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ANATOMY AND PHYSIOLOGY

FOR NURSES

•The/^y/>^o.

TEXT-BOOK

Anatomy and Physiology

FOR NURSES

COMPILED BY

DIANA CLIFFORD KIMBER

Qeajjuate op Bellevue Training School ; Assistant Sctpeuintkndent New York City
Training School, Blackwell's Island, N. Y. ; formerly Assistant

SUPEEINTENDENT ILLINOIS TBAINmG SCHOOL, CHICAGO, IlL.

NeSu Hark
THE MACMILLAN COMPANY

LONDON: MACMILLAN & CO., Ltd.
1908
All rights reserved

COPTKIGHT, 1893,

By MACMILLAN AND CO.

Copyright, 1902,
By the MACMILLAN COMPANY.

Set up and electrotyped September, 1894. Reprinted November, 1894;
February, August, 1895; January, November, 1896; July, December,
1897; September, 1898; July, 1899; February, October, 1900; March,
1901.

New edition, revised, printed February, October, 1902; Febniarv, Oct.
ober, 1903 • June, 1904; January, October, 1905 ; Januarj', 1906 ; January,
October, 1907 ; January, July, 1908.

^ffecttonatdg ©etitcateli

TO MY
FRIEND, SCHOOLMATE, AXD SUPERINTENDENT

%oum ©arcfje

GRADUATE OF BELLEVUE TRAINING SCHOOL

AND

SUPERINTENDENT NEW YORK CITY TRAINING SCHOOL

BLACKWELL's ISLAND, N.Y.

The following illustrations have been copied from Quain's
"Anatomy" and Schiifer's "Essentials of Histology," and
are used in this work by permission of the authors and pub-
lishers of those books, viz. : Figs. 4, 5, 8, 10, 12, 14, 51, 53, 64,
69, 83, 86, 103, 110, 117, 121, 127, 128.

PREFACE TO SECOND EDITION.

It is now seven years since the first edition of tliis " Text-
book on Anatomy and Physiology for Nurses" was issued, and
in order to bring the book up to date it has become necessary
to revise it.

That this revision has been accomplished with, I trust, success,
is almost entirely owing to the kind assistance given me by
Mr. T. Pickering Pick, and by Percy M. Dawson, M.D.,
Assistant Professor of Physiology in the Johns Hopkins Uni-
versity, Baltimore. To the latter I am indebted for the whole
recasting, and in large measure rewriting, of the chapter on the
Nervous System, and also, to a slighter extent, of Chapters I.
and XIX. Indeed, so greatly is this revision the work of
Dr. Dawson that I should have been glad, had I been allowed,
to place his name with mine on the title-page.

The chapter on the Nervous System has been transferred
to its usual position in such text-books, namely, following the
chapter on Muscles, but it is, of course, possible for those who
prefer the old arrangement to take this chapter later in the
course of study.

A number of new drawings have been made specially for
this edition, including ten original ones by Dr. Dawson; also,
to all the weights and measures, according to the English
System, have been added their equivalents in the Metric
System. It should be noted that the calculations are based
upon the standard of weights and measures adopted by the
United States, and not upon those of the British Pharmacopeia.

November 12, 1901.

D. C. K.

CONTENTS.

ARRANGED IN CHAPTERS AND LESSONS.

CHAPTER I.
(Lesson l.)

^ PAGB

Introductory — General Outline of the Body ; Structural Elements of the

Body ; the Cell 1

CHAPTER II.

(Lesson 2.)
Organs, Tissues, Cells ; Epithelial Tissues ; Stratified ; Transitional ;

Simple 7

CHAPTER IIL
(Lessons 3 and 4.)
Connective Tissues : Connective Tissue Proper ; Adipose Tissue or Fat ;

Cartilage ; Bone 13

CHAPTER IV.

(Lessons 5, 6, and 7.)

The Skeleton 23

CHAPTER V.

(Lesson 8.)

The Joints 48

CHAPTER VL
(Lessons 9, 10, and 11.)
Muscular Tissue : Striated or Striped ; Non-striated or Plain ; Attach-
ment of Muscles to Skeleton ; Prominent Muscles of the Head and
Trunk ; Prominent Muscles of the Limbs 53

CHAPTER VII.
(Lessons 12, 13, and 14.)
Nervous Tissue : the Neurone or Nerve-Cell ; Anatomy of the Nervous Sys-
tem ; Physiology of the Nervous System ; Reflexes .... 74

Note. — In most training schools in America instruction in class is given from
October 1 to June 1, or for thirty-eight consecutive weeks; the lessons in this text-
book can be conveniently mastered in the first year's course, taken in the manner
indicated in these introductory contents.

ix

X CONTENTS.

CHAPTER VIII.

(Lesson 15.)

PAGE

The Vascular System : the Blood ........ 95

CHAPTER IX.

(Lesson 16.)

The Vascular System continued : Heart ; Arteries ; Veins ; Capillaries . 103

CHAPTER X.

(Lessons 17 and 18)

The Vascular System continued : Arterial Distribution ; Venous Return . 115

CHAPTER XI.

(Lesson 19.)
The Vascular System continued : the General Circulation ; the Pulse and

Arterial Pressure ; Variations in the Capillary Circulation . . . 131

CHAPTER XII.

(Lessons 20 and 21.)
The Vascular System concluded : Lymphatic Vessels and Lymph ;

Lymphatic Glands and Bodies of Allied Structure .... 141

CHAPTER XIII.

(Lessons 22 and 23.)
The Respiratory Apparatus : Larynx ; Trachea ; Lungs ; Respiration ;
Effects of Respiration upon the Air within the Lungs ; upon the Air
outside the Body ; upon the Blood ; Modified Respiratory Movements 151

CHAPTER XIV.

(Lessons 24 and 25.)
Alimentation : Section 1. Preliminary Remarks on Secreting Glands and
Mucous Membranes. Section 2. Food ; Food Principles ; Proteids,
Fats, Carbo-hydrates, Water, Saline and Mineral Matters ; Chemical
Composition of the Body ; Average Composition of Milk, Bread, and
Meat ; Concluding Remarks 164

CHAPTER XV.

(Lessons 26 and 27.)
Alimentation continued : the Digestive Apparatus ; Alimentary Canal ;

Accessory Organs 175

CHAPTER XVL

(Lessons 28 and 29.)
Alimentation concluded : Digestion ; Changes the Food undergoes in the
Mouth, Stomach, Small and Large Intestines ; Summary of Digestion ;
Absorption 191

CONTENTS. xi

CHAPTER XVII.

(Lessons 30 and 31.)
Elimination : General Description of the Urinary Organs ; Structure and

PAGE

Blood-Supply of Kidneys ; Secretion of Urine ; Composition and Gen-
eral Characters of Urine 201

CHAPTER XVIII.

(Lessons 32 and 33.)

Elimination concluded : the Skin ; Nails and Hair ; Bodily Heat ; Produc-
tion of Heat ; Loss of Heat ; Distribution of Heat ; Regulation of
Heat 212

CHAPTER XIX.

(Lessons 34, 35, and 36.)

The Special Senses : Pressure, Temperature, Pain, Muscle-Sense, Taste,

Hearing, Equilibrium, Vision 222

CHAPTER XX.

(Lesson 37.)
The Female Generative Organs . 243

Glossary 253

Index 273

LIST OF ILLUSTRATIONS.

FIG. PAGE

1. Diagrammatic Longitudinal Section of the Trunk and Head . . 2

2. Diagram of a Cell 3

3. Consecutive Stages of Cell-Division, with Indirect Division of the

Nucleus 5

4. Section of Stratified Epithelium 9

5. Section of the Transitional Epithelium lining the Bladder ... 10

6. Simple Pavement Epithelium 10

7. Simple Columnar Epithelium 11

8. Glandular Epithelium, with the Cells set round a Simple Saccular

Gland 11

9. Ciliated Epithelium from the Human Trachea 11

10. Subcutaneous Areolar Tissue from a Young Rabbit .... 14

11. Fibrous Tissue from the Longitudinal Section of a Tendon ... 15

12. A Few Fat Cells from the Margin of a Fat Lobule . . . .17

13. Articular Hyaline Cartilage from the Femur of an Ox . . . . 19

14. Transverse Section of Compact Tissue (of Humerus) . . . .21

15. The Skeleton 24

16. The Clavicle 26

17. The Scapula 26

18. The Humerus 27

19. The Ulna and Radius 28

20. Bones of the Wrist and Hand ........ 29

21. Os Innominatum ........... 30

22. The Femur 31

23. The Tibia and Fibula 32

24. Bones of the Ankle and Foot 33

25. Occipital Bone 34

26. Parietal Bone 34

27. Frontal Bone 35

28. Temporal Bone ........... 35

29. Sphenoid Bone 36

30. Ethmoid Bone 36

31. Nasal Bone 37

32. Lachi-ymal Bone . 37

33. Vomer 37

34. Malar Bone 38

35. Palate Bone 38

36. Inferior Turbinated Bone 38

37. Superior Maxillary Bone . 38

38. Inferior Maxillary Bone 39

xiii

xiv LIST OF ILLUSTRATIONS.

FIG. PAOE

39. Hyoid Bone 39

40. A Cervical Vertebra 40

41. Side View of Spinal Column, without Sacrum and Coccyx ... 41

42. Thorax 42

43. Sternum 43

44. The Skull 44

45. The Skull at Birth 45

46. Male Pelvis 46

47. Female Pelvis 46

48. A Toothed or Dentated Suture 48

49. A Mixed Articulation 48

50. A Simple Complete Joint 49

51. Muscular Fibre 53

52. Fragments of Striped Fibres showing a Cleavage in Opposite Directions 54

53. Wave of Contraction passing over a Muscular Fibre of Dytiscus . . 55

54. Fibre-Cells of Plain Muscular Tissue 56

55. Muscles of Right Eyeball within the Orbit 60

56. Muscles of Eyeball 60

57. Muscles of the Tongue 61

58. Muscles of the Arm 67

59. Muscles in Front of Forearm 68

60. Muscles of the Thigh 70

61. Muscles of the Leg. Superficial View of the Calf .... 70

62. Nerve ending in Muscular Fibre of a Lizard 71

63. Diagram of a Neurone 74

64. Diagram illustrating the Arrangement of the Cerebro-Spinal System . 76

65. Nerve-Fibres . . * 77

66. Section of the Internal Saphenous Nerve 78

67. General View of the Sympathetic System 79

68. Diagram showing the Relation of the Cerebro-Spinal to the Sympa-

thetic Neurones ........... 80

69. Base of Brain, Spinal Cord, and Spinal Nerves 81

70. Transverse Sections of the Spinal Cord at Different Levels ... 82

71. Diagram showing Anatomy of the Spinal Nerve Roots and Adjacent

Parts 83

72. Diagram showing Relation of Neurones composing the Spinal Nerve-

Roots with Adjacent Nervous Structures 84

73. The Base of the Brain 86

74. Reflex Arc 91

75. Reflex Arc as it is approximately in Man 91

76. Diagram of Nervous System 93

77. Red and White Corpuscles of the Blood 97

78. The Heart and Lungs 104

79. Anterior View of Heart, dissected after Long Boiling, to show the

Superficial Muscular Fibres 105

80. Diagram of Heart and Pericardium 106

81. Right Side of Heart 106

82. Left Side of Heart 107

83. Diagram to illustrate the Action of the Heart 108

LIST OF ILLUSTRATIONS. xv

FIG. PAGE

84. Section of Heart at Level of Valves 109

85. Structure of an Artery Ill

86. Part of a Vein laid Open 112

87. Portion of Endothelium of Peritoneum 114

88 and 89. The Aorta 117

90. The Carotid, Subclavian, and Axillary Arteries 118

91. Deep Anterior View of the Arteries of the Arm, Porearm, and Hand 119

92. Iliac and Femoral Arteries 122

93. View of Popliteal Artery 123

94. Deep View of the Arteries of the Back of the Leg .... 124

95. Anterior View of Arteries of the Leg 124

96. Arteries of the Foot 125

97. Sketch of the Principal Venous Trunks 126

98. Superficial Veins of Lower Extremity 127

99. Diagram of Circulation 132

100. Isolated Capillary Network formed by the Junction of Several Hol-

lowed-out Cells, and containing Coloured Blood Corpuscles in a

Clear Fluid 140

101. A Small Portion of a Lymphatic Plexus 142

102. Lymphatics and Lymphatic Glands of Axilla and Arm . . . 146

103. Diagrammatic Section of Lymphatic Gland 147

104. Vertical Section of a Portion of a Peyer's Patch, with Lacteal Vessels

Injected 148

105. The Mouth, Nose, and Pharynx, with the Commencement of Gullet

and Larynx 152

106. The Larynx as seen by Means of the Laryngoscope . . . .153

107. Front View of Cartilages of Larynx 154

108. Two Alveoli of the Lung 155

109. Anterior View of Lungs and Heart 156

110. Diagram showing the Various Forms of Secreting Glands . . . 165

111. An Intestinal Villus 169

112. The Salivary Glands 177

113. The Mouth, Nose, and Pharynx, with the Larynx and Commence-

ment of Gullet, seen in Section . . . . . . .179

114. Vertical and Longitudinal Section of Stomach and Duodenum . . 181

115. An Intestinal Villus 182

116. Section through the Lymphoid Tissue of a Solitary Gland . . . 183

117. Csecum, showing its Appendix, Entrance of Ilium, and Ileo-csecal

Valve 184

118. Posterior View of Pancreas 186

119. Under Surface of Liver 187

120. Diagrammatic Representation of Two Hepatic Lobules . . .188

121. Section of Eabbit's Liver, Vessels and Bile Ducts injected . . . 189

122. The Renal Organs viewed from Behind 203

123. Section through the Kidney 205

124. Vascular Supply of Kidney 206

125. Plan of Blood- Vessels connected with the Tubules .... 207

126. Diagram of the Course of Two Uriniferous Tubules .... 208

127. Section of Epidermis 212

xvi LIST OF ILLUSTRATIONS.

via. PAGE

128. Section of Skin showing Two Papillse and Deeper Layers of Epidermis 214

129. Piece of Human Hair 215

130. Section of Skin showing the Hairs and Sebaceous Glands . . . 216

131. Coiled End of a Sweat-Gland 217

132. The Upper Surface of the Tongue 225

133. Vertical Longitudinal Section of Nasal Cavity 227

134. Semi-diagrammatic Section through the Right Ear .... 229

135. Diagram showing Relative Position of the Planes in which the Semi-

circular Canals lie 232

136. The Left Eyeball in Horizontal Section from Before Back . . 234

137. Diagram showing Relations of the Neurones and Sensory Epithelium

in the Retina 236

138. Diagram illustrating Rays of Light converging in (A) a Normal Eye,

(B) a Myopic Eye, and (C) Hypermetropic Eye .... 239

139. The Lachrymal Apparatus 241

140. Section of Female Pelvis showing Relative Portion of Viscera . . 244

141. The Uterus and its Appendages 246

142. Section of an Ovary 248

PLATES.

