Handle with EXTREME CARE This volume is BRITTLE: and cannot be repaired Photocopy only if necessar GERSTEIN SCIENCE INFORMATION CENTRE Library of the Academy of Medicine Coronta LiS66S~ Presented by 2. Vope, 08 Digitized by the Internet Archive in 2008 with funding from Microsoft Corporation http://www.archive.org/details/atlastextoookofh01 sobouoft ATLAS AND TEXT-BOOK HUMAN ANATOMY DR. JOHANNES SOBOTTA PROFESSOR OF ANATOMY IN THE UNIVERSITY OF WURZBI EDITED, WITH ADDITIONS, BY J. PLAYFAIR McCMURRICH, A.M., PH. D. FORMERLY PROFESSOR OF THE UNIVERSITY OF TOF PROFESSOR OF ANATOMY IN UNIVERSITY OF ANATOMY IN THE MICHIGAN VOLUME | BONES, LIGAMENTS, JOINTS, AND MUSCLES With 320 Illustrations, Mostly in Colors PHILADELPHIA AND LONDON W. B. SAUNDERS COMPANY 1914 EDITOR’S PREFACE. ‘ _ There can be no question as to the value of a good Atlas of Anatomy as an aid to the acquisition and retention of correct ideas regarding the structure of the human body and the relations of its various parts. Anatomy, at least the descriptive part of it, is learned only when one can call up a mental picture of the part in question, and volumes of description will do less to furnish a correct picture than will a single dissection or the inspection of an accurate illustration. This is especially true as regards relational anatomy, and without an accurate knowledge of the relations of parts the student or practitioner will find himself sadly at sea in his application of Anatomy to diagnosis and treatment. To both the student and the practitioner, therefore, a good Atlas must prove a great boon, to the one in enabling him we impress upon his mind what he has seen in the laboratory, without ecourse to the pernicious ‘“‘quiz-compend,” which is but a Tantalus cup, to the other in recalling the mental image more or less blurred by time. The present Atlas, with its wealth of accurate illustrations and its thorough though concise descriptive text, is presented to English- speaking students and practitioners in the full confidence that it will prove of the greatest value — to them. The work of the Editor in adapting the Atlas for English readers has largely been confined to changes in the nomenclature and in the arrangement of the text. In the original German edition the text and Atlas were separate volumes, the Atlas proper being provided with a _ descriptive epitome of the parts represented in the various figures. It has seemed best, both to the publisher and to the Editor of the present edition, to unite the text and Atlas in a com- mon volume, much repetition being thereby avoided and the result being still a volume of con- venient size. The translation of the German text has been done by Dr. W. Hersey Thomas. As to the nomenclature employed, it jis essentially that proposed by the Basel Committee on Anatomical Nomenclature, the terms being, however, for the most part Anglicized. In the e ‘tion on Myology the Latin terfms have been retained throughout, since usage has already e many of them familiar in their classical form and it seemed preferable, for uniformity’s “ to use that form for all. A few terms may be found somewhat unfamiliar to English- spea king students of anatomy, and when these are used the more familiar term has been added in parentheses. The adoption of a uniform code of nomenclature is of such great im- portance that the slight inconvenience which the present generation may experience in the temporary use of a double set of names for a few structures will be more than counterbalanced by the advantages which a universal terminology will eventually offer. : Tue Epriror. It 14 AUTHOR’S PREFACE. In order to insure the accuracy of the illustrations, all of the preparations were photographed and the photograph was made exactly the same size as the intended illustration, lenses of the longest possible focal length being employed to avoid perspective distortion.* In the great majority of the illustrations photographs were employed as the basis of the drawings; Figs. 167 to 171 are direct reproductions of photographs, and Figs. 178 and 181 were made from photographs which had been touched up. Only a few illustrations are diagrammatic, and in such instances it has been so stated in the titles. The illustrations produced by the half-tone method have been made much clearer by the use of a number of colors. A buff color has been employed for the bones in the pictures of the joints and of the muscles, and various colors have been used for the different bones of the skull and in the topographic views of the cranium.f No illustration has been omitted which would make the relations of the parts more readily understood. Microscopic and topographic anatomy have been disregarded to a certain extent, although enough has been given to serve as an outline for the subsequent volumes, which will be more topographic than descriptive in character. The parts have been designated according to the Basel nomenclature. The original drawings for this Atlas were executed by Messrs. K. Hajek and A. Schmitson.{ The former gentleman, who will also furnish the illustrations for the subsequent volumes, has performed his difficult task with such special aptitude and cleverness that the remaining volumes promise to be even better and to exhibit still greater uniformity in the method of production. A number of the specimens from which the illustrations were made are in the collection of the Anatomical Institute (Wiirzburg), and I take this occasion to express my special thanks to Professor Stéhr for his permission to employ them in this work. The majority of the joint preparations, all of the muscle dissections and some of the bones, I-have myself prepared for the Atlas. In addition to the photographed specimens, other dissections have been made and compared, so that every illustration in the book has an individual character, with the exception that marked anomalies have been corrected. ‘The muscles have been given a bright red color such as they exhibit in a fresh body after they have been exposed for a short time, although less intense tones have been selected than those of the natural muscular and fatty tissues. The publishers have spared nothing to make the illustrations excel those of all other works in character and to equal if not exceed those of the majority in number. In spite of this, how- ever, the price of the work is much lower than that of most other atlases. THE AUTHOR. tions were necessary they have been distributed over several figures. In some instances explanatory outline etchings have been appended with the designations inscribed thereon. In the lithographic plates the inscriptions have been made by a second impression. * In a few cases in which perspective distortion was feared even when lenses of the longest focal lengths were em- ployed, the subject was photographed to one-half the size of the desired illustration and the photograph was subsequently enlarged. } In carrying out this idea the same bone has always been represented by the same color; for example, the palate bone in blue, the ethmoid in orange. ¢ About ten of the illustrations in the Atlas were sketched by W. Freytag, drawing master in the University, and subsequently completed by Mr. Hajek. es cencceacceeesvesces 17 Careless scdccsccssscusee 19 0 0 6 19 OSTEOLOGY 3 22 SKELETON OF THE TRUNK.............. 22 The Vertebral Column................. 22 _ The True Vertebra................---- 22 ene (Cervical Vertebre................- 23 ~ The Thoracic Vertebre................. 26 ys Lhe Lumbar Vertebre................. 27 The False MerteDhe.clek -s- > <2. = 104 The Joints of the Foot.......------=seem : The Five Metatarsal Bones... --=5----- 105 The Ligaments of the Tarsus.......--.-- ; hts Beges Othe 1 OCS. - ween o.cak sos 5 =e 105 The Sesamoid Bones of the Foot.......-- 106 Myology --------------------++++-+2222225 The Skeleton of the Foot as a Whole..... 106 | Generar MYOLOGY........------+- soe 1 Syndesmology ------------------+--+-+-+-- 107 | Spectra, MVOLOGY........-.-------5neeee ] hs es rhe apenas Berita Lair pak mie Sele fe 107 | Tere MUSCLES OF THE TRUNK...-.--------- m9 “aaa eee ae Me ee a The Muscles of the Back. -.--. Sage BRE GS ean ava > oie er pn = = we & aint Al The Short Muscles of the Neck.......... SPECIAL SUNDESMOLOGY. ca Woon se nenenaees IIo | ve a of aie --° +0 > ei e ominal Muscles... -2252ee=eeeee Jormnts AND LIGAMENTS OF THE VERTEBRAL The Abdominal Fasciz.....---esseeeee TOBRIIEN fou aia oes a eae ere ee IIo The Diaphragm.......-. 2225 =e The Connections of the Vertebral Bodies .110 The Thoracic Muscles.....-.. 2. ene : The Intervertebral Articulations BEA Poe III The Pectoral Fasciz.....-.20 00mm The Ligaments of the Vertebral Column...111 The Muscles of the Neck......--------- : The Articulations of Sacrum and Coccyx. .113 The Prevertebral Cervical Muscles.....-.- The Articulation of the Upper Two Cer- The Fascie of the Neck......-------«e- : vical Vertebre with Each Other and paLathe Oceipitsc con. Sie. eeteen Set 113 | THE MUSCLES OF THE HEAD..-... 52 ope The Articulations of the Ribs with the Ver- | The Muscles of the Face and of the Scalp . tebral Column and with the Sternum..116 The Fascie of the Head... .2 22 2eeeeeee THE ARTICULATIONS AND LIGAMENTS OF THE | THE MUSCLES OF THE UPPER EXTREMITY ..--: HEAD.....------------ sees peceee 117 | The Muscles of the Shoulder............: The Temporomandibular Articulation. ...118 The Muscles of the Upper Arm........--: The Independent Ligaments of the Head.118 The Muscles of the Forearm.....---«-<<: The Ligaments of the Hyoid Bone....... 119 The Muscles of the Hand..... eo seuneoee THE Jomnts AND LIGAMENTS OF THE UPPER The Muscles of the Thenar Eminence... .: ESrREMITe! 55.2 vie ee nO The Muscles of the Hypothenar Eminence: The Sternoclavicular Articulation........ 1I9Q | The Interossei and Lumbricales....--.-~ The Acromioclavicular Articulation. ...-. 120 The Relations of the Extensor Tendons and The Ligaments of the Scapula........-.--. 120 ae beneath the Dorsal oe A MeMmOIUIGET-JOMIE. «nn tate oo vig ae ei obi 121 pat Mgaments . - --— 93 The Elbow-joint an Hees oe . age The Extensor Tendons of the Fingers. shies The Distal Radio-ulnar Joint and the In- The Tendons and Synovial Sheaths of “ be ccanus Mier bree ee 123 Flexor Tendons in the Palm.......--: The Fascie of the Upper Extremity... --.: THE JOINTS AND LIGAMENTS OF THE HAND...124 The Most Important Burse of the Upper ae i oints iz the Carpus..........---.-- 124 Extremity. .......2 282 ee eCarpal Ligaments. oi. 7 __ * Although the bilateral symmetry is not complete in the adult body, it is perfect during embryonic life. 17 18 INTRODUCTION. or to the inner or outer surface of a portion of the body; in this connection it is frequently better to substitute the word superficial for external, and deep for internal. Above and below, like all other designations, refer to the erect position of the body, and this direction may be frequently better indicated by the terms cranial and caudal. In front and behind refer to the anterior and posterior surface of the body, but this relation may be more accurately expressed by ventral and dorsal. Special additional designations are to a certain extent necessary for the extremities. In this connection, proximal means nearer to the trunk and distal more remote. In the forearm it is preferable to use the words radial and ulnar instead of outer and inner, since during prona- tion (see page 123) the inner side is directed outward and vice versa; and since the palm of the hand and the sole of the foot are designated respectively as the volar and plantar surfaces, the words volar and plantar are used to indicate the position of parts situated upon the corre- sponding surfaces. OSTEOLOGY. .GENERAL OSTEOLOGY. The greater portion of the skeleton of the human body is composed of bones, the remainder msisting of cartilages, and since the bones consist largely of lime salts they are much firmer than the cartilages, which, though hard, are nevertheless flexible. The parts of the skeleton e either paired or single, the latter being in the minority. The bones of the human body vary greatly in their form, shape, and size. The largest bone is the thigh bone or femur; the smallest are the sesamoid bones of the hand and the auditory ossicles. According to form, we usually distinguish between long or tubular bones, broad or 7 bones, and short bones, while bones possessing air-containing cavities are also called pneu- matic bones. _ The long bones have in general a cylindrical shape and are found only in the extremities. \ Wi th few exceptions, they consist of a middle portion or shajt (diaphysis) and of two ends or ext: ctremities (epiphyses*): The shaft contains a cavity, the medullary cavity, which is filled with bone-marrow, and it is on this account that these bones are also termed parses bones. The oe substance of their shaft surrounds this medullary cavity and, on account of its firm structure, is known as the compact substance, in contradistinction to a less dense spongy substance, which consists of a fine network and forms the greater portion of the extremities of the bones with the exception of a very thin outer compact layer of cortical substance. The long bones of the human body are found only in the skeleton of the extremities. They are as follows: the clavicle, the humerus, the radius, the ulna, the five metacarpal bones, the bones of the fingers and toes, the femur, the tibia, the fibula, and the metatarsal bones. The ribs are classified with the flat bones. The broad or flat bones are markedly flattened in one direction and have the shape of t or curved plates. Their central portion consists of spongy bone, the cortex being formed, ver, by a more or less thick layer of compact cortical substance. In many instances they rovided with well-marked processes. In the flat bones of the skull the spongiosa is known e diploé, while the layers of compact substance are designated as the outer and inner vitreous The flat bones of the human body are: the sternum, the scapula, the innominate bones, ibs, and many of the cranial bones. rhe short bones have an irregular form and no one of their diameters greatly exceeds the thers. They consist almost entirely of spongy tissue, their compact cortical layer being fre- ently very thin. They are frequently associated in groups, as in the carpus and tarsus. The ? Phe terms epiphyses and extremities are not, as a rule, synonymous, since the portions of the bones designated extremities usually contain portions of the diaphysis as well. 4 : 19 20 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. most important short bones of the human body are: the true vertebre, the carpal bones, the tarsal bones, the patella, and the sesamoid bones. In addition to the long, flat, and short bones there are a number which cannot be classified in any of the three categories. These are designated as irregular bones; as a rule, they repre- sent transition forms between the broad and flat bones, as in the cases of the sacrum and of many of the cranial bones. Among the latter there are also some—for example, the temporal bone and the occipital bone—which in a portion of their extent are typical flat bones, while in their remaining portions they would be regarded as belonging to the group of the short or irreg- ular bones. All the varieties of bones may possess prominences which take the form of projections, ridges, and processes of the most varied shapes. According to their size and form, they are designated as tubercles, tuberosities (rough, more or less pronounced projections), spines, crests (rough lines or projecting ridges), processes, condyles (also termed condyloid or articular processes), epicondyles (i. €., projections situated above the condyles), and outgrowths (apophyses). In a similar manner many bones possess excavations (fovee or joss@), impressions, grooves, furrows (sulci), notches (incisure), perforations (joramina), slits (hiatus), and canals. The enlarged rounded ends, particularly of the long bones, are frequently called heads, while the constriction situated beneath them is known as the neck. All bones possess larger or smaller foramina for the entrance of the nourishing blood-vessels; these are known as the nutrient foramina, and are particularly large in the shafts of the larger long bones, where they lead into a nutrient canal, which extends into the medullary cavity. The bones of the human body are usually studied in the macerated condition, 7. e., after their soft parts have been removed by putrefaction. The bones of the living body and of the dead subject, however, consist not only of bony substance, but also of a series of soft tissues, some of which partly resist putrefaction, so that the “entire bone” is composed of the following constituents: (1) The actual bony tissue; (2) the periosteum; (3) the articular cartilage; (4) the bone-marrow; and (5) the nutrient vessels and nerves. The macerated bone represents not only the bone-ash, 7. e., the calcium salts of the bone, but also contains other organic constituents. The bone substance consists chemically of almost two-thirds inorganic, and of a little more than one-third organic material; the latter is chiefly gelatin or ossein, and may be demonstrated in the form of the so-called bone-cartilage by extracting the calcium salts with acids. The inorganic constituents of bone are, calcium carbonate (about 85.5 per cent.), calcium phosphate (about 9 per cent.), calcium fluoride (about 3.5 per cent.), and magnesium phosphate (about 1.75 per cent.), and may be demonstrated by heating the dried bone to incandescence. Both the bone cartilage and the calcined bone retain the original shape of the bone from which they were obtained, the organic and the inorganic constituents being intimately intermingled. The actual bony tissue appears in two modifications, which pass into each other, how- ever, without demarcation, the compact substance and the spongy substance. The former has . a dense and apparently quite uniform structure, while the spongy substance consists of a fine network of bony trabecule, which at first sight seem to be without definite arrangement. In reality, however, the architecture of the spongy substance is by no means irregular. Its parts are arranged in such a manner as to produce a firm and resistent structure with the greatest possible saving in weight, and a careful examination of its trabecule and plates will GENERAL OSTEOLOGY. 2! a show that they are placed so as to lie in the direction of the greatest pressure or muscular trac- exerted upon the bone, and every bone or part of a bone formed of spongy substance con- fains, consequently, several intersecting systems of trabecula: which cross each other mostly at = angles (Figs. 167 to 171). ~ Almost nowhere in the body do we find bony tissue uncovered, as it is enveloped either by articular cartilage or by periosteum. Articular cartilage covers the ends of two bones form- a joint, as in the extremities of most of the long bones; the remainder of the bone is enveloped periosteum, a fibrous connective-tissue structure of varying thickness, which is of great im- p portance for the nourishment, growth, and regeneration of the bone. Articular cartilage is 1arc but elastic, and consists of the so-called hyaline cartilage. Its thickness varies greatly in different bones, being sometimes only the fraction of a millimeter or in other cases amounting to several millimeters. (For the more minute structure of bone, periosteum, articular cartilage, and bone-marrow, see Sobotta’s “ Histology,”’ Saunders’ “ Medical Hand Atlases.” ) The bone-marrow appears in two varicties, the red and the yellow. The yellow marrow ‘is really fat tissue, and is found in the medullary cavity of the long bones of the adult, while in young individuals these spaces are filled by red marrow, a soft vascular structure, which is 0 situated in the finer medullary spaces of the adult bone between the spongy trabecule. The vessels nourishing the bone are found chiefly in the medullary cavity and periosteum, but they also occur in the bony tissue itself. The nerves, on the contrary, are found principally F n the periosteum, the bony tissue having no nerves, and the articular cartilage neither nerves In certain regions of the human body, even in the adult condition, portions of the skeleton are formed by cartilage, as at the anterior extremities of the ribs, and since cartilage is clastic and flexible, it plays quite a different functional réle from that of bone. These cartilages are enveloped by a connective-tissue covering, the perichondrium. With reference to the development of bone, two varicties of bone formation are recognizable. The great majority of the bones are laid down in cartilage at a certain stage of fetal development, and these bones, which are thus preformed in cartilage, stand in contrast with those which are formed by the direct ossification of connective tissue, the so-~ ae te" el for as labyrels of r ‘ eo, = | | Pati at lst: / a. p> . 7 : Fic. 1.—A vertebra seen from above. Fic. 2.—A vertebra seen from the side cates with the spinal canal. The superior intervertebral notch is usually the shallower; the inferior one the deeper. 5 The processes of the vertebr consist of the articular processes (Fig. 2), for the purpose f articulation with neighboring vertebra, and the spinous (Fig. 2) and transverse processes ‘ 1), which serve as points of attachment for the muscles. Every typical vertebra possesses ur articular processes, two superior and two inferior, and these bear articular surfaces which ay * * . . . . are correspondingly named. Of the remaining processes, the spinous process is single, while the transverse processes are paired. Ww THE CERVICAL VERTEBR. - Of the seven cervical vertebra, the two uppermost ones, the first or aélas, and the second axis (epistropheus), show marked deviations from the type. They are also known as “ rota- y”’ vertebre, in contradistinction to the remaining vertebre (flexion vertebre). The general characters of the cervical vertebre (Figs. 4, 5, and 6) are as follows: The _ | A 7 7 a 24 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 4.—The cervical vertebra seen from behind and partly from the side (#). Fic. 5.—The fifth cervical vertebra seen from above (4). Fic. 6.—The seventh cervical vertebra seen from above (+). Fic. 7.—The atlas seen from above (4). Fic. 8.—The axis seen from above (4). bodies are relatively small, low, oblong (or quadrilateral with rounded corners), and they in- crease in size from above downward. The bodies are smaller than in any other region of the spine, and their upper surfaces are concave from side to side and slightly convex from before backward, while the lower surfaces are concave from before backward and slightly convex from side to side. As a consequence of this, the upper surface of every vertebra projects laterally beyond the body of the vertebra next above (Figs. 3 and 4). The arches of the cervical vertebre (Fig. 5) are of medium height and arise by a pedicle which is directed outward and backward. ‘Together with the body, the arch surrounds a spinal foramen which is very wide, especially in its transverse diameter. The articular processes (with the ex- ception of those of the upper two vertebre) are placed obliquely, so that the plane of the articu- lation passes from above downward and from before backward, and the articular surfaces are consequently in a middle position between a hori- Zaps zontal and a frontal plane, those nearer the skull aid approaching the horizontal position, and those BiG: Gag -crvical vertebre: seen inocu fronts nearer the thoracic vertebre the frontal plane. The transverse processes (Figs. 5 and 6) of all the cervical vertebre are perforated by a large round foramen (joramen iransversarium), a peculiarity which distinguishes the cervical from all other vertebra. Furthermore, the ends of the transverse processes are prolonged into two tubercles separated by a groove (sulcus nervi spinalis) (Fig. 5), situated upon the surface of the transverse process. The anterior root of the transversé process, which passes directly outward from the body of the vertebra and is separated from the posterior root by the foramen transversarium, the sulcus nervi spinalis, and the constriction between the two tubercles, is known as the costal process (processus costarius), and represents a rudimentary rib adherent to the true transverse process which is represented by the posterior root. This costal process is occasionally independent, especially in the seventh cervical vertebra, and forms then a cervical rib. The spinous processes (Figs. 4 and 5) are for the most part small, somewhat downwardly inclined, and distinctly bifid at their apices. From the third to the sixth the cervical vertebra are typical. The seventh (Fig. 6) is dis- tinguished by possessing a long spinous process which is not bifid and is directed downward, Odontoid process Crroove for - j ; 4 Vertebral artery 2. Superior articala r t (proc j Second cervical -.---- vertebra Groove for spinal nerve foramen Irensverse process transversarium Body Posterior tubercle of Fig. 5. Seventh cervical rr. we © vertebra } Superior articular facet (process) Odontoid process (anterior articular facet) y Superior articular facet Transverse Posterior tubercle process Groove for vericbral artery Inferior Body ; articular Superior Sacet articular Jacet Fig. 8. Transverse process oramen transversariun ~ 7a For Fig. 7. Lateral mass Facet for odontoid process Anterior taberce THE VERTEBRAL COLUMN. 25 and in these respects the form of the vertebra approaches that of the thoracic vertebre. Its spinous process is the uppermost one discoverable by palpation, and the bone is therefore also x known as the vertebra prominens. The anterior tubercle of its transverse process is either “a entirely or almost entirely absent, and the foramen transversarium js usually smaller than in the other cervical vertebre. Ls The first cervical vertebra, or atlas (Figs. 4 and 7), is characterized by a series of negative peculiarities. The body is absent, but in its place we find an anterior arch, opposite the custo- _ me posterior arch which the bone also possesses. The spinous process is also wanting, its place being taken by a prominence known as the posterior tubercle, corresponding to which there is an anterior tubercle upon the anterior arch. Finally, instead of articular processes, Pit possesses two upper and two lower articulating surfaces, and both the superior and the inferior ~ vyertebral notches are absent. In the atlas there are distinguishable therefore an anterior arch, a posterior arch, and the connecting /ateral masses, which are the strongest portions of the bone. The anterior arch is e shorter and weaker but higher than the posterior one; anteriorly (ventrally) it presents a slight projection, the anterior tubercle; posteriorly (dorsally, 7. ¢., toward the spinal canal) a round shallow articular surface (jovea articularis dentis), for articulation with the odontoid process or dens of the axis (the second cervical vertebra). The posterior arch of the atlas bears upon its posterior surface a short projection, the pos- _ terior tubercle, a rudiment of the spinous process, and is the lowest of all the arches of the cervical’ vertebra (and in fact of all the vertebrae). It is flat and broad, however, and presents _ upon its upper surface near the pedicle a furrow which is sometimes shallow and sometimes broad and deep, and which is occupied by the vertebral artery. This groove is not infrequently bridged over and converted into a foramen or short canal with a rough inner margin. The inner portion of each lateral mass of the atlas (tuberositas allantis) projects markedly into the anterior part of the spinal canal, so that the latter is converted into a smaller anterior compartment, for the reception of the odontoid process of the axis, and a larger posterior com- partment. This posterior compartment is really the spinal foramen and contains the spinal cord. Upon the upper surfaces of the lateral masses are the upper articular surfaces for the eption of the occipital condyles. These surfaces are bean-shaped and, corresponding tc the convexity of the condyles, they are concave from anteriorly and within to posteriorly and without. In the middle they are constricted and occasionally divided. On the under rface of the lateral masses are found the inferior articular surfaces which serve for articulation with the second cervical vertebra and resemble the similar surfaces of the other vertebre more ‘thi an do the superior articular surfaces, possessing plane, but slightly inclined (almost horizontal) - Surfaces. _ The transverse processes exhibit the same characteristics as the transverse processes of a he cervical vertebre, but are larger. Like the others, each possesses a foramen transver- rium, but the sulcus nervi spinalis and the tubercles are absent. ‘The second cervical vertebra (Figs. 4 and 8), or axis («pistropheus), so called because the ut and the atlas rotate upon it, is on the whole a typical cervical vertebra, except that its adherent to it the original body of the atlas, which forms the odontoid process (dens 26 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 9.—The tenth to the twelfth thoracic and the first and second lumbar vertebre seen from the side and slightly from behind (3). Fic. 10.—The tenth thoracic vertebra from above (+). Fic. 11.—The sixth thoracic vertebra from the side (4). Fic. 12.—The third lumbar vertebra seen from above (4). epistrophet) and projects into the anterior compartment of the spinal foramen of the atlas. This odontoid process is cone-shaped with a rounded apex, and presents an anterior facet for articu- lation with the anterior arch of the atlas and a posterior articular facet which is not always dis- tinct. Instead of articular processes the upper part of the body presents corresponding articular surfaces for connection with the atlas; these surfaces are slightly convex and but a trifle inclined from the horizontal. The spinous process (Fig. 4) is fairly well developed and always distinctly bifid; the trans- verse processes, on the contrary, are smaller than those of the atlas and their tubercles and sulci nervi spinalis are likewise absent, although there is usually a shallow groove for the second spinal nerve on each side behind the superior articular facet. The inferior articular processes are more inclined than the superior ones, and already show the characteristics of those of the flexion vertebre. The foramina transversaria of the articulated cervical vertebra form a canal for the passage of the vertebral artery and vein (the former runs through the upper six only). The markedly developed anterior tubercle of the transverse pro- cess of the sixth cervical vertebra is known as the carotid tubercle or tubercle of Chassaignac (tuberculum caroticum). THE THORACIC VERTEBR&. On account of the independent development of the ribs in the thoracic region, we find no fused costal rudiments in the thoracic vertebra such as occur throughout the remainder of the true vertebra, and the thoracic vertebrae are consequently of the purest type. Their bodies (Figs. 9, 10, 11, and 21) increase in size and height from above downward. In the upper thoracic vertebre their surfaces are elliptical, like those of the cervical region, but as we pass downward they become rounder, then cordiform, and finally reniform in the lower members of the series, which approximate the form of the lumbar vertebre. And not only do the bodies become larger, but their lateral diameter especially is increased as they gradu- ally approach the form of the lumbar vertebre. Their contiguous surfaces are almost per- fectly flat. The spinal foramen (Fig. ro) is not only absolutely, but even relatively smaller than that of the cervical vertebra, and in the upper members of the series it is rounded, while in the lower ones it is rather triangular. The upper and lower margins of the bodies each present, immediately in front of the pedicles, a demifacet for the head of a rib (Fig. 11). The first and the two (or three) lowest vertebra, however, show deviations from this arrangement, the former having an entire facet upon the upper margin, and each of the latter (Fig. 9) presenting an entire facet toward the middle of the body of the vertebra. The articular surfaces for the heads of the ribs are placed on two adjacent thoracic vertebre in such a manner that each vertebral margin does not receive exactly one-half of the articulation, but toward the lower end of the series more than half and then two-thirds of the entire surface occurs upon the lower vertebra until the eleventh, and occasion- Facet for head of rib Tenth thoracic vertebra Twelfth thoracic vertebra first lumbar vertebra Transverse process \ Yo Accessory process Fig. 9. al THE VERTEBRAL COLUMN. 27 __ally the tenth also, possesses an entire costal facet (Fig. 23). ‘Those vertebre which possess an entire facet have typically no inferior facet. i - The arches of the thoracic vertebra (Fig. 10) are high and thick. The articular processes, with the exception of those of the twelfth vertebra, lie almost in the frontal plane and are placed a the almost round and slightly concave inferior surfaces look forward, while the slightly convex superior ones look backward, the surfaces forming part of a thick cylinder the axis of which lies in front of the vertebral body. The superior processes are very prominent, while the inferior ones project but slightly. The long transverse processes (Fig. 10) are strongly developed. They are directed back- ward as well as outward, and have thickened club-shaped extremities. The anterior surface of this thickening usually presents an approximately circular, slightly concave articular facet, for the accommodation of the tubercle of a rib; this facet is wanting, however, in the eleventh a nd twelfth vertebra (Fig. 9), and the transverse process of the latter often shows a variable development, frequently consisting of several irregular tubercles. a _ The spinous processes (Figs. 9, 10, and 23) are long and three-sided, and are directed ob- -liquely downward, one border looking upward and one surface downward. Those of the middle vertebrae of the series overlap each other like the shingles of a roof (Fig. 23). That of the twelfth vertebra (Fig. 9) resembles those of the lumbar vertebre. The twelfth thoracic vertebra (and sometimes the eleventh also) is the only one that can be designated as atypical, since it exhibits several characteristics of the lumbar vertebr# (the shape of the spinous process, body, and spinal foramen, the position of the articular processes and the appearance of the accessory and mammillary processes upon the radi- mentary transverse processes). The facet for the head of the rib alone shows the truc nature of the twelfth thoracic vertebra, just as the facets upon the bodies (and transverse processes) are the surest points of identification for the thoracic vertebre in general ’ THE LUMBAR VERTEBR. _ The lumbar vertebre (Figs. 9, 12, 21, and 23) are the largest of the true vertebre. The Q, 12, mS bod ies in particular are large, very high and broad, and have plane reniform surfaces, #. ¢., they are convex anteriorly and concave posteriorly. The anterior surface is distinctly concave f m above downward and convex from side to side, so that the upper and lower surfaces of bodies are considerably broader than their middle portions. Also the bodies of the lower umbar vertebra at least (and especially of the fifth) are distinctly higher anteriorly than pos- terior r (Fig. 23). The arches of the lumbar vertebra (Fig. 12) are strongly developed and very high, but -no further peculiarities; the spinal foramina are small and approximately triangular. r surfaces looking backward and inward while the convexity of the lower ones is directed ird and outward. The surfaces represent sections of a lange hollow cylinder, whose axis uat ed, not in front of the vertebral bodies, as in the thoracic region, but behind them (behind e sp inous process), and the inferior processes of each vertebra are consequently overlapped illy by the superior processes of the next succeeding one. The inferior processes of the tebra are united with the upper articular processes of the sacrum (see page 29). 28 ATLAS AND TEXT-BOOK. OF HUMAN ANATOMY. Fic. 13.—The sacrum seen from behind (dorsal surface) (#). Fic. 14.—The sacrum seen from in front (pelvic surface) (#). Fic. 15.—The sacrum seen from above (base) (#). Fic. 16.—Horizontal section of the sacrum at the level of the second sacral foramina (#). Fic. 17.—Median longitudinal section through a sacrum, showing the synchondroses between the indi- vidual vertebre (#). Fic. 18.—The sacrum and coccyx seen from the side (3). Fic. 19.—-The coccyx seen from in front (+). Fic. 20.—The coccyx seen from behind (+). The transverse processes of the lumbar vertebre (Fig. 12) are long, directed almost at a right angle from the spinal column, and distinctly compressed from before backward. They represent rudimentary lumbar ribs and are therefore really the costal processes,* while a small projection situated at the base of the ‘transverse process,” the accessory process (Figs. 9 and 12), corresponds to the transverse process of the thoracic vertebra. This accessory process is characteristic for the lumbar vertebra, and although sometimes poorly marked, it usually ap- pears even in the twelfth thoracic vertebra. The superior articular processes of the lumbar vertebre also exhibit another round roughened protuberance, the mammullary process (Figs. g and 12). The spinous processes (Figs. 9 and 12) are very strong and high and are distinctly com- pressed from side to side. They extend directly backward and show a slight thickening at their apices. THE FALSE VERTEBRZ. The false vertebra, which are variable in number, form two bones, the sacrum and the coccyx. THE SACRUM. : The sacrum is that portion of the vertebral column which is connected with the pelvic girdle and completes the latter posteriorly; it consequently forms a portion of the pelvis itself. It is a broad, curved, moderately flat, shovel-shaped bone (Figs. 13 and 14), which is broad and thick above, and narrow and thin below (Fig. 18). In it there may be distinguished an anterior relatively smooth surface, concave in both the sagittal and transverse directions, and known as pelvic surface, because it looks toward the pelvic cavity, and a posterior extremely rough dorsal surface. The broad upper surface of the sacrum is called the base and the lower angle the apex. The pelvic surface presents a number of transverse ridges, usually four, which connect four pairs of irregular rounded foramina known as the anterior sacral foramina. The ridges correspond to the junctions of the five originally separate sacral vertebrae of which the bone is composed, while the sacral foramina indicate the junctions of the bodies with the lateral pro- cesses (costal and transverse processes). The anterior sacral foramina communicate pos- * These processes occasionally form so-called abdominal or lumbar ribs. Sacral Trans tubero- verse sity lines Lateral ar sacral crest Anterior s sacral Articular foramina Median sacral sacral crest crest osterior sacral foramina Median sacral crest Articular sacral {nex . Apex Of Sacrum “* Fig. 13. Apex of sacrum crest q Sarval f Fig. 14. io - AS ¢ a3 7 = 7 a A iy 7 . - _ downward and from without inward), the third is exactly horizontal, and from the fourth yward there is an increasing inclination from below upward and from without inward (Fig. "The cartilages of the sixth to the tenth ribs are often quite broad and articulate with each by variously formed processes passing upward and downward; they form synchondroses usually the case, diarthroses, and by their union there is formed an arch-like lower he thorax, the costal arch. 24 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 29.—The eleventh rib of the right side seen from behind (3). Fic. 30.—The twelfth rib of the right side seen from behind (3). Fic. 31.—The sternum seen from in front (4). Fic. 32.—The sternum seen from the left side (4). THE STERNUM. The breast-bone, or sternum, is a single, flat, oblong bone. It lies approximately in the frontal plane and forms the middle portion of the anterior wall of the thorax, and by its articu- lation with the clavicles, it completes the shoulder girdle anteriorly. It is composed (Fig. 31) of three distinctly separated portions placed one above the other, an upper broad handle, the manubrium, a middle piece, the body or gladiolus, and a lower piece, the xiphoid process. The three portions are either separated by cartilage or are united by bone; the former condition prevails between the manubrium and the body (synchondrosis sternalis), while the latter obtains between the body and the xiphoid process. At the synchondrosis between the manubrium and the body there is usually quite an obtuse angle, open posteriorly, the angulus sterni (angle oj Louis). The sternum is not exactly in the frontal plane, but is placed somewhat obliquely, so that the upper end is considerably nearer to the vertebral column than the lower one, a rela- tion which is also partly due to the curvature of the vertebral column (see page 14). The manubrium is considerably broader than the body of the bone, and is broadest above and narrowest below; its anterior surface is slightly convex, and the posterior surface slightly concave. The upper margin presents three rounded notches, a median shallow interclavicular or jugular notch, and two lateral deeper clavicular notches, which are covered with cartilage and accommodate the sternal ends of the clavicles. Immediately below each clavicular notch there is a notch (Fig. 32) upon the lateral margin of the sternum for the reception of the broad costal cartilage of the first rib, which is joined to the sternum in this situation by a synchon- drosis, and each side of the lower end of the manubrium presents a demifacet, for articulation with the cartilage of the second rib. The body is usually narrowest above, gradually widening as it descends, until it attains its greatest breadth in its lower third, and then rapidly narrowing again as it approaches the xiphoid process; it is occasionally, however, of uniform width throughout. Its nearly flat . anterior (ventral) surface is called the planum sternale, and sometimes presents transverse lines (Fig. 34) which indicate the original fusion of several parts situated one above the other. At the margins of the body (Fig. 32) are found notches for the cartilages of the six lower ‘true ribs, that for the second rib being situated at the junction of the manubrium and the body, that for the sixth rib on the lower margin of the body, and that for the seventh in the angle between the body and the xiphoid process. The notches for the fifth, sixth, and seventh ribs lie close together, and the fourth notch is situated below the middle of the entire bone. The xiphoid process varies greatly in shape and size. It is always markedly narrower than the body, often partly or even wholly cartilaginous, and it is sometimes perforated. The female sternum is usually shorter and broader than that of the male. Fig. 30. Jugular notch Clavicular notch .) Clavicular notch Notch for first rib Notch for first nb Manubrium Manubrium Notch for second rib Notch for second rib Notch for third rib Notch for third rib Body of sternum Notch for B : ody of sternum fourth rib “i Notch for fourth rib Nth ns Notch for fifth rib Notch for sixth pi Notch for sixth rib Notch for Notch for seventh rib seventh rib Xiphoid process Xiphoid process Fig. 31. Fig. 32 a ee - —- Vie = - —S — a _ THE THORAX. 35 THE THORAX. The thorax (Figs. 32 to 36) is formed by the twelve thoracic vertebre, the owelve pairs of ribs, and the sternum, and is an approximately conical cavity, wide open above and below, and with the apex directed upward. Init there may be recognized an upper opening and a much larger lower one. The superior _ thoracic aperture is formed by the first thoracic vertebra, the first rib, and the upper margin of the manubrium. Like the cross-section of the thorax, it is reniform in shape (on account q e of the projecting vertebral bodies), and is placed not horizontally but obliquely, being directed - downward and forward so that at the end of expiration, the upper margin of the sternum usually corresponds to the junction of the second and third thoracic vertebra. The inferior aperture is of very irregular form on account of the notch situated between ~ the costal margins and the lower end of the sternum. It is bounded posteriorly by the twelfth - thoracic vertebra, by the twelfth and then by the cleventh rib, and anteriorly by the costal mar- ; \ gins and the xiphoid process of the sternum. The angle between the costal margin and the _ xiphoid | process is known as the subcostal or injrasternal angle. The anterior wall of the thorax, formed by the sternum and the costal cartilages, is con- . siderably shorter than the posterior one, formed by the vertebral column. Above the difference _ amounts to the height of two entire vertebra, while below it is usually (according to the an of the xiphoid process) equal to three, since the lower end of the xiphoid process ordinarily is i opposite the ninth thoracic vertebra. The lateral wall formed by the ribs is still longer than - the posterior one (Fig. 35), the lower margin of the twelfth rib extending downward to the level ‘of the second lumbai vertebra. On either side of the bodies of the vertebre, which project ee into the thoracic cavity, there is a broad groove, the pulmonary groove. The trans- verse or frontal diameter of the thorax is considerably larger than the sagittal or sterno- tebral one. “The spaces situated between the ribs are known as the intercostal spaces, and are cleven in number, the lowermost one, that between the eleventh and twelfth ribs, being very short. . air direction naturally corresponds exactly to that of the adjacent ribs, but they are con- i. __ siderably wider than these structures, especially in front between the cartilages. 7 4 . THE DEVELOPMENT OF THE RIBS AND OF THE STERNUM. The ossification of the ribs takes place chiefly from a center which appears in the body of the rib simultancously with the centers of the vertebra. Some time after puberty epiphyseal centers appear for the beads and tubercles, and a do not fuse with the main portion of the bone until after the twenty. fifth year. The manubrium of the sternum is usually formed from a single nucleus, while the body is developed from a num- ber of nuclei (four to thirteen), which are frequently arranged in two more or less distinct longitudinal rows. As a rule, ther ere is but one center for the xiphoid process, Ossification of the sternum docs not begin until the fourth or sixth month of embryonic life, and in the xiphoid process not until from the sixth to the twenticth year. VARIATIONS IN THE SKELETON OF THE TRUNK. Supernumerary vertebrx are sometimes present, particularly in the lower portion of the vertebral column (sacrum, vertebre). Not infrequently ribs are formed from the costal processes of the seventh cervical and of the last r vertebra, and are designated as cervical and lumbar ribs respectively. The last lumbar vertebra sometimes 36 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 33.—The thorax together with the left shoulder girdle, seen from behind (4). Fic. 34.—The thorax together with the left shoulder girdle, seen from in front (4). Fic. 35.—The skeleton of the trunk, divided by a medium longitudinal section, together with the shoulder and pelvic girdles, seen from the left side (4). Fic. 36.—The skeleton of the trunk, divided by a median longitudinal section, together with the shoulder and pelvic girdles, seen from the median line (4). develops a broad mass which unites with the sacrum and is to be regarded as a sacral rib (lumbosacral vertebra, see page 30), and the posterior arch of the atlas and the portions representing the arches of the sacral vertebre sometimes fail to ossify, so that the spinal canal remains open posteriorly (rhachischisis). The ribs frequently fork near the costochondral articulations, the two portions so formed usually uniting again, so that a fenestration of the rib is produced. Foramina are not rare in the sternum and one is frequently found in the xiphoid process. At the upper end of the manubrium, at the sides of the interclavicular notch, two small bones which are termed epis/ernal bones occasionally occur. THE SKELETON: OF THE HEAD. The sum total of the bones of the head is designated as the skw/l or cranium, and this por- tion of the skeleton differs from the others in that all of its constituents, with the exception of the lower jaw, are firmly united even in the macerated condition (the exact nature of the union is described under ‘‘Syndesmology,” page 107), so that special means are required to separate the individual bones from each other, and such a separation is not usually successful if the indi- vidual is too old. A skull the bones of which have been isolated, is known as a disarticulated skull. The completely formed adult skull is an extremely complicated structure, some of the individual parts being united in such a manner that it is quite difficult to recognize them. Some bones, indeed, are scarcely visible in the perfect skull, owing to the fact that they are to a great extent covered or overlapped by the other cranial bones. Before describing the individual cranial bones it will be advantageous to consider briefly the skull as a whole, in order to obtain an idea of the topography of the individual cranial bones and of their chief component parts. The skull will therefore be studied first from in front, then from the side, from below (without the inferior maxilla), and from above, looking downward upon the great cranial cavity which encloses the brain, and finally the outer and inner aspects of the cranial vault will be considered. THE ANTERIOR ASPECT OF THE SKULL. If the anterior aspect of the skull (Figs. 37 and 38) be examined, it will-be seen that the bony forehead (jrons) is formed by the vertical portion of the jrontal bone, and that toward the vertex a slightly serrated suture, the coronal suture, separates the vertical plate of the frontal from the two parietal bones. The frontal bone also forms the upper margin of the orbit, and at the outer margin of the orbit it is separated from the contiguous zygomatic or malar bone by a suture, the zygomatico-jrontal suture. The process of the frontal bone articulating with the zygomatic bone in this situation is known as the external angular or zygomatic process. To either side of the frontal bone will be observed the anterior inferior or sphenoidal angle of the ; Sixth cervical vertebra hirst thoracte vertebra tag? ) First rib First rib my = First thoracic vertebra Clavicle leromion \ — Clavicle Second rib r ve ' Coracold Process SCUpula Y Gilenold cavity cf scapula Fourth rib Sixth rib Seventh rib Eleventh rth Twelfth thoracic vertebra Twelfth nb First lumbar vertebra Twelfth rib C lumbar : vertebra Twelfth thoracic vertebra Eleventh rib Fie. 33. Fig. 34. Clavicle Ama Seventh oh = : cervical vertebra a .=* ‘Le Seventh ) first thoraac ~x ei gssnie ; Z 7 { rlolr vertebra or “ cervical vertrora = =~ a Scapula Humerus Second rib Eleventh rib Twelfth rib First lumbar vertebra Ri, we i Eleventh rib Twelfth nib First lambar vertebra Antorior superior spine of iam Fig. 30. Coceyx Sacrum Symphysis pubis Tuberosity of ischium Spine of ischium THE LATERAL ASPECT OF THE SKULL. 37 parietal bone, which is separated from the greater wing of the sphenoid hone by the 5 pheno- _ parietal suture. A portion of the tem poral bone is also visible on the anterior aspect of the skull. | Below the vertical plate of the frontal bone are the large orbital cavities, the greater portion of whose roofs are formed by the orbital plates of the frontal bone, which articulate with the orbital surface of the greater wings of the sphenoids, the intervening suture being the spheno- / ontal suture; they are separated from the lesser wing of the sphenoids by the superior orbital fissure (sphenoidal jissure). The sphenozygomatic suture is situated in the outer wall of the orbit between the greater wing of the sphenoid and the zygomatic bone, the latter forming a part of the outer wall of the orbit, as well as the outer and a portion of the lower margin of the orbit. The bony bridge of the nose is placed between the two orbital cavities, and in this situation e frontal bone articulates on cither side with three bones which, from within outward, are the ‘nasal bone, the nasal or jrontal process of the maxilla, and the lachrymal bone. The inter- _yening sutures are called the nasojrontal, the jrontomaxillary, and the jrontolachrymal sutures. __ The two nasal bones, which form the main portion of the bony bridge of the nose, are sep- arated from each other by the internasal suture, and from the nasal process of the maxilla by the 2 masomaxillary suture. They form the upper boundary of the anterior nares (apertura piri- jon mis), which are bounded throughout the rest of their circumference by the two mawxille. a two bones are separated in the median line by the intermaxillary suture, and the frontal or nasal process of each is separated from the corresponding nasal bone by the nasomaxillary . cut ure, and borders externally upon the lachrymal bone (for a detailed description see the orbital Cavity, page 73). The maxilla also forms the inner half of the floor of the orbit and of the erior orbital margin, the injerior orbital (sphenomaxillary) fissure, in the floor of the orbit separating the maxilla from the greater wing of the sphenoid. Below the inferior orbital margin, in the body of the maxilla, is the injraerbital joramen, and in the anterior nares can be scen the bony nasal sepium,* and also the nasal conchae (turbin- al bones), particularly the inferior ones, which project from the outer wall of the nasal fossa. 1e junction of the intermaxillary suture with the lower margins of the anterior nares there bony spine, the anterior nasal spine. The zygomaticomanillary suture separates the maxilla fr n the zygomatic bone, whose malar surface is visible in the anterior view of the skull. The lower portion of the maxilla forms the tooth-bearing alveolar process. _ Finally there is the mandible or lower jaw. Its middle portion or body presents a foramen, he » joramen, and the tooth-bearing alveolar portion; to either side (and somewhat fore- Biot tence in the figure) the ramus. : THE LATERAL ASPECT OF THE SKULL. The lateral aspect of the skull (Figs. 39 and 40) contains a number of bones which have eer en already considered in the description of the anterior cranial region. Above and anteriorly serve that the frontal bone is separated from the parictal bone by the coronal suture, and the greater wing of the sphenoid by the sphenojronial suture. The zygomaticojrontal ‘ separates the zygomatic process of the frontal bone from the jrontosphenoidal —_ * The anterior portion of the nasal septum is cartilaginous. 38 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. of the zygomatic bone, and the temporal ridge commences at the zygomatic process of the frontal bone and passes backward in a curved manner over the frontal and parietal bones. Behind the frontal bone is seen almost the entire parietal bone. It is limited anteriorly by the coronal suture and is separated from the occipital bone posteriorly by the /ambdoid suture. Its lower border articulates with the greater wing of the sphenoid by the sphenoparietal suture, with the squamous portion of the temporal bone by the squamosal suture, and with the mastoid portion of the temporal bone by the parietomastoid suture. The only portion of the occipital bone visible in the lateral view of the skull is its squamous portion, which is separated from the mastoid process of the temporal bone by the occtpitomastoid suture. : Below the frontal and parietal bones, the temporal surface of the greater wing of the sphenoid is visible. It is separated from the zygomatic bone anteriorly by the sphenozygomatic suture, and from the squamous portion of the temporal bone posteriorly by the sphenosquamosal suture. The first portion of the temporal bone to attract attention in the lateral aspect of the skull is the squamous portion, from which a long process, the zygomatic process, passes almost hori- zontally forward to articulate with the short temporal process of the zygomatic bone by the zygomatico-tem poral suture; the two processes together forming the zygoma or zygomatic arch. The origin of the zygomatic process of the temporal bone marks the termination of the inferior temporal line as it passes from the parietal to the temporal bone. Below the inferior temporal line there is upon the lateral surface of the skull a slightly depressed area, the planum temporale, formed by the temporal and parietal bones, the greater wing of the sphenoid, and a small portion of the frontal bone. In the zygomatic region the planum temporale deepens into the temporal fossa. The portion of the temporal line situated upon the temporal bone forms approximately the anterior boundary of a second portion of the temporal bone visible in the lateral view of the skull, the mastoid portion, which derives its name from a strong conical protuberance, the mastoid process. A third portion of the temporal bone to be seen in the lateral cranial region is the tympanic portion, and is situated immediately below the root of the zygoma, forming the outer and lower circumference of the large opening of the bony external auditory meatus (meatus acusticus externus). In looking at the skull from the side, the malar surface of the zygomatic bone is directed toward the observer. In the lateral aspect of the maxilla there may be observed (as in the anterior view) the anterior nasal spine, the frontal process, the nasomaxillary suture by which it articulates with the nasal bones, and the alveolar process, which is directed toward the simi- larly named portion of the mandible. In the lower jaw we see the body with the mental foramen, and almost at right angles with the body, the ramus, the upper portion of which is divided by a deep notch, the sigmoid notch, into two processes, the coronoid and the condyloid processes. The articular surface of the condyloid process rests in a fossa of the temporal bone situated below the root of the zygoma, the mandibular or glenoid jossa. 37. Fig. “= internasal coronal frontal process of maxilla S#ure masofrontal suture lachrymomaxillary suture Jrontomaxillary suture sphenofrontal suture orbital surface of orbital plate supraorbital margin of frontal bone lachrymal bone sphenofrontal sulure sphenoparictal Sulure parietal bone (Sphenoidal angle) ~~~ greater wing of sphenoid (temporal surface) zygomatic process aon ; temporal bone orbital plate of — ~~~ © : frontal bone “n> sphenoidal fissure zygomatico-frontal Suture ” sphenozygomatic inferior orbital suture Jissure nasomaxillary Sulure “maxillary nasal bone poor cag nasal septum infraorbital foramen alveolar process ramus of mandible of superior maxilla wn ; inferior tarbinat, Ss. (body). aX Ste —o ed bone A . ST 2 we we yy anterior nasal spine WY Age RS - 2Pe . mental foramen intermaxillary suture Fig. 38. Figs. 37 and 38. The skull seen from in front (‘’s). In fig. 38 the frontal bone is violet, the maxilla yellow, the sphenoid green, the parietals brown, the lachrymals and vomer pink, the ethmoid orange, the zygomatic pink streaked, the mandible blue streaked and the nasals and temporals white. auy posoduay soisafua ~~ ‘onyq ur [ezId1I990 ay} UOTWIppe UL pue gE “Sy Ul sv paiojoD av saUOg sNolLeA 94} HE “SH Ul ‘(o/,) Opis Ie] eyI Wosz uses [[INYs ey], ‘OP Pur HE ‘SSL “ aqqipunu uaupsof joyuau a4Njns Jododiuaj-onvuogshz fo ssavosd pyouosod aanjns proyspuojapd aunjns qosoumubsouayds oes Sb SAWN Rs ‘ anqipuu — Yad aypMosse | ainjns projspuondiz0 ; —- 4° S8204d Projspuog ! snjpau M4OJIPND [VUAIIXI ‘ 4 ever fy (uoysod snowvnbs) auog 303101990 \ —_— —— Py, | << plojsp Cae, ‘6E 1] (uoysod snouwnbs) Z auog josoduay # vl adnjns plopquiny -- aungns jvsoupnbs.— ’ aun pvsodiuay souadns: aAN]NS 7DU010I @ aimgns jojatapdouayds aingns poyuodfouayds -auids JVSDU 40149]UD _--- pyixpu fo ssavosd pojuosf “gungns sypvumosdzouayds * ganyns aynumosdzouayds Fig. 40. th : y ‘ t , - =e THE EXTERNAL SURFACE OF THE BASE OF THE SKULL. 39 THE EXTERNAL SURFACE OF THE BASE OF THE SKULL. The inferior aspect of the human skull, exposed by the removal of the lower jaw, presents an extremely irregular surface (Figs. 41 and 42), and is termed the external surface of the base of the skull, basis cranti externa, to distinguish it from the internal surface which forms the floor of the cranial cavity. Passing from before backward, there may be noticed first the bony plate of the hard palate, which is bounded externally by the alveolar process of the maxilla and the upper row of teeth. It forms the bony partition separating the oral and nasal cavities, is composed of two bones upon either side, the palatine process of the maxilla, forming its anterior two-thirds to three- quarters, while the posterior third or fourth is furnished by the horizontal portion of the palate bone. It is traversed in the median line by the median palatine suture, the anterior extremity of which contains the incisive foramen, a pit-like depression, which leads to a canal of the same name. The palate bones are separated from the palatine processes of the maxilla by the érans- verse palatine suture, and at the posterior extremity of the median palatine suture, the two bones terminate in a spine, the posterior nasal spine. The posterior free margins of the horizontal plates of the palate bones form the lower boundary of the posterior nares or choane@, the pos- terior outlets of the bony nasal foss. To the outer side of the hard palate is seen the short, broad zygomatic process of the maxilla, which articulates with the malar bone by means of the zygomaticomaxillary suture. There is also to be seen the anterior extremity of the injerior orbital or sphenomaxillary fissure between the upper jaw and the greater wing of the sphenoid bone. The zygomatic arch, formed by the junction of the zygomatic process of the temporal bone with the temporal process of the zygo- matic bone, is distinctly visible. A large portion of the external surface of the base of the skull is formed by the sphenoid bone. ‘The greater wings are almost entirely visible and are limited posteriorly and externally by the sphenosquamosal suture, their foreshortened temporal surfaces, already noticed in the lateral view of the skull, being seen to unite with the infratemporal surfaces,which are actually situated in the base of the skull, at a distinct angle marked by a rough ridge, the injratem poral crest. The posterior margin of this infratemporal surface is separated from the contiguous petrous portion of the temporal bone by the sphenopetrosal fissure, which is continuous internally with an irregular foramen, the foramen lacerum. ‘The extreme postero-external angle of the greater wing of the sphenoid, the spine, is directed toward the temporal bone, and presents a round opening, the foramen spinosum, which leads into the cranial cavity and transmits the middle meningeal artery. In front of this is a larger oval aperture, the jeramen ovale, through which the mandibular division of the trigeminal nerve emerges from the cranial cavity. In the middle of the base of the skull a part of the body of the sphenoid bone is visible between the two greater wings, but its anterior portion is partly concealed. It will be observed that the posterior margin of the bony nasal septum, which in this preparation represents the septum choanarum, is formed by the vomer, which articulates with the body of the sphenoid by means of a broad base, known as the ala vomeris. A strong process, the pterygoid process, which is divided lengthwise into two plates, projects 40 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. downward from the body of the sphenoid. The broader, larger, external plate is termed the external pterygoid plate, and the narrower internal one, the internal plerygoid plate, terminates below in a small hook-like process, the hamular process (hamulus plerygoideus). The pterygoid process of the sphenoid bone articulates in this situation with the horizontal plate of the palate bone and also with a process of this bone, its ‘wberosity (processus pyramidalis), which is directed backward and outward and fills the gap between the external and internal pterygoid plates, consequently aiding in the formation of the pterygoid fossa, which occupies the interval between the two plates. In the palate bone, at its junction with the pterygoid process of the sphenoid, there is a larger anterior foramen, the greater palatine joramen, and usually several smaller posterior openings, the lesser palatine foramina. The posterior half of the external surface of the base of the skull is formed by the two tem- poral bones and by the occipital bone. All the four portions of which the temporal bone is composed are visible, namely, the inferior surfaces of the petrous portion, of the mastoid portion, and of the tympanic portion, and a part of the squamous portion. The apex of the petrous portion lies in an irregularly shaped opening, the foramen lacerum; it is separated from the sphenoid bone anteriorly by the sphenopeirosal fissure and from the occipital bone posteriorly by the petro-occipital fissure. The mastoid portion articulates with the occipital bone by means of the occi pitomastoid suture. Of the squamous portion, one sees mainly the zygomatic process (forming a portion of the zygomatic arch) and the mandibular jossa, which accommodates the condyloid process of the mandible and presents anteriorly the articular eminence. Of the mastoid portion, there is to be seen the mastoid process (processus mastoideus), which has a deep groove, the digastric fossa (incisura mastoidea), upon its inner surface, and, at the side of the occipitomastoid suture, an opening, the mastoid joramen. The tympanic portion, with the meatus auditorius externus, is placed between the mastoid process and the mandibular fossa, and in front of it there is a fissure, the Glaserian fissure (fissura petrotympanica). There are many foramina and fossee upon the very rough and irregular lower surface of the petrous portion of the temporal bone. Slightly to the inner side and in front of the mastoid process is the pointed styloid process; between the mastoid and styloid processes there is an opening, the stylomastoid joramen; to the inner side of the styloid process there is a rather deep depression, the jugular jossa, leading into the cranial cavity through an irregular opening, the jugular joramen; and to the inner side and in front of the jugular fossa there is a round opening, the external orifice of the carotid canal. The occipital bone forms the large remaining portion of the external surface of the base of the skull. In the adult skull it is united with the sphenoid so that its basilar portion is continuous anteriorly with the body of the sphenoid bone without demarcation. Posteriorly the basdar portion forms the anterior margin of the joramen magnum, while the portions of bone external to this foramen, known as the lateral portions, present the two large occipital condyles, by means of which the skull articulates with the first cervical vertebra or atlas. The base of each condyle is perforated by a short canal, the hypoglossal or anterior condyloid canal, while the termination of a similar canal, the condyloid or posterior condyloid, is visible behind the condyle. Fig. 41. ala yvomeris incisive foramen -niedian palatine suture horizontal portion of palate 3 : bone \ ‘ : internal pterygoid plate palatine process of superior maxilla zygomatic bone (temporal surface) . ransverse palatine suture external pterygold plate ergomalic process of maxiie soma liio-maailla Sar infratemporal surface of ajgema aiilary sutare greater wing of sphenoid poutiiriers nasal spine zygomatic arch infraiemporal crest spheneosgaamesa! suture s1pomahioemporal Sphenoparietal suture swfure foramen ovaic Sphenopeiresal fissure articular eminence - a-neeeerr “* ‘ probe in hipopiessal canal mandibular priroocnipital fissure sfyloid process foramen spinosum cilrrnal aundilery meatus foramen lacerum .--+---"~ =a orifice of carotid canal _. Stylomastoid foramen - orysiomasie:d salaurt jugular fossa mastoid process mastoid groove pariciomasioid suture mastoid foramen . occipital condyle condyloid fossa . lambdoid suture foramen magnum - inferior nuchal line external occipital protuberance superior nuchal lin Fig. 42. Figs. 41 and 42. The skull seen from below, the outer surface of the base (‘/s). In fig. 42 the various bones are colored as in fig. 38 except that the occipital is vellow streaked with red and the palatines are blue. é . _ eribriform rontal ethmoidal spine plate pe foramen caecum jugum ethmoidale crista galli i> -~ fronto-ethmoidal suture : __~° sulci arteriosi ik _ olivary eminence _--° Sphenofrontal suture _- dorsum sellae ~~ coronal suture v__-- carotid groove - optic foramen -. __--~ Sphenoparietal suture \ ----~ sphenosquamosal suture _-- foramen lacerum anterior clinoid process foramen rotundum _- Squamosal suture \ r \ sulcus arteriosus ert Y foramen ovale-- mit \__\--- inferior petrosal groove Wee tt wii | P i J --petro-occipital fissure foramen spinosum_\- -hiatus Fallopit trigeminal impression ‘ jugular foramen ~sigmoid groove ---condyloid canal internal auditory meatus _- jugular foramen _- (anterior compartment) 3 oe J &---- =e “fas , ---- mastoid foramen 7 L/ fe Wp lambdoid suture ___ Hy 4 \)/ squamous | --->--transverse groove jugular tubercle remains of the spheno-occipital suture internal internal hypoglossal canal y occipital occipital synchondrosis eta prohioe rance Fig. 43. Figs. 43 and 44. The inner surface of the base of the skull (‘/s). In fig. 43 the various bones are colored as in fig. 38. ———— 73. er ¢ Cy aIee phi ag os bi — es ae sa iu {i THE INTERNAL SURFACE OF THE BASE OF THE SKULL. 41 There is further to be observed the entire nuchal surface | planum nuchale) of the squamous portion and a foreshortened portion of the planum occipitale, the boundary between the two portions being formed by a rough line, the superior nuchal, which extends central external occipital protuberance. the injerior nuchal line. laterally from the Below the upper line, the nuchal surface is crossed by THE INTERNAL SURFACE OF THE BASE OF THE SKULL. : By the internal surface of the base of the skull (Figs. 43 and 44) is understood the floor of the cranial cavity which is exposed by sawing horizontally through the bony cranium and > removing the calvarium. It is concave, and contains the so-called cranial fossx, of which there _ are recognized an anterior, 1 middle, and a posterior jossa (Fig. 45). All three fosse meet in _ a saddle-like elevation, the sella turcica, which is a portion of the body of the sphenoid bone and is situated somewhat anteriorly to the middle of the cranial cavity. The anterior cranial fossa is relatively flat. The greater portion of its floor is formed by the orbital plates of the frontal bone (Figs. 43 and 44), whose upper surfaces are directed toward the cranial cavity and are known as the cerebral surjaces. They present peculiar eleva- tions and corresponding depressions, called respectively cerebral juga and digitate im pressions, and they also present grooves for blood-vessels. The two halves of the frontal bone are sepa- rated anteriorly by a ridge, the frontal crest, which commences at a foramen, the and posteriorly the orbital plates of the frontal bone _ sphenoid by the sphenojrontal suture. Lying between the two orbital plates of the frontal bone cecum to the sphenoid bone there is a thin bony plate, characterized by being perforated by numerous foramina. It is the cribrijorm plate of the ethmoid bone, and it presents in its median line a comb-like elevation, the crista galli, and articulates with the frontal bone by means of the ~ fronto-ethmoidal suture. In the median line behind the cribriform plate of the ethmoid is seen the jugum s phenoidale of the sphenoid bone with the ethmoidal Spine, and to cither side are observed the lesser wings of the bone, these latter arising from either side of the body of the sphenoid by two roots which enclose an opening, the optic joramen. Near the sella turcica, the lesser wing of either side projects into the middle cerebral fossa as a short, slightly curved, hook-like process, the anterior ( li no id process. The middle cranial fossa is much deeper and larger than the anterior one, and is divided nto two halves by a marked median clevation, the sella turcica. In this there may be recog- d the high back of the saddle, the dorsum sell@, with the hypophyseal jossa in front of nd, still further anteriorly, the olivary eminence (tuberculum selle). In front of the latter roove, the optic groove (sulcus chiasmatis), and a second groove, the carotid groove, is situated | Side of the sella turcica. A short distance behind the dorsum sellx we find the spheno- nchondrosis, a slightly serrated line which indicates the boundary between the body enoid and the occipital bone and is the remains of the synchondrosis originally separat- joramen caecum, articulate with the lesser Wings of the = fee ee and extending from the foramen ae 42 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. To the outer side of the sella turcica we see the cerebral surface of the greater wing of the sphenoid bone, which is separated from the overlying lesser wing of the sphenoid by the superior orbital or sphenoidal fissure. The remaining boundaries of this surface are the same as those seen on the external surface of the base of the skull, namely, the sphenoparietal and spheno- squamosal sutures, the foramen lacerum or sphenopetrosal fissure. Near its origin from the body, the greater wing of the sphenoid bone contains three orifices; the foramen rotundum, Fic. 45.—The inner surface of the base of the skull; the anterior fossa is colored blue, the middle fossa white, and the posterior fossa pink. directed obliquely anteriorly and leading into a short canal, the foramen ovale, and the foramen. Spinosum. In addition to the greater wing of the sphenoid bone, the floor of the middle cranial fossa is formed by the cerebral surface of the squamous portion of the temporal bone and by the an- terior surface of the petrous portion, the posterior surface of the petrous portion and the mastoid portion helping to form the floor of the posterior cranial fossa. "The boundaries of the temporal j . THE INTERNAL SURFACE OF THE BASE OF THE SKULL. 43 _ bone in the middle fossa are also similar to those observed upon the external surface of the base of the skull, namely, the sphenosquamosal and squamosal sutures and the joramen lacerum. Upon the cerebral surface of the squamous portion of the temporal, commencing at the foramen spinosum, there is a groove, the sulcus arteriosus, which is continued by manifold rami- fications upon the inner surface of the cranial vault. Upon the apex of the petrous portion, which is in contact with the body of the sphenoid, there is a shallow depression, the trigeminal impression for the Gasserian ganglion, and at about the middle of its anterior surface there is a slit-like opening, the hiatus canalis jacialis (hiatus Fallopii), while upon its superior margin there runs a shallow groove, the superior petrosal groove. The posterior cranial fossa is the largest of all. Its floor is formed by only the occipital and temporal bones, the boundaries between which in the posterior fossa are the petro-occi pital fissure, the jugular joramen, and the occi pitomastoid suture. Upon the posterior surface of the petrous portion of the temporal bone there is a large, round, irregular opening, the infernal auditory meatus ( porus acusticus internus). The jugular joramen, situated between the temporal and occipital bones, is formed in the following manner. Each of the two bones possesses a corresponding notch which is so sub- divided that the jugular foramen consists of a smaller anterior and of a larger posterior com. partment, the former giving passage to the glosso-pharyngeal, pneumogastric, and spinal accessory nerves; the latter to the internal jugular vein. In the posterior fossa the mastoid portion of the temporal bone exhibits a curved groove, the sigmoid groove, which begins at the posterior compartment of the jugular foramen and is at first situated on the lateral portion of the occipital bone, passing in a curve around the jugular process, which is directed toward the temporal bone. In the mastoid portion of the _ temporal bone is the inner (cerebral) orifice of the mastoid joramen, and at the junction of the temporal, parictal, and occipital bones, where the lambdoid and occipitomastoid sutures become continuous, the sigmoid groove bends at almost a right angle into the transverse groove, so that the posterior inferior angle of the parictal bone, the mastoid angle, also aids in its formation. The transverse groove passes across the inner surface of the squamous portion of the occipital bone as a markedly shallower groove to a median crucial elevation, the crucial eminence, whose center forms the infernal occi pital protuberance. . The cerebral surface of the occipital bone forms by far the greater portion of the floor of the posterior fossa. Its basilar portion forms a portion of the so-called divus, a steep bony incline passing from the back of the sella turcica to the border of the foramen magnum; the _ anterior portion of the clivus is formed by that part of the body of the sphenoid which is situated ~ anterior to the original spheno-occipital synchondrosis. At the outer side of the clivus there s “ae oe injerior petrosal groove, which is formed by the junction of the occipital and tem- sent two rounded projections upon their cerebral surface, the jugular tubercles, whose bases versed by the previously mentioned hypoglossal or anterior condyloid canal, and behind 44 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 46.—The skull seen from above (4). > =foramen parietale. Fic. 47.—The inner surface of the roof of the skull (calvarium) (4). The posterior margin of the round foramen magnum, situated in the middle of the posterior fossa, is formed by the squamous portion of the occipital, which exhibits, below the transverse groove, two concave depressions, the inferior occipital fosse, which are separated by a median ridge, the internal occipital crest. THE SUPERIOR ASPECT OF THE SKULL. The superior aspect of the skull (Fig. 46) is much less complicated. It shows only four bones, the vertical portion of the frontal, the large surfaces of the two parietals, and the apex of the squamous portion of the occipital. The visible sutures are the coronal suture, the sagittal suture, separating the parietal bones throughout their entire length, and the lambdoid suture, which forms an obtuse angle with the sagittal suture. In the parietal bone, on either side of the sagittal suture and at about the junction of the third and fourth quarters, there is an orifice, the parietal joramen, and the foreshortened temporal line can also be seen. THE INNER ASPECT OF THE CRANIAL VAULT OR CALVARIA. The inner surface of the cranial vault (Fig. 47) corresponds to the outer surface with slight differences. It presents the same bones, frontal, parietal, and occipital, and the same sutures, the coronal, sagittal, and lambdoid. Upon the inner surface of the sagittal suture-we find a shallow groove, the sagittal groove, which commences at the crest of the frontal bone and passes backward over the parietal to the occipital bone. The cerebral surfaces of all the bones of the cranial vault show vascular grooves, the sulci arteriosi; they are found in greatest numbers upon the parietal bone and, next in frequency, upon the frontal bone. Small inconstant depres- sions, often of inconsiderable depth and situated particularly along the sagittal suture, are desig- nated as the foveole granulares or Pacchionian depressions. THE BONES OF THE SKULL. After this consideration of the skull as a whole we turn to the description of the individual bones of the skull. These may be divided into two groups: (1) the bones of the cranium (cranium cerebrale), and (2) the bones of the face (cranium viscerale). ‘The cranial bones are the occipital bone, the sphenoid bone, the two temporal bones, the two parietal bones, the frontal bone, and the ethmoid bone. The facial bones are the nasal bones, the lachrymal bones, the vomer, the injerior turbinated bones (conche nasales injeriores), the maxille, the palate bones, the zygomatic bones, the mandible, and the hyoid bone. The bones of the skull may also be classified according to the method of their development (see page 21), and from this standpoint they are quite heterogeneous structures; some of them, such as those of the base of the skull, are devel- oped in the primordial cartilaginous cranium, some are portions of the visceral skeleton, and some are so-called covering Coronal sulure Superior temporal line s Partetal bone Lambdoid suture Frontal bone yy Lyte dl f I ) Pi ¢ . Occipital bone Sagittal suture — Dae ~ @ arteri- OSUS Sagittal groove Fig. 47. Sagittal suture => —ees _ > oe THE BONES OF THE SKULL. 45 derma! bones, which serve to close in the cranium, the upper portion of which is unrepresented in the cartilaginous jal skeleton, Only a part of the cranial bones are preformed in cartilage, the majority being formed by direct tion of connective tissue, Those which are preformed in cartilage are also known as primordia! bones, and they are the occipital, with the exception of the upper part of the squamous portion, the sphenold, with the exception af the _ internal plate of the pterygoid process, the entire ethmoid and the inferior turbinal, and the petrous and mastaid por- tions of the temporal. The cranial bones formed in membrane are the upper part of the squamous portion of the occipital, the parictals, ‘the frontal, the squamous and tympanic portions of the tempurals, the vomer, the nasals, and the lachrymals. The only portions of the visceral cephalic skeleton which are preformed in cartilage and are to be regarded as primordial bones are the hyoid and the smal! auditory ossicles situated within the temporal bone. The following bones __ 0f the face are formed in membrane: the maxille, the palate bones, the internal plates of the ptcryguld processes of the _ sphenoid bone, the zygomatic bones, and the mandible. THE OCCIPITAL BONE. The occipital bone (Figs. 48 to 51) is composed of three portions which are not sharply separated, and of these portions one is paired and two are single. They are termed the basilar portion, the lateral portions, and the squamous portion, and are grouped about the foramen mag. num in such a way that the basilar portion is in front, the lateral portions are to cither side, . and the squamous portion is behind the foramen. ____ The basilar portion of the adult skull and the body of the sphenoid bone are united by osseous tissue (Fig. 51), but up to the time of puberty they are articulated by the s pheno-occi pital __ synchondrosis or jissure (see page 47). The lower surface of the basilar portion, which forms a : part of the external surface of the base of the cranium, lies almost horizontally, but the cerebral passes obliquely from above downward and from before backward and forms the divus lumenbachii). The inferior surface (Fig. 50) presents a median projection, the pharyngeal for the attachment of the pharyngeal aponcurosis, and to cither side are roughened c surfaces for the insertions of the rectus capitis anticus minor and major muscles. x The surface of the clivus (Figs. 43, 44, and 51) is slightly concave and its lateral margins exhibit a groove, frequently quite shallow, the injerior petrosal groove, which forms with a similar groove of the temporal bone (see page 55), over the petro-occipital fissure, a channel for the . ior petrosal sinus of the dura mater. _ The lateral portions, also termed the condyloid portions, extend posteriorly, and gradually become broader and thinner as they pass into the squamous portion of the bone. Their most iportant structures are the condyles (Figs. 41, 42, 48, and 50), which are situated upon their inferior surface and articulate with the first cervical vertebra. The articular surfaces of the ondyles are reniform in shape and are markedly convex, particularly from before backward; extend from the anterior margin to about opposite the middle of the foramen magnum, | Sasol posterior halves border directly upon this opening. Behind the condyles there ession, the condyloid jossa (Fig. 48), with the (inconstant) orifice of the condyloid canal, missary foramen, and the base of the condyle is traversed from side to side by the (Figs. 49 and 50), through which the twelfth cranial nerve, the hypoglossal, . THE CRANIAL BONES. i Sy 46 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 48.—The occipital bone seen from behind (4). Fic. 49.—The occipital bone seen from in front (4). Fic. 50.—The occipital bone seen from below (4). Fic. 51.—The occipital and sphenoid bones seen from above ($). The right anterior clinoid process is fused with the middle one. Upon the outer margins of the lateral portions of the bone, projecting toward the temporal bone, there is a prominence, the jugular process (Figs. 48, 49, 50, and 51), in front of which is situated a notch, the jugular notch, which is subdivided by a small intrajugular process (Figs. 50 and 51), into a small anterior and a larger posterior compartment. By apposition of the notches to corresponding notches of the temporal bone there is formed the jugular foramen (Figs. 43 and 44), which is divided into two compartments by a ligament extending between the corresponding intrajugular processes (see page 55). The inner or cerebral surface of the lateral portion of the occipital exhibits a blunt pro- tuberance, the jugular tubercle (Fig. 51), above and to the outer side of the internal orifice of the hypoglossal canal, which consequently passes through the lateral portion of the bone, below the jugular tubercle and above the condyle. Beside the jugular process and beginning in the jugular notch is seen the commencement of the sigmoid groove (see page 43), which curves over the cerebral surface of the jugular process. The largest portion of the occipital bone is formed by the squamous portion, which is flat and moderately curved, and in which an internal and an external surface can be recognized. It is bounded by the occipitomastoid suture, forming the mastoid border, and by the lambdoid suture, forming the /ambdoid border, and its apex is situated at the posterior extremity of the sagittal suture. The most striking formation upon the rather markedly concave internal or cerebral surface (Fig. 49) is the crucial eminence, the ridges of which form four shallow fossa, two superior occipital josse and two inferior occipital fosse. The middle of the cross is formed by the internal occipital protuberance, while the inferior median limb, the internal occipital crest, passes to the posterior margin of the foramen magnum. ‘The remaining three limbs are grooves produced by the venous sinuses of the dura mater; the two lateral ones are called the transverse grooves and the superior one is the posterior extremity of the sagittal groove (see page 44). The external surface of the squamous portion (Fig. 48) is markedly convex in both the sagittal and transverse directions, and is divided into two surfaces, an inferior nuchal surface (planum nuchale), roughened for the insertion of numerous muscles, and a superior smoother triangular occipital surface (planum occipitale). These two surfaces are separated by the superior nuchal line, a roughened ridge for muscular attachment, which passes in a’ curved direction from the external occipital protuberance to the occipito-mastoid suture, and a short distance above the linea superior we observe the somewhat more sharply curved linea suprema. The entire planum nuchale, from the external occipital protuberance to the foramen mag- num, is traversed by the external occipital crest. From about the middle of this crest, and parallel to the linea suprema, there passes outward the injerior nuchal line, upon which there are fre- a Planum occipitaie External occipital protuberance Linea nuchae suprema Planum nuchale Superior nuchal line Squama occipitalis Inferior nuchal line Planum nuchate Condyloid canal - Lateral portion Condyloid fossa Jugular process Hypoglossal canal Sug prot dé. Occipital condyle 7 Foramen magnum External occipital crest Fig. 48. Sagittal groove =? ¢ ; eG A a) Naat thee Lambdoid border Superior occipital sn fossa gees caeters v “- Transverse groove Inferior ocapital Jos Sa Internal occipital Wastoid border protuberance Internal occipital crest Co ndyloid canal (sigmaed groove) Jugular tubercle Jugular process - Hypogiossal canal Occipital condyle Basilar portion + Fig. 49. Basilar portion Hypoglossal canal + {ntrajugular process Fig. 50. Cf fiz Squamous portion Yanum nuchale Frontal border Superior orbital Anterior Ethmo ay a . : hes clinoid Optic idal Olivary Optic tas j . Process groove spine process foramen , arietal , P i] a ig Vy : Parictal angle — é 4 angie Squamous border Foramen ovale Foramen spinosam Lingula Spheno-ocapital synchondros Posterior clinoid process 2) Intrajugular process Jugular notch ugular tubercle Jugular process Hypoglossal canal Sigmoid groove Lambdoid border Transverse groove THE BONES OF THE SKULL. 47 uently two particularly well-marked roughened ridges, the crest jor the rectus capitis posticus jor muscle and that for the rectus minor. The relations of the occipital bone to the neighboring bones of the skull have been pre- iously described on pages 38 and 40. Only the basilar portion, the lateral portions, and the lower part of the squamous portion are preformed in cartilage, the upper part of the squamous portion (the planum occipitale) being formed in membrane. At the begin- ning of the fourth feta! month, four (or five) points of ossification appear, one in the basilar portion, one in each lateral _ portion, and one (or two) in the lower part of the squamous portion. The upper part of the squamous portion fs separately formed, and is partly isolated from the remainder of the bone until after birth by s suture, the sutara mendesa., ~ Sometimes the part of the squamous portion which is net preformed in cartilage remains independent, from the per- _ sistence of the sutura mendosa, and forms the triangular os interparictale (os ince), For a long time after birth (until the end of the fourth year) the lateral portions are separated from the body and tain the lower part of the squamous portion by the anterior and posterior interoccipital synchondroses. THE SPHENOID BONE. In its form the sphenoid bone (Figs. 51 to 54) somewhat resembles a winged insect. It consists of the following parts: (1) The body; (2) the two greater wings (also called the fem- poral wings); (3) the two /esser wings (also called the orbital wings); (4) the plerygoid processes. Fic. §2.—The sphenoid bone seen from in front. [ the adult skull the bench’ is firmly united to the occipital bone, the two together forming ne large bone, the os basilare (Fig. 51). “he body of the sphenoid (Fig. 52) forms the center of the bone, from which all the other ns radiate. Posteriorly it articulates with the occipital bone (spheno-occi pital synchon- see page 43), and anteriorly with the ethmoid bone. Its upper surface is formed by turcica (Fig. 54); its lower surface forms a portion of the external surface of the base skull (Fig. 42) and articulates with the ala vomeris and the sphenoidal process of the e bone. It contains a cavity communicating with the nasal fosse, the sphenoidal sinus, 4& ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 53.—The sphenoid bone seen from in front (4). Fic. 54.—The sphenoid bone seen from behind (4). which is completely divided into two portions by a sagittal septum which is rarely situated exactly in the median line. The two sinuses communicate with the posterior superior portion of the nasal fossee by means of irregular openings in the anterior surface of the body of the sphenoid bone (Fig. 53). The greater portion of the almost rectangular anterior surface of the body (Figs. 52 and 53) is formed by two thin, approximately triangular bony platelets, the sphenoidal turbinated bones (conche sphenoidales), which, although usually united with the sphenoid, are to be regarded as portions of the ethmoid; they are frequently continuous with the ethmoid and may be represented by a number of small independent bones (ossa Bertini). They form the inferior margins of the apertures of the sphenoidal sinuses, and in the neighborhood of the apertures some small fossee which close in the posterior ethmoidal cells are frequently visible. The anterior extremity of the septum of the sinuses appears upon the anterior surface of the body of the sphenoid in the shape of a low ridge, the sphenoidal crest (Fig. 53). It is con- tinued upon the lower surface of the body of the sphenoid, where it becomes more pronounced and forms the sphenoidal rostrum, to which is attached the ala vomeris. The upper surface of the body (Figs. 43, 44, and 51) is the most strongly marked surface of the bone. Its most striking structure is the so-called sella turcica (see also page 41), which is that portion of the upper surface of the body which belongs to the middle cranial fossa, smaller portions of the body helping in the formation of the floors of the anterior and of the posterior fosse. The portion in the anterior fossa is a plane surface in front of the sella turcica, con- necting the two lesser wings, and is called the jugum sphenoidale; toward the adjacent lamina cribrosa of the ethmoid bone it presents a process, the ethmoidal spine (Fig. 51), the shape of which varies greatly in different individuals. Behind the jugum sphenoidale at the anterior margin of the sella turcica there is a shallow groove, the optic groove (sulcus chiasmatis), so called because it contains the decussation or chiasma of the optic nerves (Fig. 51). It is continued on either side into the optic joramen, which leads into the orbital cavity. Behind the optic groove the body of the sphenoid presents a flat elevation, the olzvary emi- nence (tuberculum selle), the margins of which sometimes give origin to the inconstant middle clinoid processes, and between the eminence and the high back of the saddle, the dorsum selle, there is situated a rather deep, slightly elliptical depression, the hypophyseal fossa, which lodges — the pituitary body or hypophysis. On each side of this fossa there is upon the root of the greater wing of the sphenoid a shallow but rather broad groove, situated at the junction of the upper and lateral surfaces of the body of the sphenoid bone and limited externally toward the greater wing of the sphenoid by a fine bony platelet, the lingula (Fig. 51). This groove is called the carotid groove (Fig. 54), since it lodges the internal carotid artery. The dorsum selle bears upon either side slightly pointed sharp corners, the posterior clinoid processes. Behind the dorsum sell a portion of the clivus also belongs to the body of the sphenoid — = Frontal border Foramen rotundum Malar border Infratemporal surface ~~ Ss — . ' tS Sphenomaxillary surface Ptery- 3s ° goid § r yo canal 5& . ew’ Internal pterygoid plate Sx | Fig. 53. Dorsum sellae For, Superior orbital rotun- Jissure dum 7 co ‘a - Squamous - border we pe , « J Z 7 Carotid groove Vaginal Pterygoid canal process Body Internal pterygoid plate Aperture of sphenoidal sinus Sphenoidal turbinated bone Sphenoidal crest eo mo (spheno-occipita synchondrosis) ! surface of greater wing _ & Lesser wing Superior orbifal Jissure Of greater wing Infratemporal ridge Spinous proces Pterygopalatine groove External pterygoid plate Pterygoid fissure Hamular process Cerebral surface of greater Post. clinotd proc. Nias Parietal Ant. clinoid proc ,. id. angle Lesser wing , : i} < ae | Sulcus arteriosus f Spinous process . Groove for Eustachian tube Scaphoid fossa External pterygoid plate Hamular process Ct Se) PO eee ee Fh — THE BONES OF THE SKULL. 49 bone (see also page 43), which thus aids in forming a part of the floor of the posterior cranial ’ fossa (Fig. 45). The posterior surface of the body of the sphenoid bone (Fig. 54) is adherent to the occipital bone. In young individuals, if a synchondrosis still exists, the surface is rough and irregular. The greater portion of the lower surface of the body of the sphenoid, like the anterior one, forms a boundary of the nasal fossz and bears the sphenoidal rostrum. On this surface there are also two small sagittal grooves or canals, the inner of which is the basipharyngeal canal (Fig. 53); while the outer one, above which is the vaginal process of the pterygoid process (Fig. 54), is the pharyngeal canal (Fig. 53) (see also page 51). The lateral surfaces of the body of the sphenoid bone give origin to the two greater wings of the sphenoid, while the pterygoid processes arise from the lower surface of the body of the bone. The lesser or orbital wings are narrow, almost horizontal, bony plates arising from the body of the sphenoid bone by two roots which surround the optic foramen (Fig. 51). Their upper surfaces form the posterior portion of the floor of the anterior cranial fossa (see page 41 and Fig. 45) and their posterior margins separate the anterior from the middle fossa. The posterior margin of each wing terminates internally in a rather sharp point, the anterior clinoid process, which partly overhangs the sella turcica, and the inferior surface forms the roof of the sphenoidal (superior orbital) fissure and also aids in the formation of the orbit. The lesser wings articulate anteriorly with the orbital plate of the frontal bone (sphenojrontal suture, see page 37), and between the lesser and the greater wings there remains a fissure, broad internally and narrowing toward its outer extremity, the sphenoidal (superior orbital) jissure (Figs. 38, 51, and 54). It leads into the orbit and its greater portion is closed by a membrane; it gives passage to the nerves of the ocular muscles (the oculomotor, the abducens, and the trochlear), to the first or ophthalmic division of the trigeminus, and to the superior ophthalmic vein. The greater or temporal wings of the sphenoid arise from the lateral surfaces of the body of the sphenoid by broad roots in which are situated three openings, the jeramen rotundum, the joramen ovale, and the joramen spinosum (Fig. 51). The foramen rotundum leads obliquely anteriorly through the bone into the sphenomaxillary fossa (jossa plerygopalatina), and trans- mits the maxillary nerve (the second division of the trigeminus). The foramen ovale traverses the bone in a vertical direction and makes its exit upon the external surface of the base of the skull (see page 39, and Figs. 41 and 42); it transmits the mandibular nerve (the third division of the trigeminus). The foramen spinosum pursues the same direction and gives passage to the middle meningeal artery.* The greater wing, like the lesser one, is practically horizontal. It possesses three distinctly separated surfaces, the cerebral, the orbital, and the temporal, and there may also be recognized a jrontal border (Fig. 51), the very rough margin directed toward the frontal bone, a zygomatic * The greater wings have also been described, although not quite correctly, as arising from the body of the sphe- noid by three roots, a middle broad root, situated between the foramen rotundum and ovale,an anterior narrower root, between the foramen rotundum and the sphenoidal fissure, and a very narrow posterior one, between the foramen ovale and spinosum. The latter, however, can scarcely be regarded as a root. ‘ 4 50 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. ~. border, in contact with the zygomatic bone, and a squamosal border,* directed toward the tem- poral bone. The most external portion of the greater wing, which is in contact with the parietal bone in the sphenoparietal suture, is known as the parietal angle, and its most posterior, pointed portion, which is directed toward the petrous portion of the temporal bone, is called the spine (Figs. 53 and 54). The cerebral surface is distinctly concave and exhibits the internal orifices of the joramen rotundum, ovale, and spinosum (Fig. 51), the last receiving its name on account of its location in the spine.t It also occasionally shows digitate impressions and cerebral juga (see pages 41 and 6r), and a sulcus arteriosus which is continued from the temporal bone. The almost plane, slightly concave, quadrangular orbital surjace (Figs. 38 and 53) is the smallest of the three surfaces. It forms a portion of the outer wall of the orbit, and in this situ- ation its zygomatic border articulates with the zygomatic bone by means of the sphenozygomatic suture. The sphenomaxillary or inferior orbital fissure separates the greater wing from the maxilla, and at the margin of this fissure, the orbital surface possesses a sharp edge, the orbital crest, which separates it from the sphenomawxillary surface (Fig. 53), a lower portion of the tem- poral surface. In the vicinity of the superior orbital fissure the orbital surface exhibits a bony spine of variable development which is called the spina recti lateralis and is the point of origin for the muscle of the same name. The temporal surface (Figs. 39, 40, and 53) is by far the largest of the three surfaces of the greater wing of the sphenoid and is distinctly angulated at the level of the znjratemporal crest (see page 39). The almost vertical portion of the temporal surface, situated above this crest, forms a portion of the planum temporale (see page 38), while the portion situated below the crest is divided into the more horizontal injratemporal surjace and the triangular spheno- maxillary surjace by a rather low ridge which is called the sphenomaxillary ridge. "The spheno- maxillary surface (Fig. 53) looks rather anteriorly and overlaps the root of the pterygoid process, while the infratemporal surface is directed more to the side, and presents the external orifices of the foramen ovale and the foramen spinosum. It forms the posterior wall of the plerygo- palatine (sphenomaxillary) fossa (see page 78), and contains the anterior or external orifice of the foramen rotundum. It is sharply separated from the orbital surface by the orbital crest (Fig. 53). , While the greater and lesser wings of the sphenoid are practically horizontal, the third pair of processes, the pterygoid processes (Figs. 53 and 54), pass almost vertically downward and are apposed (Figs. 41 and 42) to the posterior surface of the maxilla (see page 67) and to the hard palate (see page 79), forming the lateral boundaries of the posterior nares. Each pterygoid process arises from the lower surface of the body of the sphenoid by two roots, between which is the pterygoid (Vidian) canal (Fig. 53), which runs almost horizontally, its anterior extremity being in the pterygopalatine fossa, and its posterior one in the foramen lacerum. Below the pterygoid canal the pterygoid process divides into two lamelle, the internal and the external plerygoid plate. The internal plate is narrower and almost vertically placed, while * So named where it borders upon the squamous portion of the temporal bone; in the region of the sphenopetrosal fissure (see page 39) it is called the petrosal border, + Occasionally the foramen spinosum is only partially limited by the sphenoid bone, i. e., it is simply a notch in the spine. ‘ - THE BONES OF THE SKULL. 