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Full text of "Anatomy : descriptive and surgical"

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Boston Medical Library 
in the Francis A. Countway 
Library of Medicine -Boston 









ANATOMY 



DESCRIPTIVE AND SUEGICAL. 



Digitized by the Internet Archive 

in 2011 with funding from 

Open Knowledge Commons and Harvard Medical School 



http://www.archive.org/details/anatomydescripti1858gray 



ANATOMY 



DESCRIPTIVE AND SURGICAL. 



BY 



HENEY GRAY, F.R.S. 

LECTURER ON ANATOMY AT SAINT GEORGE'S HOSPITAL. 



THE DRAWINGS 
By H. V. CARTER, M.D. 

LATE DEMONSTRATOR OF ANATOMY AT ST. GEORGE'S HOSPITAL. 



THE DISSECTIONS 

JOINTLY BY THE AUTHOR AND DR. CARTER, 




LONDON: 

JOHN W. PARKER AND SON, WEST STRAND. 

1858. 



LONDON 
PKINTKD BV WEHTHKIMER AtiTt CO. 
FINSBUHV CIKCUS. 



TO 

SIR BENJAMIN COLLINS BRODIE, BART., 

F.R.S., D.C.L., 

SERJEANT-SURGEON TO THE QUEEN, 
CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE, 

THIS WORK IS DEDICATED, 

IN ADMIRATION OF HIS GREAT TALENTS, 

AND 

IN REMEMBRANCE OF MANY ACTS OF KINDNESS 

SHOWN TO THE AUTHOR, 

FROM AN EARLY PERIOD OF HIS PROFESSIONAL CAREER. 



PREFACE. 



rPHIS Work is intended to farnisli the Student and Practitioner with an 
accurate view of the Anatomy of the Human Body, and more espe- 
cially the application of this science to Practical Surgery. 

One of the chief objects of the Author has been, to induce the Student to 
apply his anatomical knowledge to the more practical points in Surgery, by 
introducing, in small type, under each subdivision of the work, such observa- 
tions as shew the necessity of an accurate knowledge of the part under 
examination. 

Osteology. Much time and care have been devoted to this part of the work, 
the basis of anatomical knowledge. It contains a concise description of the 
anatomy of the bones, illustrated by numerous accurately -lettered engravings, 
shewing the various markings and processes on each bone. The attachments 
of each muscle are shewn in dotted lines (after the plan recently adopted by 
Mr. Holden), copied from recent dissections. The articulations of each bone 
are shewn on a new plan ; and a method has been adopted, by which the 
hitherto complicated account of the development of the bones is made more 
simple. 

The Articulations. In this section, the various structures forming the joints 
are described ; a classification of the joints is given ; and the anatomy of each 
-carefully described : abundantly illustrated by engravings, all of which are 
taken from, or corrected by, recent dissections. 

The Muscles and Fascice. In this section, the muscles are described in 
groups, as in ordinary anatomical works. A series of illustrations, shewing the 
hues of incision necessary in the dissection of the muscles in each region, are 
introduced, and the muscles are shewn in fifty-two engravings. The Surgical 
Anatomy of the muscles in connection with fractures, of the tendons or 
muscles divided in operations, is also described and illustrated. 

The Arteries. The course, relations, and Surgical Anatomy of each artery 
are described in this section, together with the anatomy of the regions con- 
taining the arteries more especially involved in surgical operations. This part 
of the work is illustrated by twenty-seven engravings. 

The Veins are described as in ordinary anatomical works ; and illustrated 
by a series of eng-ravings, shewing those in each region. The veins of the spine 
are described and illustrated from the well-known work of Breschet. 



viii PREFACE. 

The Lymphatics are described, and figured in a series of illustrations copied 
from tlie elaborate work of Mascagni, 

The Nervous System and Organs of Sense. A concise and accurate descrip- 
tion of this important part of anatomy has been given, illustrated by seventy- 
two engravings, shewing the spinal cord and its membranes; the anatomy of the 
brain, in a series of sectional views; the origin, course, and distribution of the 
cranial, spinal, and sympathetic nerves; and the anatomy of the organs of 
sense. 

The Viscera. A detailed description of this essential part of anatomy has 
been given, illustrated by fifty large, accurately-lettered engravings. 

Regional Anatomy. The anatomy of the perinseum, of the ischio-rectal 
region, and of femoral and inguinal hernise, is described at the end of the 
work; the region of the neck, the axilla, the bend of the elbow, Scarpa's 
triangle, and the popliteal space, in the section on the arteries; the laryngo- 
tracheal region, with the anatomy of the trachea and larynx. The regions 
are illustrated by many engravings. 

Microscopical Anatomy. A brief account of the microscopical anatomy of 
some of the tissues, and of the various organs, has also been introduced. 

The Author gratefully acknowledges the great services he has derived, in 
the execution of this work, from the assistance of his friend, Dr. H.V. Carter, 
late Demonstrator of Anatomy at St. George's Hospital. All the drawings 
from which the engravings were made, were executed by him. In the majo- 
rity of cases, they have been copied from, or corrected by, recent dissections, 
made jointly by the Author and Dr. Carter. 

The Author has also to thank his friend, Mr. T. Holmes, for the able 
assistance afforded him in correcting the proof-sheets in their passage through 
the press. 

The engravings have been executed by Messrs. Butterworth and Heath ; 
and the Author cannot omit thanking these gentlemen for the great care and 
fidelity displayed in their execution. 



Wilton-Street, Belgrave-Square, 
August, 1858. 



CONTENTS. 



Osteology. 



General Properties of Bone . 
Chemical Composition of Bone 
Structure of Bone 
Form of Bones 
Vessels of Bone 
Development of Bone . 
Growth of Bone . 
The Skeleton 

The Spine. 



General Characters of the Vertebrae . 5 


Characters of the Cervical Vertebrae . 5 


Atlas 


. 6 


Axis 


. 7 


Vertebra Prominens 


. S 


Characters of the Dorsal Vertebrae 


. .8 


Peculiar Dorsal Vertebrae 


. 9 


Characters of the Lumbar Vertebrae . 10 


Structure of the Vertebrae . 


. 10 


Development of the Vertebrae 


. 11 


Atlas , 


. 12 


Axis 


. 12 


7th Cervical 


. 12 


Lumbar Vertebrae 12 


Progress of Ossification in the Spine . 12 


False Vertebrae 


. 12 


The Sacrum .... 


. 12 


The Coccyx .... 


. 16 


Development of the Coccyx 


. 17 


Of the Spine in general 


. 17 


The Skull. 




Bones of the Cranium . 


. 19 


Occipital Bone 


. 19 


Parietal Bones 


, 22 


Frontal Bone . 


, 24 


Temporal Bones 


. 27 


Sphenoid Bone 


. 32 


Sphenoidal Spongy Bones 


. 36 


Ethmoid Bone 


. 37 


Wormian Bones 


. 39 


Bones of the Face 


. 39 


Nasal Bones . 


. 39 


Superior Maxillary Bones 


. 40 


Lachrymal Bones . 


. 44 


Malar Bones . 


. 45 


Palate Bones . 


. 46 


Inferior Turbinated Bones 


. 49 


Vomer .... 


. 50 


Lower Jaw 


. 50 


Articulations of the Cranial Bone 


s . 53 


Sutures of the Skull . 


. 54 



Vertex of the Skull 

Base of the Skull, Internal Surface 

Anterior Fossa . 

Middle Fossa 

Posterior Fossa . 
Base of Skull, External Surface 
Lateral Regions of the Skull 
Temporal Fossae . 
Zygomatic Fossae . 
Spheno-masillary Fossae 
Anterior Eegion of Skull 
Orbits .... 
Nasal Fossae . . ^ . 
Os Hyoides . 

The Tliorax. 

The Sternum 

Development of the Sternum 
The Ribs .... 
Peculiar Ribs 
Costal Cartilages . 

The Pelvis. 
Os Innominatum .... 

Ilium 

Ischium 

Pubes 

Development of the Os Innominatum 
Boundaries of Pelvis 
Position of Pelvis .... 
Axes of Pelvis .... 
Differences between the Male and Fe- 
male Pelvis 

The Upper Extremities. 
The Clavicle . . . • 

The Scapula 

Development of the Scapula 

The Humerus 

Development of the Humerus 

The Ulna ' • 

The Radius 

The Hand 

The Carpus 

Bones of Upper Row 

Bones of Lower Row 

The Metacarpus 

Peculiar Metacarpal Bones . 

Phalanges 

Development of the Hand . 

The Lower Extremities. 

The Femur 

Development of the Femur . 
b 



PAGE. 

. 55 

. 55 

. 55 

. 57 

. 57 

. 58 

. 61 

. 61 

. 62 

. 62 

. 62 

. 64 

. 65 

. 67 



68 
70 
71 
73 
75 

76 

76 
79 

80 
81 
82 
83 

84 

84 

84 

86 

90 

91 

95 

97 

100 

102 

102 

103 

105 

107 

108 

109 

110 



111 
il5 



X 


CONTENTS. 






PAGE 




PACE 


The Leg .... 


. 115 


Astragalus .... 


. 125 


Patella .... 


. 116 


Scaphoid .... 


. 127 


Tibia . ... 


. 116 


Internal Cuneiform 


. 127 


Development of Tibia . 


. 120 


Middle Cuneiform 


. 128 


Fibula 


. 120 


External Cuneiform 


. 128 


Development of Fibula 


. 122 


Metatarsal Bones 


, 129 


Tbe Foot .... 


. 122 


Peculiar Metatarsal Bones . 


. 129 


Tarsus .... 


. 122 


Phalanges .... 


. 130 


Os Calcis .... 


. 122 


Development of the Foot 


. 130 


Cuboid .... 


. 124 


Sesamoid Bones . 


. 131 



Tlie Articulations. 



General Anatomy of the Joints 
Cartilage 


. 133 
. 133 


Fibro-cartilage 


. 133 


Ligament 


. 134 


Synovial Membrane 
Forms of Articulation . 


. 134 
. 135 


Synarthrosis . 

Amphiarthrosis 

Diarthrosis 


. 135 
. 136 
. 136 


Movements of Joints 


. 138 


Gliding Movement 
Angular Movement 
Circumduction 


. 138 
. 138 
. 138 


Eotation 


. 138 



Articulations of the Trunk. 

Articulations of the Vertebral Column , 138 
Atlas with the Axis 141 
Atlas with the Oc- 
cipital Bone . 143 
Axis with the Oc- 
cipital Bone . 144 
Temporo-maxillary Articulation . . 145 
Articulation of the Ribs with the Ver- 
tebrae 147 

Costo-vertebral . . . .147 
Costo-transverse . . . .148 
Costo-sternal Articulations . . .150 
Costo-xiphoid Ligaments . . .151 
Intercostal Articulations . . . 151 
Ligaments of the Sternum . . .151 



Articulation of the Pelvis with the 

Spine . . 152 
Sacrum and Ilium . 153 
Sacrum and Ischium 154 
Sacrum and Coccyx . 155 

Inter-pubic 155 

Articulations of the 'U202wr Extremity. 

Sterno-clavicular 156 

Scapulo-clavicular . . . .158 

Ligaments of the Scapula . . . 159 

Shoulder-joint 160 

Elbow-joint 161 

Radio-ulnar Articulation . . . 163 

Wrist-joint 164 

Articulations of the Cai'pus . .166 

Carpo-metacarpal Articulations . .168 
Metacarpo-phalangeal Articulations . 1 69 
Articulation of the Phalanges . .170 

Articulations of the Lower Extremity. 

Hip-joint 170 

Knee-joint ...... 172 

Articulations between the Tibia and 

Fibula 176 

Ankle-joint 178 

Articulations of the Tarsus . . . 180 
Tarso-metatarsal Articulations . .183 
Articulations of the Metatarsus . . 183 
Metatarso-phalangeal Articulations . 184 
Articulations of the Phalanges . .184 



Muscles and Fasciae. 



185 
186 



187 



General Anatomy of Muscles 
of Fasciae 

Muscles and Fascia of the Head 
AND Face. 
Subdivision into Groups 

Epicranial Region. 

Dissection 188 

Fascia of Head, Occipito-frontalis . IBS 

Auricular Region. 

Dissection 190 

AttoUens Aurem, Attrahens Aurem . 190 
Eetrahens Aurem, Actions . . . 191 

Palpebral Region. 

Dissection 191 

Orbicularis Palpebrarum . . . 191 
Corrugator Supercilii . . . .191 
Tensor Tarsi, Actions . . . .192 



Oriital Region. 

Dissection 192 

Levator Paljjebrse . . . .192 

Rectus Superior, Inferior and External 

Recti 193 

Superior Oblique 1 93 

Inferior Obhque 194 

Actions, Surgical Anatomy of . . 195 

Nasal Region. 

Pyramidalis Nasi 195 

Levator Labii Superioris Alaeque 

Nasi 195 

Dilator Naris, Anterior and Posterior . 195 

Compressor Nasi 195 

Narium Minor . . . 195 
Depressor Alae Nasi , . . .195 
Actions 195 



CONTENTS. 



Stqjerior Maxillary Regio7i. 

Levator Labii Superioris Propvius . 196 

Levator Anguli Oris . . . .196 

Zygomatici, Actions . . . .196 

Iiiferior Maxillary Region. 

Dissection 196 

Levator Labii Inferioris . . .196 
Depressor Labii Inferioris . . . 197 
Depressor Anguli Oris .... 197 

Intermaxillary Region. 

Dissection 197 

Orbiculai'is Oris 197 

Buccinator 198 

Eisorius 198 

Actions 198 

Tempero-Maxillary Region. 

Masseter 198 

Temporal Fascia ..... 199 
Dissection of Temporal Muscle . . 199 
Temporal 200 

Ptery go-Maxillary Region. 

Dissection 200 

Internal Pterygoid .... 200 
External Pterygoid .... 201 
Actions 201 

Muscles and Fasciae of the JSTeck. 

Subdivision into Groups . . . 201 

Superficial Region. 

Dissection 202 

Superficial Cervical Fascia . . . 202 

Platysma Myoides .... 202 

Deep Cervical Fascia .... 203 

Sterno-cleido-mastoid .... 204 

Boundaries of the Triangles of the Neck 204 

Actions 205 

Infra-Hyoid Region. 
Dissection .... 
Sterno-hyoid 

Sterno-thyroid, Thyro-hyoid 
Omo-hyoid, Actions 

Snpra-Iiyoid Region. 
Dissection .... 
Digastric .... 
Stylo-hyoid, Mylo-hyoid 
Genio-hyoid 
Actions .... 



. 205 
. 205 
. 206 

. 207 

. 207 
. 207 
. 208 
. 208 
. 209 

. 209 
. 209 
. 210 
. 210 
. 211 



Lingual Region. 
Dissection .... 
Genio-hyo-glossus 
Hyo-glossus, Lingualis 
Stylo-glossus, Palato-glossus 
Actions .... 

Pharyngeal Region. 

Dissection 211 

Inferior Constrictor . . . .211 
Middle Constrictor, Superior Constrictor 212 
Stylo-pharyngeus, Actions . . .212 

Palatal Region. 

Dissection 213 

Levator Palati . . . . .213 
Tensor Palati, Azygos Uvulae . . 214 
Palato-glossus, Palato-pharyngeus . 214 

Actions. Surgical Anatomy . . 215 



Vertebral Region, (Anterior). 
Eectus Capitis Anticus Major . . 215 
Rectus Capitis Anticus Minor . .215 

Eectus Lateralis 215 

Longus Colli 216 

Vertebral Region, {Lateral). 
Scalenus Anticus, Scalenus Medius . 217 
Scalenus Posticus, Actions . . .217 

Muscles and Fascia of the Trunk. 
Subdivision into Groups . . "217 

Muscles of the Bach. 
Subdivision into Layers . . 217, 218 

First Layer. 

Dissection 218 

Trapezius 218 

Ligamentum Nuchte . . . .220 
Latissimus Dorsi .... 220 

Second Layer. 

Dissection 221. 

Levator Anguli Scapulas . . . 221 

Rhomboideus Minor and Major . . 221 

Actions 222 

Third Layer. 

Dissection 222 

Serratus Posticus Superior and Inferior. 222 
Vertebral Aponeurosis . . . 222 
Splenius Capitis and Colli . . . 223 
Actions 223 

Fourth Layer. 

Dissection 223 

Erector Spin« 223 

Sacro-lumbalis 225 

MusculusAccessorius adSacro-lumbalem 225 

Cervicalis Ascendens .... 225 

Longissimus Dorsi .... 225 

Transversalis Colli .... 225 

Trachelo-mastoid .... 225 

Spinalis Dorsi, Spinalis Cervicis . . 226 

Complexus . ..... 226 

Biventer Cervicis .... 226 

Fifth Layer. 

Dissection 227 

Semispiualis Dorsi and Colli . . 227 

Multifidus Spinse .... 227 

Rotatores Spinee .... 227 

Supraspinales 227 

Interspinales 228 

Extensor Coccygis, Intertransversajes . 228 

Rectus Posticus Major and Minor . 228 

Obliquus Superior and Inferior . . 228 

Actions 229 

Muscles of the Abdomen. 
Dissection ...... 229 

Obliquus Externus .... 230 

Obhquus Internus .... 231 

Transversalis 233 

Lumbar Fascia 233 

Rectus 234 

Pyramidalis, Quadratus Lumborum , 235 
Linea Alba, Line* Semilunares . . 236 
Linese Transversa3 .... 236 

Actions . .... 236 

b 2 



CONTENTS. 



Muscles and Fasciae of the Thokax. 
Intercostal Fasciae .... 237 



Intercostales Interni et Externi 
Infracostales, Triangularis Sterni 
Levatores Costarum 
Actions .... 

Diaphragmatic Region. 
Diaphragm .... 
Actions .... 



237 

237 
238 
238 

238 
240 



Muscles and Fascia of the Upper 
Extremity. 

Subdivision into Groups , . . 241 
Dissection of Pectoral Region and Axilla 242 
Fasciifi of the Thorax , . .242 

Anterior Thoracic Region. 

Pectoralis Major 242 

Costo-coracoid Membrane . . . 244 

Pectoralis Minor 244 

Subclavius, xlctions .... 245 

Lateral Thoracic Region. 

Sei-ratus Magnus, Actions . . . 247 

Acromial Region. 

Deltoid, Action 247 

Anterior Scaimlar Region. 
Subscapular Aponeurosis . . . 247 
Subscapularis, Actions . . . 248 

Posterior Scajmlar Region. 
Supra-spinous Aponeurosis . , 248 

Supra-spinatus 248 

Infra- spinous Aponeurosis . . . 248 

Infra-spinatus 249 

Teres Minor 249 

Teres Major, Actions .... 250 

Anterior Humeral Region. 

Deep Fascia of Arm . . . . 250 

Coraco-brachialis, Biceps . . .251 

Brachialis Anticus, Actions . . 252 

Posterior Humeral Region. 

Triceps 252 

Sub-anconeus, Actions . . . 253 

Miiscles of Fore-arm. 
Deep Fascia of Fore-arm 

Anterior Brachial Region, Supo^ficial 
Layer. 
Pronator Radii Teres . 
Flexor Carpi Radialis . 
Palmaris Longus 
Flexor Carpi Ulnaris . 
Flexor Digitorum Sublimis 

Anterior Brachial Region, Beef 
Layer. 
Flexor Profundus Digitorum 
Flexor Longus Polhcis 
Pronator Quadratus 
Actions 

Radial Region. 

Dissection 

Supinator Longus 

Extensor Carpi Radialis Longior 

Extensor Carpi Radialis Brevior 



253 



254 
254 
255 
255 

255 



256 
257 

257 
258 

258 
258 
258 
259 



Posterior Brachial Region, Superficial 
Layer. 
Extensor Communis Digitorum . . 260 
Extensor Minimi Digiti . . . 260 
Extensor Carpi Ulnaris . . .260 
Anconeus 261 

Posterior Brachial Region, Beej) Layer. 
Supinator Brevis .... 261 

Extensor Ossis Metacarpi PoUicis . 261 

Extensor Primi Internodii Pollicis . 261 
Extensor Secundii Internodii Pollicis . 262 

Extensor Indicis 262 

Actions 263 

Muscles and Fascice of the Hand. 

Dissection 263 

Anterior Annular Ligament . . 263 
Posterior Annular Ligament . . 263 
Palmar Fascia 264 

Muscles of the Hand. 

Radial Group 264 

Ulnar Group 266 

Middle Palmar Group .... 267 
Actions 268 

Surgical Anatomy oj the Muscles of the 
TJ'pfer Extremity. 
Fractures of the Clavicle , . . 268 
Acromian Process . 269 
Coracoid Process . 269 
Humerus . . 269 

Ulna . . .271 

Olecranon . . 271 

Radius . . .271 
Muscles and Fascia of the Lower 
Extremity. 
Subdivision into groups . . . 273 



Iliac Region. 




Dissection .... 


. 274 


Iliac Fascia .... 


. 274 


Psoas Magnus, Psoas Parvus 


. 275 


Iliacus .... 


. 275 


Actions .... 


. 276 



Anterior Femoral Region. 

Dissection 276 

Fascise of the Thigh, Superficial Fascia . 276 
Deep Fascia (Fascia Lata) . . . 277 
Saphenous Opening .... 278 
Iliac and Pubic Portions of Fascia Lata 278 
Tensor Vagingg Femoris, Sartorius . 278 
Quadriceps Extensor Cruris . . 279 

Rectus Femoris, Vastus Exteruus . 279 
Vastus Internus and Cruraeus . . 280 
Sub-cruraeus, Actions .... 280 

Internal Femoral Region. 

Dissection 281 

Gracilis 281 

Pectineus, Adductor Longus . , 282 
Adductor Brevis, Adductor Magnus . 282 
Actions 283 

Gluteal Region. 

Dissection 283 

Gluteus Maximus . . . .283 

Gluteus Medius 284 

Gluteus Minimus .... 285 

Pyriformis, Obturator Internus, Gemelli 286 



CONTENTS. 



Quadratus Femoris, Obturator Externus 287 
Actions 287 

Posterior Femoral Region. 

Dissection 288 

Biceps, Semitendinosus . . . 288 
Semimembranosus, Actions . . 289 
Surgical Anatomy of Hamstring Ten- 
dons 289 

Muscles and Fascice of Leg. 
Dissection of Front of Leg . . . 289 
Fascia of the Leg .... 289 

Muscles of the Leg ... . 290 

Anterior Tibio-Fibular Region. 

Tibialis Anticus 290 

Extensor Proprius PoUicis . . .291 
Extensor Longus Digitorum . ,291 

Peroneus Tertius, Actions . . .291 

Posterior TiUo-Fihilar Region, Superficial 
Layer. 

Dissection 292 

Gastrocnemius . . . . .292 
Soleus, Tendo Achillis, Plantaris . . 293 
Actions 293 

Posterior Titio-Fibular Region, 
Deep Layer. 
Deep Fascia of Leg .... 294 
Popliteus, Flexor Longus PoUicis . 294 
Flexor Longus Digitorum, Tibialis Pos- 
ticus 295 

Actions 296 



Fibular Region. 
Peroneus Longus, Peroneus Brevis . 296 

Actions 297 

Surgical Anatomy of Tendons around 
Ankle 297 

Mtiscles and FascicB of Foot. 
Anterior Annular Ligament . . 297 
Internal Annular Ligament . .298 
External Annular Ligament . .298 
Plantar Fascia 298 

Muscles of the Foot, Dorsal Region. 
Extensor Brevis Digitorum . . 299 



Plantar Region. 




Subdivision into Groups 


. 299 


Subdivision into Layers 


. 299 


First Layer 


. 299 


Second Layer 


. 301 


Third Layer 


. 302 


Interossei .... 


. 303 



Surgical Anatomy of the Ifuscles of the 
Lower Extremity. 
Fracture of the Neck of the Femur . 304 
the Femur below Trochanter 

Minor . . .304 

the Femur above the Con- 
dyles .... 305 
the Patella . . .305 

the Tibia . . . .305 
the Fibula, with Dislocation 

of the Tibia . . 306 



The Arteries. 



General Anatomy. 
Subdivision into Pulmonary and Sys- 
temic 307 

Distribution of — Where found . . 307 
Mode of Division — Anastomoses . 307 
Capillaries — Structure of Arteries . 308 
Sheath — Vasa Vasorum . . . 308 

Aorta. 

Arch of Aorta 310 

Dissection 310 

Ascending Part of Arch . . . 310 
Transverse Part of Arch . . .311 
Descending Part of Arch . . . 311 
Peculiarities, Surgical Anatomy . .312 

Branches 313 

Peculiarities of Branches . . . 313 

Coronary Arteries . . , .313 
Arteria Lnnominata. 

Relations 314 

Peculiarities, Surgical Anatomy . 314 

Common Carotid Arteries. 
Course and Relations . . . .315 
Peculiarities, Surgical Anatomy . 317, 318 

External Carotid Artery. 

Relations 318 

Surgical Anatomy .... 319 
Branches 319 



Superior Tliyroid Artery. 
Course and Relations . 
Surgical Anatomy 


. 320 
. 320 


Lingual Artery. 
Course and Relations . 

Branches 

Surgical Anatomy , . . . 


. 320 
. 321 
. 321 


Facial Artery. 
Course and Relations . 

Branches 

Peculiarities .... 
Surgical Anatomy 


. 321 
. 322 
. 323 
. 324 


Occipital Artery. 
Course and Relations . 
Branches 


. 324 

. 324 


Posterior Auricular Artery 


. 324 


Ascending Pharyngeal Artery . 


. 325 


Temporal Artery. 
Course and Relations . 
Branches, Surgical Anatomy 


. 325 
. 326 


Internal Maxillary Artery. 
Course, Relations 
Pecuharities .... 
Branches from First Portion 
Second Portion 
Third Portion 


. 326 
. 327 
. 327 
. 328 
. 329 



CONTENTS. 



Surgical Anatomy of the Tbiangles 
OF THE Neck. 



Anterior Triangular Space. 
Inferior Carotid Triangle 
Superior Carotid Triangle 
Submaxillary Triangle 

Posterior Triangular Space. 
Occipital Triangle 
Subclavian Triangle 

Internal Carotid Artery. 
Cervical Portion 
Petrous Portion 
Cavernous Portion 
Cerebral Portion 
Peculiarities, Surgical Anatomy 
Branches .... 



330 
330 
331 



331 
332 



332 

333 

334 

334 

334' 

334 

Ophthalmic Artery . . . 334 

Cerebral Branches of Internal Carotid 338 

Subclavian Arteries. 
First Part of Eight Subclavian Artery . 339 
First Part of Left Subclavian Artery . 339 
Second Part of Subclavian Artery . 340 
Third Part of Subclavian Artery . 341 

Peculiarities, Surgical Anatomy . 341 

Branches 342 

Vertebral Artery .... 343 
Basilar Artery .... 344 
Spinal Branches of Vertebral . 344 
Cerebral Branches of Vertebral . 344 
Cerebellar Branches of Vertebral . 344 

. 345 
. 345 
. 345 
. 346 
. 346 
. 347 
. 347 

. 348 

. 349 
. 350 
. 350 
. 351 
. 351 

. 352 

. 354 

. 364 

. 354 

. 355 

. 357 
. 358 
. 358 
. 358 



Circle of Willis 
Thyroid Axis . 
Supra-scapular Artery 
Transversalis Colli . 
Internal Mammary 
Superior Intercostal 
Deep Cervical Artery 



Surgical Anatomy of the Axilla 

Axillary Artery. 
First Portion 
Second Portion 
Third Portion 

Peculiarities, Surgical Anatomy 
Branches .... 

Brachial Artery. 
Eelations .... 
Bend of the Elbow 
Peculiarities of Brachial Artery 
Surgical Anatomy 
Branches .... 

Radial Artery. 
Relations .... 
Deep Palmar Arch 
Peculiarities, Surgical Anatomy 
Branches .... 



TJlnar Artery. 
Relations .... 
Superficial Palmar Arch 
Peculiarities of Ulnar Artery 
Surgical Anatomy 
Branches .... 

Descending Aorta 



. 360 
. 361 
. 361 
. 361 
. 361 

. 363 



['horacic Aorta. 



Relations 
Surgical Anatomy 
Branches 



. 363 
. 364 
. 364 



Abdominal Aorta. 

Relations .... 
Surgical Anatomy 
Branches .... 

Coeliac Axis, Gastric Artery 

Hepatic Artery, Branches 

Splenic Artery 

Superior Mesenteric Artery 

Inferior Mesenteric Artery 

Supra-renal Arteries 

Renal Arteries 

Spermatic Arteries 

Phrenic Arteries 

Lumbar Arteries . 

Middle Sacral Artery 

Common Iliac Arteries. 

Course and Relations . 
Peculiarities, Surgical Anatomy . 

Internal Iliac Artery. 
Course and Eelations . 
Peculiarities, Surgical Anatomy 
Branches .... 

Vesical Arteries 

Hsemorrhoidal Arteries . 

Uterine and Vaginal Arteries. 

Obturator Artery . 

Internal Pudic Artery 

Sciatic Artery. 

Gluteal, Ilio-lumbar, and Lateral 
Sacral Arteries .... 

External Iliac Artery. 



366 
367 
367 
367 
368 
369 
370 
372 
373 
373 
373 
374 
374 
375 



375 
376 



377 
377 
378 
378 
378 
378 
378 
379 
381 

382 



Course and Eelations . 


. 382 


Surgical Anatomy 


. 383 


Epigastric Artery 


. 383 


Circumflex Iliac Artery 


. 384 


Femoral Artery. 




Course and Eelations . 


. 384 


Scarpa's Triangle 


. 384 


Peculiarities of Femoral Artery 


. 386 


Surgical Anatomy 


. 386 


Branches .... 


. 387 


Profunda Artery 


. 387 


Popliteal Space 


. 389 


Popliteal Artery. 




Course and Eelations . 


. 390 


Peculiarities, Surgical Anatomy 


. 390 


Branches .... 


. 391 


Anterior Tibial Artery. 




Course and Eelations . 


. 392 


Peculiarities, Surgical Anatomy 


. 393 


Branches .... 


. 393 


Borsalis Pedis Artery. 




Course and Eelations . 


. 394 


Peculiarities, Surgical Anatomy 


. 394 


Branches 


. 394 



CONTENTS. 



Posterior Tibial Artery. 

Course and Eelations .... 395 
Peculiarities, Surgical Anatomy . .396 
Branches .■ . . . . 396 



Peroneal Artery. 
Course and Eelations .... 396 

Peculiarities 397 

Plantar Arteries . , . .397 
Pulmonary Artery .... 399 



The Yeins. 



General Anatomy. 

Subdivision into Pulmonary, Systemic, 

and Portal 400 

Anastomoses of Veins .... 400 
Superficial Veins, Deep Veins, or Vense 

Comites 400 

Sinuses, their Structure . . . 400 
Structure of Veins . . . .401 

Coats of Veins 401 

Valves of Veins 401 

Vessels and Nerves of Veins , .401 

Veins of the Head and Neck. 

Facial Vein 402 

Temporal Vein 403 

Internal Maxillary Vein . , . 403 
Temporo-maxillary Vein . . .403 
Posterior Auricular Vein, Occipital Vein 404 

Veins of the Nech. 
External Jugular Vein . . . 404 

Posterior External Jugular Vein . 404 

Anterior Jugular Vein . . . 404 

Internal Jugular Vein . . . 405 

Lingual, Pharyngeal, and Thyroid Veins 405 

Veins of the Diploe .... 405 

Cerebral Veins. 
Superficial Cerebral Veins . . .406 
Deep Cerebral Veins . . . 407 

Cerebellar Veins .... 407 

Sinuses of the Dura Mater. 

Superior Longitudinal Sinus . . 407 

Inferior Longitudinal, Straight, Lateral, 

and Occipital Sinuses . . . 408 
Cavernous Sinuses .... 408 
Circular, Inferior Petrosal, and Trans- 
verse Sinuses 409 

Superior Petrosal Sinus . . . 410 



Veins op the Upper Extreihty. 

Superficial Veins .... 410 

Deep Veins 411 

Axillary Vein 412 

Subclavian Vein 412 

Vertebral Vein 412 

Innominate Veins . . . .412 

Peculiarities of .... 413 

Internal Mammary Vein . . . 414 
Inferior Thyroid Veins . . . 414 

Superior Intercostal Veins . . .414 
Superior Vena Cava .... 414 

Azygos Veins 414 

Spinal Veins 415 

Veins of the Lower Extremity. 

Internal Saphenous Vein . . .417 
External Saphenous Vein . . .418 

Popliteal Vein 418 

Femoral Vein 418 

External Iliac Vein , . . . 419 
Internal Iliac Vein . . . .419 
Common Iliac Vein .... 419 
Inferior Vena Cava .... 420 
Peculiarities .... 420 
Lumbar and Spermatic Veins . . 420 
Ovarian, Renal, Supra-renal Veins . 421 
Phrenic Veins, Hepatic Veins . .421 

Portal System of Veins. 

Inferior and Superior Mesenteric Veins 421 
Splenic and Gastric Veins . . 422 
Portal Vein 423 

Cardiac Veins. 
Coronary Sinus 423 

Pulmonary Veins .... 424 



The Lymphatics. 



General Anatomy. 
Structure of, where found . . ' . 425 
Subdivision into Deep and Superficial . 425 
Coats of Lymphatics .... 425 
Valves of Lymphatics . . . 426 

Lymphatic or Conglobate Glands . 426 

Structure of Lymphatic Glands . 426 

Thoracic Duct 426 

Eight Lymphatic Duct . . . 428 

Lymphatics of Head, Face, and Neck. 
Superficial Lymphatic Glands of Head 428 
Lymphatics of Head . 428 

of the Face . 428 



Deep Lymphatics of the Face . . 428 
of the Cranium . 428 
Lymphatic Glands of the Neck . . 429 
Superficial Cervical Glands . . 429 
Deep Cervical Glands . . . 429 
Superficial and Deep Cervical Lym- 
phatics 429 

Lymphatics of the Upper Extremity. 
Superficial Lymphatic Glands . . 430 
Deep Lymphatic Glands . . . 430 

Axillary Glands 430 

Superficial Lymphatics of Upper Ex- 
tremity 431 

Deep Lymphatics of Upper Extremity , 432 



CONTENTS. 



Lymphatics of the Lower Extremity. 

Superficial Inguinal Glands . . 432 

Deep Lymphatic Glands . . . 433 
Anterior Tibial Gland . . .433 

Deep Popliteal Glands . . . 433 

Deep Inguinal Glands . . . 433 

Gluteal and Ischiatic Glands . . 433 
Superficial Lymphatics of Lower Ex- 
tremity ..... 433 
Internal Group .... 433 
External Group . . . .433 
Deep Lymphatics of Lower Extremity . 433 

Lymphatics of Pelvis and Abdomen. 
Deep Lymphatic Glands of Pelvis . 434 
External Iliac Glands . . . 434 
Internal Iliac Glands . . . 434 
Sacral Glands .... 435 
Lumbar Glands .... 435 
Lymphatics of Pelvis and Abdomen . 435 
Superficial Lymphatics of Wall of Ab- 
domen . . 435 
of Gluteal Region . .435 
of Scrotum and Perineeum 435 
of Penis . . .435 
of Labia, Nymphse, and 

Chtoris . . 435 
Deep Lymphatics of Pelvis and Ab- 
domen 435 



Lymphatics of Bladder 
of Eectum 
of Uterus 
of Testicle 



435 
435 
435 
436 



Lymphatics of Kidney 


PAGE 

. 436 


of Liver 


. 436 


Lymphatic Glands of Stomach 


. 436 


Lymphatics of Stomach 


. 436 


Lymphatic Glands of Spleen 


. 437 


Lymphatics of Spleen 


. 437 



Lymphatic System of the Intestines. 

Lymphatic Glands of Small Intestines 

(Mesenteric Glands) . . . 437 

Lymphatic Glands of Large Intestine . 437 

Lymphatics of Small Intestine (Lacteals) 437 

of Great Intestine . .437 

Lymphatics of Thorax. 



Deep Lymphatic Glands of Thorax , 437 


Intercostal Glands 


. 437 


Internal Mammary Glands 


. 437 


Anterior Mediastinal Glands 


. 437 


Posterior Mediastinal Glands 


. 437 


Superficial Lymphatics on. Eront of 


Thorax .... 


. 437 


Deep Lymphatics of Thorax 


. 437 


Intercostal Lymphatics 


. 437 


Internal Mammary Lymphatics 


. 438 


Lymphatics of Diaphragm . 


. 438 


Bronchial Glands 


. 438 


Lymphatics of Lung . 


. 438 


Cardiac Lymphatics 


. 438 


Thymic Lymphatics 


. 438 


Thyroid Lymphatics 


. 438 


Lymphatics of Oesophagus . 


. 438 



Nervous System. 



Oeneral Anatomy. 
Subdivision into Cerebro-spinal Axis, 
Ganglia, and Nerves . . . 439 



Cerehro-Spinal Axis. 
Grey Substance 
White Substance 
Chemical Composition 



Where found. 



Ganglia. 
Structure 



439 
439 
439 



440 



Nerves. 
Subdivision into Afferent, Efferent, and 

Excito-motory .... 440 

Cerebro-spinal Nerves . . . 440 

Sympathetic Nerve . . . . 442 

The Sinnal Cord and its Membranes. 

Dissection 442 

442 
443 
443 
444 
444 
445 
445 
446 
446 



Membranes of the Cord 

Dura Mater . 

Arachnoid . 

Pia Mater 

Ligamentum Denticulat 
Spinal Cord 

Fissures of Cord 

Columns of Cord 

Grey Matter of Cord 



Mode of Arrangement of Grey and 

White Matter .... 446 
White Matter of Cord . , ." 447 



The Brain and its Membranes. 
Membranes of the Brain 

Dura Mater. 

Structure ..... 

Arteries, Veins, Nerves 

Glandulse Pacchioni 

Processes of the Dura Mater 
Ealx Cerebri 
Tentorium Cerebelli 
Falx Cerebelli 

Arachnoid Membrane. 
Sub-arachnoid Space . 
Cerebro-spinal Fluid . 

Pia Mater .... 



447 

448 
448 
448 
448 
448 
448 
449 

449 
449 

450 



The Brain. 
Subdivision into Cerebrum, Cerebellum, 

Pons Varolii, Medulla Oblongata . 450 
Weight of Brain . . . .450 

■ Medulla Oblongata. 

Anterior Pyramids . . . .451 

Lateral Tract, and Olivary Body . 452 

Restiform Bodies .... 452 

Posterior Pyramids .... 452 

Posterior Surface of Medulla Oblongata 452 

Structure of Medulla Oblongata . . 452 

of Anterior Pyramid . . 452 

of Lateral Tract . . 453 

of Olivary Body . . 453 

of Restiform Body . . 453 

Septum of Medulla Oblongata . . 454 

Grey Matter of Medulla Oblongata . 454 



CONTENTS. 



Pons Varolii. 

Structure 454 

Transverse Fibres .... 454 
Longitudinal Fibres .... 455 
Septum 455 

Cerebrum. 

Upper Surface of Cerebrum . . . 455 
Convolutions and Sulci . . . 455 

Base of the Brain . . . .457 

General Arrangement of the Parts 

composing the Cerebrum . . 460 

Interior of the Cerebrum . . . 460 

Corpus Callosum .... 461 

Lateral Ventricles .... 463 

Boundaries of, and Parts forming the 

Lateral Ventricles .... 463 

Septum Lucidum . . . 465 

Fornix 466 

Velum Interpositum . . . 466 
Thalami Optici . . . .467 
Third Ventricle . . . .468 
Anterior, Middle, and Posterior Com- 
missures ..... 468 
Grey Matter of Third Ventricle . . 468 

Pineal Gland 468 

Corpora Quadrigemina . . . 469 

Valve of Vieusseus .... 469 
Corpora Geniculata .... 469 
Structure of Cerebrum . . . 469 

1. Diverging or Peduncular Fibres . 470 

2. Transverse Commissural Fibres . 470 

3. LongitudinalCommissural Fibres . 470 

Cerebellum. 

Its Position, Size, Weight, etc. . . 470 

Cerebellum, Upper Surface . . 471 

Under Surface . . 471 

Lobes of the Cerebellum . . . 472 

Fourth Ventricle 472 

Boundaries of Ventricle . . . 472 

Lining Membrane, Choroid Plexus of . 473 

Grey Matter of 473 

Structure of the Cerebellum . . 473 

Its Laminae 473 

Corpus Dentatum .... 473 
Peduncles of Cerebellum . . . 474 

Cranial Nerves. 

Subdivision into Groups . . . 475 

Nerves of Special Sense . . 475 

of Motion . . .475 

Compound Nerves . . . 475 

Nerves of Special Sense. 

Olfactory Nerve 475 

Optic Nerve 476 

Tracts 476 

Commissure . . . .477 
Auditory Nerve 477 

Motor Cranial Nerves. 

Third Nerve (Motor Oculi) . . .477 

Fourth Nerve (Trochlearis) . . . 478 

Sixth Nerve (Abducens) . . . 479 
Relations of the Orbital Nerves 

in the Cavernous Sinus . . 479 

in the Sphenoidal Fissure . . 479 

in the Orbit 479 



Facial Nerve 

Branches of Facial Nerve 
Ninth or Hypo-glossal Nerve 

Compound Cranial Nerves. 

Fifth Nerve 

Gaserian Ganglion . . . . 

Ophthalmic Nerve . . . . 
Lachrymal, Frontal, and Nasal Branches 
Ophthalmic Ganglion . . . . 
Superior Maxillary Nerve 
Spheno-palatine Ganglion 
Inferior Maxillary Nerve 
Auriculo-temporal, Gustatory, and In 



ferior Dental Branches 

Otic Ganglion 

Sub-maxillary Ganglion 

Eighth Pair 

Giosso-pharyngeal 
Spinal Accessory 
Pneumogastric (Vagus) 



492, 



PAGE 

480 
481 
483 



485 
485 
485 
486 
487 
487 
489 
491 

493 
493 
494 
494 
494 
496 
497 



Spinal Nerves. 

Roots of the Spinal Nerves . . 501 

Origin of Anterior Roots . . 501 
of Posterior Roots . . 501 
Ganglia of the Spinal Nerves . . 501 
Anterior Branches of the Spinal Nerves 502 
Posterior Branches of the Spinal Nerves 502 

Cervical Nerves. 

Roots of the Cervical Nerves . .502 
AnteriorBranchesof theCervicalNerves 502 

Cervical Plexus. 

Superficial Branches of the Cervical 

Plexus 503 

Deep Branches of the Cervical Plexus . 505 
Posterior Branches of the Cervical 
Nerves 505 



Brachial Plexus. 
Branches above the Clavicle. 
Posterior Thoracic, Supra Scapular 
Branches below the Clavicle. 
Anterior Thoracic, and Subscapular 

Nerves 

Circumflex, and Musculo-cutaneous 

Nerves 

Internal, and Lesser Internal Cutaneous 

Nerves 

Median Nerve 

Ulnar Nerve 

Musculo-spiral Nerve .... 
Radial Nerve . . . 
Posterior Interosseous Nerve 



508 



508 

509 

510 
511 

513 
514 
515 
515 



Dorsal Nerves. 

Roots of the Dorsal Nerves . . . 516 
Posterior Branches of the Dorsal Nerves 516 
Intercostal Nerves . . . .516 



Upper Intercostal Nerves 
Intercosto-humeral Nerve 
Lower Intercostal Nerves 
Peculiar Dorsal Nerves 
First Dorsal Nerve 
Last Dorsal Nerve 



616 
517 

517 
517 
517 
517 



XVlll 



CONTENTS. 



Lumbar Nerves. 

Roots of Lumbar Nerves . . .518 
Posterior Branches of Lumbar Nerves . 518 
Anterior Branches of Lumbar Nerves . 518 

Lumbar Plexus. 

Branches of Lumbar Plexus . .519 

Ilio-hypogastric Nerve . . . 519 

Ilio-inguinal, and Geuito-crural Nerves 520 
External Cutaneous, and Obturator 
Nerves ...... 520 

Accessory Obturator Nerve . .522 

Anterior Crural Nerve . . .522 

Branches of Anterior Crural . . 522 

Middle Cutaneous .... 523 

Internal Cutaneous, Long Saphenous . 523 
Muscular and Articular Branches . 524 

Sacral and Coccygeal Nerves. 

Boots of, Origin of .... 524 

Posterior Sacral Nerves . . . 524 

Anterior Sacral Nerves . . . 524 

Posterior Branch of Coccygeal Nei've . 524 

Anterior Branch of Coccygeal Nerve . 525 

Sacral Plexus. 

Superior Gluteal Nerve . . . 525 

Pudic, and Small Sciatic Nerves . 526 

Great Sciatic Nerve .... 528 
Internal Popliteal Nerve . ■ . . 528 
Posterior Tibial Nerve . . . 529 

Plantar Nerves 529 

External Popliteal or Peroneal Nerve . 530 
Anterior Tibial Nerve . . . 530 

Musculo-cutaneous Nerve . . . 530 



Sympathetic Nerve. 
Subdivision of, into Parts . . . 532 
Branches of the Ganglia, General De- 
scription of .... . 532 

Cervical Portion of the Sympathetic. 

Superior Cervical Ganglion. 

Carotid and Cavernous Plexuses . 534 

Middle Cervical Ganglion . . 535 

Inferior Cervical Ganglion. . . 535 
Cardiac Nerves. 
Superior, Middle, and Inferior Cardiac 

Nerves 536 

Deep Cardiac Plexus .... 536 
Superficial Cardiac Plexus . . . 537 
Anterior and Posterior Coronary Plexus 537 

Thoracic Part of the Sympathetic. 
Great Splanchnic Nerve . . . 537 
Lesser Splanchnic Nerve . . . 538 
Smallest Splanchnic Nerve . . . 538 
Epigastric or Solar Plexus . . . 538 
Semilunar Ganglia .... 638 
Phrenic, Supra-renal, and Eenal Plexuses 538 
Spermatic, Coeliac, and Gastric Plexuses 539 
Hepatic, Splenic, and Superior Mesen- 
teric Plexuses 539 

Aortic, and Inferior Mesenteric Plexuses 539 

Lumbar Portion of Sympathetic. 540 
Pelvic Portion of Sympathetic . . 540 
Hypogastric Plexus .... 540 
Inferior Hypogastric or Pelvic Plexus . 540 
Inferior Hsemorrhoidal Plexus . . 540 

Vesical Plexus 540 

Prostatic Plexus 541 

Vaginal Plexus 541 

Uterine Nerves 541 



Organs of Sense. 



Skin. 

Derma, or True Skin .... 542 

Corium ..... 543 

Papillary Layer .... 543 

Epidermis or Cuticle . . . 543 

Vessels and Nerves of the Skin . 544 

Appendages op the Skin. 

Nails , 545 

Hairs 645 

Sebaceous and Sudoriferous Glands . 546 

Tongue. 

Papillse of. Structure of Papillae . 548, 549 

Folhcles, and Mucous Glands . , 549 

Fibrous Septum of ... . 549 

Muscular Fibres of . . . .549 

Arteries and Nerves of . . .550 

Nose. 

Cartilages of, Muscles .... 551 

Skin, Mucous Membrane . . . 552 

Arteries, Veins, and Nerves . . 552 



Nasal Fossce. 
Mucous Membrane of . . . . 552 
Peculiarities of, in Superior, Middle, 

and Inferior Meatuses . . 552, 553 
Arteries, Veins, and Nerves of Nasal 

Fossse 553 

Eye. 
Situation, Form of ... - 553 
Tunics of. Sclerotic .... 554 
Cornea, Structure of Cornea . . 555 

Choroid, Structure of Choroid . .557 
Ciliary Processes, Iris . . . 558 

Membrana Pupillaris, Ciliary Ligament 559 

Ciliary Muscle 559 

Retina 559 

Structure of Retina .... 560 
Jacob's Membrane . . . 560 

Granular Layer . . . .561 
Nervous Layer .... 561 
Radiating Fibres of the Retina . 561 
Arteria Centralis Retinae . . .561 
Structure of Retina, at Yellow Spot . 561 



CONTENTS. 



Humours of the Eye. 

Aqueous Humour .... 561 

Anterior Chamber . . .561 

Posterior Chamber . . . 562 

Vitreous Body 562 

Crystalhne Leus and its Capsule . 562 

Changes produced in the Lens by Age . 563 
Suspensory Ligament of Lens . .563 

Canal of Petit 563 

Vessels of the Globe of the Eye . 563 

Arteries, Veins, and Nerves of Eyeball . 564 

Appendages of the Ete. 

Eyebrows 564 

Eyehds 564 

Structure of the Eyelids . . . 564 
Tarsal Cartilages . . . .564 

Meibomian Glands . . . .565 

Eyelashes 565 

Conjunctiva, and Caruncula Lachry- 
malis 566 

Lachrymal Apparatus . 566 

Lachrymal Gland . . . .667 
Canals . . . .567 
Sac 567 

Nasal Duct 567 

Ear. 
Pinna or Auricle .... 567 

Structure of Auricle .... 568 
Ligaments of the Pinna . . . 668 



PAGE 

Muscles of the Pinna .... 669 
Arteries, Veins, and Nerves of the Pinna 570 
Auditory Canal 570 

Middle Ear or Tympanum. 

Eustachian Tube .... 573 

Membrana Tympani .... 573 

Structure of 573 

Ossicles of the Tympanum . . . 574 
Ligaments of the Ossicula . . . 574 
Muscles of the Tympanum . . 575 
Mucous Membrane of Tympanum . 575 
Arteries, Veins, and Nerves of Tym- 
panum 576 

Internal Ear or Labyrinth. 

Vestibule 576 

Semicircular Canals .... 577 
Superior Semicircular Canal . 577 

Posterior Semicircular Canal . 577 

External Semicircular Canal . 578 

Cochlea 578 

Central Axis of, or Modiolus . 578 

Spiral Canal of ... . 578 

Lamina Spiralis of . . .579 

Scala Tympani, Scala Vestibuli . . 579 

Membranous Labyrinth . . . 580 

Utricle and Sacculus .... 580 

Membranous Semicircular Canals . 580 

Vessels of the Labyrinth . . .681 

Auditory Nerve, Vestibular Nerve, 

Cochlear Nerve .... 581 



VISCERA. 



Organs of Digestion and their Appendages. 



Alimentary Canal . . . .682 

Its Subdivisions .... 682 

The Mouth 682 

The Lips . . . . . .582 

The Cheeks 683 

The Gums 583 

Teeth. 
General Characters of ... 584 

Permanent Teeth ..... 686 
Incisors, Canine, Bicuspid, Molars . 585 

Temporary or Milk Teeth . . .586 
Structure of the Teeth . . . 687 
Ivory or Dentine, Chemical Composition 687 
Enamel, Cortical Substance . . 588 

Development of the Teeth . . 688 

of the Permanent Teeth . 690 
Growth of the Teeth . . .690 

Eruption of the Teeth . . .590 

Palate. 

Hai*d Palate 591 

Soft Palate 591 

Uvula, Pillars of the Soft Palate . 592 

Mucous Membrane, Aponeurosis, and 
Muscles of Soft Palate . . .692 



To7isils. 
Arteries, Veins, and Nerves of Tonsils . 



Salivary Glands. 
Parotid Gland, 
Steno's Duct .... 

Vessels and Nerves of Parotid Gland 



593 
694 



Suhmaonllary Gland. 
"Wharton's Duct . . . .594 
Vessels and Nerves of Submaxillary 
Gland 594 

tSuhlingual Gland. 
Vessels and Nerves of ... 694 

Structure of Salivary Glands . . 594 

Pharynx. 
Structure of ..... 595 

CEsophagus . . . . .595 

Relations, Surgical Anatomy, and Struc- 
ture of ..... . 596 



592 



Abdomen. 
Boundaries 
Apertures of. Regions . 

Peritoneum. 
Reflections traced . 
Foramen of Winslow . 
Lesser Omentum . 
Great Omentum . 



597 

597 



599, 600 
. 600 
. 601 
. 601 



CONTENTS. 



PAGB. 

Gastro-splenic Omentum . . . 601 

Mesentery 601 

Mesocsecum, Mesocolon . . . 602 

Siomach. 

Situation 602 

Splenic end, Pyloric end . . . 602 

Cardiac and Pyloric Orifices . . . 602 

Greater and Lesser curvatures . . 602 

Surfaces 603 

Ligaments of . . . . • 603 

Alterations in Position .... 603 

Pylorus 604 

Structure of Stomach .... 604 

Serous and Muscular Coats . . . 604 

Mucous Membrane .... 605 

Gastric Follicles 605 

Vessels and Nerves of Stomach . .606 

Small Intestines. 

Duodenum 606 

Ascending portion .... 606 

Descending portion . . . 606 

Transverse portion . . . 606 

Vessels and Nerves of Duodenum . 607 

Jejunum 607 

Ileum 607 

607 
607 
607 
607 
608 
608 
608 



Structure of Small Intestines 

Serous, Muscular and Cellular Coats 

Mucous Membrane 

Epithelium and Valvulse Conniventes 

Villi — their Structure . 

Simple Follicles, Duodenal Glands 

Solitary Glands, Aggregate Glands 

Large Intestine. 
Csecum .... 

Appendix Ceeci Vermiformis 

Ileo-cEecal Valve 
Colon 

Ascending 

Transverse 

Descending 

Sigmoid Flexure . 
Eectum ... 

Upper Portion 

Middle Portion 

Lower Portion 
Structure of Large Intestine 
Serous and Muscular Coats . 
Cellular and Mucous Coats . 
Epithelium, Simple Follicles and 
tary Glands of Large Intestine 



Soli- 



609 
609 
610 
611 
611 
611 
611 
611 
611 
612 
612 
612 
612 
612 
613 

613 



Liver. 

Size, weight, position of 
Its Surfaces and Borders 
Changes of Position 

Ligaments. 

Longitudinal, Lateral, Coronary . 
Eound Ligament .... 

Fissures. 

Longitudinal 6] 5 

Fissure of Ductus Venosus, Portal 

Fissure 615 

Fissures for Gall Bladder and Vena 

Cava 616 



613 
614 
614 



614 
615 



Lobes. 






Eight, Left .... 




616 


Quadratus, Spigelii, Caudatus 




617 


Vessels of Liver . 




617 


Lymphatics, Nerves 




617 


Structure of Liver 




617 


Serous and Fibrous Coats 




617 


Lobules 




617 


Hepatic Cells, Biliary Ducts, 


Portai 




Vein .... 




618 


Hepatic Artery, Hepatic Veins 


619 



Gall Bladder. 

Structure 620 

BiHary Ducts 620 

Hepatic, Cystic, and Common Cho- 

ledic Ducts 620 

Structure of Biliary Ducts . . 621 

Pancreas. 

Dissection 621 

Relations 621 

Duct. Structure . . . .622 

Vessels and Nerves .... 623 

Spleen. 

Eelations 623 

Size and Weight 623 

Structure of Serous and Fibrous Coats 623 
Propef Substance . . . .624 

Malpighian Corpuscles . . . 625 

Splenic Artery, distribution . . . 625 
Capillaries of Spleen .... 627 

Veins of Spleen 627 

Lymphatics and Nerves . . .627 

THOEAX. 

Boundaries of 628 

Superior Opening, Base . . . 628 

Parts passing through Upper Opening 628 

Pericardium. 



Structure . . 
Fibrous layer. Serous Layer 



629 
629 



Heart. 

Position, Size 629 

Subdivision into Four Cavities . .629 
Circulation of Blood in Adult . . 629 
Auriculo-ventricular, and Ventricular 
Grooves 630 



Right Auricle. 




Openings .... 
Valves .... 
Eelics of Foetal Structure 
Musculi Pectinati . 


. 631 
. 631 
. 632 
. 632 



Right Ventricle. 

Openings 632 

Tricuspid and Semilunar Valves . . 633 
Chordse Tendineae and Columnse Carneas 633 

Le,ft Auricle. 
Sinus and Appendix .... 634 
Openings, Musculi Pectinati . . 634 

Jjcft Ventricle. 

Openings 635 

Mitral and Semilunar Valves . . 635 

Endocardium ..... 635 



CONTENTS. 



Structure of Heart. 




Fibrous Rings 


. 636 


Muscular Structure 


. 636 


of Auricles . 


. 636 


of Ventricles 


. 636 


Vessels and Nerves of Heart 


. 637 



Peculiarities in Vascular System of 

Foetus 637 

Foramen Ovale, Eustachian Valve . 637 

Ductus Arteriosus .... 638 

Umbilical or Hypogastric Arteries . 639 

Foetal Circulation 639 

Changes in Vascular System at Birth . 640 



Organs of Voice and Respiration. 



The Larynx. 
Cartilages of the Larynx . . . 641 
Thyroid Cartilage . . . .641 
Cricoid and Arytenoid Cartilages . 642 
Cartilages of Santorini, and Wris- 

berg 643 

Epiglottis. Its structure . . 643 
Ligaments of the Larynx . . . 643 
Ligaments connecting the Thyroid 

Cartilage with the Os Hyoides . 643 

Ligaments connecting the Thyroid Car- 
tilage with the Cricoid . . . 644 
Ligaments connecting the Arytenoid 

Cartilages to the Cricoid . . . 644 
Ligaments of the Epiglottis . . 644 

Interior of the Larynx . . ,644 

Cavity of the Larynx .... 644 

Glottis 644 

False Vocal Cords . . . .645 

True Vocal Cords . . . .645 

Ventricle of Larynx, Sacculus Laryngis 646 



Muscles of Larynx 

Crico-thyroid .... 

Crico-arytsenoideus posticus . 
lateralis . 

Th yro-arytsenoideus 

Muscles of the Epiglottis 

Thyro-epiglottideus 

Arytseno-epiglottideus, superior 
inferior 
Actions of Muscles of Larynx 
Mucous Membrane of Larynx 
Glands, Vessels and Nerves of 



Trachea. 



Eelations 
Bronchi 



646 
646 
646 
646 
646 
647 
647 
647 
647 
647 
648 
648 

648 
649 



Structure of Trachea .... 650 
Surgical Anatomy of Laryngo-tracheal 
Region 651 

The Pleurce. 

Reflections 653 

Vessels and Nerves . . . .653 

Mediastinum. 
Anterior Mediastinum . . . .653 
Middle Mediastinum .... 654 
Posterior Mediastinum .... 654 

The Lungs. 

Surfaces, Lobes 655 

Root of Lung 655 

Weight, Colour, and Properties of Sub- 
stance of Lung 656 

Structure of Lung . , . .656 

Serous Coat, and Subserous Areolar 

Tissue 656 

Parenchyma and Lobules of Lung . 656 

Bronchi, arrangement of Branches in 

Substance of Lung .... 656 
Structure of smaller Bronchial Tubes . 656 



The Air Cells 
Pulmonary Artery 
Pulmonary Capillaries and Veins 
Bronchial Arteries and Veins 
Lymphatics and Nerves of Lung 

Thyroid Gland. 
Structure .... 
Vessels and Nerves 
Chemical Composition . 

Thymus Qland. 
Structure .... 
Vessels and Nerves 
Chemical Composition 



657 
657 
657 
657 
657 

658 
659 
659 

659 
658 
659 



The Urinary Organs. 



Kidneys. 
Relations .... 
Dimensions, Weight 
Cortical Substance 
Medullary Substance 
Minute Structure 
Malpighian Bodies 
Ureter, Pelvis, Infundibula . 
Renal Artery, Renal Veins . 
Lymphatics and Nerves 

Ureters. 
Situation, Course, Relations . 
Structure .... 



Relations 



Swpra^Renal Capsules. 



660 
660 
660 
661 
661 
662 
662 
662 
663 

663 
663 

664 



Structure 

Vessels and Nerves 

Pelvis. 
Boundaries and Contents 

Bladder. 
Shape, Position, Relations 

Subdivisions . 

Ligaments 

Structure 
Interior of Bladder 
Vessels and Nerves 



Male Urethra. 



Structure 



664 
664 



665 



665 
666 
666 
667 
667 
668 



669 



CONTENTS. 



Male Generative Organs. 



i 



Prostate Gland 


PAGE 

. 671 


Structure 


. 671 


Vessels and Nerves 


. 672 


Prostatic Secretion 


. 672 


Cowper's Glands . 


. 672 



Penis. 



Root 

Glans Penis . 

Body 

Corpora Cavernosa 

Structure 
Corpus Spongiosum 
The Bulb 
Structure of Corpus Spongiosum 
Erectile Tissue 
Arteries of the Penis 
Lymphatics of the Penis 
Nerves of the Penis 



672 
672 
672 
673 
673 
673 
673' 
674 
674 
674 
674 
674 



The Testes and their Coverings. 

Scrotum 675 

Other Coverings of the Testis . . 675 
Vessels and Nerves of the Coverings of 

the Testis 675 

I 

Spermatic Cord. 

Its Composition 676 

Relations of in Inguinal Canal . . 676 
Arteries of the Cord . . . .676 



Veins of the Cord 


. 676 


Lymphatics and Nerves of the Cord . 676 


Testes. 




Form and Situation 


. 676 


Size and Weight 


. 677 


Coverings 


. 677 


Tunica Vaginalis . 


. 677 


Tunica Albuginea . 


. 677 


Mediastinum Testis 


. 677 


Tunica Vasculosa „ 


. 677 


Structure of Testis 


. 678 


Lobules of the Testis . 


. 678 


Number, Size, Shape, Positior 


1 . .678 


Structure of the Lobuli Test] 


s . .678 


Tubuli Seminiferi . 


. 678 


Arrangement in the Lobuli 


. 678 


in the Mediasti 


num. . 678 


in the Epididy 


mis . . 678 


Vasculum Aberrans 


. 678 


Vas Deferens, Course, Relatio 


ns . . 679 


Structure 


. 679 


Vesicute Seminales 


. 679 


Form and Size 


. 679 


Relations 


. 680 


Structure 


. 680 


Ejaculatory Ducts . 


. 680 


Structure of 


. 680 


The Semen . 


. 680 


Descent of the Testes . 


. .680 


Gubernaculum Testis 


. 681 



Female Organs of Greneration. 



Mons Veneris, Labia Majora . . . 682 
Labia Minora, Clitoris, Meatus Urinarius 683 
Hymen, Glands of Bartholine . . 683 

Bladder 684 

Urethra 684 

Rectum 685 

Vagina. 



Relations 


. 685 


Structure 


. 685 


Uterus. 




Situation, Form, Dimensions 


. 686 


Fundus, Body and Cervix 


. 686 


Ligaments 


. 686 


Cavity of the Uterus 


. 686 


Structure . . ' . . . 


. 687 


Vessels and Nerves 


. 687 



Its Form, Size, and Situation . . 688 
in the Foetus . . .688 

at Puberty . . . .688 
during and after Menstruation 688 
after Parturition . . . 688 
in Old Age . . . . 688 
Appendages of the Uterus. 
FaUopian Tubes ... .688 

Structure 688 

Ovaries 688 

Structure 689 

Graafian Vesicles . . . 689 

Ligament of the Ovary . . . 690 

Round Ligaments .... 690 

Vessels and Nerves of Appendages . 690 

Mammary Olands. 
Structure of Mamma . . . 691 

Vessels and Nerves . . . .691 



Surgical Anatomy of Inguinal Hernia. 



Dissection 692 

Superficial Fascia .... 692 

Superficial Vessels and Nerves . .692 
Deep Layer of Superficial Fascia . 692 

Aponeurosis of External Obhque . 693 

External Abdominal Ring . . . 694 
Pillars of the Ring .... 694 



Intercolumnar Fibres . 


. 694 


Fascia • 


. 694 


Poupart's Ligament 


. 695 


Gimbernat's Ligament . 


. 695 


Internal Oblique Muscle 


. 695 


Triangular Ligament 


. 695 


Cremaster .... 


. 695 



CONTENTS. 



Transversalis Muscle 
Spermatic Canal 
Fascia Transversalis 
Internal Abdominal Ring 
Subserous Ai-eolar Tissue 
Epigastric Artery 
Peritoneum 



PAGE 

696 
, 696 
. 696 
. 697 
. 697 
, 698 
, 698 



Inguiyial Hernia, 
Oblique Inguiual Hernia . . . 698 
Course and Coverings of Oblique Hernia 698 
Seat of Stricture . . . .698 



Scrotal Hernia 
Bubonocele 
Congenital Hernia . 
Infantile Hernia . 



PAGE 

. 699 
. 699 
. 699 
. 699 



Direct Inguinal Hernia. 

Course and Coverings of the Hernia . 699 

Seat of Stricture 699 

Incomplete Direct Hernia . . . 699 
Comparative Frequency of Oblique and 

Direct Hernia 700 

Diagnosis of Oblique and Direct -Hernia 700 



Surgical Anatomy of Femoral Hernia. 



Dissection .... 


. 700 


Crural Arch 


. 703 


Superficial Fascia 


. 700 


Gimbernat's Ligament 


. 704 


Cutaneous Vessels 


. 700 


Crural Sheath 


. 704 


Internal Sapliena Vein 


. 700 


Deep Crural Arch 


. 705 


Superficial Inguinal Glands 


. 701 


Crural Canal 


. 705 


Cutaneous Nerves 


. 701 


Femoral or Crural Ring 


. 705 


Deep Layer of Superficial Fascia 


. 701 


Position of Parts around the Ring . 705 


Cribriform Fascia 


. 702 


Septum Crurale 


. 706 


Fascia Lata .... 


. 702 


Descent of Femoral Hernia 


. 707 


Iliac Portion . 


. 702 


Coverings of Femoral Hernia 


. 707 


Pubic Portion 


. 703 


Varieties of Femoral Hernia 


. 707 


Saphenous Opening 


. 703 


Seat of Stricture 


. 708 



Surgical Anatomy of Perinseum and IscMo-Rectal Region. 



Ischio-Rectal Region. 
Dissection . 
Superficial Fascia 
External Sphincter 
Internal Sphincter 
Ischio-rectal Fossa 
Position of Parts contained in 



709 
709 
710 
710 
710 
711 



Perinceum. 
Boundaries, and Extent . . .711 
Superficial Layer of Superficial Fascia . 711 
Deep Layer of Superficial Fascia . 711 

Course taken by the Urine in Rupture 
of the Urethra . . . .712 

Muscles of the Perinceum {Male). 
Accelerator Urinee .... 712 

Erector Penis 713 

Transversus Perinsei . . . .713 
Superficial Perinseal Vessels and Nerves 713 
Transversus Perinaei Artery . . 714 

Muscles of the Perinceum {Female). 
Sphincter Vaginae . . . .714 

Erector Clitoridis . . . .714 

Transversus Perin^i . . . .714 



Surgical Anatomy of the Triangles of the Neck .... 320-2 

,, Axilla 348 

,, Bend of Elbow 354 

J, Scarpa's Triangle 384 

„ Popliteal Space . 389 

„ Laryngo-Traclieal Region. ... esi 



Compressor Urethrse . 


. 714 


Sphincter Ani 


. 714 


Levator Ani 


. 715 


CoccygEeus 


. 715 


Deep Perinseal Fascia , 


. 715 


Anterior Layer 


. 715 


Posterior Layer 


. 715 


Parts between the two Layers 


. 715 


Compressor Urethree . 


. 715 


Cowper's Glands 


. 715 


Pudic Vessels and Nerves 


. 715 


Artery of the Bulb 


. 715 


Levator Ani 


. 715 


Relations, Actions 


. 716 


Coccygeus, Relations, Actions 


. 716 


Position of Viscera at Outlet of P 


3lvis. 716 


Parts concerned in the Operati 


on of 


Lithotomy 


. 717 


Parts divided in the Operation 


. 718 


Parts to be avoided in the Operat 


ion . 718 


Abnormal Course of Arteries i 


n the 


Perinseum 


. 719 


Pelvic Fascia 


. 719 


Obturator Fascia 


. 720 


Recto-vesical Fascia . 


. 720 



i 



LIST OF ILLUSTRATIONS. 



RS" The Illustrations when copied from any other work, have tlie author's name 
affixed; when no such acknowledgment is made, the drawing is to be 
considered original. 



Osteology. 



1. A Cervical Vertebra . 

2. Atlas 

3. Axis 

4. A Dorsal Vertebra . 

5. Peculiar Dorsal Vertebrae . 

6. A Lumbar Vertebra . 
7 to 12. Development of a Vertebra 

13. Sacrum, anterior surface , 

14. Sacrum, posterior surface , 
1-5. Development of Sacrum . 

16. Coccyx, anterior and posterior surfaces 

17. Lateral View of Spine 

18. Occipital Bone, outer surface 

19. Occipital Bone, inner surface 

20. Occipital Bone, development of 

21. Parietal Bone, external surface . 

22. Parietal Bone, inner surface 

23. Frontal Bone, outer surface 

24. Frontal Bone, inner surface 

25. Temporal Bone, outer surface . 

26. Temporal Bone, inner surface . 

27. Temporal Bone, Petrous portion 

28. Temporal Bone, development of 

29. Sphenoid Bone, superior surface 

30. Sphenoid Bone, anterior surface 

31. Sphenoid Bone, posterior surface 

32. Plan of the Development of Sphenoid 

33. Ethmoid Bone, outer surface 

34. Perpendicular plate of Ethmoid, enlarged 

35. Nasal Bone, outer surface . 

36. Nasal Bone, inner surface . 

37. Superior Maxillary Bone, outer surface 

38. Superior MaxiUary Bone, inner surface 

39. Development of Superior Maxillary Bone 

40. Lachrymal Bone, outer surface . 

41. Malar Bone, outer surface 

42. Malar Bone, iuner surface 

43. Palate Bone, internal view, enlarged . 

44. Palate Bone, posterior view 

45. Inferior Turbinated Bone, inner surface 

46. Inferior Turbinated Bone, outer surface 



Quain 
Quain 

Qiiain 



Quain 



6 
6 

7 
8 
9 
10 
11 
13 
14 
15 
16 
17 
19 
21 
22 
23 
24 
25 
26 
28 
29 
31 
32 
33 
33 
35 
36 
37 
37 
39 
39 
41 
42 
44 
45 
44 
46 
47 
48 
49 
49 



XXVI 



LIST OF ILLUSTRATIONS. 



FIG. 

47. Vomer 

48. Lower Jaw, outer surface . 

49. Lower Jaw, inner surface . 

50. Base of Skull, inner surface 

51. Base of Skull, external surface . 

52. Anterior Region of Skull . 

53. Nasal Fossae, outer wall 

54. Nasal Fossae, inner wall or septum 

55. Hyoid Bone, anterior surface 

56. Sternum and Costal Cartilages, anterior surface 

57. Sternum, posterior surface 
58 to 61. Development of Sternum 

62. A Rib 

63. Vertebral Extremity of a Rib . 
64 to 68. Peculiar Ribs . . . .' 
69. Os Innominatum, external surface 

■ 70. Os Innominatum, internal surface 

71. Plan of Development of Os Innominatum 

72. Left Clavicle, superior surface 

73. Left Clavicle, inferior surface 

74. Left Scapula, anterior surface, or venter 

75. Left Scapula, posterior surface, or dorsum 

76. Plan of the Development of the Scapula 

77. Left Humerus, anterior view 

78. Left Humerus, posterior surface 

79. Plan of the Development of the Humerus 

80. Bones of the Left Fore-arm, anterior surface 

81. Bones of the Left Fore-arm, posterior surface 

82. Plan of the Development of the Ulna 

83. Plan of the Development of the radius 

84. Bones of the Left-hand, dorsal surface 

85. Bones of the Left-hand, palmar surface 

86. Plan of the Development of the Hand 

87. Right Femur, anterior surface . 

88. Right Femur, posterior surface 

89. Plan of the Development of the Femur 

90. Right Patella, anterior surface 

91. Right Patella, posterior surface 

92. Tibia and Fibula, anterior surface 

93. Tibia and Fibula, posterior surface . 

94. Plan of the Development of the Tibia 

95. Plan of the Development of the Fibula 

96. Bones of the Right Foot, dorsal surface 

97. Bones of the Right Foot, plantar surface 

98. Plan of the Development of the Foot 



PAGE 

60 



Quain 



Articulations. 

99. Vertical-Section of Two Vertebrae and their Ligaments, front view 

100. Occipito-Atloid and Alto-axoid ligaments, front view 

101. Occipito-Atloid and Alto-axoid ligaments, posterior view . 

102. Articulation between Odontoid Process and Atlas . . . Arnold 

103. Occipito-Axoid, and Alto-axoid Ligaments 

104. Temporo-Maxillary Articulation, external view . 

105. Temporo-Maxillary Articulation, internal view . 

106. Temporo-Maxillary Articulation, vertical section 

107. Costo-Vertebral and Costo-Transverse Articulations, anterior view 
103. Costo-Transverse Articulation Arnold 



LIST OF ILLUSTRATIONS. xxvii 

no. PAr.i!. 

109. Costo-Sternal, Costo-Xiphoid and Intercostal Articulations, front view . 150 

110. Articulations of Pelvis and Hip, front view 152 

111. Articulations of Pelvis and Hip, back view 153 

112. Vertical Section of Symphysis pubis : 156 

113. Stern o-Clavicular Articulation 157 

114. Shoulder Joint, Scapulo-Clavicular Articulation and proper Ligaments of 

Scapula 159 

115. Left Elbow Joint, shewing anterior and internal Ligaments . . . .161 

116. Left Elbow Joint, shewing posterior and external Ligaments . . . .162 

117. Ligaments of Wrist and Hand, anterior view .... Arnold 165 

118. Ligaments of Wrist and Hand, posterior view .... do. 165 

119. Vertical Section of Wrist, shewing the Synovial Membranes . . . .168 

120. Articulations of the Phalanges 170 

121. Left Hip Joint, laid open 171 

122. Eight Knee Joint, anterior view 172 

1 23. Right Knee Joint, posterior view 173 

124. Right Knee Joint, shewing internal Ligaments 174 

125. Head of Tibia, with semi-lunar Cartilages seen from above . . . .175 

126. Ankle Joint, Tarsal, and Tarso-Metatarsal Articulations, internal view . . 178 

127. Ankle Joint, Tarsal, and Tarso-Metatarsal Articulations, external view . . 179 

128. Ligaments of Plantar surface of the Foot 181 

129. Synovial Membranes of the Tarsus and Metatarsus . . . Arnold 182 



Muscles and Fascise. 

130. Plan of Dissection of Head, Face and Neck 188 

131. Muscles of the Head, Face and Neck 189 

132. Muscles of the right Orbit 193 

133. The relative position and attachment of the Muscles of the left Eyeball . 193 

134. The Temporal Muscle 1^)9 

135. The Pterygoid Muscles 200 

136. Muscles of the Neck and boundaries of the Triangles 204 

137. Muscles of the Neck, anterior view Quain 206 

138. Muscles of the Tongue, left side 209 

139. Muscles of the Pharynx, external view 211 

140. Muscles of the Soft Palate 213 

141. The Prevertebral Muscles • Quain 216 

142. Plan of Dissection of the Muscles of the Back 216 

143. Muscles of the Back — first, second, and part of the third layers Quain 219 

144. Muscles of the Back — deep layers 224 

145. Plan of Dissection of Abdomen 230 

146. The External Oblique Muscle £31 

147. The Internal Oblique Muscle 232 

148. The Transversalis, Rectus and Pyramidalis 234 

149. Transverse Section of Abdomen in Lumbar Region . . . Quain 235 

150. The Diaphragm, under surface 239 

151. Plan of Dissection of Upper Extremity 242 

152. Muscles of the Chest and Front of the Arm, superficial view . . . . 243 

153. Muscles of the Chest and Front of the Arm, with the boundaries of the 

Axilla 245 

154. Muscles on the Dorsum of the Scapula and the Triceps 249 

155. Front of the left Fore-arm, superficial muscles 254 

156. Front of left Fore-arm, deep muscles 257 

157. Posterior surface of Fore-arm, superficial muscles 259 

158. Posterior surface of the Fore-arm, deep muscles 262 

159. Muscles of the left Hand, palmar surface . . . . ' . . . . 265 

160. Dorsal Interossei of the left Hand 267 

IGl. Palmar InteroESci of Left Hand 268 



xxviii LIST OF ILLUSTRATIONS. 

FIG. 

162. Fracture of the Middle of the Clavicle 

163. Fracture of the Surgical Neck of the Humerus 

164. Fracture of the Humerus above the Condyles . 

165. Fracture of the Olecranon 

166. Fracture of the Shaft of the Radius .... 

167. Fracture of the lower end of the Eadius , 

168. Plan of Dissection of Lower Extremity, front view . 

169. Muscles of Iliac and Anterior Femoral Regions 

170. Muscles of the Internal Femoral Region , 

171. Plan of Dissection of Lower Extremity, posterior view 

172. Muscles of the Gluteal and Posterior Femoral Regions 

173. Muscles of the front of the Leg .... 

174. Muscles of the back of Leg, superficial layer 

175. Muscles of the back of the Leg, deep layer 

176. Muscles of the sole of the Foot, first layer. 

1 77. Muscles of the sole of the Foot, second layer 

178. Muscles of the sole of the Foot, third layer 

179. The Dorsal Interossei 

180. The Plantar Interossei 

181. Fracture of the Neck of the Femur within the Capsular Ligi 

182. Fracture of the Femur below the Trochanter Minor 

183. Fracture of the Femur above the Condyles 

184. Fracture of the Patella 

185. Oblique fracture of the shaft of the Tibia . 

186. Fracture of the Fibula, with dislocation of the Tibia inwards 



ament 



Hind 
do. 
do. 
do. 
do. 
do. 



Quain 



Hind 
do. 
do. 
do. 
do. 
do. 



PA rue " 

269 

270 

271 

271 

272 

273 

276 

277 

281 1 

284 

285 

290 

292 

294 

300 

301 

302 

303 

303 

304 

304 

305 

305 

306 

306 



■ 



Arteries. 



187. The Arch of the Aorta and its branches . 

188. Plan of the branches of the Arch of the Aorta . 

189. Surgical anatomy of the Arteries of the Neck . 

190. Plan of the branches of the External Carotid . 

191. The Arteries of the Face and Scalp .... 

192. The Internal Maxillary Artery, and its branches 

193. Plan of the branches of the Internal ]\Iaxillary Artery 

194. The Internal Carotid and Vertebral Arteries 

195. The Ophthalmic Artery and its branches . 

196. The Arteries at the base of the Brain 

197. Plan of the branches of the Right Subclavian Artery 

198. The Scapular and Circumflex Arteries 

199. The AsiUary Artery and its branches 

200. The Surgical Anatomy of the Brachial Artery . 

201. The Surgical Anatomy of the Radial and Ulnar Arteries 

202. Ulnar and Radial Arteries, deep view 

203. Arteries of the back of the Fore-Arm and Hand 

204. The Abdominal Aorta and its branches . . . - 

205. The Cceliac Axis and its branches .... 

206. The Ccehac Axis and its branches, the Stomach having been raised, and the 

Transverse Mesocolon removed .... 

207. The Superior Mesenteric Artery and its branches . 

208. The Inferior Mesenteric Artery and its branches 

209. Arteries of the Pelvis 

210. The Arteries of the Gluteal and Posterior Femoral Regions 

211. Surgical Anatomy of the Femoral Artery .... 

212. The Popliteal, Posterior Tibial, and Peroneal Arteries 

213. Surgical Anatomy of the Anterior Tibial and Dorsalis Pedis Arteries 

214. The Plantar Arteries, superficial view 

215. The Plantar Arteries, deep view ..... 



309 
309 
316 
316 
322 
327 
327 
333 
335 
337 
343 
346 
348 
353 
356 
359 
362 
366 
368 

367 
371 
372 
375 
381 
385 
391 
393 
398 
398 



do. 


430 


do. 


431 


do. 


432 



LIST OF ILLUSTRATIONS. 



Veins. 

F!0. PAGK, 

216. Veins of the Head and Neck 402 

217. Veins of the Diploe, as displayed by the removal of the outer ) „ , 

table of the Skull } i^reschet 4Ub 

218. Vertical Section of the Skull, shewing the Sinuses of the Dura Mater . . 407 

219. The Sinuses at the Base of the Skull 409 

220. The Superficial Veins of the Upper Extremity 410 

221. The VenseCavae and Azygos Veins, with their Formative Branches . . . 413 

222. Transverse Section of a Dorsal Vertebra, shewing the Spinal Veins Breschet 416 

223. VerticalSectionof two DorsalVertebrse, shewing the Spinal Veins Breschet 416 

224. The Internal Saphenous Vein and its Branches 417 

225. The External, or short Saphenous Vein 418 

226. The Portal Vein and its Branche Quaiii 422 



Lympliatics. 

227. The Thoracic and Right Lymphatic Ducts 427 

228. The Superficial Lymphatics and Glands of the Head, Face, and ) ,, ■ ^o^ 

-vj ^ > Jilciscci-Cjni 429 

229. The Deep Ljinphatics and Glands of the Neck and Thorax 

230. The Superficial Lymphatics and Glands of the Upper Extremity 

231. The Superficial Lymphatics and Glands of the Lower Extremity 

232. The Deep Lymphatic Vessels and Glands of the Abdomen and ) 

T5 1 • \ do. AM 

relvis \ 



ISTervous System, 

233. The Spinal Cord and its Membranes . 443 

234. Transverse Section of the Sjainal Cord and its Membranes . Arnold 443 

235. Spinal Cord, side view. Plan of the Fissures and Columns . Quain 445 

236. Transvers3 Sections of the Cord Arnold 447 

237. Medulla Oblongata and Pons Varolii, anterior surface 451 

238. Medulla Oblongata and Pons Varolii, posterior surface 452 

239. Transverse Section of Medulla Oblongata .... Arnold 453 

240. The Columns of the Medulla Oblongata, and their Connection ) Altered fr-om 

with the Cerebrum and Cerebellum \ Arnold '' 

241. Upper Surface of the Brain, the Pia Mater having been removed . . . 456 

242. Base of the Brain 458 

243. Section of the Brain, made on a level with the Corpus Callosum , . . 461 

244. The Lateral Ventricles of the Brain 462 

245. The Fornix, Velum Interpositum, and Middle or Descending Horn of the 

Lateral Ventricle 4G4 

246. The Third and Fourth Ventricles 467 

247. The Cerebellum, upper surface 471 

248. The Cerebellum, under surface .......... 471 

249. The Cerebellum, vertical section Arnold 473 



Cranial Nerves. 

250. The Optic Nerves and Optic Tracts ....:.... 476 

251. Course of the Fibres in the Optic Commissure . . . , Bowman 477 

252. Nerves of the Orbit, seen from above After Arnold 478 



XXX 



LIST OF ILLUSTRATIONS. 



253. Nerves of the Orbit and Ophthalmic GangHon, side view 

254. The Course and Connections of the Facial Nerve in the Tem- 

poral Bone 

255. The Nerves of the Scalp, Face, and Side of the Neck 

256. The Hypoglossal Nerve, Cervical Plexus, and their Branches . 

257. Distribution of the Second and Third Divisions of the Fifth 

Nerve and Sub-Maxillary Ganglion 

258. The Spheno-Palatine Ganglion and its Branches 

259. The Otic GangUon and its Branches 

260. Origin of the Eighth Pair, their Ganglion and Communications . 

261. Course and Distribution of the Eighth Pair of Nerves 



After Arnold 479 

After Bidder 480 

. 482 

. 484 

After Arnold 488 

. 490 

After Arnold 494 

Bendz. 494 

. 495 



Spinal 'Nerves. 



262. Plan of the Brachial Plexus 

263. Cutaneous Nerves of Right Upper Extremity, anterior view 

264. Cutaneous Nerves of Right Upper Extremity, posterior view 

265. Nerves of the Left Upper Extremity, front view 

266. The Supra-Scapular, Circumflex, and Musculo-Spiral Nerves 

267. The Lumbar Plexus and its Branches Alterei 

268. The Cutaneous Nerves of Lower Extremity, front view . 

269. Nerves of the Lower Extremity, front view 

270. Cutaneous Nerves of Lower Extremity, posterior view 

271. Nerves of the Lower Extremity, posterior view 

272. The Plantar Nerves 

273. The Sympathetic Nerve 



dfr 



. 507 
. 509 
. 610 
. 512 
. 514 
Quain 519 
. 521 
. 521 
. 527 
. 527 
629 
. 533 



274. 
275. 
276. 
277. 
278. 
279. 
280. 
281. 
282. 
283. 

284. 

285. 
286. 

287. 
288. 
289. 
290. 
291. 
292. 
293. 
294. 
295. 



Organs of Sense. 

A Sectional View of the Skin, magnified 542 

Upper Surface of the Tongue 548 

The three kinds of PapiUse of the Tongue, magnified . . . Bowman. 548 

Cartilages of the Nose Arnold 550 

Bones and Cartilages of the Septum of the Nose ... do. 651 

Nerves of Septum of Nose do, 553 

A Vertical Section of the Eyeball, enlarged . . . • . • .554 

The Choroid and Iris, enlarged Altered from Zinn 556 

The Veins of the Choroid, enlarged Arnold 667 

The Arteries of the Choroid and Iris, the Sclerotic has been ) , g^g 

mostly removed, enlarged • ) 

The Arteria Centralis Retinae, Yellow Spot, &c., the anterior half of the 

Eyeball being removed, enlarged 560 

The Crystalline Lens, hardened and divided, enlarged . . Arnold 563 

The Meibomian Glands, &c., seen from the Inner Surface of the ) , ^„^ 

Eyelids ) 

The Lachrymal Apparatus, right side 566 

The Pinna, or Auricle, outer surface 568 

The Muscles of the Pinna Arnold 569 

A Front View of the Organ of Hearing, right side . . . Scarpa 670 

View of Inner Wall of Tympanum, enlarged ....... 572 

The Small Bones of the Ear, seen from the outside, enlarged . Arnold 674 

The Osseous Labyrinth, laid open, enlarged .... Soemmering 677 

The Cochlea laid open, enlarged ...... Arnold 578 

The Membranous Labyrinth detached, enlarged . . . Breschet 580 



LIST OF ILLUSTRATIONS. 



Organs of Digestion and tlieir Appendages. 

no. PAOE. 

296. Sectional View of the Nose, Mouth, Pharynx, &c 583 

297. The Permanent Teeth, external view . . 584 

298. The Temporary, or Milk Teeth, external view 686 

299. Vertical Section of a Molar Tooth 587 

300. Vertical Section of a Bicuspid Tooth, magnified . . • . After Retzitis 587 

301. to 306. Development of the Teeth Ooodsir 589 

307. The Salivary Glands 593 

308. The Eegions of the Abdomen and their contents, (edge of Costal Cartilages in 

dotted Outline) 598 

309. Diagram shewing the Reflections of the Peritoneum, as seen in \ Altered from 

a Vertical Section of the Abdomen ) Quain 

310. The Mucous Membrane of the Stomach and Duodenum, with the Bile Ducts 603 

311. The Muscular Coat of the Stomach, (the innermost Layer is not seen) . . 604 

312. Minute Anatomy of Mucous Membrane of Stomach . . . Dr. Sprott Boyd 605 

313. Two Villi, magnified 608 

314. Patch of Pleyer's Glands from the lower part of the Ileum .... 609 

315. A portion of Peyer's Glands magnified Boehni 609 

316. The Caecum and Colon laid open, to show the Ilio-csecal Valve .... 610 

317. IVIinute structure of Large Intestine Boehvi 613 

318. The Liver, upper surface 615 

319. The Liver, under surface 616 

320. Longitudinal section of an Hepatic Vein Kiernan. 618 

321. Longitudinal section of a small Portal Vein and Canal . . do. 619 

322. A transverse section of a small Portal Canal and its vessels . do. 619 

323. The Pancreas and its relations 622 

324. Transverse section of the Spleen, showing the Trabecular Tissue, the Splenic 

Vein, and its branches ... 624 

325. The Malpighian Corpuscles, and their relation with the Splenic Artery and its 

branches 625 

326. One of the Splenic Corpuscles, showing its relations with the blood-vessels . 626 

327. Transverse section of the Human Spleen, showing the distribution of the 

Splenic Artery and its branches 626 



Organs of Circulation. 



328. The right Auricle and Ventricle laid open, the anterior walls of both being 

removed 630 

329. The left Auricle and Ventricle laid open, the anterior walls of both being 

removed ............. 634 

330. Plan of the Foetal Circulation 638 



Organs of Voice and Respiration. 

331. Side view of Thyroid and Cricoid Cartilages 641 

332. The Cartilages of the Larynx, posterior view 642 

333. Interior of the Larynx, seen from above, enlarged .... Willis 645 
33 i. Muscles of Larynx, side view, right ala of Thyroid Cartilage removed . 647 

335. Front view of Cartilages of Larynx : the Trachea and Bronchi .... 649 

336. Surgical anatomy of the Laryngo-tracheal Region 651 

337. A transverse section of the Thorax, showing the relative position of the 

Viscera, and the reflections of the Pleura3 652 

338. Front view of the Heart and Lunsrs. 654 



xxxii LIST OF ILLUSTRATIONS. 

The Urinary and Generative Organs. 

PIG. PAGE 

339. Vertical sectioB of the Kidney 661 

340. A Plan to shew the minute structure of the Kidney . . Bowman 661 

341. Vertical section of Bladder, Penis, and Urethra . . . ■ . . . 665 

342. The Bladder and Urethra laid open, seen from above 668 

343. The Testis in situ, the Tunica Vaginalis having been laid open .... 677 

344. Plan of a vertical section of the Testicle, to shew the arrangement of the 

ducts 678 

345. Base of the Bladder, with the Vasa Deferentia and Vesicula3 ) -r^ „ „^^ 

c, . T > Ealler 679 

Semmales \ 

346. The Vulva, External Female Organs of Generation 682 

347. Section of Female Pelvis, shewing Position of Viscera 684 

348. The Uterus and its Appendages, anterior view .... Wilso7i 869 

349. Inguinal Hernia, Superficial Dissection 693 

350. Inguinal Hernia, showing the Internal Oblique, Cremaster, and Spermatic Canal 695 

351. Inguinal Hernia, shewing the Transversalis Muscle, the Transversalis Fascia, 

and the Internal Abdominal Ring 697 

352. Femoral Hernia, Superficial Dissection 701 

353. Femoral Hernia, shewing Fascia Lata and Saphenous Opening .... 702 

354. Femoral Hernia, Iliac Portion of Fascia Lata removed, and Sheath of 

Femoral Vessels and Femoral Canal exposed 704 ^ 

355. Hernia; the Eolations of the Femoral and Internal Abdominal Rings, seen 

from within the Abdomen, right side 706 

356. Variations in Origin and Course of Obturator Artery 706 

357. Plan of Dissection of Perinaeum and Ischio-Rectal Region 710 

358. The Perinseum ; the Integument and Superficial Layer of Superficial Fascia 

reflected 712 

359. The Superficial Muscles and Vessels of the Perinseum 713 

360. Deep Perinseal Fascia ; on the Left Side the Anterior Layer has been removed 714 

361. A View of the Position of the Viscera at the Outlet of the Pelvis . . . 717 

362. A Transverse Section of the Pelvis, shewing the Pelvic Fascia . After Wilson 718 

363. Side View of the Pelvic Viscera of the Male Subject, shewing the Pelvic and 

Perinseal Fasciae 719 



DESCRIPTIVE AND SURGICAL ANATOMY. 



rjESCRIPTIVE ANATOMY comprises a detailed account of the numerous 
organs of which the body is formed, especially with reference to their out- 
ward form, their internal structure, the mutual relations they bear to each other, 
and the successive conditions they present during their development. 

Surgical Anatomy is, to the student of medicine and surgery, the most essential 
branch of anatomical science, having reference more especially to an accurate know- 
ledge of the more important regions, and consisting in the application of anatomy 
generally to the practice of surgery. 

The Study of Anatomy is commonly divided into several distinct branches, 
according to the mutual resemblance of the organs; and these branches have cor- 
responding denominations. 



Osteology. 



TN the construction of the human body, it would appear essential, in the first 
place, to provide some dense and solid texture capable of giving support and 
attachment to the softer parts of the frame, and at the same time to protect in 
closed cavities the more important vital organs; and such a structure we find pro- 
vided in the various bones, which form what is called the Skeleton. 

Bone is one of the hardest structures of the animal body; it possesses also a cer- 
tain degree of toughness and elasticity. Its colour, in a fresh state, is of a pinkish 
white externally, and deep red within. Chemical analysis resolves bone into an 
organic, or animal, and an inorganic, or earthy material, intimately combined 
together; the animal matter giving to bone its elasticity and toughness, the earthy 
part its hardness and solidity. The animal constituent may be separated from the 
earthy, by steeping bone in a dilute solution of nitric or muriatic acid: by this 
process the earthy constituents are gradually dissolved out, leaving a tough semi- 
transparent substance which retains, in every respect, the original form of the 
bone. This is often called cartilage, but differs from it in being softer, more flexible, 
and, when boiled under a high pressure, it is almost entirely resolved into gelatine. 
The earthy constituent may be obtained by subjecting a bone to strong heat in an 
open fire with free access of air. By these means, the animal matter is entirely 
consumed, the earthy part remaining as a white brittle substance still preserving 
the original shape of the bone. 

The organic or animal constituent of bone, forms about one-third, or 33*3 per 
cent.; the inorganic or earthy matter, two-thirds, or 66*7 per cent.: as is seen in 
the subjoined analysis by Bei'zelius: — 

Animal Matter, Gelatine and Blood-vessels . 33*30 



t Phosphate of Lime . 
Inorganic \ Carbonate of Lime . 
or < Fluoride of Calcium . 

Earthy Matter, j Phosphate of Magnesia 

i Soda and Chloride of Sodium 



51-04 
11-30 

2-00 

ri6 

I'20 

100-00 



Adult 


Old Age 


20' 1 8 . 


.. 12-2 


74-84 . 


.. 84-1 



2 OSTEOLOGY. 

The proportion between these two constituents varies at different periods of life, 
as is seen in the following table from Schreger: — 

Child 
Animal matter . . 47"20 

Earthy matter . . 48*48 

There are facts of some practical interest, bearing upon the difference here 
seen in the amount of the two constituents of bone, at different periods of life. 
Thus, in the child, where the animal matter forms nearly one-half of the weight 
of the bone, it is not uncommon to find, after an injury happening to the bones, 
that they become bent, or only partially broken, from the large amount of flexible 
animal matter which they contain. Again, also in aged people, where the bones 
contain a large proportion of earthy matter, the animal matter at the same time 
being deficient in quantity and quality, the bones are more brittle, their elasticity 
is destroyed; and, hence, fracture take's place more readily. Some of the diseases, 
also, to which bones are liable, mainly depend on the disproportion between the 
two constituents of bone. Thus, in the disease called rickets, so common in the 
children of scrofulous parents, the bones become bent and curved, either from 
the superincumbent weight of the body, or under the action of certain muscles. 
This depends upon some deficiency of the nutritive system, by which bone becomes 
minus its normal proportion of earthy matter, whilst the animal matter is of un- 
healthy quality. In the vertebra of a rickety subject. Dr. Bostock found in lOO 
parts 79'75 animal, and 20*25 earthy matter. 

The relative proportions of the two constituents of bone are found to differ in 
different bones of the skeleton. Thus the p&trous portion of the temporal bone 
contains a large proportion of earthy matter, the bones of the limbs contain more 
earthy matter than those of the trunk, and those of the upper extremity, a larger 
proportion than those of the lower. 

On examining a section of any bone, it is seen to be composed of two kinds of 
tissue, one of which is dense and compact in texture like ivory; the other open, 
reticular, spongy, enclosing cancelli or spaces, and hence called spongy or cancel- 
lated tissue. The compact tissue is always placed on the exterior of a bone; the 
cancellous tissue is always internal. The relative quantity of these two kinds of 
tissue varies in different bones, and in different parts of the same bone, as strength 
or lightness is requisite. 

Form of Bones. The various mechanical purposes for which bones are employed 
in the animal economy require them to be of very different forms. All the scien- 
tific principles of Architecture and Dynamics are more or less exemplified in the 
construction of this part of the human body. The power of the arch in resisting 
superincumbent pressure is well exhibited in various parts of the skeleton, such 
as the human foot, and more especially in the vaulted roof of the cranium. 

Bones are divisible into four classes : Long, Short, Flat, and Irregular. 

The long bones are found chiefly in the limbs, where they form a system of 
levers, which have to sustain the weight of the trunk, and to confer extensive 
powers of locomotion. A long bone consists of a lengthened cylinder or shaft, 
and two extremities. The shaft is a hollow cylinder, the walls consisting of dense 
compact tissue of great thickness in the middle, and becoming thinner towards 
the extremities; the spongy tissue is scanty, and the bone is hollowed out in its 
interior to form the medullary canal. The extremities are generally somewhat 
expanded for greater convenience of mutual connexion, and for the purposes of 
articulation. Here the bone is made up of spongy tissue with only a thin coating 
of compact substance. The long bones are the clavicle, humerus, radius, ulna, 
femur, tibia, fibula, metacarpal, and metatarsal bones and the phalanges. 

Short Bones. Where a part is intended for strength and compactness, and the 
motion at the same time slight and limited, it is divided into a number of small 
pieces united together by ligaments, and the separate bones are short and com- 
pressed, such as the bones of the carpus and tarsus. These bones, in their struc- 



GENERAL ANATOMY OF BONE. 3 

ture, are spongy throughout, excepting at their surface, where there is a thin crust 
of compact substance. 

Flat Bones. Where the principal requirement is either extensive protection, 
or tlie provision of broad surftices for muscular attachment, we find the osseous 
structure remarkable for its slight thickness, becoming expanded into broad flat 
plates, as is seen in the bones of the skull and shoulder-blade. These bones are 
composed of two thin layers of compact tissue, enclosing a layer of cancellous 
tissue of variable thickness. In the cranial bones, these layers of compact tissue 
are familiarly known as the tables of the skull; the outer one is thick and tough, 
the inner one thinner, denser, and more brittle, and hence termed the vitreous 
table. The intervening cancellous tissue is called the diploe. The flat bones are 
the occipital, parietal, frontal, nasal, lachrymal, vomer, scapulcB, and ossa inno- 
minata. 

The Irregular or Mixed bones are such as, from their peculiar form, cannot be 
grouped under either of the preceding heads. Their structure is similar to that 
of other bones, consisting of an external layer of compact, and of a spongy can- 
cellous substance within. The irregular bones are the vertebrce, sacrum, coccyx, 
temporal, sphenoid, ethmoid, superior maxillary, inferior maxillary, palate, infe- 
rior turbinated, and hyoid. 

Vessels of Bone. The blood-vessels of bone are very numerous. Those of the 
compact tissue consist of a close and dense network of vessels, which ramify in a 
fibrous membrane termed the periosteum, which covers the entire surface of the 
bone in nearly every part. From this membrane, vessels pass thi-ough all parts of 
the compact tissue, running through the canals which traverse its substance. The 
cancellous tissue is supplied in a similar way, but by a less numerous set of 
larger vessels, which, perforating the outer compact tissue, are distributed to the 
cavities of the spongy portion of the bone. In the long bones, numerous apertures 
may be seen at the ends near the articular surfaces, some of which give passage to 
the arteries referred to; but the greater number, and these are the largest of them, 
are for the veins of the cancellous tissue which run separately from the arteries. 
The medullary canal is supplied by one large artery (or sometimes more), which 
enters the bone at the nutritious foramen (situated, in most cases, near the centre 
of the shaft), and perforates obliquely the compact substance. This vessel, usually 
accompanied by one or two veins, sends branches upwards and downwards, to 
supply the medullary membrane, which lines the central cavity and the adjoining 
canals. The ramifications of this vessel anastomose with the arteries both of the 
cancellous and compact tissues. The veins of bone are large, very numerous, and 
run in tortuous canals in the cancellous texture, the sides of which are constructed 
of a thin lamella of bone, perforated here and there for the passage of branches 
from the adjacent cancelli. The veins thus enclosed and supported by the hard 
structure, have exceedingly thin coats; and when the bony structure is divided, 
they remain patulous, and do not contract in the canals in which they are con- 
tained. Hence the constant occurrence of purulent absorption after amputation, 
in those cases where the stump becomes inflamed, and the cancellous tissue is 
infiltrated and bathed in pus. Lymphatic vessels have been traced into the sub- 
stance of bone. Nerves, also, accompany the nutritious arteries into their interior. 

Development of Bone. From the peculiar uses to which bone is applied, in 
forming a hard skeleton or framework for the softer materials of the body, and in 
enclosing and protecting some of the more important vital organs, we find its 
development takes place at a very early period. Hence the parts that appear 
soonest" in the embryo, are the vertebral column and the skull, the great central 
column, to Avhich the other parts of the skeleton are appended. At an early period 
of embryonic life, the parts destined to become bone consist of a congeries of cells, 
Avhich constitutes the simplest form of cartilage. This temporary cartilage, as it 
is termed, is an exact miniature of the bone which in due course is to take its 
place; and as the process of ossification is slow, and not completed until adult life, 
it increases in bulk by an interstitial development of new cells. The next step in 

B 2 



4 OSTEOLOGY. 

this process is the ossification of the intercellular substance, and of the cells 
composing the cartilage. Ossification commences in the interior of the cartilage 
at certain points, called points or centres of ossification, from which it extends 
into the surrounding substance. The period of ossification varies much in difierent 
bones. It commences first in the clavicle, in which the primitive point appears 
during the fifth week; next in the lower jaw. The ribs also, and the long bones 
of the limbs, appear soon after. The number of ossific centres varies in diiferent 
bones. In most of the short bones, it commences by a single point in the centre, 
and proceeds towards the circumference. In the long bones, there is a central 
point of ossification for the shaft or diaphysis; and one for each extremity, the 
epiphyses. That for the shaft is the first to appear; those for the extremities 
appear later. For a long period after birth, a thin layer of unossified cartilage 
remains between the diaphysis and epiphyses, until their growth is finally com- 
pleted. Processes such as the trochanters that have separate centres of ossifi- 
cation, are called epiphyses previous to their union. 

Growth of Bone. Increase in the length of a bone, is provided for by the 
development of new bone from either end of the shaft (diaphysis); and in the 
thickness, by the deposition of new matter upon the surfece : but when growth 
is at an end, the epiphyses become solidly united to the ends of the diaphysis, 
and the bone is completely formed. A knowledge of the exact periods when the 
epiphyses become joined to the shaft, aids the surgeon in the diagnosis of many of 
the injuries to which the joints are liable; for it not unfrequently happens, that 
on the application of severe force to a joint, the epiphyses become separated from 
the shaft, and such injuries may be mistaken for fracture. 

The order in which the epiphyses become ttnited to the shaft, follows a pecu- 
liar law, which appears to be regulated by the direction of the nutritious artery 
of the bone. Thus the arteries of the bones of the arm and forearm converge 
towards the elbow, and the epiphyses of the bones forming this joint become 
united to the shaft before those at the opposite extremity. In the lower extre- 
mities, on the contrary, the nutritious arteries pass in a direction from the knee; 
that is, upwards in the femur, downwards in the tibia and fibula; and in them it 
is observed, that the upper epiphysis of the femur, and the lower epiphyses of the 
tibia and fibula, become first united to the shaft. 

A diseased condition of any joint makes considerable variation in the peAod 
of development of the several bones which enter into its formation. Thus, in 
chronic inflammation occurring in a joint at an early period of life, the epiphysal 
cartilages take on premature ossification; this process proceeding so rapidly, that 
it speedily becomes converted into bone, which becomes united to the shaft, and 
the bone ever after is considerably diminished in length: hence partial atrophy of 
the limb is the result. 

The entire skeleton in an adult, consists of 2o6 distinct bones. These are — 



Cranium . . . , . . 

Ossicula auditus ..... 

Face ....... 

Vertebral column (sacrum and coccyx included) 

Os hyoides, sternum, and ribs . 

Upper extremities ..... 

Lower extremities ..... 



26 
26 
64 
62 



206 



In this enumeration, the sesamoid and Wormian bones are excluded, as also 
are the teeth, which difier from bone both in structure, development, and mode of 
growth. The skeleton consists of a central column or Spine; of three great cavi- 
ties, the Skull, Thorax, and Pelvis; and of the Superior and Inferior Extremities. 



GENERAL CHARACTERS OF THE VERTEBRA. 5 

THE SPINE. 

The Spine is a flexuous column, formed of a series of bones called VertehrcB. 

The Vertebras are divided into true ?in^ false. 

The true vertebrae are twenty-four in number, and have received the names 
cervical, dorsal, and lumbar, according to the position which they occupy; 
seven being found in the cervical region, twelve in the dorsal, and five in the 
lumbar. 

The false vertebrae, nine in number, are firmly united, so as to form two bones 
— five entering into the formation of the upper bone or sacrum, and four into 
the terminal bone of the spine or coccyx. 

!7 Cei'vical. 
12 Dorsal. 
5 Lumbar. 

False VertebrcB, Q \ ^ r-^ 

^ ( 4 Coccyx. 

General Characters of the Vertebra. 

Each vertebi'a consists of two parts, an anterior solid segment or body, forming 
the chief pillar of supj)ort; a posterior segment, the arch, forming part of a hollow 
cylinder for protection. The arch is formed of two pedicles and two laminae, 
supporting seven processes; viz. four articular, two transverse, and one spinous 
process. 

The Body is the largest and most solid part of a vertebra, serving to support 
the weight of the cranium and trunk. Above and below it is slightly concave, 
presenting a rim around its circumference; and its surfaces are rough, for the 
attachment of the intervertebral fibro-cartilages. In front it is convex from side 
to side, concave from above downwards. Behind, flat from above downwards, and 
slightly concave from side to side. Its anterior surface is perforated by a few 
small apertures, for the passage of nutrient vessels; whilst on the posterior surface 
is a single irregular- shaped, or occasionally several large apertures, for the exit of 
veins from the body of the vertebra, the vencB basis vertebrcB. 

The Pedicles project backwards, one on each side, from the upper part of the 
body of the vertebrte, at the line of junction of its posterior and lateral surfaces; 
they form the lateral parts of the arch, which is completed posteriorly by the two 
laminae. The concavities above and below the pedicles are the intervertebral 
notches; they are four in number, two on each side, the inferior ones being 
always the deeper. 

The Lamiiice consist of two broad plates of bone, Avhich complete the vertebral 
arch behind, enclosing a foramen which serves for the protection of the spinal 
cord; they are connected to the body through the intervention of the pedicles. 
Their upper and lower borders are rough, for the attachment of the ligamenta 
subfiava. 

The Spinous Process projects backwards from the junction of the two laminae, 
and serves for the attachment of muscles. 

The Transverse Processes, two in number, project one at each side from the 
point where the articular processes join the pedicle. They also serve for the 
attachment of muscles. 

The Articular Processes are four in number; two superior, the smooth surfaces 
of which are directed more or less backwards; and two inferior, the articular 
surfaces of which look more or less forwards. 

Characters of the Cervical Vertebrae (fig. i). 

The Body is smaller than in any other region of the spine, thicker before than 
behind, and broader from side to side than from before backwards. Its upper 
surface is concave transversely, and presents a projecting lip on each side; its lower 



OSTEOLOGY. 



surface being convex from side to side, concave from before backwards, and present- 
ing laterally a shallow concavity, which receives the corresponding projecting 
lip of the adjacent vertebra. The pedicles are directed obliquely outwards, and 
the superior intervertebral notches are slightly deeper, but narrower, than the 
inferior. The lamina are narrow, long, thinner above than below, and imbricated 
i.e. overlapping each other; enclosing the foramen, which is very large, and of a 
triangular form. The spinous processes are short, bifid at the extremity, the two 
divisions being often of unequal size. They increase in length from the fourth 
to the seventh. The transverse processes are short, directed downwards, outwards 
and forwards, bifid at their extremity, and marked by a groove along their upper 
surface, which runs downwards and outwards from the superior intervertebral 
notch, and serves for the transmission of one of the cervical nerves. The trans- 
verse processes are pierced at their base by a foramen, for the transmission of 
the vertebral artery, vein, and plexus of nerves. Each of these processes is formed 
by two roots : the anterior or smaller, which is attached to the side of the body 
corresponds to the ribs in the dorsal region ; the posterior is larger, springs from 
the pedicle, and corresponds to the true transverse processes. It is by the junc- 
tion of these two processes, that the vertebral foi'amen is formed. The extremities 
of each of these roots form the anterior and posterior tubercles of the transverse 

I. — A Cervical Vertebra. 



Anterior TnhnTcle of Trans.Proc 



For a men far Yorbebr.al Art 1. 
PostenorTuicrcle of Trans . P roc- 




ansversc ±^roc£ss. 



,-Siipe.rior Artilcular ProcessK 
-Inferior AatLculiiT Process 



processes. The articular processes are oblique: the superior are of an oval form, 
flattened, and directed upwards and backwards; the inferior downwards and 
forwards. 

The peculiar vertebriB in the cervical region are the first or Atlas; the second 
or Axis; and the seventh or Vertebra prominens. 

The Atlas (fig. 2) (so named from supporting the globe of the head). The chief 
2. — 1st Cervical Vertebra, or Atlas. 



Tuhercle 



Tro/iis. Proct 




■Foratne/i £o\ 
Vertebral/ ArA 



Qrooifefcr VerD^i^ A rt -f 
ajid If.^ Gerv.N'e'rvs 



Spin, Proc, 



CERVICAL VERTEBRiE. 



peculiarities of this bone are, that it has neither body, spinous process, nor pedicles. 
It consists of an anterior arch, a posterior arch, and two lateral masses. The 
anterior or lesser arch, which forms about one-fifth of the bone, represents the 
front part of the body of a vertebra; its anterior surface is convex, and presents 
about its centre a tubercle for the attachment of the Longus colli muscle; posteriorly 
it is concave, and marked by a smooth oval surface, for articulation with the odontoid 
process of the axis. The posterior or greater arch, which forms about two-fifths 
of the circumference of the bone, terminates behind in a tubercle, which is the ru- 
diment of a spinous process, and gives origin to the Rectus capitis posticus minor. 
The posterior part of the arch presents above a rounded edge; whilst in front, 
immediately behind the superior articular processes, are two grooves, sometimes 
converted into foramina by delicate bony spiculse. These grooves represent the 
superior intervertebral notches, and are peculiar from being situated behind the 
articular processes, instead of before them, as in the other vertebrse. They serve 
for the transmission of the vertebral artery, which, ascending through the foramen 
in the transverse process, winds around the lateral mass in a direction backwards 
and inwards. They also transmit the sub-occipital nerves. On the under surface 
of the posterior arch, in the same situation, are two other grooves, placed behind 
the lateral masses, and representing the inferior intervertebral notches of other 
vertebrge. They are much less marked than the superior. The lateral masses, 
which are the most bulky and solid parts of the Atlas, present two articulating pro- 
cesses above, and two below. The two superior are of large size, oval, concave, 
and approach towards one another in front, but diverge behind; they are directed 
upwards, inwards, and a little backwards, forming a kind of cup for the condyles 
of the occipital bone, and are admirably adapted to the nodding movements of the 
head; whilst the inferior, which are circular in form, and flattened, are directed 
downwards, inwards, and a little backwards, articulating with the axis, and per- 
mitting the rotatory movements. Just below the inner margin of each superior 
articular surface, is a small tubercle, for the attachment of a ligament which, 
stretching across the ring of the Atlas, divides it into two unequal parts ; the anterior 
or smaller segment receiving the odontoid process of the Axis, the posterior allowing 
the transmission of the spinal cord and its membranes. This ligament and the 
odontoid process are marked in the figure in dotted outline. The transverse pro- 
cesses are of large size, long, not bifid, perforated at their base by a canal for the 
vertebral artery, which is directed from below, upwards and backwards. 

The Axis (fig. 3) (so named from forming the pivot upon which the head 

3. — 2nd Cervical Vertebra, or Axis. 
Odontoid Pi'oc , 



R 



Artec 



'Spin. troc.J 




Artie. iSurf. for Atlas 



B odh 



Trans .f roe. 
Infer. A rtic.Proc. 



rotates). The most distinctive character of this bone is the existence of a strong 
prominent process, tooth-like in form (hence the name odontoid), which arises per- 
pendicularly from the upper part of the body. The body is of a triangular form; 



OSTEOLOGY. 



its anterior surface deeper than the posterior, presents a median longitudinal ridge, 
separating two lateral depressed surfaces for the attachment of the Longi colli 
muscles. The odontoid process presents two oval articulating surfaces: one in 
front, for articulation with the Atlas; another behind, for the transverse ligament; 
the apex is pointed, and on either side of it is seen a rough impression for the 
attachment of the odontoid or chefek ligaments; whilst the base, where attached to 
the body, is constricted, so as to prevent displacement from the transverse ligament, 
which binds it in this situation to the anterior arch of the Atlas. On each side 
of this process are seen the superior articular surfaces; they are round, convex, 
directed upwards and outwards, and are peculiar in being supported on the body, 
pedicles, and transverse processes. The inferior articular surfaces, which are pos- 
terior and external to these, have the same direction as those of the other cervical 
vertebrae. The superior intervertebral notches are very shallow, and lie behind the 
articular processes; the inferior in front of them, as in the other cervical vertebrae. 
The transverse processes are very small, not bifid, and perforated by the vertebral 
foramen, which is directed obliquely upwards, and outwards. The laminae are 
thick and strong, and the spinous process is of large size, very strong, deeply chan- 
nelled on its under surface, and presenting a bifid tubercular extremity for the 
attachment of muscles. 

Seventh Cervical. The most distinctive character of this vertebra is the existence 
of a very large, long, and prominent spinous process; hence the name ' Vertebra pro- 
minens.' This process is thick, nearly horizontal in direction, not bifurcated, 
and has attached to it the ligamentum nuchae. The foramina in the transverse 
processes are small, often wanting, and when present do not give passage to 
the vertebral artery; their upper surface presents only a slight groove, and gene- 
rally only a trace of bifurcation at their extremity. 

Characters of the Dorsal Vertebra. 

The Dorsal Vertebrce (fig. 4) are intermediate in size between the cervical and 
lumbar. The body is somewhat triangular in form, broader in the antero-posterior than 



/Stujacrior ^I'tie. JBrocess^ 



4. — A Dorsal Vertebra. 

I. 



Devii. facet for head ofRil 



Facet fir Tubercle ofRiJ) 




i 



Dem iCacet for head of Rib 
Infer. Artie .Ftoc. 



in the lateral direction, more particularly in the middle of the dorsal region, thicker 
behind than in front, flat above and below, deeply concave behind, and marked on 
each lateral surface, near the root of the pedicle, by two demi-facets, one above, 
the other below. These are covered with cartilage in the recent state; and, when 



DORSAL VERTEBRA. 



articulated with the adjoining vertebrse, form oval surfaces for the reception of 
the heads of the corresponding ribs. The pedicles are strong, and the inferior 
intervertebral notches of large size. The lamina3 are broad and thick, and the spinal 
foramen small, and of a round or slightly oval form. The articular surfaces are 
flat, the superior being directed backwards and a little outwards and upwards, the 
infei'ior forwards and a little inwards and downwards. The transverse processes 
are thick, strong, and of great length, directed obliquely backwards and outwards, 
presenting a clubbed extremity, lipped on its anterior part by a small concave 
surface, for articulation with the tubercle of a rib. The spinous processes are 
long, directed obliquely downwards, and terminated by a tubercle. 

The peculiar dorsal vertebrse are the first, ninth, tenth, eleventh, and twelfth 

(%-5)' 

5. — Peculiar Dorsal Vertebrae. 



'A^n entire facet aioi/e 
ADemifaeet ielow- 




'■iJif—AJJ emi-faeet alove 



Oive entire fa,eei 



An entire facet 
5-'^*i3il \N'> facet onTrans.Proo. 
which is Tti.di'me7ita/ry 



An entirefacet 
No facet onFrans. 211^ 
Infer. Artie. Proe 
aon vex aTid turned 
outward 



The First Dorsal Vertebra may be distinguished by the existence on each side 
of the body, of a single entire articular facet for the head of the first rib, and a 



10 



OSTEOLOGY. 



half facet for the upper half of the second. The upper surface of the body is like 
that of a cervical vertebra, being broad transversely, concave, and lipped on each 
side. The superior articular surfaces are oblique, and the spinous process thick, 
long, and almost horizontal. 

The Ninth Dorsal has no demi-facet below. 

The Tenth Dorsal has an entire articular facet at each side above; no demi- 
facet below. 

In the Eleventh Dorsal, the body approaches in its form to the lumbar; and 
has a single entire articular surface on each side. The transverse processes are 
very short, and have no articular surfaces at their extremities. 

The Tioelfth Dorsal has the same characters as the eleventh; but may be 
distinguished from it by the transverse processes being quite rudimentary, and the 
inferior articular surfaces being convex and turned outwards, like those of the 
lumbar vertebrae. 