PLATE PAGE

I, Forms of Muscles and Tendons 57

II. Muscles of Face, Head, and Neck 59

IIL Muscles of Back 63

IV. Muscles of Chest and Abdomen 65

V. The Abdominal Aorta and its Contents 121

VI. Plan of Foetal Circulation 139

VII. Regions of the Abdomen and their Contents 176

ANATOMY AND PHYSIOLOGY
FOR NURSES

TEXT-BOOK

OF

ANATOMY AND PHYSIOLOGY FOE NUESES.

CHAPTER T.

INTRODUCTORY. — GENERAL OUTLINE OF THE BODY. — STRUCTU-
RAL ELEMENTS OF THE BODY. — THE CELL.

Introductory. — In looking upon the fully developed human
body we are impressed with the complexity of its structure, the
perfection of its mechanism, the mysteriousness of its life. To
learn to understand something of this structure, this mechan-
ism, this life, is one of our most imperative duties as nurses; for
how can we appreciate the significance of abnormal functions,
and the seriousness of diseased conditions, unless we are ac-
quainted with the normal functions of the body, and have some
knowledge of healthy bodily conditions ?

In the following pages we propose to give a description of
the structure, of the position, and of the special work or func-
tion of each part of the body. We have dwelt specially upon
the structure of the different parts, believing that any correct
understanding of the bodily functions must be preceded by a
certain amount of knowledge concerning the structure of the
organs performing these functions.

Before taking up the subject in detail it is well, first of all,
to get a general idea of the main divisions, and the position of
the different parts, and we shall therefore begin our considera-
tion of the body with an outline of its structure.

Generg,l outline of the body. — It is readily seen that the human
body is separable into trunk, head, and limbs ; the trunk and
head are cavities, and contain the internal organs or viscera,

B 1

ANATOMY FOR NURSES.

[Chap. I.

while the limbs are solid, contain no viscera, and are merely
appendages of the trunk. The limbs or extremities, upper
and lower, are in pairs, and bear a rough resemblance to
one another, the shape of the bones, and the disposition of
the muscles in the thigh and arm, leg and forearm, ankle and
wrist, foot and hand, being very similar.

The trunk and head contain two main cavities, and looking
at the body from the outside we should naturally imagine that
these two cavities were the cavity of the
head and the cavit}^ of the trunk, respec-
tively. If, however, we divide the trunk
and head lengthwise into two halves, by
cutting them through the middle line
from before backwards, we find the trunk
and head are divided by the bones of the
spine into back and front cavities, and
not into upper and lower {vide diagram).
The dorsal or back cavity is a com-
plete bony cavity, and is formed by the
vertebrae (bones of the spine) and by the
bones of the skull. It may be subdi-
vided into the spinal canal, containing
the spinal cord, and into the cranial cav-
ity, which is merely an enlargement of
the spinal canal, and contains the brain.
The ventral or front cavity is not a
Fig. 1.- Diagrammatic complete bony cavity, part of its walls
Longitudinal Section of being formed of muscular and other tis-

THE Trunk AND Head. 1,1, ^ .

the dorsal cavity; a, the suc ; it IS much larger than the dorsal
spinal portion ; 6, the era- cavity, and may be subdivided into the

nial enlargement; c, c, the '' *^

bodies of the vertebrae form- thoracic, abdominal, and pelvic cavities.

ing the partition between rr^i .-i • •■ i , i • j.i

the dorsal and ventral cavi- ^^^^ thoracic cavity, or chest, contains the
ties ; 2, 2, the ventral cavity, trachea or windpipe, the lungs, gullet,

subdivided into thoracic cav- , , i ,i , ^ ■ •

ity (rf), abdominal cavity heart, and the great vessels springing
(e), and pelvic cavity (/) ; from ^nd entering into, the heart. The

g, the nasal cavity ; h, the .

mouth, or buccal cavity, abdominal cavity contains the stomach,
The alimentary canal (ao is j^ gall-bladder, pancreas, spleen, kid-

represented running through " •■■ _ •■■

the whole length of the ven- neys, small and large intestines, etc. The
ra cavi y. pelvic cavity contains the bladder, rec-

tum, and in the female, the generative organs. Connected with

— n

Chap. I.] THE CELL. 3

the upper part of the ventral cavity are two small cavities, the
buccal cavity, or mouth, containing the tongue, teeth, salivary
glands, etc., and the nasal cavity, containing the organ of smell.

Structural elements of the body. — When any part of the body
is separated by the aid of the microscope into its simplest parts,
such parts are called its structural elements. The structural
element of every part of the body is the cell. All the varied
activities of the body are the result of the activity of the cells
which compose it, and it is very desirable, owing also to their
being the foundation of all structure (the bricks, as it were,
out of which the tissues are built), that we early acquire some
definite conception of these tiny elementary bodies.

The cell. — A cell is a minute portion of living substance
(protoplasm) which is sometimes enclosed in a membrane (cell
membrane). It consists of a semi-fluid,
often granular, part (cytoplasm) sur-
rounding a more solid part (the nu-
cleus). The nucleus differs somewhat
from the cytoplasm in function and in
chemical composition. Yryf A { Y F F^ c

The study of physics shows us that

all matter, of whatever kind it may be, -n. ^ t^

' J ■> Fig. 2. — Diagram of a

is made up of little particles, or mole- Cell, n, nucleus; c, cyto-
cules, so small that they are perfectly ^ ^^™'
invisible to the human eye, even when aided by the most power-
ful microscope ; and it is only when a great number of these
molecules are collected together that they become perceptible.
Again, a study of the chemical properties of matter teaches us
that these molecules are in turn composed of still smaller parti-
cles called atoms. There are only about seventy different kinds
of atoms, whereas the different sorts of molecules which are
formed by combination of atoms are innumerable. The prop-
erty of atoms of uniting together to form molecules is known
as their chemical affinity, while that which binds the molecules
together is called cohesion.^ The strength of chemical affinity

1 As examples of atoms and molecules we may mention the following :
hydrogen (H) and oxygen (0) unite by chemical affinity to form the hydro-
gen monoxide (H2O), or water molecule. Such molecules, when gathered
together in great numbers and united by their property of cohesion, form
the water which we can perceive by our senses. So also sodium (Na) and
chlorine (CI) unite to form sodium chloride (NaCl), or common table salt.

4 ANATOMY FOE NURSES. [Chap. I.

varies greatly, and hence in some substances the molecules can
only with great difficulty be broken up into their component
atoms. Such substances are said to be "stable." On the
other hand, many substances are very easily decomposed, and
are known as " unstable " substances. Between these two
extremes there are substances possessing every degree of
stability.

In protoplasm, or proteid (proteid being the name usually
employed by chemists), the molecule is composed of carbon,
hydrogen, nitrogen, oxygen, and sulphur, and is a highly com-
plex structure. It is also extremely unstable, and is very
sensitive to outside influences. The many vital phenomena
exhibited by protoplasm are due, in great part, to the chemi-
cal reactions of the atoms composing its molecules, and which
are rendered possible by the great instability of these mole-
cules.

During the life of a cell its protoplasm is constantly under-
going changes, the chief of which may be enumerated as
follows : —

(1) All protoplasm coming in contact with oxygen absorbs
it and combines with it. Whenever this combination takes
place, a certain amount of the protoplasm is burned or oxi-
dized, and as a result of this oxidation heat and other kinds of
energy are produced, and carbon dioxide evolved.

(2) All protoplasm is able to take to itself, and eventually
convert into its own substance, certain materials (foods) that
are non-living; in this way the protoplasm may increase in
amount, or in other words the cell may grow. But if the
amount of protoplasm does not permanently increase, this is
due to the fact that just as much protoplasm is being broken
down by the process of oxidation, and removed from the cell,
as is added by the process of assimilation. Chemical changes
which involve the building up of living material within the
cell have received the general name of anabolic changes, or
anabolism ; those, on the other hand, which involve the break-
ing down of such material into other and simpler products,
are known as katabolic changes, or katabolism ; while the sum
of all the ana- and katabolic changes which are proceeding
within the cell are spoken of as the metabolism of a cell.
These chemical clianges are always more marked as the activ-

Chap. I.]

THE CELL.

ity of the cell is promoted by warmth, electrical or other
stimulation, the action of certain drugs, etc.

(3) The most obvious physical changes that can sometimes
be seen in living protoplasm, by the aid of the microscope,
are those which are termed "amoeboid." This term is derived
from the amoeba, a single-
celled organism which has
long been observed to exhibit
spontaneous changes of form,
accompanied by a flowing of
its soft semi-fluid substance.
By virtue of this property,
the cells can move from one
place to another. If one of
these cells be observed under
a high power of the micro-
scope, it will be seen gradu-
ally to protrude a portion of
its protoplasm ; this protru-
sion extends itself, and the
main part or body of the cell
passes by degrees into the
elougated protrusion. By a
repetition of this process, the
cell may glide slowly away
from its original situation and
move bodily along the field
of the microscope, so that an
actual locomotion takes place.
When the surface of these
free cells comes in contact Fig. 3. — .4 to i7, Consecutive Stages
with any foreign particles, the «*' Cell-Division, with indirect Divi-

•^ . . SIGN OF THE NUCLEUS. (Diagrammatic.)

protoplasm, by virtue of its

amoeboid movements, tends to flow round and enwrap the
particles, and particles thus enwrapped or incepted may then
be conveyed by the cell from one place to another.

The nucleus. — The nucleus of a cell is directly concerned in
the nutrition and in the reproduction or division of the cells.
In dividing, the nucleus passes through a series of remarkable
changes, which are too complicated to be studied here. (See

6 ANATOMY FOR NURSES. [Chap. I.

Fig. 3.) The result of these changes is that either directly
or indirectly the nucleus splits into two, and the protoplasm
divides and arranges itself around the new nuclei ; these
daughter cells soon grow to the size of the parent cell, and
division of these and consequent multiplication may proceed
with great rapidity.

To sum up : The cell assimilates, is continually building
itself up and replenishing its store of energy, is as continually
breaking down into simpler products with a setting free of
energy; it grows; it moves; it reproduces itself — in other
words, it is alive and is the basis of all life.

CHAPTER II.

ORGANS, TISSUES, AND CELLS. — EPITHELIAL TISSUES: STRATI-
FIED, TRANSITIONAL, SIMPLE.

Organs, tissues, and cells. — In speaking of the different parts
of the body, we usually call each part an organ, and we may say
that the human body is made up of organs, each organ being
adapted to the performance of some special work or function.
Thus the lungs are organs specially adapted for performing
the function of respiration, the bones are organs adapted for
support and locomotion, the kidneys for secreting urine, etc.

Every part or organ, when examined microscopically, is found
to consist of certain textures or tissues. When the body is
thus analyzed by the aid of the microscope, we find that the
number of distinct tissues is comparatively small, and some of
these again, although at first sight apparently distinct, yet have
so much in common in their structure and origin one with
another, that the number becomes still further reduced, until
we can only distinguish four distinct tissues, viz. : —

The epithelial tissues. The muscular tissues.

The connective tissues. The nervous tissues.

Particles met with in the fluids of the body, such as the little bodies or cor-
puscles in the blood and lymph, are also reckoned among these elementary
tissues.

Some organs are formed of a combination of several of the
above tissues ; others contain only one or two. Thus the
muscles are made up almost entirely of muscular tissue with
only a small intermixture of connective tissue, blood-vessels,
and nerves ; whilst the ligaments or sinews are composed
wholly of a variety of connective tissue.

On the other hand, there are certain organs or parts of the

7

8 ANATOMY FOR NURSES. [Chap. II.

body not in themselves distinguished by the preponderance of
any tissue. Such are : —

Blood-vessels. Synovial membranes.

Lymphatic vessels. Mucous membranes.

Lymphatic glands and bodies Secreting glands.

of like structure. Integument or skin.
Serous membranes.

Thus, though we may say the greater bulk of the body is made
up of a combination of four distinct tissues, — the epithelial,
connective, muscular, and nervous, — there are parts in which
these tissues are so intimately mixed that we cannot distinguish
any distinct variety, and we are therefore obliged to class them
by themselves.

As the structure of an organ depends upon the properties of
the tissues composing it, so the characteristics of each tissue
depend upon their ultimate structural units — the cells and the
products of the cells. ^

The early embryo is an agglomeration of cells, and the whole
of the body is developed out of one cell, called the ovum,
which measures 2^0 ^^ 120 ^^ ^^ ^'^^^ (0.106 to 0.211 mm.)
in diameter. In the beginning of the formation of the body,
the protoplasm of the ovum divides and subdivides, and the
daughter cells thus formed eventually arrange themselves in
three la3'ers. These layers are known respectively as the epi-
blast, or upper layer ; the mesoblast, or middle layer ; the hypo-
blast^ or under layer. The epiblast is supposed to give rise to the
nervous tissue and most of the epithelial tissue ; the mesoblast
to the connective and muscular tissues, and also to a portion of the
epithelial tissue; the hypoblast to the rest of the epithelial tissue.
Of these tissues, the epithelial is the simplest and most nearly
allied to the primitive tissue, and will first engage our attention.

Epithelial tissue. — Epithelial tissue is composed entirely of
cells united together by adhesive matter. The cells are gener-
ally so arranged as to form a skin or membrane, covering the
external surfaces, and lining the internal parts of the body.
This membrane is seen when the skin is blistered, the thin and
nearly transparent membrane raised from the surface being

^ By the products of the cells is meant, for example, the fibres of connective
tissue, or the intercellular substance of cai-tilage and bone.

Chap. II.] EPITHELIAL TISSUE. 9

epithelial tissue — in this situation called epidermis, because it
lies upon the surface of the true skin. In other situations,
epithelial tissue usually receives the general name of epithelium.

Classification. — We may classify the varieties of epithelium
according to the shape of the cells which compose them, or
according to the arrangement of these cells in layers. Adopt-
ing the latter and simpler classification, we distinguish three
main varieties : the stratified, consisting of many layers ; the
transitional, consisting of two or three layers ; the simple, con-
sisting of a single layer of cells.