51 the external plate is broader and directed more externally. Between the two is situated the plerygoid jossa, which is narrow above, wide below, and open posteriorly, and whose anterior inferior boundary is formed by the tuberosity or pyramidal process of the palate bone, which closes the space, the plerygoid notch, between the two plates. At the base of the internal plate there is a small elliptical fossa, the scaphoid jossa (Fig. 54), to the outer side of which, toward the spine, there is a shallow groove, in which is situated the cartilaginous portion of the Eustachian tube which connects the middle ear with the naso- pharynx. At its lower end the internal plate terminates in the slender hook-like hamular process (hamulus plerygoideus) (Figs. 53 and 54), the groove at the base of this being called the hamudlar groove and forming a pulley for the tendon of the tensor veli palatini. Beside the scaphoid fossa is situated a small, flat, rather triangular process called the vaginal P ular | 8 process (Fig. 54), which is directed toward the sphenoidal rostrum; together with the sphenoidal process of the palate bones it aids in the formation of the pharyngeal canal (see page 49). Upon the anterior surface of the pterygoid process, running downward from the anterior extremity of the pterygoid canal, there is a shallow groove, the plerygo-palatine groove (Fig. 54), which, with similarly named grooves upon the palate and maxillary bones, forms the plerygo- palatine canal, whose external orffices are the palatine foramina of the hard palate (see pages 4o and 78). Since the sphenoid bone is almost exactly in the center of the skull and has relations with both the cranial and the facial bones, it articulates with a large number of the bones of the skull (see page 37 ef seq.). These are the occipitals, the temporal, the parietal, the frontal, the ethmoid, the maxilla, the zygomatic, the palate, and the vomer. It also forms a portion of the anterior, middle, and posterior cranial fossz, of the orbit, of the nasal fosse, of the temporal fosse, of the infratemporal fosse, and of the sphenomaxillary fossz. As regards the development of the sphenoid, it may be said that the entire bone is preformed in cartilage with the exception of the internal plates of the pterygoid processes and the sphenoida! turbinated bones, which are developed in membrane. Ossification begins toward the end of the second fetal month. Isolated centers appear in the anterior and posterior portions of the body of the bone, so that for a time there are two sphenoid bones, as it were, situated one behind the other. The lesser wings arise from special centers, as do also the greater wings, the centers for the latter also forming the outer plates of the pterygoid processes. The lesser wings unite with the anterior center of the body of the sphenoid between the sixth and seventh fetal months; the greater wings do not unite with the posterior center until after birth; and the two halves of the body of the sphenoid do not unite untl after birth, and then but slowly, so that an intersphenoidal synchondrosis exists for a long time. The internal plate of the pterygoid process is formed in membrane, but soon unites (in the seventh fetal month) with the external plate. The sphenoidal turbinated bones appear much later and do not unite with the body of the sphenoid until the age of puberty, and at the same time the spheno-occipital synchondrosis commences to disappear. The sphenoidal sinus arises during childhood, but increases considerably in extent during later life. © Variations are frequent in the sphenoid bone, such as the occurrence of middle clinoid processes (see page 48) _ and their fusion with the anterior or posterior clinoid processes. By ossification of the pterygospinous ligament (see page 119) there is not infrequently formed a pterygospinous process (processus Civinini). — = ~s iF = THE TEMPORAL BONE. 52 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 55.—The right temporal bone seen from the outer (lateral) surface (7). Fic. 56.—The right temporal bone seen from the cerebral surface (+). Each temporal bone consists of four portions: (1) A squamous portion; (2) a petrous por- lion; (3) a mastoid portion; (4) a tympanic portion. The petrous portion is also termed the pyramid. The squamous and mastoid portions are placed almost vertically, while the pyramid is practically horizontal. At the external auditory meatus, the individual portions of the temporal bone are grouped in such a manner that the smallest portion, the tympanic portion, is situated in front of and below the auditory canal, the mastoid portion is behind, the squamous portion above, and the petrous portion internally and anteriorly. THE SQUAMOUS PORTION. The squamous portion of the temporal bone (Figs. 55, 56, and 57) consists of an approxi- mately semicircular vertical bony plate which is concave internally and convex externally. An- teriorly it articulates (Figs. 39 and 40) with the temporal surface of the greater wing of the sphenoid by the sphenosquamosal suture (sphenoidal border), and superiorly with the parietal bone by means of the squamosal suture (parietal border, see page 38). A deep notch, the parietal notch, accommodates the sphenoidal angle of the parietal bone and separates the squamous portion from the mastoid portion, which is situated inferiorly and posteriorly. The zygomatic process (Fig. '55) springs from the external surface of the squamous portion of the temporal bone and aids in the formation of the zygomatic arch, by articulating with the temporal process of the zygomatic bone by means of the zygomaticotemporal suture. It is almost horizontal at its origin, but later it rotates through about go degrees, so that it assumes a vertical position and forms a bony process flattened from side to side. Its posterior prolongation above the external auditory meatus forms a su pramastoid ridge, which posteriorly becomes continuous with the terminal portion of the inferior temporal line (see Fig. 39). The part of the squamous portion which lies below the zygoma forms part of the external surface of the base of the skull and is consequently almost horizontally placed (Fig. 58), and borders upon the infratemporal surface of the greater wing of the sphenoid bone. It is there- fore advantageous to subdivide the squamous portion of the temporal bone into a larger vertical portion and a smaller horizontal portion. In the vertical portion there may be recognized an external temporal surface and an internal cerebral surface (the latter is absent in the horizontal portion). The temporal surface forms a part of the planum temporale and of the fossa temporalis (see Fig. 39), and is usually smooth, though its lower portion may sometimes be roughened by the origin of the temporal muscle. It presents a shallow groove for the middle temporal artery, beginning above the external audi- tory meatus and running upward. At the junction of the horizontal and vertical parts is situated the roof of the external auditory meatus, the remaining walls of the auditory canal being formed by the tympanic portion, and just above the external auditory meatus, at the transition into the mastoid portion, there is frequently found a small bony spine, the suprameatal spine (Fig. 55). Parietal border Squamous portion (temporal surface) la Groove for middle temporal artery ——— Temporal line Sphenoidal border Parietal notch Suprameatal spine Zygomatic process Mastoid foramen Articular eminence Glenoid fossa Petrotympanie fissure Occipital border (mastoid portion) Mastoid groove Mastoid portion Vaginal process Styloid process stoi : Tympanic Mastoid process Jortion External auditory meatus Fig. 55. Parietal border iy } ¢ nl ) f shpat Cerebral surface Arcuate eminence Sulcus arteriosus Sphenoidal border Parietal notch Superior petrosal groove Petrous portion (apex) Mastoid foramen Subarcuate fossa Occipital border Internal auditory meatus , inferior petrosal groove Sigmoid groove Sty loid process Orifice of aquaeductus vestibali Jugular notch Fig. 50. THE BONES OF THE SKULL. aA 3 The horizontal part (Fig. 58), situated in the base of the skull, exhibits a large fossa at the root of the zygomatic process. This is the mandibular or glenoid jossa, which accommodates the condyloid process of the mandible and consists of an articular surface and of an anterior portion, the articular eminence, which is also partially covered by cartilage. The two roots of the zygomatic process surround the mandibular fossa. In front of the articular eminence there remains a small portion of the inferior surface of the squamosal portion, which completes the infratemporal surface of the greater wing of the sphenoid bone, and behind the mandibular fossa lies the petrotympanic or Glaserian jissure (Figs. 55 and 58). The margins of the squamous portion of the temporal bone (Figs. 56, 57, and 58) are ex- tremely rough and sharp, and, in the squamous suture, they overlie the margins of the adjacent parietal bone and greater wing of the sphenoid; at the inferior extremity of the sphenosquamosal suture only does the margin of the infratemporal surface of the greater wing of the sphenoid overlap the squamous portion of the temporal. Its internal or cerebral surface is smaller than the external one, owing to the width of the squamosal suture, and it is separated from the petrous portion, always in the new-born and usually even in the adult, by a more or less ossified suture, the pefrosquamosal fissure. Its cerebral surface consists of only a vertical portion, which, in addition to sulci arteriosi for the branches of the middle meningeal artery, occasionally exhibits cerebral juga and digitate impressions. THE MASTOID PORTION. . The mastoid portion of the temporal bone (Figs. 55 to 58) derives its name from the mas- toid process, the most important structure of this portion of the temporal bone. At the parictal notch it articulates with the mastoid angle of the parietal bone (parietomastoid suture), and the occipital border articulates with the squamous portion of the occipital (occi pitomastoid suture) (see Fig. 42). In the temporal bone itself the mastoid portion borders upon the tympanic portion (tympanomastoid fissure), upon the petrous portion, and upon the squamous portion; it is sepa- rated from the latter during youth by the squamosomastoid suture (Figs. 59 and 60), which becomes more or less obliterated in later life. It presents a rough, markedly convex external surface, which bears the mastoid process, and an internal concave cerebral surface. The mastoid process is a broad, conical, bony projection covering a considerable part of the mastoid portion, and presents upon its inner surface a deep notch, the mastoid notch (Fig. 58). Internal to this notch, between it and the occipitomastoid suture, there is a shallower groove for the occipital artery. Behind the mastoid process, upon the external surface of the mastoid portion, is the mastoid joramen (Figs. 55 and 56), the external orifice of the mastoid emissarium, which varies in size and may be absent. It lies immediately beside, or sometimes even in, the occipitomastoid suture. The cerebral surface of the mastoid process.presents a broad groove, the sigmoid groove (see also Fig. 43), which usually contains the internal orifice of the mastoid emissarium (Fig. 57). In this situation the mastoid portion is directly continuous with the posterior surface of 1 The mastoid process contains numerous air spaces known as the mastoid cells (Figs. 61 —_— % he a ea 54 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. = Fic. 57.—The right temporal bone seen from the cerebral surface and from the apex of the petrous portion (4). Fic. 58.—The right temporal bone seen from below (+). Fic. 59.—The right temporal bone of a new-born child (3). Fic. 60.—The left temporal bone of a four-year-old child (3). In Figs. 59 and 60 the squamous portion is green, the petrous and mastoid portions yellow, and the tympanic portion white. and 63), and these may become so large, particularly in later life, that they markedly attenuate the bony tissue and even expand it. They are connected with the cavity of the middle ear, the tympanic antrum. The mastoid process is one of the chief points for muscular attachment which the skull possesses, and it receives the insertions of the sternocleidomastoid and of portions of the splenius capitis and of the longissimus capitis muscles. The mastoid notch gives origin to the posterior belly of the digastric muscle. Several openings may be present in the vicinity of the mastoid foramen. The depression beside the suprameatal spine and above the mastoid process is also called the mastoid fossa. THE PETROUS PORTION. The petrous portion or pyramid of the temporal bone (Figs. 56 to 58) forms a portion of both the external and internal surfaces of the base of the skull (see Figs. 42 and 43). It has the shape of a three-sided horizontal pyramid, two of the surfaces being directed toward the cranial cavity and one externally, and the axis of the pyramid passing obliquely from behind forward and from without inward. There may consequently be distinguished internally an anterior surface and a posterior surface, and externally an inferior surface, and there is a superior, an anterior, and a posterior border. The superior border separates the two cerebral surfaces; the two remaining borders separate the cerebral surfaces from the external one. The petrous portion in the adult is directly continuous externally with the tympanic portion, and its internal anterior surface borders upon the squamous portion (petrosquamosal fissure, see page 53) and upon the sphenoid bone (sphenopetrosal fissure). The base and a part of the posterior margin is continuous with the mastoid portion even during early fetal life, and the anterior portion of the posterior margin articulates with the lateral portion of the occipital bone (petro-occipital fissure). ‘The apex of the petrous portion projects into the foramen lacerum (see Fig. 42), in the space between the sphenoid and the occipital bones. The anterior cerebral surface forms a portion of the floor of the middle cerebral fossa, and presents a flattened projection lying at right angles to the axis of the pyramid and known as the arcuate eminence (Fig. 56), because it overlies the semicircular canal of the internal ear which is embedded in the petrous portion of the bone. Upon this anterior surface there is also a small slit-like orifice, the hiatus Fallopii (hiatus canalis facialis) (Fig. 57), from which the great superficial petrosal nerve passes toward the apex of the pyramid and to the foramen lacerum in a groove (Fig. 57). External and anterior to the hiatus canalis facialis there is a second smaller opening, the superior aperture of the tympanic canaliculus (Fig. 57), the place of exit of the lesser superficial petrosal nerve, which also passes forward to the region of the foramen lacerum in a groove. Aperture of super (+ provve for smais Greeve for greul tu; Squamous portion (cerebral surface) > Zygomalic process osquame al fi Musculotubar canal ims Pyramid . THE BONES OF THE SKULL. 59 mosomastoid suture, indications of which may be visible in adult life, separates the squamous from the mastoid por- tions. The bone also varies considerably from that of the adult in other respects, although all the portions are already united by osseous tissue. Especially large in the new-born is the subarcuate fossa During the first years of life the tympanic portion develops by the growth of the annulus tympanicus to a trough- like structure, and it is as the result of this growth that the bony meatus is formed. There nevertheless remains a con- _Stant unossified portion of the inferior wall of the meatus (Fig. 60), which usually closes in during the fifth year. The mastoid process becomes distinct at this time, but does not contain air-cells until the time of puberty. The styloid process, arising from the second cartilaginous branchial arch, ossifies late and subsequently becomes - connected with the temporal bone. THE PARIETAL BONE. The parietal bone (Figs. 64 and 65) is a typical flat bone which arises from the membranous cranial capsule and is not preformed in cartilage. It is one of the simplest of the cranial bones, is distinctly quadrangular in shape, and is markedly curved both in the sagittal and in the frontal direction. It presents for examination two surfaces, an external convex parietal surjace, and an internal concave cerebral surjace. The four borders of the bone are named respectively the jrontal, the sagittal, the occipital, and the squamosal border, and by them the bone articulates (Figs. 38 and 40) at the coronal suture with the frontal bone by its frontal border, at the sphenoparictal, squamosal, and paricto- mastoid sutures with the greater wings of the sphenoid and with the temporal bone by the squa- - mosal border, and at the lambdoid suture with the occipital bone by the occipital border. In _ the sagittal suture, the sagittal borders of both parictal bones articulate with each other (Fig. 46).. The anterior, superior, and posterior margins are markedly serrated, corresponding in character to the sutures (suture serrate); the inferior margin, however, is beveled and_ its external surface is overlaid in the squamosal suture by the margin of the temporal bone. The four angles of the bone are the frontal angle, the anterior superior angle, formed by the coronal and sagittal sutures; the sphenoidal angle, the anterior inferior angle at the sphenoparictal suture; the occipital angle, the posterior superior angle, formed by the sagittal and lambdoid sutures; and the mastoid angle, the posterior inferior angle, at the parietomastoid suture, filling out the parietal notch of the temporal bone. The most acute angle is the sphenoidal. The external or parietal surface (Fig. 64) presents at its point of greatest curvature the etal eminence. Below this run the superior and injerior temporal lines (see also Figs. 39 and 40), the latter being much more distinct than the former. Below these lines the external irface of the parietal bone forms a portion of the planum tem porale (see Fig. 39). In the vicinity of the sagittal suture and near its posterior extremity is situated the parietal joramen, a so-called emissary foramen. Sometimes the internal and sometimes the external ori ice is wanting; the former leads into the sagittal groove. The most striking structures upon the cerebral surface (Fig. 65) are the extensive grooves ie blood-vessels, sulci arteriosi, of which, as a rule, there is a well-marked anterior and a ounced posterior one. They are for the branches of the middle meningeal artery and Saad moulds of these vessels.* The cerebral surface also sapien two other grooves more rarely sulci venosi also occur. On the other hand, the commencement of the sulcus arteriosus is y converted into a short canal by a bridge of osseous tissue (see Fig. 65). 60 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 66.—The frontal bone seen from in front (4). Fic. 67.—The frontal bone seen from behind (4). presents one-half of the sagittal groove, while the mastoid angle contains a small portion of the sigmoid groove (see also Figs. 43 and 44). Digitate impressions and cerebral juga likewise occur and granular joveole granulares (Pacchionian depressions) are still more common. The parietal bone develops in membrane in the third fetal month from a center of ossification situated in the pari- etal eminence. Even in the new-born the bony trabecule show a distinct radiation from this point. THE FRONTAL BONE. The frontal bone (Figs. 66 to 69) consists of a vertical arched portion and of a horizontal portion. The vertical portion is known as the jrontal portion and the horizontal portion is composed of two orbital plates, and a small median nasal portion. At the orbital margins the horizontal and vertical portions become continuous. The frontal portion, the main portion of the entire bone, articulates in the coronal suture with both parietal bones by its parietal border (Figs. 39 and 40) and in the sphenofrontal suture with the greater wing of the sphenoid bone. It forms the entire frontal portion of the cranial vertex and presents two surfaces for examination, an external jrontal surjace and an internal cerebral surface. The frontal surface (Fig. 66) is markedly convex in both the sagittal and the transverse direction and presents some distance above the orbital cavities two feebly projecting flattened . elevations, the frontal eminences. Immediately above the orbital margins and parallel to them are two slightly projecting ridges, the superciliary arches, the development of which varies con- siderably in different individuals; the flat area between these two ridges is called the glabella. The remainder of the external surface is smooth, although there may be a slight roughening in the median line which represents the remains of the original frontal or metopic suture. The supraorbital border is situated at the junction of the vertical with the orbital plate. A portion of it is furnished by the zygomatic process of the frontal bone, which also forms part of the external orbital margin and, in the latter situation, articulates with the frontosphenoidal process of the zygomatic bone in the zygomaticofrontal suture (Figs. 37 and 38). The éemporal line commences at the zygomatic process and separates the frontal surface of the frontal portion of the bone from the small temporal surface, the latter surface, almost in the sagittal plane, forming a portion of the planum temporale and being that part of the frontal bone which borders upon the temporal surface of the greater wing of the sphenoid bone. Immediately above the supraorbital border there are foramina, which may be represented by notches of varying depth in the border itself. The inner one is designated as the frontal notch or foramen (Fig. 65), while the outer one is known as the supraorbital notch or foramen* (Figs. 66, 68, and 69). The inner or cerebral surface of the frontal portion (Fig. 67) presents a median ridge upon * The supraorbital notch is much more frequently present as a foramen than the frontal notch; sometimes both of the notches form a single shallow groove. il aed Frontal portion rontal eminence (frontal surface) i Fig. 66. Superior temporal line Temporal surface Superciliary - arch Orbital portion Zygomatic (orbital surface) Supraorbital process foramen . Frontal notch Nasal portion Frontal spine Supraorbital margin Supraorbital notch Sagittal groove Cerebral surface of frontal portion Pi arietal ¢ ‘ border Fig. 67. Lygomatic process Cerebral surface (of orbital portion) Frontal crest Foramen caecum Orifice of frontal sinus Frontal spine THE BONES OF THE SKULL. Oo! its lower portion, the frontal crest, which extends to the joramen caecum (see page 41), and is continued superiorly as a groove, the commencement of the sagilfal groove (sce page 44). The cerebral juga, digitate impressions, and sulci arteriosi upon the cerebral surface of the orbital _ portion are sometimes continued upon the inner surface of the vertical plate, as there is no dis tinct boundary between the cerebral surfaces of the two portions of the bone. The foramen cecum is sometimes situated entirely within the frontal bone. The two orbital plates of the frontal bone are separated by a deep notch, the ethmoidal notch (Fig. 68), which articulates with the cribrijorm plate of the ethmoid bone. They possess two surfaces, a superior cerebral surjace, which forms a portion of the anterior cerebral fossa, and an orbital surjace, which constitutes a portion of the roof of the orbit. The cerebral surface (Fig. 67) is separated from the ethmoid bone by the frontoethmoidal suture (Figs. 43 and 44), and is in contact with the lesser wing of the sphenoid bone at the sphenofrontal suture. It is almost flat and exhibits quite distinct cerebral juga and digitate impressions, as well as the sulci arteriosi of the anterior and middle meningeal arteries. The orbital surjace (Figs. 68 and 69) is distinctly concave, and forms the largest part of the roof of the orbit and also a portion of its internal and external walls. In this situation it articulates (Figs. 37 and 38) with the greater wing of the sphenoid bone by the sphenofrontal f suture, with the lamina papyracea of the ethmoid bone by the frontoethmoidal suture, and with the lachrymal bone by the frontolachrymal suture. The appearance of the ethmoidal notch as seen from the inferior surface of the frontal bone between the orbital surface is quite different from that which it presents from the cerebral surface. It is not limited by a simple suture, but its borders are rather broad and irregular, and are provided with small depressions, the e¢hmoidal depressions, which complete the air-cells of the ethmoid bone. In the septa between the ethmoidal cells there are two grooves or canals, an anterior and a posterior, which run respectively to the anterior and posterior ethmoidal joramina, situated beside or in the jrontoethmoidal suture; they give passage to the vessels and nerves of the same name. The portion of the orbital surface which is in the inner wall of the orbit always presents a ‘small depression, the ¢rochlear de pression (Figs. 68 and 69), and sometimes a small bony spicule, the trochlear spine, both of which are so named on account of the fibrocartilaginous pulley of _ the superior oblique muscle being attached in this situation. In the outer portion of the orbital surface beneath the zygomatic process there is situated a shallow depression, which lodges the The nasal portion of the frontal bone (Figs. 66 and 67) is the small median portion situated between the orbital cavities and projecting somewhat below the frontal portion. It possesses a very irregular roughened border, known as the nasal border, for articulation with the nasal bone and the frontal process of the maxilla, and its inferior surface is marked by a bony nidge, spine, which, together with the rough nasal border, articulates with the bones which skeleton of the nose. frontal bone, like many of the cranial bones, contains a cavity, the jrontal sinus (Fig. ccurately speaking, two cavities, which are separated by a septum usually placed to f the median line. Like the majority of the bony sinuses they communicate with the , the communication in this instance being effected by the two openings (Fig. 67) 62 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 68.—The frontal bone seen from below (4). Fic. 69.—The frontal bone, the greater part of the ethmoid, and the nasal bones in place, seen from below (4). The frontal bone is white, the ethmoid yellow, and the nasal pink. FIG. 70.—The ethmoid bone seen from above (+). Fic. 71.—The ethmoid bone seen from the side (+). Fic. 72.—The ethmoid bone together with the conche sphenoidales, which are united with it, seen from above and partly from behind (+). situated between the frontal spine and the ethmoidal notch. The development of the frontal sinuses is subject to great individual variation; they are generally larger in advanced life than during youth, and they are always situated at the base of the frontal portion, especially behind the superciliary ridges, the prominence of which is actually dependent upon the size of the sinuses. They frequently also extend into the orbital plates for a varying distance, and are sometimes enormously developed and markedly distend the frontal bone in the region of the superciliary ridges. The frontal bone is developed entirely in membrane from two completely separated portions, which grow from two centers of ossification in the frontal eminences; these centers, like those of the parietal bone, appear toward the end of the second month. Even in the new-born the two halves of the frontal bone are completely separated by the frontal suture (Fig. 105), which does not disappear until the second year of life and may sometimes be present in the adult, and is then also termed the metopic suture. At about the time it disappears the frontal sinuses begin to develop and they enlarge quite gradually until the time of puberty, when they increase more rapidly. THE ETHMOID BONE. The ethmoid bone (Figs. 70 to 73) forms the median portion of the nasal skeleton; and its cribrijorm plate aids in the formation of the floor of the anterior cerebral fossa. In the articulated skull the largest portion of the ethmoid is concealed by other bones; it is quite centrally placed and articulates with several of the cranial bones and with the majority of the facial bones. It has, as a whole, an irregularly cubical form, and presents a median and two lateral por- tions. The former consists of a small horizontal plate, the cribrijorm plate, and of a larger vertical plate, which consists of a small thickened portion situated above the cribriform plate, the crista galli (Fig. 71), and of a larger portion, the perpendicular plate, situated below the cribriform plate, which aids in the formation of the bony nasal septum (Fig. 73). If the median portion of the ethmoid bone be observed from in front or from behind, or, still better, in cross-sec- tion (Fig. 98), it will be seen to be shaped like a dagger, the handle of which is formed by the crista galli, the guard by the cribriform plate, and the blade by the perpendicular plate. Attached to the lateral margins of the lamina cribrosa are the two lateral masses, also termed the ethmoidal labyrinths, which are air-containing structures with thin bony walls, and form a part of the outer walls of the nasal fossz and a part of the inner wall of the orbit. The crista galli (Figs. 70, 71, and 73) is a pointed bony ridge situated in the sagittal plane; it is high in front and low behind, and gives attachment to the falx cerebri. The cribrijorm plaie (Figs. 69, 70, and 72) is an approximately rectangular plate situated between the cranial frontal spine Glabella Trochlear spine Superciliary arch Supraorbital margin [ ig. O8. / Thmot- Anterior ethmoidal foramen dal ° e ™ / lenressione Posterior ethmoidal foramen notch Ethmoidal depressions _ Supraorbital notch Depression for lachrymal gland , /, OY Cribriform plate Perpendicular plate of cthmoid bone J Pp Alar process Perpen- 3 } dicular Ss Crista galli i plate >> sy ' fs ~ 5 &. SE Lamina = ~ papy- = racea ~ , XQ Perpen- dicular proc piate Fig. 71. fe ig. 72. Sphenoidal turbinated bones THE BONES OF THE SKULL. 03 7 r and nasal cavities, and it consequently forms a portion of the roof of the nasal fossa. It pos- _ sesses a number of irregular rounded foramina, through which pass the olfactory nerves from the olfactory bulb, which rests upon the cribriform plate; the nerves for the most part continue their course downward in small bony grooves upon the nasal septum and the lateral nasal wall. The most anterior foramen, frequently incomplete, gives passage to the anterior ethmoidal vessels and nerve. In front of the crista galli, the cribriform plate sends out two small, somewhat quadrangular, bony platelets, the alar processes (Fig. 70), which pass toward the base of the frontal crest of the frontal bone and usually complete the foramen caecum posteriorly (Figs. 43 and 44). The cribriform plate is situated in the ethmoidal notch of the frontal bone and articulates posteriorly with the ethmoidal spine of the sphenoid bone. The perpendicular plate (Figs. 69 and 73) extends downward in the space between the two lateral masses and forms the anterior superior portion of the bony nasal septum. It is _ approximately pentagonal in shape. Its anterior superior border articulates with the frontal spine by the frontoethmoidal suture; its anterior inferior border is continuous with the cartilaginous nasal septum*; its inferior border articulates with the superior border of the vomer, which forms the remainder of the bony septum; its posterior border articulates with the sphenoidal crest of the body of the sphenoid bone by the sphenoethmoidal suture; and its superior border is received between two ridges upon the inferior surface of the cribriform plate. The ethmoidal labyrinths or lateral masses are paired structures. Their cavities are more or less completely subdivided by numerous fine bony platelets into the efhmeidal cells, which are only partially situated within the ethmoid bone and are frequently closed in by neighboring bones, particularly by the frontal. We may consequently distinguish the ethmoidal cells proper, i. ¢., those which are actually inclosed within the ethmoid bone by the lamina papyracea, from those which are closed in by the bones adjacent to the ethmoid (the frontal, lachrymal, sphenoidal, maxillary, and palatine cells). The external surface of the labyrinth forms a portion of the inner wall of the orbit (Figs. 95 and 96). It is quadrilateral in form, and, on account of its extreme thinness, is known as the lamina papyracea (Fig. 70), although it is also known as the os planum. In the orbital cavity it articulates anteriorly with the lachrymal bone, inferiorly with the maxilla, posteriorly with the palate bone (the orbital surface) and superiorly with the orbital plate of the frontal bone, the two ethmoidal joramina (see page 61) being situated either close to or actually in the fronto- _ethmoidal suture (Figs. 95 and 96). The margins of the adjacent bones aid more or less in - closing in the ethmoidal cells. a The internal wall of the ethmoidal labyrinth (Figs. 101 and 102) forms the upper portion ~ of the outer nasal wall, and from it two thin rough bony plates, whose free margins are slightly rolled up, project into the nasal fossa; these are the short superior and the longer middle turbinated bone (conche nasales superior et media), The anterior extremity of the middle turbinated bone articulates with the ethmoidal crest of the frontal process of the maxilla, while _ *In this situation the perpendicular plate is usually grooved for the attachment of the cartilage of the nasal septum; it is rarely placed exactly in the median line but usually deviates to one side. + These sutures have been previously noted and they will be considered in detail upon page 79. Aol — 64 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. its posterior extremity is attached to the similarly named crest of the palate bone. Between the superior and middle turbinated bones is situated the superior meatus of the nose, which is short and developed only in the posterior portion of the nasal fosse. Between the middle and inferior turbinated bones (the latter structure being an independent bone) is the middle meatus, in which, covered by the middle turbinated bone, there is a bulging of the ethmoidal wall, the ethmoidal bulla, a rudimentary turbinated bone, and another rudimentary turbinal (the os naso- turbinale of the mammalia) is the sickle-shaped uncinate process (Figs. 81 and 102), which is also covered by the middle turbinated bone. It articulates with a process of the inferior turbinated bone (see below) and helps to close the orifice of the maxillary sinus. Between the uncinate process and the ethmoidal bulla is a wide fissure, the infundibulum, which leads both into the orifice of the frontal sinus and into the ethmoidal cells; its orifice in the nasal fossa is known as the hiatus semilunaris (Fig. tot). The ethmoidal cells communicate partly with one another, partly with the air-cells of the adjacent bones, and in all cases, either directly or indirectly, with the nasal fossz. The ethmoid bone is completely preformed in cartilage. Ossification commences late (in the fifth month of em- bryonic life) and proceeds from the lamina papyracea and the middle turbinated bone. In the new-born, the two laby- rinths have already ossified as far as the superior turbinated bone, but they are not connected, since the cribriform and perpendicular plates do not possess ossific centers until the first year of life, when they gradually effect a bony union of the two labyrinths. The remainder of the perpendicular plate does not ossify until the fifth year. THE INFERIOR TURBINATED BONE. While the two upper turbinated bodies are portions of the ethmoid bone, the inferior one (concha nasalis injerior) (Figs. 79, 81, 82, and 98) is an independent structure and it is also the largest of the three. It is a thin roughened bony plate, the free margin of which is turned upon itself and slightly rolled up. It consists of a body and of three processes. The narrow, leaf-shaped body is placed in the sagittal plane. It is convex toward the nasal septum, concave toward the lateral nasal wall, broader in front than behind, and is provided with many depressions and small foramina. The anterior portion of the lateral border articulates with the conchal crest of the maxilla (Figs. 81, 101, and 102), and the posterior portion of this border is attached to the similarly named crest of the palate bone. The largest of the three processes is the maxillary process (Fig. 82), which is directed down- ward and outward, and closes a considerable portion of the orifice of the maxillary sinus (see Fig. to1). The /achrymal process (Figs. 61 and 82), passing forward and upward, articulates with the lower border of the lachrymal bone by the lachrymoconchal suture, and forms a portion of the wall of the nasal duct (nasolachrymal canal) (Fig. 79). The ethmoidal process (Figs. 81, 82, and 102) is directed upward and backward and articulates with the uncinate process of the ethmoid bone in the region of the orifice of the maxillary sinus. The inferior turbinated bone ossifies in immediate connection with the ethmoid bone in the fifth month of em- bryonic life. ? THE LACHRYMAL BONE. The /Jachrymal bone (Fig. 78) is an approximately rectangular bony plate, very thin and frequently even perforated, situated in the inner wall of the orbit between the frontal process of THE BONES OF THE SKULL. 65 the maxilla and the lamina papyracea of the ethmoid bone (Figs. 95 and 96). It articulates with the nasal portion of the frontal bone above, with the inferior turbinated bone below, and extends inward as far as the nasal fossa (the sutures are considered upon page 79). It presents an external or orbital surjace, and an internal or ethmoidal surjace, which is in contact with the ethmoid bone. The ethmoidal surface closes in the lachrymal cells, and a small portion of it aids in the formation of the outer nasal wall in the middle meatus, as it articulates with the lachrymal process of the inferior turbinated bone by the lachrymoconcha! suture (Fig. 1or). The anterior portion of the orbital surface exhibits a wide groove which, together with a similar groove on the frontal process of the maxilla, forms a depression for the lachrymal sac (see Fig. 77). The posterior boundary of this depression is the posterior lachrymal crest which extends downward into a hook-like process (bent up anteriorly), the hamudus lacrimalis (Fig. 78). This is situated in the lachrymal notch between the frontal process of the maxilla and the orbital surface of the body of the same bone (see page 67). The posterior portion of the orbital surface, situated behind the lachrymal crest, is smooth. [The lachrymal bone is formed by ossification of membrane and usually develops from a single center which appears during the third or fourth month of fetal life. Occasionally two centers appear, from one of which the hamulus develops, and more rarely a number of centers occur, in which case the bone is represented by a number of separate parts.—Ep.] THE NASAL BONE. The nasal bones (Figs. 86 and 87) are two flat, elongated, trapezoidal bones, which meet in the median line to form the bridge of the nose (Figs. 37 and 38). The internasal suture separates the short internal margins of the two bones, while the external margin of each, consider- ably longer, articulates with the frontal process of the maxilla by the nasomaxillary suture. The shorter and thicker superior margin is in contact with the nasal portion of the frontal bone by the nasofrontal suture; the longer and thinner inferior margin forms the upper boundary of the anterior nares (apertura pirijormis) and gives attachment to the cartilaginous nasal skeleton. The slightly concave inner (nasal) surface of each bone presents a groove, the efimoidal groove (Fig. 87), for the anterior ethmoidal nerve, and in the neighborhood of this are one or more fine foramina, the nasal foramina, leading to the slightly convex external surface of the 7 bone. Both the superior and inferior margins of the bone are usually irregularly serrated. E [Each nasal bone is developed from a single center of ossification which appears in membrane at about the third month of fetal life. At birth the length of the bones hardly exceeds their breadth.—Ep.] THE VOMER. _ The vomer (Figs. 73 to 75) of the adult skull is a flat single bone, approximately trapezoid in shape, which forms the inferior and posterior portion of the bony nasal septum (Fig. 73). Its upper end is thickened and spread out into two plates, the ale (Fig. 74), which articulate _ with the inferior surface of the body of the sphenoid bone in such a manner that the sphenoidal ‘rostrum is received between them, while the vaginal processes of the pterygoid process and pocied P ss 66 ATLAS AND TEXT-BOOK OF HUMAN: ANATOMY. Fic. 73.—The osseous nasal septum seen from the left side. The frontal, sphenoid, maxilla, and palate bones, and also the lamina cribrosa of the ethmoid and the ala vomeris, have been sawed through close to the median line. The ethmoid is yellow, the vomer (except the cut sur- face of the ala) pink. Fic. 74.—The vomer seen from behind (4). Fic. 75.—The vomer seen from the side (4). Fic. 76.—The right maxilla seen from the inner surface (4). Fic. 77.—The right maxilla seen from the outer surface (+). the sphenoidal process of the palate bone (see page 70) are applied to their margins. The posterior border of the vomer forms the sepium choanarum; the narrow anterior border articulates with the cartilaginous septum of the nose and the anterior portion of the nasal crest of the maxilla; the superior border is attached to the perpendicular plate of the ethmoid; and the inferior one is firmly fixed to the nasal crests of the maxilla and palate bone (Fig. 73). The vomer arises during the third month of fetal life as two plates situated one on either side of the upper part of the cartilaginous septum of the nose, which subsequently disappears, so that the two plates become adherent after birth, with the exception of the ale, which remain separated throughout life. THE MAXILLA. The maxilla (Figs. 76, 77, and 79) is a paired bone which forms the center of the facial skeleton, all portions of which are more or less intimately connected with it. It assists in the formation of the orbit and forms a considerable portion of the nasal fosse and of the roof of the mouth. It consists of a body and of four processes, the frontal or nasal process, the zygomatic process, . the palatine process, and the alveolar process. Of these, the alveolar process is directed downward and the frontal process upward, while the zygomatic and palate processes extend | in the hori- zontal plane, the former externally, the latter internally. The body of the maxilla is irregularly cubical, and contains a large cavity, the maxillary sinus (Figs. 76, 79, 97, and 98), also known as the antrum of Highmore. In the body there may be recognized four surfaces: the anterior, the nasal, the orbital, and the infratem poral. The actual facial surface of the bone, the anterior surjace (Fig. 77), is convex, and its superior border forms a portion of the infraorbital margin. - Below this margin is an irregular rounded opening, the injraorbital foramen (Figs. 37, 38, and 77), which gives exit to the vessels and nerves of the same name and is the termination of the infraorbital canal. Below the infra- — orbital foramen there is a depression, the canine jossa, which gives origin to the musculus caninus (levator anguli oris). The anterior border of the facial surface forms a portion of the lateral boundary of the apertura pirijormis (anterior nares), and at the infraorbital margin the surface becomes continuous with the triangular orbital surface, which articulates with the lachrymal, zygomatic, and ethmoid bones, but is separated from the greater wing of the sphenoid by the inferior orbital (sphenomaxillary) fissure (Figs. 95, 96, and 97). This is a smooth surface; it assists in forming the floor of the orbit, and exhibits a gradually deepening groove, the injra- orbital groove (Fig. 96), along which there is frequently to be observed an infraorbital suture. ’ “ Ve rtical portt ic f ‘ ‘* } “ Jrontal bone eq! 4 age Sphenoidal / eee Sphenoidal rostrum ’ . ov ; aQiagée vormeris Sunt Sphenoidal sinus (Body of sphen vd bone) Frontal sinus Nasofrontal suture Nasal bone if thy Perpendicular plate Ala vomeris frontal process of maxilla Pterygoid process Posterior nasal spine Fig. 74 Fig. 73. Palatine process Palate bone (horizontal portion) Incisive canal ! ) of maxilla Vomer é Alae vomeris “ Frontamaxillary suture i¢7 y ip i , jf / 4 7 f " choanarum 4 SS ZS - 7 Ethmoi- ' dal ° . + crest \ gos es Fig. 75 . x Conchal \ crest Wy | - Maxillary sinus Pterygopalatine groove alate process |) Frontal process (anterior » lachrymal 2 Ante. rior «© nasal spine Lachrymal border Lachrymal notch Infraorbital margin \ Tuberosity Orbital surface \ cr of maxilla ff acest) Infraorbital groove Infraorbital foramen Incisive canal Fig. 76. Infratemporal | , surface it Canine fossa , “Oe . Alveolar foramina ts \ Nasal notch f J ee Anterior . ° nasal | ats spine ¢ juga alveo- laria . £5 ee 4 a ne Ay acs 7 : “S al THE BONES OF THE SKULL. 67 The infraorbital groove gradually leads into a canal, the injraorbital canal, which runs to the injraorbital foramen. The inner margin of the orbital surface presents a notch, the lachrymal notch (Fig. 77), which accommodates the hamulus of the lachrymal bone. The injratem poral surjace (Fig. 77) is situated behind the zygomatic process, toward the infratemporal and sphenomaxillary fossw, and represents the posterior surface of the body of the maxilla. It bulges somewhat posteriorly, forming the ‘uberosity, and presents a plerygopala- tine groove (see page 79), and also from two to four small foramina, known as the alveolar jora- mina,* which transmit the nerves and vessels of the same name. The superior internal angle articulates with the orbital process of the palate bone. The nasal surjace (Fig. 76) forms the lower portion of the outer wall of the nasa! fossa; it exhibits a large irregular opening, the orifice oj the maxillary sinus. Above this orifice there are usually fosse and depressions which close in the incomplete maxillary cells of the ethmoid bone. Only a small part of the anterior portion of the nasal surface is exposed in the lateral nasal wall, the entire roughened posterior portion of this surface being concealed by other bones, namely the palate bone, the inferior turbinated bone, and the uncinate process of the cthmoid (Fig. 81), which considerably diminish the size of the orifice of the maxillary sinus (sce also page 69). Between the orifice of the sinus and the frontal process there is a deep groove, the lachrymal groove (Fig. go), which is converted into the nasolachrymal canal by the lachrymal bone and the lachrymal process of the inferior turbinated bone (see page 64). The transition of the nasal surface to the frontal process is indicated by a rough ridge, the conchal crest (Fig. 76), for the attachment of the anterior portion of the inferior turbinated bone (concha nasalis inferior) (see also page 64). The upper extremity of the frontal process articulates with the nasal portion of the frontal bone by the frontomaxillary suture; its inner margin is in contact with the nasal bone by the nasomaxillary suture, and its outer or lachrymal border is opposed to the lachrymal bone along the lachrymomaxillary suture (Figs. 37 and 38). It narrows as it passes upward and presents an external surface, forming the lateral portion of the bony nose, and an internal surface, directed toward the nasal cavity. This internal surface is separated from the nasal surface of the body of the bone by the conchal crest, and parallel to this structure is a less prominent ridge, the ethmoidal crest, for articulation with the anterior portion of the middle concha of the ethmoid bone. The external surface of the frontal process presents the lachrymal groove, which, together with the similarly named groove of the adjacent lachrymal bone, forms a depression for the accommodation of the lachrymal sac. The sharp anterior border of this fossa is called the anterior lachrymal crest (Figs. 77 and 95). The frontal process also forms the largest part of the lateral boundary of the apertura piriformis. The zygomatic process (Fig. 77) is broad, short, and three-sided, and terminates in a rough articular surface for the body of the zygomatic bone (zygomaticomaxillary suture). The maxil- lary sinus extends into the base of the process. pare These lead into small canals, the alveolar canals, which contain the nerves and vessels for the molar teeth and | the posterior alveoli, while the alveolar canals for the canine and incisor teeth proceed from the floor of the and run within the thin anterior wall of the body of the maxilla. 68 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 78.—The left lachrymal bone seen from its median surface (3). Fic. 79.—The lower half of the facial portion of the skull which has been divided horizontally, seen from above (4). Fic. 80.—The right maxilla and palate bone, seen from the inner surface (+). Fic. 81.—The right maxilla, palate bone, inferior turbinated bone and part of the ethmoid, seen from the inner surface (4). Fig. 82.—The inferior turbinated bone seen from its lateral surface (+). In Figs. 79 and 81 the maxilla is colored yellow, the sphenoid green, the palate bone blue, and the ethmoid orange. The zygomatic process forms the lower portion of the outer margin of the inferior orbital (sphenomaxillary) fissure, and is continued as a flat process, the orbital plate, upon the orbital surface of the body of the bone in such a manner that it forms the floor of the original infraorbital groove. In young subjects this orbital plate is always separated from the other bones by the z/raorbital suture, which is also frequently observable in the adult skull. The alveolar process is convex externally, concave internally, and contains eight of the six- teen upper teeth. It is directly continuous with the lower surface of the body of the bone, is sepa- rated from the frontal process by the nasal notch (Fig. 77), and forms the inferior and a portion of the lateral boundary of the apertura piriformis. Both alveolar processes are in contact in the median line in the intermaxillary suture, and their superior margins form the anterior extremity of the nasal crest and the anterior nasal spine. The free inferior margin of the process, the limbus alveolaris, contains the sockets (alveoli) for the roots of the teeth, and these are separated from each other by the interalveolar septa. The roots of the front teeth particularly cause the walls of the alveoli to project externally and in this manner produce the juga alveolaria (Fig. 77). The apices of the posterior alveoli are situated immediately beneath the maxillary sinus and are separated from it only by thin layers of bone (Fig. 98), and at the summit.of every alveolus is the orifice of an alveolar canal (see page 67). Posteriorly the alveolar process is directly continuous with the tuberosity, anteriorly with the palatine process. The palatine processes (Figs. 79 and 100) of the two maxillz articulate in the median line in the anterior portion of the middle palatine suture (Figs. 41 and 42) and form the largest portion of the hard palate. Each presents a slightly concave, relatively smooth nasal surface, which forms the floor of the nasal fossa, and a markedly concave, extremely rough palatine surface, which is directly continuous externally with the alveolar process. In the median line immediately behind the junction of the two alveolar processes each palatine process exhibits upon its palatine surface an incisive notch, and the corresponding notches of the two bones form the inferior opening of the incisive foramen (Fig. 100), which has two orifices into the nasal fossa, one on either side of the bony nasal septum (Fig. 78). The palatine surface (Fig. 100) also possesses rough longitudinal ridges and grooves, the palatine spines and grooves, the latter accommodating the vessels and nerves of the hard palate. Upon the nasal surface of the palatine processes the thickened and rolled up margins of the two bones unite in the median suture to form the nasal crest (Fig. 79), into which is inserted the inferior margin of the vomer. To either side of the anterior extremity of this crest is situated one of the nasal orifices of the incisive canal. Posterior , he lachrymai cre sf y Depression for lachrymalsac Vow -y ‘ Hamulus lacrimal: fig. 78. Nasolachrymal ’ larw sina J arin stthal ——* canal 4 Incisive foramen Nasal Apertura piriformis t/ y’ acnry- Ethmoidal crest ma ; _ oJ paule bone notch (C groove Sphenopalatine fu ; ’ : f THE BONES OF THE SKULL. 09 In the skull of the new-born and of the child the hard palate always shows an incisive suture, which is also frequently observed even in adult life (Fig. 100). In the fetus both the incisor teeth and their alveoli are situated in a special bone, the infermaslery home or os imed- sivum, which also forms the anterior portion of the hard palate. Although the portion of the incisive suture indicating the boundary between the intermaxillary bone and the alveolar process usually disappears before birth, the incisive suture upon the hard palate is maintained for a considerably longer time. The upper jaw is formed in membrane toward the end of the second fetal month, from four or five centers of ossi- fication, two of which form the intermaxillary bone and remain independent longer than the others, which usually unite as early as the fourth month of fetal life. The infraorbital suture is another indication of the complex origin of the maxilla. The upper jaw of the new-born is considerably flauer than the fully developed bone, and the alveolar process is entirely wanting, first appearing with the development of the teeth and not being completely formed until s considerably later period. The upper jaw contains a maxillary sinus even during fetal life. THE PALATE BONE. The palate bone (Figs. 83 to 85) is a flat paired bone, very thin in certain places, which is applied to the posterior portion of the maxilla and also articulates with the sphenoid (body and pterygoid processes) and with the inferior turbinated bones. It consists of two rectangular bony plates placed at right angles to each other, one, the horizontal plate, being in the horizontal, and the other, the perpendicular plate, in the sagittal plane. The palate bone also possesses three processes. The horizontal plates of the two palate bones form the posterior portion of the hard palate (Figs. 41, 42, and 100). They articulate with cach other in the posterior portion of the middle palatine suture, and with the palatine processes of the maxilla in the transverse palatine suture. At the posterior extremity of the median suture the two palate bones together form the posterior nasal spine (Figs. 83 and 100), as well as the posterior portion of the nasal crest upon the nasal surface of the hard palate (Fig. 78), and their posterior margins form the lower boundary of the choanx (Figs. 41 and 42). The rough palatine surface of the horizontal plate (Fig. 100), like the similar surface of the palatine process of the maxilla, exhibits palatine spines and grooves, and also presents, near the postero-external angle, the greater palatine joramen, one of the orifices of the plerygopalatine canal. The nasal surface (Fig. 79), however, is smooth and distinctly concave, like the corresponding surface of the palatine process of the maxilla. The perpendicular plate of the palate bone is narrower and thinner, but longer than the horizontal one. Its maxillary surjace (Fig. 84) is applied to the rough surface of the posterior portion of the nasal surface of the maxilla and also partly lies in front of and partly closes the orifice of the maxillary sinus. Its internal or nasal surjace (Fig. 85) forms the posterior portion of the lateral nasal wall (Figs. 101 and 102), and presents two horizontal parallel ridges, a distinct inferior one, the conchal crest (Fig. 85), for the attachment of the inferior turbinated bone (Figs. ror and 102), and a less pronounced superior one, the chmoidal crest (Fig. 84), for the middle turbinated bone. At the posterior border of the perpendicular plate there is a groove, the plerygopatatine groove (Fig. 84), which, with the similarly named grooves of the maxilla (see Fig. 76) and of the pterygoid process of the sphenoid bone (see Fig. 53), forms the plerygopala- tine canal, whose inferior extremity is the previously mentioned greater palatine joramen. In its vicinity are also the orifices of several smaller lateral ramifications, the palatine canals, most eee —eeE — 7° ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 83.—The right palate bone seen from behind (+). Fic. 84.—The right palate bone seen from the outer surface (4). Fic. 85.—The right palate bone seen from the inner surface (+). * = surface which completes the pterygoid fossa. Fic. 86.—The left nasal bone seen from the outer surface (+). Fic. 87.—The left nasal bone seen from its inner surface (4). Fic. 88.—The right malar bone seen from the outer surface (4). Fic. 89.—The right malar bone seen from the temporal surface (4). of which perforate the pyramidal process and end on the hard palate as the lesser palatine joramina. Of the three processes of the palate bone, the pyramidal process or tuberosity passes back- ward from the junction of the two plates of the bone, filling in the pterygoid notch of the ptery- goid processes of the sphenoid bone and completing the pterygod fossa. The other two processes, the orbital and the sphenoidal processes, are given off from the upper portion of the perpendicular plate above the ethmoidal crest, and are separated from one another by a deep notch, the sphenopalatine notch (Figs. 84 and 85). The inferior surface of the body of the sphenoid bone converts this notch into the spheno palatine joramen (Fig. 102), an important communication between the pterygopalatine (sphenomaxillary) fossa and the nasal cavity, which gives passage to vessels and nerves (see page 78). The orbital process (Figs. 83, 85, and 96) is the anterior and larger of the two processes, and is directed outward. Its upper surface forms the most posterior portion of the floor of the orbit, articulating with the lamina papyracea by the palatoethmoidal suture and with the orbital portion of the maxilla by the palatomaxillary suture. Its anterior surface is closely applied to the maxilla, while the internal one has an irregular boundary and articulates with the ethmoid labyrinth, where it assists in closing in some of the ethmoidal cells, the palatine cells. The orbital process is also in contact with the external surface of the body of the sphenoid bone by the sphenoorbital suture, and forms the posterior portion of the inner margin of the inferior orbital (sphenomaxillary) fissure. The thin posterior sphenoidal process (Figs. 83, 85, and 101), directed internally, is applied to the ala vomeris, to the inferior surface of the body of the sphenoid bone, and to the sphenoidal conch (sphenoidal turbinated bones), and also partly closes the orifice of the sphenoidal sinus. The palate bone is formed in membrane in the third fetal month and is already ossified at about the middle of the fetal life, but like the upper jaw it is rather short in the new-born. The orbital surface of the orbital process is sometimes unusually large, and the width of the perpendicular plate is subject to great individual variation. THE ZYGOMATIC BONE. The zygomatic or malar bones (Figs. 88 and 89) are three-sided, flat, strong bones which form the prominence of the cheek. They articulate with the frontal, sphenoid, and maxillary bones (Figs. 37 and 38), and also with the temporal bone by means of the zygoma which bridges over the temporal fossa (Figs. 39 and 40) (the sutures are described upon pages 37 and 8o). The small orbital plate, placed at right angles to the malar surface, assists in the formation of Orbital process Sphenoidal process Pterygopalatine groove Perpendicular plate Orbital Orbital process Sphenopalatine process Cutieimetaiiea anti notch ‘ Horizontal! plate id f Splenoidal Process —>- ae. \N Ethmoi- » i Sphenot- , 7 dal a, - f dal / crest ~~. = seen ) ; ts Process osterior Pyramidal y nasal spine eee @ proc €s$ s Maxillary surface Fig. 83. f Conchal orest Posterior nasal spine Pyramidal proce 2 Lesser palatine Pterygopalatine groove foramen (greater palatine foramen) Nasal foramen Ethmoidal groove Nasal foramen —* + ~* > Fig. 86. Fig. 87. ee re - ‘on {CO0-0 Ait J arts in he not ‘dal ( Irbital surface Zy ge matico-oroua Ie amna process Fronto- Orbital surface sphenotdal process Zyeomati Infra-orbital margin pu ivee © ° “orbital (For Zyg ymatico- Zygomatic emporal proc. of foramen r : maxilla Zygomatico- ) facial foramen Temporal process } co Fig. 88. = : Temporal process Temporal ante a Fig. 89. Malar surface ; ) ~ 4 THE BONES OF THE SKULL. 71 the orbit. The malar bone presents three surfaces, the facial or malar surjace, the posterior or temporal surjace, and the orbital surjace formed by the upper surface of the orbital plate. The orbital surjace is slightly concave and its anterior border forms part of the infraorbital margin (Fig. 95). It articulates with the orbital surface of the greater wing of the sphenoid bone, is usually separated from the orbital surface of the maxilla by the inferior orbital (spheno- maxillary) fissure, and forms a portion of the floor and of the outer wall of the orbit. Upon this surface is the zygomaticourbital joramen (Fig. 88), leading into a branching canal, whose external orifices are the zygomaticotemporal and zygomaticojacial foramina, although frequently these two canals are entirely independent of each other, in which case there are two zygomaticoorbital foramina (Fig. 88). The quadrilateral malar plate possesses a convex malar surface and a slightly concave temporal surface. It articulates by means of its anterior rough margin with the zygomatic process of the maxilla, and in common with the orbital plate it gives off the jrontosphenoidal process (Figs. 88 and 89), which passes upward, forming the outer margin of the orbit, and articulates with the zygomatic process of the frontal bone and the zygomatic border of the greater wing of the sphenoid bone. The femporal process passes posteriorly to form the zygoma by articulating with the zygomatic process of the temporal bone (Figs. 39 and 40). The sutures between the zygomatic and the adjacent bones have been previously noted (page 37), and will be reviewed in another place (page 80). The malar surface shows the zygomaticojacial joramen (Fig. 89); the temporal surface, the zygomaticotem poral joramen (Fig. 88). The zygomatic bone is formed in membrane and commences to develop about the beginning of the third fetal month from two separate centers of ossification. In rare instances the two portions of the bone are separated even in adult life by a suture which may be scen at about the middle of the bone. Since the bone is gradually pushed outward during its development and during the growth of the individual, it happens that in one-half of the specimens the orbital surface no longer forms one of the boundaries of the inferior orbital (sphenomaxillary) fissure. THE MANDIBLE. The mandible (Figs. go to 93) is a single bone, and is the only bone of the skull which is connected to the remaining bones by a joint instead of by sutures. It consists of two main portions, a body and two rami. The upper end of each ramus is composed of two processes, an anterior pointed coronoid process and a posterior rounded condyloid process (Fig. 93), the two being separated by the notch oj the mandible (sigmoid notch). The body of the mandible is an approximately paraboloid bony plate from the posterior extremities of which the rami pass vertically upward. Its inferior margin is termed the base of the mandible; the superior margin is the alveolar portion, and contains, in the adult, sixteen dental alveoli for the lower teeth, which are separated from each other by the interalveolar septa. The free margin of the alveolar process is called the alveolar border, and the roots of the teeth, particularly those of the front ones, expand the thin bony mass of the process and produce longitudinal ridges upon the surface of the bone, the a/veolar juga (Fig. go). The middle of the external surface of the body of the mandible exhibits a rough projection, the menial protuberance (Fig. 90), which marks the union of the orginally separate halves of the bone (Fig. 89), and to either side of this projection and toward the base of the mandible 72 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 90.—The mandible seen from in front (3). Fic. 91.—The mandible seen from the outer surface (4). Fic. 92.—The mandible seen from below (}). Fic. 93.—One-half of the mandible seen from the inner surface (4). Fic. 94.—The hyoid bone seen from in front and above (+). is the mental tubercle. Above and to the outer side of the mental tubercle is situated the mental joramen, giving exit to the vessels and nerve of the same name and forming the inferior opening of the mandibular (inferior dental) canal, which traverses the greater portion of the body of the mandible. There is also to be observed upon the outer surface of the body a smooth ridge, the oblique line, which passes downward from the root of the coronoid process, gradually fades away, and finally entirely disappears somewhat to the outer side of the mental foramen (Figs. go and gr). The internal surface of the body of the mandible (Figs. 92 and 93) exhibits, to either side of the median line, a shallow depression which is known as the digastric jossa, since it received the insertion of the anterior belly of the digastric muscle, and above this there is a short, rough, irregular prominence, the mental spine, which is usually a paired structure and sometimes also shows a further transverse subdivision; it gives origin to the geniohyoid and geniohyoglossus muscles. To the outer side of the mental spine there is a larger shallow depression which lodges the sublingual salivary gland, and between the sublingual and digastric fosse is the termination of the rough mylohyoid line, which passes from behind forward and from above downward upon the inner surface of the body of the mandible and gives origin to the mylohyoid muscle. A certain distance below the mylohyoid line there is a groove which commences at the mandibular joramen (Figs. 92 and 93) situated upon the inner surface of the ramus, and gradu- ally disappears as it passes forward; this is the mylohyoid groove and contains the vessels and nerve of the same name. Below the mylohyoid line, to the outer side of the depression for the sublingual gland, and frequently difficult of recognition, there is a much shallower depres- sion for the submaxillary gland. Each ramus forms almost a right angle with the body of the bone, and is both broader and thinner than the body. It passes upward, broadens, and divides into two processes, an anterior coronoid and a posterior condyloid process, which are separated by the notch of the mandible (the sigmoid notch). The ramus, like the body of the bone, possesses an external surface and an internal surface; a portion of the latter being directed toward the oral cavity. The external surface (Fig. 96) is roughened at the angle, forming the masseteric tuberosity for the insertion of the masseter muscle. There is a corresponding rough area upon the inner surface, the plerygoid tuberosity, for the insertion of the internal pterygoid muscle. At about the middle of the ramus there is an opening, the mandibular (injerior dental) joramen (Fig. 93), the superior opening of the mandibular (injerior dental) canal,* which passes * The mandibular canal is continued within the bone beyond the mental foramen almost to the median line and — gives off small lateral ramifications which lead to the apices of the alveoli. Coronotd process Pterygoid depression Buccinator crest fuga alveolaria Ramus Oblique line Angle Mental foramen fig. 90 ‘g. 90. Mental tubercle Mental protuberance ee Body Notch of the mandible Coronoid process Pterygoid depression Head of condyloid process Alveolar border . -_! : Ramus Fig. 91. Angle (masseteric tuberosity) Mental foramen a w) -\ ' wv 4 Fig. 94. Lingula Mandibular Mylohyoia groove loramen Angle Oe (Pterygoid tuberosity) Angle My hy 3 i f Submaxillary depression Fig. 92. Sublingual depression Coronoid Se ads : process = Fig. 93. Mylohyoid groove Submaxillary depression Mylokyoid ‘simt Digastric fossa. Mental spine Sublingual depression THE BONES OF THE SKULL. 73 - obliquely through the mandible to the mental foramen and transmits the inferior dental vessels and nerve. A thin tongue-shaped bony plate, the /ingula, overhangs the anterior margin of the foramen. The coronoid process is flattened from side to side and terminates in a more or less sharp apex which gives attachment to the temporal muscle. In the prolongation of its anterior mar- gin runs the previously described oblique line, and passing from its base to the region of the last molar tooth is a ridge, the buccinator crest (Fig. 93), for the origin of the buccinator muscle. The condyloid process terminates above in a condyle, whose head (Fig. 91) is separated from the base of the process by a constriction known as the neck (Fig. 92). The articular surface itself is ellipsoidal and its longitudinal axis is placed almost transversely, although directed somewhat posteriorly, so that the condyloid process, in contrast to the coronoid, is compressed from before backward. Upon the anterior surface of the neck of the condyle there is a shallow pterygoid depression, which receives part of the insertion of the external pterygoid muscle. The lower jaw is formed in membrane about Meckel’s cartilage, a cartilage of the visceral skeleton which marks the position of the adult mandible. The first center of ossification appears in the second fetal month upon both sides external to Meckel’s cartilage; a second center appears above the first, and the two unite in such a manner that they form a groove which is open above for the reception of the tecth. Even at birth the two halves of the mandible are usually separated by a synchondrosis, and they do not unite until the first year. The condyloid process is preformed in cartilage and is developed by the direct transformation of the cartilage into bone. The lower jaw of the new-born is very low, possesses no alveolar portion, and the ramus is still but poorly developed and forms a very obtuse angle with the body. THE HYOID BONE. The hyoid bone (Fig. 94) is a small horseshoe-shaped structure situated in the base of the _ tongue; it does not articulate with the skull but is connected with it by the stylohyoid ligament. It consists of a body, from either side of which proceed the greater and the lesser cornua. The body is slightly curved horizontally, the anterior surface being rough and slightly convex, the posterior one smooth and slightly concave. The greater cornua are long and thin and are connected to the body either by bony tissue or by cartilage, more rarely by fibrous connective _ tissue or by a joint. They pass horizontally outward from the body of the bone, and are directed backward and usually slightly upward, their ends exhibiting a bulbous thickening. The Jesser _ cornua are frequently cartilaginous, and arise close to the bases of the greater ones; they are directed upward, however, and also outward and backward. They are much shorter than the greater cornua and are connected with the styloid process of the temporal bone by the stylo- hyoid ligament. The nature of their attachment to the hyoid bone is subject to considerable The hyoid bone is preformed in cartilage and arises chiefly from the second branchial arch (the hyoid arch), the iter cornua, however, representing the third arch. The body (two centers) and the greater cornua commence to at birth, the lesser cornua at a much later period. Sometimes the lesser cornua extend far into the stylohyoid ent (see page r19Q), just as the styloid process does, the two bones having a common embryonic origin. THE we 74 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 95.—The left orbit seen from in front (+). Fic. 96.—The median wall of the left orbit, the outer wall having been removed (4). Fic. 97.—The outer wall of the right orbit, the median one having been removed (+). In all these figures the frontal bone is violet; the ethmoid orange; the lachrymal pink; the sphenoid green; the nasal, parietal, and zygomatic bones white; and the palate bone blue. foramen. Its base is a quadrangle with rounded corners, and forms the entrance to the cavity (aditus orbite). The four walls of the orbit are designated the superior, the internal, the external, and the inferior. Since there is no sharp dividing-line between the superior and internal and between the internal and inferior walls, and also since such a dividing-line is partly absent between the external and superior wall, the pyramidal orbital space possesses for the most part no sharp angles; indeed, posteriorly the pyramid has practically but three sides. Each orbit is formed by seven bones: the frontal, the sphenoid, the ethmoid, the lachrymal, the maxilla, the zygomatic, and the palatine. The sutures between these bones are described on pages 79 and 80. The upper wall or the roof of the orbit (Fig. 95) is formed by the orbital portion of the frontal bone, and in the posterior portion also by the lesser wing of the sphenoid bone. It is horizontal, smooth, and slightly concave. The inner wall (Fig. 97) is formed anteriorly by the lachrymal bone and posteriorly by the lamina papyracea of the ethmoid bone and by a small portion of the ala parva of the sphenoid (near the junction of the inner wall with the roof). Below the lamina papyracea, the orbital surface of the maxilla extends upward from the floor upon the inner wall, and its frontal process also forms a narrow portion of the inner wall, internal to the lachrymal bone and immediately adjacent to the internal orbital margin. The inner wall of the orbit is approximately vertical and its anterior portion exhibits the fossa for the lachrymal sac. . The floor of the orbit (Fig. 99) passes quite gradually into the inner wall, and its posterior portion is separated from the largest (posterior) portion of the outer wall by the inferior orbital (sphenomaxillary) fissure. Its greatest portion is formed by the orbital surface of the maxilla, only a small posterior portion being formed by the orbital process of the palate bone. In the anterior portion of the orbit the zygomatic bone also forms a narrow strip of the floor, but the extent to which it takes part is subject to considerable variation (see page 71). The inferior orbital wall is quite smooth and is almost exactly horizontal (slightly inclined outward, forward, and downward). The outer wall of the orbit (Fig. 97) is the most isolated of all, since the two orbital fissures separate from it the remaining walls in the posterior portion of the orbit. The inferior orbital (sphenomaxillary) fissure separates more than half of the length of the outer wall from the floor, and one-third of its extent is separated from the roof by the superior orbital (sphenoidal) fissure. It is practically formed by two bones, the orbital surface of the greater wing of the sphenoid bone contributing the posterior portion, and the orbital surface of the zygomatic bone the anterior portion. The latter portion, however, also contains a part of the orbital portion of the frontal bone, which extends downward more or less from the roof. The outer wall of the orbit is slightly oa’ Antcrior lachrymal crest Fronial bone Lad Nasal bone smducs x Fi r O45, Nasolachry- mal canal ost. lachrymal crest lnfraorbital groove Zygomatic proces3 l rhit . ‘ ee SP See - THE BONES OF THE SKULL. 75 concave and is not exactly vertical, but directed somewhat from above downward and from without inward. The margins of the orbit are known as the supraorbital and the infraorbital. They are, of course, connected at their extremities by the lateral walls of the orbit. The supraorbital margin (Fig. 96) is usually sharper than the inferior one; it is formed by the frontal bone (the vertical plate and the zygomatic process) and contains one shallow notch or two deeper ones, the supraorbital and jrontal notches or joramina (Fig. 67), which trans- mit the frontal and supraorbital vessels and nerves. The frontal bone extends lower down internally than it does externally. The infraorbital margin (Fig. 99) is formed internally by the maxilla, and externally by the zygomatic bone, these bones extending internally and externally as far as the frontal bone. A portion of the internal margin (Fig. 97) is furnished by the anterior lachrymal crest of the frontal process of the maxilla, and its smoothest portion is situated above this crest. The external margin (Fig. 97) is formed by the zygomatic bone, particularly by its frontosphenoidal process. The following foramina and fissures lead either into or from the orbit: 1. The optic joramen (Fig. 96), situated in the root of the lesser wing of the sphenoid bone, leads from the cranial cavity to the apex of the orbit and transmits the optic nerve and the ophthalmic artery. 2. The superior orbital (sphenoidal) jissure (Fig. 95), between the greater and lesser wing of the sphenoid, also leads from the cranial into the orbital cavity and transmits the ophthalmic, oculomotor, trochlear, and abducens nerves and the superior ophthalmic vein. This fissure separates the outer from the upper wall of the orbit. Its internal portion is wide; its external portion is narrow and closed by a membrane. 3. The injerior orbital (sphenomaxillary) fissure (Fig. 95), between the maxilla and the orbital process of the palate bone on one side and the greater wing of the sphenoid bone or the greater wing and the zygomatic bone on the other, leads from the pterygopalatine (sphenomax- illary) fossa into the orbital cavity and transmits the infraorbital vessels and nerve. It separates the outer wall from the floor of the orbit and is larger antero-externally than it is postero- internally. The external boundary of the fissure is furnished by the crista orbitalis of the greater wing of the sphenoid bone. 4. The superior opening of the nasolachrymal (nasal) canal (Fig. 99), in the fossa for the : lachrymal sac; this canal leads from the orbital into the nasal cavity and transmits the naso- ~ lachrymal (nasal) duct. 5. The anterior ethmoidal joramen (Figs. 95 and 96), passing from the orbital to the cranial cavity and transmitting the anterior ethmoidal vessels and nasal nerve. %. 6. The posterior ethmoidal joramen (Figs. 95 and 96), leading into the nasal cavity and transmitting the posterior ethmoidal vessels. Both this and the preceding foramen are situated in or to one side of the frontoethmoidal suture in the inner wall of the orbit. 7- The sygomaticoorbital joramen or joramina (Fig. 97), in the outer wall of the orbit, pass through the malar bone to the temporal fossa and to the face, and transmit the nerves and vessels _of the same name or their branches. 8. The entrance of the injraorbital canal (for the vessels and nerve of the same name), i, 76 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 98.—A frontal section through the anterior part of the skull, showing the orbits, the nasal fossz, and the maxillary sinuses (4). Fic. 99.—The floor of the left orbit seen from above, the roof having been removed (4). Fic. 100.—The maxilla, palate bone, and lower ends of the pterygoid process of the sphenoid, seen from the oral surface (the hard palate) (4). leading to the infraorbital foramen, is situated in the floor of the orbit. It commences at the inner end of the inferior orbital fissure as the infraorbital groove (Fig. 99). 9. The frontal and supraorbital foramina, situated in the supraorbital margin. The orbit contains the following depressions or fosse: 1. The fossa for the lachrymal gland (Fig. 69), on the frontal bone beneath the outer portion of the supraorbital margin. 2. The trochlear depression (Fig. 68), also on the frontal bone, where it passes into the inner wall of the orbit, for the attachment of the pulley of the superior oblique muscle. 3. The jossa for the lachrymal sac (Fig. 99), situated in the inner wall of the orbit between the anterior lachrymal crest of the frontal process of the maxilla and the posterior lachrymal crest of the lachrymal bone. The only groove in the orbit is the zujraorbital groove (Fig. 98), upon the orbital surface of the body of the maxilla. There are several projections into the orbital cavity. These are the anterior and posterior lachrymal crests which form the fossa for the lachrymal sac, and a bony spine upon the greater wing of the sphenoid bone near the outer margin of the superior orbital fissure, the spine jor the external rectus muscle (Fig. 99). The frontal bone occasionally presents a trochlear spine alongside of the trochlear depression. The orbital walls vary greatly in their thickness. The thinnest wall is the inner one, both in the region of the lamina papyracea of the ethmoid bone and also in that of the lachrymal bone, the latter bone even being sometimes defective. The roof of the orbit not infrequently contains a portion of the frontal sinus, in which case it is hollow. The outer wall is usually the thickest. . THE NASAL CAVITY. The bony nasal cavity (Figs. 99, 101, and 102) is subdivided into two symmetrical nasal fossze by the nasal septum, which is frequently oblique and not exactly in the median sagittal plane. The cavity is highest just behind the anterior nares and gradually becomes lower toward the posterior nares, and nine of the bones of the skull—the nasal, frontal, ethmoid, sphenoid, maxilla, palate, inferior turbinated, lachrymal, and vomer—take part in its formation. In each nasal fossa there may be recognized a roof, a floor, an internal wall, and an external wall. The anterior opening of the two bony nasal fossee is known as the apertura pirijormis (anterior nares), while the posterior opening of each is the choana. The former (Figs. 37 and 38) is bounded by the nasal bones and by the frontal processes and bodies of the maxilla, while each choana (posterior naris) (Figs. 41 and 42) is bounded by the palate bone, the internal plate of the pterygoid process, and the body of the sphenoid bone. The roof of the nasal cavity is formed anteriorly by the two nasal bones and by the nasal portions of the frontal bones, in the middle by the Greater wing of sphenotd Perpend Ethmoidal He lito Riisais) Maxillary sinus ’ Vomer aeey ¢ Alveolar process of maxilla Inferior Middle > - turbinated ‘urbinated ' Tooth bone a \- Inferior nasal meatus fr O8 Fig. 98. ;‘ niernoal iors. External ptery- ‘ternal ptery Horizontal * , goid piale goid plate Pyra:nidal proc. of palate bone Inferior orbital JSissure Greater wine j of sphen Ethmoidal Pal cells fToO Lamina papyracea Fig. 100. Depression for lachry-_ mal sac (nasolachry- mal canal) Zygomaticomaxillary sutare Infraorbital groove Fig. 99. ree THE BONES OF THE SKULL. 77 cribriform plate of the ethmoid, and posteriorly by the body of the sphenoid. It is curved so that its anterior and posterior portions also form, so to speak, an anterior and a posterior wall. The floor of the nasal fossa (Fig. 79) is formed by the upper surface of the hard palate, composed of the palatine processes of the maxilla and the horizontal plates of the palate bones. The internal or median wall is smooth and of simple composition, the anterior portion being incomplete in the bony skeleton. The external wall is extremely complicated. The median wall (Fig. 72) is the nasal septum, the antero-superior portion of which is formed by the perpendicular plate of the ethmoid bone, the postero-inferior portion by the vomer. It is attached above to the frontal crest of the frontal bone, below to the nasal crest of the hard palate, and behind and above to the sphenoidal crest and rostrum. The external nasal wall (Figs. ror and 102) exhibits three peculiar foliate prominences the free margins of which are rolled up upon themselves; these are the furbinated bones or conche nasales. The inferior of these is an independent bone, the concha nasi injerior. It is the largest and longest of the turbinated bones, while the superior is the smallest and shortest. The superior and middle turbinated bones are processes of the ethmoid bone. The outer portion of each nasal fossa is divided into three canals by the three turbinated bones: the superior meatus, between the superior and middle turbinated bones; the middle meatus, between the middle and inferior turbinated bones; and the injerior meatus, between the inferior turbinated bone and the floor of the nasal fossa. Above the superior turbinated bone in the superior meatus is situated a cleft-like recess known as the sphenoethmoidal recess. The portion of the nasal fossa situated between the inner margins of the turbinated bones and the nasal septum is termed the common meatus oj the nose; the posterior portion situated behind the posterior extremities of the turbinated bodies is known as the naso- pharynx or naso- pharyngeal meatus. The external nasal wall is formed by the following bones: the ethmoid (superior posterior portion); the nasal surface of the frontal process of the maxilla (superior anterior portion) and the nasal surface of the body of the bone (inferior anterior portion); the vertical plate of the palate bone (posterior inferior portion); the inferior turbinated bone (inferior middle portion); and the inner surface of the lachrymal bone (quite a small portion in the anterior part of the middle meatus). © In addition to the main nasal cavity there is a series of accessory cavities; these are the _ air-containing cavities of the majority of the cranial bones, particularly of the maxilla, frontal, sphenoid, and ethmoid. There is a large number of openings leading into the nasal cavity. (a) The foramina of the cribriform plate of the ethmoid bone in the roof of the nasal cavity, transmitting the olfactory nerves and the anterior ethmoidal vessels and nerves. (b) The superior orifice of the incisive canal (Fig. 79), on either side of the nasal crest in the floor of the nasal cavity, which transmits the terminations of the anterior palatine vessels and nerve. (c) The inferior orifice of the nasolachrymal canal in the inferior meatus, which contains the nasolachrymal duct. ; 78 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 101.—View of the lateral wall of the right nasal fossa, the nasal septum having been removed (4). Fic. 102.—View of the lateral wall of the right nasal fossa, the middle turbinated bone having been removed (4). In these figures the frontal bone is violet, the lachrymal pink, the ethmoid orange, the maxilla yellow, the palatine blue, the sphenoid green, and the other bones white. Fic. 103.—The left pterygopalatine fossa seen from the side, after the removal of the zygomatic bone (4). The maxilla is yellow, the palate bone blue, the sphenoid green, and the zygomatic and temporal bones white. (d) The hiatus semilunaris (Fig. 101), in the middle meatus in the region of the infundib- ulum, which leads to the orifice of the frontal sinus (Fig. 102) and to the openings of the anterior ethmoidal cells; the middle meatus also contains the orifice of the maxillary sinus. (e) The openings of the middle and posterior ethmoidal cells in the superior meatus. (j) The upper and posterior portion of the nasal cavity contains the sphenoethmoidal recess, the orifice of the sphenoidal sinus (Fig. 102), the small posterior ethmoidal foramen (leading into the orbital cavity and transmitting the vessels of the same name), and the spheno- palatine foramen (Fig. 102), which accommodates the ganglion and vessels of the same name and communicates with the pterygopalatine (sphenomaxillary) fossa. THE ROOF OF THE ORAL CAVITY, THE HARD PALATE. The roof of the oral cavity (Fig. 100) is formed by the hard palate. It is a markedly concave elliptical bony plate, composed of the palatine processes of the maxilla and of the horizontal portions and of part of the pyramidal processes or tuberosities of the palate bones. It presents in the median line the median palatine suture, upon which a bony swelling, the torus palatinus, is occasionally observed; it also contains the transverse palatine suture and sometimes the * remains of the incisive suture. At the anterior extremity of the median suture is situated the single incisive foramen, by which the bony oral cavity communicates with both bony nasal fossee; posteriorly in the horizontal plate of each palate bone is the greater palatine foramen, and the pyramidal process contains the lesser palatine foramina (inconstant). All these foramina are the orifices of the pterygopalatine canal. THE PTERYGOPALATINE FOSSA. The pterygopalatine .or sphenomaxillary fossa (Fig. 103) lies between the anterior surface of the pterygoid process of the sphenoid bone, the perpendicular portion of the palate bone, and the posterior extremity of the maxilla. It is funnel-shaped and is continued directly downward into the pterygopalatine canal, which is bounded by the same three bones. It opens out supe- riorly into the inferior orbital (sphenomaxillary) fissure which communicates with the orbit and externally the pterygomaxillary fissure connects the pterygopalatine with the infratem-- poral fossa. Opening into the pterygopalatine fossa are the foramen rotundum, by which it communicates with the cranial cavity, the pterygoid canal, which passes horizontally backward in the root of the pterygoid process, and the sphenopalatine foramen, leading into the nasal cavity. The fossa contains the sphenopalatine ganglion of the maxillary nerve as well as arteries and veins. Supertor turblnated bone Frontal SINUS Crista galli Nasal bones Middle [ u / ‘bi fl ‘ 2 lé il bone 4), Saou | Incisive a} " / Canat Frontal sinus Orifice a 1d istse$ Orifice of; frontal sinus Nasal bone Spi SLU“S Widdle tar binated bone Orifice front, Sinus Uncinate proc. Orific r of - maxillary SimBs Anterior nasal spine | y ~- - , « vr ‘ et a — Ethmoidal proccss of inferior turbinated bon: Incisive canal THE BONES OF THE SKULL. 79 The pterygopalatine canal, proceeding from the pterygopalatine fossa, is formed by the union of the pterygopalatine grooves of the pterygoid process and of the palate bone and maxillary bone; it gives off fine canaliculi which pass to the nasal cavity, and finally subdivides into a number of canals which terminate in the palatine foramina. THE INFRATEMPORAL FOSSA. The injratemporal (zygomatic) jossa (Fig. 103) has only a partial bony boundary, and is directly continuous above with the temporal fossa at the infratemporal crest of the greater wing of the sphenoid bone. It is situated between the infratemporal surface of the greater wing of the sphenoid bone, the infratemporal surface and tuberosity of the maxilla, and the external plate of the pterygoid process. It has no external or posterior boundary. THE SUTURES OF THE SKULL. The sutures of the skull are subdivided into the long sutures of the cranial vertex and the short sutures between the remaining cranial bones. The long sutures are named according to their shape, the shorter ones according to the bones which they separate. Several separate sutures are frequently grouped together and named as a single suture; for example, the fronto- ethmoidal suture. The coronal suture (Figs. 37 to 40) is situated between the parietal margins of the frontal and the frontal margins of the parietal bones. The sagitial suture (Figs. 45 and 46) is situated between the sagittal margins of the two parietal bones. The lambdoid suture (Figs. 39, 40, 45, and 46) is situated between the occipital margins of the parictal bones and the lambdoid margin of the occipital. The squamosal suture (Figs. 39 and 40) is situated between the squamous margin of the _ parietal bone and the parietal margin of the squamous portion of the temporal. The occipitomastoid suture (Figs. 39 and 40) is situated between the occipital margin of the mastoid portion of the temporal bone and the mastoid margin of the squamous portion of the occipital. It frequently contains the mastoid foramen. The parietomastoid suture (Figs. 39 and 40) is situated between the mastoid angle of the parietal bone and the parictal notch and a part of the mastoid portion of the temporal bone. The sphenoparietal suture (Figs. 39 and 40) is situated between the sphenoidal angle of the parietal bone and the parietal angle of the sphenoid bone. The sphenojrontal suture (Figs. 39 and 40) is situated between the frontal margins of the _ greater and lesser wings of the sphenoid bone and the orbital portion of the frontal bone. The sphenoorbital suture is situated between the anterior margin of the external surface of e body of the sphenoid bone and the orbital process of the palate bone. The sphenoethmoidal suture is situated between the crest of the sphenoid bone and the aay erior margin of the perpendicular plate of the ethmoid. » vi nf ; bh 80 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The sphenosquamosal suture (Figs. 39 and 40) is situated between the squamous margin of the greater wing of the sphenoid bone and the sphenoidal margin of the temporal bone. The jrontoethmoidal suture (Figs. 37, 38, 43, and 44) is situated between the inner margin of the orbital portion of the frontal bone (the outer margin of the ethmoidal notch) and the outer margin of the cribriform plate of the ethmoid, between the posterior margin of the nasal portion of the frontal bone and the anterior margin of the cribriform plate (foramen cecum), and also between the upper margin of the lamina papyracea of the ethmoid and the inner margin of the orbital portion of the frontal bone. The latter portion of the suture is in the inner wall of the orbit and frequently contains the ethmoidal foramina (Fig. 96). The nasojrontal suture (Figs. 37 and 38) is situated between the nasal portion of the frontal bone and the upper margin of the nasal bone. The internasal suture (Figs. 37 and 38) is situated between the inner margins of the two nasal bones. The jrontomaxillary suture (Figs. 37, 38, and 9s) is situated between the nasal portion of the frontal bone and the frontal process of the maxilla. The jrontolachrymal suture (Figs. 37 and 38) is situated between the orbital portion of the frontal bone and the upper margin of the lachrymal bone. The zygomaticojrontal suture (Figs. 37 to 40) is situated between the frontosphenoidal process of the zygomatic bone and the zygomatic (external angular) process of the frontal. The sphenozygomatic suture (Figs. 39 and 4o) is situated between the zygomatic margin of the greater wing of the sphenoid and the zygomatic bone. The zygomaticotemporal suture (Figs. 39 to 42) is situated between the temporal process of the zygomatic bone and the zygomatic process of the temporal bone. The zygomaticomaxillary suture (Figs. 37 and 38) is situated between the zygomatic bone and the zygomatic process of the maxilla. The nasomaxillary suture (Figs. 37 and 38) is situated between the frontal process of the maxilla and the outer margin of the nasal bone. The ethmoideomaxillary suture is situated at the junction of the inner wall with the floor of the orbit and separates the lower margins of the lamina papyracea of the ethmoid bone from the orbital surface of the body of the maxilla. The lachrymoconchal suture is situated between the lachrymal process of the inferior tur- binated bone (concha nasalis inferior) and the lachrymal bone. The lachrymomaxillary suture (Figs. 39 and 40) is situated in the inner wall of the orbit between the lachrymal margin of the maxilla and the anterior (and inferior) margin of the lachrymal bone. The lachrymoethmoidal suture is situated in the inner wall of the orbit between the lachrymal _ bone and the lamina papyracea of the ethmoid. The intermaxillary suture (Figs. 37 and 38) is situated between the alveolar processes of the two maxille. The palatomaxillary suture, in the floor of the orbit, is situated between the posterior margin of the orbital surface of the maxilla and the orbital process of the palate bone. The palatoethmoidal suture is situated immediately alongside of the preceding suture F THE BONES OF THE SKULL. 8r between the posterior extremity of the lamina papyracea of the ethmoid and the orbital pro- cess of the palate bone. The median palatine suture (Figs. 41, 42, and 100) traverses the hard palate in the median line. The éransverse palatine suture (Figs. 41, 42, and 100) is situated between the palatine proc- esses of the maxill and the horizontal portions of the palate bones. The following sutures are inconstant: the injraorbital suture (see page 66), the incisive suture (see page 69), the petrosquamosal suture (see page 54), the squamosomastoid suture (sec page 53), the sphenomaxillary suture (between the pterygoid process and the body of the max- illa), the frontal or metopic suture (see page 60), and the suéura mendosa (sce page 47). The petroocci pital and sphenopetrosal fissures are filled with fibrocartilage (petroocci pital and spheno petrosal synchondroses *). THE SKULL OF THE NEW-BORN. The skull of the new-born (Figs. 104 to 106) differs in many respects from that of adult life (see the development of the individual bones of the skull). The vertical plate of the occipital bone still exhibits the su/ura mendosa (Figs. 105 and 106) and is separated from the lateral por- tions by the posterior intraocci pital synchondrosis; the lateral portions are separated from the basilar portion by the anterior intraocci pital synchondrosis. ‘The two halves of the body of the sphenoid are still separated by the intersphenoidal synchondrosis and the sphenoocci pilal syn- chondrosis separates the sphenoid from the occipital bone. In the temporal bone may be observed the ¢ym panic annulus, one of the most striking forma- tions of the skull of childhood, and also the sguamosomastoid suture, which still completely sepa- rates the squamous and the petrous (together with the mastoid) portions. The two halves of the frontal bone are separated by the frontal suture, and the incisive suture is still visible in the maxilla, that is to say, in the hard palate. The maxilla and the mandible are still quite differently shaped from the adult structures, and the latter bone exhibits a median suture. The ethmoidal labyrinths are independent of cach other. But most striking is the incomplete ossi- fication of the cranial vault. In the lines of the sutures there are more or less narrow mem- branous connections of the contiguous bony margins, which form large spaces particularly in those situations where several sutures come together. These spaces are known as the jontanelles or fonticuli, and six of them may be recognized, two of which are single and two double: 7 1. The jrontal or anterior jontanelle (Fig. 105) is the largest of all and is quadrangular in shape, the short diagonal being situated in the transverse and the long diagonal in the sagittal _ direction. It occurs at the junction of the frontal, sagittal, and coronal sutures, between the _ two halves of the frontal bone and the two parietal bones. 2. The occipital or posterior fontanelle (Fig. 105) is small and triangylar, and is situated at the junction of the sagittal and lambdoid sutures, between the two parietal bones and the er aah portion of the a bone. * True synchondroses exist in the skull only during childhood. 