The smallest dorsal vertebra is the fourth. The vertebrae increase in size from 
that point downwards to the twelfth, and upwards to the first. The spinous 
processes also, from the eighth downwards, become shorter, and are directed more 
horizontally. 

Characters of the Lumbar Vertebra. 

The Lumbar Vertebras (fig. 6) are the largest segments of the vertebral column. 
The Body is large, broad from side to side, flat above, and below, and thicker 

6. — A Lumbar Vertebra. 




before than behind. The pedicles are very strong, directed backwards; and the 
inferior intervertebral notches are of large size. The laminae are short, but broad 
and strong; and the foramen triangular, larger than in the dorsal, smaller than in 
the cervical region. The superior articular processes are concave, and directed 
backwards and inwards; the inferior, convex, and directed forwards and outwards. 
Projecting backwards from each of the superior articular processes is a tubercle, 
the representative of the transverse processes in the dorsal and cervical regions. 
The transverse processes are long, slender, directed a little backwards, and present, 
at the posterior part of their base, a small tubercle, which is directed downwards. 
The spinous processes are thick and broad, somewhat quadrilateral, horizontal in 
direction, and thicker below than above. 

The Fifth Lumbar vertebra is peculiar from having the body much thicker in 
front than behind, which accounts for the prominence of the sacro-vertebral 
articulation. 

Structure of the Vertebrce. The structure of a vertebra differs in different parts. 
The Body is composed almost entirely of light spongy cancellous tissue, having a 
thin coating of compact tissue on its external surface, permeated throughout its 
interior with large canals for the reception of veins, which converge towards a 



DEVELOPMENT OF THE VERTEBRAE. 



II 



single large irregular or several small apertures at the posterior part of the body 
of each bone. The arch and processes projecting from it have, on the contrary, 
an exceedingly thick covering of compact tissue. 
Development. Each vertebra 

7. — Development of a Vertebra. 
Sif S jyvimary eeyitres 



is formed of three primary cen- 
tres of ossification (fig. 7), one 
for each lamella and its pro- 
cesses, and one for the body. 
Those for the lamellae appear 
about the sixth week of foetal 
life, in the situation where the 
transverse processes afterwards 
project, the ossific granules 
shooting backwards to the spine, 
forwards to the body, and out- 
wards into the transverse and 
articular processes. That for 
the body makes its appearance 
in the middle of the cartilage 
about the eighth week. At 
birth, these three pieces are 
perfectly separate. During the 
first year, the lateral portions 
become partly united behind, 
in the situation of the spinous 
process, and thus the arch is 
formed. About the third year, 
the body is joined to the arch 
on each side, in such a manner, 
that the body is formed from 
the three original centres of 
ossification. Before puberty, 
no other changes occur, ex- 
cepting a gradual increase of 
growth of these primary cen- 
tres, the upper and under sur- 
face of the bodies, and the ends 
of the transverse and spinous 
processes, being tipped with 
cartilage, in which ossific gra- 
nules are not as yet deposited. 
At sixteen years (fig. 8), four 
secondary centres appear, one 
for the tip of each transverse 
process, and two (sometimes 
united into one) for the spinous 
process. At twenty-one years 
(fig. 9), two thin circular 
plates of bone are formed, one 
for the upper, and one for the 
under surface of the body. All 
these become joined, and the 
bone is completely formed 
about the thirtieth year of life. 
Exceptions to this mode of 
development occur in the first, 
second,and seventh cervical, and 
in those of the lumbar region. 




/JurBody (8'?.> iinck) 



f for each XavieUa (6 -■ week 1 



fy J4., Secondary Centre^' 




f/ ■foT eaeJi, 
TrcLJus.Proo. 



(iSy v.] 



9- 
lates 

1 for upver surfaci\ 
of lady L 

Irs 
\—ifor u?i({<}r stivfacA 



f 



bod' 



y 



o 




I o. — Axis. 

£1/ 3 eeiitres 

f ,fvr aritej'. aiv& f'^^y ■''] 

\ f for each ), , ,.^, 
^•^j''_, I \befo-ro birth 

IcjteraL mam) •' 



II. — Axis. 

S centTes 

Z for odo7iti>£d proa fetf-oioj 

/for each Zcbteral jno,ts 
' /for tody (6'^ mo.) 

12. — Lumbar Vertebra. 

^ axtdituynal ccjitrea 





for tvherel^s on Su.p. Artie. Proo. 



12 OSTEOLOGY. 

The Atlas (fig. lo) is developed by three centres. One (sometimes two) for 
the anterior arch, and one for each lateral mass. The ossific centres for each 
lateral mass commence before birth. At birth, the anterior arch is altogether 
cartilaginous, and the two lateral pieces are separated from one another behind. 
The nucleus for the anterior arch appears in the first year, between the second and 
third years the two lateral pieces unite, and join the anterior part at the age of 
five or six years. There is frequently a separate epiphysis for the rudimentary 
spine. 

The Axis (fig. ii) is developed hj five centres; three for its anterior part, and 
two for the posterior. The three anterior centres are, one for the lower part of 
the body, and two for the odontoid process and upper part of the body; the two 
posterior ones are, one for each lamella. At about the sixth month of foetal life, 
those for the body and odontoid process make their appearance, the two for the 
odontoid process joining before birth. At birth the bone consists of four pieces, 
two anterior and two lateral. At the fourth year the body and odontoid process are 
completely joined. 

The Seventh Cervical. The anterior or costal part of the transverse process 
of the seventh cervical, is developed from a separate osseous centre at about the 
sixth month of foetal life, and joins the body and posterior division of the trans- 
verse process between the fifth and sixth years. Sometimes this process continues 
as a separate piece, and becoming lengthened outwards, constitutes what is known 
as a cervical rib. 

The Lumbar VertebrcB (fig. 12) have two additional centres (besides those 
peculiar to the vertebrae generally), for the tubercles, which project from the back 
part of the superior articular processes. The transverse process of the first lumbar 
is sometimes developed as a separate piece, which may remain permanently uncon- 
nected with the remaining portion of the bone; thus forming a lumbar rib, a pecu- 
liarity which is sometimes, though rarely, met with. 

Progress of Ossification in the Spine generally. Ossification of the laminae 
of the vertebrae commences at the upper part of the spine, and proceeds gradually 
downwards; hence the frequent occurrence of spina bifida in the lower part of the 
spinal column. Ossification of the bodies, on the other hand, commences a little 
below the centre of the spinal column, and extends both upwards and downwards. 
Although, however, the ossific nuclei make their first appearance in the lower 
dorsal vertebrae (about the ninth), the lumbar and first sacral are those in which 
these nuclei are largest at birth. 

The False Vertebra. 

The False Vertebree consist of nine pieces, which are united so as to form two 
bones, five entering into the formation of the sacrum, four the coccyx. 

The Sacrum (fig. 13) is a large triangular bone, situated at the lower part 
of the vertebral column, and at the upper and back part of the pelvic cavity, 
where it is inserted like a wedge between the two ossa innominata; its upper 
part, or base, articulating with the last lumbar vertebra, its apex with the coccyx. 
The sacrum is curved upon itself, and placed very obliquely, its upper extremity 
projecting forwards, forming, with the last lumbar vertebra, a very prominent 
angle, called the promontory or sacro-vertebral angle, whilst its central part is 
directed backwards, so as to give increased capacity to the pelvic cavity. It pre- 
sents for examination an anterior and posterior surface, two lateral surfaces, a base, 
an apex, and a central canal. 

The Anterior Surface is deeply concave from above downwards, and slightly 
so from side to side. In the middle are seen four transverse lines, indicating the 
original division of the bone into five separate pieces. The portions of bone inter- 
vening between the lines correspond to the bodies of the vertebra?; they are slightly 
concave longitudinally, and diminish in size from above downwards. At the ex- 
tremities of each of these lines, are seen the anterior sacral foramina, analogous 
to the intervertebral foramina, four in number on each side, somewhat I'ounded in 



I 



SACRUM. 



13 



form, diminishing in size from above downwards, and directed outwards and for- 
wards; tliey transmit the anterior branches of tlie sacral nerves. External to 
these foramina, is the lateral mass, formed by the coalesced transverse processes 

13. — Saciiim, Anterior Surface. 



FTonwnioru 




of the sacral vertebrae, traversed by four broad shallow grooves, which lodge the 
anterior sacral nerves as they pass outwards, the grooves being separated by pro- 
minent ridges of bone, which give attachment to the slips of the Pyriformis 
muscle. 

The Posterior Surface (fig. 14) is convex, and much narrower than the ante- 
rior. In the middle line, are three or four tubercles, sometimes connected 
together, which represent the rudimentary spinous processes. Of these tubercles, 
the first is usually very prominent, and perfectly separate from the rest; the 
second, third, and fourth, existing either separate, or united into a ridge, which 
diminishes in size as it descends; the fifth, and sometimes the fourth, remaining 
undeveloped, and exposing below, the lower end of the sacral canal. External to 
the spinous processes on each side, are the lamincB, broad and well marked in the 
three first pieces; the lower part of the fourth, and the whole of the fifth, being 
undeveloped: in this situation the sacral canal is exposed. External to the laminae 
are a linear series of indistinct tubercles representing the articular processes; the 
upper pair are well developed; the second and third are small; the fourth and fifth 
(usually blended together) are situated on each side of the sacral canal: they are 
called the sacral cornua, and articulate with the cornua of the coccyx. External 
to the articular processes are the four posterior sacral foramina; they are smaller in 
size, and less regular in form than the anterior, and- transmit the posterior branches 
of the sacral nerves. On the outer side of the posterior sacral foramina are a 
series of tubercles, representing the rudimentary transverse processes. The first 
pair of transverse tubercles are very distinct, and correspond with each superior 



H 



OSTEOLOGY. 



angle of the bone; the second, small in size, enter into the formation of the sacro- 
iliac articulation; the third give attachment to the oblique sacro-iliac ligaments; 

14. — Sacrum Posterior Surface. 




Inner X cf £M 
l^u 't. sacral for. 



and the fourth and fifth to the great sacro-ischiatic ligaments. The interspace 
between the spinous and transverse processes of the sacrum, presents a wide shal- 
low concavity, called the sacral groove; it is continuous above with the vertebral 
groove, and lodges the origin of the Erector Spina3. 

The Lateral Surface, broad above, becomes narrowed into a thin edge below. 
Its upper half presents in front a broad ear-shaped surface for articulation with 
the ilium. This is called the auricular or ear-shaped surface, and in the fresh 
state is coated with cartilage. It is bounded posteriorly by deep and rough impres- 
sions, for the attachment of the sacro-iliac ligaments. The lower half is thin and 
sharp, and gives attachment to the greater and lesser sacro-ischiatic ligaments; 
below, it presents a deep notch, which is converted into a foramen by articulation 
with the transverse process of the upper piece " of the coccyx, and transmits the 
anterior branch of the fifth sacral nerve. 

The Base of the sacrum, which is broad and expanded, is directed upwards and 
forwards. In the middle is seen an oval articular surface, which corresponds with 
the under-surface of the body of the last lumbar vertebra, bounded behind by 
the large triangular orifice of the sacral canal. This orifice is formed behind by 
the spinous process and laminse of the first sacral vertebra, whilst projecting from 
it on each side are the superior articular processes; they are oval, concave, 
directed backwards and inwards, like the superior articular processes of a lumbar 
vertebra^ in front of each articular process ik an intervertebral notch, which 
forms the lower half of the last intervertebral foramen. Lastly, on each side of 
the articular surface is a broad and flat triangular surface of bone, called the al<s 



DEVELOPMENT OF SACRUM. 



15 



of the sacrum; they extend outwards, and are continuous on each side with the 
iliac fossee. 

The Apex, directed downwards and forwards, presents a small oval concave 
surface for articulation with the coccyx. 

The Sacral Canal runs throughout the greater part of the bone; it is large 
and triangular in form above, small and flattened from before backwards below. 
In this situation, its posterior wall is incomplete, from the non-development of 
the lamina and spinous processes. It lodges the sacral nerves, and is perforated 
by the anterior and posterior sacral foramina, through which these pass out. 

Structure. It consists of much loose spongy tissue within, invested externally 
by a thin layer of compact tissue. 

Differences in the Sacrum of the Male and Female. The sacrum in the 
female is usually wider than in the male, and it is much less curved, the upper half 
of the bone being nearly straight, the lower half presenting the greatest amount 
of curvature. The bone is also directed more obliquely backwards; which increases 
the size of the pelvic cavity, and forms a more prominent sacro-vertebral angle. 
In the male the curvature is more evenly distributed over the whole length of the 
bone, and is altogether greater than in the female. 

Peculiarities of the Sacrum. This bone, in some cases, consists of six instead 
of five pieces; occasionally the number is reduced to four. Sometimes the bodies 
of the first and second vertebrge are not joined, or the laminas and spinous processes 
have not coalesced with the rest of the bone. Occasionally the superior transverse 
tubercles are not joined to the rest of the bone on one or both sides; and, lastly, 
the sacral canal may be open for nearly the lower half of the bone, in consequence 
of the imperfect development of the laminas and spinous processes. The sacrum also 
varies considerably with respect to its degree of curvature. From the examination 
of a large number of skeletons, it 
would appear, that, in one set of cases, 
the anterior surface of this bone was 
nearly straight, the curvature, which 
was very slight, affecting only its lower 
end. In another set of cases, the bone 
was curved throughout its whole length, 
but especially towards its middle. In 
a third set, the degree of curvature was 
less marked, and aifected especially the 
lower third of the bone. 

Development of Sacrum (fig. 15). 
The sacrum, formed by the union of 
five vertebrae, has thirty-Jive centres 
of ossification. Each of the three first 
pieces is developed by seven centres; 
viz., three for the body, one for its cen- 
tral part, one for each epiphysal lamella 
on its upper and under surface, and one 
for each of the laminas: so far the first 
three sacral vertebrse, as well as the 
two last, are developed like the other 
pieces of the vertebral column. One 
of the characteristic points in the deve- 
lopment of this bone, consists in the 
existence of two additional centres for 
each of the first three pieces, which 
appear one on each side, close to the 
anterior sacral foramina, and correspond 
to the transverse processes of the lum- 
bar vertebrae. 



— Development of Sacrum. 

FoTTneA hv ivnion of 6 V&rteorcE. 
2 cJietraeterkstiyC points. 
1 £? 

a AAiitioTicbl ce/ritres 

the first 3 ipieces * 



burt./i 




a JLjifphiisayL 
for each laterctl surTa.ce 



LcLmcnce 
rfct 



at 25 " 




i6 



OSTEOLOGY. 



Each of the two last pieces is developed by five centres: three for the body; viz., 
one for its central part, and one for each of the epiphy sal lamellas ; and one for each 
of the laminae. 

A second characteristic point in the development of this bone consists in each 
lateral surface of the sacrum being developed by two epiphysal points, one for the 
auricular surface, and one for the thin lateral border of the bone. 

Period of Development. At about the eighth or ninth week of foetal life, ossifi- 
cation of the central part of the bodies of the three first vertebrae commences, and, 
at a somewhat later period, that of the two last. Between the sixth and eighth 
months, ossification of the lamellte takes place; and at about the same period the 
characteristic osseous tubercles for the three first sacral vertebrse make their appear- 
ance. The lateral pieces join to form the arch, and are united to the bodies, first, 
in the lowest vertebrae. This occurs about the second year, the uppermost seg- 
ment appearing as a single piece about the fifth or sixth year. About the six- 
teenth year the epiphysal lamellae for the bodies are formed; and between the 
eighteenth and twentieth years those for each lateral surface of the sacrum make 
their appearance. At about this period, the two last segments are joined to one 
another; and this process gradually extending upwards, all the pieces become united, 
and the bone completely formed from the twenty-fifth to the thirtieth year of life. 

Articulations. With four bones; the last lumbar vertebra, coccyx, and the two 
ossa innominata. 

Attacliment of Muscles. The Pyriformis and Coccygeus on either side, behind 
the Gluteus maximus and Erector Spinae. 

The Coccyjj;. 

The Coccyx {kokkv^, cuckoo), so called from resembling a cuckoo's beak, 
(fig. 1 6) is formed of four small segments of bone, the most rudimentary parts of 
the vertebral column. Of these, the first is the largest, and often exists as a 

separate piece, the three last diminishing in size from 
above downwards, are blended together so as to form 
a single bone. The gradual diminution in the size of 
the pieces gives this bone a triangular form, articula- 
ting by its base with the apex of the sacrum. It 
Ti-a/if. presents for examination an anterior and posterior 
^''""^ surface, two borders, a base, and an apex. The an- 
terior surface is slightly concave, and marked with 
three transverse grooves, indicating the points of junc- 
tion of the diiferent pieces. It has attached to it the 
anterior sacro-coccygeal ligament and levator ani mus- 
cle, and supports the lower end of the rectum. 
The posterior surface is convex, marked by grooves 
similar to those on the anterior surface, and presents 
on each side a linear row of tubercles, which repre- 
sent the articular processes of the coccygeal vertebrae. 
Of these, the superior pair are very large; they are 
called the cornua of the coccyx, and projecting up- 
wards, articulate with the cornua of the sacrum, the 
junction between these two bones completing the 
fifth sacral foramen for the transmission of the poste- 
rior branch of the fifth sacral nerve. The lateral 
borders are thin, and present a series of small emi- 
nences, which represent the transverse processes of 
the coccygeal vertebrae. Of these, the first on each 
side is of large size, flattened from before backwards, 
and often ascends upwards to join the lower part of 
the thin lateral edge of the sacrum, thus completing 
the fifth sacral foramen: the others diminish in size 



1 6. — Coccyx. 

COCCYX 
Cornua, 




Rudirrv, 



jd-Tzterior jS%CT'faee 







rfoiCB 



THE SPINE. 



17 



17. — Lateral View of Spine. 



IV Dorsal 



fSr- 



I'J'J , 



1^." Lumbar ~ 



4-1 



I 



from above downwards, and are often wanting. 
The borders of the coccyx are narrow, and 
give attachment on each side to the sacro- 
sciatic ligaments and Coccygeus muscle. The 
base presents an oval surface for articulation 
with the sacrum. The apex is rounded, and 
has attached to it the tendon of the external 
Sphincter ani muscle. It is occasionally bifid, 
and sometimes deflected to one or other side. 

Development. The coccyx is developed by 
four centres, one for each piece. Occasionally 
one of the three first pieces of this bone is de- 
veloped by two centres, placed side by side. 
The periods when the ossific nuclei make their 
appearance is the following: in the first seg- 
ment, at birth; in the second piece, at from 
five to ten years; in the third, from ten to 
fifteen years; in the fourth, from fifteen to 
twenty years. As age advances, these various 
segments become united in the following order: 
the two first pieces join, then the third and 
fourth; and, lastly the bone is completed by 
the union of the second and third. At a late 
period of life, especially in females, the coccyx 
becomes joined to the end of the sacrum. 

Articulation. With the sacrum. 

Attachment of Muscles. On either side, the 
Coccygeus; behind, the Gluteus maximus; at 
its apex, the Sphincter ani; and in front, 
the Levator ani. 

Of the Spine in general. — The spinal 
column, formed by the junction of the verte- 
brae, is situated in the median line, at the pos- 
terior part of the trunk: its average length is 
about two feet two or three inches; the lum- 
bar region contributing seven parts, the dor- 
sal eleven, and the cervical five. 

Viewed in front, it presents two pyramids 
joined together at their bases, the upper one 
being formed by all the true vertebrae from the 
second cervical to the last lumbar; the lower 
one by the false vertebras, the sacrum, and 
coccyx. Viewed somewhat more closely, the 
uppermost pyramid is seen to be formed of 
three smaller pyramids. Of these the most 
superior one consists of the six lower cervical 
vertebras, its apex being formed by the axis or 
second cervical, its base by the first dorsal. 
The second pyramid, which is inverted, is 
formed by the four upper dorsal vertebrae, the 
base being at the first dorsal, the smaller end 
at the fourth. The third pyramid commences 
at the fourth dorsal, and gradually increases 
in size to the fifth lumbar. 

Viewed laterally (fig. 1 7), the spinal column 
presents several curves. In the dorsal region, 
the seat of the principal curvature, the spine 
c 



1 8 OSTEOLOGY. 

is concave anteriorly; whilst in the cervical and lumbar regions it is convex an- 
teriorly, especially in the latter. The spine has also a slight lateral curvature, 
the convexity of which is directed towards the right side. This is most probably 
produced, as Bichat first explained, from the effect of muscular action; most persons 
using the right arm in preference to the left, especially in making long-continued 
efforts, when the body is curved to the right side. In support of this explanation, 
it has been found by Beclard, that in one or two individuals who were left-handed, 
the lateral curvature was directed to the left side. 

The spinal column presents for examination an anterior, a posterior, and two 
lateral surfaces, a base, summit, and vertebral canal. 

The anterior surface presents the bodies of the vertebrae separated in the fresh 
state by the intervertebral discs. The bodies are broad in the cervical region, 
narrow in the upper part of the dorsal, and broadest in the lumbar region. The 
whole of this surface is convex transyersely, concave from above downwards in 
the dorsal region, and convex in the same direction in the cervical and lumbar 
regions. 

The posterior surface presents in the median line the spinous processes. These 
are short, horizontal, with bifid extremities in the cervical region. In the dorsal 
region, they are directed obliquely above, assume almost a vertical direction in the 
middle, and are horizontal, like the spines of the lumbar vertebrce, below. They 
are separated by considerable intervals in the loins, by narrower intervals in the 
neck, and are closely approximated in the middle of the dorsal region. On either 
side of the spinous processes; extending the whole length of the column, is the 
vertebral groove, formed by the laminae in the cervical and lumbar regions, where 
it is shallow, and by the laminae and transverse processes in the dorsal region, 
where it is deep and broad. In the recent state, these grooves lodge the deep 
muscles of the back. External to the vertebral grooves are the articular processes, 
and still more externally the transverse processes. In the dorsal region, these 
latter processes stand backwards, on a place considerably posterior to the same pro- 
cesses in the cervical and lumbar regions. The transverse processes in certain 
regions of the spine are formed of two different parts, or segments. In the cer- 
vical region, these two segments are distinct; the one arising from the side of the 
body, the other from the pedicle of the vertebra; and these uniting, enclose the 
vertebral foramen. In the dorsal region, the anterior segment is wanting; the pos- 
terior segment retaining the name of the transverse process. In the lumbar region, 
the anterior segments (which are largely developed) are called the transverse 
processes; but, in reality, they are lumbar ribs, the posterior segments or true trans- 
verse processes existing in a rudimentary state, and being developed from the supe- 
rior articular processes, as in the cervical region. In the cervical region, the 
transverse processes are placed in front of the articular processes, and between the 
intervertebral foramina. In the lumbar, they are placed also in front of the arti- 
cular processes, but behind the intervertebral foramina. In the dorsal region, 
they are posterior both to the articular processes and foramina. 

The lateral surfaces are separated from the posterior by the articular processes 
in the cervical and lumbar regions, and by the transverse processes in the dorsal. 
These surfaces present in front the sides of the bodies of the vertebrae, marked in 
the dorsal region by the facets for articulation with the heads of the ribs. More 
posteriorly are the intervertebral foramina, formed by the juxtaposition of the inter- 
vertebral notches, oval in shape, smallest in the cervical and upper part of the dorsal 
regions, and gradually increasing in size to the last lumbar. They are situated 
between the transverse processes in the neck, and in front of them in the back and 
loins, and transmit the spinal nerves. The base of the vertebral column is formed 
by the under surface of the body of the fifth lumbar vertebra, and the summit by 
the upper surface of the atlas. The vertebral canal follows the different curves of 
the spine; it is largest in those regions in which the spine enjoys the greatest free- 
dom of movement, as in the neck and loins, where it is wide and triangular; and 
narrow and rounded in the back, where motion is more limited. 



OCCIPITAL BONE. 



19 



THE SKULL. 

The Skull is divided into two parts, the Cranium and the Face. The Cranium is 
composed of eight hones; viz., the occipital, two parietal, frontal, two temporal, 
sphenoid, and ethmoid. The Face is composed oi fourteen bones; viz., the two 
nasal, two superior maxillary, two lachrymal, two malar, two palate, two inferior 
turbinated, vomer, inferior maxillary. The ossicula auditus, the teeth, and Wor- 
mian bones, are not included in this enumeration. 

Occipital. 

Two Parietal. 

r ri . ' or J Frontal. 

Lramum, 5 bones. ( ~ ^ , 

' ' Two Temporal. 

Sphenoid. 

Ethmoid. 

Two Nasal. 

Two Superior Maxillary. 
Two Lachrymal. 
Two Malar. 
Two Palate. 

Two Inferior Turbinated. 
Vomer. 
^ Inferior Maxillary. 

The Occipital Bone. 

The Occipital Bone (fig. 18) is situated at the posterior and inferior part of the 
cranium, is trapezoid in form, curved upon itself, and presents for examination 
two surfaces, four borders, and four angles. 

18. — Occipital Bone. Outer Surface. 



Skull, 22 bones. ( 



Face, 14 bones. 




a/£/uryn-jr. 



C 2 



20 OSTEOLOGY. 

External Surface. Midway between the summit of tlie bone and the posterior 
margin of the foramen magnum is a prominent tubercle, the external occipital pro- 
tuberance, for the attachment of the ligamentum nuchas; and descending from it, 
as far as the foramen, a vertical ridge, the external occipital crest. Passing out- 
wards from the occipital protuberance on each side are two semicircular ridges, 
the superior curved lines; and running parallel with these fx'om the middle of the 
crest, are the two inferior curved lines. The surface of the bone above the supe- 
rior curved lines presents on each side a smooth surface, which, in the recent 
state, is covered by the occipito-frontalis muscle, whilst the ridges, as well as the 
surfaces of the bone between them, serve for the attachment of numerous muscles. 
The superior curved line gives attachment internally to the Trapezius, externally 
to the Occipito-frontalis, and Sterno-cleido mastoideus; to the extent shewn in the 
figure. The depressions between the curved lines to the Complexus internally, 
the Splenius capitis and Obliquus superior externally. The inferior curved line, 
and the depressions below it, afford insertion to the Rectus capitis posticus, major 
and minor. 

The foramen magnum is a large aperture, with rounded shelving margins, oblong 
in form, and wider behind than in front; it transmits the spinal cord and its mem- 
branes, the spinal accessory nerves, and the vertebral arteries. On each side of the 
foramen magnum are the occipital condyles, for articulation with the Atlas; they 
are convex articular surfaces, oval in form, and directed downwards and out- 
wards; they approach each other anteriorly, and encroach more upon the anterior 
than the posterior segment of the foramen. On their inner surface is a rough 
tubercle, for the attachment of the check ligaments ; whilst external to them is a 
rough tubercular prominence, the transverse, or jugular process, channelled in 
front by a deep notch, which forms part of the jugular foramen. The under 
surface of this process affords attachment to the Rectus capitis lateralis muscle; 
its upper or cerebral surface presents a deeply curved groove, which lodges part 
of the lateral sinus, whilst its prominent extremity is marked by a quadrilateral 
rough surface, covered with cartilage in the fresh state, and articulating with a 
similar surface on the petrous portion of the temporal bone. On the outer side of 
each condyle is a depression, the anterior condyloid fossa, perforated at the bottom 
by the anterior condyloid foramen. This foramen (sometimes double) is directed 
downwards outwards, and forwards, and transmits the lingual nerve. Behind each 
condyle is seen an irregular fossa, also perforated at the bottom by a foramen, the 
posterior condyloid, for the transmission of a vein to the lateral sinus. This fossa 
and foramen are less regular in form and size than the anterior, and do not always 
exist. Sometimes they are found on one side only, and sometimes are altogether 
absent. In front of the foramen magnum is the basilar process, somewhat quadri- 
lateral in form, wider behind than in front; its under surface, which is rough, 
presenting in the median line a tubercvilar ridge, the pharyngeal spine, for the 
attachment of the tendinous raphe and Superior constrictor of the pharynx; and 
on each side of it, rough depressions for the attachment of the Recti capitis 
antici, major and minor. 

The Internal or Cerebral Surface (fig. 19) is deeply concave. The occipital 
part is divided by a crucial ridge into four fossse. The two superior, the smaller, 
receive the posterior lobes of the cerebrum, and present eminences and depressions 
corresponding to their convolutions. The two inferior, which receive the lateral 
lobes of the cerebellum, are larger than the former, and comparatively smooth; 
both are marked by slight grooves for the lodgment of arteries. At the point of 
meeting of the four divisions of the crucial ridge is an eminence, the internal 
occipital protuberance, which rarely corresponds to that on the outer surface. 
From this eminence, the superior division of the crucial ridge, called sulcus longi- 
tudinalis, runs upwards to the superior angle of the bone; it presents a deep 
groove for the superior longitudinal sinus, whilst its margins give attachment to 
the falx cerebri. The inferior division, the internal occipital crest, runs to the 
margin of the foramen magnum, on the edge of which it becomes gradually lost: 



OCCIPITAL BONE. 



21 



this ridge, which is bifurcated below, serves for the attachment of the falx 
cerebelli, and is slightly grooved for the lodgment of the occipital sinuses. The 
transverse grooves {sulci transver sales) pass outwards to the lateral angles; they 
are deeply grooved, for the lodgment of the lateral sinuses, their prominent margins 
affording attachment to the tentorium cerebelli. At the point of meeting of these 
four grooves is a depression for the torcular Herophili, placed a little to the right 
of the internal occipital protuberance. In the centre of the basilar portion of the 
bone is the foramen magnum, and above its margin, but nearer its anterior than 
its posterior part, the internal openings of the anterior condyloid foramina; the 
internal openings of the posterior condyloid foramina being a little external and 
posterior to them, and protected above by a small arch of bone. In front of the 
foramen magnum is the basilar process, presenting a shallow longitudinal depres- 
sion, the basilar groove, for supporting the medulla oblongata; whilst on its lateral 

19. — Occipital Bone. Inner Surface. 

S ufi e rio -p Amg I e 
S u h 




Inferior An alp V^ 

margins is observed a narrow channel on each side, which, when united with 
a similar channel on the petrous portion of the temporal bone, forms a groove, the 
inferior petrosal, which lodges the inferior petrosal sinus. 

Angles. The superior angle is acute, and is received into the interval between 
the posterior superior angles of the two parietal bones: it corresponds with that 
part of the head in the foetus which is called the posterior fontanelle. The infe- 
rior angle is represented by the square-shaped surface of the basilar process. At 
an early period of life, a layer of cartilage separates this part of the bone from the 
sphenoid; but in the adult, the union between them is osseous. The lateral 



22 



OSTEOLOGY. 



angles correspond to the outer ends of the transverse grooves, and are received into 
the interval between the posterior inferior angles of the parietal and the mastoid 
portion of the temporal. 

Borders. The superior extends on each side from the superior to the lateral angle, 
is deeply serrated for articulation with the parietal bone, and forms by this 
union the lambdoid suture. The inferior border extends from the lateral to 
the inferior angle; its upper half is rough, and articulates with the mastoid por- 
tion of the temporal, forming the masto-occipital suture: the inferior half articu- 
lates with the petrous portion of the temporal, forming the petro-occipital suture: 
these two portions are separated from one another by the jugular process. In 
front of this process is a notch, which, with a similar one on the petrous portion 
of the temporal, forms the foramen lacerum posterius. This notch is often subdi- 
vided into two parts by a small process of bone. 

Structure. The occipital bone consists of two compact laminae, called the outer 
and inner tables, having between them the diploic tissue; this bone is especially 
thick, at the ridges, protuberances, condyles, and basilar process; whilst at the 
bottom of the fossae it is thin, semi-transparent, and destitute of diploe. 

Development (fig 2o). The occipital bone has seven centres of development; 
four for the posterior or occi- 



-Development of Occipital Bone. 

Jit/ Y centres 



at IvriJi 

t]?,c Jf- pieces 

sevoLrate 




If, -for oooiviicul 
portion 



1 for each condylo 
jyorivon 

oojuiiLwt portion 



:,d 



pital part, one for the basilar 
portion ; and one for each con- 
dyloid portion. 

The four centres for the 
occipital portion are arranged 
in pairs above and below the 
occipital protuberance, and 
appear about the tenth week 
of foetal life; the inferior pair 
make their appearance first, 
and join ; the superior pair be- 
come also united: these two 
segments now join together, 
and form a single piece. The 
condyloid portions then os- 
sify; and, lastly, the basilar 

portion. At birth, the bone consists of these four parts, separate from one another, 
the posterior being fissured in the direction of the original segments. At about 
the fourth year, the occipital and the two condyloid pieces join; and at about the 
sixth year the bone consists of a single piece. At a later period, between the 
eighteenth and twenty-fifth years, the occipital and sphenoid become united, 
forming a single bone. 

Articulations. With six bones; two parietal, two temporal, sphenoid, and Atlas. 

Attachment of Muscles. To the superior curved line are attached the Occipito- 
frontalis. Trapezius, and Sterno-cleido-mastoid. To the space between the curved 
lines, the Complexus, Splenius capitis, and Obliquus superior; to the inferior curved 
line, and the space between it and the foramen magnum, the Rectus posticus ma- 
jor and minor; to the transverse process, the Rectus lateralis; and to the basilar 
process, the Recti antici majores and minores, and Superior Constrictor of the 
pharynx. 

The Parietal Bones. 

The Parietal Bones form the sides and roof of the skull; they are of an irre- 
gular quadrilateral form, and present for examination two surfaces, four borders, 
and four angles. 

Surfaces. The External Surface (fig. 2l)is convex, smooth, and presents about its 
centre an eminence, called the parietal eminence, which indicates the point where 
ossification commenced. Crossing the centre of the bone in an arched direction 



PARIETAL BONE. 



23 



is a curved ridge, the temporal ridge, for the attachment of the temporal fascia. 
Above this ridge, the surface of the bone is rough and porous, and covered by the 
aponeurosis of the Occipito-frontalis; below it the bone is smooth, and affords 

2 1 . — Left Parietal Bone. External Surface. 



'Pcirte.teiol rm , 







^^f^pORAL imSQ^^ 







■ ^if- 



attachment to the Temporal muscle. At the back part of the superior border is a 
small foramen, the parietal foramen, which transmits a vein to the superior longi- 
tudinal sinus. Its existence is not constant, and its position varies considerably. 

The Internal Surface (iig. 22), concave, presents numerous eminences and 
depressions for lodging the convolutions of the brain, and minute furrows for the 
ramifications of the meningeal arteries: these run upwards and backwards from 
deep grooves, which commence in the anterior inferior angle, and at the central 
and posterior part of the lower border of the bone. Along the upper margin is 
part of a shallow groove, which, when joined to the opposite parietal, forms a 
channel for the superior longitudinal sinus, the elevated edges of which afford 
attachment to the falx cerebri. Near the groove are seen several depressions; they 
lodge the Pacchionian bodies. The internal opening of the parietal foramen is 
also seen when that aperture exists. 

Borders. The superior, the longest, is dentated to articulate with its fellow 
of the opposite side, forming the sagittal suture. The inferior is divided into 
three parts; of these, the anterior is thin and pointed, bevelled at the expense of 
the outer surface, and overlapped by the tip of the great wing of the sphenoid; 
the middle portion is arched, bevelled at the expense of the outer surface, and 
overlapped by the squamous portion of the temporal; the posterior portion being 
thick and serrated for articulation with the mastoid portion of the temporal. 
The anterior border, deeply serrated, is bevelled at the expense of the outer sur- 
face above, and of the inner below; it articulates with the frontal bone, forming 



24 



OSTEOLOGY. 



the coronal suture. The posterior border, deeply denticulated, articulates with 
the occipital, foi-ming the lambdoid suture. 

Angles. The anterior superior, thiu and pointed, corresponds with that portion 
of the skull which in the foetus is membranous, and is called the anterior fon- 
tanelie. The anterior inferior angle is thin and lengthened, being received in 
the interval between the great wing of the sphenoid and the frontal. Its inner 
surface is marked by a deep groove, sometimes a canal, for the middle meningeal 

22. — Left Parietal Bone. Internal Surface. 



Post.jSup. -^'^A^ 




K,,%,Amt. Sup 
Ancfle 



Posl.Iyifer.An^l^ 



Alii. Infer An,cil& 



artery. The posterior superior angle corresponds with the junction of the sagittal 
and lambdoid sutures. In the foetus this part of the skull is membranous, and is 
called the posterior fontanelle. The posterior inferior articulates with the mas- 
toid portion of the temporal bone, and presents on its inner surface a broad 
shallow groove for the lateral sinus. 

Development. The parietal bone is developed by one centre, which corresponds 
with the parietal eminence, and makes its first appearance about the fifth or sixth 
week of foetal life. 

Articulations. With five bones; the opposite parietal, the occipital, frontal, 
temporal, and sphenoid. 

Attachment of Muscles. To one only, the Temporal. 

The Frontal Bone. 

This bone, which resembles a cockle-shell in form, consists of two portions — 
a vertical or frontal portion, situated at the anterior part of the cranium, forming 
the forehead; and a horizontal or orhito-nasal portion, which enters into the for- 
mation of the roof of the orbits and nose. 

Vertical Portion. External Surface (fig. 23). In the median line, traversing 
the bone from the upper to its lower part, is a slightly elevated ridge, and in 
young subjects a suture, which represents the point of union of its two lateral 



FRONTAL BONE. 



25 



halves: in the fidult, this suture usually disappears. On either side of this ridge, 
a little below the centre of the bone, is a rounded eminence, the frontal eminence, 
which indicates the point where ossification commenced. The whole surface of 
the bone above this part is smooth, and covered by the aponeurosis of the Occipito- 
frontalis muscle. Below the frontal protuberance, and separated from it by a 
slight groove, is the superciliary ridge, a curved eminence, broad internally where 
it is continuous with the nasal eminence, less distinct externally as it arches 
outwards. Beneath the superciliary ridge is the supra-orbital arch, a curved and 
prominent margin, which forms the upper boundary of the orbit, and separates the 
vertical from the horizontal portion of the bone. At the inner third of this arch 
is a notch, sometimes converted into a foramen by a bony process or ligament, and 

23. — Frontal Bone. Outer Surface. 




^Internal Easte'r-nat 

Anqalar Jiroc, Ancfular hroc. 



iXasal Q Shine 



called the supra- orbital notch or foramen. It transmits the supra-orbital artery, 
veins, and nerve. The supra-orbital arch terminates externally in the external 
angular process, and internally in the internal angular process. The external 
angular is a strong prominent process, which articulates with the malar: running 
upwards and backwards from it is a sharp curved line, the temporal ridge, for the 
attachment of the temporal fascia; and beneath it a slight concavity, that forms 
part of the temporal fossa, and gives origin to the Temporal muscle. The internal 
angular processes are less marked than the external, and articulate with the 
lachrymal bones. Between the two is a rough, uneven interval, called the nasal 
notch, which articulates in the middle line with the nasal, and on either side with 
the nasal process of the superior maxillary bones. 

Vertical Portion, Internal Surface (fig. 24). Along the middle line of this 
surface is a vertical groove, sulcus longitudinalis, the edges of which unite below 
to form a ridge, the frontal crest; the groove lodges the superior longitudinal 
sinus, whilst its edges afford attachment to the falx cerebri. The crest terminates 
below, at a small opening, the foramen coecum. which is generally completed be- 



26 



OSTEOLOGY. 



hind by the ethmoid; it lodges a process of the falx cerebri, and occasionally 
transmits a small vein from the nose to the superior longitudinal sinus. On 
either side of the groove, the bone is deeply concave, presenting eminences and 
depressions for the convolutions of the brain, and numerous small furrows for 
lodging the ramifications of the anterior meningeal arteries. Several small, irregular 
fossae are also seen on either side of the groove, for the reception of the Pacchionian 
bodies. 

Horizontal Portion. External Surface. This portion of the bone consists ot 
two thin plates, which form the vault of the orbits, separated from one another by 
the ethmoidal notch. Each orbital vault consists of a smooth, concave, trian- 
gular plate of bone, marked at its anterior and external part (immediately beneath 
the external angular process) by a shallow depression, the lachrymal fossa, for 
lodging the lachrymal gland; and at its anterior and internal part, by a de- 
pression, sometimes a tubercle, for the ' attachment of the fibrous pulley of the 
superior oblique muscle. The ethmoidal notch separates the two orbital plates: it 

24. — Frontal Bone. Inner Surface. 

,r/^^• 




with Swp.Maxill. 

with. Na/sn 7 
VL'ith Ferpendieular ylute of Etlnnoid 



FrontaZ S'inus 



EjLpandod hase of Najftcul SjJiyie, 
formtnq part trf Moirf^ ef ISjse 



is quadrilateral; and filled up, when the bones are united, by the cribriform plate 
of the ethmoid. The edges of this notch present several half-cells, which, when 
united with corresponding half-cells on the upper surface of the ethmoid, com- 
plete the ethmoidal cells : two grooves are also seen crossing these edges trans- 
versely; they are converted into canals by articulation with the ethmoid, and are 
called the anterior and posterior ethmoidal canals; they open on the inner wall 
of the orbit. In front of the ethmoidal notch is the nasal spine, a sharp eminence, 
which projects downwards and forwards, and the grooved base of which forms 
part of the roof of the nose. It articulates in front with the crest of the nasal 
bones, behind with the perpendicular plate of the ethmoid. On either side of this 
spine are the openings of the frontal sinuses. These are two irregular cavities, 



TEMPORAL BONE. 



27 



which extend upwards and outwards, a variable distance, between the two tables 
of the skull, and are separated from one another by a thin bony septum. They 
give rise to the prominences above the root of the nose, called the nasal 
eminences. In the child they are absent, and they become gradually developed 
as age advances. They are lined by mucous membrane, and communicate with 
the nose by the infundibulum. 

The Internal Surface of the Horizontal Portion presents the convex upper 
surfaces of the orbital plates, separated from each other in the middle line by the 
ethmoidal notch, and marked by eminences and depressions for the convolutions of 
the anterior lobes of the brain. 

Borders. The border of the vertical portion is thick, strongly serrated, bevelled 
at the expense of the internal table above, where it rests upon the parietal, at the 
expense of the external table at each side, where it receives the lateral pressure 
of those bones: this border is continued below, into a triangular rough surface, 
which articulates with the great wing of the sphenoid. The border of the 
horizontal portion is thin, bevelled at the expense of the internal table, and 
articulates with the lesser wing of the sphenoid. 

Structure. The vertical portion consists of diploic tissue, contained between 
two compact laminae, the bone being especially thick in the situation of the nasal 
eminences and external angular processes. The horizontal portion is thinner, 
more translucent, and composed entirely of compact tissue. 

Development. The frontal bone is developed by two centres, one for each lateral 
half, which make their appearance, at an early period of foetal life, in the situation 
of the orbital arches. At birth it consists of two pieces, which afterwards become 
united along the middle line, by a suture which runs from the vertex to the root 
of the nose. This suture becomes obliterated within a few years after birth; but 
it occasionally remains throughout life. 

Articulations. With twelve bones ; two parietal, sphenoid, ethmoid ; two nasal, 
two superior maxillary, two lachrymal, and two malar. 

Attachment of Muscles. To three pairs; the Corrugator supercilii. Orbicularis 
palpebrarum, and Temporal. 

The Temporal Bones. 

The Temporal bones, situated at the side and base of the skull, present for 
examination a squamous, mastoid, and petrous portion. 

The Squamous Portion (fig. 25), the most anterior and superior part of the 
bone, is flattened and scale-like in form, thin and translucent in texture. Its 
outer surface is smooth, convex, and grooved for the deep temporal arteries; it 
affords attachment to the fibres of the Temporal muscle, and forms part of the tem- 
poral fossa. At its back part may be seen a curved ridge — part of the temporal 
ridge; it serves for the attachment of the temporal fascia, limits the origin of 
the Temporal muscle, and marks the boundary between the squamous and mastoid 
portions of the bone. Projecting from the lower part of the squamous portion, 
is a long and arched process of bone, the zygomatic process. It is at first 
directed outwards, its two surfaces looking upwards and downwards; it then 
appears as if twisted upon itself, and takes a direction forwards, its surfaces now 
looking inwards and outwards. The superior border of this process is long, thin, 
and sharp, and serves for the attachment of the temporal fascia. The inferior, 
short, thick, and arched, has attached to it some of the fibres of the Masseter 
muscle. Its outer surface is convex and subcutaneous. Its inner, concave, also 
affords attachment to the Masseter. The extremity, broad and deeply serrated, 
articulates with the malar bone. This process is connected to the temporal bone 
by three divisions, called the roots of the zygomatic process, an anterior, middle, 
and posterior. The anterior, which is short, but broad and strong, runs trans- 
versely inwards into a rounded eminence, the eminentia articularis. This eminence 
forms the front boundary of the glenoid fossa, and in the recent state is covered 
with cartilage. The middle root runs obliquely inwards, and terminates at the 



28 



OSTEOLOGY. 



edge of a well-marked fissure, the Glaserian fissure; whilst the posterior, which 
is strongly marked, runs from the upper border of the zygoma, in an arched 
direction, upwards and backwards, forming the posterior part of the temporal 
ridge. At the junction of the anterior and middle roots is a projection, called the 
tubercle, for the attachment of the external lateral ligament of the lower jaw; 
and between these roots is a large oval depression, forming part of the glenoid 
fossa, for the reception of the condyle of the lower jaw. This fossa is bounded 
in front by the eminentia articularis; behind, by the vaginal process; and exter- 
nally by the auditory process; and is divided into two parts by a narrow slit, the 
Glaserian fissure: the anterior part, formed by the squamous portion of the bone 
is smooth, covered in the recent state with cartilage, and articulates with the 
condyle of the lower jaw; the posterior part, rough and uneven, and formed 
chiefly by the vaginal process of the petrous portion, lodges part of the parotid 
gland. The Glaserian fissure, dividing' the two, leads into the tympanum; it 

25. — Left Temporal Bone. Outer Surface. 




Masto'i d/ -forajnefi 



lodges the processus gracilis of the malleus, and transmits the laxator tympani 
muscle and the anterior tympanic artery. The chorda tympani nerve passes 
through a separate canal parallel to the Glaserian fissure, on the outer side of the 
Eustachian tube, in the retiring angle between the squamous and petrous portions 
of the temporal bone. 

The internal surface of the squamous portion (fig. 26) is concave, presents nu- 
merous eminences and depressions for the convolutions of the cerebrum, and two 
well marked grooves for the branches of the middle meningeal artery. 

Borders. The superior border is thin, bevelled at the expense of the internal 
surface, so as to overlap the lower border of the parietal bone, forming the 
squamous suture. The anterior inferior border is thick, serrated, and bevelled 
alternately at the expense of the inner and outer surfaces, for articulation with the 
great wing of the sphenoid. 



TEMPORAL BONE. 



29 



The Mastoid Portion is situated at the posterior part of the bone, its outer 
surface is rough, and perforated by numerous foramina, one of these, of large size, 
situated at the posterior border of the bone, is termed the mastoid foramen, it 
transmits a vein to the lateral sinus and a small artery. The position and size 
of this foramen are very variable, being sometimes situated in the occipital bone, 
or in the suture between it and the occipital. The mastoid portion is continued 
below into a conical projection, the mastoid process, the size and form of which 
varies considerably in different individuals. This process serves for the attach- 
ment of the Sterno-mastoid, Splenius capitis and Trachelo-mastoid (see fig. 25); 
on the inner side of the mastoid process is a deep groove, the digastric fossa, for 
the attachment of the Digastric muscle, and running parallel with it, but more 
internal, the occipital groove, which lodges the occipital artery. The internal 
surface presents a deeply curved groove which lodges the lateral sinus, and into 
it may be seen opening the mastoid foramen. 

26. — Left Temporal Bone, Inner Surface. 



rie ta I 




Dcprcvsivn for Dara-nvatenr 
]}Ieatas yiv^iCarins iriiei-nus 



-Bmi-ntiicc Jot S'uperCor S6mti:ircuia,T Ca.7ia0 

Jliatus JFaUopw 

O^oniTifj for iSivalhr Petrosal JVcri-c 
JicoressioTi fitr Casseriaji gaiifflto-n 
Bristle passed thTOiujh Carotid Canal 



Borders. The superior border of the mastoid portion is rough and serrated for 
articulation with the posterior inferior angle of the parietal bone. The posterior 
border, also uneven and serrated, articulates with the inferior border of the occi- 
pital bone between its lateral angle and jugular process. 

The Petrous Portion, so named from its extreme density and hardness, is a 
pyramidal process of bone, wedged in at the base of the skull between the sphenoid 
and occipital bones. Its direction from without is forwards, inwards, and a little 
downwards. It presents for examination a base, an apex, three surfaces, and 
three borders. The base is applied against the internal surface of the squamous 
and mastoid portions, its upper half being concealed, but its lower half is exposed 
by their divergence, which brings into view the oval expanded orifice of a canal 
leading into the tympanum, the meatus auditorius externus. This canal is situated 
between the mastoid process and the posterior and middle roots of the zygoma; its 
upper margin is smooth and rounded, its lower surrounded by a curved plate of 



30 OSTEOLOGY. 

bone, tlie auditory process, the free margin of which is rough for the attachment 
of the cartilage of the ear. The apex of the petrous portion, rough and uneven, 
is received into the angular interval between the spinous process of the sphenoid, 
and the basilar process of the occipital; it presents the anterior orifice of the 
carotid canal, and forms the posterior and external boundary of the foramen 
lacerum medium. The anterior surface (fig. 26) of the petrous portion, forms the 
posterior boundary of the middle fossa of the skull. This surface is continuous 
with the squamous portion, to which it is united by a suture, the temporal suture, 
the remains of which are distinct at a late period of life. Proceeding from the 
base to the apex, this surface presents five points for examination. i. An 
eminence which indicates the situation of the superior semicircular canal. 2. A 
shallow groove, sometimes double, leading backwards to an oblique opening, the 
hiatus Fallopii, for the passage of the petrosal branch of the Vidian nerve. 3. A 
smaller opening immediately beneath and external to the latter for the passage of 
the smaller petrosal nerve. 4. Near the apex of the bone is seen the termination 
of the carotid canal, the wall of which in this situation is deficient in front. 5. Above 
the foramen is a shallow depression for the reception of the Gasserian ganglion. 

The posterior surface forms the front boundary of the posterior fossa of the 
skull, and is continuous with the inner surface of the mastoid portion of the bone. 
It presents three points for examination, i. About its centre is a large orifice, 
the meatus auditorius internus. This aperture varies considerably in size, its 
margins are smooth and rounded, and it leads into a short and oblique canal 
which is directed outwards and forwards. It transmits the auditory and facial 
nerves and auditory artery. 2. Behind the meatus auditorius is a small slit almost 
hidden by a thin plate of bone, and leading to a 'canal, the aquseductus vestibuli; 
it transmits a small artery and vein, and lodges a process of the dura mater. 
3. In the interval between these two openings, but above them, is an angular 
depression which lodges a process of the dura mater, and transmits a small vein 
into the cancellous tissue of the bone. 

The inferior or basilar Surface (fig. 27) is rough and irregular, and forms 
part of the base of the skull. Passing from the apex to the base, this surface 
presents eleven points for examination; I. A rough surface, quadrilateral in form, 
which serves partly for the attachment of the Levator palati, and Tensor tympani 
muscles. 2. The opening of the carotid canal, a large circular aperture, which 
ascends at first vertically upwards, and then making a bend, runs horizontally 
forwards and inwards. It transmits the internal carotid artery, and the carotid 
plexus. 3. The aquseductus cochleae, a small triangular opening, lying on the 
inner side of the latter, close to the posterior border of the bone; it transmits a 
vein from the cochlea, which joins the internal jugular. 4. Behind these openings 
is a depression, the jugular fossa, which varies in depth and size in different skulls; 
it lodges the internal jugular vein, and with a similar depression on the margin 
of the occipital bone, forms the foramen lacerum posterius. 5. A small foramen 
for the passage of Jacobson's nerve (the tympanic branch of the glosso-pharyngeal). 
This is seen on the ridge of bone dividing the carotid canal from the jugular fossa. 

6. The canal for Arnold's nerve, seen on the inner wall of the jugular fossa. 

7. Behind the jugular fossa is a smooth square-shaped facet, the jugular surface, 
which articulates with the jugular process of the occipital bone. 8. The vaginal 
process, a very broad sheath-like plate of bone, which extends from the carotid 
canal to the mastoid process; it divides behind into two laminae, receiving between 
them the 9th point for examination, the styloid process; a long sharp spine, about 
an inch in length, continuous with the vaginal process, between the laminag of 
which it is received, and directed downwards, forwards, and inwards. It affords 
attachment to three muscles, the Stylo-pharyngeus, Stylo-glossus, and Stylo-hyoideus, 
and two ligaments, the stylo-hyoid and stylo-maxillary. lO. The stylo-mastoid 
foramen, a rather large orifice, placed between the styloid and mastoid processes; 
it is the termination of the aquseductus Fallopii, and transmits the facial nerve 
and stylo-mastoid artery. 11. The auricular fissure, situated between the vaginal 



THE TEMPORAL BONE. 



31 



and mastoid processes, and transmitting the auricular branch of the pneumo- 
gastric nerve. 

Borders. The superior, the longest, is grooved for the superior petrosal sinus, 
and has attached to it the tentorium cerebelli: at its inner extremity is a semilunar 
notch, upon which reclines the fifth nerve. The posterior border is intermediate 
in length between the superior and the anterior. Its inner half is marked by a 
groove, which, when completed by its articulation with the occipital, forms the 
channel for the inferior petrosal sinus. Its outer half presents a deep excavation 



2.7. — Petrous Portion. Inferior Surface. 



CavalsforlAisla-ohiaTi ttiie 
atiJ' Tensor tYmpani wusc ' 

LEVATOR PALAT 



RcriLCjh Quadrilafera/' /SuT^a-ce 
Upe.vLiia of carctid ecriial 
Canal' far Jarohwns nerve 
Aqupdiicriis Cor/date, 
Canal far Arnold's Tierve 
JziifvJar josscc 
Yncjvnal ^ocess 
Stf^lmd proeess 
^tiilo' mastoid foTctvien 
JiL^QiJaT Si'rfaee 
AuricuIaT fissure 




STYLO -PHARrNGEUS 



for the jugular fossa, which, with a similar notch on the occipital, forms the fora- 
men lacerum posterius. A projecting eminence of bone occasionally stands out 
from the centre of the notch, and divides the foramen into two parts. The ante- 
rior border is divided into two parts, an outer, joined to the squamous portion by 
a suture the remains of which are distinct; an inner, free, articulating with the 
spinous process of the sphenoid. At the angle of junction of these two parts, are 
. seen two canals, separated from one another by a thin plate of bone, the processus 
cochleariformis; they both lead into the tympanum, the upper one transmitting the 
Tensor tympani muscle, the lower one the Eustachian tube. 

Structure. The squamous portion is like that of the other cranial bones, the 
mastoid portion cellular, and the petrous portion dense and hard. 

Development (fig. 28). The temporal bone is developed hjfour centres, exclusive 
of those for the internal ear and the ossicula, viz.; — one for the squamous portion 
including the zygoma, one for the petrous and mastoid parts, one for the styloid, 
and one for the auditory process (tympanic bone). The first traces of the develop- 
ment of this bone are found in the squamous portion, they appear about the time 
when osseous matter is deposited in the vertebree; the auditory process succeeds 



32 



OSTEOLOGY. 



next, it consists of an elliptical portion of bone, forming about three-fourths of a 
circle, the deficiency being above; it is grooved along its concave surface for the 



zZ. — Development of Temporal Bone. 
By four Centres. 



1 for Sq^ua-viows 
foTtixm, mcludi;, 
Zvaama 
Z^ mo 



I for Auditor II 



1 fof Pctroiis 
portions 




£ fov StyloicL prvc. 



attachment of the membrana tympani, 
and becomes united by its extremities 
to the squamous portion during the last 
months of intra-uterine life. The pe- 
trous and mastoid portions then become 
ossified, and lastly the styloid process, 
which remains separate a considerable 
period, and is occasionally never united 
to the rest of the bone. At birth the 
temporal bone, excluding the styloid 
process, is formed of three pieces, the 
squamous and zygomatic, the petrous 
and mastoid, and the auditory. The 
auditory process joins with the squa- 
mous at about the ninth month. The 
petrous and mastoid join with the squa- 
mous during the first year, and the sty- 
loid process becomes united between 
the second and third years. The sub- 
sequent changes in this bone are the 
extension outwards of the auditory 
process so as to form the meatus audi- 
torius, the glenoid fossa becomes deeper, 
and the mastoid part enlarges from the development of numerous cellular cavities 
in its interior. 

Articulatio7is. With five bones, occipital, parietal, sphenoid, inferior maxil- 
lary and malar. 

Attachment of Muscles. To the squamous portion, the Temporal; to the zygoma, 
the Masseter; to the mastoid portion, the Occipito-frontalis, Sterno-mastoid, Splenius 
capitis, Trachelo -mastoid, Digastricus and Retrahens aurem; to the styloid j)i*ocess, 
the Stylo-pharyngeus, Stylo-hyoideus and Stylo-glossus; and to the petrous portion, 
the Levator palati. Tensor tympani, and Stapedius. 

The Sphenoid Bone. 

The Sphenoid (cr^rjv, a 'wedge'; eiSo9, 'like') is situated at the anterior part of 
the base of the skull, articulating with all the other cranial bones, which it binds 
firmly and solidly together. Li its form it somewhat resembles a bat, with its 
wings extended; and is divided into a central portion or body, two greater and 
two lesser wings extending outwards on each side of the body; and two processes, 
the pterygoid processes, which project from it below. 

The Body presents for examination ybwr surfaces — a superior, an inferior, an 
anterior, and a posterior. 

The superior surface (fig. 29). From before, backwards, is seen a prominent 
spine, the ethmoidal spine, for articulation with the ethmoid; behind this a smooth 
surface, presenting in the median line a slight longitudinal eminence, with a de- 
pression on each side, for lodging the olfactory nerves. A narroAV transverse 
groove, the optic groove, bounds the above-mentioned surface behind ; it lodges the 
optic commissure, and terminates on either side in the optic foramen, for the pas- 
sage of the optic nerve and ophthalmic artery. Behind the optic groove is a 
small eminence, olive-like in shape, the olivaiy process; and still more posteriorly, 
a deep depression, the pituitary fossa, or sella Turcica, which lodges the pituitary 
body. This fossa is pei'forated by numerous foramina, for the transmission of nu- 
trient vessels to the substance of the bone. It is bounded in front by two small 
eminences, one on either side, called the middle clinoid processes, and behind by 
a squai'e- shaped plate of bone, terminating at each superior angle in a tubercle, the 



SPHENOID BONE. 



33 



posterior clinoid processes, the size and form of which vary considerably in different 
individuals. The sides of this plate of bone are notched below, for the passao-e of 
the sixth pair of nerves; and behind, it presents a shallow depression, which slopes 

29. — Sphenoid Bone, Superior Surface, 



JPustcrior 



MiMiii CUiiocd process . , _ .„ 

/^/- J \ UtJimoudaT Spiv& 

nor LUrwid process \ ^ ^ 1 ■' 

(h'oat/ejor 



■JjO'T^ 




J!ammen Opdcw 
loramov, laceravi 
U£Tt'us, err S'jihvnoitialFCsswre 
forxvwn JRctimda 
H VmiMu 

„ Oualo 

II Sfi'nasa.-M 



obliquely backwards, and is continuous with the basilar groove of the occipital 
bone; it supports the medulla oblongata. On either side of the body may be seen 
a broad groove, curved somewhat like the italic letter y"; it lodges the internal 

30. — Sphenoid Bone, Anterior Surface. 



JPtf-rycfoici 




LAXATOR TYMPANI 



Zntcvnal Tti7-ifef> 

JSiwmuZtt/i:' /i/faccss 



carotid artery and the cavernous sinus, and is called the cavernous groove. The 
posterior surface, quadrilateral in form, articulates with the basilar process of the 
occipital bone. During childhood, a separation between these bones exists by 
means of a layer of cartilage; but in after-life this becomes ossified, and the two 
bones are immoveably connected together. The anterior surface (fig, 30) presents, 
m the middle line, a vertical lamella of bone, which articulates in front with the 



34 OSTEOLOGY. 

perpendicular plate of the ethmoid. On either side of it are the irregular openings 
leading into the sphenoidal sinuses. These are two large, irregvilar cavities, hol- 
lowed out of the interior of the body of the sphenoid bone, and separated from 
one another by a more or less complete perpendicular septum; their form varies 
considerably, being often subdivided by irregular osseous laminae. These sinuses 
do not exist in children; but they increase in size as age advances. They are 
partially closed, in front and below, by two thin triangular plates of bone, the 
sphenoidal turbinated bones, leaving a round opening at their upper parts, by 
which they communicate with the upper and back part of the nose, and occa- 
sionally with the posterior ethmoidal cells. The lateral margins of this surface 
present a serrated edge, which articulates with the os planum of the ethmoid, 
completing the posterior ethmoidal cells ; the lower margin, also rough and serrated, 
articulates with the orbital process of the palate bone; and the upper margin 
with the orbital plate of the frontal bone. The inferior surface presents, in the 
middle line, a triangular spine, the rostrum, which is continuous with the vertical 
plate on the anterior surface, and is received into a deep fissure between the alae 
of the vomer. On each side may be seen a projecting lamina of bone, which runs 
horizontally inwards from near the base of the pterygoid process: these plates, 
termed the vaginal processes, articulate with the edges of the vomer. Close to the 
root of the pterygoid process is a groove, formed into a complete canal when articu- 
lated with the sphenoidal process of the palate bone ; it is called the pterygo-pala- 
tine canal, and transmits the pterygo-palatine vessels and pharyngeal nerve. 

The Greater Wings are two strong processes of bone, which arise at the sides 
of the body, and are curved in a direction upwards, outwards, and backwards; 
being prolonged behind into a sharp-pointed extremity, called the spinous process 
of the sphenoid. Each wing presents three surfaces and a circumference. The 
superior or cerebral surface forms part of the middle fossa of the skull; it is 
deeply concave, and presents eminences and depressions for the convolutions of 
the, brain. At its anterior and internal part is seen a circular aperture, the 
foramen rotundum, for the transmission of the second division of the fifth nerve. 
Behind and external to this, a large oval foramen, the foramen ovale, for the trans- 
mission of the third division of the fifth, the small meningeal artery, and the small 
petrosal nerve. At the inner side of the foramen ovale, a small aperture may 
occasionally be seen opposite the root of the pterygoid process; it is the foramen 
Vesalii, transmitting a small vein. Lastly, in the apex of the spine of the sphe- 
noid is a short canal, sometimes double, the foramen spinosum; it transmits the 
middle meningeal artery. The external surface is convex, and divided by a trans- 
verse ridge, the pterygoid ridge, into two portions. The superior or larger, 
convex from above downwards, concave from before backwards, enters into the 
formation of the temporal fossa, and attaches part of the Temporal muscle. The 
inferior portion, smaller in size and concave, enters into the formation of the 
zygomatic fossa, and afibrds attachment to the External pterygoid muscle. It 
presents, at its posterior part, a sharp-pointed eminence of bone, the spinous 
process, to which is connected the internal lateral ligament of the lower jaw, and 
the Laxator tympani muscle. The pterygoid ridge, dividing the temporal and 
zygomatic portions, gives attachment to the upper origin of the External ptery- 
goid muscle. At its inner extremity is a long triangular spine of bone, which 
serves to increase the extent of origin of this muscle. The anterior or orbital 
surface, smooth and quadrilateral in form, assists in forming the outer wall of the 
orbit. It is bounded above by a serrated edge, for articulation with the frontal 
bone; below, by a rounded border, which enters into the formation of the spheno- 
maxillary fissure; internally, it enters into the formation of the sphenoidal fissure; 
whilst externally it presents a serrated margin, for articulation with the malar 
bone. At the upper part of the inner border is a notch, for the transmission of a 
branch of the ophthalmic artery; and at its lower part a small pointed spine of 
bone, which serves for the attachment of part of the lower head of the external 
rectus. One or two small foramina may occasionally be seen, for the passage of 



' 



SPHENOID BONE. 



35 



arteries; tliey are called the external orhitar foramina. Circumference: from 
the body of the sphenoid to the spine (commencing from behind), the outer half of 
this margin is serrated, for articulation with the petrous portion of the temporal 
bone; whilst the inner half forms the anterior boundary of the foramen lacerum 
medium, and presents the posterior aperture of the Vidian canal. In front of the 
spine, the circumference of the great wing presents a serrated edge, bevelled at 
the expense of the inner table below, and of the external above, which articulates 
with the squamous portion of the temporal bone. At the tip of the great wing 
a triangular portion is seen, bevelled at the expense of the internal surface, for 
articulation with the anterior inferior angle of the parietal bone. Internal to this 
is a broad serrated edge, for articulation with the frontal bone: this surface is 
continuous internally with the sharp inner edge of the orbital plate, which assists 
in the formation of the sphenoidal fissure. 

The Lesser Wings (processes of Ingrassias) are two thin triangular plates of 
bone, which arise from the upper and anterior part of the body of the sphenoid; 
and, projecting transversely outwards, terminate in a more or less acute point. 
The superior surface of each is smooth, flat, broader internally than externally, and 
supports the anterior lobe of the brain. The inferior surface forms the back part 
of the roof of the orbit, and the upper boundary of the sphenoidal fissure, or 
foramen lacerum anterius. This fissure is of a triangular form, and leads from the 
cavity of the cranium into the orbit; it is bounded internally by the body of the 
sphenoid; above, by the lesser wing; and below, by the orbital surface of the 
great wing ; and is converted into a foramen by the articulation of this bone with 
the frontal. It transmits the third, fourth, ophthalmic division of the fifth and 
sixth nerves, and the ophthalmic vein. The anterior border of the lesser wing 
is serrated, for articulation with the frontal bone ; the posterior, smooth and 
rounded, is received into the fissure of Sylvius of the brain. The inner extremity 
of this border forms the anterior clinoid process. The lesser wing is connected to 
the side of the body by two roots, the upper thin and flat, the lower thicker, 
obliquely directed, and presenting on its outer side a small tubercle, for the attach- 
ment of the common tendon of the muscles of the eye. Between the two roots 
is the optic foramen, for the transmission of the optic nerve and ophthalmic artery. 

The Pterygoid processes „ , . , ^ -n. , . r^ ^ 

fr. X 1-1 31. — Sphenoid Bone. Posterior Surface, 

(tig. 31), one on each side, ^ ^ 

descend perpendicularly from 
the point where the body and 
great wing unite. Each pro- 
cess consists of an external 
and an internal plate, sepa- 
rated behind by an intervening 
notch; but joined partially in 
front. The external pterygoid 
plate is broad and thin, turned a 
little outwards, and forms part 
of the inner wall of the zygo- 
matic fossa. It gives attach- 
ment, by its outer surface, to 
the External pterygoid; its 
inner surface forms part of 

the pterygoid fossa, and gives attachment to the Internal pterygoid. The internal 
pterygoid plate is much narrower and longer, curving outwards at its extremity, 
into a hook-like process of bone, the hamular process, around which turns the 
tendon of the Tensor-palati muscle. At the base of this plate is a small, oval, 
shallow depression, the scaphoid fossa, from which arises the Tensor-palati, and 
above which is seen the posterior orifice of the Vidian canal. The outer surface 
of this plate forms part of the pterygoid fossa, the inner surface forming the outer 
boundary of the posterior aperture of the nares. The two pterygoid plates are 

D 2 





36 OSTEOLOGY. 

separated below by an angular notch, in which the pterygoid process, or tuberosity, 
of the palate bone is received. The anterior surface of the pterygoid process is 
very broad at its base, and supports Meckel's ganglion. It presents, above, the 
anterior orifice of the Vidian canal ; and below, a rough margin, which articulates 
with the perpendicular plate of the palate bone. 

Development. The sphenoid bone is developed by ten centres, six for the pos- 
terior sphenoidal division, and four for 32. — Development of Sphenoid, 
the anterior sphenoid. The six centres By Ten Centres. 
for the post-sphenoid are, one for each I for eacl lesser wi:n^UA7iirj,a.rt,fiody 
greater wing and external pterygoid plate; 
one for each internal pterygoid plate; 
two for the posterior part of the body. 
The four for the anterior sphenoid are, 
one for each lesser wing and anterior part 
of the body; and one for each sphenoidal 

turbinated bone. Ossification takes place ,, i „S^*„«r,n Sr ^^-tZ-r„S'^/i,„ 

in these pieces in the following order: the 
greater wing and external pterygoid plate ^, ,„, .t,, ,- j i 

° „ -° , .„ , ,. J^joruich SpmiufumL tiirbi.nate.d bone 

are first formed, ossmc granules being 

deposited close to the foramen rotundum on each side, at about the second month 
of foetal life ; ossification spreading outwards into the great wing, and downwards 
into the external pterygoid process. Each internal pterygoid plate is then formed, 
and becomes united to the external about the middle of foetal life. The two 
centres for the posterior part of the body appear as separate nuclei, side by side, 
beneath the sella Turcica; they join about the middle of foetal life into a single 
piece, which remains ununited to the rest of the Taone until after birth. Each lesser 
wing is foi'med by a separate centre, which appears on the outer side of the optic 
foramen, at about the third month; they become united and join with the body, 
at about the eighth month of foetal life. At about the end of the third year, 
ossification has made its appearance in the sphenoidal spongy bones. 

At birth, the sphenoid consists of three pieces; viz. the greater wing and ptery- 
goid processes on each side; the lesser wings and body united. At the first 
year after birth, the greater wings and body are united. From the tenth to the 
twelfth year, the spongy bones commence their junction to the sphenoid, and be- 
come completely united by the twentieth year. Lastly, the sphenoid joins the 
occipital. 

Articulations. The sphenoid articulates with all the bones of the cranium, and 
five of the face; the two malar, two palate, and vomer: the exact extent of articu- 
lation with each bone is shewn in the accompanying figures. 

Attachment of Muscles. The Temporal, External pterygoid. Internal pterygoid, 
Superior constrictor, Tensor-palati, Laxator-tympani, Levator-palpebrge, Obliquus 
superior, Superior rectus. Internal rectus. Inferior rectus, External rectus. For the 
exact attachment of the muscles of the eye to the sphenoid bone, see fig. 133. 

The Sphenoidal Spongy Bones. 

The Sphenoidal Spongy Bones are two thin, curved plates of bone, which 
exist as separate pieces up to the fifteenth year. They are situated at the anterior 
and inferior part of the body of the sphenoid, serving to close in the sphenoidal 
sinuses in this situation. They are irregular in form, thick, and tapering to a 
point behind, broader and thinner in front. Their inner surface, which looks 
towards the cavity of the sinus, is concave; their outer surface convex. Each 
bone articulates in front with the ethmoid, an aperture of variable size being left 
in their anterior wall, which communicates with the posterior ethmoidal cells: 
behind, its point is placed under the vomer, and is received between the root of 
the pterygoid process on the outer side, and the rostrum of the sphenoid on the 
inner: externally, it articulates with the palate. 



ETHMOID BONE. 



37 




wM infjturbinated i. 



The Ethmoid. 

The Ethmoid {r)6^o^, a sieve), is an exceedingly light spongy bone, of a cubical 
form, situated at the anterior part of the base of the cranium, between the two 
orbits,''at the root of the nose. ^^. . *-^ ^ ^ „ , , 

It consists of three parts: a 33— Ethmoid Bone. Outer Surface (enlarged). 

horizontal plate, which forms *^ 

part of the base of the cra- 
nium; a perpendicular plate, 
which forms part of the sep- 
tum nasi; and two lateral 
masses of cells. 

The Horizontal or Cribri- 
form Plate (fig.33) forms part 
of the anterior fossa of the 
base of the skull, and is re- 
ceived into the ethmoid notch 
of the frontal bone between 
the two orbital plates. Pro- 
jecting upwards from the 
middle line of this plate, at its 
fore part, is a thick smooth 
triangular process of bone, 
the crista galli,so called from its resemblance to a cock's-comb. Its base joins the 
cribriform plate. Its posterior border, long, thin, and slightly curved, serves for 
the attachment of the falx cerebri. Its anterior, short and thick, articulates with 
the frontal bone, and presents at its lower part two small projecting alse, which 
are received into corresponding depressions in the frontal, completing the foramen 
coecum behind. Its sides are smooth, and sometimes bulging, when it is found to 
enclose a small sinus. On each side of the crista galli, the cribriform plate is 
concave, to support the bulb of the olfactory nerves, and perforated by numerous 
foramina for the passage of its filaments. These foramina consist of three sets, 
corresponding to the three sets of olfactory nerves; an inner, which are lost in 
grooves on the upper part of the septum; an outer set, continued on to the surface 
of the upper spongy bones; whilst the middle set run simply through the bone, 
and transmit nerves distributed to the roof of the nose. At the front part of 
the cribriform plate, by the side of the crista galli, is a small fissure, which trans- 
mits the nasal branch of the ophthalmic nerve; and at its posterior part a trian- 
gular notch, which receives the ethmoidal spine of the sphenoid. 

P^a^/(fig. r/)'!? ^thin 34.-Perpendicular Plate of Ethmoid (enlarged). Shewn by 

V &• i't) *^ ^ ''■L1J-" removing the Right Lateral Mass. 

central lamella of bone, 
which descends from the 
under surface of the 
cribriform plate, and 
assists in forming the 
septum of the nose. Its 
anterior border articu- 
lates with the frontal 
spine and crest of the 
nasal bones. Its poste- 
rior, divided into two 
parts, is connected by 
its upper half with the 
rostrum of the sphe- 
noid; its lower half with 
the vomer. The infe- 



{fji EthmoicJ, 




38 OSTEOLOGY. 

rior border serves for the attachment of the triangular cartilage of the nose. 
On each side of the perpendicular plate numerous grooves and canals are seen, 
leading from the foramina on the cribriform plate ; they lodge the filaments of the 
olfactory nerves. 

The Lateral Masses of the ethmoid are made up of a numbei" of thin walled 
cellular cavities, called the ethmoidal cells. In the disarticulated bone, many 
of these appear to be broken ; but when the bones are articulated, they are closed 
in in every part. The superior surface of each lateral mass presents a number of 
these apparently half-broken cellular spaces; these, however, are completely closed 
in when articulated with the edges of the ethmoidal fissure of the frontal bone. 
Crossing this surface are seen two grooves on each side, converted into canals by 
articulation with the frontal; they are the anterior and posterior ethmoidal fora- 
mina. They open on the inner wall of the orbit, and transmit; the anterior, the 
anterior ethmoidal vessels and nasal nerve; the posterior, the posterior ethmoidal 
artery and vein. The posterior surface also presents large irregular cellular 
cavities, which are closed in by articulation with the sphenoidal turbinated bones, 
and orbital process of the palate. The cells at the anterior surface are completed 
by the lachrymal bone and nasal process of the superior maxillary, and those 
below also by the superior maxillary. On the outer surface of each lateral mass 
is a thin smooth square plate of bone, called the os planum; it forms part of the 
inner wall of the orbit, and articulates above with the frontal; below, with the 
superior maxillary and orbital process of the palate; in front, with the lachrymal; 
and behind, with the sphenoid. 

The cellular cavities of each lateral mass, thus walled in by the os planum on 
the outer side, and by its articulation with the other bones already mentioned, are 
divided by a thin transverse bony partition into two sets, which do not commu- 
nicate with each other; they are termed the anterior and posterior ethmoidal 
cells; the former, the most numerous, communicate with the frontal sinuses above, 
and the middle meatus below, by means of a long flexuous cellular canal, the 
infundibulum ; the posterior, the smallest and least numerous, open into the supe- 
rior meatus, and communicate (occasionally) with the sphenoidal sinuses behind. If 
the inner wall of each lateral mass is now examined, it will be seen how these 
cellular cavities communicate with the nose. The internal surface of each lateral 
mass presents, at its upper and back part, a narrow horizontal fissure, the supe- 
rior meatus of the nose, bounded above by a thin curved plate of bone, the 
superior turbinated bone of the ethmoid. By means of an orifice at the top part 
of this fissure, the posterior ethmoidal cells open into the nose. Below the superior 
meatus is seen the convex surface of another thin convoluted plate of bone, the 
middle turbinated bone. It extends along the whole length of the inner wall of 
each lateral mass; its lower margin is free and thick, and its concavity, directed 
outwards, assists in forming the middle meatus. It is by means of a large orifice 
at the upper and front part of this fissure, that the anterior ethmoid cells, and 
through them the frontal sinuses, by means of a funnel-shaped canal, the infundi- 
bulum, communicate with the nose. It will be remarked, that the whole of this 
surface is rough, and marked with numerous grooves and orifices, which run 
nearly vertically downwards from the cribriform plate; they lodge the branches 
of the olfactory nerve, which are distributed on the mucous membrane covering 
this surface. From the inferior part of each lateral mass, immediately beneath 
the OS planum, there projects downwards and backwards an irregular lamina of 
bone, called the unciform process, from its hook-like form: it serves to close in 
the upper part of the orifice of the antrum, and articulates with the inferior turbi- 
nated bone. 

Development. By three centres; one for the perpendicular lamella, and one for 
each lateral mass. 

The lateral masses are first developed, ossific granules making their first appear- 
ance in the os planum between the fourth and fifth months of foetal life, and 
afterwards in the spongy bones. At birth, the bone consists of the two lateral 



WORMIAN BONES. 



39 



masses, which are small and ill-developed; but when the perpendicular and hori- 
zontal plates begin to ossify, as they do about the first year after birth, the lateral 
masses become joined to the cribriform plate. The formation and increase in the 
ethmoidal cells, which complete the formation of the bone, take place about the 
fifth or sixth year. 

Articulations. With fifteen bones; the sphenoid, two sphenoidal turbinated, the 
frontal, and eleven of the face — two nasal, two superior maxillary, two lachry- 
mal, two palate, two inferior turbinated, and vomer. 

The Wormian Bones. 

The Wormian* bones, called also, from their generally triangular form, ossa 
triquetra, are irregular plates of bone, presenting much variation in situation, 
number, and size. They are most commonly found in the course of the sutures, 
especially the lambdoid and sagittal, where they occasionally exist of large size; 
the superior angle of the occipital, and the anterior superior angle of the parietal, 
being occasionally replaced by large Wormian bones. They are not limited to the 
■vertex, for they are occasionally found at the side of the skull, in the situation of 
the anterior inferior angle of the parietal bone, and in the squamous suture; and 
more rarely they have been found at the base, in the suture between the sphenoid 
and ethmoid bones. Their size varies, in some cases not being larger than a pin's 
head, and confined entirely to the outer table; in other cases so large, that a pair 
of these bones formed the whole of that portion of the occipital bone above the 
superior curved lines, as described by Beclard and others. Their number is 
most generally limited to two or three; but more than a hundred have been found 
in the skull of an adult hydrocephalic skeleton. It appears most probable that 
they are separate accidental points of ossification, which, during their develop- 
ment and growth, remain separate from the adjoining bones. In their development, 
structure, and mode of articulation, they resemble the other cranial bones. 

Bones of the Face. 
The Facial Bones are fourteen in number, viz., the 

Two Nasal, Two Palate, 

Two Superior Maxillary, Two Inferior Turbinated, 

Two Lachrymal, Vomer, 

Two Malar, Inferior Maxillary. 

Nasal Bones. 

The Nasal Bones (figs. 35, 36) are two small oblong bones, varying in size and 
form in difierent individuals; they are placed side by side at the middle and upper 
part of the face, forming by their junction the bridge of the nose. Each bone 

presents for examina- 
tion two surfaces, and 
four borders. The outer 
surface is concave from 
above downwards, con- 
vex from side to side, 
it is covered by the 
Compressor nasi mus- 
cle, marked by nu- 
merous small arterial 
furrows, and perforated 
about its centre by a 
OuteT Surface. foramen, sometimes 

double, for the trans- 
mission of a small vein. Sometimes this foramen is absent on one or both sides, 
and occasionally the foramen coecum opens on this surface. The inner surface 
* Wonnius, a physician in Copenhagen. 



35. — Right Nasal Bone. 
with F'rontal B. 

/UfitJi 
-Ojtposct& hone. 




36.^Right Nasal Bone. 

imth 
FrontaZ lupine.- 
crest 
M-rpeiidicwlar 



groove for iujisOjI nerve 
Inner Surf (toe 




40 OSTEOLOGY. 

is concave from side to side, convex from above downwards; in which direction it 
is traversed by a well marked longitudinal groove, sometimes a canal, for the 
passage of a branch of the nasal nerve. The superior border is narrow, thick, 
and serrated for articulation with the nasal notch of the frontal bone. The infe- 
rior border is broad, thin, sharp, directed obliquely downwards, outwards and 
backwards ; serving for the attachment of the lateral cartilage of the nose. This 
border presents about its centre a notch, which transmits the branch of the nasal 
nerve above referred to, and is prolonged at its inner extremity into a sharp 
spine, which, when articulated with the opposite bone, forms the nasal angle. The 
external border is serrated, bevelled at the expense of the internal surface above, 
and of the external below, to articulate with the nasal process of the superior 
maxillary. The internal border, thicker above than below, articulates with its 
fellow of the opposite side, and is prolonged behind into a vertical crest, which 
forms part of the septum of the nose; this crest articulates with the nasal spine 
of the frontal above, and the perpendicular plate of the ethmoid below. 

Development. By one centre for each bone, which appears about the same period 
as in the vertebras. 

Articulations. With four bones; two of the cranium, the frontal and ethmoid, 
and two of the face, the opposite nasal and the superior maxillary. 

No muscles are directly attached to this bone. 

Superior Maxillary Bone. 

The Superior Maxillary is one of the most important bones of the face in a 
surgical point of view, on account of the number of diseases to which some of its 
parts are liable. Its minute examination beccrmes, therefore, a matter of consi- 
derable importance. It is the largest bone of the face, excepting the lower jaw, 
and forms, by its union with its fellow of the opposite side, the whole of the up- 
per jaw. Each bone assists in the formation of three cavities, the roof of the 
mouth, the floor and outer wall of the nose, and the floor of the orbit; enters 
into the formation of two fossae, the zygomatic and spheno-maxillary, and two 
fissures, the spheno-maxillary, and pterygo-maxillary. Each bone presents for 
examination a body and four processes, malar, nasal, alveolar, and palatine. 

The body is somewhat quadrilateral, and is hollowed out in its interior to form 
a large cavity, the antrum of Highmore. It presents for examination four sur- 
faces, an external or facial, a posterior or zygomatic, a superior or orbital, and an 
internal. 

The external or facial surface (fig. 37) is directed forwards and outwards. In 
the median line of the bone, just above the incisor teeth, is a depression, the incisive 
or myrtiform fossa, which gives origin to the Depressor labii superioris alaeque nasi. 
Above and a little external to it, the Compressor naris arises. More external and 
immediately beneath the orbit, is another depression, the canine fossa, larger and 
deeper than the incisive fossa, from which it is separated by a vertical ridge, the 
canine eminence, corresponding to the socket of the canine tooth. The canine 
fossa gives origin to the Levator anguli oris. Above the canine fossa is the infra 
orbital foramen, the termination of the infra-orbital canal; it transmits the infra- 
orbital nerve and artery. Above the infra-orbital foramen is the margin of the 
orbit, which afibrds partial attachment to the Levator labii superioris proprius 
muscle. 

The posterior or zygomatic surface is convex, directed backwards and outwards, 
and forms part of the zygomatic fossa. It presents about its centre two or three 
grooves leading to canals in the substance of the bone; they are termed the poste- 
rior dental canals, and transmit the posterior dental vessels and nerves. At 
the lower part of this surface is a rounded eminence, the maxillary tuberosity, 
especially prominent after the growth of the wisdom-tooth, rough on its inner side 
for articulation with the tuberosity of the palate bone. At the upper and inner 
part of this surface is the commencement of a groove, which, running down on the 



SUPERIOR MAXILLARY BONE. 



41 



nasal surface of the bone, is converted into a canal by articulation with the palate 
bone, forming the posterior palatine canal. 

The superior or orbital surface is thin, smooth, irregularly quadrilateral, and 
forms part of the floor of the orbit. It is bounded internally by an irregular 
margin which articulates with three bones; in front, with the lachrymal; in the 
middle, with the os planum of the ethmoid; and behind, with the orbital process 
of the palate bone; posteriorly, by a smooth rounded edge which enters into the 
formation of the spheno-maxillary fissure, and which sometimes articulates at its 
anterior extremity with the orbital plate of the sphenoid; bounded externally b^ 

37. — Left Superior Maxillary Bone. Outer Surface. 

Outer Surface . 



Jncisive fossczr 




Posterior Dental' Canals 



Maxillary Tuterositu. 



■*^**^''^-^Sji}5^ 



the malar process, and in front by part of the circumference of the orbit continuous, 
on the inner side, with the nasal, on the outer side, with the malar process. Along 
the middle line of this surface is a deep groove, the infra-orbital, for the passage of 
the infra-orbital nerve and artery. This groove commences at the middle of the 
posterior border of the bone, and, passing forwards, terminates in a canal which 
subdivides into two branches; one of the canals, the infra-orbital, opens just below 
the margin of the orbit; the other, the smaller and most posterior one, runs in the 
substance of the anterior wall of the antrum; it is called the anterior dental, trans- 
mitting the anterior dental vessels and nerves to the front teeth of the upper jaw. 
The internal surface (fig. 38) is unequally divided into two parts by a hori- 
zontal projection of bone, the palatine process; that portion above the palate-pro- 
cess forms part of the outer wall of the nose; the portion below it forms part of 
the cavity of the mouth. The superior division of this surface presents a large 
irregular shaped opening leading into the antrum of Highmore. At the upper 
border of this aperture are a number of broken cellular cavities, which, in the ar- 
ticulated skull, are closed in by the ethmoid and lachrymal bones. Below the 
aperture, is a smooth concavity which forms part of the inferior meatus of the nose, 
traversed by a fissure, the maxillary fissure, which runs from the lower part of the 
orifice of the antrum obliquely downwards and forwards, and receives the maxillary 
process of the palate. Behind it, is a rough surface which articulates with the 
perpendicular plate of the palate bone, traversed by a groove which, com- 



42 



OSTEOLOGY. 



mencing near the middle of the posterior border, runs obliquely downwards and 
forwards, and forms, when completed by its articulation with the palate bone, the 
posterior palatine canal. In front of the opening in the antrum is a deep groove, 
converted into a canal by the lachrymal and inferior turbinated bones, and lodging 
the nasal duct. More anteriorly is a well marked rough ridge, the inferior turbi- 
nated crest, for articulation with the inferior turbinated bone. The concavity 
above this ridge forms part of the middle meatus of the nose, whilst that below it 
forms part of the inferior meatus. The inferior division of this surface is concave, 
rough and uneven, and perforated by numerous small foramina for the passage of 
nutrient vessels. 

38. — Left Superior Maxillary Bone. Inner Surface. 



jSo77bj -pafttcully closivq Or^rfoce of ^'/vtT-aTn 



Ethyrujid 
J-nfcrior TurhiTiatecl 
faZoute 




Ant. NaswZ SfpLTta 



J3ristle 
pa^iscd nhrough 
ATCt^poiliit. Canal 



The Antrum of Highmore, or Maxillary Sinus, is a large triangular- shaped 
cavity, hollowed out of the body of the maxillary bone; its apex, directed out- 
wards, is formed by the malar process; its base, by the outer wall of the nose. 
Its walls are everywhere exceedingly thin, its roof being formed by the orbital 
plate, its floor by the alveolar process, bounded in front by the facial surface, and 
behind by the zygomatic. Its inner wall, or base, presents, in the disarticulated 
bone, a large irregular aperture, which communicates with the nasal fosste. The 
margins of this aperture are thin and ragged, and the aperture itself is much con- 
tracted by its articulation with the ethmoid above, the inferior turbinated below, 
and the palate bone behind. In the articulated skull, this cavity communicates 
with the middle meatus of the nose generally by two small apertures left between 
the above-mentioned bones. In the recent state, usually only one small opening 
exists, near the upper part of the cavity, sufficiently large to admit the end of a 
probe, the rest being filled in by the lining membrane of the sinus. 

Crossing the cavity of the antrum are often seen several projecting laminse of 
bone, similar to those seen in the sinuses of the cranium; and on its outer wall are 
the posterior dental canals, transmitting the posterior dental vessels and nerves to 
the teeth. Projecting into the floor are several conical processes, corresponding to 
the roots of the first and second molar teeth; in some cases, the floor is even per- 
forated by the teeth in this situation. It is from the extreme thinness of the walls 
of this cavity, that we are enabled to explain how tumours, growing from the 



SUPERIOR MAXILLARY BONE. 



43 



antrum, encroach upon the adjacent parts, pushing up the floor of the orbit and 
displacing the eyeball, projecting inward into the nose, protruding forwards on to 
the cheek, and making their way backwards into the zygomatic fossa, and down- 
wards into the mouth. 

The Malar Process is a rough triangular eminence, situated at the angle of 
separation of the facial from the zygomatic surface. In front, it is concave, 
forming part of the facial surface; behind, it is also concave, and forms part of the 
zygomatic fossa; superiorly, it is rough and serrated for articulation with the 
malar bone; whilst below, a prominent ridge, marks the division between the 
facial and zygomatic surfaces. 

The Nasal Process is a thick triangular plate of bone, which projects upwards, 
inwards, and backwards, by the side of the nose, forming its lateral boundary. Its 
external surface is concave, smooth, perforated by numerous foramina, and gives 
attachment to the Levator labii superioris algeque nasi, the Orbicularis palpebrarum, 
and Tendo oculi. Its internal surface forms part of the inner wall of the nares; 
it articulates above with the frontal, and presents a rough uneven surface which 
articulates with the ethmoid bone, closing in the anterior ethmoid cells; below this 
is a transverse ridge, the superior turbinated crest, for articulation with the middle 
turbinated bone of the ethmoid, bounded below by a smooth concavity, which forms 
part of the middle meatus; below this is the inferior turbinated crest (already de- 
scribed), for articulation with the inferior turbinated bone ; and still more inferiorly, 
the concavity which forms part of the inferior meatus. The anterior border of the 
nasal process is thin, and serrated for articulation with the nasal bone: its poste- 
rior border thick, and hollowed into a groove for the nasal duct; of the two margins 
of this groove, the inner one articulates with the lachrymal bone, the outer one 
forming part of the circumference of the orbit. Just where this border joins the 
orbital surface is a small tubercle, the lachrymal tubercle. This serves as a guide 
to the surgeon in the performance of the operation for fistula lachrymalis. The 
lachrymal groove in the articulated skull is converted into a canal by the lachrymal 
bone, and lachrymal process of the inferior turbinated; it is directed downwards, 
and a little backwards and outwards, is about the diameter of a goose-quill, slightly 
narrower in the middle than at either extremity, and lodges the nasal duct. 

The Alveolar Process is the thickest part of the bone, broader behind than in 
front, and excavated into deep cavities for the reception of the teeth. These 
cavities are eight in number, and vary in size and depth according to the teeth 
they contain: those for the canine teeth being the deepest; those for the molars 
being widest, and subdivided into minor cavities ; those for the incisors being single, 
but deep and narrow. 

The Palate Process, thick and strong, projects horizontally inwards from the 
inner surface of the bone. It is much thicker in front than behind, and forms the 
floor of the nares, and the roof of the mouth. Its upper surface is concave from 
side to side, smooth, and forms part of the floor of the nose. In front is seen the 
upper orifice of the anterior palatine (incisor) canal, which leads into a fossa 
formed by the junction of the two superior maxillary bones, and situated imme- 
diately behind the incisor teeth. It transmits the anterior palatine vessels, the 
naso-palatine nerves passing through the inter-maxillary suture. The inferior 
surface, also concave, is rough and uneven, and forms part of the roof of the 
mouth. This surface is perforated by numerous foramina for the passage of 
nutritious vessels, channelled at the back part of its aveolar border by a longi- 
tudinal groove, sometimes a canal, for the transmission of the posterior palatine 
vessels, and a large nerve, and presents little depressions for the lodgment of the pala- 
tine glands. This surface presents anteriorly the lower orifice of the anterior pala- 
tine fossa. The outer border is firmly united with the rest of the bone. The inner 
border is thicker in front than behind, raised above into a ridge, which, with 
the corresponding ridge in the opposite bone, forms a groove for the reception of 
the vomer. The anterior margin is bounded by the thin concave border of the 
opening of the nose, prolonged forwards internally into a sharp process, forming, 



44 



OSTEOLOGY, 



with a similar process of the opposite bone, the anterior nasal spine. The pos- 
terior border is serrated for articulation with the horizontal plate of the palate 
bone. 

Development (fig. 39). This bone is formed at such an early period, and ossifi- 
cation proceeds in it with such rapidity, that it has been found impracticable 

^ , .PC. • TVT -n -D hitherto to determine with accu- 

35_ — Development of Superior Maxillary Bone 

By Four Centres. 



J for N'asal ^ 
Facial portV, 



i for Orlital, ^ 
Malar jiorfV 




Anterior /Surface. 



1 J^urU-n, 



noriV: 



1 -for Palatal jiorf— 




racy its number of centres. It 
appears, however, probable that 
it has four centres of develop- 
ment, viz., one for the nasal and 
facial portions, one for the orbital 
and malar, one for the incisive, 
and one for the palatal portion, in- 
cluding the entire palate except 
the incisive segment. The inci- 
sive portion is indicated in young 
bones by a fissure, which marks 
at off a small segment of the palate, 
BlrtJi including the two incisor teeth. 
In some animals, this remains 
permanently as a separate piece, 
constituting the intermaxillary 
bone; and in the human subject, 
where the jaw is malformed, 
a detached piece is often found 
in this situation, most probably 
depending upon arrest of de- 
velopment of this centre. The 
maxillary sinus appears at an 
earlier period than any of the other sinuses, its development commencing about the 
fourth month of foetal life. 

Articulations. With nine bones; two of the cranium — the frontal and ethmoid, 
and with seven of the face, viz., the nasal, malar, lachrymal, inferior turbinated, 
palate, vomer, and its fellow of the opposite side. Sometimes it articulates with 
the orbital plate of the sphenoid. 

Attachment of Muscles. Orbicularis palpebrarum, Obliquus inferior oculi. Leva- 
tor labii superioris al^que nasi. Levator labii superioris proprius. Levator anguli- 
oris, Compressor naris. Depressor al^e nasi, Masseter, Buccinator. 

The Lachrymal Bones. 

The Lachrymal are the smallest and most fragile of all the bones of the face, 
situated at the front part of the inner wall of the 
orbit, and resemble somewhat in form, thinness, 
and size, a finger-nail; hence they are termed the 
ossa unguis. Each bone presents for examination, 
two surfaces and four borders. The external 
(fig. 40) or orbital surface is divided by a vertical 
ridge into two parts. The portion of bone in front 
of this ridge presents a smooth, concave, longitu- 
dinal groove, the free margin of which unites with 
the nasal process of the superior maxillary bone, 
completing the lachrymal groove. The upper part 
of this groove lodges the lachrymal sac; the lower 
part is continuous with the lachrymal canal, and 
lodges the nasal duct. The portion of bone be- 
hind the ridge is smooth, slightly concave, and 
forms part of the inner wall of the orbit. The 



40.- 



-Left Lachrymal Bone. 
External Surface. 



vnA Frontal 




Infi 
( SligJiily 



enla-rgcd \ 



MALAR BONE. 



45 



41. — Left Malar Bone. Outer Surface. 



ridge, and part of the orbital surface immediately behind it, affords attachment 
to the Tensor tarsi: it terminates below in a small hook-like process, which articu- 
lates with the lachrymal tubercle of the superior maxillaiy bone, and completes 
the upper orifice of the lachrymal canal. It sometimes exists as a separate piece, 
which is then called the lesser lachrymal bone. The internal or nasal surface 
presents a depressed furrow, corresponding to the elevated ridge on its outer 
surface. The surface of bone in front of this forms part of the middle meatus; 
and that behind it articulates with the ethmoid bone, filling in the anterior 
ethmoidal cells. Of the four borders, the anterior is the longest, and articulates 
with the nasal process of the superior maxillary bone. The posterior, thin and 
uneven, articulates with the os planum of the ethmoid. The superior border, the 
shortest and thickest, articulates with the internal angular process of the frontal 
bone. The inferior is divided by the lower edge of the vertical crest into two 
parts, the posterior articulating with the orbital plate of the superior maxillary 
bone; the anterior portion being prolonged downwards into a pointed process, 
which articulates with the lachrymal process of the inferior turbinated bone, 
assisting in the formation of the lachrymal canal. 

Development. By a single centre, which makes its appearance soon after ossi- 
fication of the vertebrse has commenced. 

Articulations. With four bones; two of the cranium, the frontal and ethmoid, 
and two of the face, the superior maxillary and the inferior turbinated. 

Attachment of Muscles. The Tensor tarsi. 

The Malar Bones. 

The Malar are two small quadrangular bones, situated at the upper and outer 
part of the face, forming the prominence of the cheek, part of the outer wall and floor 
of the orbit, and part of the tem- 
poral and zygomatic fossae. Each 
bone presents for examination an 
external and an internal surface ; 
four processes, the frontal, orbital, 
maxillary, and zygomatic; and 
four borders. The external sur- 
face (fig. 41) is smooth, convex, 
perforated near its centre by one 
or two small apertures, the malar 
canals, for the passage of small 
nerves and vessels, covered by 
the Orbicularis palpebrarum mus- 
cle, and affords attachment to the 
Zygomaticus major and minor 
muscles. 

The internal surface (fig. 42), 
directed backwards and inwards, 
is concave, presenting internally 
a rough triangular surface, for articulation with the superior maxillary bone; and 
externally, a smooth concave surface, which forms the anterior boundary of the tem- 
poral fossa above, wider below, where it forms part of the zygomatic fossa. This 
surface presents a little above its centre the aperture of one or two malar canals, and 
affords attachment to part of two muscles, the temporal above, and the masseter below. 
Of the four processes, the frontal is thick and serrated, and articulates with the 
external angular process of the frontal bone. The orbital process is a thick and 
strong plate, which projects backwards from the orbital margin of the bone. Its 
upper surface, smooth and concave, forms, by its junction with the great ala of 
the sphenoid, the outer wall of the orbit. Its under surface, smooth and convex, 
forms part of the temporal fossa. Its anterior margin is smooth and rounded, 
forming part of the circumference of the orbit. Its superior margin, rough, and 



Tcrrtporo M.ala.r Cancels 




46 



OSTEOLOGY. 



42. — Left Malar Bone. Inner Surface. 




directed horizontally, articulates with the frontal behind the external angular 
process. Its posterior margin is rough and serrated, for articulation with the 
sphenoid; internally it is also serrated for articulation with the orbital process of 
the superior maxillary. At the angle of junction of the sphenoid and maxillary 
portions, a short rounded non-articular margin is sometimes seen; this forms the 
anterior boundary of the spheno- 
maxillary fissure: occasionally, 
no such non-articular surface 
exists, the fissure being completed 
by the direct junction of the 
maxillary and sphenoid bones, 
or by the interposition of a small 
Wormian bone in the angular 
interval between them. 

On the upper surface of the 
orbital process are seen the ori- 
fices of one or two malar canals; 
one of these usually opens on the 
posterior surface, the other (occa- 
sionally two), on the facial sur- 
face: they transmit filaments 
of the orbital branch of the supe- 
rior maxillary nerve. The rnax- 
illary process is a rough trian- 
gular surface, which articulates with the superior maxillary bone. The zygomatic 
process, long, narrow, and serrated, articulates with the zygomatic process of the 
temporal bone. Of the four borders, the superior, or orbital, is smooth, arched, 
and forms a considerable part of the circumference of the orbit. The inferior, or 
zygomatic, is continuous with the lower border of the zygomatic arch, affording 
attachment by its rough edge to the Masseter muscle. The anterior or maxillary 
border is rough, and bevelled at the expense of its inner table, to articulate with 
the superior maxillary bone; affording attachment by its outer margin to the 
levator labii superioris proprius, just at its point of junction with the superior 
maxillary. The posterior or temporal border, curved like an italic f, is con- 
tinuous above with the commencement of the temporal ridge; below, with the 
upper border of the zygomatic arch; it afibrds attachment to the temporal fascia. 

Development. By a single centre of ossification, which appears at about the same 
period when ossification of the vertebra commences. 

Articulations. With four bones: three of the cranium, frontal, sphenoid, and 
temporal; and one of the face, the superior maxillary. 

Attachment of Muscles. Levator labii superioris proprius, Zygomaticus major 
and minor, Masseter, and Temporal. 

The Palate Bones. 

The Palate Bones are situated at the posterior part of the nasal fossas, wedged in 
between the superior maxillary and the pterygoid process of the sphenoid. In form 
they are somewhat like the letter L. Each bone assists in the formation of three cavi- 
ties ; the floor and outer wall of the nose, the roof of the mouth, and the floor of 
the orbit; and enters into the formation of three fossa;; the zygomatic, spheno- 
maxillary, and pterygoid. Each bone consists of two portions; an inferior or 
horizontal plate, a superior or vertical plate. 

The Horizontal Plate is thick, of a quadrilateral form, and presents two sur- 
faces and four borders. The superior surface, concave from side to side, forms 
the back part of the floor of the nares. The inferior surface, slightly concave and 
rough, forms the back part of the hard palate. At its posterior part may be seen 
a transverse ridge, more or less marked, for the attachment of the tendon of the 
Tensor palati muscle. At the outer extremity of this ridge is a deep groove, con- 



PALATE BONE. 



47 



verted into a canal by its articulation with the tuberosity of the superior maxil- 
lary bone, and forming the posterior palatine canal. Near this groove, the orifices 
of one or two small canals, accessory posterior palatine, may frequently be seen. 
The anterior border is serrated, bevelled at the expense of its inferior surface, and 
articulates with the palate process of the superior maxillary bone. The posterior 
border is concave, free, and serves for the attachment of the soft palate. Its 
inner extremity is sharp and pointed, and when united with the opposite bone, 
forms a projecting process, the posterior nasal spine, for the attachment of the 
Azygos uvulae. The external border is united with the lower part of the perpen- 
dicular plate almost at right angles. The internal border, the thickest, is serrated 
for articulation with its fellow of the opposite side; its superior edge is raised 
into a ridge, which, united with the opposite bone, forms a groove, in which the 
vomer is received. 

43) is thin, of an oblong form, and directed upwards 

Left Palate Bone. Internal View (enlarged). 



43-- 



^viicol I'to, 



SfU 



Superior ^fcatu,s. 




The Vertical Plate (fig. 
and a little inwards. It 
presents two surfaces, an 
external and an internal, 
and four borders. 

The internal surface pre- 
sents at its lower part a 
broad shallow depression, 
which forms part of the 
lateral boundary of the in- 
ferior meatus. Immediately 
above this is a well marked 
horizontal ridge, the infe- 
rior turbinated crest, for 
the articulation of the in- 
ferior turbinated bone ; 
above this, a second broad 
shallow depression may 
be seen, which forms part 
of the lateral boundary of 
the middle meatus, sur- 
mounted above by a hori- 
zontal ridge, less prominent 
than the inferior, the superior turbinated crest, for the articulation of the middle 
turbinated bone. Above the superior turbinated crest is a narrow horizontal 
groove, which forms part of the superior meatus. The external surface is rough 
and irregular throughout the greater part of its extent, for articulation with the 
inner surface of the superior maxillary bone, its upper and back part being smooth 
where it enters into the formation of the zygomatic fossa; it is also smooth in 
front, where it covers the orifice of the antrum. This surface presents towards 
its back part a deep groove, converted into a canal, the posterior palatine, by its 
articulation with the superior maxillary bone. It transmits the posterior pala- 
tine vessels and a large nerve. The anterior border is thin, irregular, and presents 
opposite the inferior turbinated crest, a pointed projecting lamina, the maxillary 
process of the palate bone, which is directed forwards, and closes in the lower 
and back part of the opening of the antrum, being received into a fissure that 
exists at the inferior part of this aperture. The posterior border (fig. 44) presents 
a deep groove, the edges of which are serrated for articulation with the ptery- 
goid process of the sphenoid. At the lower part of this border is seen a pyramidal 
process of bone, the pterygoid process or tuberosity of the palate, which is 
received into the angular interval between the two pterygoid plates of the 
sphenoid at their inferior extremity. This process presents at its back part 
three grooves, a median and two lateral ones. The former is smooth, and forms 
part of the pterygoid fossa, aflfording attachment to the Internal pterygoid muscle; 



HORIZONTAL PLATE 



48 



OSTEOLOGY. 



S/ihcTiot^lal firocc&s. 

i/rticular hort. 

on. articuUi/rho rL * 




whilst the lateral grooves are rough and uneven, for articulation with the anterior 
border of each pterygoid plate. The base of this process, continuous with the 
horizontal portion of the bone, presents the apertures of the accessory descending 
palatine canals; whilst its outer surface is rough, for articulation with the inner 
surface of the body of the superior maxillary bone. The superior border of the 

vertical plate presents two well Left Palate Bone. Posterior View (enlarged), 

marked processes, separated by 
an intervening notch or foramen. 
The anterior, or larger,is called the 
orbital process; the posterior, the 
sphenoidal. The Orbital Process, 
directed upwards and outwards, 
is placed on a higher level than 
the sphenoidal. It presents five 
surfaces, which enclose a hollow 
cellular cavity, and is connected 
to the perpendicular plate by a 
narrow constricted neck. Of 
these five surfaces, three are 
articular, two non-articular, or 
free surfaces. The three articu- 
lar are the anterior or maxillary 
surface, which is directed for- 
wards, outwards, and downwards, 
is of an oblong form, and rough 
for articulation with the superior 
maxillary bone. The posterior 
or sphenoidal surface, is directed 

backwards, upwards, and inwards. It ordinarily presents a small half-cellular 
cavity which communicates with the sphenoidal sinus, and the margins of which 
are serrated for articulation with the vertical part of the sphenoidal turbinated bone. 
The internal or ethmoidal surface is directed inwards, upwards and forwards, 
and articulates with the lateral mass of the ethmoid bone. In some cases, the 
cellular cavity above-mentioned opens on this surface of the bone, it then commu- 
nicates with the posterior ethmoidal cells. More rarely it opens on both surfaces, 
and then communicates with the posterior ethmoidal cells, and the sphenoidal 
sinus. The non-articular or free surfaces of the orbital process are the superior 
or orbital, directed upwards and outwards, of a triangular form, concave, smooth, 
articulating with the superior maxillary bone, and forming the back part of the 
floor of the orbit. The external or zygomatic surface, directed outwards, back- 
wards and downwards, is of an oblong form, smooth, and forms part , of the 
zygomatic fossa. This surface is separated from the orbital by a smooth rounded 
border, which enters into the formation of the spheno-maxillary fissure. 

The Sphenoidal Process of the palate bone is a thin compressed plate, much 
smaller than the orbital, and directed upwards and inwards. It presents three 
surfaces and two borders. The superior surface, the smallest of the three, articu- 
lates with the horizontal part of the sphenoidal turbinated bone; it presents a 
groove which contributes to the formation of the pterygo-palatine canal. The 
internal surface is concave, and forms part of the outer wall of the nasal fossa. 
The external surface is divided into two parts, an articular, and a non-articular 
portion; the non-articular portion is smooth and free, forming part of the zygo- 
matic fossa, whilst behind is a rough surface for articulation with the inner surface 
of the pterygoid process of the sphenoid. The anterior border forms the posterior 
boundary of the spheno-palatine foramen. The posterior border, serrated at the 
expense of the outer table, articulates with the internal surface of the pterygoid 
process. 

The orbital and sphenoidal processes are separated from one another by a deep 



INFERIOR TURBINATED BONE. 



49 



notch, which is converted into a foramen, the spheno-palatine, by articulation with 
tlie sphenoidal turbinated bone. Sometimes the two processes are united above, 
and form between them a complete foramen, or the notch is crossed by one or 
more spiculas of bone, so as to form two or more foramina. In the articulated 
skull, this foramen opens into the back part of the outer wall of the superior 
meatus, and transmits the spheno-palatine vessels and nerves. 

Development. From a single centre, which makes its appearance at the angle of 
junction of the two plates of the bone. From this point ossification spreads; in- 
wards, to the horizontal plate; downwards, into the tuberosity; and upwards, into 
the vertical plate. In the foetus, the horizontal plate is much longer than the 
vertical; and even after it is fully ossified, the whole bone is remarkable for its 
shortness. 

Articulations. With seven bones; the sphenoid, ethmoid, superior maxillary, 
inferior turbinated, vomer, opposite palate, and sphenoidal turbinated. 

Attachment of Muscles. The Tensor palati, Azygos uvulee, Internal and External 
pterygoid. 

The Inferior Turbinated Bones. 

The Inferior Turbinated bones are situated one on each side of the outer wall 
of the nasal fossae. Each bone consists of a layer of thin ' spongy ' bone, curled upon 
itself like a scroll, hence its name 'turbinated;' and extending horizontally across 
the outer wall df the nasal fossa, immediately below the orifice of the antrum. 
Each bone pi-esents two surfaces, two borders, and two extremities. 

The internal surface (fig. 45) is convex, perforated by numerous apertures, and 
traversed by longitudinal grooves 



45-- 



-Eight Inferior Turbinated Bone. 
Inner Surface. 




and canals for the lodgment of 
arteries and veins. In the recent 
state it is covered by the lining 
membrane of the nose. The exter- 
nal surface is concave (fig. 46), and 
forms part of the inferior meatus. 
Its upper border is thin, irregular, 
and connected to various bones 
along the outer wall of the nose. 
It may be divided into three por- 
tions; of these, the anterior articu- 
lates .with the inferior turbinated 

crest of the superior maxillary bone; the posterior with the inferior turbinated 
crest of the palate bone; the middle portion of the superior border presents three 

well marked processes, which vary much -r,.,,T^- mi- ,1-r, 

,1 . . J p ^p ,1 •' ^1 4.6. — Rigrnt Intenor Turbmated Bone, 

m their size and form. Of these the ^ * Outer Surface 

anterior and smallest, is situated at the 
junction of the anterior fourth with the 
posterior three-fourths of the bone; it is 
small and pointed, and is called the la- 
chrymal process, for it articulates with the 
anterior inferior angle of the lachrymal 
bone, and by its margins, with the groove 
on the back of the nasal process of the su- 
perior maxillary, and thus assists in forming the lachrymal canal, 
of the two middle fourths of the bone, but encroaching on the latter, a broad thin 
plate, the ethmoidal process, ascends to join the unciform process of the ethmoid; 
from the lower border of this process, a thin lamina of bone curves downwards 
and outwards, hooking over the lower edge of the orifice of the antrum, which 
it narrows below; it is called the maxillary process^, and fixes the bone firmly on 
to the outer wall of the nasal fossa. The inferior border is Tree, thick and cellular 
in structure, more especially in the centre of the bone. Both extremities are 

£ 




At the junction 



so 



OSTEOLOGY. 




more or less narrow and pointed. If the bone is held so that its outer concave 
surface is directed backwards (i.e., towards the holder), and its superior border, 
from which the lachrymal and ethmoidal processes project, upwards, the lachrymal 
process will be directed to the side to which the bone belongs. 

Developments By a single centre which makes its appearance about the middle 
of foetal life. 

Artictilations. With four bones; one of the cranium, the ethmoid, and three of 
the face, the superior maxillary, lachrymal and palate. 

No muscles ai-e attached to this bone. 

The Vomer. 

The Vomer (fig. 47.) is a single bone, situated vertically at the back part of the 
nasal fossas, and forming part of the septum of the nose. It is thin, somewhat 
like a ploughshare in form, but it varies in different individuals, being frequently 
bent to one or the other side; „ 

it presents for examination 
two surfaces and four borders. 
The lateral surfaces are 
smooth, marked with small 
furrows for the lodgment of 
blood-vessels, and by a groove 
on each side, sometimes a 
canal, the naso-palatine, which 
runs obliquely downwards and 
forwards to the intermaxillary 
suture between the two ante- 
rior palatine canals; it trans- 
mits the naso-palatine nerve. 
The superior border, the thick- 
est, presents a deep groove, bounded on each side by a horizontal projecting ala of 
bone; the groove receives the rostrum of the sphenoid, whilst the alte are over- 
lapped and retained by laminae which project from the under surface of the body of 
the sphenoid at the base of the pterygoid processes. At the anterior part of the 
groove a fissure is left for the transmission of blood-vessels to the substance of the 
bone. The inferior border, the longest, is broad and uneven in front, where it arti- 
culates with the two superior maxillary bones; thin and sharp behind where it 
joins with the palate bones. The upper half of the anterior border usually pre- ; 
sents two laminae of bone, which receive between them the perpendicular plate of i| 
the ethmoid, the lower half consisting of a single rough edge, also occasionally 
channelled, which is united to the triangular cartilage of the nose. The posterior 
border is free, concave, and separates the nasal fossEe from one another behind. 
It is thick and bifid above, thin below. 

Development. The vomer at an early period consists of two laming united below, ^ 
but separated above by a very considerable interval. Ossification commences in 
it at about the same period as in the vertebrae. 

Articulations. With six bones; two of the cranium, the sphenoid and ethmoid; 
and four of the face, the two superior maxillary, the two palate bones, and with 
the cartilage of the septum. 

The vomer has no muscles attached to it. 

The Inferior Maxillary Bone. 

The Inferior Maxillary Bone, the largest and strongest bone of the face, serves 
for the reception of the inferior teeth. It consists of a curved horizontal portion, 
the body, and of two perpendicular portions, the rami, which join the former nearly 
at right angles behind. 

The Horizontal portion, or body (fig. 48), is convex in its general outline, and 
curved somewhat like a horse-shoe. It presents for examination two surfaces 



'"'^'^^ Swp .MoiXfiH. 1° 



INFERIOR MAXILLARY BONE. 



51 



and two borders. The External Surface is convex from side to side, concave from 
above downwards. In the median line is a well marked vertical ridge, the sym- 
physis; it extends from the upper to the lower border of the bone, and indicates 

48. — Inferior Maxillary Bone. Outer Surface. Side View. 



Me-niffJ/ 
firocesa 




Groove ^ofjt 



the point of junction of the two pieces of which the bone is composed at an early 
period of life. The lower part of the ridge terminates in a prominent triangular 
eminence, the mental process. On either side of the symphysis, just below the 
roots of the incisor teeth, is a depression, the incisive fossa, for the attachment of 
the Levator menti; and still more externally, a foramen, the mental foramen, for 
the passage of the mental nerve and artery. This foramen is placed just below 
the root of the second bicuspid tooth. Running outwards from the base of the 
mental process on each side, is a well marked ridge, the external oblique line. 
This ridge is at first nearly horizontal, but afterwards inclines upwards and back- 
wards, and is continuous with the anterior border of the ramus; it affords attach- 
ment to the Depressor labii inferioris and Depressor anguli oris, below it, to the 
Platysma myoides. 

The Internal Surface (fig. 49) is concave from side to side, convex from above 
downwards. In the middle line is an indistinct linear depression, corresponding to 
the symphysis externally; on either side of this depression, just below its centre, 
are four prominent tubercles, placed in pairs, two above and two below; they are 
called the genial tubercles, and afford attachment, the upper pair to the Genio-hyo- 
glossi muscles, the lower pair to the Genio-hyodei muscles. Sometimes the 
tubercles on each side are blended into one, or they all unite into an irregular 
eminence of bone, or nothing but an irregularity may be seen on the surface of 
the bone at this part. On either side of the genial tubercles is an oval depression, 
the sublingual fossa, for lodging the sublingual gland; and beneath it a rough 
depression on each side, which gives attachment to the anterior belly of the Digas- 
tric muscle. At the back part of the sublingual fossa, the internal oblique line 
(mylo-hyoidean) commences; it is faintly marked at its commencement, but becomes 
more distinct as it passes upwards and outwards, and is especially prominent 
opposite the two last molar teeth; it divides the lateral surface of the bone into 
two portions, and affords attachment throughout its whole extent to the Mylo-hyoid 
muscle, the Superior constrictor being attached above its posterior extremity, 
nearer the alveolar margin. The portion of bone above this ridge is smooth, and 
covered by the mucous membrane of the mouth; whilst that below it presents an 

E 2 



52 



OSTEOLOGY. 



oblong depression, wider behind than in front, the submaxillary fossa, for the lodg- 
ment of the submaxillary gland. The superior or alveolar border is wider, and its 
margins thicker behind than in front. It is hollowed into numerous cavities, for the 



49. — Inferior Maxillary Bone. Inner Surface. Side View. 



.>tK '^"'^J^. 