1. Stratified epithelium. — The cells composing the different
layers of stratified epithelium differ in shape. As a rule, the

Fig. 4. — Section of Stratified Epithelium, c, lowermost columnar cells; P,
polygonal cells above these; fl. flattened cells near the surface. Between the cells
are seen intercellular channels, bridged over by processes which j^ass from cell to cell.

cells of the deepest layer are columnar in shape ; the next,
rounded or many-sided, whilst those nearest the surface are
always flattened and scale-like, the protoplasm of the cell being
finally converted into a horn-like substance. The deeper soft
cells of a stratified epithelium are continually multiplying by
cell-division, and as the new cells which are thus produced
in the deeper parts increase in size, they compress and push
outwards those previously formed. In this way cells which
were at first deeply seated are gradually shifted outwards and
upwards, growing harder as they approach the surface. The
older superficial cells are being continually rubbed off as the
new ones continually rise up to supply their places.

Stratified epithelium covers the anterior surface of the eye,
lines the mouth, the chief part of the pharynx, the gullet, the
vagina, and the neck of the uterus, but its most extensive distri-
bution is over the surface of the skin, where it forms the epider-
mis. Whenever a surface is exposed to friction we find stratified

10

ANATOMY FOR NURSES.

[Chap. IL

scaly epithelium, and we may therefore classify it as a protec-
tive epithelium.

2. Transitional epithelium. — This is a modification of strati-
fied epithelium, consisting only of two or three layers of cells.

FlCi. ."). SiA T!l.'.N L!i' THE TnANSITIOXAL EPITHELIUM LINING THE BLADDER.

(Highly magnified.) (E. A. S.) «, superficial; 6, iutermediate; c, deep layer of cells.

The superficial cells are large and flattened, having on their
under surface depressions into which fit the larger ends of the
pear-shaped cells which form the next layer. Between the
tapering ends of these pear-shaped cells are one or two layers
of smaller, many-sided cells, the epithelium being renewed by
division of these deeper cells. This kind of transitional epithe-
lium lines the bladder and ureters.

3. Simple epithelium. — This is composed of a single layer of
cells. The cells forming single layers are of distinctive shape,
and have distinctive functions in different parts of the body.
3 The chief varieties are the pavement, col-
umnar, glandular, and ciliated.

In simple pavement epithelium the cells
form flat, many-sided plates or scales, which
fit together like the tiles of a mosaic pave-
ment. It forms very smooth surfaces, and
' lines the alveoli of the lungs, the heart,
from a serous membrane; blood-vcssels, and lymphatics; the mam-

6, from a blood-vessel. i , ,i •.• .

mary ducts, the serous cavities, etc.
The columnar epithelium is a variety of simple epithelium in
which the cells have a prismatic shape, and are set upright on
the surface which they cover. In profile these cells look some-
what like a close palisade, their edges, however, being often
irregular and jagged, especially where free or " wander-cells "

Fig. <i. — SiMPLK Pave
MENT Epithelium. a

Chap. II.]

EPITHELIAL TISSUE.

11

Fig. 7. — Simple Col-
umnar Epithelium, a.

squeeze in between them. Columnar epithelium is found in its
most characteristic form lining the mucous
membrane of the intestinal canal.

Glandular epithelium is found in the re-
cesses of secreting glands. The cells are of
many different shapes, and are usually set
round a tubular or saccular cavity, into the cells; 6, intercellular

1 • 1 .-i , • • 1 rpi , substance between the

which the secretion is poured. The proto- i^^^er end of cells,
plasm 01 these cells is generally filled by

the materials which the gland

secretes.

In ciliated epithelium the cells,
which are generally columnar in
shape, bear at their free extrem-
ities little hair-like processes
which are agitated incessantly
with a lashing or vibrating mo-
tion. These minute and delicate
processes are named cilia^ and
may be regarded as active prolon-
gations of the cell-protoplasm.

Fig. 8. — Glandular Epithelium, ^J^g manner in which cilia move
WITH THE Cells set round a Simple .

Saccular Gland. (Highly magnified.) IS best seen when they are not
(Fiemmiug.) acting very quickly. The mo-

tion of an individual cilium may be compared to the lash-like
motion of a short-handled
whip, the cilium being rap-
idly bent in one direction.
The motion does not involve
the whole of the ciliated sur-
face at the same moment,
but is performed by the cilia
in regular succession, giv-
ing rise to the appearance of
a series of waves travelling

along the surface like the pio. 9. — ciliated Epithelium from the
waves caused by the Avind Human Trachea. (Highly magnified.) a,
n ^J c 1- i. 1X7-1, large ciliated cell ; d, cell, with two nuclei.

m a field of wheat. When ^

they are in very rapid action, their motion conveys the idea of

swiftly running water.

12 • ANATOMY FOR NURSES. [Chap. II

Cilia have been shown to exist in almost every class of ani-
mal, from the highest to the lowest. In man their use is to
impel secreted fluids, or other matters, along the surfaces to
which they are attached ; as, for example, the mucus of the
trachea and nasal chambers, which they carry towards the out-
let of these passages.

Ciliated epithelium is found in the air passages, in parts of
the generative organs, ventricles of the brain, and central canal
of the spinal cord.

To recapitulate : The most important situations in which a
covering or lining of epithelial tissue is found in the body
are : —

1. On the surface of the integument, or external skin.

2. On mucous membranes, or internal skin ; and in the
recesses of secreting glands.

3. On the inner surface of serous membranes, and on the
inner surface of the heart, blood-vessels, and lymphatics.

4. Lining the ventricles or cavities of the brain, and the
central canal of the spinal cord.

5. Epithelial cells, variously modified, are also found in the
sensory terminations of the organs of special sense.

Some varieties of epithelium are specially modified to form
protective membranes ; others to elaborate or make secretions ;
others, again, to form smooth linings for opposing surfaces ;
others to keep surfaces moist ; and yet others to keep the
surfaces they cover clean by sweeping outwards material that
would otherwise accumulate and clog important passages.

The hairs, nails, and the enamel of the teeth are modifica-
tions of epithelial tissue.

CHAPTER III.

CONNECTIVE TISSUES: CONNECTIVE TISSUE PROPER, ADIPOSE
TISSUE OR FAT, CARTILAGE, BONE.

Following the classification of tissues we have adopted, the
next group of tissues to be studied is that known as the con-
nective tissue group. This includes : —

Connective tissue proper.
Adipose tissue or fat.
Cartilage.
Bone.

These tissues differ considerably in their external character-
istics, but are alike in that they all serve to connect and support
the other tissues of the body ; they tend to pass imperceptibly
the one into the other ; there are many points of similarity
between the cells which occur in them, and we may, therefore,
reasonably group them together.

When connective tissue first begins to be formed as a distinc-
tive tissue, the cells which are set apart to form it are round in
shape and loosely packed together ; later these cells begin to
throw out branches and to form a kind of network with open
spaces. In these open spaces a semi-fluid substance is deposited
which gradually becomes more consistent, and in this substance
is developed the particular fibres which are the chief structural
characteristics of connective tissue proper.

Our description of epithelial tissue was briefly this : a skin
or membrane formed of cells, which cells may be of a variety of
shapes, and be arranged in one or more layers. It is distinctly
a tissue of cells with very little of what we call intermediate or
intercellular substance lying between the cells. Connective

13

14

ANATOMY FOR NURSES.

[Chap. III.

tissue differs from epithelial tissue in having a great deal of
intercellular substance between its cells, and according to the
manner in which this intercellular substance develops do we
get the different varieties of connective tissue.

Connective tissue proper. — There are three principal varieties
of connective tissue proper : viz. the areolar, the fibrous, and
the elastic.

Areolar tissue. — If we make a cut through the skin of some
part of the body where there is no subcutaneous fat, as in the
upper eyelid, and proceed to raise it from the parts lying beneath,

Fig. 10. — Subcutaneous Areolar Tissue from a Young Rabbit. (Highly
magnitied.) (E. A. S.) The white fibres are iu wavy bundles, the elastic fibres form
an open network, p, p, vacuolated cells; g, granular cell; c, c, branching lamellar
cells; c', a flattened cell, of which only the nucleus and some scattered granules are
visible ; /, fibrillated cell.

we observe that it is loosely connected to them by a soft filmy
substance of considerable tenacity and elasticity. This is areolar
tissue. It is also found, in like manner, under the serous and
mucous membranes,^ and serves to attach them to the parts
which they line or cover. Proceeding further, we find this
areolar tissue lying between the muscles, the blood-vessels, and
other deep-seated parts ; also forming investing sheaths for the

1 These membranes line the internal cr.vities and surfaces of the body.

Chap. III.] CONNECTIVE TISSUE PROPEE. 15

muscles, the nerves, the blood-vessels, and other parts. It both
connects and insulates entire organs, and, in addition, performs
the same office for the finer parts of which these organs are made
up. It is thus one of the most general and most extensively
distributed of the tissues. It is, moreover, continuous through-
out the body, and from one region it may be traced without
interruption into any other, however distant, — a fact not with-
out interest in practical medicine, seeing that in this way air,
water, and other fluids, effused into the areolar tissue may spread
far from the spot where they were first introduced or deposited.

Areolar tissue, when its meshes are distended, appears to
be composed of a multitude of fine threads and films crossing
irregularly in every imaginable direction, leaving open spaces
or areolce between them. Viewed with the microscope, these
threads and films are seen to be principally made up of wavy
bundles of exquisitely fine, transparent, white fibres, and these
bundles intersect in all directions. Mixed with the white fibres
are a certain number of elastic fibres, which do not form bun-
dles, and have a straight instead of a wavy outline. The
cells of the tissue, of which there
are several varieties, lie in the
spaces between the bundles of
fibres.

On comparing the areolar tissue
of different parts, it is observed in
some to be more loose and open in
texture ; in others, more close and
dense ; and accordingly free move-
ment or firm connection between
parts is provided for.

Fibrous tissue. — Fibrous tissue is
intimately allied in structure to ' '■'!}

the areolar tissue, but the bundles // '' ■ < ■i-i

of white fibres cohere very closely, ' ' , i ;,

and instead of interlacing in every ^^^ ^^ _ f^^j^^us ' Tissue, from

direction run for the most part in the Longitudinal Section of a
1 , T ,• 1 ,1 Tendon. (After Gegeubauer.)

only one or two directions, and thus

confer a distinctly fibrous aspect on the parts which they com-
pose. This fibrous tissue is met with in the form of ligaments,
connecting the bones together at the joints, and in the form of

16 ANATOMY FOR NURSES. [Chap. III.

sinews or tendons, by means of which the muscles are attached
to the bones. It also forms fibrous membranes which invest
and protect different parts or organs of the body. Examples
of these are seen in the periosteum and perichondrium, which
cover the bones and cartilages, and in the dura mater, which
lines the skull and protects the brain. Fibrous membranes,
called fascice, are also employed to envelop and bind down the
muscles of different regions, of which the great fascia enclosing
the muscles of the thigh and leg is a well-known example ;
and, under the name of aponeuroses^ serve for the attachment of
muscles in various parts of the body. It thus appears that
fibrous tissue presents itself in the form of strong bands or
cords, and of dense sheets or membranes.

Fibrous tissue is white, with a peculiarly shining silvery
aspect. It is exceedingly strong and tough, yet perfectly
pliant ; but it is almost devoid of extensibility. By these qual-
ities it is admirably suited to the purposes for which it is used
in the human frame. By its inextensile character, and by its
strength, it maintains in apposition the parts which it connects,
and we find that the ligaments and tendons do not sensibly
yield to extension in the strongest muscular efforts ; and though
they sometimes snap asunder, it is well known that bones will
break more readily than ligaments ; and the fibrous membranes
or aponeuroses are equally strong, tough, and unyielding.

Elastic tissue. — In elastic tissue the wavy white bundles are
comparativel}'^ few and indistinct, and there is a proportionate
development of the elastic fibres. When present in large num-
bers they give a yellowish colour to the tissue. This form of
connective tissue is extensile and elastic in the highest degree,
but is not so strong as the fibrous variety, and breaks across the
direction of its fibres when forcibly stretched.

It occurs in its most characteristic form in what is called
the ligamenta suhflava^ which forms an elastic band between
some of the bones of the spine. Elastic tissue is also found in
the walls of the air tubes and in the vocal cords ; it unites the
cartilages of the larynx ; and enters largely into the formation
of the walls of the blood-vessels, especially of the arteries.

These three varieties of connective tissue agree closely with
one another in elementary structure. It is the different ar-
rangement of the cells and fibres, and the relative proportion of

Chap. Ill,]

ADIPOSE TISSUE.

17

one kind of fibre to the other, that gives them their different
characteristics : the interlacing of the wavy bundles of finest
fibres, giving us the delicate web-like areolar tissue ; the close
packing of these bundles, giving us the dense opaque fibrous
membranes and bands; and the preponderance of the elastic
fibres, furnishing the extensile elastic tissue.

This connective tissue proper, as we have already noted, is
used for purely mechanical purposes : forming inextensile bands
or pulleys ; strong protective membranes ; web-like, binding, and
supporting material; sheaths of varying degrees of density;
elastic bands or membranes ; and it also serves to carry the
blood-vessels, lymphatics, and nerves to the parts which it
connects and covers.

Adipose tissue. — When fat first begins to be formed in the
embryo, it is deposited in tiny droplets in some of the cells

Fin. 12. — A Few Fat-Cells from the Margin of a Fat-Lobule. Very
highly magnified, f.g. fat-globules distending a fat-cell ; n, nucleus; m, membran-
ous envelope of the fat-cell; c, capillary vessel; v, veinlet; c.t. connective-tissue
cell ; the fibres of the connective tissue are not shown.

of the areolar connective tissue ; these droplets increase in size,
and eventually run together so as to form one large drop
in each cell. By further deposition of fat the cell becomes
swollen out to a size far beyond that which it possessed orig
inally until the protoplasm remains as a delicate envelope sur-

18 ANATOMY FOR NURSES. [Chap. III.

rounding the fat drop. As these cells increase in number they
collect into small groups or lobules, which lobules are for the
most part lodged in the meshes of the areolar tissue, and are
also supported by a fine network of blood-vessels. This fatty
tissue exists very generally throughout the body, accompanying
the still more widely distributed areolar tissue in most parts,
though not in all, in which the latter is found. Still, its dis-
tribution is not uniform, and there are some situations in which
it is collected more abundantly. It forms a considerable layer
underneath the skin, in the subcutaneous areolar tissue ; it is
collected in large quantity around certain internal parts, espe-
cially the kidneys ; it is seen filling up the furrows on the
surface of the heart ; it is deposited beneath the serous mem-
branes, or is collected between their folds ; collections of fat
arie also common around the joints, padding and filling up
inequalities ; and, lastly, fat exists in large quantities in the
marrow of the long bones.