82 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 104.—Skull of a new-born child from the side (4). Fic. 105.—Skull of a new-born child from above (3). Fic. 106.—Skull of a new-born child from behind and below (3). 3. The two sphenotdal fontanelles (Fig. 104) are of medium size, irregular in form, poorly defined, and situated between the parietal angles of the greater wings of the sphenoid bones and the sphenoidal angles of the parietal bones, in the location of the later-developed spheno- parietal sutures and the contiguous bony margins. 4. The two mastoid jontanelles (Fig. 106) are situated between the mastoid angles of the parietal bones and the parietal notches of the temporal bones, extending outward to the neigh- boring bony margins. They resemble the antero-lateral fontanelles in respect to their size, shape, and boundaries. By the progressive ossification of the flat bones of the cranial vault, the fontanelles become closed in the first year of life, rarely later, the frontal fontanelle closing last (at the end of the first or the beginning of the second year). At the same time the coronal, sagittal, and lambdoid sutures develop, whereby small bony areas frequently remain as independent structures within the sutures, and are known as supernumerary bones, Wormian bones, or ossa suturarum. They are particularly common in the sagittal and lambdoid sutures, where they are sometimes present in large numbers and are occasionally of considerable size. THE SKELETON OF THE EXTREMITIES. The skeletons of the upper and lower extremities are more or less similar. They are com- posed of: (1) The girdle of the extremity, and (2) the free extremity. The shoulder girdle is composed of the scapula and the clavicle; the pelvic girdle of the two pelvic bones. The skeleton of each free extremity consists of a proximal, a middle, and a distal segment, these being represented in the upper extremity by the bone of the arm, the bones of the forearm, and the bones of the hand, and in the lower extremity by the thigh-bone, the bones of the leg, and the bones of the foot. The skeleton of the proximal segment of each extremity consists of a single bone: in the upper extremity, the wmerus; in the lower one, the femur. The middle segment is formed by two bones: the radius and ulna in the forearm; the “bia and fibula in the leg. The distal segments, the hand and the foot, contain a number of bones, those of the hand being subdivided into the carpal bones, the metacarpal bones, and the phalanges of the fingers, and those of the foot into the ¢arsal bones, the metatarsal bones, and the phalanges of the toes. The extremities also contain a number of sesamoid bones; they occur in the upper ex- tremity only in the hand; in the lower extremity they are to be found both in the foot and also in the region of the knee (the knee-cap or patella). Frontal fontanelle g BEE = ay Frontal eminence Parietal eminence Sphenoid fontanelle Occipital fontanelle Tympanic annulus Lateral Pyra- Mastoid Sutura mendosa portion mid fontanelle of occi- (ma- pital stoid portion) Occipital fontanelle Frintal suture Squamous portion Frontal fontanelle of occipital Coronal Parietal Suture eminence Sutura §— mendosa & Mastoid JSontanelle Lateral portion MW > | Parietal tmingentle of occipital ~ Mastoid portion of temporal Ss av } Yt > & a \ 2 Membrana GR u* tympani * »\ YA Squamous portion of temporal Internal pterygoid plate Sagittal suture Palate bone Choana c Hard palate Squamous portion of occipital fae Os incisivum Ccecipital fontanelle Fig. 106. Fig. 105. THE SKELETON OF THE UPPER EXTREMITY, 55 . THE SKELETON OF THE UPPER EXTREMITY. : THE SHOULDER GIRDLE Unlike the pelvic girdle, the shoulder girdle is not completely closed, bet remains open posteriorly, its posterior constituent, the sca pula, having no direct of indirect connection with he corresponding bone of the opposite side, while the anterior skeletal portions, the devices, ose the shoulder girdle anteriorly by their connection with the manubrium sterni. Both con gents of the shoulder girdle articulate with cach other, and the free upper extremity articu- es with the scapula. THE SCAPULA. The shoulder-blade or scapula (Figs. 107 to 110) is a decidedly flat bone which is very in places and exhibits several marked processes. It articulates only with the clavicle and quMerus; otherwise it is completely free and the sur. resting against the ribs is separated from them by the ening muscles. It is triangular in form, and there consequently be recognized in it three sides, three and two surfaces. According to the position of mula when the arm lies close to the side of the the three angles are designated as the infernal or) angle, the injerior angle, and the external angle. argins are the internal or vertebral (between the ine and inferior angles), the superior (between the in- ind external angles), and the external or axilary en the external and inferior angles). The anterior directed toward the ribs, is termed the costal sur- d the posterior one the dorsal surface. he costa surjace (Fig. 109) is relatively smooth and ee ae ar at concave, the shallow depression being termed exc agrale, scapular fossa, from the subscapular muscle which om its surface. Several rough lines, the Jince musculerct, commence at the vericbral and pass outward almost transversely across the surface. t dorsal surjace (Fig. 108) is rough, and is sulxlivided into two portions by a marked ed ridge, the spine, which commences at the upper half of the vertebral margin as a projection and gradually becomes more clevated as it passes outward. The small rea is known as the supraspinatous jossa (Fig. 107), and the larger lower one as the ous fossa; both of these names being derived from the muscles to which the fossxe riebral border of the scapula (also termed the base) is not exactly straight, but pre- ht angle at the origin of the spine. The upper and lower portions of the border are Wd 84 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 108.—The dorsal surface of the left scapula (4). Fic. 1o9.—The costal surface of the left scapula (4). Fic. 110.—The left scapula seen from the outer angle and axillary border (4). Fic. 111.—The left clavicle seen from below (%). Fic. 112.—The left clavicle seen from above (%). This border receives the insertion of the serratus magnus muscle, which also extends outward upon the costal surface in the vicinity of the superior and inferior angles, so that the costal surface presents two shallow triangular areas for the attachment of muscles, in addition to the subscapular fossa. The superior border presents a notch, the scapular notch (Figs. 108 and 109), which may be either deep or shallow, and to the outer side of this there projects from the superior margin a strong, curved, hook-like process, the coracoid process (Fig. 109). This arises by a broad base between the scapular notch and the outer angle, and is at first directed upward and some- what forward; it then becomes narrower, makes a distinct turn, and passes forward and out- ward to end in a roughened apex. The axillary border (Fig. 110), so called because it is directed toward the axilla, is slightly thickened and roughened, particularly toward the external angle. A furrow separates this elevated border from the anterior surface of the bone. The internal angle is either a right or an obtuse angle; the inferior one is acute with a mark- — edly rounded apex. At the external angle is situated the so-called head of the scapula, which presents the articular surface for the head of the humerus, the glenoid cavity (Fig. 110), which is smooth, slightly concave, and shaped like a pear with the apex upward. Above the glenoid cavity is a small surface, the swpraglenoidal tuberosity (Fig. 110), which gives origin to the narrow cord-like tendon of the long head of the biceps, and below the cavity — there is a larger, markedly roughened surface, the injraglenoidal tuberosity, which gives origin i to the broad strong tendon of the triceps. The head of the scapula is separated from ‘J st mf remainder of the bone by a slight constriction called the neck. The spine of the scapuia (Fig. 108) arises by a broad base from the dorsal surface between the supraspinatous and infraspinatous fosse, and gradually becomes higher as it passes from the vertebral border to the neck of the bone. It passes over the neck, overhangs the glenoid — ms cavity from above and behind, and terminates in a strong, broad, flattened process, the acromion. — Internal to its apex, the acromion presents an elongated, flat, articular surface for the attach- — ment of the acromial end of the clavicle. ¢ The scapula is preformed in cartilage during fetal life. The first center of ossification appears in the third month. the new-born. During the first year of life an independent center appears in the coracoid process,* from which is for the greater portion of this projection. At the age of puberty special epiphyseal centers make their appearance, jn apex and the base of the coracoid process, in the acromion (usually several centers), in the base of the scapuley: (even earlier, in the tenth head in the external angle of the Sania in the region of the origin of the biceps tendon. # * In reptiles, birds, and the lowest mammalia the coracoid process is an independent bone. Internal angle Scapular notch Superior Coracoid process border “s =<) [is ab =r ri - Spine 4 bio \ = + Acromion Glenoid cavity Vertebral External angle border Neck Axillary border Fig. 108. Inferior angle Acromion — Articular surface of acromion SC SS a Subscapular fossa Coracoid 25>‘ Internal angle Superior process” | . border Scapular _ Sa notch < y , neck » External epicondyle eek Head Internal woercee \ Groove for epicondyle 2 uinar nerve Capitulum Trochlea Fig. 115. Fig. 116. - Co THE SKELETON OF THE UPPER EXTREMITY. 57 external surface, is the much smaller and shallower radial jossa (Fig. 114) for the head of the radius. Opposite to these two fossz upon the lower portion of the posterior surface is situated a broad deep depression, the olecranon jossa (Fig. 113), which accommodates the olecranon when the arm is extended. The humerus, like most of the long bones, is developed from a center of ossification for the diaphysis or shaft and from two or more epiphyseal centers. The diaphyseal center appears in the eighth week; the epiphyses are sull car- tilaginous at birth. During the first year a center appears in the upper epiphysis (for the head), then follow those for the capitulum, the greater tubercle, the lesser tubercle, and finally those for the trochlea and separate centers for each epicondyle which appear between the tenth and twelfth year. Complete ossification of all parts of the bone and the disappearance of the synchondroses between the epiphyses and the diaphysis do not occur until from the twentieth to the twenty-second year. Between the olecranon and coronoid fossa the humerus is as thin as paper and sometimes even perforated. The epicondyles serve as points of muscular origin, the internal one giving origin to the superficial flexors and pronators of the forearm, the external one to the superficial extensors. Above the internal epicondyle the inner border of the humerus occasionally presents a second process, known as the supracondyloid process. The inner portion of the trochlea extends lower than does the external portion, and its surface represents an almost complete cylinder, which is interrupted only by the thin bony plate between the coronoid and olecranon fossw. The capitulum is placed somewhat anteriorly and is scarcely visible from behind. THE ULNA. The ulna (Figs. 117 to 119) is a three-sided prismatic long bone which is thick above and quite small below. It is composed of a shaft and of a superior and an inferior extremity. The strong upper extremity presents a semilunar or greater sigmoid notch (Figs. 117, 119, and 124), which articulates with the trochlea of the humerus and is constricted in its middle. Its anterior portion rests upon the upper surface of the coronoid process (Fig. 119), a broad beak-like pro- jection directed anteriorly, and its posterior portion rests upon the anterior surface of a very strong bony process, the olecranon, which forms the tip of the elbow and projects quite a distance above the coronoid process. The external or radial side of the proximal extremity of the ulna presents a notch, the radial or lesser sigmoid notch (Fig. 116), for the head of the radius, and passing downward from this cavity there is a rough longitudinal ridge, the su pinasor ridge (Fig. 117). Immediately below the coronoid process is situated a broad roughened area which is directed anteriorly, and is termed the tuberosity (Fig. 119). The olecranon receives the insertion of the large triceps muscle, the extensor of the forearm, and the supinator ridge gives origin to the greater portion of the supinator brevis muscle. The brachialis anticus muscle is inserted into the tuberosity and the coronoid process also gives origin to portions of several of the muscles of the forearm. The shaji of the bone becomes much thinner and more rounded toward its lower extremity, so that while the bone resembles a three-sided prism in its upper portion, it becomes cylindrical in its lower fourth. In the shaft may be recognized an anterior volar, a posterior or dorsal, and an internal or ulnar surjace. The internal surjace is separated from the posterior one by the dorsal border, and from the anterior one by the volar border. The third border is sharp and is directed toward the radius; it separates the anterior from the posterior surface and is called _ the interosseous ridge (Fig. 119). The volar surjace contains the nutrient joramen, from which a nutrient canal passes toward the elbow within the bone, but otherwise the surface exhibits no peculiarities. % 88 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 117.—The left ulna seen from the outer surface (4). Fic. 118.—The left ulna seen from behind (%). Fic. 119.—The left ulna seen from in front (#). Fic. 121.—The left radius seen from in front (3). Fic. 122.—The left radius seen from the inner side (4). Fic. 123.—The left radius seen from behind (2). Fic. 124.—The upper extremities of the radius and ulna seen from above and somewhat in front (4). Fic. 125.—The lower extremities of the radius and ulna seen from below (4). . The inferior extremity of the bone is rounded and is also called the capiztulum. Its radial side presents an articular surface for the radius, the ariicular circumference (Fig. 119), and a pointed process projecting beyond the capitulum, the styloid process (Figs. 117 to 119). The distal surface of the capitulum and the articular circumference are both covered by cartilage. The center for the diaphysis of the ulna appears in the third fetal month; the centers for the epiphyses appear after birth, that for the lower epiphysis not being present until the sixth year. The upper epiphysis has two centers for the olecranon (only the apex of which is formed by the epiphysis) and one for the coronoid process. ‘There is also a special center for the styloid process. ; THE RADIUS. The radius (Figs. 121 to 125) is the outer of the two bones of the forearm, and in contrast to the ulna, it is narrow and thin above and broad and thick below. Its superior extremity (Fig. 124) is formed by the disc-like head of the bone, a distinct constriction below the head being designated as the eck, which portion of the bone is cylindrical. dorsal border. 6) fi | dorsal border. Le Ss, < ( i ey | i y ,: M 2 a(S = ! (% ' Nit I volar border ce volar borders ulna. radius. Fic. 120.—Transverse section through the bones of the forearm, taken at about the middle of their length (schematized). The upper surface of the head exhibits a depressed articular surface for the capitulum of the humerus, and the upper circumference of the margin of the head is termed the articular cir- cumjerence (Fig. 124). Below the neck the upper portion of the volar surface presents a strong, rough, marked projection, the ‘wberosity (Figs. 121, 122, and 124), for the insertion of the biceps muscle. The shaft of the radius, like that of the ulna, is shaped like a three-sided prism, and the three surfaces are arranged in a similar manner, so that volar, dorsal, and lateral surjaces, and volar and dorsal borders, and an interosseous ridge may be recognized (Fig. 120). The interosseous _- Ollecranon ‘Olecranon (at Semilunar - j ; Semilunar notch @ Coronoid notch process Coronoid Radial notch Radial ~ process notch Supinator Tuberosity ridge Tuberosity ¥ Nutrient foramen Interosseous \ ridge Volar surface [nterosseous Dorsal surface ridge Dorsal border Internal surface ¥ ; Dorsal surface ~ =~ id Dorsal ; Surpace | : oa % Articular Capitulum vy, circumference Styloid process Styloid process Styloid process Fig. 117. Fig. 118. Fig. 119. Articular Head circumference ——_ Head © Neck -—- ; Superior _. extremity ~— Tuberosity Tuberosity Shaft Volar surface Interosscous Nutrient foramen ridge Interosseous ridge is at Interosseous ridge Dorsal border —_ Volar border ; d External surface Dorsal surface Dorsal surface | | 7 | Volar surface Fig. 121. Fig. 123. Ulnar notch Interior \ > \ extremit = ¥ Carpa! | 4 articular , surface ; Styloid process 7 Fig. 122. Styloid process % ~ - i - ») f\ a. \y + p. Olecranon SS Depression on “head of radius Styloid Semilunar © process notch Articular : circum- Carpal ference articular . Styloid surface process Tuberosity Uina Radius of radius Fig. 125. Fig. 124. UIna Radius THE BONES OF THE HAND. 89 ridge is situated opposite to the similarly named ridge of the ulna, and is only the sharp margin possessed by the radius, the two remaining margins having markedly rounded edges. : The three surfaces of the radius exhibit no structure of particular note, except that the 4 volar surface contains the nutrient foramen, the nuirient canal, like that of the ulna, passing in ie a proximal direction through the compact substance into the medullary cavity. = The broad inferior extremity (Fig. 125) is flattened, so that a volar and a dorsal surface are distinctly differentiated. ‘The interosseous ridge terminates below in a slightly excavated surface, the ulnar or sigmoid notch (Fig. 122), which articulates with the capitulum of the ulna. Opposite to this surface, upon the radial side, the styloid process (Figs. 121, 123, and 125) projects beyond the bone; it is broader and less pointed than the corresponding process of the ulna. The volar surface of the inferior extremity (Fig. 121) is smooth and slightly concave; the dorsal surface is traversed by ridges (Fig. 123*) which separate-distinct grooves for the tendons of the extensor muscles of the hand and of the fingers, a particularly deep one accommodating the tendon of the extensor pollicis longus muscle. The distal or carpal articular surjace is directed toward the carpal bones; it is concave and usually distinctly subdivided into two facets (Fig. 124), by means of which the radius articulates with the scaphoid and semilunar bones. The radius is somewhat shorter than the ulna and the two bones are so related that the ulna projects considerably beyond the proximal end of the radius and the radius extends beyond the distal extremity of the ulna. Both bones 120); in pronation the bones are crossed, since the inferior extremity of the radius (together with the hand) rotates about = the ulna, while the head of the radius rotates in the radial notch of the ulna. In addition to their articulations with each other, the radius articulates with the humerus and the carpal bones, but the ulna articulates with the humerus only. The development of the radius is similar to that of the ulna. The center for the diaphysis appears in the third fetal month, while the nuclei for the epiphyses do not appear until the fifth year, the upper epiphysis being developed from a single center. Accessory nuclei appear still later in the tubercle and in the styloid processes of the radius. Ossi- fication is not complete until the twentieth year. THE BONES OF THE HAND. THE CARPAL BONES. The eight bones of the carpus (Figs. 126 to 131) are arranged in a proximal and a distal row. Passing from the radial to the ulnar side the proximal row contains the navicular or scaphoid bone, the /unate or semilunar bone, the triquetral or cuneijorm bone, and the pisijorm bone. Passing in the same direction, the distal row is composed of the greater muliangular bone or érapezium, lesser multangular bone or the trapezoid, the os capitaium or os magnum, and the hamate or uncijorm bone. The bones of the proximal row (really the first three only) are not situated in a straight line, but are curved so as to form an arch which is slightly convex proximally and markedly concave distally (Figs. 128 and 129). In the distal row the capitatum projects markedly toward the proximal row and is accommodated by its concavity. go ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 126.—The lower ends of the bones of the forearm, and the carpal and metacarpal bones in their natural positions, seen from the dorsal surface (#). The preparation was made from a frozen hand, whereby the relative position of the bones could be perfectly determined. Fic. 127.—The same preparation seen from the volar surface (4). Fic. 128.—The bones of the left hand seen from the dorsal surface (2). Fic. 129.—The same preparation seen from the volar surface (3%). Fic. 130.—Frozen preparation of the bones of the left hand, together with the lower ends of the radius and ulna, seen from the dorsal surface (3). Fic. 131.—The same preparation seen from the volar surface (3). All the bones are irregularly shaped and are difficult of description. The navicular (scaph- oid) bone is ellipsoidal; its distal surface is excavated, and the radial border of its palmar surface is provided with a rough tubercle (Fig. 127). The lunate (semilunar) bone is shaped like a half-moon, the triquetrum (cuneiform) resembles a short three-sided pyramid, and the pisiform bone is irregularly spherical. The greater (trapezium) and lesser multangular (trape- zoid) bones are irregularly cubical and the palmar surface of the former exhibits an elongated flattened elevation, the tubercle (Fig. 127). The capitatum or os magnum is the largest bone of the set, and its length is much greater than its breadth; its proximal end is large and forms the head of the bone, which is covered with cartilage. The hamatum (unciform) is also large and irregularly wedge-shaped, and its palmar surface is provided with a flat, slightly curved process, the hamulus or uncijorm process (Fig. 120). The carpal bones do not lie in a single plane, but form an arch which is convex posteriorly and concave anteriorly. The concavity is increased by the two bony prominences which are situated upon both the radial and the ulnar sides of the palmar surface of the carpus and form the carpal groove. The radial carpal eminence (Figs. 127 and 131) is formed by the tubercles of the navicular and greater multangular bones; the ulnar eminence, by the pisiform bone and the hamulus of the hamatum. The small, almost spherical pisiform bone is situated only in the palmar surface of the carpus; all of the remaining carpal bones possess a roughened dorsal and palmar surface. Both surfaces of the four bones situated at the radial and ulnar margins of the carpus, the navicular (scaphoid)— greater multangular (trapezium), triquetrum (cuneiform), and hamatum (unciform)—are con- nected by lateral, radial and ulnar surfaces, but the numerous remaining surfaces (numerous on account of the irregular shapes of the bones) are smooth articular facets covered with cartilage for articulation with each other, with the radius, or with the metacarpal bones. The pisiform bone has but a single articular facet for connection with the triquetrum (cunei- form), but all of the remaining carpal bones have several articular surfaces. The most important of these are the following: the navicular (scaphoid) and lunate (semilunar) bones each possess a convex articular surface which articulates with the distal end of the radius; the triquetrum is not connected with the ulna, however, but with an intervening disc of cartilage. Of the joints between the proximal and the distal row of the carpal bones, the most important is that between the convex surface of the head of the capitatum and the concave surfaces of the lunate and navicular bones. Articular circum- ference of head of ulna . , Styloid Styloid process process of ulna of ulna Lunate bone Lunate bone lar bone Styloid process of radiits Pisiform bone Triquetral bone : / Tubercle of navicular bone ra ' t Lesser multangular bone Triquetral bone : —<— Greater Lesser multangular bone ey Hamate bone ; fangular oone Hamate bone Tubercle of greatet multangular bone Capitate bone Base of fifth metacarpal Capitate bone bone Metacar ile of thumb Metacarpal bone of thumb Styloid proc. third meta- carpal bone Heads of metacarpal bones Fig. 120. Lesser ey r-Lunate bone Styloid process of third metacarpal bone Lungte bone Capitate bone that Capitate bone gue Triquetral bone Navicular bone Pisiform bone ¢ Lesser multangular Hlamate bone , bone Greater multan- gular bone Pisiform bone (tubercle) Hamulus — of hamate Base of fifth bone metacarp. bone First meta- carpal bone Head of Sirst meta carp. bone Head of second meta- carp. bone thumb First phalanx Second phalanx of thumb Second phalanx Ungual tuberosity Third phalanx ye A Utna iver, Radius Radius Ulna Carpus Carpus Metacarpal bone »f thumb , j Meta- Metacarpus carpus j , First phalanx of Base of phalanx \ thumb Second Trochlea of phalanx V Pha- X phalanx a Phalanges flanges ~« of thumb ‘Y First phalanx / First phalanx ; . Second phalanx Second phalanx Third phalanx Third phalanx Ungual tuberosity THE BONES OF THE HAND. gi The greater multangular articulates with the first metacarpal bone by a distinctly saddle- shaped surface; the lesser multangular (trapezoid) articulates with the second, the capitatum (os magnum) with the third, and the hamatum (unciform) with the two remaining metacarpal bones (Figs. 126 and 127). In addition to these, the following less important articular facets may be noted: on the navicular (scaphoid), for the lunatum (semilunar), capitatum (os magnum), greater (trapezium), and lesser multangular (trapezoid) bones; on the lunatum (semilunar) bone, for the navicular, capitatum (0s magnum), triquetral (cuneiform), and hamate (unci- form) bones; on the triquetral (cuneiform) bone, for the lunatum (semilunar) and hamatum (unciform); on the greater multangular (trapezium), for the navicular and lesser multangular (trapezoid) bones, and usually quite a small facet for the second metacarpal bone; on the lesser multangular (trapezoid) bone the articular facets include the greater por- tion of the surface of the bone, there being facets for the second metacarpal, the greater multangular, the capitatum, and the navicular bone; on the capitatum (os magnum), for the hamatum (unciform), lesser multangular (trapezoid), the second, the third, and the fourth metacarpal bones; and on the hamate (unciform) bone for the capitatum, trique- trum, and lunate bone. . All of the carpal bones are cartilaginous at birth, and each ossifies from a single center. In the capitatum and hamatum the center appears during the first year, in the remaining bones between the third and the ninth year, and -in the pisiform not until the twelfth year or even later. Supernumerary carpal bones are not rare. The most frequent is a central bone, a portion of the skeleton situated between the two rows, the appearance of which is explained by the development of the cartilaginous carpus, in which the bone is clearly represented. In the adult it is usually fused with the navicular, forming its tubercle. THE METACARPAL BONES. The five metacarpal bones (Fig. 126 to 131) are typical long bones in which may be recog- nized a proximal extremity or base, a shajt, and a distal extremity or head. The bases articulate with the distal row of carpal bones, the heads with the proximal row of the phalanges. The metacarpal bone of the thumb is the shortest, that of the index-finger the longest, and they grad- ually decrease in length toward the little finger. The bases of the metacarpal bones are irregularly cubical and thicker than the shaft; that of the metacarpal bone of the thumb bears a saddle-shaped surface for articulation with the trapezium, and the remaining ones present, in addition to the articular facets for the carpal bones, lateral surfaces for articulation with each other. The base of the third metacarpal bone presents a styloid process (Fig. 128) which is directed toward the radial side. The base of the first metacarpal bone has a single articular surface; that of the second has three, a small radial one for the greater multangular (trapezium), a large proximal one for the lesser multangular (trapezoid), and a small ulnar one for the base of the third metacarpal bone; the base of the third metacarpal presents a larger proximal facet for the capitatum (os magnum), a small radial one for the second metacarpal bone, and a small ulnar one for the fourth metacarpal bone; the base of the fourth metacarpal bone similarly possesses a proximal facet for the hamate (unciform) bone, a radial one for the third, and an ulnar one for the fifth metacarpal bone; and the base of the fifth metacarpal has a proximal facet for the hamate (unciform) bone and a radial facet for the fourth metacarpal (Figs. 127 and 129). Each of the nutrient foramina leads into a nutrient canal which pursues the same direction as those of the bones of the forearm. The shaft of each metacarpal bone, with the exception of that of the thumb, is approxi- mately three-sided, and possesses a palmar and a dorsal border. The palmar border becomes flat as it passes toward the base, while the dorsal border widens out into a surface as it approaches the head. Q2 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The heads of the bones are provided with spherical articular surfaces, and their sides present depressions which serve for the attachment of ligaments. Their bases (with the exception of that of the freely movable bone of the thumb) are closely approximated, but both the shafts and the heads are separated by large interspaces which are known as the interosseous spaces (Figs. 126 and 127). Between the heads these spaces are filled by ligamentous masses, between the shafts by muscles. According to the statements of most authors, the metacarpal bones develop from a diaphyseal center in the middle of the bone and from an epiphyseal center in the head; only the metacarpal bone of the thumb differing in that its epi- physeal center is in the base. Occasionally the third metacarpal has a separate center for its styloid process. The epiphyseal centers do not appear until after birth, while the diaphyseal center appears ee) early (in the ninth week) before the centers in the radius and in the ulna. THE BONES OF THE FINGERS. Each finger has three bones or phalanges, but the thumb has but two (Figs. 128 to 131). These are designated as the proximal or first phalanx, the middle or second phalanx, and the distal, terminal, ungual or third phalanx. The thumb has no middle phalanx. The phalanges * diminish in length as we pass toward the finger-tips, so that the terminal phalanges are the shortest, and the longest phalanx is the proximal one of the middle finger. The phalanges are long bones composed of a proximal extremity or base, of a shajt, and of a distal extremity or ¢rochlea. ‘The bases of the proximal phalanges have concave hemi- spherical’ sockets for the heads of the metacarpal bones; the articular surfaces or bases of the remaining phalanges present a double concavity separated by a median elevation. The shafts of the phalanges have sharp lateral borders, and their dorsal surfaces are con- vex, their palmar ones plane or slightly concave. The short bodies of the ungual phalanges terminate in a rough horseshoe-shaped expansion, the ungual tuberosity (Fig. 130). The distal extremities of the proximal and middle phalanges exhibit small fosse, similar to those upon the heads of the metacarpal bones, for the attachment of ligaments, and the nutrient canals run toward the finger-tips, in an opposite direction to those of the other bones of the extremity. The phalanges are developed like the metacarpal bone of the thumb, each phalanx being ossified from a center in the shaft and from an epiphyseal center in the proximal extremity; there are no centers for the distal ends. The proximal phalanx ossifies first (third month) and then follow the middle and the terminal phalanges. THE SESAMOID BONES. In addition to the bones previously described, the hand also contains a varying number of sesamoid bones. Two of these are constantly found at the metacarpophalangeal joint of the thumb, and occasionally others occur at the similar joints of the index and little fingers, but in the latter situation they may be replaced by fibro-cartilage. In the thumb they are usually covered with cartilage upon one side and are connected with the articulation. There is also usually a sesamoid bone at the interphalangeal joint of the thumb. THE SKELETON OF THE HAND AS A WHOLE. The metacarpal and phalangeal bones do not lie in one plane, but form a curved surface, convex upon the dorsum and concave in the palm; in the metacarpal region this curve may THE SKELETON OF THE LOWER EXTREMITY. 93 - | be considerably increased or diminished by the muscles of the hand. -The convexity of the dorsal surfaces reaches its highest point at the metacarpal bone of the index-finger, and from this point declines gradually toward the metacarpal bone of the littl finger and abruptly toward that of the thumb. The so-called dorsal surfaces of the metacarpal bone and of the two phalanges | of the thumb are directed externally and their borders, instead of their surfaces, ane Consequently - directed toward the dorsum of the hand. The dorsal surface of the metacarpal bone of the _ little finger is also directed somewhat toward the ulnar side. . While the metacarpal bone of the index-finger is the longest, the phalanges of the middle it finger are longer than those of the index-finger, so that the middle finger is the longest finger. | The phalanges of the ring-finger are also longer than those of the index-tinger. In correspondence with the functions of the hand as a prehensile organ, the fingers are ‘ well developed and take up almost half of the entire length of the hand. The length of the - carpus is about one-sixth of the entire length of the hand. THE SKELETON OF THE LOWER EXTREMITY. THE PELVIC GIRDLE. The pelvic girdle consists of the two innominate bones and in contrast to the shoulder gindle, which is closed anteriorly only, it is also closed posteriorly by the articulation of the innominate bones with the sacrum. The connection of the bones of the pelvic girdle is also much firmer than that of the bones of the shoulder-girdle. ‘Together with the sacrum, the two innominate bones form the bony pelvis. } iq THE INNOMINATE BONE. The innominate or coxal bone (Figs. 132 to 134) is a single bone in the adult only. In the new-born and until the age of puberty (Figs. 135 and 136) it consists of three bones separated by cartilage (synchondroses)—the sium, the pubis, and the ischiamm. All three bones are in contact in the acelabulum and unite at about the age of puberty to form the innominate bone. ‘The portions of the ilium, pubis, and ischium which unite in the accta- | bulum are the thickest parts of their respective bones and are designated the bodies. _ The ilium forms the upper portion of the innominate bone; it is the langest of the three | bones and forms the upper third of the acetabulum. It consists of a bedy and of an upper portion or a/a. -- The pubis forms the antero-inferior portion of the innominate bone and the antero-inferior third of the acetabulum. It is separated from the ischium by a large foramen, the obturator foramen, except at the inferior boundary of the foramen, where it is attached to the ischium by a synchondrosis which disappetrs before the age of puberty. It is composed of a body and of two rami. The su perior ramus (Fig. 134) forms the upper boundary of the obturator fora- men, the injerior ramus, the anterior one. “The ischium forms the postero-inferior portion of the innominate bone, the postero- — r third of the acetabulum, and the inferior and posterior boundary of the obturator —_ 94 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 132.—The right innominate bone seen from the outer surface ($). Fic. 133.—The right innominate bone seen from the inner surface (}). foramen. It is composed of a body (Fig. 134) and of two rami, a superior and an inferior vamus, which, like those of the pubic bone, form boundaries of the obturator foramen. In the adult innominate bone the thickened and somewhat constricted portion of the bone, upon whose outer surface is the acetabulum, gives off a bony plate, the ala of the ilium (Fig. 134), which passes upward and presents an external convex and an internal concave surface. Below and in front of the acetabulum, the middle portion of the bone sends out a second plate, which is perforated by the obturator foramen (rami of the pubis and ischium). The ala of the ilium (Fig. 137) is shaped like the horns of a buck, without the tips. In the middle it is frequently as thin as paper. Its superior margin is markedly thickened and rough and is known as the crest of the ilium, and upon this crest are three rough lines, produced by the attachment of the abdominal muscles. They are most distinct in the middle of the iliac crest, where it is thickest and reaches its greatest height, and are termed the external, the internal, and the middle lips of the crest (Figs. 132 and 134). Anteriorly the crest of the ilium ends in a spine, the anterior superior spine (Figs. 132 to 134), and at the posterior extremity of the crest there is another less pronounced spine, the pos- terior superior spine (Fig. 131). Below the posterior superior spine, and separated from it by a shallow notch, is the posterior inferior spine, and below this the posterior margin of the innominate bone presents a deep paraboloid notch, the great sciatic notch (Fig. 132), whose upper boundary is formed by the posterior margin of the ala, and its antero-inferior one by the bodies of the ilium and ischium. Below the anterior superior spine at the anterior border of the body of the ilium is situated the anterior inferior spine (Figs. 132 to 134). It is placed at a greater distance from the anterior superior spine than is the posterior inferior from the posterior superior one, and is situated im- mediately above the upper and anterior margin of the acetabulum. The external surface of the ala of the ilium (Fig. 132) is rough and convex, and presents three rough lines which indicate the areas of origin of the gluteal muscles. ‘These lines are designated as the posterior or superior, the anterior or middle, and the inferior gluteal lines. The posterior gluteal line is almost vertical and runs across the posterior portion of the ala of the ilium to the upper boundary of the great sciatic notch, and the small area of the ilium which it bounds gives origin to a portion of the gluteus maximus muscle and contains both posterior spines. The long anterior line passes backward in an arched manner from the anterior superior spine; it is at first almost horizontal, then nearly vertical, and ends near the superior line at the upper margin of the great sciatic foramen. The surface of the ala included between it and the superior line gives origin to the gluteus medius muscle. The inferior line is considerably shorter than the anterior one. It commences between the anterior superior and anterior inferior spines and passes backward almost horizontally above the acetabulum to the middle of the great sciatic foramen. It is but slightly curved and is apt ‘cer BLY sishy duds wniyast fo Apsosaqny winryas? [0 pda bid siqnd Apsosaqn 40JDAN}YO fo auids YIJOU INDIIS 4889] , ‘ 401MIUY syqud Jo jsaay WHY IS) fo auyds yJou siqnd Jo Jsad-) apps 40104)90 JNOIIS SISSIT INOOLE ae ed AOJDAN]( vssof avjpnqnye. 4OJ04N}QU 4OLIISOG of M0 y (is ba a wnimast fo gurls en OMY gvJANS avUN|NuIs aul) joanjs sorafuy YIJOU INDIIS JDAdT) aul) [Dans s0lMajuy - a, _ auyds < YIJOU INJOIIS VIM) Jvfins iwnauny auids soMafur souajuy . 4sopsafuy aurds ? AOVAISO cf sOL{un wip yo Apog | auids 4OLII}SOcf aids 40MIdNS 401MIJUY 4014adns ; 401A ]S Og] _ tani unit fo JO Apisouagny auids guids 4019S souadns a a Lol aun MOIS OG joan : AO1MIS Oc] ae WN} JO JSIMD POISE. JDplouzsvIA0g | dy 421N—E winij! fo ysaaa fo, diy ayppiyy~ | dy) 4auUup™ THE SKELETON OF THE LOWER EXTREMITY. 95 to be the least distinct of the three lines. The surface included between it and the anterior gluteal line gives origin to the glutzus minimus. The inner surface of the ala (Fig. 133) is composed of two portions, of which the larger anterior one is slightly excavated and is known as the diac jossa, while the posterior one is uneven and is further subdivided into two areas, an antero-inferior one, the auricular surjace (Fig. 135), for articulation with the similarly named surface of the sacrum, and a postero-superior extremely rough one, the ‘uberosity oj the tlium (Fig. 133), which corresponds with the similarly named surface of the sacrum. At the border of the auricular surface there is a distinct groove known asthe paraglenoidal groove (Fig. 133). The iliac fossa, the middle of which is frequently as thin as paper,* is separated from the remaining portions of the innominate bone (the body of the ilium, the pubis, and the ischium) by a line which is continued upon the pubis and is known as the arcuate line (Fig. 133). This line forms a portion of the dividing-line between the true and the false pelvis, the terminal (ilio- pectineal) line, and is consequently also known as the iliac portion of the terminal line. The body oj the ilium forms the upper portion of the acetabulum (see page 96) and a por- tion of the boundary of the great sciatic notch. It is directly continuous, particularly upon _ its inner surface, with the ala of the ilium above, and in the adult with the bodies of the pubis and ischium below. The pubic bone is intimately connected by its body with the ilium and with the ischium, and forms a portion of the acetabulum (see page 96). At the junction of the bodies of the pubis and ilium there is a low rounded elevation, the iiopectineal eminence (Fig. 135), which belongs to both bones in the adult after the ossification of the synchondrosis. Passing downward and forward from the body of the pubic bone is the approximately _ three-sided superior ramus (Fig. 135), which is practically horizontal, and forms the upper boundary of the obturator foramen. Its anterior extremity, which also gives origin to the inferior ramus, presents an oblong surface, the symphysis (Fig. 133), for articulation with the bone of the opposite side, and the anterior surface is directed forward and outward, the inferior one inward and forward, and the posterior one toward the interior of the pelvis. The upper border presents a sharp edge, the crest of the pubis (Fig. 133), which represents the continuation of the arcuate line of the ilium and is the pubic portion of the iliopectineal line. The crest ter- minates anteriorly in a small projection situated about a fingerbreadth from the symphysis and known as the /ubercle or spine of the pubis (Figs. 132 and 134). . At the junction of the superior ramus with the body of the pubis the posterior or pelvic _ surface of the bone presents a broad shallow groove, the obturator groove (Fig. 132), which gradu- _ ally fades away as it passes inward upon the inferior surface toward the obturator foramen. The sharp ridge which forms the inner boundary of the groove is known as the obturator ridge _ (Fig. 131). The obturator groove is usually bounded in front and below by a process directed toward the obturator foramen, the anterior obturator tubercle (Fig. 133), and a posterior boundary is some- times furnished by a posterior obturator tubercle, which arises from the ischium and is also directed * Sometimes there is a foramen in this situation. 96 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 134.—The right innominate bone seen from in front (3). Fic. 135.—The right innominate bone of a five- or six-year-old child seen from the inner surface (+). In Figs. 134 and 135 the ilium is yellow, the ischium green, and the pubis blue. Parts that are still cartilaginous are white. Fic. 136.—The same seen from the outer surface (+). toward the obturator foramen. Between these two tubercles is stretched the upper margin of the obturator membrane (see page 129). The inferior ramus of the pubis is flatter and possesses but two surfaces, an anterior and a posterior or pelvic surface. It passes obliquely downward and outward from the symphysis and is connected with the inferior ramus of the ischium at the site of a slight constriction. The ischium is shaped very much like the pubis, and in the adult its body is intimately connected with those of the ilium and pubis. It forms the antero-inferior boundary of the great sciatic notch, and in this situation presents a sharp triangular projection, the spine (Fig. 132). Below the spine is situated the lesser sciatic notch, which is not so deep as the greater one and is formed entirely by the ischium, its inferior boundary being furnished by the large rough tuberosity of the ischium (Fig. 132), which forms the main portion of the outer surface of the superior ramus. From the tuberosity, the thin flat inferior ramus passes forward and upward (Fig. 134), forming almost a right angle with the superior ramus of the ischium. To- gether with the inferior ramus of the pubis, it forms the lower boundary of the obturator foramen. The acetabulum (Fig. 132) is formed by the bodies of the ilium, pubis, and ischium, but dividing-lines between its component portions are visible in youthful individuals only. It is a hemispherical cavity with elevated margins looking directly outward, and only the anterior inferior portion of the margin toward the obturator foramen is incomplete; this gap is known as the acetabular or cotyloid notch. The floor of the acetabulum is composed of two differently shaped portions. The larger portion, the semilunar surface (Fig. 132), is smooth and covered with cartilage; it forms the upper and lateral portions of the cavity and extends downward to the borders of the cotyloid notch. The remaining quadrate area commences at the borders of the acetabular notch; it is rough and uneven and is known as the acetabular fossa. The obturator foramen (Fig. 134) is a large opening, the shape of which is subject to considerable individual variation; it may be either oval or triangular, its longest diameter being transverse in some cases and vertical in others. Its borders are formed by the rami of the ischium and of the pubis, and are for the most part sharp, being flat only where the obturator groove runs into the foramen. The innominate bone is formed from three main centers of ossification, one for the ilium, one for the ischium, and one for the pubis. The center for the ilium appears in the preformed cartilage at the beginning of the third fetal month, that for the ischium in the beginning of the fourth month, and that for the pubis in the fifth month. At birth and even during the first years of life (Figs. 135 and 136) a large portion of the innominate bone is still cartilaginous (the margins of the acetabulum, the crest of the ilium, the tuberosity of the ischium, and the spine of the ischium). In the acetabulum, a Y-shaped cartilage remains until the age of puberty, when the three portions of the bone become united by osseous tissue, the two inferior rami (of the pubis and ischium) becoming united still earlier, in the seventh or eighth year. In addition to the main centers, there appear a somewhat variable number of epiphyseal centers, of which those worthy of special mention are: one along the entire crest of the ilium, one in the tuberosity of the ischium, one in the upd 40LsIdny WATIYIST JO SUDA AOLII{U] soy, °F eas te PEL O14 SUMWDA JOLID{UT WUNTYIST JO ApIsoszguy MINNIS) JO SNUICA AOLAILUT Mnnyst Jo ApISOMIQUT . 3 MUDTOS. GE] “ly yo ane Ws SOLSIANG “Quy "340 *J80¢] wnsyost 40 Apog siqnd fo smuind s014afti] siqnd fo , wnnyps fo Apog wmysst fo SMV A A014, UT siqud jo Apoy sisfydiunls siqud fo auids Wusurusr : (a0fans JOautpadony siqud fo jaa 4vunpnas) siqnd yo snues sorsadng I ae bh ld cai uni fo dpog siqud fo snus fur solidus syqnd yo Apog wnnypst fo syqnd ‘OE1 ‘Oly naa Sle a fo spog = 2ouaUNuI JoDaunsadony me my uf) J PIMIUIMM fo auids poauradony winiyIsi fo Apog uwini fo Apo le | ads soiafur souauy avjans avjnauny pall dtd aids 4oj4adns sonajuy FO VIV wnt {0 Jsa47y aujds 4oladns 40149ju dy) 431N—E dy sauuy ' unyy fo sas Jo diy apply wnijyt fo Jsa1y 5 THE SKELETON OF THE LOWER EXTREMITY. 97 spine of the ischium, one in the symphysis, one in the anterior inferior spine of the ilium, and one in the spine of the pubis. Some of these do not appear until after puberty, about which time one or two epiphyseal centers also appear in the floor of the acetabulum. The epiphyses do not unite with the main portion of the bone unti! from the twentieth to the twenty-fifth year. The pelvis as a whole is considered upon page 130. THE SKELETON OF THE FREE LOWER EXTREMITY. THE FEMUR. The femur (Figs. 137 to 141) is the largest long bone of the human body, and consists of a superior extremity, a shajt, and an injerior extremity. The superior extremity presents a neck (Fig. 140), which is placed at an obtuse * angle to the axis of the bone and is surmounted by the head. This forms more than a hemisphere, representing from two-thirds to three-fourths of a sphere, and is directed inward and upward. It is covered with cartilage with the exception of a rough and slightly depressed area somewhat below and to the inner side of the middle (Fig. 138), to which is firmly attached a peculiar ligament of the hip-joint, the ligamentum teres. That portion of the bone which forms a constriction immediately below the head and which broadens externally toward the shaft is designated as the neck of the femur, and is shaped like an obliquely truncated cylinder, the superior border being about twice as long as the inferior one. The upper extremity of the bone, at the margin of the neck, presents two large, strong protuberances, the ¢rochanters (Fig. 140), which receive the attachment of numerous muscles. The greater trochanter is considerably larger than the lesser one and is situated externally, forming the entire outer portion of the superior extremity of the femur. Its slightly curved apex projects above the femoral neck, and below its apex is situated the érochanteric (digital) jossa (Fig. 138). The Jesser trochanter (Fig. 140) is a short conical projection which is placed opposite to the greater trochanter upon the inner side of the upper extremity of the femur, and is directed somewhat posteriorly. It is much smaller than the great trochanter and is situated at a lower level. The two trochanters are connected upon the anterior surface of the femur by a rough intertrochanteric linet (Fig. 139), and upon the posterior surface (Fig. 140) by a distinctly ele- vated ridge which commences at the apex of the great trochanter, and is termed the intertrochan- teric ridge. The intertrochanteric line and ridge form the posterior boundary of the neck of the femur. The greater and lesser trochanters give insertion to a large number of muscles. The shajt (Figs. 137 to 139) is almost cylindrical, although toward its lower extremity _ it becomes broader and assumes the shape of a three-sided prism with rounded margins. Its anterior and lateral surfaces are strikingly smooth, but the posterior surface presents a rough 7 line, the linea aspera, which is composed of two distinct lips, an inner and an outer lip (Fig. 137). In the middle of the femur they are closely approximated, but diverge toward both * In the female the angle approaches a right angle. . ft The intertrochanteric line does not actually run to the lesser trochanter, but passes beneath it to the inner lip of the linea aspera. 98 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 137.—The right femur seen from behind (2). Fic. 138.—The right femur seen from the inner surface (2). Fic. 139.—The right femur seen from in front (3). Fic. 140.—The upper end of the right femur seen from behind (4). Fic. 141.—The lower end of the right femur seen from below (2). Fic. 142.—The patella seen from in front (+). Fic. 143.—The patella seen from behind (4). the upper and the lower extremity of the bone, passing toward the trochanters above and to the epicondyles below. The outer lip of the linea aspera passes upward to a long broad elevation, the gluteal tuber- osity* (Fig. 140), which is usually flat but markedly roughened, and receives the greater portion of the insertion of the gluteus maximus muscle. The internal lip becomes less distinct as it passes upward and is continuous with the intertrochanteric line. Parallel to the upper part of the inner lip and somewhat to the outer side of it is situated a second rough line, the pectineal line (Fig. 140), for the insertion of the pectineus muscle. Toward the lower extremity of the femur the two lips of the linea aspera gradually diverge and form the boundaries of an almost plane triangular area upon the posterior surface of the bone, the popliteal surface (Fig. 137). Upon the line, above its middle, there are usually one or more nutrient foramina which lead into canals pursuing a distinct upward (proximal) direction. The shajt of the femur exhibits a distinct curvature, which is convex anteriorly (Fig. 139), and upon its anterior broad portion there may be distinguished an antero-internal, an antero- external, and a posterior surface. The linea aspera furnishes either the origin or the insertion for a large number of muscles. The injerior extremity of the femur is very broad, and presents two convex condyles (Fig. 137), a larger internal condyle and a smaller external condyle, which are directed posteriorly and are separated from each other by the intercondyloid fossa, an intercondyloid line separating this fossa from the popliteal surface. Anteriorly (Fig. 141) the cartilaginous surfaces of both condyles are continuous with an articular surface, the patellar surjace, which is concave from side to side and convex from above downward, so that the entire articular surface of the lower end of the femur is shaped somewhat like a horseshoe. Above the condyles upon the lateral surfaces of the lower end of the bone are situated two rough and slightly prominent processes, the epicondyles (Figs. 137, 138, and 141), which are termed the internal epicondyle and the external epicondyle. ‘The lower portions of the lips of the linea aspera run downward to the epicondyles, which give origin to the gastrocnemius muscle. | Like most of the long bones, the femur is developed from a diaphyseal and two primary epiphyseal centers. The . diaphyseal center appears as early as the seventh week of embryonic life, and while the lower epiphyseal center is usually visible at birth, the center for the head of the femur does not appear until after birth (at the end of the first year). At a later period special epiphyseal centers appear in the greater trochanter (fourth year) and in the lesser trochanter (thirteenth to fourteenth year). Although the center for the lesser trochanter appears later than any of the other epiphyseal centers, it is the * Sometimes the gluteal tuberosity develops into a more pronounced projection, the third trochanter. Great trochanter Depression on head Neck Great trochanter Great trochanter Depression Trochanteric on heaa { Jossa ¥ X Boe” Neck Neck Intertrochan Lesser teric line trochanter 1 Lesser _@SSer €30€ Pectineal __-- a , fy trochanter trochanter Inner lip of linea aspera Linea aspera Outer lip of linea aspera | | | Popliteal Su rface Popliteat Internal — surface epicondyle Internal epicondyle enty hes External j Ext, vast 7 epiconay \ epicondyle mainte External External condyle condyle Patellar surface Internai condyle Internal condyle Intercondyloid line Intercondyloid fossa Fig. 139. Fig. 138. Fig. 137. — * a o ee ot = o a - + ( i " : ‘ , ras. | ¢ | Ree: ~ § ad = $e ’ 7 i dl | a7 . n i] \ » iy . es ‘ be r “" S 5 - i ‘ ; “(oo - -) ' ¢ .- 7 : os é 4 . ‘ of . 7 7 n 5 gf - = 8 ‘ : 2 , be r . Neck Great trochante a Pee Head om Intertrochanteric ridge Patellar surface Lesser ’ Gluteal trochanter : tuberosity Internal Pectineal line Outer lip External epicondyle nner lip of , 4 of linea epicondyle linea aspera | oe aspera nti Internal condyle Fig. 140. Intercondyloid fossa Fig. 141. Articular surface Apex Fig. 143. THE SKELETON OF THE LOWER EXTREMITY. 99 first to unite with the shaft of the femur (seventeenth year); then follows the union of the trochanter major, then that of the head of the femur, and finally (at the twenticth year) that of the lower end of the femur with the shaft of the bone. THE PATELLA. The patella (Figs. 142 and 143) is a flat, rounded, disc-like bone which is nothing more than a large sesamoid bone in the tendon of the quadriceps femoris muscle. The upper border is broad and is called the base, and the lower portion of the bone terminates in a point, the apex. The anterior surface is rough; the posterior is smooth and covered with cartilage for about two-thirds of its extent, this cartilaginous surface being apposed to the patellar surface of the femur and known as the articular surjace. The posterior surface of the apex is not covered with cartilage and is rough like the anterior surface. The patella is formed from a single center which does not appear until the fourth year. Ossification is not complete until after puberty. THE TIBIA. The tibia (Figs. 144 to 147 and 150 to 152) is the inner and by far the larger of the two bones of the leg. It is composed of a superior extremity, a shajt, and an injerior extremily. inlernal border Wie. = bosler;,, ADT Rem, < \ POslerion . lace wo - yr . “a. oO a “ a orest. f \ ie 2 VW ‘ posterior crest. SN A interosseous ‘ ridge. fibula ¥ g j 4 > Wiad if 7 n 2 iy, » } } \ , | Py eed 3 ‘ y) v \ / anterior creat S VY © ~ © = x Fic. 147.—A section of the bones of the crus taken at about the middle of their length (schematized). The superior extremity is the thickest portion of the bone. It presents two condyles (Fig. 151), which articulate with the lower end of the femur, and are known as the infernal and external condyles. They exhibit upon their upper surfaces two rounded, triangular, slightly concave areas, the internal and external superior articular surjaces, for the femoral condyles, whose concavities (especially that of the external one) are considerably less than the convexities of the femoral condyles. These areas are separated by a median elevation, the intercondyloid eminence or spinous process, which presents two small tubercles, the infernal and external intercondyloid tubercles, and in front of and behind the eminence are small shallow depressions which are known respectively as the anterior and posterior intercondyloid josse (Fig. 151). The articular surfaces are bounded by the almost vertical bony margin of the upper end I00 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 144.—The right tibia seen from in front (2). Fic. 145.—The right tibia seen from behind (3). Fic. 146.—The right tibia seen from the outer surface (4). Fic. 148.—The right fibula seen from the inner surface (2). Fic. 149.—The right fibula seen from the outer surface (2). Fic. 150.—The tibia and fibula seen from behind (2). Fic. 151.—The upper ends of the tibia and fibula seen from above (4). Fic. 152.—The lower ends of the tibia and fibula seen from below (4). of the tibia, the infraglenoidal margin (Fig. 144), and at the lower portion of the external surface of this margin is an almost flat, elliptical, articular surface for the head of the fibula (Fig. 145), while below it, the anterior surface of the bone presents a large roughened elevation, the éuber- osity (Fig. 144). The entire upper end of the tibia is bent slightly backward toward the shaft of the bone (Fig. 146). The shajt of the tibia is of a distinctly triangular prismatic form. It is thick at its junction with the upper extremity, and as it passes downward becomes more slender, at first gradually and then rapidly (Figs. 144 to 146). It presents for examination three borders and three sur- faces. The sharp anterior crest (Fig. 144), somewhat S-shaped and beginning at the lower margin of the tuberosity, separates the internal and external surfaces, while the equally sharp interosseous ridge (Figs. 145 and 146), directed toward the fibula (Fig. 147), is situated between the external and posterior surjaces. The third border of the tibia is rounded; it separates the inner and posterior surfaces and is known as the internal border. The upper portion of the posterior surface of the shaft exhibits a rough line, the popliteal or oblique line (Fig. 145), which passes from above downward and from without inward from the articular surface for the fibula to the internal border. Below it is situated the nutrient foramen, which is usually very large and distinct, and leads into a canal which passes obliquely downward. The nutrient canal of the tibia consequently runs in an opposite direction to that of the femur. The inner surface of the tibia, like its anterior border, is situated immediately beneath the skin and may be easily felt. The outer surjace presents no special characteristics. ‘Toward the lower end of the bone the borders (with the exception of the interosseous ridge) become rounded off, so that in this portion the bone is almost cylindrical. The inferior extremity of the tibia is considerably smaller than the upper one, but it is distinctly thicker than the lower portion of the shaft. Its inferior surface (Fig. 152) presents a slightly concave articular surface for the astragalus, and upon its inner side there is a process which projects below the remainder of the bone and is known as the internal malleolus (Fig. 144). The external surface of this process forms an articular surface for the astragalus, and is directly continuous with the inferior articular surface of the bone. Upon the posterior surface of the internal malleolus is a broad groove (Fig. 144) for the tendon of the tibialis posticus muscle, and the outer surface of the lower end of the bone presents a notch, the fibular notch, for the recep- tion of the fibula (Fig. 146), this notch not being, however, an articular surface and therefore not being covered swith cartilage | Intercondyloid eminence Articular surface for fibula cas Infraglenoid y margin External Internal , : Superior _ condyle condyle extremity Tuberosity . - Intercondyloid eminence Internal condyle External : / condyle Crest + Nutrient foramen External : surface Posterior : surface Internal surface Interosseous ridge Popliteal line __\. Nutrient Joramen _. Posterior surface Shaft > Interosseous ridge External surface Fibular notch Articular surface of malleolus Fibular notch Internal malleolus Inferior articular surface Fig. 140. Inferior articular surface Fig. 144. Inferior extremity Groove on internal malleolus Articular surface of malleolus Inferior articular surface Fig. 145. yo Articular surface Apex of - f\ — of head head ’ Head Superior extremity Posterior crest External —- crest Interosseous Nutrient ridge foramen Anterior crest Internal surface Shaft External surface ~~ Anterior crest Posterior surface Fig. 148. Fig. 149. Articular : - surface of — <_Inferior extremity > malleolus ' Peroneal _ > hs sci External sulcus ; malleolus Anterior intercondyloid fossa a Peroneat -Tuberosity of tibia Fig. 150. sulcus Internal malleolus Int ! Articular surface of aterna Fr y external malleolus ~s external condyle xternal malleolus condyle = nie Head of fibula 7 ode External Articular sur- malleolus Jace of inter- nal malleolus Apex of head Internal intercon- dyloid tubercle Posterior intercondyloid fossa Inferior articular surface of tibia External intercondyloid tubercle Fig. 151. Fig. 152. sa” Pio . Py Sy hg 7 ome : oon is q ? 7 7...” ! ° by .S: % P — i ~ THE SKELETON OF THE LOWER EXTREMITY. or 7 i] The diaphyseal center of the tibia appears in the seventh week of embryonic life, but usually several days later than that of the femur. The upper (proximal) epiphysis ossifies immediately before or after birth, the distal one not until the beginning of the second year. The lower epiphysis unites with the shaft in the eighteenth, the upper in the twenty-second year. THE FIBULA. The fibula (Figs. 148, 149, 151, and 152) is a slender bone, and although its upper extremity is situated lower than that of the tibia, it is but a trifle shorter than that bone, since it projects below it (Fig. 150). It is situated upon the outer side of the leg, and is composed of an upper extremity, a shajt, and a lower extremity. The superior extremity is formed by the head (Fig. 148), the inferior by the external malleolus. The head is distinctly thickened as compared with the slender shaft of the bone, and its uppermost portion, which is directed outward and somewhat _ backward, is known as the apex. It presents a small flat articular facet (Pig. 148) for articulation with the tibia. ; The shajt of the fibula is of a distinctly triangular prismatic form, and its three surfaces are internal, external, and posterior (Fig. 147). The three borders are very sharp and do not pursue a straight course on account of a distinct torsion of the lower end of the bone about its longi- tudinal axis; they are known as the anterior, external, and internal crests, the anterior crest separating the internal and external surfaces, the posterior crest the posterior and internal surfaces, and the external crest the posterior and external surfaces. The inner surface also presents a feebly developed border, the inferosseous ridge (Fig. 148), so that the fibula may be said to possess four borders. The nutrient foramen is situated slightly above the middle of the posterior surface and at a lower level than that of the tibia; it leads into a canal which is directed downward. The tibia and the fibula have, therefore, different relations than do the radius and the ulna, a surface of the fibula (internal surface) being directed toward a border of the tibia (the interosscous ridge), and the similarly named surfaces of the two bones do not lie in the same planes (Fig. 147). The inferior extremity of the fibula is formed by the externa! malleolus, which is longer and more pointed than the internal one. Its inner aspect presents a flat articular surface (Figs. 148 and 152), which is immediately contiguous to the inferior articular surface of the tibia, and its external circumference is marked by a shallow groove for the tendons of the two peroneal muscles (Fig. 149). Alongside of the articular surface there is always a depression for the attachment of ligaments (Fig. 148, *). The diaphyseal center of the fibula appears somewhat later than that of the tibia (cighth week of fetal life), and the epiphyseal centers develop at a considerably later period, the inferior in the second and the superior in the third or fourth year. The inferior epiphysis unites with the shaft before the superior, as is the case in the tibia, but the union of both occurs later than in the tibia. THE BONES OF THE FOOT. The skeleton of the foot (Figs. 153 to 155), like that of the hand, consists of three divisions, 1e tarsus, the metatarsus, and the phalanges. _ | 7 sn ie 1? ee Io02 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 153.—A frozen preparation of the bones of the foot seen from the plantar surface (2). Fig. 154.—The same preparation seen from the dorsal surface (2). Fic. 155.—The same preparation seen from the outer side (4). Fic. 156.—The right talus (astragalus) seen from below (4). Fic. 157.—The right talus (astragalus) seen from above (4). THE TARSAL BONES. The ¢arsus (Figs. 153 to 155) consists of seven bones. (1) The ¢alus or astragalus; (2) the calcaneus; (3) the navicular or scaphoid bone; (4) the cuboid bone; and (5 to 7) the external, middle, and internal cuneiform bones. Only in the distal portion of the tarsus, where the cuboid articulates with the three cuneiform bones, is there an indication of an arrangement in rows as in the carpus, and in further contrast to the hand, a single tarsal bone articulates with both bones of the leg, while the carpus articulates with the radius only. THE TALUS. The éalus or astragalus (Figs. 156, 157) is a short bone, irregularly cuboid in shape, and is composed 61 a body and of a head, the constriction between the two being termed the neck. ; The body is the thickest and most posterior portion of the bone. Its upper surface presents” a cartilaginous trochlear surface, the ¢rochlea (Fig. 157), with which the tibia and fibula articulate, and it possesses three surfaces, a large superior one and two smaller lateral ones. The superior Be surface is convex in the longitudinal (sagittal) axis of the bone and concave from side to side; it is broad anteriorly and narrow posteriorly. The lateral surfaces are almost flat and approxi- mately triangular, the external one being much larger than the internal. The external surface is known as the external malleolar surface; it forms the outer side of the astragalus and is con- tinued upon a strong process of the bone, the external process (Figs. 154 and 156), which is directed outward. The cnternal surface forms a part of the inner side of the astragalus, the remainder of which is rough, and is termed the internal malleolar surface. Behind the trochlea and directed backward is the posterior process (Fig. 157), which is notched by a broad groove for the tendon of the flexor hallucis longus.* The lower surjace of the bone (Fig. 156) presents a distinctly concave, almost transverse, ovoid articular facet, the posterior articular facet, for the calcaneus, whose outer portion lies upon the lower surface of the external process, while its inner and posterior portion is upon the corresponding surface of the posterior process. In front of this articular facet is situated a broad groove, the sulcus tali (Fig. 155), which is wider externally than internally and the floor of which is roughened. Together with the similar a groove of the calcaneus it forms the sinus of the tarsus, which is filled by ligaments. In the region of the neck the lower surface of the astragalus in front of the sulcus tali presents ; an oblong, slightly convex, articular facet, parallel to the posterior one, and known as the a middle articular facet for the calcaneus, and bordering upon this, and forming a portion of the head — of the talus, is a small, slightly convex elliptical anterior articular facet for the calcaneus 4 (Fig. 156). re, * There may consequently be distinguished upon the posterior process an internal and an external tubercle. Phalanx II! of digit II Phalanx Il of digit J ~ Phalanx I of digit | ia xlo i it. ya = a om } j } \ Sesamold bones Meta- . tarsus Bases of meta- Tuberosity of reef tarsal tatarse 1] e.clatarsai bones metatarsa bones Tuberosity \“ r ff Bg Internal cuneiform ys Groove for bone ‘ tendon of ) yt “ peronaeus ; 7 tg longus Middle cuneiform * (= a | Tuberosity of bone ; Tuberosity of euboid bone mélatarsal ¥ External cuneiform bone Tuberosity of ( External He 4 , » Cuboid bone Reeeiiorm navicular bone s eo bone . ° 5 Tarsus = Head of talus Trochlea of talus External process of talus Head of talus ; Calcaneus Sustentaculum tali External process of tuberosity Tuberosity of calcaneus of calcaneus (internal process) Fig. 153. Fig. 154. ‘oO ss20ML SOLD] S0¢f OG] ‘Ol proravu sof gavfums appmiply : smauoy, sanppoy prey 4V vf Jv HvOpus] J0f JAOOMT) 4 snauvzjod 40f Javf AVJNIJAV 4O14I}S0cf ssav04dd JOUIIJXY ssa204d SNIUDIPDI pOUdIIXY sof yoovot . 1D) Ssnzjns AvINIAD 2zIPPIW ‘Pre 1?) 21S tg snauvgv9 40f Jaf SV]NIVAD 4OU4IUY ‘ ‘ Apog snouoy, Slanppoy , A, woxapf fo uopuay 40f 2A00d1) - vapyIod J (2J24IQN}) POUAI}JUI) ss2204 AOI JS Oc] (avjngiapu sof aovfins apjnjij4v) peax{ . 3 GG] 214 snaupgqwo Jo ssasoad ADapYyIod L auog plogn) i») = 4 ta saduvjeyd snauDI]D-D SNS41L}EJIW auog WAoflaUuny JOUAIJX] guog ulsofiaung ajpp1W 2 = —% Ae a5 auoqg ADINIIADN 2S40} SHUIS Snsaey i wn 2 — OP eye a « 6 7 ¥s +4 +4 The neck is distinctly constricted only upon the upper and outer surface; upon the lower and inner aspect it is not sharply defined from either the head or the body of the bone. The head of the talus (astragalus), the rounded anterior extremity of the bone, presents an ellipsoidal articular surface for articulation with the navicular bone. THE SKELETON OF THE LOWER EXTREMITY. 103 The posterior process is sometimes an independent bone, and is then designated as the os trigonum. It represents what is usually an independent bone in the lower vertebrates. THE CALCANEUS. The calcaneus (Figs. 158 to 160) is the largest of the tarsal bones, and forms the’ postero- inferior portion of the tarsus. It articulates with the talus (astragalus) by means of three articular facets and with the cuboid bone, and has its longitudinal axis directed from behind forward and slightly from within outward. The main portion of the bone is termed the body. The posterior thickened extremity is known as the /uberosity and projects posteriorly far beyond the remaining bones of the foot; its plantar surface presents two processes or tubercles, the infernal and external process (Fig. 153), and in front of the tuberosity is flat and covered by the long plantar ligament (see page 141). Upon the upper aspect of the calcaneus (Fig. 160) may be observed the three facets for articulation with the talus (astragalus); they are known as the posterior, middle, and anterior articular facets. The posterior is the largest and is markedly convex, the middle and anterior are slightly concave, and the anterior is the smallest. The middle facet lies upon the sustenta- — culum tali, and between the middle and posterior is a groove, the sulcus calcanei, which is wider externally than internally and, together with the sulcus tali, forms the sinus oj the tarsus. : : : bs The markedly concave internal surface of the calcaneus (Fig. 158) presents a broad process, the sustentaculum tali, which projects toward the talus (astragalus) and bears the middle facet for articulation with that bone. Below it is a broad groove, the direct continuation of that upon the posterior process of the talus (astragalus), known as the groove jor the flexor hallucis longus. A similar but shallower groove is situated upon the otherwise flat vertical external surface of the bone (Fig. 159), the peroneal groove, and above this there is usually a small blunt projec- ~ tion known as the ¢rochlear (peroneal) process. The anterior surface of the calcaneus presents a saddle-shaped facet, for articulation with the cuboid bone. THE NAVICULAR BONE. The navicular or scaphoid bone (Figs. 161 and 162) is situated at the inner side of the tarsus between the talus (astragalus) behind and the three cuneiform bones in front (Figs. 153 and 154). Its long axis is placed transversely to the axis of the foot, and it is convex anteriorly, markedly concave posteriorly, and distinctly convex upon its dorsal surface. Near the inner _ border of the plantar surface it presents a strong rounded tuberosity. ; The concave posterior surface of the bone (Fig. 163) forms the socket for the head of the I04 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 158.—The right calcaneus seen from the inner surface (4). Fic. 159.—The right calcaneus seen from the outer surface (4). Fic. 160.—The right calcaneus seen from above (4). Fic. 161.—The right navicular bone seen from behind (+4). Fic. 162.—The right navicular bone seen from in front (+). Fic. 163.—The right cuboid bone from the inner surface (+4). Fic. 164.—The right internal cuneiform bone seen from in front (4). Fic. 165.—The right middle cuneiform bone seen from behind (4). Fic. 166.—The right external cuneiform bone seen from behind (+). THE CUBOID BONE. The cuboid bone (Fig. 163) is situated on the outer side of the foot, in front of the anterior extremity of the calcaneus and behind the bases of the fourth and fifth metatarsal bones (Figs. 153 and 154). It is irregularly cuboid in form and its inner border is longer than the outer one. Its dorsal surface is convex, its anterior surface presents two articular facets for the bases of the fourth and fifth metatarsal bones, and its posterior surface is saddle-shaped and articulates with the calcaneus. The internal surface (Fig. 163) presents a flat articular facet for connection with the external cuneiform bone, and a small inconstant one for the navicular, and the external surface is narrow and forms a part of the outer border of the foot. ‘The plantar surface presents a flattened tuberosity (Fig. 153), in front of which is situated a broad groove, the peroneal groove, which is lined with cartilage and accommodates the tendon of the peroneus longus muscle. THE CUNEIFORM BONES. The three cuneiform bones (Figs. 164 to 166) are situated between the navicular and the bases of the first three metatarsal bones, and, as their name indicates, are more or less wedge- shaped. The internal or first cuneiform bone (Fig. 164) is by far the largest and also the longest of the three, and it has the narrow edge of its wedge directed dorsally, so that its plantar surface is much broader than the dorsal surface. Its internal surface is directly continuous with the narrow dorsal one; the anterior semilunar surface articulates with the base of the metatarsal bone of the great toe; the posterior triangular surface articulates with the navicular bone; and the external surface is in contact with the middle cuneiform and with the base of the second metatarsal bone, and exhibits articular facets for both. The middle or second cuneiform bone (Fig. 105) is the smallest and the shortest of the three. The thin edge of its wedge is directed downward and is almost concealed between the external and the internal cuneiform bones; its base forms part of the dorsal surface of the foot, and its posterior surface presents a triangular articular facet for the navicular bone. The middle cuneiform also articulates with the second metatarsal, and with the external and internal cuneiform bones. The external or third cuneiform bone (Fig. 166) is somewhat larger (especially in length) than the middle one. Its thin edge is likewise directed downward and its broadest surface looks Posterior articular facet Sustentaculum tali Anterior articular 7 Articalar face: facet Jor cuboid Middle articular Jacet Middle articular facet Anterior articular facet Sulcus cali and Articular facet Jor cuboid Posterior articular facet Sustenta- culum tali Groove for tendon : of flexor Tuberosity hallucis longus Inner process of tuberosity Sulcus calcaneti Fig. 158. Bi dy Posterior articular facet Middle articular facet Anterior articular facet Articular Jacet for cuboid Tuberosit vy ey Outer process Trochlear process of tuberosity Fig. 159. Peroneal groove Articalar facet (Head of talus) Articular facet (mid. cuneiform bone) _ Articular facet Articular facet =a (NE cuneiform bone) (metatarsals IV und V) Fig. 162. Articular facet (ext. cuneiform bone) Articular facet (ext. cunciform bone) Tuberosity Fig. 163. 4 Articular facet “fp (Base of metatarsal Il) |! Articalar facet (Base of meta- tarsal li Fig. 104. Articalar facet (ext. caneiform bone) Articalar facet (cuboid bone) Articular facet Articular facet . 4 (navicular bone) (navicular bone) Fig 165. Fig. 166 THE SKELETON OF THE LOWER EXTREMITY. 105 toward the dorsum of the foot. It articulates with the navicular, cuboid, and middle cuneiform, and with the second, third, and fourth metatarsal bones. THE FIVE METATARSAL BONES. The metatarsal bones (Figs. 153 to 155) are typical long bones, each consisting of a prox- imal extremity or base, of a shajt, and of a distal extremity or head. They articulate with the cuboid and cuneiform bones behind and with the phalanges in front, and the bases of the second to the fifth metatarsal bones also articulate with each other. The first metatarsal bone is short and very thick; the second is the longest. The base of the first possesses a broad plantar projection, the ‘uberosity oj the jirst metatarsal, which is directed outward, and that of the fifth presents a similar process, the ‘uberosity oj the jijth metatarsal, which extends some distance beyond the outer border of the foot. The bases of the metatarsal bones exhibit the following articular facets: the base of the first presents a single facet for the internal cunciform bone; that of the second a proximal facet for the middle cuneiform, an inner facet for the internal cuneiform, and two lateral facets for the third metatarsal and the external cuneiform bone; that of the third an internal (frequently a double) facet for the second metatarsal, a proximal one for the external cuneiform, and an external one for the fourth metatarsal bone; the base of the fourth has a proximal facet for the cuboid, two internal facets for the third metatarsal and the external cuneiform, and an external one for the fifth metatarsal bone; and the base of the fifth metatarsal bone presents a proximal facet for the cuboid and an internal facet for the fourth metatarsal bone. The shafts of the metatarsal bones, particularly those of the second to the fifth, become more slender toward their heads and exhibit a curvature, the convexity of which is directed toward the dorsum of the foot. In contrast to their quadrangular bases, they are of triangular prismatic form. The heads of the second to the fifth metatarsal bones are smaller than the bases and are compressed from side to side. They present extensive articular surfaces, convex in the sagittal direction, which extend far upon the plantar surface of the head and serve for articulation with the bases of the proximal phalanges. On the lateral surfaces of the heads are depressions for the attachment of ligaments, and the plantar surface of the strong head of the first metatarsal bone presents two concave articular facets, separated by a ridge, for the two constant sesamoid bones of the great toe. THE BONES OF THE TOES, PHALANGES. The four lesser toes each have three phalanges, but the great toe, like the thumb, has but two (Figs. 153 to 155). The phalanges of the great toe are considerably thicker than those of the remaining four toes, and also thicker than those of the thumb, while the phalanges of the four lesser toes are considerably shorter and more slender than those of the fingers. In other respects the phalanges of the toes are almost exactly like those of the fingers, with the exception of irregularities of development which are most noticeable in the distal phalanges of the two outer toes and are largely to be attributed to the effects of disuse. The middle pha- langes of these two toes are strikingly short, usually even shorter than the terminal phalanges; and in all the toes it is only the proximal phalanges that can be said to be well developed. _ Asin the hand, each phalanx presents a base and a ¢rochiea, and the distal ends of the third 106 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. THE SESAMOID BONES OF THE FOOT. Two sesamoid bones, remarkable on account of their size, are constantly found at the metatarsophalangeal joint of the great toe (Fig. 153). Inconstant sesamoids are also found in the tendon of the peroneus longus muscle, at the interphalangeal joint of the great toe, and less frequently in the tendon of the tibialis posterior muscle. THE SKELETON OF THE FOOT AS A WHOLE. The skeleton of the foot (Figs. 153 and 155) differs from that of the hand not only in the number and form of the component elements of the tarsus, but also in certain peculiarities, chiefly due to the functional adaptation of the foot as a support for the erect body. While the axis of the hand is situated in the direct continuation of that of the arm and forearm, the axis of the foot is placed at almost a right angle to that of the lower extremity, and while in the hand the phalanges take up about one-half of the length of the skeleton, in the foot the tarsus alone occupies the proxi- mal half and the metatarsus and phalanges together form the anterior half. The phalanges make up only a fifth of the entire length of the foot. The foot shows a much more pronounced curvature than do the relatively flat and closely approximated bones of the hand, and this curvature is practically a constant one. The convexity is directed toward the dorsal, the concavity toward the plantar surface, and the deepest point of the concavity is situated at the apex of the middle cuneiform bone, the dorsal surface of the same bone likewise forming the highest point of the middle portion of the arch. The arch of the foot is supported posteriorly by the tuberosity of the calcaneus and anteriorly by the heads of the metatarsal bones. The tarsal arch is formed exclusively by the tarsus and metatarsus and is open internally, since the inner border of the foot is much higher than the outer one, which is in contact with the ground throughout its entire length. The sinus of the tarsus (see page 102) is a striking formation which gradually becomes narrower as it passes inward and backward from the outer side of the dorsal surface. The tarsus is much narrower posteriorly than anteriorly. The phalanges of the second to the fifth toe do not lie in one plane even during extension, but are strongly curved with the convexity upward and seem to be bent upon the heads of the metatarsal bones like claws, so that only their tips touch the ground. The second toe is the longest and marks the longitudinal axis of the foot. Usually the only tarsal bones possessing centers at birth are the calcaneus (sixth month) and the talus (astragalus) (seventh month); the center for the cuboid appears at about the time of birth. The external cuneiform is the first of the three cuneiform bones to ossify (first year), the internal is the next (third year), and the middle one is the last, its ossification and that of the navicular bone occurring respectively in the fourth and the fourth to the fifth year. The cal- caneus alone has a disc-like epiphyseal center upon its posterior surface, corresponding to the tuberosity; this appears in the tenth year and fuses with the rest of the bone at from the fifteenth to the sixteenth year. The metatarsal bones ossify much earlier than do the tarsal bones and ossification proceeds in a manner quite similar to that of the metacarpal bones. The diaphyseal nuclei appear in the eighth to the ninth fetal week. and the epiphyseal centers also are like those of the metacarpal bones, appearing in the third to the fourth year and not uniting with the diaphyseal center until after puberty. The ossification of the phalanges of the foot also corresponds exactly to that of the phalanges of the hand. The diaphyseal cent®rs appear in the third fetal month, the epiphyseal centers in the third to the fourth year, and the union of the epiphyses with the diaphyses, as in the metatarsal bones, occurs after puberty. -s . p * s : P, 2 . 2 | Pie P\ oan in - - ,,. 2. *-. ota .s ’ of ° 2 or * > ;. ve "2 tre Sn 1 ae? “ot ~~ Hi ~3 . 1a," athe — - toe ey, Liss L Pe 4 Sy gat hn Metals Sean: Oot , z t a [a eB he . 4 ~ > * ft . - “ss SE Sr 2s 3 Siete : a. * « <= Fig. 167. Longitudinal (frontal) ection Ss of the of the upper extremity Jemur. mm, U; ae > tad ~~ 3 ES MH NS oy 7 a~| ‘ ~— © aes ~r~ wo OS ~ at ¢ ™ ~~ ~e ~ & Wh S 2 : Cc | 2S S — 3 ot. ’ e an ' ‘ a ’ a % be 4 ® hits “ or i are 5 (Moet | ‘ ? 5 “ < iv +h s . 5 ~~ “ « Ss % ‘ ‘ ) ea ts Longitudinal (frontal) section of the Longitudinal (sagittal) section of the upper extremity of humerus. upper extremity of Ubia. Sagittal section of lumbar vertebra. SYNDESMOLOGY. GENERAL SYNDESMOLOGY. The bones of the body are connected with each other in one of two ways. Two neighboring bones may be connected simply by intervening ligamentous, cartilaginous, or any other form of connective tissue, this form of connection between two parts of the skeleton being called a synarthrosis, or the cartilaginous articular surfaces of two neighboring bones may be so approximated that the two opposed surfaces conform to each other and are separated by a space. Such a mode of connection is a diarthrosis or a joint, and is by far the more perfect mode of connection, allowing of a much more extensive range of motion between the bones. SYNARTHROSES. - The synarthroses are classified, according to the character of the tissue connecting the ends of the bones, into syndesmoses, synchondroses, and symphyses (mixed synarthroses). In the syndesmoses the intervening substance is fibrous connective tissue (usually formed connective tissue, see the Sobotta-Huber Atlas and Epitome of Histology), in the synchondroses it is : cartilage, and in the mixed synarthroses, cartilage and fibrous connective tissue. Synchondroses are rare in the adult body, but are found in those situations in the undeveloped skeleton which subsequently become ossified, such as the connections between the epiphyses and diaphyses of the long bones (see page 21). An example is furnished by the attachment of the first rib to the manubrium of the sternum. | The syndesmoses are subdivided into two groups, (rue syndesmoses and sutures (see pages 79 and 80). The true syndesmoses are those in which interosseous ligaments, which may be elastic, actually connect the bones with each other, and, like the joints, they are frequently strengthened -by accessory ligaments. The lower end of the fibula is firmly connected with the tibia by such a syndesmosis. In the sutures of the skull, however, the soft syndesmotic mass does not con- nect the bones, which are united by the sutures themselves, but rather separates them. A peculiar characteristic of the suture is the interlocking of the contiguous bony margins by means of serrated projections in the serrate sutures, but if one bony margin overlaps the other, like two shingles on a roof, it is spoken of as a squamous suture. Another subdivision of the suture is the relatively infrequent harmonic suture, which is the simple firm apposition of two contiguous bones, and the fixation of the teeth in the alveoli of the jaws may also be designated a variety of syndesmosis, the gomphosis, the syndesmotic mass in this instance being furnished by a thin layer of periosteum (see page 68). In the mixed synarthroses or symphyses the tissue connecting the ends of the bones is fibro- age. Typical examples are furnished by the connections of the bodies of the vertebre 107 108 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. by the zutervertebral fibrocartilages, and by the connection of the two pubic bones by the inter- pubic fibrocartilage. We occasionally find a combination of a synarthrosis (particularly the syndesmosis) with a joint, as in the connection of the sacrum with the innominate bone, or articular spaces may appear within the symphyses, and such arrangements are termed half-joints (amphiarthroses). DIARTHROSES. The diarthroses or true joints are characterized by congruent cartilaginous surfaces which are separated from each other by a capillary space, and are provided with a number of struc- tures, the majority of which are absent in the synarthroses. These are the articular capsules, the accessory ligaments, and the articular cartilages. They may also be provided with special structures, such as the interarticular cartilages or menisci, diverticula of the synovial membrane forming synovial burse, glenoidal lips, joint cushions (designated by different names in the different joints), and bony locking mechanisms. The articular capsule usually surrounds the cartilaginous articular surfaces of the con- tiguous bones so~as to form a completely closed articular cavity. It consists of an external firm fibrous layer, the fibrous layer, and of an internal softer vascular layer, the synovial layer or membrane. ‘The latter gives off microscopic thread-like vascular processes of irregular shape, the synovial villi, and occasionally it forms large structures visible to the naked eye, the synovial folds. The articular cavity, usually a capillary space, is filled with a viscid fluid, the synovia. The articular capsule varies in thickness; it is sometimes strengthened by aecessory liga- ments and sometimes interrupted, so that diverticula of the synovial membrane protrude through its openings and form synovial burs (see also page 143), whose cavities are consequently directly continuous with that of the articulation (communicating synovial burs). (ye Accessory ligaments form important components of the articulations, and according to. function the ligaments of the body can be subdivided into the following classes: (1) Ligaments o} fixation; 1. e., those ligaments which firmly unite two bones, as in the syndesmoses. (2) Ke- injorcing ligaments of the joint capsule; these are more or less adherent to the capsule itself, but sometimes appear as independent structures. (3) Check ligaments, 7. e., ligaments which are capable of limiting certain movements of the joint. (4) Ligaments oj conduction, 1. e., liga- ments whose function is to conduct vessels and nerves to a part of a bone. (5) Ligaments which take the place of bone. These last are found in those situations where neither fixation, nor inhibition, nor any other of the usual functions of a ligament is required; they extend between portions of the same bone or convert a notch into a foramen. The interarticular cartilages or articular discs (termed menisci when of a purely fibrous character) serve to adapt mutually articular surfaces which are not completely congruent. ‘They are attached to the inner surface of the joint capsule and extend for a varying distance between the cartilaginous ends of the bones. In the most extreme cases they divide the articular cavity into two portions, so that the articular extremity of one bone is in relation to one side of the articular disc and that of the other bone to the other side. In such a joint the articular extremities of tle two bones are not in immediate contact with each other, and it is consequently possible to distinguish wnilocular and bilocular joints. GENERAL SYNDESMOLOGY. 10g In other cases the discs or menisci are perforated in the middle or they are semicircular _ in shape, so that the cartilaginous extremities of the bone are in contact only in the middle of c the articulation. The menisci frequently serve the purpose of deepening the socket of a joint or they may act as joint cushions. The articular margins or glenoidal lips are usually circular connective-tissue or fibrocartil- aginous structures which are situated upon the margins of the bony socket for the purpose of increasing its size. The joint cushions, usually consisting of fatty tissue, fill out the space in many of the joints, and are for the purpose of breaking the jar of the movements of the ends of the bone. Bony locking mechanisms limit the movement of a portion of the skeleton, the movable part striking against a bony projection. A joint is usually composed of only two bones, in which case it is termed a simple joint. Sometimes, however, three or more bones enter into the formation of a joint or portions of the socket are formed of connective-tissue components (ligaments, etc.), in which case the joint is termed a com pound joint. The joints of the human body are classified according to the shape of their articular sur- faces. These subdivisions are as follows: (1) Uniaxial joints; (2) biaxial joints; (3) polyaxial joints. The uniaxial joints are composed of two varieties, those with a transverse axis and those with a longitudinal axis; 7. e., the axis of motion in the first variety is at right angles to the axis of the moving bone and in the second variety the two axes are coincident. i. UNIAXIAL JOINTS. (a) With a Transverse Axis.—The hinge joint or ginglymus belongs in this class. These joints are broad and the articular surfaces are usually not quite cylindrical, the convex surface __ exhibiting a median excavation and the concave socket a corresponding elevation. This con- | formation together with strong lateral ligaments prevents the lateral displacement of the bones, so that the axis of motion coincides with the axis of the cylindroid and is consequently horizontal. The motions permitted by a ginglymoid joint are designated as flexion and extension, and in complete extension the bones form an angle of 180 degrees. Types of the ginglymus or hinge joint are furnished by the interphalangeal joints of the fingers and toes. The spiral or cochlear joint forms a subvariety of the hinge-joint. The excavation in the cylindroid and the elevation in the socket form a portion of a spiral, and as a result of this for- mation, flexion is accompanied by a certain amount of lateral deviation. Examples are fur- _ nished by the ankle-joint and by a portion of the elbow-joint. (b) With a Longitudinal Axis.—The only joint of this character is the pivot or trochoid joint, also termed a J/ateral ginglymus. The articulating surfaces are horizontal sections of a cylinder or cone and the solid cylinder rotates upon its axis in a hollow cylindrical socket. The _ superior radio-ulnar articulation and the median articulation of the atlas and axis are typical _ examples of this form of joint. IIo ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 2. BIAXIAL JOINTS. This class of joints includes the ellipsoidal or condyloid joint and the saddle joint. In the ellipsoidal joint the convex surface of an ellipsoid of rotation articulates with a cor- responding concavity, and the two axes of motion, the lesser and the greater axis, are placed at right angles to one another, but both pass through the same bone. An example is found in the atlanto-occipital articulation. The saddle joint is formed by the approximation of two saddle-shaped surfaces, 2. e., sur- faces which are concave in one direction and convex in the other. Each surface alternately forms a head and a socket, and the two axes are at right angles to one another but are situated in different bones. The most typical saddle joint of the human body is the carpometacarpal articulation of the thumb. In reality the motions in the ellipsoidal and saddle joints are not strictly biaxial, but may occur in any intervening axis between the two, and one of the two motions is frequently so lim- ited that the joint practically becomes a ginglymus. 3. POLYAXIAL JOINTS. The only polyaxial joints are those with spherical surfaces, the spheroid joints. ‘These are subdivided into two varieties, the gliding joints or arthrodia and the ball-and-socket joint or enarthrosis. . In the arthrodia a spherical head moves in a spherical socket, but the articulating surfaces are segments of very large spheres, and may seem in some cases to be almost planes. Com- paratively little motion can take place between the surfaces, and what does occur 1s more or less of a gliding character. Good examples of arthrodia are to be seen between the articulating processes of the vertebre. In the enarthroses the articulating surfaces are more extensive segments of smaller spheres and the capsular ligaments are roomy and relaxed, so that a considerable range of motion is possible between the two bones. Typical examples of these ball-and-socket joints are to be found in the shoulder-joint and hip-joint. SPECIAL SYNDESMOLOGY. JOINTS AND LIGAMENTS OF THE VERTEBRAL COLUMN. THE CONNECTIONS OF THE VERTEBRAL BODIES. The bodies of the true vertebra are connected by intervertebral jibrocartilages (Figs. 172 to 175), each of which (Fig. 174) consists of an external firm fibrous ring composed of concentric and interwoven bundles of connective tissue, and of a central gelatinous or pulpy nucleus, the latter being firmly compressed within the fibrous ring and between the adjacent vertebral sur- faces so that it rises above the level of a horizontal section of the disc. Among other substances it contains trué cartilage and the remains of the chorda dorsalis, an embryonic structure which indicates the future position of the vertebral column and is composed of a substance resembling JOINTS AND LIGAMENTS OF THE VERTEBRAL COLUMN. II! cartilage. The intervertebral fibrocartilages are attached to the upper and lower surfaces of the contiguous vertebra, which are covered with a thin layer of cartilage. The area of the intervertebral fibrocartilages is somewhat greater than that of the vertebral surfaces between which they are situated, and they are thickest in the middle, where they rest against the slightly concave surfaces of the vertebra. There is no fibrocartilage between the atlas and the axis; the first one is situated between the second and third cervical vertebra and the last one between the fifth lumbar vertebra and the sacrum. There are consequently twenty- three intervertebral fibrocartilages. Like the bodies of the vertebra, they increase both in cir- cumference and in height from above downward; the smallest and thinnest are situated between the cervical vertebra, the largest and thickest between the lumbar vertebra. The lowermost discs are much thicker (about one-third) in front than behind, a condition which is particularly noticeable in the last one, which is situated at the promontory. THE INTERVERTEBRAL ARTICULATIONS. In addition to the mixed synarthrotic connection between the vertebral bodies, the true verte- bre also articulate with each other by means of the intervertebral articulations. The two superior articular processes of a vertebra articulate with the two inferior articular processes of the over- lying bone (see page 23), and the cartilaginous surfaces of each joint are enclosed by an articular capsule, which is relaxed in the cervical and tense in the lower vertebral region. There are no accessory ligaments. The joints are really arthrodia, and the synarthrotic connections of the bodies and the ligaments of the arches limit their range of motion to a considerable extent. THE LIGAMENTS OF THE VERTEBRAL COLUMN. The ligaments of the vertebral column are composed of two groups: those which run through- out the entire length of the vertebral column; and those which regularly recur between the con- tiguous vertebra. The first group consists of the /ongitudinal ligaments, of which there is an anterior and a posterior one. The anterior longitudinal ligament is attached to the anterior surfaces of the vertebral bodies and of the intervertebral fibrocartilages; the posterior one (partly) invests their posterior surfaces. The anterior longitudinal ligament (Figs. 172, 180, and 185) commences at the pharyngeal tubercle upon the base of the skull as a narrow band which becomes much wider as it descends, and it terminates upon the anterior surface of the sacrum. It is intimately united to the inter- vertebral fibrocartilages, but is only loosely connected with the middle concave portions of the vertebral bodies. The ligament gradually disappears laterally by becoming continuous with the periosteum of the bodies of the vertebra, and is composed of long superficial fibers and of short deep ones which pass from one vertebra to another. The posterior longitudinal ligament (Figs. 173 and 177) extends along the posterior surface of the vertebral bodies as the anterior ligament does along their anterior surfaces, but it is con- siderably narrower than the anterior ligament. It begins as an independent ligament at the second cervical vertebra, but it is continued upward to the cranial cavity as the fectorial mem- brane (see page 115). It becomes narrower as it descends and terminates in the sacral canal. tis likewise composed of a superficial and of a deep layer. II2 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 172.