GENIO-HYO-GLOSSUS 
CENIO-HYOIDEUS 



Mylo-Tiyoicl Eidje 



Bod 



reception of the teeth; these are sixteen in number, and vary in depth and size accord- 
ing to the teeth which they contain. At an early period of life, before the eruption 
of the teeth, the alveolar process is proportionally larger and deeper than in the adult, 
and the chief part of the body is above the oblique line. In adult life the base of 
the bone attains its maximum of development. In old age, on the contrary, after 
the loss of the teeth, the alveolar process becomes absorbed, and the chief part 
of the body is that which exists below the obliqvie line. At this period, the dental 
canal and mental foramen are situated close to the upper border of the bone. The 
inferior border, longer than the superior, and thicker in front than behind, is rounded; 
it presents a shallow groove, just where the body joins the ramus, over which the 
facial artery turns. 

The Perpendicular Portions, or Rami, are of a quadrilateral form, and differ 
in their direction at various periods of life. In the foetus, they are almost parallel 
with the body; in youth they are oblique; in manhood they are nearly vertical, 
joining the body at almost a right angle. In old age, after the loss of the teeth, 
they again decline and assume an oblique direction. Each ramus presents for 
examination two surfaces, four borders, and two processes. The external surface 
is flat, marked with ridges, and gives attachment throughout nearly the whole of 
its extent to the Masseter muscle. The internal surface presents about its centre 
the oblique aperture of the inferior dental canal, for the passage of the inferior dental 
vessels and nerve. The margins of this opening are irregular, and present in front 
a prominent ridge, surmounted by a sharp spine, which gives attachment to the 
internal lateral ligament of the lower jaw; and at its lower and back part is 
seen a notch leading to a groove, which runs obliquely downwards to the pos- 
terior extremity of the submaxillary fossa; this groove is the mylo-hyoidean, and 
lodges the mylo-hyoid vessels and nerve; behind the groove is a rough surface, 
for the insertion of the Internal pterygoid muscle. The inferior dental canal 
descends obliquely downwards and forwards in the substance of the ramus, and 
then horizontally forwards in the body; it is here placed under the alveoli, with 
which it communicates by small openings. On arriving at the incisor teeth, it 



SUTURES OF THE SKULL. 



53 



turns back to communicate with the mental foramen, giving off two Bmall canals, 
which run forward, to be lost in the cancellous tissue of the bone beneath the in- 
cisor teeth. This canal, in the posterior two-thirds of the bone, runs nearest the 
internal surface of the jaw; and in the anterior third, nearer its external surface. 
Its walls are composed of compact tissue at either extremity, cancellous in the centre. 
It contains the inferior dental vessels and nerve, from which branches are distributed 
to the teeth through the small apertures at the bases of the alveoli. The superior 
border is thin, and presents two processes, separated by a deep concavity, the 
sigmoid notch. Of these processes, the anterior is the coronoid, the posterior the 
condyloid. 

The Coronoid Process is a thin, flattened, triangular eminence of bone, which 
varies in length in different subjects. Its external surface is smooth, and affords 
attachment to the masseter and temporal muscles. Its interyial surface gives 
attachment to the temporal muscle, and presents the commencement of a longitu- 
dinal ridge, which is continued to the posterior part of the alveolar process. In 
front of this ridge is a deep groove, continued below on to the outer side of the 
alveolar process; this ridge and part of the groove afford attachment above to 
the Temporal, below to the Buccinator muscle. 

The Condyloid Process, shorter but thicker than the coronoid, consists of two 
portions; the condyle, and the constricted portion which supports the condyle, the 
neck. The condyle is of an oval form, its long axis being transverse, and placed 
in such a manner that its outer end is a little more forward and a little higher 
than its inner. It is convex from before backwards, and from side to side, the 
articular surface extending further on the posterior than on the anterior surface. 
The neck of the condyle is flattened from before backwards. Its posterior surface 
is convex; its anterior is hollowed out on its inner side by a depression (the 
pterygoid fossa), for the attachment of the External pterygoid. The lower border 
of the ramus is thick, straight, and continuous with the body of the bone. At its 
junction with the posterior border is the angle of the jaw, which is somewhat everted, 
rough on each side for the attachment of the masseter externally, and the internal 
pterygoid internally, and, between them, serving for the attachment of the stylo- 
maxillary ligament. The anterior border is thin above, thicker below, and continu- 
ous with the external oblique line. The posterior border is thick, smooth, and 
rounded, and covered by the parotid gland. 

The Sigmoid Notch, separating the two processes, is a deep semilunar depres- 
sion, crossed by the masseteric artery and nerve. 

Development. This bone is formed at such an early period of life, befoi'e, indeed, 
any other bone excepting the clavicle, that it has been found impossible at present 
to determine its earliest condition. It appears probable, however, that it is deve- 
loped by two centres, one for each lateral half, the two segments meeting at the 
symphysis, where they become united. Additional centres have also been described 
for the coronoid process, the condyle, the angle, and the thin plate of bone, which 
forms the inner side of the alveolus. At birth it consists of two lateral halves. 
These join at the symphysis at the end of the first year; but a trace of separation 
at their upper part is seen at the commencement of the second year. 

Articulations. With the glenoid fossae of the two temporal bones. 

Attachment of 3Iuscles. By its external surface, commencing at the symphysis, 
and proceeding backwards; Levator menti, Depressor labii inferioris. Depressor 
anguli oris, Platysma myoides, Buccinator, Masseter. By its internal surface, com- 
mencing at the same point; Genio-hyo-glossus, Genio-hyoideus, Mylo-hyoideus, 
Digastric, Superior constrictor. Temporal, Internal pterygoid. External pterygoid. 

Articulations of the Cranial Bones. 

The bones of the cranium and face, are connected to each other by means of 
sutures. The Cranial Sutures may be divided into three sets: I. Those of the 
vertex of the skull. 2. Those at the side of the skull. 3. Those at the base. 



54 OSTEOLOGY. 

The sutures at the vertex of the skull are three, the sagittal, coronal, and 
lambdoid. 

The Sagittal Suture {sagitta, an arrow) is formed by the junction of the two 
parietal bones, and extends from the middle of the frontal bone, backwards to the 
superior angle of the occipital. In childhood, and occasionally in the adult, when 
the two halves of the frontal bone are not united, it is continued forwards to the 
root of the nose. This suture sometimes presents, near its posterior extremity, the 
parietal foramen on each side; and in front, where it joins the coronal suture, a 
space is occasionally left, which encloses a large Wormian bone. 

The Coronal Suture extends transversely across the vertex of the skull, and 
connects the frontal with the parietal bones. It commences at the extremity of 
the great wing of the sphenoid on one side, and terminates at the same point on 
the opposite side. The dentations of this suture are more marked at the sides than 
at the summit, and are so constructed that the frontal rests on the parietal above, 
whilst laterally the parietal supports the frontal. 

The Lambdoid Suture, so called from its resemblance to the Greek letter X, 
connects the occipital with the parietal bones. It commences on each side at the 
angle of the mastoid portion of the temporal bone, and inclines upwards to the end 
of the sagittal suture. The dentations of this suture are very deep and distinct, 
and are often interrupted by several small Wormian bones. 

The sutures at the side of the skull are also three in number; the spheno-parietal, 
squamo-parietal, and masto-parietal. They are subdivisions of a single suture, 
formed between the lower border of the parietal, and the temporal and sphenoid 
bones, and extending from the lower end of the lambdoid suture behind, to the lower 
end of the coronal suture in front. 

The Spheno-parietal is very short, and formed by the tip of the great wing of 
the sphenoid, and the anterior inferior angle of the parietal bone. 

The Squamo-parietal, or squamous suture, is arched. It is formed by the squa- 
mous portion of the temporal bone overlapping the middle division of the lower 
border of the parietal. 

The Masto-parietal is a short suture, deeply dentated, formed by the posterior 
inferior angle of the parietal, and the superior border of the mastoid portion of 
the temporal. 

The sutures at the base of the skull are the basilar in the centre, and on each 
side, the petro-occipital, the masto-occipital, the petro-sphenoidal, and the squamo- 
sphenoidal. 

The Basilar Suture is formed by the junction of the basilar surface of the 
occipital bone with the posterior surface of the body of the sphenoid. At an 
early period of life a thin plate of cartilage exists between these bones, but in the 
adult they become inseparably united. Between the outer extremity of the basilar 
suture, and the termination of the lambdoid, an irregular suture exists which is 
subdivided into two portions. The inner portion, formed by the union of the 
petrous part of the temporal, with the occipital bone, is termed the petro-occipital. 
The outer portion, formed by the junction of the mastoid part of the temporal with 
the occipital, is called the masto-occipital. Between the bones forming the petro- 
occipital suture, a thin plate of cartilage exists; in the masto-occipital is occa- 
sionally found the opening of the mastoid foramen. Between the outer extremity 
of the basilar suture and the spheno-parietal, an irregular suture may be seen 
formed by the union of the sphenoid with the temporal bone. The inner and 
smaller portion of this suture is termed the petro-sphenoidal; it is formed between 
the petrous portion of the temporal, and the great wing of the sphenoid; the 
outer portion, of greater length, and arched, is formed between the squamous por- 
tion of the temporal and the great wing of the sphenoid, it is called the squamo- 
sphenoidal. 

The cranial bones are connected with those of the face, and the facial with each 
other, by numerous sutures, which, though distinctly marked, have received no 
special names. The only remaining suture deserving especial consideration is the 



THE SKULL. 



55 



transverse. This extends across the upper part of the face, and is formed by the 
junction of the frontal with the facial bones; it extends from the external angular 
process of one side, to the same point on the opposite side, and connects the frontal 
with the malar, the sphenoid, the ethmoid, the lachrymal, the superior maxillary, 
and the nasal bones on each side. 

The Skull. 

The Skull, formed by the union of the several cranial and facial bones already 
described, when considered as a whole, is divisible into five regions; a superior 
region or vertex, an inferior region or base, two lateral regions, and an anterior 
region, the face. 

The Superior Region, or vertex, presents two surfaces, and external and an 
internal. The External Surface is bounded in front by the nasal eminences, and 
superciliary ridges; behind, by the occipital protuberance and superior curved lines 
of the occipital bone, laterally, by an imaginary line extending from the outer end 
of the superior curved line, along the temporal ridge, to the external angular pro- 
cess of the frontal. This surface includes the vertical portion of the frontal, the 
greater part of the parietal, and the superior third of the occipital bone; it is 
smooth, convex, of an elongated oval form, crossed transversely by the coronal 
suture, and from before backwards by the sagittal, which terminates behind in the 
lambdoid. From before backwards may be seen the frontal eminences and remains 
of the suture connecting the two lateral halves of the frontal bone ; on each side of 
the sagittal suture is the parietal foramen and parietal eminence, and still more 
posteriorly the smooth convex surface of the occipital bone. 

The Internal Surface of the vertex is concave, presents eminences and de- 
pressions for the convolutions of the brain, and numerous furrows for the lodgment 
of branches of the meningeal arteries. Along the middle line of this surface is a 
longitudinal groove, narrow in front, where it terminates in the frontal crest, 
broader behind; it lodges the superior longitudinal sinus, and its mai-gins aiford 
attachment to the falx cerebri. On either side of it are several depressions for the 
Pacchionian bodies, and at its back part, the internal openings of the parietal 
foramina. This surface is also crossed in front by the coronal suture; from before 
backwards, by the sagittal; behind, by the lambdoid. 

Base of the Skull. 

The Inferior Region, or base of the skull presents two surfaces, an internal or 
cerebral, and an external or basilar. 

The Internal, or Cerebral Surface (fig. 50.), is divisible into three parts, or 
fossje, called the anterior, middle, and posterior fossae of the cranium. 

The Anterior Fossa is formed by the orbital plate of the frontal, the cribriform 
plate of the ethmoid, the ethmoidal process and lesser wing of the sphenoid. It 
is the most elevated of the three fossae, convex on each side where it corresponds 
to the roof of the orbits, concave in the median line in the situation of the cribri- 
form plate of the ethmoid. It is traversed by three sutures, the ethmoido-frontal, 
ethmo- sphenoidal, and fronto- sphenoidal, and lodges the anterior lobes of the cere- 
brum. It presents in the median line from before backwards, the commencement of 
the groove for the superior longitudinal sinus, and crest for the attachment of the falx 
cerebri; the foramen ccecum, this aperture is formed by the frontal and crista galli 
of the ethmoid, and if pervious, transmits a small vein from the nose to the superior 
longitudinal sinus. Behind the foramen coecum is the crista galli, the posterior 
margin of which affords attachment to the falx cerebri. On either side of the 
crista galli is the olfactory groove, which supports the bulb of the olfactory nerves, 
perforated by the three sets of orifices which give passage to its filaments; and in 
front by a slit-like opening, which transmits the nasal branch of the ophthalmic 
nerve. On each side are the internal openings of the anterior and posterior 
ethmoidal foramina, the former, situated about the middle of its outer margin, 
transmitting the nasal nerve, which runs in a groove along its surface, to the slit- 



56 



OSTEOLOaY. 



like opening above mentioned; whilst the latter, the posterior ethmoidal foramen, 
opens at the back part of this margin under cover of a projecting lamina of the 

50. — Base of Skull. Inner or Cerebral Surface. 



Groove fir Shi-per. Zimgitud, Sinios 

drooves for ATite^r. MoTiinyealA'!- 

Toramev, C/ecitr/i,- 

Critstn, GnMi 

Slit for "N/ii.ial ru.riKi. 

j^ntcrior JEckmohdaUui: 

Ovifiees fop OlftwtoryneTfe 
Poxtcrior Edimoidnl Fo'. 



Olfaatory ffrootfcs^ 

O^tio Toravicn 

Optic OTOove- 

Oliiianj pvoot 

AjiterwT ClcTwid prac: 

Middle Cluioid -proc 

Posterior Clinorid jprco. 

Groove for ffih norve 

Tor^ laeerum medium' 

Orifice of Carotid Canal 

Dcpres^wn for CctsjicrCan Ganiglvon 



Meatus Auditor. Internus 

Slit for Diora-Mater 

Sup. Petrosal grooi^C' 

For. laeerum, posterius 

AiUcrior CondyToLd JTn 71 

Aqueduct. Ve<stihtiJi 

Pot^terior Cond'ifloid For. 



Mastoid Far. 
Post. 3fenin,g ea,l Grooifes, 




sphenoid, it transmits the posterior ethmoidal artery and vein to the posterior 
ethmoidal cells. Further back in the middle line is the ethmoidal spine, bounded 
])ehind by an elevated ridge, separating a longitudinal groove on each side which 



BASE OF THE SKULL. 



■57 



support the olfactory nerves. The anterior fossa presents laterally eminences and 
depressions for the convolutions of the brain, and grooves for the lodgment of 
the anterior meningeal arteries. 

The Middle Fossa, somewhat deeper than the preceding, is narrow in the middle, 
and becomes wider as it expands laterally. It is bounded in front by the poste- 
rior margin of the lesser wing of the sphenoid, the anterior clinoid process, and the 
anterior margin of the optic groove; behind, by the petrous portion of the temporal, 
and basilar suture; externally, by the squamous portion of the temporal, and 
anterior inferior angle of the parietal bone, and is divided into two lateral parts 
by the sella Turcica. It is traversed by four sutures, the squamous, spheno-parietal, 
spheno-temporal, and petro-sphenoidal. 

In the middle line, from before backwards, is the optic groove, which supports 
the optic commissure, terminating on each side in the optic foramen, for the 
passage of the optic nerve and ophthalmic artery, behind is seen the olivary 
process, and laterally the anterior clinoid processes, which afford attachment to 
the folds of the dura mater, which form the cavernous sinus. In the centre of the middle 
fossa is the sella Turcica, a deep depression, which lodges the pituitary gland, 
bounded in front by a small eminence on either side, the middle clinoid process, 
and behind by a broad square plate of bone, surmounted at each superior angle 
by a tubercle, the posterior clinoid process; beneath the latter process is a groove, 
for the lodgment of the sixth nerve. On each side of the sella Turcica is the 
cavernous groove; it is broad, shallow, and curved somewhat like the italic letter 
f; it commences behind at the foramen lacerum medium, and terminates on the 
inner side of the anterior clinoid process. This groove lodges the cavernous sinus, 
the internal carotid artery, and the orbital nerves. The sides of the middle fossa 
are of considerable depth; they present eminences and depressions for the middle 
lobes of the brain, and grooves for lodging the branches of the middle meningeal 
artery'; these commence on the outer side of the foramen spinosum, and consist of 
two large branches, an anterior rnd a posterior; the former passing upwards and 
forwards to the anterior inferior angle of the parietal bone, the latter passing 
upwards and backwards. The following foramina may also be seen from before 
backwards. Most anteriorly is the foramen lacerum anterius, or sphenoidal fissure, 
formed above by the lesser wing of the sphenoid; below, by the greater wing; 
internally, by the body of the sphenoid; and completed externally by the orbital 
plate of the frontal bone. It transmits the third, fourth, the three branches of 
the ophthalmic division of the fifth, the sixth nerve, and the ophthalmic vein. 
Behind the inner extremity of the sphenoidal fissure is the foramen rotundum, for 
the passage of the second division of the fifth or superior maxillary nerve; still 
more posteriorly is seen a small orifice, the foramen Vesalii; this opening is situ- 
ated between the foramen rotundum and ovale, a little internal to both; it varies 
in size in different individuals, and transmits a small vein. It opens below in 
the pterygoid fossa, just at the outer side of the scaphoid depression. Poste- 
riorly and externally is the foramen ovale, which transmits the third division of 
the fifth or inferior maxillary nerve, the small meningeal artery, and the small 
petrosal nerve. On the outer side of the foramen ovale is the foramen sjjinosum, 
for the passage of the middle meningeal artery ; and on the inner side of the foramen 
ovale, the foramen lacerum medium. This aperture in the recent state is filled up 
with cartilage. On the anterior surface of the petrous portion of the temporal 
bone is seen from without inwards, the eminence caused by the projection of the 
superior semicircular canal, the groove leading to the hiatus Fallopii, for the 
transmission of the petrosal branch of the Vidian nerve; beneath it, the smaller 
groove, for the passage of the smaller petrosal nerve; and near the apex of the 
bone, the depression for the semilunar ganglion, and the orifice of the carotid canal, 
for the passage of the internal carotid artery and carotid plexus of nerves. 

The Posterior Fossa, deeply concave, is the largest of the three, and situated 
on a lower level than either of the preceding. It is formed by the occipital, the 
petrous and mastoid portions of the temporal, and the posterior inferior angle of 



58 OSTEOLOGY. 

the parietal bones; is crossed by three sutures, the petro-occipital, masto-occipital, 
and masto-parietal; and lodges the cerebellum, pons varolii, and medulla oblon- 
gata. It is separated from the middle fossa in the median line by the basilar 
suture, and on each side by the superior border of the petrous portion of the 
temporal bone. This serves for the attachment of the tentorium cerebelli, is 
grooved externally for the superior petrosal sinus, and at its inner extremity pre- 
sents a notch, upon which rests the fifth nerve. Its circumference is bounded 
posteriorly by the groove for the lateral sinus. In the centre of this fossa is 
the foramen magnum, bounded on either side by a rough tubercle, which gives 
attachment to the odontoid ligaments; and a little above these are seen the in- 
ternal openings of the anterior condyloid foramina. In front of the foramen 
magnum is the basilar process, grooved for the support of the medulla oblongata 
and pons varolii, and articulating on each side with the petrous portion of the tem- 
poral bone, forming the petro-occipital suture, the anterior half of which is grooved 
for the inferior petrosal sinus, the posterior half being encroached upon by the 
foramen lacerum posterius, or jugular foramen. This foramen is partially subdivided 
into two parts; the posterior and larger division transmits the internal jugular 
vein, the anterior the eighth pair of nerves. Above the jugular foramen is the 
internal auditory foramen, for the auditory and facial nerves and auditory artery; 
behind and external to this is the slit-like opening leading into the aquaeductus 
vestibuli; whilst between these two latter, and near the superior border of the 
petrous portion, is a small triangular depression, which lodges a process of the 
dura mater, and occasionally transmits a small vein into the substance of the 
bone. Behind the foramen magnum are the inferior occipital fossse, which lodge 
the lateral lobes of the cerebellum, separated from one another by the internal 
occipital crest, which serves for the attachment 'of the falx cerebelli, and lodges 
the occijDital sinuses. These fosste are surmounted, above, by the deep transverse 
grooves for the lodgment of the lateral sinuses, that on the right side being usually 
larger than the left. These channels, in their passage outwards, groove the occi- 
pital bone, the posterior inferior angle of the parietal, the mastoid portion of the 
temporal, and the occipital just behind the jugular foramen, at the back part of 
which they terminate. Where this sinus grooves the mastoid part of the temporal 
bone, the orifice of the mastoid foramen may be seen; and just previous to its 
termination it has opening into it the posterior condyloid foramen. 

The External Surface of the base of the Skull (fig. 51) is extremely irregular. 
It is bounded in front by the incisor teeth in the upper jaws; behind, by the 
superior curved lines of the occipital bone; and laterally, by the lower border of 
the malar bone, the zygomatic arch, and an imaginary line, extending from the 
zygoma to the mastoid process and extremity of the superior curved line of the 
occiput. It is formed by the palate processes of the two superior maxillary and 
palate bones, the vomer, the pterygoid, under surface of the great wing, spinous 
process and part of the body of the sphenoid, the under surface of the squamous, 
mastoid, and petrous portions of the temporal, and occipital bones. The anterior 
part of the base of the skull is raised above the level of the rest of this sur- 
face (when the skull is turned over for the purpose of examination), surrounded 
by the alveolar process, which is thicker behind than in front, and excavated by 
sixteen depressions for lodging the teeth of the' upper jaw; they vary in depth and 
size according to the teeth they contain. Immediately behind the incisor teeth is 
the anterior palatine fossa or canal. At the bottom of this fossa may usually be 
seen four apertures, two placed laterally, which open above, one in the floor of 
each nostril, and transmit the anterior palatine vessels, and two in the median 
line of the intermaxillary suture, one in front of the other, the most anterior one 
transmitting the left, and the posterior one (the larger) the right naso-palatine 
nerve. These two latter canals are sometimes wanting, or they may join to form 
a single one, or one of them may open into one of the lateral canals above re- 
ferred to. The palatine vault is concave, uneven, perforated by numerous nutri- 
tious foramina, marked by depressions for the palatal glands, and crossed by a 



BASE OF SKULL. 



59 



crucial suture, which indicates the point of junction of the four bones of which 
it is composed. One or two small foramina, seen in the alveolar margin behind 

51. — Base of Skull. External Surface. 



A/it. pala/ti'/ne fossa 

^mJiSTnlts left Mi'SO'/ialiCt. n. 
nsmlts A^ni.palaT. vess. 
Transmiis rigJOi Naso-faZoJl. n.. 




Aectis soTy palatine 
Fm-amiTha. 

Post.NcLscttl SpCiie. 

AZVaOS UVUL/E 

RarruHar j>ree 



^^Ji^noid.pros, of Pcohote. 



TENSOR TYNlPflNI. 

-PJiaryiufcal Spine. fvT suP. constrict. 

'it^ of j:astacMin tu.la&LCanalfarJenso.r Tymf 
LAXATOR TYWPAWf. 

Caiml for JacolsmCs n. 
—Aqiiedtict. CucIiUn.. 
For.liwcri<.m,posteTiu.s. 
CaiialftrrArnold.'s n. 
lu-ricular fissicre- 



6o OSTEOLOGY. 

the incisor teeth, occasionally seen in the adult, almost constant in young subjects, 
are called the incisive foramina; they transmit nerves and vessels to the incisor 
teeth. At each posterior angle is the posterior palatine foramen, for the transmis- 
sion of the posterior palatine vessels and anterior palatine nerve, and running for- 
wards and inwards from it a groove, which lodges the same vessels and nerve. 
Behind the posterior palatine foramen is the tuberosity of the palate bone, perforated 
by one or more accessory posterior palatine canals, and marked by the commencement 
of a ridge, which runs transversely inwards, and serves for the attachment of the 
tendinous expansion of the tensor palati muscle. Projecting backwards from the 
centre of the posterior border of the hard palate is the posterior nasal spine, for 
the attachment of the Azygos uvulfe. Behind and above the hard palate is the 
posterior aperture of the nares, divided into two parts by the vomer, bounded 
above by the body of the sphenoid, below by the horizontal plate of the palate 
bone, and laterally by the pterygoid processes of the sphenoid. Each aperture 
measures about an inch in the vertical, and half an inch in the transverse direc- 
tion. At the base of the vomer may be seen the expanded alse of this bone, 
receiving between them the rostrum of the sphenoid. Near the lateral margins of 
the vomer, at the root of the pterygoid process, are the pterygo-palatine canals. 
The pterygoid process, which bounds the posterior nares on each side, presents 
near its base the pterygoid or Vidian canal, for the Vidian nerve and artery. 
Each process consists of two plates, which bifurcate at the extremity to receive 
the tuberosity of the palate bone, and are separated behind by the pterygoid fossa, 
which lodges the Internal pterygoid muscle. The internal plate is long and nar- 
row, presenting on the outer side of its base the scaphoid fossa, for the origin of 
the Tensor palati muscle, and at its extremity the hamular process, around which 
the tendon of this muscle turns. The external pterygoid plate is broad, forms 
the inner boundary of the zygomatic fossa, and affords attachment to the External 
pterygoid muscle. 

Behind the nasal fossa in the middle line is the basilar surface of the occipital 
bone, presenting in its centre the pharyngeal spine for the attachment of the 
Superior constrictor muscle of the pharynx, with depressions on each side for the 
insertion of the Rectus anticus major and minor. At the base of the external 
pterygoid plate is the foramen ovale; behind this, the foramen spinosum, and the 
prominent spinous process of the sphenoid, which gives attachment to the internal 
lateral ligament of the lower jaw and the Laxator tympani muscle. External to 
the spinous process is the glenoid fossa, divided into two parts by the Glaserian 
fissure, the anterior portion being concave, smooth, bounded in front by the eminentia 
articularis, and serving for the articulation of the condyle of the lower jaw; the 
posterior portion rough, bounded behind by the vaginal process, and serving for 
the reception of part of the parotid gland. Emerging from between the laminas 
of the vaginal process is the styloid process; and at the base of this process is the 
stylo-mastoid foramen, for the exit of the facial nerve, and entrance of the stylo- 
mastoid artery. External to the stylo-mastoid foramen is the auricular fissure 
for the auricular branch of the pneumogastric, bounded behind by the mastoid 
process. Upon the inner side of this process is a deep groove, the digastric fossa; 
and a little more internally, the occipital groove, for the occipital artery. At the 
base of the internal pterygoid plate is a large and somewhat triangular aperture, 
the foramen lacerum medium, bounded in front by the great wing of the sphenoid, 
behind by the apex of the petrous portion of the temporal bone, and internally by 
the body of the sphenoid and basilar process of the occipital bone; it presents in 
front the posterior orifice of the Vidian canal, behind the aperture of the carotid 
canal. This opening is filled up in the recent subject by a fibro-cartilaginous 
substance; across its upper or cerebral aspect passes the internal carotid artery 
and Vidian nerve. External to this aperture, the petro-sphenoidal suture is 
observed, at the outer termination of which is seen the orifice of the canal for the 
Eustachian tube, and that for the Tensor tympani muscle. Behind this suture is 
seen the under surfixce of the petrous portion of the temporal bone, presenting, 



LATERAL REGION OF THE SKULL. 6i 

from within outwards, the quadrilateral rough surface, part of which affords 
attachment to the Levator palati and Tensor tympani muscles ; behind this surface 
are the orifices of the carotid canal and the aquEeductus cochleae, the former trans- 
mitting the internal carotid artery and the ascending branches of the superior 
cervical ganglion of the sympathetic, the latter serving for the passage of a small 
artery and vein to the cochlea. Behind the carotid canal is a very large irregular 
aperture, the jugular fossa, formed in front by the petrous portion of the temporal, 
and behind by the occipital; it is generally larger on the right than on the left 
side, and is perforated at the bottom by an irregular aperture ; it is divided into two 
parts by a ridge of bone, which projects usually from the temporal; the anterior, 
or smaller portion, transmitting the three divisions of the eighth pair of nerves; 
the posterior, transmitting the internal jugular vein and the two ascending menin- 
geal vessels, from the occipital and ascending pharyngeal arteries. On the ridge 
of bone dividing the carotid canal from the jugular fossa, is the small foramen for 
the transmission of the tympanic nerve; and on the outer wall of the jugular 
foramen, near the root of the styloid process, is the small aperture for the trans- 
mission of Arnold's nerve. Behind the basilar surface of the occipital bone is the 
foramen magnum, bounded on each side by the condyles, rough internally for the 
attachment of the alar ligaments, and presenting externally a rough surface, the 
jugular process, which serves for the attachment of the Rectus lateralis. On either 
side of each condyle anteriorly is the anterior condyloid fossa, perforated by the 
anterior condyloid foramen, for the passage of the lingual nerve. Behind each 
condyle are the posterior condyloid foss«, perforated on one or both sides by the 
posterior condyloid foramina, for the transmission of a vein to the lateral sinus. 
Behind the foramen magnum is the external occipital crest, terminating above at 
the external occipital tuberosity, whilst on each side are seen the superior and 
inferior curved lines; these, as well as the surfaces of the bone between them, 
being rough for the attachment of numerous muscles. 

Lateral Regions op the Skull. 

The Lateral Regions of the Skull are somewhat of a triangular form, their 
base being formed by a line extending from the external angular process of 
the frontal bone along the temporal ridge backwards to the outer extremity of the 
superior curved line of the occiput; and the sides being formed by two lines, the 
one drawn downwards and backwards from the external angular process of the 
frontal bone to the angle of the lower jaw, the other from the angle of the jaw 
upwards and backwards to the extremity of the superior curved line. This 
region is divisible into three portions, temporal, mastoid, and zygomatic. 

The Temporal Foss^. 

The Temporal Portion, or fossa, is bounded above and behind by the temporal 
ridge, which extends fi-om the external angular process of the frontal upwards and 
backwards across the frontal and parietal bones, curving downwards behind to 
terminate at the root of the zygomatic process. La front, it is bounded by the 
frontal, malar, and great wing of the sphenoid: externally, by the zygomatic arch, 
formed conjointly by the malar and temporal bones; below, it is separated from 
the zygomatic fossa by the pterygoid ridge, seen on the under surface of the great 
wing of the sphenoid. This fossa is formed by five bones, part of the frontal, 
great wing of the sphenoid, parietal, squamous portion of the temporal, and malar 
bones, and is traversed by five sutures, the transverse facial, coronal, spheno- 
parietal, squamo-parietal, and squamo- sphenoidal. It is deeply concave in front, 
convex behind, traversed by numerous grooves for lodging the branches of the 
deep temporal arteries, and filled by the temporal muscle. 

The Mastoid Portion is bounded in front by the anterior horizontal root of the 
zygoma; above, by a line which corresponds with the posterior root of the zygoma 
and the masto-parietal suture; behind and inferior ly, by the masto-occipital suture. 
It is formed by the mastoid and part of the squamous portion of the temporal bone; 



62 OSTEOLOGY. 

its surface is convex and rough for the attachment of muscles, and presents, from 
behind forwards, the mastoid foramen, below the mastoid process. In front of the 
mastoid process is the external auditory meatus, surrounded by the auditory pro- 
cess. Anterior to the meatus is the Glenoid fossa, bounded in front by the tubercle 
of the zygoma, behind by the auditory process, and above by the middle root of 
the zygoma, which terminates at the Glaserian fissure. 

The Ztgomatic Foss^. 

The Zygomatic fossae, are two irregular-shaped cavities, situated one on each 
side of the head, below, and on the inner side of the zygoma ; bounded in 
front by the tuberosity of the superior maxillary bone and the ridge which 
descends from its malar process; behind, by the posterior border of the pterygoid 
process; above, by the pterygoid ridge on the under surface of the great wing of 
the sphenoid and squamous portion of the temporal; below, by the alveolar 
border of the superior maxilla; internally, by the external pterygoid plate; and 
externally, by the zygomatic arch and ramus of the jaw. It contains the lower 
part of the Temporal, the External, and Internal pterygoid muscles, the internal 
maxillary artery, the inferior maxillary nerve, and their branches. At its upper 
and inner part may be observed two fissures, the spheno-maxillary and pterygo- 
maxillary. 

The Spheno-maxillary fissure, horizontal in direction, opens into the outer and 
back part of the orbit. It is formed above by the lower border of the orbital 
surface of the great wing of the sphenoid; below, by the posterior rounded border 
of the superior maxilla and a small part of the palate bone; externally, by a small 
part of the malar bone; internally, it joins at right angles with the ptery go- 
maxillary fissure. This fissure opens a communication from the orbit into three 
fossae, the temporal, zygomatic, and spheno-maxillary; it transmits the superior max- 
illary nerve, infra-orbital artery, and ascending branches from Meckel's ganglion. 

The Ptery go -maxillary fissure is vertical, and descends at right angles from 
the inner extremity of the preceding; it is a triangular interval, formed by the 
divergence of the superior maxillary bone from the pterygoid process of the 
sphenoid. It serves to connect the spheno-maxillary fossa with the zygomatic, 
and transmits branches of the internal maxillary artery. 

Thk Spheno-maxillary Fossa. 

The Spheno-maxillary fossa is a small triangular space situated at the angle of 
junction of the spheno-maxillary and pterygo-maxillary fissures, and placed beneath 
the apex of the orbit. It is formed above by a small part of the under surface of 
the body of the sphenoid; in front, by the superior maxillary bone; behind, by the 
pterygoid process of the sphenoid; internally by the vertical plate of the palate; 
externally, it communicates with the spheno-maxillary fissure. This fossa has three 
fissures terminating in it, the sphenoidal, spheno-maxillary, and pterygo-maxillary; 
it communicates with three fossae, the orbital, nasal, and zygomatic, and with the 
cavity of the cranium, and has opening into it five foramina. Of these there are 
three on the posterior wall, the foramen rotundum above, the Vidian below and 
internal, and still more inferior and internal, the pterygo-palatine. On the inner 
wall is the spheno-palatine foramen by which it communicates with the nasal fossa, 
and below, the superior orifice of the posterior palatine canal, besides occasionally 
the orifices of two or three accessory posterior palatine canals. 

Anterior Region of the Skull. (Fig. 52.) 

The Anterior Region of the Skull, which forms the face, is of an oval form, 
presents an irregular surface, and is excavated for the reception of the two prin- 
cipal organs of sense, the eye and the nose. It is bounded above by the nasal 
eminences and margins of the orbit; below, by the prominence of the chin; on each 
side, by the malar bone, and anterior margin of the ramus of the jaw. In the 
median line are seen from above downwards, the nasal eminences, which indicate 



ANTERIOR REGION OF THE SKULL. 



63 



the situation of the frontal sinuses; diverging outwards from them, the super- 
ciliary ridges which support the eyebrows. Beneath the nasal eminences is the 
arch of the nose, formed by the nasal bones, and the nasal process of the superior 
maxillary. The nasal arch is convex from side to side, concave from above down- 
wards, presenting in the median line the inter-nasal suture, formed between the 
nasal bones, laterally the naso-maxillary suture, formed between the nasal and the 
nasal process of the superior maxillary bones, both these sutures terminating above 
in that part of the transverse suture which connects the nasal bones and nasal pro- 
cesses of the superior maxillary with the frontal. Below the nose is seen the 
heart-shaped opening of the anterior nares, the narrow end upwards, and broad 
below; it presents laterally the thin sharp margins which serve for the attachment 

52. — Anterior Eegion of the Skull. 



TENBO OCUJLr 



Amt. Nasal /SiptTie 
Incisive fossd- 




of the lateral cartilages of the nose, and in the middle line below, a prominent 
process, the anterior nasal spine, bounded by two deep notches. Below this is the 
intermaxillary suture, and on each side of it the incisive fossa. Beneath this fossa 
is the alveolar process of the upper and lower jaw, containing the incisive teeth, 
and at the lower part of the median line, the symphysis of the chin, the mental 
emine'nce, and the incisive fossa of the lower jaw. 

Proceeding from above downwards, on each side are the supra orbital ridges, 
terminating externally in the external angular process at its junction with the 
malar, and internally in the internal angular process; towards the inner third of 
this ridge is the supra orbital notch or foramen, for the passage of the supra or- 
bital vessels and nerve, and at its inner side a slight depression for the attachment 



64 OSTEOLOGY. 

of the cartilaginous pulley of the superior oblique muscle. Beneath the supra- 
orbital ridges are the openings of the orbits, bounded externally by the orbital 
ridge of the malar bone ; below, by the orbital ridge formed by the malar, superior 
maxillary, and lachrymal bones; internally, by the nasal process of the superior 
maxillary, and the internal angular process of the frontal bone. On the outer 
side of the orbit, is the quadrilateral anterior surface of the malar bone, perforated 
by one or two small malar foramina. Below the inferior margin of the orbit, is 
the infra-orbital foramen, the termination of the infra-orbital canal, and beneath 
this, the canine fossa, which gives attachment to the Levator anguli oris; bounded 
below by the alveolar processes, containing the teeth of the upper and lower jaw. 
Beneath the alveolar arch of the lower jaw is the mental foramen for the passage 
of the mental nerve and artery, the external oblique line, and at the lower border 
of the bone, at the point of junction of the body with the ramus, a shallow groove 
for the passage of the facial artery. 

The Orbits. 

The Orbits (fig. 52) are two quadrilateral hollow cones, situated at the upper and 
anterior part of the face, their bases being directed forwards and outwards, and their 
apices backwards and inwards. Each orbit is formed of seven bones, the frontal, sphe- 
noid, ethmoid, superior maxillary, malar, lachrymal and palate; but three of these, the 
frontal, ethmoid and sphenoid, enter into the formation of both orbits, so that the two 
cavities are formed of eleven bones only. Each cavity presents for examination, 
a roof, a floor, an inner and an outer wall, a circumference or base, and an apex. 
The Roof is concave, directed downwards and forwards, and formed in front by 
the orbital plate of the frontal; behind, by the lesser wing of the sphenoid. This 
surface presents internally the depression for the fibro-cartilaginous pulley of the 
superior oblique muscle; externally, the depression for the lachrymal gland, and 
posteriorly, the suture connecting the frontal and lesser wing of the sphenoid. 

The Floor is nearly flat, and of less extent than the roof; it is formed chiefly by 
the orbital process of the superior maxillary; in front, to a small extent, by the 
orbital process of the malar, and behind, by the orbital surface of the palate. 
This surface presents at its anterior and internal part, just external to the lachry- 
mal canal, a depression for the attachment of the tendon of origin of the inferior 
oblique muscle; externally, the suture betw-een the malar and superior maxillary 
bones; near its middle, the infra-orbital groove; and posteriorly, the suture between 
the maxillary and palate bones. 

The Inner Wall is flattened, and formed from before backwards by the nasal 
process of the superior maxillary, the lachrymal, os planum of the ethmoid, and 
a small part of the body of the sphenoid. This surface presents the lachrymal 
groove, and crest of the lachrymal bone, and the sutures connecting the ethmoid, 
in front, with the lachrymal, behind, with the sphenoid. 

The Outer Wall is formed in front by the orbital process of the malar bone; 
behind, by the orbital plate of the sphenoid. On it are seen the orifices of one or 
two malar canals, and the suture connecting the sphenoid and malar bones. 

Angles. The superior external angle is formed by the junction of the upper 
and outer walls; it presents from before backwards, the sutures connecting the 
frontal with the malar in front, and with the orbital plate of the sphenoid behind; 
quite posteriorly is the foramen lacerum anterius, or sphenoidal fissure, which 
transmits the third, fourth, ophthalmic division of the fifth, and sixth nerves, 
and the ophthalmic vein. The superior internal angle is formed by the junction 
of the upper and inner wall, and presents the suture connecting the frontal with 
the lachrymal in front, and with the ethmoid behind. This suture is perforated 
by two foramina, the anterior and posterior ethmoidal, the former transmitting 
the anterior ethmoidal artery and nasal nerve, the latter the posterior ethmoidal 
artery and vein. The inferior external angle, formed by the junction of the 
outer wall and floor, presents the spheno-maxillary fissure, which transmits the 
infra-orbital vessels and nerve, and the ascending branches from the spheno-palatine 



NASAL FOSS^ 



65 



ganglion. The inferior internal angle is formed by the union of the lachrymal 
and OS planum of the ethmoid, with the superior maxillary and palate bones. The 
circumference, or base, of the orbit, quadrilateral in form, is bounded above by the 
supra-orbital arch; below, by the anterior border of the orbital plate of the malar, 
superior maxillary, and lachrymal bones; externally, by the external angular 
process of the frontal and malar bone; internally, by the internal angular process 
of the frontal and nasal process of the superior maxillary. The circumference is 
marked by three sutures, the fronto-maxillary internally, the fronto-malar exter- 
nally, and the malo-maxillary below; it contributes to the formation of the la- 
chrymal groove, and presents above, the supra-orbital notch (or foramen), for the 
passage of the supra-orbital artery, veins, and nerve. The apex, situated at the 
back of the orbit, corresponds to the optic foramen, a short circular canal, which 
transmits the optic nerve and ophthalmic artery. It will thus be seen that there 
are nine openings communicating with each orbit, viz., the optic, foramen lacerum 
anterius, spheno-maxillary fissure, supra-orbital foramen, infra-orbital canal, ante- 
rior and posterior ethmoidal foramina, malar foramina, and lachrymal canal. 

The Nasal Foss^. 

The Nasal Fosscb are two large irregular cavities, situated in the middle line of 
the face, separated from each other by a thin vertical septum, and extending from 
the base of the cranium to the roof of the mouth. They communicate by two large 
apertures, the anterior nares, with the front of the face, and with the pharynx 
behind by the two posterior nares. These fossae are much narrower above than 
below, and in the middle than at the anterior or posterior openings: their depth, 
which is considerable, is much greater in the middle than at either extremity. 
Each nasal fossa communicates with four sinuses, the frontal in front, the sphe- 
noidal behind, and the maxillary and ethmoidal on either side. Each fossa also 
communicates with four cavities: with the orbit by the lachrymal canal, with the 
mouth by the anterior palatine canal, with the cranium by the olfactory foramina, 
and with the spheno-maxillary fossa by the spheno-palatine foramen; and they 
occasionally communicate with each other by an aperture in the septum. The 
bones entering into their formation are fourteen in number: three of the cranium, 
the frontal, sphenoid, and ethmoid, and all the bones of the face excepting the 
malar and lower jaw. Each cavity has four walls, a roof, a floor, an inner, and 
an outer wall. 

The upper wall, or roof (fig. 53), is long, narrow, and concave from before 
backwards; it is formed in front by the nasal bones and nasal spine of the frontal, 
which are directed downwards and forwards; in the middle, by the cribriform 
lamella of the ethmoid, which is horizontal; and behind, by the under surface of 
the body of the sphenoid, and sphenoidal turbinated bones, which are directed 
downwards and backwards. This surface presents, from before backwards, the 
internal aspect of the nasal bones; on their outer side, the suture formed between 
the nasal, with the nasal process of the superior maxillary ; on their inner side, the 
elevated crest which receives the nasal spine of the frontal and the perpendicular 
plate of the ethmoid, and articulates with its fellow of the opposite side; whilst 
the surface of the bones is perforated by a few small vascular apertures, and pre- 
sents the longitudinal groove for the nasal nerve: further back is the transverse 
suture, connecting the frontal with the nasal in front, and the ethmoid behind, 
the olfactory foramina on the under surface of the cribriform plate, and the suture 
between it and the sphenoid behind: quite posteriorly are seen the sphenoidal tur- 
binated bones, the orifice of the sphenoidal sinuses, and the articulation of the ala? 
of the vomer with the under surface of the body of the sphenoid. 

Th.Q floor is flattened from before backwards, concave from side to side, and 
wider in the middle than at either extremity. It is formed in front by the palate 
process of the superior maxillary; behind, by the palate process of the palate 
bone. This surface presents, from before backwards, the anterior nasal epine; 
behind this, the upper orifice of the anterior palatine canal; internally, the ele- 

p 



66 



OSTEOLOGY. 



vated crest which articulates with the vomer; and behind, the suture between 
the palate and superior maxillary bones, and the posterior nasal spine. 

^3._Roof, Floor, and Outer Wall of Nasal Fossae. 
Eoof 

Nnsal iSpine of J' rcmtal Se 
JLmssontaL Plate rfJSfhm^.ul 



JNaso-IaeAiyo/ia-l Ca-nal 




Bnstle fassed thnu^Tl 
li^uTidCiwluni ■ 



Oioter WalZ 

Ncisab Proc. cfSapMaa. 

ncifo77njJ?roe ef ditto 
InfiLTLor Turbvnaicd 
Palate 

'uj/ercor Meatus . 
Middle, Meafu,s 
Inferior Meatur 



Floor 

ATa.NcLspjl Sjpi.Tie 

Palate Procof Sii^Max. 

Folate Froc. of Ta/ate 

Post.ITcbsal iSpine, 

A.nt. P'wlaiti7ie Canal - 



The inner wall, or septum (fig. 54), is a thin vertical septum, which separates 
the nasal foss£e from one another; it is occasionally perforated, so that they com- 
municate, and is frequently deflected considerably to one side. It is formed, in 
front, by the crest of the nasal bones and nasal spine of the frontal; in the middle, 
by the perpendicular lamella of the ethmoid; behind, by the vomer and rostrum 
of the sphenoid; below, by the crest of the superior maxillary and palate bones. 
It presents, in front, a large triangular notch, which receives the triangular carti- 
lage of the nose; above, the lower orifices of the olfactory canals; and behind, the 
guttural edge of the vomer. Its surface is marked by numerous vascular and ner- 
vous canals, and traversed by sutures connecting the bones of which it is formed. 

The outer wall is formed, in front, by the nasal process of the superior maxil- 
lary and lachrymal bones ; in the middle, by the ethmoid and inner surface of the 
superior maxillary and inferior turbinated bones; behind, by the vertical plate of 
the palate bone. This surface presents three irregular longitudinal passages, or 
meatuses, formed between three horizontal plates of bone that spring from it; they 
are termed the superior, middle, and inferior meatuses of the nose. The superior 
meatus, the smallest of the three, is situated at the upper and back part of each 
nasal fossa, occupying the posterior third of the outer wall. It is situated between 
the superior and middle turbinated bones, and has opening into it two foramina, the 
spheno-palatine, at the back part of its outer wall, the posterior ethmoidal cells, at 
the front part of the upper wall. The opening of the sphenoidal sinuses is usually 
at the upper and back part of the nasal fossas, immediately behind the superior 
turbinated bone. The middle meatus, situated between the middle and inferior 
turbinated bones, occupies the posterior two-thirds of the outer wall of each nasal 
fossa. It presents two apertures. In front is the orifice of the infundibulum, by 
which the middle meatus communicates with the anterior ethmoidal cells, and 



NASAL F0SS7K. 



67 



through these with the frontal sinuses. At the centre of the outer wall is the 
orifice of the antrum, which varies somewhat as to its exact position in different 
skulls. The inferior meatus, the largest of the three, is the space between the 
inferior turbinated bone and the floor of the nasal fossa. It extends along the 
entire length of the outer wall of the nose, is broader in front than behind, and 
presents anteriorly the lower orifice of the lachrymal canal. 

54. — Inner "Wall of Nasal Fossfe, or Septum of Nose. 



CresP of Wasal lone. 
ffasat String of Frontal B.- 



Spcice for Triangidar 
Cartilage oj SeptTim 




Ores t of Pculal/e Eione 
Crest of Suf ■ Max-iTL.Bone 



Os Hyoides. 

The Hyoid bone is named from its resemblance to the Greek Upsilon; it is also 
called the lingual hone, from supporting the tongue, and giving attachment to its 
numerous muscles. It is a bony arch, shaped like a horse-shoe, and consisting of 
five segments, a central portion or body, two greater cornua, and two lesser cornua. 



55. — Hyoid Bone. Anterior Surface. 



The Body forms the central part of the 
bone, is of a quadrilateral form, its anterior 
surface (fig. 55) convex, directed forwards 
and upwards, and divided into two parts by 
a vertical ridge, which descends along the 
median line, and is crossed at right angles 
by a horizontal ridge, so that this surface is 
divided into four muscular depressions. At 
the point of meeting of these two lines is a 
prominent elevation, the tubercle. The por- 
tion above the horizontal ridge is directed 
upwards, and is sometimes described as the 
superior border. The anterior surface gives attachment to the Genio-hyoid in the 
greater part of its extent; above, to the Genio-hyo-glossus; below, to the Mylo- 
hyoid, Stylo-hyoid, and aponeurosis of the Digastric; and between these to part of 
the Hyo-glossus. The posterior surface is smooth, concave, directed backwards 
and downwards, and separated from the epiglottis by the thyro-hyoid membrane, 
and by a quantity of loose areolar tissue. The superior border is rounded, and 

F 2 




68 OSTEOLOGY. 

gives attachment to the thyro-hyoid membrane, and part of the Genio-hyo-glossi 
muscles. The inferior border gives attachment in front to the Sterno-hyoid, be- 
hind to part of the Thyro-hyoid, and to the Omo-hyoid at its junction with the 
great cornu. The lateral surfaces are small, oval, convex facets, covered with 
cartilage for articulation with the greater cornua. 

The Greater Cornua project backwards from the lateral surfaces of the body, 
they are flattened from above downwards, diminish in size from before backwards, 
and terminate posteriorly in a tubercle for the attachment of the thyro-hyoid 
lio-ament. Their outer surface gives attachment to the Hyo-glossus; their upper 
border, to the Middle constrictor of the pharynx; their lower border, to part of the 
Thyro-hyoid muscle. 

The Lesser Cornua are two small conical shaped eminences, attached by their 
bases to the angles of junction between the body and greater cornua, and giving 
attachment by their apices to the stylo-hyoid ligaments. In youth the cornua are 
connected to the body by cartilaginous surfaces and held together by ligaments; in 
middle life, the body and greater cornua usually become joined; and in old age 
all the segments are united together, forming a single bone. 

Development. 'Qj Jive centres; one for the body and one for each cornu. Ossi- 
fication commences in the body and greater cornua towards the end of foetal life, 
those for the cornua first appearing. Ossification of the lesser cornua commences 
some months after birth. 

Attachment of Muscles. Sterno-hyoid, Thyro-hyoid, Omo-hyoid, aponeurosis 
of the Digastricus, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus, Hyo- 
glossus, Middle constrictor of the pharynx, and occasionally a few fibres of the 
Lingualis. It also gives attachment to the thyro-hyoidean membrane, and the 
stylo-hyoid, thyro-hyoid, and hyo-epiglottic ligaments. 

THE THORAX. 

The Thorax or chest is an osseo-cartilaginous cage, intended to contain and pro- 
tect the principal organs of respiration and circulation. It is the largest of the 
three cavities connected with the spine, and is formed by the sternum and costal 
cartilages in front, the twelve ribs on each side, and the bodies of the dorsal ver- 
tebrte behind. 

The Sternum. 

The Sternum (figs. 56, 57) is a flat narrow bone, situated in the median line of 
the front of the chest, and consisting in the adult of three portions. Its form 
resembles an ancient sword: the upper piece representing the handle, is termed the 
manubrium, the middle and largest piece which represents the chief part of the 
blade, is termed the gladiolus, and the inferior piece like the point of the sword, 
is termed the ensiform or xiphoid appendix. Li its natural position, its direction 
is oblique, its anterior surface looking upwards and forwards, its posterior down- 
wards and backwards. It is flattened in front, concave behind, broad above, 
becoming narrowed at the point where the first and second pieces are connected, 
after which it again widens a little, and is pointed at its extremity. 

The First Piece of the sternum or Manubrium, is of a somewhat triangular 
form, broad and thick above, narrowed below at its junction with the middle piece. 
Its anterior surface convex from side to side, concave from above downwards, is 
smooth and affords attachment on each side to the Pectoralis major and sternal 
origin of the Sterno-cleido-mastoid muscle. In well marked bones, ridges limiting 
the attachment of these muscles are very distinct. Its posterior surface, concave 
and smooth, affords attachment on each side to the Sterno-hyoid and Sterno-thyroid 
muscles. The superior border, the thickest, presents at its centre the interclavi- 
cular notch, and on each side an oval articular surface, directed upwards backwards 
snd outwards, for articulation with the sternal end of the clavicle. The inferior 
border presents an oval rough surface, covered in the recent state with a thin layer 
of cartilage, for articulation with the second portion of the bone. The lateral 
borders are marked superiorly by an articular depression for the first costal carti- 



STERNUM. 

56.— Sternum and Costal Cartilages. Anterior Surface. 



69 



BTERNO-CttlBO MASTOro 
6UBCLAVIUS \ •^ 




57. — Posterior Surface of Sternum. 



70 



OSTEOLOGY. 



lage, and below by a half facet, which, with a similar facet on the upper angle of 
the middle portion of the bone, forms a notch for the reception of the costal car- 
tilage of the second rib. These articular surfaces are separated by a curved edge 
which slopes from above downwards and inwards. 

The Second Piece of the sternum, or gladiolus, considerably longer, narrower, 
and thinner than the superior, is broader below than above. Its anterior surface 
is nearly flat, directed upwards and forwards, and marked by three transverse lines 
which cross the bone opposite the third, fourth, and fifth articular depressions. 
These lines indicate the point of union of the four separate pieces of which this 
part of the bone consists at an early period of life. At the junction of the third 
and fourth pieces, is occasionally seen an orifice, the sternal foramen; it varies in 
size and form in difierent individuals, and pierces the bone from before backwards. 
This surface afibrds attachment on each side to the sternal origin of the Pectoralis 
major. The posterior surface, slightly concave, is also marked by three transverse 
lines; but they are less distinct than those on the anterior surface; this surface 
affords attachment below, on each side, to the Triangularis sterni muscle, and occa- 
sionally presents the posterior opening of the sternal foramen. The superior border 
is marked by an oval surface for articiilation with the manubrium. The inferior 
border is narrow and articulates with the ensiform appendix. Each lateral border 
presents five articular depressions; the first, at each superior angle, is a half facet 
for the lower half of the cartilage of the second rib, the three succeeding depres- 
sions receive the cartilages of the third, fourth, and fifth ribs, whilst each inferior 
angle presents a half facet for the upper half of the cartilage of the seventh rib. 
These depressions are separated by a series of curved inter-articular notches, 
which diminish in length from above downwards. 

The Third Piece of the sternum, the ensiform or xiphoid appendix, is the small- 
est of the three; it is thin and elongated in form, cartilaginous in structure in youth, 
but more or less ossified at its upper part in the adult. Its anterior surface afibrds 
attachment to the costo-xiphoid ligaments. Its posterior surface, to some of the 
fibres of the Diaphragm and Triangularis sterni muscles. Its lateral borders, to 
the aponeurosis of the abdominal muscles. Above, it is continuous with the lower 
end of the gladiolus; below, by its pointed extremity, it gives attachment to the 
linea alba, and at each superior angle presents a half facet for the lower half of 
the cartilage of the seventh rib. This portion of the sternum is very various in 
appearance, being sometimes pointed, broad and thin, sometimes bifid, or perforated 
by a round hole, occasionally curved, or deflected considerably to one or the other 
side. 

Structure. This bone is composed of a considerable amount of loose spongy 
tissue within, covered externally with a very thin layer of compact tissue. 

Development. The sternum, including the ensiform appendix, is developed 

by six centres. One for the first piece or manubrium, four for the second 

piece or gladiolus, and one for the ensiform appendix. The sternum is entirely 

cartilaginous up to the middle of foetal life, and when ossification takes place, the 

ossific granules are deposited in the middle of the intervals between the articular 

depressions for the costal „t^t ,pr,, -, r^- ^ . 

^^•1 • ^1, J? 11 • 58. — Development of Sternum, bv Six Centres, 

cartilages, m the lollowmg ^ ' -^ 

order (fig. 58). In the 

first piece, between the fifth 

and sixth months; in the 

second and third, between 

the sixth and seventh; 

in the fourth piece, at the 

ninth month; in the fifth, 

within the first year, or 

between the first and 

second years after birth; 

and in the ensiform appen- 





r 


m. 


Of MJjLiiahriiium 


Ti'j}h£- 


( 

t ' 


mXZ 


D 


f'l 


'J 


' , 




If for 2V^Jpl&re 
"~) or 
-' Gladi.alu,s 

3 


, 1 (?-7 mo. 

"biM 




O' 


\ej 


IforHnsifoTm 1 
" Cartoluge 


Z?f-fS^^lj.^- 






STERNUM. 



71 




cax^ept Cncloia.qc 



3S-l^O. 



Z0-2S(h yeur 



soon a4^ter piiiertv 



rlly eartila/. 



pcoruy can 

advanced life 



i/wus in 



60. — Peculiarities. 



nump&T 



^/ 



for l-fvoece Zw tiwi'e reritres 
Z^.?' 'piece, icsuctMif ont 

s.. 

4i? ; ^- placed laterO'llij 



dix, between the (second 59- 

and the seventeenth or 
eighteenth years, by a 
single centre which makes 
its appearance at the upper 
part, and proceeds gra- 
dually downwards. To 
these may be added the 
occasional existence, as de- 
scribed by Breschet, of 
two small epi- sternal cen- 
tres, which make their ap- 
pearance one on each side 
of the interclavicular notch. 
It occasionally happens that 
some of these divisions are 
formed from more than one 
centre, the number and posi- 
tion of which vary (fig. 60). 
Thus the first piece may 
have two, three, or even 
six centres; the second 
piece has seldom more than 
one; the third, fourth, and 
fifth pieces, areoften formed Centres 

from two centres placed 
laterally, the irregular 
union of which will serve 
to explain the occasional 
occurrence of the sternal 
foramen (fig. 61), or of the 
vertical fissure which occa- 
sionally intersects this part 
of the bone. Union of these 
various parts commences 
from below, and proceeds ri/zc/ in 

upwards, taking place in Mode of 
the following order (fig.59). Uvion 

The fifth piece is joined 
to the fourth soon after 
puberty; the fourth to the 
third,between the twentieth 
and twenty-fifth years; the 
third to the second, be- 
tween the thirty-fifth and 
fortieth years; the second 
is rarely joined to the first except in very advanced age. 

Articulations. With the clavicles, and seven costal cartilages on each side. 

Attachment of Muscles. The Pectoralis major, Sterno-cleido-mastoid, Sterno- 
hyoid, Sterno-thyroid, Triangularis sterni, aponeurosis of the Obliquus externus, 
Obliquus internus, and Transversalis muscles. Rectus and Diaphragm. 

The Ribs, 

The Ribs are elastic arches of bone, which form the chief part of the thoracic 
walls. They are twelve in number on each side; bijt this number may be increased 
by the development of a cervical or lumbar rib, or maybe diminished to eleven. The 
first seven are connected behind with the spine, and in front with the sternum. 




61. 




Arres'f. of DetA^loptnent 

cf laterai jjiec^.i producihc/ 

Ster'iial fissiJbre. k 

Sternal foramen 



72 



OSTEOLOGY. 



through the Intervention of the costal cartilages, they are called vertebrosternal, 
or true ribs. The remaining five are false ribs; of these the first three, being 
62, — A Central Rib of Right Side. connected behind with the spine, and in 



Inner Surface. 




front with the costal cartilages, are called 
the vertebro-costal ribs; the last two are 
connected with the vertebrae only, being 
free at their anterior extremities, they are 
termed vertebral or floating ribs. The 
ribs vary in their direction, the upper ones 
being placed nearly at right angles with 
the spine; the lower ones are placed 
obliquely, so that the anterior extremity 
is lower than the posterior. The extent 
of obliquity reaches its maximum at the 
ninth rib, gradually decreasing from that 
point towards the twelfth. The ribs are 
situated one beneath the other in such 
a manner that spaces are left between 
them; these are called intercostal spaces. 
Their length corresponds to the length of 
the ribs, their breadth is more considerable 
in front than behind, and between the 
upper than between the lower ribs. The 
ribs increase in length from the first to 
the eighth, when they again diminish to 
the twelfth. In breadth they decrease 
from above downwards; in each rib the 
greatest breadth is at the sternal extre- 
mity. 

Common characters of the Ribs{^g.62). 
Take a rib from the middle of the series 
in order to study its common characters. 
Each rib presents two extremities, a pos- 
terior or vertebral, an anterior or sternal, 
and an intervening portion, the body or 
shaft. The posterior or vertebral extre- 
mity, presents for examination a head, 
neck, and tuberosity. 

The head (fig. 63) is marked by a kid- 
ney-shaped articular surface, divided by a 
horizontal ridge into two facets for articu- 
lation with the costal cavity formed by the 
junction of the bodies of two contiguous 
dorsal vertebrae; the upper facet is small, 
the inferior one of large size; the ridge 
separating them, serves for the attachment 
of the inter-articular ligament. 

The neck is that flattened portion of the 
rib which extends outwards from the head; 
it is about an inch long, and rests upon 
the transverse process of the inferior of 
the two vertebras with which the head 
articulates. Its anterior surface is flat 
and smooth, its posterior rough, for the 
attachment of the middle costo-transverse 
ligament. Of its two borders, the super- 
rior presents a rough crest for the attach- 




RIBS. 73 

ment of the anterior costo-transverse ligament; its inferior border is rounded. 
On tlie outer surface of tlie neck, just wliere it joins tlie siiaft, is an eminence, tlie 
tuberosity; it consists of two portions, an articular and a non-articular. The 
articular portion, the most internal and inferior of the two, presents a small oval 
surface directed downwards, backwards and inwards, for articulation with the 
extremity of the transverse process of the vertebra below it. The non-articulm 
portion is a rough elevation, which affords attachment to the posterior costo-trans- 
verse ligament. 

63. — Vertebral Extremity of a Eib. External Surface. 

lor At^^T. Cnsto-tTMisLigS 
Facet fur body of lupjiev Horsal Ve/l-tehra/^ 

Rid/ue for T-nteT-artLcidar Ligt^' 

facet for liody of lower Dorsccl Yert^^ 

for tranav.^roc. of lovret 



The shaft presents two surfaces, an external and an internal; and two borders, 
a superior and an inferior. The external surface is convex, and marked for the 
attachment of muscles. At its posterior part, a little in front of the tuberosity, is 
seen a prominent line, directed obliquely from above, downwards and outwards; 
this gives attachment to a tendon of the Sacro-lumbalis muscle, and is called the 
angle. At this point, the rib is bent upon itself in two directions. If the rib is 
laid upon its lower border, it will be seen that the anterior portion of the shaft, as 
far as the angle, rests upon this surface, while the vertebral end of the bone, 
beyond the angle, is bent inwards and at the same time tilted upwards. The 
distance between the angle and the tuberosity increases gradually from the second 
to the tenth rib. This portion of bone is rounded, rough, and irregular, and 
serves for the attachment of the Longissimus dorsi. The portion of bone between 
the angle and sternal extremity is also slightly twisted upon its own axis, the 
external surface looking downwards behind the angle, a little upwards in front of 
it. This surface presents, towards its sternal extremity, an oblique line, the ante- 
rior angle. The internal surface is concave, smooth, and presents the orifices of 
two or three nutrient foramina, the course of which is directly backwards towards 
the vertebral extremity. This surface looks a little upwards, behind the angle; a 
little downwards, in front of it. The superior border, thick and rounded, is marked 
by an external and an internal lip, more distinct behind than in front; they serve 
for the attachment of the External and Internal intercostal muscles. The inferior 
border, thin and sharp, has attached the External intercostal muscle. This border 
is marked on its inner side by a deep groove which commences at the tuberosity 
and gradually becomes lost at the junction of the anterior with the middle third of 
the bone. At the back part of the bone, this groove belongs to the inferior border; 
but just in front of the angle, where it is deepest and broadest, it corresponds to 
the internal surface; it lodges the intercostal vessels and nerve. Its superior edge 
is rounded and continued back as far as the vertebral extremity; it serves for the 
attachment of the Internal intercostal muscle. Its inferior edge corresponds to the 
lower margin of the rib, and gives attachment to the External intercostal. The 
anterior or sternal extremity, is flattened, and presents a porous oval concave 
depression, into which the costal cartilage is received. 

Peculiar Ribs. 

The peculiar ribs which require especial consideration, are five in number, viz., 
the first, second, tenth, eleventh and twelfth. 

The^rs^ rib (fig. 64) is one of the shortest and the most curved of all the ribs; it 
is broad, flat, and placed horizontally at the upper part of the thorax, its surfaces 
looking upwards and downwards; and its borders, inwards and outwards. The 



74 



OSTEOLOGY. 



head is of small size, rounded, and presents only a single articular facet for arti- 
culation with the body of the first dorsal vertebra. The neck is narrow and 
rounded. The tuberosity, thick and prominent, rests on the outer border, 
There is no angle, and it is not twisted on its axis. The upper surface of the 

Peculiar Eibs. 



ShtfJdla'rmar 
^efost 'to tuioe/rosHy 




66. 



Sitiait, tiTtifCula,T ^meeJt — 



67. 

Single or tie. fiiee.- 

68. 
fSi/ngle a/rtie. ftic. — ' 




shaft is marked towards its anterior part by two shallow depressions, separated 
from one another by a ridge, which becomes more prominent towards the internal 
border, where it terminates in a tubercle; this tubercle and ridge serve for the 
attachment of the Scalenus anticus muscle, the groove in front of it transmitting 
the subclavian vein ; that behind it, the subclavian artery. The inferior surface 
is smooth, and destitute of the groove observed on the other ribs. The outer 



COSTAL CARTILAGES. 



75 



border is convex, thick, and rounded. The inner, concave, thin, and sharp, and 
marlvcd about its centre by the tubercle before mentioned. The anterior extremity 
is larger and thicker than any of the other ribs. 

The second rib (fig. 65) is much longer than the first, but bears a very considerable 
resemblance to it in the direction of its curvature. The non-articular portion of the 
tuberosity is occasionally only slightly marked. The angle is slight, and situated 
close to the tuberosity, and the rib is not twisted, so that both ends touch any 
j^lane surface upon which it may be laid. The shaft is not horizontal, like that of 
the first rib; its external surface, which is convex, looking upwards and a little 
outwards ; it presents near the middle a rough eminence for the attachment of part 
of the first, and the second serration of the serratus magnus. The inner surface 
smooth and concave, is directed downwards and a little inwards; it presents a short 
groove towards its posterior part. 

The tenth rib (fig. 66) has only a single articular surface on its head. 

The eleventh and twelfth ribs (figs. 67 and 68) have each a single articular 
surface on the head, which is of rather large size; they have no neck or tuberosity, 
and are pointed at the extremity. The eleventh has a slight angle and a shallow 
groove on the lower border. The twelfth has neither, and is much shorter than 
the eleventh. 

Structure. The ribs consist of a quantity of cancellous tissue, enclosed in a thin 
compact layer. 

Development. Each rib, with the exception of the last two, is developed by 
three centres, one for the shaft, one for the head, and one for the tubercle. The 
last two have only two centres, that for the tubercle being wanting. Ossification 
commences in the body of the ribs at a very early period, before its appearance in 
the vertebrae. The epiphysis of the head, which is of a slightly angular shape, 
and that for the tubercle, of a lenticular form, make their appearance between the 
sixteenth and twentieth years, and do not become united to the rest of the bone 
until about the twenty-fifth year. 

Attachment o^ Muscles. The Intercostals, Scalenus anticus, Scalenus medius. 
Scalenus posticus, Pectoralis minor, Serratus magnus, Obliquus externus, Trans- 
versalis, Quadratus lumborum, Diaphragm, Latissimus dorsi, Serratus posticus 
superioi", Serratus posticus inferior, Sacro-lumbalis, Musculus accessorius ad sacro- 
lumbalem, Longissimus dorsi, Cervicalis ascendens, Levatores costarum. 

The Costal Cartilages. 

The Costal Cartilages (fig. 56) are white elastic structures, which serve to pro- 
long the ribs forward to the front of the chest, and contribute very materially 
to the elasticity of this cavity. The seven first are connected with the sternum, 
the three next with the lower border of the cartilage of the preceding rib. The 
cartilages of the two last ribs, which have pointed extremities, float freely in the 
parietes of the abdomen. Like the ribs, the costal cartilages vary in their length, 
breadth, and direction. They increase in length from the first to the seventh, and 
gradually diminish to the last. They diminish in breadth, as well as the intervals 
between them, from the first to the last. They are broad at their attachment to the 
ribs, and taper towards their sternal extremities, excepting the two first, which 
are of the same breadth throughout, and the sixth, seventh, and eighth, which are 
enlarged where their margins ax'e in contact. Li direction they also vary; the first 
descends a little, the second is horizontal, the third ascends slightly, whilst all the 
rest follow the course of the ribs for a short extent, and then ascend to the sternum 
or preceding cartilage. Each costal cartilage presents two surfaces, two borders, 
and two extremities. The anterior surface is convex, and looks forwards and up- 
wards; that of the first gives attachment to the costo-clavicular ligament; that of 
the first, second, third, fourth, fifth, and sixth at their sternal ends to the Pectoralis 
major. The others are covered, and give partial attachment to some of the 
great flat muscles of the abdomen. The posterior surface is concave, and directed 
backwards and downwards, the six or seven inferior ones affording attachment 



76 OSTEOLOGY. 

to the Transversalls and Diaphragm muscles. Of the two borders, the superior is 
concave, the inferior, convex; they afford attachment to the Intercostal muscles, the 
upper border of the sixth giving attachment to the Pectoralis major muscle. The 
contiguous borders also of the sixth, seventh, and eighth, and sometimes the ninth 
and tenth costal cartilages present smooth oblong surfaces at the points where they 
articulate. Of the two extremities, the outer one is continuous with the osseous 
tissue of the rib to which it belongs. The inner extremity of the first is continuous 
with the sternum; the six next have rounded extremities, which are received into 
shallow concavities on the lateral margins of the sternum. The inner extremities 
of the eighth, ninth and tenth costal cartilages are pointed, and lie in contact with 
the cartilage above. Those of the eleventh and twelfth are free and pointed. 

In the male, the first costal cartilage becomes more or less ossified in the adult, 
and is often connected to the sternum by bone. Ossification of the remaining 
cartilages also occurs to a variable extent after the middle of life, those of the 
true ribs being first ossified. In the female, the process of ossification does not 
take place until old age. The costal cartilages are most elastic in youth, those of 
the false ribs being more so than the true. In old age they become of a deep 
yellow colour. 

Attachment of Muscles. The Subclavius, Sterno-thyroid, Pectoralis major, 
Internal oblique, Transversalls, Rectus, Diaphragm, Triangularis sterni. Internal 
and External intercostals. 

THE PELVIS. 

The Pelvis is composed of four bones. The two Ossa Innominata, which bound 
it in front and at the sides, and the Sacrum and Coccyx, which complete it behind. 

The Os InnominaIum. 

The Os Innominatum, so called from bearing no resemblance to any known 
object, is a large irregular-shaped bone, which, with its fellow of the opposite 
side, forms the sides and anterior wall of the pelvic cavity. In young subjects, 
it consists of three separate parts, which meet and form the large cup-like cavity, 
situated near the middle of the outer side of the bone; and, although in the adult 
these have become united, it is usual to describe the bone as divisible into three 
portions, the ilium, the ischium, and the pubes. 

The ilium is the superior broad and expanded portion which runs upwards 
from the upper and back part of the acetabulum, and forms the prominence of the 
hip. 

The ischium is the inferior and strongest portion of the bone; it proceeds 
downwards from the acetabulum, expands into a large tuberosity, and then curving 
upwards, forms with the descending ramus of the pubes a large aperture, the 
obturator foramen. 

The puhes is that portion which runs horizontally inwards from the inner 
side of the acetabulum for about two inches, then makes a sudden bend, and 
descends to the same extent: it forms the front of the pelvis, and supports the 
external organs of generation. 

The Ilium presents for examination two surfaces, an external and an internal, 
a crest, and two borders, an anterior and a posterior. 

External Surface or Dorsum of the Ilium (fig. 69). The back part of this 
surface is directed backwards, downwards, and outwards; its front part forwards, 
downwards and outwards. It is smooth, convex in front, deeply concave behind; 
bounded above by the crest, below by the upper border of the acetabulum, in 
front and behind by the anterior and posterior borders. This surface is crossed 
in an arched direction by three semicircular lines, the superior, middle, and 
inferior curved lines. The superior curved line, the shortest of the three, 
commences at the crest, about two inches in front of its posterior extre- 
mity; it is at first distinctly marked, but as it passes downwards and out- 
wards to the back part of the great sacro-sciatic notch, where it terminates, 
it becomes less marked, and is often altogether lost. The rough surface 



OS INNOMINATUM. 



77 



included between this line and the crest, affords attachment to part of the 
Gluteus maximus above, a few fibres of the Pyriformis below. The middle curved 
line, the longest of the three, commences at the crest, about an inch behind its 

69. — Eight Os Innominatum. External Surface. 

f 




Spine of Fiil'es 
^Or/, '*v^fe^5r--^ I \ far Powpart3 ligament 



AmgletfPubcs 

^"rectos abdominis 
ptramidalcs 



CESIELLUS IIIfERlOB 



anterior extremity, and, taking a curved direction downwards and backwards? 
terminates at the upper part of the great sacro-sciatic notch. The space between 
the middle, the superior curved lines, and the crest, is concave, and affords attach- 
ment to the Gluteus medius muscle. Near the central part of this line may often 
be observed the orifice of a nutritious foramen. The inferior curved line, 
the least distinct of the three, commences in front at the upper part of the 
anterior inferior spinous process, and taking a curved direction backwards and 
downwards, terminates at the anterior part of the great sacro-sciatic notch. The 
surface of bone included between the middle and inferior curved lines, is concave 
from above downwards, convex from before backwards, and affords attachment to 



78 



OSTEOLOGY. 



the Gluteus minimus muscle. Beneath the inferior curved line, and corresponding 
to the upper part of the acetabulum, is a smooth eminence (sometimes a depression), 
to which is attached the reflected tendon of the Rectus femoris muscle. 

The Internal Surface (fig. 70) of the ilium is bounded above by the crest, 

70. — Eight Os Innominatum. Internal Surface. 







1)^ /'y • 



..' "«;<' 




l^EVATOR AN! 




nPHESSDB OHETHnffi 



below by a prominent line, the linea-ileo pectinea, and before and behind by the 
anterior and posterior borders. It presents anteriorly a large smooth concave 
surface called the internal iliac fossa, or venter of the ilium; it lodges the 
Iliacus muscle, and presents at its lower part, the orifice of a nutritious canal. 
Behind the iliac fossa is a rough surface, divided into two portions, a superior and 
an inferior. The inferior, or auricular portion, so called from its resemblance to the 
external ear, is coated with cartilage in the recent state, and articulates with a 
similar shaped surface on the side of the sacrum. The superior portion is con- 
cave and rough for the attachment of the posterior sacro-iliac ligaments. 

The crest of the ilium is convex in its general outline and sinuously curved, 
being bent inwards anteriorly, outwards posteriorly. It is longer in the female 



OS INNOMINATUM. 



79 



than in the male, very thick behind, and thinner at the centre than at the 
extremities. It terminates at either end in a prominent eminence, the anterior 
superior, and posterior superior spinous process. The surface of the crest is 
broad, and divided into an external lip, an internal lip, and an intermediate 
space. To the external lip is attached the Tensor vaginae femoris, Obliquus 
externus abdominis, and Latissimus dorsi, and by its whole length the fascia 
lata; to the interspace between the lips, the Internal oblique; to the internal 
lip, the Transversalis, Quadratus lumborum, and Erector spinas. 

The anterior border of the ilium is concave. It presents two projections 
separated by a notch. Of these, the uppermost, formed by the junction of the 
crest and anterior border, is called the anterior superior spinous process of 
the ilium, the outer border of which gives attachment to the fascia lata, and the 
origin of the Tensor vaginae femoris, its inner border, to the Iliacus internus, 
whilst its extremity affords attachment to Poupart's ligament and the origin of 
the Sartorius. Beneath this eminence, is a notch which gives attachment to the 
Sartorius muscle, and across which passes the external cutaneous nerve. Below 
the notch is the anterior inferior spinous process, which terminates in the upper 
lip of the acetabulum; it gives attachment to the straight tendon of the Rectus 
femoris muscle. On the inner side of the anterior inferior spinous process, is a 
broad shallow groove, over which passes the Iliacus muscle. The posterior 
border, shorter than the anterior, also presents two projections separated by a 
notch, the posterior superior, and the posterior inferior spinous processes. The 
former corresponds with that portion of the posterior surface of the ilium, which 
serves for the attachment of the sacro-iliac ligaments, the latter, to the auricular 
portion which articulates with the sacrum. Below the posterior inferior spinous 
process, is a deep notch, the great sacro-sciatic. 

The Ischium forms the inferior and posterior part of the os innominatum. It 
is divisible into a thick and solid portion, the body, and a thin ascending part, the 
ramus. The body, somewhat triangular in form, presents three surfaces, an 
external, internal, and posterior, and three borders. The external surface cor- 
responds to that portion of the acetabulum formed by the ischium; it is smooth 
and concave above, and forms a little more than two-fifths of that cavity; its 
outer margin is bounded by a prominent rim or lip, to which the cotyloid-fibro- 
cartilage is attached. Below the acetabulum, between it and the tuberosity, is a 
deep groove, along which the tendon of the Obturator externus muscle runs, as 
it passes outwards to be inserted into the digital fossa of the femur. The internal 
surface is smooth, concave, and forms the lateral boundary of the true pelvic 
cavity; it is broad above, and separated from the venter of the ilium by the linea- 
ileo-pectinea, narrow below, its posterior border being encroached upon a little below 
its centre, by the spine of the ischium, above and below which are the greater and 
lesser sacro-sciatic notches; in front it presents a sharp margin, which forms the 
outer boundary of the obturator foramen. This surface is perforated by two or 
three large vascular foramina, and affords attachment to part of the Obturator 
internus muscle. 

The posterior surface is quadrilateral in form, broad and smooth above, narrow 
below where it becomes continuous with the tuberosity; it is limited in front by 
the margin of the acetabulum, behind by the front part of the great sacro-sciatic 
notch. This surface supports the Pyriformis, the two Gremelli, and the Ob- 
turator internus muscles, in their passage outwards to the great trochanter. 
The body of the ischium presents three borders, posterior, inferior, and 
internal. The posterior border presents, a little below the centre, a thin and 
pointed triangular eminence, the spine of the ischium, more or less elongated in 
different subjects. Its external surface gives attachment to the Oemellus superior, 
its internal surface to the Coccygeus and Levator ani, whilst to the pointed extremity 
is connected the lesser sacro-sciatic ligament. Above the spine is a notch of large 
size, the great sacro-sciatic, converted into a foramen by the lesser sacro-sciatic 
ligament; it transmits the Pyriformis muscle, the gluteal vessels and nerve 



8o OSTEOLOGY. 

passing out above this muscle, the sciatic, nnd internal pndic vessels and nerve, 
and a small nerve to the Obturator internus muscle below it. Below the spine is 
a smaller notch, the lesser sacro-sciatic; it is smooth, coated with cartilage in the 
recent state, the surface of which presents nmnerous markings corresponding to 
the subdivisions of the tendon of the Obturator internus which winds over it. 
It is converted into a foramen by the sacro-sciatic ligaments, and transmits the 
tendon of the Obturator interniis, the nerve which supplies this muscle, and the 
pudic vessels and nerve. The inferior border is thick and broad: at its point of 
junction with the posterior, is a large rough eminence upon which the body rests 
in sittmg; it is called the tuberosity of the ischium. The internal border is thin, 
and forms the outer circumference of the obturator foramen. 

The tuberosity, situated at the junction of the posterior and inferior borders, 
presents for examination an external lip, an internal lip, and an intermediate 
space. The external lip gives attachment to the Quadratus femoris and part of 
the Adductor magnus muscles. The inner lip is bounded by a sharp ridge for the 
attachment of a falciform prolongation of the great sacro-sciatic ligament, pre- 
sents a groove on the inner side of this for the lodgment of the internal pudic 
vessels and nerve, and more anteriorly has attached the Transversus pei'inei. 
Erector penis, and Compressor urethra muscles. The intermediate surface pre- 
sents four distinct impressions. Two of these seen at the front part of 
the tuberosity ai-e rough, elongated, and separated from each other by a pro- 
minent ridge; the outer one gives attachment to the Adductor magnus, the inner 
one to the great sacro-sciatic ligament. Two situated at the back part ai'e 
smooth, lai'ger in size and separated by an oblique ridge : from the upper and 
outer arises the Semi-membranosus; from the lower and inner, the Biceps and 
Semi-tendinosus. The most superior part of the tuberosity gives attachment to 
the Gemellus inferior. 

The ramus is the thin flattened part of the ischium, which ascends from the tube- 
rosity upwai'ds and inwards, and joins the ramus of the pubes, their point of junction 
being indicated in the adult by a rough eminence. Its outer surface is rough for 
the attachment of the Obturator exteruus muscle. Its inner surface forms part of 
the anterior wall of the pelvis. Its inner border is thick, rough, slightly everted, 
forms part of the outlet of the pelvis, and serves for the attachment of the crus- 
peuis. Its outer b-order is thin and sharp, and forms part of the inner margin 
of the obturator foramen. 

The Pubes forms the anterior part of the os innominatum; it is divisible into a 
horizontal ramus or body, and a perpendicular ramus. 

The body, or horizontal ramus, presents for examination two extremities, an 
outer and an inner, aud four surfaces. The outer extremity, the thickest part of 
the bone, forms one-fifth of the cavity of the acetabulum: it presents above, a 
rough eminence, the ilio-pectineal, which serves to indicate the point of junction 
of the ilium and pubes. The inner extremity of the body of the bone is the 
symphysis; it is oval, covered by eight or nine transverse ridges, or a series of 
nipple-like processes arranged in rows, separated by grooves; they serve for the 
attachment of the interarticular fibro-cartilage, placed between it and the oppo- 
site bone. Its upper surface, triangular in form, wider extei'nally than in- 
ternally, is bounded behind by a sharp ridge, the pectineal line, or linea- 
ilio-pectinea, which, running outwards, marks the brim of the true pelvis. The 
surfice of bone in front of the pubic portion of the linea-ilio-pectinea, serves 
for the attachment of the Pectineus muscle. This ridge terminates internally 
at a tubercle, which projects forwards, and is called the spine of the pubes. 
The portion of bone included between the spine and inner extremity of the 
pubes is called the crest; it serves for the attachment of the Rectus, Pyrami- 
dalis, and conjoined tendon of the Internal oblique and Transversalis. The 
point of junction of the crest with the symphysis is called the angle of the pubes. 
The inferior surface presents externally a broad and deep oblique groove, for 
the passage of the obturator vessels and nerve; and internally a sharp margin, 



OS INNOMINATUM. 



8i 



which forms part of the circumference of the obturator forameTi. Its external 
surface is flat and compressed, and serves for t?ie attachment of muscles. Its 
internal surface, convex from above downwards, concave from side to side, is 
smooth, and forms part of the anterior wall of the pelvis. The descending ramus 
of the pubes passes outwards and downwards, becoming thinner and narrower as it 
descends, and joins with the ramus of the ischium. Its external surface is rough, 
for the attachment of muscles. Its inner surface is smooth. Its inner harder is 
thick, rough, and everted, especially in females. In the male it serves for the 
attachment of the crus penis. Its outer border forms part of the circumference of 
the oVjturator foramen. 

The cotyloid cavity or acetabulum, is a deep cup-shaped hemisj)herical depres- 
sion; formed internally by the pubes, above by the ilium, behind and below by 
the ischium, a little less than two-fifths being formed by the ilium, a little more 
than two-fifths by the ischium, and tfie remaining fifth by the pubes. It is 
bounded by a prominent uneven rim, which is thick and strong above, and serves 
for the attachment of a fibro-cartilaginous structure, which contracts its orifice 
and deepens the surface for articulation. It presents on its inner side a deep 
notch, the cotyloid notch, which transTnits the nutrient vessels into the interior of 
the joint, and is continuous with a deep circular depression at the bottom of the 
cavity: this depression is perforated by numerous apertures, lodges a mass of fat, 
and its margins serve fV>r the attachment of the ligamentum teres. The notch is 
converted, in the natural state, into a foramen by a dense ligamentous band 



71. — Plan of the Development of the Os Innominatum. 



£y 8 Ce'n.tTc Jt 



•3 JcrlTnciry 1 2liu,jn/,lscJtium,ic I^il/bcs \ 
5. Se candci -ry 




'r.TvkC'^ 



T/ie 3 T-rimury cenires unitf. lhrou€fTi. "YShalittl Jiicee^ahiyutjiu.ltriif 
Epiphyses azmear cciaut pabcT^y ^ ^ u,nite. aboLLt 2,0 .. year 

which passes across it. Through this foramen the nutrient vessels and nerves 
enter the joint. 

The obturator or thyroid foramen is a large aperture, situated between the 
ischium and pubes. In the male it is large, of an oval form, its longest diameter 
being obliquely from above downwards; in the female smaller, and more triangu- 

6 



82 OSTEOLOGY. 

lar. It is bounded by a thin uneven margin, to which a strong membrane is 
attached; and presents at its upper and outer part a deep groove, which runs 
from the pelvis obliquely forwards, inwards, and downwards. It is converted 
into a foramen by the obturator membrane, and transmits the obturator vessels 
and nerve. 

Structure. This bone consists of much cancellous tissue, especially where it is 
thick, enclosed between two layers of thick and dense compact tissue. In the 
thinner parts of the bone, as at the bottom of the acetabulum, and centre of the 
iliac fossa, it is usually semi-transparent, and composed entirely of compact tissue. 

Development {"^g. 'J l). By eight centres: three primary — one for the ilium, one 
for the ischium, and one for the pubes; andy?i?e secondary — one for the crest of the 
ilium its whole length, one for the anterior inferior spinous process (said to occur 
more frequently in the male than the female), one ibr the tuberosity of the ischium, 
one for the symphysis pubis (more frequent in the female than the male), and one 
for the Y-shaped piece at the bottom of the acetabulum. These various centres 
appear in the following order: First, in the ilium, at the lower part of the bone, 
immediately above the sciatic notch, at about the same period that the develop- 
ment of the vertebrae commences. Secondly, in the body of the ischium, at about 
the third month of foetal life. Thirdly, in the body of the pubes, between the 
fourth and fifth months. At birth, these centres are quite separate; the crest, 
the bottom of the acetabulum, and the rami of the ischium and pubes, being still 
cartilaginous. At about the sixth year, the rami of the pubes and ischium are 
almost completely ossified. About the thirteenth or fourteenth year, the three 
divisions of the bone have extended their growth into the bottom of the acetabu- 
lum, being separated from each other by a Y-shaped portion of cartilage, which 
now presents traces of ossification. The ilium and ischium then become joined, 
and lastly the pubes, through the intervention of the portion above mentioned. 
At about the age of puberty, ossific matter appears in each of the remaining por- 
tions, and they become joined to the rest of the bone about the twenty-fifth year. 

Articulations. With its fellow of the opposite side, the sacrum and femur. 

Attachment of Muscles. Ilium. To the outer lip of the crest, the Tensor 
vaginae femoris, Obliquus externus abdominis, and Latissimus dorsi; to the internal 
lip, the Transversalis, Quadratus lumborum, and Erector spinae; to the interspace 
between the lips, the Obliquus internus. To the outer surface of the ilium, the 
Gluteus maximus, Gluteus medius. Gluteus minimus, reflected tendon of Rectus, 
portion of Pyriformis; to the internal surface, the Iliacus; to the anterior border, 
the Sartorius and straight tendon of the Rectus. To the ischium. Its outer 
surface, the Obturator externus; internal surface, Obturator internus and Levator 
ani. To the spine. The Gemellus superior. Levator ani, and Coccygeus. To 
the tuberosity, the Biceps, Semi-tendinosus, Semi-membranosus, Quadratus femoris. 
Adductor magnus. Gemellus inferior, Transversus perinasi. Erector penis. To the 
pubis, the Obliquus externus, Obliquus internus, Transversalis, Rectus, Pyramida- 
lis. Psoas parvus, Pectineus, Adductor longus, Adductor brevis. Gracilis, Obtu- 
rator externus and internus. Levator ani. Compressor urethras, and occasionally a 
few fibres of the Accelerator urinte. 

The Pelvis. 

The pelvis is stronger and more massively constructed than either of the other 
osseous cavities already considered; it is connected to the lower end of the spine, 
which it supports, and transmits its weight to the lower extremities, upon which 
it rests. It is composed of four bones — the two ossa innominata, which bound it 
on either side and in front; and the sacrum and coccyx, which complete it 
behind. 

The pelvis is divided by a prominent line, the linea ileo pectinea, into a false 
and true pelvis. 

The false pelvis is all that expanded portion of the pelvic cavity which is 
situated above the linea ileo pectinea. It is bounded on each side by the ossa ilii; 



PELVIS. 83 

in front it is incomplete, presenting a wide interval between the anterior sunerior 
spinous processes of the ilia on either side, filled up in the recent state by the 
parietes of the abdomen; behind, in the middle line, is a deep notch. This broad 
shallow cavity is admirably adapted to support the intestines, and to transmit part 
of their weight to the anterior wall of the abdomen. 

The true pelvis is all that part of the pelvic cavity which is situated beneath 
the linea ileo pectinea. It is smaller than the false pelvis, but its walls are more 
perfect. For convenience of description, it may be divided into a superior cir- 
cumference or inlet, an inferior circumfei'ence or outlet, and a cavity. 

The superior circumference forms the margin or brim of the pelvis, the 
included space being called the inlet. It is formed by the linea ileo pectinea, 
completed in front by the spine and crest of the pubes, and behind by the anterior 
margin of the base of the sacrum and sacro- vertebral angle. 

The i7ilet of the j)elvis is somewhat cordate in form, obtusely pointed in front, 
diverging on either side, and encroached upon behind by the projection forwards 
of the promontory of the sacrum. It has three principal diameters: antero-poste- 
rior (sacro-pubic), transverse, and oblique. The antero-posterior extends from 
the sacro-vertebral angle to the symphysis pubis; its average measurement is four 
inches. The transverse extends across the greatest width of the pelvis, from the 
middle of the brim on one side, to the same point on the opposite; its average 
measurement is five inches. The oblique extends from the margin of the pelvis 
corresponding to the ileo pectineal eminence on one side, to the sacro-iliac sym- 
physis on the opposite side; its average measurement is also five inches. 

The cavity of the true pelvis is bounded in front by the symphysis pubis; 
behind, by the concavity of the sacrum and coccyx, which, curving forwards 
above and below, contracts the inlet and outlet of the canal; and laterally it is 
bounded by a broad, smooth, quadrangular plate of bone, corresponding to the 
inner surface of the body of the ischium. This cavity is shallow in front, mea- 
suring at the symphysis an inch and a half in depth, three inches and a half in 
the middle, and four inches and a half posteriorly. From this description, it will 
be seen that the cavity of the pelvis is a short, curved canal, considerably deeper 
on its posterior than on its anterior wall, and broader in the middle than at either 
extremity, from the projection forwards of the sacro-coccygeal column above and 
belov/. This cavity contains, in the recent subject, the rectum, bladder, and part 
of the organs of generation. The rectum is placed at the back of the pelvis, and 
corresponds to the curve of the sacro-coccygeal column, the bladder in front, 
behind the symphysis pubis. In the female, the uterus and vagina occupy the 
interval between these parts. 

The lower circumference of the pelvis is very irregular, and forms what is 
called the outlet. It is bounded by three pz'ominent eminences: one posterior, 
formed by the point of the coccyx; and one on each side, the tuberosities of the 
ischia. These eminences are separated by three notches; one in front, the pubic 
arch, formed by the convergence of the rami of the ischia and pubes on each side. 
The other notches, one on each side, are formed by the sacrum and coccyx 
behind, the ischium in front, and the ilium above: these are called the greater 
and lesser sacro-sciatic notches; in the natural state they are converted into 
foramina by the lesser and greater sacro-sciatic ligaments. 

The diameters of the outlet of the pelvis are two, antero-posterior and trans- 
verse. The antero-posterior extends from the tip of the coccyx to the lower part 
of the symphysis pubis; and the transverse from the posterior part of one ischiatic 
tuberosity, to the same point on the opposite side: the average measurement of 
both is four inches. The antero-posterior diameter varies with the length of the 
coccyx, and is capable of increase or diminution, on account of the mobility of 
this bone. 

Position of the Pelvis. In the erect posture, the- pelvis is placed obliquely with 
regard to the trunk of the body; the pelvic surface of thesymphysis pubis looking 
upwards and backwards, the concavity of the sacrum and coccyx looking down- 

G 2 



84 OSTEOLOGY. 

wards and forwards. The base of the sacrum, in well-formed female bodies, 
being nearly four inches above the upper border of the symphysis pubis, and the 
apex of the coccyx a little more than half an inch above its lower border. This 
obliquity is much greater in the foetus, and at an early period of life, than in the 
adult. 

Axes of the Pelvis. The plane of the inlet of the true pelvis will be represented 
by a line drawn from the base of the sacrum to the upper margin of the symphy- 
sis pubis. A line carried at right angles with this at its middle, would correspond 
at one extremity with the umbilicus, and by the other with the middle of the 
coccyx; the axis of the inlet is therefore directed downwards and backwards. 
The axis of the outlet produced upwards, would touch the base of the sacrum; 
and is therefore directed downwards and forwards. The axis of the cavity is 
curved like the cavity itself: this curve corresponds to the concavity of the 
sacrum and coccyx, the extremities being indicated by the central points of the 
inlet and outlet. 

Differences betioeen the Male and Female Pelvis. In the male, the bones are 
heavier, stronger, and more solid, and the muscular impressions and eminences on 
their surfaces more strongly marked. It is altogether more massive in its general 
form; its cavity is deeper and narrower, and its apertures small. In the female, 
the bones are lighter and more delicate, the muscular impressions on its surface 
only slightly mai'ked, and the pelvis generally is less massive in structure. The 
iliac fossas are large, and the ilia widely expanded; hence the great prominence 
of the hips. The cavity is shallow, but capacious, being very broad both in the 
antero-posterior and transverse diameters ; the inlet and outlet are also large. 
The obturator foramen is triangular ; the tuberosities of the ischia are widely 
separated; the sacrum is wider and less curved"; the symphysis pubis not so deep; 
and the arch of the pubis is greater, and its edges more everted. 

In ili^Q fcBtus, and for several years after birth, the cavity of the pelvis is small; 
the viscera peculiar to this cavity in the adult, being situated in the lower part of 
the abdomen. 

THE UPPER EXTREMITY. 

The Upper Extremity consists of four parts — the shoulder, the arm, the fore- 
arm, and the hand. The shotdder consists of two bones, the clavicle and the 
scapula. 

The Clavicle. 

The Clavicle {clavis, a ' key '), or collar-bone, is a long bone, curved somewhat 
like the italic letter^ and placed horizontally at the upper and lateral part of the 
thorax, immediately above the first rib. It articulates internally with the upper 
border of the sternum, and with the acromion process of the scapula by its outer 
extremity ; serving to sustain the upper extremity in the various positions 
which it assumes, whilst at the same time it allows it great latitude of motion. 
The horizontal plane of the clavicle is nearly straight; but in the vertical plane it 
presents a double curvature, the convexity being in front at the sternal end, and 
behind at the scapular end. Its inner two-thirds are of a triangular prismatic 
form, and extend, in the natural position of the bone, from the sternum to the 
coracoid process of the scapula ; the outer fourth being flattened from above 
downwards, and extending from the coracoid process to the acromion. It pre- 
sents for examination two surfaces, two borders, and two extremities. 

The superior surface (fig, 72), for the inner three-fourths of its extent, is 
narrow, smooth, of equal diameter throughout, and presents near the sternal end 
impressions for the attachment of the Sterno-mastoid muscle behind, the Pectoralis 
major in front. Its outer fourth is broad, flat, uneven, perforated by numerous 
foramina, and covered by the fibres of the Deltoid and Trapezius muscles, which 
encroach upon it considerably in front and behind. 

The inferior surface (fig. 73) is also narrow for the inner three-fourths of its 
extent, broader and more flattened externally. Commencing at the sternal extre- 



CLAVICLE. 



85 



mity, may be seen a small facet for artlcvilatlon with the cartilage of the first rib, 
continuous with the articular surface at the sternal end of the bone. External to 
this a rough impression, the rhomboid, for the attachment of the costo-clavicular 



72. — Left Clavicle. Superior Surface. 



Av'Tomial JEaety 



Ste/malJEai.'bre/mit^j 




73. — Left Clavicle. Inferior Surface. 




(rhomboid) ligament. The middle third of this surface is occupied by a longitu- 
dinal groove, the subclavian groove, broader externally than internally; it gives 
attachment to the Subclavius muscle, and by its anterior margin to the strong 
aponeurosis which encloses it; internally is a. rough surface, the limit of the attach- 
ment of the Pectoralis major below. At the junction of the prismatic with the 
flattened portion of the bone, at its posterior border, may be seen a rough eminence, 
the tubercle of the clavicle. This, in the natural position of the bone, surmounts 
the coracoid process of the scapula, and affords attachment to the conoid ligament. 
From this tubercle an oblique line passes forwards and outwards on the under 
surface of the acromial extremity. It is called the oblique line of the clavicle, and 
affords attachment to the trapezoid ligament. 

The anterior border is broad and convex for its sternal half, and presents a 
rough impression for the attachment of the Pectoralis major muscle. Its outer half 
is a narrow, concave margin, serving for the attachment of the Deltoid: a small 
interval is usually left between the attachments of these muscles, where this 
border is smooth, receiving no muscular fibres. This is the narrowest part of the 
clavicle, and hence the most common seat of fracture. 

The posterior border is broad and deeply concave for the inner two-thirds of 
its extent, affording attachment internally by a small extent of surface, to the 
Sterno-hyoid; convex, narrow, and irregular in its outer third, for the attachment 
of the Trapezius. This border corresponds to the subclavian vessels and brachial 
plexus of nerves, and presents, towards its centre, the foramen for the nutritious 
artery of the bone. 

The internal or sternal end of the clavicle is directed inwards, and a little 
downwards and forwards ; it presents a large triangular facet, concave from before 
backwards, convex from above downwards, which articulates with the sternum 
through the intervention of an inter-articular fibro-cartilage; the circumference 
of the articular surface is rough, for the attachment of numerous ligaments. 



86 OSTEOLOGY. 

The outer extremity, directed forwards and outwards, presents a small oval 
facet, for articulation with the acromion process of the scapula. 

Peculiarities of this Bone in the Sexes and in Individuals. In the female, the 
clavicle is less curved, smoother, longer, and more slender than in the male. In 
those persons who perform considerable manual labour, which brings into constant 
action the muscles connected with this bone, it acquires considerable bulk, becomes 
shorter, more curved, its ridges for muscular attachment become prominently 
marked, and its sternal end of a prismatic or quadrangular form. 

Structure. The shaft as well as the extremities consists of cancellous tissue, 
invested in a compact layer much thicker in the centre than at either end. The 
clavicle is highly elastic, by reason of its curves. From the experiments of Mr. 
Ward, it has been shewn that it possesses sufficient longitudinal elastic force to 
raise its own weight nearly two feet on a level surface; and sufficient transverse 
elastic force, opposite the centre of its anterior convexity, to raise its own weight 
about a foot. This extent of elastic power must serve to moderate very consider- 
ably the effect of concussions received upon the point of the shoulder. 

Development. By two centres: one for the shaft, and one for the sternal end 
of the bone. The centre for the shaft appears very early, before any other bone; 
the second centre makes its appearance about the eighteenth or twentieth year, 
and unites with the rest of the bone a few years after. 

Articulations. With the sternum, scapula, and cartilage of the first rib. 

Attachment of Muscles. The Sterno cleido-mastoid. Trapezius, Pectoralis major, 
Deltoid, Subclavius, and Sterno-hyoid. 

The Scapula. 

The Scapula is a large flat bone, triangular in shape, which forms the back part 
of the shoulder. It is situated at the posterior aspect and side of the thorax, 
between the first and seventh ribs, and presents for examination two surfaces, three 
borders, and three angles. 

The anterior surface, or venter (fig. 74), presents a broad concavity, the sub- 
scapular fossa. It is marked, in the posterior two thirds, by several oblique ridges, 
which pass from behind obliquely forwards and upwards, the anterior third being 
smooth. The oblique ridges above-mentioned, give attachment to the tendinous 
intersections, and the surfaces between them, to the fleshy fibres of the Subscapu- 
laris muscle. The anterior third of the fossa, which is smooth, is covered by, 
but does not afford attachment to, the fibres of this muscle. This surface is sepa- 
rated from the posterior border, by a smooth triangular margin at the superior and 
inferior angles, and in the interval between these, by a narrow margin which is 
often deficient. This marginal surface affords attachment throughout its entire 
extent to the Serratus magnus muscle. The subscapular fossa presents a trans- 
verse depression at its upper part, called the subscapular angle; it is in this situ- 
ation that the fossa is deepest, and consequently the thickest part of the Subscapularis 
muscle lies in a line parallel with the glenoid cavity, and must consequently operate 
most effectively on the humerus which is contained in it. 

The posterior surface, or dorsum (fig, 75) is convex from above downwards, 
alternately convex and concave from side to side. It is subdivided unequally into 
two parts by the spine; that portion above the spine is called the supra spinous 
fossa, and that below it, the infra spinous fossa. 

The supra spinous fossa, the smaller of the two, is concave, smooth, and broader 
towards the vertebral than at the humeral extremity. It affords attachment by its 
inner two-thirds to the fibres of the Supra spinatus muscle. 

The infra spinous fossa is much larger than the preceding; towards its inner 
side a shallow concavity is seen at its upper part; its centre presents a prominent 
convexity, whilst towards the axillary border is a deep groove, which runs from 
the upper towards the lower part. The inner three-fourths of this surface affords 
attachment to the Infi-a-spinatus muscle; the outer fourth is only covered by it, 
without giving origin to its fibres. This surface is separated from the axillary 



SCAPULA. 



«7 



border by an elevated ridge, which runs from the lower part of the glenoid cavity, 
downwards and backwards to the posterior border, about an inch above the infe- 
rior angle. This ridge serves for the attachment of a strong aponeurosis, which 
separates the Infra-spinatus from the two Teres muscles. The surface of bone 
between this line and the axillary border is narrow for the upper two-thirds of its 
extent, and traversed near its centre by a groove for the passage of the dorsalis 
6capula3 artery; it affords attachment to the Teres minor. Its lower third presents 
a broader, somewhat triangular surface, which gives origin to the Teres major, and 
74. — Left Scapiila. Anterior Surface, or Venter. 




over which glides the Latissimus dorsi muscle; sometimes this muscle takes origin 
by a few fibres from this part. The broad and narrow portions of bone above 
alluded to are separated by an oblique line, which runs from the axillary border, 
downwards and backwards; to it is attached the aponeurosis separating the two 
Teres muscles from each other. 

Ihe Spine ia a prominent plate of bone, which crosses obliquely the inner 
three-fourths of the dorsum of the scapula at its upper part, and separates 



OSTEOLOGY. 



the supra from the infra spinous fossa: it commences at the vertebral border by 
a smooth triangular surface, oyerwhicli the trapezius glides, separated by a bursa; 
and, gi-adually becoming more elevated as it passes forwards, terminates in the 
acromion process which overhangs the shoulder joint. The spine is triangular and 
flattened from above downwards, its apex corresponding to the posterior border, its 
base, which is directed outwards, to the neck of the scapula. It presents two 

75. — Left Scapula. Posterior Surface, or Dorsum. 



00^J>J 



^^oo^'^ 



fiVlOf, 




W>^ 



surfaces and three borders. Its superior surface is concave, assists in forming the 
supra-spinous fossa, and alFords attachment to part of the Supra-spinatus muscle. 
Its inferior surface forms part of the infra-spinous fossa, gives origin to part of the 
Infra-spinatus muscle, and presents near its centre the orifice of a nutritious canal. 
Of the three borders, the anterior is attached to the dorsum of the bone; the 
posterior, or crest of the spine, is broad, and presents two lips^ and an intervening 



SCAPULA. 89 

roui^h interval. To the superior lip is attached the Trapezius, to the extent shown 
in the figure. A very rough prominence is generally seen occupying that portion 
of the spine which receives the insertion of the middle and inferior fibres of this 
muscle. To the inferior lip, its whole length, is attached the Deltoid. The interval 
between them is also partly covered by the fibres of these muscles. The external 
border, the shortest of the three, is slightly concave, its edges thick and round, 
continuous above with the under surface of the acromion, process, below with the 
neck of the scapula. The narrow portion of bone external to this border, serves 
to connect the supra and infra spinous fosste. 

The Acromion process, so called from forming the summit of the shoulder joint 
{aKpov, a summit; w/xo?, the shoulder), is a large, and somewhat triangular process, 
flattened from behind forwards, directed at first a little outwards, and then curving 
forwards and upwards, so as to overhang the glenoid cavity. Its upper surface 
directed upwards, backwards, and outwards, is convex, rough, and partly covered 
by some of the fibres of origin of the Deltoid. Its under surface is smooth and con- 
cave. Its outer border, which is thick and irregular, affords attachment to the 
Deltoid muscle. Its inner margin, shorter than the outer, is concave, gives attach- 
ment to a portion of the Trapezius muscle, and presents about its centre a small 
oval surface, for articulation with the scapular end of the clavicle. Its apex, 
formed at the point of meeting of these two borders in front, is thin, and has 
attached to it the coraco-acromion ligament. 

Of the three borders or costge of the scapula, the superior is the shortest and 
thinnest; it is concave, terminating at its inner extremity at the superior angle, 
at its outer extremity at the coracoid process. At its outer part is a deep 
semicircular notch, formed partly by the base of the coracoid process. This notch 
is converted into a foramen by the transverse ligament, and serves for the passage 
of the supra scapular nerve. The adjacent margin of the superior border affords 
attachment to the Omo-hyoid muscle. The external, or axillary border, is the 
thickest of the three. It commences above at the lower margin of the glenoid cavity, 
and inclines obliquely downwards and backwards to the inferior angle. Imme- 
diately below the glenoid cavity, is a rough depression about an inch in length, 
which affords attachment to the long head of the Triceps muscle; to this succeeds 
a longitudinal groove which extends as far as its lower third, and affords origin to 
part of the Subscapularis muscle. The inferior third of this border which is thin 
and sharp, serves for the attachment of a few fibres of the Teres major behind, and 
of the Subscapularis in front. The internal, or vertebral border, also named the 
base, is the longest of the three, and extends from the superior to the inferior 
angle of the bone. It is convex, intermediate in thickness between the superior 
and the external, and that portion of it above the spine bent considerably outwards, 
so as to form an obtuse angle with the lower part. This border presents an ante- 
rior lip, a posterior lip, and an intermediate space. The anterior lip affords 
attachment to the Serratusmagnus; ihe posterior lip, to the Supra-spinatus above 
the spine, the Infra- spinatus below; the interval between the two lips, to the Leva- 
tor anguli scapulee above the triangular surface at the commencement of the spine, 
the Rhomboideus minor, to the edge of that surface; the Rhomboideus major being 
attached by means of a fibrous arch, connected above to the lower part of the 
triangular surface at the base of the spine, and below to the lower part of the pos- 
terior border. 

Of the three angles, the superior, formed by the junction of the superior and 
internal borders, is thin, smooth, rounded, somewhat inclined outwards, and gives 
attachment to a few fibres of the Levator anguli scapulae muscle. The inferior 
angle thick and rough, is formed by the union of the vertebral and axillary 
borders, its outer surface affording attachment to the Teres major, and occasionally 
a few fibres of the Latissimus dorsi. The anterior angle is the thickest part of 
the bone, and forms what is called the head of th.e scapula. The head presents 
a shallow, pyriform, articular surface, the glenoid cavity {'yXrjvrj, a superficial 
cavity; etSo?, like); its longest diameter is from above downwards, and its 



90 



OSTEOLOGY. 



direction outwards and forwards. It is broader below than above; at its apex 
is attached the long tendon of the Biceps muscle. It is covered with cartilage in the 
recent state; and its margins, slightly raised, give attachment to a fibro-cartilaginous 
structure, the glenoid ligament, by which its cavity is deepened. The neck of 
the scapula is the slightly depressed surface which surrounds the head, it is more 
distinct on the posterior than on the anterior surface, and below than above. In 
the latter situation, it has, arising from it, a thick prominence, the coracoid 
process. 

The Coracoid process, so called from its fancied resemblance to a crow's beak 
{Kopa^, a crow; eiSo?, like), is a thick curved process of bone, which arises by a 
broad base from the upper part of the neck of the scapula; it ascends at first 
upwards and inwards, then becoming smaller, it changes its direction and passes 
forwards and outwards. The ascending portion, flattened from before backwards, 
presents in front a smooth concave surface, over which passes the sub-scapularis 
muscle. The horizontal portion is flattened from above downwards; its upper 
surface is convex and irregular; its under surface is smooth; its anterior border 
is rough, and., gives attachment to the Pectoralis minor, its posterior also rough 
to the coraco-acromion ligament, while the apex is embraced by the conjoined 
tendon of origin of the short head of the Biceps and Coraco-brachialis muscles. 
At the inner side of the root of the coracoid process is a rough depression for the 
attachment of the conoid ligament, and running from it obliquely forwards and 
outwards on the upper surface of the horizontal portion, an elevated ridge for 
the attachment of the trapezoid ligament. 

Structure. In the head, processes, and all the thickened parts of the bone, it 
is cellular in structure, of a dense compact tissue in the rest of its extent. The 

76. — Plan of the Development of the Scapula. By Seven Centres. 



^S°^C, 




Vi^no-^ 



Epiphyses (except one for the Coracoid process) appear at fifteen to 
seventeen years, and unite at twenty-two to twenty-five years. 



iiump:rus. 



91 



centre and upper part of the dorsum, but especially the former, is usually so thin 
as to be semi-transparent; occasionally the bone is found wanting in this situ- 
ation, and the adjacent muscles come into contact. 

Development {^g. 76). By seven centres; one for the body, two for the coracoid 
process, two for the acromion, one for the posterior border, and one for the inferior 
angle. 

That for the body makes its first appearance at about the same period that 
osseous matter is deposited in the vertebras, and forms the chief part of the bone. 
At birth, all the other centres are cartilaginous. About the first year after birth, 
osseous deposition occurs in the middle of the coracoid process; which usually 
becomes joined with the rest of the bone at the time when the other centres make 
their appearance. Between the fifteenth and seventeenth years, osseous matter is 
deposited in the remaining centres in quick succession, and in the following order: 
first, near the base of the acromion, and in the upper part of the coracoid process, 
the latter appearing in the form of a broad scale; secondly, in the inferior angle 
and contiguous part of the posterior border; thirdly, near the extremity of the 
acromion; fourthly, in the posterior border. The acromion process, besides being 
formed of two separate nuclei, has its base formed by an extension into it of the 
centre of ossification which belongs to the spine, the extent of which varies in 
different cases. The two separate nuclei unite, and then join with the extension 
carried in from the spine. These various epiphyses become united to the bone 
between the ages of twenty-two and twenty-five years. 

Articulations. With the humerus and clavicle. 

Attachment of Muscles. To the anterior surface, the Subscapularis; posterior 
surface, Supra-spinatus, Infra-spinatus; spine. Trapezius, Deltoid; superior 
border, Omo-hyoid; vertebral border, Serratus magnus, Levator anguli scapulas, 
Rhomboideus minor and Major; axillary border. Triceps, Teres minor. Teres 
major,' glenoid cavity; long head of the Biceps, coracoid process; short head of 
Biceps, Coraco-brachialis, Pectoralis minor; and to the inferior angle occasionally 
a few fibres of the Latissimus dorsi. 

The Humerus. 

The Humerus is the longest and largest bone of the upper extremity; it pre- 
sents for examination a shaft and two extremities. 

The Superior Extremity is the largest part of the bone; it presents a rounded 
head, a constriction around the base of the head, the neck, and two other emi- 
nences, the greater and lesser tuberosities (fig. 77). 

The head, nearly hemispherical in form, is directed inwards, upwards, and a 
little backwards; its surface is smooth, coated with cartilage in the recent state, 
and articulates with the glenoid cavity of the scapula. The circumference of its 
articular surface is slightly constricted, and is termed the anatomical neck, in 
contradistinction to the constriction which exists below the tuberosities, and 
is called the surgical neck, from its being the seat of the accident called by 
surgeons, 'fracture of the neck of the humerus.' 

The neck, which is obliquely directed, forming an obtuse angle with the shaft, 
is more distinctly marked in the lower half of its circumference, than in the 
upper half, where it presents a narrow groove, separating the head from the 
tuberosities. Its circumference afibrds attachment to the capsular ligament, and 
is perforated by numerous vascular foramina. 

The greater tuberosity is situated on the outer side of the head and lesser 
tuberosity. Its superior surface is rounded and marked by three flat facets, 
separated by two slight ridges, the most anterior giving attachment to the 
tendon of the Supra-spinatus; the middle, to the Infra-spinatus; the posterior, to 
the Teres minor. The external surface of the great tuberosity is convex, rough, 
and continuous with the outer side of the shaft. 

The lesser tuberosity is more prominent, although smaller than the greater; 
it is situated in front of the head, and is directed inwards and forwards. Its 



92 



OSTEOLOGY. 

77. — Left Humerus. Anterior View. 



ComTtion Origin 




SUPINATOR RADII LONCUS 



FLEXOR CARPI RA0IALI8 
PALMARIS LONCUS < 

rLE.XOR DJCITORUM SUBLIMIS 
,, CARPI ULNARIS 



EXTENSOR CARPI RADIALI.S 
LONCIOR 



t ^ 

V EXTENSOR. CARP.RAD. GREV 
„ DIOITQRUM COMMUfviiS 
., MIIMIMI DICITI 
„ CARPI UIWARIS 
SUPIWATOR BREVIS 



HUMERUS. 



93 



summit presents a pi'ominent facet for the insertion of the tendon of the Subsca- 
pularis muscle. These two tuberosities are separated from one another by a 
deep groove, the bicipital groove, so called from its lodging the long tendon of the 
Biceps muscle. It commences above between the two tuberosities, passes obliquely- 
down wards and a little inwards, and terminates at the junction of the upper with 
the middle third of the bone. It is deep and narrow at its commencement, and 
becomes shallow and a little broader as it descends. In the recent state it is 
covered with a thin layer of cartilage, lined by a prolongation of the synovial 
membrane of the shoulder joint, and receives part of the tendon of insertion of 
the Latissimus dorsi about its centre. 

The Shaft of the humerus is almost cylindrical in the upper half of its extent; 
prismatic and flattened below, it presents three borders and three surfaces for 
examination. 

The external border runs from the back part of the greater tuberosity to 
the external condyle, and separates the external from the posterior surface. It is 
rounded and indistinctly marked in its upper half, and serves for the attachment 
of the external head of the triceps muscle; its centre is traversed by a broad but 
shallow oblique depression, the musculo-spiral groove ; its lower part is marked 
by a prominent rough margin, a little curved from behind forwards, which presents 
an anterior lip for the attachment of the Supinator longus above, the Extensor carpi 
radialis longior below, a posterior lip for the Triceps, and an interstice for the 
attachment of the external intermuscular aponeurosis. 

The internal border extends from the lesser tuberosity above to the internal 
condyle below. Its upper third is marked by a prominent ridge, forming the 
inner lip of the bicipital groove, and giving attachment from above downwards 
to the tendons of the Latissimus dorsi, Teres major, and part of the origin of the 
inner head of the Triceps. About its centre is a rough ridge for the attachment 
of the Coraco-brachialis, and just below this is seen the entrance of the nutritious 
canal directed downwards. Its inferior third is raised into a slight ridge, which 
becomes very prominent below; it presents an anterior lip for the attachment of 
the Brachialis anticus, a posterior lip for the internal head of the Triceps, and an 
intermediate space for the internal intermuscular aponeurosis. 

The anterior border runs from the front of the great tuberosity above, to the 
coronoid depression below, separating the internal from the external surface. Its 
upper part is very prominent and rough, forms the outer lip of the bicipital groove, 
and serves for the attachment of the tendon of the Pectoralis major. About its 
centre is seen the rough deltoid impression; below, it is smooth and rounded, 
affording attachment to the Brachialis anticus. 