Adipose tissue, unless formed in abnormal quantities, confers
graceful outlines upon the human frame ; it also constitutes an
important reserve fund, by storing up fatty materials, derived
from the food and brought to it by the blood, in such a form
and manner as to be readily reabsorbed into the circulation
when needed.

Cartilage. — This is the well-known substance called "gristle."
When a very thin section is examined with a microscope, it is
seen to consist of nucleated cells disposed in small groups in a
mass of intercellular substance. This intercellular substance
is sometimes transparent, and to all appearances homogeneous
or structureless ; sometimes dim and faintly granular, like
ground glass: both these conditions are found in what is called
*' true " or hyaline cartilage, and which is the most typical form
of the tissue. There is anotlier variety of cartilage, in which
the intercellular substance is everywhere pervaded with fibres.
When the fibres are of the white variety, it is called white
fibro-cartilage ; when they are elastic fibres, it is called yellow
or elastic fibro-cartilage.

Although cartilage can be readily cut with a sharp knife, it
is nevertheless of very firm consistence, but at the same time
highly elastic, so that it readily yields to extension or pressure,
and immediately recovers its original shape when the con-

Chap. III.]

CARTILAGE.

19

Is

jji

straining force is withdrawn. By reason of these mechanical
properties it serves important purposes in the construction of
some parts of the body.

Hyaline cartilage occurs chiefly
in two situations ; viz. covering
the ends of the bones in the
joints, where it is known as
articular cartilage, and forming
the rib cartilages, where it is
known as costal cartilage. In
both these situations the carti-
lages are in immediate connec-
tion with bone, and may be said
to form part of the skeleton.
The articular cartilages, in cov-
ering the ends or surfaces of
bones in the joints, provide these
harder parts with a smooth and
yielding surface, the smoothness
giving ease to the motion of the
joint, and the elastic yielding sur-
face breaking the force of con-
cussions. The costal cartilages,
in forming a considerable part of
the solid framework of the thorax or chest, impart elasticity to
its walls. Cartilage also enters into the formation of the nose,
ears, larynx, and windpipe. It strengthens these parts without
making them unduly rigid, maintains their shape, keeps them
permanently open, and gives attachment to moving muscles and
connecting ligaments.

Elastic or yellow fibro-cartilage is tougher and more flexible
than hyaline cartilage ; it occurs only in parts of the throat
and ear.

White fibro-cartilage is found wherever great strength com-
bined with a certain amount of rigidity is required; thus we
find it joining bones together, the most familiar instance being
the flat round plates or disks of fibro-cartilage connecting the
bones of the spine and the pubic bones. White fibro-cartilage
very closely resembles white fibrous tissue.

Cartilage is not supplied with nerves, and very rarely with

Fig. 13. — Articular Hyalinb
Cartilage from the Femur of an
Ox. s, intercellular substance; p,
protoplasmic cell ; n, nucleus. (Ran-
vier.)

20 ANATOMY FOR NURSES. [Chap. III.

blood-vessels. Being so meagrely supplied with blood the vital
processes in cartilage are very slow, and when a portion of it is
absorbed in disease or removed by the knife, it is regenerated
very slowly. A wound in cartilage is usually at first healed by
connective tissue proper, which may or may not become grad-
ually transformed into cartilage. Nearly all cartilages receive
their nourishment from the perichondrium which covers them,
and which is a moderately vascular fibrous membrane.

Bone. — Bone is a connective tissue in which the intercellular
or ground substance is rendered hard by being impregnated
with mineral salts.

On sawing up a bone it will be seen that it is in some parts
dense and close in texture, appearing like ivory, whilst in others
it is open and spongy, and we distinguish two forms of bony
tissue, the dense or compact, and the spongy or cancellated.
On closer examination, however, it will be seen that the bony
matter is everywhere porous, and that the difference between
the two varieties of tissue arises from the fact that the compact
tissue has fewer spaces and more solid matter between them,
and that the cancellated has larger cavities and more slender
intervening bony partitions. In all bones the compact tissue
is the stronger ; it lies on the surface of the bone and forms an
outer shell or crust, whilst the lighter spongy tissue is con-
tained within. The shafts of the long bones are almost entirely
made up of the compact substance, except that they are hol-
lowed out to form a central canal — the medullary canal —
which contains the marrow.^ Marrow is also found in the
spongy portions of the bone in the spaces between the bony
partitions.

The hard substance of all bone is arranged in bundles of
bony fibres or lamellce, which in the cancellated texture join
and meet together so as to form a structure resembling lattice-
work (cancelli)^ and whence this tissue receives its name. In
the compact tissue these lamelhie are usually arranged in rings
around canals which carry blood-vessels in a longitudinal direc-
tion through the bones. Between the lamellae are branched

1 There are two kinds of marrow, red and yellow. Red marrow contains,
in 100 parts, 75 of water and 25 of solids, the solids consisting of albumin,
fibrin, extractive matter, salts, and a mere trace of fat. Yellow marrow con-
tains, in 100 parts, 96 of fat, 1 of areolar tissue and vessels, and 3 of fluid.

Chap. III.]

BONE.

21

cells which lie in cell-spaces or cavities called lacunce, and run-
ninof ont in a wheel-like or radial direction from each lacuna
are numerous tiny canals or canaliculi connecting one cell-space
or lacuna with another, and forming a system of minute inter-
communicating channels.

All bones are covered by a vascular fibrous membrane, the
periosteum, and, unlike cartilage, the bones are plentifully sup-
plied with blood. If
we strip this perios-
teum from a fresh
bone, we see many
bleeding points repre-
senting the apertures
through which the
blood-vessels enter the
bone. After entering,
the blood runs through
short longitudinal
channels which com-
municate freely with
one another, and are
called, from the name
of their discoverer,
Haversian canals.
Around these Haver-
sian canals, as we have
already stated, the la-
mellae are disposed in
rings, while the lacunae
containing the bone-
cells are also arranged,
between the lamellce,
in circles around the
canals. As the canaliculi run in a radial direction from the
lacunce across the lamellse, it follows that the innermost ones
must run into the Haversian canals, so that there is a direct
communication between the blood in these canals and the cells
in all the lacunse connected with and surrounding each Haver-
sian canal. In this way the whole substance of the bone is
penetrated by intercommunicating channels, and nutrient mat-

FiG. 14. — Transverse Section of Compact
Tissue (of Humerus). (Masnified about 150 diam-
eters.) (Sharpey.) Three of the Haversian canals
are seen, with their concentric rings faintly indi-
cated ; also the lacunae, with the canaliculi extend-
ing from them across the direction of the encircling
lamellse, or concentric rings.

22 ANATOMY FOR NURSES. [Chap. III.

ters and mineral salts from the blood in the Haversian canals
can find their way to every part.

The mineral or earthy substance which is deposited in bone,
and which makes it hard, amounts to about two-thirds of the
weight of the bone. It consists chiefly of phosphate of lime,
with about a fifth part of carbonate of lime, and a small portion
of other salts. The soft or animal matter consists chiefly of
blood-vessels and connective tissue, and may be resolved by boil-
ing almost entirely into gelatine : it constitutes about one-third
of the weight of the bone.

In the reunion of fractured bones new bony tissue is formed
between and around the broken ends, connecting them firmly
together; and when a portion of bone dies, the dead part be-
comes separated from the living bone, and if thrown off or
removed, a growth of new bone very generally takes place to
a greater or less extent. The periosteum is largely concerned
in the nutrition and repair of bone ; for if a portion of the
periosteum be stripped off, the subjacent bone will be liable to
die, while if a large part or the whole of a bone be removed,
and the periosteum at the same time left intact, the bone will
wholly, or in a great measure, be regenerated.

In the embryo the foundation of the skeleton is laid in cartilage, or in primi-
tive membranous connective tissue, ossification of the bones occurring later.
The hardening or ossification of the bones is accomplished by the penetration of
blood-vessels and bone-cells, called osteo-blasts, from the periosteum. As they
penetrate into the cartilaginous or membranous models, they absorb the car-
tilage and connective tissue and deposit the true bone tissue at various points
until they form the particular bony structure with which we are familiar.

CHAPTER IV.

THE SKELETON.

The bones are the principal organs of support, and the pas-
sive instruments of locomotion. Connected together in the
skeleton, they form a framework of hard material, affording
attachment to the soft parts, maintaining them in their due
position, sheltering such as are of delicate structure, giving sta-
bility to the whole fabric, and preserving its shape.

The entire skeleton in the adult consists of two hundred dis-
tinct bones. These are : —

The spine, or vertebral column (sacrum and coccyx

included) 26

Cranium 8

Face 14

Os hyoides, sternum, and ribs 26

Upper extremities 64

Lower extremities 62

200

In this enumeration the patellce, or knee-pans, are included as
separate bones, but the smaller sesamoid bones, and the small
bones of the ear, are not included.

These bones may be divided, according to their shape, into
four classes : Long, Short, Flat, and Irregular.

The long and short bones are found in the extremities. The
flat and irregular bones are found in the trunk and head, with
the exception of the patellce, which are two small flat bones
found in the lower extremities, and the scapulce, which are also
two flat bones usually reckoned among the bones of the upper
extremities.

The bones of the trunk and head are used chiefly to form

23

24

ANATOMY FOR NUESES.

[Chap. IV.

cavities and to support and
protect the organs contained
in these cavities. The bones
of the extremities enclose no
cavities, and are chiefly used
in the upper extremity for
tact and prehension, and in
the lower for support and
locomotion ; in both situa-
tions they form a system of
levers. If the surface of any
bone is examined, certain
eminences and depressions
are seen, which are of two
kinds : articular and non-
articular. Non-articular pro-
cesses and depressions serve
for attachment of ligaments
and muscles ; the articular
are provided for the mutual
connection of joints.

Long bones. — A long bone
consists of a lengthened
cylinder or shaft and two
extremities. The shaft is
formed mainly of compact
tissue, this compact tissue
beingf thickest in the mid-
die where the bone is most
slender and the strain great-
est, and it is hollowed out
in the interior to form the
medullary canal. The ex-
tremities are made up of

vr^ ir. T„„, a^„,„^^, -ti spongy tissue with only a

tiG. 15. — The Skeleton, or, parietal '■ '=>-' •'

bone; 6, frontal; c, cervical vertebrte; d, thin COating of COmpact Sub-

sternum; Mumbar vertebra. ;/, ulna; fir, ra- ^^ .^^^^ ^^,^ ^^^^ ^^ j^^g

dius ; n, wrist or carpal bones ; t, metacarpal

bones; A;, phalanges ; ;, tibia; jh, fibula; ?i, expanded for greater COn-

tarsal bones; o metatarsal; p phalanges; ^gnience of mutual COnnec-
q, patella; r, femur; s, haunch bone; t,

humerus; u, clavicle. tion, and to afford a broad

Chap. IV.] THE SKELETON. 25

surface for muscular attachment. All long bones are more or
less curved, which gives them greater strength and a more
graceful outline.

Short bones. — The short bones are small pieces of bone
irregularly shaped. Their texture is spongy throughout, ex-
cepting at their surface, where there is a thin crust of compact
substance.

Flat bones. — Where the principal requirement is either exten-
sive protection or the provision of broad surfaces for muscular
attachment, the bony tissue expands into broad or elongated
flat plates. The flat bones are composed of two thin layers of
compact tissue, enclosing between them a variable quantity of
cancellous tissue. In the bones of the skull this outer layer
is thick and tough; the inner one, thinner, denser, and more
brittle. The cancellated tissue lying between the two layers,
or " tables of the skull," is called the diploe.

Irregular bones. — The irregular bones are those which, on
account of their peculiar shape, cannot be grouped under either
of the preceding heads.

Bones of the upper extremity : — ■

Clavicle (collar bone) 2

Scapula (shoulder blade) 2

Humerus (arm) 2

Ulna, 2 ) .„ ^

Kadius,2y(^°^-^^^'^) ^

Carpus (wrist) 16

Metacarpus (palm of hand) „ . 10

Phalanges (fingers) 28

64
Thus enumerated we see that the bones of the upper extrem-
ity consist of the shoulder girdle (clavicle and scapula), of the
arm, the forearm, and the hand ; the bones of the hand being
further subdivided into those of the wrist, the palm of the hand,
and the fingers.

The clavicle forms the anterior portion of the shoulder girdle.
It articulates by its inner extremity with the sternum, and by
its outer extremity with the acromion process ^ of the scapula.

1 All eminences and projections of bones are termed processes, and these
processes were named by the early anatomists, either from their shape or use,
or from their fancied resemblance to some well-known object. It is well to look

26

ANATOMY FOR NURSES.

[Chap. IV.

Fig. 16. — The Clavicle

In the female the clavicle is generally less curved, smoother,
and more slender than in the male. In those persons who

perform considerable
manual labour, which
brings into constant
action the muscles con-
nected with this bone,
it acquires considerable
bulk.

The scapula, or shoul-
der blade, forms the
back part of the shoul-
der girdle. It is a large
flat bone, triangular in
shape, placed between
the second and seventh,
or sometimes eighth,
ribs on the back part
of the thorax. It is
unevenly divided on its
dorsal surface by a very
prominent ridge, the
spine of the scapula,
which terminates in a
large triangular projec-
tion called the acromion
process, or summit of
the shoulder. Below

„ the acromion process,

FiQ. 17. — The Scapula. 1, glenoid cavity ; - i, i j f

2, end of the spine of scapula. and at the liead 01

up the meaning of these Greek or Latin words which are used so plentifully in
naming all parts of the skeleton ; the whole subject will become more interest-
ing, more readily understood, and more easily remembered. A glossary for this
purpose is added at the end of the book.

Chap. IV.]

THE SKELETON.

27

It'

i^f

-M

Mz

i:3

the shoulder blade is a shallow socket, the glenoid cavity, which
receives the head of the humerus.

The humerus is the longest and
largest bone of the upper limb.
The upper extremity of the bone
consists of a rounded head joined
to the shaft by a constricted neck,
and of two eminences called the
greater and lesser tuberosities. The
head articulates with the glenoid
cavity of the scapula. The con-
stricted neck above the tuberosities
is called the anatomical neck, and
that below the tuberosities the sur-
gical neck, from its being often the
seat of fracture. The lower ex-
tremity of the bone is flattened
from before backwards into a broad
articular surface, which is divided
by a slight ridge into two parts, by
means of which it articulates with
ulna and radius.

The ulna (elbow bone) is placed
at the inner side of the forearm,
parallel with the radius. Its upper
extremity presents for examination
two large curved processes and two
concave cavities; the larger process
forms the head of the elbow, and
is called the olecranon process. The
lower extremity of the ulna is of
small size, and is excluded from the
wrist by a piece of fibro-cartilage.