—The anterior longitudinal ligament in the lower thoracic portion of the vertebral column, together with the costo-vertebral ligaments seen from in front (3). Fic. 173.—The posterior longitudinal ligament in the lower thoracic and upper lumbar portions of the vertebral column. ‘The vertebral arches have been removed (3). Fic. 174.—Horizontal section through an intervertebral fibrocartilage (somewhat enlarged). Fic. 175.—Two thoracic vertebre divided longitudinally in the median line and showing the ligamenta flava. Fic. 176.—The ligamenta flava of the thoracic vertebral arches seen from in front, the arches having been separated from the bodies. The left ribs have been disarticulated and removed; the right ones are retained in their natural position (#). Fic. 177.—The posterior longitudinal ligament and intervertebral fibrocartilages of the lumbar vertebre, the vertebral arches having been removed (3). Fic. 178.—A longitudinal section taken at about 45 degrees to the median plane through four thoracic vertebre to show the costo-vertebral articulations (3). Fic. 179.—The ligaments of the middle and lower thoracic vertebre and their ribs, seen from behind (3). Fic. 180.—The ligaments of the middle and lower thoracic vertebre and their ribs seen from the left side. The uppermost rib has been disarticulated and removed (3). It widens opposite each intervertebral fibrocartilage, to which it is firmly united, but it is but loosely connected to the bodies of the vertebra, being separated from them by venous plexuses. In addition to the longitudinal ligaments, this group also contains a portion of the supra- spinous ligament. It will be described subsequently, however, together with the interspinous ligaments with which it is intimately connected. The short ligaments of the vertebral column, connecting contiguous vertebre, are sub- divided into those connecting the arches and those connecting the processes. The ligaments between the vertebral arches, the ligamenta flava (Figs. 175 and 176), are strong and are composed almost entirely of elastic tissue, to which they owe their pronounced yellow color and hence their name. They extend anteriorly as far as the posterior margins of the articular capsules of the intervertebral articulations and consequently close the vertebral canal except at the situation of the intervertebral foramina. With the exception of a distinct groove in the median line, their internal surface is absolutely smooth and is directly continuous with the inner surfaces of the vertebral arches. By their elasticity they keep the posterior wall of the vertebral canal smooth during flexion of the vertebral column and they also support the backward movement of the vertebral column during extension. They commence between the second and third cervical vertebrae (sometimes between the first and second) and extend to the last lumbar vertebra, and are strongest below and weakest above. The intertranverse ligaments (Figs. 179 and 180) are unimportant and inconstant ligaments connecting the transverse processes of the vertebra; they are particularly developed in the thoracic and lumbar regions. The interspinous ligaments (Fig. 175) connect the spinous processes of contiguous vertebre _ and attain their greatest development in the lumbar region. They are continuous anteriorly with the ligamenta flava and posteriorly with the swpraspinous ligament (Fig. 179) which. con- , nects the apices of the spinous processes and forms an independent ligament. The interspinous Anterior costo-_ transverse ~ ligaments Ribs Posterior longitudinal ligament ~ ~ere fi 7 f % SS ON Radiate ligaments Anterior longitudinal ligament - QS \\ /nterverte- bral Tibro- cartilages ee Intervertebral foramen Ligamentum flavum Pulpy nucleus Interspinous P. ligament Fibrous ring Intervertebral fibrocartilage Fig. 175 Inferior verte- bral notch Ligamentum flavum _ Articular facets for costal tubercles 1 ¢rie- é ral ar ches Liga- Liga- ? oy menta Q Jlava costal 4 ; neck Posterior . longitudinal — \ ligament bral fibro Ribs X Vertebral carti arches X “ages a i Fig. 176. Vertebral body Interarticular ligament Intervertebral foramen igament of costal S@eey neck Sacrum & Posterior costo- transverse ligament = Fig. 177. Intervertebral Head of rib Tubercle of rib Jibrocartilage Fig. 178. OS! “814 ‘OL1 ‘Ol suawovdy apoipoy SATU] PADIOM LY jusuivdsy snourdsosdns [DAQIJIINGI]U | pususns) ISMIASUDAL syuauvgy) -AIUT ISAIASUDAJOJSOI 10149]S0¢] uauvdy yourpnyisiuop 4014ajUYy < SQM staswassoyean a dy 3 : vjsoo fo 40}42)UY ] SJUIUIDIIT] Sjuawmody ISAIASUDAY -0}S09 AOMMIUY ap249QMy yDISOI dof joovy jaovf avjnaiyiv 401uadng qu fo pvay sof 2IDY [I] D4qa}iaa poss Jo Apog / as vptPsVIOAQ UY PVAQIIINAI LU juasuvsly pourp nprIuop, SOLIIJUY apynsdv ADpNIyY at auog pouidia20 fa SU 0} D]NII 4D uoriod jv4iajo7] ]VISOIOUINS aupsquiaut ; popidia20-0;uv]JO s0LaJUY auog pojidiv0 fo uonsod avpisvg — IL] ev] 14vs 1VJSOD ] ! ‘ESI “Old ‘In pvjsoIousas SINY ADININADAIJ UT ajpnsdvg sD]NIIY AUZPAD JDAGIJIIA 40f JAOOIT) [[ advpijivs 10JS0D svpv fo ssavosd sisoapuoyqUss ISAIASUDL DUIS | adpjijAvd 1vjSOD aupaguiad 10}1d1990-OJUD}JV 40j494S0q] auog 70310199 A adppijava 1DjS0) Y Al asvpiyasvs Jo}S0D JOINTS AND LIGAMENTS OF THE VERTEBRAL COLUMN, TIs Passes downward and is inserted Into the posterior surface of the body of the axis (epistropheus), The combination of these fascicyli with the transverse ligament forms what is known as the cruciate ligament (F ig. 187), The joint Possesses three other ligaments which arise from the Odontoid process of the axis, a small weak middle ligament and tWo strong lateral] ligaments, The middle ligament js known as the apical odontoid ligament (F ig. 188) and runs from the tip of the Odontoid process to the Margin of the Occipital bone. It is a quite thin and insignificant Structure and has Scarcely any mechanical] function. Jt Contains remains of the chorda dorsalis (see page 110), he vertebral canal by a firm broad ligamentous Mass, the fectorig] h forms a smooth surface exhibiting in reljeg the underlying odontoid In the skull it is continuous with the dura Mater, and below it is yers of the posterior longitudinal] ligament. J; is separated from of the articulation of the first two cervical] vertebre with the occiput ] membranes, which Serve to close the broad spaces The anterior atlanto-occi pital (obturator) mem- 116 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 185.—The tectorial membrane seen from behind. The posterior portion of the occipital bone and the arches of the three upper cervical vertebra have been removed, as well as the cap- sular ligaments of the right side (;%5). Fic. 186.—The atlanto-odontoid articulation. The odontoid process (dens epistrophet) and the anterior arch of the atlas have been cut (+5). Fic. 187.—The cruciate ligament after removal of the tectorial membrane. The articular capsules have also been removed on the right side (3%5). Fic. 188.—The alar ligaments after removal of the cruciate ligament. The articular capsules as in the preceding figure (3%). THE ARTICULATIONS OF THE RIBS WITH THE VERTEBRAL COLUMN AND WITH THE STERNUM. The posterior extremities of the ribs are connected with the thoracic vertebrae by arthrodial joints (Figs. 172, 176, and 178 to 180); their anterior extremities (Fig. 181) articulate with the sternum or with each other by means of either arthrodial joints or synchondroses. The anterior extremities of the two lowermost ribs are not attached to any portion of the skeleton. The ribs are connected to the vertebre by a double articulation. The head of each rib articulates with the bodies of two adjacent vertebre (the exceptions are given upon page 26) and the tubercles of the ribs, with the exception of the last two (see page 27), articulate with the transverse processes. The articulations of the heads of the ribs, with the exception of the uppermost and the two lowermost, are characterized by the fact that the intervertebral fibrocartilage between the two vertebre forming the articular cavities is continued, as the interarticular ligament (Fig. 178), as far as the crest upon the head of the rib, and divides the articulation into two compartments. The weak articular capsules are reinforced by the radiate (stellate) ligaments (Figs. 172 and 180), which arise from the head of the rib and radiate to the lateral surfaces of the bodies of the vertebree forming the articulation. The costo-transverse articulations have capacious capsules and are characterized by possess- ing quite a number of reinforcing or check ligaments. The posterior surface of the capsule is reinforced by a short tense ligament, the ligament of the costal tubercle (posterior costo-transverse ligament) (Fig. 179), which is approximately quadrangular and composed of parallel fibers, and extends outward and slightly upward from the tip of the transverse process to the posterior sur- face of the neck of the articulating rib. The ligament of the neck (middle costo-transverse or interosseous ligament) (Fig. 178) almost completely fills the space between the neck of the rib and the transverse process of the thoracic vertebra. It is horizontal and passes from the anterior surface of the transverse process of the vertebra to the posterior surface of the neck of the rib. The costo-transverse (superior costo- transverse) ligaments run between the posterior extremities of the ribs and the transverse proc- esses, and each may be regarded as consisting of an anterior and a posterior costo-transverse liga- ment, both of which pursue a similar course from the neck of the rib to the transverse process of the overlying vertebra. The anterior ligament (Figs. 179 and 180) is tolerably strong and approximately rhemboid in shape; it passes from the lower margin of the transverse process Occipital bone Transverse process Articular capsules Transverse process of cervical vert. 111 Membrana tectoria Fig. 185. Alar Cruciate ligament ligaments (superior limb) Basilar portion of occipital bone Hypoglossal canal Pog Articular capsule Spinous proc. of axis Post articular surface of odontoid proc. Superior articular fa cet Transverse Body of axis ligament of . Odontoid process Cruciate lig. — atlas Ant. artic, ; surface of — —_ odontoid proc. Facet for f ig. 1S ‘ odontoid process Fig. 180. Apical odontotd ligament Alar ligaments Occipital bone QOdontoid process Body of axis f —7 ° : i~ ¢ a ~ tng ee . + * 7 ‘ . = . * bs ¥ ’ \ 1 oo ' ‘ . r = 2 é ri , ‘ é Us: ¢ a ws Neh ’ er nee ' te é “ss bs a oie x ) gem al * : J hy iin Le ae va ~ ‘ 4,948 ar Se, =~ ee THE ARTICULATIONS AND LIGAMENTS OF THE HEAD. Il7 and frequently also from the lower border of the adjacent rib to the neck of the next lower rib. The posterior ligament (Fig. 179) is much weaker than the anterior one; it is triangular in shape and runs from the base of the transverse process (or also from the articular process) to the pos- terior surface of the neck of the next lower rib. The two ligaments form the boundaries of an opening, the costo-transverse joramen, which gives passage to the intercostal branch of the spinal nerve. The movements of the ribs upon the vertebre are considerably limited by the surrounding check ligaments. The two joints, that of the head and that of the tubercle, act together as a combined articulation which partakes of the nature of a pivot joint, whose axis corresponds to the neck of the rib and is therefore almost transverse. The movement about this axis is such that the anterior extremities of the ribs are elevated, and the distance between their anterior extremities and the vertebral column is increased. The costal cartilages are connected with the sternum partly by synchondroses and partly by movable joints, the sterno-costal articulations (Fig. 181). The first costal cartilage is always united to the sternum by a synchondrosis, but between the anterior extremities of the second to the seventh costal cartilages and the sternum, however, there are usually true joints. The second sternocostal articulation (and frequently the remaining ones) always contains an inter- articular ligament (Fig. 181) which passes from the synchondrosis between the manubrium and the body of the sternum, or from the outer margin of the body, to the anterior extremity of the costal cartilage and divides the joint into two compartments. This ligament is inconstant in the articulations of the third to the seventh costal cartilages with the sternal border, and when it is present it is frequently so situated that the articulation is unequally subdivided. The anterior surfaces of the articular capsules of the sternocostal articulations are rein- forced by the radiate ligaments (Fig. 192) which arise from the ends of the costal cartilages and spread out like fans upon the anterior surface of the sternum. The interlacing fibers of the radiate ligaments of the lower cartilages form a membrane, the sternal membrane, upon the anterior surface of the lower portion of the sternum, and are blended with the periosteum in this situation. Joints, which are known as the interchondral joints, may also be present between the costal cartilages of the fifth to the tenth ribs (see page 33), and in the sternum itself there is a sternal synchondrosis (see page 34) between the manubrium and body which frequently has an articular cavity, and sometimes also a synchondrosis between the body and the xiphoid process. The intercostal ligaments are really modified fascize which will be considered in the descrip- tion of the muscles (See page 169). The actual range of motion of the costal cartilages in the sternocostal articulations is quite limited, but it is con- siderably increased by the elasticity of the cartilages themselves. The costovertebral and the costosternal articulations act simultaneously and in the same manner. THE ARTICULATIONS AND LIGAMENTS OF THE HEAD. The only movable joint between the bones of the head is the temporo-maxillary articulation. The remaining bones are united by sutures, the terminology of which has already been discussed 118 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 189.—The right temporo-mandibular articulation seen from the outer side (4). Fic. 190.—The right temporo-mandibular articulation seen from the inner side (4). Fic. 191.—The right temporo-mandibular articulation opened by a sagittal section. The zygomatic arch has been removed (4). in the section upon osteology. Considerable quantities of connective tissue are found only in the sphenopetrosal fissure, in the foramen lacerum, and in the petro-occipital fissure (spheno- petrosal and petro-occi pital synchondroses). THE TEMPOROMANDIBULAR ARTICULATION. The temporomandibular articulation (Figs. 189 to 191) is the joint between the condyloid process of the mandible and the mdndibular fossa of the temporal bone. It is completely ° subdivided into an upper and a lower portion by an oblong, biconcave articular disc (Fig. 191), which is adherent to the capsular ligament by its circumference. The two joints which are thus formed, namely, that between the mandible and the disc and that between the disc and the mandibular fossa, act separately. The articular capsule of the joint (Fig. 191) is rather thin and relaxed. It embraces the mandibular fossa as far as its posterior non-cartilaginous surface, the articular eminence, and the head of the condyloid process, and is inserted into the neck of the mandible. Its external surface is reinforced by a ligament passing from the zygoma to the neck of the condyloid process, the temporomandibular (external lateral) ligament (Fig. 189), and its fibers pass from above downward and from before backward. In the temporomandibular articulation the socket is formed partly by the mandibular fossa and partly by the articular eminence, and over the latter an approximately congruent surface for the head of the condyle is formed by the articular disc. The two temporomandibular articulations act simultaneously. When the mouth is opened the head of the condyle with the interarticular disc glides forward upon the articular eminence, and when the mouth is closed it slips back into the mandibular fossa. The opening and closing of the mouth are consequently attended by a sliding of the mandible (a gliding joint). In addition to this modified form of hinge movement, the articulation possesses a second kind of motion, the lateral displacement of the mandible in reference to the skull. In this movement one condyloid head remains in the mandibular fossa while the other advances upon the articular eminence, a movement which is impossible when the mouth is opened to its greatest extent. Both the hinge and the lateral movements are combined in the act of mastication. INDEPENDENT LIGAMENTS IN THE HEAD. In the vicinity of the temporomaxillary articulation, but without any direct connection with the joint, are situated two ligaments, the sphenomandibular ligament (Fig. 190) and the stylomandibular ligament (Figs. 191 and 192). The sphenomandibular ligament arises from the under surface of the greater wing of the sphenoid bone near its spine and is inserted into the lingula of the mandible. The stylomandibular ligament takes origin from the styloid process, which is frequently embedded in the ligament for some distance, and passes to the inner surface of the angle of the jaw. Both ligaments are weak and resemble fasciz, ‘and this is particularly true of the stylomandibular ligament, which radiates directly into the fascia of the internal pterygoid muscle (buccopharyngeal fascia, see page 184). Jemporomandibular ligament Zygomatic arch External auditory meatus Plerygoid process Temporal bone SpHenoid bone Sphenomandi- bular ligament Coronoid Mastoid process process Stylomandibular ligament Condyloid process Fig. 189. Articular eminence Zygomatic Fig. 190. process of oO atip temporal Zygomatic bone x bone x External pterygoid muscle Articular capsule : Coronoid process Articular disc Condyloid process x Fig. 191. THE JOINTS AND LIGAMENTS OF THE UPPER EXTREMITY. 119 In addition to these structures, the head possesses another independent ligament, the plery- gospinous ligament, which passes from the spine of the sphenoid bone to the upper extremity of the outer plate of the pterygoid process. Sometimes this ligament becomes ossified, and it then forms the pterygospinous process (Civinini). THE LIGAMENTS OF THE HYOID BONE. The greater cornua of the hyoid are connected with the body of the bone cither by movable joints or by synchondroses, or they are united by synostoses. The lesser cornua are frequently cartilaginous and are connected to the body by movable joints or by syndesmoses. Each lesser cornu is connected to the styloid process of the temporal bone by the styloh yoid . ligament. A portion of the lesser cornu, or a rod of cartilage not connected with the hyoid bone, sometimes extends into the stylohyoid ligament, and in a similar manner the styloid process or a separated bony spicule may extend far into the ligs- ment. All three portions, the lesser cornu, the stylohyoid ligament, and the styloid process, have a common ongin in the second visceral arch. THE JOINTS AND LIGAMENTS OF THE UPPER EXTREMITY. THE STERNOCLAVICULAR ARTICULATION. The sternoclavicular articulation (Fig. 192) is the joint between the clavicular notch and the sternal articular surface of the clavicle. The two articulating surfaces are incongrucnt, but they are adapted to each other by the interposition of an articular disc, which divides the articulation into two completely separated cavities, the articulation in this respect resembling the temporomandibular joint. The edges of the disc, the inner one in particular, are somewhat thickened. The articular capsule is thin and relaxed, but, except on its inferior portion, it is reinforced upon all sides by strong ligaments. The most striking of these is the sternoclavicular ligament, which is adherent to the anterior surface of the capsule. The interclavicudar ligament is a single ligament which passes across the jugular notch at the upper margin of the sternum and con- nects the sternal ends of both clavicles, thus reinforcing the upper portions of the capsules of both sternoclavicular articulations. The costoclavicular (rhomboid) ligament is exceedingly strong, and although really an inde- pendent ligament it belongs from the functional standpoint to the sternoclavicular articulation. It extends between the cartilage of the first rib and the costal tuberosity of the clavicle, and almost completely fills the space between the sternal end of the clavicle and the first rib. Its fibers are rather short and become tense when the clavicle is but slightly abducted from the “thorax. ' The sternoclavicular articulation is an arthrodial joint and its range of motion would be quite considerable were it not for the reinforcing ligaments, particularly the costoclavicular ligament, which limits its motion to a marked degree. Slight motion of the clavicle is accompanied by a pronounced movement of the scapula, since the clavicle generally acts as a lever for the latter bone. 120 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 192.—The two sternoclavicular joints, together with the costosternal articulations of the two upper ribs, seen from in front. The right sternoclavicular joint has been opened by. a sagittal section (4). Fic. 193.—The left shoulder and acromioclavicular joints seen from above and from the inner surface (3). Fic. 194.—The left shoulder-joint seen from behind, the long head of the triceps being cut and the terminal portions of the supraspinatus, infraspinatus, and teres minor muscles cut and turned outward (#). Fic. 195.—The left shoulder-joint seen from behind and above. The acromion process has been removed, and the neighboring muscles treated as in the preceding figure (#). Fic. 196.—The socket of the left shoulder-joint after removal of the articular capsule and the tendon of the biceps muscle (#). Fic. 197.—A frontal longitudinal section of the shoulder-joint, parallel to the tendon of the long head of the biceps (+). THE ACROMIOCLAVICULAR ARTICULATION. The acromioclavicular articulation (Figs. 193, 194, and 196) is the joint between the acromial articular surface of the clavicle and the acromial articular surface of the scapula, and it conse- quently forms the connection between the two components of the shoulder girdle. The articu- lation may contain an articular disc, but it is small and varies greatly in the degree of its develop- ment; it is frequently incomplete and often entirely absent. The upper portion of the articular capsule is the strongest, and is still further reinforced by the acromioclavicular ligament (Figs. 194 and 196), which connects the bones forming the articulation. A strong ligamentous connection between the acromial end of the clavicle and the scapula is effected by the coracoclavicular ligament (Figs. 193 and 196), which passes from the upper surface of the base of the coracoid process to the coracoid tuberosity of the clavicle. The liga- ment is composed of two parts, an anterior flat quadrangular portion, known as the érapezoid ligament, and a posterior triangular one, broad above and narrow below, the conoid ligament. Between the two the subclavius muscle is inserted. . The acromioclavicular articulation has but a slight range of motion. The coracoclavicular ligament acts as a check ligament, just as the costoclavicular ligament does in the sternoclavicular articulation. ‘The relative position of the two bones, can scarcely be changed voluntarily, but passive movements, producing a change in the angle between the two bones, etc., occur. The small, indistinctly bounded, and usually flat articular surfaces allow of a displacement of the two bones, but the direction of the movement is not determined by the shape of the articular facets. THE LIGAMENTS OF THE SCAPULA. There are three ligaments attached to the scapula (Figs. 193, 195, and 196) which do not belong to any of the neighboring joints. These are the coracoacromial ligament, the superior lransverse ligament, and the inferior transverse ligament. The coracoacromial ligament (Figs. 193, 194, and 196) is a flat, tense, strong ligament which connects the anterior margin of the acromion with the posterior surface of the anterior extremity of the coracoid pgocess. It is situated immediately above the shoulder-joint. The superior transverse ligament (Figs. 193 and 195) is a short, tense ligament which bridges Clavicle » _Articular disc Interclavicular ligament Costoctavicular ligament Articular capsule Costoclavicular ligament Costal cartilage I Manubrium x Fig. 192. Costal cartilage Il Sternal synchondrosis Coracoclavicular ligament (Trapezoid portion) Coracoid process Coraco-acromial ligament Acromion Clavicle Coracoclavicular ligament (Conoid portion) Superior transverse ligament [ntertaubercalar mucous Sheath Subscapularis Long head of biceps Acromioclavicular ligament Acromion Coraco-acromial ligament Supraspinatus ae. Sapras Spine of scapula Infraspinatus Teres minor Humerus Articular [ong head capsule of triceps Fig. 194. Superior transverse ligament Spine of scapula Coracoid process Coracohumeral ligament Supraspinatus Infraspinatus Articular capsule Inferior transverse Long head ligament Teres minor of triceps Fig. 195. ~ . . . Clavicle Acromiodavicular ugament Coracoclavicular ligament (Trapezoid portion) Acromios Coracoclavicular ligament (Conoid portiony Coracold process Coraco-acromial ligament Tendon of long head of biceps Glenoid cavity Glenoidal lip Long head Of triceps Fig. 196. Tendon of long head of biceps Coracoid process Coracohumeral ligament Glenoid cavity Intertubercular mucous sheath Articular capsule Tendon of long head of biceps Fig. 197. ae > ie THE JOINTS AND LIGAMENTS OF THE UPPER EXTREMITY. I21I over the scapular notch and converts it into a foramen. It is occasionally replaced by bone (see page 84). The Suprascapular nerve passes beneath this ligament, while the transverse artery of the scapula (suprascapular artery) passes over it. The tnjerior transverse ligament (Fig. 195) is much weaker than the superior one. It con- sists of delicate connective-tissue fasciculi which form a bridge beneath the base of the acromion where the supraspinous and infraspinous fosse« communicate with each other, and covers certain small branches of the blood-vessels. The ligaments of the scapula belong to that class of liga- ments which take the place of bony structures. THE SHOULDER-JOINT. The shoulder-joint (Figs. 193 to 197) is the articulation between the glenoid cavity of the scapula and the head of the humerus. The glenoid cavity is relatively small and very slightly concave, but it is considerably enlarged and deepened by a markedly fibrous articular lip, the glenoidal lip (glenoid ligament) (Fig. 196), which surrounds the margin of the bony socket. In spite of this, however, the socket of the shoulder-joint is still considerably smaller than the head of the humerus, and consequently does not interfere with the free movement of the latter bone. The articular capsule (Figs. 194 and 195) is roomy and relaxed, as must necessarily be the case in a freely movable enarthrosis. It arises from the margin of the glenoidal lip and is inserted into the anatomical neck of the humerus, and although it is in itself thin, it acquires considerable strength from its adherence to the tendons of the surrounding muscles (supra- spinatus, infraspinatus, teres minor, subscapularis) and to a reinforcing ligament, the coraco- humeral ligament (Figs. 195 and 197). This ligament arises from the outer border of the base of the coracoid process and passes, independently at first and then inseparably connected with the upper and posterior portion of the capsular ligament, to the insertion of the latter structure in the neighborhood of the two tuberosities. A somewhat weaker fasciculus strengthens the inner portion of the capsule. A peculiarity of the shoulder-joint is that it contains, throughout its entire length, the tendon of the long head of the biceps (see page 188). This tendon, which arises from the supraglenoid tubercle and is adherent to the upper portion of the glenoidal lip, passes through the articular cavity beneath the coracohumeral ligament and leaves it at the intertubercular groove, being accompanied for a certain distance outside of the joint by a tubular prolongation of the synovial membrane, the infertubercular mucous sheath (Figs. 193 and 197). This portion of the inter- tubercular groove is lined with cartilage. At the termination of the mucous sheath the synovial membrane is closely adherent to the tendon, and it also extends beneath the tendon of the sub- scapularis muscle in the shape of a bursa which communicates with the articular cavity (Fig. 193). This subscapular bursa has a very thin wall and is situated beneath the concave anterior surface of the coracoid process, between the coracohumeral ligament and the reinforcing fibers _ of the internal portion of the capsule. The shoulder-joint is the most freely movable articulation in the entire human body, and permits of movements in all directions. The chief movements are: pendulu m movements in the sagittal plane, which are more extensive ante- I22 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 198.—The left elbow-joint seen from in front (4). Fic. 199.—The left elbow-joint seen from behind and from the radial side (§). Fic. 200.—The bones of the left forearm with the interosseous membrane; the annular ligament has been divided (4). riorly than posteriorly; raising and lowering of the arm in a coronal plane (abduction and adduction, the former motion not being possible beyond a horizontal plane); and rotation of the arm about its longitudinal axis. During the move- ments of the arm the capsular ligament is thrown into folds upon one side and made tense upon the other and in certain extreme positions it may act as a check ligament. THE ELBOW-JOINT. The elbow-joint is a typical compound joint, being formed by the association of the lower end of the humerus with the upper ends of the radius and ulna, and so consisting of three articulations. The trochlea of the humerus articulates with the semilunar (greater sigmoid) notch of the ulna (the umero-ulnar articulation), the capitulum of the humerus with the depressed surface on the head of the radius (the huwmero-radial articulation), and the radial (lesser sigmoid) notch of the ulna with the articular circumference of the radius (the proximal radio- ulnar articulation). The three articulations are surrounded by a common articular capsule (Figs. 198 and 199), which is roomy and relaxed, particularly in front and behind. It encloses the three fossz at the lower end of the humerus (the olecranal, coronoid, and radial fossze), is attached to the ulna just below the tip of the olecranon, at the margin of the semilunar (greater sigmoid) notch, and at the tip of the coronoid process, and the entire head and the greater portion of the neck of the radius are situated within it. The only portions of it which are firm and tense are the lateral ligaments and the annular ligament which surrounds the upper end of the radius. There may be recognized a radial or external lateral ligament and an ulnar or internal lateral ligament. ‘The radial lateral ligament (Figs. 198 and 199) arises from the external epicon- dyle and passes as two fasciculi to the annular ligament, with which a portion of its fibers are continuous. The ulnar lateral ligament (Fig. 198) arises from the internal epicondyle of the humerus and passes in a radiating manner to the ulnar margin of the semilunar notch. The annular ligament (Fig. 199) is a firm tense ligament which surrounds the head of the radius like a sling and forms three-fourths of the circumference of the socket for the pivot joint of the proximal radio-ulnar articulation, the remaining fourth being formed by the radial (lesser sigmoid) notch of the ulna. The ligament arises from the anterior margin of the semilunar (greater sigmoid) notch and is inserted into the posterior margin of the radial notch. Below it the capsule is thin, and at the neck of the radius forms a small protrusion which is known as the saccular recess. The brachialis anticus muscle passes over the anterior surface of the capsular ligament of the elbow-joint (Fig. 201) and some of its fibers are inserted directly into this structure. The . triceps muscle, particularly its middle head, holds a similar relation to the posterior surface of the capsule, from which the tendon of the muscle is separated by fatty tissue. Semilunar notch Annular ligament » Internal epicondyle Articular Articular _ 9 circumference capsule of radius Tendon of biceps Ani ° P Ulnar lateral ligament- f ieee ps api lateral igament Z| ligament Annular ligament Ulna Tendon of Oblique biceps ligament ) Fig. 198. Interosseous membrang Articular capsule Internal epicondyle External epicondyle Radial lateral ligament Annular : Olecranon ligament Articular capsule of distal radio-ulnar articulation Radius Fig. 200. THE JOINTS AND LIGAMENTS OF THE UPPER EXTREMITY. 123 From a physiological standpoint the elbow is a combination of two joints only, since the humero-radial articulation does not function as an independent joint. These two joints are the hinge joint of the humero-ulnar articulation and the pivot joint of the proximal radio-ulnar articulation. The flexion of the forearm upon the arm is not a pure hinge motion, but rather that of a spiral joint, since the surfaces of the trochlea and the median ridge of the semilunar notch resemble that of the worm of a screw. From a practical standpoint, however, the elbow may be regarded as a ginglymus or hinge joint, whose axis of movement passes through the two epicondyles. The humero-radial articulation is not involved in this movement, since the ends of the respective bones are scarcely in contact during flexion. The axis of the trochlea of the humerus is not placed at right angles to the axis of the humerus, but cuts it obliquely, and, consequently, when the forearm is extended the elbow forms an obtuse angle of about 140 degrees, which is open externally; while when the joint is flexed this angle becomes an acute one. When the forearm is flexed the coronoid process of the ulna rests in the coronoid fossa, and when it is strongly extended, the olecranon is received into the olecranal! fossa, which is cushioned with fatty tissue. The humero-radial articulation is only passively involved in the pivot movement of the proximal radio-ulnar joint, since the radius rotates in the socket about its long axis, and the actual pivot movement takes place in the proximal and distal radio-ulnar articulations. Both movements of the elbow-joint are completely independent. THE DISTAL RADIO-ULNAR JOINT AND THE INTEROSSEOUS MEMBRANE. The radius and ulna are connected by a thin interosseous membrane (Fig. 200) which almost completely fills the space intervening between the two bones of the forearm. It is attached to the interosseous ridges of the two bones and consists for the greater part of fibers which pass obliquely downward from the radius to the ulna. It does not, however, extend to the upper- most part of the interosseous space and possesses an opening in its lower portion for the passage of blood-vessels. It represents a membranous supplement to the bones of the forearm, and, like these structures, it gives origin to various muscles. In addition to the connection by the interosseous membrane, the radius and ulna are held together also by the oblique ligament (Figs. 199 and 200), which passes obliquely from the coronoid process of the ulna to the lower margin of the tuberosity of the radius, and is directly in contact with the upper portion of the interosseous membrane. The distal radio-ulnar joint (Figs. 202 to 204) is the joint between the articular circum- ference of the capitulum of the ulna and the ulnar (sigmoid) notch of the radius, and also between the capitulum of the ulna and the articular disc which separates the head of the ulna from the triquetral (cuneiform) bone. Anatomically it is an independent joint, but it functions in association with the proximal radio-ulnar articulation. The socket for the capitulum of the ulna (Fig. 202) is formed by the ulnar notch of the radius as well as by the articular disc; the portion of the socket formed by the radius is almost _ vertical, and that formed by the disc is practically horizontal, and a portion of the lateral surface as well as the inferior surface of the capitulum of the ulna consequently rests in the socket of the joint. The articular capsule is somewhat roomy and relaxed, and a prolongation of it, known as the saccular recess, extends upward between the bones of the forearm above the level of the articulation. The articular disc is attached upon one side to the ulnar margin of the middle portion of he radius, where it insensibly merges into the cartilaginous covering of this portion of the bone; 124 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 201.—Sagittal section of frozen preparation of the left elbow-joint (4). Fic. 202.—A frozen section through the radiocarpal articulation parallel with the dorsal surface of the hand (4). upon the other side it is attached to the styloid process of the ulna. In rare instances it is perforated. The movement in the distal radio-ulnar joint is a rotation of the radius about the ulna which is simultaneously carried out in the proximal radio-ulnar articulation also. During the movement known as pronation, the radius is applied obliquely to the ulna, so that the two bones cross; the opposite movement, the return to the parallel position of the two bones, is called supination. The axis of movement of both radio-ulnar articulations passes through the heads of both bones and is consequently placed obliquely to the axes of the bones. The angle of rotation of the lower end of the radius about the ulna amounts to about 180 degrees. THE JOINTS AND LIGAMENTS OF THE HAND. The joints of the hand may be divided into those of the carpus and those of the fingers. Those of the carpus are: (1) The radiocarpal or wrist-joint; (2) the intercarpal joint; (3) the joint of the pisijorm bone; (4) the common carpo-metacarpal joint; (5) the carpo-metacar pal joint of the thumb. The joints of the fingers include the metacar po-phalangeal articulations and digital or inter- phalangeal articulations. THE JOINTS OF THE CARPUS. The radiocarpal articulation, the articulation of the pisiform bone, and the carpo-meta- carpal articulation of the thumb are usually independent joints, while the common carpo-meta- carpal articulation is, as a rule, connected with the intercarpal joint. The radiocarpal articulation is the joint between the carpal articulating surface of the radius and the triangular articular disc interposed between the ulna and the triquetral (cunei- form) bone upon one side, and the proximal articular facets of the first row of carpal bones— navicular (scaphoid), lunatum (semilunar), and triquetrum (cuneiform)—upon the other, the navicular and lunate bones articulating with the radius and the triquetrum (cuneiform) bone with the triangular articular disc in such a manner that the radius and the disc together form a socket, while the corresponding articular facets of the three carpal bones form a condyle. The articulation is completely separated from the intercarpal joint, but in rare instances it communicates with the articulation of the pisiform bone. It is separated from the intercar- pal articulation by the short ligaments connecting the navicular, the lunate, and the triquetral (cuneiform) bones. The articular capsule of the joint is thin, capacious, and relaxed, and embraces the car- tilaginous extremities of the bones entering into the articulation. From the shape of its articulating surfaces the radiocarpal articulation is an ellipsoidal joint. The curvature of the surfaces is greater in the sagittal than in the coronal diameter. The iwtercar pal articulation is the joint between the two rows of carpal bones and is formed by the distal articular facets of the navicular, lunate, and triquetral (cuneiform) bones upon Triceps Humerus Coronoid fossa Trochlea of humerus Tendon of triceps Median vein Subcutaneous olecranal bursa ; Brachial artery Synovial cavity Distal radio-ulnar articulation Articular dise ~~ Navicular bone Triguetrum \ Radial lateral ligament Intercarpal articulation \ Greater multangular bone Carpometacarpal articulation Hamatum aN of thumb X\ Metacarpal b ~~ d acarpa one x4 Tas. of thumb Carpometacarpal articulation - Metacarpal bones Capitatum Lesser multangular bone Fig. 202. THE JOINTS AND LIGAMENTS OF THE HAND. 125 the one side, and by the proximal facets of the greater and lesser multangular (trapezium and trapezoid), capitate (os magnum), and hamate (unciform) bones upon the other. The first row of the carpal bones practically forms a socket for the head of the capitatum (os magnum) and the proximal portion of the hamatum (unciform), and toward the radial, and to a certain extent also the ulnar, side of the joint, the proximal row exhibits a convex and the distal row a concave surface, since the navicular bone presents a convexity toward the greater and lesser multangular (trapezium and trapezoid) bones. As a result, the line of the joint is not a simple curve, but has an irregular 0) shape (Fig. 202). The articular cavity of the joint is very complicated, since it extends from the actual articular line both proximally and distally between the individual carpal bones of both rows. It is sep- arated from the radiocarpal joint by the previously mentioned ligaments, and similar ligaments connect the bones of the second row and separate the intercarpal from the carpo-metacarpal articulation. The latter separation is incomplete, however, and these two articulations usually ‘communicate between the capitatum (os magnum) and the lesser multangular (trapezoid) bone, since interosseous ligaments are usually wanting in this situation. The thin articular capsule exhibits no special peculiarities and resembles that of the radiocarpal articulation. The articulation oj the pisijorm bone is a small unimportant joint between the contiguous surfaces of the pisiform and triquetral (cuneiform) bones, and is usually an independent articu- lation. As the pisiform bone is simply the sesamoid bone of the flexor carpi ulnaris, this joint is analogous to those situated between the sesamoid bones of the great toe and the head of the first metatarsal bone. The ligaments arising from the pisiform bone are similarly to be regarded as continuations of the tendon of the flexor carpi ulnaris; they are the piso-hamate ligament (Fig. 204), passing to the hamulus of the hamate (unciform) bone, and the piso-metacar pal ligament (Fig. 204), which passes to the base of the fifth metacarpal bone and sends prolonga- tions to the neighboring metacarpal bones. The carpo-metacarpal joint (Fig. 202) is the joint between the bases of the second to the fifth metacarpal bones and the distal articular facets of the lesser multangular (trapezoid), of a small portion of the greater multangular (trapezium) {see page g1), capitate (os magnum), and hamate (unciform) bones. The articular cavity, which is usually single, communicates, as a rule, with the intercarpal joint in the manner previously described. It is sometimes com- posed of two separate articulations, each of which connects two metacarpal bones. The bones forming the carpometacarpal articulation are capable of only slight movements and the articular capsule is correspondingly tense and firm. In addition to the previously men- tioned surfaces, it also embraces the lateral articular facets between the bases of the individual metacarpal bones (see page 91), and the articulation consequently includes the concealed inter- metacarpal articulations. The articulation is an arthrodium. ‘The carpo-metacarpal joint oj the thumb is the joint between the saddle-shaped articular facet at the distal extremity of the greater multangular bone (trapezium) and the base of the ‘metacarpal of the thumb. It is always an independent articulation, communicating with none of the other carpo-metacarpal joints nor with any of the carpal joints. From the shape of the articulating surfaces the articulation is a saddle joint, and although the surfaces are not com- pletely congruent, it is the most pronounced saddle joint in the human body. 126 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 203.—Articulations and ligaments of the hand seen from the dorsal surface (#). Fic. 204.—Articulations and ligaments of the hand seen from the volar surface, the transverse carpal ligament having been removed (#). Fic. 205.—Articulations of the middle finger seen from the side ($). In the movements of the hand the radiocarpal and intercarpal articulations act together as hinge joints. The four chief movements of the hand are flexion, extension, radial flexion (or, better, radial abduction), and ulnar flexion (or, better, ulnar abduction). By a combination of these movements it is possible to effect an almost complete circumduc- tion of the hand. The chief movements of the joints are flexion and extension. The axes of rotation of the two hinge joints are not ' placed at right angles to the axis of the forearm, but obliquely and intersecting each other.* During flexion of the radio- carpal articulation, the hand deviates to the radial side; during the similar movement in the intercarpal articulation the hand deviates to the ulnar side and vice vers@. If one joint is flexed and the other extended, the movements in the axis of the extremity neutralize each other, while the lateral movements (radial or ulnar abduction, as the case may be) are more pronounced. If both joints are flexed or extended together, the lateral movements neutralize each other and the movements in the axis of the extremity (flexion or extension) are more pronounced. The carpo-metacarpal articulations are arthrodia and are but slightly movable; this is particularly true of the carpo-metacarpal joints of the second and third fingers. "They move slightly when the concavity of the hand is increased or diminished, that is to say, during hollowing or flattening of the palm, and during opposition of the little finger. The range of motion of the carpo-metacarpal joint of the thumb is much more extensive. Like all saddle joints it is biaxial, but owing to the incongruity of the articulating surfaces, the curvatures of one of the surfaces being always more pronounced than those of the other, the movements about the two axes may be so combined that actual circum- duction is possible. The chief movements of this joint are abduction (away from the index-finger), adduction (toward the index-finger), and opposition (bringing the thumb opposite to the little finger). During the latter motion the con- cavity of the palm is markedly increased. THE CARPAL LIGAMENTS. The carpal ligaments (Figs. 203 and 204) are composed of the ligaments between the bones of the forearm and the carpal bones and of those which connect the carpal bones with each other and with the bases of the metacarpal bones. Of the first group, the ligaments which connect the ulna with the carpus are weak, while the radius is connected to the carpus by strong ligaments. It will be remembered that the carpal bones articulate with the radius only. The only ligament arising from the ulna is the wnar lateral ligament (Figs. 203 and 204), which passes from the styloid process of the ulna to the triquetral (cuneiform) bone. The corresponding ligament upon the radial side is the radial lateral ligament (Figs. 202 and 204) which passes from the styloid process of the radius to the navicular bone. The radius is con- nected to the carpus also by two strong ligaments which reinforce the dorsal and palmar sur- faces of the capsule. The dorsal radiocar pal ligament (Fig. 203) passes obliquely from the lower end of the radius to the dorsal surface of the first row of carpal bones and is attached particularly to the triquetral (cuneiform) bone. The corresponding anterior ligament, the volar radiocarpal ligament (Fig. 204), is longer than the dorsal one; it arises from the margin of the articular surface of the carpus - and is inserted not only into the bones of the first row, but also into the capitatum (os magnum). * This deScription of the movements of the hand has been materially modified by the more recent studies of these articulations. It must not be supposed that the two rows of carpal bones cannot move upon each other; during radial abduction the navicular bone is markedly moved toward the adjacent bones. rO0C OI / spusuivdy sADpNpdOD ISMIASUVA | spuauiody - - ‘ ‘ 4 ADIOA AMOS SIIIY souog plouvsas ‘€0% “S1Y “ WN woyopnotap poatuvjoyd -odavsvjaid ayy fo apnsdod avpnoypsy syuauivgy) [D4] 7 auog / plowvsas ‘COZ “G14 Sjuawmody yosvq s Dif 7 suauvsy Rd ge iy jos4od Jodavavjaut yuamnsy aca Made ba + dang opD 7 s0g spoiwoy ee quny) fo fo snjnuovpy avpnduvjynia UONVINIIAD ao" ddssa'] podivg unjojidp? - -pyauiodivy auog avjnis : ManyDy. juauvdy poduvgvjauoste] “UDI AIDIAD) juauosy aynsdod yy : ; au0q ADINIIADN po4ajo7] 4upnaipiy : WNJOUDEY a : JUIUIDS!) ; podivg ajyvipoy ~ Juauvgy ADULDY OST _ Juaunisy) yodsvs a -OJPDA JDSAO. JuausDs}) 210g wa4ofisty MInAOTOIAL Pie te pies vdiv2oipod 4vj0 vA4ajv] [DIPVS i Ipd4 AvjoA juauvdy jodavs jusuvdy poduvy OPE TEES. osvy ADuyy) =—- 1949} DUTT) Ae y auog uoNvpnIyaéw aa ee r; i oe splat ists. gM ary intyats : q ov - ae = aba see, } ‘ 7h ah a. | . eh ao Oe 5 as a | 7 & . THE JOINTS AND LIGAMENTS OF THE HAND. i27 ; The transverse carpal (anterior annular) ligament (Fig. 282) is a particularly strong ligament fx which serves more for the retention of the long flexor tendons in place (see page 205) than as fe an accessory ligament of the carpus. It connects the two carpal eminences, but is also attached “to the radius, and converts the carpal groove into a canal. Upon the floor of the carpal canal are found the ligaments which connect the individual carpal bones (Fig. 204); they radiate toward the head of the capitatum (os magnum), forming the radiate car pal ligament. The remaining carpal ligaments which unite the carpal bones or connect them with the bases of the metacarpal bones are designated according to their position as the volar and dorsal intercar pal ligaments, the volar and dorsal car po-metacar pal ligaments,* and the volar (three in number) and dorsal (four in number) basa? ligaments (Figs. 203 and 204). The interosseous basal ligaments are situated in the interspaces between the bases of the metacarpal bones. aii THE FINGER-JOINTS. q The metacar po-phalangeal articulations (Figs. 203 to 205) are the joints between the heads ) of the metacarpal bones and the bases of the proximal phalanges. Although the articulating surfaces are irregularly spherical, the movements of the joints are restricted by ligaments. The articular surfaces of the heads of the metacarpal bones become somewhat cylindrical upon the palmar aspect of the bones, so that the surfaces in contact during extension are spherical, while during flexion they are cylindrical. The joints are consequently a mixture of the ginglymoid and arthrodial types (ginglymo-arthrodia). The metacarpo-phalangeal joint of the thumb is an exception; it resembles the interphalangeal articulations and is a true ginglymoid joint. The articular capsules (Figs. 203 and 205) are thin and somewhat relaxed, but they are reinforced in several situations. Strong /ateral ligaments are excentrically inserted into the heads of the metacarpal bones, so that they become tense during flexion of the phalanges; they arise from small depressions upon the sides of the heads of the metacarpal bones (see page 92). The anterior surfaces of the capsules are reinforced by the accessory volar ligaments (Fig. 204), which are connected with the sheaths of the flexor tendons (see page 205), and by the éransverse capitular ligaments (Fig. 204), which are flat strong ligaments connecting the heads of the second to the fifth metacarpal bones. The dorsal surfaces of the capsules are protected by the dorsal aponeuroses of the fingers (see page 205), which are intimately connected with them. The metacar po-phalangeal joint oj the thumb always contains two sesamoid bones (a radial and an ulnar) (Fig. 204), which are embedded in the articular capsule; the surfaces directed - toward the articulation are covered by cartilage. Sesamoid bones occasionally occur in the metacarpo-phalangeal joints of the other fingers (see also page 92). eS eee The movements of the metacarpo-phalangeal joints of the four fingers consist of hinge movements by which the phalanges are flexed and extended. During flexion, the lateral ligaments are tense, and prevent any lateral motion. During extension, however, these ligaments become relaxed and the spherical articular surfaces are in contact, so that ioe 228 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 206.—The female pelvis with its ligaments, seen from behind (2). Fic. 207.—The female pelvis with its ligaments, seen from below (2). Fic. 208.—The male pelvis with its ligaments, seen from in front (2). Fic. 209.—The female pelvis with its ligaments, seen from in front (2). Fic. 210.—The male pelvis with its ligaments, seen from above (2). Fic. 211.—The female pelvis with its ligaments, seen from above (2). while extensive rotation is impossible, the phalanges and consequently the fingers can be abducted and adducted. The metacarpo-phalangeal articulation of the thumb is a pure hinge joint. The digital or interphalangeal articulations (Fig. 205) are the joints between the individual phalanges of the fingers, the bases forming the articular sockets and the trochlear surfaces con- stituting the articular heads. The articulations are pure hinge joints. Lateral ligaments (Fig. 205) at the sides of the capsules prevent any lateral motion, and the articular capsules are roomy. Volar flexion is the only movement of which these joints are capable. THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. THE PELVIC LIGAMENTS, SYNARTHROSES AND DIARTHROSES. The pelvic girdle and its ligaments form the pelvis (Figs. 206 to 211 and 215), which, unlike the shoulder girdle, is complete both anteriorly and posteriorly, the pubic bones being connected anteriorly by a symphysis and the pelvic girdle completed posteriorly by the sacrum, which articulates with the two iliac bones either by joints or half joints. The symphysis pubis (Figs. 208 and 209) is a mixed synarthrosis connecting the symphysial surfaces of the two pubic, bones. These surfaces are covered with cartilage and the space between them is filled by a mass, consisting largely of dense connective tissue and partly of fibro- cartilage, which is termed the inter pubic fibrocartilage. This interpubic tissue is broader in front than behind and its posterior portion frequently contains a space resembling an articular cavity, so that the symphysis is converted into a half joint (amphiarthrosis). The symphysis is reinforced by fibers which pass across its upper margin from the pubic spine of one side to that of the other; these fibers are intimately connected with the interpubic fibrocartilage and form the superior pubic ligament (Fig. 210). The lower margin of the sym- physis is reinforced by a more independent structure, the arcuate (injerior pubic) ligament (Figs. 206 and 208), which is approximately triangular and rounds off the pubic angle. The posterior connection of the pelvic girdle is a paired articulation which is termed the sacroiliac articulation. It occurs between the auricular surface of the sacrum and the:similarly named surface of the ilium, and is an almost immovable joint, a true amphiarthrosis. The rough irregular surfaces of the two bones are scarcely adapted for reciprocal movements, and the strong ligaments surrounding the articulation further insure its immobility. In addition to being connected by the auricular surfaces, the innominate bone and the sacrum are also held together by a strong ligament passing between the tuberosities of the two Short post. sacro-iliac. lig, Supra- spinous (@ i 'Z {liolumbar ligament ew g* Short posterior sacro-iliac lig Long post. sacro-tliaclig Sacro-spinous ligament Articular capsule of hip joint if \( a J Great tro- A chanter === gl \ Symphysis < : Superf. post. pubis is. of sacrococe. lig. Arcuate ligament . Falciform Deep post. Ps ' ? Process Sacrococe. lig. . hae Sacro-tuberous ligament ate ° Fig. 200. Median sacral crest Post superior spine of ilium Great sciatic foramen Lesser sacro-spinous ligament Lesser sciatic foramen /£ Great tro- chanter Superficial posterior tuberous SQCcro-coccy- . geal lig. ligament Fig. 207. Tuberosity o ischium Falciform process Inguinal ligami Articular capsule 4 PES Arcuate iP ae ligament Pes met A oP ar > 90 OR) EA aad wy Parner ay +) Pages Vey ‘ ” ' = ‘ Lumbar vertebra IV - Anterior longitudinal ligament Anterior sacro-iliac lig, Miolumbar lig. Anterior superior ; 1p Inguinal lig. spine of tlium ot & Articular capsule of hip joint lliofemoral lig. Great trochanter ‘g Arcuate ligament _Interpubic Obturator Superior lbrocartilage membrane pubic lig. Ma Pubic angle = Fig. 209. Lumbar vertebra 1V ) Iliolumbar lig. Anterior sacro- iliac lig. Great Ssctatic foramen Lesser S ciatic \ Joramen Lat. sacro- \ ; coce. lig. Ant. SQCTOCOCC. lig. Terminal line Iliofemoral lig. Inguinal lig. Supenor pubic lig. Fig. 210. Lacunar ligament Fig. 211. “A TO RAR ep and oy 4 OSes ten | . .7 = THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. 129 , bones, the interosseous sacroiliac ligament (Fig. 215). Since this ligament completely fills the space between the tuberosities of the ilium and the sacrum, it may be said that these two bones are connected anteriorly by an amphiarthrosis and posteriorly by a syndesmosis, but from the physiological standpoint, the syndesmosis is the most important part of the articulation, since it firmly unites the pelvic bone to the sacrum which bears the weight of the entire trunk. The sacrum and ilium are also connected by the following ligaments: the anterior sacro- iliac ligaments (Figs. 208, 210, and 215), which pass as flat bands, composed of transverse, oblique, and frequently interlacing fibers, from the anterior surface of the sacrum in front of the iliosacral joint to the anterior surface of the ilium, and particularly to the linea terminalis; the posterior sacroiliac ligaments (Figs. 206 and 215), of which there are to be distinguished a long and a short ligament. The short posterior sacroiliac ligament consists of a number of’ fibers which pass obliquely from the lateral ridges of the sacrum to the iliac crest in the region of the posterior inferior spine. The long posterior sacroiliac ligament is composed of superficial longitudinal fasciculi which run from the posterior superior spine of the ilium to the lateral portion of the dorsal surface of the sacrum and intermingle in this situation with the origin of the sacrotuberous (great sacrosciatic) ligament. It covers in the corresponding short ligament posteriorly. The iliac bone is also connected to the fifth lumbar vertebra by the iliolumbar ligament (Figs. 206 and 208). This is a strong ligament which passes from the transverse process of the fifth lumbar vertebra to the iliac crest, and is frequently connected with the uppermost fibers of the anterior sacroiliac ligament. Through it the last lumbar vertebra and also the last inter- vertebral fibrocartilage are included in the pelvis, and are connected not only with the ilium but also with the sacrum. THE INDEPENDENT LIGAMENTS OF THE PELVIS. In addition to the ligaments which directly connect the individual parts of the pelvic girdle, there is another series of ligaments which belong to that class of ligaments which take the place of bones (see page 108). These are: (1) The obturator membrane; (2) the sacrotuberous (great sacrosciatic) ligament; and (3) the sacros pinous (lesser sacrosciatic) ligament. The obturator membrane (Figs. 208 and 216) is a rather thin membrane which closes in the obturator foramen with the exception of the upper portion, in which is situated the prolongation of the obturator groove, the opening, the obturator canal (Fig. 216), which this forms giving passage to the obturator vessels. The sacrotuberous (great sacrosciatic) ligament (Figs. 206, 207, 210, and 211) has a broad origin from the lateral portion of the entire posterior surface of the sacrum, from the posterior portion of the iliac crest in the region of the posterior superior and inferior spines (where it is connected with the posterior sacroiliac ligaments), and from the posterior surface of the coccyx. It becomes narrower as it passes downward, but again broadens out near its insertion into the tuberosity of the ischium. It covers the sacrospinous ligament posteriorly, and the two ligaments are adherent at their intersection. The jalcijorm process (Figs. 206 and 207) isa narrow oblique continuation of the sacrotuberous ligament, which passes along the lower margin of the ischium and pubis and gradually disappears anteriorly. [30 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The sacros pinous (lesser sacrosciatic) ligament (Figs. 206, 207, 210, and 211) is more deeply situated than the sacrotuberous ligament, and arises from the lateral margins of the lower portion of the sacrum and of the upper portion of the coccyx. It rapidly becomes narrower and passes almost horizontally forward and outward, crossing the sacrotuberous ligament shortly before reaching its insertion at the tip of the spine of the ischium. Its pelvic surface covers and is adherent to the coccygeus muscle (see Splanchnology). The sacrospinous ligament converts the greater sciatic notch into an elliptical foramen which is termed the great sciatic (sacrosciatic) joramen, and the two ligaments, the sacrospinous and the sacrotuberous, convert the lesser sciatic notch into a foramen, the lesser sciatic (sacrosciatic) joramen. ‘This latter foramen is triangular with rounded angles and is separated from the great sciatic foramen by the sacrospinous ligament. The sacrotuberous ligament forms a portion of the outlet of the pelvis. THE PELVIS AS A WHOLE. The following bones enter into the formation of the pelvis: the two innominate bones, the sacrum, the coccyx, and the fifth lumbar vertebra; and its boundaries are also partly formed by the interpubic fibrocartilage, the obturator membrane, and the sacrotuberous and sacrospinous ligaments. The iliolumbar ligament forms a portion of the pelvic wall. In the pelvis may be recognized the jalse or greater pelvis, and the true or lesser pelvis. The former forms the floor of the abdominal cavity, and is wide open above and in front and is bounded only partly by bone. Its cavity is considerably larger than that of the true pelvis, from which it is separated by the terminal (iliopectineal) line (Fig. 210). It is bounded by the ale of the ilium, by the fifth lumbar vertebra together with the promontory, and by the two iliolumbar liga- ments. The true or lesser pelvis is a short canal, the greater portion of whose boundaries are bony. The anterior wall is short while the posterior one is considerably longer, and it is open above and below. The upper opening is termed the superior aperture of the pelvis or the pelvic inlet (Figs. 210 and 211), whose boundary is formed by the terminal line, by the promontory, and by the upper margin of the interpubic fibrocartilage. The terminal line is composed of a sacral, an iliac (the arcuate line), and a pubic (crest of the pubis) portion. The actual cavity oj the pelvis is bounded posteriorly by the concave pelvic suriace of the sacrum and by the anterior surface of the coccyx; laterally by the pelvic surfaces of the bodies of the ilium, pubis, and ischium (the floor of the acetabulum), by the sacrotuberous and sacro- spinous ligaments, by the rami of the pubis and ischium, and by the obturator membranes; and anteriorly by the symphysis pubis with its ligaments and by the anterior extremities of the two pubic bones. The anterior wall of the pelvic cavity is by far the shortest, while the posterior wall is the longest. The posterior portions of the lateral walls exhibit two openings, the upper elliptical greater sciatic‘foramen and the lower triangular lesser sciatic foramen; the anterior portions contain the openings in the obturator membranes which form the obturator canals (see page 129). The upper more capacious portion of the pelvic cavity is designated as the plane of pelvic expansion, while the inferior contracted portion is known as the plane oj pelvic contraction. THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. 13! The injerior aperture oj the pelvis or pelvic outlet (Fig. 207) is bounded by the lower margin of the symphysis (arcuate ligament), by the tuberosities of the ischium, by the inferior rami of the ischium and pubis, by the sacrotuberous ligaments, and by the tip and the lateral margins of the sacrum. These boundaries, unlike those of the pelvic inlet, do not lie in the same plane. The coccyx forms the lowermost point of the pelvic outlet, and next come the tuberosities of the ischia, which project downward, while the boundary curves markedly upward in the region of the sacro- tuberous ligaments and particularly at the lower margin of the symphysis. The angle which the two inferior rami of the pubis form with the symphysis is known as the pubic angle (Fig. 209). It is rounded off by the arcuate ligament to form the pubic arch, The pelvis is not horizontal but inclined, the degree of its inclination varying in different individuals, but usually averaging about 60 degrees. The plane of the pelvic inlet consequently passes obliquely from above downward and from behind. The pelvis exhibits, as does no other portion of the skeleton, typical sexual characteristics. This is particularly noticeable in the true pelvis. In the female the false pelvis is lower, broader, and flatter, and the al of the ilium usually show a less marked curvature. The true pelvis exhibits similar characteristics, and its cavity in particular is more capacious. In the male the pelvic inlet is heart-shaped (from the marked projection of the promontory), while in the female it is elliptical, and the pelvic outlet in the male is also much narrower than in the female on account of the convergence of the tuberosities of the ischia. The pubic angle in the male pelvis forms an acute angle of about 75 degrees, while in the female it forms a right or obtuse angle (go to 100 degrees). For a more detailed account of the pelvic diameters and of the pelvis in its relations to obstetrics the reader is referred to the text-books and atlases of topographic anatomy. The inguinal or Pou part’s ligament (Figs. 207 and 209) is not one of the actual ligaments of the pelvis, but is a portion of the aponeurosis of the external oblique muscle of the abdomen. It arises from the anterior superior spine of the ilium and is inserted into the spine of the pubis. An almost horizontal continuation of the ligament passes from its insertion to the upper margin of the horizontal ramus of the pubis, forming the /acunar (Gimbernat’s) /igament (Fig. 211). THE HIP-JOINT. The hip-joint or coxal joint is the articulation between the acetabulum of the innominate bone and the head of the femur. The acetabular cavity is considerably deepened by a strong circular fibrocartilaginous ligament, the glenoidal lip (cotyloid ligament) (Fig. 216), so that the socket embraces more than half of the spherical head of the femur, and the joint consequently belongs to that group of the spheroidal articulations which is known as an enarthrosis. The glenoidal lip (Fig. 214) of the hip-joint is triangular in cross-section and stretches across the notch of the acetabulum, converting it into a cleft-like foramen. This portion of the gle- noidal lip is known as the éransverse ligament (Fig. 214). The acetabular fossa (Fig. 214) does not come into direct contact with the cartilaginous surface of the head of the femur and is not covered with cartilage, but by a cushion of fat and by synovial villi. From this fatty cushion, and particularly from the acetabular notch, there arises 132 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 212.—The right hip-joint seen from in front (4). Fic. 213.—The right hip-joint seen from behind (@). Fic. 214.—Socket of the right hip-joint after cutting through the articular capsule and the round ligament. The head of the femur has been removed (#). Fic. 215.—Section through the pelvis and the two hip-joints taken in a plane almost at right angles to the axis of the pelvis (#). Fic. 216.—The right hip-joint opened through the anterior wall of the articular capsule so as to show the round ligament. The head of the femur has been drawn out of the socket and rotated outward and backward (#). a broad characteristic ligament of the hip-joint, the round ligament (ligamentum teres) (Figs. 214 and 216), which becomes slightly narrower and is inserted into the depression on the head of the femur. This ligament is flat, and only its external portion is formed of firm connective-tissue fasciculi; in its interior nutrient vessels pass to the head of the femur. It lies in folds upon the cushion of fat in the acetabular fossa, and on account of its length and soft structure plays little part in checking the movements of the joint. The strong articular capsule of the hip-joint (Figs. 212, 213, and 215) is markedly reinforced by accessory ligaments. It arises from the outer circumference of the glenoidal lip and embraces not only the head of the femur but also the greater portion of its neck. Anteriorly it is inserted into the intertrochanteric line; posteriorly it does not extend so far, and surrounds only somewhat more than the half of this portion of the rieck of the femur. The reinforcing ‘ligaments are firmly adherent to the capsule of the hip-joint and are com- posed of longitudinal and of circular fibers. The latter are known as the orbicular ligament (zona orbicularis) (Fig. 215) and embrace the narrowest portion of the femoral neck; they pursue a circular course within the innermost fibrous layers of the capsular ligament and are rather inti- mately connected with the longitudinal ligaments. The longitudinal fasciculi receive different names according to their places of origin, and since each of the three parts of the innominate bone gives origin to one of the fasciculi, they are consequently known as the iliofemoral, pubo- capsular, and 1schiocapsular ligaments. The iliofemoral ligament (Figs. 212 and 216) is the strongest of the three ligaments and is one of the thickest ligaments in the body. It arises in the region of the anterior inferior spine of the ilium, passes obliquely across the anterior surface of the articular capsule, broadening as it goes, and is inserted into the entire length of the intertrochanteric line. The pubocapsular liga- ment (Figs. 212 and 216) arises from the horizontal ramus of the pubis and passes across the inner and posterior portion of the articular capsule toward the lesser trochanter. The ischiocapsular liga- ment (Figs. 215 and 218) arises from the body of the ischium and runs in the posterior portion of the capsular ligament; the majority of its fibers pass into the zona orbicularis, but some of them converge upward to the great trochanter. The thinnest places in the capsule of the hip-joint are situated in its lower portion between the pubocapsular and the ischiocapsular ligaments, and above the zona orbicularis between the ischiocapsular and iliofemoral ligaments. There is also a thin place in the antero-internal wall of the capsule between the iliofemoral and pubocapsular ligaments, and a communication occasion- Pubocapsular ligament Tendon of rectus femoris liofemoras | ligament | Great trochanter y/ A ‘Lesser ' F ; trochanter ion : . Tendon *hiocapsular Tendon of rectus femoris Sacrotuberous lliofemoral trochant ligament X ‘ ° : : — Fossa of acetabulum Glenoidal _ lip ’ , ; wit a py Round ligament > Gluteai tuberosity Uae Heue sated . Facies lunata Articular capsule X Fig. 214. Transverse ligament of acetabulum Posterior sacro-iliac lig. Sacral canal f wr Sacrospinous ligament! Sacrotubcrous lig Synovial cavity... F« ‘Ss Orbicular ligament sacrococe. lig. hg =4 este LEN POC AEAS é ¢ Obturator membrane Arcuate lig. of pubis Artucular capsut Interpubic fibrocartilage Round Ug. Fig. 215. Iliofenural ligament X Glenoidal Round Pubo- lip lig capsular Obturator ig lig canal igi Obturator gicmbrane yy Head of 3 ' femur [schio- capsular te | oF Cane ,/ q a 4, f fo i “S° Lesser trochanter THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. 133 ally exists at this point between the synovial cavity of the hip and the iliopectineal bursa which is situated beneath the iliopsoas muscle (see page 211). The hip-joint is a ball-and-socket joint, and although the socket embraces more than one-half of the spherical head of the femur and limits the range of motion to a slight extent, movements in all directions are possible. Since the head of the femur forms a marked angle with the axis of the bone, the axis of movement of the joint does not pass through, but forms an acute angle with, that of the femur. The chief movements of the hip-jaint are abduction and adduction (separation and approximation of the lower extremities), flexion (anteriorly) and extension (dorsal flexion is impossible on account of the tension of the iliofemoral ligament), rotation, and circumduction. When the joint is half flexed (the “middle” position) all of the ligaments are relaxed. In the upright position the iliofemoral ligaments are tense and steady the pelvis upon the femora. The round ligament has no mechanical function whatever, but acts simply as a ligament of conduction (see page 108). It is occasionally wanting in man and regularly absent in many animals, and is to be regarded as an originally extra-articular structure, probably a portion of the pectineus muscle, which has been displaced into the joint. The head of the femur is held in its socket not only by the strong capsular ligaments but also by atmospheric pressure. THE KNEE-JOINT. The knee-joint (Figs. 217 to 222) is the articulation between the condyles (and the articular surface for the patella) of the femur and the condyles of the tibia, and the posterior surface of the patella is also passively involved in the formation of the articulation. Disregarding the patella, it will be noticed that, in contrast to the elbow, only two bones are included in the articulation, as the fibula is completely excluded from it. From the form of its articular surfaces as well as on account of the manifold character of its structures, the knee-joint is one of the most complicated articulations of the human body. The articulating surfaces are incongruent, since the concavities of the condyles of the tibia are less than the convexities of the condyles of the femur. The jemoral condyles are separated by the deep intercondylar fossa, and their posterior portions are spherical while their anterior surfaces are cylindrical and unite in front of the intercondyloid fossa to form the articular surface for the patella (Fig. 220). Ordinarily the condyles of the femur present their cylindrical surfaces to the tibia and the articulation is consequently a hinge-joint, the intercondyloid eminence of the tibia being received into the intercondyloid notch of the femur and preventing lateral displace- ment of the articulating surfaces. The most posterior portions of the femoral condyles, however, are spherical, and when they rest upon the condyles of the tibia, during flexion of the knee- joint, they form a double arthrodial joint. From the shape of its articulating surfaces the knee-joint is consequently a ginglymo-arthrodial articulation. Upon the condyle of the tibia are situated two menisci, which from their position are termed the infernal and the external meniscus (Fig. 221). They are but loosely connected with the con- dyles of the tibia and are attached only to the capsular ligament and to the intercondyloid eminence, so that they may be moved upon the surfaces of the tibial condyles. Their external margins are thick, their internal margins thin, and their cross-sections are decidedly wedge- shaped. - The inéernal meniscus (the internal semilunar cartilage) is narrower than the external one and does not form a complete semicircle, but is a segment of a circle whose radius is larger than that of the external meniscus. The external meniscus (the external semilunar cartilage) is almost _ completely circular and is open only at its point of attachment to the intercondyloid eminence. 134 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 217.—The right knee-joint in extension seen from in front (4). Fic. 218.—The right knee-joint in extension seen from behind (%). ae Fic. 219.—The right knee-joint in extension opened by two lateral incisions. The quadriceps ae py together with the patella, has been reflected downward (%). . Fic. 220.—The right knee-joint in flexion after removal of the articular capsule and the nical ligaments (4). ae ane “ It is broader than the internal meniscus, and, as its radius is smaller, it covers the condyle of the | tibia except in the situation of its relatively small median hiatus. It arises in the anteriorintercon- - dyloid fossa of the tibia and runs to the external intercondyloid tubercle, while the internal meniscus _ passes from the anterior margin of the articular surface of the internal condyle to the posterior — intercondyloid fossa. ‘The anterior portions of both menisci are connected by fasciculi which vary _ greatly in their development and are known as the éransverse ligament, and their thick external — i margins are adherent to the articular capsule, the external meniscus being less intimately adherent, — ; and hence more movable than the internal one. In addition to the menisci, the articular cavity also contains two important accessory liga- ments, the crucial ligaments (Figs. 220 and 221), of which there are two, an anterior and a posterior. Their anterior surfaces are provided with a synovial covering which passes asa septum through — the posterior portion of the articulation, and they are strong ligaments firmly connecting the tibia with the femur. They both arise from the intercondyloid fossa of the femur and pass to the 3m tubercles and intercondyloid fossz of the tibia. The anterior ligament has a broad origin on the | "7 inner surface of the external condyle of the femur, and, becoming narrower, it passes to the anterior = a c intercondyloid fossa and to the anterior intercondyloid tubercle of the tibia. The posterior liga- ment passes from the outer surface of the internal condyle of the femur to the posterior intercon- ae dyloid fossa and to the corresponding tubercle of the tibia; it is flat at its origin but rounded at its insertion, and is usually stronger than the anterior ligament. During rest (semiflexion), the two — ligaments cross in such a way that the anterior one is in front of the posterior. The latter is usu- ally connected with the external meniscus. r With the exception of certain diverticula of the synovial membrane, which will subsequently be described, the articular capsule is attached to the margins of the cartilaginous articular surface: Its line of attachment upon the posterior surface of the femur is indicated by the intercondyle line, so that the entire intercondyloid fossa is situated within the articular cavity. The knee-joint possesses a number of peculiarities: its synovial folds are more eer than those of any other joint in the body; its synovial membrane gives off divertialil some of which are of large size and pass beneath the neighboring muscles; it is much strengthened by the majority of the overlying tendons; and the patella is embedded in the anterior portion | om le articular capsule and forms the immediate anterior boundary of the articular cavity. ; The majority of the reinforcing ligaments of the knee-joint are adherent to the capsule th “a out the greater portion of their extent. There are two lateral ligaments, the jibular and the didi lateral ligament. The tibial (internal) lateral ligament (Fi igs. 217 and 218) arises from the intert epicondyle and is intimately adherent to the capsular ligament; its superficial fibers run tot =o a A ad Femur Internal tntermuscular septum ‘rf (Tendon of adductor magnus) Articalar capsule Tendon of gastrocnemius (int. head) Tendon o f frocnicml t he 2 Articular muse. Obligue of knee pe Suprapatellar ~ Fibulae bursa “ Tendon of Poplite quadriceps -..Quadriceps Tendon of semi- membranosus Poster capu oy ier Tibial lateral “e" / ligament Patella i ge ; \ hi LAI | | Tibia Ext. retina- | sf | culunc-F ‘im! %, | aed | Int, retinacul Fie. 218 patella in A po ig. 218. Fibular Ns : lateral _ lig. Deep in- Polar ; Tibial lateral ligament bursa Patellar ligament Head of- Sibula Tibia Articular surface for patella Patellar fold of synovial membrane Internal condyle Alar folds f Articular capsule * Fibular lateral lig. , External condyle Patella Patellar surface Articular capsule x Posterior cru- cial ligament Internal condyle Exter- nal condyle Internal wieniscus External meniscus Suprapatellar | bursa Anterior crucial Fig. 219, ligament Anterior capitular lig. Transverse ligament Fig. 220. Fibula Tuberosity of tibia _— THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. 135 inner margin of the condyle of the tibia, while the shorter deep fibers pursue a somewhat oblique course and pass posteriorly to be inserted into the internal meniscus and into the infraglenoidal margin of the internal condyle. The main portion of the fibular (external) lateral ligament (Figs. 217, 218, and 219) is separated from the capsular ligament by fatty tissue, and consequently appears as a firm, indepen- dent, flattened cord which passes from the external condyle of the femur to the head of the fibula. A deeper and shorter portion of the ligament (the short external lateral ligament) is adherent to the capsule. The posterior wall of the capsule is reinforced by two ligaments which are intimately con- nected with the muscles which have their insertion in the vicinity of the knee-joint. The oblique popliteal ligament (Fig. 218) is a continuation of the tendon of the semimembranosus muscle and runs obliquely from below upward and from within outward upon the posterior surface of the capsular ligament, in which structure it finally disappears. The arcuate popliteal ligament (Fig. 218) passes in a curved manner above the tendon of the popliteus muscle, the concavity of the curve being directed upward. It runs from the region of the external condyle of the femur to the posterior wall of the capsule of the knee-joint, some of its fibers passing also to the head of the fibula and to the deeper fasciculi of the fibular lateral ligament, these fibers being termed the retinaculum oj the arcuate ligament. The anterior wall of the knee-joint is formed almost entirely by the tendon of the quadriceps cruris muscle and its continuations. The tendon of this muscle is really inserted into the base of the patella, but it is continued onward as the flat but very strong patellar ligament (Figs. 217 and 222) which passes from the tip of the patella to the tuberosity of the tibia. The patellar ligament, however, is independent of the knee-joint and is not adherent to the capsular ligament; it is one of the thickest ligaments of the body, and it is separated from the upper end of the tibia and from : the capsular ligament by fatty tissue and by a constant bursa, the deep injra patellar bursa (Fig. 222), which does not communicate with the synovial cavity. Both the patella and the actual tendon of the quadriceps, however, directly form a portion of the anterior boundary of the joint, and the anterior portion of the capsular ligament is also reinforced by lateral fibrous continuations of the quadriceps, which are known as the infernal and external patellar relinacula (Fig. 217). They arise from the lateral margins of the patella, receive fibers from the vasti upon cither side (see page 215), and pass downward to the lateral margins of the condyles of the tibia. ‘ The synovial folds of the knee-joint are the alar jolds (Figs. 219 and 222) and the patellar synovial fold (Fig. 221). The greater portion of the alar folds consist of the fatty tissue which is situated behind the patellar ligament, and is covered by the synovial membrane; they project into the knee-joint from either side of the patella. The patellar synovial jold is a fibrous band of variable size which usually contains a considerable quantity of fat; it arises from the anterior wall of the capsule between the two alar folds, with which it is connected, and is inserted into the intercondyloid fossa of the femur. The largest diverticulum of the synovial membrane of the joint is the suprapatellar bursa (Fig. 222), which extends upward beneath the tendon of the quadriceps femoris for almost a hand’s breadth. It always communicates with the synovial cavity, usually by quite a large re, and receives the insertion of those fibers of the quadriceps which are termed the articular Ti 36 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 221.—The condyles of the tibia with the two menisci and the origins of the crucial ligaments (3). Fic. 222.—Sagittal section of the right knee-joint in extension. The section passes through the external condyle of the tibia (#). Fic. 223.—The right tibia and fibula with their ligaments (4). muscle of the knee (subcrureus) (see page 215). The suprapatellar bursa does not lie directly upon the anterior surface of the femur, but is separated from it by a cushion of fat. There are two or three other considerably smaller diverticula of the synovial membrane at the posterior portion of the articulation. These are the popliteal bursa, beneath the tendon of the popliteus, the semimembranous bursa, beneath the tendon of the semimembranosus, and the internal gastrocnemial bursa (Fig. 304), beneath the tendon of the inner head of the gastrocnemius. The last two bursee may communicate. There are other bursz in the neighborhood of the knee-joint which have no direct relation to the articulation. In addition to the previously mentioned deep infrapatellar bursa, these are: the subcutaneous prepatellar bursa (Fig. 222), a subcutaneous bursa which is constantly found in front of the patella; the subfascial prepatellar bursa, between the fascia and the tendon of the quadriceps; the swbtendinous prepatellar bursa, between the quadriceps tendon and the periosteum of the patella; and the subcutaneous infrapatellar bursa, which is situated in front of the patellar ligament (see also page 234). As might be supposed from the shape of the articulating surfaces, there are two kinds of motion possible in the knee- joint, a hinge motion (flexion of the leg and the return to the extended position) and a movement of rotation which is possible only when the knee is flexed. Rotation is impossible when the knee is extended, not only from the shape of the articulating surfaces (see page 133), but especially on account of the tension of the lateral ligaments, which are relaxed only during flexion of the joint. The lateral ligaments also prevent a lateral displacement of the bones during flexion of the articulation. The crucial ligaments serve mainly to hold the femur and tibia together; they are so situated that one of them is always tense in any position of the joint, the posterior ligament being tense during part of the move- ment of flexion and part of the movement of extension, and the anterior one during the whole of flexion. The crucial ligaments also check the movement of rotation. . The patella glides upon the surface of the femur, and has no influence upon the mechanism of the articulation. During extension of the joint it is pulled upward by muscular action and during flexion it descends toward the tibia. The function of the menisci is rather to form an articular cushion than to supplement and deepen the articular socket. In some positions of the joint they act both as cushions and as portions of the articular socket, in other positions they act only as cushions, and in still others they exert no influence whatever upon the mechanism of the joint. During some of the movements of the articulation they are markedly displaced or strongly compressed. THE ARTICULATIONS OF THE TIBIA AND FIBULA. The tibia and fibula are connected with each other in three ways: their upper extremities articulate by means of a small joint, the ‘biofibular articulation; the bodies of the bones are connected by the interosseous membrane; and the lower extremities are united by tense ligaments, forming the ¢ibiofibular syndesmosis. The tibiofibular articulation (Figs. 217, 218, 220, and 223) is the joint between the fibular articular surface of the tibia and the capitular articular surface of the fibula. It is an arthrodium with almost plane articular surfaces and possesses strong accessory ligaments, which reinforce the capsule anjeriorly and posteriorly and are known as the anterior and posterior capitular liga- ments (Figs. 218, 220, and 223). The tense capsular ligament snugly embraces the cartilaginous surfaces. This articulation may occasionally communicate with the knee-joint (through the popliteal bursa). Transverse ligament Anterior crucial Deep infrapatellar bursa lig. Patellar lig. Anterior capitular ligament Internal meniscus External meniscus Tuberosity of tibia Posterior crucial lig. Fig. 221. Tendon of Interosscous : quadriceps membrane Biceps ’ ' JSemoris Supra- / patellar i bursa \ Articular : ' surface Pe “\~\ of patella -—- ¢ eile Gastro- Par ¥ AN cnemius ft Patella (ext. head) Subcutancous prepatcliar External bursa condyle of femur ta ular folds External Patellar meniscus ligament External meniscus Deep infra- patellar bursa Anterior lig. of external malleolus Fig, 222. Fig. 223. ? ; \ K ¢ { ° G ’ - 7 F ‘ ‘ ; = * - ” * J i hy ay ‘ - en es | THE JOINTS AND LIGAMENTS OF THE FOOT. 137 The inlerosseous membrane (Fig. 223) resembles the interosseous membrane of the forearm very closely and extends between the interosseous ridges of the two bones. It consists chiefly of oblique fibers, the majority of which run downward from the tibia to the fibula, although some pursue a course at right angles to this direction. Its upper portion contains a large foramen for the passage of blood-vessels. The tibiofibular syndesmosis (Figs. 223, 224, and 226) is situated between the fibular notch of the tibia, which is not covered by cartilage, and the internal surface of the external malleolus. It is formed by two ligaments, rich in elastic fibers, the anterior and posterior liga- ments of the external malleolus (tibiofibular ligaments) (Figs. 225 and 226), which are situated upon the anterior and posterior surfaces of the lower end of the two bones. They pass obliquely downward from the tibia to the fibula and are made tense when the broader portion of the superior articular surface of the talus (astragalus) enters into the articular socket of the ankle-joint. The lower ends of the tibia and fibula may consequently be passively separated for a certain distance; this is, however, practically the only movement between the tibia and fibula. THE JOINTS AND LIGAMENTS OF THE FOOT. The joints and ligaments of the foot will be considered separately, since many of the ligaments of the foot belong to several joints. THE JOINTS OF THE FOOT. The joints between the talus (astragalus) and the bones of the leg and those between the indi- vidual bones of the foot may be divided into the following groups: 1. The Articulations of the Talus (Astragalus), which include the talocrural articulation (the ankle-joint), the falocalcaneal articulation, the talocalcaneo-navicular articulation, and the calcaneocuboid articulation, 2. The Tarsal Arthrodia. (a) The intertarsal articulations (the cuneonavicular articulation). (6) The tarsometatarsal joints (the /arsometatarsal and intermetatarsal articulations). (3) The Joints oj the Toes (the metatarsophalangeal and digital (interphalangeal) articula- tions). The ankle-joint or ¢éalocrural articulation (Figs. 224 and 226) is the joint between the astraga- lus and the two bones of the leg. The articulating surfaces are the trochlea of the talus upon the one hand, and the inferior articular surface of the tibia and the articular surfaces of the internal and external malleoli upon the other. The articular capsule, which surrounds the cartilaginous surfaces and is inserted toward the neck of the astragalus, is thin; its anterior and especially its lateral portions are rather tense, while the posterior portion is roomy and relaxed. From its function and in accordance with the form of the articular surfaces, the talocrural articulation is a hinge joint, the socket of which, however, is formed by two bones. As the syndesmosis connecting the tibia and the fibula does not absolutely preclude motion, the broad anterior portion of the trochlea of the talus can be accommodated by a 138 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 224.—The ankle-joint seen from behind (#). Fic. 225.—Horizontal frozen section through the tarsal articulations (3). - Fic. 226.—Frontal frozen section through the ankle and posterior talocalcaneal Jor (4). slight separation of the bones of the leg; and when the foot is depressed, the narrow posterior portion of the trochlea has so much room in the articular socket that slight lateral movements are possible in the axis of the fibula. The ankle- joint is consequently not a pure hinge joint, although it acts mainly as such; its movements are those of plantar and dorsal flexion. The /alocalcaneal articulation (Figs. 225 and 226) is the joint between the convex posterior articular surface of the calcaneus and the concave posterior calcaneal articular surface of the talus (astragalus). The articulating facets are portions of the surface of a cone, the axis of which is almost sagittal, but directed somewhat obliquely upward and forward. The articular capsule is roomy and relaxed. This articulation occasionally communicates with the ankle-joint. The ¢alocalcaneo-navicular articulation (Figs. 225 and 230) is the joint formed by the head of the (talus) astragalus, the anterior and middle articular facets of the calcaneus, the posterior articular facet of the navicular, and the navicular fibrocartilage of the plantar calcaneonavicular ligament (see page 141). The joint is a pronouncedly compound articulation, and includes an anterior talocalcaneal and a talonavicular articulation. The socket for the head of the talus (astrag- alus) is formed by four different cartilage-covered surfaces. The articulation is separated from the posterior calcaneo-astragaloid joint by the sinus of the tarsus and its articular capsule exhibits no special peculiarities. The calcaneocuboid articulation (Fig. 225) is the joint between the cuboid articular surface of the calcaneus and the posterior articular surface of the cuboid bone. The surfaces are approxi- mately saddle-shaped. ‘Together with the talonavicular joint, it forms the transverse articulation of the tarsus (Chopart’s joint). From a functional standpoint the talocalcaneo-navicular joint is composed of two portions. The first of these is the joint between the talus (astragalus) and the navicular bone, which acts together with the calcaneo-cuboid articula- tion. It is an ellipsoidal joint, while the talonavicular articulation is a saddle-joint. Although these joints are biaxial, they check each other reciprocally, so that during motion each joint loses one of its axes of movement and a common uniaxial hinge joint results, the transverse tarsal joint. The remaining portion of the talocalcaneo-navicular joint acts ~ together with the talocalcaneal joint, whose axis coincides with that of the transverse tarsal joint. Both joints, or rather both combinations of joints, always work together; during adduction there is also an elevation of the inner margin of the sole of the foot (supination), and during abduction there is a simultaneous elevation of the outer margin of the sole of the foot (pronation). The anatomical and physiological associations of the joints are altogether different, as is also the case at the elbow and at the inferior radio-ulnar articulation (see pages 122 and 123). The arthrodia of the tarsus consist of a variable number of single or combined articulations, since neighboring articular cavities frequently intercommunicate, and while the number of articular facets is relatively large, the number of joints is comparatively small because the small lateral articular facets do not all form independent articulations. The cuneonavicular articulation (Fig. 225) is the joint between the articular surface of the navicular bone and the posterior articular facets of the three cuneiform bones; it also extends between the opposed articular facets of the cuneiform bones and between the internal articular Tibia Fibula ee Tarsometatar al joint of great loe Int. cuneiform bone Posterior lig of external malleolus ry naviciia Posterior calcaneal Posterior talo-tibial lig. Talonavicul Calcaneo- articulation tibial lig. Internal talo- calcaneal lig ae / Fig. 224. bie oS OA Calcaneus Calcaneal tendon Inferior articular Tibia surface of tibia Fibula Ta External malleolus Articalar surface Deltoid ligament Calca- neo~ | fibular lig. Posterior talo-caleaneal articulation Fig. 220. Flexor digitorum brevis Calcaneus Long plantar ligament X THE JOINTS AND LIGAMENTS OF THE FOOT. 139 surface of the cuboid and the corresponding surfaces of the navicular and external cuneiform bones. The joint also usually communicates between the internal and middle cuneiform bones with the second tarsometatarsal joint, and is consequently a very complicated articulation. The /arso-metatarsal articulation (Lisfranc’s joint) (Fig. 225), together with the infer- metatarsal articulations (Fig. 225), form three separate joints: one connecting the metatarsal bone of the great toe with the internal cuneiform bone; one connecting the bases of the second and third metatarsal bones with each other and with the middle and external cuneiform bones; and the third connecting the fourth and fifth metatarsal bones with the cuboid bone. The line of Lis- franc’s joint has its most proximal point at the inner margin of the sole of the foot and its most distal point at the base of the second metatarsal bone, so that a deep indentation is present in this situation. From this point the joint-line pursues a markedly distal direction and then makes a distinct curve toward the proximal portion of the foot. The movements in the tarsal arthrodia are extremely slight, since numerous tense ligaments limit the range of motion very considerably. The slight movements which are possible supplement the chief movements of the foot. The metatarso- phalangeal and the digital (interphalangeal) joints resemble the corresponding joints of the hand with slight variations. The metatarso-phalangeal joint of the great toe in particular exhibits a special mechanism, as two large sesamoid bones are embedded in the plantar surface of its capsular ligament (see page 106) and transform the articulation into a species of hinge joint. A further peculiarity is the marked dorsal extension of the articular surfaces, par- ticularly those of the second to the fifth metatarsal bones, which permit of a hyperextension (dorsal flexion) of the toes. These articulations also resemble hinge joints more than arthrodia (ginglymo- arthrodia). Ossification is frequently observed between the individual phalanges, particularly in the little toe. The accessory ligaments of these joints are similar to those of the hand (frans- verse capitular (Figs. 228 and 229), accessory plantar, and /ateral ligaments). THE LIGAMENTS OF THE TARSUS. The ligaments of the tarsus (Figs. 224 to 230) may be subdivided into: (1) The liga- -ments of the ankle-joint, (2) the ligaments between the astragalus and the calcaneus, (3) the dorsal tarsal ligaments, (4) the plantar tarsal ligaments, and (5) the interosseous tarsal ligaments. The ligaments of the ankle-joint (Figs. 224 and 226 to 228) connect the bones of the leg with the talus (astragalus) and the calcaneus, and pursue a more or less vertical direction. Each of the two malleoli is connected with the neighboring tarsal bones. The deltoid ligament (Fig. 227) arises from the internal malleolus and radiates to the talus (astragalus), the calcaneus, and the navicular bone. It is narrower at its origin, broad at its insertion, and is composed of four separate ligaments: the anterior talo-tibial, the posterior talo-tibial, the calcaneo-tibial, and the libio-navicular ligaments. The anterior talo-tibial ligament (Fig. 227) passes to the anterior extremity of the neck of the _ talus (astragalus) and is almost completely covered by the calcaneo-tibial ligament (Fig. 227) which runs to the margin of the sustentaculum tali. The posterior talo-tibial ligament (Figs. 224 140 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 227.