The external surface is directed outwards above, where it is smooth, rounded, 
and covered by the Deltoid muscle; forwards below, where it is slightly concave 
from above downwards, and gives origin to part of the Brachialis anticus muscle. 
About the middle of this surface, is seen a rough triangular impression for the 
insertion of the Deltoid muscle, and below it the musculo-spiral groove, directed 
obliquely from behind, forwards and downwards; it transmits the musculo-spiral 
nerve and superior profunda artery. 

The internal surface, less extensive than the external, is directed forwards 
above, inwards and forwards below: at its upper part it is narrow, and forms the 
bicipital groove. The middle part of this surface is slightly rough for the 
attachment of the Coraco-brachialis; its lower part is smooth, concave, and 
gives attachment to the Brachialis anticus muscle. 

The posterior surface (fig. 78) appears somewhat twisted, so that its superior 
part is directed a little inwards, its inferior part backwards and a little outwards. 
Nearly the whole of this surface is covered by the external and internal heads of 
the triceps, the former being attached to its upper and outer part, the latter to its 
inner and back part, their origin being separated by the musculo-spiral groove. 

The Loxoer Extremity is flattened from before backwards, and curved slightly 
forwards; it terminates below in a broad articular surface, which is divided into 



94 



OSTEOLOGY. 



78. — Left Humerus. Posterior surface. 



.INFRA ^ 



)1 



¥A 



f 






n 



^^ 



\Trochl\ 



two parts by a shallow groove; on either 
side of the articulate surface are the ex- 
ternal and internal condyles. The articular 
surface extends a little lower than the con- 
dyles, and is curved slightly forwards, so 
as to occupy the more anterior part of the 
bone; its greatest breadth is in the trans- 
verse diameter, and it is obliquely directed, 
so that its inner extremity occupies a lower 
level than the outer. The outer portion 
of this articular surface presents a smooth 
rounded eminence, which has received the 
name of the lesser or radial head of the 
humerus; it articulates with the cup-shaped 
depression on the head of the radius, is 
limited to the front and lower part of the 
bone, and does not extend as far back as 
the other portion of the articular surface. 
On the inner side of this eminence is a 
shallow groove, in which is received the 
inner margin of the cup-like cavity of the 
head of the radius. The inner or trochlear 
portion of the articular surface pi*esents 
a deep depression between two well- 
markeL borders. This surface is curved 
from before backwards, concave from side 
to side, and occupies the anterior lower and 
posterior part of the bone. The external 
border, less prominent than the internal, 
corresponds to the interval between the 
radius and ulnar. The internal border is 
thicker, more prominent, and, consequently, 
of greater length than the external. The 
grooved portion of the articular surface fits 
accurately within the greater sigmoid cavity 
of the ulna; it is broader and deeper on the 
posterior than on the anterior aspect of 
the bone, and is directed obliquely from 
behind forwards, and from without inwards. 
Lnmediately above the back part of the 
trochlear surface, is a deep triangular de- 
pi'ession, the olecranon depression, in which 
is received the summit of the olecranon 
process in extension of the fore-arm. Above 
the front part of the trochlear surface, is 
seen. a smaller depression, the coronoid de- 
pression; it receives the coronoid process 
of the ulna during flexion of the fore-arm. 
These fossss are separated from one another 
by a thin lamina of bone, which is some- 
times perforated; their margins afford at- 
tachment to the anterior and posterior 
ligaments of the elbow joint, and they are 
lined in the recent state by the synovial 
membrane of this articulation. Above the 
front part of the radial tuberosity, is seen 
a slight depression which receives the 



HUMERUS. 



95 



anterior border of the head of the radius when the fore-arm is strongly flexed. 
The external condyle is a small tubercular eminence, less prominent than the 
internal, curved a little forwards, and giving attachment to the external lateral 
ligament of the elbow joint, and to a tendon common to the origin of some of the 
extensor and supinator muscles. The internal condyle, larger and more promi- 
nent than the external, is directed a little backwards, it gives attachment to the 
internal lateral ligament, and to a tendon common to the origin of some of the flexor 
muscles of the fore-arm. These eminences are directly continuous above with the 
external and internal borders. 

Structure. The extremities consist of cancellous tissue, covered with a thin 
compact layer; the shaft is composed of a cylinder of compact tissue, thicker at 
the centre than at the extremities, and hollowed out by a large medullary canal. 

Development. By seven centres 



79.- 



Plan of the Development of the Humerus. 
By 7 centres. 



EpijjJiyses efHead & | A.*^ 
Tiiierosities ileniZ a^ I ty 
S.yV and umte | 
wBh Skafl at 20 *}■;/ Tj 



seven 
(fig. 79); one for the shaft, one for 
the head, one for the greater tu- 
berosity, one for the radial, and one 
for the trochlear portion of the 
articular surface, and one for each 
condyle. The centre for the shaft ap- 
pears very early, soon after ossifica- 
tion has commenced in the cavicle, 
and soon extends towards the extremi- 
ties. At birth, it is ossified nearly in 
its whole length, the extremities re- 
maining cartilaginous. Between the 
first and second years, ossification com- 
mences in the head of the bone, and 
between the second and third years 
the centre for the tuberosities marks 
its appearance usually by a single 
ossific point, but sometimes, according 
to Beclard, by one for each tuberosity, 
that for the lesser being Small, and not 
appearing until after the fourth year. 
By the fifth year, the centres for the 
head and tuberosities have enlarged 
and become joined, so as to form a 
single large epiphysis. 

The lower end of the humerus is 
developed in the following manner: 
At the end of the second year, ossifi- 
cation commences in the radial portion 
of the articular surface, and from this point extends inwards, so as to form the 
chief part of the articular end of the bone, the centre for the inner part of 
the articular surface not appearing until about the age of twelve. Ossification 
commences in the internal condyle about the fifth year, and in the external one 
not until between the age of thirteen or fourteen. About sixteen or seventeen 
years, the outer condyle and both portions of the articulating surface (having 
already joined) unite with the shaft; at eighteen years, the inner condyle becomes 
joined, whilst the upper epiphysis, although the first formed, is not joined until 
about the twentieth year. 

Articulations. With the glenoid cavity of the scapula,and with the ulna and radius. 
Attachment of Muscles. To the greater tuberosity, the Supra-spinatus, Infra- 
spinatus, and Tei-es minor; to the lesser tuberosity, the Subscapularis; to the ante- 
rior bicipital ridge, the Pectoralis major; to the posterior bicipital ridge and groove, 
the Latissimus dorsi and Teres major; to the shaft, the Deltoid, Coraco-brachialis, 
Brachialia anticus. External and Internal heads of the Triceps; to the internal 



Jhiites wr. 
Shajta 







96 



OSTEOLOGY. 

80. — Bones of the Left Fore-Arm. Anterior Surface. 

RADIUS 



FLEXOR DICITORUM 
SUBLIMIS 



PRDN ATOR 
RADII, TERES 



of FLEXOR LONCUS POLLICIS 




"f 

FLEXOR DICITORUM 

SUBLIM IS 



Styloid JBrocess 



SUPINATOR LOMCUS 
Groove Jar ext. qssis 

METACARPI POLLieiS 
GroovafanEtS. PRIMI 
INTERNODII POLLICIS 






ULNA. 



97 



condyle, the Pronator radii teres, and common tendon of the Flexor carpi radialis, 
Palmaris longus, Flexor digitorum sublimis, and Flexor carpi ulnaris ; to the 
external condyloid ridge, the Supinator longus, and Extensor carpi radialis 
longior; to the external condyle, the common tendon of the Extensor carpi 
radialis brevior. Extensor communis digitorum. Extensor minimi digiti, and Ex- 
tensor carpi ulnaris, the Anconeus, and Supinator brevis. 

The Fore-arm is that portion of the upper extremity, situated between the 
elbow and wrist. It is composed of two bones, the Ulna and Eadius. 

The Ulna, 

The Ulna (fig. 80, 8 1) is a long bone, prismatic in form, placed at the inner side 
of the fore-arm, parallel with the radius, being the largest and longest of the two. 
Its upper extremity, of great thickness and strength, forms a large part of the 
articulation of the elbow joint; it gradually tapers as it descends, its inferior 
extremity being very small, and excluded from the wrist joint by the interposi- 
tion of an interarticular fibro-cartilage. It is divisible into a shaft and two 
extremities. 

The Upper Extremity, the strongest part of the bone, presents for examination 
two large curved processes, the Olecranon process and the Coronoid process, and 
two concave articular cavities, the greater and lesser Sigmoid cavities. 

The Olecranon Process is a large thick curved eminence, situated at the upper 
and back part of the ulna. It rises somewhat higher than the coronoid, is 
contracted where it joins the shaft, and curved forwards at the summit so as to 
present a prominent tip. Its posterior surface, directed backwards, is of a 
triangular form, smooth, subcutaneous, and covered by a bursa. Its superior 
surface, directed upwards, is of a quadrilateral form, marked behind by a rough 
surface for the attachment of the Triceps muscle, and in front, near the margin, 
by a slight transverse groove for the attachment of part of the posterior ligament 
of the elbow joint. Its anterior surface is smooth, concave, covered with car- 
tilage in the recent state, and forms the upper and back part of the great sigmoid 
cavity. The lateral borders present a continuation of the same groove that was 
seen on the margin of the superior surface, they serve for the attachment of 
ligaments, viz., the back part of the internal lateral ligament internally; the 
posterior ligament externally. The Olecranon process, in its structure as well 
as in its position and use, resembles the Patella in the lower limb, and, like it, 
sometimes exists as a separate piece, not united to the rest of the bone. 

The Coronoid Process {Kopcovrj, a crow's beak; etSo?) is a rough triangular 
eminence of bone which projects horizontally forwards from the upper and front 
part of the ulna, forming the lower part of the great sigmoid cavity. Its base 
is continuous with the shaft. Its apex, pointed, slightly curved upwards, is 
received into the coronoid depression of the humerus in flexion of the fore-arm. 
Its superior surface is smooth, concave, and forms the lower part of the great 
sigmoid cavity. The inferior surface is concave, directed downwards and for- 
wards and marked internally by a rough impression for the insertion of the Bra- 
chialis anticus. At the junction of this surface with the body, is a rough eminence, 
the tubercle of the ulna, for the attachment of the oblique ligament. Its outer 
surface presents a narrow, oblong, articular depression, the lesser sigmoid cavity. 
The inner surface, by its prominent free margin, serves for the attachment of the 
front part of the internal lateral ligament. At the front part of this surface is a small 
rounded eminence for the attachment of one head of the Flexor digitorum sublimis. 
Behind the eminence, a depression for part of the origin of the Flexor profundus 
digitorum, and descending from it a ridge, lost below on the inner border of the 
shaft, which gives attachment to one head of the Pronator radii teres. 

The Greater Sigmoid Cavity {ai^ixa, €iSo<;, form), so called from its resemblance 
to the Greek letter S, is a semi-lunar depression of large size, situated between 
the olecranon and coronoid processes, and serving for articulation with the trochlear 
surface of the humerus. About the middle of either lateral border of this cavity 



98 OSTEOLOGY. 

is a notch, which contracts it somewhat, and serves to indicate the junction of the 
two processes of which it is formed. The cavity is concave from above down- 
wards, and divided into two lateral parts by a smooth elevated ridge, which runs 
from the summit of the olecranon to the tip of the coronoid process. Of these two 
portions, the intei'nal is the largest, and slightly concave transversely; the external 
the smallest, being nearly plane from side to side. 

The Lesser Sigmoid Cavity is a narrow, oblong, articular depression, placed on 
the outer side of the coronoid process, and serving for articulation with the head 
of the radius. It is concave from before backwards ; and its extremities, which are 
prominent, serve for the attachment of the orbicular ligament. 

The Shaft is prismatic in form at its upper part, and curved from behind 
forwards, and from within outwards, so as to , be convex behind and exter- 
nally; its central part is quite straight; its lower part rounded, smooth, and bent 
a little outwards; it tapers gradually from above downwards, and presents for 
examination three borders and three surfaces. 

The anterior border commences above at the prominent inner angle of the 
coronoid process, and terminates below in front of the styloid process. It is well 
marked above, smooth and rounded in the middle of its extent, and affords attach- 
ment to the Flexor profundus digitorum, sharp and prominent in its lower fourth 
for the attachment of the Pronator quadratus. It separates the anterior from the 
internal surface. 

The posterior border commences above at the apex of the triangular surface at 
the back part of the olecranon, and terminates below at the back part of the sty- 
loid process; it is well marked in the upper three-fourths, and gives attachment to 
an aponeurosis common to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and 
the Flexor profundus digitorum muscles; its lower fourth is smooth and rounded. 
This border separates the internal from the posterior surface. 

The external border commences above by two lines, which converge one from 
each extremity of the lesser sigmoid cavity, enclosing between them a triangular 
space for the attachment of part of the Supinator brevis, and terminates below at 
the middle of the articular surface for the radius. Its two middle-fourths are 
very prominent, and serve for the attachment of the interosseous membrane; its 
lower fourth is smooth and rounded. This border separates the anterior from the 
posterior surface. 

The anterior surface, much broader above than below, is concave in the upper 
three-fourths of its extent, and affords attachment to the Flexor profundus digito- 
rum. Its lower fourth, also concave, to the Pronator quadratus. The lower fourth 
is separated from the remaining portion of the bone by a prominent ridge, directed 
obliquely from above downwards and inwards; this ridge marks the extent of 
attachment of the Pronator above. At the junction of the upper with the middle 
third of the bone is the nutritious canal, directed obliquely upwards and inwards. 

The posterior surface, directed backwards and outwards, is broad and concave 
above, somewhat narrower and convex in the middle of its course, narrow, smooth, 
and rounded below. It presents above an oblique ridge, which runs from the pos- 
terior extremity of the lesser sigmoid cavity, downwards to the posterior border, 
marking off a small triangular surface above it for the insertion of the Anconeus 
muscle, whilst the ridge itself affords attachment to the Supinator brevis. The 
surface of bone below this is subdivided by a longitudinal ridge into two parts, 
the internal part is smooth, concave, and gives origin (occasionally is merely covered 
by) the Extensor carpi ulnaris. The external portion, wider and rougher, gives 
attachment from above downwards to part of the Supinator brevis, the Extensor 
ossis metacarpi pollicis. Extensor secundii internodii pollicis, and Extensor indicis 
muscles. 

The internal surface is broad and concave above, narrow and convex below. 
It gives attachment by its upper three-fourths to the Flexor profundus digitorum 
muscle; its lower fourth is subcutaneous. 

The Lower Extremity of the ulna is of small size, and excluded from the articu- 
lation of the wrist joint. It presents for examination two eminences; the outer 



ULNA. 

!i. — Bones of the Left Forearm. Posterior Surface. 

ULNA 



RADIUS 



99 



yI?7*EX.T.CARPI RAD. to 

EXT. CARPI RAD.BiLi 
EXT. SECUNDl INTERNODII POLLICl's 




LGXOK DICITORUM 
'SUBLIMIS' 



EXT. CARPI ULNAS 

EXT. INDICIS 

EXT. DICITORUM COMMUNIS 

EXT. MIIMimi DICITI 



100 



OSTEOLOGY. 



and larger is a rounded articular eminence, termed the head of the ulna. The 
inner, narrower and more projecting, is a non-articular eminence, the styloid 
process. The head presents an articular facet, part of which, of an oval form, is 
directed downwards, and plays on the surface of the triangular fibro-cartilage, 
which separates this bone from the wrist joint; the remaining portion, directed 
outwards, is narrow, convex, and received into the sigmoid cavity of the radius. 
The styloid process projects from the inner and back part of the bone, and descends 
a little lower than the head, terminating in a rounded summit, which affords attach- 
ment to the internal lateral ligament of the wrist. The head is separated from 
the styloid process below and in front, by a depression for the attachment of the 
triangular inter-articular fibro-cartilage; behind, by a shallow groove for the pas- 
sage of the tendon of the Extensor carpi ulnaris.. 

Structure. Similar to that of the other long bones. 

Development. By three centres; one for the shaft, one for the inferior extremity, 
and one for the olecranon (fig. 82). The centre for the shaft appears a short time after 
the radius, and soon extends through the greater part of the bone. At birth, the 
ends are cartilaginous. About the fourth year, a separate osseous nucleus appears 
in the middle of the head, which soon 82.— Plan of the Development of the Ulna. 

By Three Centres. 



extends into the styloid process. 
About the tenth year, ossific matter 
appears in the upper cartilaginous end 
of the bone near its extremity, the 
chief part of the olecranon being 
formed from an extension of the 
shaft of the bone into it. At about 
the sixteenth year, the upper epiphysis 
becomes joined, and at about the twen- 
tieth the inferior one. 

Articulations. With the humerus 
and radius. 

Attachment of Muscles. To the 
olecranon; the Triceps, Anconeus, and 
one head of the Flexor carpi ulnaris. 
To the coronoid process; the Bra- 
chialis anticus. Pronator radii teres, 
Flexor sublimis digitorum, and Flexor 
profundus digitorum. To the shaft; 
the Flexor profundus digitorum, Pro- 
nator quadratus, Flexor carpi ulnaris, 
Extensor carpi ulnaris. Anconeus, 
Supinator brevis. Extensor ossis meta- 
carpi pollicis, Extensor secundi inter- 
nodii pollicis, and Extensor indicis. 



Oleerantffz, 






^oim SJu/ft at W^-yS^ 



The Radius. 

The Radius is situated on the outer side of the fore-arm, lying parallel with the 
ulna, which exceeds it in length and size. Its upper end is small, and forms only 
a small part of the elbow-joint; but its lower end is large, and forms the chief part of 
the wrist. It is one of the long bones, having a prismatic form, slightly curved 
longitudinally, and presenting for examination a shaft and two extremities. 

The Upper Extremity presents a head, neck, and tuberosity. The head is of 
a cylindrical form, depressed on its upper surface into a shallow cup, which 
receives the radial or lesser head of the humerus. Around the circumference 
of the head is a smooth articular surface, coated with cartilage in the recent 
state, broad internally where it articulates with the lesser sigmoid cavity of 
the ulna, narrow in the rest of its circumference, to play in the orbicular liga- 
ment. The head is supported on a round, smooth, and constricted portion of 
bone, called the neck, which presents, behind, a slight ridge, for the attachment 



RADIUS. 1 01 

of part of the Supinator brevis. Beneath the neck, at the inner and front aspect 
of the bone, is a rough eminence, the tuberosity. Its surface is divided into two 
parts bj a vertical line — a posterior rough portion, for the insertion of the tendon 
of the Biceps muscle; and an anterior smooth portion, on which a bursa is inter- 
posed between the tendon and the bone. 

The Shaft of the bone is prismoid in form, narrower above than below, and 
slightly curved, so as to be convex outwards. It presents three surfaces, sepa- 
rated by three borders. 

The anterior border extends from the lower part of the tuberosity above, to the 
anterior part of the base of the styloid process below. It separates the anterior 
from the external surface. Its upper third is very prominent; and, from its 
oblique direction downwards and outwards, has received the name of the oblique 
line of the radius. It affords attachment, externally, to the Supinator brevis; 
internally, to the Flexor longus pollicis, and between these to the Flexor digito- 
rum sublimis. The middle third of the anterior border is indistinct and rounded. 
Its lower fourth is sharp, prominent, affords attachment to the Pronator quadra- 
tus, and terminates in a small tubercle, into which is inserted the tendon of the 
Supinator longus. 

The posterior border commences above, at the back part of the neck of the 
radius, and terminates below, at the posterior part of the base of the styloid pro- 
cess; it separates the posterior from the external surface. It is indistinct above 
and below, but well marked in the middle third of the bone. 

The internal or interosseous border commences above, at the back part of the 
tuberosity, where it is rounded and indistinct, becomes sharp and prominent as it 
descends, and at its lower part bifurcates into two ridges, which descend to the 
anterior and posterior margins of the sigmoid cavity. This border separates the 
anterior from the posterior surface, and has the interosseous membrane attached 
to it throughout the greater part of its extent. 

The anterior surface is narrow and concave for its upper two-thirds, and gives 
attachment to the Flexor longus pollicis muscle; below, it is broad and flat, its 
lower fourth giving attachment to the Pronator quadratus. At the junction of 
the upper and middle thirds of this surface is the nutritious foramen, which is 
directed obliquely upwards. 

The posterior surface is rounded, convex, and smooth in the upper third of its 
extent, and covered by the Supinator brevis muscle. Its middle third is broad, 
slightly concave, and gives attachment to the Extensor ossis metacarpi pollicis 
above, the Extensor primi internodii pollicis below. Its lower third is broad, 
convex, and covered by the tendons of the muscles which subsequently run in the 
grooves on the lower end of the bone. 

The external surface is rounded and convex throughout its entire extent. Its 
upper third gives attachment to the Supinator brevis muscle. About its centre 
is seen a rough ridge, for the insertion of the Pronator radii teres muscle. Its 
lower part is narrow, and covered by the tendons of the Extensor ossis metacarpi, 
and Extensor primi internodii pollicis muscles. 

The Lower Extremity of the radius is large, of quadrilateral form, and provided 
with two articular surfaces, one at the extremity, and one at the inner side of the 
bone; it presents, also, three borders, an anterior, posterior, and external. The 
articular surface at the ©xtremity of the bone is of triangular form, concave, 
smooth, and divided by a slight ridge into two parts. Of these, the external is 
large, of a triangular form, and articulates with the scaphoid bone; the inner, 
smaller and quadrilateral, articulates with the semi-lunar. The articular surface 
at the inner side of the bone is called the sigmoid cavity of the radius ; it is 
narrow, concave, smooth, and articulates with the head of the ulna. 

Its anterior border, rough and irregular, affords attachment to the anterior 
ligament of the wrist-joint. Its external border is prolonged obliquely down- 
wards upon the margin of a strong conical projection, the styloid process, which 
gives attachment by its base to the tendon of the Supinator longus, and by its 
apex to the external lateral ligament of the wrist-joint. The outer surface of 



102 



OSTEOLOGY. 



this process is marked by two grooves, which run obliquely downwards and for- 
wards, and are separated from one another by an elevated ridge. The most ante- 
rior one gives passage to the tendon of the Extensor ossis metacarpi pollicis, the 
posterior one to the tendon of the Extensor primi internodii pollicis. Its posterior 
border is convex, affords attachment to the posterior ligament of the wrist, and is 
marked by three grooves. The most external is broad, but shallow, and sub- 
divided into two by a slightly elevated ridge. The external groove transmits the 
tendon of the Extensor carpi radialis longior, the inner one the tendon of the 
Extensor carpi radialis brevior. Near the centre of the bone is a deep, but nar- 
row, groove, directed obliquely from above downwards and outwards; it transmits 

the tendon of the Extensor secundi 
83. — Plan of the Development of the Eadius. 
By Three Centres. 



AjpjicaTS at 5pliy- 



B>«-^ 



) —V'nJtes with Shaft 1 



'/hott.-C 



internodii pollicis. Internally is a 
broad groove, for the passage of the 
tendons of the Extensor communis 
digitorum, and that of the Extensor 
indicis ; the tendon of the Extensor 
minimi digiti passing through the 
groove at its point of articulation with 
the ulna. 

Development (fig. 83). By three 
centres: one for the shaft, and one for 
each extremity. That for the shaft, 
makes its appearance near the centre 
of the bone, soon after the develop- 
ment of the humerus commences. At 
birth, the shaft is ossified; but the 
ends of the bone are cartilaginous. 
About the end of the second year, 
ossification commences in the lower 
epiphysis; and about the fifth year, in 
the upper one. At the age of puberty, 
the upper epiphysis becomes joined to 
the shaft; the lower epiphysis becom- 
ing united about the twentieth year. 

Articulations. With four bones ; the 
humerus, ulna, scaphoid, and semi- 
lunar. 
Attachment of Muscles. To the tuberosity, the Biceps ; to the oblique ridge, 
the Supinator brevis. Flexor digitorum sublimis, and Flexor longus pollicis; to 
the shaft (its anterior surface), the Flexor longus pollicis and Pronator quadratus, 
(its posterior surface) the Extensor ossis metacarpi pollicis, and Extensor primi 
internodii pollicis; to the outer surface, the Pronator radii teres; and to the styloid 
process, the Supinator longus. 



k 



Appears at Zv^-y.^ — ^1 






^iir^tr.^it^J 



THE HAND. 

The Hand is subdivided into three segments, the Carpus or wrist, the Meta- 
carpus or palm, and the Phalanges or fingers. 

Carpus. 

The bones of the Cai-pus, eight in number, are arranged in two horizontal rows. 
Those of the upper row, enumerated from the radial to the ulnar side, are the 
scaphoid, semi-lunar, cuneiform, and pisiform; those of the lower row, enumerated 
m the same order, are the trapezium, trapezoid, magnum, and unciform. 

Common Characters of the Carpal Bones. 

Each bone (excepting the pisiform) presents six surfaces. Of these, the ante- 
rior or palmar, and the posterior or dorsal, are rough, for ligamentous attach- 



CARPUS. 



103 



ment, the dorsal surface being generally the broadest of the two. The superior 
and iyiferior are articular, the superior generally convex, the inferior concave; 
and the internal and external are also articular when in contact with contiguous 
bones, otherwise rough and tubercular. Their structure in all is similar, con- 
sisting within of a loose cancellous tissue enclosed in a thin layer of compact 
tissue. Each bone is also developed from a single centre of ossification. 

Bones of the Upper Row. (Figs, 84, 85.) 

The Scaphoid is the largest bone of the first row. It has received its name 
from its fancied resemblance to a boat, being broad at one end, and narrowed like 
a prow at the opposite. It is situated at the superior and external part of the 
carpus, its direction being from, above downwards, outwards, and forwards. Its 
superior surface is convex, smooth, of triangular shape, and articulates with the 
lower end of the radius. Its inferior surface, directed downwai'ds, outwards, and 
backwards, is smooth, convex, also triangular, and divided by a slight ridge into 
two parts, the external of which articulates with the trapezium, the inner with 
the trapezoid. Its posterior or dorsal surface presents a narrow, rough groove, 
which runs the entire breadth of the bone, and serves for the attachment of liga- 
ments. The anterior or palmar surface is concave above, and elevated at its 
lower and outer part into a prominent rounded tubercle, which projects forwards 
from the front of the carpus, and gives attachment to the anterior annular liga- 
ment of the wrist. The external surface is rough and narrow, and gives attach- 
ment to the external lateral ligament of the wrist. The internal surface presents 
two articular facets: of these, the superior or smaller one is flattened, of semi- 
lunar form, and articulates with the semi-lunar; the inferior or larger is concave, 
forming, with the semi-lunar bone, a concavity for the head of the os magnum. 

To ascertain to which hand this bone belongs, hold the convex radial articular 
surface upwards, and the dorsal surface backwards; the prominent tubercle will 
be directed to the side to which the bone belongs. 

Articulations. With five bones; the radius above, trapezium and trapezoid be- 
low, OS magnum and semi-lunar internally. 

The Semi-lunar bone may be distinguished by its deep concavity and crescentic 
outline. It is situated in the centre of the upper range of the carpus, between 
the scaphoid and cuneiform. Its superior surface, convex, smooth, and quadri- 
lateral in form, articulates with the radius. Its inferior surface is deeply con- 
cave, and of greater extent from before backwards, than transversely; it articu- 
lates with the head of the os magnum, and by a long narrow facet (separated by 
a ridge from the general surface) with the unciform bone. Its anterior or palmar 
and posterior or dorsal surfaces are rough, for the attachment of ligaments, the 
former being the broader, and of somewhat rounded form. The external surface 
presents a narrow, flattened, semi-lunar facet, for articulation with the scaphoid. 
The internal surface is marked by a smooth, quadrilateral facet, for articulation 
with the cuneiform. 

To ascertain to which hand this bone belongs, hold it with the dorsal surface 
upwards, and the convex articular surface backwards; the quadrilateral articular 
facet will then point to the side to which the bone belongs. 

Articulations. With five bones : the radius above, os magnum and unciform 
below, scaphoid and cuneiform on either side. 

The Cuneiform {V Os Pyramidal), may be distinguished by its pyramidal shape, 
and from having an oval-shaped, isolated facet, for articulation with the pisiform 
bone. It is situated at the upper and inner side of the carpus. The superior 
surface presents an internal, rough, non-articular portion ; and an external or 
articular portion, which is convex, smooth, and separated from the lower end 
of the ulna by the inter-articular fibro-cartilage of the wrist. The inferior 
surface, directed outwards, is concave, sinuously curved, and smooth, for articu- 
lation with the unciform. Its posterior or dorsal surface is rough, for the attach- 
ment of ligaments. Its anterior or palmar surface presents, at its inner side, an 



104 



OSTEOLOGY. 



oval-shaped facet, for articulation with the pisiform; and is rough externally, for 
ligamentous attachment. Its external surface, the base of the pyramid, is marked 

84. — Bones of the Left Hand. Dorsal Surface. 



' -^^RPl 



tvr. 



'"""'' ^Aot^U 



"^'■fRwooij 



"VTeBMODli" 







by a flat, quadrilateral, smooth facet, for articulation with the semi-lunar. The 
internal surface, the summit of the pyramid, is pointed and roughened, for the 
attachment of the internal lateral lia;ament of the wrist. 



I 

I 



CARPUS. 



105 



To ascertain to which hand tliis bone belongs, liold it so that the base is 
directed backwards, and the articular facet for the pisiform bone upwards; the 
concave articular facet will point to the side to which the bone belongs. 

Articulations. With three bones: the semi-lunar externally, the pisiform in 
front, the unciform below, and with the triangular inter- articular fibro-cartilage 
which separates it from the lower end of the ulna. 

The Pisiform bone may be known by its small size, and from its presenting a 
single articular facet. It is situated at the anterior and inner side of the carpus, 
is nearly circular in form, and presents on its posterior surface a smooth, oval 
facet, for articulation with the cuneiform bone. This facet approaches the supe- 
rior, but not the inferior, border of the bone. Its anterior or palmar surface is 
rounded and rough, and gives attachment to the anterior annular ligament. The 
outer and inner surfaces are also rough, the former being convex, the other 
usually concave. 

To ascertain to which hand it belongs, hold the bone with its posterior or arti- 
cular facet downwards, and the non-articular portion of the same surface back- 
wards; the inner concave surface will then point to the side to which the bone 
belongs. 

Articulations. With one bone, the cuneiform. 

Attachment of Muscles. To two : the Flexor carpi ulnaris, and Abductor 
minimi digiti; and to the anterior annular ligament. 

Bones of the Lower Row. (Figs. 84, 85.) 

The Trapezium is of very irregular form. It may be distinguished by a deep 
groove, for the tendon of the Flexor carpi radialis muscle. It is situated at the 
external and inferior part of the carpus, between the scaphoid and first meta- 
carpal bone. The superior surface, concave and smooth, is directed upwards and 
inwards, and articulates with the scaphoid. Its inferior surface, directed down- 
wards and outwards, is oval, concave from side to side, convex from before back- 
wards, so as to form a saddle- shaped surface, for articulation with the base of the 
first metacarpal bone. The anterior or palmar surface is narrow and rough. 
At its upper part is a deep groove, running from above obliquely downwards and 
inwards; it transmits the tendon of the Flexor carpi radialis, and is bounded 
externally by a prominent ridge, the oblique ridge of the trapezium. This sur- 
face gives attachment to the Abductor pollicis. Flexor ossis metacarpi, and Flexor 
brevis pollicis muscles ; and the anterior annular ligament. The posterior or 
dorsal surface is rough, and the external surface also broad and rough, for the 
attachment of ligaments. The internal surface presents two articular facets; the 
upper one, large and concave, articulates with the trapezoid ; the lower one, 
narrow and flattened, with the base of the second metacarpal bone. 

To ascertain to which hand it belongs, hold the bone with the grooved palmar 
surface upwards, and the external, broad, non-articular surface backwards; the 
saddle-shaped surface will then be directed to the side to which the bone 
belongs. 

Articulations. With four bones: the scaphoid above, the trapezoid and second 
metacarpal bones internally, the first metacarpal below. 

Attachment of Muscles. Abductor pollicis. Flexor ossis metacarpi, part of the 
Flexor brevis pollicis, and the anterior annular ligament. 

The Trapezoid is the smallest bone in the second row. It may be known by 
its wedge-shaped form; its broad end occupying the dorsal, its narrow end the 
palmar surface of the hand. Its superior surface, quadrilateral in form, smooth 
and slightly concave, articulates with the scaphoid. The inferior surface articu- 
lates with the upper end of the second metacarpal bone; it is convex from side to 
side, concave from before backwards, and subdivided, by an elevated ridge, into 
two unequal lateral facets. The posterior or dorsal, and anterior or palmar 
surfaces are rough, for the attachment of ligaments; the former being the larger 
of the two. The external surface, convex and smooth, articulates with the 



io6 



OSTEOLOGY. 



trapezium. The internal surface is concave and smooth below, for articulation 

with the OS magnum, rough above, for the attachment of an interosseous ligament. 

To ascertain to which side this bone belongs, let the broad dorsal surface be 

85. — Bones of the Left Hand. Palmar Surface. 



FLEXOR^ CARPJ ULNARIS 









FLEXOR BRE.VI5 MINIMI DICITI 



FLEXOR OSSIS METACARPI 
MINIMI DICITI 



ME-"^'"''''' 



Metaear/iUyS 



rUEKi BREVIS 

& 
ABDUCTOR 
MINIMI DICITI 







Sesamoid 



PBOFONOUS 



held upwards, and its inferior concavo-convex surface forwards; the internal con- 
cave surface will then point to the side to which the bone belongs. 

Articulations. With four bones ; the scaphoid above, second metacarpal bone 
below, trapezium externally, os magnum internally. 



CAEPUS. 



107 



Attachment of Muscles. Part of the Flexor brevis pollicis. 

The Os Magnum is the largest bone of the carpus, and occupies the centre of 
the wrist. It presents, above, a rounded portion or head, which is received into 
the concavity formed by the scaphoid and senai-lunar bones; a constricted portion 
or neck; and, below, the body. Its superior surface is rounded, smooth, and 
articulates with the semi-lunar. Its inferior surface is divided, by two ridges, 
into three facets, for articulation with the second, third, and fourth metacarpal 
bones; that for the third (the middle facet) being the largest of the three. The 
posterior or dorsal surface is broad and rough, and the anterior or palmar nar- 
row, rounded, but also rough, for the attachment of ligaments. The external 
surface articulates with the trapezoid by a small facet at its anterior inferior 
angle, behind which is a rough depression, for the attachment of an interosseous 
ligament. Above this is a deep and rough groove, which forms part of the neck, 
and serves for the attachment of ligaments, bounded superiorly by a smooth, con- 
vex surface, for articulation with the scaphoid. The internal surface articulates 
with the unciform by a smooth, concave, oblong facet, which occupies its posterior 
and superior parts; rough in front, for the attachment of an interosseous liga- 
ment. 

To ascertain to which hand this bone belongs, the rounded head should be held 
upwards, and the broad dorsal surface forwards ; the internal concave articular 
surface will point to its appropriate side. 

Articulatiotis. With seven bones : the scaphoid and semi-lunar above ; the 
second, third, and fourth metacarpal below; the trapezoid on the radial side; and 
the unciform on the ulnar side. 

Attachment of Muscles. Part of the Flexor brevis pollicis. 

The Unciform bone may be readily distinguished by its wedge-shaped form, 
and the hook-like process that projects from its palmar surface. It is situated at 
the inner and lower angle of the carpus, with its base downwards, resting on the 
two inner metacarpal bones, and its apex directed upwards and outwards. Its 
superior surface, the apex of the wedge, is narrow, convex, smooth, and articu- 
lates with the semi-lunar. Its inferior surface articulates with the fourth and 
fifth metacarpal bones, the concave surface for each being separated by a ridge, 
which runs from before backwards. The posterior or dorsal surface is triangular 
and rough, for ligamentous attachment. The anterior or palmar surface presents 
at its lower and inner side a curved, hook-like process of bone, the unciform pro- 
cess, directed from the palmar surface forwards and outwards. It gives attach- 
ment, by its apex, to the annular ligament; by its inner surface, to the Flexor 
brevis minimi digiti, and the Flexor ossis metacarpi minimi digiti; and is grooved 
on its outer side, for the passage of the Flexor tendons into the palm of the hand. 
This is one of the four eminences on the front of the carpus, to which the anterior 
annular ligament is attached; the others being the pisiform internally, the oblique 
ridge of the trapezium and the tuberosity of the scaphoid externally. The inter- 
nal surface articulates with the cuneiform by an oblong surface, cut obliquely 
from above downwards and inwards. Its external surface articulates with the 
OS magnum by its upper and posterior part, the remaining portion being rough, 
for the attachment of ligaments. 

To ascertain to which hand it belongs, hold the apex of the bone upwards, and 
the broad dorsal surface backwards ; the concavity of the unciform process will be 
directed to the side to which the bone belongs. 

Articulations. With five bones : the semi-lunar above, the fourth and fifth 
metacarpal below, the cuneiform internally, the os magnum externally. 

Attachment of Muscles. To two: the Flexor brevis minimi digiti, the Flexor 
ossis metacarpi minimi digiti; and to the anterior annular ligament. 

The Metacarpus.. 

The Metacarpal bones are five in number; they are long cylindrical bones, 
presenting for examination a shaft and two extremities. 



io8 OSTEOLOGY. 



Common Characters of the Metacarpal Bones. 

The shaft is prismoid in form, and curved longitudinally, so as to be convex in 
the longitudinal direction behind, concave in front. It presents three surfaces; 
two lateral, and one posterior. The lateral surfaces are concave, for the attach- 
ment of the Interossei muscles, and separated from one another by a prominent 
line. The posterior or dorsal surface is triangular, smooth, and flattened below, 
and covered, in the recent state, by the tendons of the Extensor muscles. In its 
upper half, it is divided by a ridge into two nai'row lateral depressions, for the 
attachment of the Dorsal interossei muscles. This ridge bifurcates a little above 
the centre of the bone, and its branches run to the small tubercles on each side of 
the digital extremity. 

The carpal extremity, or hase, is of a cuboidal form, and broader behind than 
in front: it articulates, above, with the carpus; and on each side with the adjoin- 
ing metacarpal bones ; its dorsal and palmar surfaces being rough, for the 
attachment of tendons and ligaments. 

The digital extremity, or head, presents an oblong surface, flattened at each 
side, for artictxlation with the first phalanx; it is broader and extends farther 
forwards in front than behind; and longer in the antero-posterior, than in the 
transverse diameter. On either side of the head is a deep depression, surmounted 
by a tubercle, for the attachment of the lateral ligament of the metacarpo-phalan- 
geal joint. The posterior surface, broad and flat, supports the Extensor tendons; 
and the anterior surface presents a median groove, bounded on each side by a 
tubercle, for the passage of the Flexor tendons. 

Peculiar Metacarpal Bones. 

The metacarpal bone of the thumb is shorter and wider than the rest, diverges 
to a greater degree from the carpus, and its palmar surface is directed inwards 
towards the palm, The shaft is flattened and broad on its dorsal aspect, and does 
not present the bifurcated ridge peculiar to the other metacarpal bones; concave 
from before backwards on its palmar surface. The carpal extremity, or base, 
presents a concavo-convex surface, for articulation with the trapezium, and has 
no lateral facets. The digital extremity is less convex than that of the other 
metacarpal bones, broader from side to side than from before backwards, and ter- 
minates anteriorly in a small articular eminence on each side, over which play 
two sesamoid bones. 

The metacarpal bone of the index finger is the longest, and its base the largest 
of the other four. Its carpal extremity is prolonged upwards and inwards; and 
its dorsal and palmar surfaces are rough, for the attachment of tendons and liga- 
ments. It presents four articular facets: one at the end of the bone, which has 
an angular depression for articulation with the trapezoid; on the radial side, a 
flat quadrilateral facet, for articulation with the trapezium; its ulnar side being 
prolonged upwards and inwards, to articulate above with the os magnum, inter- 
nally with the third metacarpal bone. 

The metacarpal bone of the middle finger is a little less in size than the pre- 
ceding; it presents a pyramidal eminence on the radial side of its base (dorsal 
aspect), which extends upwards behind the os magnum. The carpal-articular 
facet is concave behind, flat and horizontal in front, and corresponds to the os 
magnum. On the radial side is a smooth, concave facet, for articulation with the 
second metacarpal bone; and on the ulnar side two small oval facets, for articula- 
tion with the third metacarpal. 

The metacarpal bone of the ring-finger is shorter and smaller than the pre- 
ceding, and its base small and quadrilateral; its carpal surface presenting two 
facets, for articulation with the unciform and os magnum. On the radial side are 
two oval facets, for articulation with the third metacarpal bone;- and on the ulnar 
side a single concave facet, for the fifth metacai'pal. 



METACARPUS AND PHALANGES. 



109 



The metacarpal bone of the little finger may be distinguished by the concavo- 
convex form of its carpal surface, for articulation with the unciform, and from 
having only one lateral articular facet, which corresponds with the fourth meta- 
carpal bone. On its ulnar side, is a prominent tubercle for the insertion of the 
tendon of the Extensor carpi ulnaris. The dorsal surface of the shaft is marked 
by an oblique ridge, which extends from near the inner side of the upper extremity, 
to the outer side of the lower. The outer division of this surface serves for the 
attachment of the fourth Dorsal interosseous muscle; the inner division is smooth, 
and covered by the Extensor tendons of the little finger. 

Articulations. The first, with the trapezium; the second, with the trapezium, 
trapezoides, os magnum, and third metacarpal bones; the third, with the os mag- 
num, and second and fourth metacarpal bones; the fourth, with the os magnum, 
unciform, and third and fifth metacarpal bones; and the fifth, with the unciform 
and fourth metacarpal. 

Attachment of Muscles. To the metacarpal bone of the thumb, three: the Flexor 
ossis metacarpi pollicis. Extensor ossis metacarpi pollicis, and first Dorsal inter- 
osseous. To the second metacarpal bone, five: the Flexor carpi radialis. Extensor 
carpi radialis longior, first and second Dorsal interosseous, and first Palmar inter- 
osseous. To the third, five: the Extensor carpi radialis brevior. Flexor brevis 
pollicis. Adductor pollicis, and second and third Dorsal interosseous. To the 
fourth, three: the third and fourth Dorsal interosseous and second Palmar. To 
the fifth, four: the Extensor carpi ulnaris. Flexor carpi ulnaris, Flexor ossis meta- 
carpi minimi digiti, and third Dorsal interosseous. 

Phalanges. 

The Phalanges are the bones of the fingers; they are fourteen in number, three 
for each finger and two for the thumb. They are long bones, and present for 
examination a shaft, and two extremities. The shaft tapers from above down- 
wards, is convex posteriorly, concave in front from above downwards, flat from 
side to side, and marked laterally by rough ridges, which give attachment to the 
fibrous sheaths of the Flexor tendons. The metacarpal extremity or base, in the 
first row, presents an oval concave articular surface, broader from side to side, 
than from before backwards; and the same extremity in the other two rows, a 
double concavity separated by a longitudinal median ridge, extending from before 
backwards. The digital extremities are smaller than the others, and terminate, 
in the first and second row, in two small lateral condyles, separated by a slight 
groove, the articular surface being prolonged farther forwards on the palmar, than 
on the dorsal surface, especially in the first row. 

The Ungual phalanges are convex on their dorsal, flat on their palmar surfaces, 
they are recognised by their small size, and from their ungual extremity presenting, 
on its palmar aspect, a roughened elevated surface of a horse-shoe form, which 
serves to support the sensitive pulp of the finger. 

Articulations. The first row with the metacarpal bones, and the second row of 
phalanges; the second row, with the first and third; the third, with the second 
row. 

Attachment of Muscles. To the base of the first phalanx of the thumb, four 
muscles: the Extensor primi internodii pollicis. Flexor brevis pollicis, Abductor 
pollicis. Adductor pollicis. To the second phalanx, two: the Flexor longus pollicis, 
and the Extensor secundi internodii. To the base of the first phalanx of the 
index finger, the first Dorsal and the first Palmar interosseus; to that of the middle 
finger, the second and third Dorsal interosseous; to the ring finger, the fourth 
Dorsal and the second Palmar interosseous; and to that of the little finger, the 
third Palmar interosseous, the Flexor brevis minimi digiti, and Abductor minimi 
digiti. To the second phalanges, the Flexor sublimis digitorum. Extensor com- 
munis digitorum; and, in addition, the Extensor indicis, to the index finger; the 
Extensor minimi digiti, to the little finger. To the third phalanges, the Flexor 
profundus digitorum and Extensor communis digitorum. 



no 



OSTEOLOGY. 



Development op the Hand. 

The Carpal bones are each developed by a single centre; at birth they are all 
cartilagmous. Ossification proceeds in the following order (fig. 86); in the os 
magnum and unciform an ossific point appears during the first year, the former 
preceding the latter; in the cuneiform, at the third year; in the trapezium and semi- 
lunar, at the fifth year, the former preceding the latter; in the scaphoid, at the 
sixth year; in the trapezoid, during the eighth year; and in the pisiform, about 
the twelfth year. 

86. — Plan of the Development of the Hand. 



Carpus 

1. cenfrejbr each lone 

All cartiJcfqinous at Zirtli '^J^. , 



Metacarpus 
2 Centres for each tone 
IforShocft- 
i -for DiqituJ Extremity 

except /-^ 







5^> 



The Metacarpal hones are developed each by two centres: one for the shaft, and 
one for the digital extremity, for the four inner metacarpal bones; one for the 
shaft and one for the base, for the metacarpal bone of the thumb, which, in this 
respect, resembles the phalanges. Ossification commences in the centre of the 
shaft about the sixth week, and gradually proceeds to either end of the bone; 
about the third year the digital extremity of the four inner metacarpal bones and 
the base of the first metacarpal, commence to ossify, and they unite about the 
twentieth year. 

The Phalanges are each developed by two centres: one for the shaft and one 
for the base. Ossification commences in the shaft, in all three rows, at about the 
sixth week, and gradually involves the whole of the bone excepting the upper 
extremity. Ossification of the base commences in the first row between the third 
and fourth years, and a year later in those of the second and third row. The two 
centres become united between the eighteenth and twentieth years. 



FEMUE. 



Ill 



THE LOWER EXTREMITY. 



87, — Riglit Femur. Anterior Surface. 



V^ 






The Lower Extremities, two in num- obtur«tor intehnus 
ber, are connected witli the inferior part pvrtor.,,! 
of the trunk. They are divided into three 
parts, the thigh, the leg, and the foot, 
which correspond to the arm, the forearm, 
and hand in the upper extremity. 

The thigh is formed of a single bone, 
the femur. 






LICAMENTUM TCRE! 



ml 



The Femur. 

The Femur is the longest, largest, and 
heaviest bone in the skeleton, and almost 
perfectly cylindrical in the greater part 
of its extent. In the erect position of the 
body it is not vertical, but presents a 
general curvature in the longitudinal 
direction, which renders the bone convex 
in front and slightly concave behind; it 
also gradually inclines from above down- 
wards and inwards, approaching its fellow 
towards its lower part, but separated 
from it above by a very considerable in- 
terval which corresponds to the entire 
breadth of the pelvis. The degree of 
this inclination varies in different persons, 
and is greater in the female than in the 
male. The femur, like other long bones, 
is divisible into a shaft and two extremi- 
ties. 

The Upper Extremity presents for ex- 
amination a head, neck, and the greater 
and lesser trochanters. 

The head, which is globular, and forms 
rather more than a hemisphere, is directed 
upwards, inwards, and a little forwards, 
the greater part of its convexity being 
above and in front. Its surface is smooth, 
coated with cartilage in the recent state, 
and presents a little behind and below 
its centre a rough depression, for the 
attachment of the ligamentum teres. 
The neck is a flattened pyramidal pro- 
cess of bone, which connects the head 
with the shaft. It varies in length and 
obliquity at various periods of life, and 
under different circumstances. In the 
adult male, it forms an obtuse angle with 
the shaft, being directed upwards, in- 
wards, and a little forwards. In the 
female, it approaches more nearly a right 
angle. Occasionally, in very old subjects, 
and more especially in those greatly de- 
bilitated, its direction becomes horizontal, 
so that the head sinks below the level 
of the trochanter, and its length diminishes 



h;^»* 



\ : 






SUB'CRUREOS 



.l^i 



w 



'^erCoiM' 



"n^vlf 



112 OSTEOLOGY. 

to such a degree, that the head becomes almost contiguous with the shaft. The 
neck, is flattened from before backwards, contracted in tlie middle, and broader at 
its outer extremity, where it is connected with the shaft, than at its summit, where 
it is attached to the head. It is much broader in the vertical than in the ante- 
rior posterior diameter, on account of the greater amount of resistance required in 
sustaining the weight of the trunk. Its anterior surface, narrower than the 
posterior, is perforated by numerous vascular foramina. Its posterior surface is 
smooth, broader, and more concave than the anterior, and receives towards its 
outer side the attachment of the capsular ligament of the hip. Its superior border 
is short and thick, bounded externally by the great trochanter, and its surface 
perforated by large foramina. Its inferior border, long and narrow, curves a 
little backwards, to terminate at the lesser trochanter. 

The Greater Trochanter is a large irregular quadrilateral eminence, situated at 
the outer side of the neck, at its junction with the upper part of the shaft. It is 
directed a little outwards and backwards, and rises less high than the head. It 
presents for examination two surfaces and four borders. 

Its external surface, quadrilateral in form, is broad, rough, convex, and marked 
by a prominent diagonal line, which extends from the posterior superior to the 
anterior inferior angle: this line serves for the attachment of the tendon of the 
Gluteus medius. Above the line is a triangular surface, sometimes rough for 
part of the tendon of the same muscle, sometimes smooth for the interposition of a 
bursa between that tendon and the bone. Below and behind the diagonal line is 
a smooth triangular surface, over which the tendon of the Gluteus maximus muscle 
plays, a bursa being interposed. The internal surface is of much less extent than 
the external, and presents at its base a deep depression, the digital or trochan- 
teric fossa, for the attachment of the tendon of the Obturator externus muscle. 

The superior border is free; it is thick and irregular, and marked by im- 
pressions for the attachment of the Pyriformis behind, the Obturator internus and 
Gemelli in front. >The inferior border is placed at the point of junction of the 
trochanter with the outer surface of the shaft; it is rough, prominent, slightly 
curved, and gives attachment to the upper part of the Vastus externus muscle. 
The anterior border is prominent, somewhat irregular, as well as the surface of 
bone immediately below it; it afiords attachment by its outer part to the Gluteus 
minimus. The posterior border is very prominent, and appears as a free rounded 
edge, which forms the back part of the digital fossa. 

The Lesser Trochanter is a conical eminence, which varies in size in different 
subjects; it is situated at the lower and back part of the base of the neck. Its 
base is triangular, and connected with the adjacent parts of the bone by three 
well-marked borders: of these the superior is continuous with the lower border of 
the neck; \hQ posterior, with the posterior intertrochanteric line; and the inferior 
with the middle bifurcation of the linea aspera. Its summit, which is directed 
inwards and backwards, is rough, and gives insertion to the tendon of the Psoas 
magnus. The Iliacus is inserted into the shaft below the lesser trochanter, be- 
tween the Vastus internus in front, and the Pectineus behind. A well marked 
prominence, but of variable size, situated at the upper and front part of the 
neck, at its junction with the great trochanter, is called the tubercle of the 
femur; it is the point of meeting of three- muscles, the Gluteus minimus exter- 
nally, the Vastus externus below, and the tendon of the Obturator internus and 
Gemelli above. Running obliquely downwards and inwards from the tubercle is 
the spiral line of the femur, or anterior intertrochanteric line; it winds around the 
inner side of the shaft, below the lesser trochanter, and terminates in the linea . 
aspera, about two inches below this eminence. Its upper half is rough, and affords 
attachment to the capsular ligament of the hip joint; its lower half is less promi- 
nent and gives attachment to the upper part of the Vastus internus. The posterior 
inter-trochanteric line is very prominent, and runs from the summit of the great 
trochanter downwards and inwards to the upper and back part of the lesser tro- 
chanter. Its upper half forms the posterior border of the great trochanter. A 



FEMUR. 



well-marked eminence commences about 
the centre of the posterior inter-troclian- 
teric line, and passes vertically down- 
wards for about two inches along the 
back part of the shaft: it is called the 
linea quadrati, and gives attachment to 
the Quadratus femoris, and a few fibres 
of the Adductor magnus muscles. 

The Shaft, almost perfectly cylindrical 
in form, is a little broader above than in 
the centre, and somewhat flattened from 
before backwards below. It is curved from 
before backwards, smooth and convex in 
front, and strengthened behind by a pro- 
minent longitudinal ridge, the linea 
aspera. It presents for examination three 
borders separating three surfaces. Of 
the three borders, one, the linea aspera, 
is posterior, the other two are placed 
laterally. 

The linea a5joera(fig.88) is a prominent 
longitudinal ridge or crest, presenting on 
the middle third of the bone an external 
lip, an internal lip, and a rough inter- 
mediate space. A little above the centre 
of the shaft, this crest divides into three 
lines; the most external one becomes 
very rough, and is continued almost ver- 
tically upwards to the base of the great 
trochanter; the middle one, the least dis- 
tinct, is continued to the base of the 
trochanter minor; and the internal one 
is lost above in the spiral line of the 
femur. Below, the linea aspera divides 
into two bifurcations, which enclose be- 
tween them a triangular space (the po- 
pliteal space), upon which rests the 
popliteal artery. Of these two bifurca- 
cations, the outer branch is the most 
prominent, and descends to the summit 
of the outer condyle. The inner branch 
is less marked, presents a broad and 
shallow groove for the passage of the 
femoral artery, and terminates at a small 
tubercle at the summit of the internal 
condyle. 

To the inner lip of the linea aspera, 
its whole length, is attached the Vastus 
internus; and to the whole length of the 
outer lip the Vastus externus. The 
Adductor magnus is also attached to the ^/o"; 
whole length of the linea aspera, being ^"]y^ 
connected with the outer lip above, and '"""" 
the inner lip belov/. Between the Vastus 
externus and the Adductor magnus are 
attached two muscles, viz., the Gluteus 
maximus above, and the short head of the 

I 



-Right Femur. Posterior Surface. 



V 



,v^- 






' rohlUeallSJiac 



vtir'ffc^ 



- t^oovB' j'oT tcttMon 
of 

PaPI_ITEU5 



°^«^ 



\¥'fk 



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'Art^' 



114 OSTEOLOGY. 

Biceps below. Between the Adductor magnus and the Vastus internus four 
muscles are attached: the Iliacus and Pectineus above (the latter to the middle 
division of the upper bifurcation) ; below these, the Adductor brevis and Adductor 
longus. The linea aspera is perforated a little below its centre by the nutritious 
canal, which is directed obliquely from below upwards. 

The two lateral borders of the femur are only very slightly marked, the 
external extending from the anterior inferior angle of the great trochanter to the 
anterior extremity of the external condyle; the internal passes from the spiral 
line, at a point opposite the trochanter minor, to the anterior extremity of the 
internal condyle. The internal border marks the limit of attachment of the Cru- 
rseus muscle internally. 

The anterior surface includes that portion of the shaft which is situated be- 
tween the two lateral borders. It is smooth, convex, broader above and below 
than in the centre, slightly twisted, so that its upper part is directed forwards and 
a little outwards, its lower part forwards and a little inwards. The upper three- 
fourths of this surface serve for the attachment of the Crurseus; the lower fourth 
is separated from this muscle by the intervention of the synovial membrane of the 
knee-joint, and affords attachment to the Sub-crurasus to a small extent. The 
external surface includes the portion of bone between the external border and the 
outer lip of the linea aspera; it is continuous above with the outer surface of the 
great trochanter, below with the outer surface of the external condyle: to its 
upper three-fourths is attached the outer portion of the Crurseus muscle. The 
internal surface includes the portion of bone between the internal border and the 
inner lip of the linea aspera; it is continuous above with the lower border of 
the neck, below with the inner side of the internal condyle: it is covered by the 
Vastus internus muscle. 

The Lower Extremity, larger than the upper, is of a cuboid form, flattened 
from before backwards, and divided by an interval presenting a smooth depression 
in front, and a notch of considerable size behind, into two large eminences, the 
condyles. The interval is called the inter- condyloid notch. The external con- 
dyle is the most prominent anteriorly, and is the broadest both in the antero- 
posterior and transverse diameters. The internal condyle is the narrowest, 
longest, and most prominent internally. This difference in the length of the two 
condyles depends upon the obliquity of the thigh-bones, in consequence of their 
separation above at the articulation with the pelvis. If the femur is held in this 
oblique position, the surfaces of the two condyles will be seen to be nearly hori- 
zontal. The two condyles are joined together anteriorly, and form a smooth 
trochlear surface, the external border of which is more prominent, and ascends 
higher than the internal one. This surface articulates with the patella. It pre- 
sents a median groove, which extends downwards and backwards to the inter- 
condyloid notch ; and two lateral convexities, of which the external is the broader, 
more prominent, and prolonged farther upwards upon the front of the outer 
condyle. The inter-condyloid notch lodges the crucial ligaments; it is bounded 
laterally by the opposed surfaces of the two condyles, and in front by the lower 
end of the shaft. 

Outer Condyle. The outer surface of the external condyle presents, a little 
behind its centre, an eminence, the outer tuberosity; it is less convex and pro- 
minent than the inner tuberosity, and gives attachment to the external lateral 
ligament of the knee. Immediately beneath it is a groove, which commences at 
a depression a little behind the centre of the lower border of this surface: the 
depression is for the tendon of origin of the Popliteus muscle; the groove in 
which this tendon is contained is smooth, covered with cartilage in the recent 
state, and runs upwards and backwards to the posterior extremity of the condyle. 
The inner surface of the outer condyle forms one of the lateral boundaries of the 
inter-condyloid notch, and gives attachment, by its posterior part, to the anterior 
crucial ligament. The inferior surface is convex, smooth, and broader than that 
of the internal condyle. The posterior extremity is convex and smooth : just 



FEMUR. 



"5 



89. — Plan of the Development of the Femur, 
by Five Centres. 



Appears at i^yT -Vv*^! 
J^f3iaftttioi(t18'}yV^ 

to' 

Si 



Ajijtears ateiTdofl.yV 
Juins Shaft adout lS'}y '■ 



Appears 13 -14-* y^ 
^ Joins Simp about 18^ tjT 



above the articular surface is a depression, for the tendon of the outer head of the 
Gastrocnemius, 

Inner Condyle. The inner surface of the inner condyle presents a convex 
eminence, the inner tuberosity, rough, for the attachment of the internal lateral 
ligament. Above this tuberosity, at the termination of the inner bifurcation of the 
linea aspera, is a tubercle, for the insertion of the tendon of the Adductor magnus ; 
and behind and beneath the tubercle a depression, for the tendon of the inner head 
of the Gastrocnemius. The outer side of the inner condyle forms one of the lateral 
boundaries of the inter- condyloid notch, and gives attachment, by its anterior 
part, to the posterior crucial ligament. Its inferior or articular surface is con- 
vex, and presents a less extensive surface than the external condyle. 

Structure. Like that of the other cylindrical bones, the linear-aspera is com- 
posed of a very dense, ivory-like, compact tissue. 

Articulations. With three bones; the os innominatum, tibia, and patella. 

Development (fig. 89). The femur 
is developed by five centres ; one 
for the shaft, one for each extre- 
mity, and one for each trochanter. 
Of all the long bones, it is the first to 
show traces of ossification: this fi rst 
commences in the shaft, at about the 
fifth week of foetal life, the centre s of 
ossification in the epiphyses appe ar- 
ing in the following order. First , in 
the lower end of the bone, at the 
ninth month of foetal life ; from 
this the condyles and tuberosities 
are formed; in the head, at the end 
of the first year after birth; in the 
great trochanter, during the fourth 
year; and in the lesser trochanter, 
between the thirteenth and four- 
teenth. The order in which the 
epiphyses are joined to the shaft, is 
the direct reverse of their appear- 
ance; their junction does not com- 
mence until after puberty, the lesser 
trochanter being first joined, then 
the greater, then the head, and, 
lastly, the inferior extremity (the 
first in which ossification com- 
menced), which is not united until 
the twentieth year. 

Attachment of Muscles. To the great trochanter, the Gluteus medius. Gluteus 
minimus, Pyriformis, Obturator internus. Obturator externus. Gemellus superior. 
Gemellus inferior, and Quadratus femoris. To the lesser trochanter, the Psoas 
magnus, and the Iliacus below it. To the shaft, its posterior surface, the Vastus 
externus. Gluteus maximus, short head of the Biceps, Vastus internus, Adductor 
magnus, Pectineus, Adductor brevis, and Adductor longus ; to its anterior surface, 
the Crurseus and Sub-crui'£eus. To the condyles, the Gastrocnemius, Plantaris, 
and Popliteus. 



,'k 



ovear'j- at 




I'-fce-tal) ^^ ,,,. 



Joins Shaft ae-ZO''-if: 



THE LEG. 

The Leg consists of three bones: the Patella, a large sesamoid bone, placed in 
front of the knee, analogous to the olecranon process of the ulna; and the Tibia 
and Fibula. 

I 2 



ii6 



OSTEOLOGY. 



Surface. 




91- — Posteriot Surface. 



The Patella. (Figs. 90, 91). 

The Patella is a small, flat, triangular bone, situated at the anterior part of the 
knee-joint. It resembles the sesamoid bones, from being developed in the tendon 
of the Quadriceps extensor; but, in relation with the tibia, it may be regarded as 
analogous to the olecranon process of the ulna, which occasionally exists as a sepa- 
rate piece, connected to the shaft of that bone by a continuation of the tendon of 
the Triceps muscle. It presents an anterior and posterior surface, three borders, 
a base, and an apex. 

The anterior surface is convex, perforated by small apertures, for the passage 
of nutrient vessels, and marked by numerous rough, 
90.— Eight Patella, Anterior longitudinal striee. This surface is covered, in the 
recent state, by an expansion from the tendon of the 
Quadriceps extensor, separated from the integument by 
a synovial bursa, and gives attachment below to the 
ligamentum patellae. The posterior surface presents a 
smooth, oval-shaped, articular surface, covered with car- 
tilage in the recent state, and divided into two facets by 
a vertical ridge, which descends from the superior to- 
wards the inferior angle of the bone. The ridge cor- 
responds to the groove on the trochlear surface of the 
femur, and the two facets to the articular surfaces of 
the two condyles; the outer facet, for articulation with 
the outer condyle, being the broader and deeper, serves 
to indicate the leg to which the bone belongs. This 
surface presents, infer iorly, a roup,h, convex, non-arti- 
cular depression, the lower half of which gives attach- 
ment to the ligamentum patellae; the upper half being 
separated from the head of the tibia by adipose tissue. 

Its superior and lateral borders give attachment to 
the tendon of the Quadriceps extensor; to the superior 
border, that portion of the tendon which is derived from 
the Rectus and Crurjeus muscles; and to the lateral 
borders, the portion derived from the external and in- 
ternal Yasti muscles. 
The base, or superior border, is thick, directed upwards, and cut obliquely at 
the expense of its outer surface; it receives the attachment, as already mentioned, 
of part of the Quadriceps extensor tendon. 

The apex is pointed, and gives attachment to the ligamentum patellae. 
Structure. It consists of loose cancellous tissue, covered by a thin compact 
lamina. 

Development. By a single centre, which makes its appearance, according to 
Beclard, about the third year. In two instances, I have seen this bone cartilagi- 
nous throughout, at a much later period (six years). More rarely, the bone is 
developed by two centres, placed side by side. 

Articulations. With the two condyles of the femur. 

Attachment of Muscles. Four muscles are attached to the patella, viz., the 
Rectus, Cruraius, Vastus internus, and Vastus externus. The tendons of these 
muscles joined at their insertion, constitute the Quadriceps extensor cruris. 




The Tibia. 

The Tibia (figs. 92, 93) is situated at the anterior and inner side of the leg, and, 
excepting the femur, is the longest and largest bone in the skeleton. It is pris- 
moid in form, expanded above, where it enters into formation with the knee joint, 
and more slightly below. In the male, its direction is vertical, and parallel with 



TIBIA. 



117 



the bono of the opposite side, 
hut in the female it has a slight 
oblique direction downwards and 
outwards, to compensate for the 
oblique direction of the femur 
inwards. It presents for exami- 
nation a shaft and two extre- 
mities. 

The Superior Extremity, or 
head, is large and expanded on 
each side into two lateral emi- 
nences, the tuberosities. Supe- 
riorly, the tuberosities present 
two smooth concave surfaces, 
which articulate with the con- 
dyles of the femur; the internal 
articular surface is longer than 
the external, oval from before 
backwards, to articulate with the 
internal condyle; the external 
one being broader, flatter, and 
more circular, to articulate with 
the external condyle. Between 
the two articular surfaces, and 
nearer the posterior than the 
anterior aspect of the bone, is an 
eminence, the spinous process of 
the tibia, surmounted by a pro- 
minent tubercle on each side, 
which give attachment to the 
extremities of the semilunar 
fibro-cartilages; and in front and 
behind the spinous process, a 
rough depression for the attach- 
ment of the anterior and poste- 
rior crucial ligaments and the 
semilunar cartilages. Anteriorly 
the tuberosities are continuous 
with one another, presenting a 
large and somewhat flattened 
triangular surface, broad above, 
and perforated by large vascular 
foramina, narrow beloAV, where 
it terminates in a prominent 
oblong elevation of large size, 
the tubercle of the tibia; the 
lower half of this tubercle is 
rough, for the attachment of the 
ligamentum patellae; the upper 
half is a smooth facet corres- 
ponding, in the recent state, with 
a bursa which separates this 
ligament from the bone. Poste- 
riorly, the tuberosities are sepa- 
rated from each other above by 
a shallow depression, the popli- 
teal notch, which gives attach- 



92. — Bones of the Eight Leg, Anterior Surface. 

JI e a el 



StyJeiiJ VTi 




iEactexnrtl Nalleotus 



ii8 OSTEOLOGY. 

ment to the posterior crucial ligament. The posterior surface of the inner 
tuberosity presents a deep transverse groove, for the insertion of the tendon of 
the Semi-membranosus; and the posterior surface of the outer one, a flat articular 
facet, nearly circular in form, directed downwards, backwards, and outwards, for 
articulation with the fibula. The lateral surfaces are convex and rough, the internal 
one, the most prominent, gives attachment below to the internal lateral ligament. 

The Shaft of the tibia is of a triangular prismoid form, broad above, gradually 
decreasing in size to the commencement of its lower fourth, its most slender part, 
and then enlarges again towards its lower extremity. It presents for examination 
three surfaces and three borders. 

The anterior border, the most prominent of the three, is called the crest of the 
tibia, or in popular language, the shin; it commeiKies above at the tubercle, and 
terminates below at the anterior margin of the inner malleolus. This border is 
very prominent in the upper two-thirds of its extent, smooth and rounded below. 
It presents a very flexuous course, being curved outwards above, and inwards 
below; it gives attachment to the deep fascia of the leg. 

The internal border is smooth and rouiided above and below, but more promi- 
nent in the centre ; it commences at the back part of the inner tuberosity, and 
terminates at the posterior border of the internal malleolus; its upper third gives 
attachment to the internal lateral ligament of the knee, and to some fibres of the 
Popliteus muscle; its middle third, to some fibres of the Soleus and Flexor longus 
digitorum muscles. 

The external border is thin and prominent, especially its central part, and gives 
attachment to the interosseous membrane; it commences above in front of the 
fibular articular facet, and bifurcates below, forming the boundaries of a triangular 
rough surface, for the attachment of the inferior interosseous ligament, connecting 
the tibia and fibula. 

The internal surface is smooth, convex, and broader above than below; 
its upper third, directed forwards and inwards, is covered by the aponeurosis 
derived from the tendon of the Sartorius, and by the tendons of the Gracilis 
and Semi-tendinosus, all of which are inserted nearly as far forwards, as the ante- 
rior border; in the rest of its extent it is sub-cutaneous. 

The external surface is narrower than the internal, its upper two-thirds present 
a shallow groove for the attachment of the Tibialis anticus muscle; its lower third is 
smooth, convex, curves gradually forwards to the anterior part of the bone, and is 
covered from within outwards by the tendons of the following muscles: Tibialis 
anticus. Extensor proprius poUicis, Extensor longus digitorum, Peroneus tertius. 

The posterior surface (fig. 93) presents at its upper part a prominent ridge, the 
oblique line of the tibia, which extends from the back part of the articular facet for 
the fibula, obliquely downwards, to the internal border, at the junction of its 
upper and middle thirds. It marks the limit for the insertion of the Popliteus 
muscle, and serves for the attachment of the popliteal fascia, and part of the 
Soleus, Flexor longus digitorum, and Tibialis posticus muscles; the triangular 
concave surface, above, and to the inner side of this line, gives attachment to 
the Popliteus muscle. The middle third of the posterior surface is divided by a 
vertical ridge into two lateral halves; the ridge is well marked at its commence- 
ment at the oblique line, but becomes gradually indistinct below; the inner and 
broadest half gives attachment to the Flexor longus digitorum, the outer and 
narrowest, to part of the Tibialis posticus. The remaining part of the bone is 
covered by the Tibialis posticus, Flexor longus digitorum, and Flexor longus 
pollicis muscles. Immediately below the oblique line is the medullary foramen, 
which is directed obliquely downwards. 

The Lower Extremity, much smaller than the upper, is somewhat quadrilateral 
in form, and prolonged downwards, on its inner side, into a strong process, the 
internal malleolus. The inferior surface of the bone presents a quadrilateral 
smooth surface, for articulation with the astragalus; narrow internally, where 
it becomes continuous with the articular surface of the inner malleolus, broader 



TIBIA. 



119 



externally, and traversed from 
before backwards by a slight 
elevation, separating two lateral 
depressions. The anterior sur- 
face is smooth and rounded 
above, and covered by the ten- 
dons of the Extensor muscles of 
the toes; its lower margin presents 
a rough transverse depression, for 
the attachment of the anterior 
ligament of the ankle joint. The 
posterior surface presents a 
superficial groove directed 
obliquely downwards and in- 
wards, continuous with a simi- 
lar groove on the posterior ex- 
tremity of the astragalus, it 
serves for the passage of the 
tendon of the Flexor longus 
poUicis. The external surface 
presents a triangular rough de- 
pression, the lower part of which, 
in some bones, is smooth, covered 
with cartilage in the recent state 
and articulates with the fibula, 
the remaining part is rough for 
the attachment of the inferior 
interosseous ligament, which 
connects it with the fibula. 
This surface is bounded by two 
prominent ridges, continuous 
above with the interosseous 
ridge; they afford attachment 
to the anterior and posterior 
tibio-fibular ligaments. The 
internal surface is prolonged 
downwards to form a strong 
pyramidal- shaped process, flat- 
tened from without inwards, the 
inner malleolus ; its inner surface 
is convex and subcutaneous. Its 
outer surface, smooth and slight- 
ly concave, deepens the articular 
surface for the astragalus. Its 
anterior border is rough, for the 
attachment of ligamentous fibres. 
Its posterior border presents a 
broad and deep groove, directed 
obliquely downwards and in- 
wards; it is occasionally double, 
and transmits the tendons of the 
Tibialis posticus and Flexor 
longus digitorum muscles. Its 
summit is marked by a rough 
depression behind, for the attach- 
ment of the internal lateral liga- 
ment of the ankle joint. 



93. — Bones of the Right Leg. Posterior Surface. 



'otHt Teiriiu^ 




■yiozc 



120 



OSTEOLOGY. 



^:^er eoctremit^ 



ApjpeccTS out birth- 



^oin.!/ Shaft abowt 



Structure. Like that of the other long bones. 

Development. By three centres (fig. 94): one for the shaft, and one for each 
extremity. Ossification commences in the centre of the shaft about the same time 

^, „,i TN 1 , P ji m-i • as in the femur, the fiftli week, and 

04. — Plan of the Development 01 the iibia. in j^ i . 3 •l^ 

By Three Centres. gradually extends towards either ex- 

tremity. The centre for the upper 
epiphysis appears at birth; it is flat- 
tened in form, and has a thin tongue- 
Bhaj)ed process in front, which forms 
the tubercle. That for the lower 
epiphysis appears in the second year. 
The lover epiphysis joins the shaft 
at about the twentieth year, and the 
upper one about the twenty-fifth 
year. Two additional centres occa- 
sionally exist, one for the tongue- 
shaped process of the upper epiphysis, 
the tubercle, and one for the inner 
malleolus. 

Articulations. With three bones: 
the femur, fibula, and astragalus. 

Attachment of Muscles. To the 
inner tuberosity, the Semi-membra- 
nosus. To the outer tuberosity, the 
Tibialis anticus and Extensor longus 
digitorum: to the shaft; its internal 
surface, the Sartorius, Gracilis, and 
Semi-tendinosus: to its external sur- 
face, the Tibialis anticus: to its poste- 



A2>2>£(irs at 2.7.'^ j^ 




Jains Shaft a hou/f 
20^ ?/.? 



^'/i'e.r extre'^>^^^'^J 



rior surface, the Popliteus, Soleus, Flexor longus digitorum, and Tibialis posticus: 
to the tubercle, the ligamentum patellae. 

The Fibula. 

The Fibula (fig. 92, 93) is situated at the outer side of the leg. It is the 
smaller of the two bones, and, in proportion to its length, the most slender of all 
the long bones; it is placed nearly parallel with the. tibia, its lower extremity 
inclining a little forwards, so as to be on a plane anterior to that of the upper end. 
It presents for examination a shaft and two extremities. 

The Superior Extremity or Head, is of an irregular rounded form, presenting 
above a flattened articular facet, directed upwards and inwards, for articulation 
with a corresponding facet on the external tuberosity of the tibia. On the outer 
side is a thick and rough prominence, continued behind into a pointed eminence, 
the styloid process, which projects upwards from the posterior part of the head. 
The prominence above mentioned gives attachment to the tendon of the Biceps 
muscle, and to the long external lateral ligament of the knee, the ligament dividing 
this tendon into two parts. The summit of the styloid process gives attachment 
to the short external lateral ligament. The remaining part of the circumference 
of the head is rough, for the attachment, in front, of the anterior superior tibio- 
fibular ligament, and the upper and anterior part of the Peroneus longus; and 
behind, to the posterior superior tibio-fibular ligament, and the upper fibres of the 
outer head of the Soleus muscle. 

The Lower Extremity, called the malleolus externus, is of a pyramidal form, some- 
Avhat flattened from without inwards, and is longer, and descends lower than the 
internal malleolus. Its external surface is convex, sub-cutaneous, and continuous 
with a triangular (also sub-cutaneous) surface on the outer side of the shaft. The 
internal surface presents in front a smooth triangular facet, broader above than 
below, convex from above downwards, which articulates with a corresponding 



FIBULA. 121 

surface on the outer side of the astragalus. Behind and beneath the articular 
surface is a rough depression, which gives attachment to the posterior fasciculus of 
the external lateral ligament of the ankle. Its anterior border is thick and rough, 
and marked below by a depression for the attachment of the anterior fasciculus of 
the external lateral ligament. The posterior border is broad and marked by a 
shallow groove, for the passage of the tendons of the Peroneus longus and brevis 
muscles. Its summit is rounded, and gives attachment to the middle fasciculus of 
the external lateral ligament. 

The Shaft presents three surfaces, and three borders. The anterior border com- 
mences above in front of the head, runs vertically downwards to a little below the 
middle of the bone, and then curving a little outwards, bifurcates below into two 
lines, which bound the triangular sub-cutaneous surface immediately above the outer 
side of the malleolus externus. It gives attachment to an inter-muscular septum, 
which separates the muscles on the anterior surface from those on the external. 

The internal border or interosseous ridge, is situated close to the inner 
side of the preceding, it runs nearly parallel with it in the upper third of its 
extent, but diverges from it so as to include a broader space in the lower two- 
thirds. It commences above just beneath the head of the bone (sometimes it is quite 
indistinct for about an inch below the head), and terminates below at the apex of a 
rough triangular surface immediately above the articular facet of the external mal- 
leolus. It serves for the attachment of the interosseous membrane, and separates 
the extensor muscles in front, from the flexor muscles behind. The portion of bone 
included between the anterior and interosseous lines, forms the anterior surface. 

The posterior border is sharp and prominent; it commences above at the base of 
the styloid process, and terminates below in the posterior border of the outer mal- 
leolus. It is directed outwards above, backwards in the middle of its course, 
backwards and a little inwards below, and gives attachment to an aponeurosis 
which separates the muscles on the outer from those on the inner surface of the shaft. 
The portion of bone included bet-v^een this line and the interosseous ridge, forms 
the internal surface. Its upper three-fourths are subdivided into two parts, an 
anterior and a posterior, by a very prominent ridge, the oblique line of the tibia, 
which commences above at the inner side of the head, and terminates by being 
continuous with the interosseous ridge at the lower fourth of the bone. It attaches 
an aponeurosis which separates the Tibialis posticus from the Soleus above, and 
the Flexor longus poUicis below. This ridge sometimes ceases just before 
approaching the interosseous ridge. 

The anterior surface is the interval between the anterior and interosseous lines. 
It is extremely narrow and flat in the upper third of its extent; broader and grooved 
longitudinally in its lower third ; it serves for the attachment of three muscles, the 
Extensor longus digitorum, Peroneus tertius, and Extensor longus pollicis. 

The external surface, much broader than the preceding, is directed outwards in 
the upper two-thirds of its course, backwards in the lower third, where it is con- 
tinuous with the posterior border of the external malleolus. This surface is com- 
pletely occupied by the Peroneus longus and brevis muscles. 

The internal surface is the interval between the interosseous ridge and the 
posterior border, and occupies nearly two-thirds of the circumference of the bone. 
Its upper three-fourths are divided into an anterior and a posterior portion by a 
very prominent ridge already mentioned, the oblique line of the fibula. The 
anterior portion is directed inwards, and is grooved for the attachment of the 
Tibialis posticus muscle. The posterior portion is continuous below with the 
rough triangular surface above the articular facet of the outer malleolus; it is 
directed backwards above, backwards and inwards at its middle, directly inwards 
below. Its upper fourth is rough, for the attachment of the Soleus muscle; its 
lower part presents a triangular rough surface, connected to the tibia by a strong 
interosseous ligament, and between these two points", the entire surface is covered 
by the fibres of origin of the Flexor longus pollicis muscle. At about the middle 
of this surface is the nutritious foramen, which is directed downwards. 



122 



OSTEOLOGY. 



95 



Fibula. 

v~ about lil'}y.^r^^\ 



'Pnttos about 26 ^'iiV. 



In order to distinguish the side to which the bone belongs, hold it with the 

m ..,1 T-w 1 J. i?j.T. lower extremity downwards, and the broad groove 

— Plan of the Development of the „ ,, -r» . , t n i t , -^ ,-, 

j^„ Three Centres. ^^^ ^^^ ir^eronei tendons backwards, towards the 
holder, the triangular sub-cutaneous surface will 
then be directed to theside to which thebone belongs. 

Articulations. With two bones; the tibia and 
astragalus. 

Development. By three centres (fig. 95); one 
for the shaft, and one for each extremity. Ossi- 
fication commences in the shaft about the sixth 
week of foetal life, a little later than in the tibia, 
and extends gradually towards the extremities. 
At birth both ends are cartilaginous. Ossification 
commences in the lower end in the second year, 
and in the upper one about the fourth year. 
The lower epiphysis, the first in which ossification 
commences, becomes united to the shaft about the 
twentieth year, contrary to the law which appears 
to prevail with regard to the junction of the 
epiphyses with the shaft; the upper one is joined 
about the twenty-fifth year. 

Attachment of Muscles. To the head, the 
Biceps, Soleus, and Peroneus longus: to the shaft, 
its anterior surface, the Extensor longus digito- 
» rum, Peroneus ;tertius, and Extensor longus pol- 
licis: to the internal surface, the Soleus, Tibialis 
posticus, and Flexor longus pollicis: to the exter- 
nal surface, the Peroneus longus and brevis. 



Appears aiZ V4ij^ 






THE FOOT. 

The Foot (fig. 96, 97) is the terminal part of the inferior extremity; it serves to 
support the body in the erect posture, and as an important instrument of locomo- 
tion. It consists of three divisions: the Tarsus, Metatarsus, and Phalanges. 

The Tarsus. 

The bones of the Tarsus are seven in number; viz., the calcaneum, or os calcis, 
astragalus, cuboid, scaphoid, internal, middle, and external, cuneiform bones. 
These bones may be conveniently arranged into two lateral rows. The outer 
row, remarkable for its great solidity and strength, forms the basis of support to 
the foot; it consists of two bones, the os calcis and cuboid. The inner row, which 
contributes chiefly to its elasticity, is formed by the astragalus, scaphoid, and three 
cuneiform bones. 

The Calcaneum. 

The Calcaneum, or Os Calcis, is the largest bone of the tarsus. It is irregu- 
larly cuboidal in form, and situated at the lower and back part of the foot. It 
presents for examination six surfaces; superior, inferior, external, internal, ante- 
rior, and posterior. 

The superior surface is formed behind, of the upper edge of that process of the 
OS calcis which projects backwards to foi-m the heel. This process varies in 
length in different individuals; it is convex from side to side, concave from before 
backwards, and corresponds above to a mass of adipose substance placed in front 
of the tendo Achillis. In the middle of this surface are two (sometimes three) 
articular facets, separated by a broad shallow groove, directed obliquely for- 
wards and outwards, and rough for the attachment of the interosseous ligament 
connecting the astragalus and os calcis. Of these two articular surfaces, the 



TARSUS. 

96.— Bones of the Right Foot. Dorsal Surface. 



123 



Grotyv^ far peromeus loncus 

GhaOl'R fav PERONEUS BREVIS — V _ "^tei 



PERONEUS TERTIU 
PERONEUS BREVIS 




C-roove for TCTi-oton, of 

rLEXOB CONCaS POU.1CIS 



Ta^rsus 



Meta/t£Lrsws 



Iiimr'niost tendon of 

EXT.BREVIS OICITORUM 



PJtojZcu'rvges 



EXT.LONCUS POLLICIS 



124 OSTEOLOGY. (j^ 

external is the larger, and situated upon the body of the bone; it is of an oblong 
form, broader behind than in front, and convex from before backwards. The 
infernal articular surface is supported on a projecting process of bone, called the 
lesser process of the calcaneum (sustentaculum tali) ; it is of an oblong form, con- 
cave longitudinally, and sometimes subdivided into two, which differ in size and 
shape. More anteriorly is seen the upper surface of the greater process, marked 
by a rough depression for the attachment of numerous ligaments, and the tendon 
of origin of the Extensor brevis digitorum muscle. 

The inferior surface is narrow, rough, uneven, broader behind than in front, 
and convex from side to side ; it is bounded posteriorly by two tuberosities, 
separated by a rough depression : the external, small, prominent, and rounded, 
gives attachment to part of the Abductor minimi digiti; the internal, broader and 
larger, for the support of the heel, gives attachment, by its prominent inner 
margin, to the Abductor pollicis, and in front to the Flexor brevis digitorum 
muscles, and the depression between the tubercles to the Abductor minimi digiti, 
and plantar fascia. The rough surface in front of these tubercles gives attach- 
ment to the long plantar ligament; and to a prominent tubercle nearer the anterior 
part of the bone,. as well as to the transverse groove in front, is attached the short 
plantar ligament. 

The external surface is subcutaneous, and presents near its centre a tuber- 
cle, for the attachment of the middle fasciculus of the external lateral liga- 
ment. Behind the tubercle is a broad smooth surface, giving attachment, at its 
upper and anterior part, to the external astragalo-calcanean ligament ; and in 
front a narrow surface marked by two oblique grooves, separated by an elevated 
ridge: the superior groove transmits the tendon Qf the Peroneus brevis; the infe- 
rior, the tendon of the Peroneus longus; the intervening ridge gives attachment 
to a prolongation from the external annular ligament. 

The internal surface presents a deep concavity, directed obliquely downwards 
and forwards, for the transmission of the plantar vessels and nerves and Flexor 
tendons into the sole of the foot; it affords attachment to part of the Flexor 
accessorius muscle. This surface presents in front an eminence of bone, the 
lesser process, which projects horizontally inwards from the upper and front part 
of this surface. This process is concave above, and supports the anterior articu- 
lar surface of the astragalus; below, it is convex, and grooved for the tendon of 
the Flexor longus pollicis. Its free margin is rough, for the attachment of liga- 
ments. 

The anterior surface, of a somewhat triangular form, is smooth, concavo-con- 
vex, and articulates with the cuboid. It is surmounted, on its outer side, by a 
rough prominence, which forms an important guide to the surgeon in the per- 
formance of Chopart's operation. 

The posterior surface is rough, prominent, convex, and wider below than 
above. Its lower part is rough, for the attachment of the tendo Achillis; its 
upper part smooth, coated with cartilage, and corresponds to a bursa which 
separates this tendon from the bone. 

Articulations. With two bones: the astragalus and cuboid. 

Attachment of Muscles. Part of the Tibialis posticus, the tendo Achillis, Plan- 
taris. Abductor pollicis. Abductor minimi digiti. Flexor brevis digitorum. Flexor 
accessorius, and Extensor brevis digitorum. 

The Cuboid. 

The Cuboid bone is placed on the outer side of the foot, immediately in front 
of the OS calcis. It is of a pyramidal shape, its base being directed upwards and 
inwards, its apex downwards and outwards. It may always be known from all 
the other tarsal bones, by the existence of a deep grove on its under surface, for 
the tendon of the Peroneus longus muscle. It presents for examination six sur- 
faces; three articular, and three non-articular: the non-articular surfaces are the 
superior, inferior, and external. 



I 



TARSUS. 125 

The superior or dorsal surface, directed upwards and outwards, is rough, for 
the attacluiient of numerous ligaments. The inferior or plantar surface presents 
in front a deep groove, which runs obliquely from without, forwards and inwards; 
it lodges the tendon of the Peroneus longus, and is bounded behind by a promi- 
nent ridge, terminating externally in an eminence, the tuberosity of the cuboid, 
the surface of which presents a convex facet, for articulation with the sesamoid 
bone of the tendon contained in the groove. The ridge and surface of bone 
behind it are rough, for the attachment of the long and short plantar ligaments. 
The external surface, the smallest and narrowest of the three, presents a deep 
notch, formed by the commencement of the peroneal groove. 

The articular surfaces are the posterior, anterior, and internal. The posterior 
is a smooth, triangular, concavo-convex surface, for articulation with the anterior 
surface of the os calcis. The anterior, of smaller size, but also irregularly trian- 
gular, is divided by a vertical ridge into two facets; the inner quadrilateral in 
form, to articulate with the fourth metatarsal bone; the outer larger and more 
triangular, for articulation with the fifth metatarsal. The internal surface is 
broad, rough, irregularly quadrilateral, presenting at its middle and upper part a 
small oval facet, for articulation with the external cuneiform bone; and behind 
this (occasionally) a smaller facet, for articulation with the scaphoid; it is rough 
in the rest of its extent, for the attachment of strong interosseous ligaments. 

To ascertain to which foot it belongs, hold the bone so that its under surface, 
marked by the peroneal groove, looks downwards, and the large concavo-convex 
articular surface backwards, towards the holder; the small non-articular surface 
marked by the commencement of the peroneal groove, will point to the side to 
which the bone belongs. 

Articulations. With four bones: the os calcis, external cuneiform, and the 
fourth and fifth metatarsal bones, occasionally with the scaphoid. 

Attachment of Muscles. Part of the Flexor brevis pollicis. 

The Astragalus. 

The Astragalus (fig. 96), next to the os calcis, is the largest of the tarsal bones. 
It is placed at the middle and upper part of the tarsus, supporting the tibia above, 
articulating with the malleoli on either side, resting below upon the os calcis, and 
joined in front to the scaphoid. This bone may easily be recognised by its large 
rounded head, the broad articular facet on its upper convex surface, and by the 
two articular facets separated by a deep groove on its under concave surface. It 
presents six surfaces for examination. 

The superior surface presents, behind, a broad smooth trochlear surface, for 
articulation with the tibia; it is broader in front than behind, convex from be- 
fore backwards, slightly concave from side to side. In front of the trochlea 
is the upper surface of the neck of the astragalus, rough for the attachment of 
ligaments. The inferior surface presents two articular facets separated by a deep 
groove. The groove runs obliquely forwards and outwards, becoming gradually 
broader and deeper in front: it corresponds with a similar groove upon the upper 
surface of the os calcis, and forms, when articulated with that bone, a canal, filled 
up in the recent state by the calcaneo-astragaloid interosseous ligament. Of the 
two articular facets, the posterior is the larger, of an oblong form, and deeply 
concave from side to side; the anterior, although nearly of equal length, is nar- 
rower, of an elongated oval form, convex from side to side, and often subdivided 
into two by an elevated ridge; the posterior articulates with the lesser process of 
the 0^ calcis; the anterior, with the upper surface of the calcaneo-scaphoid ligament. 
The internal surface presents at its upper part a pear-shaped articular facet for the 
inner malleolus, continuous above with the trochlear surface; below the articular sur- 
face is a rough depression, for the attachment of the deep portion of the internal 
lateral ligament. The external surface presents a large triangular facet, concave 
from aljove downwards, for articulation with the external malleolus; it is con- 



126 



OSTEOLOGY. 

97. — Bones of the Eight Foot. Plantar Surface. 



fLEXOR BREVIS POtllCIS 



Tulierch: of 
Sfeajpkoid 




TIBIALIS ANTICUSI 



/' FLEXOR 8i7EVIS 
J & ABDUCTOR 
(^ MiniMI DICITI 



FLEXOR LONCUS 
\/ QICITORUM 



TARSUS. 



127 



tinuous above with the trochlear surface: in front is a deep rough margin, for the 
attachment of the anterior fasciculus of the external lateral ligament. The 
anterior surface, convex and rounded, forms the head of the astragalus; it is 
smooth, of an oval form, and directed obliquely inwards and downwards; it is 
continuous below with that part of the anterior facet on the under surface which 
rests upon the calcaneo-scaphoid ligament. The head is surrounded by a con- 
stricted portion, the neck of the astragalus. The posterior surface is narrow, and 
traversed by a groove, which runs obliquely downwards and inwards, and trans- 
mits the tendon of the Flexor longus pollicis. 

To ascertain to which foot it belongs, hold the bone with the broad articular 
surface upwards, and the rounded head forwards; the lateral triangular articular 
surface for the external malleolus will then point to the side to which the bone 
belongs. 

Articulations. With four bones; tibia, fibula, os calcis, and scaphoid. 

The Scaphoid. 

The Scaphoid or Navicular bone, so called from its fancied resemblance to a 
boat, is situated at the inner side of the tarsus, between the astragalus behind and 
the three cuneiform bones in front. This bone may be distinguished by its boat- 
like form, being concave behind, convex, and subdivided into three facets in 
front. 

The anterior surface, of an oblong from, is convex from side to side, and sub- 
divided by two ridges into three facets, for articulation with the three cuneiform 
bones. The posterior surface is oval, concave, broader externally than internally, 
and articulates with the rounded head of the astragalus. The superior surface is 
convex from side to side, and rough for the attachment of ligaments. The 
inferior, somewhat concave, irregular, and also rough for the attachment of 
ligaments. The internal surface presents a rounded tubercular eminence, the 
tuberosity of the scaphoid, which gives attachment to part of the tendon of the 
Tibialis posticus. The external surface is broad, rough, and irregular, for the 
attachment of ligamentous fibres, and occasionally presents a small facet for articu- 
lation with the cuboid bone. 

To ascertain to which foot it belongs, hold the bone with the concave articular 
surface backwards, and the broad dorsal surface upwards; the broad external 
surface will point to the side to which the bone belongs. 

Articulations. With four bones; astragalus and three cuneiform; occasionally 
also with the cuboid. 

Attachment of Muscles. Part of the Tibialis posticus. 

The Cuneiform Bones have received their name from their wedge-like form. 
They form the most anterior row of the inner division of the tarsus, being placed 
between the scaphoid behind, the three innermost metatarsal bones in front, and 
the cuboid externally. They are called ihe first, second, and third, counting from 
the inner to the outer side of the foot, and from their position, internal, middle, 
and external. 

The Internal Cuneiform. 

The Internal Cuneiform is the largest of the three. It is situated at the inner 
side of the foot, between the scaphoid behind and the base of the first metatarsal 
in front. It may be distinguished by its large size, as compared with the other 
two, and from its more irregular wedge-like form. It presents for examination 
six surfaces. 

The internal surface is subcutaneous, and forms part of the inner border of the 
foot; it is broad, quadrilateral, and presents at its anterior inferior angle a smooth 
oval facet, over which the tendon of the Tibialis anticus muscle glides; rough in 
the rest of its extent, for the attachment of ligaments. The external surface is 
concave, presenting, along its superior and posterioi- borders, a narrow surface for 
articulation with the middle cuneiform behind, and second metatarsal bone in 



128 OSTEOLOGY. 

front; in the rest of its extent, it is rough for the attachment of ligaments, and 
prominent below, where it forms part of the tuberosity. The anterior surface, 
reniform in shape, articulates with the metatarsal bone of the great toe. The 
posterior surface is tinangular, concave, and articulates with the innermost and 
largest of the three facets on the anterior surface of the scaphoid. The inferior 
or plantar surface is rough, and presents a prominent tuberosity at its back part 
for the attachment of part of the tendon of the Tibialis posticus. It also gives 
attachment in front of this to part of the tendon of the Tibialis anticus. The 
superior surface is the narrow pointed end of the wedge, which is directed upwai'ds 
and outwards ; it is rough for the attachment of ligaments. 

To ascertain to which side it belongs, hold the bone so that its superior narrow 
edge looks upwards, and the long articular surface forwards; the external surface 
marked by its vertical and horizontal articular facets will point to the side to 
which it belongs. 

Articulations. With four bones; scaphoid, middle cuneiform, and first and 
second metatarsul bones. 

Attachment of Muscles. The Tibialis anticus and posticus. 

The Middle Cuneiform. 

The Middle Cuneiform, the smallest of the three, is of very regular wedge- 
like form; the broad extremity being placed upwards, the narrow end downwards. 
It is situated between the other two bones of the same name, and corresponds to 
the scaphoid behind, and the second metatarsal in front. 

The anterior surface, triangular in form, and narrower than the posterior, articu- 
lates with the base of the second metatarsal bone. The posterior surface, also 
triangular, articulates with the scaphoid. The internal surface presents an articular 
facet, running along the superior and posterior borders, for articulation with the 
internal cuneiform, and is rough below for the attachment of ligaments. The 
external surface presents posteriorly a smooth facet for articulation with the 
external cuneiform bone. The superior surface forms the base of the wedge ; it 
is quadrilateral, broader behind than in front, and rough for the attachment of 
ligaments. The inferior surface, pointed and tubercular, is also rough for liga- 
mentous attachment. 

To ascertain to which foot the bone belongs, hold its superior or dorsal surface 
upwards, the broadest edge being towards the holder, and the smooth facet 
(limited to the posterior border) will point to the side to which it belongs. 

Articulations. With four bones; scaphoid, internal and external cuneiform, and 
second metatarsal bone. 

The External Cuneiform. 

The External Cuneiform, intermediate in size between the two preceding, is of 
a very regular wedge-like form, the broad extremity being placed upwards, the 
narrow end downwards. It occupies the centre of the front row of the tarsus 
between the middle cuneiform internally, the cuboid externally, the scaphoid 
behind, and the third metatarsal in front. It has six surfaces for examination. 

The anterior surface triangular in form, articulates with the third metatarsal bone. 
The posterior surface articulates with the most external facet of the scaphoid, and 
is rough below for the attachment of ligamentous fibres. The internal surface pre- 
sents two articular facets separated by a rough depression; the anterior one, situated 
at the superior angle of the bone, articulates with the outer side of the base of the 
second metatarsal bone; the posterior one skirts the posterior border, and articu- 
lates with the middle cuneiform; the rough depression between the two gives 
attachment to an interosseous ligament. The external surface also presents two 
articular facets, separated by a rough non-articular surface; the anterior facet, 
situated at the superior corner of the bone, is small, and articulates with the inner 
side of the base of the fourth metatarsal; the posterior, and larger one, articulates 



METATARSAL BONES. 129 

with the cuboid; the rough non-articular surface serves for the attachment of an 
interosseous ligament. The three facets for articulation with the three metatarsal 
bones are continuous with one another, and covered by a prolongation of the same 
cartilage; the facets for articulation with the middle cuneiform and scaphoid are 
also continuous, but that for articulation with the cuboid is usually separate and 
independent. The superior or dorsal surface, of an oblong form, is rough for the 
attachment of ligaments. The inferior or plantar surface is an obtuse rounded 
margin, and serves for the attachment of part of the tendon of the Tibialis posticus, 
some of the fibres of origin of the Flexor brevis pollicis, and ligaments. 

To ascertain to which side it belongs, hold the bone with the broad dorsal sur- 
face upwards, the prolonged edge backwards; the separate articular facet for the 
cuboid will point to the proper side. 

Articulations. With six bones : the scaphoid, middle cuneiform, cuboid, and 
second, third, and fourth metatarsal bones. 

Attachment of Muscles. Part of Tibialis posticus, and Flexor brevis pollicis. 

The Metatarsal Bones. 

The Metatarsal bones are five in number; they are long bones, and subdivided 
into a shaft, and two extremities. 

The Shaft is prismoid in form, tapers gradually from the tarsal to the phalan- 
geal extremity, and is slightly curved longitudinally, so as to be concave below, 
slightly convex above. 

The Posterior Extremity, or Base, is wedge-shaped, articulating by its terminal 
surface with the tarsal bones, and by its lateral surfaces with the contiguous bones ; 
its dorsal and plantar surfaces being rough, for the attachment of ligaments. 

The Anterior Extremity, or Head, presents a terminal rounded articular sur- 
face, oblong from above downwards, and extending further backwards below than 
above. Its sides are flattened, and present a depression, surmounted by a tuber- 
cle, for ligamentous attachment. Its under surface is grooved in the middle line, 
for the passage of the Flexor tendon, and marked on each side by an articular 
eminence continuous with the terminal articular surface. 

Peculiar Metatarsal Bones. 

The First is remarkable for its great size, but is the shortest of all the meta- 
tarsal bones. The shaft is strong, and of well-marked prismoid form. The 
posterior extremity presents no lateral articular facets; its terminal articular sur- 
face is of large size, of semi-lunar form, and its circumference grooved for the 
tarso-metatarsal ligaments; its inferior angle presents a rough oval prominence, 
for the insertion of the tendon of the Peroneus longus. The head is of large size; 
on its plantar surface are two grooved facets, over which glide sesamoid bones, 
separated by a smooth elevated ridge. 

The Second is the longest and largest of the remaining metatarsal bones; its 
posterior extremity being prolonged backwards, into the recess formed between 
the three cuneiform bones. Its tarsal extremity is broad above, narrow and rough 
below. It presents four articular surfaces: one behind, of a triangular form, for 
articulation with the middle cuneiform; one at the upper part of its internal 
lateral surface, for articulation with the internal cuneiform; and two on its 
external lateral surface, a superior and an inferior, separated by a rough depres- 
sion. Each articular surface is divided by a vertical ridge into two parts; the 
anterior segment of each facet articulates with the third metatarsal; the two pos- 
terior (sometimes continuous) with the external cuneiform. 

The Third articulates behind, by means of a triangular smooth surface, with 
the external cuneiform; on its inner side, by two facets, with the second meta- 
tarsal; and on its outer side, by a single facet, with the third metatarsal. This 
facet is of circular form, and situated at the upper angle of the base. 

K 



130 OSTEOLOGY. 

The Fourth is smaller in size than the preceding; its tarsal extremity presents 
a terminal quadrilateral surface, for articulation with the cuboid; a smooth facet 
on the inner side, divided by a ridge into an anterior portion for articulation with 
the third metatarsal, and a posterior portion for articulation with the external 
cuneiform; on the outer side a single facet, for articulation with the fifth metatarsal. 

The Fifth is recognised by the tubercular eminence on the outer side of its 
base; it articulates behind, by a triangular surface cut obliquely from without 
inwards, with the cuboid, and internally with the fourth metatarsal. 

Articulations. Each bone articulates with the tarsal bones by one extremity, 
and by the other with the first row of phalanges. The number of tarsal bones 
with which each metatarsal articulates, is one for the first, three for the second, 
one for the third, two for the fourth, and one for the fifth. 

Attachment of Muscles. To the first metatarsal bone, three: part of the Tibialis 
anticus, Peroneus longus, and First dorsal interosseous. To the second, three: 
the Adductor pollicis, and First and Second dorsal interosseous. To the third, 
four : the Adductor pollicis. Second and Third dorsal interosseous, and First 
plantar. To the fourth, four: the Adductor pollicis. Third and Fourth dorsal, 
and Second plantar interosseous. To the fifth, five: the Peroneus brevis, Pero- 
neus tertius. Flexor brevis minimi digiti. Fourth dorsal, and Third plantar inter- 
osseous. 

Phalanges. 

The Phalanges of the foot, both in number and general arrangement, resemble 
those in the hand; there being two in the great toe, and three in each of the 
other toes. 

The phalanges of the first row resemble closely those of the hand. The shaft 
is compressed from side to side, convex above, concave below. The posterior 
extremity is concave ; and the anterior extremity presents a trochlear-articular 
surface, for articulation with the second phalanges. 

The phalanges of the second roio are remarkably small and short, but rather 
broader than those of the first row. 

The ungual phalanges in form resemble those of the fingers; but they are 
smaller, flattened from above downwards, presenting a broad base for articulation 
with the second row, and an expanded extremity for the support of the nail and 
end of the toe. 

Articulations. The first row with the metatarsal bones, and second phalanges; 
the second of the great toe with the first phalanx, and of the other toes with the 
first and third phalanges; the third with the second row. 

Attachment of Muscles. To the first phalanges, gi'eat toe: innermost tendon of 
Extensor brevis digitorum. Abductor pollicis. Adductor pollicis, Flexor brevis 
pollicis, Transversus pedis. Second toe: First and Second dorsal interosseae. 
Third toe: Third dorsal and First plantar interosseae. Fourth toe: Fourth dor- 
sal and Second plantar interossese. Fifth toe : Flexor brevis minimi digiti, 
Abductor minimi digiti, and Third plantar interosseous. — Second phalanges, 
great toe : Extensor longus pollicis. Flexor longus pollicis. Other toes : Flexor 
brevis digitorum, one slip from the Extensor brevis digitorum and Extensor longus 
digitorum. — Third phalanges: two slips from the common tendon of the Extensor 
longus and Extensor brevis digitorum, and the Flexor longus digitorum. 

Development of the Foot. (Fig. 98.) 

The Tarsal bones are each developed by a single centre, excepting the os calcis, 
which has an epiphysis for its posterior extremity. The centres make their 
appearance in the following order: in the os calcis, at the sixth month of foetal 
life ; in the astragalus, about the seventh month ; in the cuboid, at the ninth 
month; external cuneiform, during the first year; internal cuneiform, in the third 
year ; middle cuneiform, in the fourth year. The epiphysis for the posterior 



SESAMOID BONES. 



131 



tuberosity of the os calcis appears at the tenth year, and unites with the rest of 
the bone soon after puberty. 

The Metatarsal bones are each developed by tioo centres: one for the shaft, 
and one for the digital extremity in the four outer metatarsal; one for the shaft, 
and one for the base in the metatarsal bone of the great toe. Ossification 



98. — Plan of the Development of the Foot. 



lC7ntfs afttr puiertj 



Tarsus 

/ CeTitTC for f^acJi io7i6 
^scctvi Os Calcic 



Mctatarsas 

2 CcTitrcs far each Lone 
i for Shaft 

1 -fnr I)i.cfitaZI!s:tremity 
ea-CKvt tvf 




I V2dUJS-Z0t-'y.r 
A pp. 7f?2CH^ 



Unii£ 18-20yA 



FJiaJanges 

^CcnPresfar earJi l/on£i 

fforSMfl 

f Jh7Mita,t-arsaUJa:t.y 



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commences in the centre of the shaft about the seventh week, and extends towards 
either extremity, and in the digital epiphyses about the third year; they become 
joined between the eighteenth and tAventieth years. 

The Phalanges are developed by two centres for each bone: one for the shaft, 
and one for the metatarsal extremity. 

Sesamoid Bones. 

These are small rounded masses, cartilaginous in early life, osseous in the 
adult, which are developed in those tendons which exert a certain amount of 
pressure upon the parts over which they glide. It is said that they are more 
commonly found in the male than in the female, and in persons of an active mus- 
cular habit than in those that are weak and debilitated. They are invested 
throughout their whole surface by the fibrous tissue of the tendon in which they 
are found, excepting upon that side which lies in contact with the part over which 
they play, where they present a free articular facet. They may be divided into 

K 2 



132 OSTEOLOGY. 

two kinds: those which glide over the articular surfaces of joints; those which 
play over the cartilaginous facets found on the surfaces of certain bones. 

The sesamoid bones of the joints are, in the lower extremity, the patella (already 
described), which is developed in the tendon of the Quadriceps extensor. Two 
small sesamoid bones are found opposite the metatarso-phalangeal joint of the 
great toe in each foot, in the tendons of the Flexor brevis poUicis, and occasionally 
one in the metatarso-phalangeal joints of the second toe, the little toe, and, still 
more rarely, in the third and fourth toes. 

In the upper extremity, there are two on the palmar surface, opposite the meta- 
carpo-phalangeal joint in the thumb, developed in the tendons of the Flexor brevis 
pollicis. Occasionally one or two opposite the metacarpo-phalangeal articulations 
of the fore and little fingers, and, still more rarely^, one opposite the same joints of 
the third and fourth fingers. 

Those found in tendons which glide over certain bones occupy the following 
situations. One in the tendon of the Peroneus longus, where it glides through the 
groove in the cuboid bone. One appears late in life in the tendon of the Tibialis 
anticus, opposite the smooth facet on the internal cuneiform bone. One in the 
tendon of the Tibialis posticus, opposite the inner side of the astragalus. One in 
the outer head of the Gastrocnemius, behind the outer condyle of the femur; and 
one in the Psoas and Iliacus, where they glide over the body of the pubes. Occa- 
sionally in the tendon of the Biceps, opposite the tuberosity of the radius; in the 
tendon of the Gluteus maximus, as it passes over the great trochanter; and in the 
tendons which wind around the inner and outer malleoli. 



The Articulations. 

THE various bones of which the Skeleton consists are connected together at 
different parts of their surfaces, and such connection is designated by the 
name of Joint or Articulation. If the joint is immoveable, as between the cranial 
bones, their adjacent margins are applied in almost close contact, a thin layer of 
fibrous membrane only being interj)osed; but in the moveable joints, the bones 
forming the articulation are generally expanded for greater convenience of mutual 
connexion, covered by an elastic structure, called cartilage, held together by strong 
bands, or capsules, of fibrous tissue, called ligament, and lined throughout by a 
membrane, the synovial membrane, which secretes a fluid which lubricates the 
various parts of which the joint is formed, so that the structures which enter 
into the formation of a joint are bone, cartilage, fibro- cartilage, ligament, and 
synovial membrane. 

Bone constitutes the fundamental element of all the joints. In the long bones 
the extremities are the parts which form the articulations; they are generally some- 
what enlarged and expanded, consisting of loose spongy cancellous tissue, with a 
thin coating of compact substance, which forms their articular surface, and is 
called the articular lamella. In the flat bones, the articulations usually take 
place at the edges; and in the short bones, by various parts of their surface. 

Cartilage is a firm, opaque, blueish-white substance, highly elastic, extremely 
flexible, and possessed of considerable cohesive power. That form of cartilage 
which enters into the formation of the joints is called articular cartilage; it forms 
a thin incrustation upon the articular extremities, or surfaces, of bones, and is 
admirably adapted, by its elastic property, to break the force of concussions, and 
afford perfect ease and freedom of movement between the bones. Where it covers 
the rounded ends of bones, as the extremities of the femur and humerus, it is thick 
at the centre, and becomes gradually thinner towards the circumference: an oppo- 
site arrangement exists where it lines the corresponding cavities. On the articular 
surfaces of the short bones, as the carpus and tarsus, the cartilage is disposed in a 
layer of uniform thickness throughout. The attached surface of articular cartilage 
is closely adapted to the articular lamella; the free surface is smooth, polished, 
and covered in the fcetus by an extremely thin prolongation of synovial membrane, 
which, however, at a later period of life, cannot be demonstrated. Articular car- 
tilage in the adult does not contain blood-vessels; its nutrition being derived from 
the vessels of the synovial membrane which skirt the circumference of the carti- 
lage, and from those of the adjacent bone, which are, however, separated from direct 
contact with the cartilage by means of the articular lamella. Mr. Toynbee has 
shown, that the minute vessels as they approach the articular lamella dilate, and 
forming arches, return into the cancellous tissue of the bone. The vessels of the 
synovial membrane advance forwards with it upon the circumference of the carti- 
lage for a very short distance, and then return in loops; they are only found on the 
parts not subjected to pressure. In the fcetus, and also in certain diseased condi- 
tions of the joints, the vessels advance for some distance upon the cartilage. Lym- 
phatic vessels and nerves have not, as yet, been traced in its substance. 

Fibro-cartilage is also employed in the construction of the joints, contributing 
to their strength and elasticity. This consists of a mixture of white fibrous and 
cartilaginous tissues in various proportions; it is to the first of these two consti- 
tuents that its strength and toughness is chiefly owing and to the latter Its elas- 
ticity. The fibro-cartilages admit of arrangement into four groups, inter-articular, 
inter-osseous, circumferential, and stratiform. 

The Inter-articular fibro-cartilages {menisci) are flattened fibro-cartilaginous 
plates, of a round, oval, or sickle-like form, interposed between the articular sur- 



134 ARTICULATIONS. 

faces of certain joints. They are free on both surfaces, thinner toward their 
centre than at their circumference, and held in position by their exti-emities being 
connected to the surrounding ligaments. The synovial membrane of the joint is 
prolonged over them a short distance from their attached margin. They are found 
in the temporo-maxillary, sterno-clavicular, acromio-clavicular, wrist and knee 
joints. 

The Inter-osseous fibro-cartilages are interposed between the bony surfaces of 
those joints which admit of only slight mobility, as between the bodies of the 
rertebrse and the symphysis of the pubes; they exist in the form of discs, inti- 
mately adherent to the opposed surfaces, being composed of concentric rings of 
fibrous tissue, with cartilaginous laminae interposed, the former tissue predomi- 
nating towards the circumference, the latter towards the centre. 

The Circumferential fihro-cartilages consist of a rim of fibro-cartilage, which 
surrounds the margins of some of the articular cavities, as the cotyloid cavity of 
the hip, and the glenoid cavity of the shoulder ; they serve to deepen the articular 
surface and protect the edges of the bone. 

The Stratiform fihro-cartilages are those which form a thin layer in the osseous 
grooves, through which the tendons of certain muscles glide. 

Ligaments are found in nearly all the moveable articulations; they consist of 
bands of various forms, serving to connect together the articular extremities of 
bones, and composed mainly of bundles of white fibrous tissue, placed parallel with, 
or closely interlaced with, one another, and presenting a white, shining, silvery 
aspect. Ligament is pliant and flexible, so as to allow of the most perfect freedom 
of movement, but strong, tough, and inextensile, so as not readily to yield under the 
most severely applied force; it is, consequently, admirably adapted to serve as the 
connecting medium between the bones. There, are some ligaments which consist 
entirely of yellow elastic tissue, as the ligamenta subflava, which connect together 
the adjacent arches of the vertebrae. 

Synovial Membrane is a thin, delicate membrane, which invests the arti- 
cular extremities of the bones, and is then reflected on the inner surface of the 
various ligaments which connect the articulating surfaces. It resembles the serous 
membrane in being a shut sac, but difiers in the nature of its secretion, which is 
thick, viscid, and glairy, like the white of egg ; and hence termed synovia. The 
synovial membranes found in the body admit of subdivision into three kinds, 
articular, bursal, and vaginal. 

The Articular Synovial Membranes are found in all the freely moveable 
(diarthrodial) joints. In the foetus, this membrane may be traced over the entire 
surface of the cartilages; but in the adult it is wanting, excepting at their circum- 
ference, upon which it encroaches for a short distance: it then invests the inner 
surface of the capsular or other ligaments enclosing the joint, and is reflected over 
the surface of any tendons passing through its cavity, as the tendon of the Popli- 
teus in the knee, and the tendon of the Biceps in the shoulder. In some joints, 
the synovial membrane is thrown into numerous folds, which project forward into 
the cavity. These folds consist of a reduplication of the synovial membrane, some 
of them containing fat, and, more rarely, isolated cartilage-cells; the free borders 
of the longer processes being subdivided into vascular fringe-like processes, the 
vessels of which have a convoluted arrangement. They are especially distinct in 
the knee, where they are known as the mucous and alar ligaments, and were 
described by Clop ton Havers as mucilaginous glands, and as the source of the 
synovial secretion, a view lately revived by Mr. Eainey, who finds them in the 
bursal and vaginal, as well as in the articular synovial membranes. 

The Bursal Synovial Membranes {Burses mucosce) are found interposed be- 
tween surfaces which move upon each other, producing friction, as in the gliding 
of a tendon, or of the integument over projecting bony surfaces. They are small 
shut sacs, connected by areolar tissue with the adjacent parts, and secreting a 
fluid in their interior analogous to synovia. The bursse admit of a subdivision 
into two kinds, subcutaneous and deep-seated. The subcutaneous are found in 



STRUCTURE OF JOINTS. 



135 



various situations, as between the integument and front of the patella, over the 
olecranon, the malleoli, and other prominent parts. The deep seated are more 
numerous, and usually found interposed between muscles or their tendons as they 
play over projecting bony surfaces, as between the Glutei muscles and surface of 
the gi-eat trochanter. Where one of these exists in the neighbourhood of a joint, 
it usually communicates with the cavity of the synovial membrane, as is generally the 
case with the bursa between the tendon of the Psoas and Iliacus, and the capsular 
ligament of the hip, or the one interposed between the under surface of the Sub- 
scapularis and the neck of the scapula. 

The Vaginal Synovial Membranes (synovial sheaths) serve to facilitate the 
gliding of tendons in the osseo-fibrous canals through which they pass. The 
membrane is here arranged in the form of a sheath, one layer of which adheres to 
the wall of the canal, and the other is reflected upon the outer surface of the con- 
tained tendon; the space between the two free surfaces of the membrane, being 
partially filled with synovia. These sheaths are chiefly found surrounding the 
tendons of the Flexor and Extensor muscles of the fingers and toes, as they pass 
through the osseo-fibrous canals in the hand or foot. 

Synovia is a transparent, yellowish-white, or slightly reddish fluid, viscid like 
the white of Qgg, having an alkaline reaction, and slightly saline taste. It con- 
sists, according to Frerichs, in the ox, of 94*85 water, o"56 mucus and epithelium, 
0*07 fat, 3'5i albumen and extractive matter, and 0*99 salts. 

The Articulations are divided into three classes: Synarthrosis, or immoveable; 
Amphiarthrosis, or mixed; and Diarthrosis, or moveable, 

I. Synarthrosis. Lmmoveable Articulations. 

Synarthrosis {crvv, with, apOpov, a joint), or Immoveable Joints, include all those 
articulations in which the surfaces of the bones are in almost direct contact, not se- 
parated by an intervening synovial cavity, and immoveably connected with each 
other, as between the bones of the cranium and face, excepting the lower jaw. 
The varieties of synarthrosis are three in number: Sutura, Schindylesis, Gomphosis. 

Sutura (a seam). Where the articulating surfaces are connected by a series 
of processes and indentations interlocked together, it is termed sutura vera; of 
which there are three varieties: sutura dentata, serrata, and limbosa. The sur- 
faces of the bones are not in direct contact, being separated by a layer of mem- 
brane continuous externally with the pericranium, internally with the dura mater. 
The sutura dentata {dens, a tooth) is so called from the tooth-like form of the 
projecting articular processes, as in the suture between the parietal bones. In 
the sutura serrata {serra, a saw), the edges of the two bones forming the arti- 
culation are serrated like the teeth of a fine saw, as between the two portions of 
the frontal bone. In the sutura limbosa {limbus, a selvage), besides the den- 
tated processes, there is a certain degree of bevelling of the articular surfaces, sc 
that the bones overlap one another, as in the suture between the parietal and 
occipital bones. Where the articulation is formed by roughened surfaces placed 
in apposition with one another, it is termed the false suture, sutura notha, of 
which there are two kinds: the sutura squamosa {squama, a scale), formed by 
the overlapping of two contiguous bones by broad bevelled margins, as in the 
temporo-parietal suture; and the sutura harmonia {apeiv, to adapt), where there 
is simple apposition of two contiguous rough bony surfaces, as in the articulation 
between the two superior maxillaiy bones, or of the palate processes of the palate 
bones with each other. The sutures present a great tendency to obliteration as 
age advances, the intervening fibrous-tissue becoming ossified. The frontal suture 
seldom exists after puberty; and it rarely happens that all the others are distinct 
in a skull beyond the age of fifty. 