The radius is situated on the outer

side of the forearm. The upper Fig.IS.- The Humerus, a,

^ J- rounded head ; gt, greater tuber-

end is small and rounded with a osity; it, lesser tuberosity; b,

shallow depression on its upper sur- fZlV""' ^"^'^'"'"' ^^ ^'''^^^
face for articulation with the hume-
rus, and a prominent ridge about it, like the head of a nail
by means of which it rotates within the lesser sigmoid cav-

I'.iijH

■\i

'■'']

\:

28

ANATOMY FOR NURSES.

[Chap. IV.

ity of the ulna. The lower end of the radius is large, and
forms the chief part of the wrist.

The carpus, or wrist, is formed of
small pieces of bone united by liga-
ments ; they are arranged in two
rows and are closely welded to-
gether, yet by the arrangement of
their ligaments allow of a certain
amount of motion. There are eight
carpal bones in each wrist; they are
named from their shape, scaphoid,
semilunar, cuneiform, etc.

Each metacarpus is formed by five
bones. These metacarpal bones are
curved longitudinally, so as to be
convex behind, concave in front ;
they articulate by their bases with
the bones of the wrist and with one
another, and the heads of the bones
articulate with the phalanges.

The phalanges, or digits, are the
bones of tlie fingers; they are four-
teen in number (in each hand),
three for each finger, and two for
the thumb. The first row articu-
lates with the metacarpal bones and
the second row of phalanges ; the
second row, with the first and third;
and the third, with the second row.
Bones of lower extremity : —

Os innominatum (hip bone) ... 2

Femur (thigh bone) 2

o, olecranon process, on the -t atella (knee pan) Zi

anterior surface of which are Tibia, '^ \ n \ a

seen the large (r/s) and the JTibula 2 i ^ ^^^

small {Is) cavities for the recep- m ' / i i \ -\ a

tion of the lower end of the TaiSUS (ankle) . 14

humerus and of the head of Metatarsus (soIe and instep of foot) . 10

the radius, respectively; h, Phalanges (toes) 28

head of radius. o \ / —

62

The bones of the lower extremity correspond to a great
extent with those of the upper extremity, and bear a rough

Thk Ulna and
radius; 2, ulna;

Chap. IV.]

THE SKELETON.

29

resemblance to them. They consist, as stated above, of the
OS innominatum, which forms the pelvic girdle connecting
the lower extremity with the trunk, of the thigh, the leg,
and the foot. The foot is separable into ankle, sole and
instep, and toes.

The OS innominatum, or nameless bone, so called from bear-
ing no resemblance to any known object, is a large irregular-
shaped bone, which, with its fellow of the opposite side, forms
the sides and front wall of the pelvic cavity. In young

Fig. 20. — Bones of the Wrist and Hand, m, metacarpal bones ;
p, phalanges; 3, bones of the wrist.

subjects it consists of three separate parts, and although in
the adult these have become united, it is usual to describe
the bone as divisible into three portions, — the ilium, the
ischium, and the pubes. The ilium, so called from its sup-
porting the flank, is the upper broad and expanded portion
which forms the prominence of the hip. The ischium is the
lower and strongest portion of the bone, while the pubes is
that portion which forms the front of the pelvis. Where
these three portions of the bone meet and finally ankylose is
a deep socket, called the acetabulum, into which the head of

30

ANATOMY FOR NURSES.

[Chap. IV.

the femur fits. Other points of special interest to note are
(1) the spinous process formed by the projection of the crest
of the ilium in front, which is called the anterior superior
spinous process, and which is a well-known and convenient
landmark in making anatomical measurements ; (2) the largest

Fig. 21. — Os Innominatum. Outer surface. R, O, crest of ilium, just below 0
is seen the anterior superior spinous process ; J, tuberosity of ischium ; T, part of
pubes, between J and T is seen the thyroid foramen : //, acetabulum, beloAv H is
seen end of pubic bone which, with its fellow of opposite side, forms the symphysis
pubis. (For further illustration, vide Figs. 46 and 47.)

foramen in the skeleton, known as the door-like or thyroid
foramen, situated between the ischium and pubes ; and (3) the
symphysis pubis, or pubic articulation, which also serves for
a convenient landmark in making measurements.

The femur is the longest, largest, and strongest bone in the
skeleton. In the erect position it is not vertical, the upper

Chap. IV.]

THE SKELETON.

31

end being separated from its
fellow by a considerable inter-
val, which corresponds to the
entire breadth of the pelvis,
but the bone inclines gradu-
ally downwards and inwards,
so as to approach its fellow
towards its lower part, in order
to bring the knee-joint near the
line of gravity of the body. The
degree of inclination varies in
different persons, and is greater
in the female than the male, on
account of the greater breadth
of the pelvis. The upper ex-
tremity of the femur, like that
of the humerus, consists of a
rounded head joined to the
shaft by a constricted neck, and
of two eminences, called the
greater and lesser trochanters.
The head articulates with the
cavity in the os innominatum,
called the acetabulum. The
lower extremity of the femur is
larger than the upper, is flat-
tened from before backwards,
and divided into tAvo large emi-
nences or condyles by an inter-
vening notch. It articulates
with the tibia and the patella,
or knee-pan.

The patella, or knee-cap, is
a small flat triangular bone
placed in front of the knee-
joint, which it serves to pro-
tect. It is separated from the
skin by a bursa. (See page 51.)

The tibia is situated at the front and inner side of the leg, and
forms what is popularly known as the shin bone. In the male, its

Fig. 22. — The Femur, b, rounded
head; 7i, neck; jr^r, greater trochanter ;
Itr, lesser trochanter.

32

ANATOMY FOR NURSES.

[Chap. IV.

direction is vertical and parallel
with the bone of the opposite side ;
but in the female it has a slight
oblique direction outwards, to com-
pensate for the oblique direction of
the femur inwards. The upper ex-
tremity is large, and expanded into
two lateral eminences with concave
surfaces which receive the condyles
of the femur. The lower extrem-
ity is much smaller than the upper;
it is prolonged downwards on its
inner side into a strong process,
the internal malleolus. It articu-
lates with the fibula and one of the
bones of the ankle.

The fibula is situated at the outer
side of the leg. It is the smaller
of the two bones, and, in propor-
tion to its length, the most slender
of all the long bones : it is placed
nearly parallel with the tibia. The
upper extremity consists of an ir-
regular quadrate head by means of
which it articulates with the tibia.
The lower extremity is prolonged
downwards into a pointed process,
the external malleolus, which lies
just beneath the skin. It articu-
lates with the tibia and one of the
bones of the ankle.

The tarsus, or ankle, like the
carpus, or wrist, is composed of
small pieces of bone united by
ligaments, but the tarsal bones
differ from the carpal in being
larger and more irregularly shaped.
The largest and strongest of the tarsal bones is called the
OS calcis, or heel bone ; it serves to transmit the weight of
the body to the ground, and forms a strong lever for the

Fig. 23.— The Tibia and Fibula.
o, tibia; /, fibula; etu and itu, lat-
eral eminences for reception of con-
dyles of femur; h, head of fibula;
em, external malleolus; im, internal
malleolus.

Chap. IV.]

THE SKELETON.

33

muscles of the calf of the leg. There are seven tarsal bones
in each ankle. (The names of the carpal and tarsal bones are
supplied in the table of the bones at the end of the chapter.)

The metatarsus is formed by live bones. These metatarsal
bones closely resemble the metacarpal bones of the hand. Each
bone articulates with the tarsal bones
by one extremity, and by the other
with the first row of phalanges.

The phalanges of the foot, both in
number and general arrangement,
resemble those in the hand, there
being two in the great toe and three
in each of the other toes.

Bones of the cranium : —

Occipital 1

Parietal 2

Frontal 1

Temporal 2

Sphenoid 1

Ethmoid 1

8

The occipital bone is situated at
the back and base of the skull. At
birth the bone consists of four parts,
which do not unite into a single bone
until about the sixth year. The in-
ternal surface is deeply concave, and
presents many eminences and de-
pressions for the reception of parts
of the brain. There is a large
hole — the foramen magnum — in
the inferior portion of the bone, for
the transmission of the medulla oblongata, the constricted por-
tion of the brain where it narrows down to join the spinal cord.

The parietal bones (^paries, a wall) form by their union the
greater part of the sides and roof of the skull. The external
surface is convex and smooth ; the internal surface is con-
cave, and presents eminences and depressions for lodging the
convolutions of the brain, and numerous furrows for the rami-
fications of arteries.

Fig. 24. — Bones of the
Ankle and Foot. m, meta-
tarsal boues; p, phalanges; ca,
OS calcis, or heel bone.

Fig. 25. — Occipital Bone. luner surface. 9, 9, and 10, 10, depressions for reception
of lobes of brain ; 11, foramen magnum.

Fig. 26. — Parietal Bone. Inner surface, ^.parietal depression; £, furrow for

ramification of arteries.

34

Chap. IV.]

THE SKELETON.

35

Fig. 27. — Frontal Bone. Outer surface. 1, frontal emi-
nence ; 7, roof of orbital cavity ; 10, orbital arch.

The frontal bone resembles a cockle shell in form. It not
only forms the forehead, but also enters into the formation of

the roof of the

orbits, and of
the nasal cavity.
The arch formed
by part of the
frontal bone
over the eye
is sharp and
prominent and
affords that or-
gan considera-
ble protection
from injury.
At birth the bone consists of two pieces, which afterwards
become united, along the middle line, by a suture which runs
from the vertex of the bone to the root of the nose. This

suture usually
becomes obliter-
ated within a
few years after
birth, but it occa-
sionally remains
throughout life.
The temporal
bones are situ-
ated at the sides
and base of the
skull. They are
named temporal
from the Latin
word, tempus,
time, as it is on
the temple the
hair first be-
comes gray and thin, and thus shows the ravages of time.
The temporal bones are divided into three parts : the hard,

1 The temporal, sphenoid, lachrymal, vomer, and maxillary bones are drawn
to a larger scale than the other bones of the head and face.

Fig. 28. —Temporal Bone.i 1, squamous portion; 2,
placed below external opening of auditory canal in petrous
portion : 3, placed below mastoid portion ; 4, placed below
glenoid cavity for reception of condyle of lower jaw.

36

ANATOMY FOR NURSES.

[Chap. IV.

dense portion, called petrous; a thin and expanded scale-like
portion, called squamous ; and a mastoid portion, which is per-
forated by numerous holes and contains a number of sinuses or

Fig. 29. — Sphenoid Bone, a, greater wing; b, lesser wing.

air spaces. The internal ear, the essential part of the organ
of hearing, is contained in a series of cavities, channelled out of
the substance of the petrous portion. Between the squamous

and petrous portions is a socket for
the reception of the condyle of the
lower jaw.

The sphenoid bone {sphen, a wedge)
is situated at the anterior part of the
base of the skull, articulating with all
the other cranial bones, which it binds
firmly and solidly together. In form
it somewhat resembles a bat with ex-
tended wings.

The ethmoid bone is an exceedingly
light, spongy bone, placed between the
two orbits and at the root of the nose,
contributing to form a part of each of
these cavities. The portion of the bone
situated at the back of the nose, which forms the roof of the
nasal fossae and also closes the anterior part of the base of
the skull cavity, is pierced by numerous holes, through which

Fig. 30. — E j;hmoii> Bone
Posterior surface. 2, cribri
form, or perforated plate.

Chap. IV.] THE SKELETON. 37

the nerves conveying the sense of smell pass. Descending
from this perforated plate, on either side of the nasal cavity,
are two masses of very thin, spongy, bony tissue.
Bones of the face : —

Nasal 2

Lachrymal 2

Vomer 1

Malar 2

Palate 2

Inferior turbinated 2

Superior maxillary 2

Inferior maxillary 1

14

The nasal bones are two small oblong bones,
varying in size and form in different individ-
uals; they are placed side by
r>^-,ft side at the middle and upper

■ ■■" "tA part of the face, forming by their %;

i unction " the bridge " of the

Fig. 31. — Na-
^^^^- SAL Bone. Outer

The lachrymal are the smallest surface. J.inter-

1 j^ £ ^^ 1 <• .1 iial border; £,

ana most iragiie bones oi the external border.
Fig. 32. — Lach- face. They are situated at the

front part of the inner wall of the orbit, and
resemble somewhat in form, thinness, and size, a finger-nail.

The vomer is a single bone
placed at the back part of ^—-'^'^fi \\

the nasal cavity, and forms /■ .> / , -xxv

part of the septum of the t-""^"'. ^;^.

na^al fossse. It is thin, /^'',:^^^^'''' • '/''^'W

and shaped somewhat like a ,:::^:^0'' --" ' -■'■■'■'■'■'■ 'i,''''^^i'.-M^

ploughshare, but varies in %^. — — ■ " .■■'''-^■' v-^ii

different individuals, being
frequently bent to one or

^ "^ Fig. 33. — Vomer.

the other side.

The malar or cheek bones form the prominence of the cheek,
and part of the outer wall and floor of the orbit.

The palate bones form (1) the back part of the roof of the
mouth ; (2) part of the floor and outer wall of the nasal fossse;
and (3) a very small portion of the floor of the orbit.

38

ANATOMY FOR NURSES.

[Chap. IV.

The inferior turbinated bones are situated on the outer wall
of each side of the nostril. Each consists of a layer of thin,

Fig. 34. — Malar Bone.

Fig. 35. — Palate Bone.

Fig. 30. — Inferior Tureinated
Bone. Convex surface.

spongy bone, curled upon itself like a scroll ; hence its name,

"turbinated."

The superior maxillary is one of the most important bones

of the face, in a surgical point of
view, on account of the number of
diseases to which some of its parts
are liable. With its fellow of the
opposite side, it forms the whole of
the upper jaw. Each bone assists

in forming part of the floor of the orbit, the floor and outer

wall of the nasal fossoe,

and the greater part of the

roof of the mouth. That

part of the bone which con-
tains the teeth is called the

alveolar process, and is exca-

vat€id into cavities, varying

in depth and size according

to the size of the teeth they

contain. There are eight

cavities in each bone: those

for the canine teeth are

the deepest ; those for the

molars are widest and sub-
divided into minor cavities;

those for the incisors are

single, but deep and narrow.

""'Xe. Bicuspids

Fig. 37. — Superior Maxillary Bone.
1, orbital surface; 2, facial surface; 3, alveo-
lar process.

Chap. IV.]

THE SKELETON.

39

Coronoid process.