—The ligaments of the tarsus seen from the inner side (#). Fic. 228.—The ligaments of the foot seen from above and from the outer side (3). Fic. 229.—The ligaments of the foot seen from the plantar surface (2). Fic. 230.—The ligaments of the foot seen from the dorsal surface. The talus has been removed so as to show the participation of the navicular ligament in forming the socket of the talocalcaneo-navicular joint (#). and 227) goes to the posterior process of the talus, and the tibio-navicular (Fig. 227) has its insertion upon the dorsal surface of the navicular bone. Ligaments pass in a similar manner from the external malleolus to the talus (astragalus) and to the calcaneus. These are known as the anterior talo-fibular, the posterior talo- fibular, and the calcaneo-jfibular ligaments. The anterior talo-fibular ligament (Fig. 228) passes almost horizontally from the anterior surface of the external malleolus to the an- terior margin of the trochlea of the talus; the posterior talo-fibulgr (Fig. 224) pursues a corresponding course and connects the posterior border of the external malleolus with the outer tubercle of the posterior process of the talus; and the calcaneo-jfibular ligament (Figs. 226 and 230) passes somewhat obliquely downward and backward from the tip of the external malleolus to the outer surface of the calcaneus. Upon this ligament run the tendons of the two peroneal muscles (see page 222). The ligamentous connections between the astragalus and the calcaneus consist of the rein- forcing ligaments of the talo-calcaneal articulation and of the ligamentous mass which occupies the sinus of the tarsus, the interosseous talo-calcaneal ligament. The latter (Figs. 225 and 230) consists of a number of firm fibrous layers and forms a species of syndesmosis between the two bones. The reinforcing ligaments of the posterior articulation of the two bones are known as the internal, external, posterior, and anterior talo-calcaneal ligaments. The external and particularly the anterior ligaments, which bridge over the sinus of the tarsus, are connected with the inter- osseous ligament. The external ligament (Fig. 228) passes from the outer and lower surface of the neck of the talus (astragalus) to the upper surface of the calcaneus; the anterior ligament connects the lower surface of the talus (astragalus) with the upper surface of the calcaneus; the posterior ligament connects the outer tubercle of the posterior process of the talus with the upper surface of the calcaneus; and the very narrow internal ligament passes from the inner tuber- cle of the posterior process of the talus to the sustentaculum tali. The dorsal and plantar ligaments of the foot are practically horizontal, and are composed partly of transverse and partly of longitudinal fasciculi which connect neighboring bones and consequently reinforce the articular capsules. The plantar ligaments are considerably the stronger, and some of them connect distant portions of the tarsus, passing over one or even more bones. The dorsal tarsal ligaments are those which connect the talus (astragalus) and the cal- caneus with the navicular and the cuboid bones. They are the dorsal talo-navicular ligament, the dorsal calcaneo-navicular ligament, and the bijurcate ligament. ‘The bifurcate ligament (Fig. 228) connects the antero-internal angle of the calcaneus with the dorsal surfaces of the navicular and Anterior talo- tibial lig. | Tibio- navicular lig. Deltoid ligament Tendon of tibialts anter. Dorsal Caleaneo- tibial lig. - Deltoid tarsometatarsal re. ligament = Posterior talo-tibial lig. Tendon of tibialis posterior Sustentaculum tali Tibia Fibula Anterior lig, of external malleolus Calcaneus Calcaneal tendon Anterior tulo- fibular lig. Anterior talo-fibular l 1g. | External talo- | caleaneal lig. , hi “" , ; yr Bifurcate lig Plantar salianeo- Long plantar Dors. cuboideo-navicular lig. navictlar lig lig. Dorsal naviculari-cuneiform lig. Dorsal basal lig. 7 Calcaneo- 4 = Fig. 227. fibular lig. . , P MW & Ba — — ~ ‘Transverse capttular lig. ey eae “ale : Long ee lar oabotd. Dorsal Tendon of _* ; ie j ~- . : : calcanco , He ors -so-metatarsa plantar lig. portion portion Seabed peronaeus Dorsal tarso-meta of bifurcate lig. brevis ligaments lig Metatarso-phalangeel articulations Transverse capitular ligaments Sesamoid bons Tendon of peronaeus longus Plantar tarsometatarsal ligts. Plantar rr’ basal ‘ ligaments | a oo 11 | Tendon of hy peronaeus At Dorsal tarso-metatarsal brevis Plantar naviculari- ligaments Groove for cuneiform ligaments tendon of { ) peronaeus Plantar longus \ cuboideo- \ navicular \ lig. \ iN \ Tendon of . tibialis ‘ Pe posterior Dorsal - uncocuboid ant Dorsas lig : - * “ i) inter- 4 “ “A Long. . Plantar calcaneo ee plantar lig. navicular lig. ia Dorsal naviculari- cuneiform ligts. Dorsa! calcaneo- caboid lig Tendon of : : ner peronacu: Articular facet of navicular bone ge becee vag brevis Fi lg. 229. Navicular fibrocartilage Middle articular facet of calcaneus Interosseous talo-calcaneal ligament Anterior articular facet of calcaneus Posterior articular facet of calcaneus Fig. 230. ers * ~~ is . ‘acto’ ae - welbaoa? ie | Wea ese’ 3: a ag vw f ; eS aera THE JOINTS AND LIGAMENTS OF THE FOOT. 141 cuboid bones; it necessarily divides into two portions, one for each bone, known as the calcaneo- navicular and the calcaneocuboid portions. The navicular is connected with the cuneiform bones by the three dorsal navicular-cunei- jorm ligaments (Fig. 228). The first of these is the broadest. The cuboid and navicular bones are connected by the dorsal cuboideo-navicular ligament (Fig. 228); the cuneiform bones are connected with each other by the dorsal intercuneijorm ligaments (Fig. 230); and the dorsal cuneo-cuboid ligament (Fig. 230) runs between the external cuneiform and cuboid bones. The connection between the bases of the metatarsal bones and the tarsal bones is effected by the dorsal tarsometatarsal ligaments (Figs. 228 and 230); the bases of the metatarsals are connected with each other by the four dorsal basal ligaments (Fig. 228). The plantar tarsal ligaments maintain the normal arch of the foot. By far the largest and strongest of them is the /ong plantar ligament (Figs. 226, 227, and 229), which is, indeed, one of the strongest ligaments of the body. It arises from the entire lower surface of the calcaneus in front of the tubercles of the tuberosity, its width almost entirely covering the bone, and its strong longitudinal fasciculi are inserted into the tuberosity of the cuboid. From the main mass of the ligament there are given off superficial fasciculi which pass over the tendon-sheath of the pero- neus longus situated in the cuboid groove, and extend to the bases of the outer metatarsal bones (see page 227, Fig. 312). The second strongest ligament of the tarsus is the plantar calcaneo-navicular ligament (Figs. 227 and 229), whose strong fibers pass obliquely between the sustentaculum tali and the navic- ular bone. The dorsal surface of the ligament is covered with cartilage and contains the navicu- lar fibrocartilage (Fig. 230), which forms a portion of the socket for the head of the talus (astrag- alus) (see page 138). Upon the dorsal surface of the foot this ligament is connected with the tibio-navicular ligament. The plantar calcaneocuboid ligament is adherent to the dorsal surface of the long plantar ligament and reinforces the plantar surface of the articular capsule of the calcaneocuboid joint. The navicular and the cuneiform bones are connected by the plantar naviculari-cuneijorm liga- ments (Figs. 227 and 230); the cuboid and the navicular bones by the plantar cuboideo-navicu- lar ligament (Fig. 230); the cuboid and the external cuneiform bones by the plantar cuneo-cuboid ligament; and the three cuneiform bones with each other by the plantar intercuneijorm ligaments. There are also plantar tarso-metatarsal ligaments and three plantar basal ligaments, which pursue a similar course to the corresponding dorsal ligaments. The interosseous ligaments are those ligaments of the foot which are situated neither upon the dorsal nor the plantar surface, but which connect contiguous surfaces of the tarsal or metatar- sal bones in those situations where no articular connection exists. They really represent syndes- moses, and are found only between those bones which move upon each other but slightly, if at all. In addition to the previously mentioned interosseous talocalcaneal ligament (Figs. 229 and 230), these ligaments are the inferosseous cuneo-cuboid ligament, the interosseous intercuneijorm liga- ments, the interosseous cuneo-metatarsal ligaments (particularly between the internal cuneiform and the base of the second metatarsal bone, where an interosseous basal metatarsal is wanting), and the inéerosseous basal metatarsal ligaments. The upper and lower surfaces of some of these ligaments are in direct contact with the corresponding dorsal and plantar ligaments. MYOLOGY. GENERAL MYOLOGY. Myology is the study of the muscles and of their accessory structures, such as tendons, aponeuroses, fascia, intermuscular septa, tendinous arches, pulleys, mucous bursz, tendon- sheaths (vagine mucose), tendon relinacula, and sesamoid bones. The musculature of the human body occurs in two forms which present both histological and physiological differences (see “Atlas and Epitome of Normal Histology,” Sobotta-Huber). The actual skeletal muscles are composed only of striated muscular tissue. The muscles form the fleshy portion of the body, and are contractile structures which vary considerably in size and shape. A typical muscle is composed of a muscular belly, which forms the greater portion of it, and of two ends, one of which is known as the origin, or head, and the other as the insertion, the origin being that end which is attached to the usually more fixed portion of the skeleton and the insertion that attached to the more freely movable portion, but the physio- logical relation of origin and insertion may be reversed. As a rule, both the origin and the insertion possess a tendon of varying length, which is usually considerably thinner than the muscle. Muscles are distinguished according to their shapes. A great many, particularly those forming the mass of the extremities, are fusiform or spindle-shaped, while others are broad, thin, and flat; muscles whose length but slightly exceeds their breadth are designated short muscles. Some muscles surround orifices of the body or canals, and their fibers are circularly arranged; they are known as orbicular muscles, or, if they serve to close orifices, such as the mouth, for example, as sphincters. Those muscles in which the fasciculi pass to a tendon developed at the side of the muscle are known as pinnate or penniform muscles, and if the tendon be situated in the middle and receives muscular fasciculi from either side, the muscle is said to be bipinnate or bipenniform. The majority of the muscles have a single head, but occasionally two, three, or four heads unite to form a muscular belly, producing a biceps, triceps, or quadriceps muscle. A muscle com- posed of two bellies with an intervening tendon is termed a biventer or digastric muscle. If muscles pass only over one joint of the body (particularly in the extremities), they are known as monarticular muscles; if they extend over two main joints in their course, they are called biarticular. Lendons occur in connection with nearly all the muscles, and are completely absent in the sphincters only, though partly wanting in the orbicular muscles. Every muscle, however, has not a tendon at both ends, it frequently happening that only the tendon of insertion is developed, while the origin is purely muscular. The fibers of the tendons of origin or insertion are very 142 ; origin or insertion exists. GENERAL MYOLOGY. 143 frequently mixed with muscular fibers, so that neither a purely muscular nor a purely tendinous The spindle-shaped muscles have cylindrical and frequently very long tendons, but the flat muscles usually arise by means of flattened tendons which are known as aponeuroses, and, in . the cases of the flat muscles, may serve as fasciw for other muscles. The round tendons also occasionally form aponeuroses in the vicinity of their insertions. Broad tendinous plates are sometimes found upon one of the surfaces of a muscle in the middle of its course, and a muscle may possess a number of tendinous interruptions, arranged at more or less regular distances from each other; these are termed fendinous inscriptions. The jasci@ are connective-tissue coverings which surround individual muscles or groups of muscles. ‘They are frequently adherent to their muscles and form their aponeuroses, and are especially well developed in the extremities, where they form a common superficial sheath for all of the muscles. Some muscles do not possess fascia, as, for example, the muscles situated in the skin, such as the platysma and the majority of the facial muscles. The intermuscular septa are intimately connected with the fascia, being sheet-like prolonga- tions of those of the extremities, extending to the periosteum so as to form partitions between - groups of muscles having a similar function (synergists*); they frequently also give origin to muscles. The fendinous arches are ligamentous bands which bridge over vessels or nerves and pro- tect them as they pass through a muscle; they may also pass between two neighboring bones and furnish a support for muscular origin. Pulleys or trochlee are for the purpose of giving the tendon of a muscle a different direction from that of the belly. The fendon retinacula operate in a similar manner, and are found chiefly in those situations where tendons run in a bony groove. They hold the tendons firmly in the channel and prevent their displacement; a similar function is served by the vaginal ligaments which maintain the tendon-sheaths (see below) in position. The mucous burse are thin-walled cavities filled with a fluid similar to that of the synovia of the joints. They are found where muscles or tendons pass over bony prominences or where tendons are inserted into a bone, and serve to prevent friction between the muscles and tendons and the bone. They are frequently diverticula of the synovial membranes of the joints (see page 108). The fendon-sheaths or vagine mucos@ act in a similar manner; they surround the tendons of the muscles of the extremities (particularly in the hand and foot) for a certain distance, and pro- tect the tendons from friction during action. They are partly protected by retinacula, and partly by vincula. Sesamoid bones are mechanical accessories of the tendons in which they are usually embedded. They are not necessarily bony but are often only fibrocartilaginous, and serve the purpose of increasing the working angle of the tendons and of making it possible for the tendons to glide over the joint. The patella (see page 99) is the largest sesamoid bone of the body. The striated musculature of the body, with few exceptions, arises from the myotomes of the mesodermic somites. The musculature of the trunk arises directly from these structures, and its segmental arrangement, corresponding to its ‘ * Muscles having opposite functions are termed antagonists. I44 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 236.—The superficial layer of the flat muscles of the back together with the neighboring muscles of the head, neck, abdomen, and buttock. Upon the right side the rhomboideus major and the teres major are represented covered by fascia. origin, can usually be distinctly recognized in the deeper layers of the muscles of the back and neck. The muscles of the abdomen and of the extremities arise secondarily from the myotomes. In man the musculature of the extremities is very strongly developed and covers the entire dorsal and part of the ventral musculature of the trunk. [In the following pages the classification adopted for the muscles is a topographical one, an arrangement which best accords with an atlas designed as an aid for the laboratory, Such a classification, however, is in many cases faulty in that it fails to present the true morphological relations of the muscles, sometimes grouping together muscles which have entirely different morphological values, and sometimes separating in different groups muscles which in reality are closely related. - At the close of each section where it seems necessary there will be found a brief morphological classification of the muscles of which it treats—Ep,] SPECIAL MYOLOGY. THE MUSCLES OF THE TRUNK. THE MUSCLES OF THE BACK. The muscles of the back are arranged in layers and extend throughout the neck, the back, and the lumbar region. The muscles of the individual layers may be advantageously grouped, Obliquus abdominis Lumbar vertebra Transversus abdominis internus ? r Psoas major Lumbo- dorsal Quadra- Trans- fascia tus lum- versalis (ant. borum jascia la yer ) ~ Obliquus ab- dominis externus unction of anterior and posterior layers of \ lumbo-dorsal jascia Lumbo-dorsal fascia Long muscles Lumbo-dorsal fascia (posterior layer) of back (posterior layer) Fic. 237.—Transverse section of the posterior wall of the abdomen in the lumbar region (schematic). : p according to their shape, in three subdivisions—the flat or surface muscles, the long muscles, and the short muscles. The flat muscles are still further subdivisible into several layers, some of THE MUSCLES OF THE BACK. 145 which completely conceal the others; the superior layers are inserted into the skeleton of the uppei extremity and consequently are really muscles of the extremity. The long and short muscles are portions of the actual musculature of the trunk, and are situated in the groove between the spinous processes of the vertebre and the angles of the ribs (or the costal processes of the remaining vertebra), and many of them extend upward as far as the head. The long muscles of the back extend over a large number of vertebre and in their superficial layers extend over the entire vertebral column; the short muscles pass from vertebra to vertebra. The flat muscles are also designated as superficial, the long and short as deep muscles of the back. THE FLAT MUSCLES OF THE BACK. The flat muscles of the back (Figs. 236 and 238) are arranged in three lavers which partially overlap each other. The first layer is formed by the trapezius and the latissimus dorsi, the second by the rhomboidei and the levator Scapule, and the third by the serratus posterior superior and inferior and the splenius capitis and cervicis. The muscles of the first and second layers are inserted into the skeleton of the extremities; those of the third layer find their insertions in the skeleton of the trunk. The First Layer. The trapezius or cucullaris (Figs. 236 and 256) takes its name from the trapezium formed by the muscles of the twe sides. Each muscle by itself is triangular, its longest border being situated at the vertebral column. It is flat and smooth; below, and particularly above, it is very thin, and it is situated in the nuchal, median dorsal, suprascapular, scapular, and infrascapular regions. It takes origin from the following situations: from the inner half of the superior nuchal line (extending to the linea Suprema as a short thin tendon), from the external occipital protuber- ance, from the nuchal ligament (by a muscular origin, sometimes by a short tendon in the upper portion), and from the spinous processes and supraspinous ligaments of all of the thoracic vertebra (more or less tendinous). It is inserted into the upper surface of the acromial third of the clavicle, into the inner Margin of the acromion, and into the entire length of its upper border, and partly also into the inner portion of the lower border of the spine of the scapula. The superior fibers of the trapezius pass from within outward and from above abruptly downward to the lateral portion of the neck (Fig. 256); the middle fibers are the shortest and pass almost horizontally outward; while the inferior fibers run from within outward and from below abruptly upward. Tendinous areas are constantly found at the origin of the trapezius from the occiput, in the region of the seventh cervical vertebra and of the spines of the upper thoracic vertebre, and at its insertion into the inner end of the spine of the scapula; the fibers coming from the spines of the lower thoracic vertebrae are also tendinous for a certain distance, and in the region of the spines of the upper thoracic vertebra the muscles of the two sides form a broad, well-developed, trapezoid aponeurosis. At the occiput the trapezius joins the tendinous insertion of the sternocleidomastoid. Be- tween the two muscles, the splenius capitis and the levator scapule are always partly visible, and if the upper part of the trapezius is narrow, a portion of the Semispinalis capitis also appears Io eu 146 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. between it and the splenius capitis. The deltoid has its origin immediately adjacent to the insertion of the trapezius, and a small transverse muscle occasionally passes between the insertions of the trapezius and the sternocleidomastoid; it is known as the fransversus nuche (Fig. 244), and usually has a tendinous origin from the tendon of one muscle and passes to the tendon of the other. The trapezius is supplied by the accessory nerve and by the cervical plexus. On account of the different directions taken by the fibers in different portions of the trapezius the function of the muscle is complicated, and differs according to whether all portions of the muscle contract simultaneously or individ- ual portions contract separately. Its action also depends upon whether the scapula is fixed or movable. The upper portion of the trapezius elevates the entire shoulder girdle, the lower portion pulls the scapula downward, and the middle portion draws the scapula backward toward the vertebral column. The scapula is also drawn backward by the action of the entire muscle, since the upper and lower fasciculi neutralize each other to a certain extent and aid the middle portion of the muscle. If the shoulder-blade is fixed, the muscle turns the head; when both scapule are fixed and the two muscles act together, the head is extended. The muscle may also fix the scapula. It usually acts together with the levator scapuli, the rhomboidei, the splenii, and the other muscles of the back. The latissimus dorsi (F igs. 236, 238, 269, and 272) isa broad, thin, triangular muscle which becomes somewhat thicker toward its insertion. The upper portion of its origin is partly con- cealed by the trapezius, and it is situated in the median dorsal, the sacral, the lumbar, the infra- scapular, and the scapular regions. Its origin is tendinous throughout, with the exception of three or four accessory digitations which arise from the three or four lower ribs. The tendon of origin is furnished by the posterior surface of the posterior layer of the lumbodorsal fascia (see page 156), by means of which the muscle arises from the spinous processes of the lower five or six thoracic vertebre, from the spinous processes of the lumbar vertebre, and from the median ridge of the sacrum and the neighboring portion of the outer lip of the crest of the ilium. The superior fibers run almost horizontally; the inferior fibers ascend abruptly from within outward and from below upward, and toward the insertion the fibers converge, and terminate in a flat tendon which is adherent to that of the teres major and is inserted with it into the lesser tubercular tidge (the posterior lip of the bicipital groove) of the humerus. An almost constant bursa, the latissimus bursa, separates the non-adherent portions of the tendons of the latissimus dorsi and teres major. The tendinous surface of the posterior layer of the lwmbodorsal jascia (Figs. 238 and 240) is widest in the region of the middle and lower lumbar vertebra, and it becomes markedly nar- rower as it extends upward, and to a lesser degree as it passes downward. Between the upper border of the latissimus, the lower border of the trapezius, and the vertebral border of the scapula, there is a triangular space, which is larger or smaller according to the position of the scapula and in which are visible a portion of the rhomboideus major, small portions of one or more of the middle ribs with their intercostal muscles, and a segment of the iliocostalis dorsi. Upon the neighboring dorsal surface of the scapula, the dense infraspinatus fascia covers the infraspinatus muscle, and a portion of the deltoid muscle, covered by its fascia, is also visible in this situation. The costal serrations of the latissimus dorsi interdigitate with the inferior serrations of the obliquus abdominis externus (Fig. 247). Between the outer border of the latissimus, the pos- terior border of the external oblique, and the crest of the ilium there is usually a small triangle, - Occipitalis Semispinalis capitis Splenius capitis _—-- Sacrospinalis 3 S 3 3 Se 3 a F g 8 3 ‘ x = 8 5) ”“ x s Ss ae 4 8 c et oF » / . i —— BVO \\\\ \\ \ : - 1 NANA pe -Obliquus abdominis externus Lumbar triangle-= —-- volar digital rr. : nasal | Ey, oral r ; cf 7 j lamach { anterior mental r. ; ternocleidomastotd cubital r. infraclavi- aad Jateral cervical r cular ae ee = UPractavicusa z i SS ciaviciiiar middle cubital r. Ea olecranal r. post brachial r. axillary fossa lateral pectoral r. inframammary fr lateral abdominal r. inguinal r. - nl r COXQaL TF. nbinouinal r. suoinguinatl fF. trochanteric r. pudendal r. external femoral r. patellar region sural fr external crural ?. internal crural r. internal retromalleolar r. internal malleolar r. calcaneal r. digital rr. of foot. ungual rr. Fig. 231. Regions of the human body. neual rr. < 5 mastoid r. nee Be ONE” . » auricular r. fovea nuchae } ( acromial r external cubital r. olecranal r. posterior ! cubital r K e \ Ry digital rr volar external femoral r. external crural r external \ brachial r internal brachial r temporal r. acTrou- rad nual r. antertor antibr. r brachial is zt > posteric 4 olecranal Fs rpee lateral pe torai r - f as ~ hypochondriac fr. A lateral abdominal r. ; | anal r. \\ | _--- trochanteric r. popliteal fossa _---- external retromalleolar r. i) é ----- external malleolar r. ‘ dorsal of foot calcaneal r. Y ofFoor te G Fig. 232. Regions of the human body. ; superior palpebral r. . inferior palpebral r superior labial r. -_ inferior labial r. auricular ¢ mastoid r. retromandibular fosse La suprasternal r. __ \ " + h riangle a 4 t ; . + lesser supraclavicular fossa [ jugular fossa Fig. 233. Regions of the head and neck, ° : } - . , ‘ - . . . ’ oe ' , 4 ~* ’ ro . Be fn eee “ 3 ~ . o - ‘ ~ } a perineal regions. THE MUSCLES OF THE BACK. 147 the /umbar triangle or triangle oj Petit (Fig. 236), in which a portion of the origin of the obliquus abdominis internus from the anterior layer of the lumbar fascia (see page 160) is exposed. The posterior border of the latissimus dorsi forms a part of the posterior boundary of the axillary fossa, and the muscle not infrequently receives accessory fibers from the inferior angle of the _ scapula (the scapular digitation). Since the latissimus is really one of the muscles of the extremity, it is supplied from the plexus brachialis, its nerve being the thoracodorsal (middle or long subscapular) nerve. The latissimus dorsi adducts the arm, carrying it backward and rotating it inward. The Second Layer. The second layer of the flat muscles of the back (Fig. 238) is covered by the trapezius, with the exception of a portion of the rhomboideus major, which is exposed between the latissimus and the trapezius, and of that part of the levator scapula which is situated immediately beneath the cervical fascia at the outer border of the trapezius. This layer is not represented beneath the latissimus which directly overlies the third layer. The rhomboideus major (Fig. 238) is a flat and rather thin quadrangular muscle which arises from the spinous processes and supraspinous ligaments of the upper four thoracic vertebra. Its fibers are distinctly parallel and pass downward to be inserted into the vertebral border of the scapula below the root of the spine. The muscle is frequently rather intimately connected with the rhomboideus minor, and, according to the position of the scapula, may be either quadrangular or rhomboidal in shape. The rhomboideus minor (Fig. 238) resembles the major in every respect, but is much narrower. It takes origin from the spinous processes of the two lowermost cervical vertebre and inserts into the vertebral margin of the scapula above the root of the spine. The two rhom- _ boidei are separated by a cleft, which is usually quite narrow, and as a rule their origins are distinctly tendinous (aponeurotic). The rhomboidei are supplied from the brachial plexus by the dorsal scapular nerve. They draw the scapula _ toward the vertebral column and somewhat upward. The levator scapule (Figs. 238 and 258) is the only one of the flat muscles which possesses any considerable degree of thickness. It is an elongated muscle which arises by four short tendinous digitations from the posterior tubercles of the transverse processes of the four upper cervical vertebre, the largest digitation coming from the transverse process of the atlas. The digitations unite to form a single belly which passes outward and downward and is inserted into the superior angle of the scapula immediately alongside of the rhomboideus minor. The levator scapulz forms a portion of the lateral cervical region and is immediately adjacent to the posterior margin of the scalenus posterior. Its origin is partly covered by the posterior ee rtion of the sternocleidomastoid. ‘The levator scapulz, like the rhomboidei, is supplied by the dorsal scapular nerve. It elevates the superior angle of i he scapula and consequently the entire shoulder-blade, thereby assisting the trapezius and the rhomboidei. When he scapula is fixed, it can incline and rotate the cervical portion of the vertebral column. " 148 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 238.—The deeper layers of the flat muscles of the back. On the left side the trapezius and latissimus have been cut away; on the right side the rhomboidei have also been cut and reflected and the lumbodorsal fascia has been retained only where it is in relation with the origin of the serratus posterior inferior and below. The Third Layer. The muscles of this layer (Figs. 238 and 239) are situated partly beneath the rhomboidei and partly directly beneath the latissimus and the trapezius. The two splenii are also covered at their origins by a muscle of the same layer, the serratus posterior superior. The serratus posterior superior (Fig. 238) is a flat muscle, rhomboidal in shape, which is tendinous for almost half its breadth and is wholly or almost wholly covered by the rhomboidei. It arises by an aponeurosis from the spinous processes of the two lowermost cervical and of the two uppermost thoracic vertebra, passes outward and downward, and is inserted by four flat muscular digitations into the outer side of the angles of the second to the fifth ribs. It is supplied by the upper (first to fourth) intercostal nerves. It draws the upper ribs upward and backward and acts as a muscle of inspiration by enlarging the thorax. The serratus posterior inferior (Fig. 238) resembles the serratus posterior superior in many respects, but it is flatter and its fibers run from within outward and from below upward. It arises from the anterior surface of the posterior layer of the lumbodorsal fascia in common with the latissimus dorsi, at the level of the two lowermost thoracic and the two uppermost lumbar vertebra; it is at first a thin and independent aponeurosis, but subsequently becomes entirely muscular, and is inserted into the lower borders of the lower four ribs by digitations which fre- quently vary in their development or may be wanting. The muscle is supplied by the lower (ninth to twelfth) intercostal nerves. It draws the lower ribs backward and downward. Whether it aids inspiration or expiration is uncertain; in either case its influence upon the ribs is very slight. It may increase the tension of the lumbar fascia. The splenius capitis (Figs. 238 and 239) is a strong, elongated, strap-shaped muscle, which arises by means of the nuchal ligament from the spinous processes of the lower four or five cervical and from the upper two or three thoracic vertebree. It passes from within outward and from below upward, partly covered by the trapezius, the rhomboidei, and the serratus posterior superior, and its insertion is into the outer half of the uppermost nuchal line of the occipital bone extending as far as the mastoid process. The insertion is covered by the sternocleidomastoid. The splenius cervicis (Fig. 239) is situated immediately to the outer side of the splenius capitis. It arises in immediate succession to the latter muscle from the spinous processes of the third or fourth to the fifth or sixth thoracic vertebra, and passes obliquely outward and upward as a flat but rather slender muscle, to be inserted into the posterior tubercles of the transverse processes of the upper two or three cervical vertebra. Its insertion is intimately connected with the origin of the levator scapule. The two splenii are supplied from the posterior divisions of the second to the eighth cervical nerves. When the muscles of both sides act in common, they pull the head (or the neck) backward, and when the muscles of one side act alone, they turn the head (or the neck) toward the side of the contracting muscle. Occipitalis Semispinalis capitis eh] y Sternocleidomastoideus ~Splenius cervicis Levator scapulae Levator scapulae Teres mayor Latissimus » Serratus anterior.- ~Latissimus x Rib Xi1/ ac Obliquus __.---¥ abdominis internus _ vy Gee ~ 7 i Po )-. ae oe a if ‘ is Ce 4 = ‘ ’ . 5 Pa bs Pa > (FA - fia - P; t 7 a “4 - 4 . * . es 8 | y ae 4 = ey ry ye. ch 5 5 ~ i i “' f . t “x THE MUSCLES OF THE BACK. 149 THE LONG MUSCLES OF THE BACK. The long muscles of the back (Figs. 239 and 242) are subdivided into two layers according to the direction of their fasciculi. In the superficial layer, the spinotransversalis, the fibers pass from the spinous processes to the transverse processes or to the ribs; in the deep layer, the trans- versospinalis, they pass from the transverse to the spinous processes. The spinalis, belong- ing to the upper layer, is the only muscle passing from spinous process to spinous process. The First Layer. The Spinotransversalis and Spinalis. The muscles of this layer (Fig. 239) fill the vertebral groove between the spinous processes of the vertebra and the angles of the ribs, and extend over a large area of the vertebral column, usually the entire length of the back. With the exception of a small portion which may lie directly beneath the skin, between the trapezius and the latissimus dorsi (see page 145), they are com- pletely covered either by the flat muscles of the back or by the posterior layer of the lumbar fascia. The spinotransverse fibers form a single, large, complicated muscle, the sacrospinalis. The sacrospinalis or erector spine (Figs. 239 and 241) is a long and strong muscular mass which extends from the dorsal surface of the sacrum and the crest of the ilium to the skull. It forms a single mass only in its lower portion, dividing as it passes upward into two separate muscles, the external and weaker iliocostalis and the internal and stronger /ongissimus dorsi. Internal to the latter muscle and adherent to it is situated the spinalis, so that the superficial layer of the long muscles of the back is arranged in three longitudinal strips upon either side of the vertebral column, a strong median one, the /ongissimus, an external one, the iliocostalis, and an internal one the spinalis. Before its division the sacrospinalis is a thick powerful muscular mass, whose surface is strongly aponeurotic and which arises from the dorsal surface of the sacrum, from the spinous processes of the lumbar vertebra, and from the crest of the ilium and is included between the two layers of the lumbar fascia (see page 156). The iliocostalis lumborum > and the longissimus dorsi pass upward directly from this mass. | The iliocostalis (Figs. 239 and 241) is the outer portion of the sacrospinalis, and is composed of three subdivisions—the i/iocostalis lumborum, dorsi, and cervicis. The iliocostalis Lusberum (Figs. 239 and 241) arises in common with the longissimus and inserts into the angles of the fifth to the twelfth ribs. The superior insertions are by means of long tendons, while the lower insertions are in the shape of fleshy serrations, the lowermost of which is the strongest and passes to the lower border of the twelfth rib. The greater portion of the origin of the iiocostalis dorsi (Figs. 239 and 241) is covered by the iliocostalis lumborum. It arises by means of special accessory serrations from the inner side of the angles of the twelfth to the seventh ribs, and is inserted by thin tendons which pass to the angles of the sixth to the first ribs and to the transverse process of the last cervical vertebra. The iliocostalis cermicis (Figs. 239, 240, and 241), also termed the cervicalis ascendens, is a slender muscle the origin of which is intimately connected with the iliocostalis dorsi. It comes from the upper and middle ribs in a variable manner and is inserted by narrow tendons into the transverse processes of the middle cervical vertebrae immediately alongside of the scalenus pos- terior (see page 175), with the origin of which it may be adherent. I50 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 239.—The superficial layer of the long muscles of the back. All the flat muscles, the splenii and the iliocostalis of the left side have been removed. The longissimus, the inner portion of the sacrospinalis, is composed of three subdivisions —the longissimus dorsi, cervicis, and capitis. > Transverse processes Rotatores longi = f Rotatores breves “~—€ ———— Semispinalis Muitifidus ~~ Spinous process <.-- Fic. 240.—Diagram of the arrangement of the various portions of the transverso-spinalis (semispinalis, multifidus, rotatores). The longissimus dorsi (Figs. 239 and 241), in addition to its common origin with the ilio- costalis lumborum, receives accessory origins from the transverse processes of the lower thoracic vertebr. Its insertions are arranged in an internal and in an external series, and are, partly a iP Splenius capitis » " Splenius capitis a oP 1, - Sternocleidomastoid Longissimus capitis == J Sf _ ; , - Splenius cervicis » al Splenius cervicis A Longissimus cervicts Levator scapulae ™ ¥ . 4 : - : . - i $ haa heal 7 7 i F/ ql - f j i Iliocostalis cervicis -4 . ‘ Serratus poster. = ll 1 ae am super. f — ; it = . is > te Y ’ . ‘/ , - - ' '— 7 _ \ s ¢& ‘al | Se Semispinalis dorsi ~~ Spinalis Spinalis Latissimus dorsi » Serratas an terior pSerratus poster. infer Obliquus abdominis ext THE MUSCLES OF THE BACK. Is! fleshy, partly tendinous, and their digitations are frequently variable. Those of the internal series are inserted into the accessory processes of the upper lumbar vertebra and into the trans- verse processes of the thoracic vertebra; those of the external series insert into the apices of the transverse processes (costal processes) of the upper lumbar vertebra and into the ribs between the angles and the tubercles. The serrations of the internal insertions consequently pass to the transverse processes and their homologues, while those of the external series run to the ribs or homologous parts. The longissimus cervicis (Figs. 239, 241, and 242), also known as the (ransversalis cervicis, is the direct continuation of the longissimus dorsi. It arises from the transverse processes of the upper thoracic vertebre, is situated immediately internal to the iliocostalis cervicis, and is inserted by tendinous slips into the transverse processes of the upper and middle cervical vertebre. The longissimus ca pitis* (Figs. 239, 241, and 242) is the only portion of the sacrospinalis which extends up to the head. It is situated internal to the longissimus cervicis, with the origin of which it is frequently united, and arises by separate short tendinous slips of variable extent from the transverse and articular processes of the middle and lower cervical vertebrae and from the transverse processes of the upper thoracic vertebra. This muscle often presents a tendinous inscription, is inserted by a short tendon into the posterior margin of the mastoid process, and is completely concealed by the splenius capitis. The iliocostalis and longissimus cervicis and the longissimus capitis are situated beneath (in front of) the two splenil. The spinalis (Figs. 239 and 241) is composed of the spinalis dorsi, cervicis, and capitis, of which the spinalis dorsi alone is an independent and constant muscle, the spinalis cervicis being inconstant and the spinalis capitis a part of the semispinalis capitis. The spinalis dorsi (Figs. 239 and 241) is intimately connected with the tendinous origins of the longissimus dorsi which come from the spinous processes of the lumbar vertebra and takes its origin partly from these bony points. It is situated alongside of the spines of the thoracic vertebre and contains numerous tendinous fasciculi. It takes its origin from the spinous proc- esses of the upper lumbar and of the lower thoracic vertebre and passes to the spines of the middle and upper thoracic vertebre, bridging over one or two of the spinous processes (usually the ninth or the ninth and tenth). The spinalis cervicis (Fig. 241) is inconstant and, when present, is frequently quite rudi- mentary. It is a very slender muscle which arises from the spinous processes of the sixth and seventh cervical vertebre and inserts into the spinous processes of the epistropheus (axis) and of the third cervical vertebra. An inconstant muscular fasciculus which arises from the spinous processes of the lower cervical and upper thoracic vertebra is designated the spinalis capitis. It forms a portion of the semispinalis capitis, with which it will be described (see page 152). The Second Layer. The Transversospinalis. The fibers of this layer (Figs. 239 to 242), passing from the transverse to the spinous processes, represent in their arrangement a portion of the original trunk musculature which has * This muscle has also been termed the fransversalis capitis, the complexus minor, and the trachelomastoid. I52 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 241.—The deeper layers of the long muscles of the back. On the left side the sacrospinalis has been partly removed and the semispinalis has been cut and reflected. Fic. 242.—The cervical portion of the deeper layers of the muscles of the back, seen from the side. The trapezius and splenii have been removed. undergone but slight changes. They are arranged in three layers, each of which is described as a special muscle, although they are not separated by fascia, but are distinguishable from each other chiefly by the length of their fasciculi. The semispinalis, the most superficial layer, has the — longest and consequently the most slanting fibers, which bridge over from four to six spinous processes; the mudltifidus, the middle layer, has fasciculi which pass over two or three vertebral F spines; and the rolatores, forming the deepest layer, either extend over only one spinous process (rotatores longi) or pass to the next succeeding vertebra (rotatores brevi). With the exception of the semispinalis capitis, all of the fibers of the transversospinalis end at the spinous process of the axis. The semispinalis is absent in the lumbar region, and the rotatores are situated chiefly in the thoracic region. The semispinalis (Figs. 239, 241, and 242) consists of the semispinalis dorst, semis pinalis : cervicts, and semis pinalis capitis. ~~” The semis pinalis dorsi (Figs. 239 and 241) and cervicis (Fig. 241) are directly contin without demarcation, the lowermost fibers arising from the transverse processes of the lower” thoracic vertebrae, and the uppermost fasciculi terminating at the spinous process of the axis. — The muscle is stronger and more fleshy in the neck than it is in the back. The fibers of the — semispinalis dorsi are intermingled with numerous tendinous fasciculi and are also partly con- — nected with the spinalis dorsi. The muscle is completely covered by the longissimus dorsi and the semispinalis capitis. The semis pinalis capitis (Figs. 239, 241, and 242) is a flat but rather thick muscle and is the, strongest muscle of the neck. Asa rule, it consists of two portions which aré separated below b a adherent above at their insertion—a stronger external or semispinal portion and a weaker internal — or spinal portion. The semispinal segment, sometimes termed the complexus, arises by numerous — short tendinous slips from the transverse processes of the third cervical to the fifth or sixth thoracic vertebra, while the spinal segment arises from the spinous processes of the lower cervical and of the upper thoracic vertebre (the spinalis capitis). This latter portion is characterized by a tendin- ous inscription, and hence is sometimes termed the biventer cervicis, and sometimes, when the spinalis capitis is absent, its origin extends to the transverse processes of the second to the sixth cervical vertebra. The external portion of the muscle also usually possesses a broad tendinous inscription which is situated above the middle tendon of the biventer. Both portions of the muscle unite and pass to the nuchal surface of the occipital bone, where they insert between the superior and inferior nuchal lines. Ga The multifidus (Figs. 241 and 242) consists of the multifidus lwmborygn, dorsi, and cervici but these segments cannot be clearly demarcated from each other. It commences below at posterior surface of the sacrum and terminates above at the spinous process of the epistrophe (axis). It is strongest in the lumbar region, where it lies directly beneath the longissimus; weakest in the thoracic region, where it is covered by the semispinalis dorsi; and in the cervical 3 a 1c ra i Transversus nuchae a“ Splenius capitis » Rectus iia y is ost. miner _ “— eal “é Splenius capitis x f . — - ~ Splenius capitis» : “ 7 Obliquus = V capitis super. Sternodceido- mastoid ess NX ’ Splenius cervicis » PHETUUS CerVICs longissimus . capitis Obliquus capitis Spinalis inferior cervicis Longissimus capitis Me / ongissimus i capitis Interspinales pitts Longissimus cervicis = / ongissimus Miocostalis cervicis cervicis Semispinalis cervicis et dorsi Semispinalis dorsi et cervicis Serratus = /lliocostalis cervicis poster. super. » Fig. 241. THE MUSCLES OF THE BACK. 153 region it is partly concealed by the semispinalis cervicis, to the outer side of which it is covered by the semispinalis capitis. In the lumbar region the greater portion of its fibers arise from the acces- sory and mammillary processes, in the thoracic region from the transverse processes, and i cervical region from the articular processes of the four lower cervical vertebra. The fasciculi are intermixed with tendinous fibers and generally extend over two or three vertebra, combining | rance Occipital bone (basilar portion) 1+ At Distr / FE pist = : éV uchai digament Inters pinale > Wh «~ lifleriransversarii fosteriores « P. why ay FYc. 243.—Diagram of the cervical interspinales and intertransversarii anc to form a single uninterrupted muscular layer, the deeper portion of which is distinguishable only with difficulty from the rotatores, part of whose fibers pass in the same direction (Fig. 240). The rotatores are composed of the rofatores longi and breves. They are small, flat, and partly tendinous muscles which lie immediately upon the vertebral arches throughout the entire spinal column, but are chiefly developed in the thoracic region. The rofatores breves (Fig. 240) are almost horizontal and pass from the transverse process of one vertebra to the root of the spinous process of the vertebra next above; the rotatores longi (Fig. 240) extend over one or sometimes 154 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. two vertebrze before inserting into the roots of the spinous processes, their fibers having a course parallel to that of the multifidus. All of the long muscles of the back are supplied by the posterior divisions of the spinal nerves (cervical, thoracic, lumbar, and sacral). The majority of the long muscles of the back have the same functions. If the muscles of the two sides act together, they hold the trunk upright, extend the vertebral column and the head, and bend the head and vertebral column back- ward. During unilateral action they bend or rotate the vertebral column toward the contracting side. The strongest action upon the head is exerted by the two semispinales capitis; when they act together, they pull the head backward, but when they act singly they rotate the head so that the face is drawn toward the opposite side, and consequently in the opposite direction to that in which it is turned by the splenius capitis. THE SHORT MUSCLES OF THE BACK. The short muscles of the back are divided into two groups: those which are found through- out the entire flexible vertebral column and those which are situated between the axis and the ee Interiransversarii laterales Intertransversarii mediales ~_ Fic. 244.—Diagram of the lumbar interspinales and intertransversarii. atlas. The first group is composed of two further subdivisions: the interspinales, between the spinous processes of the vertebra; and the intertransversarii, between the transverse processes. The second group is also designated as the short muscles of the neck. The interspinales (Figs. 241, 243, and 244) are small muscles which are well developed only in the cervical region and may be entirely wanting throughout the thoracic vertebral column. They are connected with the interspinous ligaments and pass from the spinous process of one THE MUSCLES OF THE BACK. 15 in vertebra to that of the next lower one, and in the bifid spinous processes of the cervical vertebra they form paired structures. Like the majority of the muscles of the back, they do not extend beyond the spinous process of the epistropheus (axis). The intertransversarii (Figs. 243 and 244) are small, short, paired muscles which connect the transverse processes of neighboring vertebra. They are double upon both sides and are well developed both in the cervical and in the lumbar vertebral column. They may be entirely absent from the thoracic column. In the cervical region infertransversarii anteriores and posteriores (Fig. 243), which run between the anterior and posterior tubercles of the transverse processes, are differentiated. Both muscles are about equally developed; the anterior ones are situated in the anterior cervical rather than in the nuchal region. The intertransversarii of the lumbar region are composed of the wider and stronger inter- transversarii laterales, running between the transverse processes, and the narrower and weaker intertransversarii mediales, which extend between the accessory and mammillary processes (Fig. 244). As regards their function and innervation, the interspinales and the intertransversarii resemble the long muscle of the back. THE SHORT MUSCLES OF THE NECK. The short muscles of the neck (Figs. 241 and 259) are the rectus capitis posterior major, the rectus capitis posterior minor, the rectus capitis lateralis, the obliquus capitis superior, and the obliquus capitis injerior. The rectus capitis posterior major (Fig. 241) arises by a short tendon from the spinous process of the axis, runs upward and outward, becoming much broader, and inserts into the middle portion of the inferior nuchal line of the occipital bone. The rectus capitis posterior minor (Fig. 241) is considerably weaker than the major. It is a small triangular muscle which arises by a short tendon from the posterior tubercle of the atlas to the inner side of and partly beneath the rectus major. It runs to the inner third of the inferior nuchal line of the occipital bone. The rectus capitis lateralis (Fig. 259) arises from the transverse process of the atlas and inserts into the jugular process of the occipital bone. It represents the uppermost intertrans- versarius. The obliquus capitis superior (Fig. 241) also arises from the transverse process of the atlas, and runs to the outer third of the inferior nuchal line of the occipital bone, where its tendin- ous insertion partly covers the rectus capitis posterior major. The obliquus capitis inferior (Fig. 241) is a rather strong and fleshy muscle which runs from the spinous process of the epistropheus (axis) to the transverse process of the atlas. It is thick in the middle and becomes narrower toward its origin and insertion. The short muscles of the neck are supplied by the posterior division of the first cervical nerve (suboccipital nerve). The function of the short muscles of the neck practically consists of a rotation or extension of the head, dependent upon whether they act upon one or both sides. The rectus minor can only extend the head (nodding movement); the rectus lateralis inclines the head to one side; the obliquus inferior and the rectus major rotate the head in the same direction and are opposed by the obliquus superior. 156 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 245.—Superficial and second layers of the abdominal and pectoral muscles seen from in front. On the right side the pectoralis major and the obliquus abdominis externus have been removed. Between the rectus capitis posterior major and the obliquus capitis superior and inferior is situated a small triangle (the suboccipital triangle) in which is exposed the posterior arch of the atlas, crossed by the vertebral artery. THE FASCIZ OF THE BACK. In the dorsal region there are but two fasciz worthy of note, the Jwmbodorsal fascia and the nuchal fascia. ‘The upper layer of the flat muscles of the back is covered only by the general superficial fascia. The lumbodorsal fascia (Figs. 236 to 238) is composed of two layers, the strong posterior layer, which is superficially situated in the back and forms the aponeurosis of the latissimus and the serratus posterior inferior, and the anterior or deep layer, which is developed only in the lumbar region, where the long muscles of the back are included between the two layers. The posterior layer (Figs. 236 and 238) covers the sacrospinalis from behind and extends above the uppermost portion of the latissimus to the inferior margin of the aponeurosis of the serratus posterior superior. Although the fascia becomes considerably thinner after it ceases to be the aponeurosis of the latissimus, it usually still contains distinct tendinous slips. In the thoracic region the posterior layer is attached laterally to the angles of the ribs, and is covered by the trapezius and by the rhomboidei. The anterior layer (Fig. 237) runs from the inner lip of the crest of the ilium to the twelfth rib, and is attached internally to the transverse processes of the lumbar vertebra. Its upper margin forms a firmer tendinous band which passes from the transverse process of the first lumbar vertebra to the twelfth rib and is known as the /umbocostal (external arcuate) ligament (Fig. 251). The anterior layer is situated between the sacrospinalis and the quadratus lumborum, and at the outer margin of the sacrospinalis the two layers unite and give origin to several of the abdominal muscles. The thin nuchal fascia is situated beneath the trapezius and also partly beneath the rhom- boidei. It is continuous below with the upper portion of the lumbodorsal fascia and externally with the fascia of the neck, and the fascize of the two sides are connected in the median line with the nuchal ligament. [The trunk musculature is derived from the trunk myotomes of the embryo and is clearly divisible into two portions: (1) the dorsal trunk musculature, derived from the dorsal portions of the myotomes and supplied by the dorsal (posterior) branches of the spinal nerves; and (2) the ventral trunk musculature, developed from the ventral portions of the trunk myotomes and supplied by the ventral branches of the spinal nerves. When considered from this standpoint, the muscles of the back as arranged above clearly form a somewhat hetero- geneous group. The flat muscles are for the most part supplied by ventral branches of the spinal nerves or, in the case of the trapezius, by a cranial nerve, a fact which at once distinguishes them from the long and short muscles together with the splenii, which form the true dorsal musculature. The majority of the flat muscles are in reality muscles of the upper limb and the trapezius is primarily part of the cranial musculature; they will be considered later in con- nection with the other muscles of their groups. So far as the true dorsal musculature is concerned, comparative anatomy has shown that it is composed of two parallel groups of muscles, a lateral one, which consists of muscles primarily passing from the transverse processes to the ribs, and hence is termed the transversocostal group, and a more median one, whose muscles pass from the transverse to the _ Subclavius AA ao 2: Axillary vessels a = ---Latissimus dorsi =---Serratus anterior Obliquas abdominis \ > externus S Sheath of Ss reclus © = abdominis— ».-4 “ ” (agterior Umbilicus layer) ~ Intercrural fibres ~ Subcutaneous Cremaster--4e—_—_— inguinal ring. Reflected inguinal lig. C4 - By, 5 "| ~ Spermatic cord. _ Superior pillar. Fundiform lig. of penis Inferior pillar. Fig. 245. THE ABDOMINAL MUSCLES. 157 spinous processes, and which has been termed the fransverso-spinal group. The constitution of the two groups is as follows: Transverso-costal:—Sacrospinalis, iliocostalis, longissimus, and splenius. Transverso-spinal:—Spinalis, semispinalis, multifidus, rotatores, interspinales, inter-transversarii posteriores and laterales, rectus capitis posterior major, rectus capitis posterior minor, rectus capitis lateralis, obliquus capitis superior, and obliquus capitis inferior —Eb.) THE ABDOMINAL MUSCLES. The abdominal muscles (Figs. 245 to 250) form the anterior, the lateral, and a portion of the posterior abdominal wall, and extend from the lower margin of the thorax to the upper margin of the pelvis. They are subdivided into the anterior abdominal, of which three are flat muscles and one a straight muscle, and the posterior abdominal, the quadratus lumborum. THE ANTERIOR ABDOMINAL MUSCLES. THE FLAT ABDOMINAL MUSCLES. The flat abdominal muscles (Figs. 245 to 250) include the obliquus externus, the obliquus abdominis internus, and the transversus abdominis; they are arranged in three layers and form the lateral and a portion of the anterior abdominal wall. According to the direction of their fibers, the two oblique muscles may be regarded as the direct continuations of the inter- costales, the obliquus internus, in particular, being directly continuous with the lower intercostal muscles. The obliquus abdominis externus (Figs. 245 to 249) isa broad flat muscle which is aponeu- rotic anteriorly and markedly so in its anterior inferior portion. It is situated in the lateral pectoral, the hypochondriac, the epigastric, the mesogastric (lateral abdominal and umbilical), and the hypogastric (inguinal and pubic) regions. It arises by eight fleshy serrations from the eight (fifth to twelfth) lower ribs, the upper five serrations interdigitating with the lower ones of the serratus anterior, the lower three with those of the latissimus dorsi. The majority of the fibers of the muscle, like those of the intercostales externi, run from above downward and from without inward; the superior fibers, however, pass somewhat horizontally, while the inferior ones approach a vertical direction. The fibers coming from the lower ribs have an extensive fleshy insertion into the outer lip of the crest of the ilium, extending anteriorly to the anterior superior spine and posteriorly almost to the outer margin of the latissimus dorsi. The remainder of the insertion is aponeurotic and passes to the inguinal (Poupart’s) ligament, the greater portion of which is formed by the tendinous fasciculi of the muscle (see page 163), and to the anterior layer of the sheath of the rectus, by means of which it is continued to the linea alba. Almost the entire anterior abdominal surface is consequently aponeurotic; especially in the lower abdominal region the muscle fibers commence quite at the side. The obliquus abdominis externus is in relation superiorly with the abdominal portion of the pectoralis major, externally with the serratus anterior, postero-externally with the latissimus — dorsi, with which it forms the lumbar (Petit’s) triangle (see page 147), and inferiorly with the I 58 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 247.—The superficial layer of the abdominal muscles and the serratus anterior seen from the left side. The pectoralis major and minor and the inner portion of the clavicle have been removed and the arm has been drawn backward. iliac crest opposite to the gluteeus medius. In the region of the symphysis pubis the tendinous fibers of the aponeurosis form an opening by bridging over the space between the pubic spine (the insertion of the inguinal ligament) and the upper margin of the symphysis. In this manner Obliquus abdominis externus Muscle surface A poneurosis Linea alba BENS PMs, Va fae Anterior superior spine of ilinm = Inguinal ligament Intercrural fibers Superior pillar~ wv l p ~ Acetabulum Subcutaneous inguinal ~ ring Inferior pillar (inguinal~ ligament) a | Reflected inguinal lig. Symphysis pubis Fic. 246.—Diagram of the subcutaneous inguinal ring. On the right only a portion of the aponeurosis of the obliquus abdominis is represented. there is formed a triangle, the outer angle of which is directed upward and outward, and which constitutes the subcutaneous inguinal (external abdominal) ring (Figs. 245 and 246). The margins of the ring are formed by the aponeurosis of the obliquus abdominis externus, and are known as the superior crus or pillar and the inferior crus or pillar of the ring. The upper and outer angle of this triangular slit in the aponeurosis of the external oblique muscle is rounded off by fibers which arise from the region of the inguinal ligament and are Clavicle x Omohyoid Scalenus medius ‘ AN Sternohyoid + Sternothyreoid Scalenus anterior-— ’ Inferior angle of scapula THE ABDOMINAL MUS¢ situated superficially and in front of the aponeurosis itst (intercolumnar) fibers or the anterior crus or pillar (Figs. 245 a! rounded off by fibs rs of variable dev lopm« nt whi h origi ligament to the pubic spine and pass toward the linea fibers are known as the reflected inguinal (triangular) 11 Fic. 245 Transver tion of th anterior ibdomina!l wall a ta Sheath of rectus abdomini interior layer) 1¢ Fic. 240.—Transverse tion of the anterior abdominal wall midwa of Colles or the posterior crus (Figs. 245 and 246). Asa the ligament, the ring becomes irregularly quadrangular It is the anterior extremity of a canal, the inguinal the abdominal walls, and transmits the spermatic cord in the uterus in the female. (For a more detailed account of the inguinal canal the reader is 1 anatomy and to the section upon splanchnolog) passes obliquely through nd the round ligament of the -OKS and atlases of topographic 160 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 250.—The deeper layers of the abdominal muscles. On the left side the anterior layer of the sheath of the rectus abdominis and the obliquus abdominis externus have been removed; on the right side, in addition, the rectus abdominis, the pyramidalis, and the obliquus abdominis internus. The external intercostal ligaments have been removed on the left side. The obliquus abdominis internus (Figs. 245, 248 to 250), like the externus, is a decidedly flat muscle. With the exception of the small area in the lumbar triangle it is completely covered by the obliquus externus. It arises from almost the entire length of the middle lip of the crest of the ilium, extending anteriorly as far as the anterior superior spine, from the junction of the two layers of the lumbodorsal fascia (see page 156), and from the outer two-thirds of the inguinal ligament. The direction of the fibers of the upper portion of the muscle is similar to that of the intercostales interni (from without inward and from below upward); the middle fibers are less oblique, and the lower ones are horizontal, those of the lower third even passing slightly from without inward and from above downward, like those of the obliquus externus. The posterior fibers coming from the lumbar fascia have fleshy insertions into the lower borders of the three lower ribs. The long fibers coming from the iliac crest, as well as the hori- zontal and descending fasciculi from the inguinal ligament, pass into the sheath of the rectus, the two layers of which are formed by the aponeurosis of the obliquus internus (Fig. 248). The muscular portion of the obliquus internus is broader than that of the externus and consequently approaches much more closely to the sheath of the rectus in the anterior abdominal wall, especially in its lower portion (Fig. 249). A variable number of the inferior fibers of the obliquus internus accompany the spermatic cord, as the cremaster (Figs. 245 and 250), as far as the testicle, and consequently pass through the external abdominal ring as flat isolated fasciculi, and in the female a few fibers of the muscle are similarly continued upon the round ligament of the uterus. The transversus abdominis (Figs. 248 to 250) is a flat, rather thin, and largely aponeurotic muscle which is completely covered by the obliquus internus. It arises by flat muscular serrations from the inner surface of the six lower ribs and from the cartilages of the seventh to the tenth, interdigitating with the serrations of origin of the diaphragm (see page 164). It also arises by an aponeurosis from the entire length of the junction of the two layers of the lumbodorsal fascia, from the internal lip of the crest of the ilium, and from the outer third of the inguinal ligament. The fibers pass almost transversely and are attached to the aponeurotic insertion in a curved line, the semilunar line (line of Spigelius) (Fig. 250), in such a manner that the uppermost fibers coming from the ribs almost approach each other in the median line, the middle ones become aponeurotic at quite a distance from this location, and the inferior fasciculi remain muscular for a somewhat greater distance. The upper two-thirds of the aponeurosis of the transversus, together with that of the internus, form the posterior layer of the sheath of the rectus (Fig. 248); the lower third together with the aponeuroses of the obliquus internus and externus, forms the anterior layer of the sheath (Fig. 249). Py External intercostal ligts. j - > ‘ eee SA , : ¢ & f SS - Se Sternal . MO mem- Rib IV bran¢ Intercostales interns i Serratus anterior Intercostales externi 7 Sheath of & us ab- | @ !dominis | (posterior ; layer) s Semilunar lin Obliquus abdominis internus Semicircular line Obliguus abdo- minis externus Inguinal lig. Cremaster x Cremaster ee ot" \ 4 i ; - + i 6 ¢ 1 4 _ < « rs ” > a - yo : a) ES THE ABDOMINAL MUSCLES. 161 THE STRAIGHT ABDOMINAL MUSCLE, RECTUS ABDOMINIS. The rectus abdominis (Figs. 248 to 250) is a flat, broad, and rather thick muscle. lt arises (Fig. 250) broadly by flat muscular serrations from the cartilages of the fifth to the seventh ribs and from the xiphoid process, and its fibers pass almost vertically downward just to either side of the median line. The muscle becomes somewhat narrower as it descends and is inserted by a much narrower tendon into the upper border of the pubis between the pubic tubercle and the symphysis, a portion of the tendinous fasciculi of the muscles of the two sides interlacing in front of the pubic symphysis. The rectus is characterized by possessing several narrow, transverse, slightly curved or dentate tendinous intersections, the /endinous inscriplions (transverse lines) (Fig. 250), which traverse a portion or the entire width of the muscle, but do not usually extend throughout its thickness. The number varies between three and four. The uppermost one lies immediately below the origin of the muscle in the region of the costal arch and is sometimes developed only in the inner half of the muscle; the third is situated at the level of the umbilicus or somewhat above it; and the second is about midway between the first and the third. A fourth intersection is inconstant, but, when present, is below the umbilicus and usually traverses only the outer half of the muscle. In the vicinity of the tendinous intersections the muscle is adherent to the anterior layer of its sheath. Instead of being surrounded by fascia, the rectus is inclosed by the aponeurotic layers of its sheath (Figs. 245, 247 to 250), which consists of an anterior and a posterior layer. Only the anterior layer covers the muscle throughout; the posterior layer forms a sheath for only the upper two-thirds of the muscle (Figs. 248 and 249). At the junction of the middle with the lower third of the length of the muscle (or even somewhat higher) the posterior layer of the rectus sheath abruptly ceases in the shape of a slightly curved line, the semicircular line (line oj Douglas) (Fig. 250), and below this line, the muscle is in immediate relation posteriorly with the transversalis fascia (see page 163). The layers of the sheath are formed from the flat abdominal muscles (Figs. 248 and 249) in such a way that the aponeurosis of the obliquus internus splits into two layers in the upper two- thirds of the sheath, one of which forms the anterior layer and the other the posterior; in the lower third of the rectus, however, the aponeurosis of the obliquus internus forms only the anterior layer. The aponeurosis of the obliquus externus passes into the anterior layer; the upper two- thirds of that of the transversus goes to the posterior layer, and the lower third to the anterior layer. At the inner margin of the rectus the two layers of the sheath unite with each other and with the corresponding layers of the opposite side to form a thick tendinous strip, the /inea alba (Fig. 245), which extends between the xiphoid process and the sternum. The linea alba usually possesses a special tensor muscle in the shape of the inconstant pyra- midalis (Fig.250). This is a triangular muscle arising broadly from the tendon of insertion of the rectus abdominis and passing obliquely inward to be inserted into the lower portion of the inea_alba. 162 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The rectus and pyramidalis, like the other muscles of the anterior abdominal wall, are innervated by branches of the lower intercostal nerves; the flat abdominal muscles also receive branches from the iliohypogastric and the ilio- inguinal nerves from the lumbar plexus. The cremaster muscle is supplied by the external spermatic nerve (the genital branch of the genitocrural nerve). When all the anterior abdominal muscles act together their function is to diminish the size of the abdominal cavity and to compress the abdominal contents, the increased intra-abdominal] tension aiding in the evacuation of the contents of the intestines, of the uterus, and possibly also of the urinary bladder. With the exception of the transversus abdominis, these muscles also draw the thorax downward, the rectus directly downward, and the obliqui, when acting separately, toward the side of the contracting muscle. When the thorax is fixed, the anterior abdominal muscles and particularly the rectus, raise the pelvis. THE POSTERIOR ABDOMINAL MUSCLE. The quadratus lumborum (Figs. 251 and 254) is a flattened, rather thick, and approxi- mately quadrilateral muscle which forms a portion of the posterior abdominal wall. It extends Thoracic vertebra XII —— C Lumbar vertebra I .— Lumbar vertebra V .-- Tliolumbar ligament £G. 251.—The quadratus lumborum seen from the side and somewhat from behind (diagrammatic). between the crest of the ilium and the twelfth rib, and consists of two incompletely separated layers, a posterior and an anterior. The posterior portion (Fig. 251) arises by aponeurotic fibers from “Ae ; — =. a THE ABDOMINAL MUSCLES. 163 the posterior part of the inner lip of the crest of the ilium and from the iliolumbar ligament and runs to the inner half of the lower border of the twelfth rib and to the transverse processes of the upper four lumbar vertebra. The anterior portion of the muscle arises from the transverse processes of the lower and middle lumbar vertebri, the fibers intimately interlacing with those of the posterior portion, and inserts into the transverse process of the first lumbar vertebra and into the inner half of the last rib. The inner half of the quadratus lumborum is placed beneath (posterior to) the psoas major, and it is situated in front of the anterior layer of the lumbodorsal fascia, which separates it from the sacrospinalis. The lateral lumbocostal arch (external arcuate ligament) of the diaphragm bridges over the insertion of the muscle into the twelfth rib. To the outer side of the muscle there is visible the aponeurotic origin of the transversus abdominis from the lumbodorsal fascia, and at the crest of the ilium it borders upon the iliacus. The quadratus lumborum is supplied by muscular branches from the lumbar plexus. It draws the last rib down- ward and bends the vertebral column toward the side. THE ABDOMINAL FASCL®. The superficial layer of the flat abdominal muscles is covered only by the general su perjicial jascia (Figs. 248 and 249), which is, however, well developed in the lower portion of the abdomen in the region of the subcutaneous inguinal ring, where it forms what is known as Scarpa’s jascia. From this situation it extends downward upon the thigh and also envelops the spermatic cord as the cremasteric jascia. The sheath of the rectus muscle serves as its fascia. The inner surface of the abdominal musculature, 7.¢., the inner surface of the transversus abdominis and the posterior surface of the posterior layer of the sheath of the rectus, is lined by the ‘ransversalis jascia, which also covers the anterior surface of the quadratus lumborum and is especially strong over that muscle. It is rather firmly adherent to the aponeurosis of the trans- versus and to the posterior layer of the sheath of the rectus; below the semicircular line it is frequently very thin and forms the only posterior covering of the rectus abdominis (see page 161 and Fig. 249). Above the symphysis, it is connected with the so-called adminiculum linee albe (see below), and at the inguinal (Poupart’s) ligament, with the posterior surface of which it is adherent, it becomes continuous with the iliac fascia (see page 231). Superiorly the fascia gradually disappears upon the lower surface of the diaphragm. The Jinea alba (Figs. 245 and 248) is formed by the union of the aponeuroses of the flat abdominal muscles in the median line of the abdomen. It is broader above than below the umbilicus and, at the umbilicus itself, it is adherent to the integument. At its insertion into the upper margin of the symphyseal cartilage, its posterior surface is reinforced by a triangular fibrous _ expansion, sometimes containing muscle fibers, which passes upward from the superior pubic _ ligament and is known as the adminiculum linee alba. The inguinal ligament (Pou part's ligament) (Figs. 208 to 210) is also formed by the aponeu- roses and fascie of the abdomen. It extends as a strong tendinous band from the anterior uperior spine of the ilium to the spine of the pubis, some of its fibers radiating at its insertion o the inner extremity of the crest of the pubis and forming an almost horizontal triangular © : : se 164 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 252.—The diaphragm and the muscles of the posterior abdominal wall. The anterior abdominal wall and the abdominal viscera have been removed; the thorax has been bent backward so that the lumbar vertebre are strongly convex forward. ligament, the /acunar ligament (Gimbernat’s ligament) (Figs. 212 and 213), which is also con- nected with radiating fibers of the fascia of the thigh (see page 231). The reflected inguinal ligament (triangular ligament) (Fig. 245) is also formed by radiating fibers from the inguinal ligament, which pass to the posterior surface of the anterior layer of the sheath of the rectus (see page 159). The inguinal ligament gives origin not only to the flat abdominal muscles, but it also furnishes attachment to the fasciz of the abdomen and thigh (see page 231), and the deeper layers of the integument are also adherent to it. | [The ventral portions of the trunk myotomes during their development undergo a considerable amount of differ- entiation, forming a number of muscle groups. From each myotome a portion is cut off which comes to lie ventral to the vertebre or ribs, forming what is termed the hyposkeletal group of muscles. Similarly the ventral edges of the myo- tomes are separated to form band-like muscles, whose fibers are directed longitudinally and which are situated immediately adjacent to the mid-ventral line. These constitute what is termed the rectus group. And, finally, the intervening portions of the myotomes divide tangentially into three layers, whose fibers assume an oblique or transverse direction and which constitute what is known as the oblique group of muscles. The abdominal muscles are referable to these groups as follows: Hyposkeletal: Psoas major and psoas minor (see p. 210). Rectus: Rectus abdominis and pyramidalis. Oblique: Obliquus abdominis externus, obliquus abdominis internus, transversus abdominis, and quadratus lumborum. It is also probable that the intertransversarii laterales of the lumbar region are properly referable to the oblique group.—ED.] THE DIAPHRAGM. The diaphragm (Fig. 252) is a single independent muscle, which, from a topographical standpoint, is best considered with the abdominal muscles. Its shape differs from that of all the other skeletal muscles, in that it isa thin and markedly dome-shaped muscle, which is stretched across the inferior aperture of the thorax in such a way that it is convex toward the thorax and concave toward the abdomen. It consists of a central tendinous portion, the central tendon, and of a peripherial muscular portion. The muscular fasciculi of the diaphragm are subdivided according to their origin into three parts, which are designated the sternal portion, the costal portion, and the lumbar portion, and of these the lumbar portion is the strongest and the sternal portion by far the weakest. The fibers of all three portions are inserted into the margins of the central tendon. The sternal portion (Figs. 252 and 253) arises from the posterior surface of the xiphoid process and consists of but a few slender fasciculi. The costal portion (Figs. 252 and 253) arises by broad fleshy serrations from the inner surface of the six lower costal cartilages and from the eleventh and twelfth ribs, being also attached to the lumbocostal ligament in this situation, interdigitating with the transversus abdominis and with the transversus thoracis, following the curvature of the dome of the diaphragm and passing to the central tendon. The fibers of this portion, although weaker than those of the lumbar portion, Oesophageal openir esophageal opening Ocsophagus > Opening for the vena cava a TR FF ee ida Central TA tendon ZA & ws (Middle Diaphragie crus) ) Aortic : ‘ : ; ’ ; \ Limba) opening } pepe tiore f : Costal portion Niner 4, ; bo | tras) . ; (Outer mm Internal lumbo- 4 costal arch External lumbo- costal arch Transver- sus abdo- munis ba ; ) ur: 0-Bijratns f ; y, ; : dorsal J tom. if Lumbar & | ! Vivertcbrae en em THE ABDOMINAL MUSCLES. 165 cover a much larger area and form the main portion of the dome of the diaphragm. Between the individual serrations of origin there are sometimes linear intervals which contain no muscular tissue. The greater part of the /umbar portion (Fig. 252) comes from the bodies of the lumbar vertebre. Upon either side there may be distinguished three crura, or pillars, the crus mediale, intermedium, and laterale. The inner crura, sometimes termed simply the crura, are by far the strongest parts. They arise by tendinous fibers from the anterior surfaces of the third and fourth lumbar vertebrz and from the anterior longitudinal ligament and the intervertebral fibrocartilage between the two vertebri, and their outer margins soon become muscular while the inner ones remain tendinous. They may arise at different levels on the two sides, and when this is the case, it is the right crus which is always the longer of the two. The inner tendinous margins unite at the level of the twelfth thoracic vertebra or at that of the eleventh intervertebral fibrocartilage to form a pointed arch with tendinous margins, which is converted into a short canal by the anterior surfaces of the last thoracic and the first lumbar vertebra. The opening so formed gives passage to the aorta and is consequently designated the aortic opening (Fig. 252). The fibers of the entire lumbar portion, and especially those of the inner crura, pass at first almost vertically upward in front of the lumbar column, but just before their insertion into the central tendon they follow the curvature of the diaphragm, and in this situation they enclose a second opening in the diaphragm, which is elliptical, the long axis being vertically placed. The margins of the foramen are purely muscular and, as it gives passage to the esophagus, it is known as the esophageal opening. In its formation there usually occurs a decussation of the fibers of the two inner crura. The middle crura are considerably weaker and more slender than the inner ones. They arise by short tendons from the lateral surfaces of the body of the second lumbar vertebra and are at first separated from the inner crura by narrow slits, but before their insertion into the central tendon they become closely approximated to the muscular tissue of these. The ouler crura practically arise from the two tendinous lumbocostal arches, the infernal and external lumbocostal arches (arches oj Haller). The internal lumbocostal arch (internal arcuate ligament) passes from the body of the first lumbar vertebra to the tip of the transverse process of the same bone, crossing over the psoas major, while the external lumbocostal arch (external arcuate ligament) extends from the transverse process of the first lumbar vertebra to the twelfth rib and bridges over the quadratus lumborum. The slender fibers of the lateral lumbar portion of the diaphragm arise chiefly from the internal lumbocostal arch and also from the transverse process and lateral margin of the body of the first lumbar vertebra. Only a few fibers arise from the external lumbocostal arch and these may be entirely absent; they represent the connection between the lumbar and the costal portions of the diaphragm. The fasciculi of the outer crura are considerably shorter than those of the inner and middle ones. The central tendon (Fig. 252) is a fibrous layer which may be either reniform or shaped like a clover-leaf* and its fasciculi undergo manifold decussations. ‘The convex surface of the central tendon is situated anteriorly; the more marked concavity is placed posteriorly. In it there may be recognized a middle almost plane or but slightly curved portion, which is situated between the * The clover-leaf form is present when the central tendon extends toward the sternal portion. 106 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. two domes of the diaphragm, and two leaflets which are directed posteriorly. The left leaflet is the smaller and forms the left dome of the diaphragm; the right is larger and forms the right dome. At the base of the right leaflet near its posterior margin is situated a large irregular rounded opening, completely within the central tendon, which gives passage to the inferior vena cava and is designated the opening for the vena cava (quadrilateral joramen). The curvature of the diaphragm is not uniform, but there is a middle lower portion and two lateral domes which project markedly toward the thoracic cavity. The right dome is more capa- cious and extends to a higher level than the left; its highest point corresponds to the fourth, that of the left to the fifth intercostal space. Posteriorly the diaphragm (the lumbar portion) extends much lower than it does anteriorly. Its transverse is considerably larger than its sagittal diameter. The diaphragm possesses a series of foramina and spaces which give passage to vessels or nerves. These are: (1) The aortic opening, which is only partly formed by the diaphragm; (2) the esophageal opening, purely muscular and formed entirely by the diaphragm; (3) the opening jor the vena cava, situated entirely within the tendinous portion of the muscle; and (4) the slit-like spaces between the inner and middle crura and between the middle and external crura. The latter spaces give passage to the vena azygos, to the vena hemiazygos, and to the sympa- thetic and the splanchnic nerves, which are arranged ina variable manner. In addition to the aorta, the aortic opening also transmits the thoracic duct. The motor nerve of the diaphragm is the phrenic nerve from the cervical plexus. The diaphragm is the chief muscle of respiration. By the contraction of its fibers the domes of the diaphragm are drawn downward and the costal portions are drawn away from contact with the thoracic wall, so that the thoracic cavity is increased in size and the abdominal cavity is diminished. [The diaphragm, from the developmental standpoint, belongs to the cervical musculature, the muscular tissue which it contains being derived from the fourth (and to a certain extent from the third and fifth) cervical myotomes; the entire structure lying at one period of the development in the cervical region and later migrating downward to its final posi- tion between the thorax and abdomen. Hence it is that it is supplied by the phrenic nerve, which arises from the fourth (third to fifth) cervical nerve, and elongates in proportion as the diaphragm recedes toward its final position.—ED.] THE THORACIC MUSCLES. The muscles of the thorax (Figs. 245, 247, 253, and 254) are composed of two main groups: (1) Those which arise from the thoracic skeleton and insert into the skeleton of the upper extrem- ity; these are, consequently, really muscles of the extremity; and (2) the actual muscles of the thoracic wall, which are known as the intercostales. The first group is arranged in three layers which are not exactly superimposed. The first layer is formed by the pectoralis major, the second by the pectoralis minor and the subclavius, and the third by the serratus anterior. THE THORACIC MUSCLES OF THE UPPER EXTREMITY. The First Layer. The Pectoralis Major. The pectoralis major (Fig. 245) is a large, flat, thick muscle which is situated in the sternal, infraclavicular, mammary, axillary, and inframammary regions, its outer border forming the THE THORACIC MUSCLES. 167 anterior boundary of the axilla. The muscle is approximately triangular in shape, since its origin is very extensive and its insertion quite limited. It arises by three more or less separated portions, which are designated as the clavicular, the sternocostal, and the abdominal portions. The clavicular portion comes from the sternal half of the clavicle, the sternocostal portion from the anterior surface of the manubrium and the body of the sternum, with accessory digitations from the cartilages of the second to the sixth or seventh rib, while the abdominal portion, which is by far the smallest portion of the origin of the muscle, is a flat bundle which is attached to the lower margin of the sternocostal portion and arises by an aponeurosis from the anterior layer of the sheath of the rectus abdominis. Toward its insertion, the pectoralis major becomes considerably narrower but correspond- ingly thicker. Only the fibers of the clavicular portion and the upper fibers of the sternocostal portion pursue their original course, the greater number of the fibers of the sternocostal and abdominal portions passing from the anterior surface of the muscle toward the posterior surface of the tendon of insertion, so that an extensive twisting of the muscular fasciculi occurs in the outer portion of the muscle. The tendon is inserted (Fig. 269) into the entire length of the greater tubercular (anterior bicipital) ridge of the humerus. It consists of a weaker posterior aponeurotic layer and of a stronger anterior layer which becomes tendinous immediately before its actual insertion. Both layers are adherent below; the anterior is formed by the clavicular and by the upper part of the sternocostal portion, the lower by the bulk of the sternocostal and abdominal portions. Tendinous fasciculi from the insertion of the pectoralis major not infrequently bridge over the intertubercular (bicipital) groove and pass to the latissimus. These fibers sometimes contain muscle fibers (the muscle of Langer). The two pectorales arise from the anterior surface of the sternum in such a way that an area is left in the middle of the bone, narrow above and somewhat broader below, which contains no muscular tissue and in which is exposed the sternal membrane. In this situation the sternal head of the sternocleidomastoid (Fig. 255) (see page 171) borders immediately upon the pectoralis, and at the clavicle the origin of the pectoralis is situated exactly opposite to the clavicular head of the sternocleidomastoid. The anterior margin of the deltoid usually borders immediately upon the upper convex margin of the pectoralis major, a considerable space between the two muscles, known at the deltoideo pectoral triangle, usually existing only immediately below the clavicle, and the cephalic vein (Fig. 291) usually runs in the groove between the two muscles. At its lower margin the pectoralis major is continuous with the aponeurosis of the abdominal muscles (the sheath of the rectus), and its outer margin borders anteriorly upon the obliquus abdominis exter- nus and posteriorly upon the serratus anterior. The tendon of insertion is situated between the deltoid upon one side and the short head of the biceps and the coracobrachialis upon the other; in this situation it is separated from the latissimus by the intertubercular (bicipital) groove. An exceedingly inconstant muscle, the sferna/is, is quite rarely found upon the pectoralis major. It may be present upon one or both sides, is elongated, tendinous at its extremities, and is usually connected with the tendon of the sterno- cleidomastoid and the sheath of the rectus as well as with the pectoralis major, and usually represents a dislocated portion of the latter muscle. __ The pectoralis major is supplied by the anterior thoracic nerves. Together with the latissimus, it addacts the arm, and when it acts alone, it draws the arm anteriorly and toward the chest and, at the same time, rotates it internally. 168 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The Second Layer. The Pectoralis Minor and the Subclavius. The pectoralis minor (Fig. 245) is a flat triangular muscle which is completely concealed by the pectoralis major and, at its insertion, also by the deltoid. It arises by thin tendinous slips, frequently indistinctly separated, from the costochondral articulations of the second or third to the fifth ribs; it passes upward and outward and becomes markedly narrower toward its short tendinous insertion into the tip of the coracoid process. It covers the upper portion of the serratus anterior and bridges over the axillary vessels and the brachial plexus. The pectoralis minor, like the major, is supplied by the anterior thoracic nerves. It draws down the scapula, or, if the scapula be fixed, elevates the ribs, and it can also aid in fixing the scapula. The subclavius (Figs. 245 and 269) is a small, elongated, somewhat flattened muscle which arises by a tendon from the first costal cartilage alongside of the costoclavicular ligament, and is inserted into the under surface of the acromial end of the clavicle between the two portions of the coracoclavicular ligament (see page 120). In this situation there is usually a shallow groove in the bone. The nerve supplying the muscle is the subclavian from the brachial plexus. The muscle, by its contraction, fixes the clavicle in the sternoclavicular joint, and when the shoulder girdle is fixed the muscle elevates the first rib. The Third Layer. The Serratus Anterior. The serratus anterior (serratus magnus) (Figs. 247, 250) is covered in its upper portion by both pectoral muscles; its lower portion is situated in the lateral pectoral region and, immedi- ately below the pectoralis major, is covered only by the integument and fascia, the most inferior portion of the muscle, however, being placed beneath the anterior margin of the latissimus. The muscle is flat throughout, irregularly quadrilateral in shape, and its middle portion is very thin; it forms a muscular plate which is adapted to the curved surface of the thorax. It arises from the first to the ninth ribs by means of individual serrations, the lower five of which are distinctly separated and interdigitate with the serrations of the origin of the obliquus exter- nus abdominis. In the broad muscle sheet formed by the union of the serrations, three por- tions, distinctly differentiated by the direction of their fibers, may be recognized. The fibers of the upper and lower portions converge toward the insertion of the muscle, while those of the middle segment pass in the same direction but in a diverging manner. The upper converging portion (Fig. 258) arises as a rather strong muscular mass from the first and second ribs and from an intervening tendinous arch; it inserts into the superior angle of the scapula; the middle diverging portion is by far the thinnest and weakest part of the muscle and it arises from the second * and third ribs and diverges markedly to be inserted into the entire length of the vertebral border of the scapula; and the lower converging portion, which is the strongest part of the entire muscle, arises from the fifth to the ninth ribs and passes to the inferior angle of the scapula. The fibers of the lower portion are the longest and those of the upper portion are the shortest. The * The second rib consequently gives origin to two serrations. ee ee Os THE THORACIC MUSCLES. 169 muscle is fleshy throughout, with the exception of the insertion of the middle portion, which is sometimes aponeurotic. In order to reach the vertebral border of the scapula, the serratus anterior must pass back- ward for quite a distance along the thoracic wall, to which it is attached by loose connective tissue. When the muscle reaches the axillary border of the scapula it passes behind the sub- scapularis as far as the vertebral border of the bone and is separated from this muscle by a very loose connective tissue. Throughout its course it forms the inner wall of the axilla. The serratus anterior is supplied by the long thoracic nerve from the brachial plexus. When all the fibers of the muscle contract simultaneously, they fix the scapula, which is also drawn forward at the same time. The upper converging portion draws the superior scapular angle anteriorly; the lower portion pulls the inferior ’ angle forward and downward, and in the latter case the anterior angle, together with the glenoid cavity, ascends, as in elevation of the arm above the horizontal. When the scapula is fixed by the muscles of the back (trapezius, rhomboidei, levator scapulw), the serratus can also elevate the ribs and act as an accessory muscle of respiration. THE MUSCLES OF THE THORACIC WALLS. The muscles of the thoracic walls are the intercostales, the levatores costarum, the subcostales, and the ¢ransversus thoracis. The intercostales (Figs. 247, 250, 253, and 254) occupy the eleven intercostal spaces and are composed of two layers, an external, the infercostales externi, and an internal, the intercostales interni. The intercostales externi (Figs. 241, 247, 250, and 254) pass from above downward and from without inward between the borders of adjacent ribs; they are short flat muscles which fre- quently contain numerous tendinous fibers. They commence posteriorly in the region of the costal tubercles and extend anteriorly as far as the costochondral articulations, leaving the spaces between the costal cartilages free. In these spaces are found tendinous slips which run in the same direction as the fibers of the intercostales externi and extend to the margin of the sternum; they are called the exlernal intercostal ligaments (ligamenta coruscantia). The inlercostales interni (Figs. 250, 253, 254) run from above downward and from within out- ward between the borders of adjacent ribs, and they arise from the lower border of the upper rib of each intercostal space in such a manner that the costal groove is situated between the two muscular layers. They cross the intercostales externi at right angles and are covered by them except in the spaces between the costal cartilages. They extend anteriorly to the sternum or to the anterior extremities of the cartilages of the false ribs and end posteriorly at the costal angles. In the region of the costal cartilages they lie behind the external intercostal ligaments and those portions of them occurring in these situations are also termed the infercartilaginei. Between the posterior extremities of the ribs they are replaced by tendinous structures which are called the internal intercostal ligaments. The intercostales externi are covered almost throughout their entire extent by the thoracic, abdominal, and dorsal muscles (pectoralis major and minor, serratus anterior, obliquus abdominis externus, latissimus, serrati posteriores, rhomboidei), with the exception of a small area between the trapezius and the latissimus (Fig. 238). The levatores costarum (Fig. 243), from the course of their fibers, belong to the external intercostal muscles. They are situated in the dorsal thoracic region immediately beside the deeper layers of the long muscles of the back, are covered by the sacrospinalis (particularly by the — — 170 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 253.—The sternum, sternal ends of the clavicles and the ribs, with the intercostales, and the transversus thoracis, seen from behind. Fic. 254.