Schindylesis {<T')(^ivSv\rjac^, a fissure) is that form of articulation in which a 
thin plate of bone is received into a cleft or fissure formed by the separation of 
two laminge of another, as in the articulation of the rostrum of the sphenoid, 
and descending plate of the ethmoid with the vomer, or in the reception of the 
latter in the fissure between the superior maxillary and palate bones. 



136 ARTICULATIONS. 

Gomphosis (<yo/x(l>o<;, a nail) is an articulation formed by the insertion of a 
conical process into a socket, as a nail is driven into a board; and is illustrated in 
the articulation of the teeth in the alveoli of the maxillary bones. 

2. Amphiarthrosis. Mixed Articulations. 

Amp Mar thro sis (a//.<^4 'on all sides,' apOpov a 'joint'), or Mixed Articulation. 
In this form of articulation, the contiguous osseous surfaces are connected together 
by broad flattened discs of fibro- cartilage, which adhere to the ends of both bones, 
as in the articulation between the bodies of the vertebrae, and first two pieces of 
the sternum; or the articulating surfaces are covered with fibro-cartilage, lined by 
a partial synovial membrane, and connected together by external ligaments, as in 
the sacro-iliac and pubic symphyses; both these forms being capable of limited 
motion in every direction. The former resemble the synarthrodia! joints in the 
continuity of their surfaces, and absence of synovial sac; the latter, the diarthro- 
dial. These joints occasionally become obliterated in old age: this is frequently 
the case in the inter-pubic articulation, and occasionally in the intervertebral and 
sacro-iliac. 

3, Diarthrosis. Moveable Articulations. 

Diarthrosis (Sia 'through,' apOpov 'a joint'). This form of articulation 
includes the greater number of the joints in the body, mobility being their dis- 
tinguishing character. They are formed by the approximation of two contiguous 
bony surfaces, covered with cartilage, connected by ligaments, and having a syno- 
vial sac interposed. The varieties of joints in this class, have been determined 
by the kind of motion permitted in each; they are four in number: Arthrodia, 
Enarthrosis, Ginglymus, Diarthrosis Rotatorius., 

Arthrodia is that form of joint which admits of a gliding movement; it is 
formed by the approximation of plane surfaces, or one slightly concave, the other 
slightly convex; the amount of motion between them being limited by the liga- 
ments, or osseous processes, surrounding the articulation; as in the articular pro- 
cesses of the vertebrae, temporo-maxillary, sterno and acromio-clavicular, inferior 
radio-ulnar, carpal, carpo-metacarpal, superior tibio-fibular, tarsal, and tarso-meta- 
tarsal articulations. 

Enarthrosis is that form of joint which is capable of motion in all directions. 
It is formed by the reception of a globular head into a deep cup-like cavity (hence 
the name ' ball and socket '), the parts being kept in apposition by a capsular 
ligament strengthened by accessory ligamentous bands, and the contiguous carti- 
laginous surfaces having a synovial sac interposed. Examples of this form of 
articulation are found in the hip and shoulder-joints. 

Ginglymus, Hinge-joint {jL'yyXv/jiO'i, a hinge). In this form of joint, the 
articular surfaces are moulded to each other in such a manner, as to permit 
motion only in one direction, forwards and backwards, the extent of motion at the 
same time being considerable. The articular surfaces are connected together by 
strong lateral ligaments, which form their chief bond of union. The most 
perfect forms of ginglymi are the elbow and ankle; the knee is less perfect, as it 
allows a slight degree of rotation in certain positions of the limb: there are also 
the metatarso-phalangeal and phalangeal joints in the lower extremity, metacarpo- 
phalangeal and phalangeal joints in the upper extremity. 

Diarthrosis rotatorius (Lateral G-inglymus). Where the mobility is limited to rota- 
tion, the joint is formed by a pivot-like process turning within a ring, or the ring 
on the pivot, the ring being formed partly of bone, partly of ligament. In the ar- 
ticulation of the odontoid process of the axis with the atlas, the ring is formed in 
front by the anterior arch of the atlas; behind, by the transverse ligament; here the 
ring rotates around the odontoid process. In the superior radio-ulnar articulation, 
the ring is formed partly by the lesser sigmoid cavity of the ulna; in the rest of its 
extent, by the orbicular ligament; here, the neck of the radius rotates within the 
ring. 



SUBDIVISION INTO THREE CLASSES. 



137 



Subjoined, in a tabular form, are the names, distinctive characters, and examples 
of the different kinds of articulations. 

Dentata, having 
tooth-like processes. 

Inter-parietal su- 
ture. 

Serrata, having 
serrated edges, like 
the teeth of a saw. 

Inter-frontal su- 
ture. 

Limbosa, having 
bevelled margins, 
and dentated pro- 
cesses. 

Occipito - parietal 
suture. 



Synarthrosis, or 
immoveable joint. 
Surfaces separated 
by fibrous membrane, 
no intervening syno- 
vial cavity, and im- 
moveably connected 
with each other. 

Example: bones of 
cranium and face 
(except lower jaw). 



Sutura. Arti- 
culation by pro- 
cesses and indent- 
ations interlocked 
toarether. 



Sutura vera 
(true) articulate 
by indented bor- 
ders. 



Sutura notha 
(false) articulate < 
^ by rough surfaces 



Squamosa,^OTXXMe,dL 
by thin bevelled mar- 
gins overlapping 
each other. 

Temporo - parietal 
suture. 

Harmonia, formed 

by the apposition of 

contiguous rough 

surfaces. 

Inter-maxillary su- 

^ture. 



Schindylesis. Articulation formed by the reception of , a 
thin plate of bone into a fissure of another. 

Rostrum of sphenoid with vomer. 

Gomphosis. An articulation formed by the insertion of a 
conical process into a socket. 

Tooth in socket. 



Amphiarthrosis, 
Mixed Articulation, 



Diarthrosis, 

Moveable Joint. 



11. Surfaces connected by fibro-cartilage, not separated by 
synovial membrane, and having limited motion. Bodies of 
vertebras. 
2. Surfaces connected by fibro-cartilage, lined by a partial 
synovial membrane. Sacro-iliac and pubic symphyses. 

Arthrodia. Gliding joint; articulation by plane surfaces, 
which glide upon each other. As in sterno and acromio- 
clavicular articulations. 

Enarthrosis. Ball and socket joint; capable of motion in 
all directions. Articulation by a globular head received into 
a cup-like cavity. As in hip and shoulder joints. 

Ginglymus. Hinge joint; motion limited to one direction, 
forwards and backwards. Articular surfaces fitted together 
so as to permit of movement in one plane. As in the elbow, 
ankle, and knee. 

Diarthrosis rotatorius. Articulation by a pivot process 
turning within a ring, or ring "around a pivot. As in supe- 
rior radio-ulnar articulation, and atlo-axoid joint. 



138 AETICULATIONS. 

The Kinds of Movement admitted in Joints. 

The movements admissible in joints may' be divided into four kindb, gliding, 
angular movement, circumduction, and rotation. 

Gliding movement is the most simple kind of motion that can take place in a 
joint, one surface gliding over another. This kind of movement is common to all 
moveable joints; but in some, as in the articulations of the carpus and tarsus, 
is the only motion permitted. This motion is not confined to plane surfaces, but 
may exist between any two contiguous surfaces, of whatever form, limited by the 
ligaments which enclose the articulation. 

Angular movement occurs only between the long bones, and may take place in four 
directions, forwards or backwards, constituting flexion and extension, or inwards 
and outwards, which constitutes abduction and adduction. Flexion and extension 
is confined to the strictly ginglymoid or hinge joints. Abduction and adduction, 
combined with flexion and extension, are met with only in the most moveable 
joints; as in the hip, shoulder, and thumb, and partially in the wrist and ankle. 

Circumduction is that limited degree of motion which takes place between the 
head of a bone and its articular cavity, whilst the extremity and sides of a limb 
are made to circumscribe a conical space, the base of which corresponds with the 
inferior extremity of the limb, the apex to the articular cavity; and is best seen 
in the shoulder and hip joints. 

Rotation is the movement of a bone upon its own axis, the bone retaining the 
same relative situation with respect to the adjacent parts; as in the articulation 
between the atlas and axis, where the odontoid process serves as a pivot around 
which the atlas turns; or in the rotation of the radius against the humerus, and 
also in the hip and shoulder. 

The articulations may be arranged into those of the trunk, those of the upper 
extremity, and those of the lower extremity. 

ARTICULATIONS OF THE TRUNK. 

These may be divided into the following groups viz.: — • 

1. Of the vertebral column. 7. Of the cartilages of the ribs with the 

2. Of the atlas with the axis. sternum, and with each other. 

3. Of the atlas with the occipital bone. 8. Of the sternum. 

4. Of the axis with the occipital bone. g. Of the vertebral column with the 

5. Of the lower jaw. pelvis. 

6. Of the ribs with the vertebra. 10. Of the Pelvis. 

I. Articulations of the Vertebral Column. 

The different segments of the vertebral column are connected together by ligaments, 
which admit of the same arrangement as the vertebrae themselves. They may be 
divided into five sets, i . Those connecting the bodies of the vertebrae. 2. Those 
connecting the lamina. 3. Those connecting the articular processes. 4. The liga- 
ments connecting the spinous processes. 5. Those of the transverse processes. 

The articulation of the bodies of the vertebrae with each other, form a series of 
amphiarthrodial joints; whilst those between the articular processes form a series 
of arthrodial joints. 

I. The Ligaments of the Bodies are 

Anterior Common Ligament. Posterior Common Ligament. 

Intervertebral Substance. 

The Anterior Common Ligament (fig. 107) is a broad and strong band of ligamen- 
tous fibres, which extends along the front surface of the bodies of the vertebrae, from 
the axis to the sacrum. It is broader below than above, and thicker in the dorsal 
than in the cervical or lumbar regions. It is attached, above, to the body of the 
axis by a pointed process, which is connected with the tendon of origin of the 
Longus colli muscle; and, as it descends, is somewhat broader opposite the centre 



OF THE SPINE. 



139 



of the body of each vertebra, than opposite the intervertebral substance. It con- 
sists of dense longitudinal fibres, which are intimately adherent to the interverte- 
bral substance and prominent margins of the vertebras; but less closely with the 
centre of the bodies. In this situation the fibres are exceedingly thick, and serve 
to fill up the concavities on their front surface, and to make the anterior surface 
of the spine more even. This ligament is composed of several layers of fibres, which 
vary in their length, but are closely interlaced with each other. The most super- 

99. — Vertical Section of two Vertebrae and their Ligaments, 
from the Lumbar Region. 



/INTERIOR 

COMIViaN 

LICT 



POSTERIOR 

COMMON 

tICT 




ficial or longest fibres extend between four or five vertebrae. A second subja- 
cent set extend between two or three vertebras; whilst a third set, the shortest 
and deepest, extend from one vertebra to the next. At the sides of the bodies, 
this ligament consists of a few short fibres, which pass from one vertebra to the 
next, separated from the median portion by large oval apertures, for the passage 
of vessels. 

The Posterior Common Ligament is situated within the spinal canal, and 
extends along the posterior surface of the bodies of the vertebrae, from the body 
of the axis above, where it is continuous with the occipito-axoid ligament, to the 
sacrum below. It is broader at the upper than at the lower part of the spine, 
and thicker in the dorsal than in the cervic.al or lumbar regions. In the situation 
of the intervertebral substance and contiguous margins of the vertebrae, where 
the ligament is more intimately adherent, it is broad, and presents a series of 
dentations with intervening concave margins; but it is narrow and thick over the 
centre of the bodies, from which it is separated by the vencs basis vertebrcB. This 
ligament is composed of smooth, shining, longitudinal fibres, denser and more com- 
pact than the anterior ligament, and composed of a superficial layer occupying the 
interval between three or four vertebrse, and of a deeper layer, which extends 
between one vertebra and the next adjacent to it. It is separated from the dura 
mater of the spinal cord by some loose filamentous tissue, very liable to serous 
infiltration. 

The Intervertebral Substance (fig. 99) is a lenticular disc of fibro-cartilage, in- 
terposed between the adjacent surfaces of the bodies of the vertebrae, from the axis 
to the base of the sacrum. These discs vary in shape, size, and thickness, in 



140 



ARTICULATIONS. 



different parts of the spine. In shape they accurately correspond with the surfaces 
of the bodies between which they are placed, being oval in the cervical and lumbar 
regions, circular in the dorsal. Their size is greatest in the lumbar region. In 
thickness they vary not only in the different regions of the spine, but in different 
parts of the same region: thus, they are uniformly thick in the lumbar region; 
thickest in front in the cervical and lumbar regions which are convex forwards, 
and behind, to a slight extent, in the dorsal region. They thus contribute, in a 
great measure, to the curvatures of the spine in the neck and loins; whilst the 
concavity of the dorsal region is chiefly due to the shape of the bodies of the 
vertebrae. The intervertebral discs form about one-fourth of the spinal column, 
exclusive of the first two vertebrae; they are not equally distributed, however, 
between the various bones; the dorsal portion of the spine having, in proportion 
to its length, a much smaller quantity than in the cervical and lumbar regions, 
which necessarily gives to the latter parts greater pliancy and freedom of move- 
ment. The intervertebral discs are adherent, by their surfaces, to the adjacent 
parts of the bodies of the vertebrae; and by their circumference are closely con- 
nected in front to the anterior, and behind to the posterior common ligament; 
■whilst in the dorsal region they are connected laterally to the heads of those ribs 
which articulate with two vertebrae, by means of the inter-articular ligament; 
they consequently form part of the articular cavities in which the heads of these 
bones are received. 

The intervertebral substance is composed, at its circumference, of laminee of 
fibrous tissue and fibro-cartilage; and at its centre of a soft, elastic, pulpy matter. 
The laminae are arranged concentrically one within the other, with their edges 
turned towards the corresponding surfaces of the vertebrae, and consist of alternate 
plates of fibrous tissue and fibro-cartilage. These plates are not quite vertical in 
their direction, those near the circumference being curved outwards and closely 
approximated; whilst those nearest the centre curve in the opposite direction, and 
are somewhat more widely separated. The fibres of which each plate is com- 
posed, are directed, for the most part, obliquely from above downwards; the fibres 
of an adjacent plate have an exactly opposite arrangement, varying in their direc- 
tion in every layer ; whilst in some few they are horizontal. This laminar 
arrangement belongs to about the outer half of each disc, the central part being 
occupied by a soft, pulpy, highly elastic substance, of a yellowish colour, which 
rises up considerably above the surrounding level, when the disc is divided hori- 
zontally. This substance presents no concentric arrangement, and consists of 
white fibrous tissue, having interspersed cells of variable shape and size. The 
pulpy matter is separated from immediate contact with the vertebrae, by the 
interposition of thin plates of cartilage. 

2. Ligaments connecting- the Lamina. 
Ligamenta Subflava. 
The Ligamenta Subflava are interposed between the laminse of the vertebrae, 
from the axis to the sacrum. They are most distinct when seen from the inner 
surface of the spine; when viewed from the outer surface, they appear short, 
being overlapped by the laminae. Each ligament consists of two lateral portions, 
which commence on each side at the root of either articular process, and pass 
backwards to the point where the laminae converge to form the spinous process, 
where their margins are thickest, and separated by a slight interval, filled up 
with areolar tissue. These ligaments consist of yellow elastic tissue, the fibres of 
which, almost perpendicular in direction, are attached to the anterior surface of 
the margin of the lamina above, and to the posterior surface, as well as to the 
margin of the lamina below. In the cervical region, they are thin in texture, 
but very broad and long; they become thicker in the dorsal region; and in the 
lumbar acqviire very considerable thickness. Their highly elastic property serves 
to preserve the upright posture, and to counteract the efforts of the Flexor muscles 
of the spine. These ligaments do not exist between the occiput and atlas, or 
between the atlas and axis. 



OF THE ATLAS WITH THE AXIS. 141 

3. Ligaments connecting the Articular Processes. 

Capsular. Synovial Membranes. 

The Capsular Ligaments are thin and loose bags of ligamentous fibre attached 
to the contiguous margins of the articulating processes of each vertebra, through 
the greater part of their circumference, and completed internally by the liga- 
menta subflava. They are longer and more loose in the cervical than in the dorsal 
or lumbar regions. The capsular ligaments are lined on their inner surface by a 
delicate synovial membrane. 

4. Ligaments connecting the Spinous Processes. 

Inter-spinous. Supra- spinous. 

The Inter-spinous Ligaments, thin and membranous, are interposed between the 
spinous processes in the dorsal and lumbar regions. Each ligament extends from 
the root to near the summit of each spinous process, and connects together their 
adjacent margins. They are narrow and elongated in the dorsal region, broader, 
quadrilateral in form, and thicker in the lumbar region. 

The Supra-spinous Ligament is a strong fibrous cord, which connects together 
the apices of the spinous processes from the seventh cervical to the spine of the 
sacrum. It is thicker and broader in the lumbar than in the dorsal region, and 
intimately blended, in both situations, with the neighbouring aponeuroses. The 
most superficial fibres of this ligament connect three or four vertebrae ; those deeper 
seated pass between two or three vertebrae; whilst the deepest connect the con- 
tiguous extremities of neighbouring vertebrae. 

5. Ligaments connecting the Transverse Processes. 
Inter-transverse. 

The Inter-transverse Ligaments consist of a few thin scattered fibres, interposed 
between the transverse processes. They are generally wanting in the cervical 
region; in the dorsal, they are rounded cords; in the lumbar region, thin and 
membranous. 

The two upper vertebrse, the Atlas and Axis, are connected together by liga- 
ments distinct from those by which the rest are united. 

2. Articulation of the Atlas with the Axis. 

The articulation of the anterior arch of the atlas with the odontoid process 
forms a lateral ginglymoid joint, whilst that between the articulating processes of the 
two bones forms a double arthrodia. The ligaments of this articulation are the 

Two Anterior Atlo-Axoid. Transverse. 

Posterior Atlo-Axoid. Two Capsular. 

Four Synovial Membranes. 

Of the Two Anterior Atlo-Axoid Ligaments (fig. 1 00), the most superficial is 
a rounded cord, situated in the middle line, attached, above, to the tubercle on the 
anterior arch of the atlas ; below, to the base of the odontoid process and body of 
the axis. The deeper ligament is a membranous layer, attached, above, to the 
lower border of the anterior arch of the atlas ; below, to the base of the odontoid 
process and body of the axis. These ligaments are in relation, in front, with the 
Recti antici majores. 

The Posterior Atlo-Axoid Ligament (fig. lOl) is a broad and thin membranous 
layer, attached, above, to the lower border of the posterior arch of the atlas; 
below, to the upper edge of the laminae of the axis. This ligament supplies the 
place of the ligamenta subflava, and is in relation, behind, with the Inferior oblique 
muscles. 



142 



ARTICULATIONS. 



The Transverse Ligament (figs. 102, 103) is a thick and strong ligamentous band, 
which arches across the ring of the atlas, and serves to retain the odontoid process 

100. — Occipito-Atloid and Atlo-Axoid Ligaments. Front View. 




CAPSULAR LIQT b 
5YNOVIA1. MEMBRANE 



CAPSULAR LICT & 
YNOVIAL MEMBRANE 



1 01. — Occipito-Atloid and Atlo-Axoid Ligaments. Posterior View. 




Arch for passage ofVitft^iralA-fl 



in firm connection with its anterior arch. This ligament is flattened from before 
backwards, broader and thicker in the middle than at either extremity, and firmly 



OF THE ATLAS WITH THE OCCH^ITAL BONE. 



143 




attached on each side of the atlas to a small tubercle on the inner surface of each 

of its lateral masses. As it crosses the odontoid process, a small fasciculus is 

derived from its upper and lower borders; the former, passing upwards to be 

inserted into the ba- k .■ ^ .■ , , ^. 

silar process of the 102.— Articulation between Odontoid Process and Atlas. 

occipital bone ; the 
latter, downwards, to 
be attached to the 
root of the odontoid 
process: hence this 
ligament has received 
the name of cruci- 
form. The transverse 
ligament divides the 
ring of the atlas into 
two unequal parts: 
of these, the poste- 
rior and larger serves 
for the transmission 

of the cord and its membranes; the anterior and smaller serving to retain the 
'odontoid process in its position. The lower border of the space formed between 
the atlas and transverse ligament being smaller than the upper (on account of the 
transverse ligament embracing firmly the narrow neck of the odontoid process), 
while the central part of the odontoid process is larger than its base; this process 
is still retained in firm connection with the anterior arch when all the other liga- 
ments have been divided. 

The Capsular Ligaments are two thin and loose capsules, connecting the 
articular surfaces of the atlas and axis, the fibres being strongest on the anterior 
and external part of the articulation. 

There are four Synovial Membranes in this articulation. One lining the 
inner surface of each of the capsular ligaments: one between the anterior surface 
of the odontoid process and anterior arch of the atlas: and one between the poste- 
rior surface of the odontoid process and the transverse ligament. This synovial 
membrane often communicates with those between the condyles of the occipital 
bone and the articular surfaces of the atlas. 

Actions. This joint is capable of great mobility, and allows the rotation of the 
atlas, and, with it, of the cranium upon the axis, the extent of rotation being 
limited by means of the odontoid ligaments. 

Articulation of the Spine with the Cranium. 
The ligaments connecting the spine with the cranium may be divided into two 
sets: Those connecting the occipital bone with the atlas; Those connecting the 
occipital bone with the axis. 

3. Articulation of the Atlas with the Occipital Bone. 
This articulation is a double arthrodia. Its ligaments are the 
Two Anterior Occipito-Atloid, 
Posterior Occipito-Atloid. 
•Two Lateral Occipito-Atloid. 
Two Capsular and Synovial Membranes. 
Of the Two Anterior Ligaments (fig. lOO), the most superficial is a strong, 
narrow, rounded cord, attached, above, to the basilar process of the occiput; below, 
to the tubercle on the anterior arch of the atlas: the deeper ligament is a broad and 
thin membranous layer, which passes between the anterior margin of the foramen 
magnum above, and the whole length of the upper border of the anterior arch of 
the atlas below. This ligament is in relation, in front, with the Eecti antici 
minores; behind, with the odontoid ligaments. 



144 



ARTICULATIONS. 



The Posterior Occipito-Atloid Ligament (fig. lOi) is a very broad but thin mem- 
branous lamina, intimately blended with the dura mater. It is connected, above, to 
the posterior margin of the foramen magnum; below, to the central part of 
the upper border of the posterior arch of the atlas. This ligament is incomplete 
at each side, and forms, with the superior intervertebral notches, an opening for 
the passage of the vertebral artery and sub-occipital nerve. It is in relation, be- 
hind, with the Recti postici minores and Obliqui superiores; in front, with the 
dura mater of the spinal canal, to which it is intimately adherent. 

The Lateral Ligaments are strong bands of fibres, directed obliquely upwards 
and inwards, attached, above, to the jugular process of the occipital bone; below, 
to the base of the transverse process of the atlas. 

The Capsular Ligaments surround the condyles of the occipital bone, and con- 
nect them with the articular surfaces of the atlas; they consist of thin and loose 
capsules, which enclose the synovial membrane of this articulation. The synovial 
membranes between the occipital bone and atlas communicate occasionally with 
that between the posterior surface of the odontoid process and transverse liga- 
ment. 

Actions. The movements permitted in this joint are flexion and extension, ' 
which give rise to the ordinary forward or backward nodding of the head, besides . 
slight lateral motion to one or the other side. When either of these actions is 
carried beyond a slight extent, the whole of the cervical portion of the spine assists 
in its production. 



4. Articulation of the Axis wjth the Occipital Bone. 
Occipito-Axoid. Three Odontoid. 

To expose these ligaments, the spinal canal should be laid open by removing the 
posterior arch of the atlas, the laminae and spinous process of the axis, and that 
portion of the occipital bone behind the foramen magnum, as seen in fig. 103. 

The Occipito-Axoid Ligament (Apparatus ligamentosus colli) is situated at the 

103. — Occipito-Axoid and Atlo-Axoid Ligaments. Posterior View. 




tAe Vcrlical jiurfion 

^ODONTOID UICT? 



OCCIPITOJ CAPSULAR LIC T & 



ATLOf CAPSULAR LICT & 

Axo I D [ Synovial 'jne/nirane 



I 



TEMPORO-M AX ILL All Y. 



H5 



upper part of the front surface of the spinal canal. It is an exceedingly broad and 
strong ligamentous band, which covers the odontoid process and its ligaments, and 
appears to be a prolongation upwards of the posterior common ligament of the 
spine. It is attached, below, to the posterior surface of the body of the axis, and 
becoming broader and expanded as it ascends, is inserted into the basilar groove 
of the occipital bone, in front of the foramen magnum. 

Relations. By its anterior surface, it is intimately connected with the transverse 
ligament; by its posterior surface, with the dura mater. By dividing this ligament 
transversely across, and turning its ends aside, the transverse and odontoid liga- 
ments are exposed. 

The Odontoid or Check Ligaments are strong rounded fibrous cords, which 
arise one on either side of the apex of the odontoid process, and passing obliquely 
upwai'ds and outwards, are inserted into the rough depressions on the inner side 
of the condyles of the occipital bone. In the triangular interval left between these 
ligaments and the margin of the foramen magnum, a third strong ligamentous band 
(ligamentum suspensorium) may be seen, which passes almost perpendicularly from 
the apex of the odontoid process to the anterior margin of the foramen, being 
intimately blended with the anterior occipito-atloid ligament. 

Actions. The odontoid ligaments serve to limit the extent to which rotation 
of the cranium may be carried; hence they have received the name of check 
ligaments. 

5. TeMPORO-M AXILLARY ARTICULATION. 

This articulation is a double arthrodia. The parts entering into its formation 
are, on each side, the anterior part of the glenoid cavity of the temporal bone and 
the eminentia articularis above; with the condyle of the lower jaw below. The 
ligaments are the following. 

External Lateral. Capsular. 

Internal Lateral. Inter-articular Fibro- cartilage. 

Stylo-maxillary, Two Synovial Membranes. 

104, — Temporo-Maxillary Articulation. External View. 




146 



ARTICULATIONS. 



105. — Temporo-Maxillary Articulation. Internal View, 



The External Lateral Ligament (fig, 1 04) is a short, thin, and narrow fasciculus, 
attached above to the outer surface of the zygoma and to the rough tubercle on its 
lower border; below, to the outer surface and posterior border of the neck of the 
lower jaw. This ligament is a little broader above than below; its fibres are 
placed parallel with one another, and directed obliquely downwards and backwards. 
Externally, it is covered by the parotid gland and by the integument. Internally, 
it is in relation with the inter-articular fibro-cartilage and the synovial 
membranes. 

The Internal Lateral lAgament (fig. 105) is a long, thin, and loose band, 
attached above by its narrow extremity to the spinous process of the sphenoid 

bone, and becoming 
broader as it descends, 
is inserted into the inner 
margin of the dental 
foramen. Its outer sur- 
face is in relation above 
with the External ptery- 
goid muscle; lower down 
it is separated from the 
neck of the condyle by 
the internal maxillary 
artery; and still more 
inferiorly the inferior 
dental vessels and nerve 
separate it from the ra- 
mus of the jaw. Inter- 
nally it is in relation 
with the Internal ptery- 
goid. 

The Stylo-maxillary 
Ligament is a thin apo- 
neurotic cord, which 
extends from near the 
apex of the styloid pro- 
cess of the temporal bone, to the angle and posterior border of the ramus of the 
lower jaw, between the Masseter and Internal pterygoid muscles. This ligament 
separates the parotid from the sub-maxillary gland, and has attached to its inner 
side part of the fibres of origin of the Stylo-glossus muscle. Although usually 
classed among the ligaments of the jaw, it can only be considered as an accessory 
in the articulation. 

The Capsular Ligament consists of a thin and loose ligamentous capsule, 
attached above to the circumference of the glenoid cavity and the articular surface 
immediately in front; below, to the neck of the condyle of the lower jaw. It 
consists of a few thin scattered fibres, and can hardly be considered as a distinct 
ligament; it is thickest at the back part of the articulation. 

The Inter-articular Fibro-cartilage (fig. 106) is a thin plate of a transversely 
oval form, placed horizontally between the condyle of the jaw and the glenoid 
cavity. Its upper surface is concave from before backwards, and a little convex 
transversely, to accommodate itself to the form of the glenoid cavity. Its under 
surface, where it is in contact with the condyle, is concave. Its circumference is 
connected externally to the external lateral ligament; internally, to the capsular 
ligament; and in front to the tendon of the External pterygoid muscle. It is 
thicker at its circumference, especially behind, than at its centre, where it is some- 
times perforated. The fibres of which it is composed have a concentric arrange- 
ment, more apparent at the circumference than at the centre. Its surfaces are 
smooth, and divide the joint into two cavities, each of which is furnished with 




CO STO- VERTEBRAL. 



f47 



.-.^.jaj'^ 




a separate synovial membrane. When the fibro-cartilage is perforated, the syno- 
vial membranes are continuous with one another. 

The Synovial Mem- _ . , ^ 

branes, two in number, '^^.-Vertical Section of Temporo-MaxiUary Articulation. 

are placed one above, 
and the other below the 
fibro-cartilage. The 

upper one, the larger 
and looser of the two, 
after lining the cartilage 
covering the glenoid 
cavity and eminentia 
articulai'is, is continued 
over the upper surface 
of the fibro-cartilage. 
The lower one is inter- 
posed between the un- 
der surface of the fibro-cartilage and the condyle of the jaw, being prolonged 
downwards a little further behind than in front. 

Actions. The movements permitted in this articulation are very extensive. Thus 
the jaw may be depressed or elevated, or it may be carried forwards or backwards, or 
from side to side. It is by the alternation of these movements performed in suc- 
cession, that a kind of rotatory movement of the lower jaw upon the upper takes 
place, which materially assists in the mastication of the food. 

If the movement of depression is carried only to a slight extent, the condyles 
remain in the glenoid cavities, their anterior part descending only to a slight extent, 
but if depression is considerable, the condyles glide from the glenoid fossge on to 
the eminentia articularis, carrying with them the inter-articular fibro-cartilages. 
When the jaw is elevated, the condyles and fibro-cartilages are carried backwards 
into their original position. When the jaw is carried forwards or backwards, a 
horizontal gliding movement of the fibro-cartilages and condyles upon the glenoid 
cavities takes place in the antero-posterior direction ; whilst in the movement from 
side to side, this occurs in the lateral direction. 

6. Articulation of the Ribs with the Vertebra. 

The articulation of the ribs with the vertebral column, may be divided into two 
sets. I. Those which connect the heads of the ribs with the bodies of the vertebrae 
2. Those which connect the neck and tubercle of the ribs with the transverse 
processes. 

I. Articulation between the Heads of the Ribs and the Bodies of 

THE Vertebra. 

These form a series of angular ginglymoid joints, connected together by the 
following ligaments: — 

Anterior Costo-vertebral or Stellate. 

Capsular. 

Inter-articular. 

Two Synovial Membranes. 

The Anterior Costo-vertebral or Stellate Ligament (fig. 107) connects the ante- 
rior part of the head of each rib, with the sides of the bodies of the vertebras, and 
the intervening intervertebral disc. It consists of three flat bundles of liga- 
mentous fibres, which radiate from the anterior part of the head of the rib. The 
superior fasciculus passes upwards to be connected with the body of the vertebra 
above; the inferior one descends to the body of the vertebra below; and the mid- 
dle one, the smallest and least distinct, passes horizontally inwards to be attached 
to the intervertebral substance. 

L 2 



148 



ARTICULATIONS. 



Relations. In front with the thoracic ganglia of the sympathetic, the pleura, 
and on the right side, the vena azygos major; behind, with the inter-articular liga- 
ment and synovial membranes. 

In the first rib, which articulates with a single vertebra only, this ligament 

does not present a dis- 
tinct division into three 



107. — Costo-vertebral and Costo-transverse Ariculations. 
Anterior View. 



fasciculi ; its superior 
fibres, however pass to 
be attached to the body 
of the last cervical ver- 
tebra, as well as to that 
of the vertebra with 
which the rib articu- 
lates. In the eleventh 
and twelfth ribs, which 
also articulate with a 
single vertebra, the 
same division does not 
exist, but the superior 
fibres of the ligament, 
in each case, are con- 
nected with the verte- 
bra above, as well as 
that with which the ribs 
articulate. 

The Capsular Liga- 
ment is a thin and 
loose ligamentous bag, 
which surrounds the 
joint between the head of the rib and the articular cavity formed by the junction 
of the vertebra3. It is very thin, firmly connected with the anterior ligament, and 
most distinct at the upper and lower parts of the articulation. 

The Inter -articular Ligament is situated in the interior of the articulation. It 
consists of a short band of fibres, flattened from above downwards, attached by one 
extremity to the sharp crest on the head of the rib, and by the other to the inter- 
vertebral disc. It divides the joint into two cavities, which have no communica- 
tion with one another, and are each lined by a separate synovial membrane. 
In the first, eleventh, and twelfth ribs, the inter-articular ligament does not exist, 
consequently there is but one synovial membrane. 

Actions. The movements permitted in these articulations are limited to elevation, 
depression, and slightly forwards and backwards. This movement varies however, 
very much in its extent in different ribs. The first rib is almost entirely immov- 
able, excepting in strong and violent inspirations. The movement of the second 
rib is also not very extensive. In the other ribs, their mobility increases succes- 
sively to the two last, which are very moveable. The ribs are generally more 
moveable in the female than in the male. 




2. Articulation between the Neck and Tubercle of the Ribs with 
THE Transverse Processes. 

The ligaments connecting these parts are — 

Anterior Costo-Transverse. 

Middle Costo-Transverse (Interosseous). 

Posterior Costo-Transverse. 

Capsular and Synovial Membrane. 

The Ante7'ior Costo-Transverse Ligament (fig. 108.) is a bi'oad and strong 



COSTO-TRANSVERSE. 



149 



band of fibres, attached below to the sharp crest on the upper border of the neck 
of each rib, and passing obliquely upwards and outwards, to the lower border of 
the transverse process immediately above. It is broader below than above, 
broader and thinner between the lower ribs than between the upper, and more 
distinct in front than behind. This ligament is in relation, in front, with the 
intercostal vessels and nerves; behind, with the Longissimus dorsi. Its internal 

io3. — Costo-Trausverse Articulation. Seen from above. 



ANTERIOR COSTO-TRANSVERSE LIG-r DIVID 



MIDDLE COSTO-TRANSVERSE 0»*, 
INTEROSSEOUS 




POSTERIOR COSTO-TRANSVERSE LIG'^ 



CAPSULAR MEMBRANE 



border completes an aperture formed between it and the articular processes, 
through which pass the posterior branches of the intercostal vessels and nerve. 
Its external border is continuous with a thin aponeurosis, which covers the 
External intercostal muscle. 

The^r^^ and last ribs have no anterior costo-transverse ligament. 

The Middle Costo- Transverse or Interosseous Ligament consists of short, but 
sti'ong, fibres, which pass between the rough surface on the posterior part of the 
neck of each rib, and the anterior surface of the adjacent transverse process. In 
order fully to expose this ligament, a horizontal section should be made across the 
transverse process and corresponding part of the rib; or the rib may be forcibly 
separated from the transverse process, and its fibres torn asunder. 

In the eleventh and tioelfth ribs, this ligament is quite rudimentary. 

The Posterior Costo-Transverse Ligament is a short, but thick and strong, 
fasciculus, which passes obliquely from the summit of the transverse process to 
the rough non-articular portion of the tubercle of the rib. This ligament is 
shorter and more oblique in the upper, than in the lower ribs. Those correspond- 
ing to the superior ribs ascend, and those of the inferior ones slightly descend. 

In the eleventh and twelfth ribs, this ligament is wanting. 

The articular portion of the tubercle of the rib, and adjacent transverse process, 
form an arthrodial joint, provided with a thin capsular ligament attached to 
the circumference of the articulating surfaces, and enclosing a small synovial 
membrane. 

In the eleventh and twelfth ribs, this articulation is wr.nting. 

Actions. The movement permitted in these joints, is limited to a slight gliding 
motion of the articular surfaces one upon the other. 



150 



ARTICULATIONS. 



7. Articulation of the Cartilages of the Ribs with the Sternum. 

The articulation of the cartilages of the true ribs with the sternum are arthro- 
dial joints. The ligaments connecting them are — 

Anterior Costo- Sternal. 

Posterior Costo- Sternal. 

Capsular. 

Synovial Membranes. 

The Anterior Costo- Sternal Ligament (fig. 109) is a broad and thin membranous 

109. — Costo-Sternal, Costo-Xiphoid, and Inter-costal Articulations. Anterior View. 

17ic synovial cavities exposed 
by a verttjcaL seetioti ffftjic SteviMin k Cki 



coii/tuiuLoiu! vdth tStcrTbuvi 



INTER-ARTICULAR llc! 

two SiiTiovbal, 7ne7niraTte9 




Single S/ytunM 
MenAmnOM 



band that radiates from the inner extremity of the cartilages of the true ribs, to the 
anterior surface of the sternum. It is composed of fasciculi, which pass in differ- 



1 



COSTO-STERNAL, COSTO-XIPIIOID, AND INTER-COSTAL. 151 

ent directions. The superior fasciculi ascend obliquely, the inferior pass obliquely 
downwards, and the middle fasciculi horizontally. The superficial fibres of this 
ligament are the longest; they intermingle with the fibres of the ligaments above 
and beneath them, with those of the opposite side, and with the tendinous fibres 
of origin of the Pectoralis major; forming a thick fibrous membrane, which covers 
the surface of the sternum, but is more distinct at the lower than at the upper 
part. 

The Posterior Costo- Sternal Ligament, less thick and distinct than the ante- 
rior, is composed of fibres which radiate from the posterior surface of the sternal 
end of the cartilages of the true ribs, to the posterior surface of the sternum, 
becoming blended with the periosteum. 

The Capsular Ligament surrounds the joints formed between the cartilages of 
the true ribs and the sternum. It is very thin, intimately blended with the 
anterior and posterior ligaments, and strengthened at the upper and lower part of 
the articulation by a few fibres, which pass from the cartilage to the side of the 
sternum. These ligaments protect the synovial membranes. 

Synovial Membranes. The cartilage of the first rib is directly continuous with 
the sternum, the synovial membrane being absent. The cartilage of the second 
rib articulates with the sternum by means of an inter-articular ligament, attached 
by one extremity to the ridge which separates the two articular facets of the 
cartilage of the second rib, and by the other extremity to the cartilage which 
unites the first and second pieces of the sternum. This articulation is provided 
with two synovial membranes. That of the third rib has also two synovial mem- 
branes; and that of the fourth, fifth, sixth, and seventh, each a single synovial 
membrane. These synovial membranes may be demonstrated by removing a thin 
section from the anterior surface of the sternum and cartilages, as seen in the 
figure. After middle life, the articular surfaces lose their polish, become rough- 
ened, and the synovial membranes appear to be wanting. In old age, the articu- 
lations do not exist, the cartilages of most of the ribs becoming firmly united to 
the sternum. The cartilage of the seventh rib, and occasionally also that of the 
sixth, is connected to the anterior surface of the ensiform appendix, by a band of 
ligamentous fibres, which varies in length and breadth in different subjects. It is 
called the costo-xiphoid ligament. 

Actions. The movements which are permitted in the costo-sternal articulations, 
are limited to elevation and dej)ression; and these only to a slight extent. 

Articulation of the Cartilages of the Ribs with each other. 

The cartilages of the sixth, seventh, and eighth ribs articulate, by their lower 
borders, with the corresponding margin of the adjoining cartilages, by means of a 
small, smdoth, oblong-shaped facet. Each articulation has a perfect synovial 
membrane enclosed in a thin capsular ligament, strengthened externally and 
internally by some ligamentous fibres (intercostal ligaments), which pass from one 
cartilage to the other, and which are intimately united to the perichondrium. 
Sometimes the cartilage of the fifth rib, more rarely that of the ninth, articulate, 
by their lower borders, with the corresponding cartilages by small oval facets; 
more frequently they are connected together by a few ligamentous fibres. Occa- 
sionally, the articular surfaces above mentioned are found wanting. 

Articulation of the Ribs with their Cartilages. 

The outer extremity of each costal cartilage is received into a depression in 
the sternal end of the ribs, and held together by the periosteum. 

8. Ligaments of the Sternum. 

The first and second pieces of the Sternum are united by a layer of cartilage 
which rarely ossifies, except at an advanced period' of life. These two segments 
are connected by an anterior and posterior ligament. 



152 



ARTICULATIONS. 



The anterior sternal ligament consists of a layer of fibres, having a longi- 
tudinal direction; they blend with the fibres of the anterior costo-sternal liga- 
ments on both sides, and with the aponeurosis of origin of the Pectoralis major. 
This ligament is rough, irregular, and much thicker at the lower than at the 
upper part of this bone. 

The posterior sternal ligament is disposed in a somewhat similar manner on 
the posterior surface of the articulation. 

9. Articulation of the Pelvis with the Spine. 

The ligaments connecting the last lumbar vertebra with the sacrum are similar 
to those which connect the segments of the spine with each other, viz. I. The con- 
tinuation downwards of the anterior and posterior' common ligaments. 2. The 
inter-vertebral substance connecting the flattened oval surfaces of the two bones, 
thus forming an amphiarthrodial joint. 3. Ligamenta subflava, connecting the 
arch of the last lumbar vertebra with the posterior border of the sacral canal. 
4. Capsular ligaments and synovial membranes connecting the articulating pro- 
cesses and forming a double arthrodia. 5. Inter- and supra-spinous ligaments. ' 

The two proper ligaments connecting the pelvis with the spine are the lumbo- 
sacral amd lumbo-iliac. 

1 10. — Articulatious of Pelvis and Hip. Anterior View. 




ofeoTm 
<>J PSOAS m ILIACU5 



The Lumbosacral Ligament (fig. no) is a short, thick, triangular fasciculus, 
connected above to the lower and front part of the transverse process of the last 
lumbar vertebra, and passing obliquely outwards, is attached below to the lateral 
surface of the base of the sacrum; becoming blended with the anterior sacro-iliac 
ligament. This ligament is in relation anteriorly with the Psoas muscle. 

The Lumbo-iliac Ligament (fig. no) passes horizontally outwards from the 



SACRO-ILIAC. 



153 



apex of the transverse process of the last lumbar vertebra, to that portion of the 
crest of the ilium immediately in front of the sacro-iliac articulation. It is of a 
triangular form, thick and narrow internally, broad and thinner externally; and is 
in relation, in front, with the Psoas muscle; behind, with the muscles occupying 
the vertebral groove; above, with the Quadratus lumborum. 



10. Articulations of the Pelvis. 

The Ligaments connecting the bones of the pelvis with each other may be 
divided into four groups, i. Those connecting the sacrum and ilium. 2. Those 
passing between the sacrum and ischium. 3. Those connecting the sacrum and 
coccyx. 4. Those between the two pubic bones. 

I. Articulation of the Sacrum and Ilium. 

The sacro-iliac articulation is an amphiarthrodial joint, formed between the 
lateral surfaces of the sacrum and ilium. The anterior or auricular portion of the 
articular surfaces is covered with a thin plate of cartilage, thicker on the sacrum 
than on the ilium. The surfaces of these cartilages in the adult are rough and 
irregular, and separated from one another by a soft yellow pulpy substance. At 
an early period of life, occasionally in the adult, and in the female during preg- 

1 1 1. — Articulations of Pelvis and Hip. Posterior View. 




: on LESSER 
SACRO-SCiATIC L I aT . 



nancy, 'they are smooth and lined by a delicate synovial membrane. The ligaments 
connecting these surfaces are the anterior and posterior sacro-iliac. 

The Anterior Sacro-iliac Ligament consists of numerous thin ligamentous bands, 
which connect the anterior surfaces of the sacrum and ilium. 

The Posterior Sacro-iliac (fig. Ill) is a strong interosseous ligament, situated 
in the deep depression between the sacrum and ilium behind, and forming the 



154 ARTICULATIONS. 

chief bond of connexion between these bones. It consists of numerous strong 
fasciculi, which pass between the bones in various directions. Three of these are 
of large size; the two superior, nearly horizontal in direction, arise from the first 
and second transverse tubercles on the posterior surface of the sacrum, and are 
inserted into the rough uneven surface at the posterior part of the inner surface 
of the ilium. The third fasciculus, oblique in direction, is attached by one extre- 
mity to the third or fourth transverse tubercle on the posterior surface of the 
sacrum, and by the other to the posterior superior spine of the ilium; it is some- 
times called the oblique sacro-iliac ligament. 

2. Akticulation op the Sacrum and Ischium. 

The Great Sacro- Sciatic (Posterior). 
The Lesser Sacro- Sciatic (Anterior). 

The Great or Posterior Sacro- Sciatic Ligament is situated at the posterior 
and inferior part of the pelvis. It is thin, flat, and triangular in form; narrower 
in the middle than at the extremities; attached by its broad base to the posterior 
inferior spine of the ilium, to the third and fourth transverse tubercles on the 
sacrum, and to the lower part of the lateral margin of that bone and the coccyx; 
passing obliquely downwards, outwards, and forwards, it becomes narrow and 
thick; and at its insertion into the inner margin of the tuberosity, it increases in 
breadth, and is prolonged forwards along the inner margin of the ramus forming 
the falciform ligament. The free concave edge of this ligament has attached to 
it the obturator fascia, with which it forms a kind of groove, protecting the 
internal pudic vessels and nerve. One of its surfaces is turned towards the peri- 
naeum, the other towards the Obturator internus muscle. 

The posterior surface of this ligament gives origin, by its whole extent, to 
fibres of the Gluteus maximus. Its anterior surface is united to the lesser sacro- 
sciatic ligament. Its superior border forms the lower boundary of the lesser 
sacro-sciatic foramen. Its loioer border forms part of the boundary of the peri- 
neum. This ligament is pierced by the coccygeal branch of the sciatic artery. 

The Lesser or Anterior Sacro- Sciatic Ligament, much shorter and smaller 
than the preceding, is thin, triangular in form, attached by its apex to the spine 
of the ischium, and internally, by its broad base, to the lateral margins of the 
sacrum and coccyx, anterior to the attachment of the great sacro-sciatic ligament, 
with which its fibres are intermingled. 

It is in relation, anteriorly, with the Coccygeus muscle; posteriorly, it is 
covered by the posterior ligament, and crossed by the pudic vessels and nerves. 
Its superior border forms the lower boundary of the great sacro-sciatic foramen. 
Its inferior border, part of the lesser sacro-sciatic foramen. 

These two ligaments convert the sacro-sciatic notches into foramina. The 
superior or larger sacro-sciatic foramen is bounded, in front and above, by the 
posterior border of the os innominatum; behind, by the great sacro-sciatic liga- 
ment; and below, by the lesser ligament. It is partially filled up, in the recent 
state, by the Pyriformis muscle. Above this muscle, the gluteal vessels and 
nerve emerge from the pelvis; and below it; the ischiatic vessels and nerves, the 
internal pudic vessels and nerve, and the nerve to the Obturator internus. The 
inferior or smaller sacro-sciatic foramen is bounded, in front, by the tuber ischii ; 
above, by the spine and lesser ligament; behind, by the greater ligament. It 
transmits the tendon of the Obturator internus muscle, its nerve, and the pudic 
vessels and nerve. 

3. Articulation of the Sacrum and Coccyx. 

This articulation is an amphiarthrodial joint, formed between the oval surface 
on the summit of the sacrum, and the base of the coccyx. It is analogous to the 



SACRO-COCCYGEAL. 155 

joints between the bodies of the vertebrae, and is connected by similar ligaments. 
They are the 

Anterior Sacro- Coccygeal. 

Posterior Sacro-Coccygeal. 

Inter-articular Fibro-Cartilage. 

The Anterior Sacro-Coccygeal Ligament consists of a few irregular fibres, 
which descend from the anterior surface of the sacrum to the front of the coccyx, 
becoming blended with the periosteum. 

The Posterior Sacro-Coccygeal Ligament is a flat band of ligamentous fibres, 
of a pearly tint, which arises from the margin of the lower orifice of the sacral 
canal, and descends to be inserted into the posterior surface of the coccyx. This 
ligament completes the lower and back part of the sacral canal. Its superficial fibres 
are much longer than the deep-seated; the latter extend from the apex of the sacrum 
to the upper cornua of the coccyx. Anteriorly, it is in relation with the arach- 
noid membrane of the sacral canal, a portion of the sacrum, and almost the whole 
of the posterior surface of the coccyx; posteriorly, with some aponeurotic fibres 
from the Gluteus maximus. 

An Inter-articular Fibro-Cartilage is interposed between the contiguous sur- 
faces of the sacrum and coccyx ; it differs from that interposed between the bodies 
of the vertebrae, in being thinner, and its central part more firm in texture. It is 
somewhat thicker in front and behind, than at the sides. Occasionally a synovial 
membrane is found where the coccyx is freely movable, which is more especially 
the case during pregnancy. 

The different segments of the coccyx are connected together by an extension 
downwards of the anterior and posterior sacro-coccygeal ligaments, a thin annular 
disc of fibro-cartilage being interposed between each of the bones. In the adult 
male, all the pieces become ossified; but in the female, this does not commonly 
occur until a later period of life. The separate segments of the coccyx are first 
united, and at a more advanced age the joint between the sacrum and the 
coccyx. 

Actions. The movements which take place between the sacrum and coccyx, 
and between the different pieces of the latter bone, are slightly forwards and back- 
wards; they are very limited. Their mobility increases during pregnancy. 

4. Articulation of the Pubes. 
The articulation between the ossa pubis is an amphiarthrodial joint, formed by 
the junction of the two oval surfaces which have received the name of the sym- 
physis. The ligaments of this articulation are the 

Anterior Pubic. Posterior Pubic. 

Superior Pubic. Sub-Pubic. 

Inter-articular Fibro-Cartilage. 

The Anterior Pubic Ligament consists of several superimposed layers, which 
pass across the anterior surface of the articulation. The superficial fibres pass 
obliquely from one bone to the other, decussating and forming an interlacement 
with the fibres of the aponeurosis of the External oblique muscle. The deep 
fibres pass transversely across the symphysis, and are blended with the inter- 
articular fibro-cartilage. 

The Posterior Pubic Ligament consists of a few thin, scattered fibres, which 
unite the two pubic bones posteriorly. 

The Superior Pubic Ligament is a band of fibres, which connects together the 
two pubic bones superiorly. 

The Sub-Pubic Ligament is a thick, triangular arch of ligamentous fibres, con- 
necting together the two pubic bones below, and forming the upper boundary of 
the pubic arch. Above, it is blended with the • inter-articular fibro-cartilage; 
laterally, with the rami of the pubes. Its fibres are of a yellowish colour, closely 
connected, and have an arched direction. 



156 



ARTICULATIONS. 



The Inter-articular Fibro- Cartilage consists of two oval-shaped plates, one 
covering the surface of each symphysis pubis. They vary in thickness in 
different subjects, and project somewhat beyond the level of the bones, espe- 
cially behind. The outer surface of each is firmly connected to the bone by a 
series of nipple-like processes, which accurately fit within corresponding depres- 
sions on the osseous surface. Their opposed surfaces are connected, in the greater 
part of their extent, by an intermediate fibrous elastic-tissue; and by their cir- 
cumference to the various ligaments surrounding the joint. An interspace is left 
between the two plates at the upper and back part of the articulation, where the 

1 1 2. — Vertical Section of the Symphysis Pubis. 
Made near its Posterior Surface. 



Xii/o Fthiro-Ca/rtiiacjinoas jplntes 
Xnte/rmcdiate 
Sytimfuil cavity 




fibrous-tissue is deficient, and the surface of the fibro-cartilage lined by epithelium. 
This space is found at all periods of life, both in the male and female; but it is 
larger in the latter, especially during pregnancy, and after parturition. It is 
most frequently limited to the upper and back part of the joint; but it occasion- 
ally reaches to the front, and may extend the entire length of the cartilages. 
This structure may be easily demonstrated, by making a vertical section of the 
symphysis pubis near its posterior surface. 

The Obturator Ligament is a dense membranous layer, consisting of fibres 
which interlace in various directions. It is attached to the circumference of the 
obturator foramen, which it closes completely, except at its upper and outer part, 
where a small oval canal is left for the passage of the obturator vessels and nerve. 
It is in relation, in front, with the Obturator externus ; behind, with the Obtura- 
tor internus; both of which muscles are in part attached to it. 



ARTICULATIONS OF THE UPPER EXTREMITY. 

The articulations of the Upper Extremity may be arranged into the following 
groups: — I. Sterno-clavicular articulation. 2. Scapulo-clavicular articulation. 
3. Ligaments of the Scapula. 4. Shoulder-joint. 5. Elbow-joint. 6. Radio- 
ulnar articulation, 7. Wrist-joint. 8. Articulation of the Carpal bones. 9. 
Carpo-metacarpal articulation. 10. Metacarpo-phalangeal articulation. 1 1. Arti- 
culation of the Phalanges. 

I. Sterno-Clavicular Articulation. 

The Sterno-Clavicular is an arthrodial joint. The parts entering into its 
formation are the sternal end of the clavicle, the upper and lateral part of the 



STERNO-CLAVICULAR. 



157 



first piece of the sternum, and tile cartilage of the first rib. The articular surface 
of the clavicle is much longer than that of the sternum, and invested with a 



113. — Sterno-CIavicular Articulation. Anterior View. 




layer of cartilage, which is considerably thicker than that on the latter bone. 
The ligaments of this joint are the 



Anterior Sterno-CIavicular. 
Posterior Sterno-CIavicular. 
Inter- Clavicular. 



Costo-Clavicular (rhomboid). 
Inter- Articular Fibro-Cartilage. 
Two Synovial Membranes. 



The Anterior Sterno-CIavicular Ligament is a broad band of ligamentous 
fibres, which covers the anterior surface of the articulation, being attached, above, 
to the upper and front part of the inner extremity of the clavicle; and, passing 
obliquely downwards and inwards, is attached, below, to the front and upper part 
of the first piece of the sternum. This ligament is covered anteriorly by the 
sternal portion of the Sterno-cleido-mastoid and the integument; behind, it is in 
relation with the inter-articular fibro-cartilage and the two synovial membranes. 

The Posterior Sterno-CIavicular Ligament is a broad band of fibres, which 
covers the posterior surface of the articulation, being attached, above, to the pos- 
terior part of the inner extremity of the clavicle; and, passing obliquely down- 
wards and inwards, to be connected, below, to the posterior and upper part of the 
sternum. It is in relation, in front, with the inter-articular fibro-cartilage and 
synovial membranes; behind, with the Sterno-hyoid and Sterno-thyroid muscles. 

The Inter- Clavicular Ligament is a flattened ligamentous band, which varies 
considerably in form and size in different individuals; it passes from the superior 
part of the inner extremity of one clavicle to the other, and is closely attached to 
the upper margin of the sternum. It is in relation, in front, with the integu- 
ment; behind, with the Sterno-thyroid muscles. 

The Costo-Clavicular Ligament {rhomboid^ is a short, flat, and strong band of 
ligamentous fibres of a rhomboid form, attached, below, to the upper and inner 
part of the cartilage of the first rib; and, ascending obliquely backwards and out- 
wards,' to be attached, above, to the rhomboid depression on the under surface 
of the inner extremity of the clavicle. It is in relation, in front, with the tendon 
of origin of the Subclavius; behind, with the subclavian vein. 

The Inter- articular Fibro-Cartilage is a flat and nearly circular disc, inter- 
posed between the articulating surfaces of the sternum and clavicle. It is attached 
above, to the upper and posterior border of the clavicle; below, to the cartilage of 



158 AETICULATIONS. 

the first rib, at its junction with the sternum; and by its circumference to the 
anterior and posterior sterno-clavicular ligaments. It is thicker at the circum- 
ference, especially its upper and back pai't, than at its centre, or below. It 
divides the joint into two cavities, each of which is furnished with a separate 
synovial membrane; when the fibro-cartilage is perforated, which not unfrequently 
occurs, the synovial membranes communicate. 

Of the two Synovial Membranes found in this articulation, one is reflected over 
the sternal end of the clavicle, the adjacent surface of the fibro-cartilage, and 
cartilage of the first rib; the other is placed between the articular surface of the 
sternum and adjacent surface of the fibro-cartilage; the latter is the more loose of 
the two. TJtiey seldom contain much synovia. 

Actions. This articulation is the centre of the movements of the shoulder, and 
admits of motion in nearly every direction — upwards, downwards, backwards, 
forwards, as well as circumduction; the sternal end of the clavicle and the inter- 
articular cartilage gliding on the articular surface of the sternum. 

2. ScAPULO- Clavicular Articulation. 

The Scapulo- Clavicular is an arthrodial joint, formed between the outer 
extremity of the clavicle, and the upper edge of the acromian process of the 
scapula. Its ligaments are the 

Superior Acromio-Clavicular. 
Inferior Acromio-Clavicular, 

{Trapezoid 
and 
Conoid. 
Inter-articular Fibro-Cartilage. 
Two Synovial Membranes. 

The Superior Acromio-Clavicular Ligament is a broad band of fibres, of a 
quadrilateral form, which covers the superior part of the articulation, extending 
between the upper part of the outer end of the clavicle, and the superior part of 
the acromion. It is composed of parallel fibres, which interlace, above, with the 
aponeurosis of the Trapezius and Deltoid muscles; below, it is in contact with the 
inter-articular fibro-cartilage and synovial membranes. 

The Inferior Acromio-Clavicular Ligament, somewhat thinner than the pre- 
ceding, covers the inferior part of the articulation, and is attached to the adjoining 
surfaces of the two bones. It is in relation, above, with the inter-articular fibro- 
cartilage (when it exists) and the synovial membranes; below, with the tendon of 
the Supra- spinatus. These two ligaments are continuous with each other in front 
and behind, and form a complete capsule around the joint. 

The Coraco- Clavicular Ligament serves to connect the clavicle with the 
coracoid process of the scapula. It consists of two distinct fasciculi, which have 
received separate names. 

The Trapezoid Ligament, the anterior and external fasciculus, is a broad, thin, 
quadrilateral-shaped band of fibres, placed obliquely between the acromian process 
and the clavicle. It is attached, below, to a rough line at the inner and back 
part of the upper surface of the coracoid process; above, to the oblique line on 
the under surface of the clavicle. Its anterior border is free; its posterior is 
joined with the conoid ligament, forming by their junction a projecting angle. 

The Conoid lAgament, the posterior and internal fasciculus, is a dense band of 
fibres, conical in form, the base being turned upwards, the summit downwards. 
It is attached by its apex to a rough depression at the anterior and inner side of 
the base of the coracoid process, internal to the preceding; above, by its expanded 
base, to the rough tubercle on the under surface of the clavicle. These ligaments 
are in relation, in front, with the Subclavius; behind, with the Trapezius: they 
serve to limit rotation of the scapula forwards and backwards. 



PROPER LIGAMENTS OF SCAPULA. 



159 



The Inter- articular Fibro- Cartilage is most frequently absent in this articula- 
tion. When it exists, it generally only partially separates the articular surftxces, 
and occupies the upper part of the articulation. More rarely, it completely sepa- 
rates this joint into two cavities. 

114. — The Left Shoulder- Joint, Scapulo-Clavicular Articulations, 
and Proper Ligaments of Scapula. 




There are tico Synovial Membranes where a complete inter-articular cartilage 
exists; more frequently there is only one synovial membrane. 

Actions. The movements of this articulation are of two kinds. I. A gliding 
motion of the articular end of the clavicle on the acromion. 2. Rotation of the 
scapula forwards and backwards upon the clavicle, the extent of this rotation being 
limited by the two portions of the coraco-clavicular ligament. 



3. Proper Ligaments of the Scapula. 

The proper ligaments of the scapula are the 

Coraco-acromial. Transverse (Coracoid). 

The Coraco-acromial Ligament is a broad, thin, and flat band, of a triangular 
shape, extended transversely across the upper part of the shoulder-joint, between 
the coracoid process and the acromion. It is attached by its apex to the summit 
of the acromion just in front of the articular surface for the clavicle, and by its 
broad base to the whole length of the outer border of the coracoid process. Its 
posterior fibres are directed obliquely backwards and outwards, its anterior fibres 
transversely. This ligament completes the vault formed by the acromion and cora- 
coid processes for the protection of the head of the humerus. It is in relation, 
above, with the clavicle and under surface of the deltoid ; below, with the tendon of 



i6o ARTICULATIONS. 

the Supra- spinatus itmscle, a bursa being interposed. Its anterior border is con- 
tinuous with a dense cellular lamina that passes beneath the deltoid upon the 
tendons of the Supra- and Infra-spinati muscles. 

The Transverse or Coracoid Ligament, is a thin and flat fasciculus, narrower 
at the middle than at the extremities, attached by one end to the base of the cora- 
coid process, and by the other, to the inner extremity of the scapular notch, which 
it converts into a foramen. The supra- scapular nerve passes through this foramen, 
its accompanying vessels above it. 

4. Shoulder Joint. 

The Shoulder is an enarthrodial or ball and socket joint. The bones en- 
tering into its formation are the large globular head of the humerus, which is 
received into the shallow glenoid cavity of the scapula, an arrangement which 
permits of very considerable movement, whilst the joint itself is protected against 
displacement by the strong ligaments and tendons which surround it, and above by 
an arched vault, formed by the under surface of the coracoid and acromion processes, 
and the coraco-aci'omion ligament. The two articular surfaces are covered by a 
layer of cartilage, which on the head of the humerus is thicker at the centre than 
at the circumference, the reverse being observed in the glenoid cavity. Its liga- 
ments are the 

Capsular. Glenoid. 

Coraco-humeral. Synovial Membrane. 

The Capsular Ligament completely encircles this articulation; being attached, 
above, to the circumference of the glenoid cavity beyond the glenoid ligament; below, 
to the margin of the neck of the humerus, approaching nearer to the articular carti- 
lage above, than in the rest of its extent. It is thicker above than below, remark- 
ably loose and lax, and much larger and longer than is necessary to keep the bones 
in contact, allowing them to be separated from each other more than an inch, an 
evident provision for that extreme freedom of movement which is peculiar to 
this articulation. Its external surface is strengthened above by the Supra spi- 
natus; above and internally by the coraco-humeral ligament; below, where it is 
thin and weak, the long tendon of the Triceps is separated from it by a little loose 
areolar tissue; externally the tendons of the Infra- spinatus and Teres minor are 
firmly attached to it; and internally, the tendon of the Sub-scapularis. The cap- 
sular ligament usually presents three openings; one at its inner side, partially 
filled up by the tendon of the Sub-scapularis; it establishes a communication be- 
tween the synovial membrane of the joint, and a bursa beneath the tendon of that 
muscle; a second, not constant, at its external part, where a communication 
exists between the joint and a bursal sac belonging to the Infra- spinatus muscle. 
The third is seen in the lower border of the ligament, between the two tuberosities, 
for the passage of the tendon of the Biceps muscle. 

The Coraco-humeral or Accessory Ligament, is a broad band which strengthens 
the upper and inner part of the capsular ligament. It arises from the outer border 
of the coracoid process, and descends obliquely downwards and outwards to the 
anterior part of the great tuberosity of the humerus, being blended with the tendon 
of the Supra-spinatus muscle. This ligament is intimately united to the capsular 
in the greater part of its extent. 

The Glenoid Ligament is a fibro-cartilaginous band attached around the margin 
of the glenoid cavity. It is triangular on section, the thickest portion being fixed to 
the circumference of the cavity, the free edge being thin and sharp. It appears 
to be mainly formed of the fibres of tlae long tendon of the Biceps muscle, bifur- 
cating at the upper part of the glenoid cavity into two fasciculi, which encircle 
its margin and unite at its lower part. This ligament deepens the cavity for articu- 
lation, and protects the edges ofthe bone. It is lined by the synovial membrane. 

The Synovial Membrane lines the glenoid cavity and the fibro-cartilaginous rim 



I 



ELBOW JOINT. 



i6i 



surrounding it; it is then reflected over the internal surface of the capsular liga- 
ment, lines the lower part and sides of the neck of the humerus, and is con- 
tinued over the cartilage covering the head of this bone. The long tendon of the 
Biceps muscle which passes through the joint, is enclosed in a tubular sheath of 
synovial membrane, which is reflected upon it at the point where it perforates the 
capsule, and is continued around it as far as the summit of the glenoid cavity, 
where it is continuous with that portion of the membrane which covers its surface. 
The tendon of the Biceps is thus enabled to traverse the articulation, but is not 
contained in the interior of the synovial cavity. The synovial membrane commu- 
nicates with a large bursal sac beneath the tendon of the Sub-scapularis, by an 
opening at the inner side of the capsular ligament; it also occasionally communi- 
cates with another bursal sac, beneath the tendon of the Infra-spinatus, through an 
orifice Tit its upper part. A third bursal sac, which does not communicate with 
the joint is placed between the under surface of the deltoid and the outer surface 
of the capsule. 

The Muscles in relation with this joint are, above, the Supra-spinatus; below, 
the long tendon of the Triceps; internally, the Sub-scapularis; externally, the Infra- 
spinatus and Teres minor; within, the long tendon of the Biceps. The Deltoid is 
placed most externally, and covers the articulation on its outer side, and in front 
and behind. 

The Arteries supplying this joint are articular branches of the anterior and 
posterior circumflex, and supra- scapular. 



The Nerves are dei'ived from the cir- 
cumflex and supra-scapular. 

Actions. The shoulder joint is capable 
of movement in almost any direction, for- 
wards, backwards, abduction, adduction, 
circumduction, and rotation. 

5. Elbow Joint. 

The Elbow is a gi?igli/nioid or hinge 
joint. The bones entering into its forma- 
tion are the trochlear surface of the 
humerus, which is received in the greater 
sigmoid cavity of the ulna, and admits 
of the movements peculiar to this joint, 
those of flexion and extension, whilst the 
cup-shaped depression of the head of the 
radius articulates with the radial tubero- 
sity of the humerus, its circumference Avith 
the lesser sigmoid cavity of the ulna, al- 
lowing of the movement of I'otation of the 
radius on the ulna, the chief action of the 
superior radio-ulnar articulation. These 
various articular surfaces are covered with 
a thin layer of cartilage, and connected 
together by the following ligaments. 

Anterior Ligament. 
Posterior Ligament. 
Internal Lateral. 
External Lateral, 
Synovial Membrane. 

The Anterior Ligament (fig. 115) is a 
broad and thin membranous layer, which 
covers the anterior surface of the joint. 
It is attached to the humerus immediately 



1 1 5. — Left Elbow- Joint, showing Anterior 
and Internal Ligaments. 




1 62 



ARTICULATIONS. 



1 1 6. — Left Elbow-Joint, shewing Pos- 
terior and External Licraments. 



above the coronoid fossa; below, to the anterior surface of the coronoid process of 
the ulna and orbicular ligament, being continuous on each side with the lateral 
ligaments. Its superficial or oblique fibres pass from the internal tuberosity of 
the humerus outwards to the orbicular ligament. The middle fibres, vertical 
in direction, pass from the upper part of the coronoid depression, and become 
blended with the preceding. A third, or transverse set, intersect these at right 
angles. This ligament is in relation, in front, with the Brachialis anticus; behind, 
with the synovial membrane. 

The Posterior Ligament is a thin and loose membranous fold, attached, above, 
to the lower end of the humerus, immediately above the olecranon depression; 
below, to the margin of the olecranon. The superficial or transverse fibres pass 
between the adjacent margins of the olecranon fossa. The deeper portion consists 
of vertical fibres, which pass from the upper pa^rt of the olecranon fossa to the 
margin of the olecranon. This ligament is in relation, behind, with the tendon of 
the Triceps and Anconeus; in front, with the synovial membrane. 

The Internal Lateral I^igament is a thick triangular band of ligamentous 
fibres, consisting of two distinct portions, an anterior and posterior. The ante- 
rior portion, directed obliquely forwards, is attached, above, by its apex, to 
the front part of the internal condyle of the humerus; and, below, by its broad 
base to the inner margin of the coronoid process. The posterior portion, also of 
triangular form, is attached, above, by its apex to the lower and back part of the 
internal condyle; below, to the inner margin of the olecranon. This ligament is 
in relation, internally, with the Triceps and Flexor carpi ulnaris muscles and the 
ulnar nerve. 

The External Lateral lAgament (fig. 1 1 6) is a short and narrow fibrous fasci- 
culus, less distinct than the internal, attached, 
above, to the external condyle of the hume- 
rus; below, to the orbicular ligament, some 
of its most posterior fibres passing over that 
ligament to be inserted into the outer margin 
of the greater sigmoid cavity. This ligament 
is intimately blended with the tendon of origin 
of the Supinator brevis muscle. 

The Synovial Membrane is very extensive. 
It covers the articular surface of the humerus, 
and lines the coronoid and olecranon depres- 
sions on that bone ; from these points, it is 
reflected over the anterior, posterior and lateral 
ligaments; lines the greater sigmoid cavity, the 
concave depression on the head of the radius; 
and forms a pouch between the lesser sigmoid 
cavity, the internal surface of the annular liga- 
ment, and the circumference of the radius. 

The Muscles in relation with this joint are, 
in front, the Brachialis anticus; behind, the 
Triceps and Anconeus; externally, the Supina- 
tor brevis, and the common tendon of origin of 
the Extensor muscles; internally, the common 
tendon of origin of the Flexor muscles, the 
Flexor carpi ulnaris, and ulnar nerve. 

The Arteries supplying this joint are derived 
from the communicating branches between the 
superior profunda, inferior profunda, and ana- 
stomatic branches of the Brachial, with the 
anterior, posterior and interosseous recurrent 
branches of the Ulnar, and the recurrent branch 
of the Radial. These vessels form a complete 
chain of inosculation around this joint. 




RADIO-ULNAR. 163 

The Nerves are derived from the ulnar, as it passes between the internal condyle 
and the olecranon. 

Actio?is. The elbow is one of the most perfect hinge-joints in the body; its 
movements are consequently limited to flexion and extension, the exact apposition 
of the articular surfaces preventing the least lateral motion. The movement of 
flexion is limited by the coronoid process, and that of extension by the olecranon 
process. 

6. Radio-Ulnar Articulations. 

The articulation of the radius with the ulna is effected by ligaments, which 
connect together both extremities as well as the centre of these bones. They may, 
consequently, be subdivided into three sets: I, the superior radio-ulnar; 2, the 
middle radio-ulnar; and, 3, the inferior radio-ulnar articulations. 

1. Superior Radio-Ulnar Articulation. 

This articulation is a lateral ginglymoid joint. The bones entering into its 
formation are the inner side of the circumference of the head of the radius, which 
is received into the lesser sigmoid cavity of the ulna. These surfaces are covered 
with cartilage, and invested with a duplicature of synovial membrane, continuous 
with that which lines the elbow-joint. Its only ligament is 

The Annular or Orbicular. 

The Orbicular Ligament {^g. II 6) is a strong flat band of ligamentous fibres, which 
surrounds the head of the radius, and retains it in firm connection with the lesser 
sigmoid cavity of the ulna. It forms about three-fourths of a fibrous ring, attached 
by each end to the extremities of this cavity, and is broader at the upper part of 
its circumference than below, which serves to hold the head of the radius more 
securely in its position. Its outer surface is strengthened by the external lateral 
ligament, and affords partial origin to the Supinator brevis mwscle. Its internal 
surface is smooth, and lined by the synovial membrane of the elbow-joint. 

Actions. The movement which takes place in this articulation is limited to rota- 
tion of the inner part of the head of the radius within the orbicular ligament, and 
upon the lesser sigmoid cavity of the ulna; rotation forwards being called prona- 
tion; rotation backward, supination. 

2. Middle Radio-Ulnar Articulation. 

The interval between the radius and ulna in the middle of the forearm is occu- 
pied by two ligaments. 

Oblique. Interosseous. 

The Oblique or Round Ligament (fig. 115) is a small round fibrous cord, which 
extends obliquely downwards and outwards, from the tubercle of the ulna at the 
base of the coronoid process, to the radius a little below the bicipital tuberosity. 
Its fibres run in the opposite direction to those of the interosseous ligament; and 
it appears to be placed as a substitute for it in the upper part of the interosseous 
interval. 

The Interosseous Ligament is a broad and thin plane of aponeurotic fibres, de- 
scending obliquely downwards and inwards, from the interosseous ridge on the 
radius to that on the ulna. It is deficient above, commencing about an inch be- 
neath the tubercle of the radius; broader in the middle than at either extremity; 
and presents an oval aperture just above its lower margin for the passage of the 
anterior interosseous vessels to the back of the forearm. This ligament serves to 
connect the bones, and to increase the extent of surface for the attachment of the 
deep muscles. Between its upper border and the oblique ligament an interval 
exists, through which the posterior interosseous vessels pass. Two or three fibrous 
bands are occasionally found on the posterior surface of this membrane, which 

M 2 



1 64 ARTICULATIONS. 

descend obliquely from the ulna towards the radius, and which have consequently 
a direction contrary to that of the other fibres. It is in relation, in front, by its 
upper three-fourths (radial margin) with the Flexor longus pollicis (ulnar margin), 
with the Flexor profundus digitorum (lying upon the interval between which are 
the anterior interosseous vessels and nerve), by its lower fourth with the Pronator 
quadratus; behind, with the Supinator brevis. Extensor ossis metacarpi pollicis, 
Extensor primi internodii pollicis. Extensor secundi internodii pollicis. Extensor 
indicis; and, near the wrist, with the anterior interosseous artery and posterior 
interosseous nerve. 

3. Inferior Radio-Ulnar Articulation. 

This is a lateral ginglymoid joint, formed by the head of the ulna being received 
into the sigmoid cavity at the inner side of the ' lower end of the radius. The 
articular surfaces are invested by a thin layer of cartilage, and connected together 
by the following ligaments. 

Anterior radio-ulnar. 
Posterior radio-ulnar. 

Triangular Inter-articular Fibro-cartilage. 
, Synovial Membrane. 

The Anterior Radio-ulnar Ligament (fig. 117) is a narrow band of fibres, ex- 
tending from the anterior margin of the sigmoid cavity of the radius to the ante- 
rior surface of the head of the ulna. 
Q\ The Posterior Radio-ulnar Ligament (ijg. 118) extends between the same 

points on the posterior surface of the articulation. 

The Lnter-articular Fibro-cartilage (fig. i ig^-is a thick fibro-cartilaginous lamella, 
of a triangular form, placed transversely, completing the wrist-joint, and binding 
the lower ends of the radius and ulna firmly together. Its circumference is more 
dense than its centre, which is thin and occasionally perforated; and it is thinner 
and broader extei^ially than internally. It is attached by its apex to a depres- 
sion which separates the styloid process of the ulna from the head of that bone; 
by its base, which is thin, to the prominent edge of the radius, which sepa- 
rates the sigmoid cavity from the carpal articulating surface, and by its anterior 
and posterior margins to the ligaments of the radio-carpal articulation. Its 
upper surface, smooth and concave, is contiguous with the head of the ulna; its 
under surface, also concave and smooth, with the cuneiform bone. Both surfaces 
are lined by a synovial membrane: the superior surface, by one peculiar to the 
radio-ulnar ^.rticulation ; the inferior surface, by the synovial membrane of the 
wrist. 

The Synovial Membrane of this articulation has been called, from its extreme 
looseness, the membrana sacciformis; it covers the articular surface of the head 
of the ulna, and where reflected from this bone on to the radius, forms a very loose 
cul-de-sac; from the radius it is continued over the upper surface, of the fibro- 
cartilage. The quantity of synovia which it contains is usually considerable. 
When the fibro-cartilage is perforated, this synovial membrane is continuous with 
that which lines the wrist-joint. 

Actions. The movement which occurs in .the inferior radio-ulnar articulation is 
just the inverse of that which takes place between the two bones above; it is limited 
to rotation of the radius around the head of the nlna; rotation forwards being 
termed pronation, rotation backwards supination. In pronation, the sigmoid cavity 
glides forward on the articular edge of the ulna; in supination, it rolls in the 
opposite direction, the extent of these movements being limited by the anterior 
and posterior ligaments. 

7. Wrist Joint. 

The Wrist presents most of the characters of an enarthrodial joint. The parts 
entering into its formation are the lower end of the radius, and under surface 



WRIST JOINT. 



165 



of the triangular interarticular fibro-cartilage, above; and the scaphoid, eomilunar, 
and cuneiform bones below. The articular surfaces of the radius and interarticular 

117. — Ligaments of Wrist and Hand. Anterior View. 




INFERIOR RADIO-Ui-NAR ARTIC" 



WRIST-JOiNT 



CARPAL ARTICJ? 



CARPO-METACARPAL ARTIC ' 



fibro-cartilage form a transversely elliptical concave surface. The radius is sub- 
divided into two parts by a line extending from before backwards; and these, 
together with the interarticular cartilage, form three facets, one for each carpal 



1 18. — Ligaments of Wrist and Hand. Posterior View. 




Carp o-MMctcaimal /y j 



bone. The three carpal bones are connected together, and form a rounded convex 
surface, which is received into the cavity above mentioned. All the bony surfaces 



1 66 ARTICULATIONS. 

of this articulation are covered with cartilage, and connected together by the 
following ligaments. 

External Lateral. Anterior. 

Internal Lateral. Posterior. 

Synovial Membrane. 

The External Lateral Ligament extends from the summit of the styloid pro- 
cess of the radius to the outer side of the scaphoid, some of its fibres being 
prolonged to the trapezium and annular ligament. 

The Internal Lateral Ligament is a rounded cord, attached, above, to the ex- 
tremity of the styloid process of the ulna; below, it divides into two fasciculi, 
which are attached, one to the inner side of the cuneiform bone, the other to the 
pisiform bone and annular ligament. 

The Anterior Ligament is a broad membranous band, consisting of three fasci- 
culi, attached, above, to the anterior margin of the lower end of the radius, its 
styloid process, and the ulna; its fibres pass downwards and inwards, to be 
inserted into the anterior surface of the scaphoid, semilunar, and cuneiform bones. 
This ligament is perforated by numerous apertures for the passage of vessels, and 
is in relation, in front, with the tendons of the Flexor profundus digitorum and 
Flexor longus pollicis; behind, with the synovial membrane of the wrist-joint. 

The Posterior Ligament, less thick and strong than the anterior, is attached, 
above, to the posterior border of the lower end of the radius; its fibres descend 
obliquely downwards and inwards to be attached to the posterior surface of the 
scaphoid, semilunar, and cuneiform bones, its fibres being continuous with those 
of the dorsal carpal ligaments. This ligament is in relation, behind, with the 
extensor tendons of the fingers; in front, with the synovial membrane of the 
wrist. 

The Synovial Membrane lines the lower end of the radius and under surface of 
the triangular inter-articular fibro-cartilage above; and being reflected on the 
inner surface of the ligaments above mentioned, covers the convex surface of the 
scaphoid, semilunar, and cuneiform bones below. 

Relations. The wrist-joint is covered in front by the flexor, and behind by the 
extensor tendons; it is also in relation with the radial and ulnar arteries. 

The Arteries supplying this joint are the anterior and posterior carpal branches 
of the Radial and Ulnar, the anterior and posterior interosseous, and some 
ascending branches from the deep palmar arch. 

The Nerves are derived from the posterior interosseous. 

Actions. The movements permitted in this joint are flexion, extension, abduc- 
tion, adduction, and circumduction. It is totally incapable of rotation, one of the 
characteristic movements in true enarthrodial joints. 

8. Articulations of the Carpus. 
These articulations may be subdivided into three sets. 

1. The articulation of the first row of carpal bones. 

2. The articulation of the second row of carpal bones. 

3. The articulation of the two rows with each other. 

I. Articulation of the First Row of Carpal Bones. 

These are arthrodial joints. The articular surfaces are covered with cartilage, 
and connected together by the following ligaments. 

Two Dorsal. Two Palmar. 

Two Interosseous. 

The Dorsal Ligaments, two in number, are placed transversely behind the bones 
of the first row; they connect the scaphoid and semilunar, and the semilunar and 
■ cuneiform. 

The Palmar Ligaments, also two in number, connect the scaphoid and semi- 



I 



OF THE CARPUS. 167 

lunar, and the semilunar and cuneiform bones; they are less strong than the dorsal, 
and placed very deep under the anterior ligament of the wrist. 

The Interosseous Ligaments (fig. 1 19) are two narrow bundles of dense fibrous 
tissue, connecting the semilunar bone, on one side with the scaphoid, on the other 
with the cuneiform bone. They close the upper part of the interspaces between 
the scaphoid, semilunar, and cuneiform bones, their upper surfaces being smooth, 
and lined by the synovial membrane of the wrist-joint. 

The articulation of the pisiform with the cuneiform is provided with a separate 
synovial membrane, protected by a thin capsular ligament. There are also two 
strong fibrous fasciculi, which connect this bone to the unciform, and base of the 
fifth metacarpal bone. 

2. Articulation of the Second Row or Carpal Bones. 

These are also arthrodial joints, the articular surfaces being covered with carti- 
lage, and connected by the following ligaments. 

Three Dorsal. Three Palmar. 

Two Interosseous. 

The three Dorsal Ligaments extend transversely from one bone to another on 
the dorsal surface, connecting the trapezium with the trapezoid, the trapezoid with 
the OS magnum, and the os magnum with the unciform. 

The three Palmar Ligaments have a similar arrangement on the palmar surface. 

The tioo Interosseous Ligaments, much thicker than those of the first row, are 
placed one on each side of the os magnum, connecting it with the trapezoid exter- 
nally, and the unciform internally. The former is less distinct than the latter. 

3. Articulation of the Two Rows of Carpal Bones with each other. 

The articulation between the two rows of the carpus consists of an enarthrodial 
joint in the middle, formed by the reception of the os magnum into a cavity 
formed by the scaphoid and semilunar bones, and of an arthrodial joint on each 
side, the outer one formed by the articulation of the scaphoid with the trapezium 
and trapezoid, the internal one by the articulation of the cuneiform and unciform. 
The articular surfaces are covered by a thin layer of cartilage, and connected by 
the following ligaments. 

Anterior or Palmar. External Lateral. 

Posterior or Dorsal. Internal Lateral. 

Synovial Membranes. 

The Anterior or Palmar Ligaments consist of short fibres, which pass obliquely 
between the bones of the first and second row on the palmar surface. 

The Posterior or Dorsal Ligaments have a similar arrangement on the dorsal 
surface of the carpus. 

The Lateral Ligaments are very short; they are placed, one on the radial, the 
other on the ulnar side of the carpus; the former, the stronger and more distinct, 
connecting the scaphoid and trapezium bones, the latter the cuneiform and unci- 
form: they are continuous with the lateral ligaments of the wrist-joint. 

There are two Synovial Membranes found in the articulation of the carpal 
bones with each other. The first of these, the more extensive, lines the under 
surface of the scaphoid, semilunar, and cuneiform bones, sending upwards two 
prolongations between their contiguous surfaces; it is then reflected over the 
bones of the second row, and sends down three prolongations between them, which 
line thfeir contiguous surfaces, and invest the carpal extremities of the four outer 
metacarpal bones. The second is the synovial membrane between the pisiform 
and cuneiform bones. 

Actions. The partial movement which takes place between the bones of each 
row is very inconsiderable; the movement between the two rows is more marked, 
but limited chiefly to flexion and extension. 



1 68 



ARTICULATIONS. 



9. Carpo Metacarpal Articulations. 

Articulation of the First Metacarpal Bone with the Trapezium. 

This is an enarthrodial joint. Its ligaments are a capsular and synovial mem- 
brane. The capsular ligament is a thick but loose capsule, which passes from 
the circumference of the upper extremity of the metacarpal bone, to the rough 
edge bounding the articular surface of the trapezium; it is thickest externally and 
behind, and lined by a separate synovial membrane. 

Articulation of the Four inner Metacarpal Bones with the Carpus. 

The joints formed between the carpus and four inner metacarpal bones, are con- 
nected together by dorsal, palmar, and interosseous ligaments. 

The Dorsal Ligaments, the strongest and most distinct, connect the carpal and 
metacarpal bones on their dorsal surface. The second metacarpal bone receives 
two fasciculi, one from the trapezium, the other from the trapezoid; the third me- 
tacarpal receives one from the os magnum; the fourth two, one from the os mag- 
num, and one from the unciform; the fifth receives a single fasciculus from the 
imciform bone. 

The Palmar Ligaments have a somewhat similar arrangement on the palmar 
surface, with the exception of the third metacarpal, which has three ligaments, an 
external one from the trapezium, situated above the sheath of the tendon of the 
Flexor carpi radialis ; a middle one, from the os magnum ; and an internal one, from 
the unciform. 

The Interosseous Ligaments consist of short thick fibres, which are limited to 
one part of the carpo-metacarpal articulation; they connect the inferior angles of 
the OS magnum and unciform, with the adjacent surfaces of the third and fourth 
metacarpal bones. 

The Synovial 3Iembrane is a continuation of that between the two rows of 
carpal bones. Occasionally the unciform has a separate synovial membrane, lining 
it and the fourth and fifth metacarpal bones. 

The Synovial Membranes of the wrist (fig. 119) are thus seen to be five in 

119. — Vertical Section through the Articulations at the Wrist, showing the five 
Synovial Membranes. 




CARPO-METACARPAL AND METACARPO-PHALANGEAL. 169 

number. The first, the membrana sacciformis, lining the lower end of the ulna, 
the sigmoid cavity of the radius, and upper surface of the triangular inter-articular 
iibro-cartilage. The second lines the lower end of the radius and inter-articular 
fibro-cartilage above, and the scaphoid, semilunar, and cuneiform bones below. The 
third, the most extensive, covers the contiguous surfaces of the two rows of carpal 
bones, and passing between the bones of the second range, lines the carpal extre- 
mities of the four inner metacarpal bones. The fourth lines the adjacent sur- 
fiices of the trapezium and metacarpal bone of the thumb. And the fifth the 
adjacent surfaces of the cuneiform and pisiform bones. 

Actions. The movement permitted in the carpo-metacarpal articulations is limited 
to a slight gliding of the articular surfaces upon each other, the extent of which 
varies in the diiFerent joints. Thus the articulation of the metacarpal bone of the 
thumb with the trapezium is most moveable, then the fifth metacarpal, and then 
the fourth. The second and third are almost immoveable. In the articulation of 
the metacarpal bone of the thumb with the trapezium, the movements permitted 
are flexion, extension, adduction, abduction, and circumduction. 

Articulation of the Metacaepal Bones with each other. 

The carpal extremities of the metacarpal bones of the fingers, articulate with 
one another at each side by small surfaces covered with cartilage, and connected 
together by dorsal, palmar, and interosseous ligaments. 

The Dorsal or Palmar Ligaments pass transversely from one bone to another 
on the dorsal and palmar surfaces. The Interosseous Ligaments passing between 
their contiguous surfaces, just beneath their lateral articular facets. 

The Synovial Membrane lining the lateral facets, is a reflection of that between 
the two rows of carpal bones. 

The digital extremities of the metacarpal bones of the fingers, are connected 
together by the transverse ligament, a narrow fibrous band, passing transversely 
across their under surfaces, and blended with the ligaments of the metacarpo-pha- 
langeal articulations. Its anterior surface presents four grooves for the passage 
of the flexor tendons, and its sides are continuous with their sheaths. Its poste- 
rior surface blends with the ligaments of the metacarpo-phalangeal articulation. 

10. Metacarpo-phalangeal Articulations (fig. 120). 

These ai-ticulations are of the ginglymoid kind, formed by the reception of each 
of the rounded heads of the metacarpal bones of the four fingers, into a superficial 
cavity in the extremity of the first phalanges. They are connected by the fol- 
lowing ligaments, 

Anterior. Two Lateral. 

Synovial Membrane. 

The Anterior Ligaments are very thick and dense, they are placed on the 
palmar surface of the joint in the interval between the lateral ligaments, to which 
they are connected; they are loosely united to the metacarpal bone, but very 
firmly to the base of the first phalanges. Their palmar surface is intimately 
united to the transverse ligament, each ligament forming with it a groove for the 
passage of the flexor tendons, the sheath surrounding which is connected to it at 
each side. By their internal surface they form part of the articular surface for 
the head of the metacarpal bone, and are lined by a synovial membrane. 

The Lateral Ligaments are thick and strong rounded cords, placed one on each 
side of the joint, attached by one extremity to the sides of the head of the meta- 
carpal bones, and by the other, to the contiguous extremity of the phalanges. 

The Posterior Ligament is supplied by the extensor tendon of the fingers placed 
over the back of each joint. 

Actions. The movements which occur in these joints are flexion, extension, 
adduction, abduction, and circumduction ; the lateral movements are very limited. 



170 



ARTICULATIONS. 



LATERAL LICAMCNT- 



Metacar^o - jJuvla.Tic/ml 



1 1 . Articulations of the Phalanges. 
These are ginglymoid joints, connected by the following ligaments; 

120.— Articulations of the Phalanges. ;^"*^ x^^/ . 

iwo Lateral. 

Synovial Membrane. 

The arrangement of these liga- 
ments is similar to those in the 
preceding articulations; the exten- 
sor tendon supplies the place of a 
posterior ligament. 

Actions. The only movements 
permitted in the phalangeal joints 
are flexion and extension; these 
movements are more extensive be- 
tween the first and second phalanges 
than between the second and third. 
The movement of flexion is very ex- 
tensive, but extension is limited by 
the anterior and lateral ligaments. 

ARTICULATIONS OF THE 
LOWER EXTREMITY. 

'The articulations of the lower 
extremity comprise the following 
groups. I. The hip joint. 2. The 
knee joint. 3. The articulations 
between the tibia and fibula. 
4. The ankle joint. 5. The arti- 
culations of the tarsus. 6. The 
tarso-metatarsal articulations. 7. 
The metatarso phalangeal articula- 
tions. 8. The articulation of the 
phalanges. 

I. Hip Joint, (fig. 121). 

This articulation is an enarthro- 
dial, or ball and socket joint, formed by the reception of the globular head of 
the femur into the cup-shaped cavity of the acetabulum. These two articulating 
surfaces are covered with cartilage, that on the head of the femur being thicker 
at the centre than at the circumference, and covering the entire surface with the 
exception of a depi-ession just below its centre for the ligamentum teres; that 
covering the acetabulum is much thinner at the centre than at the circumference, 
and is deficient in the situation of the circular depression at the bottom of this 
cavity. The ligaments of this joint are the • 

Capsular. Cotyloid. 

Uio-femoral. Transverse. 

Teres. Synovial Membrane. 

The Capsular Ligament is a strong, dense, ligamentous capsule, embracing the 
margin of the acetabulum above, and surrounding the neck of the femur below. 
Its upper circumference is attached to the acetabulum two or three lines extei'nal 
to the cotyloid ligament; but opposite the notch where the margin of this cavity 
is deficient, it is connected with the transverse ligament, and by a few fibres to the 
edge of the obturator foramen. Its lower circumference surrounds the neck of 




PJi eoTa,ji (f eal 

Artie Vf 



HIP JOINT. 



171 



the femur, being attached, in front, to the spiral or anterior inter-trochanteric line; 
above, to the base of the neck; behind, to the middle of the neck of the bone, 
about thi'ee quarters of an inch from the posterior inter-trochanteric line. It is 



izi. — Left Hip Joint laid open. 




much thicker at the upper and anterior part of the joint where the greatest amount 
of resistance is required, than below, where it is thin, loose, and longer than in 
any other situation. Its external surface is rough, covered by numerous muscles, 
and separated in front from the Psoas and Iliacus by a synovial bursa, which not 
unfrequently communicates by a circular aperture with the cavity of the joint. It 
differs from the capsular ligament of the shoulder, in being much less loose and 
lax, and in not being perforated for the passage of a tendon. 

The Ilio-femoral Ligament (fig. no) is an accessory band of fibres, extending 
obliquely across the front of the joint: it is intimately connected with the capsular 
ligament, and serves to strengthen it in this situation. It is attached above to the 
anterior inferior spine of the ilium, below, to the anterior inter-trochanteric line. 

The Ligamentum Teres is a flat triangular band of fibres, implanted by its 
apex into the depression just below the middle of the head of the femur, and by 
its broad base, which consists of two bundles of fibres, into the margins of the 
notch at the bottom of the acetabulum, becoming blended with the transverse 
ligament. It is formed of a bundle of fibres, the thickness and strength of which 
is very variable, surrounded by a tubular sheath of synovial membrane. Some- 
times the synovial fold only exists, or the ligament may be altogether absent. 

The Cotyloid Ligament is a fibro-cartilaginous rim attached to the margin of the 
acetabulum, the cavity of which it deepens, at the same time it protects the edges 
of the bone, and fills up the inequalities on its surface. It is prismoid in form, its 
base being attached to the margin of the acetabulum, its opposite edge being free 
and sharp; whilst its two surfaces are invested by synovial membrane, the external 



172 



ARTICULATIONS. 



one being in contact with the capsular ligament, the internal being inclined inwards 
so as to narrow the acetabulum and embrace the cartilaginous surface of the head 
of the femur. It is much thicker above and behind than below and in front, and 
consists of close, compact fibres, which arise from different points of the circum- 
ference of the acetabulum, and interlace with each other at very acute angles. 

The Transverse Ligament is a strong flattened band of fibres, which crosses 
the notch at the lower part of the acetabulum, and converts it into a foramen. It 
is continuous at each side with the cotyloid ligament, and consists of fibres which 
arise from each side of the notch, and pass across each other. An interval is left 
beneath this ligament for the passage of nutrient vessels to the joint. 

The Synovial Membrane is very extensive. It invests the cartilaginous sur- 
face of the head of the femur, and all that portion of the neck which is contained 
within the joint; from this point it is reflected on the internal surface of the cap- 
sular ligament, covers both surfaces of the cotyloid ligament, and lines the cavity 
of the acetabulum, covers the mass of fat contained in the fossa at the bottom of 
this cavity, and is prolonged in the form of a tubular sheath around the liga- 
nientum teres on to the head of the femur. 

The Muscles in relation with this joint are, in front, the Psoas and Iliacus, 
separated from the capsular ligament by a synovial bursa; above, the short head of 
the Rectus and Gluteus minimus, the latter being closely adherent to it; internally, 
the Obturator externus and Pectineus; behind, the Pyriformis, G-emellus superior, 
Obturator internus. Gemellus inferior. Obturator externus, and Quadratus femoris. 

The Arteries supplying it are derived from the obturator, sciatic, internal cir- 
cumflex, and gluteal. 

The Nerves are articular branches from the sacral plexus, great sciatic, obtu- 
rator, and accessory obturator nerves. 

Actions. The movements of 

122. — Eight Knee Joint. 



the hip, like all enarthrodial 
joints, are very extensive; they 
are flexion, extension, adduction, 
abduction, circumduction, and 
rotation. 

2. The Knee Joint. 

The knee is a ginglymoid, or 
hinge joint; the bones entering 
into its formation are the con- 
dyles of the femur above, the 
head of the tibia below, and the 
patella in front. The articular 
surfaces are covered with car- 
tilage, lined by synovial mem- 
brane, and connected together 
by ligaments, some of which are 
placed on the exterior of the 
joint, whilst others occupy its 
interior. 

External Ligaments. 

Anterior, or Ligamentum Pa- 
tellae. 

Posterior, or Ligamentum Pos- 
ticum Winslowii. 

Internal Lateral. 

Two External Lateral. 

Capsular. 



Anterior View. 







KNEE JOINT. 



173 



Internal Ligaments. 

Anterior, or External Crucial. Two Semilunar Fibro-cartilages. 

Posterior, or Internal Crucial. Transverse. 

Coronary. 

„ . 1 T,*- , ( Liffamentum mucosum. 

Synovial Membrane. s t • x i • 

"^ ( Ligamenta aiaria. 

Tlie Anterior Ligament, or Ligamentum Patellce (fig. 122), is that portion of the 
common tendon of the extensor muscles of the thigh v^hich is continued from the 
patella to the tubercle of the tibia, supplying the place of an anterior ligament. 
It is a strong, flat, ligamentous band, attached, above, to the apex of the patella 
jind the rough depression on its posterior surface; below, to the lower part of the 
tuberosity of the tibia; its superficial fibres being continuous across the front of 
the patella with those of the tendon of the Rectus femoris. Two synovial bursas 
are connected with this ligament and the patella; one is interposed between the 
patella and the skin covering its anterior surface; the other, of small size, between 
the ligamentum patellce and the upper part of the tuberosity of the tibia. The 
posterior surface of this ligament is separated above from the knee joint by a 
large mass of adipose tissue, its lateral margins are continuous with the aponeu- 
roses derived from the Vasti muscles. 

The Posterior Ligament, Li- 
gamentum Posticum Winsloioii i^s.-^igbt-Knee Joint. Posterior View. 

(fig. 123), is a broad, flat, fibrous 

band, which covers over the 

whole of the back part of the 

joint. It consists of two lateral 

portions, formed chiefly of ver- 
tical fibres, which arise above 

from the condyles of the femur, 

and connected below with the 

back part of the head of the tibia, 

being closely united with the 

tendons of the Gastrocnemii, 

Plantaris, and Popliteus muscles; 

the central portion is formed of 

fasciculi obliquely directed and 

separated from one another by 

apertures for the passage of 

vessels. The strongest of these 

fasciculi is derived from the 

tendon of the Semi-membranosus, 

it passes from the back part of 

the inner tuberosity of the tibia, 

obliquely upwards and outwards 

to the back part of the outer 
condyle of the femur. The 
posterior ligament forms part of 
the floor of the popliteal space, 
and upon it rests the popliteal 
artery. 

The Internal Lateral Ligament is a broad, flat, membranous band, thicker 
behind than in front, and situated nearer to the back than the front of the 
joint. It is attached, above, to the inner tuberosity of the femur; below, to the 
inner tuberosity and inner surface of the shaft of the tibia, to the extent of about 
two inches. It is crossed, at its lower part, by the aponeurosis of the Sartorius, 
and the tendons of the Gracilis and Semi-tendinosus -muscles, a synovial bursa 
being interposed. Its deep surface covers the anterior portion of the tendon of 




174 



ARTICULATIONS. 



the Semi-membranosus, the synovial membrane of the joint, and the inferior inter- 
nal articular artery; it is intimately adherent to the internal semi-lunar fibro- 
cartilage. 

The Long External Lateral Ligament is a strong, rounded, fibrous cord, 
situated nearer the posterior part of the articulation than the anterior. It is 
attached, above, to the outer tuberosity of the femur; belovs^, to the outer part of 
the head of the fibula. Its outer surface is covered by the tendon of the Biceps, 
which divides into two parts, separated by this ligament, at its insertion. It has, 
passing beneath it, the tendon of the Popliteus muscle, and the inferior external 
articular artery. 

The Short External Lateral Ligament is an accessory bundle of fibres, placed 
behind and parallel with the preceding; attached, above, to the lower part of the 
outer tuberosity of the femur; below, to the summit of the styloid process of the 
fibula. This ligament is intimately connected with the capsular ligament, and 
has passing beneath it the tendon of the Popliteus muscle. 

The Capsular Ligament consists of an exceedingly thin, but strong, fibrous 
membrane, which surrounds the joint in the intervals left by the preceding liga- 
ments, being attached to the femur immediately above its articular surface ; 
below, to the upper border and sides of the patella, the margins of the head of 
the tibia and inter-articular cartilages, and being continuous behind with the pos- 
terior ligament. This membrane is strengthened by fibrous expansions, derived 
from the fascia lata and Yasti muscles, at their insertion into the sides of the 
patella. 

The Crucial are two interosseous ligaments of very considerable strength, 
situated in the interior of the joint, nearer its posterior than its anterior part. 
They ai'e called crucial, because they cross each other, somewhat like the lines of 



124. — Eight Knee-Joint. Shewing Internal Ligaments. 
F e : 



SUPERIOR 
•riBULAH ABTICl 




KNEE JOINT. 



175 



125. — Head of Tibia, with Semi-lunar 

Cartilages, etc. Seen from above. 

Eight Side. 



the letter X; and have received the names anterior and posterior, from the posi- 
tion of their attachment to the tibia. 

The Anterior or External Crucial Ligament (fig. 124), smaller than the poste- 
rior, arises from the inner side of the depression in front of the spine of the tibia, 
being blended with the anterior extremity of the external semi-lunar fibro-carti- 
lage, and passing obliquely upwards, backwarks, and outwards, is inserted into 
the inner and back part of the outer condyle of the femur. 

The Posterior or Internal Crucial Ligament is larger in size, but less oblique 
in its direction than the anterior. It arises from the back part of the depression 
behind the spine of the tibia, and from the posterior extremity of the external 
semi-lunar fibro-cartilage ; passing upwards, forwards, and inwards, it is inserted 
into the outer and front part of the inner condyle of the femur. As it crosses the 
anterior crucial ligament, a fasciculus is given off from it, which blends with its 
posterior part. It is in relation, in front, with the anterior ligament; behind, 
with the ligamentum posticum Winslowii. 

The Semi-lunar Fibro- Cartilages (fig. 125) are two crescentic lamellae attached 
to the margins of the head of the tibia, serving to deepen its surface for articula- 
tion with the condyles of the femur. The 
circumference of each cartilage is thick and 
convex ; the inner free border, thin and con- 
cave. Their upper surfaces are concave, and 
in relation with the condyles of the femur; 
their lower surfaces are flat, and rest upon 
the head of the tibia. Each cartilage covers 
nearly the outer two-thirds of the corre- 
sponding articular surface of the tibia, the 
inner third being uncovered; both surfaces 
are smooth, and invested by synovial mem- 
brane. 

The Internal Semi-lunar Fibro- Cartilage 
is nearly semicircular in form, a little elon- 
gated from before backwards, and broader behind than in front; its convex border 
is united to the internal lateral ligament, and to the head of the tibia, by means of 
the coronary ligaments; its anterior extremity, thin and pointed, is firmly im- 
planted into the depression in front of the spine of the tibia; its posterior extre- 
mity to the depression behind the spine. 

The External Semi-lunar Fibro- Cartilage forms nearly an entire circle, cover- 
ing a larger portion of the articular surface than the internal one. It is grooved 
on its outer side, for the tendon of the Popliteus muscle. Its circumference is 
held in connexion with the head of the tibia, by means of the coronary ligaments; 
and by its two extremities is firmly implanted in the depressions in front and 
behind the spine of the tibia. These extremities, at their insertion, are interposed 
between the attachments of the internal cartilage. The external semi-lunar fibro- 

1 cartilage gives off from its anterior border a fasciculus, which forms the trans- 

' verse ligament. By its anterior extremity, it is continuous with the anterior 
crucial ligament. Its posterior extremity divides into three slips ; one, a 
strong cord, passes upwards and forwards, and is inserted into the outer side of 
the inner condyle, in front of the posterior crucial ligament; another fasciculus is 
inserted into the outer side of the inner condyle, behind the posterior crucial 

•ligament; a third fasciculus is inserted into the back part of the anterior crucial 

[ ligament. 

The Transverse Ligament is a band of fibres, which passes transversely between 

I the anterior convex margin of the external cartilage, to the anterior extremity of 

jthe internal cartilage; its thickness varies considerably in different subjects. 

The Coronary Ligaments consist of numerous short fibrous bands, which con- 

inect the convex border of the semi-lunar cartilages with the circumference of the 
head of the tibia, and with the other ligaments surrounding the joint. 




176 ARTICULATIONS. 

The Synovial Membrane of the knee-joint is the largest and most extensive in 
the body. Commencing at the upper border of the patella, it forms a large cul- 
de-sac beneath the Extensor tendon of the thigh: this is sometimes replaced 
by a synovial bursa interposed between this tendon and the femur, which in 
some subjects communicates with the synovial membrane of the knee-joint, by an 
orifice of variable size. On each side of the patella, the synovial membrane 
extends beneath the aponeuroses of the Vasti muscles, and more especially beneath 
that of the Vastus internus; it covers the surface of the patella itself, and, beneath 
it, is separated from the anterior ligament by a considerable quantity of adipose 
tissue. In this situation, it sends oif a triangular- shaped prolongation, containing 
a few ligamentous fibres, which extends from the anterior part of the joint below 
the patella, to the front of the inter-condyloid notch. This fold has been termed 
the ligamentum mucosum. The ligamenta alaria consist of two fringe-like 
folds, which extend from the sides of the ligamentum mucosum, upwards and out- 
wards, to the sides of the patella. The synovial membrane covers both surfaces 
of the semi-lunar fibro-cartilages, and on the back part of the external one forms 
a cul-de-sac between the groove on its surface and the tendon of the Popliteus; 
it covers the articular surface of the tibia; surrounds the crucial ligaments, and 
inner surface of the ligaments which enclose the joint; lastly, it covers the entire 
surface of the condyles of the femur, and from them is continued on to the lower 
part of the front surface of the shaft. The pouch of synovial membrane between 
the Extensor tendons and front of the femur is supported, during the movements 
of the knee, by a small muscle, the Sub-crurseus, which is inserted into it. 

The Arteries supplying this joint are derived from the anastomotic branch of 
the Femoral, articular branches of the Popliteal, and recurrent branch of the Ante- 
rior Tibial. 

The Nerves are derived from the obturator and external and internal popliteal. 

Actions. The chief movements of this joint are flexion and extension; but it is 
also capable of performing some slight rotatory movement. During flexion, the 
articular surfaces of the tibia, covered by their inter-articular cartilages, glide 
backwards upon the condyles of the femur, the lateral posterior and crucial liga- 
ments are relaxed, the ligamentum patellae is put upon the stretch, the patella, 
filling up the vacuity in the front of the joint between the femur and tibia. In 
extension, the tibia and inter-articular cartilages glide forwards upon the femur; 
all the ligaments are stretched, with the exception of the ligamentum patellae, 
which is relaxed, and admits of considerable lateral movement. The movement 
of rotation is permitted when the knee is semi-flexed, rotation outwards being 
most extensive. 

3. Articulations between the Tibia and Fibula. 

The articulations between the tibia and fibula are effected by ligaments which 
connect both extremities, as well as the centre of these bones. They may, conse- 
quently, be subdivided into three sets. i. The Superior Tibio-Fibular articula- 
tion. 2. The Middle Tibio-Fibular articulation. 3. The Inferior Tibio-Fibular 
articulation. 

I. Superior Tibio-Fibular Articulation. 

This articulation is an arthrodial joint. The contiguous surfaces of the bones 
present two flat oval surfaces covered with cartilage, and connected together by 
the following ligaments. 

Anterior Superior Tibio-Fibular. 

Posterior Superior Tibio-Fibular. 

Synovial Membrane. 

The Anterior Superior Ligament (fig. 124) consists of two or three broad and 
flat bands, which pass obliquely upwards and inwards, from the head of the fibula 
to the outer tuberosity of the tibia. 



TIBIO-FIBULAR. 



177 



The Posterior Superior Ligament is a single thick and broad band, which 
passes from the back part of the head of the fibula to the back j^art of the outer 
tuberosity of the tibia. It is covered in by the tendon of the Popliteus muscle. 

There is a distinct Synovial Membrane in this articulation. Occasionally the 
synovial membrane of the knee-joint is continuous with it at its upper and back 
part. 



2. Middle Tibio-Fibular Articulation. 

The interval between the tibia and fibula is filled up by an interosseous mem- 
brane, which extends between the contiguous margins of the two bones. It 
consists of a thin aponeurotic lamina composed of oblique fibres, which pass 
between the interosseous ridges on the tibia and fibula. It is broader above than 
below, and presents at its upper part a large oval aperture for the passage of the 
anterior tibial artery forwards to the anterior aspect of the leg; and at its lower 
third, another opening, for the passage of the anterior peroneal vessels. It is 
continuous below with the inferior interosseous ligament; and is perforated in 
numerous parts for the passage of small vessels. By its anterior surface it is in 
relation with the Tibialis anticus, Extensor longus digitorum. Extensor proprius 
pollicis, Peroneus tertius, and the anterior tibial vessels and nerve; behind, with 
the Tibialis posticus and Flexor longus pollicis muscles. 



3. Inferior Tibio-Fibular Articulation. 

This articulation, continuous with that of the ankle-joint, is formed by the 
convex surface at the lower end of the inner side of the fibula, being received 
into a concave surface on the outer side of the tibia. These surfaces, below, to 
the extent of about two lines, are smooth and covered with cartilage, which is 
continuous with that of the ankle-joint. Its ligaments are — 

Inferior Interosseous. Posterior Inferior Tibio-fibular. 

Anterior Inferior Tibio-fibular. Transverse. 

The Inferior Interosseous Ligament consists of numerous short, strong fibrous 
bands, which pass between the contiguous rough surfaces of the tibia and fibula, 
constituting the chief bond of union between these bones. It is continuous, above, 
with the interosseous membrane. 

The Anterior Inferior Ligament {^g.12']^ is a flat triangular band of fibres, 
broader below than above, which extends obliquely downwards and outwards be- 
tween the adjacent margins of the tibia and fibula on the front aspect of the 
articulation. It is in relation, in front, with the Peroneus tertius, the aponeurosis 
of the leg, and the integument; behind, with the inferior interosseous ligament, 
and lies in contact with the cartilage covering the astragalus. 

The Posterior Inferior Ligament, smaller than the preceding, is disposed in 
a similar manner on the posterior surface of the articulation. 

The Transverse Ligament is a long narrow band of ligamentous fibres, con- 
tinuous with the preceding, passing transversely across the back of the joint, 
from the external malleolus to the tibia, a short distance from its malleolar process. 
The three preceding ligaments project somewhat below the margins of the bones, 
and form part of the articulating surface for the ankle-joint. 

The Synovial Membrane lining the articular surfaces is derived from that of 
the ankle-joint. 

Actions. The movement permitted in these articulations is limited to a very 
slight gliding of the articular surfaces upon one another. 

N 



178 



ARTICULATIONS. 



4. Ankle Joint. 



The Ankle is a ginglymoid or hinge joint. The bones entering into its forma- 
tion are the lower extremity of the tibia and its malleohis, and the malleolus of 
the fibula, above, which, united, form an arch, in which is received the upper 
convex surface of the astragalus and its two lateral facets. These surfaces are 
covered with cartilage, lined by synovial membrane, and connected together by 
the following ligaments: 

Anterior. Internal Lateral. 

External Lateral. 

The Anterior Ligament (fig, 126) is a broad, thin, membranous layer, attached, 
above, to the margin of the articular surface of the tibia; below, to the margin of 
the astragalus, in front of its articular surface. It is in relation, in front, with 



126. — Ankle-joint: Tarsal and Tarso-Metatarsal Articulations. 

Eight Side. 



Internal View. 



TARSO-METATARSAl. 
ARTIC 




TARSAL ARTlC"f 



the extensor tendons of the toes, the tendons of the Tibialis anticus and Peroneus 
tertius, and the anterior tibial vessels and nerve; posteriorly, it lies in contact 
with the synovial membrane. 

The Internal Lateral or Deltoid Ligament consists of two layers, superficial 
and deep. The superficial layer is a strong, flat, triangular band, attached, above, 
to the apex and anterior and posterior borders of the inner malleolus. The most 
anterior fibres pass forwards to be inserted into the scaphoid; the middle descend 
almost perpendicularly to be inserted into the os calcis; and the posterior fibres 
pass backwards and outwards to be attached to the inner side of the astragalus. 
The deeper layer consists of a short, thick, and strong fasciculus, which passes 
from the apex of the malleolus to the inner surface of the astragalus, below the 
articular surface. This ligament is covered in by the tendons of the Tibialis 
posticus and Flexor longus digitorum muscles. 



ANKLE-JOINT. 



179 



The External Lateral Ligament (fig. 127) consists of three fasciculi, taking 
different directions, and separated by distinct intervals. 

The anterior fasciculus, the shortest of the three, passes from the anterior 
margin of the summit of the external malleolus, downwards and forwards, to the 
astragalus, in front of its external articular facet. 

Tlhe, posterior fasciculus, the most deeply seated, passes from the depression at 
the inner and back part of the external malleolus to the astragalus, behind its 
external malleolar facet. Its fibres are directed obliquely downwards and in- 
wards. 

The middle fasciculus, the longest of the three, is a narrow rounded cord, pass- 
ing from the apex of the external malleolus downwards and slightly backwards to 
the middle of the outer side of the os calcis. It is covered by the tendons of the 
Peroneus longus and brevis. There is no posterior ligament, its place being sup- 
plied by the transverse ligament of the tibia and fibula. 

The Synovial Membrane invests the cartilaginous surfaces of the tibia and 



127. — ^Ankle- Joint : Tarsal and Tarso-Metatarsal Articulations. 

Right Side. 



External View. 



INFERIOR TIBIO-FIEULAFI 
ARTJCS 



ANKLE-40INT 

TflRSAL ARTIC"? 

TARSO-METATAFtSAL ARTICB? 




fibula, and sends a duplicature upwards between their lower extremities; it is 
then reflected on the inner surface of the ligaments surrounding the joint, and 
covers the upper surface of the astragalus and its two lateral facets below. 

Relations. The tendons, vessels, and nerves in connection with this joint are, 
in front, from within outwards, the Tibialis anticus, Extensor proprius pollicis, 
anterior tibial vessels, anterior tibial nerve. Extensor communis digitorum, and 
Peroneus tertius; behind, from within outwards. Tibialis posticus, Flexor longus 
digitorum, posterior tibial vessels, posterior tibial nerve, Flexor longus pollicis, 
and, in the groove behind the external malleolus, the tendons of the Peroneus 
longiis and brevis. 

The Arteries supplying the joint are derived from the malleolar branches of the 
anterior tibial and peroneal. 

The Nerves are derived from the anterior tibial. . 

Actions. The movements of this joint are limited to" flexion and extension, 
There is no lateral motion. 

N 2 



i8o ARTICULATIONS. 

5. Articulations of the Tarsus. 

These articulations may be subdivided into three sets: I. The articulation of 
the first row of tarsal bones. 2. The articulation of the second row of tarsal 
bones. 3. The articulation of the two rows with each other. 

I. Articulation of the First Row of Tarsal Bones. 

The articulation between the astragalus and os calcis is an arthrodial joint, 
connected together by three ligaments. 

External Calcaneo-Astragaloid. Interosseous. 

Posterior Calcaneo-Astragaloid. Two Synovial Membranes. 

The External Calcaneo-Astragaloid Ligament (fig. 127) is a short, strong fasci- 
culus, passing from the outer surface of the astragalus, immediately beneath its 
external malleolar facet, to the outer edge of the os calcis. It is placed in front 
of the middle fasciculus of the external lateral ligament of the ankle-joint, with 
the fibres of which it is parallel. 

The Posterior Calcaneo-Astragaloid Ligament (fig. 126) connects the posterior 
extremity of the astragalus with the upper contiguous surface of the os calcis; it 
is a short narrow band, the fibres of which are directed obliquely backwards and 
inwards. 

The Interosseous Ligament forms the chief bond of union between these bones. 
It consists of numerous vertical and oblique fibres, attached by one extremity to 
the groove between the articulating surfaces of, the astragalus, by the other, to a 
corresponding depression on the upper surface of the os calcis. It is very thick 
and strong, being at least an inch in breadth from side to side, and serves to unite 
the OS calcis and astragalus solidly together. 

The Synovial Membranes (fig. I2g) are two in number; one for the posterior 
calcaneo-astragaloid articulation, a second for the anterior calcaneo-astragaloid 
joint. The latter synovial membrane is continued forwards between the con- 
tiguous surfaces of the astragalus and scaphoid bones. 

2. Articulations of the Second Row of Tarsal Bones. 

The articulations between the scaphoid, cuboid, and three cuneiform are effected 
by the following ligaments. 

Dorsal. Plantar. 

Interosseous. 

The Dorsal Ligaments are small bands of parallel fibres, which pass from each 
bone to the neighbouring bones with which it articulates. 

The Plantar Ligaments have the same arrangement on the plantar surface. 

The Interosseous Ligaments are four in number. They consist of strong 
transverse fibres, which pass between the rough non-articular surfaces of adjoin- 
ing bones. There is one between the sides of the scaphoid and cuboid, a second 
between the internal and middle cuneiform bones, a third between the middle and 
external cuneiform, and a fourth between the external cuneiform and cuboid. 
The scaphoid and cuboid, when in contact, present each a small articulating facet, 
covered with cartilage, and lined either by a separate synovial membrane, or by 
an offset from the common tarsal synovial membrane. 