The inferior maxillary, or lower jaw, is the largest and

strongest bone of the face, and serves for

the reception of the lower teeth. At birth,

it consists of two lateral halves, which

join and form one bone during the first or

second year. The lower jaw undergoes

several changes in shape during life, owing

mainly to the hrst

and second denti-
tion, to the loss of

teeth in the aged,

and the subsequent

absorption of that

part of the bone

which contained

them. It articulates, by its condyles, with the sockets in the

temporal bones.

The hyoid, os hyoides, or tongue bone, is an isolated, U-shaped
bone lying in front of the throat, just above
"Adam's apple"; it supports the tongue, and
gives attachment to some of its numerous
muscles.

The spine or vertebral column is formed of a
series of bones called vertebrse. The vertebrae

are thirty-three in number, and according to the position

they occupy are named : —

Cervical 7

Dorsal 12

Lumbar 5

Sacral 5

Coccygeal 4

33

Fig. 39.— Hyoid
Bone.

The vertebrre in the upper three portions of the spine are
separate throughout the whole of life ; but those found in
the sacral and coccygeal regions are, in the adult, firmly
united, so as to form two bones, five entering into the upper
bone, or sacrum, and four into the terminal bone of the spine,
or coccyx.

Each vertebra consists of two essential parts, an anterior

40

ANATOMY FOR NURSES.

[Chap. IV.

solid portion or body, and a posterior portion or arch. The
bodies of the vertebroe are piled one upon another, forming a
solid, strong pillar, for the support of the cranium and trunk,
the arches forming a hollow cylinder behind for the protection
of the spinal cord. Each arch has seven processes : four
articular, two transverse, and one spinous process. The dif-
ferent vertebrae are connected together by means of the articu-
lar processes, and by disks of intervertebral fibro-cartilage
placed between the vertebral bodies, while the transverse and
spinous processes serve for the attachment of muscles which
move the different parts of the spine. In the cervical region of

the vertebral column
the bodies of the ver-
tebras are smaller than
in the dorsal, but the
arches are larger ; the
spinous processes are
short, and are often
cleft in two, or bifid.
The first and second
cervical vertebrse
differ considerably
from the rest. The
first, or atlas, so
named from support-
ing the head, has
practically no body,
and may be described as a bony ring divided into two sections
by a transverse ligament. The dorsal section of this ring
contains the spinal cord, and the ventral or front section
contains the bony projection which arises from the upper sur-
face of the body of the second cervical vertebra, or axis. This
bony projection, called the odontoid process, represents the
body of the atlas. Around this peg the atlas rotates when
the head is turned from side to side, carrying the skull, to
which it is firmly articulated, with it. The bodies of the dorsal
vertebras are larger and stronger than those of the cervical ;
they contain depressions for the reception of the vertebral
ends of the ribs. The bodies of the lumbar vertebrse are the
largest and heaviest in the whole spine. The sacrum, formed

Fig. 40. — A Cervical Vertebra. Inferior sur-
face. 1, spinous process, slightly bifid ; 4, transverse
process ; 5, articular process, inferior surface. Below
the arch, or hollow portion, is seen the solid portion,
or body.

Chap. IV.]

THE SKELETON.

41

by the union of the five sacral vertebrse, is a large triangular
bone situated like a wedge between
the ossa innominata ; it is curved
upon itself in such a way as to give
increased capacity to the pelvic
cavity (^vide Fig. 47). The coccyx
is usually formed of four small seg-
ments of bone, and is the most
rudimentary part of the vertebral
column.

The vertebral column as a whole. —
Tlie spinal column in a man of aver-
age height is about twenty-eight
inches long. Viewed from the side
it presents four curvatures; the first
curve has its convexity forwards in
the cervical region, and is followed
in the dorsal, by a curve with its a-
concavity towards the chest. In the
lumbar region the curve has again
its convexity forwards, while in the
sacral and coccygeal regions the con-
cavity is turned forwards. These
curvatures confer a considerable
amount of springiness and strength
upon the spinal column which would
be lacking were it a straight column :
the elasticity is further increased by
the disks of fibro-cartilage lying be-
tween and connecting the bodies of
the vertebroe. These disks or pads
also mitigate the effects of concussion
arising from falls or blows, and allow
of a certain amount of motion be- iporrct.

tween the vertebras. The amount Fig. 4i. — Side View of Spi-

Of motion permitted is greatest in ^^^ Column, without Sacrum

^ => AND Coccyx. 1 to 7, cervical

thp cervical region. Between each vertebrEe; 8 to 19, dorsal verte-

P , 1 ^ 1. i\ 1 brse; 20 to 24, lumbar vertebrae;

pair of vertebrse are apertures through ^^ ^^ ^pi^^,^, processes; (7, B,

which the spinal nerves pass from transverse processes; E, inter-
, , . , 1 vertebral aperture or foramen :

the spinal cord. l^ atlas; 2, axis.

42

ANATOMY FOR NURSES.

[Chap. IV.

The thorax, or chest, is an elongated conical-shaped cage,
formed by the sternum and costal cartilages in front, the
twelve ribs on each side, and the bodies of the twelve dorsal

J^IESNARD.

Fig. 42. — Thorax. 1 to 12, ribs; c/, d, costal cartilages ; c, upper end of sternum;
6, middle portion of sternum; la, first dorsal vertebra; 12 «, twelfth dorsal verte-
bra ; 7 a, seventh cervical vertebra ; 1 to 7, true ribs ; 8 to 12, false ribs : 11, 12, float-
ing ribs. 10th rib is defective ; it should be attached to the costal cartilage.

vertebrae behind. It contains and protects the 23rincipal organs
of respiration and circulation.

The sternum, or breast bone, is a flat narrow bone, situated
in the median line in the front of the chest, and consisting,
in the adult, of three portions. It has been likened to an
ancient sword. The ui)per piece, rejDresenting the handle, is

Chap. IV.]

THE SKELETON.

43

termed the manubrium or handle ; the middle and largest
piece, which represents the chief part of the blade, is termed
the , gladiolus ; and the inferior piece, which is likened to the
point of the sword, is termed
the ensiform appendix. On
both sides of the upper and
middle pieces are notches for
the reception of the sternal
ends of the costal cartilages.
The ensiform appendix is carti-
laginous in structure in early
life, but is more or less ossified
at the upper part in the adult :
it has no ribs attached to it.
The sternum is about six inches
long, being rather longer in the
male than in the female.

The ribs are elastic arches of
bone, forming the chief part of
the thoracic wall (^vide Fig. 42).
They are usually twelve in
number on each side. They
are all connected behind with

the vertebrae, and the first seven pairs are connected with the
sternum in front through the intervention of the costal carti-
lages: these first seven pairs are called from their attachment
the vertebro-sternal, or true ribs. The remaining five pairs
are termed false ribs; of these, the first three, being attached
in front to the costal cartilages, are usually called the vertebro-
costal, while the two remaining, being unattached in front,
are termed vertebral, or floating ribs. The convexity of the
ribs is turned outwards so as to give roundness to the sides of
the chest and increase the size of its cavity; each rib slopes
downwards from its vertebral attachment, so that its sternal
end is considerably lower than its dorsal. The spaces left
between the ribs are called the intercostal spaces.

The skull as a whole. — The skull, formed by the union of
the cranial and facial bones already described, is divisible into
cranium or brain case, and the anterior region or face.

The bones of the cranium begin to develop at a very early

Fig. 43. — Sternum. Front and side
view.

44

ANATOMY FOR NURSES.

[Chap. IV.

period of foetal life. Before birth the bones at the top and
sides of the skull are separated from each other by membra-
nous tissue in which bone is not yet formed. The spaces
at the angles of the bone occupied by this membranous tissue
are termed the fontaiielles, so named from the pulsations of
the brain, which can be seen in some of them, rising like the
water in a fountain. There are six of these fontanelles. The

Fia. 44. — The Skull, a, nasal bone; 6, superior maxillary ; c, inferior maxillary;
d, occipital; e, temporal; /, parietal; g, frontal bone.

anterior fontanelle is the largest, and is a lozenge-shaped space
between the angles of the two parietal bones and the two
segments of the frontal bone. The posterior fontanelle is
much smaller in size, and is a triangular space between the
occipital and two parietal bones. The other four fontanelles,
two on each side of the skull, are placed at the inferior angles
of the parietal bones : they are comparatively unimportant.
The posterior fontanelle is closed by an extension of the ossify-
ing process a few months after birth. The anterior remains

Chap. IV.] THE SKELETON. 45

open until the second year, and occasionally persists throagh-
out life. The base of the skull is much thicker and stronger
than the walls and roof ; it presents a
number of openings for the passage of
the cranial nerves, blood-vessels, etc.

The diameters of the foetal skull
given by King are : —

Occipito-niental (from posterior fontanelle

to chin) . . . . 5|- inches (140 mm.).

Occipito-frontal (centre of frontal bone to

occiput) .... 41 inches (114 mm.).

Bi-parietal (from one parietal prominence ^,^ 45. -t1^ Skull at

to another) . . 3^ inches (89 mm.). Birth. Superior surface. 1,

posterior fontanelle ; 2, sagit-
tal suture ; 4, anterior fon-

The foetal cranial bones being iraper- taneiie; a, a, bi-parietal

«., -n 1 ivi-i .T diameter; B, B, bi-temporal

lectly ossmed, and their edges separated diameter.

by membranous intervals, they are

readily moulded, and they overlap one another more or less

during parturition.

The pelvic cavity. — The pelvis, so called from its resemblance
to a basin, is stronger and more massively constructed than
either the cranial or the thoracic cavity. It is composed of
four bones, the ossa innominata, forming sides and front, and
the sacrum and coccyx, completing it behind. It is divided
by a brim or prominent line, the linea ilio-pectinea, into the
false and true pelvis. The false pelvis is all that expanded
portion of the pelvis situated above the brim : it forms an in-
complete or " false " basin. The true pelvis is all that portion
situated below the brim. Its cavity is a little wider in every
direction than the brim itself, while the false pelvis is a great
deal wider. The brim is, therefore, a narrowed bony ring or
aperture between these two cavities; hence it is often termed
the "strait"; while the space included within the strait or
brim, is called the " inlet." The true bony pelvis is a basin
with incomplete walls of bone and without a bottom to it: the
opening below is called the "inferior strait" or "outlet."

The female pelvis differs from that of the male in those
particulars which render it better adapted to parturition,
notably in being wider in every direction, which gives more

46 ANATOMY FOR NURSES. [Chap. IV.

room for the child to pass; in being shallower, which lessens

Fig. 46. — Male Pelvis.

the distance through which the child has to be propelled; and
lastly, in the bones being thinner and smoother.

Fig. 47. — Female Pelvis.

Chap. IV.] THE SKELETON. 47

The diameters of an average female pelvis given by King
are : —

Antero-posterior diameter of brim or inlet, 4 in. (102 mm.).

Transverse diameter of brim or inlet . . 4 in. (102 mm.).

Oblique dia:meter of brim or inlet . . . 4^ to 5 in. (114 to 127 mm.).

Antero-posterior of outlet 41 to 5 in. (114 to 127 mm.).

Transverse of outlet 4 in. (102 mm.).

Oblique of outlet 4 in. (102 mm.).

TABLE OF THE BONES.

Head.

Cranium.

Face.

Occipital.

Nasal.

Parietal.

Lachrymal.

Temporal.

Malar.

Frontal.

Superior maxillary.

Ethmoid.

Inferior maxillary.

Sphenoid.

Palate.

Inferior turbinated.

Vomer.

Os hyoides.

7 cervical.

12 dorsal.

Vertebrae

5 lumbar.

5 sacral, or sacrum.

Trunk.

. 4 coccygeal,

or coccyx.

Ribs.

Sternum.

Clavicle.

Os innominatum.

Humerus.

Femur.

Ulna.

Patella.

Radius.

>^

Tibia.

|H

\ Scaphoid.

H

Fibula.

Semilunar.

Os calcis.

Cuneiform.

Astragalus.

04
H

Carpus

Pisiform.

Cuboid.

Trapezium.

Tarsus ■

Scaphoid.

4

Trapezoid.

04

Internal cuneiform.

^

Os magnum.

p

Middle cuneiform.

o

^ Unciform.

External cuneiform.

Metacarpus.

Metatarsus.

Phalang

es, or digits.

Phalang

3S, or digits.

CHAPTER V.

JOINTS.

Fig. 48. — A Toothed, or
Dentated Suture.

The various bones of which the skeleton consists are con-
nected together at different parts of their surfaces, and such
connections are called joints or articulations.

In all instances some softer substance is placed between the
bones, uniting them together, or clothing the opposed surfaces ;
but the manner in which the several pieces
of the skeleton are thus connected varies
to a great degree. We distinguish three
varieties ; viz. those which are (1) immov-
able, (2) slightly movable, (3) freely
movable.

The immovable articulations. — The bones
of the cranium and the facial bones (with
the exception of the lower jaw) have
their adjacent surfaces applied in close

contact, with only a thin layer of fibrous tissue or of cartilage
placed between their margins. In most of the cranial bones

this union occurs by means of toothed
ed^es which fit into one another and
form jagged lines of union known as
sutures. The suture between the fron^
tal and parietal bones is called the
coronal suture; between the parietal
and occipital, the larabdoidal; and be-
LATioN. a, b, di.sk of fibro-car- twcen the two parietal bones, along the
d!w.'' ''''''"'''' '''''"^^"'' middle line on the top of the crown,

the sagittal suture.
The slightly movable or mixed articulation. — In this form of
articulation the bony suifaces are usually joined together by

48

Fig. 49. — A Mixed Articu-

Chap. V.]

JOINTS.

49

broad, flattened disks of fibro-cartilage, as in the articulations
between the bodies of the vertebrse. These intervertebral
disks being compressible and extensile, the spine can be moved
to a limited extent in every direction. In the pelvis the articu-
lation between the two pubic bones (symphysis pubis), and
between the sacrum and ilia (sacro-iliac articulation), are also
slightly movable. The pubic bones are united by a disk of
fibro-cartilage and by ligaments. In the sacro-iliac articulation
the sacrum is united more closely to the ilia, the articular sur-
faces being covered by cartilage and held together by ligaments.
The movable articulations. — This division includes the com-
plete joints, — joints having a secreting membrane placed be-
tween their opposing surfaces, which keeps them well lubricated
and capable of free movement one upon the other. Each articular
end of the bone is covered by cartilage, which provides surfaces

of remarkable smoothness, and
these surfaces are lubricated by
the synovial fluid secreted from
the delicate synovial membrane
which lines the cavity of the
joint. This membrane is contin-
uous with the margin of the ar-
ticular cartilage, and along with
them completely encloses the
joint cavity. The bones are
united by fibrous connective
tissue in tlie various forms of
ligaments, such as membranous
capsules, flat bands, or rounded cords. These ligaments are not
always so tight as to maintain the bones in close contact in all
positions of the joint, but are rather tightened in some positions
and relaxed in others, so that in many cases they are to be looked
upon chiefly as controllers of movements, and not as serving
solely to hold the bones together. The bones are mainly held
together in these joints by atmospheric pressure and by the
surrounding muscles.