—The fifth to the twelfth thoracic vertebre and the vertebral extremities of the corresponding ribs, with the intercostales and subcostales, seen from in front. On the left side the intercostal ligaments have been removed. iliocostalis), and are divided into the /evatores costarum breves and longi. ‘The levatores costarum breves (Fig. 243) arise from the transverse processes of the seventh cervical to the eleventh thoracic vertebre and insert into the rib next below between the tubercle and the angle. The /evatores costarum longi (Fig. 243) are found chiefly on the lower ribs and are distinguished from the breves in that they pass over one rib and insert into the second below near its costal angle. The levatores costarum become markedly broader toward their insertion and usually possess aponeu- roses. The subcostales (Fig. 254) are flat muscles which are not always present and vary greatly in their development. From the direction of their fibers they are to be grouped with the internal intercostal muscles, with the posterior portion of which they are continuous. They are found chiefly in the lower thoracic region and bridge over one or two ribs. They are usually partly tendinous both at their origin and at their insertion. The transversus thoracis (triangularis sterni) (Fig. 253) is a very thin flat muscle, the greater portion of which is tendinous, which arises by a broad aponeurosis from the posterior surfaces of the body and xiphoid process of the sternum and inserts by short broad tendinous slips into the inner surfaces of the cartilages of the second or third to the sixth ribs. The muscle is constant but very variable in its development. All the muscles of the intercostal series are supplied by the intercostal nerves which pass, together with the vasa intercostalia, between the internal and the external intercostal muscles. The intercostal muscles are important muscles of respiration. The great majority of them are muscles of inspiration, but the transversus thoracis and the subcostales probably play some part in expiration. THE PECTORAL FASCIA. The pectoral jascia lies upon the pectoralis major and the lower portion of the serratus ante- rior. The coracoclavicular fascia (costocoracoid membrane) is a much more pronounced layer which is situated beneath the pectoralis major and upon the pectoralis minor, covering the subclavius and the axillary vessels. It is particularly firm where it lies upon the subclavius and inserts into the lower surface of the clavicle. Internally it is inserted into the upper costal cartilages; eXter- nally it is continuous with the axillary fascia. [As was the case in the dorsal region, all the muscles referred to the thoracic region in the above description do not strictly belong to the thoracic musculature, but belong in part to the musculature of the upper extremity. This is true with regard to the muscles of the first three layers, only those described as the muscles of the thoracic walls being trunk muscles. These may be classified similarly to the abdominal muscles, but owing to the presence of a sternum in the thoracic region and to the lessened mobility of the thoracic portion of the spinal column due to the presence of fully developed ribs, no representatives of either the rectus or hyposkeletal groups occur in this region. The classification is consequently as follows: $9E “O1Y ‘€6¢ “Bly s7risooqnsy =| Bagapsas sUQuéT] MX 94 “IN Wa ‘ “HAWS pusayuy » SI]D{SQAIPUT 4 ee % paproashyjousa) X J aopys09 yoysoy - ~~ \ es Pepjoasdyy S Sajvjsord2}U] A aM X PPAR] | gt 7 \ ae g ssawudyy pogsoxsa;uy pousazuy X paprodyousag ‘ sawed} youlpnySuey sopsajpuy ‘Stuaupdy ayoypoy weeewer ee act yet ea " in we 4 . . * "5 P 4 ' _ 9 om THE MUSCLES OF THE NECK. 171 Hyposkeletal: wanting; Rectus: wanting; Oblique: Intercostales externi, intercostales interni, subcostales, transversus thoracis, and levatores costarum. In addition, two muscles described as belonging to the muscles of the back are probably members of the thoracic oblique group, namely, the serratus posterior superior and the serratus posterior injerior —ED.] THE MUSCLES OF THE NECK. The muscles of the neck (Figs. 256 to 259 and 267) include the platysma, the sternocleido- mastoid, the hyoid muscles, and the deep cervical muscles. The hyoid muscles are subdivided into the suprahyoid and the infrahyoid group; the deep cervical muscles are composed of an outer group, the scaleni, and of an inner group, the prevertebral muscles. The platysma (m. subcutaneus colli) (Figs. 260 and 267) is a thin, flat, quadrilateral muscle which is situated in the subcutaneous connective tissue in the neck, the upper portion of the chest and the lower portion of the face. It arises (Fig. 267) from the fascia over the pectoralis major and the deltoid at the level of the first or second rib, by separate fasciculi which are frequently separated by interspaces. At the level of the clavicle these fasciculi unite to form a broad, thin, compact muscular layer, which leaves uncovered the anterior cervical region but covers more or less extensively the lateral cervical, the sternocleidomastoid, the carotid, and submaxillary regions, and toward the chin the margins of the two muscles converge and meet each other in the mental region, frequently interlacing. Some of the fibers of the platysma are attached to the lower border of the mandible, while the rest pass over the mandible and appear upon the face, gradually disappearing partly upon the parotideo-masseteric fascia, and partly by intermingling with the risorius and triangularis by which they reach the angle of the mouth. The platysma is supplied by the cervical branch of the facial nerve. It wrinkles the skin in the cervical and upper thoracic regions and acts upon the angle of the mouth with the facial muscles. It can also increase the tension of the fascia in the facial, cervical, and thoracic regions. The sternocleidomastoideus (Figs. 238, 255, 256, 260, and 262) is a strong, broad, and thick muscle which is situated in the sternocleidomastoid region. It arises by two heads, a strong, thick, tendinous, sternal head from the anterior surface of the manubrium, and a short, tendinous, clavicular head from the sternal end of the clavicle. The sternal head passes over the sternoclavicular articulation and forms a muscular inter- space of varying size, the lesser supraclavicular jossa, by uniting with the clavicular head. It becomes much wider as it passes upward to assist in forming the thick belly of the muscle and partly conceals the clavicular portion. The sternocleidomastoid is inserted into the outer surface of the mastoid process of the tem- poral bone and into the outer half of the superior nuchal line, the anterior portion of the insertion being effected by a short, the posterior portion by a long tendon. The muscle passes obliquely through the neck from below upward and from within-outward. _ At its insertion it borders upon the trapezius (see page 145), with the anterior margin of which eS I72 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 255.—Superficial layer of the muscles of the neck, seen from in front. On the right side the sternohyoid, anterior belly of the digastric, and the submaxillary gland have been removed. Fic. 256.—Superficial layer of the muscles of the neck, seen from the left side. * = External carotid artery. it forms a triangle in which are situated the splenius capitis, the levator scapul, the scaleni, and the inferior belly of the omohyoid. The anterior margin of the muscle borders upon the infrahyoid muscles, bounds the carotid fossa (a deep muscular interspace containing the large vessels of the neck, 7. e., the common carotid artery and the internal jugular vein, and the vagus nerve), and crosses over and conceals the posterior belly of the digastric and stylohyoid. The upper part of its anterior margin is also in relation with the parotid gland. The sternocleidomastoid together with the trapezius is supplied by the accessory nerve. When both sternocleidomastoids act together, they draw the head downward and forward; when one muscle acts alone, it turns the head obliquely so that the face looks upward and toward the opposite side. e THE HYOID MUSCLES. The Infrahyoid Muscles. The infrahyoid muscles (Figs. 255, 256, and 258) are situated between the hyoid bone and the upper margin of the thorax, chiefly in the anterior cervical region, and represent a continu- ation of the rectus abdominis into the neck, being the remains of an originally single muscular layer which is interrupted in the thoracic region. Some of these muscles, like the rectus, have retained indications of their original segmental téndinous intersections. The group includes the sternohyoideus, the sternothyreoideus, the thyreohyoideus, and the omohyoideus. The sternohyoideus (Figs. 253, 255, 256, and 258) isa flat, long, and rather narrow muscle which is situated in the suprasternal, thyroid, laryngeal, subhyoid, and hyoid regions. It arises (Fig. 254) from the internal surface of the first costal cartilage and from the posterior surface of the manubrium and the capsule of the sternoclavicular articulation, and is covered at its origin by the sternal end of the clavicle and the sternal origin of the sternocleidomastoid. It passes upward at a slight distance from the median line, becoming somewhat narrower, and is inserted into the body of the hyoid bone. It not infrequently exhibits a feebly developed tendinous inscription. The sternothyreoideus (Figs. 253, 255, 256, and 258) is broader than the sternohyoid. Its origin is similar but more deeply placed (Fig. 254), sometimes extending downward as far as the second costal cartilage. The lower portion of the muscle is covered not only by the manubrium and the sternocleidomastoid, but also by the sternohyoid, although its outer and inner margins project beyond the latter muscle, and its middle and particularly its upper portion are also situated beneath the upper belly of the omohyoideus. It forms a broad flat muscle which covers the thyreoid gland, passes directly upward, so that only a narrow space is left in the median line between the two muscles of opposite sides, and is inserted into the oblique line of the thyreoid — cartilage. (For additional details see ‘“‘Splanchnology.”) In the space between the two muscles is situated a portion of the larynx, the thyreoid gland, and the trachea. a> 962 ‘sty J0UIJUM SnuaTDIS Smxaypd /oIy 204g , ({yjaq s0Lafur) snsprodyourr) 4 (Ayjaq 4ouajsod) snziujsvaig ‘guog ploApy] SNIPIOAYOHAYS snaprodyopA yy ’ (A}}aq 40LdajUD) SUIMSVIIC] Bip upiavpqus Seg prryomg (‘pq s0Lafay SNIpIOAY OU) . SIpIOAYy -OUdIS snaproa4sNy} apjndpgs “Ona “snap! ) . 5 LOJVAIT q PLOMAYJOUANS (Ajjaq sadns) snaplodyould 1ajDIS Sia plohyousygs (Ajjaqg ‘4adns) snaprodyougE Aiapiv Pyosvd UOUNO") snaprokyoasdy J ‘una avpnant yu] (Ajjaq 401493800) snaploayorays SMILLSOIIC] snaiajsosip fo uopu } ; ’ | ' (Ajjaq 4o1saquv) snnaysv5iq YS * THE MUSCLES OF THE NECK. 17 The thyreohyoideus (Figs. 255, 256, and 2sé sternothyreoid. Itis a flat 1 iscle, thi greater porti ol the omohyoid, and it passe Irom th ObDlgue iin I where it is inserted beside the sternohyoid into the late of the greater cornu. A fasciculus sometimes passes f and is known as the /Jevator glandule thyreoidee. The omohyoideus (Figs. 255, 256, and 258) is a long, flat, narrow muscl posed of two distin tly separated bellies. Thi in fe rior belly arises from the upper border of t} scapula between the inner angle and the notch metimes being also attached to t ‘ ~ i ( ‘ > erse ligament. lt is < i first \ verte d by the t { iS { ( cS. NS ( ( ] in : . . the greater suprac lavicular lossa as it passes tl r ost Ste I stoideus Beneath the latter it forms a flat intermediate tendon which is erent to the cervical f to the sheath of the great vessels of the neck. The su peri } tendon, appears at the anterior margin of t] stk S Atti) al A U) ine sterno- thyreoid and thyreohyoid, and is inserted immediately alongside of the sternohyoid into the lower border of the lateral portion of the hyoid bone in front of the thyreohvoid. ee Se eet ae ERE ea, ee en == ae shy . oh ee : ~} The infrahyoid muscles are supplied : \ ig so-called ansa hypoglossi. The thyreohyoid receives a special branch from the sam«x os) 174 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 258.—Deep layer of the muscles of the neck, seen from the left side. The anterior belly of the digastric, the mylohyoid, the sternocleidomastoid, and the sternal end of the clavicle har been removed. Fic. 259.—The deep muscles of the neck, seen from in front. On the right side the longus capitis has been drawn outward. The infrahyoid muscles depress the hyoid bone, the sternothyreoid draws down the larynx, and the thyreohyoic approximates the hyoid bone te the larynx. They also act as accessory muscles of deglutition, and, by its attachmen’ te the sheath of the great vessels, the omohyoid facilitates the return of blood through the internal jugular vein. z The Suprahyoid Muscles. The suprahyoid muscles (Figs. 255 to 258) lie between the hyoid bone and the mandible. They are the digastricus, the stylohyoideus, the mylohyoideus, and the geniohyoideus. a The digastricus (biventer mandibule) (Figs. 255, 256, and 258) is a typical two-belliec muscle with a distinct cylindrical intermediate tendon which is attached to the hyoid bone. The two bellies form an obtuse angle, open above, in which is situated the submaxillary salivary glan¢ The anterior belly is a fairly thick muscle which passes from the intermediate tendon, frequently receiving a few tendinous fibers directly from the hyoid bone, to the digastric fossa of the mandible where it is inserted by a short tendon. The posterior belly is longer but somewhat weaker th the anterior one. It arises from the mastoid notch of the temporal bone and passes with stylohyoideus to the hyoid region, where it becomes continuous with the intermediate tendon. The anterior belly of the digastric lies in the submental and mental regions, between the skit and the mylohyoid; the posterior belly is completely concealed at its origin by the sternocleide mastoid, and further anteriorly it separates the submaxillary region from the carotid fossa. When the hyoid bone is fixed, the anterior belly depresses the lower jaw and opens the mouth; the posterior | draws tne hyoid bone backward and upward and, together with the stylohyoid and the infrahyoid muscles, fixes the hyoi bone. The posterior belly is supplied by the facial nerve, the anterior belly by the mylohyoid nerve from the third divi of the trigeminus. The sigititvoldnun (Figs. 255, 256, and 258) arises by a tendon from the styloid process | the temporal bone and runs to the hyoid bone.as a flat rounded muscle above and almost paralle to the posterior belly of the digastric. Before its insertion into the bone it almost always divide into two slips, between which the intermediate tendon of the digastric passes. These slips hy av muscular attachments to the base of the greater cornu and to the posterior extremity of the be 04 of the hyoid bone. The action of the muscle is similar to that of the posterior belly of the digastric and it is also cuppliedil facial nerve. Between the infrahyoid muscles and the anterior border of the sternocleidomastoid there remains a d p bounded above by the posterior belly of the digastricus; this is the carotid fossa, and it contains the great ; and nerve of the neck (the common carotid artery, the internal jugular vein, and the vagus nerve). The lateral 1 of the pharynx forms its floor. The mylohyoideus (Figs. 256 to 258 and 265) is a peculiar broad, flat muscle whi i] situated in the submental and submaxillary regions and is partly covered by i anterior belly ¢ Bastlar portion of occipitals Stylohyoideus Digastricus (poster. belly) Rectus capitis lateralis Anter. tubercle of atlas Tendon of digastricus » Hyoid bone Thyreohyoideus THE MUSCLES OF THE NECK. 175 the digastric. The two muscles of opposite sides unite in the median line in a slightly tendinous mylohyoid raphe, and form a muscular layer which extends across the mandibular arch and constitutes the floor of the mouth. Each muscle arises (Fig. 257) by a short tendon from the mylohyoid line of the mandible, and the majority of the fibers run obliquely to the median raphe, some of them, however, passing to the upper border of the body of the hyoid bone. The muscle is supplied by the mylohyoid nerve from the third division of the trigeminus. During deglutition it elevates the entire floor of the mouth, together with the tongue; the hyoid bone is also drawn upward by the fibers inserted into it, and when the hyoid bone is fixed, the muscle depresses the lower jaw, assisting the digastric. The geniohyoideus (Figs. 257, 258, and 265) is a rather strong, slightly flattened muscle which is situated between the muscles of the tongue proper and the mylohyoid, the inner margins of the muscles of the two sides being in immediate contact. Each muscle has a tendinous origin from the mental spine of the mandible (Fig. 257), and becoming considerably broader as it passes backward, has a fleshy insertion into the anterior border and upper surface of the body of the hyoid bone. The geniohyoid is supplied by fibers from the first and second cervical nerves, which accompany the hypoglossal nerve, It draws the hyoid bone forward, or, when the hyoid bone is fixed, it depresses the lower jaw. Together with the infrahyoid and the posterior suprahyoid muscles, it fixes the hyoid bone. THE DEEP MUSCLES OF THE NECK. The Group of the Scaleni. The scaleni (Figs. 244, 247, 258, and 259) are’composed of three (rarely four) muscles which pass from the transverse processes of the cervical vertebr to the first and second ribs. Their origins are concealed by the sternocleidomastoid, but they are partly situated immediately beneath the skin in the lateral cervical region. The scalenus anterior (Figs. 247, 258, and 259) is a long muscle which is almost wholly covered by the sternocleidomastoid and partly so by the inferior belly of the omohyoid. _ It arises by tendinous slips from the anterior tubercles of the transverse processes of the fourth to the sixth cervical vertebra, and passes downward and forward to the first rib, becoming narrow and tendin- ous at its insertion into the scalene tubercle. The anterior surface of the muscle just above the - insertion is provided with an aponeurosis. ; The scalenus medius (Figs. 258 and 259) is longer and usually stronger than the anterior, with which it is closely related by its short tendons of origin. It arises from the anterior tubercles of all of the cervical vertebra and is situated to the outer side of and partly beneath the scalenus anterior. It is inserted by a broad short tendon into the outer surface of the first rib about a _ fingerbreadth to the outer side of the scalenus anterior. Between the insertions of the scalenus anterior and medius into the first rib there is a space which gives passage to the subclavian artery and to the greater part of the brachial plexus. ; The scalenus posterior (Figs. 244 and 259) is the smallest of the scaleni, and is frequently adherent to the medius, from which it is distinguishable only by its separate insertion. It arises the transverse processes of the fifth to the seventh cervical vertebra, is situated between the ? 176 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. scalenus medius and the levator scapul, and is inserted by a short tendon into the upper border of the second rib. Its insertion is covered by the upper digitations of the serratus anterior. There is occasionally present a small independent muscular fasciculus situated between the scalenus anterior and medius. It is known as the scalenus minimus, and is inserted into the first rib and also into the dome of the pleura. The scaleni receive their nerve-supply partly from the cervical plexus and partly (the scalenus posterior) from small special branches of the brachial plexus. They elevate the two upper ribs. THE PREVERTEBRAL CERVICAL MUSCLES. The muscles of the prevertebral group (Figs. 258 and 259) are situated to the inner side and above the scaleni, from which they are separated by the transverse processes of the cervical] vertebrae. ‘They are the longus colli, the longus capitis, and the rectus capitis anterior. The longus colli (Fig. 259) is a rather thin flat muscle which is situated between the cervical viscera and the bodies of the upper thoracic and of all of the cervical vertebra. Its upper and outer portion is covered by the longus capitis, and between the two muscles and to either side of the median line there is a space, the width of the little finger, in which may be seen the anterior longitudinal ligament of the vertebral column. The muscle has the form of a very obtuse-angled triangle, the obtuse angle being placed at the transverse process of the sixth cervical vertebra. It is composed of three portions, each of which constitutes a side of the triangle. The inner portion is the longest, and extends from the body of the third thoracic vertebra to the axis. It arises by tendinous slips from the bodies of the upper thoracic and the lower cervical vertebrae, and inserts, partly by muscular and partly by tendinous tissue, into the bodies of the upper cervical vertebra. The upper and outer portion arises by flat tendinous digitations from the anterior tubercles of the transverse processes of the upper cervical vertebra and is inserted into the anterior tubercle of the atlas, this portion being sometimes termed the longus atlantis, and also into the bodies of the underlying cervical vertebrz in common with the inner segment of the muscle. The lower and outer portion arises from the lateral surfaces of the bodies of the upper thoracic vertebre and is inserted by the tendinous slips into the transverse processes of the lower cervical vertebre. The longus capitis (rectus capitis anterior major) (Figs. 258 and 259) is a rather broad flat muscle the upper portion of which is somewhat thickened. It lies to the outer side of the longus colli and covers its upper and outer segment, and arises by distinctly separated tendinous digitations from the anterior tubercles of the transverse processes of the third to the sixth cervical vertebre. From these origins it passes upward and slightly inward, and is inserted into the lower surface of the basilar portion of the occipital bone. There is a distinct aponeu- rosis upon the anterior surface of the muscle somewhat above its middle. The longus colli and the longus capitis are supplied by special branches of the cervical plexus. They bend the — cervical vertebral column anteriorly, and, when they act unilaterally, turn the head toward the side of the contracting muscle. In the turning movement, the longus capitis and the upper and outer segment of the longus colli act together. i = ea 4 THE MUSCLES OF THE HEAD, 177 The rectus capitis anterior (minor) (Fig. 259) is a small muscle passing between the atlas and the occipital bone and is almost entirely concealed by the longus capitis. It arises from the base of the atlas and passes upward and inward behind the insertion of the longus capitis, to be inserted into the under surface of the basilar process of the occipital bone. Both the function and the innervation of this muscle are intimately connected with those of the preceding ones. THE FASCIZ OF THE NECK. In the neck two fascie may be distinguished: the cervical jascia and the prevertebral jascia. The cervical fascia is further subdivided into a superficial stronger and a deeper weaker layer, The superficial layer of the cervical jascia covers the sternohyoid, the sternothyreoid, the thyreohyoid, the anterior surface of the sternocleidomastoid, the inferior belly of the omohyoid, the posterior belly of the digastric, the stylohyoid, the submaxillary gland, and the carotid fossa; it is itself concealed by the platysma. This superficial layer is connected above with the parotideo- masseteric fascia, and also covers in the space between the posterior border of the sternocleido- . mastoid and the anterior border of the trapezius. The deep layer of the cervical jascia unites with the superficial layer at the anterior border of the sternocleidomastoid, so that in the middle of the neck but a single layer of fascia covers the larynx and the upper portion of the trachea. It covers the posterior surface of the sternocleido- mastoid, which is consequently ensheathed between the two layers, the posterior surface of the posterior belly of the digastric and of the stylohyoid, the floor of the carotid fossa and the scaleni. It is intimately adherent to the intermediate tendon of the omohyoid and behind the manubrium of the sternum it extends downward to the first rib, while posteriorly it is continuous with the nuchal fascia. The prevertebral fascia is a rather dense layer of fascia which covers the prevertebral muscles and the anterior surfaces of the cervical and of the upper thoracic vertebra. It is separated from the cervical viscera by loose connective tissue. relations, many of the muscles described above, such as the platysma, the sternocleidomastoid muscles, with the exception of the geniohyoid, belonging = the cranial musculature. The true cervical muscles, #. ¢., those derived from the cervical myotomes, may be classified as follows: Hyposkeletal: longus colli, longus capitis, and rectus ca pitis anterior, Rectus: sternohyoidetis, sternoth yreoideus, thyreohyoideus, and omoh yoideus. Oblique: scaleni (and probably also the intertransversaris anteriores). As has already been pointed out, the musculature of the diaphragm is also derived from the cervical myotomes and is probably to be regarded as a portion of the oblique group.—Ep.] — - ear a 4 178 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 260.—The superficial layer of the facial muscles and the neighboring muscles of the neck seen from the side and slightly from in front. Fic. 261.—The orbicularis oculi seen from behind. The muscle together with the integument has been removed; the lachrymal portion is represented in connection with the inner margin of the orbit. THE MUSCLES OF THE FACE AND OF THE SCALP. The cutaneous muscles of the face exhibit manifold peculiarities by which they are more or less differentiated from the ordinary skeletal muscles. They possess no fasciz, they exhibit but a slight degree of independence, and many of them are so combined and their fibers interlace to such an extent that it is often purely a matter of choice whether individual fasciculi are regarded as special muscles or as the heads of a larger muscle. The arrangement of the facial muscles into sphincters or muscles of closure is also characteristic. The group includes the epicranius as well as the muscles of the face proper. THE EPICRANIUS. The epicranius (Figs. 260, 262, and 264) consists of a middle aponeurosis which envelops the cranium, the galea aponeurotica, and of muscles which arise in the frontal and occipital regions and are inserted into the galea. This is thickest in the occipital region, becomes thinner toward the forehead and particularly toward the temples, and gradually loses.its aponeurotic character (especially in the temporal region). It is connected to the skin by fibrous connective-tissue fasciculi and separated from the cranial periosteum by loose areolar tissue. The frontalis is a very thin, broad, and flat muscle which is intimately adherent to the skin of the eyebrows. It has a broad origin above the supraorbital margin, extends over the vertical portion of the frontal bone, and is inserted into the galea aponeurotica in the upper portion of the forchead. It has also a slender origin, which varies in size, from the bony bridge of the nose; when strongly developed, it is known as the procerus (pyramidalis) nasi, but it is always immediately connected with the frontalis. The two frontales are separated in the median line by a narrow area containing no muscular tissue. The occipitalis is also a flat, broad, and an approximately quadrilateral muscle which arises on each side by short tendinous fibers from the highest nuchal line; it passes upward, and after a comparatively short course is inserted into the galea aponeurotica in the occipital region. The width of the muscle is much greater than its height, in contrast to the opposite condition in the frontalis. Like all the facial muscles, the frontalis and the occipitalis are supplied by the facial nerve. Both muscles are tensors of the galea aponeurotica. They pull the scalp forward or backward, and the frontalis wrinkles the skin of the forehead. A portion of the auricularis is also related to the galea aponeurotica. This muscle presents three portions, an auricularis anterior, superior, and posterior, and like almost all the facial muscles they are subject to great individual variations in the degree of their development. Lig. palpebrale mediale a: / Procerus =< Qua- : Occipitalis dratus j labii . super. <~— Transversus mentt Fig. 200. * . 2, 7 » ho Frontal bone , yy a = Lachrymal portion : Quadratus Angular head __ labis _ \Zygomatic head > “a superiorts \Jnfraorbital head’ om Maased Trapezius Zygomaticus x -2—— Splenius capitis Triangularis x v —_ Quadratus labii infer. Incisivus labii superioris iy Depressor septi Buccinator Triangularis | es THE MUSCLES OF THE FACE AND OF THE SCALP. 181 upward as far as the zygoma and covering the radiating fibers of the platysma in this situation. The lower portion of the muscle is connected with the platysma and frequently appears to be a direct continuation of some of the individual fasciculi of the latter muscle (Fig. 267). It is inserted into the labial musculature at the angle of the mouth immediately below the zygo- maticus major. The triangularis (/riangularis labii injerioris or depressor anguli oris) (Fig. 260) forms the superficial layer of the musculature of the lower lip. It is a flat triangular muscle, situated in the buccal, mental, and inferior labial regions, and arises broadly from the anterior extremity of the lower border of the body of the jaw. Its fibers are inserted into the labial musculature of _ the lower lip near the angle of the mouth, some of its superficial fasciculi passing to the opposite side in an arched manner to form a single subcutaneous muscle which is known as the fransversus menti (Fig. 260). The quadratus labii superioris, the zygomaticus, the risorius, and the triangularis form the superficial layer of the oral muscles and conceal the greater number of those which are now to be described. The caninus (ériangularis labii superioris or levator anguli oris) (Figs. 260, 262, and 264) arises from the canine fossa of the maxilla and passes into the musculature of the lip above the zygomaticus. It is a flattened elongated muscle and is almost entirely concealed by the over- lying quadratus labii superioris and zygomaticus. ; The quadratus labii inferioris (depressor labii injerioris) (Figs. 260, 262, and 264) is a flat quadrangular muscle, the posterior portion of which is covered by the triangularis. It arises : from the anterior extremity of the lower border of the jaw and passes to the orbicularis oris in : the lower lip. The incisivi (/abii superioris et injerioris) (Fig. 263) are small slender muscles which arise ; from the alveolar juga of the superior and inferior lateral incisors and pass directly into the _ musculature of the orbicularis oris. : The orbicularis oris (sphincter oris) (Figs. 262 and 263) is the muscle which surrounds the i mouth and forms the proper musculature of the lips. The fasciculi of the muscle run in quite _ different directions and, at the angles of the mouth and in both the upper and lower lips, are intimately connected with the fibers of both quadrati, the triangularis, the caninus, the risorius, 4 the zygomaticus, and the buccinator, some of the fibers of these muscles passing in the same direction as the fasciculi of the orbicularis oris. In addition to the fibers which encircle the mouth, 7 the orbicularis oris also possesses sagittal and vertical fasciculi; the latter form a small slender muscle, situated alongside of the median line of the upper lip, which is inserted into the cartilagin- ous nasal septum and is known as the depressor se pti (nasi) (Fig. 263). The mentalis (/evator menti or levator labii injerioris) (Figs. 262 to 264) is a short muscle situated in the mental region, which arises from the lower jaw near the alveolar jugum of the edian incisor. Some of the arching fibers unite with those of the muscle of the opposite side, ut the eo number are inserted into the integument of the chin. The origin of both my jaw, and situated immediately beneath the buccal mucous membrane. Only the Ped 182 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 264.—The deepest layer of the facial muscles and the temporalis. The caninus, the zygomatic arch, a portion of the zygomatic bone with the origin of the masseter and the temporal fascie have been removed. Fic. 265.—The two pterygoidei seen from the inner surface. The anterior portion of the skull has been divided in the sagittal plane, and the temporal bone in an oblique plane; the tongue and soft palate have been removed. anterior border of the muscle is superficial, passing into the orbicularis oris and the other muscles of the mouth. It is the»strongest muscle in the oral region. It arises from the buccinator ridge of the mandible, from the posterior extremity of the ‘ee: lar process of the maxilla, and from the pterygomandibular raphe. The pterygomandibular raphe (pterygomaxillary ligament) is embedded in the buceopharyngeal fascia (see page 184) and extends from the hamulus of the internal pterygoid plate to the posterior border of the alveolar portion of the mandible. It separates the buc-inator from the constrictor pharyngis superior (see “Splanchnology”’). At the angles of the mouth the fibers of the buccinator muscles are directly continuous with those of the orbicularis oris, while the posterior surfaces border immediately upon the oral mucous membrane. ‘The anterior portion of each muscle is covered by the risorius, the triangularis, the zygomaticus, and the caninus, while the posterior portion is situated beneath the masseter (see page 183), from which it is separated by a mass of fat, the buccal fat mass (Bichat’s jat mass). The buccinator is perforated by the parotid duct, and the small buccal glands rest directly upon the muscle. THE NASAL MUSCLES, The muscles of the nose are much less important than those of the mouth. The feebly developed nasalis (Figs. 262, 264, and 266) is composed of a ¢ransverse portion and an alar por- tion. ‘he transverse portion is a flat and very thin muscle which arises from the upper jaw and is adherent to the angular head of the quadratus labii superioris upon the bridge of the nose; it is united with its fellow of the opposite side by means of a thin aponeurosis termed the compressor narium. The alar portion comes from the alveolar jugum of the upper canine tooth and goes to the cartilage of the ala of the nose; its greater portion is covered by the quadratus labii superi- oris, although a small portion is also concealed by the orbicularis oris. The ala of the nose also receives constantly the insertion of a portion of the angular head of the quadratus labii superioris. All of the muscles of the face proper are supplied by the facial nerve. Their function is to produce the movements of expression, closure of the mouth, movements of the lips, and compression of the contents of the mouth (as, in blowing, the buccinator). THE MUSCLES OF MASTICATION. The muscles of mastication are composed of four strong separate muscles which are divided into two groups: the first group is formed by the masseter and the temporalis; the second by the two pterygoidet. The masseter (Fig. 262) is a thick, strong, and approximately quadrilateral muscle which Corrugator supercilii x Procerus GY ~Trapezius Splenius capitis Quadratus labii sup. x Zygomat icus x Triangularis = : r Quadratus labii inferioris . . Fig. 264. WMeniali. RR Hamulus of — a: 2). \\. plerygoid e Pterygoideus externus ~~ a ‘ Stylohyoideus, > ae Stylopharyngeus, = | AS Styloglossus » G V4 Styloid process Stylomandibular lig. Genioglossus x— Geniohyoideus x Digastricus Fig. : (Ant. belly) ea THE MUSCLES OF THE FACE AND OF THE SCALP. 183 is situated chiefly in the parotideo-masseteric and partly also in the zygomatic region. Its super- ficial portion arises by a broad aponeurosis from the lower border of the anterior and middle thirds of the zygoma, while the deep portion takes a short muscular origin from the lower border and the inner surface of the posterior part of the zygomatic arch. Its chief insertion is into the angle of the jaw and into the adjacent portions of the body and of the ramus, the deep portion being inserted into the ramus above the superficial portion, which conceals it. The aponeurosis covers more than half of the length of the muscle and usually penetrates its interior in the shape of individual serrations. The masseter is covered behind by the parotid gland, whose duct passes transversely across the muscle, and in front by the parotideo-masseteric fascia. Its anterior portion is also in relation with the uppermost portion of the risorius, which is still more superficial than the parotideo-masseteric fascia, with the zygomaticus, and partly with the zygomatic head of the quadratus labii superioris. Only the lower portion of the muscle is situated immediately beneath the fascia, the aponeurosis being usually covered by a layer of fatty tissue. It covers the insertion of the temporalis and is separated from the buccinator by the buccal jat mass (see page 182). The masseter is supplied by the masseteric branch of the third division of the trigeminus. It closes the mouth by bringing the lower jaw in contact with the upper. The temporalis (Fig. 264) is a broad strong muscle, rather flat in its upper portion, which covers the planum temporale and the temporal fossa. In the temporal region it is almost sub- cutaneous, and takes a muscular origin from the entire surface of the planum temporale below the inferior temporal line, partly from the anterior portion of the temporal fossa, and also from the overlying deep layer of the temporal fascia. The wide fasciculi of the muscle con- verge toward the coronoid process of the mandible, and in doing so become markedly tendi- nous upon the outer surface. They embrace the entire apex of the process and upon its inner surface extend downward as far as the base. The muscle is supplied by the deep temporal branches from the motor portion of the third division of the trigeminus. Its function is to close the mouth, moving, like the masseter, the lower toward the upper jaw. The pterygoideus externus (Figs. 265 and 266) is a triangular, fairly strong muscle _ which is situated in the infratemporal fossa between the temporalis and the pterygoideus inter- nus. It arises by two more or less distinctly separated heads: the larger and inferior from the outer surface of the outer plate of the pterygoid process, from the pyramidal process of the palate bone, and from the tuberosity of the maxilla; the smaller and superior one from the infratemporal crest and surface of the greater wing of the sphenoid bone. The two heads unite, the muscle becomes markedly narrower, and is inserted by a short tendon into the pterygoid fossa of the head of the mandible, some fibers passing also to the articular disc of the ‘emporomaxillary articulation. _ The pterygoideus internus (Figs. 265 and 266) is stronger than the externus, which con- 184 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 266.—The deep layers of the facial muscles, the buccinator, and the pterygoids, seen from the side. The lower portion of the temporalis together with the coronoid process of the mandible has been removed; the whole of the masseter is also removed and the parotid duct has been severed near its entrance into the buccinator. Fic. 267.—The left platysma, seen from the side. of the jaw, where it is inserted exactly opposite to the masseter. ‘The outer surface of the muscle is usually aponeurotic. [The pferygoideus internus is an elevator of the mandible, assisting the temporalis and masseter. The pterygoideus externus draws the condyle of the mandible and the articular disc forward upon the articular eminence; when the muscle of one side acts alone, it draws forward the mandibular condyle to which it is attached, the other one pivoting in the mandibular fossa, and the result being an apparently lateral movement of the mandible.—ED.] The muscles are supplied by the external and internal pterygoid nerves from the third division of the trigeminus. THE FASCIZ OF THE HEAD. The parotideo-masseteric fascia (Fig. 260) is the layer of fascia which passes over the parotid gland and the masseter muscle. At the zygoma it is connected with the temporal fascia, at the anterior margin of the masseter with the buccopharyngeal fascia, and at the angle of the jaw with the cervical fascia. The temporal jascia (Figs. 260 and 262) is the strongest fascia in the head ands in its lower portion divides into two layers, the superficial and the deep, which are separated by fatty tissue. The interspace between the two layers becomes larger as they descend, the superficial layer inserting into the anterior, the deep into the posterior border of the zygoma. The upper cir- cumference of the temporal fascia is connected with the galea aponeurotica. The anterior portion of the buccopharyngeal jascia lies upon the buccinator and is connected with the parotideo-masseteric fascia; the posterior portion is stronger, more tendinous, and covers the inner surface of the pterygoideus internus. In this posterior portion are embedded the pterygomandibular raphe (pterygomaxillary ligament) and the stylomandibular (stylomaxillary) ligament (see page 118). In this situation the fascia forms the postero-lateral wall of the oral cavity and the lateral wall of the pharynx. ae [The cranial musculature, considered from the developmental standpoint, includes several muscles in addition to those which are assigr o the head in the above description, since it is properly to be regarded as consisting of all the muscles supplied by the cranial nerves. Among these nerves there exist motor fibers of two different qualities: (1) lateral motor roots whose nuclei of origin may be regarded as occupying a position intermediate between the sensory nuclei and (2) the median motor roots, which correspond in all their essentials to the anterior roots of the spinal cord. The lateral motor roots, which occur in connection with the fifth, seventh, ninth, tenth, and eleventh nerves, are distributed to the muscles associated with the embryonic branchial arches, while the median motor roots are represented by the third, fourth, sixth, and twelfth nerves, and supply the muscles associated with the eyeball and tongue. In accordance with this difference of innervation, which is of great morphological importance, the cranial muscula- ture may be divided into two groups: (1) The myomeric muscles, supplied by median motor roots, and (2) the branchi- omeric muscles, supplied by lateral motor roots. The muscles belonging to the former group as well as certain of those belonging to the branchiomeric group, such as the muscles of the tympanum, palate, pharynx, and larynx, will be described and figured in connection with the regions to which they belong, but for the sake of completeness they will be included in the classification that follows. In the classification of the muscles of each group the individual nerve- supply may form the basis. ‘0% ‘B14 ‘002 ‘dl Y \ x Yul ngey smoapon?y fe y y y & Suan dun f yy i ea i ~~ ‘ SUINDUOIAZ Y se } : m y P ~ VFB ». a. ¢ z 4 Ste ‘Peer ~ i? Bn 1299/0, ‘INP plOddef + ~ f f — vy a 4 wed —> J 7 ee” ’ Joa - 4 f A “1y Fail A | 7 adits ed ‘A Za eth 3 ans fo + ba Re ¥ >. , "s ~ spose»: Grou POaqadys ° Fa 81149904 “ ' yynjo , ' \. “sadns 11q0) eu gig | snipaponh fo \ | : poay avjntuy j ibd x pypsadns J } 40j03 1140 ati ; i] ~ STDTU OLE |i THE MUSCLES OF THE UPPER EXTREMITY. 185 1. MyomMERIC MUSCLES. (2) The oculomotor muscles: sevator pal pebree superiors, rectus superior, rectus medialis, rectus inferior, and obliguus "inferior. (b) The trochlearis muscles: obliquus superior, (c) The abducens muscles: rectus lateralis. (d) The hypoglossus muscles: genioglossus, hyoglossus, styloglossus, and lingualis. 2. BRANCHIOMERIC MUSCLES. (2) The trigeminus muscles: masseter, lemporalis, plerygoideus externus, plerygoideus internus, mylohyoideus, digas tricus (anterior belly), fensor palati, and fensor tympani, (6) The facialis muscles: stylohyoideus, digastricus (posterior belly), slapedius, platysma, epicranius, and the auricular, palpebral, oral, and nasal muscles as classified above. (c) The vago-accessorius muscles: stylopharyngeus, levator veli palatine, musc, uvula, palatoglossus, palatopharyn- geus, constrictores pharyngis, the laryngeal muscles, érapezius, and sternocleidomastoideus.—ED.] THE MUSCLES OF THE UPPER EXTREMITY. The muscles of the upper extremity are composed of four chief groups: I. The muscles of the shoulder, 7. ¢., muscles which arise from the shoulder-girdle, pass through the region of the shoulder, and are inserted into the skeleton of the free upper extremity in the vicinity of the shoulder-joint. This group includes the deltoideus, the su pra- Spinatus, the injras pinatus, the teres minor, the subscapularis, and the teres major. II. The muscles of the upper arm, i. ¢., muscles the greater portion of which are situated in the upper arm. This group is subdivided into: (1) The muscles of the flexor surface; (2) the muscles of the extensor surface. Group II, 1, is composed of the biceps brachii, the coracobrachialis, and the brachialis; group II, 2, is formed by the ¢riceps brachii (and the anconeus). III. The muscles of the forearm, i. ¢., those of which the greater portions are situated in the forearm. According to their arrangement and position they are composed of three sub- divisions: (1) the muscles of the flexor surface; (2) the muscles of the radial side; (3) the muscles of the extensor surface. The muscles of the flexor surface are arranged in two layers. The superficial layer is formed by the pronator teres, the palmaris longus, the flexor carpi radialis, the flexor digitorum __- sublimis, and the flexor carpi ulnaris. The deep layer is composed of the flexor digitorum pro- fundus, the flexor pollicis longus, and the pronator quadratus. The radial group consists of the brachioradialis, the extensor carpi radialis longus, and the extensor carpi radialis brevis. In the muscles of the extensor group the supinator holds a special position. The remain- 7 ing muscles are composed of three subdivisions: (a) A superficial layer, formed by the extensor digitorum communis, the extensor digili V proprius, and the extensor carpi ulnaris; (b) a deep oblique layer, formed by the abductor pollicis longus and the extensor pollicis brevis; (c) a deep ‘straight layer, composed of the extensor pollicis longus and the extensor indicis proprius. __ IV. The muscles of the hand, i. ¢., those which extend between parts of the skeleton of he hand. These muscles are subdivided into three groups: (1) The muscles of the thenar 186 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 268.—The muscles of the posterior surface of the left scapula and the neighboring portion of the extensor surface of the upper arm. The deltoid has been removed with the exception of its origin and insertion; portions of the dorsal muscles inserting into the vertebral border of the scapula and also of the latissimus dorsi and pectoralis major have been retained. Fic. 269.—The muscles of the anterior surface of the left scapula and the neighboring portion of the flexor surface of the upper arm. Portions of the thoracic, cervical, and dorsal muscles which insert into the scapula or humerus have been retained. eminence; (2) the muscles of the hypothenar eminence; and (3) the lumbricales (four) and the interossei (seven). The palmaris brevis is also situated in the hand. The muscles of the thenar group are the abductor pollicis brevis, the flexor pollicis brevis, the opponens pollicis, and the adductor pollicis; those of the hypothenar group are the abductor digiti V brevis, the flexor digiti V brevis, and the opponens digiti V. The interossei are composed of the zuterossei dorsales (four) and the interossei volares (three). THE MUSCLES OF THE SHOULDER. The deltoideus (Figs. 268 and 270) is a thick, triangular, markedly curved muscle which is situated in the deltoid region. It arises, opposite to the insertion of the trapezius, by short tendons from the acromial third of the clavicle and from the border of the acromion, by a wide aponeurosis from the entire length of the spine of the scapula, and partly from the infraspinatus fascia (see page 207). Its fibers, which are grouped into coarse fasciculi separated by deep inter- spaces, converge toward intramuscular septa, so that the muscle rapidly diminishes in size as it passes toward its insertion, which is into the deltoid tuberosity of the humerus. The upper surface of the insertion is muscular; the lower is tendinous and is separated from the greater tubercle of the humerus by a large bursa, the subdeltoid bursa (Fig. 268). The anterior border of the deltoid is practically in contact with the clavicular portion of the pectoralis major, although between the two muscles there is usually a quite narrow space, the deltoideo-pectoral triangle, which becomes broader as it approaches the clavicle and in which runs the cephalic vein. The posterior border of the muscle is in relation with the infraspinatus, the fascia of which partly covers its under surface, and the entire upper border is in contact with the trapezius. Its insertion is embraced by the origin of the brachialis. The deltoid is supplied by the axillary (circumflex) nerve. It elevates the arm to the horizontal plane. The supraspinatus (Fig. 268) is a triangular, moderately strong muscle which fills the supraspinatus fossa and is completely concealed by the insertion of the trapezius. It arises from the entire extent of the supraspinatus fossa and from the enveloping supraspinatus fascia. The markedly narrowed tendon of insertion passes beneath the acromion and the coracoacromial ligament, immediately above the articular capsule of the shoulder-joint (to which it is adherent), and is attached to the uppermost facet of the greater tubercle of the humerus. The infraspinatus (Fig. 268) is also triangular, but it is stronger and broader than the supraspinatus. The outer half of the muscle is covered by the deltoid, while the inner half is Levator scapulae * Acromio-clavi- cular lig. . ee f. Clavicle <<, : 4 \ <—Supraspinatiis ? \ — ) Rhomboideus minor » , y- . — ~ \ Deltoideus x Spine of scapula _——Deltoideus » : " 2 ——_ panne —— —_ - Subdeltoid bursa | ~— % j ae ‘5 \ Z 2 ¢ : \ \ Rh \ Pectoralis major yd i , Serratus ant. » y hi a Omohyotdeus * Trapezius ~ Clavicle x Supraspinatus Subclavius » -- Coracoid process _Pectoralis minor » Serratus Long head ant. x of triceps ymboideus major THE MUSCLES OF THE SHOULDER. 187 immediately beneath the skin in the scapular region (see page 146). The muscle arises from the entire surface of the infraspinatus fossa and from the markedly aponeurotic enveloping infraspin- atus fascia. The fibers are practically horizontal, and as they converge toward the insertion frequently form a kind of intermediate tendon. The terminal tendon is a flat strong tendon, and, like that of the supraspinatus, is adherent to the articular capsule of the shoulder-joint; it is inserted into the middle facet of the greater tubercle of the humerus. The supraspinatus and the infraspinatus are supplied by the suprascapular nerve. They rotate the arm outward (backward). The teres minor is an clongated quadrangular muscle, situated immediately below the infraspinatus, to which it is more or less adherent. It is covered by the infraspinatus fascia, from which it takes a partial origin, and in its outer third it is also covered by the deltoideus. It arises from the lower part of the infraspinatus fossa and from the middle portion of the axillary border of the scapula. The tendon of the muscle is but slightly narrowed and is inserted into the lowermost facet of the greater tubercle, being, like the tendons of the preceding muscles, _ also adherent to the articular capsule of the shoulder-joint. The teres minor is supplied by the axillary (circumflex) nerve and is an external rotator like the supraspinatus and the infraspinatus. The teres major (Figs. 268 and 269) is stronger and longer than the teres minor. Its origin is covered by the latissimus, being situated between this muscle and the teres minor, and it lies along the axillary border of the scapula somewhat nearer to the dorsal surface. It arises from the dorsal surface of the lower third of the axillary border of the scapula, extending down- ay ward as far as the inferior angle, and, crossing the long head of the triceps, it terminates in a broad thick tendon which is situated in front of that of the latissimus and is inserted with it into the entire length of the lesser tubercular ridge (see page 146). Between the teres major and minor there is a triangular aperture which is subdivided by the long head of the triceps into an inner triangular and an outer quadrangular space. The triangular space gives passage to the circumflex scapular artery, while the quadrangular space transmits the axillary nerve and the posterior circumflex artery of the humerus. Pe The teres major is supplied by the subscapular nerves. It is an internal rotator of the arm, assisting the latissimus. 4 f The subscapularis (Fig. 269) is a broad, flat, triangular muscle which completely fills the . subscapular fossa. The muscle with its fascia is in contact with the serratus anterior by its entire width, with the origin of the short head of the biceps and the coracobrachialis by its inser- tion, and with the teres major and the origin of the long head of the triceps by its lower border. ‘The upper border of the muscle is adjacent to the origin of the omohyoid. It arises from the subscapular fossa and from the muscular lines thereon. Its fasciculi sonverge to a number of intermuscular septa, and the strong broad tendon of insertion passes ver the anterior surface of the articular capsule of the shoulder-joint, to which it is firmly adherent, and is attached to the lesser tubercle of the humerus and to the sees portion the lesser tubercular ridge. =e 188 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 270.—The deltoid and muscles of the upper arm seen from the side. Fic. 271.—The muscles of the upper arm seen from the side and from behind. The part of the antibrachial fascia which covers the anconeus has been removed and the outer head of the triceps has been severed and turned aside in either direction. Fic. 272.—The muscles of the flexor surface of the upper arm, superficial layer. The deltoid has been removed. Fic. 273.—The muscles of the flexor surface of the upper arm, deep layer. The deltoid and biceps have been removed. Immediately below the coracoid process, and on the under surface of the subscapularis near its insertion, there is a constant bursa which is a diverticulum of the synovial membrane of the shoulder-joint and is known as the subscapular bursa (see page 121). The subscapularis is supplied by the subscapular nerves from the brachial plexus. It is an internal rotator of the arm. THE MUSCLES OF THE UPPER ARM. THE MUSCLES OF THE FLEXOR SURFACE. Upon either side of the lower portion of the arm there is a distinct ¢ntermuscular septum (Figs. 270 to 273) between the muscles of the flexor and those of the extensor surface. The internal intermuscular septum is the stronger of the two and ends at the internal epicondyle, the external intermuscular septum is weaker and extends downward as far as the external epicon- dyle. These septa give origin to muscles of both groups, the external septum furnishing attach- ment also for the radial group. The biceps (Figs. 272 and 273) is a long, large, spindle-shaped muscle which is situated immediately beneath the brachial fascia in the anterior brachial and cubital regions, and arises by two distinct heads, the long head and the short head. The long head arises from the supragle- noidal tuberosity of the scapula by means of a long cylindrical tendon, which passes through the cavity of the shoulder-joint (see page 121) and through the intertubercular groove, being enveloped in the latter situation by the intertubercular mucous sheath (Fig. 273). The tendon of the short head is short, flat, and adherent to that of the coracobrachialis; it comes from the coracoid process of the scapula. Each head of the biceps forms a cylindrical muscular belly (the short head almost immedi- ately after its origin) and the two bellies may remain separated for quite a distance, though in immediate contact with one another, but always unite above the elbow-joint (never before reach- ing the middle of the arm) to form a single muscle. The widest part of this muscle is at the middle of the arm; and to either side of it a distinct groove may be recognized, the internal and external bicipital grooves. As it passes downward, the muscle becomes narrower, and in the region of the elbow-joint it passes into a tendon of insertion which consists of two portions, a deep, flat, strong tendon and a thin superficial portion known as the Jacertus fibrosus (Figs. 272, 273,274, and 291). The latter is composed of superficial radiating fibers from the tendon es * Trapezius Z y Jascia Fig. 270. ' Antibrachial j > ___ External inter- muscular septum ; External § cpicondyle 4) J 7 - Olecranon Outer Outer ¥ head » head » External inter- muscular septum i 14 f/ \ Extensor carpi ij radialis longus j Brachioradialis ] t \ J Olecranote | External fF / = | epicondyle j | y = , Extensor carpi f SS radialis brevis 4 A ntibrachia in 4 JSascia Fig. 271. Omohyotdeus » / ‘ aes Clavicle A CA Subclavius » Coracoid process. » —_ ‘ — a “Subscapularis Z — © Biceps , | ‘ (short head) BTendon of long head of biceps : Tendon of Bucctoralis mayor | . . 5 MB -# HBursa of latissimus major ~ Hy top| Tendon of latissimus Supra- spinatus * _Coraco-clavi- cular lig. Coraco-acro- mial lig. f Intertubercular mucous Sheath ) Hf Tendon of biceps (long head) Tres = Dr iceps : Blog piead) Coraco- A ; brachialis "fy Deltoideus Long head of biceps » Internal intermuscular septum Internal intermuscular septum Brachialis Internal epicondyle Lacertus « fibrosus endon of biceps Ricipito-radial Lacertus WR » bursa Jibrosus Pee H _ Tendon brachii = i\ “a a : Vi 4 Fig. 273. a rs _—S a THE MUSCLES OF THE UPPER ARM. 189 of the biceps, which pass obliquely across the antecubital fossa toward the ulnar side and fade away in the antibrachial fascia covering the superficial flexors of the forearm. The actual tendon of the biceps muscle passes deep down between the flexor and the radial groups of muscles and inserts into the tuberosity of the radius (Figs. 273 and 275). Between the tendon of insertion and the radius there is placed a bursa, the bicipitoradial bursa (Fig. 273). The biceps is supplied by the musculocutaneous nerve. It flexes the forearm, supinates the forearm (in common } with the supinator brevis), and increases the tension of the antibrachial fascia. A third or accessory head of the biceps is present in rare instances; it arises from the humerus in common with the brachialis. The coracobrachialis (Fig. 273) is a long and rather flat muscle, which is placed alongside of the short head of the biceps and is almost entirely concealed by this structure. Its short tendon of origin, arising from the tip of the coracoid process, is adherent to the short head of the biceps and covers the insertion of the subscapularis and the tendons of the latissimus and teres major shortly before their insertion. It is inserted into the anterior and internal surfaces of the humerus at about its middle, below the lesser tubercular ridge, and into the internal intermuscular septum. The muscle possesses a long slit which gives passage to the musculocutaneous nerve. ' The coracobrachialis is supplied by the musculocutaneous nerve. It elevates the upper arm, assisting the deltoideus. : The brachialis (Figs. 273 to 275) is a strong, broad, rather flat, elongated muscle, almost entirely concealed by the biceps, which is situated in the lower two-thirds of the flexor surface of the arm. It arises from the antero-internal surface of the humerus, somewhat above the middle of the bone and, embracing the insertion of the deltoid, takes origin also from the antero- internal and antero-external surfaces of the lower portion of the shaft of the humerus, and from the internal and external intermuscular septa, the origin from the internal intermuscular septum extending downward almost to the internal condyle. The anterior surface of the muscle is distinctly hollowed to accommodate the overlying biceps, and in the lower portion of the arm it appears to either side of that muscle. On the outer side it is in relation with the outer head of the triceps and with the brachioradialis; on the inner side, it is especially distinct and is in relation with the inner head of the triceps. It is inserted into the tuberosity of the ulna by means of a strong tendon which is especially well developed upon the anterior surface of the muscle. Its insertion is concealed by the tendon of the biceps and also by the superficial flexors of the forearm arising from the internal condyle. The brachialis is supplied by the musculocutaneous nerve and usually also by the radial. It is a pure flexor of the THE MUSCLES OF THE EXTENSOR SURFACE. The triceps (Figs. 268 and 270 to 273) isa large elongated muscle which possesses three aeads. The Jong head (anconeus longus) (Figs. 268 and 271 to 273) is a somewhat rounded muscle which arises by a short tendon from the infraglenoidal tuberosity of the scapula. It es between the teres major and minor, that is to say, in front of the teres minor and behind the Igo ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. teres major (see page 187), and becomes aponeurotic upon its inner surface. It is frequently connected with the latissimus dorsi by a tendinous slip. The outer head (anconeus lateralis) (Figs. 270 and 271) arises from the postero-external surface of the humerus, commencing immediately below the greater tubercle, and from the upper half or the upper two-thirds of the external intermuscular septum. ‘The origin of this outer head is fibrous above but fleshy below; its fibers run downward and inward to the common tendon of the triceps. The inner head (anconeus medialis) (Figs. 271 to 273) arises more deeply than the outer one, and its fibers are shorter and extend further downward; as a rule, however, it is not as strong as the outer head. It arises from the entire length of the internal intermuscular septum, opposite to the brachialis and partly covered by the biceps, from the posterior surface of the humerus below the groove for the radial nerve, and from the external intermuscular septum as low down as the externalepicondyle. The portion of it which comes from the internal intermuscular septum and which is not concealed by the biceps, lies immediately beneath the brachial fascia, as does also that portion arising from the external intermuscular septum, which is not covered by the outer head. A large part of the inner head is concealed by the outer one, and between the origins of the inner and outer heads the radial nerve runs in its groove. The fibers of the inner and outer heads unite with those of the long head and pass into the common extensor tendon, which commences upon the posterior surface of the muscle at about the middle of the arm and is inserted chiefly into the olecranon process of the ulna. The insertion not only completely surrounds the olecranon, but also radiates to the ulna and the antibrachial fascia. The triceps occupies the entire extensor surface of the arm between the intermuscular septa, and is consequently situated in the postero-external and postero-internal brachial regions. The relations of the long head have already been described (see page 187). The inner head is in relation with the brachialis at the internal intermuscular septum, and at the internal epicondyle its fibers are continued directly into the anconeus; the outer head, at the external intermuscular septum, is in relation successively with the brachialis, the brachioradialis, and sometimes also with the extensor carpi radialis longus. The triceps is supplied by the radial nerve. It extends the forearm. From a functional and topographic standpoint the triceps is associated with the anconeus (anconeus quartus) (Figs. 271, 278, and 280), which is situated in the upper part of the forearm, and is a flat triangular muscle lying beneath but not adherent to the antibrachial fascia. The lower angle of the muscle is placed between the flexor carpi ulnaris and the superficial group of extensors. It arises by a short tendon from the external epicondyle, passes over the articular capsule of the elbow-joint, to which it is adherent, and is inserted into the upper portion of the posterior surface of the ulna immediately below the olecranon. The upper fibers of the nauscle are usually directly continuous with the lower portion of the inner head of the triceps. The anconeus has a function and innervation similar to that of the triceps, and in addition it increases the tension: of the articular capsule of the elbow-joint. There is frequently a small muscular fasciculus passing between the internal epicondyle and the olecranon over the ulnar nerve; it is known as the epitrochleo-anconeus. iis’ ng tn) cle ee A ll ii THE MUSCLES OF THE FOREARM. 191 THE MUSCLES OF THE FOREARM. THE MUSCLES OF THE FLEXOR SURFACE. THE SUPERFICIAL LAYER. e The superficial layer of the flexor group (Fig. 274) consists of a muscle complex which arises by a common tendon from the internal epicondyle. All of the muscles of this group with the exception of the pronator teres pass beyond the wrist-joint and become tendinous ata varying distance above this articulation, and they occupy the ulnar side of the volar surface of the forearm. In the upper portion of the forearm they are all adherent to the antibrachial fascia, with the exception of the flexor digitorum sublimis, and conceal the _ the brachialis. They are separated from the radial group of muscles by a through which the tendon of the biceps passes to its insertion (see page 188), to the muscles of the deep layer they arise chiefly in the upper arm and, with the pronator teres, consequently pass over two articulations. The pronator teres (Figs. 274 and 275), the outermost of the group, is an elongated quad- rangular muscle which arises by two heads. The humeral head is the Stronger and comes from _ the common tendon of origin; the weaker ulnar head is more deeply placed, coming from the ~ coronoid process of the ulna, and is frequently adherent to the tendon of the brachialis. The . space between the two heads gives passage to the median nerve. a The belly of the pronator teres covers the insertions of the biceps and supinator and passes below the latter muscle to the middle of the outer surface of the radius, where it is attached to the bone by a short tendon (Fig. 280). insertion of deep groove and in contrast exception of the This muscle, like the majority of the group, is supplied by the median nerve. the forearm, and it can also assist the brachialis in flexing the elbow ‘usually gives a partial origin to the muscle. As indicated by its name, it pronates -joint. Ifa supracondyloid process be present, it The flexor carpi radialis (radialis internus) (Fig. 274) is a long spindle-shaped muscle, _ the distal half of which is tendinous. It is the second muscle of the group passing from the radial to the ulnar side, and arises like its fellows from the common tendon and from the antibrachial fascia. In the middle of the forearm it forms a round tendon which passes through a special sheath (see page 205) beneath the transverse carpal ligament in the groove of the multangulum majus to the base of the second, and sometimes also of the third metacarpal bone. The muscle is supplied by the median nerve, Together with the flexor carpi ulnaris it : produces volar flexion; when it acts with the radial extensors it causes radial flexion (radial abduction), The palmaris longus (Fig. 274) is the smallest and the most superficial muscle of the entire er, and is weak, frequently absent, and tendinous in the lower two-thirds of its course. Its gin is adherent to those of its neighbors and is from the internal epicondyle and the antibrachial a. The long tendon becomes markedly flattened in the lower third of the forearm and is situated immediately beneath the fascia; it passes over the transverse carpal ligament, to which it S partly adherent, and radiates into the palmar aponeurosis (see page 198). . ‘his muscle acts chiefly as a tensor of the palmar and of the antibrachial fascia; it can also assist in lexing the forearm. It is supplied by the median nerve. I9Q2 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 274.—The superficial layer of the muscles of the flexor surface of the forearm together with the brachioradialis, seen from in front. Fic. 275.—The superficial layer of the muscles of the flexor surface of the forearm after removal of the palmaris longus and the flexor carpi radialis, seen from in front and slightly from the radial side. The brachioradialis is drawn outward to show the supinator and the insertion of the tendon of the biceps. The flexor digitorum sublimis (Figs. 274 to 276) is concealed at its origin by the palmaris longus and the flexor carpi radialis, and the greater portion of its ulnar border is covered by the flexor carpi ulnaris. The main origin of the muscle, the wmeral head, forms the deepest portion of the common tendon arising from the internal epicondyle, while the second head, the radial head, arises by a flat tendon from the volar surface and border of the radius below the insertion of the supinator. The two heads are connected by a tendinous arch beneath which passes the median nerve, and unite to form a broad and strong muscular belly which is usually composed of two distinct portions, a superficial and a deep. The deep portion receives the oblique fibers from the radius and soon gives off the tendons for the index and little fingers, while the tendons for the middle and ring fingers proceed from the superficial portion. The four tendons, which frequently do not become independent until near the wrist-joint, run through a synovial sheath together with the tendons of the deep flexor and pass beneath the transverse carpal ligament to the middle phalanges of the second to the fifth fingers (see page 205). The flexor digitorum sublimis is exclusively supplied by the median nerve. It flexes the middle phalanges of the four fingers. The flexor carpi ulnaris (u/naris internus) (Figs. 274 and 276) is the innermost and the most posterior muscle of the group. Its posterior border is in relation with the anconeus and the superficial extensors, being separated from the latter by the dorsal -border.of the ulna. In addition to a humeral head the muscle also possesses an ulnar head from the anterior surface of the olecranon, the ulnar nerve passing between the two heads. An additionai origin is furnished by the antibrachial fascia, which is adherent to the upper two-thirds of the ulnar border of the muscle and by means of which the muscle arises from the volar border of the ulna. The muscle is distinctly semipenniform in structure, since a tendon is formed in its inner border at the middle of the forearm, into which muscular fibers radiate almost as far down as the wrist-joint. This tendon is inserted into the pisiform bone and the insertion is thence prolonged to the metacarpus by the ligaments of the pisiform bone (see page 125). The muscle is supplied by the ulnar nerve. When acting with the flexor carpi radialis it effects volar flexion; together with the extensor carpi ulnaris it produces ulnar flexion. THE DEEP LAYER. The deep layer of the muscles of the flexor surface consists of the two deep flexors of the digits and of the pronator quadratus. ‘It is almost entirely concealed by the superficial layer. The flexor digitorum profundus (Figs. 275 and 277) is a broad, strong, thick muscle which arises from the volar surface of the ulna from the coronoid process to the junction of the | Internal epicondyle Triceps (inner head) Internal intermuscu- ~ lar septum — = Olecranon 4 Tendon of biceps --Pronator teres : Internal epicondyle Brachio- radialis Extensor carpi radialis longus : ‘ Lacertus Tendon of bicep Fascia longus » __Bicipito-radial bursa “Radius Flexor carpi ulnaris Flexor digito-- ; rum sublimis ‘ Flexor digitorum s f profundus . +--- Flexor pollicis | fp ongus i j : Flexor pollicis longus : Radius | Abduct. llicis i - Tendon of pied A brachioradialis gus : ; : : Tendon of brachio- ronator ‘ali: guadratus : ler \ i ih ™ Pronator : : th ij A Tendon of 4m b A palmaris longus “ Fig. 274. Fig. 275. THE MUSCLES OF THE FOREARM, 132 ip ira ry Y Hlumeral | 1 of flexor sublimti Fic. 276.—The flexor sublimis digitorum after removal of the flexor carpi radialis, the palmaris longus, and the pronator ™Q4 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 277.—The deep layer of the muscles of the flexor surface of the forearm after removal of the superficial layer, seen from in front. Fic. 278.—The muscles of the forearm seen from the radial side. middle and lower thirds of the bone, and from the adjacent portion of the interosseous membrane. Four parallel tendons are soon given off, the one situated nearest to the radial side coming from a separate muscular belly composed of the fibers proceeding from the interosseous membrane. These tendons run in the same synovial sheath as do those of the flexor sublimis and pass beneath the transverse carpal ligament (the anterior annular ligament) to terminate upon the ungual phalanges of the second to the fifth fingers (see page 205). The ulnar half of the muscle is supplied by the ulnar nerve, the radial half by the median nerve. It flexes the terminal phalanges of the four fingers. The flexor pollicis longus (Figs. 275 to 277) is a spindle-shaped muscle placed imme- diately alongside of the flexor digitorum profundis; it is penniform above and semipenniform below. It arises from the volar surface of the radius between the insertion of the supinator and the upper border of the pronator quadratus. It also usually receives a slendér fasciculus, frequently aponeurotic, from the coronoid process and from the internal condyle; this origin, however, which is known as the humeral head, does not come directly from the bone but from the muscular mass of the superficial flexors. The muscle becomes tendinous almost immediately below its origin, the upper portion receiving the muscular fibers from either side, the lower portion from the radial side only, and the tendon runs in its own tendon-sheath beneath the transverse carpal ligament and passes between the two heads of the flexor pollicis brevis to the ungual phalenx of the thumb. The muscle is supplied by the median nerve. It flexes the terminal phalanx of the thumb. ai. ‘onator quadratus (Figs. 277 and 284) is a flat quadrilateral muscle which is con- cealed by all the tendons of the flexor muscles and lies upon the volar surfaces of both bones of the forea.m toward their distal extremities. It arises from the volar border of the ulna and is inserted into the volar surface and border of the radius, both its origin and insertion being usually by short aponeuroses. The muscle is supplied by the median nerve (volar interosseous nerve) and pronates the forearm. THE RADIAL GROUP OF THE MUSCLES OF THE FOREARM. The three muscles of the radial group are placed at the radial side of the forearm and of ~ the lower portion of the arm in the so-called radial region, between the flexors and the extensors. The brachioradialis belongs more to the flexor surface, but the other two muscles are upon the extensor side of the forearm, and while the superficial layers of both flexor and extensor muscles are adherent to the fascia of the forearm, the extensor carpi radialis brevis is the only muscle of the radial group in which a similar relation obtains. The brachioradialis (supinator longus) (Figs. 270, 271, and 274 to 279) is a very long flat Brachioradialis External cpicondyle Palmaris longus Olecranon Pronator teres (humeral head) + N Flexor carpi radialis Ulnar head of pronator teres Tendon of biceps Bicipito-radial bursa Humeral head of flexor longus pollicis Pronator teres » Brachioradialis Interosscous membrane Extensor dig. propr. Tendon of | —Tendon of exten dig. comm. —Tendon of exten dig. V propr. Abductor ___ Tendon of extensor pollicis longus carpi radial longus Extensor pollicis Tendon of flexor br eves —Tendon of exter carpi ulnaris Tendon ____ J carpi ulnaris Tendon of flexor of. extens. 7 Wal ac g- Ulna carp radialis carpi rad. long.-“Darsal j Tendon of extens. ° FF carpi rad. br. ste - endons of flex. dig. sublimis: - oo Tendon of palmaris longus | Fig. 277. Tendon of extens. indicis propr. Fig. 278. THE MUSCLES OF THE FOREARM. 195 muscle which is in immediate relation in the forearm with the superficial layer of the flexor surface (see page 191). It arises from the external intermuscular septum of the upper arm, where it is in immediate relation with the outer portion of the brachialis on the one side and with the outer head (or inner head, see page 190) of the triceps on the other (Figs. 270 and 271). The origin ends some distance above the external epicondyle. In the forearm the brachioradialis becomes somewhat narrower, covers the supinator and the insertion of the pronator teres (Figs. 274 and 275), and, in the middle of the forearm, terminates in a flat tendon which runs over the insertion of the _ pronator quadratus to be attached to the upper end of the styloid process of the radius. ~The radial nerve passes between the outer portion of the brachialis and the brachioradialis. The muscle is supplied by the radial nerve. It is practically a flexor of the forearm, and the name, supinator longus, formerly applied to it, does not correctly state its function, The extensor carpi radialis longus (radialis externus longus) (Figs. 270, 271, and 278) is a long flat muscle resembling the brachioradialis. It arises as a direct continuation of the origin of the latter muscle, from the lower end of the external intermuscular septum of the upper arm and from the external epicondyle opposite to the lowermost portion of the inner head of the triceps (Figs. 270 and 271) (see page 190), and terminates above the middle of the forearm in : a somewhat flattened tendon. It lies immediately adjacent to the brachioradialis (upon its ulnar side and somewhat posteriorly), covers the volar and lateral surfaces of the radius, passes beneath the dorsal carpal ligament, and inserts into the dorsal surface of the base of the second aa metacarpal bone (see also page 203). The extensor carpi radialis brevis (radialis externus brevis) (Figs. 270, 271, and 278) es immediately beside the longus. It arises just below the latter muscle from the external -epicondyle, the antibrachial fascia, and the articular capsule of the elbow-joint; it covers the : lateral surface of the radius and becomes tendinous somewhat below the middle of the forearm. The flattened tendon is longer than that of the longus, with which it passes beneath the dorsal carpal ligament, and is inserted into the base of the third metacarpal bone. .e Both extensores carpi radiales are supplied by the radial nerve. Together with the extensor carpi ulnaris they produce dorsal flexion; and with the flexor carpi radialis they effect radial ~ flexion (radial abduction). Their tendons are crossed in the forearm by the extensor pollicis _ brevis and the abductor pollicis longus, and their insertions are crossed by the tendon of the extensor pollicis longus. p ye THE MUSCLES OF THE EXTENSOR SURFACE. ; _ With the exception of the supinators, the extensors are situated to the ulnar side of the radia group. i Eh > supinator (su pinator brevis) (Figs. 275 to 277 and 280) is a flat muscle which curves yout the upper extremity of the radius and is in relation with many of the muscles of the fore- Its origin is concealed by the anconeus, its middle portion by the superficial extensors, s anterior (volar) portion by the radial group and the pronator teres. The insertion of the e 196 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 279.—The superficial layer of muscles of the extensor surface of the forearm. Fic. 280.—The deep layer of muscles of the extensor surface of the forearm. The superficial layer of the extensors has been removed, the cavities of the dorsal carpal ligament have been opened and the tendons of the superficial muscles removed. muscle is in immediate relation with the insertion of the tendon of the biceps and with the bicipito- radial bursa. It arises from the external epicondyle of the humerus, from the radial lateral and annular ligaments of the elbow-joint, and from the supinator ridge of the ulna. It is tendinous at its origin and usually exhibits a superficial aponeurosis in the middle of its course. Some of the fibers run almost horizontally and some of them obliquely forward and downward, passing to the upper, outer, and lower portion of the tuberosity of the radius and to the volar surface and border, the outer surface, the dorsal surface and border of the same bone. The fibers passing to the volar border terminate immediately above the insertion of the pronator (radii) teres. The muscle usually consists of a superficial and of a deep portion which are not sharply differentiated, and between the two portions the deep (posterior interosseous) branch of the radial nerve passes. The supinator is supplied by the radial nerve. As its name indicates, it supinates the forearm. THE SUPERFICIAL LAYER OF THE EXTENSORS. This layer consists of three muscles, adherent to each other at their origins, which are partly in common with the extensor carpi radialis brevis from the external epicondyle of the humerus and the antibrachial fascia, and they terminate in tendons which are distinctly directed toward the ulnar side and pass beneath the dorsal carpal ligament to the back of the hand. They are situated in the dorsal region of the forearm, chiefly upon the dorsal surface of the ulna (and upon the supinator above), and are in relation externally with the extensor carpi radialis brevis, inter- nally with the anconeus and below with the flexor carpi ulnaris. The extensor digitorum communis (Figs. 278, 279, and 289) is a broad, flat, strong muscle which arises from the external epicondyle of the humerus and the antibrachial fascia; it is intimately adherent to the extensor digiti V and partly to the extensor carpi radialis brevis. Somewhat below the middle of the forearm it divides into three (or four) bellies (Fig. 279) which terminate in round tendons; the ulnar one gives off tendons for both the ring and little fingers when only three bellies are present. ‘The tendons pass beneath the dorsal carpal ligament to the back of the hand (Fig. 289), where those for the ulnar fingers are connected by slender transverse or oblique tendinous fasciculi, the juncture tendinum. In the fingers, these tendons form the main portion of the dorsal aponeurosis. The extensor digiti V proprius (Figs. 279 and 289) is a thin slender muscle which is so closely connected with the extensor digitorum communis that it seems to be a part of it. Its slender tendon passes through a separate compartment in the dorsal carpal ligament to the dorsal aponeurosis of the little finger (Fig. 281) and is sometimes double, taking the place of the tendon of the extensor communis to the little finger, which may be poorly developed or even absent (Fig. 289). Brachialis— Radial lateral ligament ¥ Annular ligament Pronator teres » * Flexor carpi ulnaris p Extensor dig. V proprius Abductor pollicis long.-- | Tendons of exten- + : i} sores carpi radial. Ss Extensor pollicis brevis - y ; 7 Dorsal ae a ; Tendon of extensoris carpi radial. brevis Tendon of extensoris carpi radial. longi Fig. 280. Extensor pollicis{ , “Dorsal lis x long. arpal — et ‘ Extensor indicis pr. : Fig. 270, THE MUSCLES OF THE FOREARM. 197 Both muscles are supplied from the radial nerve. They extend the four ulnar fingers especially their proximal phalanges ' The extensor carpi ulnaris (u/naris externus ) (Figs. 279 and 2869) arises together with the two other muscles of this group from the external epicondyle of the humerus, and also from the articular capsule of the elbow-joint and quite extensively from the antibrachial fascia, with which the muscle is adherent for almost half of its entire length. It is in relation above with the anco- neus and lower down is separated from the flexor carpi ulnaris by the dorsal border of the ulna. It passes over the dorsal surface of the ulna, becomes tendinous in the lower third of the forearm, runs beneath the dorsal carpal ligament, and inserts into the base of the fifth metacarpal bone. i, The extensor carpi ulnaris is supplied from the radial nerve. When acting with the extensores carpi radiales, it produces dorsal flexion, and together with the flexor carpi ulnaris it effects ulnar flexion (ulnar abduction). THE DEEP OBLIQUE GROUP OF EXTENSORS. This layer is differentiated from the deep straight group by the fact that only the origins of the muscles comprising it are concealed by the superficial extensors. The muscles become superficial below and cross the tendons of both extensores carpi radiales in the lower third of the forearm. Like the muscles of the deep flexor group, they pass over only the wrist-joint. The abductor pollicis longus (ex/ensor ossis metacar pi pollicis) (Figs. 279, 280, and 289), the outermost of the group, is a flat strong muscle, the origin of which is completely concealed by the superficial group of extensors. It has a long pointed origin from the dorsal surface of the ulna and also arises from the interosseous membrane and from the dorsal surface of the radius below the insertion of the supinator. In the lower third of the forearm it crosses, together with the extensor pollicis brevis, the tendons of the extensores carpi radiales at an acute angle and Bs terminates in a tendon (or two tendons) which passes beneath the dorsal carpal ligament to be inserted chiefly into the base of the metacarpal bone of the thumb. Tendinous fibers usually _ Tadiate also to the greater multangular bone and to the abductor pollicis brevis (see page 199). The muscle is supplied from the radial nerve. It abducts the thumb and also assists in the extension of this digit. The extensor pollicis brevis (Figs. 279, 280, and 289) is situated more to the ulnar side _ and is by far the weakest muscle of the group. It is a slender muscle, situated immediately _ alongside of the abductor, and arises from the interosseous membrane and from the dorsal surface of the radius. It crosses the tendons of the extensores carpi radiales and its slender tendon _ passes through the same compartment as the abductor (Fig. 289) and is inserted into the dorsal aponeurosis of the first phalanx of the thumb. — Ttis supplied from the radial nerve. It extends and abducts the first phalanx of the thumb. THE DEEP STRAIGHT GROUP OF EXTENSORS. ___ The muscles of this group lie immediately to the ulnar side of the preceding, but they are deeply placed in the forearm and are completely concealed by the superficial extensors. _ The extensor pollicis longus (Figs. 279, 280, and 289) is stronger than the brevis. It a arises from the dorsal surface of the ulna and from the interosseous membrane and forms a 1) 198 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 281.—Tendons and muscles (interossei dorsales) of the dorsum of the hand. The dorsal carpal ligament is retained, the rest of the dorsal fascia being removed. Fic. 282.—The palmar aponeurosis and the palmaris brevis. The thenar and hypothenar muscles are shown covered by the fascia. long, slender, muscular belly which passes downward to the wrist-joint beside the extensor digitorum communis. Just before reaching the wrist it terminates in a tendon which passes — through a special compartment in the dorsal carpal ligament (Fig. 289), crosses* the tendons of the extensores carpiradiales immediately before their insertion, and is attached to the ungual phalanx of the thumb, being partly adherent to the tendon of the extensor pollicis brevis. This muscle is also supplied from the radial nerve. It extends the ungual phalanx of the thumb and assists the action of the abductor. The extensor indicis proprius (the indicator) (Figs. 279, 280, and 289) is a long slender muscle situated to the ulnar side of the extensor pollicis longus. It arises chiefly from the dorsal surface of the ulna, receiving additional fibers from the interosseous membrane, is completely concealed by the extensor digitorum communis, and passes through the dorsal carpal liga- ment in the same compartment with the latter muscle (Fig. 289). Just above the wrist-joint it terminates in a tendon which runs on the dorsum of the hand alongside of the tendon of the communis for the index-finger and forms with this tendon the dorsal aponeurosis of that finger. It is supplied from the radial nerve. It aids in the extension of the index-finger. THE MUSCLES OF THE HAND. The thenar and hypothenar eminences occupy respectively the radial and ulnar bor- ders of the hand, but the flexor tendons and lumbricales, running in the middle of the palm, are covered by a strong aponeurosis which is usually a direct radiation of the tendon of the palmaris longus (see page 193) and is known as the palmar aponeurosis (Fig. 284) (the palmar fascia). This aponeurosis is always connected with the transverse carpal ligament and gradually fades away upon either side into the fascia of the thenar and hypothenar eminences. It is narrow at the transverse carpal ligament and becomes broader as it passes downward toward the fingers, and its longitudinal fasciculi, which gradually disappear in the integument over the bases of the proximal phalanges of the second to the fifth fingers, are united in the distal portion of the palm by transverse fasciculi, which close in the interspaces lying between the longitudinal fasciculi passing to the individual fingers. These spaces give passage to the vessels and nerves for the margins of the fingers, and beneath them are situated the lumbricales. The ulnar margin of the denser central portion of the palmar aponeurosis and the transverse carpal ligament give origin to a muscle which passes over the muscles of the hypothenar emi- nence and the ulnar vessels to the integument at the ulnar border of the hand. This muscle is — situated entirely within the superficial fascia of the palm, varies in its development in difiprent individuals, and is termed the palmaris brevis (Fig. 282). * This crossing occurs within the dorsal carpal ligament, so that the tendon-sheaths also cross each other (see the description of the tendon-sheaths of the hand, page 203). 78S St snJuop surpuyod fo uopua] oy a prsvf “pomyovsgy snJuo, sypipps sdivg 4osuajxa Jo uopuas snJuo) siayjod dojanpqno fo uopua,— siiadg sypipos 1div2 «A . srumundod wnsop1aip ‘4osuajxa fo suopua] dosuajxa fo uopuar] seis yap sniuo, sryjod r fe; 4osuajxa fo uopuay y . Peel ft! Te ~ siaasg Siaiyod 7 SOE i Ewen - Puree iober und) jods02 ASAIASUDA saposmus ow jooaquny oo 7 sasoanauodp uopua | THE MUSCLES OF THE HAND. 199 It is supplied by the superficial volar branch of the ulnar nerve and is a tensor of the skin of the ulnar border of the hand. THE MUSCLES OF THE THENAR EMINENCE. The abductor pollicis brevis (Figs. 285 and 290) is the most superficial of the muscles of the thenareminence. It arises by a broad short tendon from the tuberosity of the navicular bone and from the transverse carpal ligament, becomes markedly narrower toward its insertion, and is attached by means of a short tendon, containing the radial sesamoid bone, to the base of the first phalanx of the thumb. It is usually adherent to the adjacent tendon of the abductor pollicis longus (see page 197). It is supplied by the median nerve and abducts the thumb. The opponens pollicis (Figs. 283, 284, and 290) is a rather short, moderately strong muscle, the greater portion of which is concealed by the abductor brevis. It arises from the tuberosity of the greater multangular bone (the trapezium) and from the transverse carpal ligament and inserts by oblique, partly tendinous fibers into the entire length of the radial border of the meta- carpal bone of the thumb. It is supplied by the median nerve and opposes the thumb. The flexor pollicis brevis (Figs. 283 and 284) is situated on the ulnar side of the abductor _ and is only partly concealed by the latter muscle. It consists of a superficial or radial and a deep or ulnar head. The superficial head arises from the transverse carpal ligament beside and distal to the origins of the abductor and the oppenens, it conceals the ulnar border of the latter muscle, ’ becomes adherent to the ulnar or deep head, and is attached to the basal phalanx of the thumb by means of the radial sesamoid bone. The deep head arises from the bottom of the carpal canal, _ chiefly from the palmar surfaces of the lesser multangular (trapezoid) and capitate (os magnum) _ bones, is adherent to the oblique fibers of the abductor pollicis, and passes to the ulnar sesamoid _ bone and to the ulnar side of the basal phalanx of the thumb. The deeper portions of the two heads are adherent, but the superficial portions form a groove for the tendon of the flexor pollicis longus. Both heads together flex the first phalanx of the thumb; the radial head assists opposition, the ulnar aids adduction. he radial head is supplied by the median nerve, the ulnar by the deep volar branch of the ulnar nerve. , [The description of the muscle given above follows the plan which is usual in anatomical text-books. Comparative anatomy shows very clearly, however, that the two heads are really of very different significance, the radial head being the true flexor brevis pollicis, while the ulnar head is a portion of the adductor. This is indicated in the human hand by the different nerve-supply of the two heads.—Ep } The adductor pollicis (Figs. 284, and 290) is situated in the depths of the palm. It is ered by the palmar aponeurosis, 7 the tendons of the flexores digitorum, and by the lum- es, and rests upon the interosseus volaris I (and dorsalis 1). Some of its fibers, which have ; n oblique direction and are intimately connected with the deep head of the flexor brevis, arise at : 200 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. ' Fic. 283.—The palmar muscles after removal of the palmar aponeurosis. The tendon-sheath of the middle finger has been split lengthwise. Fic. 284.—The deep layer of the palmar muscles. The transverse carpal ligament and the abductores digiti V and pollicis brevis have been removed. The tendons of the long flexors have been removed from the carpal canal and, after splitting the tendon-sheaths of the fingers, have been partly removed and partly drawn aside. the bottom of the carpal canal from the palmar surfaces of the lesser multangular (trapezoid) and capitate (os magnum) bones, but the greater number arise from the palmar surface of the ~ shaft of the third metacarpal bone, and pass almost horizontally toward the narrow tendon of insertion which is attached to the basal phalanx of the thumb by means of the ulnar sesamoid bone. The muscle is supplied by the ulnar nerve. It adducts the thumb, 7. e., approximates the thumb and index-finger. THE MUSCLES OF THE HYPOTHENAR EMINENCE. The abductor digiti quinti (Figs. 285 and 290) is the strongest and innermost muscle of the group. It arises from the pisiform bone, sometimes also from the transverse carpal ligament, and is inserted into the ulnar border of the dorsal aponeurosis of the little finger. It is supplied by the ulnar nerve, and abducts the little finger, 7. e., separates the little from the ring finger. The flexor digiti quinti brevis (Figs. 285 and 286) arises from the transverse carpal liga- ment and from the hamulus of the hamate (unciform) bone. It is a small slender muscle situated _to the radial side of the abductor and may be entirely absent, or fused with the opponens. Its short tendon of insertion is attached beside that of the abductor into the basal phalanx of the little finger. It is supplied by the ulnar nerve. It flexes the first phalanx of the little finger. The opponens digiti quinti (Figs. 283, 284, and 290) arises together with the preceding muscle and runs to the ulnar border of the metacarpal bone of the little finger. It also is supplied by the ulnar nerve and opposes the little finger. THE INTEROSSEI AND THE LUMBRICALES. The interossei completely fill the interspaces between the metacarpal bones. Those mus- cles situated nearer to the dorsal surface are known as the interossei dorsales, those nearer the palmar surface as the interossei volares. The four interossei dorsales (Figs. 281, 285, and 289) are located in the dorsal portions of the four interosseous spaces, the largest being the interosseus dorsalis primus, which is situated between the metacarpal bones of the thumb and index-finger. They arise by two heads from the opposite surfaces of the contiguous metacarpal bones and are the only muscles which are partly visible beneath the fascia upon the back of the hand. Near the heads of the metacarpal bones « SuDUyN KIDD b 4oxf fo uopur] * ee 11 Ta ee ; * y [. ; : : & . . ‘ aw ; ‘ * ‘ ‘ “eg ag! : : 7 ss ad 2 4 7 + oar eel ay ea THE MUSCLES OF THE HAND. 201 they terminate in short tendons which radiate into the dorsal aponeuroses of the basal phalanges (see page 205) (Fig. 286), the middle finger receiving the tendons of the second and third muscles, while the tendon of the first passes to the radial side of the index-finger, and that of the last to the ulnar side of the ring-finger. The interossei volares (Figs. 284 and 287) are three in number and are deeply placed in Interosseus dorsalis II } ferosseus dorsalis Interosseus dorsalis I ‘. aes Interosseus dors III _-- Interosseus dorsalis IV Tendons o} extensor digitorum -«< comm, ===Se=e Tendons o} interossei volar. Tendons o} lumbricales Fic. 285.—Diagram of the dorsal aponceurosis of the fingers and of the interossei dorsales. the palm, the two ulnar muscles (the second and third) being situated beside the abductor pollicis and the first or radial one beneath the latter muscle. They arise by a single head, the first one coming from the ulnar border of the metacarpal bone of the index-finger and the second and third from the radial sides of the fourth and fifth metacarpal bones. Each muscle is inserted into the extensor tendon of the finger from the metacarpal bone of which it takes its origin. The index-finger consequently receives the tendon of an interosseus dorsalis upon its radial side and 202 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Tendon of Tendon of extensor digitorum comm. interosseus Tendon of lumbricalis ae Jos Interosseus +. Lumbricalis Tendon of flexor digitorum Tendon of flexor digitorum sublimis profundus Fic. 286.—Diagram showing the relation of the tendons of the interossei and lumbricales to the dorsal aponeurosis of the fingers and the arrangement of the long flexor tendon of the fingers. Tendons of flexor digi- , forum pro- Lumbricalis jundus Yi | i Lumbricalis __..- LIP | Nae iy S| \— Lumbri- IV gf ||) Ba \-“ calis I Lumbricalis III i flexor digi- torum sub- limis X Tendons of flexor digitorum projun- dus X Fic. 287.—Diagram of the interossei volares. Fic. 288.—Diagram of the lumbricales. THE MUSCLES OF THE HAND. 203 the tendon of an interosseus volaris upon its ulnar side; the middle finger has two interossei dorsales; the ring-finger has a volar tendon upon its radial, and a dorsal tendon upon its ulnar side; and the little finger received a single tendon, that of the third interosseus volaris, upon its radial side. The interossei dorsales are posterior and the interossei volares anterior to the trans- verse capitular ligaments (see page 127), which consequently separate the two groups of interossei in the region of their insertions. [As stated above, it is customary to recognize but three interossei volares. A fourth is, however, present in the form of an exceedingly slender muscle which arises from the first metacarpal and is inserted into the ulnar side of the base of the first phalanx of the thumb, along with the ulnar head of the flexor brevis pollicis, with which muscle it is frequently more or less extensively fused.—ED.] All of the interossei are usually supplied by the ulnar nerve. They either abduct or adduct the fingers. The middle finger may be moved toward cither the index-finger or ring-finger by the action of its interossei dorsales; the first inter- osseus dorsalis pulls the index-finger toward the thumb; the last one draws the ring-finger toward the little finger. The first volaris pulls the index toward the middle finger; the second draws the ring toward the middle finger; and the third adducts the little toward the ring-finger. The interossci also assist the action of the lumbricales (see below). The four /umbricales (Figs. 283, 286, 288, and 290) are long, narrow, worm-like muscles which arise deep in the palm from the four tendons of the flexor digitorum profundus. The two radial muscles arise by a single head from the radial borders of the two radial tendons, while the two ulnar muscles usually arise by two heads from the adjacent borders of the three ulnar tendons. Near the basal phalanges of the fingers they terminate in very slender tendons which are inserted, from the radial side, into the dorsal aponeuroses of the fingers in common with the interossei. The two radial lumbricales are usually supplied by the median nerve, the two ulnar by the ulnar nerve. They flex ; the basal phalanges of the fingers and extend the second and third phalanges. | THE RELATIONS OF THE EXTENSOR TENDONS AND THEIR SHEATHS BENEATH THE DORSAL CARPAL LIGAMENTS. ; As the tendons of the extensors of the hand and of the fingers pass over the wrist-joint (Figs. 280, 283, and 289) they are enclosed in the synovial sheaths and held in the grooves upon the _ dorsal surfaces of the radius and ulna by a thickened portion of the antibrachial fascia, the dorsal : carpal (posterior annular) ligament. The individual synovial sheaths are situated in different _ compartments of the ligament, since this structure is attached to the longitudinal ridges upon the bones and especially to those of the radius. - These compartments will be described in the order in which they are encountered in passing m the radial to the ulnar side of the wrist (Figs. 280 and 289). The tendons of the extensor icis brevis and abductor pollicis longus pass through a common compartment and to a certain ent are invested by a common synovial sheath. The second compartment gives passage to the tendons of the extensor carpi radialis longus and brevis, which usually possess individual synovial sheaths. The third compartment is superficially placed and is not longitudinal but it at an acute angle and contains the tendon and synovial sheath of the extensor pollicis . Next follows the largest of all the compartments; it contains in a common sheath the 204 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. four tendons of the extensor digitorum communis and that of the extensor indicis proprius. The fifth compartment contains the slender tendon of the extensor digiti V proprius and is superficially situated. The sixth and last compartment gives passage to the tendon of the extensor carpi ulnaris. The synovial sheaths are considerably longer than the width of the dorsal carpal ligament; those of the extensores communis, indicis, and digiti V may extend to the middle of the meta- carpus. Tendons oj extensor digitorum Juncture tendinum = ve W 1g ; 6 Interosseus dorsalis I Tendon-sheath of extensor --~ digitt V proprius ‘. Tendon-sheath of extensor pollicis ee brevis Tendon-sheath of extensor -~ \ : carpi ulnaris \ Tendon-sheath of abductor pollicis longus Common tendon-sheath of ex--~ tensor digitorum and exten- sor indicis Tendon-sheath of extensor pollicis longus fogs : ] co aod = : a 3 “ olecranal bursa Dorsal carpal lugament Fig. 292. Fig. 291. i i eee a THE MUSCLES OF THE LOWER EXTREMITY. 