3. Articulations of the Two Rows of the Tarsus with each other. 
These articulations consist of ligaments that may be conveniently divided into 



OF THE TARSUS. 



i8i 



three sets. i. The articulation of the os calcis with the cuboid. 2. Tlic os 
calcis with the scaphoid. 3. The astragalus with the scaphoid. 

I. The ligaments connecting the os calcis with the cuboid are four in number. 



Dorsal. 



Plantar, 



( Superior Calcaneo-Cuboid. 
( Internal Calcaneo-Cuboid (Interosseous), 
j Long Calcaneo-Cuboid. 
" \ Short Calcaneo-Cuboid. 



128. — Ligaments of Plantar Surface of the 
Foot. 



Synovial Membrane. 

The Superior Calcaneo-Cuboid Ligament (fig. 1 27) is a thin and narrow 
fasciculus, which passes between the contiguous surfaces of the os calcis and 
cuboid, on the dorsal surface of the joint. 

The Internal Calcaneo-Cuboid {Interosseous) Ligament (Q.g. 127) is a short, but 
thick and strong, band of fibres, arising from the os calcis, in the deep groove which 
intervenes between it and the astragalus; being closely blended, at its origin, 
with the superior calcaneo-scaphoid ligament. It is inserted into the inner side 
of the cuboid bone. This ligament forms one of the chief bonds of union between 
the first and second row of the tarsus. 

The Long Calcaneo-Cuboid (fig. 128), the most superficial of the two plantar 
ligaments, is the longest of all the liga- 
ments of the tarsus, being attached pos- 
teriorly to the under surface of the os 
calcis, as far forwards as the anterior 
tubercle, and passing horizontally for- 
wards to the tuberosity on the under 
surface of the cuboid bone, the more 
superficial fibres being continued for- 
wards to the bases of the second, third, 
and fourth metatarsal bones. This liga- 
ment crosses the groove on the under 
surface of the cuboid bone, converting it 
into a canal for the passage of the ten- 
don of the Peroneus longus. 

The Short Calcaneo- Cuboid lies nearer 
to the bones than the preceding, from 
which it is separated by a little areolar 
adipose tissue. It is exceedingly broad, 
and about an inch in length ; passing 
from the tuberosity at the fore part of 
the under surface of the os calcis, to the 
inferior surface of the cuboid bone be- 
hind the peroneal groove. A synovial 
membrane lines the contiguous svirfaces 
of the bones, and is reflected upon the 
i ligaments connecting them. 

2. The ligaments connecting the os 
[calcis with the scaphoid are two in num- 
1 ber. 

Superior Calcaneo- Scaphoid. 

Inferior Calcaneo- Scaphoid. 

. Synovial Membrane. 

The Superior Calcaneo - ScapJtoid 

.arises, (fig. I27)as already mentioned, with 

fthe internal calcaneo-cuboid in the deep 

groove between the astragalus and os calcis, it "passes^ forward from the inner 
side of the anterior extremity of the os calcis to the outer side of the scaphoid 




I«2 



ARTICULATIONS. 



bone. These two ligaments resemble the letter Y, being blended together behind, 
but separated in front. 

The Inferior Calcaneo- Scaphoid {^g. 128) is by far the largest and strongest of 
the two ligaments of this articulation; it is a broad and thick band of ligamentous 
fibres, which passes forwards and inwards from the anterior and inner extremity 
of the OS calcis, to the under surface of the scaphoid bone. This ligament not only 
serves to connect the os calcis and scaphoid, but supports the head of the astra- 
galus, forming part of the articular cavity in which it is received. Its upper 
surface is lined by the synovial membrane continued from the anterior calcaneo- 
astragaloid articulation. Its under surface is in contact with the tendon of the 
Tibialis posticus muscle. 

3. The articulation between the astragalus and scaphoid is an enarthrodial 
joint; the rounded head of the astragalus being received into the concavity formed 
by the posterior surface of the scaphoid, the anterior articulating surface of the 
calcaneum, and the upper surface of the calcaneo- scaphoid ligament, which fills up 
the triangular interval between these bones. The only ligament of this joint is 
the superior astragalo-scaphoid, a broad band of ligamentous fibres, which passes 
obliquely forwards from the neck of the astralagus, to the superior surface of the 
scaphoid bone. It is thin and weak in texture, and covered by the Extensor 
tendons. The inferior calcaneo-scaphoid supplies the place of an inferior liga- 
ment. 

The Synovial Membrane which lines this joint is continued forwards from the 
anterior calcaneo-astragaloid articulation. This articulation permits of considerable 
mobility; but its feebleness is such as to occasionally allow of dislocation of the 
astragalus. 

The Synovial Membranes (fig. 129) found in -the articulations of the tarsus are 

129. — Oblique Section of the Articulations of the Tarsus and Metatarsus. 
Shewing the Six Synovial Membranes. 




four in number: one for the posterior calcaneo-astragaloid articulation; a second 
for the anterior calcaneo-astragaloid and astragalo-scaphoid articulations; a third 
for the calcaneo-cuboid articulation; and &. fourth for the articulations between 
the scaphoid and the three cuneiform, the three cuneiform with each other, the 
external cuneiform with the cuboid, and the middle and external cuneiform with 
the bases of the second and third metatarsal bones. The prolongation which lines 
the metatarsal bones, passes forwards between the external and middle cuneiform 
bones. A small synovial membrane is sometimes found between the contiguous 
surfaces of the scaphoid and cuboid bones. 

Actions. The movements permitted between the bones of the first row, the 



TARSO-METATARSAL. 183 

astragalus, and os calcis, are limited to a gliding upon each other from before 
backwards, and from side to side. The gliding movement which takes place 
between the bones of the second row is very slight, the articulation between the 
scaphoid and cuneiform bones being more moveable than those of the cuneiform 
with each other and with the cuboid. The movement which takes place between 
the two rows is more extensive, and consists in a sort of rotation, by means ot 
which the sole of the foot may be slightly flexed, and extended, or carried inwards 
and outwards. 

6. Tarso-Metataksal Articulations. 

These are arthrodial joints. The bones entering into their formation are the 
internal, middle, external cuneiform, and cuboid, which articulate with the meta- 
tarsal bones of the five toes. The metatarsal bone of the first toe articulates with 
the internal cuneiform; that of the second is deeply wedged in between the in- 
ternal and external cuneiform, resting against the middle cuneiform, and being the 
most strongly articulated of all the metatarsal bones; the third metatarsal articu- 
lates with the extremity of the external cuneiform; the fourth with the cuboid 
and external cuneiform; and the fifth with the cuboid. These various articular 
surfaces are covered with cartilage, lined by synovial membrane, and connected 
together by the following ligaments. 

Dorsal. Plantar. 

Interosseous. 

The Dorsal Ligaments consist of strong, flat, fibrous bands, which connect the 
tarsal with the metatarsal bones. The first metatarsal is connected to the inter- 
nal cuneiform by a single broad, thin, fibrous band; the second has three dorsal 
ligaments, one from each cuneiform bone; the third has one from the external 
cuneiform; and the fourth and fifth have one each from the cuboid. 

The Plantar Ligaments consist of strong fibrous bands connecting the tarsal 
and metatarsal bones, but disposed with less regularity than on the dorsal surface. 
Those for the first and second metatarsal are the most strongly marked; the 
second and third receive strong fibrous bands, which pass obliquely across from 
the internal cuneiform; the plantar ligaments of the fourth and fifth consist of a 
few scanty fibres derived from the cuboid. 

The Interosseous Ligaments are three in number: internal, middle, and exter- 
nal. The internal one passes from the outer extremity of the internal cuneiform, 
to the adjacent angle of the second metatarsal. The middle one, less strong than 
the preceding, connects the external cuneiform with the adjacent angle of the 
second metatarsal. The external interosseous ligament connects the outer angle 
of the external cuneiform with the adjacent side of the third metatarsal. 

The Synovial Membranes of these articulations are three in number: one for the 
metatarsal bone of the great toe, with the internal cuneiform: one for the second 
and third metatarsal bones, with the middle and external cuneiform; this is con- 
tinuous with the great tarsal synovial membrane: and one for the fourth and fifth 
metatarsal bones with the cuboid. The synovial membranes of the tarsus and 
metatarsus are thus seen to be six in number (fig. 129). 

Articulations of the Metatarsal Bones with each other. 

At their tarsal extremities, the metatarsal bones are connected together by dorsal, 
plantar, and interosseous ligaments. The dorsal and plantar ligaments pass from 
one metatarsal bone to another. The interosseous ligaments lie deeply between the 
rough non-articular portions of their lateral surfaces. The articular surfaces are 
covered by synovial membrane, continued forwards from their respective tarsal 
joints. At their digital extremities, they are connected to each other by the trans- 
verse metatarsal ligament, which holds them loosely together. This ligament, 
which is analogous to the same structure in the hand, connects the great toe 
v/ith the rest of the metatarsal bones, which in this respect difiers from the same 
structure in the hand. 



1 84 ARTICULATIONS. 

Actions. The movement permitted in the tarsal ends of the metatarsal bones is 
limited to a slight gliding of the articular surfaces upon one another; considerable 
motion, however, takes place in their digital extremities. 

Metatarso-Phalangeal Articulations. 

The heads of the metatarsal bones are connected with the concave articular 
surfaces of the first phalanges by the following ligaments : 

Anterior or Plantar. Two Lateral. 

Synovial Membrane. 

They are arranged precisely similar to the corresponding parts in the hand. 
The expansion of the extensor tendon supplies the place of a posterior ligament. 

Actions. The movements permitted in the metatarso-phalangeal articulations are 
flexion, extension, abduction, and adduction. 



Articulation of the Phalanges. 

The ligaments of these articulations are similar to those found in the hand; each 
pair of phalanges being connected by an anterior or plantar and two lateral liga- 
ments, and their articular surfaces lined by synovial membrane. Their actions 
are also similar. 



I 



The Muscles and Fasciae. 

THE Muscles and Fasciae are descx-ibed conjointly, in oi-der that the student may 
considei' the arrangement of the latter in his dissection of the former. It is 
rare for the student of anatomy in this country to have the opportunity of dissect- 
ing the fascite separately; and it is from this reason, as well as from the close 
connexion that exists between the muscles and their investing aponeuroses, that 
they are considered together. Some general observations are first made on the 
anatomy of the muscles and fasciae, the special description being given in con- 
nexion with the different regions. 

The Muscles are the active organs of locomotion. They are formed of bundles 
of reddish fibres, consisting chemically of fibrine, and endowed with the property 
of contractility. 

Muscle is of a deep red colour, the intensity of which varies considerably with 
the age and health of the individual. It is composed of bundles of parallel fibres, 
placed side by side, and connected together by a delicate web of areolar tissue. 
Each fasciculus consists of numerous smaller bundles, and these of single fibres, 
which, from their minute size and comparatively isolated appearance, have been 
called ultimate fibres. Two kinds of ultimate muscular fibre are found in the 
animal body, viz., that of voluntary or animal life, and that of involuntary or 
organic life. The ultimate fibre of animal life is capable of being either excited 
or controlled by the efforts of the will, and is characterised, on microscopic exami- 
nation, by its size, its uniform calibre, and the presence of minute transverse bars, 
which are situated at short and i-egular distances throughout its whole extent. Of 
such is composed the muscular tissue of the trunk and limbs; the fibres of the 
heart, and some of those of the oesophagus: the muscles of the internal ear, and 
those of the urethra, present a similar structure, although they are not capable of 
being acted upon by the will. Involuntary muscular fibre is entirely withdrawn 
from the influence of volition, and is characterised, on microscopic examination, by 
the ultimate fibrils being homogeneous in structure, of smaller size than those of 
animal life, flattened, and unstriped; of such the muscles of the digestive canal, 
the bladder, and uterus are composed. 

Each muscle is invested externally by a thin cellular layer, forming what is 
called its sheath, which not only covers its outer surface, but penetrates into its 
interior in the intervals between the fasciculi, surrounding these, and serving as a 
bond of connection between them. 

The voluntary muscular fibres terminate at either extremity in fibrous tissue, 
the separate fibrillse of which being, in some cases, aggregated together, form a 
rounded or flattened fibrous cord or tendon; in the flat muscles, the separate fibres 
are arranged in flattened membranous laminae, termed aponeuroses; and it is in 
one or other of these forms, that nearly every muscle is attached to the pai't which 
it is destined to move. 

The involuntary muscular fibres, on the contrary, form a dense interlacement, 
crossing each other at various angles, forming a layer of variable thickness, which 
usually circumscribes the wall of some cavity, which, by its contraction, it 
constricts. 

Muscles vary considerably in their form. In the limbs, they are of considerable 
length, especially the more superficial ones, the deep ones being generally broad ; 
they, surround the bones, and form an important protection to the various joints. 
In the trunk, they are broad, flattened, and expanded, forming the parietes of the 
cavities which they enclose; hence the reason of the terms, long, broad, short, etc., 
I used in the description of a muscle. 

There is considerable variation in the arrangement of the fibres of certain 
: muscles, in relation to the tendon to which they are attached. In some, the fibres 



i86 MUSCLES AND FASCIA. 

are arranged longitudinally, and terminate at either end in a narrow tendon, so 
that the muscle is broad at the centre, and narrowed at either extremity: such a 
muscle is said to he fusiform in shape, as the Rectus femoris. If the fibres con- 
verge, like the plumes of a pen, to one side of a tendon, which runs the entire 
length of the muscle, it is said to be penniform, as the Peronei; or, if they converge 
to both sides of a tendon, they are called bipenniform, as the Rectus femoris; if 
they converge from a broad surface to a narrow tendinous point, they are then 
said to be radiated, as the Temporal and Glutei muscles. 

Their size presents considerable variation: the Gastrocnemius forms the chief 
bulk of the back of the leg, and the fibres of the Sartorius are nearly two feet in 
length, whilst the Stapedius, a small muscle of the internal ear, weighs about a 
grain, and its fibres are not more than two lines in length. In each case, how- 
ever, they are admirably adapted to execute the^ various movements they are 
required to perform. 

The names applied to the various muscles have been derived: i,from their situ- 
ation, as the Tibialis, Radialis, Ulnaris, Peroneus; 2, from their direction, as the 
Rectus abdominis, Obliqui capitis, Transversalis; 3, from their uses, as Flexors, 
Extensors, Abductors, etc. ; 4, from their shape, as the Deltoid, Trapezius, Rhom- 
boideus; 5, from the number of their divisions, as the Biceps (from having two 
heads), the Triceps (from having three heads) ; 6, from their points of attachment, 
as the Sterno-cleido-mastoid, Sterno-hyoid, Sterno-thyroid. 

In the description of a muscle, the term origin is meant to imply its more fixed 
or central attachment; and the tei'm insertion, the moveable point upon which 
the force of the muscle is directed: this holds true, however, for only a very small 
number of muscles, such as those of the face, which are attached by one extremity 
to the bone, and by the other to the moveable integument; in the greater number, 
the muscle can be made to act from either extremity. 

In the dissection of the muscles, the student should pay especial attention to 
the exact origin, insertion, and actions of each, and its more important relations 
with surrounding parts. An accurate knowledge of the points of attachment of 
the muscles is of great importance in the determination of their action. By 
a knowledge of the action of the muscles, the surgeon is able at once to explain 
the causes of displacement in the various forms of fracture, or the causes which 
produce distortion in various forms of deformities, and, consequently, to adopt 
appropriate treatment in each case. The relations, also, of some of the muscles 
especially those in immediate apposition with the larger blood-vessels; and the 
surface-markings they produce should be especially remembered, as they form 
most useful guides to the surgeon in the application of a ligature to these vessels. 

The Fascias (^fascia, a bandage) are fibro-areolar or aponeurotic laminae, of vari- 
able thickness and strength, found in all regions of the body, investing the softer 
and more delicate organs. The fasciae have been subdivided, from the structure 
which they present, into two groups, fibro-areolar or superficial fasciae, and aponeu- 
rotic or deep fascia. 

The fibro-areolar fascia is found immediately beneath the integument over 
almost the entire surface of the body, and is generally known as the superficial 
fascia. It connects the skin with the deep or aponeurotic fascia, and consists of 
fibro-areolar tissue, containing in its meshes pellicles of fat in varying quantity. 
In the eyelids and scrotum, where adipose tissue is never deposited, this tissue is 
very liable to serous infiltration. This fascia varies in thickness in difierent parts 
of the body: in the groin it is so thick as to be capable of being subdivided into 
several laminae, but in the palms of the hands it is of extreme thinness, and inti- 
mately adherent to the integument. The superficial fascia is capable of separation 
into two or more layers, between which are found the superficial vessels and nerves, 
and superficial lymphatic glands; as the superficial epigastric vessels in the ab- 
dominal region, the radial and ulnar veins in the forearm, the saphenous veins 
in the leg and thigh, as well as in certain situations cutaneous muscles, as the 
Platysma myoides in the neck, Orbicularis palpebrarum around the eyelids. It is 



GENERAL ANATOMY. 187 

most distinct at the lower part of the abdomen, the scrotum, perinasum, and in the 
extremities; is very thin in those regions where muscular fibres are inserted into 
the integument, as on the side of the neck, the face, and around the margin of the 
anus, and almost entirely wanting in the palms of the hands and soles of the feet, 
where the integument is adherent to the subjacent aponeurosis. The superficial 
fascia connects the skin to the subjacent parts, serves as a soft nidus, for the pas- 
sage of vessels and nerves to the integuments, and retains the warmth of the body 
from the adipose tissue contained in its areolee, being a bad conductor of caloric. 

The aponeurotic or deep fascia is a dense inelastic and unyielding fibrous 
membrane, forming sheaths for the muscles, and affording them broad surfaces for 
attachment, it consists of shining tendinous fibres, placed parallel with one another, 
and connected together by other fibres disposed in a reticular manner. It is usu- 
ally exposed on the removal of the superficial fascia, forming a strong investment, 
which not only binds down collectively the muscles in each region, but gives a 
separate sheath to each, as well as to the vessels and nerves. The fasciae are 
thick in unprotected situations, as on the outer side of a limb, and thinner on 
the inner side. By Bichat, aponeurotic fasciae were divided into two classes, 
aponeuroses of insertion, and aponeuroses of investment. 

The aponeuroses of insertion serve for the insertion of muscles. Some of these 
are formed by the expansion of a tendon into an aponeurosis, as, for instance, the 
tendon of the Sartorius; others do not originate in tendons, as the aponeuroses of 
the abdominal muscles. 

The aponeuroses of investment form a sheath for the entire limb, as well as 
for each individual muscle. Many aponeuroses, however, serve both for invest- 
ment and insertion. Thus the deep fascia on the front of the leg gives 
attachment to the muscles in this region; and the aponeurosis of insertion given off 
from the tendon of the Biceps is continuous with the investing fascia of the fore- 
arm, and gives origin to the muscles in this region. The deep fasciae assist the 
muscles in their action, by the degree of tension and pressure they make upon their 
surface; and in certain situations this is increased and regulated by muscular 
action, as, for instance, by the Tensor vaginae femoris and Gluteus maximus in 
the thigh, by the Biceps in the leg, and Palmaris longus in the hand. In the 
limbs, the fasciae not only invest the entire limb, but give off septa, which sepa- 
rate the various muscles, and are attached beneath to the periosteum; these pro- 
longations of fasciae are usually spoken of as intermuscular septa. 

The Muscles and Fasciae may be arranged, according to the general division of 
the body, into, i. Those of the head, face, and neck. 2. Those of the trunk. 
3. Those of the upper extremity. 4. Those of the lower extremity. 

MUSCLES AND FASCIA OF THE HEAD AND FACE. 

The Muscles of the Head and Face consist of ten groups, arranged according 
to the region in which they are situated. 

1. Cranial Region. 6. Superior Maxillary Region. 

2. Auricular Region. 7. Inferior Maxillary Region. 

3. Palpebral Region. 8. Inter-Maxillary Region. 

4. Orbital Region. 9. Temporo-Maxillary Region. 

5. Nasal Region. lO. Pterygo-Maxillary Region. 

The Muscles contained in each of these groups are the following. 

I. Epicranial Region. 3. Palpebral Region. 

Occipito-frontalis. Orbicularis palpebrarum. 

r. A • 1 D • Corrugator supercilii. 

2. Auricular Keqion. m • 

. ^^ ,, lensor tarsi. 
Attoliens aurem. 

Attrahens aurem. ' 4- Orbital Region. 

Retrahens aurem. Levator palpebrae. 



MUSCLES AND FASCIA. 



Rectus superior. 
Rectus inferior. 
Rectus internus. 
Rectus externus. 
Obliquus superior. 
Obliquus inferior. 

5. Nasal Region. 
Pyramidalis nasi. 

Levator labii superioris al^que nasi. 
Levator proprius alee nasi posterior. 
Levator proprius alfB nasi anterior. 
Compressor nasi. 
Compressor narium minor. 
Depressor alae nasi, 

6. Superior Maxillary Region. 
Levator labii superioris proprius. 
Levator anguli oris. 



Zygomaticus major. 
Zygomaticus minor. 

7. Inferior Maxillary Region. 
Levator labii inferioris. 
Depi'essor labii inferioris. 
Depressor anguli oris. 

8. Inter-Maxillary Region. 
Buccinator. 
Risorius. 
Orbicularis oris. 

9. T^mporo- Maxillary Region. 
Masseter. 

Temporal. 

10. Ptery go- Maxillary Region. 
Pterygoideus externus. 
Pterygoideus internus. 



I. Epickanial Region — Occipito-Frontalis. 

Dissectioni^g. 130). The head being staved, and a block placed beneath the back of the 
neck, make a vertical incision through the skin from before backwards, commencing at the root 
of the nose in front, and terminating behind at the occipital protuberance ; make a second 
incision in a horizontal direction along the forehead and around the side of the head, from 

130. — Dissection of the Head, Face, and Neck. 



-/ UlssectioTiofscMj' 

S.S^of AURICULAR REGION 
4^.5. 6. of FACE 
J. 8. of NECK 




the anterior to the posterior extremity of the preceding. Eaise the skin in front from the 
subjacent muscle from below upwards ; this must be done with extreme care, on account 
of their intimate union. The tendon of this muscle is best avoided by removing the in- 
tegument from the outer surface of the vessels and nerves which lie between the two. 

The superficial fascia in the epicranial region is a firm, dense layer, intimately 
adherent to the integument, and to the Occipito-frontalis and its tendinous aponeu- 
rosis; it is continuous, behind, with the superficial fascia at the back pai*t of the 
neck; and, laterally, is continued over the temporal aponeurosis: it contains be- 
tween its layers the small muscles of the auricle, and the superficial temporal 
vessels and nerves. 

The Occipito-frontalis (fig. 131) is a broad musculo-fibrous layer, which covers 
over the whole of one side of the vertex of the skull, from the occiput to the eye- 



OCCIPITO-FRONTALIS. 



i8g 



brow. It consists of two muscular bellies, separated by an intervening tendinous 
aponeurosis. The occipital portion, thin, quadrilateral in form, and about an inch 
and a half in length, arises from the outer two-thirds of the superior curved line 
of the occijiital bone, and from the mastoid portion of the temporal. Its fibres of 



CORRUCATOR 



OILATOK NARIS A^ 
DILATOaNARIS POSTER 




131. — Muscles of the Head, Face, and Neck. 



origin are tendinous, but they soon become muscular, and ascend in a parallel 
direction to terminate in the tendinous aponeurosis. The frontal portion is thin, 
of a quadrilateral form, and intimately adherent to the skin. It is broader, its 
fibres are longer, and their structure more pale than the occipital portion. Its 



igo MUSCLES AND FASCIA. 

internal fibres are continuous with those of the Pyramidalis nasi. Its middle 
fibres become blended with the Corrugator supercilii and Orbicularis: and the 
outer fibres are also blended with the latter muscle over the external angular 
process. The inner margins of the two frontal portions of the muscle are joined 
together for some distance above the root of the nose; but between the occipital 
portions there is a considerable but variable interval. 

The aponeurosis covers over the whole of the vertex of the skull without any 
separation into two lateral parts, and is connected with the occipital and frontal 
portions of the muscle. Behind, it is attached, in the interval between the occi- 
pital origins, to the occipital protuberance and superior curved lines above the 
attachment of the trapezius; in front, it forms a short angular prolongation be- 
tween the frontal portions; and on each side, it has connected with it the Attollens 
and Attrahens aurem muscles: in this situation it loses its aponeurotic character, 
and is continued over the temporal fascia to the zygoma by a layer of laminated 
areolar tissue. This aponeurosis is closely connected to the integument by a 
dense fibro-cellular tissue, which contains much granular fat, and in which ramify 
the numerous vessels and nerves of the integument; it is loosely connected with 
the pericranium by a quantity of loose cellular tissue, which allows of a considerable 
degree of movement of the integument. 

Nerves. The Occipito-frontalis is supplied (frontal portion) by the supra-orbital 
and facial nerves; (occipital portion) by the posterior auricular branch of the facial 
and the small occipital. 

Actions. This muscle raises the eyebrows and the skin over the root of the nose; 
at the same time it throws the integument of the forehead into transverse wrinkles, 
a predominant expression in the emotions of delight. It also moves the scalp from 
before backwards, by bringing alternately into action the occipital and frontal 
portions. 

Auricular Region (fig. 131). 

Attollens Aurem. Attrahens Aurem. 

Retrahens Aurem. 

These three small muscles are placed immediately beneath the skin around the 
external ear. In man, in whom the external ear is almost immoveable, they are 
rudimentary. They are the analogues of large and important muscles in some of 
the mammalia. 

Dissection. This requires considerable care, and should be performed in the following 
manner. To expose the Attollens aurem ; draw the pinna or broad part of the ear down- 
wards, when a tense band will be felt beneath the skin, passing from the side of the head 
to the upper part of the concha; by dividing the skin over the tendon, in a direction from 
below upwards, and then reflecting it on each side, the muscle is exposed. To bring into 
view the Attrahens aurem, draw the helix backwards by means of a hook, when the muscle 
will be made tense, and may be exposed in a similar manner to the preceding. To expose 
the Retrahens aurem, draw the pinna forwards, when the muscle being made tense may be 
felt beneath the skin, at its insertion into the back part of the concha, and may be exposed 
in the same manner as the other muscles. 

The Attollens Aurem (superior auriculae), the largest of the three, is thin, 
and of a radiated form; it arises from the aponeurosis of the Occipito-frontalis, and 
is inserted by a thin, flattened tendon into the upper and anterior part of the concha. 

Relations. Externally, with the integument; internally, with the Temporal apo- 
neurosis. 

The Attrahens Aurem (anterior auriculse), the smallest of the three, is of a 
triangular form, very thin in texture, and its fibres pale and indistinct. It arises 
from the lateral edge of the aponeurosis of the Occipito-frontalis; its fibres con- 
verge to be inserted into the front of the helix. 

Relations. Externally, with the skin; internally, with the temporal fascia, 
which separates it from the temporal artery and vein. 

The Retrahens Aurem (posterior auriculae) consists of two or three fleshy 



AURICULAR AND PALPEBRAL REGIONS. 



191 



fasciculi, which arise from the mastoid portion of the temporal bone by short 
aponeurotic fibres. They are inserted into the back part of the concha. 

Relations. Externally, with the integument; internally, with the mastoid portion 
of the temporal bone. 

Nerves. The Attollens aurem is supplied by the small occipital; the Attrahens 
aurem, by the facial and auriculo-temporal branch of the inferior maxillary, and 
the Retrahens aurem, by the posterior auricular branch of the facial. 

Actions. In man these muscles possess very little action; their use is sufficiently 
expressed in their names. 

Palpebral Region (fig. 131). 

Orbicularis Palpebrarum. Levator Palpebrge. 

Corrugator Supercilii. Tensor Tarsi. 

Dissection (fig. 1 30 — 4). In order to expose the muscles of the face, continue the longitudinal 
incision made in the dissection of the Occipito-frontalis, down the median line of the face to 
the tip of the nose, and from this point onwards to the upper lip ; another incision should 
be carried along the margin of the lip to the angle of the mouth, and transversely across 
the face to the angle of the jaw. The integument should also be divided by an incision 
made in front of the external ear, from the angle of the jaw, upwards, to the transverse 
incision made in exposing the Occipito-frontalis. These incisions include a square-shaped 
flap which should be carefully removed in the direction marked in the figure, as the mus- 
cles at some points are intimately adherent to the integument. 

The Orbicularis Palpebrarum is a sphincter muscle which surrounds the whole 
circumference of the orbit and eyelids. It arises from the internal angular process 
of the frontal bone, from the nasal process of the superior maxillary in front of 
the lachrymal groove, and from the anterior surface and borders of a short tendon, 
the Tendo palpebrarum, placed at the inner angle of the orbit. The muscle, thus 
arising, forms a broad, thin, and flat plane of elliptical fibres, which cover the eye- 
lids, surround the circumference of the orbit, and spread out over the temple, and 
downwards on the cheek, becoming blended with the Occipito-frontalis and Corru- 
gator supercilii. The palpebral portion (ciliaris) of the Orbicularis is thin and 
pale; it arises from the bifurcation of the Tendo palpebrarum, and forms a series 
of concentric curves, which are united on the outer side of the eyelids at an acute 
angle by a cellular raphe, some being inserted into the external tarsal ligament 
and malar bone. The orbicular portion (orbicularis latus) is thicker, of a reddish 
colour, its fibres well developed, forming a complete ellipse. 

The tendo palpebrarum (oculi) is a short tendon, about two lines in length 
and one in breadth, attached to the nasal process of the superior maxillary bone 
anterior to the lachrymal groove. Crossing the lachrymal sac, it divides into two 
parts, each division being attached to the inner extremity of the corresponding 
tarsal cartilage. As the tendon crosses the lachrymal sac, a strong aponeurotic 
lamina is given off from its posterior surface, which expands over the sac, and is 
attached to the ridge on the lachrymal bone. This is the reflected aponeurosis of 
the Tendo palpebrarum. 

Relations. By its superficial surface, the orbicular portion is closely adherent to 
the integument, more especially over the upper segment of the muscle; the palpe- 
bral portion being separated from the skin by loose areolar tissue. By its deep 
surface, above, with the Occipito-frontalis and Corrugator supercilii, with which 
it is intimately blended, and with the supra-orbital vessels and nerve; below, it 
covers the lachrymal sac and the origin of the Levator labii superior! s. Levator 
labii superioris alaeque nasi, and the Zygomaticus major and minor muscles. 
Internally, it is occasionally blended with the Pyramidalis nasi. Externally, it lies 
on the temporal fascia. On the eyelids, it is separated from the conjunctiva by a 
fibrous membrane and the tarsal cartilages. 

The Corrugator Supercilii is a small, narrow, pyramidal muscle, placed at the 
inner extremity of the eyebrow beneath the Occipito-frontalis and Orbicularis 



192 MUSCLES AND FASCIiE. 

palpebrarum muscles. It arises from the inner extremity of the superciliary ridge; 
its fibres pass upwards and outwards, to be inserted into the vmder surface of the 
orbicularis, opposite the middle of the orbital arch. 

Relations. By its anterior surface, with the Occipito-frontalis and Orbicularis 
palpebrarum muscles. By its posterior surface, with the frontal bone and supra- 
orbital vessels and nerve. 

The Levator PalpebrcB will be described with the muscles of the orbital region. 

The Tensor Tarsi is a small thin muscle, about three lines in breadth and six 
in length, situated at the inner side of the orbit, beneath the Tendo oculi. It 
arises from the crest and adjacent part of the orbital surface of the lachrymal bone, 
and passing across the lachrymal sac, divides into two slips, which cover the la- 
chrymal canals, and are inserted into the tarsal cartilages near the Puncta lachry- 
malia. Its fibres apj)ear to be continuous with those of the palpebral portion of 
the Orbicularis; it is occasionally very indistinct. 

Nerves. The Orbicularis palpebrarum and Corrugator supercilii are supplied 
by the facial and supra-orbital nerves; the Tensor tarsi by the facial. 

Actions. The Orbicularis palpebrarum is the sphincter muscle of the eyelids. 
The palpebral portion acts involuntarily in closing the lids, and independently of 
the orbicular portion, which is subject to the will. When the entire muscle is 
brought into action, the integum^ents of the forehead, temple, and cheek are drawn 
inwards towards the inner angle of the eye, and the eyelids are firmly closed. 
The Levator palpebrse is the direct antagonist of this muscle; it raises the upper 
eyelid, and exposes the globe. The Corrugator supercilii draws the eyebrow 
downwards and inwards, producing the vertical wrinkles of the forehead. This 
muscle may be regarded as the principal agent in the expression of grief. The 
Tensor tarsi draws the eyelids and the exti'emities of the lachrymal canals 
inwards, and compresses them against the surface of the globe of the eye; thus 
p lacing them in the most favourable situation for receiving the tears. It serves, 
a Iso, to compress the lachrymal sac. 

Orbital Region (fig. 132). 

Levator Palpebrse. Rectus Internus. 

Rectus Superior. Rectus Externus. 

Rectus Inferior. Obliquus Superior. 

Obliquus Inferior. 

Dissection. To open the cavity of the orbit, the skull-cap and brain should be first 
removed ; then saw through the frontal bone at the inner extremity of the supra-orbital 
ridge, and externally at its junction with the malar. The thin roof of the orbit should 
then be comminuted by a few slight blows with the hammer, and the superciliary portion 
of the frontal bone driven forwards by a smart stroke ; but must not be removed. The 
several fragments may then be detached, when the periosteum of the orbit will be exposed : 
this being removed, together with the fat which fills the cavity of the orbit, the several 
muscles of this region can be examined. To facilitate their dissection, the globe of the 
eye should be distended ; this may be effected by puncturing the optic nerve near the 
eyeball, with a curved needle, and pushing it onwards into the globe. Through this aper- 
ture the point of a blow-pipe should be inserted, and a little air forced into the cavity of 
the eyeball ; then apply a ligature around the neiwe, so as to prevent the air escaping. 
The globe should now be drawn forwards, when the muscles will be put upon the 
stretch. 

The Levator PalpebrcB is a thin, flat, triangular muscle. It arises from the 
under surface of the lesser wing of the sphenoid, immediately above the optic 
foramen; and is inserted, by a broad aponeurosis, into the upper border of the 
superior tarsal cartilage. At its origin it is narrow and tendinous, but soon 
becomes broad and fleshy, and finally terminates in a broad aponeurosis. 

Relations. By its upper surface, with the frontal nerve and artery, the peri- 
osteum of the orbit; and in front with the inner surface of the broad tarsal liga- 
ment. By its under surface, with the Superior rectus; and, in the lid, with the 
conjunctiva. 



ORBITAL REGION. 



193 



The Rectus Superior {Attollens), tho tliinnest and narrowest of the four Recti, 
arises from tlie upper margin of tlxo optic foramen, beneath the Levator palpebras 
and Superior oblique, and from the fibrous slieath of tho optic nerve; and is 

132. — Muscles of the Right Orbit. 




133. — The relative Position and Attach- 
ment of the Muscles of the Left 
Eyeball. 

Ha^cb reels' ti(p« vlar 



inserted, by a tendinous expansion, into the sclerotic coat of the eyeball, about 
three or four lines from the margin of the cornea. 

Relatio7is. By its upper surface, with the Levator palpebrse. By its under 
surface, with the optic nerve, the ophthalmic artery, and nasal nerve; and in 
front with the tendon of the Superior oblique and the globe of the eye. 

The Inferior and Internal Recti arise by a common tendon (the ligament 
of Zinn), which is attached around the circumference of the optic foramen, 
except at its upper and outer part. The 
External rectus has two heads : the upper 
one arises from the outer margin of the 
optic foramen, immediately beneath the Su- 
perior rectus; the lower head, partly from 
the ligament of Zinn, and partly from a 
small pointed process of bone on the lower 
margin of the sphenoidal fissure. Each 
muscle passes forward in the position im- 
plied by its name, to be inserted, by a ten- 
dinous expansion, into the sclerotic coat of 
the eyeball, about three or four lines from 
the margin of the cornea. Between the two 
heads of the External rectus is a narrow 
interval, through which pass the third, nasal 
branch of the fifth, and sixth nerves, and the ophthalmic vein. Although nearly 
all these muscles present a common origin, and are inserted in a similar manner 
into the sclerotic coat, there are certain differences to be observed in them, as re- 
gards their length and breadth. The Internal rectus is the broadest, the External 
the longest, and the Superior the thinnest and narrowest. 

The Superior Oblique is a fusiform muscle, placed at the upper and inner side 
of the orbit, internal to the Levator palpebrae. It arises about a line above the 
inner margin of the optic foramen, and, passing forwards to the front and mner 
side of the orbit, terminates in a rounded tendon, v/hich passes through a fibro- 
cartilaginous pulley attached to a depression beneath the internal angular process 




■lUa^ 



194 MUSCLES AND FASCIA. 

of the frontal bone, the contiguous surfaces of the tendon and pulley being lined 
by a delicate synovial membrane, and enclosed in a thin fibrous investment. The 
tendon is then reflected backwards and outwards beneath the Superior rectus to 
the outer and posterior part of the globe of the eye, and inserted into the sclerotic 
coat between the Superior and External recti muscles, midway between the cornea 
and entrance of the optic nerve. 

Relations. By its upper surface, with the periosteum covering the roof of the 
orbit, and the fourth nerve. By its under surface, with the nasal nerve, and the 
upper border of the Internal rectus muscle. 

The Inferior Oblique is a thin, narrow muscle, which arises from a depression 
in the orbital plate of the superior maxillary bone, immediately external to the 
lachrymal groove. Passing outwards and backwards beneath the Inferior rectus, 
it terminates in a tendinous expansion, which is inserted into the outer and pos- 
terior part of the sclerotic coat of the eyeball. 

Relations. By its superior surface, with the globe of the eye, and with the 
Inferior rectus. By its under surface, with the periosteum covering the floor of 
the orbit, and with the External rectus. 

Nerves. The Levator palpebrte. Inferior oblique, and all the recti excepting 
the External, are supplied by the third nerve; the Superior oblique by the fourth; 
the External rectus by the sixth. 

Actions. The Levator palpebrse raises the upper eyelid, and is the direct anta- 
gonist of the Orbicularis palpebrarum. The four Recti muscles are attached in 
such a manner to the globe of the eye, that, acting singly, they will turn it either 
upwards, downwards, inwards, or outwards, as expressed by their names. If any 
two Recti act together, they carry the globe of the eye in the diagonal of these 
directions, viz. upwards and inwards, upwards and outwards, downwards and 
inwards, or downwards and outwards. By some anatomists, these muscles have 
been considered the chief agent in adjusting the sight at ditferent distances, by 
compressing the globe, and so lengthening its antero-posterior diameter. The 
Oblique are the 'rotatory muscles' of the eyeball. The Superior oblique acting 
alone, would rotate the globe, so as to carry the pupil outwards and downwards 
to the lower and outer side of the orbit; the Inferior oblique rotating the globe 
in such a direction, as to carry the pupil upwards and outwards to the upper and 
outer angle of the eye. 

Surgical Anatomy. The position and exact point of insertion of the tendons of the 
Internal and External recti muscles into the globe, should be carefully examined from the 
front of the eyeball, as the surgeon is often required to divide one or the other muscle for 
the cure of strabismus. In convergent strabismus, which is the most common form of 
the disease, the eye is turned inwards, requiring the division of the Internal rectus. In 
the divergent form, which is more rare, the eye is turned outwards, the External rectus 
being especially implicated. The deformity produced in either case is considerable, and 
is easily remedied by division of one or the other muscle. This operation is readily 
effected by having the lids well separated by retractors held by an assistant, and the eye- 
ball being drawn outwards by a blunt hook ; the conjunctiva shoidd be raised by a pair of 
forceps, and divided immediately beneath the lower border of the tendon of the Internal 
rectus, a little behind its insertion into the sclerotic ; the submucous areolar tissue is 
then divided, and into the small aperture thus made a blimt hook is passed upwards 
between the muscle and the globe, and the tendon of the muscle and conjunctiva covering 
it divided by a pair of blunt-pointed scissors. Or the tendon may be divided by a sub- 
conjunctival incision, one blade of the scissors being passed upwards between the tendon 
and the conjunctiva, and the other between the tendon and sclerotic. The student, when 
dissecting these muscles, should remove on one side of the subject the conjunctiva from 
the front of the eye, in order to see more accurately the position of these tendons, and 
on the opposite side the operation may be performed. 



NASAL REGION. 



195 



Nasal Region (fig. 131). 

Pyramidalis Nasi. 

Levator Labii Superioris Alaeque Nasi. 

Levator Proprius Alas Nasi Posterior. 

Levator Proprius Ala3 Nasi Anterior. 

Compressor Nasi. 

Compressor Narium Minor. 

Depi'essor Alas Nasi. 

The Pyramidalis Nasi is a small pyramidal slip of muscular fibre, prolonged 
downwards from the Occipito-frontalis upon the bridge of the nose, where it 
becomes tendinous, and blends with the Compressor nasi. As the two muscles 
descend, they diverge, leaving an angular interval between them, which is filled 
up by cellular tissue. 

Relations. By its upper surface, with the skin. By its under surface, with 
the frontal and nasal bones. By its outer border, it is connected with the fleshy 
fibres of the Orbicularis palpebrarum. 

TliQ Levator Labii Superioris Alceque Nasi is a thin triangular muscle, situated 
along the side of the nose, and extending between the inner margin of the orbit 
and upper lip. It arises by a pointed extremity from the upper part of the nasal pro- 
cess of the superior maxillary bone, and passing obliquely downwards and outwards, 
divides into two slips, one of which is inserted into the cartilage of the ala of the 
nose; the other is prolonged into the upper lip, becoming blended with the Orbi- 
cularis and Levator labii proprius. 

Relations. In front, with the integument; and with a small part of the Orbicu- 
laris palpebrarum above. 

Lying upon the superior maxillary bone, beneath this muscle, is a longitudinal 
muscular fasciculus about an inch in length. It is attached by one end near the 
origin of the Compressor naris, and by the other to the nasal process about an inch 
above it; it was described by Albinus as the Musculus 'anomalus,' and by Santorini, 
as the 'Rhomboideus.' 

The Levator Proprius Alee Nasi Posterior (^dilator 7iaris posterior^ is a small 
muscle, which is placed partly beneath the proper elevator of the nose and lip. 
It arises from the margin of the nasal notch of the superior maxilla, and fi'om the 
sesamoid cartilages, and is inserted into the skin near the margin of the nostril. 

The Levator Proprius Alee Nasi Anterior {dilator naris anterior) is a thin, 
delicate fasciculus, passing from the cartilage of the ala of the nose to the integu- 
ment near its margin. This muscle is situated in front of the preceding. 

The Compressor Nasi is a small, thin, triangular muscle, arising by its apex 
from the superior maxillary bone, above and a little external to the incisive fossa; 
its fibres proceed upwards and inwards, expanding into a thin aponeurosis which 
is attached to the fibro-cartilage of the nose, and is continuous on the bridge of 
the nose with that of the muscle of the opposite side, and with the aponeurosis of 
the pyramidalis nasi. 

The Compressor Narium Minor is a small muscle, attached by one end to the 
alar cartilage, and by the other to the integument at the end of the nose. 

The Depressor Alee Nasi {myrtiformis) is a short, radiated muscle, arising from 
the incisive fossa of the superior maxilla; its fibres diverge upwards and outwards, 
the upper, or ascending set, being inserted into the septum, and back part of the 
ala of the nose; the lower, or descending, into the back part of the upper segment 
of the orbicularis. 

Nerves. All the muscles of this group are supplied by the facial nerve. 

Actions. The Pyramidalis nasi draws down the inner angle of the eyebrow; by 
some anatomists it is also considered as an elevator of the ala, and, consequently, 
a dilator of the nose. The Levator labii superioi:is alaeque nasi draws upAvards 
the upper lip and ala of the nose; its most important action is upon the nose, 
which it dilates to a considerable extent. The action of this muscle produces a 

o 2 



ig6 MUSCLES AND FASCIiE. 

marked influence over the countenance, and is the principal agent in the expres- 
sion of contempt. The two Levatores alse nasi are the dilators of the pinna of the 
nose, and the Compressores nasi appear to act as a dilator of the nose rather than 
as a constrictor. The Depressor ala3 nasi is a direct antagonist of the preceding 
muscles, drawing the upper lip and ala of the nose downwards, and thereby con- 
stricting the aperture of the nares. 

Superior Maxillary Region (fig. 131). 

Levator Labii Superioris Proprius. Zygomaticus major. 

Levator Anguli Oris. Zygomaticus minor. 

The Levator Labii Superioris Proprius is a thin muscle of a quadrilateral form. 
It arises from the lower margin of the orbit immediately above the infra-orbital 
foramen, some of its fibres being attached to the superior maxilla, some to the 
malar bone; its fibres converge downwards and inwards to be inserted into the 
muscular substance of the upper lip. 

Relations. By its superficial surface, with the lower segment of the Orbicu- 
laris palpebrarum; below, it is sub-cutaneous. By its deep surface, it conceals the 
origin of the Compressor nasi and Levator anguli oris muscles, and the infra- 
orbital vessels and nerves, as they escape from the infra-orbital foramen. 

The Levator Anguli Oris {musculus caninus) arises by a broad attachment 
from the canine fossa, immediately below the infra-orbital foramen; its fibres 
incline downwards and a little outwards, to be inserted into the angle of the mouth, 
intermingling its fibres with those of the Zygomatici, the Depressor anguli oris, 
and the Orbicularis. 

Relations. Its superficial surface, is covered 'above by the Levator labii supe- 
rioris proprius and the infra-orbital vessels and nerves; below, by the integument. 
By its deep surface, it is in relation with the superior maxilla, the Buccinator, 
and the mucous membrane. 

The Zygomaticus major is a slender cylindrical fasciculus, which arises from 
the malar bone, in front of the zygomatic suture, and, descending obliquely down- 
wards and inwards, is inserted into the angle of the mouth, where it blends with 
the fibres of the Orbicularis and Depressor anguli oris. 

Relations. By its superficial surface, occasionally with the Orbicularis palpe- 
brarum, above; and below, with the sub-cutaneous adipose tissue. By its deep 
surface, with the malar bone, the Masseter and Buccinator muscles. 

The Zygomaticus Mi?ior arises from the malar bone, in front of the Zygomati- 
cus major, immediately behind the maxillary suture, and, passing downwards and 
inwards, is continuous with the outer margin of the Levator labii superioris pro- 
prius. 

Relations. By its superficial surface, with the integument and the Orbicularis 
palpebrarum above. By its deep surface, with the Levator anguli oris. 

Nerves. This group of muscles is supplied by the facial nerve. 

Actions. The Levator labii superioris proprius is the proper elevator of the 
upper lip, carrying it at the same time a little outwards. The Levator anguli 
oris raises the angle of the mouth and draws it inwards; whilst the Zygomatici 
raise the upper lip, and draw it somewhat outwards, as in laughing. 

Inferior Maxillary Region (fig. 131). 
Levator Labii Inferioris. 

Depressor Labii Inferioris (Quadratus menti). 
Depressor Anguli Oris (Triangularis menti). 

Dissection. The Muscles in this region may be dissected by making a vertical incision 
tlirough the integument from the margin of the lower hp to the chin : a second incision 
should then be carried along the margin of the lower jaw as far as the angle, and the integu- 
ment carefully removed in the direction shewn in fig. 130. 

The Levator L^abii Inferioris {^Levator menti) is to be dissected by everting the 



MAXILLARY REGIONS. 



197 



lower lip and raising the mucous membrane. It is a small conical muscular fasci- 
culus, which arises from the incisive fossa, external to the symphysis of the lower 
jaw; its fibres expand downwards and forwards, to be inserted into the integu- 
ment of the chin. 

Relations. On its inner surface, with the buccal mucous membrane; in the 
median line, it is blended with the muscle of the opposite side; and on its outer 
side, with the Depressor labii inferioris. 

The Depressor Labii Inferioris (^Quadratus menti) is a small quadrilateral 
muscle, situated at the outer side of the preceding. It arises from the external 
oblique line of the lower jaw, between the symphysis and mental foramen, and 
passes obliquely upwards and inwards, to be inserted into the integument of the 
lower lip, its fibres blending with the Orbicularis, and with those of its fellow of 
the opposite side. It is continuous with the fibres of the Platysma at its origin. 

Relations. By its superficial surface, with part of the Depressor anguli oris, 
and with the integument, to which it is closely connected. By its deep surface, 
with the mental vessels and nerves, the mucous membrane of the lower lip, the 
labial glands and the Levator labii inferioris, with which it is intimately united. 

The Depressor Anguli Oris is a triangular muscle, arising, by its broad base, 
from the external oblique line of the lower jaw; its fibres pass upwards, to be 
inserted, by a thick and narrow fasciculus, into the angle of the mouth, being con- 
tinuous with the Orbicularis, Levator anguli oris, and Zygomaticus major. 

Relations. By its superficial surface, with the integument. By its deep sur- 
face, with the Depressor labii inferioris, the Platysma, and Buccinator. 

Nerves. This group of muscles is supplied by the facial nerve. 

Actions. The Levator labii inferioris raises the lower lip, and protrudes it for- 
wards; at the same time it wrinkles the integument of the chin. The Depressor 
labii inferioris draws the lower lip directly downwards and a little outwards. The 
Depressor anguli oris depresses the angle of the mouth, being the great antagonist 
to the Levator anguli oris and Zygomaticus major: acting with those muscles, it 
will draw the angle of the mouth directly backwards. 

Inter-Maxillary Region. 
Orbicularis Oris. Buccinator. Risorius. 

Dissection. The dissection of these muscles may be considerably faciUtated by filling the 
cavity of the mouth with tow, so as to distend the cheeks and lips ; the mouth should 
then be closed by a few stitches, and the integument carefully removed from the surface. 

The Orbicularis Oris is a sphincter muscle, elliptic in form, composed of con- 
centric fibres, which surround the orifice of the mouth. It consists of two thick 
semicircular planes of muscular fibre, which surround the oral aperture, and inter- 
lace on either side with those of the Buccinator and other muscles inserted into 
this part. On the free margin of the lips the muscular fibres are continued unin- 
terruptedly from one side to the other, forming a roundish fasciculus of fine pale 
fibres closely approximated. To the outer part of each segment some special fibres 
are added, by which the lips are connected directly with the maxillary bones 
and septum of the nose. The additional fibres for the upper segment consist of 
four bands, two of which (Accessorii orbicularis superioris) arise from the alveo- 
lar border of the superior maxilla, opposite the incisor teeth, and arching out- 
wards on each side, are continuous at the angles of the mouth with the other 
muscles inserted into this part. 

The two remaining muscular slips, called the Naso-labialis, connect the upper lip 
to the septum of the nose: as they descend from the septum, an interval is left 
between them, which corresponds to that left by the divergence of the accessory 
portions of the Orbicularis above described. It is this interval which forms the 
depression seen on the surface of the skin beneath the septum of the nose. 
Those for the lower segment (Accessorii orbicularis inferior) arise from the infe- 



igS MUSCLES AND FASCIA. 

rior maxilla, external to tlie Levator labii inferioris, near the root of the canine 
teeth, being separated from each other by a considerable interval; arching out- 
vp-ards to the angles of the mouth, they join the Buccinator and the other muscles 
attached to this part. 

Relations. By its superficial surface, with the integument, to which it is closely 
connected. By its deep surface, with the mucous membrane, the labial glands, 
and coronary vessels. By its outer circumference, it is blended with the nu- 
merous muscles, which converge to the mouth from various parts of the face. 
Its inner circumference is free, and covered by mucous membrane. 

The Buccinator is a broad, thin muscle, quadrilateral in form, occupying the 
interval between the jaws at the side of the face. It arises, above, from the ex- 
ternal surface of the alveolar process of the upper jaw, between the first molar 
tooth and the tuberosity; below, from the external surface of the alveolar process 
of the lower jaw, corresponding to the three last molar teeth; and, behind, from 
the anterior border of the pterygo-maxillary ligament. The fibres of this muscle 
converge towards the angle of the mouth, where those occupying its centre inter- 
siect each other, the inferior fibres being continuous with the upper segment of the 
Orbicularis oris; the superior fibres, with the inferior segment; but the upper 
and lower fibres continue forward uninterruptedly into the corresponding segment 
of the lip. 

Relations. By its superficial surface, behind, with a large mass of fat, which 
separates it from the ramus of the lower jaw, the Massetei", and a small portion of 
the Temporal muscle; anteriorly, Avith the Zygomaticus, Risorius, Levator anguli 
oris. Depressor anguli oris, and Stenon's duct, which pierces it opposite the second 
molar tooth of the upper jaw; the transverse facial artery and vein lie parallel 
with its fibres, and the facial artery and vein cross it from below upwards; it is 
also crossed by the branches of the facial and buccal nerves. By its internal sur- 
face, with the buccal glands and mucous membrane of the mouth. 

The Pterygo-maxillary ligament separates the Buccinator muscle from the 
Superior constrictor of the pharynx. It is a tendinous band, attached by one 
extremity to the apex of the internal pterygoid plate, and by the other, to the 
posterior extremity of the internal oblique line of the lower jaw. Its inner sur- 
face corresponds to the cavity of the mouth, and is lined by mucous membrane. 
Its outer surface is separated from the ramus of the jaw by a quantity of adipose 
tissue. Its posterior border gives attachment to the Superior constrictor of the 
pharynx; its anterior border, to the fibres of the Buccinator. 

The Risorius {Santorini) consists of a delicate bundle of muscular fibres, which 
arises in the fascia over the Masseter muscle, and passing horizontally forwards, 
is inserted into the angle of the mouth, joining with the fibres of the Depressor 
anguli oris. It is placed superficial to the Platysma, and is broadest at its outer 
extremity. This muscle varies much in its size and form. 

Nerves. The Orbicularis oris is supplied by the facial, the Buccinator by the 
facial and buccal branch of the inferior maxillary nerve. 

Actions. The Orbicularis oris is the direct antagonist of all those muscles which 
converge to the lips from the various parts of the face, its action producing the 
direct closure of the lips; and its forcible action throwing the integument into 
wrinkles, on account of the firm connection between the latter and the surface of 
the muscle. The Buccinators contract and compress the cheeks, so that, during 
the process of mastication, the food is kept under the immediate pressure of the 
teeth. 

Temporo-Maxillaky Region (fig. 134). 

Masseter. Temporal. 

The Masseter muscle has been already exposed by the removal of the integu- 
ment from the side of the face (fig. 131). 

The Blasseter is a short thick muscle, somewhat quadrilateral in form, consisting 



TEMPORO-MAXILLARY REGION. 



199 



of two portions, superficial and deep. The superficial portion, the largest part of 
the muscle, arises by a thick tendinous aponeurosis from the malar process of the 
superior maxilla, and from the anterior two-thirds of the lower border of the zy- 
gomatic arch: its fibres pass downwards and backwards, to be inserted into the 
lower half of the ramus and angle of the lower jaw. The deep portion is much 
smaller, more muscular in texture, and the direction of its fibres is forwards; it 
arises from the posterior third of the lower border and whole of the inner surface 
of the zygomatic arch and is inserted into the upper half of the ramus and coro- 
noid process of the jaw. The deep portion of the muscle is partly concealed, in 
front, by the superficial portion; behind, it is covered by the parotid gland. The 
fibres of the two portions are united at their insertion. 

Relations. By its superficial surface, with the integument; above, with the 
Orbicularis palpebrarum and Zygomaticus major; and has passing across it trans- 
versely, Stenon's duct, the branches of the facial nerve, and the transverse facial 
artery. By its deep surface, with the ramus of the jaw, the Temporal muscle, 
and the Buccinator, from which it is separated by a mass of fat. Its posterior 
margin is covered by the parotid gland. Its anterior margin is in relation, below, 
with the facial artery. 

At this stage of the dissection, the temporal fascia is seen covering in the Tem- 
poral muscle. It is a strong aponeurotic investment, affording attachment, by its 
inner surface, to the superficial fibres of this muscle. Above, it is a single uniform 
layer, attached to the entire extent of the temporal ridge; but below, where it is 
attached to the zygoma, it consists of two layers, one of which is inserted into 
the outer, and the other to the inner border of the zygomatic arch. A small 
quantity of fat, and the orbital branch of the temporal artery, are contained be- 
tween these. It is covered, on its outer surface, by the aponeurosis of the 
Occipito frontalis, the Orbicularis palpebrarum, and Attollens and Attrahens aurem 
muscles; the temporal artery and vein, and ascending branches of the temporal 
nerves, cross it from below upwards. 



[ 34. — The Temporal Muscle, the Zygoma and Masseter having been removed. 




Dissection. In order to expose the Temporal muscle, this fascia should be removed : this 
may be eflfected by separating it at its attachment along the upper border of the zygoma, 
and dissecting it upwards from the surface of the muscle. The zygomatic arch should 



200 



MUSCLES AND FASCIA. 



then be divided in front at its junction with the malar bono, and, behind, near the exter- 
nal auditory meatus, and drawn downwards with the masseter, which should be detached 
from its insertion into the ramus and angle of the jaw. The whole extent of the Temporal 
muscle is then exposed. 

The Temporal is a broad radiating muscle, situated at the side of the head, and 
occupying the entire extent of the temporal fossa. It arises from the whole of 
the temporal fossa, which extends from the external angular process of the frontal 
in front, to the mastoid portion of the temporal behind, and from the curved line 
on the frontal and parietal bones above, to the pterygoid ridge on the great wing 
of the sphenoid below. It is also attached to the inner surface of the temporal 
fascia. Its fibres converge as they descend, the anterior passing obliquely back- 
wards, the posterior obliquely forwards, and the middle fibres descend vertically, 
and terminate in an aponeurosis, the fibres of wliich, radiated at its commence- 
ment, converge into a thick and flat tendon, which is inserted into the inner surface, 
apex, and anterior border of the coronoid process of the lower jaw. 

Relations. By its superficial surface, with the integument, the temporal fascia, 
aponeurosis of the Occipito-frontalis, the Attollens and Attrahens aurem muscles, 
the temporal vessels and nerves, the zygoma and Masseter. By its deep surface, 
with the temporal fossa, the External pterygoid and part of the Buccinator muscles, 
the internal maxillary artery, and its deep temporal branches. 

Nerves. Both muscles are supplied by the inferior maxillary nerve. 

10. PtERTGO-M AXILLARY REGION. 

Internal Pterygoid. External Pterygoid. 

Dissection. The Temporal muscle having been examined, the muscles in the pterygo- 
maxillary region may be exposed by sawing through the base of the coronoid process, and 
drawing it upwards, together with the Temporal muscle, which should be detached from 
the surface of the temporal fossa. Divide the ramus of the jaw just below the condyle, 
and also, by a transverse incision extending across the commencement of its lower third, 
just above the dental foramen, remove the fragment, and the Pterygoid muscles will be 
exposed. 

1 35- — The Pterygoid Muscles, the Zygomatic Arch and a portion of the 
Eamus of the Jaw having been removed. 




The Internal Pterygoid is a thick quadrilateral muscle, and resembles the 
Masseter in form, structure, and in the direction of its fibres. It arises from the 



I 



PTERYGO-MAXILLARY REGION. 201 

pterygoid fossa, its fibres being attached to the inner surface of the external ptery- 
goid plate of the sphenoid, and to the grooved surface of tlie tuberosity of the 
palate bone; its fibres descend downwards, outwards, and backwards, to be inserted, 
by strong tendinous lamina3, into the lower and back part of the inner side of 
the ramus and angle of the lower jaw. 

Relations. By its external surface, with the ramus of the lower jaw, from which 
it is separated at its upper part by the External Pterygoid, the internal lateral liga- 
ment, the internal maxillary artery, and the superior dental vessels and nerves. 
By its internal surjace, with the Tensor palati, being separated from the Superior 
constrictor of the pharynx by a cellular interval. 

The External Pterygoid is a short thick muscle, somewhat conical in form, 
being broader at its origin than at its insertion. The two extremities of the 
muscle are tendinous, the intervening portion being fleshy. It arises by two 
heads, separated by a cellular interval. The upper head is attached to the ptery- 
goid ridge on the great ala of the sphenoid, and the portion of bone included be- 
tween it and the base of the external pterygoid plate; the other, the larger fasci- 
culus, from the outer sur'face of the external pterygoid plate, and part of the 
tuberosity of the palate bone. From this origin, its fibres proceed horizontally 
backwards and outwards, to be inserted into a depression on the anterior part of 
the neck of the condyle of the lower jaw, and into the corresponding part of 
the interarticular fibro-cartilage. 

Relations. By its external surface, with the ramus of the lower jaw, the inter- 
nal maxillary artery, which crosses it, the tendon of the Temporal muscle, and 
the Masseter. By its internal surface, it rests against the upper part of the 
Internal pterygoid, the internal lateral ligament, the middle meningeal artery, 
and inferior maxillary nerve; by its upper border it is in relation with the 
temporal and masseteric branches of the inferior maxillary nerve. 

Nerves. These muscles are supplied by the inferior maxillary nerve. 

Actions. The Temporal, Masseter, and Internal pterygoid raise the lower jaw 
against the upper with great force. The two latter muscles, from the obliquity 
in the direction of their fibres, assist the External pterygoid in drawing the 
lower jaw forwards upon the upper, the jaw being drawn back again by the deep 
fibres of the Masseter, and posterior fibres of the Temporal. The External pte- 
rygoid muscles are the direct agents in the trituration of the food, drawing the 
lower jaw directly forwards, so as to make the lower teeth project beyond the 
upper. If the muscle of one side acts, the corresponding side of the jaw is drawn 
forwards, and the other condyle remaining fixed, the symphysis deviates to the 
opposite side. The alternation of these movements on the two sides, produces 
trituration. 



MUSCLES AND FASCIA OF THE NECK. 

The muscles of the Neck may be arranged into groups, corresponding with the 
region in which they are situated. 
These groups are nine in number. 

1. Superficial Region. 6. Muscles of the Soft Palate. 

2. Depressors of the Os Hyoides 7. Muscles of the Anterior Ver- 

and Larynx. tebral Region. 

3. Elevators of the Os Hyoides o ^^^ , ^ .1 t ^ i tt 

and Lar nx ^" ^"^^^^^ ^^ *^^ Lateral Ver- 

4. Muscles of &e Tongue. *^^^"^^ ^^S^^^' 

9. Muscles of the Larynx. 

5. Muscles of the Pharynx. 



202 



MUSCLES AND FASCIA. 



I. Superficial Region. 

Platysma myoides. 
Sterno-cleido-mastoideus. 

Infra-hyoid Regio7i. 

2. Depressors of the Os Hyoides and 

Larynx. 

Sterno-hyoid. 
Sterno-thyroid. 
Thyro-hyoid. 
Omo-hyoid. 

Supra-hyoid Region. 

3. Elevators of the Os Hyoides and 

Larynx. 

Digastric. 
Stylo-hyoid. 
Mylo-hyoid. 
Genio-hyoid. 

Lingual Region. 

4. 3Iuscles of the Tongue. 

Genio-hyo-glossus. 

Hyo-glossus. 

Lingualis. 

Stylo-glossus. 

Palato-fflossus. 



5. Muscles of the Pharynx. 
Constrictor inferior. 
Constrictor medius. 
Constrictor superior. 
Stylo-pharyngeus. 
Palato-pharyngeus. 

6. Muscles of the Soft Palate. 
Levator palati. 
Tensor palati. 
Azygos uvulae. 
Palato-glossus. 
Palato-pharyngeus. 

7. Muscles of the Anterior Vertebral 

Region. 
Rectus capitis anticus major. 
Rectus capitis anticus minor. 
Rectus lateralis. 
Longus colli. 

8. Muscles of the Lateral Vertebral 

Region. 
Scalenus anticus. 
Scalenus medius. 
Scalenus posticus. 

'9. Muscles of the Larynx. 
Included in the description of the 
Larynx. 



Superficial Region, (fig. 131)- 



Platysma Myoides. 



Sterno-Cleido-Mastoid. 



Dissection. A block having been placed at the back of the neck, and the face turned to 
the side opposite to that to be dissected, so as to place the parts upon the stretch, two 
transverse incisions are to be made: one from the chin, along the margin of the lower jaw, 
to the mastoid process ; and the other along the upper border of the clavicle. These are 
to be connected by an oblique incision made in the course of the Sterno-mastoid muscle, 
from the mastoid process to the sternum ; the two flaps of integument having been 
removed in the direction shewn in fig. 130, the superficial fascia will be exposed. 

The Superficial Cervical Fascia is exposed on the removal of the integument 
from the side of the neck; it is an extremely thin aponeurotic lamina, which is 
hardly demonstrable as a separate membrane. Beneath it is found the Platysma 
myoides muscle, the external jugular vein, and some superficial branches of the 
cervical plexus of nerves. 

The Platysma Myoides is a broad thin flat plane of muscular fibres, of an 
irregular quadrilateral form, placed immediately beneath the skin on each side of 
the neck. It arises from the clavicle and acroinion, and from the fascia covering 
the upper part of the Pectoral, Deltoid, and Trapezius muscles; its fibres proceed 
obliquely upwards and inwards along the side of the neck, to be inserted into the 
lower jaw beneath the external obliqvie line, some fibres passing forwards to the 
angle of the mouth, and others becoming lost in the cellular tissue of the face. 
The most anterior fibres interlace, in front of the jaw, with the fibres of the 
muscle of the opposite side; those next in order become blended with the Depres- 
sor labii inferioris and the Depressor anguli oris; others are prolonged upon the 
side of the cheek, and interlace, near the angle of the mouth, with the muscles in 
this situation, and may occasionally be traced to the Zygomatic muscles, or to the 



SUPERFICIAL CERVICAL REGION. 



203 



margin of the Orbicularis palpebrarum. The most posterior fibres, which are 
lost in the skin at the side of the face, are the rudiments of a remarkable acces- 
sory fasciculus, the Risorius Santorini, already described. Beneath this muscle, 
the external jugular vein may be seen descending from the angle of the jaw to 
the clavicle. It is essential to remember the direction of the fibres of the Pla- 
tysma, in connection with the operation of bleeding from this vessel; for if the 
point of the lancet is introduced in the direction of the fibres of this muscle, the 
orifice made will be filled up by its contraction, and blood will not flow; but if 
the incision is made in a direction opposite to that of the course of the fibres, 
they will retract, and expose the orifice in the vein, and so facilitate the flow of 
blood. This operation is now, however, very rarely performed. 

Relations. By its extertial surface, with the integument, to which it is united 
closely below, but more loosely above. By its internal surface, below the cla- 
vicle which it covers, with the Pectoralis major. Deltoid, and Trapezius. In the 
neck, with the external and anterior jugular veins, the deep cervical fascia, the 
superficial cervical plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, and 
Digastric muscles. In front of the Sterno-mastoid, it covers the sheath of the 
carotid vessels; and behind it, the Scaleni muscles and the nerves of the brachial 
plexus. On the face, it is in relation with the parotid gland, the facial artery 
and vein, and the Masseter and Buccinator muscles. 

The Deep Cervical Fascia is exposed on the removal of the Platysma myoides. 
It is a strong fibrous layer, which invests the muscles of the neck, and encloses 
the vessels and nerves. It commences, as an extremely thin layer, at the back 
part of the neck, where it is attached to the spinous processes of the cervical 
vertebrae, and to the ligamentum nuchse; and, passing forwards to the posterior 
border of the Sterno-mastoid muscle, divides into two layers, one of which passes 
in front, and the other behind it. These join again at its anterior border; and, 
being continued forwards to the front of the neck, blend with the fascia of the 
opposite side. The superficial layer of the deep cervical fascia (that which passes 
in front of the Sterno-mastoid), if traced upwards, is found to pass across the 
parotid gland and Masseter muscle, forming the parotid and masseteric fascias, 
and is attached to the lower border of the Zygoma, and more anteriorly to the 
lower border of the body of the jaw; if the same layer is traced downwards, it is 
seen to pass to the upper border of the clavicle and sternum, being pierced just 
above the former bone for the external jugular vein. In the middle line of the 
neck, this layer is thin above, and connected to the hyoid bone; but it becomes 
thicker below, and divides, just below the thyroid gland, into two layers, the more 
superficial of which is attached to the upper border of the sternum and inter- 
clavicular ligament; the deeper and stronger layer is connected to the posterior 
border of that bone, covering in the Sterno-hyoid and Sterno-thyroid muscles. 
Between these two layers is a little areolar tissue and fat, and occasionally a 
small lymphatic gland. The deep layer of the cervical fascia (that which lies 
behind the postei'ior surface of the Sterno-mastoid) sends numerous prolongations, 
which invest the muscles and vessels of the neck; if traced upwards, a process of 
this fascia, of extreme density, passes behind and to the inner side of the parotid 
gland, and is attached to the base of the styloid process and angle of the lower 
jaw, forming the stylo-maxillary ligament; if traced downwards and outwards, it 
will be found to enclose the posterior belly of the Omo-hyoid muscle, binding it 
down by a distinct process, which descends to be inserted into the clavicle and 
cartilage of the first rib. The deep layer of the cervical fascia also assists in 
forming the sheath which encloses the common carotid artery, internal jugular 
vein, and pneumogastric nerve. There are fibrous septa intervening between each 
of these parts, which, however, are included together in one common investment. 
More internally, a thin layer is continued across the trachea and thyroid gland, 
beneath the Sterno-thyroid muscles; and at the root of the neck this may be 
traced, over the large vessels, to be continuous with the fibrous layer of the 
pericardium. 



204 



MUSCLES AND FASCIA. 



The Sterno-Cleido- Mastoid (fig. 136) is a large thick muscle which passes 
obliquely across the side of the neck, being enclosed between the two layers of 
the deep cervical fascia. It is thick and narrow at its central part, but is broader 
and thinner at each extremity. It arises, by two distinct heads, from the sternum 
and clavicle. The sternal portion arises by a rounded fasciculus, tendinous in 
front, fleshy behind, from the upper and anterior part of the first piece of the 
sternum, and is directed upwards and backwards. The clavicular portion arises 
from the inner third of the upper surface of the clavicle, being composed of fleshy 
and aponeurotic fibres; it is directed perpendicularly upwards. These two por- 
tions are separated from one another, at their origin, by a triangular cellular 
interval; but become gradually blended, below the middle of the neck, into a 
thick rounded muscle, which is inserted, by a strong aponeurosis, into the outer 
surface of the mastoid process, from the apex to its superior border, and into the 

136. — Muscles of the Neck, and Boundaries of the Triangles, 




outer two- thirds of the superior curved line of the occipital bone. This muscle 
varies much in its extent of attachment to the' clavicle: in one case it may be as 
narrow as the sternal portion; in another, as much as three inches in breadth. 
When the clavicular origin is broad, it is occasionally subdivided into numerous 
slips, separated by narrow intervals. More rarely the corresponding margins of 
the Sterno-mastoid and Trapezius have been found in contact. In the application 
of a ligature to the third part of the subclavian artery, it will be necessary, where 
the muscles have an arrangement similar to that above mentioned, to divide a 
portion of one or of both, in order to facilitate the operation. 

This muscle serves to divide the large quadrilateral space at the side of the 
neck into two large triangles, an anterior and a posterior. The boundaries of the 
great anterior triangle being, in front, the median line of the neck ; above, the 



INFRA-IIYOID REGION. 



205 



lower border of the body of the jaw, and an imaginary line drawn from the angle 
of the jaw to the mastoid process; behind, the anterior border of tlie Sterno-mastoid 
muscle. The boundaries of the great posterior triangle are, in front, the poste- 
rior border of the Sterno-mastoid; below, the upper border of the clavicle; behind, 
the anterior margin of the Trapezius. 

The anterior edge of this muscle forms a very prominent ridge beneath the 
skin, which forms a gviide to the surgeon in making the incisions for ligature of 
the common carotid artery, and for cesophagotomy. 

Relations. By its superficial surface, with the integument and Platysma, 
from which it is separated by the external jugular vein, the superficial branches 
of the cervical plexus, and the anterior layer of the deep cervical fascia. By its 
deep surface, it rests on the deep layer of the cervical fascia, the sterno- clavicular 
articulation, the Sterno-hyoid, Sterno-thyroid, and Omo-hyoid muscles, the poste- 
rior belly of the Digastric, Levator anguli scapula, the Splenius and Scaleni 
muscles. Below, with the lower part of the common carotid artery, internal 
jugular vein, pneumogastric, descendens noni, and communicans noni nerves, and 
with the deep lymphatic glands; with the spinal accessory nerve, which pierces 
its upper third, the cervical plexus, the sympathetic nerve, and the parotid gland. 

Nerves. The Platysma-myoides is supplied by the facial and superficial cer- 
vical nerves. The Sterno-cleido-mastoid by the spinal accessory and deep branches 
of the cervical plexus. 

Actions. The Platysma-myoides produces a slight wrinkling of the surface of 
the skin of the neck, in a vertical direction, when the entire muscle is brought 
into action. Its anterior portion, the thickest part of the muscle, depresses the 
lower jaw; it also serves to draw down the lower lip and angle of the mouth on 
each side, being one of the chief agents in the expression of melancholy. The 
accessory transverse fibres draw the angle of the lips upwards and outwards, as 
in laughing. The Sterno-mastoid muscles, when both are brought into action, 
serve to depress the head upon the neck, and the neck upon the chest. Either 
muscle, acting singly, flexes the head, and (combined with the Splenius) draws 
it towards the shoulder of the same side, and rotates it so as to carry the face 
towards the opposite side. 

Infra-Hyoid Region (figs, 136, 137). 
Depressors of the Os Hyoides and Larynx. 

Sterno-Hyoid. Thyro-Hyoid. 

Sterno-Thyroid. Omo-Hyoid. 

Dissection. The muscles in this region may be exposed by removing the deep fascia 
from the front of the neck. In order to see the entire extent of the Omo-hyoid, it is 
necessary to divide the Sterno-mastoid at its centre, and turn its ends aside, and to detach 
the Trapezius from the clavicle and scapula, if this muscle has been previously dissected ; 
but not otherwise. 

The Sterno-Hyoid is a thin, narrow, ribband-like muscle, which arises from 
the inner extremity of the clavicle, and the upper and posterior part of the first 
piece of the sternum; and, passing upwards and inwards, is inserted, by short 
tendinous fibres, into the lower border of the body of the os hyoides. This 
muscle is separated, below, from its fellow by a considerable interval; they approach 
one another in the middle of their course, and again diverge as they ascend. It 
often presents, immediately above its origin, a transverse tendinous intersection, 
analogous to those in the Rectus abdominis. 

Variations in Origin. The origin of this muscle presents many variations. 
Thus, it may be found to arise from the inner extremity of the clavicle, and the 
posterior sterno-clavicular ligament ; or from the sternum and this ligament ; 
from either bone alone, or from all these parts; and occasionally has a fasciculus 
connected with the cartilage of the first rib. 



206 



MUSCLES AND FASCIA. 



Relations. By its superficial surface, below, with the sternum, sternal end of 
the clavicle, and the Sterno-mastoid; and, above, with the Platysma and deep 
cervical fascia. By its deep surface, with the Sterno-thyroid, Crico-thyroid, and 
Thyro-hyoid muscles, the thyroid gland, the superior thyroid artery, the crico- 
thyroid and thyro-hyoid membranes. 

The Sterno- Thyroid is situated immediately beneath the preceding muscle, but 
is shorter and broader than it. It arises from the posterior surface of the first 
bone of the sternum, beneath the origin of the Sterno-hyoid, and occasionally 
from the edge of the cartilage of the first rib; and is inserted into the oblique line 
on the side of the ala of the thyroid cartilage. These muscles are in close contact 



137. — Muscles of the Neck. Anterior View. 







at the lower part of the neck by their inner margins; and are frequently traversed 
by transverse or oblique tendinous intersections, analogous to those in the Rectus 
abdominis. 

Variations. This muscle, at its insertion, is liable to some variations. A lateral 
prolongation is sometimes continued as far as the os hyoides; and it is sometimes 
continuous with the Thyro-hyoideus and Inferior constrictor of the pharynx. 

Relations. By its anterior surface, with the Sterno-hyoid, Omo-hyoid, and 
Sterno-mastoid. By its posterior surface, from below upwards, with the trachea, 
vena innominata, common carotid (and on the right side the arteria innominata), 
the thyroid gland and its vessels, and the lower part of the larynx. The middle 
thyroid vein lies along its inner border, this should be remembered in the operation 
of tracheotomy. 

The Thyro-Hyoid is a small quadrilateral muscle, appearing like a continuation 
of the Sterno-thyroid. It arises from the oblique line on the side of the thyroid 
cartilage, and passes vertically upwards to be inserted into the lower border of 
the body, and greater cornu of the hyoid bone. 



SUPRA-HYOID REGION. 



207 



Relations. By its external surface, with the Sterno-hyoid and Omo-hyoid 
muscles. By its internal surface, with the thyroid cartilage, and thyro-hyoid 
membrane. Interposed between this muscle and the membrane, is the superior 
laryngeal nerve and artery. 

The Omo-hyoid passes across the side of the neck, from the scapula to the 
hyoid bone. It consists of two fleshy bellies, united by a central tendon. It 
arises from the upper border of the scapula, and occasionally from the transverse 
ligament which crosses the supra-scapular notch; its extent of attachment to the 
scapula varying from a few lines to an inch. From this origin, the posterior 
belly forms a flat, narrow fasciculus, which inclines forwards across the lower 
part of the neck; behind the Sterno-mastoid muscle, where it becomes tendinous, 
it changes its direction, forming an obtuse angle, and ascends almost vertically 
upwards, close to the outer border of the Sterno-hyoid, to be inserted into the 
lower border of the body of the os hyoides, just external to the insertion of the 
Sterno-hyoid. The tendon of this muscle, which much varies in its length and 
form in different subjects, is held in its position between two lamella of the deep 
cervical fascia, which include it in a sheath, and are prolonged down to be 
attached to the cartilage of the first rib. It is by this means that the angular 
form of the muscle is maintained. 

This muscle subdivides each of the two large triangles at the side of the neck, 
formed by the Sterno-mastoid, into two smaller triangles. The two posterior 
ones being the posterior superior or sub-occipital, and the posterior inferior or 
subclavian; the two anterior, the anterior superior or superior carotid, and the 
anterior inferior or inferior carotid triangle. 

Relations. By its superficial surface, with the Trapezius, Subclavius, the 
clavicle, the Sterno-mastoid, deep cervical fascia, Platysma, and integument. By 
its deep surface, with the Scaleni, brachial plexus, sheath of the common carotid 
artery, and internal jugular vein, the descendens noni nerve, Sterno-thyroid and 
Thyro-hyoid muscles. 

Nerves. All the muscles of this group, excepting the Thyro-hyoid, which is 
supplied by the hypo-glossal, receive their nerves from the loop of communication 
between the descendens and communicans noni. 

Actions. These muscles serve to depress the larynx and hyoid bone, after these 
parts have been drawn up with the pharynx in the act of deglutition. The Omo- 
hyoid muscles not only depress the hyoid bone, but carry it backwards, and to 
one or the other side. These muscles also are tensors of the cervical fascia. The 
Thyro-hyoid may act as an elevator of the thyroid cartilage, when the hyoid bone 
ascends, drawing upwards the thyroid cartilage behind the os hyoides. 



Supra-Hyoid Region (figs. 136, 137). 

Elevators of the Os Hyoides — Depressors of the Lower Jaw. 

Digastricus. Mylo-Hyoid. 

Stylo-Hyoid. Genio-Hyoid. 

Dissection. To dissect these muscles, a block should be placed beneath the back of the 
neck, and the head drawn backwards, and retained in that position. On the removal of 
the deep fascia, the muscles are at once exposed. 

The Digastric, so called from its consisting of two fleshy bellies united by an 
intermediate rounded tendon, is a small muscle, situated immediately beneath the 
side of the body of the lower jaw, and extending, in a curved form, from the side 
of the head to the symphysis of the jaw. The posterior belly, longer than the 
anterior, arises from the digastric groove on the inner side of the mastoid process 
of the temporal bone, and passes downwards, forwards, and inwards. The ante- 
rior belly, being reflected upwards and forwards, is inserted into a depression 



2o8 MUSCLES AND FASCIA. 

on the inner side of the lower border of the jaw, close to the symphysis. The 
tendon of this muscle perforates the Stylo-hyoid, and is held in connection 
with the side of the body of the hyoid bone by an aponeurotic loop, lined by a 
synovial membrane. A broad aponeurotic layer is given oif from the tendon of 
the digastric on each side, which is attached to the hyoid bone: this is termed the 
supra-hyoid aponeurosis. It forms a strong layer of fascia between the anterior 
portion of the two muscles, and forms a firm investment for the other muscles of 
the supra-hyoid region, which lie beneath it. 

The Digastric muscle divides the anterior superior triangle of the neck into 
two smaller triangles; the upper, or sub-maxillary, being bounded above by the 
lower jaw; below, by the two bellies of the Digastric muscle: the lower, or supe- 
rior carotid triangle, being bounded above by the posterior belly of the Digastric; 
behind, by the Sterno-mastoid; below, by the Omb-hyoid. (fig. 136). 

Relations. By its superficial surface, with the Platysma, Sterno-mastoid, part 
of the Stylo-hyoid muscle, and the parotid and sub-maxillary glands. By its deep 
surface, its anterior belly lies on the Mylo-hyoid, the posterior belly lies on the 
Stylo-glossus, Stylo-pharyngeus, and Hyo-glossus muscles, the external carotid 
and its lingual and facial branches, the internal carotid, internal jugular vein, and 
hypoglossal nerve. 

The Stylo-Hyoid is a small, slender muscle, lying in front of, and above, the 
posterior belly of the Digastric. It arises from the middle of the outer surface Of 
the styloid process; and, passing downwards and forwards, is inserted into the 
body of the hyoid bone, just at its junction with the greater cornu, and imme- 
diately above the Omo-hyoid. 

This muscle is perforated near its insertion by the tendon of the Digastric 
muscle. 

Relations. By its superficial surface, with the Sterno-mastoid and Digastric 
muscles, the parotid and submaxillary glands. Its deep surface has the same 
relations as the posterior belly of the Digastric. 

Dissection. The Digastric and Stylo-hyoid muscles should be removed, in order to expose 
the next muscle. 

The Mylo-Hyoid is a flat triangular plane of muscular fibre, situated imme- 
diately beneath the anterior belly of the Digastric, and forming, with its fellow 
of the opposite side, a muscular floor for the cavity of the mouth. It arises from 
the whole length of the mylo-hyoid ridge, from the symphysis in front, to the last 
molar tooth behind. The posterior fibres pass obliquely forwards, to be inserted 
into the body of the os hyoides. The middle and anterior fibres are inserted into 
the median fibrous raphe, where they join at an angle with the fibres of the oppo- 
site muscle. This median raphe is sometimes wanting; the muscular fibres of the 
two sides are then directly continuous with one another. 

Relations. By its superficial or inferior surface with the Platysma, the ante- 
rior belly of the Digastric, the supra-hyoid fascia, the submaxillary gland, and 
submental vessels. By its deep or superior surface, with the Genio-hyoid, part 
of the Hyo-glossus, and Stylo-glossus muscles, the lingual and gustatory nerves, 
the sublingual gland, and the buccal mucous membrane. Wharton's duct curves 
around its posterior border in its passage to the mouth. 

Dissection. The Mylo-hyoid should now be removed, in order to espose the muscles 
which lie beneath; this is effected by detaching it from its attachments to the hyoid bone 
and jaw, and separating it by a vertical incision from its fellow of the opposite side. 

The Genio-Hyoid is a narrow slender muscle, situated immediately beneath the 
inner border of the preceding. It arises from the inferior genial tubercle on the 
inner side of the symphysis of the lower jaw, and descends downwards and back- 
wards, to be inserted into the anterior surface of the body of the os hyoides. This 
muscle lies in close contact with its fellow of the opposite side, and increases 
slightly in breadth as it descends. 

Relations. It lies between the Mylo-hyoid- and the Genio-hyo-glossus muscles. 



LINGUAL REGION. 



209 



Nerves. The Digastric is supplied, its anterior belly, by the mylo-hyoid branch 
of the inferior dental; its posterior belly, by the facial and glosso-pharyngeal; the 
Stylo-hyoid, by the facial and glosso-pharyngeal; the Mylo-hyoid, by the mylo- 
hyoid branch of the inferior dental; the Genio-hyoid, by the lingual. 

Actiofis. This group of muscles performs two very important actions. They 
raise the hyoid bone, and with it the base of the tongue, during the act of deglu- 
tition ; or, when the hyoid bone is fixed by its depressors and those of the larynx, 
they depress the lower jaw. During the first act of deglutition, when the mass is 
being driven from the mouth into the pharynx, the hyoid bone, and with it the 
tongue, is carried upwards and forwards by the anterior belly of the Digastric, the 
Mylo-hyoid, and Genio-hyoid muscles. In the second act, when the mass is passing, 
the direct elevation of the hyoid bone takes place by the combined action of all 
the muscles; and after the food has passed, the hyoid bone is carried upwards and 
backwards by the posterior belly of the Digastric and Stylo-hyoid muscles, which 
assists in preventing the return of the morsel into the cavity of the movith. 



Lingual Region. 

Genio-Hyo-Glossus. 
Hyo-Glossus. 

Palato-Glossus. 



Lingualis. 
Stylo- Glossus. 



Dissection. After completing the dissection of the preceding muscles, saw through the 
lower jaw just external to the symphysis. The tongue should then be drawn forwards with 
a hook, and its muscles, which are thus put on the stretch, may be examined 

138. — Muscles of the Tongue. Left Side. 




The Genio-Hyo-Glossus has received its name from its triple attachment 
to the chin, hyoid bone, and tongue; it is a thin, flat, triangular muscle, placed 
vertically in the middle line, its apex corresponding with its point of attachment 
to the lower jaw, its base with its insertion into the tongue and hyoid bone. It 



210 MUSCLES AND FASCIiE. 

arises by a short tendon from the superior genial tubercle on the inner side of the 
symphysis of the chin, immediately above the Genio-hyoid; from this point the 
muscle spreads out in a fan-like form, the inferior fibres passing downwards, to be 
inserted into the upper part of the body of the hyoid bone, a few being continued 
into the side of the pharynx; the middle fibres passing backwards, and the an- 
terior ones upwards and forwards, to be attached to the whole length of the 
under surface of the tongue, from the base to the apex. 

Relations. By its internal surface, it is in contact with its fellow of the opposite 
side, from which it is separated, at the back part of the tongue, by a fibro-cellular 
structure, which extends forwards through the middle of the organ. By its 
external surface, with the Lingualis, Hyo-glossus, and Stylo-glossus, the lingual 
artery and hypoglossal nerve, the gustatory nerve, and the sublingual gland. 
By its upper border, with the mucous membrane of the floor of the mouth. By its 
lower border, with the Genio-hyoid. 

The Hyo- Glossus is a thin, flat, quadrilateral plane of muscular fibres, arising 
from the body, the lesser cornu, and whole length of the greater cornu of the 
hyoid bone, and passing almost vertically upwards, is inserted into the side of the 
tongue, between the Stylo-glossus and Lingualis. Those fibres of this muscle 
which arise from the body are directed upwards and backwards, overlapping those 
from the greater cornu, which are directed obliquely forwards. Those from the 
lesser cornu extend forwards and outwards along the side of the tongue, under 
cover of the portion arising from the body. 

The difference in the direction of the fibres of this muscle, and their separate 
origin from different segments of the hyoid bone, led Albinus and other anato- 
mists to describe it as three muscles, under the names of the Basio-glossus, the 
Cerato-glossus, and the Chondro-glossus. 

Relations. By its external surface, with the Digastric, the Stylo-hyoid, Stylo- 
glossus, and Mylo-hyoid muscles, the gustatory and hypoglossal nerves, Wharton's 
duct, and the sublingual gland. By its deep surface, with the Genio-hyo-glossus, 
Lingualis, and the origin of the middle Constrictor muscle of the pharynx, the 
lingual artery, and the glosso-pharyngeal nerve. 

The Lingualis is a longitudinal band of muscular fibres, situated on the under 
surface of the tongue, lying in the interval between the Hyo-glossus and the 
Genio-hyo-glossus, and extending from the base to the apex of that organ. Pos- 
teriorly, some of its fibres are lost in the base of the tongue, and others are 
attached to the hyoid bone. It blends with the fibres of the Stylo-glossus, in 
front of the Hyo-glossus, and is continued forwards as far as the apex of the 
tongue. It is in relation, by its under surface, with the ranine artery. 

The Stylo- Glossus, the shortest and smallest of the three styloid muscles, 
arises from the anterior and outer side of the styloid process, near its centre, and 
from the stylo-maxillary ligament, to Avhich its fibres in most cases are attached 
by a thin aponeurosis. Passing downwards and forwards, so as to become nearly 
horizontal in its direction, it divides upon the side of the tongue into two portions; 
one longitudinal, which is inserted along the side of the tongue, blending with the 
fibres of the Lingualis, in front of the Hyo-glossus; the other oblique, which 
overlaps the Hyo-glossus muscle, and decussates with its fibres. 

Relations. By its external surface, from above downwards, with the parotid 
gland, the Internal pterygoid muscle, the sublingual gland, the gustatory nerve, 
and the mucous membrane of the mouth. By its internal surface, with the tonsil, 
the Superior constrictor muscle of the pharynx, and the Hyo-glossus muscle. 

The Palato- Glossus, or Constrictor Isthmi Faucium, although one of the mus- 
cles of the tongue, serving to draw its base upwards during the act of deglutition, 
is more nearly associated with the soft palate, both in its situation and function; 
it will, consequently, be described with that group of muscles. 

Nerves. The muscles of the tongue are supplied by the hypoglossal nerve, 
excepting the Palato-glossus, which receives its nerves from the palatine branches 
of Meckel's ganglion. 



PHARYNGEAL REGION. 



211 



Actions. The movements of the tongue, although numerous and complicated, 
may easily be explained by cai-efully considering the direction of the fibres of the 
muscles of this organ. The Genio-hyo-glossi, by means of their posterior and 
inferior fibres, draw upwards the hyoid bone, bringing it and the base of the tongue 
forwards, so as to protrude the apex from the mouth. The anterior fibres will restore 
it to its original position by retracting the organ within the mouth. The whole 
length of these two muscles acting along the middle line of the tongue will draw 
it downwards, so as to make it concave from before backwards, forming a channel 
along which fluids may pass towards the pharynx, as in sucking. The Hyo-glossi 
muscles draw down the sides of the tongue, so as to render it convex from side to 
side. The Linguales, by drawing downwards the centre and apex of the tongue, 
render it convex from before backwards. The Palato-glossi draw the base of the 
tongue upwards, and the Stylo-glossi upwards and backwards. 



I 



Pharyngeal Region. 

Constrictor Inferior. Constrictor Superior. 

Constrictor Medius. Stylo -pharyngeus. 

Palato-pharyngeus. 

Dissection (fig. 139). In order to examine the muscles of the pharynx, cut through the 
trachea and oesophagus just above the sternum, and draw them upwards by dividing the 
loose areolar tissue connecting 

the pharynx with the front of 139. — Muscles of the Pharynx. External View, 

the vertebral column. The parts 
being drawn well forwards, the 
edge of the saw should be applied 
immediately behind the styloid 
processes, and the base of the 
skull sawn through from below 
upwards. The pharynx and 
mouth should then be stuffed 
with tow, in order to distend its 
cavity and render the muscles 
tense and easier of dissection. 

The Inferior Constrictor, 
the most superficial and thick- 
est of the three, arises from 
the side of the cricoid and 
thyroid cartilages. To the 
cricoid cartilage it is attached 
in the interval between the 
crico-thyroid, in front, and the 
articular facet for the thyroid 
cartilage behind. To the thy- 
roid cartilage, it is attached 
to the oblique line on the side 
of the great ala, the cartilagi- 
nous surface behind it, nearly 
as far as its posterior border, 
and to the inferior cornu. 
From these attachments, the 
fibres spread backwards and inwards, to be inserted into the fibrous raphe in the 
posterior median line of the pharynx. The inferior fibres are horizontal, and 
overlap the commencement of the oesophagus; the rest ascend, increasing in obli- 
quity, and overlap the Middle constrictor. The superior laryngeal nerve passes 
near the upper border, and the inferior, or recurrent laryngeal, beneath the lower 
border of this muscle, previous to their entering the' larynx. 

Relations. It is covered by a dense cellular membrane which surrounds the 

p 2 




212 MUSCLES AND FASCIiE. 

entire pharynx. Behind, it lies on the vertebi*al column and the Longus colli. 
Laterally, it is in relation with the thyroid gland, the common carotid artery, and 
the Sterno-thyroid muscle. By its internal surface, with the Middle constrictor, 
the Stylo-pharyngeus, Palato-pharyngeus, and the mucous membrane of the 
pharynx. 

The Middle Constrictor is a flattened, fan-shaped muscle, smaller than the pre- 
ceding, and situated on a plane anterior to it. It arises from the whole length of 
the upper border of the greater cornu of the liyoid bone, from the apex of this 
cornu by a tendinous origin, from the lesser cornu, and from the stylo-hyoidean 
ligament. The fibres diverge from their origin in various directions; the lower 
ones descending and being overlapped by the inferior constrictor, the middle fibres 
passing transversely, and the upper fibres ascending to cover in the Superior con- 
strictor. It is inserted into the posterior median' fibrous raphe, blending in the 
middle line with the fibres of the opposite muscle. 

Relations. This muscle is separated from the Superior constrictor by the glosso- 
pharyngeal nerve and the Stylo-phai-yngeus muscle; and from the inferior constric- 
tor, by the superior laryngeal nerve. Behind, it lies on the vertebral column, the 
Longus colli, and the Rectus anticus major. On each side it is in relation with the 
carotid vessels, the pharyngeal plexus, and some lymphatic glands. Near its 
origin, it is covered by the hyo-glossus, from which it is separated by the lingual 
artery. It covers in the Superior constrictor, the Stylo-pharyngeus, the Palato- 
pharyngeus, and the mucous membrane. 

The Superior Constrictor is a quadrilateral plane of muscular fibres, thinner 
and paler than those of the other Constrictors, situated at the upper part of the 
pharynx. It arises from the lower third of the margin of the internal pterygoid 
plate and its hamular process, from the contiguous portion of the palate bone and 
the reflected tendon of the Tensor palati muscle, from the pterygo-maxillary liga- 
ment, from the alveolar process above the posterior extremity of the mylo-hyoid 
ridge, and by a few fibres from the side of the tongue in connexion with the Genio- 
hyo-glossus. From these points, the fibres curve backwards, to be inserted into 
the median raphe, being also prolonged by means of a fibrous aponeurosis to 
the pharyngeal spine on the basilar process of the occipital bone. Its superior 
fibres arch beneath the Levator palati and the Eustachian tube, the interval 
between this border of the muscle and the basilar process being deficient in mus- 
cular fibres, and closed by fibrous membrane. 

Relations. By its outer surface, behind, with the vertebral column. On each 
side, with the carotid vessels, the internal jugular vein, the three divisions of the 
eighth and the ninth nerves, the Middle constrictor which overlaps it, and the 
Stylo-pharyngeus. Internally, it covers the Palato-pharyngeus and the tonsil and 
is lined by mucous membrane. 

The Stylo-pharyngeus is a long, slender muscle, round above, broad and thin 
below. It arises from the inner side of the base of the styloid process, passes 
downwards and inwards to the side of the pharynx between the Superior and 
Middle constrictors, and spreading out beneath the mucous membrane, some of its 
fibres are lost in the Constrictor muscles, and others joining with the Palato- 
pharyngeus, are inserted into the posterior border of the thyroid cartilage. The 
glosso-pharyngeal nerve runs on the outer side of this muscle, and crosses over it 
in passing forward to the tongue. 

Relations. Externally, with the Stylo-glossus muscle, the external carotid 
artery, the parotid gland, and the Middle constrictor. Internally, with the inter- 
nal carotid, the internal jugular vein, the Superior constrictor, Palato-pharyngeus 
and mucous membrane. 

Nerves. The muscles of this group are supplied by branches from the pharyn- 
geal plexus and glosso-pharyngeal nerve; and the Inferior constrictor, by an addi- 
tional branch from the external laryngeal nerve. 

Actions. When deglutition is about to be performed, the pharynx is drawn 
upwards and dilated in diflerent directions, to receive the morsel propelled into it 



PALATAL REGION. 



213 



from the mouth. The Stylo-pharyngei, which are much farther removed from one 
another at their origin than at their insertion, draw upwards and outwards the 
sides of this cavity, the breadth of the pharynx in the antero-posterior direction 
being increased, by the larynx and tongue being carried forwards in their ascent. 
As soon as the morsel is received in the pharynx, the elevator muscles relax, the 
bag descends, and the Constrictors contract upon the morsel, and convey it gradually 
downwards into the oesophagus. The pharynx also exerts an important influence 
in the modulation of the voice, especially in the production of the higher tones. 

Palatal Region. 

Levator Palati. Azygos Uvulae. 

Tensor Palati. Palato-glossus, 

Palato-pharyngeus. 

Dissection (fig. 140). Lay open the pharynx from behind, by a vertical incision extending 
from its upper to its lower part, and the posterior surface of the soft palate is exposed. 
Having fixed the uvula so as to make it tense, the mucous membrane and glands should 
be carefully removed from the posterior surface of the soft palate and the muscles of this 
part are at once exposed. 

140.— Muscles of the Soft Palate. The Pharynx being laid open from behind. 




"> /I h a <j'' 



The Levator Palati is a long, thin muscle, placed on the outer side of the pos- 
terior aperture of each nasal fossa. It arises from the apex of the basilar surface 
of the petrous portion of the temporal bone and from the adjoining cartilaginous 
portion of the Eustachian tube; after passing into the interior of the pharynx, 
above the upper concave margin of the Superior constrictor, it descends obliquely 
downwards and inwards, its fibres spreading out in the posterior surface of the 



214 MUSCLES AND FASCIA. 

soft palate as far as the middle line, where they blend with those of the opposite 
side. 

Relations. Externally, with the Tensor palati and Superior constrictor. Inter- 
nally, it is lined by the mucous membrane of the pharynx. Posteriorly, with the 
mucous lining of the soft palate. This muscle must be removed and the pterygoid 
attachment of the Superior constrictor dissected away, in order to expose the next 
muscle. 

The Circumflexus or Tensor Palati is a broad, thin, flat muscle, placed on the 
outer side of the preceding, and consisting of two distinct portions, a vertical and 
horizontal. The vertical portion arises by a broad, thin, and flat lamella from the 
scaphoid fossa at the base of the internal pterygoid plate, its fibres of origin 
extending as far back as the spine of the sphenoid; it also arises from the anterior 
aspect of the cartilaginous portion of the Eustachian tube, descending vertically 
downwards between the internal pterygoid plate and the inner surface of the 
Internal pterygoid muscle; it terminates in a tendon which winds around the 
hamular process, being retained in this situation by a tendon of origin of the 
Internal pterygoid muscle, and lubricated by a synovial membrane. The tendon 
or horizontal portion then passes horizonally inwards, and expands into a broad 
aponeurosis on the anterior surface of the soft palate, which unites in the median 
line with the aponeurosis of the opposite muscle, the fibres of which are attached 
anteriorly to the transverse ridge on the posterior border of the horizontal portion 
of the palate bone, 

Relations. Externally, with the Internal pterygoid. Internally, with the 
Levator palati, from which it is separated by the Superior constrictor, and the in- 
ternal pterygoid plate. In the soft palate its aponeurotic expansion is anterior to 
that of the Levator palati, being covered by mucous membrane. 

The Azygos UvuIcb is not a single muscle as implied by its name, but a pair of 
small cylindrical fleshy fasciculi, placed side by side in the median line of the soft 
palate. Each muscle arises from the posterior nasal spine of the palate bone, 
and from the contiguous tendinous aponeurosis of the soft palate, and descending 
vertically downwards, is inserted into the uvula. 

Relations. Anteriorly, with the tendinous expansion of the Levatores palati; 
behind, with the mucous membrane. 

The two next muscles are exposed by removing the mucous membrane which covers the 
pillars of the soft palate on each side throughout their whole extent. 

The Palato- Glossus (or. Constrictor Isthmi Eaucium) is a small fleshy fasci- 
culus, narrower in the middle than at either extremity, forming, with the mucous 
membrane covering its surface, the anterior pillar of the soft palate. It arises from 
the soft palate on each side of the uvula, and passing forwards and outwards in 
front of the tonsil, is inserted into the side and upper surface of the tongue, where 
it blends with the fibres of the Stylo-glossus muscle. In the soft palate, the fibres 
of origin of this muscle are continuous with those of the opposite side, and with 
the Palato-pharyngeus. 

The Palato-Pharyngeus is a long fleshy fasciculus, narrower in the middle 
than at either extremity, forming, with the mucous membrane covering its surface, 
the posterior pillar of the soft palate. It is separated from the preceding by an 
angular interval, in which the tonsil is lodged. It arises from the soft palate by an 
expanded fasciculus, its fibres being divided into two unequal parts by the Levator 
palati, and being continuous partly with the muscle of the opposite side, and 
partly with the fibrous aponeurosis of the palate. Passing outwards and down- 
wards behind the tonsil, it joins the Stylo-pharyngeus, and is inserted with it into 
the posterior border of the thyroid cartilage, some of its fibres being lost on the 
side of the pharynx. 

Relations. In the soft palate, its anterior and posterior surfaces are covered by 
mucous membrane, from which it is separated by a layer of palatine glands. By 
its superior border, it is in relation with the Levator palati. Where it forms the 
posterior pillar of the fauces, it is covered by mucous membrane, excepting on its 



ANTERIOR VERTEBRAL REGION. 



215 



outer surface. In the pharynx, it lies between the mucous membrane and the 
constrictor muscles. 

Nerves. The Tensor jjalati ia supplied by a branch from the otic ganglion; the 
other muscles by the palatine branches of Meckel's ganglion. 

Actions. When the morsel of food has been driven backwards into the fauces 
by the pressure of the tongue against the hard palate, the Palato-glossi muscles, 
the constrictors of the fauces, contract behind it, the soft palate is slightly raised 
(by the Levator palati), and made tense (by the Tensor palati), and the Palato- 
pharyngtei contract, and come nearly together, the Uvula filling up the slight 
interval between them. By these means, the food is prevented passing into the 
upper part of the pharynx or the posterior nares; at the same time the latter 
muscles form an inclined plane, directed obliquely downwards and backwards, 
along which the morsel descends into the pharynx. 

Surgical Anatomy. The muscles of the soft palate should be carefully dissected, the rela- 
tions they bear to the surrounding parts especially examined, and their action attentively 
studied upon the dead subject, as the surgeon is required to divide one or more of these 
muscles in the operation of staph yloraphy. Mr. Ferguson has shewn, that in the con- 
genital deficiency, called cleft palate, the edges of the fissure are forcibly separated by the 
action of the Levatores palati and Palato-pharyngsei muscles, producing very considerable 
impediment to the healing process after the performance of the operation for uniting their 
margins by adhesion ; he has, consequently, recommended the division of these muscles as 
one of the most important steps in the operation : by these means, the flaps are relaxed, 
lie perfectly loose and pendulous, and are easily brought and retained in apposition. The 
Palato-pharynggei may be divided by cut^^ing across the posterior pillar of the soft palate, 
just below the tonsil, with a pair of blunt-pointed curved scissors, and the anterior pillar 
may be divided also. To divide the Levator palati, the plan recommended by Mr. Pollock 
is to be greatly preferred. The flap being put upon the stretch, a double-edged knife is 
passed through the soft palate just on the inner side of the hamular process, and above the 
line of the Levator palati. The handle being now alternately raised and depressed, a 
sweeping cut is made along the posterior surface of the soft palate, and the knife with- 
drawn, leaving but a small opening in the mucous membrane on the anterior surface. If 
this operation is performed on the dead body, and the parts afterwards dissected, the 
Levator palati will be found completely divided. 



Vertebral Region (Anterior). 

Rectus Capitis Anticus Major. Rectus Lateralis. 

Rectus Capitis Anticus Minor. Longus Colli. 

The Rectus Capitis Anticus Major (fig. 14 1), broad and thick above, narrow 
below, appears like a continuation upwards of the Scalenus anticus. It arises by 
four tendons from the anterior tubercles of the transverse processes of the third, 
fourth, fifth, and sixth cervical vertebrge, and ascends, converging towards its 
fellow of the opposite side, to be inserted into the basilar process of the occipital 
bone. 

Relations. By its anterior surface, with the pharynx, the sympathetic nerve, 
and the sheath enclosing the carotid artery, internal jugular vein, and pneumo- 
gastric nerve. By its posterior surface, with the Longus colli, the Rectus anticus 
minor, and the upper cervical vertebrae. 

The Rectus Capitis Anticus Minor is a short muscle, situated immediately 
beneath the upper part of the preceding. It arises from the anterior surface of 
the lateral mass of the atlas, and from the root of its transverse process; passing 
obliquely upwards and inwards, it is inserted into the basilar process immediately 
behind the preceding muscle. 

Relations. By its anterior surface, with the Rectus anticus major. By its 
posterior surface, with the anterior part of the occipito-atlantai articulation. 
Externally, with the superior cervical ganglion of the sympathetic. 

The Rectus Lateralis is a short, flat muscle, situated between the transverse 
process of the atlas, and the jugular process of the occipital bone. It arises from 



2 {6 MUSCLES AND FASCIA. 

the upper surface of the transverse process of the atlas, and is inserted into the 
under surface of the jugular process of the occipital bone. 

Relations. By its anterior surface, with the internal jugular vein. By its 
posterior surface, with the vertebral artery. 

The Longus Colli is a long, flat muscle, situated on the anterior surface of the 
spine, between the atlas and the third dorsal vertebra, being broad in the middle, 
narrow and pointed at each extremity. It consists of three portions, a superior 
oblique, an inferior oblique, and a vertical portion. 

The superior oblique portion arises by a narrow tendon from the tubercle on 
the anterior arch of the atlas, and descending obliquely outwards, is inserted into 
the anterior tubercles of the transverse processes of the third, fourth, and fifth 
cervical vertebrae. 

The inferior oblique portion, the smallest part of the muscle, arises tendinous 

141.— The Pre- Vertebral Muscles. 




from the transverse processes of the fifth and sixth cervical vertebras, and passing 
obliquely inwards, is inserted into the bodies of the first two or three dorsal vertebrae. 

The vertical portion lies directly on the front of the spine, and is extended 
between the bodies of the second, third, and fourth cervical vertebrae above, and 
the bodies of the three lower cervical and the three upper dorsal below. 

Relations. By its anterior surface, with the pharynx, the oesophagus, sympa- 
thetic nerve, the sheath of the carotid artery, internal jugular vein, and pneumo- 
gastric nerve, inferior thyroid artery, and recurrent laryngeal nerve. By its 
posterior surface, with the cervical and dorsal portions of the spine. 



latp:ral vertebral region. 217 

Vertebral Region (Lateral). 

Scalenus Anticus. Scalenus Medius. 

Scalenus Posticus. 

The Scalenus Anticus is a triangular muscle, situated deeply at the side of the 
neck, behind the Sterno-mastoid. It arises by a narrow, flat tendon from the 
tubercle on the inner border and upper surface of the first rib, and ascending ver- 
tically upwards, is inserted into the anterior tubercles of the transverse processes 
of the third, fourth, fifth, and sixth cervical vertebrae. The lower part of this 
muscle separates the subclavian artery and vein; the latter being in front, and the 
former, with the brachial plexus, behind. 

Relations. By its anterior surface, with the Sterno-mastoid and Omo-hyoid 
muscles, the transversalis Colli, and descending cervical arteries, and the phrenic 
nerve. By its posterior surface, with the subclavian artery, and brachial plexus 
of nerves. It is separated from the Longus colli on the inner side by the subcla- 
vian artery. 

The Scalenus Medius, the largest and longest of the three Scaleni, arises, by a 
broad origin, from the upper surface of the first rib, behind the groove for the 
subclavian artery, as far back as the tubercle, and ascending along the side of the 
vertebral column, is inserted, by separate tendinous slips, into the posterior tuber- 
cles of the transverse processes of the six lower cervical vertebras. It is separated 
from the Scalenus anticus by the subclavian artery below, and the cervical nerves 
above. 

Relations. By its external surface, with the Sterno-mastoid; it is crossed by the 
clavicle and Omo-hyoid muscle. To its outer side, is the Levator anguli scapulae 
and the Scalenus posticus muscle. 

The Scalenus Posticus, the smallest of the three Scaleni, arises by a thin tendon 
from the outer surface of the second rib, behind the attachment of the Serratus 
magnus, and enlarging as it ascends, is inserted, by two or three separate tendons, 
into the posterior tubercles of the transverse processes of the two or three lower 
cervical vertebrfe. This is the most deeply-placed of the three Scaleni, and is 
occasionally blended with the Scalenus medius. 

Nerves. The Rectus capitis anticus major and minor are supplied by the sub- 
occipital and deep branches of the cervical plexus; the Rectus lateralis by the 
sub-occipital; and the Longus colli and Scaleni by branches from the lower cer- 
vical nerves. 

Actions. The Rectus anticus major and minor are the direct antagonists of 
those placed at the back of the neck, serving to restore the head to its natural 
position when drawn backwards by the posterior muscles. These muscles also 
serve to bow the head forwards. The Longus colli will flex and slightly rotate 
the cervical portion of the spine. The Scaleni muscles, taking their fixed point 
from below, draw down the transverse processes of the cervical vertebrae, flexing 
the spinal column to one or the other side. If the muscles of both sides act, the 
spine will be kept erect. When taking their fixed point from above, they elevate 
the first and second ribs, and are, therefore, inspiratory muscles. 

MUSCLES AND FASCIA OF THE TRUNK. 

The muscles of the Trunk may be subdivided into four groups. 

1 . Muscles of the Back. 3. Muscles of the Thorax. 

2. Muscles of the Abdomen. 4. Muscles of the Perinaeum. 

The Muscles of the Back are very numerous, and may be subdivided into five 
layers. 

First Layer. Second Layer. 

Trapezius. Levator anguli scapulae. 

Latissimus dorsi. Rhomboideus minor. 

. . Rhomboideus major. 



2l8 



MUSCLES AND FASCIA. 



Third Layer. 
Serratus posticus superior. 
Serratus posticus inferior. 
Splenius capitis. 
Splenius colli. 

Fourth Later. 
Sacral and Lumbar Regions. 
Erector Spinae. 

Dorsal Region. 

Sacro-lumbalis. 

Musculus accessorius ad sacro-lumbalem. 

Longissimus dorsi. 

Spinalis dorsi. 

Cervical Region. 
Cervicalis ascendens. 
Transversalis cervicis. 



Trachelo-mastoid. 
Complexus. 
Biventer cervicis. 
Spinalis cervicis. 

Fifth Layer. 
Semi-spinalis dorsi. 
Semi- spinalis colli. 
Multifidus spinae. 
Rotatores spinae. 
Supra-spinales. 
Inter-spinales. 
Extensor coccygis. 
Inter- transversales. 
Rectus posticus major. 
Rectus posticus minor. 
Obliquus superior. 
Obliquus inferior. 



First Layer. 



Trapezius. 



Latissimus Dorsi. 



Dissection {^g.T^^). The body sbould be placed in the prone position, with the arms 
extended over the sides of the table, and the chest and abdomen supported by several 

blocks, so as to reuder the muscles tense. An 
142.— Dissection of the Muscles of the Back, incision should then be made along the middle 

line of the back, from the occipital protu- 
berance £0 the coccyx. From the upper end 
of this, a transverse incision should extend to 
the mastoid process ; and from the lower end 
a third incision should be made along the 
crest of the ilium to about its middle. This 
large intervening space, for convenience of 
dissection, should be subdivided by a fourth 
incision, extending obliquely from the spinous 
process of the last dorsal vertebra, upwards 
and outwards, to the acromion process. This 
incision corresponds with the lower border of 
the Trapezius muscle. The flaps of integu- 
ment should then be removed in the direction 
shewn in the accompanying figure. 




The Trapezius is a broad, flat, trian- 
gular muscle, placed immediately beneath 
the skin, and covering the upper and back 
part of the neck and shoulders. It arises 
from the occipital protuberance and inner 
third of the superior curved line of the 
occipital bone ; from the ligamentum 
nuchae, the spinous processes of the 
seventh cervical, and all the dorsal ver- 
tebrae, and from the corresponding por- 
tion of the supra-spinous ligament. From 
these points the muscular fibres proceed, 
the superior ones downwards and out- 
wards, the inferior ones upwards and 
outwards, and the middle fibres horizon- 
tally, and are inserted, the superior ones curving forwards into the outer third of 
the posterior border of the clavicle, the middle fibres into the upper margin of the 
acromion process, and into the whole length of the upper border of the spine of 
the scapula; the inferior fibres converge near the scapula, and are attached 



OF THE BACK. 



219 



143. — Muscles of the Back. On the Left Side is exposed the First Layer; 
on the Eight Side, the Second Layer and part of the Third. 




220 MUSCLES AND FASCIA. 

to a triangular aponeurosis, which glides over a small triangular surface at the 
inner extremity of the spine, and is inserted into a small tubercle in immediate 
connection with its outer part. The Trapezius is fleshy in the greater part of 
its extent, but tendinous at its origin and insertion. At its occipital origin, it is 
connected to the bone by a thin fibrous lamina, firmly adherent to the skin, and 
wanting the lustrous, shining appearance of aponeurosis. At its origin from the 
spines of the vertebrje, it is connected by means of a broad semi-elliptical aponeu- 
rosis, which occupies the space between the sixth cervical and the third dorsal 
vertebrae, and forms, with the muscle of the opposite side, a tendinous ellipse. 
The remaining part of the origin is effected by numerous short tendinous fibres. 
If the Trapezius is dissected on both sides, the two muscles resemble a trapezium, 
or diamond-shaped quadrangle; two angles, corresponding to the shoulders; a 
third, to the occipital protuberance; and the fourth, to the spinous process of the 
last dorsal vertebra. 

The clavicular insertion of this muscle varies as to the extent of its attachment; 
it sometimes advances as far as the middle of the clavicle, and may even become 
blended with the posterior edge of the Sterno-mastoid, or overlap its margin. This 
should be borne in mind in the operation for tying the subclavian artery. 

Relations. By its superficial surface, with the integument^ to which it is closely 
adherent above, but separated below by an aponeurotic lamina. By its deep sur- 
face, in the neck, with the Complexus, Splenius, Levator anguli scapulae, and 
Rhomboideus minor; in the back, with the Rhomboideus major, Supra-spinatus, 
Infra-spinatus, a small portion of the Serratus posticus superior, the intervertebral 
aponeurosis which separates it from the Erector spinae, and with the Latissimus 
dorsi. The spinal accessory nerve passes beneath the anterior border of this 
muscle, near the clavicle. The outer margin ©f its cervical portion forms the 
posterior boundary of the large posterior triangle of the neck, the other boundaries 
being the Sterno-mastoid in front, and the clavicle below. 

The Lig amentum Nuchm (fig. 1 43) is a thin band of condensed cellulo-fibrous 
membrane, placed in the line of union between the two Trapezii in the neck. It 
extends from the external occipital protuberance to the spinous process of the 
seventh cervical vertebra, where it is continuous with the supra-spinous ligament. 
From its anterior surface a fibrous slip is given off to the spinous processes of 
each of the cervical vertebra, excepting the atlas, so as to form a septum between 
the muscles on each side of the neck. In the human subject, it is merely the rudi- 
ment of an important elastic ligament, which serves to sustain the weight of the 
head in some of the lower animals. 

The Latissimus Dorsi is a broad flat muscle, which covers the lumbar and 
lower half of the dorsal regions, and is gradually contracted into a narrow fasci- 
culus at its insertion into the humerus. It arises by tendinous fibres from the 
spinous processes of the six inferior dorsal, from those of the lumbar and sacral 
vertebrse, and from the supra-spinous ligament. Over the sacrum, the aponeurosis 
of this muscle blends with the tendon of the Erector spinte. It also arises from 
the external lip of the crest of the ilium, behind the origin of the External oblique, 
and by fleshy digitations from the three or four lower ribs, being interposed be- 
tween similar processes of the External oblique muscle. From this extensive 
origin the fibres pass in different directions,, the upper ones horizontally, the 
middle ones obliquely upwards, and the lower ones vertically upwards, so as to 
converge and form a thick fasciculus, which crosses the inferior angle of the 
scapula, and occasionally receives a few fibres from it. The muscle then curves 
around the lower border of the Teres major, and is twisted upon itself, so that 
the superior fibres become at first posterior and then inferior, and the vertical 
fibres at first anterior and then superior. It then terminates in a short quadri- 
lateral tendon, about three inches in length, which, passing in front of the tendon 
of the Teres major, is inserted into the bottom of the bicipital groove of the humerus, 
above the insertion of the tendon of the Pectoralis major. The lower border of 
the tendon of this muscle is united with that of the Teres major, the surfaces of 



i 



OF THE BACK. 221 

the two being separated by a synovial bursa; a second synovial bursa is interposed 
between the muscle and the inferior angle of the scapula. 