The varieties of joints in this class have been determined
by the kind of motion permitted in each. They are as
follows : —

(1) Gliding joint. Tlie articular surfaces are nearly flat,

r/\.,„.

Fig. 50. — A Simple Complete Joint.
The synovial membraue is represented
by dotted lines.

60 ANATOMY FOR NURSES. [Chap. V.

and admit of only a limited amount of gliding movement,
as in the joints between the articular processes of the ver-
tebrae.

(2) Hinge joint. The articular surfaces are of such shape
as to permit of movement, to and fro, in one plane only, like a
door on its hinges. These movements are called flexion and
extension, and may be seen in the articulation of the arm with
the forearm, in the ankle joint, and in the articulations of the
phalanges.

(3) Ball and socket joint. In this form of joint a more or
less rounded head is received into a cup-like cavity, as the head
of the femur into the acetabulum, and the head of the humerus
into the glenoid cavity of the scapula. Movement can take
place freely in any direction, but the shallower the cup, the
greater the extent of motion.

(4) Pivot joints. In this form, one bone rotates around
another which remains stationary, as in the articulation of the
atlas with the axis, and in the articulation of the ulna and
radius. In the articulation of the ulna and radius, the ulna
remains stationary and the radius rotates freely around its
upper end. The hand is attached to the lower end of the
radius, and the radius, in rotating, carries the hand with it;
thus, the palm of the hand is alternately turned forwards and
backwards.^ When the palm is turned forwards, the attitude
is called supination ; when backwards, pronation.

(5) Ootid i/loid joints. When an oval-shaped head, or con-
dyle, of a bone is received into an elliptical cavity, it is said to
form a condyloid joint. An example of this kind of joint is
found in the wrist.

(6) Saddle joints. In this joint the articular surface of each
bone is concave in one direction, and convex in another, at
right angles to the former. A man seated in a saddle is
"articulated" with the saddle by such a joint. For the saddle
is concave from before backwards, and convex from side to
side, while the man presents to it the concavity of his legs
astride, from side to side, and the convexity of his seat, from
before backwards. The metacarpal bone of tlie thumb is
articulated with the wrist by a saddle joint. Both the con-

1 Anatomists always speak of the body as being in the erect position, with
the arms hanging, and the palms of the hands looking forwards.

Chap. V.] JOINTS. 61

dyloid and the saddle joints admit of motion in every direction
except that of axial rotation.

The different kinds of movement of which bones thus con-
nected are capable, are — flexion and extension ; abduction and
adduction ; rotation and circumduction.

A limb is flexed, when it is bent; extended, when it is
straightened out. It is abducted, when it is drawn away from
the middle line of the body ; adducted, when it is brought
to the middle line. It is rotated, when it is made to turn on
its own axis ; circumducted, when it is made to describe a
conical space, by rotation around an imaginary axis. No part
of the body is capable of perfect rotation like a wheel, for the
simple reason that such motion would necessarily tear asunder
all the vessels, nerves, muscles, etc., which unite it with other
parts.

As the synovial membranes are intimately connected with
the joints, it may be well to give a brief description of them
here.

The synovial membranes are composed entirely of connective
tissue, with the usual cells and fibres of that tissue. They are
distinguished by the nature of their secretion, which is a viscid,
glairy fluid, resembling the white of an egg and named synovia.
From its nature, it is well adapted for diminishing friction, and
thereby facilitating motion.

These membranes are found surrounding and lubricating the
cavities of the movable joints in which the opposed surfaces
glide on each other ; in these situations they are called articu-
lar synovial memhraiies. They are found forming sheaths for
the tendons of some of the muscles, and thus facilitating their
motion as they glide in the fibrous sheaths which bind them
down against the bones ; they are here called vaginal synovial
membranes^ or synovial sheaths. Lastly, they are found in the
form of simple sacs, interposed, so as to prevent friction, be-
tween two surfaces which move upon each other, and in these
situations they take the name of bursal synovial membranes^ or
synovial bursse. These bursse may be either deep seated or
subcutaneous. The former are, for the most part, placed be-
tween a muscle and a bone, or between a tendon and a bone.
The subcutaneous bursse lie immediately under the skin, and
occur in various parts of the body, interposed between the skin

52

ANATOMY FOR NURSES.

[Chap. V.

and some firm prominence beneath it. The large bursa situ-
ated over the pateUa is a well-known example of this class,
but similar, though smaller, bursse are found also over the ole-
cranon, the malleoli, the knuckles, and other prominent parts.

Synarthrosis,

OR

Immovable Joint.

TABLE OF CHIP:F JOINTS.

r Sutura. — Articulations by processes and indentations
interlocked together. A thin layer of fibrous tis-
sue is interposed between the bones. Sutures may
be dentated, tooth-like ; serrated, saw-like ; squa-
mous, scale-like ; harmonic, smooth ; and grooved,
for the reception of thin plates of bone.

AmPHI ARTHROSIS,
OR

Slightly Movable

JlINT.

ri.

Diarthrosis,

OR

Movable Joint.

Symphysis. — The bones are united by a plate or
disk of fibro-cartilage of considerable thickness.

Syndosmosis. — The bony surfaces are united by
an interosseous ligament, as in the lower tibio-
fibular articulation.

1. Arlhrodia. — Gliding joint; articulates by plane
surfaces which glide upon each other.

2. Ginglymus. — Hinge or angular joint ; moves back-
wards and forwards in one plane.

3. Enarthrosis. — Ball and socket joint ; articulates
by a globular head in a cup-like cavity.

4. Pivot. — Articulates by a pivot process turning
within a ring, or by a ring turning round a pivot.

5. Condyloid. — Ovoid head received into elliptical
cavity.

6. Reciprocal Reception. — Saddle joint; articular sur-
faces are concavo-convex.

CHAPTER VI.

MUSCULAR TISSUE : STRIATED OR STRIPED ; NON-STRIATED OR
PLAIN; ATTACHMENT OF MUSCLES TO SKELETON; PROMI-
NENT MUSCLES OF HEAD AND TRUNK ; PROMINENT MUSCLES
OF LIMBS.

Muscular tissue is the tissue by means of which the active
movements of the body are produced. It is a more specialized
kind of tissue than the connective, which, as we have seen, is
used chiefly for mechanical purposes. Muscular tissue is irri-
table, and if we irritate or stimulate it, it will respond. We
may irritate or stimulate the bones, ligaments, or other connec-
tive tissue structures and they will not
respond, they will remain immovable ; if,
however, we stimulate muscular tissue,
it will show its response to the stimula-
tion by contracting. This power of the
muscle to contract is called muscular con-
tractility. All muscular tissue consists
of fibres, and whenever a muscle fibre con-
tracts, it tends to bring its two ends, with
whatever may he attached to them^ together.
Influences which irritate or stimulate
muscle fibres are spoken of under the
general name of stimuli.

Muscle fibres are of two different kinds,
and we therefore distinguish two varieties
of muscular tissue, the striped or striated,

and the plain or non-striated. The striated muscle is nearly
always under the control of the will, and is often spoken of as
voluntary muscle ; the non-striated is usually withdrawn from
the control of the will, and is often termed involuntary muscle.

Voluntary, striated muscle is composed of long slender fibres
measuring on an average about -^^ inch (.050 mm.) in diame-

53

Fig. 51. — Diagram of
Muscle Fibre with Sar-
colemma attached.

54

ANATOMY FOR NURSES.

[Chap. VI.

ter, but having a length of an inch or more. Each fibre con-
sists of three distinct elements : (1) contractile substance,
forming the centre and making up most of the bulk of the fibre ;
(2) nuclei, which lie scattered upon the surface of the con-
tractile substance; (3) the sarcolemma, a thin, structureless

tube, which tightly en-
closes the contractile sub-
stance and the nuclei.

If we examine a fresh
muscle fibre microscopi-
cally, we see that the
contractile substance is
marked with very fine in-
distinct longitudinal lines,
or stride; and in addition

Fig. 52. -Fragments of Striped Fibres, ^q ^I^q longitudinal Stria-
SHOwiNG A Cleavage in Opposite Direc- . . °

TiONS. (Magnified 300 diameters.) A, longitu- tion it is CroSSCd by more

dinal cleavage; c, fibrillae separated from one ^ligti^ct narrow dark and
another at the broken end of the fibre; c c ,

single fibrils more highly magnified, in c' the light bands or stripes,^
elementary structures are square, in c" round; • •■ ,. • -i,, n ,-,

£, transverse cleavage; a, b, partially detached ^^^^ relative WKltn Ot tllC

disks ; b' detaclied disk, more highly magnified, gtripes varying according
showing the sarcous elements. ^ n^ •

as the fibre is seen in a
state of contraction or relaxation. The ultimate structure of
muscular fibre is still by no means fully understood. This
much, however, is certain, that the contractile substance is a
complex chemical structure, and that the molecules of which it
is composed readily change their places under the influence of
certain stimuli. When a muscle contracts, the dark bands
swell up and shorten (the light bands are also constricted), and
the whole fibre broadens and shortens. This broadening and
shortening is brought about by the molecules of each section
of the fibre changing their places. We shall have a rough
image of the movements of the molecules during a muscular
contraction if we imagine a company of a hundred soldiers ten
ranks deep, with ten men in each rank, rapidly, but by a series
of gradations, extending laterally into a double line with fifty
men in each line.

1 By treating a fibre with certain chemical agents, we may cause it to break
up longitudinally into fibrillse, and transversely into thin disks. Thus each fibre
is resolvable into a number of tiny structures, which elementary structures have
been termed sarcous elements.

Chap. VI.]

THE MUSCLES.

55

The striated muscles are all connected with nerves, and under
normal conditions do not contract otherwise than by the agency of
the nerves. They are also plentifully supplied with blood-vessels.

The muscular fibres lie closely packed, their ends lapping
over on to adjacent fibres, and forming bundles. These bundles
are grouped so as to make
larger bundles, and in this
way the muscles which are
attached to the skeleton are
formed.

Involuntary, non-striated mus-
cular tissue is composed of
long, somewhat flattened,
elongated fibre-cells. Each
fibre-cell contains an oval or
rod-shaped nucleus, contain-
ing one or more nucleoli.
The substance of the fibre-
cell is longitudinally striated,
but does not exhibit trans-
verse striation. The fibre-
cells lie side by side, or lap
over one another at the ends,
and are joined together by a
small amount of cement sub-
stance.

This kind of muscular tis-
sue is found arranged around
the blood-vessels and most
of the hollow viscera. The
fibres are variously grouped
in different parts of the body ;
sometimes crowded together
in solid bundles, which are arranged in layers and surrounded
by connective tissue, as in the intestines ; sometimes arranged
in narrow interlacing bundles, as in the bladder ; sometimes
wound in single or double layers around the blood-vessels ; and
again, running in various directions and associated with bands
of connective tissue, they form large compact masses, as in the
uterus.

Fig. 5'.>. — Wave of ('<intr action pass-
ing OVER A Muscular Fibrk of Dytiscus.
Very highly magnified. B, R, portions
of the fibre at rest; C, contracted part;
/, I, intermediate condition.

56

ANATOMY FOR NURSES.

[Chap. VI.

Numerous nerves are supplied to non-striated muscular tissue,
and many blood-vessels.

The contraction of this kind of muscular tissue is much
slower and lasts longer than the contrac-
tion of the striated variety. As a general
rule the muscles of the skeleton are thrown
into contraction only by nervous impulses
reaching them along their nerves ; sponta-
neous contractions, as in a case of "cramps,"
being rare and abnormal. The plain mus-
cular tissue of the internal organs, however,
very often contracts indejiendently of the
central nervous system, and under favor-
able circumstances will continue to do so
after the viscera have been removed from
the body.

The great increase in the muscular tissue of the
uterus during gestation takes place both by elonga-
tion and thickening of the pre-existing fibre-cells,
Fig. 54.— Fibre-cells and also, it is thought, by the development of new

OF Plain Muscular fibre-cells from small granular cells lying in the
TissuK. Highly magni- ^ , , . , . , , ^

gg(j tissue. In the shrinking oi the uterus after par-

turition the fibre-cells diminish to their previous
size ; many of them become filled with fat granules, and eventually many
are, doubtless, removed by al)sorption.

Development of striated muscular tissue. — When the muscular fibres
are about to be formed, the cells set apart for this purpose elongate, and
their nuclei multiply, so that each cell is converted into a long, multi-
nucleated protoplasmic fibre. At first the substance of the fibre is not
striated, but presently it becomes longitudinally striated along one side,
and about the same time a delicate membrane, the sarcolemma, may be
discovered bounding the fibre ; then transverse striation commences, and
gradually extends around the fibre, and, finally, the nuclei take up their
position under the sarcolemma.

Regeneration of muscular tissue. — It was formerly thought that after
removal, by tlie knife, or by disease, muscular tissue was not regenerated,
but that any breach of continuity which might occur in the muscle was filled
up by a growth of connective tissue. It would appear, however, that the
breach is after a certain lapse of time bridged across by muscular substance,
but how the new muscular tissue is formed is not fully understood.

Attachment of muscles to the skeleton. — The muscles are sepa-
rate organs, each muscle having its own sheath of connective
tissue. The connective tissue extends also into the muscle, form-

Plate I. — Forms of Muscles and Tendons. A , adductor of thigh ; B, biceps of
arm; L), deltoid; G, gastrocnemius; P , pronator of fore-arm; P", pectoral; R,
rectus abdominis; R", rectus muscle of thigh; S', serratus magnus of thorax; S",
semi-membranosus of thigh.

57

68 ANATOMY FOR NURSES. [Chap. VI.

ing sheaths for the smaller bundles, connecting and binding the
fibres and bundles together, and conducting and supporting the
blood-vessels and nerves distributed to the muscle fibres.

The muscles vary greatly in shape and size. In the limbs
they are of considerable length, forming more or less elongated
straps ; in the trunk they are broad, flattened, and expanded,
forming the walls of the cavities which they enclose.

They are attached to the bones, cartilages, ligaments, and
skin in various ways, the most common mode of attachment
being by means of tendons. The muscular fibres converge as
they approach their tendinous extremities, and gradually blend
with the fibres of the tendons, the tendons in their turn insert-
ing their fibres into the bones. Sometimes the muscles end in
expanded form in the flat fibrous membranes, called aponeuroses.
Again, in some cases, the muscles are connected with the bones,
cartilages, and skin, without the intervention of tendons or
aponeuroses.