209 17. The bursa oj the flexor carpi radialis, at the tubercle of the navicular bone. 18. The inlermetacar pophalangeal bursa, situated at the metacarpophalangeal articulations, posterior to the capitular ligaments. ‘ [In the development of the muscles of the upper extremity, the earliest differentiation observable is a separation of the muscle sheet which lies upon the posterior or extensor surface of the limb from that which lies upon the anterior or flexor surface. In accordance with this, it is possible to recognize a group of posterior or, as they are preferably termed, post-axial muscles, and a second group of pre-axial muscles, in each of the segments of the limb, and it is noticeable that the former, in so far as they are supplied by nerves given off after the establishment of the cortis of the brachial plexus, receive their innervation through the posterior cord, while the latter are supplied by derivatives of the anterior (%. e., the inner and outer) cords. The classification of the limb muscles according to the limb segments, as given above, may therefore be supplemented by dividing each set into a post-axial and a pre-axial group, thus: I. THE MUSCLES OF THE SHOULDER (to which should be added the pectoral muscles and the superficial muscles of the back with the exception of the trapezius). (a) Post-axial muscles: levator scapula, rhomboideus minor, rhomboideus major, serratus anterior, delloideus, supra- spinatus, injraspinatus, teres minor, subscapularis, teres major, and latissimus dors. (b) Pre-axial muscles: pectoralis major, pectoralis minor, subclavius, and coracobrachialis. II. THE MUSCLES OF THE UPPER ARM. (a) Post-axial muscles: friceps, anconeus. (b) Pre-axial muscles: biceps, brachialis. III. THE MUSCLES OF THE FOREARM. (a) Post-axial muscles: brachio-radialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum communis, extensor digiti quinti proprius, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis proprius. (b) Pre-axial muscles: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum sublimis, flexor digitorum projundus, flexor pollicis longus, and pronator quadratus. IV. THE MUSCLES OF THE BAND. (a) Post-axial muscles: wanting. : (b) Pre-axial muscles: palmaris brevis, abductor pollicis brevis, opponens pollicis, flexor brevis pollicis, abductor digité quinti, opponens digiti quinti, flexor brevis digiti quinti, lumbricales, adductor pollicis, interossei volares, interossei dorsales.—ED.] THE MUSCLES OF THE LOWER EXTREMITY. The muscles of the lower extremity are divided into the muscles of the hip, the muscles of the thigh, the muscles of the leg, and the muscles of the foot. The muscles of the hip are again _ subdivided into an anterior and a posterior group, the former consisting of the iliopsoas, and the latter of the gluteus maximus, the gluleus medius, the gluteus minimus, the pirijormis, the obturator internus with the gemelli, the quadratus jemoris, and the tensor jascie late. In the thigh there may be distinguished the muscles of the anterior surface, those of the inner side, and those of the posterior surface. The first two groups are separated by the sartorius; the muscle of the anterior surface is the quadriceps jemoris; those of the inner side are the pec- tineus, the adductor longus, the gracilis, the adductor magnus, the adductor brevis, the adductor eds, and the obturator externus; and those of the posterior surface are the biceps jemoris, th e semilendinosus, and the semimembranosus. In the leg there may be distinguished the muscles of the posterior surface (the muscles of he calf), the muscles of the anterior surface, and the muscles of the outer side. The muscles mq oe a eon ae aon ——— 210 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. of the posterior surface are arranged in two layers, the superficial one being formed by the ¢7- ceps sure and the deep one consisting of the popliteus, the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus. The anterior group is composed of the tibialis anterior, the extensor digitorum longus, the peroneus tertius, and the extensor hallucis longus. ‘The exter- nal group is formed by the peroneus longus and brevis. The muscles of the foot may be divided into the muscles of the dorsum and the muscles of the sole (plantar muscles). The muscles of the dorsum are the extensor digitorum brevis and the extensor hallucis brevis. The muscles of the sole are composed of a median group, the flexor digitorum brevis and the quadratus plante; of a group passing to the great toe, the abductor hal- lucis, the flexor hallucis brevis, and the adductor hallucis; and of a group passing to the little toe, the abductor digiti V, the flexor brevis digiti V, and the opponens digiti V. The lumbricales and the interossei are also situated in the sole of the foot. THE MUSCLES OF THE HIP. THE INTERNAL MUSCLES OF THE HIP, THE ILIOPSOAS. The iliopsoas (Figs. 252, 296, 297, 299, and 300) is composed of the psoas major and the iliacus, which are completely separated in the upper portion of their course but united at their insertion. ‘This muscle frequently also includes a psoas minor. ; The psoas major is a long, strong muscle, the greater portion of which is situated in the posterior abdominal wall. It arises from the upper and lower margins of the bodies of the twelfth thoracic to the fourth lumbar vertebra, from the intervertebral fibrocartilages, and from the tendinous arches which pass over the concavities of the middle of the bodies of the lumbar verte- bre and the lumbar vessels. A second series of origins comes from the transverse processes of all of the lumbar vertebra, but is concealed by the fibers proceeding from the vertebral bodies, and the nerves forming the lumbar plexus pass between the two origins of the muscle. The muscle is flat above but becomes narrower and thicker as it passes downward and out- ward over the terminal line of the pelvis and beneath the inguinal ligament to unite with the iliacus. It lies upon the lateral surfaces of the upper and middle portions of the lumbar vertebral column and its upper portion is bridged over by the internal lumbocostal arch of the diaphragm. The outer margin of the muscle is in relation above with the quadratus lumborum, which it partly conceals, and below with the inner margin of the iliacus. The inner margins of the two psoas major muscles form the lateral boundaries of the pelvic inlet. The iliacus is a flat, thick, strong muscle which fills the entire iliac fossa. It arisesfrom the iliac fossa, extending upward to the crest of the ilium and forward to the anterior superior and inferior spines, and passes downward and forward behind the inguinal ligament and fuses with the psoas major. The combined iliopsoas passes beneath Poupart’s ligament through the muscular lacuna (see page 231) into the thigh, where it is placed between the rectus femoris and the pectineus and forms a deep fossa with the latter muscle, the iliopectineal fossa. It runs directly over the capsular ligament of the hip-joint, passes slightly backward, and is inserted by a short tendon into the lesser trochanter. Where the muscle runs over the iliofemoral ligament of the hip- THE MUSCLES OF THE HIP. 211 joint there is a bursa which not infrequently communicates with the articular cavity, the iio pec- lineal bursa (Fig. 208). A psoas minor (Fig. 238) is present in somewhat more than half of all cases. It is a flat thin muscle, lying upon the psoas major and arising from the body of the last thoracic or the first lumbar vertebra and from the intervertebral disc between the two. The muscle soon passes into a flat tendon which becomes continuous with the iliac fascia covering the iliopsoas (sce page 231) and is inserted with this fascia in the region of the iliopectineal eminence. - / The iliopsoas is supplied from the lumbar plexus. It flexes the thigh and also rotates it slightly inward. ‘The psoas minor ! is a tensor of the iliac fascia. THE GLUTEAL MUSCLES. The gluteus maximus (Figs. 293 and 294) is a large strong muscle, particularly thick* in its lower portion, and is situated in the gluteal region im- | mediately beneath the skin. It is covered by a thin layer of fascia and by the layer of subcutaneous fat which is very well developed in this situation. The muscle arises from the external surface of the ilium (Fig. 293) between the posterior gluteal line and the posterior portion of the iliac crest, from the posterior surface of the sacrum and coccyx (and _ from the posterior sacroiliac ligament in this situa- tion), and from the sacro-tuberous ligament. Its fibers pass from above downward and from within outward. The fasciculi are unusually thick and dis- tinctly separated from each other by penetrating septa 5 of fascia and fat; the lower (inner) fasciculi are the 4. Sg The origion of the hres plated unos. ie longest, and this portion of the muscle is twice as dorsum of the ilium. thick as the upper (outer) segment. The gluteal lines are represented by the dotted lines. The superficial fibers of the muscle, especially those of the upper weaker half, pass over the greater trochanter to the iliotibial band of the fascia lata (see page 232); the deeper fibers, particularly the longer inferior ones, are inserted into the gluteal tuberosity. The inner and upper margin of the glutus maximus is in relation with the posterior layer _ of the lumbodorsal fascia, where this structure gives origin to the latissimus; the antero-external portion is in relation with the gluteus medius and the gluteal fascia, which envelops the latter muscle. It runs over the tuberosity of the ischium and the origins of the flexor group of muscles ‘see page 218), these latter making their appearance beneath the fascia below the inner and lower * The gluteus maximus is one of the thickest muscles in the human body. 212 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 294.—Superficial layer of the posterior muscles of the hip. The portion of the superficial layer of the fascia lata which covers the tensor fascia late has been removed. *=posi- tion of greater trochanter. Fic. 295.—Middle layer of the posterior muscles of the thigh. The gluteus maximus has been divided and reflected. margin of the gluteus maximus. The insertion conceals the tendinous origin of the vastus later- alis from the trochanter major. The tendon of insertion is separated from the great trochanter by a large bursa, the trochanteric bursa (Fig. 295), beneath which there is usually one or two addi- tional bursze, the gluteofemoral bursa or burse (Fig. 295). About half of the gluteus medius, the piriformis, the obturator internus and gemelli, the quadratus femoris, and the adductor mini- mus are covered by the gluteus maximus. The glutzus maximus is supplied by the inferior gluteal nerve. It extends the thigh and is the antagonist of the iliopsoas. The gluteus medius (Figs. 293, 295) is also a strong, flat, thick muscle, part of which is concealed by the gluteus maximus, the remainder of it (Fig. 294) being situated in the upper glu- teal region directly beneath the gluteal fascia, to which it is adherent. It arises from the outer surface of the ilium (Fig. 293), in the area between the anterior gluteal line, the iliac crest, and the posterior gluteal line, and from the gluteal fascia. The fibers of the muscle converge toward the greater trochanter, the posterior fasciculi being more or less independent and passing obliquely downward and outward, the middle fibers running directly downward and the anterior ones down- ward and inward. The short and broad tendon of insertion is attached to the outer portion of the greater trochanter (Fig. 295), extending upward as far as the tip of this process. While the greater portion of the gluteus medius is covered by the glutzeus maximus, it in turn completely conceals the gluteus minimus, and its posterior margin is usually in immediate rela- tion with the upper margin of the piriformis. Beneath its insertion there is usually situated a bursa, the posterior bursa of the gluteus medius (Fig. 301). , The muscle is supplied by the superior gluteal nerve. It abducts the thigh; the larger anterior portion also acts as an internal rotator, the posterior portion (frequently characterized by a species of intermediate tendon and by a different direction of its fibers) also as an external rotator. The gluteus minimus (Figs. 293, 301, and 302) is a flat, broad, fan-like muscle which lies upon the outer surface of the ala of the ilium and the postero-superior aspect of the articular cap- sule of the hip-joint. It arises from the posterior surface of the ilium between the anterior and inferior gluteal lines (Fig. 293), and the fibers converge from all sides toward the greater tro- chanter. In the middle of its course the muscle develops a broad aponeurosis which passes directly into a short broad tendon. The insertion is into the tip and inner border of the great trochanter. The gluteus minimus, like the medius, is supplied by the superior gluteal nerve. It also has a similar function (abduction). The piriformis (Figs. 295, 298, and 300 to 302) is a decidedly conical muscle which is usually in immediate relation with the posterior border of the gluteus medius. Its insertion is ee a q ‘66% “SIY psing posouiaf -090}1)1) xD snavjns fo vsang ILIIJUDYIO‘ | 4dJUDYION 4d4DO4T) pul 40404490 - fo uopua, & , ”, , é ¢v 4 4 puvq 71g 01 apjv} apisvf 408d | juauind1 snou 1804305 | i . — poe THE MUSCLES OF THE HIP. 213 covered by the gluteus medius and minimus, the middle or main portion of the muscle is directly beneath the glutaus maximus, and the origin is situated within the pelvic cavity. It arises from the pelvic surface of the sacrum at the margins of the anterior sacral foramina II to IV (frequently also from between the foramina or concealing them), and from the margin of the greater sciatic notch. After leaving its flat and broad origin, the muscle becomes somewhat narrower, passes through the middle of the greater sciatic foramen, beneath the glutaus maximus becomes tendinous rather abruptly, and is inserted by a slender rounded tendon into the tip of the greater trochanter. The piriformis does not fill the greater sciatic foramen but divides it into two compartments which transmit both vessels and nerves, the sciatic nerve being one of several structures which leave the pelvic cavity through the lower compartment. The piriformis is usually supplied by direct branches from the sciatic plexus. It is an external rotator. It is some- times perforated by a portion of the sciatic nerve. The obturator internus (Figs. 295 and 300 to 302), like the piriformis, arises in the true pelvis, but it passes to the gluteal region through the lesser sciatic foramen. The muscle arises from the obturator membrane and the adjacent surfaces of the pubis and ischium and, to a cer- tain extent, from the obturator fascia. It is very broad at its origin, but becomes markedly nar- rower as its fibers converge toward the lesser sciatic foramen, in passing through which the muscle bends at almost a right angle around the margin of the lesser sacrosciatic notch, the surface directed toward the bone being tendinous, and reaches the gluteal region, where it soon terminates in a slightly flattened tendon which passes directly to the trochanteric fossa, where it is inserted. After passing through the lesser sciatic foramen and reaching the posterior surface of the pelvis, the muscle receives two accessory heads in the form of the slender gemelli. The gemellus superior arises from the spine of the ischium, the gemellus inferior from the ischial tuberosity. They are inserted into the tendon of the obturator internus almost throughout their entire length, so that they together with the tendon form a kind of penniform muscle. Where the obturator internus bends about the margin of the lesser sciatic notch there is constantly situated a bursa, the bursa of the obturator internus, and upon the muscle lies the thick sciatic nerve. The obturator internus, together with the gemelli, is usually supplied by direct branches from the sacral plexus. Like the piriformis, it is an external rotator of the thigh. The quadratus femoris (Figs. 295 and 301) is a flat, thick, rectangular muscle situated in front of the gluteus maximus. It arises from the outer border of the tuberosity of the ischium and inserts by a short tendon into the intertrochanteric ridge. The upper margin of the muscle is in immediate relation with the gemellus inferior, and the lower margin with the adductor mini- mus. Usually beneath the quadratus, or in the groove between it and the gemellus inferior, runs the obturator externus, upon which lies the sciatic nerve. The quadratus femoris is supplied by the sciatic nerve. It is an external rotator of the thigh. The tensor fascie late (Figs. 294 and 296) is a flat elongated muscle, narrow above and broad below, which is situated between the two layers of the fascia lata (see page 232) in the upper gluteal, trochanteric, and external femoral regions. It arises by a short and flat tendon from | ei - 214 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 296.—The superficial layer of muscles of the anterior surface of the thigh. Fic. 297.—The muscles of the anterior surface of the thigh after removal of the sartorius. The inguinal ligament has also been removed. ‘ the anterior superior iliac spine, and at the junction of the upper and middle thirds of the thigh q becomes distinctly broader and is continuous with the iliotibial band (tract of Maissiat) of the outer side of the fascia lata. Anteriorly the muscle is in immediate relation with the sartorius, posteriorly with the glutzeus medius, and it partly covers the vastus lateralis. The muscle is supplied by the superior gluteal nerve and serves to increase the tension of the fascia lata. THE MUSCLES OF THE THIGH. THE SARTORIUS. The sartorius (Fig. 296) is a very long, flat, narrow muscle running diagonally across the anterior surface of the thigh, and is the longest muscle of the body.* It arises from the anterior superior spine of the ilium in common with the tensor fasciz late but in front of the latter muscle, becomes considerably broader for a short distance after its origin, passes inward and downward below the iliopsoas and upon the upper portion of the rectus femoris, covers the groove between — the vastus medialis and the adductors in the middle third of the thigh (see page 217), and reaches — the lower portion of the internal femoral region. In this situation it gradually becomes — narrower and is twisted so that the surface which was anterior in the upper portion of the thigh now becomes internal. It then takes up a position beside the outer (anterior) margin of the gra- — cilis and becomes tendinous as it passes over the inner aspect of the articular capsule of the knee- joint, and its flattened tendon runs above that of the gracilis to be inserted into the inner border — of the tuberosity of the tibia, being separated from the bone by the sartorial bursa. The tendon of insertion forms the uppermost of the group of tendons known as the pes anserinus (see page 219). The sartorius is supplied by the femoral nerve. It aids in the flexion of the thigh and the extension of the lower leg and acts as an internal rotator when the knee-joint is flexed. THE MUSCLES OF THE ANTERIOR SURFACE. The quadriceps femoris (Figs. 296 to 298, 301, and 302) consists of four different heads, the most independent of which, the rec/ws femoris, unites with the remainder only in the lower por- tion of its course. This head passes over two articulations, while the remaining three are inti- mately adherent with each other and extend over the knee-joint only. The rectus femoris (Figs. 296 to 298) is a long, thick, decidedly spindle-shaped muscle, which is situated in the anterior femoral region, lying for the most part immediately beneath the | deep fascia. It arises by a short, strong, bifurcated tendon (Fig. 298), one part of which comes from the anterior inferior spine of the ilium and pursues the same direction as that of the muscle * The sartorius also possesses the longest muscular fasciculi in the body. Anterior super. % & “Ligament. | Tensor Sasciae latae Hiotibial “9 band of fascia lata Vastus "Tendon of sartorins ~Tendon of gracilis Tuberosity of tibig Tendon of i Semitendinosus L 4 : is Fig. 296. ~~ Promontory Spine of ilium Sartorius Tensor fasciae | Piriformis latae » Glutaeus & ~ Inguinal medius Symphyseal .~ surface of pubis Adductor magnus Adductor canal (femoral vessels) lateralis ies ; Gracilis Patellar 3 lig. = Sartorial 5 bursa Sartorius » ‘ 24 Pes ba j anserinus Fig. 297. —* ‘ [ te JF a h a = - = a > ” s lt [ re ff I : | Che vastus lateralis fl. : ; ( | e ¥ . ° lhe vastus intermedius | " 216 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 298.—The deep layer of muscles of the anterior surface of the thigh. The iliopsoas, sartorius, rectus femoris, pectineus, adductor longus, and gracilis have been removed. Fic. 299.—The insertion of the iliopsoas and the origin of the obturator externus. The adductors have been divided and reflected; the femur has been sawed through below the trochanters, and is slightly flexed and rotated outward. Fic. 300.—The origins of the piriformis and the obturator internus. The pelvis has been divided in the median line. THE INTERNAL OR ADDUCTOR GROUP. The muscles of this group arise from the pubis and ischium in such a way that they form a series of rings about the obturator foramen. The outermost ring is formed by the obturator externus, the middle by the adductor brevis and minimus, and the inner by the pectineus, the adduc- tor longus, the gracilis, and the adductor magnus. The pectineus (Figs. 296 and 297) is a flat, strong, quadrangular muscle situated between the iliopsoas and the adductor longus in the subinguinal and anterior femoral regions, and form- ing, together with the iliopsoas, the iliopectineal fossa. It arises from the crest of the pubis as far forward as the pubic tubercle, passes obliquely from above downward and from within outward, and is inserted by a short tendon into the pectineal line of the femur. The insertion is partly concealed by the iliopsoas, covers the obturator externus and the upper part of the adductor brevis, and passes over the inner surface of the articular capsule of the hip-joint. The pectineus adducts the thigh and also assists flexion. It is supplied by the obturator and femoral nerves. The adductor longus (Figs. 296 and 297) is a thick, flat, almost triangular muscle, situated between the pectineus and the gracilis. It arises by a rather narrow but short and strong tendon from the superior pubic ramus, between the origins of the pectineus and gracilis, becomes decidedly broader as it passes downward, and is inserted by a short tendon into the middle third of the inner lip of the linea aspera. The fibers of the muscle pursue a direction similar to those of the pecti- neus, although they run more directly downward. If the muscle is well developed its upper mar- gin is immediately continuous with the lower margin of the pectineus, and while it is situated between the pectineus and the gracilis above, its lower portion lies upon the adductor magnus, which is exposed between the adductor iongus and the gracilis. The upper portion of the adduc- tor longus covers the adductor brevis, the lower the adductor magnus, its tendon of insertion is concealed by the sartorius and is adherent to the origins of the vastus medialis (see page 215), and, together with the sartorius and the inguinal ligament, the muscle forms a triangle, the jemoral triangle (triangle of Scarpa). The adductor longus is supplied by the obturator nerve; it adducts the thigh. The gracilis (Fig. 297) is a long, thin, slender muscle, situated upon the inner aspect of the thigh. It arises by a flat tendon from the superior and inferior rami of the pubis near the sym- physis, becomes somewhat broader at first, but soon narrows and, just above the knee-joint, passes into a long, round, slender tendon which runs to the inner border of the iubercle of the tibia and radiates into the pes anserinus as the second tendon of that structure. a — Paliness a 4 “~ ' Adductor brevis » US x c ‘ Piriformis . | ot / may , a y . ’ aft - 3 i ; a : ‘ \ = nh : meee Adductor » S- er 4 ’ api ; | | ymphyseal Sacrotuberous ligament § ; Adductor longus Veen surface | of pubis s /liopectineal bursa Bb iofemorai i lig. | : , Pirvformis . > cus a) ( oceyg' = y <> a” J Sacrotubcrous (s >. wa Lesser ——— ligament 4y trochanter Adductor Fig. 299. magnas Adductor opening. Tendon of adductor magnus 3 Promontory ~Semimembranosus Obturator canal. Internal intermuscular septum Patella * A Facies d : Rhyseos Pa lar e Sartorial bursa Y Sacrotuberous ligament Anserine bursa ; Al 7 yr 4 Tendon of sartorius . Tendon of gracilis - endon of semitendinosus + Pes anserinus \ THE MUSCLES OF THE THIGH. 217 The muscle is supplied by the obturator nerve. When the knee is extended, it adducts the thigh and assists in the flexion of the knee-joint, and, when the knee is flexed, rotates the leg inward. The adductor brevis (Fig. 298) is a long, broad, rather thick muscle which is situated in the middle layer of the adductors (behind the pectineus and adductor longus, but in front of the adductor magnus). It is longer than the pectineus, shorter than the adductor longus, and is usually completely concealed by these two muscles. It arises from the superior ramus of the pubis, nearer the obturator foramen than the adductor longus, and its fibers pursue a course similar to those of the latter muscle, but not so oblique, to the upper third of the inner lip of the linea aspera of the femur. The nerve-supply and the function are like those of the adductor longus. The adductor magnus (Figs. 296 to 298, 301, and 302) is the strongest of the adductors. It forms the deepest layer and is situated most posteriorly, arising from the inferior pubic ramus and from the lower border of the tuberosity of the ischium. Its upper fibers pass but slightly downward, the middle are more oblique, and the lower and innermost fibers pursue an almost vertical direction; the upper and middle fibers pass behind the adductor longus and brevis to a muscular or short tendinous insertion into the upper two-thirds of the inner lip of the linea aspera; the lower, almost vertical fibers, however, pass into a round slender tendon which runs to the lowest portion of the linea aspera and to the internal epicondyle of the femur. At about the lower third of the thigh this insertion contains an elongated orifice, known as the fendinous adductor opening (Fig. 298), which has tendinous boundaries and gives passage to the femoral vessels. Between the tendinous origin of the vastus medialis and the short tendinous insertions of the adductor brevis, longus, and magnus, there is a deep groove which is converted into a canal, the adductor (Hunter's) canal, by the sartorius. It contains the femoral vessels, and the tendi- nous fibers of both groups of muscles are interwoven in this situation to form a fibrous vascular sheath. While the greater portion of the anterior surface of the adductor magnus is covered by the adductor longus and brevis, its posterior surface lies upon the flexor muscles, and it is consequently situated between these two sets of muscles. The sciatic nerve lies upon its posterior surface. The adductor minimus (Figs. 295, 301, 302) is a small, flat, approximately quadrangular muscle, which frequently appears to be simply the upper portion of the adductor magnus, with ____-which it is always directly continuous. It arises from the inferior pubic ramus or from the junc- | tion of the inferior rami of the pubis and ischium, its upper fibers being almost horizontal, and running below (distal) and parallel to the quadratus femoris (covering in the uppermost fibers of the adductor magnus from behind) to be inserted into the upper end of the femur below the great trochanter and beside the gluteal tuberosity. Its lower fibers run obliquely downward and are inserted, together with those of the adductor magnus, into the upper extremity of the inner lip of the linea aspera. The sciatic nerve lies also upon the adductor minimus (see page 213). _ _ The adductor magnus and minimus are chiefly supplied by the obturator nerve and partly also by the sciatic nerve. Their action is similar to that of the other adductors. _ The obturator externus (Figs. 298 and 299) belongs to the adductor group only on account ; 218 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 301.—The deep layer of the posterior hip muscles and the superficial layer of the flexors of the thigh region. The gluteus maximus and medius and the obturator internus have been removed. Fic. 302.—The deep layer of the posterior hip muscles and the deep layer of the flexors of the thigh region. The gluteus maximus and medius, the quadratus femoris, the long head of the biceps, and the semitendinosus have been removed. of its position and innervation. It is situated upon the outer and lower surface of the pubis and ischium and is completely covered by the pectineus, the adductor longus, and the adductor brevis. Like the obturator internus within the pelvis, it arises from the pubis, from the ischium, and from the obturator membrane. It becomes narrower and thicker, runs over the lesser tro- chanter, and passes over and behind the insertion of the iliopsoas, along the neck of the femur between the gemellus inferior and quadratus femoris, largely covered by the latter muscle, to the trochanteric fossa, where it is inserted beside the obturator internus. The muscle becomes ten- dinous a short distance before its insertion. The obturator externus is supplied by the obturator nerve. It acts as an external rotator. THE POSTERIOR GROUP, THE FLEXORS. This group consists of but three muscles, the biceps femoris, the semitendinosus, and the semi- membranosus, which have a more or less common origin from the ischial tuberosity; as they pass toward the knee they are grouped in such a way that the biceps is external and the semitendi- nosus and semimembranosus internal. The three muscles lie in the posterior femoral region and their origins are concealed by the glutzeus maximus. The biceps femoris (Figs. 301, 302) is a large, strong muscle which is composed of a long biarticular and of a short monarticular head and belly. The long head (Fig. 301) is a rather strong tendon which arises in intimate connection with the semitendinosus from the lower aspect of the tuberosity of the ischium. It passes downward and becomes continuous with a broad mus- cular belly, which at first lies behind the adductor magnus and then passes markedly outward to take up a position behind the vastus lateralis. At the lower third of the thigh it receives the second head or short head (Fig. 302), which is short and rhomboid, and arises from the lower half of the outer lip of the linea aspera. At the junction of the two heads, or somewhat above it, the posterior surface of the long head possesses a distinct aponeurosis which is directly continuous with the tendon of insertion. The short head is muscular throughout its entire course. The two heads unite just above the knee-joint and the muscle is inserted by a tendon into the capitulum of the fibula. The inner margin of the biceps forms one of the boundaries of the popliteal fossa (see page 220). The long head of the biceps is supplied by the tibial nerve, and the short head by the peroneal nerve. The semitendinosus (Fig. 301) is muscular in its upper two-thirds and tendinous in its lower third. At its origin from the tuberosity of the ischium it is completely adherent to the long _ Gemellus supert Glutaens min x Re EF ‘ _- Gemellus infert Moe =/endon of obtura- == of PM Glutacus Sm for internus » s mm medius ~ - Sacrospinous Ge igtt ' N AN Middle gluteal lig. “A ¥ —— e- ‘ , bursa Sacrotuberous : , lg f “2 - Quadratus Glutaeus medius f Ischia . 2 x j lubes vf Semoris » Sacrotuberous lig. } a. —- iI ° ° — a Sacrospinous lig. - — | Obturator internus » ; Bursa of obturator int. At of @actor A t 2) i | | Vastus / Vast. s Jateralig ; Sem. - prem ra - t FOS us t iv i ly MR Biceps femoris (long head) . Biceps femoris oon 2 SHO 4 Tendon of (short head) semitendinosus Tendon of semimembranosus Tendon of = semiumnem- -- Tendon of p ema Biceps aint) ams 7 THE MUSCLES OF THE LEG. 219 head of the biceps, although its tendon is somewhat shorter, and its muscle portion frequently exhibits a tendinous intersection. In the lower fourth of the thigh it passes into a cylindrical ten- don which is inserted into the inner surface of the tubercle of the tibia and forms the lowermost tendon of the pes anserinus (Fig. 208). The three tendinous expansions of the sartorius, gracilis, and semitendinosus forming the pes anserinus (Fig. 298) are peculiar in that they form fan-like radiations between which are situated thin membranes. The broad tendinous surface of the pes anserinus is separated from the bone by the anserine bursa (Fig. 298). In addition to its attachment to the tibia, the pes anserinus is also intimately connected with the crural fascia. The semitendinosus is supplied by the tibial nerve. It flexes the leg and rotates it inward. The semimembranosus (Fig. 302) is a very peculiar muscle. Its upper third or half con- sists of a flat membranous tendon, then follows a flat but very thick muscular belly, which finally terminates at its insertion in a flattened round tendon. The muscle arises from the tuberosity of the ischium, in front of the long head of the biceps and the semitendinosus, by a flat tendon which lies between the posterior surface of the adductor magnus and the upper portion of the semi- tendinosus; upon the outer side it extends downward as far as the middle of the thigh, while it is somewhat shorter upon its inner aspect. From this tendon are given off muscular fasciculi * which pass from above downward and from without inward, and become continuous with a more rounded tendon situated upon the inner side of the muscle and commencing at the middle of the thigh. This tendon of insertion passes to the internal tubercle of the tibia, a small por- _ tion radiates into the oblique popliteal ligament (see page 135), and some fibers also run ante- riorly to the inner margin of the tibia. Beneath the tendon of the semimembranosus there is situated a bursa which communicates with the knee- joint, the bursa oj the semimembranosus (see page 136). While the upper portion of the semimembranosus is situated in front of the semitendinosus and the long head of the biceps, in the lower third of the thigh, the muscle lies internal to the biceps, together with which it forms the upper boundary of the popliteal fossa (see below). The nerve-supply and the function of the semimembranosus are similar to those of the semitendinosus, and it also _ acts as a tensor of the capsular ligament of the knee-joint. THE MUSCLES OF THE LEG. THE SUPERFICIAL LAYER, THE TRICEPS SURAE. The triceps sure consists of a superficial biarticular and _bicipital portion, the gastroc- mius, and of a deeper monarticular portion, the soleus. The gastrocnemius (Fig. 303) isa flat, elongated, distinctly bicipital and very strong muscle, 220 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 303.—The superficial muscles of the calf of the leg. Fic. 304.—The second layer of the calf muscles. The gastrocnemius has been removed. Fic. 305.—The deep musculature of the calf, seen from behind and from the inner side. The triceps sure has been removed. which is situated upon the posterior aspect of the knee and leg; its muscular belly is situated chiefly in the sural region, while its tendinous portion is located in the posterior crural region. The two heads, the inner head (gastrocnemius medialis) and the outer head (gastrocnemius later- alis), arise by tendons from the upper extremities of the epicondyles of the femur and exhibit aponeuroses upon their internal and external surfaces, extending downward almost to the middle of the muscle. Beneath the somewhat stronger inner head is situated a bursa which communi- cates with the interior of the knee-joint, the inner gastrocnemial bursa (Fig. 304) (see also page 136). Both heads of the muscle pass immediately over the posterior surface of the knee-joint forming the inferior boundary of the popliteal fossa, and below the articulation they become broader and are united in such a manner that their line of union is indicated by a median groove which extends almost to their insertion into the common tendon. Somewhat below the middle of the leg, the muscular tissue terminates rather suddenly in a broad tendon which becomes nar- rower and fuses with that of the soleus. The soleus (Fig. 304) is a flat, very broad, and rather thick muscle, the upper portion of which is covered by the gastrocnemius, the lower portion being situated immediately beneath the ‘deep fascia to either side of the gastrocnemius tendon. The muscle arises from the capitulum, posterior surface, and outer border of the fibula, from the popliteal line and the surface immedi- ately below it upon the posterior surface of the tibia, and from-a tendinous arch passing over the popliteal vessels between the tibia and fibula, the tendinous arch of the soleus. Shortly after its origin the muscle becomes broader, and exhibits upon its posterior aspect an aponeurosis which is continuous with a tendon which fuses with that of the gastrocnemius and also receives the insertions of lower lying lateral muscular fasciculi. This tendon of the triceps sure, broad at first and becoming narrower and thicker as it passes downward, is known as the calcaneal tendon (tendo Achillis). It is the strongest tendon in the entire body and is inserted into the upper margin of the tuberosity of the calcaneus. The triceps sure also includes the plantaris (Fig. 304), a small muscle witha very short but rather strong belly anda very long slender tendon. It arises from the external epicondyle of the femur, to the inner side of and somewhat above the outer head of the gastrocnemius, which partly covers it, and the short muscular belly is directed obliquely outward and downward between the gastrocnemius and soleus. The slender tendon lies upon the inner side of the soleus, runs down- ward along the inner margin of the tendo Achillis, and fades away partly into this structure and partly into the deep fascia of the leg. The triceps sure is supplied by the tibial nerve. It produces plantar flexion of the foot. The plantaris acts as a tensor of the tendo Achillis. THE POPLITEUS. The popliteus (Figs. 304 and 305) is a flat triangular muscle which is in a class by itself. It@ is situated in the same layer as the soleus, with which it is directly related by its lower and outer Inner head of Gastrocn. Tendon of semiten- [3 dinosus Semimem- branosus “Plantaris /nner gastrocn. bursa 1 Obliq. popli- teal lig. Popliteal vessels Tendon of plantaris | yi Triceps suraé | Calca- neal "do Crural fascia. | (deep layer) Peronacus | RNase i> = . ¢ ’ ri a Gastrocnemius + Inner head of gastrocnemius » Tendon of ,_ 7 semiten- dinosus Outer head of gastrocn. Semimem-* branosus \} Tendon of gracilis Perona Perona Tendon of | tibialis : 20ST. Internal _ Peroneus br. Pao of malleolus Sup. flexor -~Cale peroneal External _— digitorung tena retinac, malleolus / Sup. p Inf. retine peroneal retinac. ‘ a 7 ny - 7 o jaa i — L ‘ > a ‘ a 7 : P 7 » ’ oe -_ ye : : JZ 2 : A 7. ; 7 . > ¥ a i~@s - -. : ' = > ¥ -. :! ' i i 7 ‘ - a if e " 7 7 ‘- THE MUSCLES OF THE LEG. 221 margin, and is covered by the gastrocnemius; it runs immediately over the posterior surface of the knee-joint. It arises (inserts) by a tendon from the external epicondyle of the femur and from the arcuate popliteal ligament and inserts (arises) in the triangular area above the popliteal line upon the posterior surface of the tibia. The lower portion of the muscle is covered by a fascia, aponeurotic in character, which also gives origin to muscular fibers. Beneath the tendon of origin (insertion) is situated the popliteal bursa (see page 136), which communicates with the knee- joint. The popliteus is supplied by the tibial nerve. It acts as a tensor of the articular capsule of the knee-joint and helps to rotate the tibia inward (when the knee is flexed). THE DEEP LAYER. The muscles of this layer (Fig. 305) (the position of which has been previously described) have experienced a peculiar displacement with reference to those of the anterior group, since the tibialis posterior is pushed away from the tibia and situated in the middle, while the flexor digi- torum lies against the tibia; the flexor hallucis consequently lies upon the fibula, and therefore to the outer and not to the inner side of the flexor digitorum, as might be expected. The correct relation is restored by a crossing of the muscles, that of the tibialis posterior occurring in the leg, while the tendons of the flexor hallucis and of the flexor digitorum do not cross until they reach the sole of the foot. The tibialis posterior (Figs. 305 and 312) isa long, rather flat, distinctly penniform muscle (the lower portion is only semipenniform), which arises bya short tendon from the upper portion of the posterior surface of the tibia, from the interosseous membrane, and from the inner surface of the fibula beside the flexor digitorum, which frequently partly covers it. Immediately below this origin a very strong tendon appears in the middle of the muscle, verging gradually to its inner border, and passes behind the internal malleolus to the sole of the foot. The tendon is inserted chiefly into the tuberosity of the navicular bone (Fig. 312), some fasciculi being directly prolonged to the internal cuneiform and others radiating also to the remaining cuneiform bones and extend- ing as far as the cuboid. Above the malleolus, the tibialis posterior crosses beneath the flexor digitorum, so that its tendon assumes a position internal to that of the latter muscle. Behind the malleolus it is situated within a tendon-sheath in the laciniate ligament (see page 231). The tibialis posterior is supplied by the tibial nerve. It produces plantar flexion of the foot and also elevates the inner margin of the sole (supination). The flexor digitorum longus (Figs. 305 and 311) resembles the tibialis posterior in its external appearance. It is penniform above, semipenniform below, and lies at first upon the tibia _and, in the lower fourth of the leg, between the tibialis posterior and the flexor hallucis, the former muscle being crossed by it at a slightly higher level. The muscle arises from the posterior surface and interosseous crest of the tibia, and its tendon, like that of the tibialis posterior, is developed upon the inner border of the muscle. This tendon is situated to the outer side of that of the pia $s posterior and runs beneath the laciniate ligament to the sole of the foot (Fig. 311), where it divides into four tendons for the outer four toes. These perforate the tendons of the flexor me 222, ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 306.—The muscles of the anterior surface of the lower leg and of the dorsum of the foot. The transverse crural ligament has been removed. Fic. 307.—The muscles of the lower leg and of the dorsum of the foot, seen from the side. digitorum brevis and pass to the ungual phalanges. (Further details as to the relations of the tendons are given on page 231.) The muscle is supplied by the tibial nerve and flexes the second to the fifth toes (especially the ungual phalanges). The flexor hallucis longus (Figs. 305 and 311) resembles the other two muscles in this group, but it is somewhat shorter and stronger and, at the same time, distinctly penniform. It is the most external muscle of the group and preserves this relation throughout the leg. It arises by a ‘short tendon from the posterior surface and outer border of the fibula, below the origin of the soleus, 7. e., from the lower two-thirds of the bone, extending downward to just above the malle- olus. A thick tendon which is situated in the center of the broad muscle, commences in the middle of the leg and passes through the outer compartment of the laciniate ligament to the sole of the foot (Fig. 311), where it crosses the tendon of the flexor digitorum and runs to the ungual phalanx of the great toe and indirectly also to the other toes. The muscle is supplied from the tibial nerve. It flexes the great toe and indirectly also the four lesser toes. THE MUSCLES OF THE OUTER SIDE OF THE LEG, THE PERONZI. The posterior borders of both of these muscles are in relation with the soleus and with the deep flexor group, while their anterior margins are in relation with the muscles of the extensor group, from which they are separated in the lower third of the leg by the lower portion of the shaft of the fibula and the external malleolus. They are situated in the external crural region. The peronzus longus (Figs. 306 and 307) is a very long, distinctly semipenniform muscle, which arises by indistinctly separated anterior and posterior heads. The anterior head is a short tendon from the head of the fibula, the contiguous portion of the external condyle of the tibia and the crural fascia; the posterior springs from the upper two-thirds of the outer surface and outer border of the fibula. At the junction of the middle and upper thirds of the leg, both heads pass into a slightly flattened tendon upon the anterior surface of the muscle, which broadens as it descends and passes beneath the retinacula peroneorum (Fig. 307) (see page 230) in the groove behind the external malleolus, to the outer side of the sole of the foot. Deep down in the sole the tendon lies in the groove of the cuboid (Figs. 311 and 312), is provided with a thick sesamoid cartilage or sesamoid bone, and passes to the tuberosity of the metatarsal bone of the great toe, some fibers being prolonged to the internal cuneiform and to the base of the second metatarsal bone. The peronzus longus almost entirely conceals the origin of the peronzus brevis; in the lower part of the leg the latter may be seen both in front of and behind the margins of the peronzeus longus or its tendon. The peronzus longus is supplied from the peroneal nerve. It abducts the foot, assists in producing plantar flexion, and elevates the outer margin of the sole (pronation). Tendon of biceps Capitulum of fibula- yo ae ee Plantaris *- Patellar lig. Tuberosity of tibia ~-Capiiulum of fibula Tuberosity of tibia Peronaeus longus. Tibia (Inner surface) Peronaeus brevis Soleus Extensor digitorum longus ...Tendon of peronaeus long. Extensor C. a. hallucis longus “hank wie (Deep layer) ~> Peronaeus brevis ; Extensor hail. |. » Cruciate lig. Calcaneal tendon | Extensor digit. |. Extensor Extensor digitorum hallucis brevis brevis Tendon Tendon of ext. of peronaeus /|/] hall. long. Super. peronacal retinaculum Inf. peronaeal retinaculum H Tendon of peronaeus long. H i Fig. 306. Tendon of peronaeus brev. Tendon of peronaeus III Fig. 307. - Be a | 7 > a - . S THE MUSCLES OF THE LEG. 223 The peronzus brevis (Figs. 306, 308, and 315) is shorter than the longus, which it markedly resembles, and by which it is largely concealed. It arises from the outer surface and anterior border of the lower half of the fibula as far down as the upper margin of the external malleolus. The tendon commences in the middle of the upper portion of the muscle and then passes to the anterior margin in a similar manner to that of the peronzus longus; it is situated in front of the tendon of the peronwus longus, passing with it in the groove of the external malleolus and beneath the retinacula peronworum (see page 230) to the tuberosity of the fifth metatarsal bone, which it embraces by a wide insertion (Fig. 315). Some fibers of the tendinous insertion are usually pro- longed into the dorsal aponeurosis of the little toe. The peronwus brevis is supplied also from the peroneal nerve. It abducts the foot and assists in the production of _ dorsal flexion and pronation. THE ANTERIOR GROUP, THE EXTENSORS. The outer margin of this group is in relation with the peronai, but otherwise it is entirely isolated, since its inner margin is bounded by the inner surface of the tibia. The muscles of this group are situated in the anterior crural region. The tibialis anterior (Figs. 306 and 316) is a long muscle which is broad above and narrow below. It is the strongest muscle of the group and arises from the outer surface of the tibia as far upward as the external condyle and from the interosseous membrane. The upper third of the muscle is markedly adherent to the deep fascia of the leg, and somewhat below the middle of the leg it develops a flat, broad tendon which becomes thicker and narrower as it descends. This tendon passes beneath the cruciate ligament (see page 229) to the dorsum of the foot, and upon eaching the inner margin, is inserted into the inner and plantar surfaces of the internal cunei- form bone and into the inner border of the base of the first metatarsal bone. ; The muscle is supplied by the deep branch of the peroneal nerve. It effects dorsal flexion and clevation of the inner noargin of the foot (supination). The extensor hallucis longus (Figs. 306 and 316) is a rather weak semipenniform muscle lying to the outer side of the tibialis anterior and between it and the extensor digitorum. These two muscles, particularly the latter, conceal the greater portion of the origin of the extensor hallucis, which is from the inner surface of the lower two-thirds of the fibula and from the adjacent portion of the interosseous membrane. Almost immediately after its origin, a tendon is formed which is situated in the anterior and inner portion of the muscle; it receives muscular fibers which are directed obliquely from above downward and from without inward and passes beneath the cruciate ligament to the dorsal surface of the great toe. The muscle is supplied by the deep branch of the peroneal nerve. It extends the great toe. The extensor digitorum (communis) longus (Figs. 306 and 315) is the outermost muscle ) the group, and is stronger than the extensor hallucis, which it otherwise resembles. The per portion of this muscle is narrow and arises from the upper end of the fibula between the longus and the tibialis anterior, but its greater portion arises from the anterior border 224 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 308.—The muscles of the dorsum of the foot. The compartments of the cruciate ligament have been opened and the tendons of the long extensors cut off shortly before their insertions. ' Fic. 309.—The plantar aponeurosis. Fic. 310.—The superficial layer of the plantar muscles. The plantar fascia has been largely removed from the surface of the flexor digitorum brevis. brane. The upper portion of the muscle is adherent to the origin of the tibialis anterior and to the deep fascia of the leg. ‘The tendon is situated in the anterior margin of the muscle and receives the middle and inferior fibers, which pursue a course similar to those of the extensor hallucis. During its passage through the cruciate ligament or just above it, the tendon sub- divides into four flat, rather weak tendons, which run to the dorsal aponeuroses of the second to the fifth toes. : The peroneus tertius (Figs. 306 and 315) seems to be a part of the extensor digitorum. It arises from those fibers of the latter muscle which come from the lower portion of the fibula; its flat tendon runs beneath the cruciate ligament with those of the extensor digitorum and is inserted by means of a flat tendinous expansion into the dorsal surface of the fifth metatarsal bone. The extensor digitorum extends the four outer toes; and the peronzus tertius assists in producing dorsal flexion of the foot. Both muscles are supplied by the deep branch of the peroneal nerve. THE MUSCLES OF THE FOOT. THE MUSCLES OF THE DORSUM. Unlike the back of the hand, the dorsal aspect of the foot is provided with two short extensor muscles. . The extensor hallucis brevis (Figs. 306, 308, and 315) is a small, flat, triangular muscle which is situated upon the dorsal surface of the bones, joints, and ligaments of the tarsus. It arises in common with the extensor digitorum brevis, with which it is adherent, from the dorsal — surface of the calcaneus, passes forward and inward, and in the region of the base of the first — metatarsal bone becomes continuous with a flat narrow tendon which runs over the metatarsal bone beneath the tendon of the extensor longus, the two tendons together forming the dorsal — aponeurosis. c The extensor digitorum brevis (Figs. 306, 308, and 315) arises together with the preceding muscle from the dorsal surface and the adjacent portion of the lateral surface of the calcaneus, and subdivides into three (rarely four) muscular bellies which terminate in very slender tendons passing to the second, third, and fourth toes, and fusing with the tendons of the extensor digi- torum longus to form dorsal aponeuroses. Both muscles upon the dorsum of the foot are supplied by the deep peroneal nerve. They extend the toes. A tendon for the little toe is rarely present. Ole Bhs O08 Sty ‘806 “31-4 < snduoj -anpjoy 4osuajxa fo yjoays uopuay < dayUD S1]DIQH fo yspays uopuay x snduop “p3ip sosuapxa Jo yyoays uopusy aA001d 4 4vyunjd jDUsIIXA ynavurjas “uosad fu] IAOOLS ‘Ju0} sojunjd pousayuy snapuoid fo uopua | “ADM q snapuosad fo uopua | yup s1ypiqy fo uopuay ‘WI snavuosa fo uopua ] JASSOdOJU1 SION}JOY 40XI)}-4~ ‘]Ds40q] STONTDY SaJISMU JVILQUIN] 4opnpqn fo _—l ‘Juop “1/04 : 2 [0 ‘Buoy anyyoy 7" ste a 4oxaf fo ‘Juop “piwip . wopual ~~ dosuajxa fo suopua {” snduo} -drp 4oxyfe fo uopuay sasainauodp a THE MUSCLES OF THE FOOT. 225 THE MUSCLES OF THE SOLE OF THE FOOT. The muscles of the sole differ materially from those of the palm, since in addition to the groups for the great and little toes there is also a central muscular mass. This central group is formed by the flexor digitorum brevis and the quadratus planta, an accessory head of the flexor digitorum longus which arises in the foot. The superficial muscles of the sole are covered by the plantar aponeurosis (plantar fascia) (Fig. 309) (see page 233), with which they are partly _ adherent. THE MUSCLES OF THE MIDDLE OF THE SOLE OF THE FOOT. The flexor digitorum brevis (Fig. 310) is a thick elongated muscle entirely covered by the plantar fascia, and forms the middle plantar eminence (sce page 233) (Fig. 309). It arises by a short tendon from the inner tubercle of the calcaneus and from the plantar fascia, with which the entire proximal half of the muscle is adherent. Just in front of the middle of the sole it subdivides into four bellies, terminating in four flat tendons, which behave in exactly the same manner as do those of the flexor digitorum sublimis in the hand, ¢. e., they are per- forated by the tendons of the flexor longus in the region of the proximal phalanges and are inserted chiefly into the second phalanges. The posterior portion of the flexor digitorum brevis is in immediate relation with the two abductors (hallucis and digiti V) which form the middle and external plantar eminences (Fig. 309), and the origin of the muscle is especially adherent to the abductor hallucis. Its anterior portion covers the tendons of the flexor digitorum longus and the lumbricales and is in relation on either side with the short muscles of the great and little toes. The muscle is supplied by the internal plantar nerve. The quadratus planta, also termed the flexor accessorius and the caro quadrata Sylvii (Fig. 311), may be regarded as a plantar head of the flexor digitorum longus. It is situated ‘upon the dorsal surface of the flexor brevis and is entirely covered by the latter muscle. It takes origin by means of two heads, of which the inner is usually the stronger, from the plantar surface of the calcaneus and from the long plantar ligament, and the flat and approximately ‘quadrangular muscle inserts into the outer margin of the tendon of the flexor longus digitorum it passes obliquely across the sole of the foot from within outward and from behind forward. The insertion occurs before the flexor longus tendon has subdivided into its four digital slips and after it has crossed the tendon of the flexor hallucis. At the crossing of these tendons they assume their proper positions (see page 222) and are always connected by anastomotic fibers. e the tendon of the flexor hallucis runs in the long axis of the toe, and consequently in the axis of traction, those of the flexor digitorum pursue an oblique course as above described and deviate from the axis of traction by about 30 degrees. _ The quadratus planta is supplied by the external plantar nerve. It converts the oblique axis of traction of the endons of the flexor digitorum longus into a straight one and increases the traction upon the tendons. 226 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 311.—The middle layer of plantar muscles. The flexor digitorum brevis, the abductor hallucis, and the abductor digiti quinti have been removed; the tendon. sheaths of the digits and of the peronzus longus have been opened. Fic. 312.—The deep layer of plantar muscles. The tendons of the flexor digitorum longus, the flexor hallucis longus, and the quadratus plant have been removed. THE MUSCLES OF THE BALL OF THE GREAT TOE. The muscles of the ball of the great toe differ from those of the thenar eminence not only in their number but also in the fact that one of them arises from the posterior extremity of the calcaneus and the other two from the anterior portion of the tarsus. The ball of the great toe consequently contains one long and two short muscles, while all four muscles of the thenar eminence are practically of the same length, on account of the shortness of the carpus. The abductor hallucis (Fig. 310) is a long, triangular, penniform muscle which occupies the entire inner margin of the foot and whose origin is situated immediately alongside of that of the flexor digitorum. It forms the internal plantar eminence (Fig. 309) and arises from the inner tubercle of the calcaneus from the adjacent portion of the inner surface of that bone, from the laciniate ligament, and also from the plantar aponeurosis, which covers the muscle completely by the radiations of its middle portion. Soon after its origin, a flat strong tendon develops in the middle of the muscle, which is inserted by means of the internal sesamoid bone into the first phalanx of the great toe and into its dorsal aponeurosis. The flexor hallucis brevis is situated between the tendons of the abductor hallucis and flexor hallucis longus. The muscle is supplied by the internal plantar nerve. Its chief function is the abduction of the great toe.* The flexor hallucis brevis (Figs. 311 and 312) is much shorter than the abductor. It arises partly from the plantar surfaces of the middle and external cuneiform bones and partly from the tendinous prolongations of the long plantar ligament which form the sheath of the peroneus longus. Like the flexor pollicis brevis, the insertion of the muscle divides into two slips, between which passes the tendon of the flexor hallucis longus. The inner slip, together with the adductor hallucis, passes into the tendon of the internal sesamoid bone; the outer slip, together with the adductor hallucis, passes to the external sesamoid bone. The outer margin of the muscle is in relation with the abductor, the inner with the adductor hallucis. The muscle flexes the great toe and is supplied partly by the internal plantar nerve and partly by the external plantar nerve. The adductor hallucis (Fig. 312) is a distinctly bicipital muscle and the two heads do not unite until they almost reach the insertion. The oblique head is a round, strong, elongated muscle arising from the plantar surface of the external cuneiform bone, in common with and partly adherent to the flexor hallucis, from the bases of the second and third metatarsal bones, * The marked development of most of the muscles of the great and little toes, in spite of the limited range of motion of these digits within the usual coverings of the foot, allows of the conclusion that these muscles not only move the toes, but that they play an important réle in supporting the arch of the foot, especially since the abductor digiti V does not extend to the toe at all, but is inserted into the practically immovable fifth metatarsal bone. . | | k ‘TIE Sy We F14 ynXuo} swnppoy 4oxayf fo uopuay < snduop sranpoy sox Jo uopur] ‘od syoiqyy fo uopuays < saJuoy wnsopdrp soxmf fo uopua] smduoy wnsondyeg 4oxayf fo vopusy ‘ysod sypiqy “ aoyunjd fo uopuay > -smypspone) x Staadg MITT PUD} SIAIMQ SNavUOsad snaouosad fo wopury penal fo uopua] “juw syojgn ow 7 . ‘By avjuvjd spittin < yuo j “Hyp 40x49} : y 7 A syoiqy fo uopua] ‘i 7 A Ap suasuoddg s14a4q SPIMI[OY 40xIJ | ‘Ip susuoddo be . sunpyoy / f A rd 4opsnpqno 4opnpqo 40, pqy sr ad fo wopuay ‘Buoy « fo wopu vo ip ree ra te soxaf fo suopuay SapooLiquiny ~e JO SUOpUIT ‘ ‘Sip SIU0G PIOWDSIS ly — sapopraquer fT * { 3 4oxaf fo suopuay h) Buoy 3p soxyf fo suopua] - \f *aaag “Srp ‘soxaf fo suopus f THE MUSCLES OF THE FOOT. 227 and especially from the anterior extremity of the long plantar ligament (see page 141). The broad muscular belly is at first situated in the middle of the sole, covering the plantar interossei, and it then passes inward toward the external sesamoid bone of the great toe, and in this situation _ unites with the weaker éransverse head. This arises by a purely muscular origin from the plantar aspect of the tarsometatarsal joints of the second to the fifth toes; it remains muscular until its insertion, while the oblique head usually exhibits an aponeurosis before reaching this point. Both heads are inserted together into the first phalanx of the great toe, the tendon of insertion containing the external sesamoid bone. The adductor hallucis is supplied by the external plantar nerve. Its chief function is adduction of the great toe. THE MUSCLES OF THE BALL OF THE LITTLE TOE. The muscles of this group correspond to those of the hypothenar eminence both in number and in function, but the abductor is much longer than the other two muscles. The abductor digiti quinti (Fig. 310) resembles the abductor hallucis not only in its posi- tion but in many other respects. It forms the external plantar eminence, and is thick and broad behind and narrow and tendinous in front. It arises by a short tendon from the outer tubercle of the calcaneus beside the flexor digitorum brevis, and also quite extensively from the plantar Aponeurosis, which covers the greater portion of the muscle. The insertion is partly into the tuberosity of the fifth metatarsal bone and partly into the outer border of the first phalanx of the little toe. The inner margin of the abductor digiti V is in relation with the flexor digitorum brevis behind and with the flexor digiti V brevis in front. It is supplied by the external plantar nerve. Its special function is abduction of the little toe. The flexor digiti quinti brevis (Figs. 310 and 311) is a small elongated muscle which arises chiefly from the anterior portion of the long plantar ligament (see page 141) and is inserted by a short tendon into the first phalanx of the little toe. It is in relation externally with the third plantar interosseous muscle. The opponens digiti quinti (Fig. 311) is smaller but somewhat broader than the flexor brevis, the two muscles having a common origin. It inserts into the outer border of the anterior portion of the fifth metatarsal bone, extending forward almost as far as the head. The muscle is almost entirely covered by the abductor digiti V. The flexor and opponens digiti V are supplied by the external plantar nerve. Their chief functions are indicated by their names. THE INTEROSSEI PEDIS. There are, as in the hand, four dorsal and three plantar interossei (Figs. 312 to 314); the former arise by two heads, the latter by one. The difference between the hand and the foot consists in the fact that not the middle but the second toe receives the tendons of two dorsal interossei (the first and the second), while the third and the fourth pass from the outer side into extensor tendons of the third and fourth toes (Fig. 313). The inner head of the first dorsal iterosseous is poorly developed; it arises only from the base of the first metatarsal bone and rom the ligaments of the tarsometatarsal joint, not from the shaft of the bone. 228 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. The plantar interossei (Fig. 314) are stronger than the dorsal. They arise from the outer borders of the three outer metatarsal bones and pass to the same borders of the corresponding toes. The interossei pedis are supplied by the external plantar nerve. ‘Their functions are the same as those of the palmar interossei, with certain modifications dependent upon the difference in their position (see page 203). THE LUMBRICALES. The lumbricales (Fig. 311) of the foot arise from the tendons of the flexor digitorum longus; the first lumbricalis has a single origin from the inner margin of the first tendon and the other Fic. 313.—Diagram of dorsal interossei of the foot. Fic. 314.—Diagram of the plantar interossei of the foot. — three have a bicipital origin. In the vicinity of the metatarsophalangeal joints, they pass from the inner side into the dorsal aponeuroses of the toes. At their insertions are usually situated small burs, the Jumbrical burse. | These muscles are supplied in a variable manner partly by the external plantar nerve and — partly by the internal plantar nerve. Their functions are similar to the corresponding muscles — in the hand (see page 203). m, peroneus brevis m. £p NeUS loneus > ~- cri . THE MUSCLES OF THE FOOT. 229 THE SYNOVIAL SHEATHS OF THE FOOT. Like the tendons of the muscles of the forearm, the muscles of the leg run in synovial sheaths as they pass into the foot. The retinacula of these synovial sheaths are formed partly by rein forcements of the deep fascia and partly by processes of the ligaments of the for Upon the dorsum of the foot (Fig. 315) are situated thre synovial sheaths; one for the tibialis anterior, one for the extensor hallucis longus, and a common one for the tendons of th Extensor digitorum longus + Peronaus III Extensor hallucis longus Fibula ‘ A ‘ chim extensor digitorum longus and peronveus tertus. They commence in the leg and extend for a variable distance upon the dorsum of the foot. Their retinac ulum is chiefly formed by a rein- forcement of the dorsal fascia of the foot, the cruciate (anterior annular) ligament, which arises } irom the outer surface of the calcaneus, where it js adherent to the interosseous talocalcanea] ligament, and divides into a distal and a proximal band which form almost a right angle with each other (Fig. 306). The proximal band runs to the internal malleolus, the distal to the dorsal Surfaces of the navicular and internal cuneiform bones, and when the latter band is prolonged 230 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. to the external malleolus, as sometimes occurs, the ligament presents a cruciform appearance. The outer undivided half of the ligament is connected at its origin with the inferior peroneal retinaculum and the ligament contains three compartments separated by fibrous partitions, for the three synovial sheaths. At the outer side of the ankle-joint the two peroneal muscles (longus and. brevis) have a common synovial sheath (Fig. 315), the upper and lower portions of which are usually sub- divided for a short distance. This sheath is held in place by two retinacula which are frequently indistinctly separated. The superior peroneal retinaculum (Figs. 307 and 315) passes from Hit ---- Tendon-sheath of tibialis posterior if -~ Tendon-sheath of flexor digitorum po a eae ‘4 iN Tendon-sheath of ios i a sil extensor hallucis Tendon-sheath of extensor hallucis longus J ’ longus 1 Sf SH. \\ Bia --Calcaneal tendon ‘ / / / i Tendon of flexor hallucis Tendon-sheath 7. j Abductor hallucis X long. of flexor digi- Tendon-sheath Flexor digit. brevis X torum long. of tibialis posterior Fic. 316.—The tendon-sheaths and retinacula of the internal border of the foot (somewhat diagrammatic). the posterior border of the internal malleolus to the upper extremity of the tuberosity of the calcaneus, and is also connected with the deep fascia of the leg. The injerior peroneal retinacu- lum (Figs. 307 and 315) extends from the outer extremity of the cruciate ligament to the outer surface of the calcaneus and its trochlear process. At the inner side of the ankle-joint (Fig. 316) there are three synovial sheaths for the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus. The sheath for the tibialis posterior is the shortest and extends only to the inner border of the foot. The two remaining sheaths are continued into the sole of the foot and extend as far as the decussation of the tendons. THE FASCLE OF THE LOWER EXTREMITY. 231 These sheaths are held in place by the laciniate (internal annular) ligament (Figs. 305 and 316), a wide, poorly defined band which commences at the internal malleolus and passes partly to the inner and upper border of the calcaneus and partly to the plantar surface of the foot as far for- ward as the navicular bone. It contains three distinctly separated compartments for the three synovial sheaths. In the sole of the foot, in addition to the continuations of the synovial sheaths of the flexor hallucis longus and digitorum longus, there is situated the special synovial sheath oj the peroneus longus, which surrounds the tendon of this muscle in its passage across the sole within the groove of the cuboid (Figs. 311, 312, and 316) and almost to the point of its insertion.* This sheath is at first situated above (dorsal to) the flexor digitorum brevis and the tendon of the longus, and its retinaculum is furnished by a prolongation of some of the fibers of the long plantar liga- ment which pass beyond the cuboid to the base of the metatarsal bones (see page 141). The flexor tendons of the toes also possess synovial sheaths which resemble those in the fingers, although they are correspondingly shorter and smaller. The longest sheath is usually _ that for the tendon of the flexor pollicis longus. The retinacula for these sheaths are the vaginal ligaments, which are analogous to the similar structures in the fingers (see page 205). . Within the synovial sheaths of the second to the fifth toes exactly the same relations obtain which we have previously observed in the fingers, since the weak tendons of the flexor digitorum _ brevis are perforated by the much stronger tendons of the flexor digitorum longus (see page 207). THE FASCL# OF THE LOWER EXTREMITY. The lower extremity is enveloped in a very strong fascia (Figs. 317 to 320) which is unus- ually thick in certain situations. In the different regions of the extremity this fascia receives corresponding names, and we consequently speak of the iliac fascia the fascia lata, the crural fascia, the dorsal fascia of the foot, and the plantar aponeurosis. THE ILIAC FASCIA. The iliac jascia covers the anterior surface of the iliopsoas above the inguinal ligament. _ At the inner margin of the psoas major this fascia is continuous with the pelvic fascia; at the _ Outer margin it passes into the thigh with the iliopsoas and joins the pectineal fascia to form - the iliopectineal jascia, a portion of the fascia lata (see page 232). In doing this the fascia is attached to the anterior superior spine of the ilium, to the inguinal ligament, and to the iliopec- t eal eminence (the iliopectineal ligament) and divides the space beneath the inguinal ligament into two compartments, an outer compartment for the iliopsoas and the femoral nerve, the lacuna musculorum, and an inner one for the femoral vessels, the Jacuna vasorum. The iliac fascia is ectly continuous with the transversalis fascia (see page 163). The lacuna vasorum is rounded off and bounded internally by the lacunar (Gimbernat’s) ligament (see page 164), and forms THE FASCIA OF THE THIGH, FASCIA LATA. The jascia lata (Figs. 317 and 318) consists of two layers which are separated only in certain tions, and its different portions vary greatly in thickness. It is composed of longitudinal _ * Within this sheath A ie of the peronzus longus develops a sesamoid bone (or cartilage). 232 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. Fic. 317.—The fascia of the thigh seen from in front. Fic. 318.—The fascia of the thigh seen from behind. Fic. 319.—The fascia of the lower leg seen from behind. Fic. 320.—The fascia of the lower leg, seen from in front, and the dorsal fascia of the foot. and transverse fasciculi which are so arranged that sometimes one set and sometimes the other preponderates, or both may occur together. In a general way the posterior portion of the fascia lata is stronger than the anterior and the external portion is decidedly thicker than the internal. Upon the posterior surface of the thigh the very thin superficial layer of the fascia lata covers the gluteus maximus, while the deep layer passes beneath the muscle, and over that portion of the gluteus medius which is not covered by the maximus, the fascia assumes a markedly tendinous or aponeurotic character and is termed the gluteal jascia (Figs. 238, 240, and 241). In the gluteal sulcus (Fig. 318), over the lower portion of the gluteus maximus, the fascia con- tains numerous strong transverse fasciculi, and over the flexor muscles it is of average thickness and is composed chiefly of transverse fasciculi which are especially well marked in the popliteal region, where the superficial layer of the fascia lata covers in the popliteal space and its con- tents, the deep layer enveloping its muscular margins. ; The strongest portion of the fascia lata is situated upon the outer side of the thigh and is known as the iliotibial (or Maissiat’s) band (Figs. 296 and 318). ‘This band is composed chiefly of strong tendinous longitudinal fasciculi and receives the insertion of the tensor fasciz late* and of a portion of the gluteus maximus (see page 211). Its lower extremity is attached to the external tuberosity of the tibia, and beneath it is situated the vastus lateralis with its large aponeurosis. In the lower portion of the thigh the fascia lata gives off a septum upon either side, and these pass between the femoral muscles to the lips of the linea aspera, forming the internal and external intermuscular septa. Just below the inguinal ligament the fascia lata is composed of two layers. The superficial layer passes over the anterior surface of the sar- torius and the great femoral vessels; the posterior goes behind the sartorius and covers in the iliopectineal fossa (see page 210) and the groove between the vastus medialis and the adductors. Over the adductor muscle the fascia is very thin and transparent. ‘The portion of it covering the pectineus is also called the pectineal jascia; it unites with the lower extremity of the iliac jascia to form the ilzo pectineal jascia covering the floor of the iliopectineal fossa. Immediately below the inguinal ligament the superficial layer of the fascia lata exhibits a free internal margin, the falcijorm margin (Fig. 317), which, together with the pectineal fascia, bounds a round or oval depression in the fascia lata, the oval jossa (saphenous opening). The inferior portion of the falciform margin, which passes almost imperceptibly into the pectineal fascia, is called the zujferior cornu, while the superior portion, extending upward to the lacunar ligament, is termed the superior cornu. The opening of the oval fossa is covered by a portion of the superficial layer, the cribriform fascia, which contains a considerable quantity of fat and quite a number of foramina, the largest of which gives passage to the great saphenous vein (the internal saphenous vein). This vein comes from the foot and leg, runs upon the fascia lata, and * The surface of the tensor fasciz late is also covered by a very thin layer of the fascia lata. ee --- Clateal fascia Inguinal Folciform margin ligament / Subcutaneous inguinal ring “Femoral yein el Oval fossa latae) Pectineal fascia 4 ~_{" Great saphenous V.< "vein YY (Tensor fasciae latac) Gluteai Sulcus .---~ ‘bend aa Hiotibial band Subcutaneous Prepatellar bursa “ ee , v4 — a —_—_ « Subcutaneous infra- : ——— patellar bursa — . = - ~ _. => . ~~Subcutanecous prepateliar bursa ae ~ Popliteal fossa Subcutaneous infrapatellar bursa a oat’ amit er (ige '08 oe . epee? peri n ‘ vowel: 7 _. Transverse crural lig. _... Crudate ligament ----- Calcaneal tendon Dorsal fascia-—---- of foot Fig. 319. Fig. 320. uw THE BURS OF THE LOWER EXTREMITY. 233 empties into the femoral vein, which is situated in the region of the oval fossa. The oval fossa (the saphenous opening) is the external or subcutaneous femoral ring and the external orifice of the femoral canal. (For a more detailed description the reader is referred to the text-books and atlases of topographic anatomy.) THE FASCIA OF THE LEG, FASCIA CRURIS. The jascia cruris (Figs. 319 and 320) envelops the muscles of the leg, but is wanting over the inner surface of the tibia; it is thickest anteriorly below the knee, where it is adherent to the extensors, the peronei, and the tendons of the pes anserinus. It gives off the anterior intermuscular sepium, which passes between the extensors and the peronei to the anterior border of the fibula, and the posterior intermuscular se plum, which passes between the peronei and the flexors to. the posterior border of the fibula, and its upper and inner portion is adherent to the pes anserinus (see page 219). “posterior aspect of the leg it divides into a superficial and a deep layer, the former cover- ‘ing the triceps sure, the latter the deep group of flexors; the triceps sure and its tendon, ‘the tendo Achillis, are consequently completely invested by this fascia. In addition to the previously described retinacula (see page 230) the fascia cruris is especially reinforced by the transverse crural ligament, which is composed of transverse fasciculi passing from the tibia to the fibula above the ankle. It is situated to the proximal side of the cruciate ]j becomes continuous. Upon the gament, with which it gradually THE FASCL£ OF THE FOOT. While the dorsal fascia of the foot (Fig. 320) is an exceedingly thin layer, the plantar aponeurosis (Fig. 309) is the thickest portion of the entire fascia of the leg. In the middle of the sole it consists ofa very thick aponeurotic layer, composed chiefly of longitudinal fasciculi with some fibers which pass obliquely toward the lateral margins of the foot. The proximal portion of the aponeurosis arises from the inner and outer tubercles of the calcancus and is closely adherent to the long muscles of the foot which take their origins from the same bony points; it is considerably thicker than the broader distal portion. The aponeurosis together with the long muscles forms the three plantar eminences (internal, middle, and external; see pages 225 to 227). Its lateral portions are much weaker than the central portion, and the thickest part of the lateral portion is situated over the origin of the abductor digiti V. Numerous slender fasciculi pass from the entire margin of e aponeurosis to the skin, and toward the toes the aponeurosis divides into four slips, correspond- ing to the four outer toes, which are bound together by transverse fibers, the fransverse jasciculi. Upon the toes the aponeurosis gradually disappears in the connective-tissue layers of the skin. Both the fascia lata and the fascia cruris, like the fascia of the upper extremity, give passage ) vessels and nerves. THE MOST IMPORTANT BURS OF THE LOWER EXTREMITY. 1. The subcutaneous trochanteric bursa, the chief bursa upon the great trochanter. 2. The trochanteric bursa oj the gluteus maximus (see page 212, Fig. 295). 3- The gluteofemoral burse (see page 212, Fig. 295), inconstant. 234 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 4. The sciatic bursa oj the gluteus maximus, between the tuberosity of the ischium and the © gluteus maximus. 5. The anterior (trochanteric) bursa oj the gluteus medius, between the tendons of the gluteus medius and maximus. 6. The posterior (trochanteric) bursa of the gluteus medius, between the tendons of the gluteus medius and the piriformis (see page 212). 7. The trochanteric bursa of the gluteus minimus, at the insertion of the muscle of the same name into the great trochanter. . 8. The piriform bursa, at the insertion of the muscle of the same name into the great trochanter. g. The bursa of the obturatorius internus (see page 213, Fig. 301). 10. The bursa of the rectus femoris, at the origin of the muscle of the same name from the margin of the acetabulum. 11. The iliopectineal bursa (see page 211, Fig. 298) occasionally communicates with the hip-joint. | 12. The subtendinous iliac bursa, at the insertion of the iliopsoas into the lesser trochanter. _ 13. The pectineal bursa, at the insertion of the muscle of the same name. | 14. The superior bici pital bursa, at the origin of the long head of the biceps. 15. The injerior bicipital bursa, between the tendon of insertion of the biceps and the long external lateral ligament of the knee-joint. 16. The subcutaneous prepatellar bursa (see page 136, Figs. 317 and 320). . 17. The subjascial prepatellar bursa (see page 136). 18. The subtendinous prepatellar bursa (see page 136). 19. The suprapatellar bursa (see page 135) communicates almost always with the knee- joint. 20. The subcutaneous infra patellar bursa, in front of the upper extremity of the ligamentum patella (see page 136, Figs. 317 and 320). | 21. The deep injrapatellar bursa (see page 135). 22. The subcutaneous bursa of the tuberosity oj the tibia, a subcutaneous bursa over the tubercle of the tibia. 23. The sartorial bursa (see page 214, Fig. 298). 24. The anserine bursa (see page 219, Fig. 208). 25. The popliteal bursa (see pages 136 and 221) communicates with the knee-joint. 26. The internal gastrocnemial bursa (see pages 136 and 220, Fig. 303) also communicates ~ with the knee-joint. 27. The semimembranous bursa (see pages 136 and 219) may communicate with the knee- | joint. 28. The subcutaneous external malleolar bursa, subcutaneous bursa over the external malleolus. 29. The subcutaneous internal malleolar bursa, subcutaneous bursa over the internal mal-— leolus. 30. The bursa oj the sinus tarsi, in the interosseous ligament in the sinus tarsi between the ee 6 — ae THE BURS#® OF THE LOWER EXTREMITY. 2 falocrural and talonavicular articulations, may communicate with the articular cavity of the falocalcaneonavicular articulation. 31. The sublendinous bursa oj the tibialis anterior, at the insertion of the tendon of the tibialis anterior. 32. The subtendinous bursa oj the tibialis posterior, at the insertion of the tendon of the ‘ibialis posterior. 33- The subcutaneous calcaneal bursa, a subcutaneous bursa beneath the tuber calcanei. 34- The bursa of the calcaneal tendon, at the insertion of the tendo Achillis. 35. The intermetatarsophalangeal burse, corresponding to the intermetacarpophalangeal ‘1 n DJUTSd 36. The lumbrical burse (see page 228). [As in the case of the upper extremity, so too in the lower a classification of the muscles of each of the groups recog- zed above into post-axial and pre-axial sets can be made. Owing, however, to a rotation which the lower limb under- oes during its development, an inversion of its surfaces, as compared with those of the upper limb, occurs, so that the st-axial muscles of the thigh, leg, and foot are situated on the anterior surface and the pre-axial muscles on the posterior rface. Furthermore, there is not, in the nerve plexuses of the lower limb, that definite separation of the fibers of the ial and post-axial muscles into distinct cords, such as are found in the brachial plexus, but the pre-axial and post- lal fibers do not complete their separation, as a rule, until they have reached the lower third of the thigh, the division the great sciatic nerve into the tibial and peroneal nerves occurring at about that level, Bearing these facts in mind, 2 morphological classification of the muscles of the lower limb may be made as follows: I. THE MUscCLEs OF THE HIP. (a) Post-axial muscles: gluteus maximus, gluteus medius, gluteus minimus, and tensor jascia late. (6) Pre-axial muscles: iliacus, pirijormis, obturator externus, obturator internus, gemelli, and guadratus jemoris. II. THe Muscies oF THE THIGH. (a) Post-axial muscles: sartorius, quadriceps jemoris, and biceps jemoris (shorter head).* (b) Pre-axial muscles: pectineus, gracilis, adductor longus, adductor brevis, adductor magnus, adductor minimus, Ti branosus, semitendinosus, and biceps jemoris (long head). III. THe Muscies oF THE Lec. (a) Post-axial muscles: extensor digitorum longus, peronaus tertius, extensor hailucis longus, tibialis anterior, onus longus, and peroneus brevis. b) Pre-axial muscles: gastrocnemius, plantaris, soleus, popliteus, flexor digitorum longus, tibialis posterior, flexor cis longus, and quadratus plante.t IV. THe MUSCLES OF THE Foor, (a) Post-axial muscles: extensor digitorum brevis and extensor hallucis brevis. ‘Pre-axial muscles: flexor digitorum brevis, abductor hallucis, flexor brevis hallucis, abductor digiti quinti, oppo- Mi quinti, lumbricales, adductor hallucis, flexor brevis digiti quinti, and interossei.—Ep.} ET he biceps femoris really represents two muscles with a common insertion; its long head is a pre-axial muscle 's short head belongs primarily to the gluteal set of muscles. he quadratus plantzx, although situated in the foot, is nevertheless morphologically one of the muscles of the leg, derivative of the same muscle mass which gives rise to the flexor longus hallucis and the tibialis posterior. im ABDOMINAL fascie, 163 muscles, 157 anterior, 157 development, 164 development, 164 157 development, 164 erior, 162 Seeiaheent, 164 t, 161 Erereenent, 164 portion of pectoralis major muscle, 1 iP ag ring, external, 158 Abductor digiti quinti muscle, 220, 227 Das shaes on Lodo 210, 226 function of, 226 nerve supply of, 226 _ function of, 199 longus muscle, 185, 197 function of, 197 co.” nar a. 139 - ligaments, 12 babuler fossa, 96 , Dtch, 96 Sarees Ac ‘om extremity of clavicle, 85 Acromioclavicular articulation, 120 ke < ment, 120 Tron function of, 217 nerve supply of, 217 217 hal ucis muscle, 210, 226 function of, dope | nerve supply of, 227 ongus muscle, 209) 216 function of, 216 nerve supply of, 216 tion of, 217 — of, 200, 227 ove supply of, 200, 227 186, 210 pollicis brevis muscle, 186, 199 nerve supply of, 199 nerve supply of, 197 108 process, 84 dductor brevis muscle, 209, 216, 217 us muscle, 209, 216, 217 e supply of, 217 us — 209, 216, 217 INDEX Adductor minimus muscle, function of, 217 nerve supply of, 217 muscles of thigh, 216 opening, tendinous, 217 pollicis muscle, 186, 199 function of, 200 nerve supply of, 200 Aditus orbitw, 74 Adminiculum linex albx, 163 Al of ethmoid, 63 of ilium, 93, 94 surfaces of, 94, 95 vomeris, 39, 65 Alar folds of knee, 135 ligaments, 115 portion of a. muscle, 182 processes, 6 Alveolar sae of mandible, 71 canals, 67 foramina, 67 juga, 7% portion of mandible, 71 process, 37 of superior maxillary, 66, 68 Alveoli for teeth, 68, 71 Amphiarthrosis, 108 Anatomical neck of humerus, 85 Anatomy, definition, 17 descriptive, definition, 17 general, definition, 17 special, definition, 17 systematic, definition, 17 topographic, definition, 17 Anconeus lateralis muscle, 190 longus muscle, 189 ialis muscle, 190 muscle, 185, 190 function of, 190 nerve supply of, 190 quartus muscle, 190 function of, 190 nerve supply of, 190 Angiology, definition, 17 Angle, external, of scapula, 84 inferior, of scapula, 84 infrasternal, 35 internal, of ‘scapula, 84 mastoid, 59 occipital, ?? sphenoidal, 59 of ribs, 32 of scapula, external, 83 237 Angle of scapula, inferior, 83 internal, 83 superior, 83, 84 of sternum, 34 parietal, 50 pubic, 131 sphenoidal, 36 subcostal, 35 Angular head of quadratus labii su- perioris muscle, 150 Angulus sterni, 34 Ankle-joint, 137 ligaments of, 139 Annular ligament, 122 anterior, 127, 229 internal, 231 of palm, 205 posterior, 203, 208 Annulus tympanicus, 58 Anserine bursa, 219 Antagonist muscles, 143 Anterior abdominal muscles, 157 development, 164 annular ligament, 127, 229 arch of atlas, 25 of vertebra, 22 articular facet of calcaneus, 103 of tabes, 102 atlantooccipital membrane, 1 - belly of digastricus muscle, 1 capitular ligament, 136 clinoid process, 41, 49 condyloid canal, 40, 45 coronoid process of mandible, 72 costotransverse ligament, 116 cranial fossa, 41 crest of fibula, ror crucial ligament, 134 crus of subcutaneous inguinal ring, 159 ethmoidal forgmen, 61, 75 fontanelle, 81 luteal line, 94 inferior spine of ilium, 94 intercondyloid fossa, 99 intermuscular septum, 233 interoccipital synchondrosis, 47 intertransversarius muscle, 155 intraoccipital synchondrosis, 31 lachrymal crest, 67 layer of rete fascia, 156 ligament of external malleolus, 137 longitudinal ligament of vertebral column, 111 muscles of leg, 223 nares, 66, 76 238 Anterior nasal spine, 37, 68 obturator membrane, 115 tubercle, 95 pelvic surface, 96 pillar of subcutaneous inguinal ring, 159 portion of quadratus lumborum muscle, 163 sacral foramina, 28 sacrococcygeal ligament, 113 sacroiliac ligament, 129 superior spine of ilium, 94 surface of superior maxillary, 66 of thigh, muscles of, 214 of ulna, 87 talocalcaneal articulation, 138 ligament, 140 talofibular ligament, 140 talotibial ligament, 139 trochanteric bursa of gluteus me- dius, 234 Anteroexternal surface of humerus, 86 Anterointernal surface of humerus, Antibrachial fascia, 207 Antrum of Highmore, 66 tympanic, 54, 58 Aortic opening of diaphragm, 165, 166 Apertura piriformis, 37, 65, 66, 7 Aperture of aquzductus vestibuli, ex- ternal, 55 of pelvis, inferior, 131 superior, 130 of tympanic canaliculus, superior, 54 Apex of fibula, ror of patella, 99 of pyramid of temporal bone, 55 Apical odontoid ligament, 115 Aponeurosis, 143 palmar, 198, 207, 208 Apophyses, 20 Appendicular skeleton, 22 Aqueductus cochlez, orifice of, 56 vestibuli, aperture of, external, 55 Arch, costal, 33 lumbocostal, external, 165 internal, 165 of Haller, 165 of soleus, 220 of vertebrie, 22, 23 ligaments between, 112 pubic, 131 superciliary, 60 tendinous, 143 zygomatic, 38, 39, 40 Arcuate eminence, 54 ligament, 128 external, 156, 165 internal, 165 line, 95 popliteal ligament, 135 Arm, bones of, 85 upper, extensor surface of, muscles of, 189 flexor surface of, muscles of, 188 INDEX. Arm, upper, muscles of, 185, 188 classification, 209 Artery, vertebral, 25 canal for, 26 Arthrodia, 110 Articular capsules, 108 of hip-joint, 132 of phalanges of foot, 137 of hand, 127 cartilages, 21, 108 circumference of radius, 88 of ulna, 88 crest of sacrum, 29 discs, 108, 118 of elbows, 123 eminence, of occipital bone, 4o of temporal bone, 53 margins, 108, 109 processes, 20 of sacrum, superior, 29 of vertebrze, 23 surfaces of calcaneus, 103 of patella, 99 of radius, carpal, 89 of tibia, inferior, 100 superior, 99 Articularis genu muscle, 215 subcrureus muscle, 215 Articulations, 107, 108 acromioclavicular, 120 ankle, 137 atlantoaxial, 113, 115 atlantoepistrophic, 113 atlantooccipital, 113, 115 ball-and-socket, 110 biaxial, 110 bilocular, 108 calcaneocuboid, 137, 138 carpometacarpal, common, 124, 125 of thumb, 124, 125 Chopart’s, 138 cochlear, 109 compound, 109 condyloid, 110 costotransverse, 116 coxal, 131 cuneonavicular, 137, 138 digital, 128, 137, 139 ellipsoidal, 110 gliding, r10 hinge, 109 hip, 131 humeroradial, 122 humeroulnar, 122 intercarpal, 124 interchondral, 117 intermetatarsal, 137, 139 interphalangeal, 128, 137, 139 intertarsal, 137 intervertebral, 111 Lisfranc’s, 139 metacarpophalangeal, 127 of thumb, 127 metatarsophalangeal, 137, 139 of astragalus, 137 of atlas, 113 of axis, 113 | Articulations of carpus, 124 Astragalus, 102. Atlantoaxial articulations, 113, T15 Atlantoepistrophic articulations, 113 Atlantooccipital articulation, 113, 115 Atlas, 23, 25 of costal cartilages, 117 of elbow, 122 of fibula, 136 of fingers, 127 of first and second cervical verte- presi of foot, 137 of hand, 124 of head, 117 of knee, 133 of pelvic girdle, 128 of phalanges of foot, 157 of hand, 127 of pisiform bone, 124, 125 of ribs with sternum, 116, 117 with vertebral column, 26, 116, m7 of sacrum, 113 of shoulder, 121 of sternum with ribs, 116, 117 of talus, 137 of tibia, 136 of toes, 137 of upper extremity, 119 of vertebral column, 110 with ribs, 26, 116, 117 of wrist, 124 pelvic, 128 pivot, 109 polyaxial, 110 radiocarpal, 124 radioulnar, distal, 123 proximal, 122 sacroiliac, 128 saddle, 110 simple, 109 spheroid, 110 spiral, 109 sternoclavicular, 119 sternocostal, 117 talocalcaneal, 137, 138 talocalcaneonavicular, 137, 138 talocrural, 137 talonavicular, 138 tarsal, 137, 138 tarsometatarsal, 137, 139 temporomandibular, 118 tibiofibular, 136 transverse, of tarsus, 138 trochoid, 10g true, 108 uniaxial, 109 with longitudinal axis, 109 with transverse axis, 109 unilocular, 108 See also Talus. membrane, 115 anterior, 115 posterior, II5 articulations of, 113 development of, 31 lateral masses of, 25 transverse ligament of, 114 Attollens auricula muscle, 179 ttrahens auricula muscle, 179 Auditory canal, internal, 55 foramen, internal, 55 meatus, external, 35, 40 internal, 43 Auricular surface of ilium, 95 of sacrum, 29 Auricularis anterior muscle, 178, 179 muscle, 178 functions of, 179 nerve supply of, 179 ‘posterior muscle, 178, 179 _ superior muscle, 178, 179 Axial skeleton, 22 Axillary border of scapula, 84 fascia, 207 fossa, 147 _ margin of scapula, 83 Axis, 23, 2 articulations of, 113 dens of, 25 development of, 31 odontoid process of, 25 Back, fascia of, 156 muscles of, 144 development of, 156 flat, 145 development, 156 long, 149 development, 156 short, 154 P development, 156 Ball of great toe, muscles of, 226 of little toe, muscles of, 227 -and-socket joint, 110 Basal ligaments, dorsal, 127, 141 interosseous, 127 ee I41 tar, I41 _ volar, 127 Base of mandible, 71 of metacarpal bones, o1 ae ape bones, 105 patella, 99 of phalanges of fingers, 92 of toes, 105 _ of scapula, 83 Basilar portion of occipital bone, 40, pharyngeal canal, 49 cranii externa, 39 ly of muscle, 142 irticular muscles, 142 al joints, 110 seps brachii muscle, 185, 188 function of, 189 nerve supply of, 189 tendon of long head of, 121 femoris muscle, 209, 218 unction of a : nerve supply of, 21 hat’ Fades, 182, 183 al bursa, inferior, 234 SUperor, 234 sroove, ena, 188, 207 >. INDEX. Bicipital groove, internal, 188, 207 of humerus, §5 ridges, 86 Bicipitoradial bursa, 189 Bifurcate ligament, 140 Bilocular joints, 108 Bipenniform muscles, 142 Bipinnate muscles, 142 Biventer cervicis muscle, 152 mandibulaw muscle, 174 muscle, 142 Bloodvessels of bones, 21 Bone-cartilage, 20 Bone-marrow, 21 Bones, 19 bloodvessels of, 21 broad, 19 calcined, 20 composition of, 20 development of, 21 flat, 19 heads of, 20 inorganic constituents of, 20 irregular, 20 long, 19. See also Long bones. macerated, 20 membranous, 21, 22 neck of, 20 nerves of, 21 nutrient canals of, 20 organic constituents of, 20 pneumatic, 19 short, 19 tissue of, 20 tubular, 19 visceral, 22 Bony locking mechanisms, 108, 109 pelvis, 93 tissue, 20 Brachial fascia, 207 Brachialis muscle, 185, 189 function of, 189 nerve supply of, 189 Brachioradialis muscle, 185, 194 function of, 195 nerve supply of, 195 Branchiomeric muscles, 184, 185 Breast-bone, 22, 34. See also Ster- num. Broad bones, 19 Buccal fat mass, 182, 183 Buccinator crest, 73 muscle, 180, 181 Buccopharyngeal fascia, 184 Bulbus ven jugularis superior, 56 Bursa, anserine, 210, 234 bicipital, inferior, 234 superior, 234 bicipitoradial, 189 calcaneal, subcutaneous, 235 coracobrachial, 208 cubital interosseous, 208 digital, dorsal subcutaneous, 208 gastrocnemial, internal, 136, 220, 234 gluteofemoral, 212, 233 iliopectineal, 133, 234 infrapatellar, deep, 135 subcutaneous, 136, 234 Burs#, infraspinatus, 208 intermetacarpophalangeal!, 209 intermetatarsophalangeal, 235 intratendinous olecranal, 205 latissimus, 146 lumbrical, 228 malleolar, subcutaneous 234 internal, 234 metacarpophalangeal, dorsal sub- cutaneous, 205 mucous, 143 of calcaneal tendon, 235 of extensor carpi radialis brevis, 208 of flexor carpi radialis, 209 ulnaris, 208 of glutaus maximus, sciatic, 234 trochanteric, 212, 233 medius, anterior trochanteric, 234 posterior, 212 trochanteric, 212, 234 minimus, trochanteric, 234 of latissimus dorsi, 146 of lower extremity, 233 of obturator internus, 213 of obturatorius internus, 213, 234 of rectus femoris, 234 of semimembranosus muscle, 219 of sinus tarsi, 234 of teres major, 208 of tibialis anterior 235 posterior subtendinous, 235 of tuberosity of tiba, subcutaneous, 234 of upper extremity, 208 olecranal, 208 pectineal, 234 piriform, 234 popliteal, 136, 220, 221, 234 prepatellar, subcutaneous, 136, 234 subfascial, 136 subtendinous, 136 sartorial, 214, 234 sciatic, of glutwus maximus, 234 semimembranous, 136, 219, 234 subacromial, 208 subcutancous epicondylar, 208 olecranal, 208 subdeltoid, 186, 208 subscapular, 121, 188 subtendinous iliac, 234 olecranal, 208 suprapatellar, 135, 234 synovial, 10S communicating, 108 trochanteric, 212 anterior, of glutwus medius, 234 of glutwus minimus, 234 maximus, 212, 233 posterior, of glut@us medius, 212, 234 subcutaneous, 233 external, subtendinous, CALCANEAL bursa, subcutaneous, 235 tendons, 220 bursa of, 235 240 Calcaneocuboid articulation, 137, 138. ligament, 141 plantar, 141 Calcaneofibular ligament, 140 Calcaneonavicular ligament, 141 dorsal, 140 plantar, 141 Calcaneotibial ligament, 139 Calcaneus, 102, 103 articular surfaces of, 103 body of, 103 development, 106 facets of, 103 groove of, 103 surfaces of, 103 Calf muscles, 219 Calvaria, inner aspect of, 44 Canal, adductor, 217 alveolar, 67 auditory, internal, 55 basipharyngeal, 49 carotid, 55, 58 external orifice of, 40 condyloid, 40, 45 anterior, 40, 45 posterior, 40 dental, inferior, 72 facial, 56, 57 geniculum of, 57 for vertebral artery, 26 vein, 26 Hunter’s, 217 hypoglossal, 40, 45 infraorbital, 67 entrance of, 75 inguinal, 159 mandibular, 72 musculotubar, 55, 58 nasal, 75 nasolachrymal, 64, 67, 75 nutrient, of arm, 87 of bones, 20 of radius, 89 of temporal bone, 57 palatine, 69 pharyngeal, 49, 51 pterygoid, 50, 78 pterygopalatine, 51, 69 sacral, 29 spinal, 31 vertebral, 31 vidian, 50 Canaliculi, caroticotympanic, 53 Canaliculus chorde tympani, 57 cochlez, orifice of, 56 mastoid, 58 tympanic, 58 Canalis vertebralis, 31 Canine fossa, 66 Caninus muscle, 181 Capitular ligament, anterior, 136 posterior, 136 transverse, of foot, 139 of hand, 127 Capitulum of humerus, 86 of ulna, 88 Capsules, articular, 108 of hip-joint, 132 | INDEX. Capsules, articular, of phalanges of foot, 137 of hand, 127 Caro quadrata Sylvii muscle, 22: Caroticotympanic canaliculi, 56, 58 Carotid canal, 55, 58 external orifice of, 40 foramen, external, 56 internal, 55 fossa, 172, 174 groove, 41, 48 tubercle, 26 Carpal articular surface of radius, 89 bones, 82, 89 articulations of, 124 central, 91 development, 91 supernumerary, Qt surfaces of, go, gt eminence, radial, go ulnar, 90 groove, 90 ligaments, 126 dorsal, 203, 208 extensor tendon sheaths neath, 203 radiate, 127 transverse, 127, 205 volar, 208 Carpometacarpal articulation, com- mon, 124, 125 of thumb, 124, 125 ligament, dorsal, 127 volar 127 Carpus, 89 articulations of, 124 ligaments of, 126 Cartilages, 21 articular, 21, 108 bone, 20 costal, 33 articulations of, 117 interarticular, 108 semilunar, 133 functions of, 136 Cavities, glenoid, 84, 121 nasal, 76 oral, roof of, 78 orbital, 73 pelvic, 130 Cells, ethmoidal, 63, 64 frontal, 63 lachrymal, 63, 65 mastoid, 53 maxillary, 63, 67 palatine, 63, 70 sphenoidal, 63 Centers of ossification, 21 Central carpal bone, 91 tendon of diaphragm, 164, 165 Cerebral juga, 41 of sphenoid bone, 50 surfaces of frontal bone, 41, 60 of orbital plates, 61 of parietal bone, 59 of sphenoid bone, 42, 49 of temporal bone, 52 Cervical fascia, 177 22 be- Cervical muscles, prevertebral, 176 ribs, 35 vertebre, cervical. Cervicalis ascendens muscle, 149 Chassaignac’s tubercle, 26 Check ligaments, 108 Chiasma of tendons, 207 Choane, 39 76 Chopart’s joint, 138 Chorda dorsalis, 110, 115 tympani, 57 Clavicle, 83, 85 body of, 85 development, 85 extremities of, 85 Clavicular notches, 34 portion of pectoralis major muscle, 167 Clinoid process, anterior, 41, 49 middle, 48 posterior, 48 Clivus, 43, 45, 48 Coccygeal cornua, 30 Coccyx, 30 development of, 31 joints of, 113 movements of, 113 Cochlear joint, to9 Collar bone, 85. See also Clavicle. Colles’ ligament, 159 Common carpometacarpal joint, 124, 125 meatus of nose, 77 Communicating synovial burs, 108 Complexus minor muscle, 151 muscle, 152 Compound joints, 109 Compressor narium, 182 Concha nasalis inferior, 64, 67, 77 Conche nasales, 77 media, 63 superior, 63 sphenoidales, 48 Conchal crest, 67, 69 Conduction ligaments, 108 Condyles, 20 femoral, 98, 133 of occipital bone, 45 of tibia, external, 99 internal, 99 Condyloid canal, 40, 45 anterior, 40, 45 posterior, 40 fossa, 45 joint, T10 portions of occipital bone, 45 processes, 200 of mandible, 71, 73 posterior, 72 of skull, 38 Conoid ligament, 120 Coracoacromial ligament, 120 Coracobrachial bursa, 208 Coracobrachialis muscle, 185, 189 _ function of, 189 nerve supply of, 189 Coracoclavicular fascia, 170 23. See also Vertebre, “oracoclavicular ligament, 120 -Coracohumeral ligament, 121 _ Coracoid process of scapula, 84 tuberosity, 85 Cornua of fascia lata, 232 of hyoid bone, greater, 73 : lesser, 73 Coronal suture, 36, 37, 79 ‘Coronoid fossa, 86 process of cranium, 38, 72 of a 71, 73 of ulna, 8 Corrugator eect muscle, 179 Costa, 32. See also Ribs. Costal arch, 33 cartilages, 33 