The origin of this muscle from the spine and ilium is effected by an aponeu- 
rosis, which assists in forming the sheath for the Erector spinas. Its costal 
attachment takes place by means of three or four fleshy slips, which inter-digitate 
with the External oblique muscle of the abdomen. 

Relations. Its superficial stirface is subcutaneous, excepting at its upper part, 
where it is covered by the Trapezius. By its deep surface, it is in relation with 
the Erector spinas, the Serratus posticus inferior. Intercostal muscles and ribs, the 
Serratus magnus, inferior angle of the scapula, Rhomboideus major, Infra-spinatus, 
and Teres major. Its external margin is separated below, from the external 
oblique, by a small triangular interval; and another triangular interval exists 
between its superior border and the margin of the Trapezius, in which the Inter- 
costal and Rhomboideus major muscles are exposed. 

Nerves. The Trapezius is supplied by the spinal accessory and cervical plexus; 
the Latissimus dorsi, by the subscapular nerves. 

Second Layer. 

Levator Anguli Scapulas. Rhomboideus Minor. 

Rhomboideus Major. 

Dissection. The Trapezius must be removed in order to expose the next layer ; to effect 
this, the muscle must be detached from its attachment to the clavicle and spine of the 
scapula, and turned back towards the spine. 

The Levator Anguli Scapulce is a long, thick, and somewhat flattened muscle, 
situated at the posterior part and side of the neck. It arises by four tendons from 
the posterior tubercles of the transverse processes of the three or four upper cer- 
vical vertebras, these becoming fleshy are united so as to form a flat muscle, which, 
passing downwards and backwards, is inserted into the posterior border of the 
scapula, between the superior angle and the triangular smooth surface at the root 
of the spine. 

Relations. By its superficial surface, with the integument, Trapezius, and 
Sterno-mastoid. By its deep surface, with the Splenius colli, Transversalis colli, 
Cervicalis ascendens, and Serratus posticus superior, and with the transverse cer- 
vical and posterior scapular arteries. 

The Rhomboideus Minor arises from the ligamentum nuchre, and spinous pro- 
cesses of the seventh cervical and first dorsal vertebrae, its fibres of origin being 
intimately united with those of the Trapezius. Passing downwards and outwards, 
it is inserted into the margin of the triangular smooth surface at the root of the 
spine of the scapula. This small muscle is usually separated from the Rhom- 
boideus major by a slight cellular interval. 

The Rhomboideus Major is situated immediately below the preceding, the adja- 
cent margins of the two being occasionally united. It arises by tendinous fibres 
from the spinous processes of the four or five upper dorsal vertebrse and their 
inter-spinous ligaments, and is inserted into the posterior border of the scapula, 
between the triangular surface at the base of the spine and the inferior angle. 
The insertion of this muscle takes place by means of a narrow, tendinous arch, 
attached above, to the triangular surface near the spine; below, to the inferior angle, 
the arch being connected to the border of the scapula by a thin membrane. When 
the arch extends, as it occasionally does, but a short distance, the muscular fibres are 
inserted into the scapula itself. 

Relations. By their superficial surface, with the integument, and Trapezius, 
the, Rhomboideus major, with the Latissimus dorsi. By their deep surface, with 
the Serratus posticus superior, posterior scapular artery, part of the Erector spinse, 
the Intercostal muscles and ribs. 

Nerves. These muscles are supplied by branches from the fifth cervical nerve, 
and additional filaments from the deep branches of the cervical plexus are distri- 
buted to the Levator anguli scapulae. 



222 MUSCLES AND FASCIiE. 

Actions. The movements effected by the preceding muscles are numerous, as may 
be conceived from their extensive attachment. If the head is fixed, the upper 
part of the Trapezius will elevate the point of the shoulder, as in supporting 
weights; when the middle and lower fibres are brought into action, partial rotation 
of the scapula upon the side of the chest is produced. If the shoulders are fixed 
both Trapezii acting together will draw the head directly backwards, or if only 
one acts, the head is drawn to the corresponding side. 

The Latissimus Dorsi, when it acts upon the humerus, draws it backwards and 
downwards, and at the same time rotates it inwards. If the arm is fixed, the 
muscle may act in various ways upon the trunk; thus, it may raise the lower ribs 
and assist in forcible inspiration, or if both arms are fixed, the two muscles may 
conspire with the Abdominal and great Pectoral muscles in drawing the whole 
trunk forwards, as in climbing or walking on crutches. 

The Levator Anguli Scapulce raises the superior angle of the scapula after it 
has been depressed by the Trapezius, whilst the Rhomboid muscles carry the infe- 
I'ior angle backwards and upwards, thus producing a slight rotation of the scapula 
upon the side of the chest. If the shoulder be fixed, the Levator scapulae may 
incline the neck to the corresponding side. The Rhomboid muscles acting together 
with the middle and inferior fibres of the Trapezius, will draw the scapula directly 
backwards towards the spine. 

Third Later. 

Serratus Posticus Superior, Serratus Posticus Inferior, 

o 1 . ( Splenius Capitis. 

bplenius <^ ci -x • r^. Tt 

{ Splenius Colli. 

Dissection. The third layer of muscles is brought Into view by the entire removal of 
the preceding, together with the Latissimus dorsi. To effect this, the Levator anguli 
scapulae and Rhomboid muscles should be detached near their insertion, and reflected 
upwards, thus exposing the Serratus posticus superior ; the Latissimus dorsi should then 
be divided in the middle by a vertical incision carried from its upper to its lower part, and 
the two halves of the muscle reflected. 

The Serratus Posticus Superior is a thin, flat muscle, irregularly quadrilateral 
in form, and situated at the upper and back part of the thorax. It arises by a 
thin and broad aponeurosis, from the ligamentum nuchse and from the spinous pro- 
cesses of the last ceiwical and two or three upper dorsal vertebrae. Inclining 
downwards and outwards, it becomes muscular, and is inserted by four fleshy digi- 
tations, into the upper borders of the second, third, fourth^ and fifth ribs, a little 
beyond their angles. 

Relations. By its superficial surface, with the Trapezius, Rhomboidei, and Ser- 
ratus magnus. By its deep surface, with the Splenius, upper part of the Erector 
spinae, Intercostal muscles and ribs. 

The Serratus Posticus Inferior is situated at the lower part of the dorsal and 
upper part of the lumbar regions: it is of an irregularly quadrilateral form, 
broader than the preceding, and separated from it by a considerable interval. It 
arises by a thin aponeurosis from the spinous processes of the two lower dorsal 
and two or three upper lumbar vertebrae, and from the inter-spinous ligaments. 
Passing obliquely upwards and outwards, it becomes fleshy, and divides into four 
flat digitations, which are inserted into the lower borders of the four lower ribs, a 
little beyond their angles. 

Relations. By its superficial surface, it is covered by the Latissimus dorsi, with 
the aponeurosis of which its own aponeurotic origin is inseparably blended. By 
its deep surface, with the posterior aponeurosis of the Transversalis, the Erector 
spinae, ribs and Intercostal muscles. Its upper margin is continuous with the ver- 
tebral aponeurosis. 

The Vertebral Aponeurosis is a thin aponeurotic lamina, extending along the 
whole length of the posterior part of the thoracic region, serving to bind down the 
Erector spiuEe, and separating it from those muscles which connect the spine to 



OF THE BACK. 



223 



the upper extremity. It consists of longitudinal and ti*ansverse fibres blended 
together, forming a thin lamella, which is attached in the median line to the spi- 
nous processes of the dorsal vertebrae; externally, to the angles of the ribs; and 
below, to the upper border of the Inferior serratus and tendon of the Latissimus 
dorsi; above, it passes beneath the Serratus posticus superior, and blends with the 
deep fascia of the neck. 

The Serratus posticus superior should now be detached from its origin and turned out- 
wards, when the Splenius muscle will be brought into view. 

The Spleiiius is a broad muscle, situated at the posterior part of the neck and 
upper part of the dorsal region. At its origin, it is a single muscle, narrow and 
pointed in form; but it soon becomes broader, and divides into two portions, which 
have separate insertions. It arises, by tendinous fibres, from the lower half of 
the Ligamentum nuchse, from the spinous processes of the last cervical and of the 
six upper dorsal vertebrae, and from the supra-spinous ligament. From this 
origin, the fleshy fibres proceed obliquely upwards and outwards, forming a broad 
flat muscle, which divides as it ascends into two portions, the Splenius capitis and 
Splenius colli. 

The Splenius capitis is inserted into the mastoid process of the temporal bone, 
and into the rough surface on the occipital bone beneath the superior curved line. 

The Splenius colli is inserted, by tendinous fasciculi, into the posterior tubercles 
of the transverse processes of the three or four upper cervical vertebras. 

The Splenius is separated from its fellow of the opposite side by a triangular 
interval, in which is seen the Complexus. 

Relations. By its superficial surface, with the Trapezius, from which it is sepa- 
rated below by the Rhomboidei and the Serratus posticus superior. It is also 
covered by the Sterno-mastoid and Levator anguli scapulae. By its deep surface, 
with the Spinalis dorsi, Longissimus dorsi, Semi-spinalis colli, Complexus, Trachelo- 
mastoid, and Transversalis colli. 

Nerves. The Splenius and Superior serratus are supplied from the external 
posterior branches of the cervical nerves; the Inferior serratus, from the external 
branches of the dorsal nerves. 

Actions. The Serrati are respiratory muscles acting in antagonism to each 
other. The Serratus posticus superior elevates the ribs; it is, therefore, an inspi- 
ratory muscle; while the Serratus inferior draws the lower ribs downwards, and 
is a muscle of expiration. This muscle is also probably a tensor of the vertebral 
aponeurosis. The Splenii muscles of the two sides, acting together, draw the 
head directly backwards, assisting the Trapezius and Complexus; acting sepa- 
rately, they draw the head to one or the other side, and slightly rotate it, turning 
the face to the same side. They also assist in supporting the head in the erect 
position. 

Fourth Later. 

Sacral and Lumbar Regions. Cervical Region. 

Erector Spinte. Cervicalis ascendens. 

Dorsal Region. Transversalis cervicis. 

Sacro-lumbalis. Trachelo-mastoid. 

Musculus accessorius ad sacro-lumbalem. Complexus. 

Longissimus dorsi. Biventer cervicis. 

Spinalis dorsi. Spinalis cervicis. 

Dissection. To expose the muscles of the fourth layer, the Serrati and vertebral aponeu- 
rosis should be entirely removed. The Splenius may then be detached by separating its 
attachments to the spinous processes, and reflecting it outwards. 

The Erector Spince (fig. 1 42), and its prolongations in the dorsal and cervical 
regions, fill up the vertebral groove on each side of the spine. They are covered 
in the lumbar region by the lumbar aponeurosis; in the dorsal region, by the 
Serrati muscles and the vertebral aponeurosis; and in the cervical region, by a 



224 



MUSCLES AND FASCIiE. 

144. — Muscles of the Back. Deep Layers 



\ifnt i 



MULTIFIUUS SPIN/e 



iffmi 



1 i^Jiu/inbar V- 



l^^Sacrat^ 




OF THE BACK. 



225 



layer of cervical fascia continued beneath the Trapezius, This large muscular 
and tendinous mass varies in size and structure at different parts of the spine. 
In the sacral region, the Erector spinaa is narrow and pointed, and its origin 
chiefly tendinous in structure. In the lumbar region, it becomes enlarged, and 
forms a large fleshy mass. In the dorsal region, it subdivides into two parts, 
which gradually diminish in size as they ascend to be inserted into the vertebra} 
and ribs, and are gradually lost in the cervical region, where a number of special 
muscles are superadded, which are continued upwards to the head, which they 
support upon the spine. 

The Erector spinas arises from the sacro-iliac groove, and from the anterior 
surface of a very broad and thick tendon, which is attached, internally, to the 
spines of the sacrum, to the spinous processes of the lumbar and three lower dorsal 
vertebra, and the supra-spinous ligament; externally, to the back part of the inner 
lip of the crest of the ilium, and to the series of eminences on the posterior part 
of the sacrum, representing the transverse processes, where it blends with the 
great sacro-sciatic ligament. The muscular fibres thus arising form a single large 
muscular mass, bounded in front by the transverse processes of the lumbar ver- 
tebrge, and by the middle lamella of the fascia of the Transversalis muscle. Oppo- 
site the last rib, this mass divides into two parts, one external, the Sacro-lumbalis, 
the other internal and larger, the Longissimus dorsi. 

The Sacro-Lumbalis, the external and smaller portion of the Erector spinae, is 
inserted, by a series of separate tendons, into the angles of the six lower ribs. If 
this muscle is reflected outwards, it will be seen to be reinforced by a series of 
muscular slips, which arise from the angles of the ribs; by means of these the 
Sacro-lumbalis is continued upwards, to be connected with the upper ribs, and 
with the cervical portion of the spine, forming two additional muscles, the Mus- 
culus accessorius and the Cervicalis ascendens. 

The Musculus Accessorius ad Sacro-Lumbalem arises by separate flattened 
tendons, from the upper margins of the angles of the six lower ribs; these become 
muscular, and are finally inserted, by separate tendons, into the angles of the six 
upper ribs. 

The Cervicalis Ascendens is the continuation of the Sacro-lumbalis upwards 
mto the neck: it is situated on the inner side of the tendons of the Accessorius, 
arising from the angles of the four or five upper ribs, and is inserted, by a series 
of slender tendons, into the posterior tubercles of the transverse processes of the 
fourth, fifth, and sixth cervical vertebrae. 

Longissimus Dorsi. The inner portion of the Erector spinae, the larger and 
longer of the two, has received the name ' Longissimus dorsi.' It arises, with the 
Sacro-lumbalis, from the common origin already mentioned. In the lumbar region, 
where it is as yet blended with the Sacro-lumbalis, some of the fibres are directed 
forwards to be inserted into the posterior surface of the transverse processes of 
the lumbar vertebrae their whole length, into the tubercles at the back of the 
articular processes, and into the layer of lumbar fascia connected with the apices 
of the transverse processes. In the dorsal region, the Longissimus dorsi is inserted, 
by long and thin tendons, into the extremities of the transverse processes of all 
the dorsal vertebra, and into from seven to eleven ribs between their tubercles 
and angles. 

This muscle is continued upwards to the cranium and cervical portion of the 
spine, by means of two additional slender fasciculi, the Transversalis colli, and 
Trachelo-mastoid. 

The Transversalis Colli, placed on the inner side of the Longissimus dorsi, 
arises, by long thin tendons, from the summit of the transverse processes of the 
third, fourth, fifth, and sixth dorsal vertebras, and is inserted, by similar tendons, 
into the posterior tubercles of the transverse processes of the five lower cervical. 

The Trachelo-Mastoid lies on the inner side of the preceding, between it and 
the Complexus muscle, and may be regarded as the. continuation of the Longissimus 
dorsi upwards to the head. It arises, by four tendons, from the transverse pro- 



226 MUSCLES AND FASCIA. 

cesses of the third, fourth, fifth, and sixth dorsal vertebrae, and from the articular 
processes of the three or four lower cervical; these joining form a small muscle, 
which ascends to be inserted into the posterior margin of the mastoid process, 
beneath the Splenius and Sterno-mastoid muscles. This small muscle is almost 
always crossed by a tendinous intersection near its insertion into the mastoid 
process. 

The spinous processes of the upper lumbar and the dorsal vertebra3 are con- 
nected together by a series of muscular and tendinous slips, which are intimately 
connected with the Longissimus dorsi, forming, in fact, part of this muscle; it is 
called the Spinalis dorsi. 

The Spinalis Dorsi is situated at the inner side of the Longissimus dorsi. It 
arises, by three or four tendons, from the spinous processes of the two upper 
lumbar and the two lower dorsal vertebrae: these uniting, form a small muscle, 
which is inserted, by separate tendons, into the spinous processes of all the upper 
dorsal vertebra?, the number varying from four to eight. It is intimately united 
with the Semi- spinalis dorsi, which lies beneath it. 

The Spinalis Cervicis is a small muscle, connecting together the spinous pro- 
cesses of the cervical vertebrte, and analogous to the Spinalis dorsi in the dorsal 
region. This muscle varies considerably in its size, and in its extent of attachment 
to the vertebras, not only in different bodies, but on the two sides of the same 
body. It usually arises by fleshy or tendinous fibres, varying from two to four in 
number, from the spinous processes of the fifth and sixth cervical vertebrae, and 
occasionally from the first and second dorsal, and is inserted into the spinous pro- 
cess of the axis, and occasionally into the spinous processes of the two vertebrse 
below it. This muscle has been found absent in five cases out of twenty-four. 

The Complexus is a broad thick muscle, situated at the upper and back part of 
the neck, lying beneath the Splenius, the direcfion of which it crosses obliquely 
from without inwards. It arises, by a series of tendons, about seven in number, 
from the posterior and upper part of the transverse processes of the three upper 
dorsal and seventh cervical, and from the articular processes of the three cervical 
above this. The tendons uniting form a broad muscle, which is directed obliquely 
upwards and inwards, and is inserted into the innermost depression between the 
two curved lines of the occipital bone. This muscle, about its middle, is traversed 
by a transverse tendinous intersection. 

The Biventer Cervicis, is a small fasciculus, situated on the inner side of the pre- 
ceding muscle, and in the majority of cases blended with it; it has received its 
name from presenting a tendon of considerable length with tAvo fleshy bellies. 
It is sometimes described as a separate muscle, arising, by from two to four ten- 
dinous slips, from the transverse processes of as many upper dorsal vertebrae, and 
is inserted, on the inner side of the Complexus, into the superior curved line of 
the occipital bone. 

Relations. By their superficial surface, with the Trapezius and Splenius. By 
their deep surface, with the Semi-spinalis dorsi and colli and the Recti and Obliqui. 
The Biventer cervicis is separated from its fellow of the opposite side by the liga- 
mentum nuchje, and the Complexus from the Semi-spinalis colli by the profunda 
cervicis artery, the princeps cervicis branch of the occipital, and by the posterior 
cervical plexus of nerves. 

Nerves. The Erector spinas and its subdivisions in the dorsal region are sup- 
plied by the external posterior branches of the lumbar and dorsal nerves. The 
Cervicalis ascendens, Transversalis colli, Trachelo-mastoid, and Spinalis cervicis, 
by the external posterior branches of the cervical nerves; the Complexus, by the 
internal posterior branches of the cervical nerves, the sub-occipital and great 
occipital. 



OF THE BACK. 

Fifth Layer. 
Semi-spinalis Uorsi. Extensor Coccygis. 



227 



Semi-spinulis Colli. Inter-transversalcs. 

Multifidus Spina3. Rectus Capitis Posticus Major. 

Rotatores Spina3. Rectus Capitis Posticus Minor. 

Supra-spinales. Obliquus Superior. 

Inter-spinales. Obliquus Inferior. 

Dissection. The muscles of the preceding layer must be removed by dividing and turning 
aside the Complexus, then detach the Spinalis and Longissimus dorsi from their attach- 
ments, and divide the Erector spinas at its connection below to the sacral and lundjar 
spines, and turn it outwards. The muscles filling up the interval between the spinous and 
transverse processes are then exposed. 

The Semi-spinales JIuscles connect together the transverse and spinous pro- 
cesses of the vertebrtB, extending from the lower part of the dorsal region to the 
upper part of the cervical. 

The Semi-spinalis Dorsi consists of a thin, narrow, fleshy fasciculus, interposed 
between tendons of considerable length. It arises by a series of small tendons 
from the transverse processes of the lower dorsal vertebrfB, from the tenth or 
eleventh to the fifth or sixth; these uniting form a small muscular fasciculus, 
which subdividing into five or six tendons, is inserted into the spinous j)rocesses 
of the four upper dorsal and two lower cervical. 

The Semi-spinalis Colli, thicker than the preceding, arises by a series of tendi- 
nous and fleshy points from the transverse processes of the four upper dorsal 
vertebrae, and is inserted into the spinous processes of the four upper cervical ver- 
tebrae, from the axis to the fifth cervical. The fasciculus connected with the axis 
is the largest, and chiefly muscular in structure. 

Relations. By their superficial surface, from below upwards with the Longis- 
simus dorsi. Spinalis dorsi, Splenius, Complexus, the profunda cervicis and princeps 
cervicis arteries, and the posterior cervical plexus of nerves. By their deep 
surface, with the Multifidus spinae. 

The Multifidus Spince consists of a number of fleshy and tendinous fasciculi, 
which fill up the groove on either side of the spinous processes of the vertebrae 
from the sacrum to the axis. In the sacral region, these fasciculi arise from the 
sacral groove, as low down as the fourth sacral foramen, being connected with the ' 
aponeurosis of origin of the Erector spinse. In the iliac region, from the inner 
surface of the posterior superior spine, and posterior sacro-iliac ligaments. In the 
lumbar and cervical regions they arise from the articular processes, and in the 
dorsal region, from the transverse processes. Each fasciculus, ascending obliquely 
upwards and inwards, is inserted into the lamina and whole length of the spinous 
process of the vertebra above. These fasciculi vary in length; the most sujDcr- 
ficial, the longest, pass from one vertebra to the third or fourth above ; those next in 
order pass from one vertebra to the second or third above; whilst the deepest con- 
nect two contiguous vertebrae. 

Relations. By its superficial surface, with the Longissimus dorsi. Spinalis dorsi, 
Semi-spinalis dorsi, and Semi-spinalis colli. By its deep surface, with the laminae 
and spinous processes of the vertebrae, and with the Rotatores spinas in the dorsal 
region. 

The Rotatores Spines are found only in the dorsal region of the spine, beneath 
the Multifidus spinae, they are eleven in number on each side. Each muscle, 
which is small and somewhat quadrilateral in form, arises from the upper and back 
part of the transverse process, and is inserted into the lower border and outer 
surface of the lamina of the vertebra above, the fibres extending as far inwards as 
the -root of the spinous process. The first is found between the first and second 
dorsal, the last, between the eleventh and twelfth. Sometimes the number of these 
muscles is diminished by the absence of one or more from the upper or lower end. 

The Supra Spinales consist of a series of fleshy bands, which lie on the spi- 
nous processes in the cervical region of the spine. - 

Q 2 



228 MUvSCLES AND FASCIA. 

The Inter- S pinoles are short muscular fasciculi, placed in pairs between the 
spinous processes of the contiguous vertebrae. In the cervical region they are 
most distinct, and consist of six pairs, the first being situated between the axis and 
third vertebra, and the last between the last cervical and the first dorsal. In the 
dorsal region they are found above, between the first and second vertebras, and 
occasionally between the second and third; and below, between the eleventh and 
twelfth. In the lumbar region there are four pairs of these muscles in the intervals 
between the five lumbar vertebra?. There is also occasionally one in the inter- 
spinous space, between the last dorsal and first lumbar, and between the fifth 
lumbar and the sacrum. 

The Extensor Coccygis is a slender muscular fasciculus, occasionally present, 
which extends over the lower part of the posterior surface of the sacrum and 
coccyx. It arises by tendinous fibres from the last bone of the sacrum, or first 
piece of the coccyx, and passes downwards to be inserted into the lower part of 
the coccyx. It is a rudiment of the Extensor muscle of the caudal vertebrfe 
present in some animals. 

The Inter-Transversales are small muscles placed between the transverse pro- 
cesses of the vertebrae. In the cervical region they are most developed, consisting 
of two rounded muscular and tendinous fasciculi, which pass between the anterior 
and posterior tubercles of the transverse processes of two contiguous vertebras, 
being separated from one another by the anterior branch of a cervical nerve, 
which lies in the groove between them, and by the vertebral artery and vein. In 
this region there are seven pairs of these muscles, the first being between the 
atlas and axis, and the last between the seventh cervical and first dorsal vertebrae. 
In the dorsal region the Inter-transversales are least developed, consisting chiefly 
of rounded tendinous cords in the inter-transverse spaces of the upper dorsal 
vertebrae ; but between the transverse processes of the three lower dorsal vertebrae 
and the first lumbar, they are muscular in structure. In the lumbar region they 
are four in number, and consist of a single muscular layer, which occupies the 
entire interspace between the transverse processes of the lowest lumbar vertebrae, 
whilst those between the transverse processes of the upper lumbar, are not attached 
to more than half the breadth of the process. 

The Rectus Capitis Posticus Major, the larger of the two Recti, arises by a 
pointed tendinous origin from the spinous process of the axis, and becoming broader 
as it ascends, is inserted into the inferior curved line of the occipital bone and the 
surface of bone immediately beneath it. As the muscles of the two sides ascend 
upwards and outwards, they leave between them a triangular space, in which are 
seen the Recti capitis postici minores muscles. 

Relations. By its superficial surface, with the Complexus, and at its insertion, 
with the Superior oblique. By its deep surface, with the posterior arch of the atlas, 
the posterior occipito-atloid ligament, and part of the occipital bone. 

The Rectus Capitis Posticus Minor, the smallest of the four muscles in this 
region, is of a triangular shape, it arises by a narrow, pointed tendon from the tu- 
bercle on the posterior arch of the atlas, and becoming broader as it ascends, is 
inserted into the rough surface beneath the inferior curved line, nearly as far as 
the foramen magnum, nearer to the middle line than the preceding. 

Relations. By its superficial surface, with the Complexus. By its deep sur- 
face, with the posterior occipito-atloid ligament. 

The Obliquus Inferior, the largest of the two oblique muscles, arises from the 
apex of the spinous process of the axis, and forms a thick cylindrical muscle, 
which passes almost horizontally outwards, to be inserted into the apex of the 
transverse process of the atlas. 

Relations. By its superficial surface, with the Complexus, and is crossed by 
the posterior branch of the second cervical nerve. By its deep surface, with the 
vertebral artery and posterior occipito-atloid ligament. 

The Obliquus Superior, narrow below, wide and expanded above, arises by 
tendinous fibres from the upper part of the extremity of the transverse process of 



OF THE BACK. 229 

the atlas, joining with the insertion of the Inferior oblique muBcle, and passing 
obliquely upwards and inwards, is inserted into the occipital bone, between the 
two curved lines, external to the Complexus. Between the two oblique muscles 
and the Rectus posticus major, a triangular interval exists, in which is seen the 
vertebral artery and the posterior branch of the sub-occipital nerve. 

Relations. By its superficial surface, with the Complexus and Trachelo-mas- 
toid. By its deep surface, with the posterior occipito-atloid ligament. 

Nerves. The Semi-spinalia dorsi and Rotatores spinse are supplied by the inter- 
nal posterior branches of the dorsal nerves. The Semi-spinalis colli, Supra- 
spinales, and Inter-spinales, by the internal posterior branches of the cervical 
nerves. The Inter- transversales, by the internal posterior branches of the cervi- 
cal, dorsal, and lumbar nerves. And the Multifidus spinas, by the same, with the 
addition of the internal posterior branches of the sacral nerves. The Recti and 
Obliqui muscles are all supplied by the sub-occipital and great occipital nerves. 

Actions. The Erector spina3, comprising the Sacro-lumbalis, with its accessory 
muscle, the Longissimus dorsi and Spinalis dorsi, serves, as its name implies, to 
maintaiB the spine in the erect posture; it also serves to bend the ti'unk back- 
wards, when it is required to counter-balance the influence of any weight at the 
front of the body, as, for instance, when a heavy weight is suspended from the 
neck, or when there is any great abdominal development, as in pregnant women 
or in abdominal dropsy; the peculiar gait under such circumstances depends upon 
the spine being drawn backwards, by the counter-balancing action of the Erector 
spin£e muscles. The continuation of these muscles upwards to the neck and head, 
steady and preserve the upright position of these several parts. If the Sacro- 
lumbalis and Longissimus dorsi of one side act, they serve to draw down the chest 
and spine to the corresponding side. The Musculus acce'ssorius, taking its fixed 
point from the cervical vertebrae, elevates those ribs to which it is attached. The 
Multifidus spinas act successively upon the different segments of the spine; thus 
the lateral parts of the sacrum furnish a fixed point from which the fasciculi of 
this muscle act upon the lumbar region; these then become the fixed points for 
the fasciculi moving the dorsal region, and so on throughout the entire length of 
the spine; it is by the successive contraction and relaxation of the separate fas- 
ciculi of this and other muscles, that the spine preserves the erect posture without 
the fatigue that would necessarily have existed had this movement been accom- 
plished by the action of a single muscle. The Multifidus spinas, besides pre- 
serving the erect position of the sjDine, serves to rotate it, so that the front of the 
trunk is turned to the side opposite to that from which the muscle acts, this 
muscle being assisted in its action by the Obliquus externus abdominis. The 
Complexi, the analogues of the Multifidus spinas in the neck, draw the head 
directly backwards; if one muscle acts, it draws the head to one side, and rotates 
it so that the face is turned to the opposite side. The Rectus capitis posticus mi- 
nor and the Superior oblique draw the head backwards, and the latter from the 
obliquity in the direction of its fibres, may turn the face to the opposite side. The 
Rectus capitis posticus major and the Obliquus inferior, rotate the atlas, and with 
it the cranium around the odontoid process, and turn the face to the same side. 

Muscles of the Abdomen. 

The muscles in this region are, the 

Obliquus Externus. Rectus. 

Obliquus Internus. Pyramidalis, 

Transversalis. Quadratus Lumborum. 

Dissection (fig. 145). To dissect the abdominal muscles, a vertical incision should be 
made from the ensiform cartilage to the puhes ; a second oblique incision should extend 
from the umbilicus upwards and outwards to the outer surface of the chest, as high as the 
lower border of the fifth or sixth rib ; and a third, commencing rnidway between the umbi- 
licus and pubes, should pass transversely outwards to the antei'ior superior ihac spine, and 
along the crest of the ilium as far as its posterior third. The three flaps included between 



230 



MUSCLES AND FASCItE. 



14.5. — Dissection of Abdomen. 



these incisions should then be reflected from within outwards, in the direction indicated in 
the figure. 

The External Oblique Muscle (Obliquus descendens) (fig, 146), so called from 
the direction of its fibres, is situated on the lateral and anterior aspects of the 
abdomen ; being the largest and the most superficial of the three flat muscles in this 
region. It is broad, thin, irregularly quadrilateral in form, its muscular portion 
occupying the sides, its aponeurosis the anterior wall of that cavity. It arises, by 
eight fleshy digitations, from the external surface and lower borders of the eight 
inferior ribs ; these digitations are arranged in an oblique line running downwards 
and backwards; the upper ones being attached close to the cartilages of the cor- 
resj)onding ribs; the lowest, to the apex of the cartilage of the last rib; the inter- 
mediate ones, to the ribs at some distance from their cartilages. The five superior 

serrations increase in size from above down- 
wards, and are received between corresponding 
processes of the Serratus magnus; the three 
lower ones diminish in size from above down- 
wards, receiving between them corresponding- 
processes from the Latissimus dorsi. From 
these attachments the fleshy fibres proceed in 
various directions. Those from the lowest ribs 
pass nearly vertically downwards, to be inserted 
into the anterior half of the outer lip of the 
crest of the ilium; the middle and upper fibres, 
directed downwards and forwards, terminate in 
tendinous fibres, which spread out into a broad 
aponeurosis. This aponeurosis, joined with that 
of the opposite muscle along the median line, 
covers the whole of the front of the abdomen: 
above, it is connected with the lower border of 
the Pectoralis major; below, its fibres are closely 
aggregated together, and extend obliquely across 
from the anterior superior spine of the ilium to 
the spine of the os pubis and the pectineal line. 
In the median line, it interlaces with the apo- 
neurosis of the opposite muscle, forming the 
linea alba, and extends from the ensiforra car- 
tilage to the symj)hysis pubis. 
That portion of the aponeurosis which extends between the anterior superior 
spine of the ilium and the spine of the os pubis is a broad band, folded inwards, and 
continuous below with the fascia lata; it is called Pouparfs ligament. The por- 
tion which is reflected from Poupart's ligament backwards and inwards into the 
pectineal line, is called Gimhernat's ligament. 

In the aponeurosis of the External oblique, immediately above the crest of the 
OS pubis, is a triangular opening, the external abdominal ring, formed by a splitting 
of the fibres of the aponeurosis in this situation ; it serves for the transmission of 
the spermatic cord in the male, and the round ligament in the female. This opening 
is directed obliquely upwards and outwards, and corresponds with the course of 
the fibres of the aponeurosis. It is bounded below by the crest of the os pubis; 
above, by some curved fibres, which pass across the aponeurosis at the upper 
angle of the ring so as to increase its strength; and on either side, by the margins 
of the aponeurosis, which are called the pillars of the ring. Of these, the external, 
which is, at the same time inferior, from the obliquity of its direction, is inserted 
into the spine of the os pubis. The internal, or superior pillarjvbeing attached to 
the front of the symphysis pubis, interlaces with the corresponding fibres of the 
opposite muscle. To the margins of the pillars of the external abdominal ring is 
attached an exceedingly thin and delicate fascia, which is prolonged down over 
the external surface of the cord and testis. This has received the name of inter- 



3. 

of \ 
iMC'JINAlV\ 
HERNIA 




OF THE ABDOMEN. 



231 



columnar fascia from its attachment to the pillai-s of the ring. It has also re- 
ceived the name of external spermatic fascia, from being tlie most external of 
the fascia3 whicli cover tlie spermatic cord. 

Relations. By its external surface, with the superficial fascia, superficial 
epigastric and circumflexa ilii vessels, and some cutaneous nerves. By its internal 
surface, with the Internal oblique, the lower part of the eight inferior ribs and Inter- 
costal muscles, the cremaster, the spermatic cord in the male, and round ligament in 
the female. Its posterior border is occasionally overlapped by the Latissimus dorsi; 
sometimes an interval exists between the two muscles, in which is seen a portion 
of the Internal oblique. 

146, — The External Oblique Muscle. 



^lit.Abdo7iu>i(il JRirLq-'r — 
Clmiernat's Ligl—I— 




I 



Dissection. The External oblique should now be detached by dividing it across, just in 
front of its attachment to the ribs, as far as its posterior border, and by separating it 
below from the crest of the ilium as far as the spine ; the muscle should then be carefully 
separated from the Internal oblique, which lies beneath, and turned towards the opposite 
side. ' 

The Internal Oblique Muscle (fig. 147) (Obliquus ascendens), thinner and 



23: 



MUSCLES AND FASCIA. 



smaller than the preceding, beneath which it lies, is of an irregularly quadrilateral 
form, and situated at the anterior lateral and posterior parts of the abdomen. It 
arises, by fleshy fibres, from the outer half of Poupart's ligament, being attached to 
the groove on its upper surface; from the anterior two-thirds of the middle lip of 
the crest of the ilium, and from the lumbar fascia. From this origin, the fibres 
diverge in different directions. Those from Poupart's ligament, few in number 
and paler in colour than the rest, arch downwards and inwards across the sper- 
matic cord, to be inserted, conjointly with those of the Transversalis, into the 
crest of the os pubis and pectineal line, to the extent of half an inch, forming the 
conjoined tendon of the Internal oblique and Transversalis; those from the anterior 
superior iliac spine are horizontal in their direction; whilst those which arise from 
the front part of the crest of the ilium pass obliquely upwards and inwards, 
and terminate in an aponeurosis, which is continued forwards to the linea alba; 
the most posterior fibres ascend almost vertically upwards, to be inserted into the 

147. — The Internal Oblique Muscle. 



Conjoined fene/on—r- 

L 



CREMASTER 




lower borders of the cartilages of the four lower ribs, being continuous with the 
internal intercostal muscles. 

The conjoined tendon of the Internal oblique and Transversalis is inserted into 
the crest of the os pubis and pectineal line immediately behind the external abdo- 
minal ring, serving to protect what Avould otherwise be a weak point in the 
abdomen. Sometimes this tendon is insufiicient to resist the pressure from within, 
and is carried forward in front of the protrusion through the externf.l ring, forming- 
one of the coverings of direct inguinal hernia. 



OF THE ABDOMEN. 



233 



The aponeurosis of the Internal oblique is continued forward to the middle line 
of the abdomen, where it joins with the aponeurosis of the opposite muscle at the 
linea alba, and extends from the margin of the thorax to the pubes. At the 
outer margin of the sheath of the Rectus muscle, for the upper three-fourths of its 
extent, this aponeurosis divides into two lamellas, which pass, one in front and the 
other behind it, enclosing it in a kind of sheath, and reuniting on its inner border 
at the linea alba: the anterior layer is blended with the aponeurosis of the 
External oblique muscle; the posterior layer with that of the Transversalis. 
Along the lower fourth, the aponeurosis passes altogether in front of the Rectus 
without any separation. 

Relations. By its external surface, with the External oblique, Latissimus dorsi, 
spermatic cord, and external ring. By its internal surface, with the Transversalis 
muscle, fascia transversalis, internal ring, and spermatic cord. Its lower border 
forms the upper boundary of the spermatic canal. 

Dissection. The Internal oblique should now be detached in order to expose the Trans- 
versalis muscle beneath. This may be efiected by dividing the muscle, above, at its 
attachment to the ribs ; below, at its connexion with Poupart's ligament and the crest of 
the ilium ; and behind, by a vertical incision extending from the last rib to the crest of 
the ilium. The muscle should previously be made tense by drawing upon it with the 
lingers of the left hand, and if its division is carefully effected, the cellular interval between 
it and the Transversalis, as weU as the direction of the fibres of the latter muscle, will 
afford a clear guide to their separation ; along the crest of the ilium the circumflex ilii 
vessels are interposed between them, and form an important aid in separating them. The 
muscle should then be thrown forwards towards the linea alba. 

The Transversalis muscle (fig. 148), so called from the direction of its fibres, 
is the most internal flat muscle of the abdomen, being placed immediately beneath 
the Internal Oblique. It arises by fleshy fibres from the outer third of Poupart's 
ligament, from the inner lip of the crest of the ilium, its anterior two-thirds, from 
the inner surface of the cartilages of the six lower ribs, interdigitating with the 
Diaphragm, and by a broad aponeurosis from the spinous and transverse processes 
of the lumbar vertebrae. The lower fibres curve downwards, and are inserted to- 
gether with those of the Internal oblique, into the crest of the os pubis and pec- 
tineal line, forming what was before mentioned as the conjoined tendon of these 
muscles. Throughout the rest of its extent the fibres pass horizontally inwards, 
and near the outer margin of the Rectus, terminate in an aponeurosis, which is in- 
serted into the linea alba; its upper three-fourths passing behind the Rectus 
muscle, blending with the posterior lamella of the Internal oblique; its lower 
fourth passing in front of the Rectus. 

Relations. By its external surface, with the Internal oblique, the inner sur- 
faces of the lower ribs, and Internal intercostal muscles. By its internal surface, 
it is lined by the fascia transversalis, which separates it from the peritoneum. Its 
lower border forms the upper boundary of the spermatic canal. 

Lumbar Fascia (fig. 149). The vertebral aponeurosis of the Transversalis divides 
into three layers, an anterior, very thin, which is attached to the front part of 
the apices of the transverse processes of the lumbar vertebrae, and, above, to the 
lower margin of the last rib, forming the ligamentum arcuatum externum; a mid- 
dle layer, much sti-onger, which is attached to the apices of the transverse processes; 
and a posterior layer, attached to the apices of the spinous processes. Between the 
anterior and middle layers is situated the Quadratus lumborum, between the middle 
and posterior, the Erector spinae. The posterior lamella of this aponeurosis 
receives the attachment of the Internal oblique; it is also blended with the apo- 
neurosis of the Serratus posticus inferior and with that of the Latissimus dorsi, 
forming the Lumbar fascia; the two anterior layers are connected solely with the 
Transversalis. 

Dissection. To expose the Rectus muscle, its sheath should be opened by a vertical inci- 
sion extending from the margin of the thorax to the piibes, the two portions should then 
be reflected from the surface of the muscle, which is easily effected, excepting at the linese 
transversae, where so close an adhesion exists, that the greatest care is requisite in sepa- 



234 



MUSCLES AND FASCIA. 



rating them. The outer edge of the muscle should now be raised, when the posterior 
layer of the sheath will be seen. By dividing the muscle in the centre, and turning its 
lower part downwards, the point where the posterior waU of the sheath terminates in a 
thin curved margin will be seen. 

The Rectus Abdominis is a long, flat muscle, which extends along the w^hole 
length of the anterior wall of the abdomen, being separated from its fellow of the 
opposite side by the linea alba. It is much broader above than below, and 
arises by two tendons, the external or larger being attached to the crest of the 

148. — The Transversalis, Kectus, and Pyramidalis Muscles. 



I m e a 




OS pubis; the internal, smaller portion, interlacing with its fellow of the opposite 
side, and being connected with the ligaments covering the symphysis pubis. The 
fibres ascend vertically upwards, and the muscle becoming broader and thinner 
at its upper part, is inserted by three portions of unequal size into the cartilages 
of the fifth, sixth, and seventh ribs. Some fibres are also occasionally connected 
with the costo-xiphoid ligaments, and side of the ensifoi-m cartilage. 



OF THE ABDOMEN. 



235 



The Rectus muscle is traversed by 11 series of tendinous intersections, which 
vary from two io five in number, and have received the name lineaa transversoe. 
One of these is usually situated opposite the umbilicus, and two above that point; 
of these, one corresponds to the ensiform cartilage, and the other, to the interval 
between the ensiform cartilage und the umbilicus; there is occasionally one below 
the umbilicus. These intersections pass transversely or obliquely across the mus- 
cle in a zigzag course; they rarely extend completely through its substance, some- 
times pass only half way across it, and are intimately adherent to the sheath in 
which the muscle is enclosed. 

The Rectus is enclosed in a sheath (fig. 149) formed by the aponeuroses of the 
Oblique and Transversalis muscles, which are arranged in the following manner. 
When the aponeurosis of the Internal oblique arrives at the margin of the Rectus, 
it divides into two lamellae, one of which passes in front of the Rectus, blending 
with the aponeurosis of the Extei'nal oblique; the other, behind it, blending with 
the aponeurosis of the Transversalis; and these, joining again at its inner border, 
are inserted into the linea alba. This arrangement of the fascia exists along the 

149. — A Transverse Section of the Abdomen in the Lumbar Region. 




upper three-fourths of this muscle; at the commencement of the loAver fourth, 
the posterior wall of the sheath terminates in a thin curved margin, the concavity 
of which looks downwards towards the pubes; the aponeuroses of all three 
muscles passing in front of the Rectus without any separation. The Rectus 
muscle in the situation where its sheath is deficient, is separated from the perito- 
neum by the transversalis fascia. 

The Pyramidalis is a small muscle, triangular in form, situated at the lower 
part of the abdomen, one on each side of the linea alba. It arises by tendinous 
fibres from the front of the OS pubis and anterior pubic ligament; the fleshy portion 
of the muscle passes upwards, diminishing in size as it ascends, and terminates by 
a pointed extremity, which is inserted into the linea alba, midway between the 
umbilicus and the os pubis. It rests against the lower part of the front of the Rec- 
tus, and is contained in the same sheath with that muscle. This muscle is some- 
times found wanting on one or both sides; the lower end of the Rectus then 
becomes proportionally increased in size. Occasionally it has been found double 
on one side, or the muscles of the two sides are of unequal size. Sometimes its 
length exceeds that stated above. 

The Quadratus Lumhorum is situated in the lumbar region of the spine, 
it is irregularly quadrilateral in shape, broader below than above, and consists 
of two portions. One portion arises by aponeurotic fibres from the ilio- 
lumbar ligament, and the adjacent portion of the crest of the ilium for about two 



236 MUSCLES AND FASCIiBL 

inches, and is inserted into the lower border of tlie last rib, about half its length, 
and by four small tendons, into the apices of the transverse processes of the third, 
fourth, and fifth lumbar vertebrae. The other portion of the muscle, situated 
anterior to the preceding, arises from the upper borders of the transverse processes 
of the third, fourth, and fifth lumbar vertebrae, and is inserted into the lower margin 
of the last rib. The Quadratus lumborum is contained in a sheath formed by 
the anterior and middle lamellae of the vertebral aponeurosis of the Transversalis. 

Nerves. All the abdominal muscles are supplied by the lower intercostal, ilio- 
hypo-gastric, and ilio-inguinal nerves, excepting the Quadratus lumborum, which 
receives filaments from the anterior primary branches of the lumbar nerves. 

In the description of the abdominal muscles, mention has frequently been made 
of the linea alba, line^e semilunares, lineae transversas; when the dissection of these 
muscles is completed, these structures should be examined. 

The Linea Alba is a tendinous raphe or cord seen along the middle line of the 
abdomen, extending from the ensiform cartilage to the symphysis pubis. It is 
placed between the inner borders of the Recti muscles, and formed by the blending 
of the anterior aponeuroses of the Oblique and Transversalis muscles. It is nar- 
row below, corresponding to the narrow interval existing between the Recti, but 
broader above, as these muscles diverge from one another in their ascent, be- 
coming of considerable breadth after great distension of the abdomen from preg- 
nancy or ascites. It presents numerous apertures for the passage of vessels and 
nerves; the largest of these is the umbilicus, which in the foetus transmits the 
umbilical vessels, but in the adult is obliterated, the cicatrix being stronger than 
the neighbouring parts; hence the occurrence of umbilical hernia in the adult 
above the umbilicus, whilst in the foetus it occvirs at the umbilicus. The 
linea alba is in relation, in front, with the integument to which it is adherent, 
especially at the umbilicus; behind, it is separated from the peritoneum by the 
transversalis fascia; and below, by the urachus, and the bladder, when that organ 
is distended. 

The LinecB Semilunares are two curved tendinous lines, placed one on each 
side of, and a little external to the linea alba. Each extends from the cartilage of 
the eighth rib to the pubes, and corresponds with the outer border of the Rectus 
muscle. They are formed by the aponeurosis of the Internal oblique at its point 
of division to enclose the Rectus. 

The Linece Transverse^ are three or four narrow transverse lines which inter- 
sect the Rectus muscle as already mentioned, they connect the lineae semilunares 
with the linea alba. 

Actions. The abdominal muscles perform a three-fold action. 

When the pelvis and thorax are fixed, they can compress the abdominal viscera, 
by constricting the cavity of the abdomen, in which action they are materially 
assisted by the descent of the diaphragm. By these means, the foetus is expelled 
from the uterus, the fasces from the rectum, the urine from the bladder, and the 
ingesta from the stomach in vomiting. 

If the spine be fixed, these muscles compress the lower part of the thorax, ma- 
terially assisting in the process of expiration. If the spine be not fixed, the thorax 
is bent directly forward, if the muscles of both sides act, or to either side if they act 
alternately, rotation of the trunk at the same time taking place to the opposite side. 

If the thorax be fixed, these muscles act upon the pelvis, as in climbing, when 
the pelvis is drawn directly upwards, or to one or the other side. The Recti 
muscles may draw the pelvis forwards, and flex it upon the vertebral column. The 
Pyramidales are tensors of the linea alba. 

Muscles and Fascia of the Thorax. 

The muscles exclusively connected with the bones in this region are few in 
number. They are the 

Intercostales Extei-ni. lufra-Costales, 

Intercostales Interni. Triangularis vSterni. 

Levatores Costarum. 



OF THE THORAX. 237 

Intercostal Fascice. A thin but firm layer of fascia covers the outer surface of 
the External intercostal and the inner surface of the Internal intercostal muscles; 
and a third layer, more delicate, is interposed between these two planes of mus- 
cular fibres. These are the intercostal fascise; they are best marked in those 
situations where the muscular fibres are deficient, as between the External inter- 
costal muscles and sternum, in front; and between the Internal intercostals and 
spine, behind. 

The Intercostal Muscles are two thin planes of muscular and tendinous struc- 
ture, placed one over the other, filling up the intercostal spaces, and being directed 
obliquely between the margins of the adjacent ribs. These two planes have re- 
ceived the name 'external' and 'internal,' from the position they bear to one an- 
other. 

The External Intercostals are eleven in number on each side, being attached to 
the adjacent margins of each pair of ribs, and extending from the tubercles of the 
ribs, behind, to the commencement of the cartilages of the ribs, in front, where 
they terminate in a thin membranous aponeurosis, which is continued forwards to 
the sternum. They arise from the outer lip of the groove on the lower border of 
each rib, and are inserted into the upper border of the rib below. In the two 
lowest spaces they extend to the end of the ribs. Their fibres are directed 
obliquely downwards and forwards, in a similar direction with those of the Exter- 
nal oblique muscle of the abdomen. They are thicker than the Internal inter- 
costals. 

Relations. The External intercostals, by their outer surface, are covered by 
the muscles which immediately invest the chest, viz., the Pectoralis major and 
minor, Serratus magnus, Ehomboideus major, Serratus posticus superior and infe- 
rior, Scalenus posticus, Sacro-lumbalis and Longissimus dorsi, Cervicalis ascendens, 
Transversalis colli, Levatores costarum, and the Obliquus externus abdominis. By 
their internal surface, they are in relation with a thin layer of fascia, which 
separates them from the intercostal vessels and nerve, the Internal intercostal mus- 
cles, and, behind, from the pleura. 

The Internal Intercostals, also eleven in number on each side, are placed on 
the inner surface of the preceding, commencing anteriorly at the sternum, in the 
interspaces between the cartilages of the true ribs, and from the anterior extre- 
mities of the cartilages of the false ribs; and extend backwards as far as the 
angles of the ribs, where they are continued to the vertebral column by a thin 
aponeurosis. They arise from the inner lip of the groove on the lower border of 
each rib, as well as from the corresponding costal cartilage, and are inserted into 
the upper border of the rib below. Their fibres are directed obliquely downwards 
and backwards, decussating with the fibres of the preceding. 

Relations. By their external surface, with the External intercostals, and the 
intercostal vessels and nerves. By their internal surface, with the pleura costalis. 
Triangularis sterni, and Diaphragm. 

The Intercostal muscles consist of muscular and tendinous fibres, the latter 
being long and more numerous than the former; hence these spaces present very 
considerable strength, to which their crossing materially contributes. 

The Infra- Co stales consist of muscular and aponeurotic fasciculi, which vary 
in number and length; they arise from the inner surface of one rib, and are in- 
serted into the inner surface of the first, second, or third rib below. Their direc- 
tion is most usually oblique, like the Internal intercostals. They are most frequent 
between the lower ribs. 

The Triangularis Sterni is a thin plane of muscular and tendinous fibres, 
situated upon the inner wall of the front of the chest. It arises from the lower 
pari of the side of the sternum, from the inner surface of the ensiform cartilage, 
and from the sternal ends of the costal cartilages of the three or four lower true 
ribs. Its fibres diverge upwards and outwards, to be inserted by fleshy digitations 
into the lower border and inner surfaces of the costal cartilages of the second, 
third, fourth, and fifth ribs. The lowest fibres of this muscle are horizontal in 



238 MUSCLES AND FASCIA. 

their direction, and continuous with those of the Transversalis; those which suc- 
ceed are oblique, whilst the supei'ior fibres are almost vertical. This muscle varies 
much in its attachment, not only in different bodies, but on opposite sides of the 
same body. 

Relations. In front yfith the sternum, ensiform cartilage, the costal cartilages, 
the Internal intercostal muscles, and internal mammary vessels. Behind, with 
the pleura, pericardium, and anterior mediastinum. 

The Levatores Costarum, twelve in number on each side, are small tendinous 
and fleshy bundles, which arise from the extremities of the transverse processes 
of the dorsal vertebrae, and passing obliquely downwards and outwards, are in- 
serted into the upper rough surface of the rib below them, between the tubercle 
and the angle. That for the first rib arises from the transverse process of the last 
cervical vertebra, and that for the last from the eleventh dorsal. The Inferior 
levatores divide into two parts, one being inserted as above described, the other 
fasciculus passing downwards to the second rib below their origin; thus each of 
the lower ribs receives fibres from the transverse processes of tAvo vertebras. 

Nerves. The muscles of this group are supplied by the intercostal nerves. 
. Actions. The Intercostals are the chief agents in the movement of the ribs in 
ordinary respiration. The External intercostals raise the ribs, especially their fore 
part, and so increase the capacity of the chest from before backwards; at the same 
time they evert their lower borders, and so enlarge the thoracic cavity transversely. 
The Internal intercostals, at the side of the thorax, depress the ribs, and invert 
their lower borders, and so diminish the thoracic cavity; but at the fore part of 
the chest these muscles assist the External intercostals in raising the cartilages. 
The Levatores Costarum assist the external intercostals in raising the ribs. The 
Triangularis sterni draws down the costal cartilages; it is therefore an expiratory 
muscle. 

Diaphragmatic Region. 

Diaphragm. 

The Diaphragm {Aiacfipdaaco, to separate two parts) (fig. 150) is a thin mus- 
culo-fibrous septum, placed obliquely at the junction of the upper with the lower 
two-thirds of the trunk, and separating the thorax fi'om the abdomen, forming the 
floor of the former cavity and the roof of the latter. It is elliptical, its longest 
diameter being from side to side, somewhat fan-shaped, the broad elliptical portion 
being horizontal, the narrow part, which represents the handle, being vertical, and 
joined at right angles with the former. It is from this circumstance that some 
anatomists describe it as consisting of two portions, the upper or great muscle of 
the diaphragm, and the lower or lesser muscle. This muscle arises from the 
whole of the internal circumference of the thorax, being attached, in front, by 
fleshy fibres to the ensiform cartilage; on either side, to the inner surface of the 
cartilages and bony portions of the six or seven inferior ribs, interdigitating with 
the Transversalis; and behind, to the ligamentum arcuatum externum and in- 
ternum. The fibres from these sources vary in length; those arising from the 
ensiform appendix 'are very short and occasionally aponeurotic; but those from the 
ligamenta arcuata, and more especially those from the ribs at the side of the 
chest, are the longest, describe well marked curves as they ascend, forming an 
arch on each side with the concavity downwards, this concavity being deeper on 
the right than on the left side. These fibres converge, to be inserted into the 
circumference of the central tendon. Between the sides of the muscular slip 
from the ensiform appendix and the cartilage of the adjoining rib, the fibres of the 
diaphragm are deficient, the interval being filled by areolar tissue, covered on the 
thoracic side by the pleurae, on the abdominal by the peritoneum. This is, con- 
sequently, a weak point, and a portion of the contents of the abdomen may pro- 
trude into the chest, forming phrenic or diaphragmatic hernia, or a collection of 
pus in the mediastinum may descend through it so as to point at the epigastrium. 



DIAPHRAGMATIC REGION. 



239 



The Liganientum Arcuatum Internum is a tendinous ai'ch, thrown across the 
upper part of the Psoas magnus muscle, on each side of the spine. It arises from 
the outer side of the body of the first, and occasionally from the second lumljar 
vertebra, being continuous with the outer side of the tendon of the correspondino- 
crus, and, arching across the Psoas muscle, is attached to the front of the trans- 
verse process of the second lumbar vertebra. 

The Ligamentum Arcuatum Externum is the thickened upper margin of the 
anterior lamella of the transversalis fascia; it arches across the upper part of the 
Quadratus lumborum, being attached by one extremity to the front of the trans- 
verse process of the second lumbar vertebra, and by the other to the apex and 
lower margin of the last rib. 



150. — The Diaphragm. Under Surface. 




Ojtenir>5 J" 



Zesscr 



To the spine the Diaphragm is connected by two crura, which are situated on 
the bodies of the lumbar vertebrae, one on each side of the aorta. The crura at 
their origin are tendinous in structure; the right crus, larger and longer than the 
left, arising from the anterior surface of the bodies and intervertebral substances 
of the second, third, and fourth lumbar vertebrae; the left from the second and 
thii'd; and both blending with the anterior common ligament of the spine. A 
tendinous arch is thrown across the front of the vertebral column, from the 
tendon of one crus to that of the other, beneath which passes the aorta, vena 
azygos major, and thoracic duct. The tendons terminate in two large fleshy bellies, 
which, with the tendinous portions above alluded to, are called the crura, or 
pillars of the diaphragm. The outer fasciculi of the two crura are directed up- 
wards and outwards to the central tendon, but the inner fasciculi decussate in front 
of the aorta, and then diverge, so as to surround the ossophagus before ending in 



240 MUSCLES AND FASCIA. 

the tendinous centre. The most anterior and larger of these fasciculi is formed by 
the right crus. 

The Central or Cordiform Tendon of the Diaphragm is a thin tendinous aponeu- 
rosis, situated at the centre of the vault of this muscle, immediately beneath the 
pericardium, with which its circumference is blended in adults. It is shaped 
somewhat like a trefoil leaf, consisting of three divisions, or leaflets, separated 
from one another by slight indentations. The right leaflet is the largest; the 
middle one, directed towards the ensiform cartilage, the next in size; and the left 
the smallest. In structure, it is composed of several planes of fibres, which inter- 
sect one another at various angles, and unite into straight or curved bundles, an 
arrangement which afibrds additional strength to the tendon. 

The Openings connected with the Diaphragm are three large and several 
smaller apertures. The former are the aortic, oesophageal, and the opening for 
the vena cava. 

The Aortic Opening is the lowest and the most posterior of the three large 
apertures connected Avith this muscle. It is situated in the middle line, im- 
mediately in front of the bodies of the vertebrte. It is an osseo-aponeurotic 
aperture, formed by a tendinous arch throAvn across the front of the bodies of the 
vertebrse, from the crus on one side to that on the other, and transmits the aorta, 
vena azygos major, thoracic duct, and occasionally the left sympathetic nerve. 

The Oesophageal Opening, elliptical in form, muscular in structure, and formed 
by the two crura, is placed higher, and, at the same time, anterior, and a little to 
the left of the preceding. It transmits the oesophagus and pneumogastric nerves. 
The anterior margin of this aperture is occasionally tendinous, being formed by 
the margin of the central tendon. 

The Opening for the Vena Cava is situated the highest; it is quadrilateral in 
form, tendinous in structure, and placed at th6 junction of the right and middle 
leaflets of the central tendon, its margins being bounded by four bundles of tendi- 
nous fibres, which meet at right angles. 

The Right Crus transmits the sympathetic and the greater and lesser splanchnic 
nerves of the right side; the left crus, the greater and lesser splanchnic nerves of 
the left side, and the vena azygos minor. 

The Serous Membranes in relation with the Diaphragm are four in number; 
three lining its upper or thoracic surface, one its abdominal. The three serous 
membranes on its upper surface are the pleura on either side, and the serous layer 
of the pericardium, which covers the upper surface of the tendinous centre. The 
serous membrane covering its under surface is a portion of the general peritoneal 
membrane of the abdominal cavity. 

Peculiarities. The portion of the muscle described as arising from the last rib is 
occasionally aponeurotic in structure. The sternal attachment of the muscle is 
sometimes partially or entirely deficient. 

Relations. Its upper or thoracic surface is convex on each side, and corresponds 
with the pleura and lungs, more flattened at the centre where it supports the heart. 
The convexity of this surface is greater on the right than on the left side, reaching 
in the former situation as high as the junction of the fifth rib with the sternum, 
and in the latter as high as the sixth rib. It reaches much higher in the foetus 
than in the adult. 

Its under or abdominal surface is concave, more so on the right side, where it 
is in relation with the convex surface of the liver, than on the left, where it cor- 
responds to the spleen and great end of the stomach behind; it is also in relation 
with the kidneys, supra-renal capsules, transverse portion of the duodenum, pan- 
creas, and the solar plexus. 

Nerves. The Diaphragm is supplied by the phrenic nerves. 

Actions. The Diaphragm is the most important inspiratory muscle, being the 
only one brought into action in tranquil respiration. During inspiration, when 
the fibres of the Diaphragm contract, the muscle descends, forming an inclined 
plane, which extends from the ensiform cartilage to the tenth rib. During this 



OF THE UPPER EXTREMITY. 



241 



action, the cavity of the thorax is enlarged considerably from above downwards, 
and the abdominal viscera are pushed into the lower and fore part of the abdomen, 
which is much diminished in size. If the abdominal muscles and Diaphragm act 
together, the viscera are compressed and forced to the lower part of the abdominal 
cavity, as in most expulsory efforts, which are usually accompanied by a deep 
inspiration. During expiration, when the Diaphragm is relaxed, the muscle is 
convex, encroaching considerably on the cavity of the chest, particularly at the 
sides, its upper border, in a forced expiration, being on a level with the lower 
border of the fourth rib on the right side, and with the fifth on the left. During 
the action of the Diaphragm the oesophagus is compressed, the aperture through 
which it passes being chiefly muscular; the apertures for the vena cava and aorta 
are also compressed, but only to a very trifling extent, as the openings for the 
passage of these vessels are completely tendinous. Hiccough and sobbing are the 
result of spasmodic contraction of this muscle; and laughing and crying are pro- 
duced by its rapid alternation of contraction and relaxation, combined with 
laryngeal and facial movements. 



MUSCLES AND FASCIA OF THE UPPER EXTREMITY. 

The Muscles of the Upper Extremity are divisible into groups, corresponding 
with the different regions of the limb. 



Anterior Thoracic Region. 
Pectoralis major. 
Pectoralis minor. 
Subclavius. 

Lateral Thoracic Region. 
Serratus magnus. 

Acromial Region. 
Deltoid. 

Anterior Scapular Region. 

Subscapularis. 

Posterior Scapular Region. 

Supra-spinatus. 
Infra-spinatus. 
Teres minor. 
Teres major. 

Anterior Humeral Region. 

Coraco-brachialis. 
Biceps. 
Brachialis anticus. 

Posterior Humeral Region. 
Triceps. 
Sub-anconeus. 

Anterior Brachial Region. 

Pronator radii teres. 

Flexor carpi radialis. 

Palmaris longus. 

I Flexor carpi ulnaris. 

.Flexor sublimis digitorum. 
r^ ;h' j Flexor profundus digitorum. 
S ^ \ Flexor longus pollicis. 
^ \A \ Pronator quadratus. 









Radial Region. 

Supinator longus. 

Extensor carpi radialis longior. 

Extensor carpi radialis brevior. 



Posterior Brachial Region. 

( Extensor communis digitorum. 

I Extensor minimi digiti. 

I Extensor carpi ulnaris. 

I Anconeus. 

I Supinator brevis. 

Extensor ossis metacarpi pollicis. 

Extensor primi internodii pollicis. 
I Extensor secundi internodii pollicis. 
I Extensor indicis. 



ce 


<D 


u 


>-. 


© 


1:3 


5 


k1 


in 




Ph 


' s 




Hi 



Muscles of the Hand. 
Radial Region, 
Abductor pollicis. 

Flexor ossis metacarpi pollicis (opponens). 
Flexor brevis pollicis. 
Adductor pollicis. 

Ulnar Region. 

Palmaris brevis. 

Abductor minimi digiti. 

Flexor brevis minimi digiti. 

Flexor ossis metacarpi minimi digiti. 

Palmar Region. 

Lumbricales. 
Interossei palmares. 
Interossei dorsales. 



242 



MUSCLES AND FASCIA. 



3.D Lsseetbon of 
SHOULDER & ARM 



2.BEIMDo/'ELB0\M 



'^r 



FORE-ARIV! 



Dissection of Pectoral Region and Axilla (fig. 151). The arm being drawn away from 
the side nearly at right angles with the trunk, and rotated outwards, a vertical incision 
should be made through the integu- 
ment in the median line of the chest, 1 5 1 . — Dissection of Upper Extremity, 
from the upper to the lower part 
of the sternum; a second incision 
should be carried along the lower 
border of the Pectoral muscle, from 
the ensiform cartilage to the outer 
side of the axilla ; a third, from the 
sternum along the clavicle, as far as 
its centre ; and a fourth, from the 
middle of the clavicle obliquely 
downwards, along the interspace be- 
tween the Pectoral and Deltoid 
muscles, as low as the fold of the 
armpit. The flap of integument 
may then be dissected off in the 
direction indicated in the figure, 
but not entirely removed, as it 
should be replaced on completing 
the dissection. If a transverse in- 
cision is now made from the lower 
end of the sternum to the side of 
the chest, as far as the posterior 
fold of the armpit, and the integu- 
ment reflected outwards, the axillai-y 
space will be more completely ex- 
posed. 

Fascia OF THE Thorax. / , \ r b^. ,v,^uAR,r. 

c \ t^ \(5, PALM ^ HAND 

The Superficial Fascia of the 
thoracic region is a loose cellulo- 
fibrous layer, continuous v^itli 
the superficial fascia of the neck 
and upper extremity above, and 
of the abdomen below; oppo- 
site the mamma it subdivides into two layers, one of which passes in front, and 
the other behind this gland; and from both of these layers numerous septa pass 
into its substance, supporting its various lobes: from the anterior layer, fibrous 
processes pass forward to the integument and nipple, enclosing in their areolae 
masses of fat. These processes were called by Sir A. Cooper, the ligamenta 
suspensoria, from the support they afford to the gland in this situation. On 
removing the superficial fascia, the deep fascia of the thoracic region is exposed: 
it is a thin aponeurotic lamina, covering in the outer surface of the great Pectoral 
muscle, and sending numerous prolongations between its fasciculi: it is attached, 
in the middle line, to the front of the sternum, and above to the clavicle: it is 
very thin over the upper part of the muscle, somewhat thicker in the interval 
between the Pectoralis major and Latissimus dorsi, where it closes in the axillary 
space, and divides at the margin of the latter muscle into two layers, one of which 
passes in front and the other behind it; these proceed as far as the spinous pro- 
cesses of the dorsal vertebrEe, to w^hich they are attached. At the lower part of 
the thoracic region this fascia is well developed, and is continuous with the fibrous 
sheath of the Recti muscles. 




Anterior Thoracic Region. 



Pectoralis Major. 



Pectoralis Minor. 



Subclavius. 



The Pectoralis Major (fig. 152) is a broad, thick, triangular muscle, situated at 
the upper and anterior part of the chest, in front of the axilla. It arises, by short 
tendinous fibres, from the entire bi'eadth of the anterior border of the clavicle, its 



ANTERIOR THORACIC REGION. 



243 



sternal half or two-thirds, from one half the breadth of the anterior surface of the 
sternum, as low down as the attachment of the cartilage of the sixth or seventh 
rib, its origin consisting of aponeurotic fibres, which intersect with those of the 
opposite muscle: it also arises from the cartilages of all the true ribs, and from 
the aponeurosis of the External oblique muscle of the abdomen. The fibres from 
this extensive origin converge tOAvards its insertion, giving to the muscle a radi- 
ated appearance. Those fibres which arise from the clavicle pass obliquely down- 

152. — Muscles of the Chest and Front of the Arm. Superncial View. 




wards and outv/ards, and are usually separated from the rest by a cellular ui- 
terval, those from the lower part of the sternum and the cartilages of the lower 
true ribs pass upwards and outwards; whilst the middle fibres pass horizontally. 
As these three sets of fibres converge, they are so disposed that the upper overlap 
the middle, and the middle the lower portion, the fibres of the lower portion being 
folded backwards upon themselves; so that those fibres which are lowest in front, 
become highest at their point of insertion. They all terminate in a flat tendon, 
about two inches broad, which is inserted into the anterior lip of the bicipital 

R 2 



244 MUSCLES AND FASCIiE. 

groove of the humerus. This tendon consists of two laminae, placed one in front 
of the other, and usually blended together below. The anterior, the thicker, receives 
the clavicular and upper half of the sternal portion of the muscle; the posterior 
layer receiving the attachment of the lower half of the sternal portion. A pecu- 
liarity resulting from this arrangement is, that the fibres of the upper and middle 
portions of the muscle are inserted into the lower part of the bicipital ridge, those 
of the lower portion into the upper part. The tendon of the Pectoralis major, 
at its insertion, is connected with that of the Deltoid, and from its borders an 
expansion is given off above to the head of the humerus below to the fascia of 
the arm. 

Relations. By its anterior surface, with the Platysraa myoides, the mammary 
gland, the superficial fascia, and integument. By its posterior surface : its thoracic 
portion, with the sternum, the ribs and costal cartilages, the Subclavius, Pectoralis 
minor, Serratus magnus, and the Intercostals; by its axillary portion, it forms the 
anterior wall of the axillary space, and is in relation with the axillary vessels and 
nerves. By its outer border, it lies parallel with the Deltoid, from which it is 
separated by the cephalic vein and descending branch of the thoracico-acromialis 
artery. Its loiver border forms the anterior margin of the axilla, being at first 
sei:)arated from the Latissimus dorsi by a considerable interval; but both muscles 
gradually converge towards the outer part of this space. 

Peculiarities. In well developed muscular subjects, the sternal origins of the two 
Pectoral muscles ai'e separated only by a very narrow interval; but this interval 
is enlarged in those cases where these muscles are ill developed. Very rarely, the 
whole of the sternal portion is deficient. Occasionally, one or two additional 
muscular slips arise from the aponeurosis of the Extei'nal oblique, and become 
united to the lower margin of the Pectoralis major. 

Dissection. The Pectoralis major should now be detached by dividing the muscle along 
its attachment to the clavicle, and by making a vertical incision through its substance a 
little external to its line of attachment to the sternum and costal cartilages. The muscle 
should then be reflected outwards, and its tendon carefully examined. 

The Pectoralis minor is now exposed, and immediately above it, in the interval 
between its upper border and the clavicle, a strong fascia, the costo-coracoid 
membrane. This fascia, which protects the axillary vessels and nerves, is very 
thick and dense externally, where it is attached to the coracoid process, and is 
continuous with the fascia of the arm; more internally, it is connected with the 
lower border of the clavicle, as far as the inner extremity of the first rib: traced 
downwards, it passes behind the Pectoralis minor, surrounding, in a more or less 
complete sheath, the axillary vessels and nerves; and above, it sends a prolonga- 
tion behind the Subclavius, which is attached to the lower border of the clavicle, 
and so encloses this muscle in a kind of sheath. The costo-coracoid membrane is 
pierced by the cephalic vein, the thoracico-acromialis artery and vein, superior 
thoracic artery, and anterior thoracic nerve. 

The Pectoralis Minor (fig. 153) is a thin, flat, triangular muscle, situated at 
the upper part of the thorax, immediately beneath the Pectoralis major. It arises, 
by three delicate tendinous digitations, from the upper margin and external sur- 
face of the third, fourth, and fifth ribs, near their cartilages, and from the aponeu- 
rosis covering the Intercostal muscles: the fieshy fibres succeeding to these unite, 
and passing upwards and outwards, converge to form a flat tendon, which is in- 
serted into the anterior and upper margin of the coracoid process of the scapula. 

Relations. By its anterior surface, with the Pectoralis major, and the superior 
thoracic vessels and nerves. By its posterior surface, with the ribs. Intercostal 
muscles, Serratus magnus, the axillary space, and the axillary vessels and nerves. 
Its superior border is separated from the clavicle by a triangular interval, broad 
internally, narrow externally, bounded in front by the costo-coracoid membrane, 
and internally by the ribs. In this space are seen the axillary vessels and nerves. 

The costo-coracoid membrane should now be removed, when the Subclavius 
muscle will be seen. 



ANTERIOR THORACIC REGION. 



245 



The Subclaviiis is a long, thin, spindle-sliaped muscle, placed immediately 
beneath the clavicle, in the interval between it and the first rib. It arises by a 
short and thick tendon from the cartilage of the first rib, immediately in front of 
the rhomboid ligament; the fleshy fibres proceed outwards to be inserted by short 
tendinous fibres into a deep groove on the under surface of the middle third of the 
clavicle. 

Relations. By its upper surface, with the clavicle. By its under surface, it is 
separated from the first rib by the axillary vessels and nerves. Its anterior 
surface is separated from the Pectoralis major by a strong aponeurosis, which 
with the clavicle, forms an osteo-fibrous sheath in which the muscle is enclosed. 

153. — Muscles of the Chest and Front of the Arm, with the boundaries 

of the Axilla. 




If the costal attachment of the Pectoralis minor is divided across, and the muscle 
reflected outwards, the axillary vessels and nerves are brought fully into view, and 
should be examined. 

Nerves. The Pectoral muscles are supplied by the anterior thoracic nerves; the 
Subclavius, by a filament from the cord formed by the union of the fifth and sixth 
cervical nerves. 

Actions. If the arm has been raised by the Deltoid, the Pectoralis major will, 
conjointly with the Latissimus dorsi and Teres major, depress it to the side of the 
chest; and, if acting singly, it will draw the arm across the front of the chest. 
The Pectoralis minor depresses the point of the shoulder, drawing the scapula 
downwards and inwards to the thorax. The Subclavius depresses the shoulder, 



246 MUSCLES AND FASCIiE. 

drawing tlie clavicle dowriAvards and forwards. When the arms are fixed, all three 
muscles act upon the ribs, drawing them upwards and expanding the chest, thus 
becoming very important agents in forced inspiration. Asthmatic patients always 
assume this attitude, fixing the shoulders, so that all these muscles may be brought 
into action to assist in dilating the cavity of the chest. 

Lateral Thoracic Region. 

Serratus Magnus. 

The Serratus Magnus is a broad, thin, and irregularly quadrilateral muscle, 
situated at the upper part and side of the chest. It arises by eight fleshy digita- 
tions from the external surface and upper borders of the eight upper ribs, and from 
the aponeurosis covering the upper intercostal spaces, and is inserted into the whole 
length of the inner margin of the posterior border of the scapula. This muscle 
has been divided into three portions, a superior, middle, and inferior, on account 
of the difference in the direction, and in the extent of attachment of each part. 
The superior portion, separated from the rest by a cellular interval, is a narrow, 
but thick fasciculus, consisting of the first digitation, which arises by a double 
origin from the first and second ribs, and from the aponeurotic arch between them 
(called by some authors, first and second serrations); its fibres proceed upwards, 
outwards and backwards, to be inserted into the triangular smooth surface on the 
inner side of the superior angle of the scapula. The middle portion of the muscle, 
the broadest and thinnest of the three, consists of the second, third, and fourth 
digitations, the fibres from which form a thin and broad muscular layer, which 
proceeds horizontally backwards, to be inserted by short tendinous fibres into the 
posterior border of the scapula, between the superior and inferior angles. The 
largest portion of this division of the muscle is formed by the third digitation. 
The inferior portion of the muscle consists of four digitations, in the intervals 
between which are received corresponding processes of the External oblique; the 
muscular fibres from these converging, pass upwards, outwards, and backwards, to 
be inserted into the inner surface of the inferior angle of the scapula, by an attach- 
ment partly muscular, partly tendinous. 

Relations. This muscle is covered, in front, by the Pectoral muscles; behind, 
by the Subscapularis; above, by the axillary vessels and nerves. Its deep surface 
rests upon the ribs and intercostal spaces. 

Nerves. The Serratus magnus is supplied by the posterior thoracic nerve. 

Actions. The Serratus magnus is the most important external inspiratory 
muscle. When the shoulders are fixed, it elevates the ribs, and so dilates the 
cavity of the chest, assisting the Pectoral and Subclavius muscles. This muscle, 
especially its middle and lower segments, draws the base and inferior angle 
of the scapula forwards, and so raises the point of the shoulder by causing a rota- 
tion of the bone on the side of the chest; assisting the Trapezius muscle in sup- 
porting weights upon the shoulder, the thorax being at the same time fixed by 
preventing the escape of the included air. 

Dissection. After completing the dissection of the axilla, if the muscles of the back have 
been dissected, the upper extremity should be separated from the trunk. Saw through 
the clavicle at its centre, and then cut through the muscles which connect the scapula and 
arm with the trunk, viz., the Pectoralis minor, in front, Serratus magnus, at the side, and 
behind, the Levator anguli scapulse, the Rhomboids, Trapezius, and Latissimusdorsi. These 
muscles should be cleaned and traced to their respective insertions. An incision should 
then be made through the integument, commencing at the outer third of the clavicle, and 
extending along the margin of this bone, the acromion process, and spine of the scapula ; 
the integument should be dissected from above downwards and outwards, when the fascia 
covering the Deltoid is exposed. 

The Superficial Fascia of the upper extremity, is a thin cellulo-fibrous lamina, 
containing between its layers the superficial veins and lymphatics, and the cuta- 
neous nerves. It is most distinct in front of the elbow, and contains between 
its laminae in this situation the large superficial cutaneous veins and nerves; in 



LATERAL THORACIC AND ACROMIAL REGIONS. 247 

the hand it is hardly demonstrable, the integument being closely adherent to the 
deep fascia by dense fibrous bands. Small subcutaneous bursas are found in this 
fascia, over the acromion, the olecranon, and the knuckles. The deep fascia of 
the upper extremity comprises the aponeurosis of the shoulder, arm, and fore-arm, 
the anterior and posterior annular ligaments of the carpus, .and the palmar fascia. 
These will be considered in the description of the muscles of these several regions. 

AcROBiiAL Region. 

Deltoid. 

The Deep Fascia covering the Deltoid (deltoid aponeurosis) is a thick and 
strong fibrous layer, which covers the outer surface of the muscle, and sends down 
numerous prolongations between its fasciculi; it is continuous internally with that 
covering the great Pectoral muscle; behind, with the aponeurosis covering the 
Infra-spinatus and back of the arm; above, it is attached to the clavicle, the acro- 
mion, and spine of the scapula. 

The Deltoid is a large thick triangular muscle, which forms the convexity 
of the shoulder, and has received its name from its resemblance to the Grreek 
letter A reversed. It surrounds the shoulder -joint in the greater part of its 
extent, covering it on its outer side, and in front and behind. It arises, by tendi- 
nous fibres, from the outer third of the anterior border and upper surface of the 
clavicle; from the external margin and upper surface of the acromion process; 
and from the whole length of the inferior border of the spine of the scapula, as far 
back as the triangular surface which terminates it. From this extensive origin, 
the muscular fibres proceed downwards, and converge towards their insertion, the 
middle passing vertically, the anterior obliquely backwards, the posterior obliquely 
forwards; they unite to form a thick tendon, which is inserted into a rough pro- 
minence on the middle of the outer side of the shaft of the humerus. This muscle 
is remarkably coarse in its texture, and intersected by three or four tendinous 
laminge, attached at intervals to the clavicle and acromion; these extend into the 
substance of the muscle, and give origin to a number of fleshy fibres. The largest 
of these laminae extends from the summit of the acromion. 

Relations. By its superficial surface, with the Platysma, supra- acromial nerves, 
the superficial fascia, and integument. By its deep surface, it is separated from 
the Scapular muscles covering the head of the humerus by a large sacculated 
synovial bursa, and covers the coracoid process, coraco-acromial ligament, Pecto- 

ralis minor, Coraco-brachialis, both heads of the Biceps, tendon of the Pectoralis 
lajor, Teres major. Scapular, and external headsof the Triceps, the circumfiex vessels 

md nerve, and the humerus. Its anterior border is separated from the Pectoralis 
lajor by a cellular interspace, which lodges the cephalic vein and descending 

branch of the thoracico-acromialis artery. Its posterior border is thin above, 
Tthicker below, and bound down by the aponeurotic covering of the Infra-spinatus. 
Nerves. The Deltoid is supplied by the circumflex nerve. 

Actions. The Deltoid serves to raise the arm directly from the side, and to 
[bring it at right angles with the trunk. Its anterior fibres, assisted by the Pecto- 
Iralis major, draw the arm forwards; and its posterior fibres, aided by the Teres 
[major and Latissimus dor si, will draw it backwards. 

Dissection. Divide the Deltoid across, near its upper part, by an incision carried along 
the margin of the clavicle, the acromion process, and spine of the scapula, and reflect it 
downwards ; the bursa will be seen on its under surface, as well as the circumflex vessels 
and nerves, and External rotator muscle. The insertion of the muscle should be care- 
!_ fully - examined. 

Anterior Scapular Region, 
Subscapularis. 
The Subscapular Aponeurosis is a thin membrane, attached to the entire cir- 
cumference of the subscapular fossa, and afibrding attachment by its inner surface 



248 MUSCLES AND FASCIA. 

to some of the fibres of the Subscapularis muscle: when this is removed the Sub- 
scapularis muscle is exposed. 

The Subscapularis is a large triangular muscle, which fills up the whole of the 
subscapular fossa, arising from its internal two-thirds, with the exception of a 
narrow margin along the posterior border, and the small triangular portions of 
bone on the inner side of the superior and inferior angles, which afford attach- 
ment to the Serratus magnus. Some of the fibres arise from tendinous lamina3, 
which intersect the muscle, and are attached to ridges on the bone; and others 
from an aponeurosis attached to the anterior margin of the axillary border of the 
scapula, which separates this muscle from the Teres major and the long head of 
the Triceps. From this origin, the fibres pass outwards, and gradually converging, 
the muscle becomes narrow and thick, and terminates in a tendon, which is inserted 
into the lesser tuberosity of the humerus. Some of the muscular fibres which arise 
from the axillary border of the scapula are inserted into the neck of the bone to 
the extent of an inch below the tuberosity. The tendon of this muscle is in close 
contact with the capsular ligament of the shoulder-joint, and glides over a large 
bursa, which separates it from the base of the coracoid process. This bursa com- 
municates with the cavity of the joint by an aperture in the capsular ligament. 

Relations. By its anterior surface, with the Serratus magnus, some loose areolar 
tissue being interposed, the Coraco-brachialis, and Biceps, and the axillary vessels 
and nerves. By its posterior surface, with the scapula, the subscapular vessels 
and nerves, and the capsular ligament of the shoulder -joint. 

Nerves. It is supplied by the subscapular nerves. 

Actions. The Subscapularis rotates the head of the humerus inwards; when the 
arm is raised it draws the humerus downwards. It is a powerful defence to the 
front of the shoulder-joint, preventing displacement of the head of the bone for- 
wards. 

Posterior Scapular Region. 

Supra-spinatus. Teres Minor. 

Infra-spinatus. Teres Major. 

Dissection. To expose these muscles, and to examine their mode of insertion into the 
humerus, detach the Deltoid and Trapezius from their attachment to the spine of the 
scapula and acromion process. Eemove the clavicle by dividing the ligaments connecting 
it with the coracoid process, and separate it at its articulation with the scapula : divide 
the acromion process near its root with a saw, and the fragment being removed, the ten- 
dons of the posterior Scapular muscles will be fully exposed, and can be examined. A 
block should be placed beneath the shoulder-joint, so as to make the muscles tense. 

The Supraspinous Aponeurosis is a thick and dense membranous layer, attached 
to the entire circumference of the supra-spinous fossa, and completing the osteo- 
fibrous case in which the Supra-spinatus muscle is contained: by its inner surface 
it affords attachment to some of the fibres of this muscle. It is very thick inter- 
nally, but thinner externally under the cor aco- acromion ligament. When this 
fascia is removed, the Supra-spinatus muscle is exposed. 

The Supra-spinatus is a thick triangular muscle, which occupies the whole of 
the supra-spinous fossa, arising from its internal two-thirds, and from a strong 
fascia which covers the muscle and completes the osteo-fibrous sheath in which 
it is enclosed. From these points, the muscular fibres converge to a tendon, which 
passes across the capsular ligament of the shoulder-joint, to which it is intimately 
adherent, and is inserted into the highest of the three facets on the great tuberosity 
of the humerus. 

Relations. By its upper surface, with the Trapezius, the clavicle, the acromion, 
the coraco-acromion ligament, and the Deltoid. By its under surface, with the 
scapula, the supra-scapular vessels and nerve, and upper part of the shoulder- 
joint. 

The Infra-spinous Aponeurosis is a dense fibrous membrane, covering in the 
Infra-spinatus muscle, and attached to the entire circumference of the infra-spinous 



SCAPULAR REGIONS. 



249 



fossa; it affords attachment by its inner surface to some fibres of this muscle, is 
continuous externally with the fascia of the arm, and gives off from its under 
surface intermuscular septa, which separate it from the Teres minor, and the latter 
from the Teres major. 

The Infra-spinatus is a thick triangular muscle, which occupies the chief part 
of the infra-spinous fossa, arising by fleshy fibres, from its internal two-thirds; and 
by tendinous fibres, from the ridges on its surface: it also arises from a strong 
fascia which covers it externally, and separates it from the Teres major and 
minor. The fibres converge to a tendon, which glides over the concave border of 
the spine of the scapula, and passing across the capsular ligament of the shoulder- 



154. — Muscles on the Dorsum of the Scapula and the Triceps. 



\ 




joint, is inserted into the middle facet on the great tuberosity of the humerus. 
The tendon of this muscle is occasionally separated from the spine of the scapula 
by a synovial bursa, which communicates with the synovial membrane of the 
shoulder-joint. 

Relations. By its posterior surface, with the Deltoid, the Trapezius, Latissimus 
dorsi, and the integument. By its anterior surface, with the scapula, from which 
it is separated by the superior and dorsalis scapulte vessels, and with the capsular 
ligatnent of the shoulder-joint. Its lower border is in contact with the Teres 
minor, and occasionally united with it, and with the Teres major. 

The Teres 3finor is a narrow elongated muscle, which lies along the inferior 
border of the scapula. It arises from the dorsal surface of the axillary border of 
the scapula for the upper two-thirds of its extent, and from two aponeurotic 
laminae, which separate this muscle, one from the Infra-spinatus, the other from 



250 MUSCLES AND FASCIiE. 

the Teres major; its fibres pass obliquely upwards and outwards, and terminate in 
a thick tendon, which is inserted below the Infra- spinatus into the lowest of the 
three facets on the great tuberosity of the humerus, and, by fleshy fibres, into 
the humerus immediately below it. The tendon of this muscle, passes across 
the capsular ligament of the shoulder-joint. 

Relations. By its posterior surface, with the Deltoid, Latissimus dorsi, and 
integument. By its anterior surface, with the scapula, the dorsal branch of the 
subscapular artery, the long head of the Triceps, and the shoulder -joint. By its 
upper border, with the Infra-spinatus. By its lower border, with the Teres 
major, from which it separated anteriorly by the long head of the Triceps. 

The Teres Major is a broad and somewhat flattened muscle, which arises from 
the triangular surface on the dorsal aspect of the inferior angle of the scapula, 
and from the fibrous septa interposed between it and the Teres minor and Infra- 
spinatus; the fibres are directed upwards and outwards, and terminate in a flat 
tendon, about two inches in length, which is inserted into the posterior border of 
the bicipital groove of the humerus. The tendon of this muscle lies immediately 
behind that of the Latissimus dorsi, from which it is separated by a synovial 
bursa; it is also placed a little below that muscle at its insertion into the humerus. 

Relations. By its posterior surface, with the integument, from which it is sepa- 
rated internally by the Latissimus dorsi, and externally by the long head of the 
Triceps. By its anterior surface, with the Subscapularis, Latissimus dorsi, 
Coraco-brachialis, short head of the Biceps, the axillary vessels, and brachial plexus 
of nerves. Its upper border, is at first in relation with the Teres minor, from 
which it is afterwards sejaarated by the long head of the Triceps. Its loioer 
border forms, in conjunction with the Latissimus dorsi, part of the posterior boun- 
dary of the axilla. 

Nerves. The Supra and Infra-spinati muscles are supplied by the supra- 
scapular nerve; the Teres minor, by the circumflex; and the Teres major by the 
subscapular. 

Actions. The Supra- spinatus assists the Deltoid in raising the arm from the side; 
its action must, however, be very feeble, from the very disadvantageous manner in 
which the force is applied. The Infra-spinatus and Teres minor rotate the head 
of the humerus outwards; when the arm is raised, they assist in retaining it in 
that position, and carrying it backwards. One of the most important uses of 
these three muscles, is the great protection they afford to the shoulder joint, the 
Supra-spinatus supporting it above, and preventing displacement of the head of 
the humerus upwards, whilst the Infra-spinatus and Teres minor protect it behind, 
and prevent dislocation backwards. The Teres major assists the Latissimus dorsi 
in drawing the humerus downwards and backwards when previously raised, and 
rotating it inwards; when the arm is fixed, it may assist the Pectoral and Latis- 
simus dorsi muscles in drawing the trunk forwards. 

Anterior Humeral Region. 
Coraco-Brachialis. Biceps. Brachialis Anticus. 

Dissection. The arm being placed on the table, with the front surface uppermost, make 
a vertical incision through the integument along the middle line, from the middle of the 
interval between the folds of the axilla, to about two inches below the elbow joint, where 
it should be joined by a transverse incision, extending from the inner to the outer side of 
the fore-arm ; the two flaps being reflected on either side, the fascia should be examined. 

The Deep Fascia of the arm, continuous with that covering the shoulder and 
front of the great Pectoral muscle, is attached, above, to the clavicle, acromion, 
and spine of the scapula; it forms a thin, loose, membranous sheath investing the 
muscles of this region, sending down septa between them, and composed of fibres 
disposed in a circular or spiral direction, and these being connected together by 
vertical fibres. It differs in thickness at different parts, being thin over the Biceps, 
but thicker where it covers the Triceps and over the condyles of the humerus, and is 
strengthened by fibrous aponeuroses, which it derives from the Pectoralis major 



ANTERIOR HUMERAL REGION. 



251 



and Latissiraus dorsi, on the inner side, and from the Deltoid, externally. On 
either side it gives off a strong intermuscular septum, which is attached to the 
condyloid ridge and condyles on either side of the humerus. These septa serve 
to separate the muscles of the anterior, from those of the posterior brachial region. 
The external intermuscular septum extends from the lower part of the anterior 
bicipital ridge, along the external condyloid ridge, to the outer condyle; it is 
blended with the tendon of the Deltoid; gives attachment to the Triceps behind, 
to the Brachialis anticus. Supinator longus, and Extensor carpus radialis longior, 
in front; and is perforated by the musculo-spiral nerve, and superior profunda 
artery. The internal intermuscular septum, thicker than the preceding, extends 
from the lower part of the posterior bicipital groove below the Teres major, along 
the internal condyloid ridge to the inner condyle; it is blended with the tendon of 
the Coraco-brachialis, and affords attachment to the Triceps, behind, and the 
Brachialis anticus, in front. It is perforated by the ulnar nerve, and the inferior 
profunda and anastomotic arteries. At the elbow the deep fascia takes attachment 
to all the prominent points around this joint, and is continuous with the fascia of 
the fore-arm. On the removal of this fascia the muscles of the anterior humeral 
region are exposed. 

The Cor aco- Brachialis, the smallest of the three muscles in this region, is 
situated at the upper and inner part of the arm. It arises from the apex of the 
coracoid process of the scapula, in common with the short head of the biceps, and 
from the inter-muscular septum between these two muscles; the fibres pass down- 
wards, backwards, and a little outwards, to be inserted by means of a flat tendon 
into a rough line at the middle of the inner side of the shaft of the humerus. It 
is perforated by the musculo-cutaneous nerve. The inner border of this muscle 
forms a guide to the performance of the operation of tying the brachial artery in 
the upper part of its course. 

Relations. By its anterior surface, with the Deltoid and Pectoralis major above, 
at its insertion it is crossed by the brachial artery. By its posterior surface, with 
the tendons of the Subscapularis, Latissimus dorsi, and Teres major, the short head 
of the Triceps, the humerus, and the anterior circumflex vessels. By its inner 
border, with the brachial artery, and the median and musculo-cutaneous nerves. 
By its outer border, with the short head of the Biceps and Brachialis anticus. 

The Biceps is a long fusiform muscle, situated along the anterior aspect of the 
arm its entire length, and divided above into two portions or heads, from which 
circumstance it has received its name. Its internal or short head arises by a thick 
flattened tendon from the apex of the coracoid process of the scapula, in common 
with the Coraco-brachialis. The external or long head, arises from the upper 
margin of the glenoid cavity of the scapula, by a long rounded tendon, which is 
continuous with the glenoid ligament. This tendon passes across the head of the 
humerus, being enclosed in a special sheath of the synovial membrane of the 
shoulder joint; it then pierces the capsular ligament at its attachment to the 
humerus, and descends in the bicipital groove which separates the two tuberosities 
in which it is retained by a sort of fibrous bridge. The fibres from this tendon 
form a rounded belly, which about the middle of the arm joins with the short 
portion of the muscle. The belly of the muscle, narrow and somewhat flattened, 
terminates above the elbow in a flattened tendon, which is inserted into the 
posterior part of the tuberosity of the radius, a synovial bursa being interposed 
between the tendon and the anterior part of the tuberosity. The tendon of this 
muscle is thin and broad; as it approaches the radius it becomes narrowed and 
twisted upon itself, being applied by a flat surface to the posterior part of the 
tuberosity, and opposite the bend of the elbow gives off, from its inner side, a 
broad aponeurosis, which passes obliquely downwards and inwards across the 
brachial artery, and is continuous with the fascia of the fore-arm. The inner 
border of this muscle forms a guide to the performance of the operation of tying 
the brachial artery in the middle of the arm. 

Relations. Its anterior surface is overlapped above by the Pectoralis major and 



252 MUSCLES AND FASCI-^. 

Deltoid; in the rest of its extent it is covered by the superficial and deep fascife 
and the integument. Its posterior surface rests on the shoulder-joint and humerus, 
from which it is separated by the Subscapularis, Teres major, Latissimus dorsi, 
Brachialis anticus, and the musculo-cutaneous nerve. Its inner border is in rela- 
tion with the Coraco-brachialis, the brachial vessels, and median nerve. By its 
outer border, with the Deltoid and Supinator longus. 

The Brachialis Anticus is a broad muscle, which covers the whole of the ante- 
rior svirface of the lower part of the humerus. It is somewhat compressed from 
before backwards, and is broader in the middle than at either extremity. It arises 
from the lower half of the external and internal surfaces of the shaft of the 
humerus, commencing above at the insertion of the Deltoid, which it embraces by 
two well marked angular processes, and extending, below, to within an inch of the 
margin of the articular surface, and being limited on each side by the external 
and internal borders. It also arises from the inter-muscular septa on each side, 
but more extensively from the inner than the outer. Passing down in front of 
the elbow joint, its fibres converge to a thick tendinous fasciculus, which is inserted 
into a rough depression on the lower part of the coronoid process of the ulna, being 
received into a notch at the upper part of the Flexor digitorum profundus. 

Relations. By its anterior surface, with the Biceps, musculo-cutaneous nerve, 
the brachial vessels, and median nerve. By its posterior surface, with the humerus 
and anterior ligament of the elbow joint. By its inner border, with the Triceps, 
ulnar nerve, and Pronator radii teres, from which it is separated by the inter- 
muscular septa. By its outer border, with the musculo-spiral nerve, radial recur- 
rent artery, the Supinator longus, and Extensor carpi radialis longior. 

Nerves. The muscles of this group are supplied by the musculo-cutaneous nerve. 
The Brachialis anticus receives an additional filament from the musculo-spiral. 

Actions. The Coraco-brachialis draws the humerus forwards and inwards, and 
at the same time assists in elevating it towards the scapula. The Biceps and 
Brachialis anticus are flexors of the fore-arm; the former muscle is also a supina- 
tor, and serves to render tense the fascia of the fore-arm by means of the broad 
aponeurosis given off from its tendon. When the fore-arm is fixed, the Biceps 
and Brachialis anticus flex the arm upon the fore-arm, as is seen in the efforts of 
climbing. The Brachialis anticus forms an important defence to the elbow joint. 

Posterior Humeral Region. 
Triceps. Subanconeiis. 

The Triceps is the only muscle situated on the back of the arm, extending 
the entire length of the posterior surface of the humerus. It is of large size, and 
divided above into three portions or heads; hence the name of the muscle. These 
three portions have been named, the middle or long head, the external, and the 
internal or short head. 

The middle or long head arises, by a flattened tendon, from a rough triangular 
depression, immediately below the glenoid cavity of the scapula, being blended at 
its upper part with the glenoid ligament; the muscular fibres pass downwards 
between the two other portions of the muscle, and join with them in the common 
tendon of insertion. 

The external head arises from the posterior surface of the shaft of the humerus, 
between the insertion of the Teres minor and the upper part of the musculo-spiral 
groove, from the external border of the humerus and external intermuscular 
septum: the fibres from this origin converge towards the common tendon of 
insertion. 

The internal or short head arises from the whole of the posterior surface of the 
shaft of the humerus, below the groove for the musculo-spiral nerve, commencing 
above, narrow and pointed, immediately below the insertion of the Teres major, 
and extending, below, to Avithin an inch of the trochlear surface; it also arises 
from the internal border and internal intermuscular septum. The fibres of this 



POSTERIOR HUMERAL REGION. 253 

portion of the muscle are directed, some downwards to the olecranon, whilst others 
converge to the common tendon of insertion. 

The common tendon of the Triceps commences about the middle of the back 
part of the muscle: it consists of two aponeurotic laminae, one of which is sub- 
cutaneous, and covers the posterior surface of the muscle for the lower half of its 
extent; the other layer is more deeply seated in the substance of the muscle: after 
receiving the attachment of the muscular fibres, they join together immediately 
above the elbow, and are inserted into the posterior part of the upper surface of 
the olecranon process, a small bursa, occasionally multilocular, being interposed 
between the tendon and the front of this surface. 

The long head of the Triceps passes between the Teres minor and Teres major, 
dividing the triangular space between these two muscles and the humerus into two 
smaller spaces, one triangular, the other quadrangular (fig. 154). The triangular 
space transmits the dorsalis scapulas artery and veins, being bounded by the Teres 
minor above, the Teres major below, and the scapular head of the Triceps ex- 
ternally: the qviadrangular space transmits the posterior circumflex vessels and 
nerve; it is bounded by the Teres minor above, the Teres major below, the sca- 
pular head of the Triceps internally, and the humerus externally. 

Relations. By its posterior surface, with the integument, superficial and deep 
fascia, and integument. By its anterior surface, with the humerus, musculo- 
spiral nerve, sujDerior profunda artery, and back part of the elbow-joint. Its 
middle or long head is in relation, behind, with the Deltoid and Teres minor; in 
front, with the Subscapularis, Latissimus dorsi, and Teres major. 

Subanconeus. This is a small muscle, distinct from the Triceps, and analogous 
to the Subcrureus in the lower limb. It may be exposed by removing the Triceps 
from the lower part of the humerus. It consists of one or two slender fasciculi, 
which arise from the humerus, immediately above the olecranon fossa, and are 
inserted into the posterior ligament of the elbow-joint. 

Nerves. The Triceps and Subanconeus are supplied by the musculo-spii-al 
nerve. 

Actions. The Triceps is the great Extensor muscle of the fore-arm; when the 
fore-arm is flexed, serving to draw it into a right line with the arm. It is the 
direct antagonist of the Biceps and Brachialis anticus. When the arm is extended, 
the long head of this muscle may assist the Teres major and Latissimus dorsi in 
drawing the humerus backwards. The long head of the Tricejis protects the 
under part of the shoulder-joint, and prevents displacement of the head of the 
humerus downwards and backwards. 

Muscles of the Fore-arm. 

Dissection. To dissect the fore-arm, place the limb in the position indicated in fig. 151; 
make a vertical incision along the middle line from the elbow to the wrist, and connect 
each extremity with a transverse incision ; the flaps of integument being removed, the 
fascia of the fore-arm is exposed. 

The Deep Fascia of the fore-arm, continuous above with that enclosing the arm, 
is a dense highly glistening aponeurotic investment, which forms a general sheath 
enclosing all the muscles in this region; it is attached behind to the olecranon and 
posterior border of the ulna, and gives ofi* from its inner surface numerous inter- 
muscular septa, which enclose each muscle separately. It consists of circular and 
oblique fibres, connected together at right angles by numerous vertical fibres. It 
is much thicker on the dorsal than on the palmar surface, and at the lower than 
at the upper part of the fore-arm, and is strengthened by tendinous fibres, derived 
from the Brachialis anticus and Biceps in front, and from the Triceps behind. 
Its inner surface affords extensive origin for muscular fibres, especially at the 
upper part of the inner and outer sides of the fore-arm, and forms the boundaries 
of a series of conical- shaped fibrous cavities, in which the muscles in this region 
are contained. Besides the vertical septa separating , each muscle, transverse 
septa are given oiF both on the anterior and posterior surfaces of the fore-arm. 



254 



MUSCLES AND FASCIA. 



separating the deep from the superficial layer of muscles. Numerous apertures 
exist in the fascia for the passage of vessels and nerves; one of these, of large 
size, situated at the front of the bend of the elbow, serves for the passage of a 
communicating branch between the superficial and deep veins. 

The muscles of the fore-arm may be subdivided into groups corresponding to 
the region they occupy. The first group occupies the inner and anterior aspect of 
the fore-arm, and comprises the Flexor and Pronator muscles. The second group 
occupies the outer side of the fore-arm; and the third, its posterior aspect. The 
two latter groups include all the Extensor and Supinator muscles. 

Anterior Brachial Region. 



155. 



-Front of the Left Fore-arm. 
Superficial Muscles. 




Superficial Layer. 

Pronator radii teres. 
Flexor carpi radialis. 
Palmaris longus. 
Flexor carpi ulnaris. 
Flexor sublimis digitorum. 

All these muscles take origin from 
the internal condyle by a common 
tendon. 

The Pronator Radii Teres arises 
by two heads. One, the largest and 
most, superficial, from the humerus, 
immediately above the internal condyle, 
and from the tendon common to the 
origin of the other muscles; also from 
the fascia of the fore-arm, and inter- 
muscular septum between it and the 
Flexor carpi radialis. The other head 
is a thin fasciculus, which arises from 
the inner side of the coronoid process 
of the ulna, joining the other at an 
acute angle. Between the two heads 
passes the median nerve. The muscle 
passes obliquely across the fore-arm 
from the inner to the outer side, and 
terminates in a flat tendon, which 
turns over the outer margin of the 
radius, and is inserted into a rough 
ridge at the middle of the outer sur- 
face of the shaft of that bone. 

Relations. By its anterior surface, 
with the fascia of the fore-arm, the Su- 
pinator longus, and the radial vessels 
and nerve. By its posterior surface, 
with the Brachialis anticus. Flexor 
sublimis digitorum, the median nerve, 
and ulnar artery. Its upper border 
forms the inner boundary of a trian- 
gular space, in which is placed the 
brachial artery, median nerve, and 
tendon of the Biceps muscle. Its 
lower border is in contact with the 
Flexor carpi radialis. ^""~~^^- 



ANTERIOR BRACHIAL REGION. 



255 



The Flexor Carpi Radialis lies on the inner side of the preceding muscle. 
It arises from the internal condyle by the common tendon, from the fascia of the 
fore-arm, and from the inter-muscular septa between it and the Pronator teres, on 
the inside; the Palmaris longus, externally; and the Flexor sublimis digitorum, 
Ijeneath. Slender and aponeurotic in structure at its commencement, it increases 
in size, and terminates in a tendon which forms the lower two-thirds of its struc- 
ture. This tendon passes through a separate opening on the outer side of the 
annular ligament, runs through a groove in the os trapezium, converted into a 
canal by a thin fibrous sheath, lined by a synovial membrane, and is inserted into 
the base of the metacarpal bone of the index finger. The radial artery lies 
between the tendon of this muscle and the Supinator longus, and may easily be 
secured in this situation. 

Relations. By its superficial surface, with the fascia of the fore-arm and the 
integument. By its deep surface, with the Flexor sublimis digitorum. Flexor 
longus pollicis, and wrist joint. By its outer border, with the Pronator radii teres, 
and the radial vessels. By its inner border, with the Palmaris longus. 

The Palmaris Longus is a slender fusiform muscle, lying on the inner side of 
the preceding. It arises from the inner condyle of the humerus by the common 
tendon, from the fascia of the fore-arm, and inter-muscular septa, between it and 
the adjacent muscles. It terminates in a slender flattened tendon, which forms 
the lower two-thirds of its structure, being inserted into the annular ligament, and 
expanding to be continuous Avith the palmar fascia. 

Variations. This muscle is often found wanting; when it exists, it presents 
many varieties. Its fleshy belly is sometimes very long, or it may occupy the 
middle of the muscle, which is tendinous at either extremity; or it may be mus- 
cular at its lower extremity, its upper part being tendinous. Occasionally there 
is a second Palmaris longus placed on the inner side of the preceding, terminating, 
below, partly in the annular ligament or fascia, and partly in the small muscles of 
the little finger. 

Relations. By its anterior surface, with the fascia of the fore-arm. By its 
posterior surface, with the Flexor digitorum sublimis. Internally, with the 
Flexor carpi ulnaris. Externally, with the Flexor carpi radialis. 

The Flexor carpi ulnaris lies along the ulnar side of the fore-arm. It arises 
by two heads, separated by a tendinous arch, beneath which passes the ulnar nerve, 
and posterior ulnar recurrent artery. One head arises from the inner condyle of 
the humerus, by the common tendon; the other, from the inner margin of the 
olecranon, and by an aponeurosis from the upper two-thirds of the posterior border 
of the ulna. It also arises from the inter-muscular septum between it and the 
Flexor sublimis digitorum. The muscular fibres terminate in a tendon, which is 
inserted on the anterior surface of the pisiform bone, the tendon being pro- 
longed to the annular ligament and base of the metacarpal bone of the little finger. 
The ulnar artery lies on the outer side of the tendon of this muscle, in the lower 
two-thirds of the fore-arm; the tendon forming a guide to the operation of in- 
cluding this vessel in a ligature in this situation. 

Relations. By its anterior surface, with the fascia of the fore-arm, with which 

it is intimately connected for a considerable extent. By its posterior surface, with 

the Flexor sublimis, the Flexor profundus, the Pronator quadratus, and the ulnar 

Ivessels and nerve. By its outer or radial border, with the Palmaris longus, above; 

ibelow, with the ulnar vessels and nerve. 

The Flexor Digitorum Sublimis is placed beneath the preceding muscles; these 

therefore require to be removed before its entire extent of attachment is brought 

into view. It is the largest of the muscles of the superficial layer, and arises by 

tthree distinct heads. One from the internal condyle of the humerus by the com- 

Imon tendon, from the internal lateral ligament of the elbow joint, and from the 

I inter-muscular septum common to it and the preceding muscles. The second head 

[^arises from the coronoid process of the ulna, above' the ulnar origin of the Pro- 

lator radii teres. The third head arises by tendinous fibres from the oblique line 



256 MUSCLES AND FASCIiE. 

of the radius, extending from the tubercle above, to the insertion of the Pronator 
radii teres below. The muscular fibres pass vertically downwards, forming a 
broad and thick muscle, which divides into four tendons about the middle of the 
fore-arm; as these tendons pass beneath the annular ligament into the palm of the 
hand, they are arranged in pairs, the anterior pair corresponding to the middle and 
ring fingers; the posterior pair to the index and little fingers. The tendons 
diverge from one another as they pass onwards, and are finally inserted into the 
lateral margins of the second phalanges, about their centre. Opposite the base of 
the first phalanges, each tendon divides, so as to leave a fissured interval, between 
which passes one of the tendons of the Flexor profundus, and they both enter an 
osso-aponeurotic canal, formed by a strong fibrous band which arches across them, 
and is attached on each side to the mai'gins of the phalanges. The two portions 
into which the tendon of the Flexor sublimis divides, so as to admit of the passage 
of the deep flexor, expand somewhat, and form a grooved channel into which the 
accompanying deep flexor tendon is received; the two divisions then unite, and 
finally subdivide a second time to be inserted into the fore part and sides of the 
second phalanges. The tendons whilst contained in the fibro-osseous canals are 
connected to the phalanges by slender tendinous filaments, called vincula acces- 
soria tendinum. A synovial sheath invests the tendons as they pass beneath the 
annular ligament; a similar membrane surrounds each tendon as it passes along 
the phalanges. 

Relations. In the fore-arm. By its anterior surface, with the deep fascia and 
all the preceding superficial muscles. By its posterior surface, with the Flexor 
profundus digitorum, Flexor longus pollicis, the ulnar vessels and nerves, and the 
median nerve. In the hand, its tendons are in relation, in front, with the palmar 
fascia, superficial palmar arch, and the branches of the median nerve. Behind, 
with the tendons of the deep Flexor and the Lumbricales. 

Anterior Brachial Region. 

Deep Layer. 

Flexor Profundus Digitorum. Flexor Longus Pollicis. 

Pronator Quadratus. 

Dissection. Divide each of the superficial muscles at its centre, and turn either end aside, 
the deep layer of muscles, together with the median nerve and ulnar artery, will then be 
exposed. 

The Flexor Profundtis Digitorum {perforans) is situated on the ulnar side of 
the fore-arm, immediately beneath the superficial Flexors. It arises from the upper 
two-thirds of the anterior and internal surfaces of the shaft of the ulna, embracing 
above, the insertion of the Brachialis anticus, and extending, below, to within a 
short distance of the Pronator quadratus. It also arises from a depression on the 
inner side of the coronoid process, by an aponeurosis from the upper two-thirds of 
the posterior border of the ulna, and from the ulnar half of the interosseous mem- 
brane. The fibres from these origins pass downwards, forming a fleshy belly of 
considerable size, which divides into four unequal portions, each of which termi- 
nates in a tendon which passes beneath the annular ligament beneath the tendons of 
the Flexor sublimis. Opposite the first phalanges, the tendons pass between the 
two slips of the tendons of the Flexor sublimis, and are finally inserted into the 
bases of the last phalanges. The tendon of the index finger is distinct; the rest 
are connected together by cellular tissue and tendinous slips, as far as the palm of 
the hand. 

Four small muscles, the Lumbricales, are connected with the tendons of the 
Flexor profundus in the palm. They will be described with the muscles in that 
region. 

Relations. By its anterior surface, in the fore-arm, with the Flexor sublimis 
digitorum, the Flexor carpi ulnaris, the ulnar vessels and nerve, and the median 
nerve; and in the hand, with the tendons of the superficial Flexor. By its 



ANTERIOR BRACHIAL RECIION. 



257 



posterior surface, in the fore- 
arm, with the ulna, the inter- 
osseous ligament, the Pronator 
quadratus; and in the hand, 
with the Interossei, Adductor 
pollicis, and deep palmar arch. 
By its ulnar border, with the 
Flexor carpi ulnaris. By its 
radial border, with the Flexor 
longus pollicis, the anterior 
interosseous artery and nerve 
being interposed. 

The Flexor Longus Polli- 
cis is situated on the radial 
side of the fore-arm, lying on 
the same plane as the prece- 
ding. It arises from the up- 
per two-thirds of the grooved 
anterior surface of the shaft 
of the radius; commencing, 
above, immediately below the 
tuberosity and oblique line, 
and extending, below, to with- 
in a short distance of the 
Pronator quadratus. It also 
arises from the adjacent part 
of the interosseous membrane, 
and occasionally by a fleshy 
slip from the inner side of the 
base of the coronoid process. 
The fibres pass downwards 
and terminate in a flattened 
tendon, which passes beneath 
the annular ligament, is then 
lodged in the inter- space be- 
tween the two heads of the 
Flexor brevis pollicis, and 
entering a tendino-osseous ca- 
nal, similar to those for the 
other flexor tendons, is in- 
serted into the base of the 
last phalanx of the thumb. 

Relations. By its anterior 
surface, with the Flexor sub- 
limis digitorum. Flexor carpi 
radialis. Supinator longus, and 
radial vessels. By its poste- 
rior surface, with the radius, 
interosseous membrane, and 
Pronator quadratus. By its 
ulnar border, with the Flexor 
profundus digitorum, from 
which it is separated by the 
anterior interosseous artery 
and nerve. 

The Pronator Quadratus 
is a small muscle, quadrilateral 



156. — Front of the Left Fore-arm. Deep Muscles. 




258 „ MUSCLES AND FASCIA.. 

in form, extending transversely across the radius and ulna, immediately above 
their carpal extremities. It arises from the oblique line on the lower fourth of 
the anterior surface of the shaft of the ulna, and the surface of bone immediately 
below it; from the internal border of the ulna; and from a strong aponeurosis 
which covers the inner third of the muscle. The fibres pass horizontally out- 
wards, to be inserted into the lower fourth of the anterior surface and external 
border of the shaft of the radius. 

Relations. By its anterior surface, with the Flexor profundus digitorvim, the 
Flexor longus poUicis, Flexor carpi radialis, and the radial and ulnar vessels, and 
ulnar nerve. By its posterior surface, with the radius, ulna, and interosseous 
membrane. 

Nerves. All the muscles of the superficial layer are supplied by the median 
nerve, excepting the Flexor carpi ulnaris, whicli, is supplied by the ulnar. Of 
the deep layer, the Flexor profundus digitorum is supplied conjointly by the 
ulnar and anterior interosseus nerves, the Flexor longus pollicis and Pronator 
quadratus by the anterior interosseous nerve. 

Actions. These muscles act upon the fore-arm, the wrist, and hand. Those 
acting on the fore-amn, are the Pronator radii teres and Pronator quadratus, which 
rotate the radius upon the ulna, rendering the hand prone; when pronation has 
been fully effected, the Pronator radii teres assists the other muscles in flexing 
the fore-arm. The flexors of the wrist are the Flexor carpi ulnaris and radialis; 
and the flexors of the phalanges are the Flexor sublimis and Profundus digitorum; 
the former flexing the second phalanges, and the latter the last. The Flexor longus 
pollicis flexes the last phalanx of the thumb. The three latter muscles, after flexing 
the phalanges by continuing their action, act upon the wrist, assisting the ordinary 
flexors of this joint; and all assist in flexing the fore-arm upon the arm. The 
Palmaris longus is a tensor of the palmar fascia; when this action has been fully 
effected, it flexes the hand upon the fore-arm. 

Radial Region. 

Supinator Longus. Extensor Carpi Radialis Longior. 

Extensor Carpi Radialis Brevior. 

Dissection. Divide the integument in the same manner as in the dissection of the ante- 
rior brachial region ; and after having examined the cutaneous vessels and nerves and deep 
fascia, they should be removed, when the muscles of this region will be exposed. The 
removal of the fascia will be considerably facilitated by detaching it from below upwards. 
Great care should be taken to avoid cutting across the tendons of the muscles of the 
thumb. 

The Supinator Longus is the most superficial muscle on the radial side of 
the fore-ai*m, fleshy for the upper two-thirds of its extent, tendinous below. It 
arises from the upper two-thirds of the external condyloid ridge of the humerus, 
and from the external intermuscular septum being limited above by the musculo- 
spiral groove. The fibres descend on the anterior and outer side of the fore-arm, 
and terminate in a flat tendon, which is inserted into the base of the styloid pro- 
cess of the radius. 

Relations. By its superficial surface, with the integument and fascia for the 
greater part of its extent; near its insertion it is crossed by the Extensor ossis 
metacarpi pollicis and the Extensor primi internodii pollicis. By its deep surface, 
with the humerus, the Extensor carpi radialis longior and brevior, the insertion of 
the Pronator radii teres, and the Supinator brevis. By its imier border, above the 
elbow with the Brachialis anticus, the musculo-splral nerve, and radial recurrent 
artery; and in the fore-arm, with the radial vessels and nerve. 

The Extensor Carpi Radialis Longior is placed partly beneath the preceding 
muscle. It arises from the lower third of the external condyloid ridge of the, 
humerus, immediately below the Supinator longus, and from the external inter- 
muscular septum. The fibres pass downwards, and terminate at the upper third 
of the fore-arm in a flat tendon, which runs along the outer border of the radius. 



RADIAL REGION. 



259 



157. — Posterior Surface of Forearn. Superficial Muscles. 




beneath the extensor tendons 
of the thumb; it then passes 
through a groove common to 
it and the Extensor carpi 
radialis brevior, immediately 
behind the styloid process; 
and is inserted into the base 
of the metacarpal bone of the 
index finger, its radial side. 

Relations. By its superfi- 
cial surface, with the Supi- 
nator longus and fascia of the 
fore-arm. Its outer side, 
is crossed obliquely by the 
Extensor ossis metacarpi pol- 
licis and the Extensor primi 
internodii pollicis; and at the 
wrist by the Extensor secundi 
internodii pollicis. By its 
deep surface, with the elbow- 
joint, the Extensor carpi ra- 
dialis brevior, and back part 
of the wrist. 

The Extensor Carpi Ra- 
dialis Brevior is shorter, as 
its name implies, and thicker 
than the preceding muscle, 
beneath which it is placed. 
It arises from the external 
condyle of the humerus by a 
tendon common to it and the 
other extensor muscles; from 
the external lateral ligament 
of the elbow-joint; from a 
strong aponeurosis which co- 
vers its surface; and from the 
intermuscular septum between 
it and the adjacent muscles. 
The fibres pass downwards, 
and terminate about the mid- 
dle of the fore-arm in a flat 
tendon, which is closely con- 
nected with that of the pre- 
ceding muscle, accompanies it 
to the wrist, lying in the same 
groove on the posterior surface 
of the radius; passes beneath 
the annular ligament, and di- 
verging somewhat from its 
fellow, is inserted into the 
base of the metacarpal bone 
of the middle finger, its radial 
side. 

The tendons of the two 

preceding muscles, as they 

pass across the same groove 

at the back of the radius, are 

s 2 



26o MUSCLES AND FASCIA. 

retained in it by a fibrous sheath, kibricated by a single synovial membrane, 
but separated from each other by a small vertical ridge of bone. 

Relations. By its superficial surface, with the Extensor carpi radialis longior, 
and crossed by the Extensor muscles of the thumb. By its deep surface, with the 
Supinator brevis, tendon of the Pronator radii teres, radius and wrist-joint. By 
its ulnar border, with the Extensor communis digitorum. 



Posterior Brachial Region. 

Superficial Layer. 

Extensor Communis Digitorum. Extensor Carpi Ulnaris. 

Extensor Minimi Digiti. Anconeus. 

The Extensor Communis Digitorum is situated at the back part of the fore-arm. 
It arises from the external condyle of the humerus by a tendon common to it and 
the other superficial Extensor muscles, from the deep fascia, and the inter- 
muscular septa between it and the adjacent muscles. Just below the middle 
of the fore-arm it divides into four tendons, which pass in a separate sheath be- 
neath the posterior annular ligament of the wrist, lubricated by a synovial mem- 
brane. The tendons then diverge, the two middle ones passing along the dorsal 
surface of the corresponding metacarpal bones, the lateral ones crossing obliquely 
to the metacarpal bones, along which they pass; and are finally inserted into the 
second and third phalanges of the fingers in the following manner. Each tendon 
opposite its correspondmg metacarpo-phalangeal articulation becomes narrow and 
thickened, being reinforced by the tendons of the, interossei and lumbricales, gives 
ofi" a thin fasciculus upon each side of the joint, and spreads out into a broad 
aponeurosis, which covers the whole of the dorsal surface of the first phalanx. 
Opposite the first phalangeal joint, this aponeurosis divides into three slips, a 
middle and two lateral; the former is inserted into the base of the second phalanx, 
and the two lateral, which are continued onwards along the sides of the second 
phalanx, unite by their contiguous margins, and are inserted into the upper sur- 
face of the last phalanx. The tendons of the middle, ring, and little fingers are 
connected together as they cross the hand by small oblique tendinous slips. The 
tendons of the index and little fingers also receive, before their division, the special 
extensor tendons belonging to them. 

Helations. By its superficial surface, with the fascia of the fore-arm and hand, 
the posterior annular ligament and integument. By its deep surface, with the 
Supinator brevis, the Extensor muscles of the thumb and index finger, posterior 
interosseous artery and nerve, the wrist-joint, carpus, metacarpus, and phalanges. 
By its radial border, with the Extensor carpi radialis brevior. By its ulnar bor- 
der, with the Extensor minimi digiti, and Extensor carpi ulnaris. 

The Extensor Mi?iimi Digiti is a small slender muscle, placed on the inner side 
of the Extensor communis, with which it is generally connected. It arises from 
the common tendon of origin of the Extensor muscles by a thin tendinous slip; 
and from the inter-muscular septa between it and the adjacent muscles. Passing 
down to the lower extremity of the ulna, its tendon runs through a separate 
sheath in the annular ligament, and at the metacarpo-phalangeal articulation 
unites with the tendon derived from the long Extensor. The common tendon 
then spreads into a broad aponeurosis, which is inserted into the second and third 
phalanges of the little finger in a similar manner to the common extensor tendons 
of the other fingers. 

The Extensor Carpi Ulnaris is the most superficial muscle on the ulnar side of 
the fore-ai-m. It arises by the common tendon from the external condyle of the 
humerus, from the middle third of the posterior border of the ulna below the An- 
coneus, and from the fascia of the fore-arm. This muscle teniiinates in a tendon, 
which runs through a groove behind the styloid process of the ulna, passes through 



POSTERIOR BRACHIAL REGION. 261 

a separate sheath in the annular ligament, and is inserted into the base of the 
metacarpal bone of the little finger. 

Relations. By its superficial surface, with the fascia of the fore-arm. By its 
deep surface, with the ulna, and the muscles of the deep layer. 

The Anconeus is a small triangular muscle, placed behind and beneath the 
elbow-joint, and appears to be a continuation of the external portion of the 
Triceps. It arises by a separate tendon from the back part of the outer condyle 
of the humerus; the fibres diverge from this origin, the upper ones being directed 
horizontally, the lower obliquely inwards, to be inserted into the triangular surface 
at the upper part of the j)osterior surface of the shaft of the ulna. 

Relations. By its superficial surface, with a strong fascia derived from the Tri- 
ceps. By its deep surface, with the elbow-joint, the orbicular ligament, the ulna, 
and a small portion of the Supinator brevis. 

Posterior Brachial Region. 
Deep Layer. 

Supinator Brevis. Extensor Primi Internodii Pollicis. 

Extensor Ossis Metacarpi Pollicis. Extensor Secundi Internodii Pollicis. 

Extensor Indicis. 

The Supinator Brevis is a broad muscle, of a hollow cylindrical form, curved 
around the upper third of the radius. It arises from the external condyle of the 
humerus, from the external lateral ligament of the elbow-joint, from the orbicular 
ligament of the radius, from the prominent oblique line of the ulna, extending 
down from the lower extremity of the lesser sigmoid cavity, and the triangular 
depression in front of it; it also arises from a tendinous expansion which covers 
its surface. The fibres of the muscle pass obliquely around the upper part of the 
radius; the most superior fibres forming a sling-like fasciculus, which passes around 
the neck of the radius above the tuberosity, to be attached to the back part of its 
Mnner surface; the middle fibres being attached to the outer edge of the bicipital 
Ituberosity; the lower fibres to the oblique line as low down as the insertion of the 
IPronator radii teres. This muscle is pierced by the posterior interosseous nerve. 
Relations. By its superficial surface, with the Pronator radii teres, all the su- 
perficial Extensor and Supinator muscles, the Anconeus, the radial vessels and 
lerve, and the musculo-sj)iral nerve. By its deep surface, with the elbow joint, 
the interosseous membrane, and the radius. 

The Extensor Ossis Metacarpi Pollicis is the most external and the largest 
^of the deep Extensor muscles, lying immediately below the Supinator brevis. 
[t arises from the posterior surface of the shaft of the ulna below the origin 
'of the Supinator brevis, from the interosseous ligament, and from the middle 
third of the posterior surface of the shaft of the radius. Passing obliquely down- 
wards and outwards, it terminates in a tendon which runs through a groove on the 
outer side of the styloid process of the radius, accompanied by the tendon of the 
Extensor primi internodii pollicis, and is inserted into the base of the metacarpal 
bone of the thumb. 

Relations. By its superficial surface, with the Extensor communis digitorum. 
Extensor minimi digiti, and fascia of the fore-arm; being crossed by the branches 
of the posterior interosseous artery and nerve. By its deep surface, with the 
ulna, interosseous membrane, radius, the tendons of the Extensor carpi radialis 
longior and brevior, and at the outer side of the wrist with the radial artery. By 
its upper border, with the Supinator brevis. By its lower border, with the Ex- 
tensor primi internodii pollicis. 

The Extensor Primi Internodii Pollicis is much smaller than the preceding 
muscle, on the inner side of which it lies. It arises from the posterior surface of 
the shaft of the radius, immediately below the Extensor ossis metacarpi, and 
from the interosseous membrane. Its direction is similar to that of the Exten- 
sor ossis metacarpi, its tendon passing through the same groove on the outer side 



262 



MUSCLES AND FASCIA. 



of the styloid process, to be inserted into the base of the first phalanx of the 
thumb. 

Relations. The same as those of the Extensor ossis metacarpi pollicis. 

The Extensor Secundi Internodii Pollicis is much larger than the preceding 

muscle, the origin of which 

158.— Posterior Surface of the Fore-arm. Deep Muscles. ^* P^^'^^J covers in. It arises 

from the posterior surface of 
the shaft of the ulna, below 
the origin of the Extensor 
ossis metacarpi pollicis, and 
from the interosseous mem- 
brane. It terminates in a 
tendon which passes through 
a distinct canal in the annu- 
lar ligament, lying in a nar- 
row oblique groove at the 
back part of the lower end of 
the radius. It then crosses 
obliquely the tendons of the 
Extensor carpi radialis lon- 
gior and brevier, being sepa- 
rated by a triangular interval 
from the other Extensor ten- 
dons of the thumb, in which 
space the radial artery is 
found; and is finally inserted 
into the base of the last 
phalanx of the thumb. 

Relations. By its super- 
ficial surface, with the same 
parts as the Extensor ossis 
metacarpi pollicis. By its 
deep surface, with the ulna, 
interosseus membrane, radius, 
the wrist, the radial artery, 
and metacarpal bone of the 
thumb. 

The Extensor Indicis is a 
narrow elongated muscle, 
placed on the inner side of, 
and parallel with, the pre- 
ceding. It arises from the 
posterior surface of the shaft 
of the ulna below the origin 
of the Extensor secundi inter- 
nodii pollicis, and from the 
interosseous membrane. Its 
tendon passes with the Ex- 
tensor communis digitorum 
through the same canal in the 
annular ligament, and subse- 
quently joins that tendon of 
the Extensor communis which 
belongs to the index finger, 
opposite the lower end of 
the corresponding metacarpal 
bone. It is finally inserted 




OF THE HAND. 263 

into the second and third phalanges of tlie index finger, in the manner already 
described. 

Relations. They are similar to those of the preceding muscles. 

Nerves. The Supinator longus, Extensor carpi radialis longior, and Anconeus, 
are supplied by branches from the musculo-spiral nerve. The remaining muscles 
of the radial and posterior brachial regions, by the posterior interosseous nerve. 

Actions. The muscles of the radial and jjosterior brachial regions, which com- 
prise all the Extensor and Supinator muscles, act upon the fore-arm, w^rist and 
hand; they are the direct antagonists of the Pronator and Flexor muscles. The 
Anconeus assists the Triceps in extending the fore-arm. The Supinator longus 
and brevis are the supinators of the fore-arm and hand; the former muscle more 
especially acting as a supinator when the limb is pronated. When supination has 
been produced, the Supinator longus, if still continuing to act, Ilexes the fore-arm. 
The Extensor carpi radialis longior and brevier, and Extensor carpi ulnaris 
muscles, are the Extensors of the wrist; continuing their action, they serve to 
extend the fore-arm upon the arm; they are the direct antagonists of the Flexor carpi 
radialis and ulnaris. The common Extensor of the fingers, the Extensors of the 
thumb, and the Extensors of the index and little fingers, serve to extend the pha- 
langes into which they are inserted; and are the direct antagonists of the Flexors. 
By continuing their action they assist in extending the fore-arm. The Extensors 
of the thumb may assist in supinating the fore-arm, when this part of the hand 
has been drawn inwards towards the palm, on account of the oblique direction of 
the tendons of these muscles. 

Muscles and Fasciae of the Hand. 

Dissection (fig.i 30). Make a transverse incision across the front of the wrist, and a second 
across the heads of the metacarpal bones, connect the two by a vertical incision in the 
middle line, and continue it through the centre of the middle finger. The anterior and 
posterior annular ligaments, and the palmar fascia, should first be dissected. 

The Anterior Annular Ligament is a strong fibrous band, which arches over 
the front of the carpus, converting the deep groove on the front of these bones 
into a canal, beneath which the tendons of the muscles of the fore-arm pass, pre- 
vious to their insertion into the fingers. This ligament is attached, internally, to 
the pisiform bone, and unciform process of the unciform; and externally, to the 
tuberosity of the scaphoid, and ridge on the trapezium. It is continuous, above, 
with the deep fascia of the fore-arm, and below, with the palmar fascia. It is 
crossed by the tendon of the Palmaris longus, by the ulnar artery and nerve, and 
the cutaneous branch of the median nerve. It has inserted into its upper and 
inner part, the tendon of the Flexor carpi ulnaris; and has, arising from it below, 
the small muscles of the thumb and little finger. It is pierced by the tendon of 
the Flexor carpi radialis; and, beneath it, pass the tendons of the Flexor sublimis 
and profundus digitorum, the Flexor longus pollicis, and the median nerve. 
There are two synovial membranes beneath this ligament; one of large size, en- 
closing the tendons of the Flexor sublimis and profundus; and a separate one 
for the tendon of the Flexor longus pollicis; the latter is also lai'ge and very ex- 
tensive, reaching from above the wrist to the extremity of the last phalanx of the 
thumb. 

The Posterior Annular Ligament is a strong transverse fibrous band, extending 
across the back of the wrist, and continuous with the fascia of the fore-arm. It 
forms a sheath for the extensor tendons in their passage to the fingers, being 
attached, internally, to the cuneiform and pisiform bones, and palmar fascia; ex- 
ternally, to the margin of the radius; and in its passage across the wrist, to the 
elevated ridges on the posterior surface of the radius. It presents six 
compartments for the passage of tendons, each of which is lined by a separate 
synovial sac. These are, from within outwards, I. A sheath on the outer side of 
the radius for the tendons of the Extensor ossis metacarpi, and Extensor 
primi internodii pollicis. 2. Behind the styloid process, for the tendons 



264 MUSCLES AND FASCIiE. 

of the Extensor carpi radialis longior and brevior. 3. Opposite the middle of the 
posterior surface of the radius, for the tendon of the Extensor secundi internodii 
pollicis. 4. For the tendons of the Extensor communis digitorum, and Extensor 
indicis. 5. For the Extensor minimi digiti. 6. For the tendon of the Extensor 
carpi ulnaris. The synovial membranes lining these sheaths are usually very ex- 
tensive, extending from above the annular ligament, dow^n upon the tendons, al- 
most to their insertion. 

The Palmar Fascia foi'ms a common sheath w^hich invests the muscles of the 
hand. It consists of three portions, a central and tvi^o lateral. The central por- 
tion occupies the middle of the palm, is triangular in shape, of great strength and 
thickness, and binds down the tendons in this situation. It is narrow above, being- 
attached to the lower margin of the annular ligament, and receives the expanded 
tendon of the Palmaris longus muscle. Below, it is broad and expanded, and op- 
posite the heads of the metacarpal bones divides into four slips, for the four fingers. 
Each slip subdivides into two processes which enclose the tendons of the Flexor 
muscles, and are attached to the sides of the first phalanx, and to the anterior or 
glenoid ligament; by this arrangement, four arches are formed, under which the 
Flexor tendons pass. The arched intervals left in the fascia between these four 
fibrous slips, transmit the digital vessels and nerves, and the tendons of the Lum- 
bricales. At the point of division of the palmar fascia into the slips above men- 
tioned, numerous strong transverse fibres bind the separate processes together. 
This fascia is intimately adherent to the integument by numerous fibrous bands, 
and gives origin by its inner margin to the Palmaris brevis; it covers the superficial 
palmar arch, the tendons of the fiexor muscles, and the branches of the median 
and ulnar nerves; and on each side it gives ofi" a vertical septum, which is con- 
tinuous with the interosseous aponeurosis, and s&parates the lateral from the middle 
palmar region. 

The Lateral portions of the palmar fascia are very thin fibrous layers, which 
cover, on the radial side, the muscles of the ball of the thumb; and on the ulnar 
side, the muscles of the little finger; they are continuous with the dorsal fascia, 
and in the palm, with the middle j)ortion of the palmar fascia. 

Muscles of the Hand. 

The muscles of the hand are subdivided into three groups. I. Those of the 
thumb, which occupy the radial side. 2. Those of the little finger, which occupy 
the ulnar side. 3. Those in the middle of the palm and between the interosseous 
spaces. 

Radial Group. 
Muscles of the Thumb. 
Abductor Pollicis. 

Opponens Pollicis (Flexor Ossis Metacarpi). 
Flexor Brevis Pollicis. 
Adductor Pollicis. 

The Abductor Pollicis is a thin, flat, narrow muscle, placed immediately be- 
neath the integument. It arises from the ridge of the os trapezium and annular 
ligament; and passing outwards and downwards, is inserted by a thin flat tendon 
into the radial side of the base of the first phalanx of the thumb. 

Relations. By its superficial surface, with the palmar fascia. By its deep sur- 
face, with the Opponens pollicis, from which it is separated by a thin aponeurosis. 
Its inner border, is separated from the Flexor brevis pollicis by a narrow cellular 
interval. 

The Opponens Pollicis {Flexor Ossis Metacarpi) is a small triangular muscle, 
placed beneath the preceding. It arises from the palmar surface of the trapezium 
and annular ligament; the fleshy fibres pass downwards and outwards, to be inserted 
into the whole length of the metacarjDal bone of the thumb on its radial side. 

Relations. By its superficial surface, with the Abductor pollicis. By its deep 



OF THE HAND. 



265 



surface, with the trapezio-metacarpal articulation. By its inner border, with the 
Flexor brevis pollicis. 

The Flexor Brevis Pollicis is much larger than either of the two preceding 
muscles, beneath which it is placed. It consists of two distinct portions, in the 
interval between which lies the tendon of the Flexor longus pollicis. The ante- 
rior and more superficial portion arises from the trapezium and outer two-thirds of 
the annular ligament. The deeper portion from the trapezoides, os magnum, base 

159. — Muscles of the Left Hand. Palmar Surface. 




of the third metacarpal bone, and sheath of the tendon of the Flexor carpi radialis. 
The fleshy fibres unite to form a single muscle; this divides into two tendons, 



266 MUSCLES AND FASCIA. 

which are inserted one on either side of the base of the first phalanx of the thumb. 
A sesamoid bone is developed in each of these tendons as they pass across the me- 
tacarpo-phalangeal joint; the outer one being joined by the tendon of the Abduc- 
tor, and the inner, by that of the Adductor. 

Relations. By its superficial surface, with the palmar fascia. By its deep 
surface, with the Adductor pollicis, and tendon of the Flexor carpi radialis. 
By its external surface, with the Opponens pollicis. By its internal surface, with 
the tendon of the Flexor longus pollicis. 

The Adductor Pollicis (fig. 156), is the most deeply seated, and the largest of this 
group of muscles. It is of a triangular form, arising, by its broad base, from the 
whole length of the metacarpal bone of the middle finger on its palmar surface : the 
fibres, proceeding outwards, converge, to be inserted by a short tendon into 
the ulnar side of the base of the first phalanx of the thumb, and into the internal 
sesamoid bone, being blended with the innermost tendon of the Flexor brevis 
pollicis. 

Relations. By its superficial surface, with the Flexor brevis pollicis, the 
tendons of the Flexor profundus digitorum and Lumbricales. Its deep surface, 
covers the two first interosseous spaces, from which it is separated by a strong 
aponeurosis. 

Nerves. The Abductor, Opponens, and outer head of the Flexor brevis pollicis, 
are supplied by the median nerve ; the inner head of the Flexor brevis, and the 
Adductor pollicis, by the ulnar nerve. 

Actions. The actions of the muscles of the thumb are almost sufiS.ciently indi- 
cated by their names. This segment of the hand is provided with three Extensors, 
an Extensor of the metacarpal bone, an Extensor of the first, and an Extensor of 
the second phalanx ; these occupy the dorsal sm'face of the fore-arm and hand. 
There are, also, three Flexors on the palmar surface, a Flexor of the metacarpal 
bone, the Flexor ossis metacarpi (Opponens pollicis), the Flexor brevis pollicis, 
and the Flexor longus pollicis ; there is also an Abductor and an Adductor. 
These muscles give to the thumb that extensive range of motion which it pos- 
sesses in an eminent degree. 

Ulnar Region. 
Muscles of the Little Finger. 

Palmaris Brevis. Flexor Brevis Minimi Digiti. 

Abductor Minimi Digiti. Opponens Minimi Digiti. 

The Palmaris Brevis, is a thin quadrilateral plane of muscular fibres, placed 
immediately beneath the integument on the ulnar side of the hand. It arises 
by tendinous fasciculi, from the annular ligament and palmar fascia ; the fleshy 
fibres pass horizontally inwards, to be inserted into the skin on the inner border 
of the palm of the hand. 

Relations. By its superficial surface, with the integument to which it is inti- 
mately adherent, especially by its inner extremity. By its deep surface, with 
the inner portion of the palmar fascia, which separates it from the ulnar artery 
and nerve, and from the muscles of the ulnar side of the hand. 

The Abductor Minimi Digiti is situated on the ulnar border of the palm of the 
hand. It arises by tendinous fibres from the pisiform bone, and from an expan- 
sion of the tendon of the Flexor carpi ulnaris. The muscle terminates in a 
flat tendon, which is inserted into the base of the first phalanx of the little finger, 
on its ulnar side. 

Relations. By its superficial surface, with the inner portion of the palmar 
fascia, and the Palmaris brevis. By its deep surface, with the Flexor ossis meta- 
carpi. By its inner border, with the Flexor brevis minimi digiti. 

The Flexor Brevis Minimi Digiti lies on the same plane as the preceding 
muscle, on its radial side. It arises from the unciform process of the uncifoi'm 



OF THE HAND. 



267 



boue, and anterior surface of the annular ligament, and is inserted into the base 
of the first phalanx of the little finger, in connection with the preceding. It 
is separated from the Abductor at its origin, by the communicating branch 
of the ulnar artery, and deep palmar branch of the ulnar nerve. This muscle is 
sometimes wanting. The Abductor is then, usually, of large size. 

Relations. By its superficial surface, with the internal portion of the palmar 
fascia, and the Palmaris brevis. By its deep surface, with the Flexor ossis me- 
tacarpi. 

The Opponens Minimi Digiti (fig. 1 5 6), is of a triangular form, and placed im- 
mediately beneath the preceding muscles. It arises from the unciform process 
of the unciform bone, and contiguous portion of the annular ligament ; from 
these points, the fibres pass downwards and inwards, to be inserted into the 
whole length of the metacarpal bone of the little finger, along its ulnar margin. 

Relations. By its superficial surface, with the Flexor brevis, and Abductor 
minimi digiti. By its deep surface, with the interossei muscles in the fifth 
metacarpal space, the metacarpal bone, and the Flexor tendons of the little 
finger. 

Nerves. All the muscles of this group are supplied by the ulnar nerve. 

Actions. The actions of the muscles of the little finger are expressed in their 
names. The Palmaris brevis corrugates the skin on the inner side of the 
palm of the hand. 

Middle Palmar Eegion. 

Lumbricales. Interossei Palmares. 

Interossei Dorsales. 



The Lumbricales are four small fleshy fasciculi, accessories to the deep Flexor 
muscle. They arise by fleshy fibres from the tendons of the deep Flexor, the 
first and second, from the radial side and palmar surface of the tendons of the index 
and middle fingers, the third, from the contiguous sides of the tendons of the 
middle and ring fingers, and the fourth, from the contiguous sides of the tendons 
of the ring and little fingers. They pass forwards to the radial side of the cor- 
responding fingers, and opposite the Metacarpo-phalangeal articulations, each 
tendon terminates in a broad aponeurosis, 160. — The Dorsal Interossei of Left Hand, 
which is inserted into the tendinous ex- 
pansion from the Extensor communis di- 
gitorum, which covers the dorsal aspect 
of each finger. 

The Interossei Muscles are so named 
from their occupying the intervals be- 
tween the metacarpal bones. They are 
divided into two sets, a dorsal and pal- 
mar, the former are four in number, one 
in each metacarpal space, the latter, 
three in number, lie upon the metacarpal 
bones. 

The Dorsal Interossei are four in 
number, larger than the palmar, and 
occupy the intervals between the meta- 
carpal bones. They are bipenniform 
muscles, arising by two heads from the 
adjacent sides of the metacarpal bones, 
but more extensively from that side of 
the metacarpal bone, which corresponds 
to the side of the finger in which the 
muscle is inserted. They are inserted 




268 



SURGICAL ANATOMY. 



into the base of the first phalanges, and mto the aponeurosis of the common 
Extensor tendon. Between the double origin .of each of these muscles is a 
narrow triangular interval, through which passes a perforating branch from the 
deep palmar arch. 

The First Dorsal Interosseous muscle or Abductor indicis, is larger than the 
others, and lies in the interval between the thumb and index finger. It is flat, 
triangular in form, and arises by two heads, separated by a fibrous arch, for the 
passage of the radial artery into the deep part of the palm of the hand. The 
outer head arises from the upper half of the ulnar border of the first metacarpal 
bone, the inner head, from the entire length of the radial border of the second 
metacarpal bone, the tendon is inserted into the radial side of the index finger. 
The second and third are inserted into the middle finger, the former into its 
radial, the latter into its ulnar side. The fourth is inserted in the radial side 
of the ring finger. 

The Palmar Interossei, three in number, are smaller than the Dorsal, and placed 
i6i.— The Palmar Interossei of Left "^V^^ ^^^ palmar surface of the metacarpal 
Hand. bones, rather than between them. They 

arise from the entire length of the meta- 
carpal bone of one finger, and are inserted 
into the side of the base of the first pha- 
lanx and aponeurotic expansion of the 
common Extensor tendon of the same finger. 
The first arises from the ulnar side of 
the second metacarpal bone, and is inserted 
into the same side of the index finger. The 
second arises from the radial side of the 
fourth metacarpal bone, and is inserted into 
the same side of the ring finger. The third 
arises from the radial side of the fifth me- 
tacarpal bone, and is inserted into the same 
side of the little finger. From this account 
it may be seen, that each finger is provided 
with two Interossei muscles, with the excep- 
tion of the little finger. 

Nerves. The two outer Lumbricales are 
supplied by the median nerve; the rest of 
the muscles of this group by the ulnar. 

Actions. The Dorsal interossei muscles 
abduct the fingers from an imaginary line 
drawn longitudmally through the centre of the middle finger, and the Palmar 
interossei adduct the fingers towards the same line. They usually assist the 
Extensor muscles, but when the fingers are slightly bent, assist in flexing the 
fingers. 

SURGICAL ANATOMY. 

The Student having completed the dissection of the muscles of the upper ex- 
tremity, should consider the efifects likely to "be produced by the action of the 
various muscles in fracture of the bones ; the causes of displacement are thus 
easily recognised, and a suitable treatment in each case may be readily adopted. 

In considering the actions of the various muscles upon fractures of the upper 
extremity, the most common forms of injury have been selected, both for illus- 
tration and description. 

Fracture of the clavicle is an exceedingly common accident, and is usually caused 
by indirect violence, as a fall upon the shoulder; it occasionally, however, occurs 
from direct force. Its most usual situation is just external to the centre of the 
bone, but it may occur at the sternal or acromial ends. 

Fracture of the middle of the clavicle (fig. 162) is always attended with con- 




Of the muscles of the upper extremity. 



269 




siderable displacement, the outer fragment being drawn downwards, forwards, and 
inwards; the inner fragment slightly upwards. The outer fragment is drawn down 
by the weight of the arm and the action of 

the Deltoid, and forwards and inwards by 162.— Fracture of the Middle of the 
the Pectoralis minor and Subclavius muscles ; Clavicle. 

the inner fragment is slightly raised by the 
Sterno-cleido mastoid, but only to a very 
limited extent, as the attachment of the 
costo-clavicular ligament and Pectoralis 
major below and in front would prevent any 
very great displacement upwards. The 
causes of displacement having been ascer- 
tained, it is easy to apply the appropriate 
treatment. The outer fragment is to be 
drawn outwards, and, together with the 
scapula, raised upwards to a level with the 
inner fragment, and retained in that posi- 
tion. 

In fracture of the acromial end of the 
clavicle between the conoid and trapezoid 
ligaments, only slight displacement occurs, 
as these ligaments, from their oblique inser- 
tion, serve to hold both portions of the bone 
in apposition. Fracture, also, of the sternal 
end, internal to the costo-clavicular ligament, 
is attended with only slight displacement, 
this ligament serving to retain the fragments 
in close apposition. 

Fracture of the acromion process usually arises from violence applied to the 
upper and outer part of the shoulder: it is generally known by the rotundity of 
the shoulder being lost, from the Deltoid drawing downwards and forwards the 
fractured portion; and the displacement may easily be discovered by tracing the 
mai'gin of the clavicle outwards, when the fragment will be found resting on 
the front and upper part of the head of the humerus. In order to relax the 
anterior and outer fibres of the Deltoid (the opposing muscle), the arm should 
be drawn forwards across the chest, and the elbow well raised up, so that 
the head of the bone may press upwards the acromion process, and retain it in its 
position. 

Fracture of the coracoid process is an extremely rare accident, and is usually 
caused by a sharp blow directly on its pointed extremity. Displacement is here 
produced by the combined actions of the Pectoralis minor, short head of the 
Biceps, and Coraco-brachialis, the former muscle drawing the fragment inwards, 
the latter directly downwards, the amount of displacement being limited by the 
connection of this process to the acromion by means of the coraco-acromion liga- 
ment. In order to relax these muscles, and replace the fragments in close appo- 
sition, the fore-arm should be flexed so as to relax the Biceps, and the arm drawn 
forwards and inwards across the chest so as to relax the Coraco-brachialis; the 
action of the Pectoralis minor may be counteracted by placing a pad in the axilla; 
the humerus should then be pushed upwards against the coraco-acromial ligament, 
and the arm retained in this position. 

Fracture of the anatomical neck of the humerus within the capsular ligament 
is a rare accident, attended with very slight displacement, an impaired condition of 
the motions of the joint, and crepitus. 

Fracture of the surgical neck (fig. 163) is very common, is attended with con- 
siderable displacement, and its appearances correspond somewhat with those of 
dislocation of the head of the humerus into the axilla. - The upper fragment is 
slightly elevated under the coraco-acromion ligament by the muscles attached to 



270 



SURGICAL ANATOMY. 



163. — Fracture of the Surgical Neck 
of the Humerus. 




the greater and lesser tuberosities; the upper end of the lower ligament is drawn 
inwards by the Pectoralis major, Latissimus dorsi, and Teres major; and the 

humerus is thrown obliquely outwards from 
the side by the action of the Deltoid, and 
occasionally elevated so as to project beneath 
and in front of the coracoid process. By 
fixing the shoulder, and drawing the arm 
outwards and downwards, the existing de- 
formity is at once reduced. To counteract 
the action of the opposing muscles, and to 
keep the fragments in position, the arm 
should be drawn from the side, and paste- 
board splints' applied on its four sides, a 
large conical-shaped pad should be placed 
in the axilla with the base turned upwards, 
and the elbow approximated to the side, and 
retained there by a broad roller passed 
around the chest; by these means, the action 
of the Pectoralis major, Latissimus dorsi. 
Teres major, and Deltoid muscles are coun- 
teracted: the fore-arm should then be flexed, 
and the liand supported in a sling, care 
being taken not to raise the elbow, otherwise the lower fragment may be displaced 
upwards. 

Li fracture of the shaft of the humerus below the insertion of the Pectoralis 
major, Latissimus dorsi, and Teres major, and abeve the insertion of the Deltoid, 
there is also considerable deformity, the lower end of the upper fragment being 
drawn inwards by the first mentioned muscles, and the lower fragment drawn up- 
wards and outwards by the Deltoid, producing shortening of the limb, and a con- 
siderable prominence at the seat of fracture, from the fractured ends of the bone 
riding over one another, especially if the fracture takes place in an oblique direc- 
tion. The fragments may be readily brought into apposition by extension from 
the elbow, and retained in that position by adopting the same means as in the 
preceding injury. 

Li fracture of the shaft of the humerus immediately below the insertion of the 
Deltoid, the amount of deformity depends greatly upon the direction of the fracture. 
If the fracture occurs in a transverse direction, only slight displacement occurs, 
the lower extremity of the upper fragment being drawn a little forwards: but in 
oblique fracture, the combined actions of the Biceps and Brachialis anticus muscles 
in front, and the Triceps behind, draw upwards the lower fragment, causing it to 
glide over the lower end of the upper fragment, either backwards or forwards, 
according to the direction of the fracture. Simple extension reduces the defor- 
mity, and the application of splints on the four sides of the arm retain the frag- 
ments in apposition. Care should be taken not to raise the elbow, but the fore-arm 
and hand may be supported in a sling. 

Fracture of the humerus (fig. 164) immediately above the condyles deserves very 
attentive consideration, as the general appearances correspond somewhat with 
those produced by separation of the epiphysis of the humerus, and with those of 
dislocation of the radius and ulna backwards. If the direction of the fracture 
is oblique from above, downwards and outwards, the lower fragment is drawn 
upwards and backwards by the Brachialis anticus and Biceps in front, and the 
Triceps behind. This injury may be diagnosed from dislocation by the increased 
mobility in fracture, the existence of crepitus, and the deformity being remedied 
by extension, by the discontinuance of which it is again reproduced. The age of 
the patient is of importance in distinguishing this form of injury from separation 
of the epiphysis. If fracture occurs in the opposite direction to that shewn in 
the plate, the lo'-ver fragment is drawn upwards and forwards, causing a con- 



OF THE MUSCLES OF THE UPPER EXTREMITY. 



271 



siderable prominence in fi'ont, and the lower end of the upper fragment projects 

backwards beneath the tendon of the Triceps muscle. 

Fracture of the coronoid process of the . t^ , o ,-, tt ■, 

'■ '' \ 64. — Jj racture of the Humerus above 



the Condyles. 




\ 



ulna is an accident of rai-e occurrence, and 

is usually caused by violent action of the 

Brachialis anticus muscle. The amount of 

displacement varies according to the extent 

of the fracture. If the tip of the process 

only is broken off, the fragment is drawn 

upwards by the Brachialis anticus on a level 

with the coronoid depression of the humerus, 

and the power of flexion is partially lost. If 

the process is broken off near its root, the 

fragment is still displaced by the same 

muscle; at the same time, on extending the 

fore-arm, partial dislocation backwards of the 

ulna occurs from the action of the Triceps 

muscle. The appropriate treatment would 

be to relax the Brachialis anticus by flexing 

the fore-arm, and to retain the fragments in 

immediate apposition by keeping the arm in 

this position. Union is generally liga- 
mentous. 

Fracture of the olecranon process (fig. 165) is a more frequent accident, and is 

caused either by violent action of the Triceps muscle, or by a fall or blow upon the 

point of the elbow. The detached fragment is displaced upwards, by the action of 

the Triceps muscle, from half an inch 

to two inches; the prominence of the 165.— Fracture of the Olecranon. 

elbow is consequently lost, and a deep 

hollow is felt at the back part of the 

joint, which is much increased on 

flexing the limb. The patient at the 
same time loses the power of extend- 
ing the fore-arm. The treatment con- 
sists in relaxing the Triceps by ex- 
tending the fore-arm, and retaining it 
in this position by means of a long 
straight splint applied to the front of 
the arm; the fragments are thus 
brought into closer apposition, and 
may be further approximated by draw- 
ing down the upper fragment. Union 
is generally ligamentous. 

Fracture of the neck of the radius 
is an exceedingly rare accident, and is generally caused by direct violence. Its 
diagnosis is somewhat obscure, on account of the slight deformity visible from the 
large number of muscles which surround it; but the movements of pronation and 
supination are entirely lost. The upper fragment is drawn outwards by the Supi- 
nator brevis, its extent of displacement being limited by the attachment of the 
orbicular ligament. The lower fragment is drawn forwards and slightly upwards 
by the Biceps, and inwards by the Pronator radii teres, its displacement forwards 
and, upwards being counteracted in some degree by the Supinator brevis. The 
treatment essentially consists in relaxing the Biceps, Supinator brevis, and Pro- 
nator radii teres muscles; by flexing the fore-arm, and placing it in a position 
midway between pronation and supination, extension having been previously made 
so as to bring the parts in apposition. 

Fracture of the radius (fig. 166) is more common than fracture of the ulna, on 




272 



SURGICAL ANATOMY, 



166. — Fracture of the Shaft of the Eadius. 




account of the connection of the former with the wrist. Fracture of the shaft of 
the radius near its centre may occur from direct violence, but more frequently 
from a fall forwards, the entire weight of the body being received on the wrist 

and hand. The upper fragment is 
drawn upwards by the Biceps, and 
inwards by the Pronator radii teres, 
holding a position midway between 
pronation and supination, and a de- 
gree of fulness in the upper half of 
the fore-arm is thus produced; the 
lower fragment is drawn downwards 
and inwards towards the ulna by the 
Pronator quadratus, and thrown into 
a state of pronation by the same 
muscle; at the same time, the Supinator longus, by elevating the styloid process, 
into which it is inserted, will serve to depress still more the upper end of the 
lower fragment towards the ulna. In order to relax the opposing muscles the 
fore-arm should be bent, and the limb placed in a position midway between pro- 
nation and stipination; the fracture is then easily reduced by extension from the 
wrist and elbow: well padded splints should then be applied on both sides of the 
fore-arm from the elbow to the wrist; the hand being allowed to fall, will, by its 
own weight, counteract the action of the Pronator quadratus and Supinator longus, 
and elevate this fragment to the level of the upper one. 

Fracture of the shaft of the ulna is not a common accident; it is usually caused 
by direct violence. Its more protected position on the inner side of the limb, the 
greater strength of its shaft, and its indirect coi^nection with the wrist, render it 
less liable to injury than the radius. It usually occurs a littl^^ below the centre, 
which is the weakest part of the bone. The upper fragment retains its usual 
position; but the lower fragment is drawn outwards towards the radius by the 
Pronator quadratus, producing a well marked depression at the seat of fracture, 
and some fulness on the dorsal and palmar surfaces of the fore-arm. The fracture 
is easily reduced by extension from the wrist and fore-arm. The fore-arm should 
be flexed, and placed in a position midway between pronation and supination, and 
well padded splints applied from the elbow to the ends of the fingers. 

Fracture of the shafts of the radius and ulna together is not a common acci- 
dent; it may arise from a direct blow, or from indirect violence. The lower 
fragments are drawn upwards, sometimes forwards, sometimes backwards, according 
to the direction of the fracture, by the combined actions of the Flexor and Ex- 
tensor muscles, producing a degree of fulness on the dorsal or palmar surface of 
the fore-arm; at the same time the two fragments are drawn into contact by the 
Pronator quadratus, the radius in a state of pronation : the upper fragment of the 
radius is drawn upwards and inwards by the Biceps and Pronator radii teres to a 
higher level than the ulna; the upper portion of the ulna is slightly elevated by 
the Brachialis anticus. The fracture may be reduced by extension from the wrist 
and elbow, and the fore-arm should be placed in the same position as in fracture of 
the ulna. 

In the treatment of all cases of fracture of the bones of the fore-arm, the greatest 
care is requisite to prevent the ends of the bones from being drawn inwards 
towards the interosseous space: if this is not carefully attended to, the radius and 
ulna may become anchylosed, and the movements of pronation and supination 
entirely lost. To obviate this, the splints applied to the limb should be well 
padded, so as to press the muscles down into their normal situation in the inter- 
osseous space, and so prevent the approximation of the fragments. 

Fracture of the lower end of the radius (fig. 167) is usually called Colles frac- 
ture, from the name of the eminent Dublin surgeon who first accurately described 
it. It usually arises from the patient falling from a height, and alighting upon 
the hand, which receives the entire weight of the body. This fracture usually 



OF THE MUSCLES OF THE UPPER EXTREMITY. 



273 



takes place from half an inch to an inch above the articular surface if it occurs in 
the adult; but in the child, before the age of sixteen, it is more frequently a sepa- 
ration of the epiphysis 'from the apophysis. The displacement which is produced 
is very considerable, and bears some resemblance to dislocation of the carpus back- 
wards, from which it should be carefully distinguished. The lower fragment is 
drawn upwards and backwards behind the upper fragment by the combined actions 

167. — Fracture of the Lower End of the Eadius. 




of the Supinator longus and the flexors and extensors of the thumb and carpus, 
producing a well marked prominence on the back of the wrist, with a deep de- 
pression behind. The upper fragment projects forwards, often lacerating the 
substance of the Pronator quadratus, and is draAvn by this muscle into close con- 
tact with the lower end of the ulna, causing a projection on the anterior surface 
of the fore-arm, immediately above the carpus, from the flexor tendons being 
thrust forwards. This fracture may be distinguished from dislocation by the 
deformity being removed on making sufiicient extension, when crepitus may be 
occasionally detected; at the same time, on extension being discontinued, the parts 
immediately resume their deformed appearance. The age of the patient will also 
assist in determining whether the injury is fracture or separation of the epiphysis. 
The treatment consists in flexing the fore-arm, and making powerful extension 
from the wrist and elbow, depressing at the same time the radial side of the hand, 
and retaining the parts in this position by Avell ])added pistol-shaped splints. 



MUSCLES AND FASCIA OF THE LOWER EXTREMITY. 

The Muscles of the Lower Extremity are subdivided into groups, corresponding 
with the different regions of the limb. 



Iliac Region. 
Psoas magnus. 
Psoas parvus. 
Iliacus. 

Thigh. 
Anterior Femoral Region. 
Tensor vaginae femoris. 
Sartorius. 
Rectus. 

Vastus externus. 
Vastus internus. 
Crurseus. 
Subcrurseus. 

Internal Femoral Region. 

Gracilis. 



Pectineus. 
Adductor longus. 
Adductor brevis. 
Adductor magnus. 

Hip. 

Gluteal Region. 
Gluteus maximus. 
Gluteus medius. 
Gluteus minimus. 
Pyriformis. 
Gemellus superior. 
Obturator internus. 
Gemellus inferior. 
Obturator externus. 
Quadratus femoris. 



274 



MUSCLES AND FASCIAE. 



Posterior Femoral Region. 

Biceps. 

Semi-tendinosus. 

Semi-membranosus. 

Leg. 
Anterior Tibio-fihidar Region. 
Tibialis anticus. 
Extensor longus digitorum. 
Extensor proprius pollicis. 
Peroneus tertius. 

Posterior Tihio-fihular Region. 
Superficial Layer. 
Gastrocnemius. 
Plantaris. 
Soleus. 

Deep Layer. 
Popliteus. 

Flexor longus pollicis. 
Flexor longus digitorum. 
Tibialis posticus. 



Fibular Region. 
Peroneus longus. 
Peroneus brevis. 

Foot. 
Dorsal Region. 
Extensor brevis digitorum. 
Literossei dorsales. 

Plantar Region. 
First Layer. 

Abductor pollicis. 
Flexor brevis digitorum. 
Abductor minimi digiti. 

Second Layer. 
Musculus accessorius. 
Lumbricales. 

Third Layer. 
Flexor brevis pollicis. 
Adductor pollicis. 
Flexor brevis minimi digiti. 
Transversus pedis. 

Fourth Layer. 
Interossei plantares. 



Psoas Ma2:nus. 



Iliac Region., 
Psoas Parvus. 



Iliac VIS. 



Dissection. No detailed description is required for tlie dissection of these muscles. 
They are exposed after the removal of the viscera from the abdomen, covered by the Peri- 
toneum and a thin layer of fascia, the fascia iliaca. 

The Iliac fascia is the aponeurotic layerwhich lines the back partof the abdominal 
cavity, and encloses the Psoas and Iliacus muscles throughout their whole extent. It 
is thin above, and becomes gradually thicker below, as it approaches the femoral 
arch. 

The portion investing the Psoas, is attached, above, to the ligamentum arcuatum 
internum; internally, to the sacrum; and by a series of arched processes to the 
inter- vertebral substances, and prominent margins of the bodies of the vertebrae; 
the intervals left opposite the constricted portions of the bodies, transmitting the 
lumbar arteries and sympathetic filaments of nerves. Externally, it is continuous 
with the fascia lumborum. 

The portion investing the iliacus is connected, externally, to the whole length 
of the inner border of the crest of the ilium. Internally, to the brim of the true 
pelvis, where it is continuous with the periosteum, and receives the tendon of 
insertion of the Psoas parvus. External to the femoral vessels, this fascia is 
intimately connected with Poupart's ligament, and is continuous with the fascia 
transversalis; but corresponding to the point where the femoral vessels pass down 
into the thigh, it is prolonged down behind them, forming the posterior wall of the 
femoral sheath. Below this point, the iliac fascia surrounds the Psoas and Iliacus 
muscles to their termination, and becomes continuous with the iliac portion of the 
fascia lata. Internal to the femoral vessels the iliac fascia is connected to the ilio- 
pectineal line, and is continuous with the pubic portion of the fascia lata. The 
iliac vessels lie in front of the iliac fascia, but all the branches of the lumbar 
plexus, behind it; it is separated from the peritoneum by a quantity of loose areolar 
tissue. In abcesses accompanying caries of the lower part of the spine, the matter 
makes its way to the femoral arch, distending the sheath of the Psoas; and when 
it accumulates in considerable quantity, this muscle becomes absorbed, and the 



I 



ILIAC REGION. 



275 



nervous cords contained in it are dissected out, and lie exposed in the cavity of 
the abscess; tlie femoral vessels, however, remain intact, and the peritoneum seldom 
becomes implicated notwithstanding the extreme thinness of this membrane. 

Eemove this fascia, and the muscles of the iliac region will be exposed. 

The Psoas Magnus is a long fusiform muscle, placed on the side of the lumbar 
region of the spine (fig. 169) and margin of the pelvis. It arises from the sides of 
the bodies, from the corresponding inter- vertebral substances, and from the anterior 
part of the bases of the transverse processes of the last dorsal and all the lumbar 
vertebrae. The muscle is connected to the bodies of the vertebrae by five slips, each 
of which is attached to the upper and lower margins of two vertebrse, and to the 
inter- vertebral substance between them; the slips themselves being connected by 
tendinous arches extending across the constricted part of the bodies, beneath which 
pass the lumbar arteries and sympathetic nervous filaments. These tendinous 
arches also give origin to muscular fibres and protect the blood-vessels and nerves 
from pressure during the action of the muscle. The first slip is attached to the 
contiguous margins of the last dorsal and first lumbar vertebree; the last, to the 
contiguous margins of the fourth and fifth lumbar, and inter- vertebral substance. 
From these points, the muscle passes down across the brim of the pelvis, and dimi- 
nishing gradually in size, passes beneath Poupart's ligament, and terminates in a 
tendon, which after receiving the fibres of the Iliacus, is inserted into the lesser 
trochanter of the femur. 

Relations. In the lumbar region. By its anterior surface, which is placed 
behind the Peritoneum, with the ligamentum arcuatum internum, the kidney, Psoas 
parvus, renal vessels, ureter, spermatic vessels, genito-crural nerve, the colon, and 
along its pelvic border, with the common and external iliac artery and vein. By 
its posterior surface, with the transverse processes of the lumbar vertebrge and the 
quadratus lumborum, from which it is separated by the anterior lamella of the apo- 
neurosis of the Transversalis ; the anterior crural nerve is at first situated in the 
substance of the muscle, and emerges from its outer border at its lower part. The 
lumbar plexus is situated in the posterior part of the substance of the muscle. 
By its inner side, with the bodies of the lumbar vertebrae, the lumbar arteries, the 
sympathetic ganglia, and its communicating branches with the spinal nerves. In 
the thigh it is in relation, in front, with the fascia lata; behind, with the capsular 
ligament of the hip, from which it is separated by a synovial bursa, which some- 
times communicates with the cavity of the joint through an opening of variable 
size. By its inner border, with the Pectineus and the femoral artery, which 
slightly overlaps it. By its outer border, with the crural nerve and Iliacus muscle. 

The Psoas Parvus is a long slender muscle, placed immediately in front of the 
preceding. It arises from the sides of the bodies of the last dorsal and first lum- 
bar vertebrse, and from the inter-vertebral substance between them. It forms a 
small flat muscular bundle, which terminates in a broad flattened tendon, which is 
inserted into the ilio-pectineal eminence, being continuous, by its outer border, 
with the iliac fascia. This muscle is most frequently found wanting, being pre- 
sent, according to M. Theile, in one out of every twenty subjects examined. 

Relations. It is covered by the peritoneum, and at its origin by the ligamentum 
arcuatum internum; it rests on the Psoas magnus. 

The Iliacus is a flat radiated muscle, which fills up the whole of the in- 
ternal iliac fossa. It arises from the inner concave surface of the ilium, from 
the inner margin of the crest of that bone; behind, from the ilio-lumbar liga- 
ment, and base of the saci-um; in front, from the anterior superior and anterior 
inferior spinous processes of the ilium, the notch between them, and by a few fibres 
from the capsular ligament of the hip-joint. The fibres converge to be inserted 
into the outer side of the tendon common to this muscle and the Psoas magnus, 
some of them being prolonged down into the oblique line which extends from 
the lesser trochanter to the linea aspera. 

Relations. Within the pelvis : by its anterior surface, with the iliac fascia, 

T 2 



276 



MUSCLES AND FASCIiE. 



which separates this muscle from the peritoneum, and with the external cutaneous 
nerve; on the right side, with the caecum; on the left side, with the sigmoid flexure 
of the colon. By its posterior surface, with the iliac fossa. By its inner border, 
with the Psoas magnus, and anterior crural nerve. In the thigh, it is in relation, 
by its anterior surface, with the fascia lata, Rectus and Sartorius; behind, with 
the capsule of the hip-joint, a synovial bursa common to it, and the Psoas magnus 
being interposed. 

Nerves. The Psore muscles are supplied by the anterior branches of the lumbar 
nerves. The Iliacus from the anterior crural. 

Actions. The Psoas and Iliacus muscles, acting from above, flex the thigh upon 
the pelvis, and, at the same time, rotate the femur outwards, from the obliquity 
of their insertion into the inner and back part of that bone. Acting from below, 
the femur being fixed, the muscles of both sides bpnd the lumbar portion of the 
spine and pelvis forwards. They also serve to maintain the erect position, by 
supporting the spine and pelvis upon the femur, and assist in raising the trunk 
Avhen the body is in the recumbent posture. 

The Psoas parvus is a tensor of the iliac fascia. 

Anterior Femoral Region. 



i63. 



Tensor Vaginje Feraoris. 

Sartorius. 

Rectus. 

-Dissection of Lower Extremity. 
FroiTt view. 



^ 1 



i . DtsstetLon 
femoral hernia, 
Scarpa's triangle 



Z. FRONTo/"THICH 



"f 



■^ 



/f , DOR.SUMcf FOOT 



Vastus Externus. 
Vastus In tern us. 
Cruraeus. 
Sub-Crui'aeus. 

Dissection. To expose the muscles and 
fascise in this region, an incision should be 
made along Poupart's ligament, from the spine 
of the ilium to the pubes, from the centre 
of this, a vertical incision must be carried 
along the middle Hne of the thigh to below 
the knee-joint, and connected with a trans- 
verse incision, carried from the inner to 
the outer side of the leg. The flaps of in- 
tegument having been removed, the super- 
ficial and deep fasciae should be examined. 
The more advanced student would com- 
mence the study of this region by an exa- 
mination of the anatomy of femoral hernia, 
and Scarpa's triangle, the incisions for the 
dissection of which are marked out in the 
accompanying figure. 

Fascia of the Thigh. 

The Superficial fascia, forms a con- 
tinuous layer over the whole of the 
lower extremity, consisting of areolar tis- 
sue, containing in its meshes much adipose 
matter, and capable of being separated 
into two or more layers, between which 
are found the superficial vessels and 
nerves. It varies in thickness in diflPe- 
rent parts of the limb; in the sole of the 
foot it is so thin, as to be scarcely demon- 
strable, the integument being closely ad- 
herent to the deep fascia beneath, but in 
the groin it is thicker, and the two layers 
are separated from one another by the 
superficial inguinal glands, the internal 
saphenous vein, and several smaller ves- 
sels. Of these two layers, the most 



ANTEEIOR FEMORAL REGION. 



-77 



superficial is continuous above with tlie 
superficial fascia of the abdomen, the deep 
layer becoming blended Avith the fascia 
lata, a little below Poupart's ligament. 
The deep layer of superficial fascia is inti- 
mately adherent to the margins of the saphe- 
nous opening in the fascia lata, and pierced 
in this situation by numerous small blood 
and lymphatic vessels, hence the name crib- 
riform fascia, which has been applied to 
it. Subcutaneous bursas are found in the 
superficial fascia over the patella, point ot 
the heel, and phalangeal articulations of the 
toes. 

The Deep fascia of the thigh is exposed 
on the removal of the superficial fascia, and 
is named, from its great extent, the fascia 
lata ; it forms a uniform investment for the 
whole of this region of the limb, but varies 
in thickness in different parts; thus, it is 
thickest in the upper and outer side of the 
thigh, where it receives a fibrous expansion 
from the Gluteus maximus muscle, and the 
Tensor vaginae femoris is inserted between 
its layers, it is very thin behind, and at 
the upper and inner side, where it covers 
the Adductor muscles, and again becomes 
stronger around the knee, receiving fibrous 
expansions from the tendons of the Biceps 
externally, and from the Sartorius, Gracilis, 
Semitendinosus, and Triceps extensor cruris 
in front. The fascia lata is attached, above; 
to Poupart's ligament, and crest of the ilium, 
behind to the margin of the sacrum and 
coccyx, internally to the pubic arch and pec- 
tineal line, and below to all the prominent 
points around the knee-joint, the condyles 
of the femur, tuberosities of the tibia, and 
head of the fibula. That portion which 
invests the Gluteus medius (the Gluteal 
aponeurosis) is very thick and strong, and 
gives origin, by its inner surface, to some of 
the fibres of that muscle; at the upper bor- 
der of the Gluteus maximus, it divides into 
two layers; the most superficial, A^ery thin, 
covers the surface of the Gluteus maximus, 

>and is continuous below with the fascia lata: 
the deep layer is thick above, and blends 
with the great sacro- sciatic ligament, thin 
below, where it separates the Gluteus max- 
imus from the deeper muscles. From the 
innel" surface of the fascia lata, are given 
off" two strong intermuscular septa, which are 
attached to the whole length of the linea 
aspera; the external and stronger one, ex- 
tending from the insertion of the Gluteus 
maximus, to the outer condyle, separates 



[69.— Muscles of the Iliac and 
Femoral Regions. 



Aiiieriur 




278 MUSCLES AND FASCIJE. 

the Vastus externus in front from the short head of the Biceps behind, and gives 
partial origin to these muscles ; the inner one, the thinner of the two, separates 
the Vastus internus from the Adductor muscles. Besides these, there are nu- 
merous smaller septa, separating the individual muscles, and enclosing each in 
a distinct sheath. At the upper and inner part of the thigh, a little below 
Poupart's ligament, a large oval-shaped aperture is observed in this fascia, 
it transmits the internal saphenous vein, and other smaller vessels, and is 
termed the saphenous opening. In order more correctly to consider the mode 
of formation of this aperture, the fascia lata is described as consisting, in this 
part of the thigh, of two portions, an iliac portion, and a pubic portion. 

The iliac portion is all that part of the fascia lata placed on the outer side of 
the saphenous opening. It is attached, externally, to the crest of the ilium, and its 
anterior superior spine, to the whole length of Po\ipart's ligament, as far inter- 
nally as the spine of the pubes, and to the Pectineal line in conjunction with 
Gimbernat's ligament. From the spine of the pubes, it is reflected downwards 
and outwards, forming an arched margin, the superior cornu, or outer boundary of 
the saphenous opening ; this margin overlies, and is adherent to the anterior 
layer of the sheath of the femoral vessels, to its edge is attached the cribri- 
form fascia, and, below, it is continuous with the pubic portion of the fascia lata. 

The pubic portion is situated at the inner side of the saphenous opening; at 
the lower margin of this aperture it is continuous with the iliac portion ; traced 
upwards, it is seen to cover the surface of the Pectineus muscle, and passing 
behind the sheath of the femoral vessels, to which it is closely united, is conti- 
nuous with the sheath of the Psoas and Iliacus muscles, and is finally lost in the 
fibrous capsule of the hip-joint. This fascia is attached above, to the pectineal line in 
front of the insertion of the aponeurosis of the external oblique, and internally, to the 
margin of the pubic arch. From this description it may be observed, that the 
iliac portion of the fascia lata passes in front of the femoral vessels, the pubic 
portion behind them, an apparent aperture consequently exists, between the 
two, through which the internal saphena joins the femoral vein. 

The fascia should now be removed from the surface of the muscles. This may be effected 
by pinching it up between the forceps, dividing it, and separating it from each muscle in 
the course of its fibres. 

The Tensor Vagince Femoris is a short flat muscle, situated at the upper and 
outer side of the thigh. It arises by aponeurotic fibres from the anterior part 
of the outer lip of the crest of the ilium, and from the outer surface of the an- 
terior superior spinous process, between the Gluteus medius, and Sartorius. 
The muscle passes obliquely downwards, and a little backwards, to be inserted 
by tendinous fibres between the two layers of the fascia lata, about one fourth 
down the thigh. 

Relations. By its superficial surface, with a layer of the fascia lata and the 
integument. By its deep surface, with the deep layer of the fascia lata, the 
Gluteus medius, Rectus femoris, and. Vastus externus. By its anterior border, 
with the Sartorius, from which it is separated below by a triangular space, in 
which is seen the Rectus femoris. By its posterior border, with the Gluteus me- 
dius, being separated from it below by a slight interval. 

The Sartorius, the longest muscle in the body, is a flat, narrow, riband-like 
muscle, which arises by tendinous fibres from the anterior superior spinous process 
of the ilium and upper half of the notch below it; it passes obliquely inwards, 
across the upper and anterior part of the thigh, then descends vertically, as far 
as the inner side of the knee, passing behind the inner condyle of the femur, and 
terminates in a tendon, which curving obliquely forwards, expands into a broad 
aponeurosis, which is inserted into the upper part of the inner surface of the 
shaft of the tibia, nearly as far forwards as the crest. This expansion covers 
in the insertion of the tendons of the Gracilis and Semitendinosus, with which 
it is partially united, a synovial bursa being interposed between them. An offset 



ANTERIOR FEMORAL REGION. 279 

is derived from this aponeurosis, whicli blends with the fibi'ous capsule of the knee- 
joint, and another, given off from its lower border, blends with the fascia on the 
inner side of the leg. The relations of this muscle to the femoral artery should 
be carefully examined, as its inner border forms the chief guide in the operation 
of including this vessel in a ligature. In the upper third of the thigh, it forms, 
with the Adductor longus, the sides of a triangular space, Scarpa's triangle, the 
base of which, turned upwards, is formed by Poupart's ligament; the femoral artery 
passes perpendicularly through the centre of this space from its base to its apex. 
In the middle third of the thigh, the femoral artery lies first along the inner bor- 
der, and then beneath the Sartorius. 

Relations. By its superficial surface, with the fascia lata and integument. 
By its deep surface with the Iliacus, Psoas, Rectus, Vastus internus, sheath of 
the femoral vessels, Adductor longus. Adductor magnus, G-racilis, long saphenous 
nerve, and internal lateral ligament of the knee-joint. 

The Quadriceps Extensor Cruris, includes the four remaining muscles on the 
anterior part of the thigh. They are the great Extensor muscles of the leg, 
forming a large fleshy mass, which covers the anterior surface and sides of the 
femur, being united below into a single tendon, attached to the tibia, and above 
subdividing into separate portions, which have received sepai-ate names. Of 
these, one occupying the middle of the thigh, connected above with the ilium, 
is called the Rectus Femoris, from its straight course. The other divisions lie 
in immediate connection with the shaft of the femur, which they cover from the 
condyles to the trochanters. The portion on the outer side of the femur being 
termed the Vastus Externus, that covering the inner side the Vastus Internus, 
and that covering the front of the bone, the Crurceus. The two latter portions 
are, however, so intimately blended, as to form but one muscle. 

The Rectus Femoris, is situated in the middle of the anterior region of the 
thigh; it is fusiform in shape, and its fibres are arranged in a bipenniform man- 
ner. It arises by two tendons; one, the straight tendon, from the anterior 
inferior spinous process of the ilium, the other is flattened and curves outwards, 
to be attached to a groove above the brim of the acetabulum ; this is the reflected 
tendon of the Rectus, it unites with the straight tendon at an acute angle, and 
then spreads into an aponeurosis, from which the muscular fibres arise. The 
muscle terminates in a broad and thick aponeurosis, which occupies the lower 
two-thirds of its posterior surface, and, gradually becoming narrowed into a 
flattened tendon, is inserted into the patella in common with the Vasti and 
Crurteus. 

Relations. By its superficial surface, with the anterior fibres of the Gluteus 
medius, the Tensor vaginge femoris, Sartorius, and the Psoas and Iliacus, by its 
lower three-fourths with the fascia lata. By its posterior surface, with the 
hip-joint, the anterior circumflex vessels, and the Cruraeus and Vasti muscles. 

The three remaining muscles have been described collectively by some anatomists, 
separate from the Rectus, under the name of the Triceps Extensor Cruris ; in 
order to expose them, divide the Sartorius and Rectus muscles across the middle, 
and turn them aside, when the Triceps extensor will be fully brought into 
view. 

The Vastus Externus is the largest part of the Quadriceps extensor. It arises 
by a broad aponeurosis, which is attached to the anterior border of the great 
trochanter, to a horizontal ridge on its outer surface, to a rough line, leading from 
the trochanter major to the linea aspera, and to the whole length of the outer 
lip of the linea aspera ; this aponeurosis covers the upper three-fourths of the 
muscle, and from its inner surface, many fibres arise. A few additional fibres 
arise from the tendon of the Gluteus maximus, and from the external inter- 
muscular septum between the Vastus externus, and short head of the Biceps. 
These fibres form a large fleshy mass, which is attached to a strong aponeurosis, 
placed on the under surface of the muscle at its lowest part, this becomes con- 



28o MUSCLES AND FASCIA. 

tracted and thickened into a flat tendon, which is inserted into the outer part of 
the upper border of the patella, blending with the great Extensor tendon. 

Relations. By its superficial surface, with the Rectus, the Tensor vaginge 
femoris, the fascia lata, and the Gluteus maximus, from which it is separated by 
a synovial bursa. By its deep surface, with the Crurgeus, some large branches 
of the external circumflex artery being interposed. 

The Vastus internus and Crurceus, are so inseparably connected together, as 
to form but one muscle. It is the smallest portion of the Quadriceps extensor. 
The anterior portion covered by the Rectus, being called the Crurgeus, the internal 
portion, which lies immediately beneath the fascia lata, the Vastus Internus. It 
arises by an aponeurosis, which is attached to the lower part of the line that 
extends from the inner side of the neck of the femur to the linea aspera, from 
the whole length of the inner lip of the linea aspera, and internal intermuscular 
septum. It also arises from nearly the whole of the internal, anterior and 
external surfaces of the shaft of the femur, limited above by the line between 
the two trochanters, and extending below to within the lower fourth of the 
bone. From these different origins, the fibres converge to a broad aponeurosis, 
which covers the anterior surface of the middle portion of the muscle (the 
Cruragus), and the deep surface of the inner division of the muscle (the Vastus 
internus), becoming joined and gradually narrowing, it is inserted into the patella, 
blending with the other portions of the Quadriceps extensor. 

Relations. By their superficial surface, with the Psoas and Iliacus, the Rectus, 
Sartorius, Pectineus, Adductors, and fascia lata, femoral artery, vein, and saphe- 
nous nerve. By its deep surface, with the femur, subcruraeus and synovial 
membrane of the knee joint. 

The student will observe the striking analogy that exists between the 
Quadriceps extensor, and the Triceps brachialis in the upper extremity. So 
close is this similarity, that M. Cruvelhier has described it under the name of 
the Triceps femoralis. Like the Triceps brachialis, it consists of three distinct 
divisions or heads ; a middle or long head, analogous to the long head of the 
Triceps, and of two other portions which have respectively received the 
names of the external and internal heads of the muscle. These, it will be 
noticed, are strictly analogous to the outer and inner heads of the Triceps 
brachialis. 

The Subcrurceus is a small muscular fasciculus usually distinct from the super- 
ficial muscle, which arises from the anterior surface of the lower part of the shaft 
of the femur, and is inserted into the upper part of the synovial pouch that 
extends upwards from the knee-joint behind the patella. This fasciculus is 
occasionally united with the Cruraeus. It sometimes consists of two separate 
muscular bundles. 

The tendons of the different portions of the Quadriceps extensor unite at the 
lower part of the thigh, so as to form a single strong tendon, which is inserted 
into the upper part of the patella. More properly speaking, the patella may be 
regarded as a sesamoid bone, developed in the tendon of the Quadriceps extensor, 
and the ligamentum patellre, which is continued from the lower part of the patella, 
to the tuberosity of the tibia, as the proper tendon of insertion of this muscle. A 
small synovial bursa is intei-posed between the tendon and the upper part of the tube- 
rosity. From the tendons corresponding to the Vasti, a fibrous prolongation is 
derived, which is attached below to the upper extremities of the tibia and fibula. 
It serves to protect the knee-joint, which is strengthened on its outer side by the 
fascia lata. 

Nerves. The Tensor vaginae femoris is supplied by the superior gluteal 
nerve, the other muscles of this region, by branches from the anterior 
crural. 

Actions. The Tensor vaginas femoris is a tensor of the fascia lata ; continuing 
its action, the oblique direction of its fibres enables it to rotate the thigh inwards. 



INTERNAL FEMORAL REGION. 



2«I 



-Muscles of the Internal Femoral 
Region. 



In the erect posture, acting from below, it will serve to Bteady the pelvis upon 
the head of the femur. The Sartorius flexes the leg upon the thigh, and, con- 
tinuing to act, the thigh upon the pelvis, at the same time drawing the limb 
inwards, so as to cross one leg over 
the other. Taking its fixed point from 170.- 
the leg, it flexes the pelvis upon the 
thigh, and, if one muscle acts, assists in 
rotating it. The Quadriceps extensor 
extends the leg upon the thigh. Taking 
their fixed point from the leg, as in 
standing, the Extensor muscles will act 
upon the femur, supporting it perpendi- 
cularly upon the head of the tibia, 
thus maintaining the entire weight of the 
body. The Rectus muscle assists the 
Psoas and Iliacus, in supporting the pel- 
vis and trunk upon the femur, or in 
bending it forwards. 



Internal Femoral Region. 

Gracilis. 
Pectineus. 
Adductor Longus. 
Adductor Brevis. 
Adductor Magnus. 

Dissections. These muscles are at once ex- 
posed by removing the fascia from the fore 
part and inner side of the thigh. The limb 
should be abducted so as to render the mus- 
cles tense, and easier of dissection. 

The Gracilis is the most superficial 
muscle on the inner side of the thigh. It 
is a thin, flattened, slender muscle, broad 
above, narrow and tapering below. It 
arises by a thin aponeurosis between two 
and three inches in breadth, from the 
inner margin of the ramus of the pubes 
and ischium. The fibres pass vertically 
downwards, and terminate in a rounded 
tendon which passes behind the internal 
condyle of the femur, and curving around 
the inner tuberosity of the tibia, becomes 
flattened, and is inserted into the upper 
part of the inner surface of the shaft of th6 
tibia, beneath the tuberosity. The ten- 
don of this muscle is situated immediately 
above that of the Semi-tendinosus, and 
beneath the aponeurosis of the Sar- 
torius, with which it is in part blended. 
As it passes across the the internal lateral 
ligament of the knee-joint, it is separated 
from it by a synovial bursa, common to it 
and the Semi-tendinosus muscle. 

Relations. By its superficial surface, 
with the fascia lata and the Sartorius 




282 MUSCLES AND FASCIA. 

below; the internal saphena vein crosses it obliquely near its lower part, lying su- 
perficial to the fascia lata. By its deep surface, with the three Adductors, and 
the internal lateral ligament of the knee-joint. 

The Pectineus is a flat quadrangular muscle, situated at the anterior part of the 
upper and inner aspect of the thigh. It arises from the linea ilio-pectinea, from 
the surface of bone in front of it, between the pectineal eminence and spine 
of the pubes, and from a tendinous prolongation of Gimbernat's ligament, 
which is attached to the crest of the pubes, and is continuous with the fascia 
covering the outer surface of the muscle; the fibres pass downwards, backwards, 
and outwards, to be inserted into a rough line leading from the trochanter minor 
to the linea aspera. 

Relations. By its anterior surface, with the pubic portion of the fascia lata, 
which separates it from the femoral vessels and iilternal saphena vein. By its 
posterior surface, with the hip-joint, the Adductor brevis and Obturator externus 
muscles, the obturator vessels and nerve being interposed. By its outer border, 
with the Psoas, a cellular interval separating them, upon which lies the femoral 
artery. By its inner border, with the margin of the Adductor longus. 

The Adductor Longus, the most superficial of the thi'ee Adductors, is a flat 
triangular muscle, lying on the same plane as the Pectineus, with which it is often 
blended above. It arises, by a flat narrow tendon, from the front of the pubes, at 
the angle of junction of the crest with the symphysis; it soon expands into a broad 
fleshy belly, which, passing downwards, backwards, and outwards, is inserted, by 
an aponeurosis, into the middle third of the linea aspera, between the Vastus 
intern us and the Adductor magnus. 

Relations. By its anterior surface, with the fascia lata, and near its insertion, 
with the femoral artery and vein. By its posterior surface, with the Adductor 
brevis and magnus, the anterior branches of the obturator vessels and nerve, and 
with the profunda artery and vein near its insertion. By its outer border, with 
the Pectineus. By its inner border, with the Gracilis. 

The Pectineus and Adductor longus should now be divided near their origin, and turned 
downwards, when the Adductor brevis and Obturator externus will be exposed. 

The Adductor Brevis is situated immediately beneath the two preceding muscles. 
It is somewhat triangular in form, and arises by a narrow origin from the outer 
surface of the descending ramus of the pubes, between the Gracilis and Obturator 
externus. Its fibres passing backwards, outwards, and downwards, are inserted by 
an aponeurosis into the upper part of the linea aspera, immediately behind the Pec- 
tineus and upper part of the Adductor longus. 

Relations. By its anterior surface, with the Pectineus, Adductor longus, and 
anterior branches of the obturator vessels and nerve. By its posterior surface, 
with the Adductor magnus, and posterior branches of the obturator vessels and 
nerves. By its outer border, with the Obturator externus, and conjoined tendon of 
the Psoas and Iliacus. By its inner border, with the Gracilis and Adductor mag- 
nus. This muscle is pierced, near its insertion, by the middle perforating branch 
of the profunda artery. 

The Adductor brevis should now be cut away near its origin and turned outwards, when 
the entire extent of the Adductor magnus will be exposed. 

The Adductor Magnus is a large triangular muscle, forming a septum between 
the muscles on the inner, and those on the posterior aspect of the thigh. It arises 
by short tendinous fibres from a small part of the descending ramus of the pubes, 
from the ascending ramus of the ischium, and from the outer margin and under 
surface of the tuberosity of the ischium. Those fibres which arise from the ramus 
of the pubes are very short, horizontal in direction, and are inserted into the rough 
line leading from the great trochanter to the linea aspera, internal to the Gluteus 
maximus; those from the ramus of the ischium are directed downwards and out- 
wards with different degrees of obliquity, to be inserted by means of a broad apo- 
neurosis, into the whole length of the interval between the two lips of the linea 



INTERNAL FEMORAL REGION. 283 

aspera and upper part of the internal bifurcation below. The internal portion of 
the muscle, consisting principally of those fibres which arise from the tuberosity 
of the ischium, forms a thick fleshy mass consisting of coarse bundles which 
descend almost vertically, and terminate about the lower third of the thigh in a 
rounded tendon, which is inserted into the tuberosity above the inner condyle of 
the femur, being connected by a fibrous expansion to the line leading upwards from 
the condyle to the linea aspera. Between these two portions of the muscle, an 
angular interval is left, almost entirely tendinous in structure, for the passage of 
the femoral vessels into the popliteal space. The external portion of the muscle 
is pierced by four apertures, the three superior for the three perforating arteries; 
the fourth, for the passage of the profunda. This muscle gives oif an aponeu- 
rosis, which passes in front of the femoral vessels, and joins with the Vastus 
internus. 

Relations. By its anterior surface, with the Pectineus, Adductor brevis, Ad- 
ductor longus and the femoral vessels. By its posterior surface, with the great 
sciatic nerve, the Gluteus maximus, Biceps, Semi-tendinosus, and Semi-membra- 
nosus. By its superior or shortest border, it lies parallel with the Quadratus 
femoris. By its internal or longest border, with the Gracilis, Sartorius, and fascia 
lata. By its external or attached border, it is inserted into the femur behind the 
Adductor brevis and Adductor longus, which separate it, in front, from the Vastus 
internus; and in front of the Gluteus maximus and short head of the Biceps, which 
separate it from the Vastus externus. 

Nerves. All the muscles of this group are supplied by the obturator nerve. 
The Pectineus receives additional branches from the accessory obturator and ante- 
rior crural; and the Adductor magnus an additional one from the great sciatic. 

Actions. The Pectineus and three Adductors adduct the thigh powerfully; they 
are especially used in horse-exercise, the flanks of the horse being firmly grasped 
between the knees by the action of these muscles. From their oblique insertion 
into the linea aspera, they rotate the thigh outwards, assisting the external Rotators, 
and when the limb has been abducted, they draw it inwards, carrying the thigh 
across that of the opposite side. The Pectineus and Adductor brevis and longus 
assist the Psoas and Iliacus in flexing the thigh upon the pelvis. In progression, 
also, all these muscles assist in di'awing forwards the hinder limb. The Gracilis 
assists the Sartorius in flexing the leg and drawing it inwards; it is also an Ad- 
ductor of the thigh. If the lower extremities are fixed, these muscles may take 
their fixed point from below and act upon the pelvis, serving to maintain the body 
in the erect posture; or, if their action is continued, to flex the pelvis forwards 
upon the femur. 

Gluteal Region. 

Gluteus Maximus. Gemellus Superior. 

Gluteus Medius. Obturator Internus. 

Gluteus Minimus. Gemellus Inferior. 

Pyriformis. Obturator Externus. 

Quadratus Femoris. 

Dissection (fig. 171) The subject should be turned on its face, a block placed beneath the 
pelvis to make the buttocks tense, and the limbs allowed to hang over the end of the table, 
the foot inverted, and the limb abducted. An incision should be made through the integu- 
ment along the back part of the crest of the ihum and margin of the sacrum to the tip of 
the coccyx, from which point a second incision should be carried obliquely downwards and 
outwards to the outer side of the thigh, four inches below the great trochanter. The por- 
tion of integument included between these incisions, together with the superficial fascia, 
should be removed in the direction shewn in the figure, when the Gluteus maximus and 
the dense fascia covering the Gluteus medius will be exposed. 

The Gluteus Maximus, the most superficial muscle in the gluteal region, is a 
very broad and thick fleshy mass, of a quadrilateral shape, which forms the pro- 
minence of the nates. Its large size is one of the most characteristic points in 



284 



MUSCLES AND FASCIA. 



/ , Dissection of 

GLUTEAL REGION 



the muscular system in man, connected as it is with the power he has of main- 
taining the trunk in the erect posture. In structure it is remarkably coarse, being 
made up of muscular fasciculi lying parallel with one another, and collected 
together into large bundles, separated by deep cellular intervals. It arises from 
the superior curved line of the ilium, and the portion of bone, including the ci*est, 
immediately behind it; from the posterior surface of the last piece of the sacrum, 

the sides of the coccyx, and posterior surface 
171.— Dissection of Lower Extremity, f t^e great sacro-sciatic and posterior sacro- 
posterior View. iliac ligaments. The fibres are directed ob- 
liquely downwards and outwards; those forming 
the upper and larger portion of the muscle 
(after converging somewhat) terminate in a 
thick tendinous lamina, which passes across 
the great trochanter, and is inserted into the 
fascia lata covering the outer side of the thigh, 
the lower portion of the muscle being inserted 
into the rough line leading from the great 
trochanter to the linea aspera, between the 
Vastus externus and Adductor magnus. 

Three synovial bursce are usually found se- 
parating the under surface of this muscle from 
the eminences which it covers. One of these, 
of large size, and generally multilocular, sepa- 
rates it from the great trochanter. A second, 
often wanting, is situated on the tuberosity of 
the ischium. A third, between the tendon of 
this muscle and the Vastus externus. 

Relations. By its superficial surface, with 
a thin fascia, which separates it from cellular 
membrane, fat, and the integument. By its 
deep surface, with the ilium, sacrum, coccyx, 
and great sacro-sciatic ligament, the Gluteus 
medius, Pyriformis, Gemelli, Obturator inter- 
nus, Quadratus femoris, the great sacro-sciatic 
foramen, the tuberosity of the ischium, great 
trochanter, the Biceps, Semi-tendinosus, Semi- 
membranosus, and Adductor magnus muscles, the 
gluteal vessels and nerve issuing from the pelvis 
above the Pyriformis muscle, ihe ischiatic and 
internal pudic vessels and nerves below it. Its 
upper border is thin, and connected with the 
Gluteus medius by the fascia lata. Its lower 
border, free and prominent, forms the fold of the 
nates, and is directed towards the perineum. 

Dissection. The Gluteus maximus should now be divided near its origin by a vertical 
incision carried from its upper to its lower border: a cellular interval will be exposed, 
separating it from the Gluteus medius and External rotator muscles beneath. The upper 
portion of the muscle should be altogether detached, and the lower portion turned out- 
wards; the loose areolar tissue filling up the interspace between the trochanter major and 
tuberosity of the ischium being removed, the parts already enumerated as exposed by the 
removal of this muscle wiU be seen. 

The Gluteus Medius is a broad, thick, radiated muscle, situated on the outer 
surface of the pelvis. Its posterior third is covered by the Gluteus maximus; its 
anterior two-thirds, is covered by a layer of fascia, which is thick and dense, 
and separates it from the integument. It arises from the outer surface of the 
ilium, between the superior and middle curved lines, and from the outer lip of 
that portion of the crest which is between them; it also arises from the dense 



BA.CK of THICB 



POPLITEAL SPACE 



BACK of LEG 



ST 



GLUTEAL REGION. 



285 



fascia covering its outer sur- 
face. The fibres gradually 
converge to a strong flattened 
tendon, which is inserted into 
the oblique line which tra- 
verses the outer surface of 
the great trochanter. A 
synovial bursa separates the 
tendon of this muscle from 
the surface of the trochanter 
in front of its insertion. 

Relations. By its superfi- 
cial surface, with the Gluteus 
maximus, Tensor vaginae fe- 
moris, and deep fascia. By 
its deep surface, with the 
Gluteus minimus and the glu- 
teal vessels and nerve. Its 
anterior border is blended 
Avith the Gluteus minimus 
and Tensor vaginae femoris. 
Its posterior border lies 
parallel with the Pyriformis. 

This muscle should now be 
divided near its insertion and 
turned upwards, when the Glu- 
teus minimus will be exposed. 

The Gluteus Minimus, the 
smallest of the three glutei, 
is placed immediately beneath 
the preceding. It is a fan- 
shaped muscle, arising from 
the external surface of the 
ilium, between the middle and 
inferior curved lines, and 
behind, from the margin of 
the great sacro-sciatic notch; 
the fibres converge to the 
deep surface of a radiated 
aponeurosis, Avhich, terminat- 
ing in a tendon, is inserted 
into an impression on the an- 
terior border of the great tro- 
chanter. A synovial bursa is 
interposed between the ante- 
rior part of the tendon and 
the great trochanter. 

Relations. By its superfi- 
cial surface, with the Gluteus 
medius, and the gluteal vessels 
and nerves. By its deep sur- 
face, with the ilium, the re- 
flected tendon of the Rectus 
femoris, and capsular liga- 
ment of the hip-joint. Its 
anterior margin is blended 



172. — Muscles of the Gluteal and Posterior 
Femoral Regions. 




286 MUSCLES AND FASCIA. 

with the Gluteus medius. Its posterior margin is often joined with the tendon 
of the Pyriformis. 

The Pyriformis is a flat muscle, pyramidal in shape, lying almost parallel with 
the lower margin of the Grluteus minimus. It is situated partly within the pelvis 
at its posterior part, and partly at the back part of the hip-joint. It arises from 
the anterior surface of the sacrum by three fleshy digitations, attached to the por- 
tions of bone interposed between the second, third, and fourth anterior sacral 
foramina, and also from the grooves leading from them: a few fibres also arise 
from the margin of the great sacro- sciatic foramen, and from the anterior surface 
of the great sacro-sciatic ligament. The muscle passes out of the pelvis through 
the great sacro-sciatic foramen, the upper part of which it fills, and is inserted, by 
a rounded tendon, into the back part of the upper border of the great trochanter, 
being generally blended with the tendon of the Obturator internus. 

Relations. By its anterior surface, within the pelvis, with the Rectum (espe- 
cially on the left side), the sacral plexus of nerves, and the internal iliac vessels; 
external to the pelvis, with the os innominatum and capsular ligament of the hip- 
joint. By it^ posterior surface, within the pelvis, with the sacrum; and external 
to it, with the Gluteus maximus. By its upper border, with the Gluteus medius, 
from which it is separated by the gluteal vessels and nerves. By its loioer border, 
with the Gemellus superior; the ischiatic vessels and nerves, and the internal 
pudic vessels and nerves, passing from the pelvis in the interval between them. 

Dissection. The next muscle, as well as the origin of the Pyriformis, can only be seen 
when the pelvis is divided, and the viscera contained in this cavity removed. 

The Obturator Internus, like the preceding muscle, is situated partly within 
the cavity of the pelvis, partly at the back of the hij)-joint. It arises from the 
inner surface of the anterior and external wall 6f the pelvis, being attached to 
the margin of bone around the inner side of the obturator foramen; viz., from the 
descending ramus of the pubes, and the ascending ramus of the ischium; and, 
laterally, from the inner surface of the body of the ischium, between the margin 
of the obturator foi-amen in front, the great sciatic notch behind, and the brim of 
the true pelvis above. It also arises from the inner surface of the obturator mem- 
brane, and from the tendinous arch which protects the obturator vessels and nerve 
in passing beneath the sub-pubic arch. The fibres converge downwards and out- 
wards, and terminate in four or five tendinous bands, which are found on its deep 
surface; these bands are reflected at a right angle over the inner surface of the 
tuberosity of the ischium, which is covered with cartilage, grooved for their recep- 
tion, and lined with a synovial bursa. The muscle leaves the pelvis by the lesser 
sacro-sciatic notch; and the tendinous bands unite into a single flattened tendon, 
which passes horizontally outwards, and, after receiving the attachment of the 
Gemelli, is inserted into the upper border of the great trochanter in front of the 
Pyriformis. A synovial bursa., nai'row and elongated in form, is usually found 
between the tendon of this muscle and the capsular ligament of the hip. It occa- 
sionally communicates with that between the tendon and the tuberosity of the 
ischium, the two forming a single sac. 

In order to display the peculiar appearances presented by the tendon of this muscle, it 
should be divided near its insertion and reflected outwards. 

Relations. Within the pelvis, this muscle is in relation, by its anterior surface, 
with the obturator membrane and inner surface of the anterior wall of the pelvis; 
by its posterior surface, with the obturator fascia, Avhich separates it from the 
Levator ani; and it is crossed by the internal pudic vessels and nerve. This 
surface forms the outer boundary of the ischio-rectal fossa. External to the 
pelvis, it is covered by the great sciatic nerve and Gluteus maximus, and rests 
on the back part of the hip-joint. 

The Gemelli are two small muscular fascicvili, accessories to the tendon of the 
Obturator internus, which is received into a groove between them. They have 
received the names superior and inferior from the position they occupy. 



J 



GLUTEAL REGION. 287 

The Gemellus Superior, the smaller of the two, is a fleshy fasciculus, which 
arises from the external surface of the spine of the ischium, and passing horizon- 
tally outwards, becomes blended with the upper part of the tendon of the Obturator 
internus, and is inserted with it into the superior border of the great trochanter. 
This muscle is sometimes wanting. 

Relations. By its superficial surface, with the Gluteus maximus and the 
ischiatic vessels and nerves. By its deep surface, with the capsule of the hip- 
joint. By its upper border, with the lower margin of the Pyriformis. By its 
lower border, with the tendon of the Obturator internus. 

The Gemellus Inferior arises from the upper part of the outer border of the 
tuberosity of the ischium, and, passing horizontally outwards, is blended with the 
lower part of the tendon of the Obturator internus, and inserted with it into the 
upper border of the great trochanter. 

Relations. By its superficial surface, with the Gluteus maximus, and the 
ischiatic vessels and nerves. By its deep surface, it covers the capsular ligament 
of the hip-joint. By its upper border, with the tendon of the Obturator internus. 
By its loiver border, with the tendon of the Obturator externus and Quadratus 
femoris. 

The Quadratus Femoris is a short flat muscle, quadrilateral in shape (hence its 
name), situated immediately below the Gemellus inferior, and above the upper 
margin of the Adductor magnus. It arises from the external border of the 
tuberosity of the ischium, and proceeding horizontally outwards, is inserted into 
the upj)er part of the linea quadrati, on the posterior surface of the trochanter 
major, A synovial bursa is often found between the under surface of this muscle 
and the lesser trochanter, which it covers. 

Relations. By its posterior surface, with the Gluteus maximus and the ischiatic 
vessels and nerves. By its anterior surface, with the tendon of the Obturator 
externus and Trochanter minor. By its upper border, with the Gemellus inferior. 
Its lower border is separated from the Adductor magnus by the internal circumflex 
vessels. 

Dissection. In order to expose the next muscle (the Obturator ezternus), it is necessary 
to remove the Psoas, Iliacus, Pectineus, and Adductor brevis and longus muscles, from the 
front and inner side of the thigh ; and the Gluteus maximus and Quadratus femoris, from 
the back part. Its dissection should consequently be postponed until the muscles of the 
anterior and internal femoral regions have been examined. 

The Obturator Externus is a flat triangular muscle, which covers the outer 
surface of the anterior wall of the pelvis. It arises from the margin of bone 
immediately around the inner side of the obturator foramen, viz., from the body 
and ramus of the pubes, and the ramus of the ischium; it also arises from the 
inner two-thirds of the outer surface of the obturator membrane, and from the 
tendinous arch which completes the sub-pubic canal for the passage of the obturator 
vessel and nerve. The fibres converging pass outwards, and terminate in a ten- 
don which runs across the back part of the hip-joint, and is inserted into the 
digital fossa of the femur. 

Relations. By its anterior surface, with the Psoas, Iliacus, Pectineus, Adductor 
longus. Adductor brevis, and Gracilis; and more externally, with the neck of the 
femur and capsule of the hip-joint. By its posterior surface, with the obturator 
membrane and Quadratus femoris. 

Nerves. The Gluteus maximus is supplied by the inferior gluteal nerve and a 
branch from the sacral plexus. The Gluteus medius and minimus, by the superior 
gluteal. The Pyriformis, Gemelli, Obturator internus, and Quadratus femoris, by 
branches from the sacral plexus. And the Obturator externus, by the obturator 
nerve. 

Actions. The Glutei muscles, when they take their fixed point from the pelvis, 
are all abductors of the thigh. The Gluteus maximus and the posterior fibres of 
the Gluteus medius, rotate the thigh outwards; the anterior fibres of the Gluteus 
medius and the Gluteus minimus rotate it inwards. The Gluteus maximus serves 



288 MUSCLES AND FASCIA. 

to extend the femur, and the Gluteus medius and minimus draw it forwards. The 
Gluteus maximus is also a tensor of the fascia lata. Taking their fixed point 
from the femur, the Glutei muscles act upon the pelvis, supporting it and the whole 
trunk upon the head of the femur, which is especially obvious in standing on one 
leg. In order to gain the erect posture after the efibrt of stooping, these muscles 
draw the pelvis backwards, assisted by the Biceps, Semi-tendinosus, and Semi- 
membranosus muscles. The remaining muscles are powerful rotators of the thigh 
outwards. In the sitting posture, when the thigh is flexed upon the pelvis, their 
action as rotators ceases, and they become abductors, with the exception of the 
Obturator externus, which still rotates the femur outwards. When the femur is 
fixed, the Pyriformis and Obturator muscles serve to draw the pelvis forwards if 
it has been inclined backwards, and assist in steadying it upon the head of the 
femur. 

Posterior Febioral Region. 

Biceps. Semi-tendinosus. Semi-membranosus. 

Dissection (fig. 171). Make a vertical incision along the middle of the thigh, from the lower 
fold of the nates to about three inches below the back of the knee-joint, and there connect it 
with a transverse incision, carried from the inner to the outer side of the leg. A third inci- 
sion should then be made transversely at the junction of the middle with the lower third of 
the thigh. The integument having been removed from the back of the knee in the direc- 
tion indicated in the figure, and the boundaries and contents of the popliteal space exa- 
mined, the removal of the integument from the remaining part of the thigh should be 
continued, when the fascia and muscles of this region will be exposed. 

The Biceps is a large muscle, of considerable length, situated on the posterior 
and outer aspect of the thigh. It arises by two distinct portions or heads. One, 
the long head, from an impression at the upper and back part of the tuberosity of 
the ischium, by a tendon common to it and the Semi-tendinosus. The femoral or 
short head, from the outer lip of the linea aspera, between the Adductor magnus 
and Vastus externus, extending from two inches below the Gluteus maximus, to 
within two inches of the outer condyle; it also arises from the external inter- 
muscular septum. The fibres of the long head form a fusiform belly, which, 
passing obliquely downwards and a little outwards, terminates in an aponeurosis 
which covers the posterior surface of the muscle, and receives the fibres of the 
short head; this aponeurosis becomes gradually contracted into a tendon, which is 
inserted into the outer side of the head of the fibula. At its insertion, the tendon 
divides into two portions, which embrace the external lateral ligament of the knee- 
joint, a strong prolongation being sent forwards to the outer tuberosity of the tibia, 
which gives off an expansion to the fascia of the leg. The tendon of this muscle 
forms the outer ham-string. 

Relations. By its superficial surface, with the Gluteus maximus and fascia lata. 
By its deep surface, with the Semi-membranosus, Adductor magnus, and Vastus 
externus, the great sciatic nerve, popliteal artery and vein, and near its insertion, 
with the external head of the Gastrocnemius, Plantaris, and superior external 
articular artery. 

The Semitendinosus, remarkable for the great length of its tendon, is situated 
at the posterior and inner aspect of the thigh. It arises from the tuberosity of 
the ischium by a tendon common to it and the long head of the Biceps; it also 
arises from an aponeurosis which connects the adjacent surfaces of the two muscles 
to the extent of about three inches after their origin. It forms a fusiform muscle 
which, passing downwards and inwards, terminates a little below the middle of 
the thigh in a long round tendon, which lies along the inner side of the popliteal 
space, curving around the inner tuberosity of the tibia, to be inserted into the 
upper part of the inner surface of the shaft of this bone, nearly as far forwards 
as its anterior border. This tendon lies beneath the expansion of the Sartorius, 
and below that of the Gracilis, to which it is united. A tendinous intersection is 
usually observed about the middle of this muscle. 

Relations. By its superficial surface, with the Gluteus maximus and fascia lata. 



POSTERIOR FEMORAL REGION. 289 

By its deep surface, with the Semi-membranosus, Adductor magnus, inner head of 
the G-astrocnemius, and internal lateral ligament of the knee-joint. 

The Semi-membranosus, so called from the tendinous expansion on its anterior 
and posterior surfaces, is situated at the back part and inner side of the thigh. 
It arises by a thick tendon from the upper and outer part of the tuberosity of the 
ischium above and to the outer side of the Biceps and Semi-tendinosus, and 
is inserted into the posterior part of the inner tuberosity of the tibia, beneath 
the internal lateral ligament. The tendon of this muscle at its insertion divides 
into three portions; the middle portion is the fasciculus of insertion into the back 
part of the inner tuberosity, it sends down an expansion to cover the Popliteus 
muscle. The internal portion is horizontal, passing forwards beneath the internal 
lateral ligament, to be inserted into a groove along the inner side of the internal 
tuberosity. The posterior division passes upwards and backwards, to be inserted 
into the back part of the outer condyle of the femur, forming the chief part of the 
posterior ligament of the knee-joint. 

The tendon of origin of this muscle expands into an aponeurosis, which covers 
the upper part of its anterior surface; from this muscular fibres arise, and con- 
verge to another aponeurotic expansion, which covers the lower part of its posterior 
surface, and this contracts into the tendon of insertion. The tendons of the two 
preceding muscles, with those of the Gracilis and Sartorius, form the inner ham- 
string. 

Relations. By its superficial surface, with the Gluteus maximus, Semi-tendi- 
nosus, Biceps, and fascia lata. By its deep surface, with the Quadratus femoris. 
Adductor magnus, and inner head of the Gastrocnemius. It covers the popliteal 
artery and vein, and is separated from the knee-joint by a synovial membrane. 
By its inner border, with the Gracilis. By its outer border, with the great 
sciatic nerve. 

Nerves. The muscles of this region are supplied by the great sciatic nerve. 
Actions. The three ham-string muscles flex the leg upon the thigh. When the 
knee is semi-flexed, the Biceps, from its oblique direction downwards and out- 
wards, rotates the leg slightly outwards; and the Semi-membranosus, in consequence 
of its oblique direction, rotates the leg inwards, assisting the Popliteus. Taking 
their fixed point from below, these muscles serve to support the pelvis upon the 
head of the femur, and to draw the trunk directly backwards, as is seen in feats 
of strength, when the body is thrown backwards in the form of an arch. 

Surgical Anatomy. The tendons of these muscles occasionally require subcutaneous 
division in some forms of spurious anchylosis of the knee-joint, dependent upon permanent 
contraction and rigidity of the flexor muscles, or from stiff"ening of the ligamentous and 
other tissues surrounding the joint, the result of disease. This is easily effected by putting 
the tendon upon the stretch, and inserting a narrow sharp-pointed knife between it and 
the skin ; the cutting edge being then turned towards the tendon, it should be divided, 
taking care that the wound in the skin is not at the same time enlarged. This operation 
has been attended with considerable success in some cases of stiffened knee from rheuma- 
tism, gradual extension being kept up for some time after the operation. 

Muscles and Fascia of the Leg. 

Dissection (fig. 168). The knee should be bent, a block placed beneath it, and the foot 
kept in an extended position ; an incision should then be made through the integument in 
the middle line of the leg to the ankle, and continvied along the dorsum of the foot to the 
toes. A second incision should be made transversely across the ankle, and a third in the 
same direction across the bases of the toes: the flaps of integument included between 
these incisions should be removed, and the fascia of the leg examined. 

The ■ Fascia of the Leg forms a complete investment to the whole of this 
region of the limb, excepting to the inner surface of the tibia, to which it is un- 
attached. It is continuous above with the fascia lata, receiving an expansion 
from the tendon of the Biceps on the outer side, and from the tendons of the 
Sartorius, Gracilis, and Semi-tendinosus on the inner side; in front it blends 
with the periosteum covering the tibia and fibula; below, it is continuous with 

u 



ago 



MUSCLES AND FASCIA. 



the annular ligaments of the ankle. It is 
thick and dense in the upper and anterior 
part of the leg, and gives attachment, by its 
inner surface, to the Tibialis anticus and Ex- 
tensor longus digitorum muscles; but thinner 
behind, where it covers the Grastrocnemius and 
Soleus muscles. Its inner surface gives off, on 
the outer side of the leg, two strong inter- 
muscular septa, which enclose the Peronsei 
muscles, and separate them from those on the 
anterior and posterior tibial regions, and several 
smaller and more slender processes enclose 
the individual muscles in each region; at 
the same time, a broad transverse intermus- 
cular septum intervenes between the superficial 
and deep muscles in the posterior tibio-fibular 
region. 

The fascia should now be removed by dividing it 
in the same direction as the integument, excepting 
opposite the ankle, where it should be left entire. 
The removal of the fascia should be commenced 
from below, opposite the tendons, and detached in 
the line of direction of the muscular fibres. 

Muscles of the Leg. 

These may be subdivided into three groups: 
those on the anterior, those on the posterior, 
and those on the outer side. 

Anterior Tibio-Fibular Region. 

Tibialis Anticus. 
Extensor Proprius Pollicis. 
Extensor Longus Digitorum. 
Peroneus Tertius. 

The Tibialis Anticus is situated on the outer 
side of the tibia, being thick and fleshy at its 
upper part, tendinous below. It arises from 
the outer tuberosity and upper two-thirds of 
the external surface of the shaft of the tibia; 
from the adjoining part of the interosseous 
membrane; from the deep fascia of the leg; 
and from the intermuscular septum between it 
and the Extensor communis digitorum: the 
fibres pass vertically downwards, and terminate 
in a tendon, which is apparent on the anterior 
surface of the muscle at the lower third of the 
leg. After passing through the innermost 
compartment of the anterior annular ligament, 
it is inserted into the inner side of the internal 
cuneiform bone, and base of the metatarsal 
bone of the great toe. 

Relations. By its anterior surface, with the 
deep fascia, and with the annular ligament. 
By its posterior surface, with the interosseous 
membrane, tibia, and ankle-joint. By its inner 
surface, with tlie tibia. By its otiter surface, 
with the Extensor longus digitorum, and 



173. — Muscles of the Front of 
the Leg. 



BH 



Tllii 



ANTERIOR TIBIO-FIBULAR REGION. 291 

Extensor proprins pollicis, the anterior tibial vessels and nerve lying between it 
and the last mentioned muscles. 

The Extensor Proprius Pollicis is a thin, elongated, and flattened muscle, 
situated between the Tibialis anticus and Extensor longus digitorum. It arises 
from the anterior surface of the fibula for about the two middle fourths of its 
extent, its origin being internal to the Extensor longus digitorum; it also arises 
from the interosseous membrane to a similar extent. The fibres pass down- 
wards, and terminate in a tendon, which occupies the anterior border of the 
muscle, passes through a distinct compartment in the annular ligament, and is 
inserted into the base of the last phalanx of the great toe. Opposite the metatarso- 
phalangeal articulation, the tendon gives off a thin prolongation on each side, 
which covers its surface. 

Relations. By its anterior border, with the deep fascia of the leg, and the 
anterior annular ligament. By its posterior border, with the interosseous mem- 
brane, fibula, tibia, ankle-joint, and Extensor brevis digitorum. By its outer 
side, with the Extensor longus digitorum above, the dorsalis pedis artery and 
anterior tibial nerve below. By its inner side, with the Tibialis anticus, and the 
anterior tibial vessels above. 

The Extensor Longus Digitorum is an elongated, flattened, semi-penniform 
muscle, situated the most external of all the muscles on the fore-part of the leg. 
It arises from the outer tuberosity of the tibia; from the upper three-fourths of 
the anterior surface of the shaft of the fibula; from the interosseous membrane, 
deep fascia; and from the intermuscular septa between it and the Tibialis anticus 
on the inner, and the Peronei on the outer side. The fibres pass downwards, and 
terminate in four tendons, v/hich pass through a distinct canal in the annular liga- 
ment, together with the Peroneus tertius, run across the dorsum of the foot, and 
are inserted into the second and third phalanges of the four lesser toes. The 
mode in which these tendons are inserted is the following. Each tendon opposite 
the metatarso-phalangeal articulation is joined on its outer side by a tendon of 
the Extensor brevis digitorum (except the fourth), and receives a fibrous expansion 
from the Interossei and Lumbricales; it then spreads into a broad aponeurosis, 
which covers the dorsal surface of the first phalanx: this aponeurosis, at the 
articulation of the first with the second phalanx, divides into three slips, a middle 
one, which is inserted into the base of the second phalanx, and two lateral slips, 
which, after uniting on the dorsal surface of the second phalanx, are continued 
onwards to be inserted into the base of the third. 

Relations. By its anterior surface, with the deep fascia of the leg, and the 
annular ligament. By its posterior surface, with the fibula, interosseous mem- 
brane, ankle-joint, and Extensor brevis digitorum. By its inner side, with the 
Tibialis anticus, Extensor proprius pollicis, and anterior tibial vessels and nerve. 
By its outer side, with the Peroneus longus and brevis. 

The Peroneus Tertius is but a part of the Extensor longus digitorum, being 
almost always intimately united with it. It arises from the lower fourth of the 
anterior surface of the fibula; its outer part, from the lower part of the inter- 
osseous membrane; and from an intermuscular septum between it and the Pero- 
neus brevis. Its tendon, after passing through the same canal in the annular 
ligament as the Extensor longus digitorum, is inserted into the base of the meta- 
tarsal bone of the little toe on its dorsal surface. 

This muscle is often wanting. 

Nerves. These muscles are supplied by the anterior tibial nerve. 

Actions. The Tibialis anticus and Peroneus tertius are the direct flexors of the 
tarsus upon the leg; the former muscle, from the obliquity in the direction of 
its tendon, raises the inner border of the foot; and the latter, acting with the 
Peroneus brevis and longus, will draw the outer border of the foot upwards and 
the sole outwards. The Extensor longus digitorum and Extensor proprius pollicis 
extend the phalanges of the toes, and continuing their action, flex the tarsus upon 
the leg. Taking their origin from below, in the erect posture, all these muscles 

u 2 



2g2 



MUSCLES AND FASCIA. 



serve to fix the bones of the leg in a perpendicular direction, and give increased 
strength to the ankle-joint. 

POSTEKIOR TiBIO-FlBULAR EeGION. 

Dissection (fig. 171). Make a vertical incision along the middle line of the back of the 
leg, from the lower part of the popliteal space to the heel, connecting it below by a trans- 
verse incision extending between the two malleoli; the flaps of integument being removed, 
the fascia and muscles should be examined. 



174. — Muscles of the Back of the Leg. 
Superficial Layer. 




The muscles in this region of the leg are 
subdivided into two layers, superficial and 
deep. The superficial layer constitutes a 
powerful muscular mass, forming what is 
called the calf of the leg. Their large size 
is one of the most characteristic features of 
the muscular apparatus in man, and bears a 
direct connection with his ordinary attitude 
and mode of progression. 

Superficial Layer. 

Gastrocnemius. Soleus. 

Plantaris, 

The Gastrocnemius is the most superficial 
muscle at the back part of the leg, and 
forms the greater part of the calf. It 
arises by two heads, which are connected 
to the condyles of the femur by two 
strong flat tendons. The inner head, the 
larger, and a little the most posterior, is 
attached to a depression at the upper and 
back part of the inner condyle. The outer 
head, to the upper and back part of the 
external condyle, immediately above the 
origin of the Popliteus. Both heads, also, 
arise by a few tendinous and fleshy fibres 
from the ridges which are continued up- 
wards from the condyles to the linea aspera. 
Each tendon spreads into an aponeurosis, 
which covers the posterior surface of that 
portion of the muscle to which it belongs; 
that covering the inner head being longer 
and thicker than the outer. From the an- 
terior surface of these tendinous expansions 
muscular fibres are given off"; those in the 
median line, which correspond to the acces- 
sory portion of the muscle derived from the 
bifurcations of the linea aspera, unite at an 
angle upon a median tendinous raphe below. 
The remaining fibres converge to the poste- 
rior surface of an aponeurosis which covers 
the front of the muscle, and this, gradually 
contracting, unites with the tendon of the 
Soleus, and forms with it the tendo Achillis. 

Relations. By its superficial surface, 
with the fascia of the leg, which sepa- 
rates it from the external saphenous vein 
and nerve. By its deep surface, with the 



POSTERIOR TIBIO-FIBULAR REGION. 



293 



posterior ligament of the knee-joint, the Popliteus, Soleus, Plantaris, popliteal 
vessels, and internal popliteal nerve. The tendon of the inner head corresponds 
with the back part of the inner condyle, from which it is separated by a synovial 
bursa, which in some cases communicates with the cavity of the knee-joint. The 
tendon of the outer head contains a sesamoid fibro-cartilage (rarely osseous), where 
it plays over the corresponding outer condyle; and one is occasionally found in the 
tendon of the inner head. 

The Gastrocnemius should be divided across just below its origin, and turned down- 
wards, in order to expose the next muscles. 

The Soleus is a broad flat muscle, situated immediately beneath the preceding, 
It has received its name from the fancied resemblance it bears to a sole-fish. It 
arises by tendinous fibres from the back part of the head, and from the upper half 
of the posterior surface of the shaft of the fibula, from the oblique line of the tibia, 
and from the middle third of its internal border; some fibres also arise from a 
tendinous arch which passes between the tibial and fibular origins of the muscle, 
and beneath which the posterior tibial vessels and nerve pass into the leg. The 
fibres pass backwards to an aponeurosis which covers the posterior surface of the 
muscle, and this, gradually becoming thicker and narrower, joins with the tendon 
of the Gastrocnemius, and forms with it the tendo Achillis. 

Relations. By its superficial surface, with the Gastrocnemius and Plantaris. 
By its deep surface, with the Flexor longus digitorum. Flexor longus pollicis. 
Tibialis posticus, and posterior tibial vessels and nerve ; from which it is separated 
by the transverse intermuscular septum, interposed between the superficial and 
deep muscles at the back of the leg. 

The Tendo Achillis, the common tendon of the Gastrocnemius, Soleus, and 
Plantaris, is the thickest and strongest tendon in the body. It is about six inches 
in length, and formed by the junction of the aponeuroses of the two preceding 
muscles. It commences about the middle of the leg, but receives fleshy fibres 
much lower on its anterior surface. Gradually becoming contracted below, it is 
inserted into the lower part of the posterior tuberosity of the os calcis, a synovial 
bursa being interposed between the tendon and the upper part of the tuberosity. 
Externally it is covered by the fascia and the integument, and it is separated 
beneath from the deep seated muscles and vessels, by a considerable interval filled 
up with areolar and adipose tissue. 

The Plantaris is an extremely diminutive muscle, placed between the Gastroc- 
nemius and Soleus, and remarkable for the long and delicate tendon which it 
presents. It arises from the lower part of the external bifurcation of the linea 
aspera, and from the posterior ligament of the knee-joint. It forms a small fusi- 
form belly, about two inches in length, which terminates in a long and slender 
tendon, which crosses obliquely between the two muscles of the calf, and running 
along the inner border of the tendo Achillis, is inserted with it into the poste- 
rior part of the os calcis. This muscle is occasionally double, it is sometimes 
wanting. Occasionally its tendon is lost in the subcutaneous adipose tissue, or in 
the internal annular ligament. 

Nerves, These muscles are supplied by the internal popliteal nerve. 

Actions. The muscles of the calf possess considerable power, and are constantly 
called into use in standing, walking, dancing, and leaping, hence the large size 
they usually present. In walking, these muscles draw powerfully upon the os 
calcis, raising the heel, and, with it, the entire body, from the ground; the body 
being thus supported on the raised foot, the opposite limb can be carried forwards. 
In standing, the Soleus, taking its fixed point from below, steadies the leg upon 
the foot, and prevents the body from falling forwards, to which there is a constant 
tendency from the super-incumbent weight. The Gastrocnemius, acting from 
below, serves to fiex the femur upon the tibia, assisted by the Popliteus. The 
Plantaris is the rudiment of a large muscle which exists in some of the lower 
animals, and serves as a tensor of the plantar fascia. 



294 



MUSCLES AND FASCIA. 



175. — Muscles of the Back of the Leg, 
Deep Layer. 



Femu7^\\ 



Iw 



Posterior Tibio-Fibular Region. 

Deep Layer. 

Popliteus. Flexor Longus Digitorum. 

Flexor Longus Pollicis. Tibialis Posticus. 

Dissection. Detach the Soleus from its attachment to the fibula and tibia, and turn it 

downwards, when the deep layer of muscles is 
exposed, covered by the deep fascia of the leg. 

The deej) fascia of the leg is a broad, 
transverse inter-muscular septum, interposed 
between the superficial and deep muscles, 
in the^ posterior tibio-fibular region. On 
each side it is connected to the margins of 
the tibia and fibula. Above, where it covers 
the Popliteus, it is thick and dense, and 
receives an expansion from the tendon of 
the Semi-membranosus; it is thinner in the 
middle of the leg, but, below, where it 
covers the tendons passing behind the mal- 
leoli, it is thickened. It is continued on- 
wards in the interval between the ankle and 
the heel, where it covers the vessels and 
is blended with the internal annular liga- 
ment. 

This fascia should now be removed, com- 
mencing from below opposite the tendons, and 
detaching it "from the muscles in the direction of 
their fibres. 

The Popliteus is a thin, flat, triangular 
muscle, which forms the floor of the popli- 
teal space, and is covered in by a tendinous 
expansion, derived from the Semi-membra- 
nosus muscle. It arises by a strong flat 
tendon, about an inch in length, from a deep 
depression on the outer side of the external 
condyle of the femur, and from the posterior 
ligament of the knee-joint; and is inserted 
into the inner two-thirds of the triangular 
surface above the oblique line on the poste- 
rior part of the shaft of the tibia, and into 
the tendinous expansion covering the surface 
of the muscle. The tendon of this muscle 
is covered in by that of the Biceps and the 
external lateral ligament of the knee-joint ; 
it grooves the outer surface of the external 
semilunar cartilage, and is invested by the 
synovial membrane of the knee-joint. 

Relations. By its superficial surface, with 
the fascia above mentioned, which separates 
it from the Gastrocnemius, Plantaris, popli- 
teal vessels and internal popliteal nerve. 
By its deep surface, with the tibio-flbular 
articulation and back of the tibia. 

The Flexor Longus Pollicis is situated 
on the fibular side of the leg, and is the 
most superficial, and largest of the three 
next muscles. It arises from the lower two- 



POSTERIOR TIBIO-FIBULAR REGION. 



295 



tliirds of the internal surface of the shaft of the fibula, with the exception of an 
inch below, from the lower part of the interosseous membrane, from an inter-mus- 
cular septum between it and the Peroneus longus and brevis, externally; and from 
the fascia covering the Tibialis posticus. The fibres pass obliquely downwards 
and backwards, and terminate around a tendon which occupies nearly the wliole 
length of the posterior surface of the muscle. This tendon passes through a 
groove on the posterior surface of the tibia, external to that for the Tibialis pos- 
ticus and Flexor longus digitorum; it then passes through a second groove on the 
posterior extremity of the astragalus, and along a third groove, beneath the tubercle 
of the OS calcis, into the sole of the foot, where it runs forwards between the two 
heads of the Flexor brevis pollicis, and is inserted into the base of the last pha- 
lanx of the great toe. The grooves in the astragalus and os calcis which contain 
the tendon of this muscle, are converted by tendinous fibres into distinct canals, 
lined by synovial membrane; and as the tendon crosses the sole of the foot, it is 
connected to the common Flexor by a tendinous slip. 

Relations. By its superficial surface, with the Soleus and tendo Achillis, from 
which it is separated by the deep fascia. By its deep surface, with the fibula. 
Tibialis posticus, the peroneal vessels, the lower part of the interosseous mem- 
brane, and the ankle-joint. By its outer border, with the Peroneus longus and 
brevis. By its inner border, with the Tibialis posticus, and Flexor longus digi- 
torum. 

The Flexor Longus Digitorum is situated on the inner or tibial side of the leg. 
At its origin, it is thin and pointed, but gradually increases in size as it descends. 
It arises from the posterior surface of the shaft of the tibia, immediately be- 
low the oblique line, to within three inches of its extremity, internal to the 
tibial origin of the Tibialis posticus; some fibres also arise from the intermus- 
cular septum, between it and the Tibialis posticus. The fibres terminate in a 
tendon, which runs nearly the whole length of the posterior surface of the muscle. 
This tendon passes, behind the inner Malleolus, in a groove, common to it, and the 
Tibialis posticus, from which it is separated by a fibrous septum ; each tendon is 
lined by a separate synovial membrane. It then passes, obliquely, forwards and 
outwards, beneath the arch of the os calcis, into the sole of the foot, where, 
crossing beneath the tendon of the Flexor longus pollicis, to which it is connected 
by a strong tendinous slip, it becomes expanded, is joined by the Musculus 
accessoriuri, and, finally divides into four tendons, which are inserted into the 
bases of the last phalanges of the four lesser toes, each tendon passing through 
a fissure in the tendon of the Flexor brevis digitorum, opposite the middle of the 
first phalanges. 

Relations. In the leg. By its superficial surface, with the Soleus, and the 
posterior tibial vessels and nerve, from which it is separated by the deep fascia. 
By its deep surface, with the Tibia and Tibialis posticus. In the foot, it is 
covered by the Abductor pollicis, and Flexor brevis digitorum, and crosses beneath 
the Flexor longus pollicis. 

The Tibialis Posticus lies between the two preceding muscles, and is the most 
deeply seated of all the muscles in the leg. It commences above, by two pointed 
processes, separated by an angular inteiwal, through which, the anterior tibial 
vessels pass forwards to the front of the leg, arising from the posterior surface 
of the interosseous membrane, its whole length, excepting its lowest part, from 
the posterior surface of the shaft of the tibia, external to the Flexor longus 
digitorum, between the commencement of the oblique line above, and the centre 
of the external border of the bone below, and from the upper two-thirds of the 
inner surface of the shaft of the fibula; some fibres also arise from the deep 
fascia, and from the intermuscular septa, separating it from the adjacent muscles 
on each side. The fibres terminate in a tendon, which passes in front of the 
Flexor longus digitorum, through a groove behind the inner Malleolus, enclosed 
in a separate sheath; it then passes through another she.ith, over the internal 
lateral ligament, and beneath the calcaneo-scaphoid articulation, and is inserted 



296 MUSCLES AND FASCIA. 

into the tuberosity of the scaphoid, and internal cuneiform bones. The tendon 
of this muscle, contains a sesamoid bone, near its insertion, and gives off 
fibrous expansions, one of which, passes backwards to the os calcis, others ovit- 
wards to the middle and external cuneiform, and some forwards to the bases of 
the third and fourth metatarsal bones. 

Relations. By its superficial surface, with the Soleus, Flexor longus digito- 
rum. Flexor longus pollicis, the posterior tibial vessels and nerve, and the 
peroneal vessels, from which it is separated by the deep fascia. By its 
deep surface, with the interrosseous ligament, the tibia, fibula, and ankle- 
joint. 

Nerves. The Popliteus is supplied by the internal popliteal nerve, the remain- 
ing muscles of this group, by the posterior tibial nerve. 

Actions. The Popliteus assists in flexing the leg upon the thigh, and, when 
flexed, it may rotate the tibia inwards. The Tibialis posticus is a direct Extensor 
of the tarsus upon the leg; acting in conjunction with the Tibialis anticus, it 
turns the sole of the foot inwards, antagonizing the Peroneus longus which 
turns it outwards. The Flexor longus digitorum, and Flexor longus pollicis, are 
the direct Flexors of the phalanges, and, continuing their action, extend the foot 
upon the leg ; they assist the Gastrocnemius and Soleus in extending the foot, 
as in the act of walking, or in standing on tiptoe. In consequence of the oblique 
direction of the tendon of the long Extensor, the toes would be drawn inwards, 
were it not for the Flexor accessorius muscle, which is inserted into the outer side 
of that tendon, and draws it to the middle line of foot, during its action. Taking 
their fixed point from the foot, these muscles serve to maintain the upright pos- 
ture, by steadying the tibia and fibula, perpendicularly, upon the ankle-joint. They 
also serve to raise these bones from the oblique position they assume in the 
stooping posture. 

Fibular Region. 
Pei'oneus Longus. Peroneus Brevis. 

Dissection, These muscles are readily exposed, by removing the fascia, covering their 
surface, from below upwards, in the line of direction of their fibres. 

The Peroneus Longus is situated at the upper part of the outer side of the 
leg. It arises from the head, and upper two-thirds of the outer surface of the 
shaft of the fibula, from the deep fascia, and from the intermuscular septa, 
between it and the muscles on the anterior, and those on the posterior surface 
of the leg. It terminates in a long tendon, which passes behind the outer 
malleolus, in a groove, common to it, and the Peroneus brevis, the groove being 
converted into a canal by a fibrous band, and the tendons, invested by a com- 
mon synovial membrane; it is then reflected, obliquely forwards, across the outer 
side of the os calcis, being contained in a separate fibrous sheath, lined by a 
prolongation of the synovial membrane, from the groove behind the malleolus. 
Having reached the outer side of the cuboid bone, it runs, in a groove, on its 
under surface, which is converted into a canal, by the long calcaneo-cuboid liga- 
ment, lined by a synovial membrane, and crossing, obliquely, the sole of the foot, 
is inserted into the outer side of the base of the metatarsal bone of the great toe. 
The tendon of the muscle has a double reflection^ first, behind the external malleolus, 
secondly, on the outer side of the cuboid bone; in both of these situations, the 
tendon is thickened, and, in the latter, a sesamoid bone is usually developed in 
its substance. 

Relations. By its superficial surface, with the fascia and integument. By its 
deep surface, with the fibula, the Peroneus brevis, os calcis, and cuboid bone. 
By it§ anterior border, a tendinous septum intervenes between it and the 
Extensor longus digitorum. By its posterior border, an intermuscular septum, 
separates it from the Soleus above, and the Flexor longus pollicis below. 

The Peroneus Brevis lies beneath the Peroneus longus, and is shorter and 



FIBULAR REGION. 



297 



smaller than it. It arises from the lower two-thirds of the external surface of the 
shaft of the fibula, internal to the Peroneus longus ; from the anterior and poste- 
rior borders of the bone; and from the intei'muscular septa separat