articulations of, 117 ve, 32 sina of diaphragm, 164 process, 24 surface of scapula, 83 tubercle, ligament of, 116 tuberosity of clavicle, 85 Costoclavicular ligament, 119 ‘Costocoracoid membrane, 170 -Costotransverse articulations, 116 foramen, 117 ligament, anterior, 116 middle, 116 posterior, 116 superior, 116 Cotyloid ligament, 131 notch, 9 Coxal bone, 93 development, 96 joint, 131 Cranial bones, 44, 45 fosswe, 41-43 anterior, 41 middle, 41 erior, 41, 43 yh aspect of, 44 { um, 36. See also Shut, ~ cerebrale, 44) 45 mexwe ou ply of, 162 tag Sia » 163 “eg 47 ntal, 41, infratemporal, 39, 50 lachrymal ny, anterior, 67 rectus capitis posticus major INDEX. Crest of sacrum, 29 of tibia, 100 orbital, of sphenoidal bone, 50 eo 48 Cribriform fossa, 232 plate of ethmoid bone, 41, 61, 62 Crista galli, 41, 62 Crucial eminence, 43, 46 ligament, 134 anterior, 134 of palm, 205 terior, 134 Cruciate ligament, 115, 229 Crural ligament, transverse, 233 Crus, inner, of diaphragm, 165 intermedium of diaphragm, 165 laterale of diaphragm, 165 mediale of diaphragm, 165 of subcutaneous inguinal ring, an- terior, 159 inferior, 158 posterior, 159 superior, 158 Cubital interosscous bursa, 208 Cuboid bone of foot, 102, 104 development, 106 Cuboideonavicular ligament, dorsal, Iq! plantar, 141 Cucullaris muscle, 145 functions of, 146 nerve supply of, 146 Cuneiform bones, external, 104 first, 104 internal, 104 middle, 104 of foot, 102, 104 development, 106 of hand, 89, 90, 91 second, 104 third, 104 ligaments, navicular dorsal, 141 Cuncocuboid ligament, dorsal, 141 interassecous, 141 plantar, 141 Cuneometatarsal osseous, I41 Cuneonavicular articulation, 137, 138 ligaments, _ inter- Deep head of flexor pollicis brevis muscle, 199 infrapatellar bursa, 135 layer of calf muscles, 221 of cervical fascia, 177 of extensors of forearm, oblique, 107 straight, 197 of flexor muscles of forearm, 192 muscles of neck, 175 posterior sacrococcygeal ligament, 113 temporal fascia, 184 Deltoid ligament, 139 tuberosity, 86 Deltoideopectoral triangle, 167 Deltoideus muscle, 185, 186 241 Deltoideus muscle, function of, 186 nerve supply of, 186 Dens epistrophei, 25, 26, 114 of axis, 25 Dental canal, inferior, 72 foramen, inferior, 72 Depressor anguli oris muscle, 181 labii inferioris muscle, 181 septi nasi muscle, 181 Descriptive anatomy, definition, 117 Designations of positions, 17, 18 Diameters of pelvis, 131 Diaphragm, 164 crura of, 165 development, 166 foramina of, 166 functions of, 166 nerve supply of, 166 Diaphysial center of ossification, 21 Diaphysis, 19 Diarthroses, 107, 108. See also Artic- ulations. Digastric fossa, 40, 72 muscle, 142, 174 functions of, 174 nerve supply of, 174 Digital articulations, 128, 137, 139 burs, dorsal subcutaneous, 208 fossa, 97 Digitate impressions, 41 of sphenoid bone, so Diploé, 19 Disarticulated skull, 36 Discs, articular, 108, 118 of elbow, 123 Distal radioulnar articulation, 123 Dorsal arch of vertebra, 22 basal ligaments, 127, 141 border of metacarpal bones, gr of radius, SS of ulna, 87 calcanconavicular ligament, 140 carpal ligaments, 203, 208 extensor tendon sheaths be- neath, 203 carpometacarpal ligament, 127 cuboideonavicular ligament, 141 cuncocuboid ligament, 141 fascia of hand, 207, 208 intercarpal ligament, 127 intercunciform ligament, 141 interassei muscles, 227 ligaments of foot, 140 naviculari-cunciform ligaments, 141 radiocarpal ligament, 126 subcutaneous digital bursx, 208 metacarpophalangeal bursx, 208 surface of radius, 88 of scapula, 83 of ulna, 87 talonavicular ligament, 140 tarsal ligaments, 140 tarsomietatarsal ligaments, 141 Dorsum, muscles of, 224 sell, 41,48 $6 Douglas’ line, 161 Ductus endolymphaticus, 55 242 ELzow, articular disc of, 123 articulations of, 122 Elbow-joint, 122 movements of, 123 Ellipsoidal joint, 110 Embryology, definition, 17 Eminence, arcuate, 54 articular, of temporal bone, 40, 53 carpal, radial, go ulnar, 90 crucial, 43, 46 frontal, 60 hypothenar, 198 muscles of, 200 iliopectineal, 95 intercondyloid, of tibia, 99 olivary, 41, 48 parietal, 59 plantar, external, 33 internal, 233 middle, 225, 233 pyramidal, 57 thenar, 198 muscles of, 199 Enarthrosis, 110, 131 Epicondyles, 20 of femur, external, 98 internal, 98 of humerus, 86 Epicranius muscle, 178 Epiphyses, 19 Epiphysial centers of ossification, 21 line, 21 Episternal bones, 36 Epistropheus, 23, 25 Epitrochleoanconeus muscle, tg0 Erector spine muscle, 149 Esophageal opening of diaphragm, 165, 166 Ethmoid bone, 62 ale of, 63 cribriform plate of, 41, 61, 62 development of, 64 in newborn, 64, 81 lateral masses. of, 62, 63 perpendicular plate of, 62, 63 Ethmoidal bulla, 64 cells, 63, 64 crest, 67, 69 depressions, 61 foramen, 63 anterior, 61, 75 posterior, 61, 75 groove, 65 labyrinths, 62, 63 notch, 61 process of inferior turbinated bone, 64 spine, 41, 48 surface of lachrymal bone, 65 Ethmoideomaxillary suture, 80 Eustachian tube, cartilaginous portion of, 51 semicanal for, 58 Extensor carpi radialis brevis muscle, 185, 195 longus muscle, 185, 195 ulnaris muscle, 185, 197 INDEX. Extensor carpi ulnaris muscle, function of, 197 nerve supply of, 197 digiti V proprius muscle, 185, 196 function of, 197 nerve supply of, 197 digitorum brevis muscle, 210, 224 communis muscle, 185, 196 function of, 197 nerve supply of, 197 longus muscle, 210, 223 function of, 224 nerve supply of, 224 hallucis brevis muscle, 210, 224 function of, 224 nerve supply of, 224 longus muscle, 210, 223 function of, 223 nerve supply of, 223 indicis proprius muscle, 185, 198 function of, 198 nerve supply of, 198 of leg, 223 ossis metacarpi pollicis muscle, 197 pollicis brevis muscle, 185, 197 function of, 197 nerve supply of, 197 longus muscle, 185, 197 function of, 198 nerve supply of, 198 surface of forearm, muscles of, 195 of upper arm, muscle of, 189 tendons of fingers, 204 of hand, 203 sheaths of, 203 External abdominal ring, 158 angle of scapula, 83, 84 angular process of frontal bone, 36 aperture of aqueeductus vestibuli, 55 arcuate ligament, 156, 165 auditory meatus, 38, 4o bicipital groove, 188, 207 border of humerus, 86 carotid foramen, 56 condyle of femur, 98 of tibia, 99 crest of fibula, ror cuneiform bones of foot, 102, 104 epicondyles of femur, 98 of humerus, 86 intercondyloid tubercle of tibia, 99 intercostal ligaments, 169 intercostales muscles, 169 intermuscular septa of arm, 207 of thigh, 232 lateral ligament of arm, 122 of head, 118 of knee, 135 lumbocostal arch, 165 malleolar bursa, subcutaneous, 234 surface of talus, 102 malleolus, 1or ligaments of, anterior, 137 posterior, 137 margin of scapula, 83 meniscus of knee-joint, 133 occipital crest, 46 protuberance, 4r, 46 External palpebral raphe, 179 patellar retinaculum, 135 plantar eminence, 233 process or calcaneus, 103 of talus, 102 pterygoid plate, 40, 50 rectus muscle, spine for, 76 - semilunar cartilage, 133 subcutaneous epicondylar bursa, 208 superior articular surface of tibia, 99 surface of shaft of tibia, 100 talocalcaneal ligament, 140 tubercle of talus, 102 Extremities, lower, burs of, 233 fascize of, 231 free, skeleton of, 97 muscles of, 209 classification, 235 skeleton of, 82, 93 of long bones, 19 skeleton of, 22, 82, 83 upper, articulations of, 119 burs of, 208 fascie of, 207 free, skeleton of, 85 ligaments of, 119 muscles of, 185 development, 209 skeleton of, 82, 83 thoracic muscles of, 166 Face, bones of, 44 muscles of, 178 functions of, 182 nerve supply of, 182 proper, 179 Facial canal, 56, 57 geniculum of, 57 surface of malar bone, 71 Falciform margin of fascia lata, 232: process, 129 False pelvis, 130 ribs, 33 vertebrae, 22, 28 Fascie, 143 abdominal, 163 antibrachial, 207 axillary, 207 brachial, 207 buccopharyngeal, 184 cervical, 177 coracoclavicular, 170 cremasteric, 163 cruris, 233 gluteal, 232 iliac, 231, 232 iliopectineal, 231, 232 infraspinatus, 207 lata, 231 lumbodorsal, 146, 156 nuchal, 156 of back, 156 of foot, 233 of hand, dorsal, 207, 208 of head, 184 of leg, 233 Fascia of lower extremity, 231 of neck, 177 of thigh, 231 of Mpper extremity, 207 pare deomasseteric, 184 ; necti neal, 232 pectoral, 170 pi ertebral, 177 Searpa’s, 163 subscapular, 207 perficial, general, 163 ? praspinatus, 207 tran sversalis, 163 asciculi, transverse, 233 Fat mass, Bichat’s, 182, 183 buccal, 182, 183 Female pelvis, 131 Femoral condyles, 133 _ triangle, 216 Femur, 82, 97 condyles of, 98 d pment, 98 epicondyles of, 98 extremities of, 97, 98 head of, 97 neck of, 97 (one of, 97, 98 surfaces of, 97, 98 surfaces of, 97 tro hanters of, 97 } apts — 159 Fibroce aoe to interpubic, 108, 128 ntervertebral, , 110 of subcutaneous inguinal ring, vicular, 141 s layer of articular capsule, 108 ring of tervertebral fibrocartilage, ec) ibu 82, 101 d tibia, relations, 101 ent, 101 extremities of, 101 head of, 101 ‘ of, 101 surfaces of, ror yu lateral ligament, 134, 135 HO ich. 100 s membrane of, #36, 137 ir \eiform bone of foot, 104 mpanica, 4°, 53, 57 » 49, 53, 57 obi 3 39, 66, 71, 74,75 tall, 49, 43) 54) Sr » 53, 54 INDEX. Fissure, petrotympanic, 40, 53, 57 sphenoidal, 37, 42, 49, 74, 75 sphenomaxillary, 37, 39, 71, 74) 75 sphenooccipital, 45 sphenopetrosal, 39, 40, 42, 54, 55) | 81 superior orbital, 37, 42, 49, 74) 75 tympanomastoid, 53, §7 tympanosquamosal, 57 Fixation ligaments, 108 Flat abdominal muscles, 157 development, 164 bones, 19 muscles of back, 145 development, 156 Flexion vertebra, 23 Flexor accessorius muscle, 225 brevis digiti V muscle, 210 carpi radialis muscle, 185, 191 function of, 191 nerve supply of, rox ulnaris muscle, 185, 192 function of, 192 nerve supply of, 192 digiti quinti brevis muscle, 186, 200, 227 function of, 200, 227 nerve supply, 200, 227 digitorum brevis muscle, 210, 225 nerve supply of, 22 longus muscle, 210, 219, 221 function of, 222 nerve supply of, 222 profundus muscle, 185, 192 function of, 194 nerve supply of, 194 sublimis muscle, 185, 192 function of, 192 nerve supply of, 192 hallucis brevis muscle, 210, 226 function of, 226 nerve supply of, 226 longus muscle, 210, 219, 222 function of, 222 groove for, 103 nerve supply of, 222 of thigh, 218 pollias brevis muscle, 186, 199 function of, 190 nerve supply of, 190 longus muscle, 185, 194 function of, 194 nerve supply of, 104 surface of forearia, muscles of, 191 | of upper arm, muscles of, 188 tendons of palm, 205 ~ Floating ribs, 33 Fontanelles, 81 anterior, 81 frontal, 81 mastoid, 82 occipital, 81 posterior, 81 sphenoidal, 82 Fonticuli, 81 Foot, articulations of, 137 bones of, 101 calcaneus of, 102, 103 a 243 Foot, cuboid bone of, 102, 104 cuneiform bones of, 102, 104 fascix of, 233 ligaments of, 137 accessory, 139 interosseous, 141 lumbricales muscles of, 228 metatarsal bones of, 105 muscles of, 224 classification, 235 navicular bone of, 102, 03 phalanges of, 82, 105 sesamoid bones of, $2, 106 skeleton of, 101, 106 sole of, muscles of, 225 synovial sheaths of, 229 talus of, 102 tarsal bones of, 102 vaginal ligaments of, 231 Foramina, 20 alveolar, 67 anterior sacral, 28 auditory, internal, 55 cx#cum, 41, 61, So carotid, external, 56 internal, 55 costotransverse, 117 dental, inferior, 72 ethmoidal, 63 anterior, 61, 75 posterior, 61, 75 frontal, 60, 75, 76 incisive, -39, 68 infraorbital, 37, 66, 67 intervertebral, 23, 31 jugular, 40, 43, 46 lacerum, 39, 40, 42, 43, 5§ magnum, 40, 44, 45 mandibular, 72 mastoid, 40, 43, 53, 54 mental, 37, 72 nasal, 65 nutrient, 20 of bone, 20 of tibia, 100 of ulna, 87 obturator, 93, 96 of diaphragm, 166 of nasal cavity, 77 of sacrum, intervertebral, 29 of sternum, 36 of xiphoid process, 36 optic, 41, 48, 75 ovale, 39, 42, 49, 50 palatine, greater, 40, 69 lesser, 40, 7° parietal, 44, 59 quadniateral, 166 rotundum, 42, 49, 50, 78 sacral, 28, 29 intervertebral, 29 sacrosciatic, 130 sciatic, great, 130 lesser, 130 sphenopalatine, 70, 78 spinal, 23 spinosum, 39, 42, 49, 50 stylomastoid, 40, 56 : . ee ——_r- Uc C YC Krt—~—“—™ —- 244 Foramina, supraorbital, 60, 75, 76 transversarium, 24 vertebrale, 23 zygomaticofacial, 71 zygomaticoorbital, 71, 75 zygomaticotemporal, 71 Forearm, extensor surface of, muscles of, 195 flexor surface of, muscles of, 1gt muscles of, 185, 191 classification, 209 radial muscles of, 194 Forehead, bony, 36 Foss, 20 acetabular, 96 anterior cranial, 41 axillary, 147 canine, 66 carotid, 172, 174 condyloid, 45 coronoid, 86 cranial, 41-43 anterior, 41 middle, 41 posterior, 41, 43 cribriform, 232 digastric, 40, 72 digital, 97 for lachrymal gland, 76 sac, 76 glenoid, 38, 53 hypoglossal, 48 hypophyseal, 41 iliac, 95 iliopectineal, 210 infraspinatous, of scapula, 83 infratemporal, 79 intercondyloid, 98 anterior, 99 posterior, 99 jugular, 40, 46, 56 mandibular, 38, 40, 53, 118 mastoid, 54 middle cranial, 41 occipital, inferior, 44, 46 superior, 46 olecranon, 87 oval, 232 petrosal, 56 posterior cranial, 41, 43 pterygoid, 4o, 51 pterygopalatine, 49, 50, 73 radial, 87 scaphoid, 51 sphenomaxillary, 49, 50, 78 subarcuate, 55 subscapular, 83 supraclavicular, lesser, 171 supraspinatous, of scapula, 83 temporal, 38, 52 trochanteric, 97 zygomatic, 79 Fovea, 20 articularis dentis, 25 Foveole granulares, 44, 60 Free lower extremity, skeleton of, 97 upper extremity, skeleton of, 85 Frons, 36 INDEX..: Frontal angle of parietal bone, 59 bone, 36, 60 borders of, 60 cerebral surfaces of, 41 development of, 62 frontal portion of, 60 in newborn, 62, 81 nasal portion of, 60, 61 orbital plates of, 61 surfaces of, 61 sulci arteriosi of, 61 surfaces of, 60 zygomatic process of, 60 border of parietal bone, 59 of sphenoid bone, 49 cells, 63 crest, 41, 61 eminences, 60 fontanelle, 81 foramen, 60, 75, 76 notch, 60, 75 plane, 17 portion of frontal bone, 60 process of maxilla, 37 of superior maxillary, 66, 67 sinus, 61 development, 62 spine, 61 surface of frontal bone, 60 suture, 60, 81 Frontalis muscle, 178 functions of, 17 nerve supply of, 178 Frontoethmoidal suture, 41, 61, 80 Frontolachrymal suture, 37, 80 Frontomaxillary suture, 37, 80 Frontosphenoidal process, 37, 71 Fusiform muscle, 142 GALEA aponeurotica, 178 Gastrocnemial bursa, inner, 220 internal, 136, 220, 234 Gastrocnemius lateralis muscle, 220 medialis muscle, 220 muscle, 219 Gemelli muscles, 209, 213 Gemellus inferior muscle, 213 superior muscle, 213 General anatomy, definition, 17 superficial fascia, 163 Geniculum of facial canal, 57 Geniohyoideus muscle, 174, 175 functions of, 175 nerve supply of, 175 Gimbernat’s ligament, 131, 163, 164, 231 Ginglymoarthrodia, 127, 139 Ginglymus, 109 lateral, ro9 Girdle, pelvic, 93 articulations of, 128 ligaments of, 128 shoulder, 83 Glabella, 60 Gladiolus of sternum, 34 Gland, lachrymal, fossa for, 76 Glaserian fissure, 40, 53, 57 Glenoid cavity, 84, 121 fossa, 38, 53 ligament, 121 Glenoidal lip, 108, 109, 121 of hip, 131 Gliding joints, 110 Gluteus maximus muscle, 209, 211 function of, 212 nerve supply of, 212 medius muscle, 209, 212 function of, 212 nerve supply of, 212 minimus muscle, 209, 212 function of, 212 nerve supply of, 212 Gluteal fascia, 232 line, anterior, 94 inferior, 94 middle, 94 posterior, 94 superior, 94 muscles, 211 sulcus, 232 tuberosity, 98 Gluteofemoral burse, 212, 233 Gomphosis, 107 Gracilis muscle, 209, 216 function of, 217 nerve supply of, 217 Great sacrosciatic ligament, 129 saphenous vein, 232 sciatic foramen, 130 notch, 94, 96 toe, ball of, muscles of, 226 Greater cornua of hyoid bone, 73 multangular bone, 89, go palatine foramen, 40, 69 pelvis, 130 sigmoid notch of ulna, 87 trochanter, 97 tubercle of humerus, 85 tubercular ridge, 86 wings of sphenoid bone, 47, 49 Groove, bicipital, external, 188, 207 internal, 188, 207 of humerus, 85 carotid, 41, 48 carpal, go costal, 32 ethmoidal, 65 for flexor hallucis longus, 103 for musculospiral nerve, 86 for radial nerve, 86 hamular, 51 infraorbital, 66, 76 intertubercular, of humerus, 85 lachrymal, 67 musculospiral, 86 mylohyoid, 72 obturator, 95 of calcaneus, 103 of promontory, 58 of talus, 102 optic, 41, 48 palatine, 68 paraglenoidal, 95 peroneal, 103, 104 petrosal, inferior, 43, 45, 55 2 Bee palatine, SI, on 69 pulmonary, 35 ‘Sagittal, 44, 46, 60, 61 Semacid, 43) 40, 53, 60 su vian, 33 transverse, 43, 46 tympanic, 57 H R’s arches, 165 Hamate bone, 89, 90 H iecstacarpal i ligament, 127 mular ae 51 ces 40, 5 Hamulus serinalis, 65 beens cus, 40, 51 Hand, articulations of, 124 bones of, 89 carpal bones of, 89 extensor tendons of, 203 . sheaths of, 203 ligaments of, 124 ‘metacarpal bones of, gt movements of, 126 muscles of, 185, 198 classification, 209 palm of, Caren of, 205 of, 82, 92. Re iaares of hand. ” sesamoid bones of, 82, 92. Sesamoid bones ‘of hand. “nape of, Be es: ‘ te, 39, 7 in newborn, tuberosity of, 40 armonic suture, 107 d, articulations of, 117 ependent, 118 mmm of, 177 See also Pha- See also ee) re INDEX. Horizontal plates of palate bone, 69 portion of hard palate, 39 of squamous portion of temporal bone, 52 | Horner’s muscle, 179 Humeral head of flexor carpi ulnaris muscle, 192 digitorum sublimis muscle, 192 pollicis longus muscle, 194 of pronator teres muscle, 191 Humeroradial articulations, 122 Humeroulnar articulation, 122 Humerus, 82, 85 anatomical neck of, 85 borders of, 86 development, 87 extremities of, 85 head of, 85 neck of, anatomical, 85 surgical, 86 shaft of, 85 surfaces of, 86 surgical neck of, 86 tubercles of, 85 Hunter’s canal, 217 Hyoid bone, 73 body of, 73 development, 73 ligaments of, 119 muscles, 172 Hypoglossal canal, 40, 45 fossa, 48 Hypophyseal fossa, 41 Hypophysis, 48 Hyposkeletal muscles, 164 Hypothenar eminence, 198 muscles of, 200 Intac bursa, subtendinous, 234 fascia, 231, 232 fossa, 95 Tliacus muscle, 210 lliocostalis cervicis muscle, 149 dorsi muscle, 149 lumborum muscle, 149 muscle, 149 functions of, 54 nerve supply of, 154 Iliofemoral ligament, 132 Iliolumbar ligament, 129 Iliopectineal bursa, 133, 211, 234 eminence, 95 fascia, 231, 232 fossa, 210 ligament, 231 line, 95 Iliopsoas muscle, 209, 210 function of, 211 nerve supply of, 211 lliotibial band, 232 Ilium, 93, 94 ala be 93, os Surfaces of, 94, 95 body of, 95 crest of, 94 lips of, o4 development, 96 | Ilium, spines of, 94 tuberosity of, 95 Incisive foramen, 39, 68 muscles, 181 notch, 68 suture, 69, 81 Incisor teeth in fetus, 69 Incisura, 20 mastoidea, 40 Independent ligaments of head, 118 Indicator cate 198 Inferior angle of scapula, 83, 84 aperture of pelvis, 131 articular surfaces of tibia, 100 belly of omohyoideus muscle, 173 bicipital bursa, 234 cornu of fascia lata, 232 crus of subcutaneous inguinal ring, 158 dental canal, 72 foramen, 72 extremity of femur, 97, 98 surfaces of, 98 of fibula, 101 of humerus, 85 of radius, 89 of tibia, 99 of ulna, 87, 88 gluteal line, 94 intervertebral notch, 23 maxillary, 71. See also Mandible. meatus of nose, 77 nuchal line, 41, 46 occipital fossa, 44, 46 orbital fissure, 37, 30, 66, 71, 74, 75 peroneal retinaculum, 230 petrosal groove, 43, 45, 55 pillar of subcutancous inguinal ring, 158 process of temporal bone, 57 — ligament, 128 tp, pene nl 904 “a rouble: 93, 96 temporal line, 59 thoracic aperture, 35 transverse ligament, 121 turbinated bone, 64, 67, 77 development, 64 vertebral notches, 23 Infraglenoidal margin of tibia, roo tuberosity, 84 Infrahyoid muscles, 172 functions of, 174 nerve supply of, 173 Infraorbital canal, 67 entrance of, 75 foramen, 37, 66, 67 groove, 66, 76 margin, 75 suture, 68, 81 Infrapatellar bursa, deep, 135 subcutaneous, 136, 234 Infraspinatus bursa, fascia, 207 . fossa of scapula, 83 muscle, 185, 186 function of, 187 nerve supply of, 187 246 Infrasternal angle, 35 Infratemporal crest, 39, 50 fossa, 79 surface of sphenoid bone, 50 of superior maxillary, 66 Infundibular fissure, 64 Inguinal canal, 159 ligament, 131, 163 reflected, 159, 164 ring, subcutaneous, 158 Inner crura of diaphragm, 165 gastrocnemial bursa, 220 head of gastrocnemius muscle, 220 of triceps muscle, 190 lip of linea aspera, 97 portion of longus colli muscle, 176 vitreous table of flat bones, 19 Innominate bone, 93 development, 96 Inscriptions, tendinous, 143 ° of rectus abdominis, 161 Insertion of muscle, 142 Interalveolar septa, 68 Interarticular cartilages, 108 ligament, 116, 117 Intercarpal articulations, 124 ligament, dorsal, 127 volar, 127 Intercartilaginei ligaments, 169 Interchondral joints, 117 Interclavicular ligament, 119 notch of manubrium, 34 Intercolumnar fibers of subcutaneous inguinal ring, 159 Intercondyloid eminence of tibia, 99 fossa, 98 anterior, 99 posterior, 99 line, 98 tubercle, external, 99 internal, 99 Intercostal ligaments, 117 external, 169 internal, 169 spaces, 35 Intercostales externi muscles, 169 interni muscles, 169 muscles, 166, 169 functions of, 170 nerve supply of, 170 Intercrural fibers of subcutaneous in- guinal ring, 159 Intercuneiform ligament, dorsal, 141 interosseous, 141 plantar, r41 Intermaxillary bone, 69 suture, 37, 80 Intermedial crus of diaphragm, 165 Intermetacarpophalangeal bursz, 209 Intermetatarsal articulations, 137, 139 Intermetatarsophalangeal bursa, 235 Intermuscular septa, 143 anterior, of leg, 233 external, of arm, 207 of thigh, 232 interna], of arm, 188, 207 of thigh, 232 of arms, 188, 207 INDEX. Intermuscular septa, posterior, of leg, 233 Internal angle of scapula, 83, 84 annular ligament, 231 arcuate ligament, 165 auditory canal, 55 foramen, 55 meatus, 43 bicipital groove, 188, 207 border of humerus, 86 of tibia, 100 carotid foramen, 55 cerebral surface of frontal bone, 60 condyle of femur, 98 of tibia, 99 crest of fibula, ror cuneiform bones of foot, 102, 104 epicondyle of femur, 98 of humerus, 86 gastrocnemial bursa, 136, 220, 234 intercondyloid tubercle of tibia, 99 intercostal ligaments, 169 intercostales muscles, 169 intermuscular septum of arm, 188, 207 of thigh, 232 lateral ligament of knee, 134 of radius, 122 lumbocostal arch, 165 malleolar bursa, subcutaneous, 234 surface of talus, 102 malleolus, roo margin of scapula, 83 meniscus of knee-joint, 133 muscles of hip, 210 of thigh, 216 occipital crest, 44, 46 protuberance, 43, 46 palpebral ligament, 179 patellar retinaculum, 135 plantar eminence, 233 process of calcaneus, 103 pterygoid plate, 4o, 50 semilunar cartilage, 133 subcutaneous epicondylar 208 superior articular surface of tibia, bursa, 99 surface of shaft of tibia, too of talus, 102 of ulna, 87 talocalcaneal ligament, 140 tubercle of talus, 102 Internasal suture, 37, 65, 80 Interoccipital synchondroses, 47 Interossei dorsales muscles, 186, 200 functions of, 203 nerve supply of, 203 muscles of foot, 210, 227 of hand, 186, 200 pedis muscles, 227 dorsal, 227 functions of, 228 nerve supply of, 228 plantar, 227, 228 volares muscles, 186, 200, 201 function of, 203 nerve supply of, 203 Interosseous basal ligaments, 127 metatarsal ligaments, 141 bursa, cubital, 208 cuneocuboid ligament, 141 cuneometatarsal ligaments, 141 intercuneiform ligament, 141 ligaments of foot, 141 of neck, 116 membrane of radius and ulna, 123 of tibia and fibula, 136, 137 ridges of fibula, ror of radius, 88 of tibia, 100 of ulna, 87 sacroiliac ligament, 129 spaces of metacarpal bones, 92 talocalcaneal ligament, 140 Interphalangeal articulations of foot, 137, 139 of hand, 128 Interpubic fibrocartilage, 108, 128 Intersphenoidal synchondrosis, 51, 81 Interspinales muscles, 154 functions of, 155 nerve supply of, 155 Interspinous ligaments, 112 Intertarsal articulations, 137 Intertransversarii anterior muscles, 155 laterales muscles, 155 mediales muscles, 155 = muscles, 154, 155 functions of, 155 nerve supply of, 155 posteriores muscles, 155 Intertransverse ligaments of vertebral column, 112 Intertrochanteric line, 97 ridge, 97 ; Intertubercular groove of humerus, 85 mucous sheath of biceps, 121, 188 Intervertebral discs, 30 fibrocartilages, 108, 110 foramen, 23, 31 of sacrum, 29 joints, III Intrajugular process, 46, 55 Intraoccipital synchondrosis, anterior, 81 posterior, 81 Intratendinous olecranal bursa, 208 Irregular bones, 20 Ischiocapsular ligament, 132 Ischium, 93, 96 development, 96 Jaws. See Mandible and Mawxille. Joint. See Articulations. cushions, 108, 109 Juga alveolaria, 68 Jugular foramen, 40, 41, 43 fossa, 40, 46, 56 ; notch of manubrium, 34 of temporal bone, 55 process, 43, 46 tubercles, 43, 46 Jugum sphenoidale, 41, 48 Juncture tendinum, 196 -KNEE-CAP, 99. See also Patella. Knee-joint, 133 — menisci of, 133 functions of, 136 movements, 136 _ semilunar cartilages of, 133, 136 transverse ligament of, 134 ‘Lacertvus fibrosus, 188, Lachrymal bone, 37, 64 4 development, 65 surfaces of, 65 cells, 63, 65 crest, anterior, 67 terior, 65 Rand, fossa for, 76 groove, 67 notch, 67 portion of orbicularis oculi muscle, 179 process of inferior turbinated, 64 sac, fossa for, 76 Lachrymoconchal suture, 80 -Lachrymoethmoidal suture, 80 Lachrymomaxillary suture, 80 Laciniate ligament, 221, 231 Lacuna musculorum, 231 vasorum, 231 nar ligament, 131, 163, 164, 231 ambdoid border of occipital bone, 46 _ suture, 38, 79 Lamina papyracea, 63 anger’s muscle, 167 zateral crest of sacrum, 29 crus of diaphragm, 165 ginglymus, 109 intertransversarius muscle, 155 ligament, external, of arm, 12 of head, 118 of knee, 135 fibular, 134, 135 internal, of arm, 122 of knee, 134 of fingers, 127 of foot, 139 _ radial, 126 tibial, 134 ulnar, 126 es of atlas, 25 of ethmoid, 62, 63 of sacrum, 29 pe ortions of occipital bone, 40, 45 sacrococcygeal oe 113 ace of radius, 88 ssimus bursa, 146. rsi muscle, 146 functions of, 147 "nerve supply of, 147 anterior muscles of, 223 207 i ay a J pecs of, 222 INDEX. Lesser palatine foramen, 40, 70 pelvis, 130 sacrosciatic ligament, 129, 130 sciatic foramen, 130 notch, g6 sigmoid notch of ulna, 87 supraclavicular fossa, 171 trochanter, 97 tubercle of humerus, 85 tubercular ridge, 86 wings of sphenoid bone, 47, 49 Levator al# nasi muscle, 180 anguli oris muscle, 181 glandule thyreoidea muscle, 173 labii inferioris muscle, 181 superioris alaque nasi muscle, 180 muscle, 180 menti muscle, 181 scapul# muscle, 147 functions of, 147 nerve supply of, 147 Levatores costarum breves muscles, 170 longi muscles, 170 muscles, 169 Ligamenta coruscantia, 169 flava, 112 Ligaments, 108 accessory, 108 acromioclavicular, 120 alar, 115 annular, 122 anterior, 127, 229 internal, 2 of palm, 205 posterior, 203, 208 apical odontoid, 115 arcuate, 128 external, 156, 165 internal, 165 popliteal, 135 basal dorsal, 127, 141 interosseous, 127 metatarsal, interosseous, 141 piantar, 141 volar, 127 bifurcate, 140 calcaneocuboid, 141 plantar, 141 calcaneofibular, 140 calcaneonavicular, 141 dorsal, 140 plantar, 141 calcaneotibial, 139 capitular, anterior, 136 posterior, 136 transverse, of foot, 139 carpal, 126 dorsal, 203, 208 extensor tendon sheaths be- neath, 203 radiate, 127 transverse, 127, 205 volar, 208 carpometacarpal, dorsal, 127 volar, 127 check, 108 Colles’, 159 247 Ligaments, conoid, 120 coracoacromial, 120 coracoclavicular, 120 coracohumeral, 121 costoclavicular, 119 costotransverse, anterior, 116 middle, 1160 posterior, 116 superior, 116 cotyloid, 131 crucial, 134 anterior, 134 of palm, 205 posterior, 134 cruciate, 115, 22 crural, transverse, 232 cuboideonavicular, dorsal, 141 plantar, 14! cuneocuboid, dorsal, 141 interoasscous, 141 plantar, 141 cuneometatarsal, interosseous, 141 deltoid, 139 dorsal, of foot, 140 Gimbernat’s, 131, 163, 164, 231 glenoid, 121 hamatometacarpal, 127 iliofemoral, 132 iliolumbar, 129 iliopectineal, 231 inguinal, 131, 163 reflected, 159, 164 interarticular, 116, 117 intercarpal dorsal, 127 volar, 127 intercartilaginei, 169 interclavicular, 119 intercostal, 117 external, 169 internal, 169 intercunciform, dorsal, 141 interosscous, 141 plantar, 141 interosscous, 116 basal, 127 metatarsal, 141 cuneocuboid, 141 cuneometatarsal, 141 intercuneiform, 141 of foot, 141 sacroiliac, 129 talocalcancal, 140 interspinous, 112 intertransversc, of vertebral column, 112 ischiocapsular, 132 laciniate, 221, 231 lacunar, 131, 163, 164, 231 lateral, external, of arm, 122 of head, 122 of knee, 135 short, 135 fibular, 134, 135 internal, of head, 122 of knee, 134 of fingers, 127 of foot, 139 radial, 122, 126 248 Ligaments, lateral, tibial, 134 ulnar, 122, 126 lumbocostal, 156 navicular cuneiform, dorsal, 141 plantar, 141 oblique, 123 popliteal, 135 odontoid apical, 115 of ankle-joint, 139 of conduction, 108 of costal tubercle, 116 of external malleolus, anterior, 137 posterior, 137 of fixation, 108 of foot, 137 accessory, 139 of hand, 124 of head, 117 independent, 118 of hyoid bone, 119 of lower extremities, 128 of neck, 116 of pelvic girdle, 128 of scapula, 120 of upper extremities, 119 of vertebral column, 11r orbicular, 132 palpebral, internal, 179 patellar, 135 pelvic, 128 independent, 129 pisohamate, 125 pisometacarpal, 125 plantar accessory, 139 long, 141 of foot, 140 tarsal, 141 popliteal, arcuate, 135 oblique, 135 Poupart’s, 131, 163 pterygomaxillary, 184 pterygospinous, 119 pubic, inferior, 128 superior, 128 pubocapsular, 132 radial lateral, 122, 126 radiate, 116, 117 radiocarpal, dorsal, 126 volar, 126 reinforcing, 108 rhomboid, 119 round, 132, 133 sacrococcygeal, anterior, 113 lateral, 113 posterior, 113 sacroiliac, anterior, 129 interosseous, 129 posterior, 129 sacrosciatic, great, 129 lesser, 129, 130 sacrospinous, 129, 130 sacrotuberous, 129 sphenomandibular, 118 stellate, 116, 117 sternoclavicular, 119 stylohyoid, 119 stylomandibular, 118, 184 stylomaxillary, 184 INDEX. Ligaments, supraspinous, 112 talocalcaneal, anterior, 140 external, 140 internal, 140 interosseous, I40 posterior, 140 talofibular, anterior, 140 posterior, 140 talotibial, anterior, 139 posterior, 139 tarsal, 139 dorsal, 140 tarsometatarsal, dorsal, 141 plantar, 141 temporomandibular, 118 tibionavicular, 139, 140 transverse, capitular, 127 inferior, 121 of atlas, 114 of hip, 131 of knee, 134 superior, 120 trapezoid, 120 triangular, 159, 164 ulnar, lateral, 122, 126 vaginal, 143 of foot, 231 volar, accessory, 127 Ligamentum nuche, 113 teres, 132 Limbus alveolaris, 68 Linea alba, 161, 163 aspera, 97, 98 muscularis, 83 suprema, 46 terminalis, 29 Lingula, 48, 73 Lips, glenoidal, 108, 109, 121 of hip, 131 of crest of ilium, 94 Lisfranc’s joint, 139 tubercle, 32 Little toe, ball of, muscles of, 227 Locking mechanisms, bony, 108, 109 Long bones, 19 diaphyses of, 19 epiphyses of, 19 extremities of, 19 neck of, 20 shaft of, 19 head of triceps muscle, 189 muscles of back, 149 development, 156 plantar ligament, 141 posterior sacroiliac ligament, 129 Longissimus capitis muscle, 150, 152 cervicis muscle, 150, 151 dorsi muscle, 149, 150 muscle, 149, I50 functions of, 154 nerve supply of, 154 Longitudinal ligaments of vertebral column, III Longus atlantis muscle, 176 capitis muscle, 176 functions of, 176 nerve supply of, 176 colli muscle, 176 Longus colli muscle, functions of, 176 nerve supply of, 176 Louis’ angle, 34 Lower extremity, burs of, 233 fascize of, 231 free, skeleton of, 97 muscles of, 209 classification, 235 skeleton of, 82, 93 jaw, 37. See also Mandible. portion of longus colli muscle, 176 Lumbar portion of diaphragm, 164, 165 ribs, 28, 35 triangle, 147 vertebra, 27 Lumbocostal arch, external, 165 internal, 165 ligament, 156 Lumbodorsal fascia, 146, 156 Lumbosacral vertebra, 30, 36 Lumbricales burse, 228 muscles of foot, 210, 228 of hand, 200, 203 functions of, 203 nerve supply of, 203 Lunate bone, 89, 90 MAIssIAT’s band, 232 Malar bone, 36, 70. matic bone. portion of orbicularis oculi muscle, See also Zygo- 79 surface of malar bone, 71 Male pelvis, 131 Malleolar bursa, subcutaneous exter= nal, 234 internal, 234 surfaces of talus, 102 Malleolus, external, ror ligaments of, anterior, 137 posterior, 137 internal, 100 Mammillary process, 28 Mandible, 37, 71 body of, 71 borders of, 71 development, 73 in new-born, 73, 81 notch of, 71 processes of, 71 ramus of, 37, 71, 72 Mandibular canal, 72 foramen, 72 fossa, 38, 40, 53, 118 Manubrium of sternum, 34 Marrow, bone, 21 Masseter muscle, 182 functions of, 183 nerve supply of, 183 Masseteric tuberosity, 72 Mastoid angle, 43, 59 border of occipital bone, 46 canaliculus, 56, 58 cells, 53 fontanelles, 82 Mastoid foramen, 40, 43, 53, 54 fossa, 54 notch, 53, 54 53 process, 38, 40, 53, 54 Maxille, 37, 66 body of, 66 development, 69 frontal processes of, 37 in newborn, 69, 81 nasal processes of, 37 processes of, 37, 66 surfaces of, 66 Maxillary cells, 63, 67 process of inferior turbinated, 64 sinus, 66 orifice of, 67 surface of palate bone, 69 _ Meatus acusticus externus, 38 auditorius externus, 40 nasopharyngeal, 77 of nose, 77 common, 77 inferior, 77 middle, 64, 77 __ superior, 64, 77 Medial crus of diaphragm, 165 intertransversarius muscle, 155 Median palatine suture, 39, 81 plane, 17 Medullary cavity, 19 Membrane, atlantooccipital, 115 posterior, 115 costocoracoid, 170 interosseous, of radius and ulna, 123 of tibia and fibula, 136, 137 obturator, 115, 129 anterior, 115 posterior, 115 sternal, 117 of knee-joint, 133 function of, 136 protuberance, 71 spine, 72 _ tubercle, 72 Mentalis muscle, 181 d bones, 82, gr base of, ot borders of, or _ development, 92 head of, g1, 92 shaft of, or _ surfaces of, or Metacarpophalangeal articulations, 327 of thumb, 127 yursz, dorsal subcutaneous, 208 portion of temporal bone, 38, 40, 52, | | INDEX. Metatarsal bones, shaft of, 105 | ligaments, basal interosseous, 141 Metatarsophalangeal —_ articulations, 137) 139 Metatarsus, 105 Metopic suture, 60, 62, 81 Middle articular facet of calcaneus, | 103 of talus, 102 clinoid processes, 48 | costotransverse ligament, 116 cranial fossa, 41 crura of diaphragm, 163 cuneiform bones of foot, 102, 104 gluteal line, 94 meatus of nose, 64, 77 plantar eminence, 225, 233 turbinated bone, 163 Monarticular muscles, 1.42 Mucous bursa, 143 sheath, intertubercular, 121, 188 Multangular bone, greater, 89, go lesser, 89, go Multifidus cervicis muscle, 152 dorsi muscle, 152 lumborum muscle, 152 muscle, 152 functions of, 154 nerve supply of, 154 Muscles, 142 abdominal, 157 antagonistic, 143 belly of, 142 biarticular, 142 biceps, 142 bipenniform, 142 bipinnate, 142 biventer, 142 cervical, prevertebral, 176 development, 143 digastric, 142 fusiform, 142 gluteal, 211 head of, 142 hyoid, 172 infrahyoid, 172 insertion of, 142 monarticular, 142 nasal, 179, 182 of anterior surface of thigh, 214 of back, 144 flat, 145 long, 149 short, 154 of extensor surface of forearm, 195 of upper arm, 189 of face, 178 of flexor surface of forearm, 191 of upper arm, 188 of foot, 224 of forearm, 185, 191 of hand, 185, 198 of head, 177 of hip, 210 of hypothenar eminence, 200 of leg, 219 of lower extremity, 209 of mastication, 182 Muscles of neck, 171 of scalp, 178 of shoulder, 185, 186 of thenar eminence, 199 of thigh, 214 of thoracic walls, of trunk, 144 of upper arm, 185, 188 extremity, 185 oral, 179, 150 orbicular, 142 origin of, 142 palpebral, 179 penniform, 142 pinnate, 142 prevertebral cervical, 176 quadriceps, 142 short, 142 sphincter, 142 spindle-shaped, 142 suprahyoid, 174 synergistic, 143 thoracic, 166 triceps, 142 typical, 142 Musculospiral groove, 86 nerve, groove for, 86 Musculotubar canal, 55, 58 Mylohyoid groove, 72 line, 72 raphe, 175 Mylohyoideus muscle, 174 functions of, 175 nerve supply of, 175 Myology, 142 definition, 17 general, 142 special, 144 Myomeric muscles, 184, 185 109 NARES, anterior, 66, 76 posterior, 39 Nasal bones, 37, 65 development, 65 in new-born, 65 border of frontal bone, 61 canal, 75 cavity, 76 foramina of, 77 conch, 37 crest, 68, 69 foramina, 65, 77 muscles, 179, 182 notch, 68 portion of frontal bone, 60, 61 process of maxilla, 37, 66, 67 septum, 37, 76, 77 spine, anterior, 37, 68 posterior, 39, 69 surface of palate bone, 69 of superior maxillary, 66, 67 Nasalis muscle, 182 Nasofrontal suture, 37, 65, 80 Nasolachrymal canal, 64, 67, 75 Nasomanillary suture, 37, 65, 80 Nasopharyngeal meatus, 77 Nasopharynx, 77 249 — 250 Navicular bone of foot, 102, 103 development, 106 of hand, 89, 90 fibrocartilage, 141 Naviculari-cuneiform ligaments, dor- sal, 141 plantar, 141 Neck, fascie of, 177 ligaments of, 116 muscles of, 171 deep, 175 short, 155 development, 156 of femur, 97 of humerus, anatomical, 85 surgical, 86 of long bones, 20 of radius, 88 of ribs, 32 of scapula, 84 of talus, 102, 103 Nerves of bones, 21 Neurology, definition, 17 Nose, meatus of, 77 common, 77 inferior, 77 middle, 64, 77 superior, 64, 77 Nuchal fascia, 156 line, inferior, 41, 46 superior, 41, 46 surface of occipital bone, 46 Nutrient canal of arm, 87, 89 of bones, 20 of radius, 87, 89 foramen, 20 of tibia, 100 of ulna, 87 OB.LigueE head of adductor hallucis muscle, 226 ligament, 123 line of mandible, 72 of tibia, roo muscles, 164 popliteal ligaments, 135 Obliquus abdominis externus mus- cle; 157 functions of, 162 nerve supply of, 162 internus muscle, 157, 160 functions of, 162 nerve supply of, 162 capitis inferior muscle, 155 functions of, 155 nerve supply of, 155 superior muscle, 155 functions of, 155 nerve supply of, 155 Obturator externus muscle, 209, 216, 21 functions of, 218 nerve supply of, 218 foramen, 93, 96 groove, 95 internus muscle, 209, 213 functions of, 213 INDEX. Obturator internus muscle, nerve sup- ply of, 213 membrane, 115, 129 anterior, I15 posterior, 115 ridge, 95 tubercle, anterior, 95 posterior, 95 Occipital angle of parietal bone, 59 bone, 38, 40, 45 basilar portion of, 40, 45 borders of, 46 condyles of, 45 condyloid portions of, 45 development of, 47 in new-born, 47, 81 lambdoid border of, 46 lateral portions of, 40, 45 mastoid border of, 46 nuchal surface of, 41, 46 relations of, 38, 40 squamous portion of, 38, 45, 46 border of parietal bone, 59 condyles, 40 crest, external, 46 internal, 44, 46 fontanelle, 81 fossa, inferior, 44, 46 superior, 26 protuberance, external, 41, 46 internal, 43, 46 Occipitalis muscle, 178 functions of, 178 nerve supply of, 178 Occipitomastoid suture, 38, 40, 43, 53, 79 Occiput, articulation of first and sec- ond vertebre with, 113 Odontoid ligament, apical, 115 process, 25, 26 Olecranal burs, 208 Olecranon, 87 fossa, 87 Olivary eminence, 41, 48 Omohyoideus muscle, 172, 173 Opponens digiti quinti muscle, 200, 227 function of, 200, 227 nerve supply of, 200, 227 V muscle of foot, 186, 210 pollicis muscle, 186, 199 function of, 199 nerve supply of, 199 Optic foramen, 41, 48, 75 groove, 41, 48 Oral cavity, roof of, 78 muscles, 179, 180 Orbicular ligament, 132 muscles, 142 Orbicularis oculi muscle, 179 functions of, 180 nerve supply of, 180 oris muscle, 180, 181 Orbit, margins of, 75 walls of, 73, 74 development, 76 Orbital cavities, 37, 73 crest of sphenoidal bone, 59 Orbital fissure, inferior, 37, 39, 66, 71,74) 75 superior, 37, 42, 49, 74; 75 plates, 61 surfaces of, 61 portion of orbicularis oculi muscle, 179 process of palate bone, 70 surface of lachrymal bone, 65 of malar bone, 71 of orbital plates, 61 of sphenoid bone, 49, 50 of superior maxillary, 66 wings of sphenoid bone, 47, 49 Orifice of aqueeductus cochlee, 56 of canaliculus cochlee, 56 of maxillary sinus, 67 Origin of muscle, 142 Os basilare, 47, 51 capitatum, 89, 90 ince, 47 incisivum, 69 interparietale, 47 magnum, 89, 90 nasoturbinale, 64 planum, 63 trigonum, 103 Ossa Bertini, 48 suturarum, 82 Ossification, 21 centers, 21 Osteology, 19 definition, 17 general, 19 | special, 22 7 Outer crura of diaphragm, 165 head of gastrocnemius muscle, 220 . of triceps muscle, 190 leg muscles, 222 lip of linea aspera, 97, 98 portion of longus colli muscle, 176 vitreous table of flat bones, 19 Outgrowths, 20 Oval fossa, 232 PACCHIONIAN depressions, 44, 60 Palate bone, 69 development, 70 horizontal plates of, 69 in newborn, 70 perpendicular plate of, 69 processes of, 70 surfaces of, 69 hard, 39, 68, 78 in newborn, 68 tuberosity of, 40 Palatine canals, 69 cells, 63, 70 foramen, greater, 40, 69 lesser, 40, 70 grooves, 68 process, 39, 66, 68 spines, 68 suture, median, 39, 81 transverse, 39, 81 Palatoethmoidal suture, 80 Palatomaxillary suture, 80 Palm, tendons of, 205 flexor, 205 Palmar aponcurosis, 198, 207, 208 Palmaris brevis muscle, 180, 198 function of, 199 nerve supply of, 199 longus muscle, 185, 191 function of, 191 nerve supply of, 191 Palpebral ligament, internal, 179 eqoncies, 179 179 raphe, external, 179 Paraglenoidal groove, 95 Parietal angle, 50 bone, 36, 50 angles of, 59 borders of, 59 development of, 59, 60 in new-born, 60 — sulci of, 59 surfaces of, border of frontal bone, 60 of temporal bone, 52 - eminence, 59 oramen, 44, 59 notch, 52 surface of parietal bone, 59 arietomastoid suture, 38, 53, 79 irotideomasseteric fascia, 184 Patella, 99 apex Ee, 99 base of, 99 i evelopment, 99 — surfaces of, 99 Patellar ligament, 135 retinaculum, external, 135 internal, 135 surface of "femur, 98 ovial fold, 135 neal bursa, 234 fascia, 232 ne, 98 Pectineus muscle, 209, 216 function of, 216 nerve supply of, 216 oral fascia, 170 ect eae major muscle, 166 functions of, 167 nerve supply of, 167 minor muscle, 166, 168 functions of, 168 __ nerve supply of, 168 es of vertebra, 23 contraction, plane of, 130 throses, 128 ion, plane of, 130 €, 93 cos of, 128 portion of orbicularis oculi muscle, INDEX. Pelvis, aperture of, superior, 130 bony, 93 cavity of, 130 diameters of, 131 false, 130 female, 131 greater, 130 lesser, 130 ligaments of, 129 male, 131! true, 130 Penniform muscles, 142 Perichondrium, 21 Periosteum, 21 Peronzus brevis muscle, 210, 2 functions of, 223 nerve supply of, 223 longus muscle, 210, 222 function of, 222 nerve supply of, 222 sheath of, 231 tertius muscle, 210, 224 function of, 224 nerve supply of, 22 Peroneal groove, 103, 104 process, 103 retinaculum, inferior, 230 superior, 230 Perpendicular plate of ethmoid bone, 62, 63 of palate bone, 69 Pes anserinus, 214, 216 Petit’s triangle, 147 Petrooccipital fissure, 40, 43, 54, 81 synchondrosis, 81, 118 Petrosal border of sphenoidal bone, 50 fossa, 56 groove, inferior, 43, 45, 55 superior, 43, 55 Petrosquamosal fissure, 53, 54 suture, 81 Petrotympanic fissure, 53, 57 Petrous portion of temporal bone, 40, 52, 54 apex of, 55 Phalanges of foot, 82, 105 development, 106 of hand, 82, 92 articular capsules of, 12 articulations of, 127 borders of, 92 development, 92 movements of, 127 shaft of, 92 surfaces of, 92 trochlea of, 92 ungual, 92 Pharyngeal canal, 49, 51 tubercle, 45 Pillar of subcutaneous inguinal ring, anterior, 159 inferior, 158 posterior, 159 superior, 158 Pinnate muscles, 142 Piriform bursa, 234 Piriformis muscle, 209, 212 ed Ge 251 Piriformis muscle, function of, 213 nerve supply of, 213 Pisiform bone, 89, 90 articulation of, 124, 125 Pisohamate ligament, 125 Pisometacarpal ligament, 125 Pituitary body, 45 Pivot joint, 109 Plane of pelvic contraction, 130 expansion, 130 Plantar basal ligaments, 141 caleaneocuboid ligament, 141 calcaneonavicular ligament, 141 cuboideonavicular ligament, 141 cuneocuboid ligament, 141 eminence, external, 233 internal, 233 middle, 225, 233 intercuneiform ligaments, 141 interossei muscles, 227, 228 ligament, accessory, 139 long, 141 of foot, 140 naviculari-cuneiform ligaments, 141 surface, 18 tarsal ligaments, 141 tarsometatarsal ligaments, 141 Plantaris muscle, 220 Planum nuchale, 41, 46 occipitale, 41, 46 sternale, 34 temporale, 38, 50, 52, 59, 60 Platysma muscle, 171 functions of, 171 nerve supply of, 171 Pneumatic bones, 19 Polyaxial joints, 110 Popliteal bursa, 136, 221, 234 ligament, arcuate, 135 oblique, 135 line, 100 space, os Popliteus muscle, 210, function of, 221 nerve supply of, 221 Porus acusticus internus, 43 Positions, designations of, 17, 18 Postaxial muscles of lower extremity 235 of upper extremity, 209 Posterior abdominal muscle, 162 development, 164 annular ligament, 203, 208 arch of vertebra, 22 articular facet of calcaneus, 103 of talus, 102 atlanto-occipital membrane, 115 belly of digastricus muscle, 174 bursa of glutzus medius, 212 capitular ligament, 136 clinoid processes, 48 condyloid canal, 40 process of mandible, 72 costotransverse ligament, 116 cranial fossa, 41, 43 crucial ligament, 134 crus of subcutaneous inguinal ring, 159 219, 220 252 Posterior ethmoidal foramen, 61, 75 fontanelle, 81 gluteal line, 94 inferior spine of ilium, 94 intercondyloid fossa, 99 intermuscular septum, 233 interoccipital synchondrosis, 47 intertransversarius muscle, 155 intraoccipital synchondrosis, 81 lachrymal crest, 65 layer of lumbodorsal fascia, 156 ligament of external malleolus, 137 longitudinal ligament of vertebral column, III muscles of thigh, 218 nares, 39 nasal spine, 39, 69 obturator membrane, 115 tubercle, 95 pelvic surface, 96 pillar of subcutaneous inguinal ring, 159 portion of quadratus lumborum muscle, 162 process of talus, 102 sacral foramina, 29 sacrococcygeal ligaments, 113 sacroiliac ligament, 129 surface of fibula, ror of humerus, 86 of legs, muscles of, 219 of tibia, 100 of ulna, 87 of zygomatic bone, 71 talocalcaneal ligament, 140 talofibular ligament, 140 talotibial ligament, 139 trochanteric bursa of gluteus me- dius, 212, 234 Poupart’s ligament, 131, 163 Preaxial muscles of lower extremity, 235 of upper extremity, 209 Prepatellar bursa, subcutaneous, 136, 234 subfascial, 136 subtendinous, 136 Prevertebral cervical muscles, 176 fascia, 177 Procerus nasi muscle, 178 Processes, 20 accessory, 28 acromion, 84 alar, 63 alveolar, 37, 66, 68 articular, 20 of vertebre, 23 clinoid, anterior, 41, 49 middle, 48 posterior, 48 condyloid, 20, 38, 71, 72, 73 coracoid, 84 coronoid, of mandible, 38, 71, 73 anterior, 72 of ulna, 87 costal, 24 ethmoidal, of inferior turbinated, 64 INDEX. Processes, external angular, 36 of calcaneus, 103 of talus, 102 falciform, 129 frontal, of maxilla, 37, 66, 67 frontosphenoidal, 37, 71 hamular, 40, 51, 90 inferior, of temporal bone, 57 internal, of calcaneus, 103 intrajugular, 46, 55 jugular, 43, 46 lachrymal, of inferior turbinated, 64 mammillary, 28 mastoid, 38, 40, 53, 54 maxillary, of inferior turbinated, 64 nasal, of maxilla, 37, 66, 67 odontoid, 25, 26 of sacrum, superior articular, 29 of vertebre, 23 orbital, 70 palatine, 39, 66, 68 peroneal, 103 posterior, of talus, 102 pterygoid, 39, 47, 50 pterygospinous, 51 pyramidal, 4o of palate bone, 70 sphenoidal, of palate bone, 70 spinous, of tibia, 99 of vertebre, 23 styloid, of metacarpal bone, 91 of radius, 89 of temporal bone, 40, 56 of ulna, 88 supracondyloid, 87 temporal, of ulnar bone, 71 transverse, of vertebra, 23 trochlear, of calcaneus, 103 unciform, go uncinate, 64 vaginal, of pterygoid processes, 49, 51 of temporal bone, 56, 57 xiphoid, 34 foramen of, 36 zygomatic, of frontal bone, 60 of maxilla, 66, 67 of temporal bone, 36, 38, 39, 52 Processus Civinini, 51 costarius, 24 mastoideus, 40 pyramidalis, 40 Promontory, groove of, 58 of vertebral column, 30 Pronation, 124 Pronator quadratus muscle, 185, 194 function of, 194 nerve supply of, 194 teres muscle, 185, 191 function of, 191 nerve supply of, rgt Protuberance, mental, 71 Proximal radioulnar articulation, 122 Psoas major muscle, 210 minor muscle, 210, 211 Pterygoid canal, 50, 78 Pterygoid depression, 73 fossa, 40, 51 notch, 51 plate, external, 40, 50 internal, 40, 50 process, 39, 47, 50 tuberosity, 72 Pterygoidei muscles, 182, 183 functions of, 184 nerve supply of, 184 Pterygoideus externus muscle, 183 internus muscle, 183 Pterygomandibular raphe, 182, 184 Pterygomaxillary ligament, 184 Pterygopalatine canal, 51, 69 fossa, 50, 78 groove, 51, 67, 69 Pterygospinous ligament, 119 process, 51 Pubic angle, 131 arch, 131 ligaments, inferior, 128 superior, 128 Pubis, 93, 95 development, 96 ramus of, 95, 96 Pubocapsular ligament, 132 Pulleys, 143 Pulmonary groove, 35 Pulpy nucleus of intervertebral fibro- cartilage, IIo Pyramid of temporal bone, 52, 54 apex of, 55 Pyramidal eminence, 57 process of palate bone, 40, 70 Pyramidalis muscle, 161 functions of, 162 nerve supply of, 162 nasi muscle, 178 QuADRATUS femoris muscle, 209, 213 function of, 213 nerve supply of, 213 labii inferioris muscle, 181 superioris muscle, 180 lumborum muscle, 162 functions of, 163 nerve supply of, 163 plante muscle, 210, 225 function of, 225 nerve supply of, 225 Quadriceps femoris muscle, 209, 214 function of, 215 nerve supply of, 215 muscle, 142 Quadrilateral foramen, 166 RADIAL carpal eminence, 90 fossa, 87 head of flexor digitorum sublimis muscle, 192 lateral ligament, 122, 126 muscles of forearm, 194 nerve, groove for, 86 notch of ulna, 87 Radiate carpal ligament, 127 Radiate ligaments, 116, 117 Radiocarpal articulations, 124 ligament, dorsal, 126 volar, 126 Radioulnar articulation, distal, 123 roximal, 122 Radius, 82, 88 and ulna, relations, 89 articular circumference of, 88 borders of, 88 development, 89 extremities of, 88 head of, 88 interosseous ridge of, 88 neck of, 88 nutrient canal of, 89 shaft of, 88 surfaces of, 88 tuberosity of, 88 Radix arcus vertebra, 23 Ramus of ischium, 94 of mandible, 37, 71, 72 of pubis, 93, 95, 9 Rectus abdominis muscle, 161 development, 164 functions of, 162 nerve supply of, 162 capitis anterior major muscle, 176 minor muscle, 177 functions of, 177 nerve supply of, 177 lateralis muscle, 155 functions of, 155 nerve supply of, 155 "posterior major muscle, 155 crest for, 47 functions of, 155 nerve supply of, 155 minor muscle, 155 functions of, 155 nerve supply of, 155 femoris muscle, 214 muscles, 164 external, spine for, 76 Red bone-marrow, 21 lected inguinal ligament, 159, 164 nforcing ligaments, 108 R tinacula peronzorum, 222, 230 Retinaculum of arcuate ligament, 135 patellar, external, 135 internal, 135 peroneal, inferior, 230 - superior, 230 tendon, 142, 143 hens auriculze muscle, 179 chischisis, 36 nboid ligament, 119 -homboideus major muscle, 147 functions of, 147 nerve supply of, 147 minor muscles, 147 unctions of, 147 nerve supply of, 147 INDEX. Ribs, articulations of, with vertebral column, 26, 116, 117 body of, 32 bony, 32, 33 cervical, 35 curvature of, 33 development of, 35 eleventh, 33 false, 33 fenestration of, 36 first, 32 floating, 33 head of, 32 length of, 33 lumbar, 28, 35 movements of, 117 neck of, 32 sacral, 36 second, 33 surface curvature of, 33 torsion curvature of, 33 true, 33 twelfth, 33 typical, 32, 33 Ring, abdominal, external, 155 inguinal, subcutaneous, 155 Ridge, bicipital, 86 interosseous, of fibula, 101 of radius, 88 of tibia, 100 of ulna, 87 intertrochanteric, 97 obturator, 95 sphenomaxillary, 50 supinator, 87 temporal, 38 tubercular, greater, 86 lesser, 86 Risorius muscle, 180 Roof of oral cavity, 78 Root of vertebra, 2: Rostrum, sphenoidal, 48, 49 Rotary vertebra, 23 Rotatores breves muscles, 152, 153 longi muscles, 152, 153 muscles, 152, 153 functions of, 154 nerve supply of, 154 Round ligament, 132, 133 SACCULAR recess, 122, 123 Sacral canal, 29 cornu, 29 foramina, 28, 2 intervertebral, 29 ae 29, 31 rib, 36 tuberosity, 29 Sacrococcygeal ligament, anterior, 113 lateral, 113 posterior, 113 symphysis, 113 Sacroiliac articulation, 128 ligament, anterior, 129 interosseous, 129 posterior, 129 Sacrosciatic foramen, 130 ' 253 | Sacrosciatic ligament, greater, 129 l. lesser, 12g, 130 | Sacrospinalis muscle, 149 functions of, 154 nerve supply of, 154 Sacrospinous ligament, 129, 130 Sacrotuberous ligament, 129 Sacrum, 28 apex of, 28, 30 base of, 28 canal of, 29 crests of, 29 development of, 31 dorsal surface of, 29 female, 30 foramina of, 28, 2 intervertebral, 2 joints of, 113 male, 30 movements of, 113 pelvic surface of, 28 processes of, superior articular, 2 tuberosity of, 29 upper surface of, 29 Saddle joint, 110 Sagittal border of parietal bone, 59 groove, 44, 40, Go, O1 plane, 17 suture, 79 Saphenous opening of fascia lata, 232 vein, great, 232 Sartorial bursa, 214 Sartorius muscle, 209, 214 function of, 214 nerve supply of, 214 Scalene tubercle, 32 Scaleni muscles, 175 functions of, 176 nerve supply of, 176 Scalenus anterior muscle, 175 medius muscle, 175 minimus muscle, 176 | posterior muscle, 175 Scalp, muscles of, 175 | Scaphoid bone of foot, 102, 103 development, 106 of hand, 89, go fossa, 51 Scapula, 83 angles of, 83, 84 base of, 83 borders of, 83, S4 | development, 84 head of, 84 ligaments of, 120 margins of, 83 neck of, 84 spine of, 83, S4 surfaces of, 83 | | Scapular notch, 84 Scarpa's fascia, 163 | Sciatic bursa of gluta@us maximus, 234 foramen, great, 130 lesser, 130 notch, great, 94, 96 lesser, 96 | Second cuneiform bone, 104 ' Sella turcica, 41, 47, 48 254 Semicanal for Eustachian tube, 58 for tensor tympani, 58 Semicircular line, 161 Semilunar bone, 89, 90 cartilages, 133 function of, 136 line, 160 notch of ulnar, 87 surface of acetabulum, 96 Semimembranous bursa, 136, 219, 234 muscle, 209, 218, 219 function of, 219 nerve supply of, 219 Semispinalis capitis muscle, 151, 152 cervicis muscle, 152 dorsi muscle, 152 muscles, 152 functions of, 154 nerve supply of, 154 Semitendinosus muscle, 209, 218 function of, 219 nerve supply of, 219 Septum choanarum, 39, 66 intermuscular, 143 anterior, of leg, 233 external, of arm, 207 of thigh, 232 internal, of arm, 188, 207 of thigh, 232 of arm, 188, 207 of leg, 233 of thigh, 232 posterior, of leg, 233 nasal 375070,77 Serrate suture, 107 Serratus anterior muscle, 166, 168 functions of, 169 nerve supply of, 169 magnus muscle, 168 functions of, 169 nerve supply of, 169 posterior inferior muscle, 148, 171 functions of, 148 nerve supply of, 148 superior muscle, 148, 171 functions of, 148 nerve supply of, 148 Sesamoid bones, 143 of foot, 82, 106 of hand, 82, 92 Sheath, intertubercular mucous, 121, 188 peronzus longus, 231 rectus abdominis, 161 ° synovial, of dorsal carpal ligament, 203 of fingers, 205 of flexor tendons of palm, 205 of foot, 229 Short bones, 19 external lateral ligament of knee, 135 muscles, 142 of back, 154 development, 156 of neck, 155 development, 156 posterior sacroiliac ligament, 129 Shoulder, articulations of, 121 INDEX. Shoulder girdle, 83 muscles of, 185, 186 classification, 209 Shoulder-blade, 83. Shoulder-joint, 121 movements of, 121 Sigmoid groove, 43, 46, 53, 60 notch of mandible, 38, 71 of radius, 89 of ulna, greater, 87 lesser, 87 Simple joint, 109 Sinus, frontal, 61 development, 62 maxillary, 66 orifice of, 67 of tarsus, 102, 103 sphenoidal, 47 Skeleton, appendicular, 22 axial, 22 divisions of, 22 of extremities, 22, 82 of foot, Io1, 106 of free lower extremity, 97 upper extremity, 85 of hand, 92 of head, 22, 36 of lower extremities, 82, 93 of trunk, 22 variations in, 35 of upper extremities, 82, 83 Skull, 36 anterior aspect of, 36 base of, external surface of, 39 internal surface of, 41 bones of, 44 developmental classification, 44 disarticulated, 36 external surface of base of, 39 inner aspect of, 44 lateral aspect of, 37 of newborn, 81 superior aspect of, 44 sutures of, 79 Smiling muscle, 180 Sockets for teeth, 68 Sole of foot, muscles of, 225 Soleus, arch of, 220 muscle, 219, 220 Special anatomy, definition, 17 Sphenoethmoidal recess, 77 suture, 79 Sphenofrontal suture, 37, 41, 49, 79 Sphenoid bone, 37, 39, 47 body of, 47 borders of, 49, 50 cerebral juga of, 50 surface of, 42 development of, 51 digitate impressions of, 50 greater wing of, 42 in newborn, 51, 81 lesser wings of, 41 orbital crest of, 50 variations in, 51 wings of, greater, 47, 49 surfaces of, 49 lesser, 47, 49 See also Scapula. Sphenoid bone, wings of, orbital, 47, 49 temporal, 47, 49 spine of, 39 Sphenoidal angle, 36, 59 cells, 63 crest, 48 fissure, 37) 42, 49, 74) 75 fontanelles, 82 process of palate bone, 70 rostrum, 48, 49 sinus, 47 spine, 56 turbinated bones, 48 Sphenomandibular ligament, 118 Sphenomaxillary fissure, 37, 39, 71, 74, 75 fossa, 49, 50, 78 ridge, 50 surface of sphenoidal bone, 50 suture, 81 Sphenooccipital fissure, 45 synchondrosis, 41, 45, 47, 81 Sphenoorbital suture, 79 Sphenopalatine foramen, 70, 78 notch, 70 Sphenoparietal suture, 37, 38, 42, 79, 82 Sphenopetrosal fissure, 39, 40, 42, 54, 55, 81 synchondrosis, 81, 118 Sphenosquamosal suture, 38, 39, 42, 43, 52, 80 Sphenozygomatic suture, 37, 38, 50, 80 Spheroid joints, r1o Sphincter muscles, 142 oris muscle, 181 Spigelius’ line, 160 Spina recti lateralis, 50 Spinal canal, 31 column, 22. umn. Spinalis capitis muscle, 151, 152 cervicis muscle, 151 dorsi muscle, 151 muscles, 149, I5I functions of, 154 nerve supply of, 154 Spindle-shaped muscles, 142 Spine, 20 anterior nasal, 37 ethmoidal, 41, 48 for external rectus muscle, 76 frontal, 61 mental, 72 nasal anterior, 68 posterior, 69 of ilium, anterior inferior, 94 superior, 94 posterior inferior, 94 of ischium, 96 of pubis, 95 of scapula, 83, 84 palatine, 68 sphenoidal, 56 suprameatal, 52 trochlear, 61 tympanic, greater, 57 lesser, 57 See also Vertebral col- a Spinotransversalis muscle, 149 Spinous process of tibia, 99 of vertebra, 23 epi al joint, 1c9 Spla nchnology, definition, 17 Splenius capitis muscle, 148 7 functions of, 148 nerve supply of, 148 ~ cervicis muscle, 148 functions of, 148 nerve supply of, 148 Squamosal border of parietal bone, 59 of sphenoid bone, 50 suture, 38, 43. 52, 79 amosomastoid suture, 53, 59, 81 SO od 38, 45, 46 of temporal bone, 38, 40, 43, 52 _ suture, 107 Stellate ligaments, 116, 117 Sternal extremity of clavicle, 85 _ membrane, 117 portion of diaphragm, 164 _ synchondrosis, 117 Sternalis muscle, 167 Sternoclavicular articulation, 119 Beeement, 119 Sternocleidomastoideus muscle, 171 functions of, 172 = nerve supply of, 172 Sternocostal articulations, 117 _ 167 ternohyoideus muscle, 172 rnothyreoideus muscle, 172 : lernum, 22, 34 angle of, 34 g feulations of ribs with, 116, 117 body of, 34 development of, 35 foramen of, 36 gladiolus of, 34 mz nubrium: of, 34 notches of, 34 x miphoid process of, 34 str raight abdominal muscle, 161 development, 164 stylohyoid ligament, 119 tylohyoideus muscle, 174 functions of, 174 nerve supply of, 174 Dot radius, 89 of temporal bone, 40, 56 ae ulna, 88 mandibular ligament, 118, 184 astoid foramen, 40, 56 cillary ligament, 184 bacromial bursa, 208 late fossa, 55 an groove, 33 us muscle, 166, 168 ions of, 168 ‘supply of, 168 al angle, 35 les muscles, 169, 170 rloma uamous portions of occipital bone, portion of pectoralis major muscle, bursa of tuberosity of INDEX. | Subcutaneous calcaneal bursa, 235 | tyloid process of metacarpal bone, or | colli muscle, 171 digital burs, dorsal], 208 epicondylar burs#, 208 external malleolar bursa, 234 infrapatellar bursa, 136, 234 inguinal ring, 155 internal malleolar bursa, 234 metacarpophalangeal bursa, dorsal, 208 olecranal bursa, 208 prepatellar bursa, 136, trochanteric bursa, 233 Subdeltoid bursa, 186, 205 Subfascial prepatellar bursa, 136 Suboccipital triangle, 156 Subscapular bursa, 121, 188 fascia, 207 fossa, 83 Subscapularis muscle, 185, functions of, 1835 nerve supply of, 188 Subtendinous bursa of tibialis ante- rior, 235 posterior, 235 iliac bursa, 234 olecranal bursa, 208 prepatellar bursa, 136 Sulcus, 20 arteriosus, 43, 44 of frontal bone, 61 of parietal bone, 59 of sphenoid bone, 50 of temporal bone, 53 calcaneus, 103 chiasmatis, 41, 48 gluteal, 232 nervi spinalis, 24 tali, 102 venosus, of parietal bone, 59 Superciliary arches, 60 Superficial fascia, general, 163 head of flexor pollicis brevis muscle, 199 layer of calf muscles, 219 of cervical fascia, 177 of extensors of forearm, 196 of flexor muscles of forearm, 191 posterior sacrococcygeal ligament, 113 temporal fascia, 184 Superior angle of ag 83, 84 aperture of pelvis, 130 of tympanic canaliculus, 54 articular processes of sacrum, 29 surfaces of tibia, 99 belly of omohyoideus muscle, 173 bicipital bursa, 234 border of scapula, 84 cornu of fascia lata, 232 costotransverse ligament, 116 crus of subcutaneous inguinal ring, 158 extremity of femur, 97 of fibula, ror of humerus, 85 of radius, 88 of tibia, 99 234 187 | Superior extremity of ulna, 87 gluteal line, O4 intervertebral notch, 23 margin of scapula, 83 maxillary,66. See also Maxille. meatus of nose, 64, 77 nuchal! line, 41, 46 occipital fosse, 46 orbital! fissure, 37. 42, 49. 74 75 peroneal retinaculum, 230 petrosal groove, 43, 55 pillar of subcutaneous inguinal ring 155 pubic ligament, 128 ramus of ischium, 94 of pubis, 93, 95 surface of talus, 102 temporal line, 59 thoracic aperture, 35 transverse ligament, turbinated bone, 63 vertebral notches, 23 Supernumerary bones, 82 Supination, 124 Supinator brevis muscle, 195 longus muscle, 194 muscle, 185, 195 function of, 196 nerve supply of, 196 ridge, 87 Supraclavicular fossa, lesser, 171 Supracondyloid process, 87 Supraglenoidal tuberosity, 84 Suprahyoid muscles, 174 Supramastoid ridge, 52 Suprameatal spine, 52 Supraorbital border of frontal bon: 60 foramen, 60, 75, 7 margin, 75 notch, 60, 75 Suprapatellar bursa, 135, 234 Supraspinatus fascia, 207 fossa of scapula, 83 muscle, 185, 186 function of, 187 nerve supply of, 187 Supraspinous ligament, 112 Surgical neck of humerus, 86 Sustentaculum tali, 103 Sutura mendosa, 47, 81 120 | Sutur@ serrate, 59 Suture, 107 coronal, 36, 37. 79 ethmoidcomaxillary, 80 frontal, 60, 81 frontocthmoidal, 41, 61, 81 frontolachrymal, 37, 80 frontomaxillary, 37, 80 harmonic, 107 incisive, 60, 81 infraorbital, 68, 8x intermaxillary, 37, 80 internasal, 37, 65, 80 lachrymoconchal, 80 lachrymoethmoidal, 80 lachrymomaxillary, 80 lambdoid, 38, 79 256 Suture, median palatine, 39, 81 mendosal, 47, 81 metopic, 60, 62, 81 nasofrontal, 37, 65, 80 nasomaxillary, 37, 65, 80 occipitomastoid, 38, 40, 43, 53, 79 of skull, 79 palatine, median, 39, 81 transverse, 39, 81 palatoethmoidal, 80 palatomaxillary, 80 parietomastoid, 38, 53, 79 petrosquamosal, 81 sagittal, 79 serrate, 59, 107 sphenoethmoidal, 79 sphenofrontal, 37, 41, 49, 79 sphenomaxillary, 81 sphenoorbital, 79 sphenoparietal, 37, 38, 42, 79, 82 sphenosquamosal, 38, 39, 42, 43, 52; 80 sphenozygomatic, 37, 38, 50, 80 squamosal, 38, 43, 52, 79, 107 squamosomastoid, 53, 59, 81 transverse palatine, 39, 81 zygomaticofrontal, 36, 37, 80 zygomaticomaxillary, 37, 39, 67, 80 zygomaticotemporal, 38, 52, 80 Symphysis, 107 pubis, 95, 128 sacrococcygeal, 113 Synarthrosis, 107 mixed, 107 pelvic, 128 Synchondrosis, 107 epiphyseos, 21 interoccipital, anterior, 47 posterior, 47 intersphenoidal, 51, 81 intraoccipital, anterior, 81 posterior, 81 petrooccipital, 81, 118 sphenooccipital, 41, 45, 47, 81 sphenopetrosal, 81, 118 sternal, 34, I17 Syndesmology, 107 definition, 17 general, 107 special, 110 Syndesmosis, 107 tibiofibular, 136, 137 true, 107 Synergists, 143 Synovia, 108 Synovial burs, 108 communicating, 108 folds, 108 patellar, 135 layer of articular capsule, 108 membrane, 108 sheaths of dorsal carpal ligament,203 of fingers, 205 of flexor tendons of palm, 205 of foot, 229 of peroneus longus, 231 villi, 108 Systematic anatomy, definition, 17 INDEX. TALOCALCANEAL articulation, 137, 138 anterior, 138 ligament, anterior, 140 external, 140 internal, 140 interosseous, 140 posterior, 140 Talocalcaneonavicular 137, 138 Talocrural articulation, 137 Talofibular ligament, anterior, 140 posterior, 140 Talonavicular articulation, 138 ligament, dorsal, 140 Talotibial ligament, anterior, 139 posterior, 139 Talus, 102 articular facets of, 102 articulations of, 137 body of, 102 development, 106 groove of, 102 head of, 102, 103 neck of, 102, 103 surfaces of, 102 Tarsal bones, 82, 102 articulations of, 137, 138 development, 106 ligaments, 139 dorsal, 140 plantar, 141 Tarsometatarsal 139 ligaments, dorsal, 141 plantar, 141 Tarsus, 102 articulations of, 137, 138 ligaments of, 139 sinus of, 102, 103 transverse articulation of, 138 Tectorial membrane, III, 115 Teeth, alveoli for, 68, 71 incisor, in fetus, 69 sockets of, 68, 717 Tegmen tympani, 55, 57 Temporal bone, 37, 38, 51 articular eminence of, 53 canals of. 57 development of 58 in newborn, 58, 59, 81 inferior process of, 57 mastoid portion of, 38, 40, 52, 53 petrous portion of, 40, 52, 54 articulation, articulations, 137, apex of, 55 pyramid of, 52, 54 apex of, 55 squamous portion of, 38, 40, 43, 52 tympanic portion of, 38, 40, 52, eS fascia, 184 fossa, 38 line. 44, 60 inferior, 59 superior, 590 process of zygomatic bone, 71 ridge, 38 surface of zygomatic bone, 71 Temporal surface of spheneid bone, 49, 5° of squamous portion of temporal bone, 52 wings of sphenoid bone, 47, 49 Temporalis muscle, 182, 183 functions of, 183 nerve supply of, 183 Temporomandibular articulation, 118 ligament, 118 Temporomazxillary articulation, 117 Tendinous adductor opening, 217 arches, 143 inscriptions, 143 of rectus abdominis, 161 Tendo Achillis, 220 Tendons, 142 central, of diaphragm, 164, 165 chiasma of, 207 flexor, of palm, 205 of fingers, extensor, 204 of hand, extensor, 203 of long head of biceps, 121 of palm, 205 retinacula, 142, 143 vincula, 207 Tendon-sheaths, 143 Tensor fascie latee muscle, 209, 213 function of, 214 nerve supply of, 214 tympani, semicanal for, 58 Teres major muscle, 185, 187 function of, 187 nerve supply of, 187 minor muscle, 185, 187 function of, 187 nerve supply of, 187 Terminal line of ilium, 95 Thenar eminences, 198 muscles of, 199 Thigh, adductor muscles of, 216 anterior surface of, muscles of, 214 fascia of, 231 flexors of, 218 internal muscles of, 216 muscles of, 214 classification, 235 posterior muscles of, 218 Third cuneiform bone, 104 trochanter, 98 Thoracic muscles, 166 vertebra, 26 eleventh, 26, 27 first, 26 walls, nvuscles of, 169 Thorax, 22, 35 apertures of, 35 muscles of, 166 walls of, muscles of, 169 Thumb, bones of, 92 carpometacarpal joint of, 124, 125 metacarpophalangeal articulation of, r27 j Thyreohyoideus muscle, 172, 173 Tibia, 82, 99 and fibula, relations, rot articular surfaces of, inferior, 100 superior, 99 | ‘Tibia, articulations of, 136 borders of, 100 condyles of, 99 crest of, 100 development, 101 extremities of, 99 interosseous membrane of, 136, 137 shaft of, 99, 100 surfaces of inferior extremity of, 99 of shaft of, 100 of superior extremity of, 99 tuberosity of, subcutaneous bursa of, 234 ibial lateral ligament, 134 Tibialis anterior muscle, 210, 223 function of, 223 nerve supply of, 223 posterior muscle, 210, 219, 221 function of, 221 nerve supply of, 221 Tibiofibular articulation, 136 syndesmosis, 136, 137 Tibionavicular ligament, 139, 140 Tissue, bony, 20 Toes, articulations of, 137 bones of, 105 t, ball of, muscles of, 226 — little, ball of, muscles of, 227 Topographic anatomy, definition, 17 ‘Torus Sesame 78 “g achelomastoid muscle, 151 ansversalis capitis muscle, 151 _cervicis muscle, 151 _ fascia, 163 Transverse articulation of tarsus, 138 capitular ligament of foot, 139 of hand, 127 carpal ligament, 127, 205 crural ligament, 233 fasciculi, 233 groove, 43, 46 head of adductor hallucis muscle, 227 ligament, inferior, 121 of atlas, 114 of hip, 131 of knee, 134 Superior, 120 ; lines of rectus abdominis, 161 palatine suture, 39, 81 te ane, 17 ion of nasalis muscle, 182 processes of vertebra, 23 ansversocostal muscles, 156, 157 ransversospinalis muscle, 149, 151, ansversus abdominis muscle, 157, i) G0: functions of, 162 INDEX. Trapezoid ligament, 120 Triangle, deltoideopectoral, 167 femoral, 216 lumbar, 147 of Petit, 147 suboccipital, 156 Triangular ligament, 159, 164 Triangularis labii inferioris muscle, | 181 superioris muscle, 181 muscle, 181 sterni muscle, 170 Triceps brachii muscle, 142, 185, 189 function of, 190 heads of, 189, 190 nerve supply of, 190 sure muscle, 210, 219 function of, 220 nerve supply of, 220 Trigeminal impression, 43, 55 Triquetral bone, 89, go Trochanteric bursa, 212 of gluteus maximus, 233 medius, anterior, 234 posterior, 212, 234 minimus, 234 subcutaneous, 233 fossa, 97 Trochanters, 97 greater, 97 lesser, 97 third, 98 Trochlex, 143 of phalanges of foot, 105 of hand, 92 of talus, 102 Trochlear area of humerus, 86 depression, 61, 76 process of calcaneus, 103 spine, 61 Trochoid joint, 109 True joints, 108 pelvis, 130 ribs, 33 syndesmosis, 107 vertebra, 22 Trunk, muscles of, 144 skeleton of, 22 variations in, 35 Tubercle, 20 carotid, 26 costal, ligament of, 116 intercondyloid, external, 99 internal, 99 jugular, 43, 46 mental, 72 obturator, anterior, 95 posterior, 95 of Chassaignac, 26 of humerus, greater, 85 lesser, 85 of Lisfranc, 32 of neck of ribs, 32 of pubis, 95 of talus, external, ro2 internal, 102 of trapezium, go pharyngeal, 45 | 257 Tubercle, scalene, 32 Tubercular ridge, greater, 86 lesser, 56 Tuberculum caroticum, 26 sella, 41, 45 Tuberositas atlantis, 2 Tuberosities, 20 coracoid, 85 costal, 55 deltoid, 86 gluteal, 98 infraglenoidal, 84 masseteric, 72 of calcaneus, 103 of fifth metatarsal bone, 105 of first metatarsal bone, 105 of hard palate, 40 of ilium, 95 of ischium, 96 of maxilla, 67 of navicular bone, 103 of palate bone, 70 of radius, 88 of scaphoid bone, 103 of tibia, 100 subcutaneous bursa of, 234 of ulna, 87 pterygoid, 72 sacral, 29 supraglenoidal, 84 ungual, 92, 105 Tubular bones, 19 Turbinated bones, 37, 77 inferior, 64, 67, 77 development, 64 middle, 63 sphenoidal, 48 supenor, 03 Tympanic annulus, 81 antrum, 54, 55 canaliculus, 58 aperture of, superior, 54 groove, $7 notch, 57 portion of temporal bone, 38, 40, §2, 57 spines, greater, 57 lesser, 57 Tympanomastoid fissure, 53, §7 Tympanosquamosal fissure, §7 Una, 82, 87 and radius, relations, 89 borders of, 87 development, 8S extremities of, 87, 88 shaft of, 87 surfaces of, 87 Ulnar carpal eminence, go head of flexor carpi ulnaris muscle, 192 of pronator teres muscle, 191 lateral ligament, 122, 126 notch, 89 Unciform bone, 89, 90 process, 90 Uncinate process, 64 258 Ungual phalanges, 92 tuberosity, 92, 105 Uniaxial joints, 109 Unilocular joints, 108 Upper arm, extensor surface of, mus- cles of, 189 flexor surface of, muscles of, 188 muscles of, 185, 188 classification, 209 extremity, articulations of, r19 burs of, 208 fasciz of, 207 free, skeleton of, 85 ligaments of, 119 muscles of, 185 development, 209 skeleton of, 82, 83 thoracic muscles of, 166 portion of longus colli muscle, 176 VAGINE mucose®, 142, 143 Vaginal ligaments, 143 of foot, 231 process, 49, 51 of temporal bone, 56, 57 Vastus externus muscle, 215 intermedius muscle, 215 internus muscle, 215 lateralis muscle, 215 medialis muscle, 215 Vein, saphenous, great, 232 vertebral, canal for, 26 Vena caval opening of diaphragm, 166 Ventral arch of vertebra, 22 Vertebrz, 22 arches of, 22, 23 articular processes of, 23 bodies of, 22, 23 connections of, 110 caudales, 30 cervical, 23 characters of, 24 first, 23, 25 and second, 113 development, 31 second, 23, 25 development, 31 articulations of, INDEX. Vertebrz, cervical, seventh, 24 third to sixth, 24 development, 31 false, 22, 28 flexion, 23 lumbar, 27 lumbosacral, 30, 36 pedicles of, 23 processes of, 23 prominens, 25 root of, 23 rotatory, 23 spinous processes of, 23 supernumerary, 35 thoracic, 26 first, 26 twelfth, 26, 27 transverse processes of, 23 true, 22 Vertebral arches, ligaments between, 112 artery, 25 canal for, 26 border of scapula, 83 canal, 31 column, 22, 30 articulation of ribs with, 116, 117, 261 curvature of, 30 development, 31 intertransverse ligaments of, 112 joints of, 110 ligaments of, 111 movements of, 113 promontory of, 30 margin of scapula, 83 notches, 23 vein, canal for, 26 Vertical portion of squamous portion of temporal bone, 52 Vidian canal, 50 Villi, synovial, 108 Vincula, 143 of tendon, 207 Visceral bones, 22 Vitreous tables of flat bones, 19 Volar basal ligaments, 127 border of radius, 88 of ulna, 87 Volar carpal ligament, 208 carpometacarpal ligament, 127 intercarpal ligament, 17 ligaments, accessory, 127 radiocarpal ligament, 126 surface, 18 of radius, 88 of ulna, 87 Vomer, 39, 65 ale of, 65 development, 66 WA tts of thorax, muscles of, 169 Wings of sphenoid bone, 47, 49 Wormian bones, 82 Wrist-joint, 124 XIPHOID process, 34 foramen of, 36 YELLOW bone-marrow, 21 ZonaA orbicularis, 132 Zygoma, 70 Zygomatic arch, 38, 39, 40 bone, 36, 70 development, 71 surfaces of, 71 border of sphenoid bone, 50 fossa, 79 head of quadratus labii superioris muscle, 180 process of frontal bone, 60 of maxilla, 66, 67 of temporal bone, 36, 38, 39, 52 Zygomaticofacial foramen, 71 Zygomaticofrontal suture, 36, 37, 80 Zygomaticomaxillary suture, 37, 39, 67, 80 Zygomaticoorbital foramen, 71, 75 Zygomaticotemporal foramen, 71 suture, 38, 52, 80 Zygomaticus major muscle, 180 minor muscle, 180 muscles, 180 GYNECOLOGY OBSTETRICS W. B. SAUNDERS COMPANY WEST WASHINGTON SQUARE PHILADELPHIA 9, HENRIETTA STREET COVENT GARDEN, LONDON SAUNDERS’ ANNOUNCEMENTS HAVE AN ANNUAL CIRCULATION OF OVER 5,000,000 HE recent growth of our foreign business necessitated some further provision for brining our new books before the English-speak fess 1 In addition to our front cover and inside space in the British Medical Journal and the London Lancet, we have, therefore, recently arrat for front er and inside space in the Indian Medical Gaz ette, the China Medical Journal, and the Bulletin of the Manila Medical Society—each : nal u its field. The extension of our advertising has always gone hand in hand th the ex pansion of our business both at home and abroad. In 1905 we 10 journals ; in 1906 and 1907, in It journals; in 1908, in 13 journals in 16 journals ; in Ig1o, in 17 journals; in IgII, in 1& journals ; and in 1913, in 26 journals. Our announcements 1 have an annual circulation of over 5,000,000, or nearly 100 every week in the year. A Complete Catalogue of Our Publications will be Sent Upon Request z SAUNDERS’ BOOKS ON De Lee’s Obstetrics Principles and Practice of Obstetrics. By JoszepH B. DE LEE, M. D., Professor of Obstetrics in the Northwestern University Medical School, Chicago. Large octavo of 1060 pages, with 913 illustrations, 150 in colors. Cloth, $8.00 net; Half Morocco, $9.50 net. THREE PRINTINGS IN TEN MONTHS The Most Superb Book on Obstetrics Ever Published You will pronounce this new book by Dr. DeLee the most elaborate, the most superbly illustrated work on Obstetrics you have ever seen. Especially will you value the 973 z//ustrations, practically all original, and the best work of lead- ing medical artists. Some 150 of these illustrations are in colors. Such a mag- nificent collection of obstetric pictures—and with really practical value—has never before appeared in one book. You will find the text extremely practical throughout, Dr. De Lee’s aim being to produce a book that would meet the needs of the general practitioner in every par- ticular. For this reason diagnosis is featured, and the relations of obstetric con- ditions and accidents to general medicine, surgery, and the specialties brought into prominence. Regarding “reatment: You get here the very latest advances in this field, and you can rest assured every method of treatment, every step in operative technic, is just right. Dr. De Lee’s twenty-one years’ experience as a teacher and obstetrician guarantees this. Worthy of your particular attention are the descriptive legends under the illus- trations. These are unusually full, and by studying the pictures serially with their detailed legends, you are better able to follow the operations than by referring to the pictures from a distant text—the usual method. Dr. M. A. Hanna, University Medical College, Kansas City ‘‘T am frank in stating that I prize itmore highly than any other volume in my obstetric library, which consists of practically all the recent books on that subject.” Dr. Clark E. Day, Zrdianapolis, Ind. “Dr, DeLee’s work is by far the greatest on Obstetrics published to-day for the general practitioner. It will meet what is expected of it in a more concise and comprehensive way than any other book he could buy.”’ Dr. George L. Brodhead, New York Post-Graduate Medical School “The name of the author is in itself a sufficient guarantee of the merit of the book, and I congratulate him, as well as you, on the superb work just published.” GYNECOLOGY AND OBST} LRICS 3 Norris’ Gonorrhea in Women Gonorrhea in Women. By Cy apy ps | Norris, M. D., Ih in Gynecology, University of Pennsylvania, With a Introducti Joun G. Crark, M. D., Professor of Gynecol. y, University of Penn- sylvania. Large octavo of 520 pages, illustrated. Cloth, s¢ A CLASSIC Dr. Norris here presents a work that is destined to take high place amor publications on this Subject. He has done his work thor the important literature very carefully, over 2300 references bein coupled with Dr. Norris’ large experience, gives his book the The chapter on serum and vaccine therapy and organotheray valuable because it expresses the newest advances. Eve ry phase of the is considered: History, ba teriology, pathology, sé (operative and medicinal), gonorrhea during preenan perium, diffuse gonorrheal pertitonitis, and all other phases also considers the rare varieties of gonorrhea occurring in men, women children. ‘The text is illustrated. a American Text-Book of Gynecology Second Revised Edition American Text-Book of Gynecology. Edited by J. M. Batpy, M.D. Imperial octavo of 718 pages, with 341 text-illustrations and 38 plates. Cloth, $6.00 net. American Text-Book of Obstetrics Second Revised Edition The American Text-Book of Obstetrics. In two volumes. Edited by Ricuarp C. Norris, M. D.: Art Editor, Robert L. Dickinson, M. D. Two octavos of about 600 pages each ; nearly goo illustrations, includ- ing 49 colored and _ half-tone plates. Per volume: Cloth, $3.50 net. “As an authority, as a book of reference, as a ‘ working book ’ for the student or practi- tioner, we commend it because we believe there is no better,’’—AMERICAN JOURNAL OF THE MBDICAL SCIENCES. t SAUNDERS’ BOOKS ON Ashton’s Practice of Gynecology The Practice of Gynecology. By W. Easrerty Asuton, M.D., LL.D., Professor of Gynecology in the Medico-Chirurgical College, Philadelphia. Handsome octavo volume of 1100 pages, containing 1058 original line drawings. Cloth, $6.50 net; Half Morocco, $8.00 net. NEW (5th) EDITION The continued success of Dr. Ashton’s work is not surprising to any one knowing the book. ‘The author takes up each procedure necessary to gynecologic step by step, the student being led from one step to another, just as in studying any non-medical subject, the minutest detail being explained in language that cannot fail to be understood even at first reading. Nothing is left to be taken for granted, the author not only telling his readers in every instance what should be done, but also precisely how to do zt. A distinctly original feature of the book is the illustrations, numbering 1058 line drawings made especially under the author's personal supervision from actual apparatus, living models, and dissections on the cadaver. From its first appearance Dr. Ashton’s book set a standard in fractical medical books; that he Zas produced a work of unusual value to the medical practitioner is shown by the demand for new editions. Indeed, the book is a rich store-house of practical information, presented in such a way that the work cannot fail to be of daily service to the practitioner. Howard A. Kelly, M. D. Professor of Gynecologic Surgery, Johns Hopkins University. “Tt is different from anything that has as yet appeared. The illustrations are particuiarly clear and satisfactory. One specially good feature is the pains with which you describe sa many details so often left to the imagination.” Charles B. Penrose, M. D. Formerly Professor of Gynecology in the University of Pennsylvania “TI know of no book that goes so thoroughly and satisfactorily into all the detaz/s of every- thing connected with the subject. In this respect your book differs from the others.” George M. Edebohls, M. D. Professor of Diseases of Women, New York Post-Graduate Medical School ‘* A text-book most admirably adapted to feach gynecology to those who must get their knowledge, even to the minutest and most elementary details, from books.” Bandler’s Medical Gynecology Medical Gynecology. By S. Wy.tiis BaNpLer, M. D., Adjunet Professor of Diseases of Women, New York Post-Graduate Medical School and Hospital. Octavo of 790 pages, with 150 original illus- trations. Cloth, $5.00 net; Half Morocco, $6.50 net. NEW (3d) EDITION—60 PAGES ON INTERNAL SECRETIONS This new work by Dr. Bandler is just the book that the physician engaged in general practice has long needed. It is truly the practitioner's gy /ogyv—planned for him, written for him, and illustrated for him. ‘There are many gyne conditions that do not call for operative treatment; yet, because of lack of that special knowledge required for their diagnosis and treatment, the general practi- tioner has been unable to treat them intelligently. This work not or deals with those conditions amenable to non-operative treatment, but it also tel recognize those diseases demanding operative treatment. American Journal of Obstetrics ‘‘He has shown good judgment in the selection of his data. He g on diagnostic and therapeutic aspects. He has presented his facts > t ra I grasped by the general practitioner. Bandler’s Vaginal Celiotomy Vaginal Celiotomy. By S. Wy.iis BANDLER, M. D., New York Post-Graduate Medical School and Hospital. Octavo of 450 pages, with 148 original illustrations. Cloth, $5.00 net; Half Morocco, $6.50 net. SUPERB ILLUSTRATIONS The vaginal route, because of its simplicity, ease of execution, absence of shock, more certain results, and the opportunity for conservative measures, con- stitutes a field which should appeal to all surgeons, gynecologists, and obstetricians. Posterior vaginal celiotomy is of great importance in the removal of small tubal and ovarian tumors and cysts, and is an important step in the performance of vaginal myomectomy, hysterectomy, and hysteromyomectomy. Anterior vaginal celiotomy with thorough separation of the bladder is the only certain method of correcting cystocele. The Lancet, London “Dr. Bandler has done good service in writing this book, which gives a very clear descrip- tion of all the operations which may be undertaken through the vagina. He makes out a strong case for these operations.” 6 SAUNDERS’ BOOKS ON Kelly and Noble’s Gynecology and Abdominal Surgery Gynecology and Abdominal Surgery. Edited by Howarp A. Ke tty, M. D., Professor of Gynecology in Johns Hopkins University ; and CuHaries P. Nosie, M.D., formerly Clinical Professor of Gyne- cology in the Woman’s Medical College, Philadelphia. Two imperial octavo volumes of 950 pages each, containing 880 illustrations, some in colors. Per volume: Cloth, $8.00 net; Half Morocco, $9.50 net. TRANSLATED INTO SPANISH WITH 880 ILLUSTRATIONS BY HERMANN BECKER AND MAX BRODEL In view of the intimate association of gynecology with abdominal surgery the editors have combined these two important subjects in one work. For this reason the work will be doubly valuable, for not only the gynecologist and general prac- titioner will find it an exhaustive treatise, but the surgeon also will find here the latest technic of the various abdominal operations. It possesses a number of valuable features not to be found in any other publication covering the same fields. It contains a chapter upon the bacteriology and one upon the pathology of gyne- cology, dealing fully with the scientific basis of gynecology. Inno other work can this information, prepared by specialists, be found as separate chapters. There is a large chapter devoted entirely to medical gynecology written especially for the physician engaged in general practice. Heretofore the general practitioner was compelled to searci through an entire work in order to obtain the information desired. Abdominal surgery proper, as distinct from gynecology, is fully treated, embracing operations upon the stomach, upon the intestines, upon the liver and bile-ducts, upon the pancreas and spleen, upon the kidneys, ureter, bladder, and the peritoneum. The illustrations are truly magnificent, being the work of Wm Flermann Becker and Mr. Max Bride. American Journal of the Medical Sciences “Tt is needless to say that the work has been thoroughly done: the names of the authors and editors would guarantee this; but much may be said in praise of the method of presen- tation, and attention may be called to the inclusion of matter uot to be found elsewhere.” Webster’s Text-Book gf Obstetrics A Text-Book of Obstetrics. By J. CLARENCE Wi rer. M. —D (Epin.), F. R. C. P. E., Professor of Obstetri: nd Gynecol in Rush Medical College, in affiliation with the University of Chica Octavo volume of 767 pages, illustrated. Cloth, $5 net: Half Mor O, $6.50 net. BEAUTIFULLY ILLUSTRATED In this work the anatomic changes accompany!! regnal the puerperium are described more full the subject. The exposition of these sections ased mail tudies of frozen specimens. Unusual consideration is given to et data of importance in their relation to obstetri Buffalo Medical Journal ‘* As a pri practical text-book on obstetr f little to be desired, it being Webster’s Diseases of Women A Text-Book of Diseases of Women. Jy |. CLAREN Wi M. D. (Eprn.), F. R. C. P. E., Professor of Gynecology and O in Rush Medical College. Octavo of 712 pages, with 372% tions and 10 colored plates. Cloth, $7.00 net; Half Mor , $8.50 net Dr. Webster has written this work cussing the clinical features of the subject practice rather than from the standpoint of specialis: rhe ma ent illus- trations, three hundred and seventy-two in number, are nearly a nal. Howard A. Kelly. M, D. Professor of Gynecologic Surgery lohns Hopkins Uni “It is undoubtedly one of ¢ years, showing from start to finish Dr. W t wie t ] illustrations are also of the highest order.” Hirst’s Text-Book of Obstetrics The New (7th) Edition A Text-Book of Obstetrics. By Barton Cooke Hirst, M.D., Professor of Obstetrics in the University of Pennsylvania. Handsome octavo of 1013 pages, with 895 illustrations, 53 of them in colors. Cloth, $5.00 net; Half Morocco, $6.50 net. INCLUDING RELATED GYNECOLOGIC OPERATIONS Immediately on its publication this work took its place as the leading text-book on the subject. Both in this country and in England it is recognized as the most satisfactorily written and clearly illustrated work on obstetrics in the language. The illustrations form one of the features of the book. They are numerous and the most of them are original. In this edit.on the book has been thoroughly revised. Recognizing the inseparable relation between obstetrics and certain gynecologic conditions, the author has included all the gynecologic operations for complica- tions and consequences of childbirth, together with a brief account of the diagnosis and treatment of all the pathologic phenomena peculiar to women. OPINIONS OF THE MEDICAL PRESS British Medical Journal ‘““The popularity of American text-books in this country is one of the features of recent years. The popularity is probably chiefly due to the great superiority of their illustrations over those of the English text-books. The illustrations in Dr. Hirst’s volume are far more numerous and far better executed, and therefore more instructive, than those commonly found in the works of writers on obstetrics in our own country.” Bulletin of Johns Hopkins Hospital “The work is an admirable one in every sense of the word, concisely but comprehensively written.” The Medical Record, New York ‘The illustrations are numerous and are works of art, many of them appearing for the first time. The author's style, though condensed, is singularly clear, so that it is never necessary to re-read a sentence in order to grasp the meaning. Asa true model of what a modern text- book on obstetrics should be, we feel justified in affirming that Dr. Hirst’s book is without a rival,” Hirst’s Diseases of Women A Text-Book of Diseases of Women. by Barron Cooker Ilinst, M. D., Professor of Obstetrics, University of Pennsylvania; Gynecolo- gist to the Howard, the Orthopedic, and the Philadelphia Hospitals. Octavo of 745 pages, with 7o1 original illustrations, many in colors. Cloth, $5.00 net; Half Morocco, $6.50 net. THE NEW (2d) EDITION WITH 701 ORIGINAL ILLUSTRATIONS The new edition of this work has just been issued after a careful revision. As diagnosis and treatment are of the greatest importance in considering diseases of women, particular attention has been devoted to these divisions. To this er also, the work has been magnificently illuminated with 701 illustrations, for the most part original photographs and water-colors of actual clinical cases a lated during the past fifteen years. The palliative treatment, as well as the radical operative, is fully described, enabling the general practitioner to treat many of his own patients +.tthout referring them to a specialist. An entire sec- tion is devoted to = full description of all modern gynecologic operations, illumi- nated and elucidated by numerous photographs. The author's extensive ex- perience renders this work of unusual value. OPINIONS OF THE MEDICAL PRESS Medical Record, New York ‘‘Tts merits can be appreciated only by a careful perusal. . . . Nearly one hundred pages are devoted to technic, this chapter being in some respects superior to the descnptions in many other text- boks.” Boston Medical and Surgical Journal “The author has given special attention to diagnosis and treatment throughout the book, and has produced a practical treatise which should be of the greatest value to the student the general practitioner, and the specialist.”’ Medical News, New York ‘‘ Office treatment is given a due amount of consideration, so that the work will be as useful to the non-operator as to the specialist.” 10 SAUNDERS’ BOOKS ON GET THE NEW THE BEST Am erican STANDARD Illustrated Dictionary New (7th) Edition—5000 Sold in Two Months The American Illustrated Medical Dictionary. A new and com- plete dictionary of the terms used in Medicine, Surgery, Dentistry, Pharmacy, Chemistry, Veterinary Science, Nursing, and kindred branches; with over 100 new and elaborate tables and many handsome illustrations. By W. A. Newman Dortanp, M.D., Editor of “ The American Pocket Medical Dictionary.” Large octavo, 1107 pages, bound in full flexible leather. Price, $4.50 net; with thumb index, $5.00 net. IT DEFINES ALL THE NEW WORDS—MANY NEW FEATURES The American Illustrated Medical Dictionary defines hundreds of the newest terms not defined in any other dictionary—bar none. ‘These new terms are live, active words, taken right from modern medical literature. It gives the capitalization and pronunciation of all words. It makes a feature of the derivation or etymology of the words. In some dictionaries the etymology occupies only a secondary place, in many cases no derivation being given at all. In the ‘‘American Illustrated’’ practically every word is given its derivation. Every word has a separate paragraph, thus making it easy to find a word quickly. The tables of arteries, muscles, nerves, veins, etc., are of the greatest help in assembling anatomic facts. In them are classified for quick study all the necessary information about the various structures. Every word is given its definition—a definition that defines in the fewest pos- sible words. In some dictionaries hundreds of words are not defined at all, refer- ring the reader to some other source for the information he wants at once. Howard A. Kelly, M. D., joins Hopkins University, Baltimore “The American Illustrated Dictionary is admirable. It is so well gotten up and of such convenient size. No errors have been found in my use of it.”’ J. Collins Warren, M. D., LL.D., F.R.C.S. (Hon.), Harvard Medical School “JT regard it as a valuable aid to my medical literary work. It is very complete and of convenient size to handle comfortably. I use it in preference to any other.” GYNECOLOGY AND OBSTETRI( {! 4 Penrose’s Diseases of Women Sixth Revised Edition ) A Text-Book of Diseases of Women. By Cuarres B. Penrose M. D., Pu. D., formerly Professor of Gynecology in the University of til Pennsylvania; Surgeon to the Gynecean Hospital, Philadelphia. Oc- tavo volume of 550 pages, with 225 fine original illustrations. Clot $3.75 net. ILLUSTRATED Regularly every year a new edition of this excellent text-book is called for, and it appears to be in as great favor with physicians as with students. this book has taken its place as the ideal work for the general practitioner. The author presents the best teaching of modern gynecology, untrammeled by anti quated ideas and methods. In every case the most modern and progressive technique is adopted and made clear by excellent illustrations. Howard A. Kelly, M.D., Professor of Gynecologic Surgery, Johns Hopkins University, Baltimore. “I shall value very highly the copy of Penrose’s ‘ Diseases of Women’ received. I have already recommended it to my class as THE BEST book.” Davis’ Operative Obstetrics Operative Obstetrics. By Epwarp P. Davis, M.D., Professor of Obstetrics at Jefferson Medical College, Philadelphia. Octavo of 483 ? pages, with 264 illustrations. Cloth, $5.50 net; Halt Morocco, $7.00 net INCLUDING SURGERY OF NEWBORN Dr. Davis’ new work is a most practical one, and no expense has been spared to make it the handsomest work on the subject as well. Every stepin every operation is described minutely, and the technic shown by beautiful new illustra- tions. Dr. Davis’ name is sufficient guarantee for something above the mediocre. 12 SAUNDERS’ BOOKS ON Dorland’s Modern Obstetricy Modern Obstetrics: General and Operative. By W. A. Newman DorwanD, A. M., M.D., Professor of Obstetrics at Loyola University, Chicago, Illinois. Handsome octavo volume of 797 pages, with 201 illustrations. Cloth, $4.00 net. Second Edition, Revised and Greatly Enlarged In this edition the book has been entirely rewritten and very greatly enlarged. Among the new subjects introduced are the surgical treatment of puerperal sepsis, infant mortality, placental transmission of diseases, serum-therapy of puerperal sepsis, etc. By newillustrations the text has been elucidated, and the subject pre- sented in a most instructive and acceptable form, Journal of the American Medical Association “This work deserves commendation, and that it has received what it deserves at the hands of the profession is attested by the fact that a second edition is called for within such a short time. Especially deserving of praise is the chapter on puerperal sepsis.” Davis’ Obstetric and Gynecologic Nursing Obstetric and Gynecologic Nursing. By Epwarp P. Davis, A, M., M.D., Professor of Obstetrics in the Jefferson Medical College and - Philadelphia Polyclinic; Obstetrician and Gynecologist, Philadelphia Hospital. 12mo of 480 pages, illustrated. Buckram, $1.75 net. NEW (4th) EDITION Obstetric nursing demands some knowledge of natural pregnancy, and gyne- cologic nursing, really a branch of surgical nursing, requires special instruction and training. This volume presents this information in the most convenient form. This third edition has been very carefully revised throughout, bringing the subject down to date. The Lancet, London ‘“Not only nurses, but even newly qualified medical men, would learn a great deal by a perusal of this book. It is written in a clear and pleasant style, and is a work we can recom- mend.” GYNECOLOGY AND OBSTETRICS 13 Kelly ano Cullen’s Myomata of the Uterus Myomata of the Uterus. By Howarp A. Kecty, M. D., P: of Gynecologic Surgery at Johns Hopkins University; and Thomas 5. Cutten, M. B., Associate in Gynecology at Johns Hopkins University Large octavo of about 700 pages, with 388 original illustrat August Horn and Hermann Becker. Cloth, $7.50 net; Half Morocco, $9.00 net. ILLUSTRATED BY AUGUST HORN AND HERMANN BECKER This monumental work, the fruit of over ten years of remain for many years the last word upon the subject. Written by those men who have brought, step by step, the operative treatment of uteri such perfection that the mortality is now less than one per cent the record of greatest achievement of recent times. Surgery, Gynecology, and Obstetrics ‘«Tt must be considered as the most comprehensive work of the kind yet published. It will always be a mine of wealth to future students.’ Cullen’s Adenomyoma of the Uterus ADENOMYOMA OF THE UTERUS. By THOMAs S. CULLEN, M.B. Octavo of 275 pages, with original illustrations by Hermann Becker and August Horn. (¢ $5.00 net; Half Morocco, $6.50 net. *¢ A good example of how such a monograph should be writte It is an excell work, worthy of the high reputation of the author and of the school from which it emanates.’’— 7%e Lancet, London. Cullen’s Cancer of the Uterus CANCER OF THE UTERUS. By THomas S. CULLEN, M. B. Large octay f ¢ pages, with over 300 colored and half-tone text-cuts and eleven lithographs. Cl $7.50 net; Half Morocco, $8.50 net. wy) “ Dr. Cullen’s book is the standard work on the greatest problem which faces the surgical world to-day. Any one who desires to attack this pr m must have this book.’”>—Howarp A. KELLY, M. D., Joins Hopkins University. 14 SAUNDERS’ BOOKS ON Schaffer and Edgar’s Labor and Operative Obstetrics Atlas and Epitome of Labor and Operative Obstetrics. By Dr. O. SCHAFFER, of Heidelberg. Edited, with additions, by J. CLIFTON EDGAR, M. D., Professor of Obstetrics and Clinical Midwifery, Cornell University Medical School, New York. With 14 lithographic plates in colors, 139 text- cuts, and 111 pages of text. Cloth, $2.00 net. / Saunders’ Hand-Atlases. Schaffer and Edgar’s Obstetric Diagnosis and Treatment Atlas and Epitome of Obstetric Diagnosis and Treatment. By Dr. O. SCHAFFER, of Heidelberg. Edited, with additions, by J. CLirron EpGar, M. D., Professor of Obstetrics and Clinical Midwifery, Cornell University Medical School, New York. With 122 colored figures on 56 plates, 38 text- cuts, and 315 pages of text. Cloth, $3.00 net. Saunders’ Hand-Altlases. Schaffer and Norris’ Gynecology Atlas and Epitome of Gynecology. By Dr. O. SCHAFFER, of Heidel- berg. Edited, with additions, by RicHarp C. Norris, A. M., M. D., Gynecologist to Methodist Episcopal and Philadelphia Hospitals. With 207 colored figures on go plates, 65 text-cuts, and 308 pages of text. Cloth, $3.50 net. Jz Saunders’ Hand-Atlas Series, Galbraith’s Four Epochs of Woman’s Life New (2d) Edition The Four Epochs of Woman’s Life: A Stupy IN HYGIENE. By ANNA M. GALBRAITH, M. D., Fellow of the New York Academy of Medicine, etc. With an Introductory Note by JoHN H. Musser, M. D., University of Pennsylvania. 12mo of 247 pages. Cloth, $1.50 net. Birmingham Medical Review, England “We do not, as a rule, care for medical books written for the instruction of the public. But we must admit that the advice in Dr. Galbraith’s work is, in the main, wise and wholesome,” Garrigues’ Diseases of Women Third Edition A Text-Book of Diseases of Women. By HENry J. GARRIGUES, M. D., Gynecologist to St. Mark’s Hospital, New York City. Octavo of 756 pages, illustrated. Cloth, $4.50 net; Half Morocco, $6.00 net. GYNE ( OLOG ) AND O&8 LEI KA 1S Schaffer and Webster’s Operative Gynecology Atlas and Epitome of Operative Gynecology. By Dre. ©. s FER, of Heidelberg. Edited, with additi ns, DY LRENCI M.D. (Edin.), F.R.C.P.E., Professor of Obstetrics and Gyt Rush Medical College, in affiliation with the University of ( 42 colored lithographic plates, many text-cuts, a number in colo: 138 pages of text. /u Saunders’ Hand-Atlas Series. Cloth, $ Much patient endeavor has been expended by the author, the artist, and the lithographer in the preparation of the plates of th hundreds of photographs taken from nature, and illustrate most faithf the various surgical situations. Dr. Schaffer has made a specialty of demonstrating by illustrations. Medical Record, New York “The volume should prove most helpful to student to be acquired only in the amphitheater itself.” De Lee’s Obstetrics for Nurses Obstetrics for Nurses. By Josepn B. De Ler, M.D., Professor of Obstetrics in the Northwestern University Medical School; Lecturer in the Nurses’ Training Schools of Mercy, Wesley, Provident, Cool County, and Chicago Lying-in Hospitals. 12mo volume of 508 pages, fully illustrated. Cloth, § THE NEW (4th) EDITION While Dr. De Lee has written his work especially for nurses, yet the pra titioner will find it useful and instructive, since the duties of a nurse often devolve upon him in the early years of his practice. The illustrations are nearly all original, and represent photographs taken from actual scenes. The text is the result of the author’s many years’ experience in lecturing to the nurses of five different training schcols. J. Clifton Edgar, M. D., Professor of Obstetrics and Clinical Midwifery, Cornell University, New York “It is far and away the best that has come to my notice, and I shall take great pleasure in recommending it to my nurses, and students as well.” 1 SAUNDERS BOOKS ON GYNECOLOGY AND OBSTETRICS. American Pocket Dictionary New (8th) Edition THe AMERICAN Pocket MepicaLt Dictionary. Edited by W, A. Newman Dortanp, A.M., M.D. 677 pages. $1.00 net; with patent thumb index, $1.25 net. James W. Holland, M.D., Professor of Medical Chemistry and Toxicology at the Jefferson Medical College, Philadelphia. “Tam struck at once with admiration at the compact size and attractive exterior. J can recommend it to our students without reserve.” Cragin’s Gynecology. New (7th) Edition ESSENTIALS OF GYNECOLOGY. By Epwin B. Craain, M.D., Professor of Obstetrics, College of Physicians and Surgeons, New York. Crown octavo, 232 pages, 59 illustrations. Cloth, $1.00 net. /2 Saunders’ Question-Compend Series. The Medical Record, New York “A handy volume and a distinct improvement ot students’ compends in general. No author who was not himself a practical gynecologist could have consulted the student’s needs so thoroughly as Dr. Cragin has done.” Ashton’s Obstetrics. New (7th) Edition ESSENTIALS OF OBSTETRICS. By W. EasTERLy AsutTon, M.D., Professor of Gynecology in the Medico-Chirurgical College, Phila- delphia. Revised by Joun A. McGtinv, M. D., Assistant Professor of Obstetrics in the Medico-Chirurgical College .of Philadelphia. 12mo of 287 pages, 109 illustrations. Cloth, $1.00 net. Zi Saunders’ Question-Compend Series. Southern Practitioner “An excellent littke volume ccataining correct and practical knowledge. An admir- able compend, and the best condensation we have seen.” Barton and Wells’ Medical Thesaurus A TuHeEsAurRus OF MEpIcAL Worps AND PHRASES. By WILFRED M. Barton, M. D., Assistant to Professor of Materia Medica and Therapeutics, Georgetown University, Washington, D. C.; and Wa tter A. WELLS, M. D., Demonstrator of Laryngology, George- town University, Washington, D.C. 12mo of 534 pages. Flex- ible leather, $2.50 net; with thumb index, $3.00 net. Macfarlane’s Gynecology for Nurses Second Edition A REFERENCE Hanb-Book OF GYNECOLOGY FOR Nurses. By CATH- ARINE MACFARLANE, M. D., Gynecologist to the Woman’s Hospital of Philadelphia. 32mo of 150 pages, with 70 illustrations. Flexible leather, $1.25 net. A. M. Seabrook, M. D., Woman's Medical College of Philadelphia. “Tt is a most admirable little book, covering in a concise but attractive way the subject from the nurse’s standpoint.” ra paebae ear RARE te Saat - oe. te, Ry, . ® : Fears: Re ated Cre cand Rey Leyige Hite > sneee aa eae i é Saat = =: . Pheisse forte fee : Ril