In the description of muscles it is customary to speak of the
attachments of their opposite ends under the names of origin
and insertion, the first term origin being usually applied to the
more fixed attachment ; the second term insertion being applied
to the more movable attachment. The origin is, however,
absolutely fixed in only a very small number of muscles, such
as those of the face, which are attached by one end to the bone,
and by the other to the movable skin. In the greater number,
the muscle can be made to act from either end.

The muscular tissue or flesh forms a large proportion of the
weight of the whole body. The following has been calculated
for a man of one hundred and fifty pounds' weight from the
tables of Liebig: skeleton, twenty-eight pounds; muscles, sixty-
two pounds ; viscera (with skin, fat, blood, etc.), sixty pounds.

The total number of voluntary muscles may be stated at
three hundred and eleven. It is not necessary for us to be able
to distinguish more than a few of the most prominent. We
may conveniently classify these into two groups : —

1. Chief muscles of the head and trunk.

2. Chief muscles of the limbs.

Chief muscles of head, face, neck, and trunk. — The chief muscles
of the head are the occipital and frontal muscles, which, united

Plate II. — Muscles of Face, Head, and Neck. 1, sterno-cleido-mastoid;
10, temporal ; 11, masseter ; 13, 13, occipito-f routalis.

o»

60

ANATOMY FOR NURSES.

[Chap. VI.

together by a thin aponeurosis extending over and covering
the whole of the upper part of the cranium, are usually known
as one muscle, the occipito-frontalis. The frontal portion of this
muscle is the more powerful ; by its contraction the eyebrows

are elevated, the skin of the forehead
thrown into transverse wrinkles, and
the scalp drawn forward.

There are about thirty facial mus-
cles; they are chiefly small, and con-
trol the movements of the eye, nose,
and mouth.

The six muscles which move the
Fig. 55. -Muscles of Right eyeball are the four straight or recti.

Eyeball within the Orbit.

Seen from the front. 21, superior and the twO Oblique, mUSCieS. ihc

rectus ; 22, inferior rectus ; 23, ex- four recti have a common Origin at the

terual rectus ; 24, internal rectus ; _ "^ _

25, superior oblique ; 26, inferior bottom of the Orbit ; they pasS straight

°^^^*^"®' forwards to their insertion into the

eyeball, one, the superior rectus, in the middle line above ; one,
the inferior rectus, opposite it below, and one halfway on each
side, the external and internal recti. The eyeball is completely
imbedded in fat, and these mus-
cles turn it as on a cushion, the
superior rectus inclining the
axis of the eye upwards, the in-
ferior downwards, the external
outwards, the internal inwards.
The two oblique muscles are
both attached on the outer side
of the ball; their action is some-
what complicated, but their
general tendency is to roll the
eyeball on its own axis, and pull
it a little forward and inward.

llie muscles of mastication are the masseter, the temporal, and
tlie external and internal pterygoid. They all have their origin
in the immovable bones of the skull, and are all inserted into
the movable lower jaw. They generally act in concert, bring-
ing the lower teeth forcibly into contact with the upper; they
also move the lower jaw forward upon the upper, and in every
direction necessary to the process of grinding the food.

Fig. 56. — Muscles of Eyeball. Seen
from side. 19, elevator muscle of eyelid ;
22-26, same as in Ficr. 55.

Chap. VI.]

THE MUSCLES.

61

Fig. 57. — Muscles of the Tongue.

The chief muscles connecting the tongue and tongue bone to
the lower jaw are the genio-glossus and stylo-g^lossus. They are
interesting to us from the fact that during general anaesthesia
they, together with the other muscles, become relaxed, and it
is necessary to press the angle
of the lower jaw upwards and
forwards in order to prevent
the tongue from falling back-
wards and obstructing the
larynx.

The most prominent muscle
of the neck is the sterno-cleido-
mastoid. It is named from its
origin and insertion, arising
from part of the sternum and
clavicle, and being inserted
into the mastoid portion of the
temporal bone. This muscle
is easily recognized in thin
persons by its forming a cord-
like prominence obliquely situated along each side of the neck.
It serves as a convenient landmark in locating the great vessels
carrying the blood to and from the head. If one of these
muscles be either abnormally contracted or paralyzed, we get
the deformity called wry neck.

The muscles of the trunk may be arranged in three groups :
(1) muscles of the back; (2) muscles of the thorax; (3) muscles
of the abdomen.

The muscles of the back are disposed in five layers, one be-
neath another. The two largest and most superficial are the
trapezius and tlie latissimus dorsi.

The trapezius arises from the middle of the occipital bone,
from the ligamenfum nuchce, and from the spinous processes of
the last cervical and all the dorsal vertebrae. From this ex-
tended line of origin the fibres converge to their insertion in
the acromion process and spine of the scapula. The latissimus
dorsi arises from the last six dorsal vertebrae, and through the
medium of the lumbar aponeurosis, from the lumbar and sacral
part of the spine and from the crest of the ilium. The fibres
pass upwards and converge into a thick, narrow band, which

62 ANATOMY FOR NURSES. [Chap. VI

winds around and finally terminates in a flat tendon, which is
inserted into the front of the humerus just below its head.

These muscles cover nearly the whole of the back; but as they
act upon the bones of the upper extremity, they are often more
properly reckoned as belonging to the muscles of that region.

The muscles of the thorax are chiefly concerned with the
movements of the ribs during respiration. They are the inter-
costals, subcostals, etc.

The chief bulk of the anterior muscular wall of the chest is
made up of the pectoral muscles, the larger of which arises partly
from the front of the sternum. The fibres converging form
a thick mass, which is inserted by a tendon of considerable
breadth into the upper part of the humerus. As these muscles
move the arm, they are, like the superficial muscles of the back,
usually reckoned among the muscles of the upper extremity.
Covering the pectoral muscles is a superficial fascia (composed
of connective tissue) in which are lodged the mammary glands
and a variable amount of fat.

The muscular walls of the abdomen are mainly formed by
three layers of muscles, the fibres of which run in different
directions, those of the superficial and middle layers being
oblique, and those of the innermost layer being transverse. In
the front of the abdomen these three layers of muscles are
replaced by tendinous expansions or aponeuroses, which meet in
the middle line, the line of union giving rise to a white cord-
like line, the linea alba. On each side of this line the fibres of
a straight muscle, the rectus muscle, extend in a vertical direc-
tion between the tendinous layers. The abdominal muscles
are covered and lined by sheets of fascise, some of which are
very dense and strong, and serve to strengthen weak points in
the muscular walls.

The strongest and most superficial of the abdominal muscles
is the external oblique, the fibres of which, arising from the lower
eight ribs, incline downwards and forwards and terminate in the
broad aponeurosis, which, meeting its fellow of the opposite side
in the linea alba, covers the whole of the front of the abdomen.
The lowest fibres of the aponeurosis are gathered together in
the shape of a thickened band, which extends from the anterior
superior spinous process of the ilium to the pubic bone, and
forms the well-known and important landmark, called from the

Pi»A.TE III,— Muscles of Back. 50, latissimus dorsi ; 51, trapezius ; 52, deltoid

63

64 AKATOMY FOR NURSES. [Chap. VI.

anatomist who first described it, Poupart's ligament. Just
above this ligament, and near the pubic bone, is an oblique
opening which transmits the spermatic cord in the male, or the
round ligament in the female. This opening, called the ex-
ternal abdominal ring, is usually the seat of hernia.

The internal oblique muscle lies just beneath the external
oblique. Its fibres run upwards and forwards, and end for the
most part in a broad aponeurosis. At the outer border of the
rectus muscle this aponeurosis divides into two layers, one passing
before, the other behind, that muscle: they reunite at its inner
border in the linea alba, and thus form a sheath for the rectus.

The transversalis muscle lies beneath the internal oblique;
the greater part of its fibres have a horizontal direction, and
extend forward to a broad aponeurosis in front.

The rectus is a long, flat muscle, consisting of vertical fibres
situated at the fore part of the abdomen, and enclosed in the
fibrous sheath formed by the aponeurosis of the internal oblique.
It arises from the pubic bone, and is inserted into the cartilages
of the fifth, sixth, and seventh ribs; it is separated from the
muscle of the other side by a narrow interval which is occupied
by the linea alba.

The linea alba, or white line, is a tendinous band formed by
the union of the aponeuroses of the two oblique and transverse
muscles, the tendinous fibres crossing one another from side to
side. It extends perpendicularly, in the middle line, from the
ensiform portion of the sternum to the pubis. It is a little
broader above than below, and a little below the middle it is
widened into a flat circular space, in the centre of which is sit-
uated the cicatrix of the umbilicus.

The abdominal muscles perform a threefold action. When
acting from both pelvis and thorax as fixed points they com-
press the abdominal viscera by constricting the cavity of the
abdomen, in which action they are much assisted by the descent
of the diaphragm. (See below.) By these means they give
assistance in expelling the foetus from the uterus, the faeces
from the rectum, tlie urine from the bladder, and its contents
from the stomach in vomiting. When the pelvis and spine are
the fixed points the abdominal muscles raise the diaphragm by
pressing on the abdominal viscera, draw down the ribs, compress
the lower part of the thorax, and assist in expiration. Again,

Plate IV. - Muscles of Chest and Ahdomen. 55, pectoral muscle • 44 sermtus
magnus ; M, external oblique ; :^5, rectus abdo.uinis, the external layer of ap^neuiot^
sheath IS removed : 38, linea alba ; 40, aponeurosis. aponeurotic

65

66 ANATOMY FOR NURSES. [Chap. VI.

if the trunk and arms are the fixed point, the muscles draw the
pelvis upwards as a preparatory step to the elevation of the
lower limbs in the action of climbing.

The diaphragm is a thin musculo-fibrous partition, placed
obliquely between the abdominal and tb.oracic cavities. It is
fan-shaped, and consists of muscle fibres arising from the whole
of the internal circumference of the thorax, and of an aponeu-
rotic tendon, shaped somewhat like a trefoil leaf, into which
the muscle fibres are inserted. (^Vide Plate V, page 121, for
illustration of diaphragm.) It has three large openings for
the passage of the aorta, the large artery of the body, the in-
ferior vena cava, one of the largest veins of the body, and the
oesophagus or gullet ; it has also some smaller o^^enings, of
less importance, for the passage of blood-vessels, nerves, etc.
The upper or thoracic surface of the diaphragm is highly
arched ; the heart is supported by the central tendinous por-
tion of the arch, the right and left lungs by the lateral portions,
the right portion of the arch being slightly higher on the right
than on the left side. The lower or under surface of the dia-
phragm is deeply concave, and covers the liver, stomach, pan-
creas, spleen, and kidneys.

The action of the diaphragm modifies considerably the size
of the chest, and the position of the thoracic and abdominal
viscera, and it is essentially the great respiratory muscle of the
body. The mechanical act of respiration consists of two sets
of movements; viz. those of inspiration and of expiration, in
which air is successively drawn into the lungs and expelled
from them by the alternate increase and diminution of the
thoracic cavity. The changes in the capacity of the thorax are
efifected by the expansion and contraction of its lateral walls,
called costal respiration, and by the depression and elevation
of the floor of the cavity, through contraction and relaxation
of the diaphragm, called diaphragmatic or abdominal respiration.
These two movements are normally combined in the act of
respiration, but in different circumstances one of them may be
employed more than the other. Abdominal respiration pre-
dominates in men and in children, and costal respiration in
women.i jj^ ^l^g o^^^ of inspiration the diaphragm contracts,

1 The costal respiration of women is abnormal, and has been shown to be
due to their mode of dress.

Chap. VI.]

THE MUSCLES.

67

and in contracting flattens out and descends, the abdominal
viscera are pressed downwards, and the thorax is expanded
vertically. In normal and quiet expiration the diminution of
the capacity of the chest is
mainly due to the return of
the walls of the chest to the
condition of rest, in conse-
quence of their own elastic
reaction, and of the elasticity
and weight of the viscera dis-
placed by inspiration. In more
forcible acts of expiration, and
in efforts of expulsion from the
thoracic and abdominal cavi-
ties, all the muscles which tend
to depress the ribs, and those
which compress the abdominal
cavity, concur in powerful ac-
tion to empty the lungs, to fix
the trunk, and to expel the con-
tents of the abdominal viscera.
Thus the diaphragm is an ex-
pulsive as well as the chief
respiratory muscle of the body.
Muscles of the upper extrem-
ity. — A certain number of
muscles situated superficially
on the trunk pass to the bones
of the shoulder and of the
arm, so as to attach the upper
limbs to the trunk. Of these,
the two superficial muscles we
have mentioned as covering the
back, the trapezius and latis-
simus dorsi, and the pectoral
muscles covering the front of Fig. 58. — Muscles of Arm. 58, biceps;

KQ tl'icGDS

the chest, are the chief. The

most prominent muscles found in the upper limbs are : —

Deltoid. Triceps. Supinators. Extensors.

Biceps. Pronators. Flexors.

68

ANATOMY FOR NURSES.

[Chap. VI.

The deltoid is a coarse triangu-
larmuscle which gives the rounded
outline to the shoulder; it extends
downwards and is inserted into
the middle of the sliaft of tlie
humerus. It raises the arm from
the side so as to bring it at right
angles to the trunk.

The biceps is a long fusiform
muscle, occupying the whole of
the anterior surface of the arm;
it is divided above into two por-
tions or heads, from which cir-
cumstance it has received its
name. It arises by these two
heads from the scapula, and is
inserted into the radius. It flexes
and supinates the forearm on the
arm.

The triceps is situated on the
back of the arm, extending the
whole length of the posterior sur-
face of the humerus. It is of
large size, and divided above into
three heads; hence its name. It
is inserted into the ulna. It is
the great extensor muscle of the
forearm, and is the direct antago-
nist of the biceps.

The muscles covering the fore-
arm are disposed in groups, the
pronators and flexors being placed
on the front and inner part of the
forearm, and the supinators and
extensors on the outer side and
back of the forearm: they antag-
onize one another. The prona-
FiG. 59. — Muscles in Fnofir of i r i i j

Forearm. (52, pronator teres ; 63, (55, torS turn the palm ot the hand

^^ I'!' i'^^^^'"!' 70, .supinator lonsus; fo^vvards, and, when the elbow

71, 77, 78, extensors; a, annular liga- '

ment. is flexed, downwards or prone.

Chap. VI.] THE MUSCLES. 69

The supinators turn the palm of the hand backwards, and,
when the elbow is flexed, upwards or into the supine position.
Tire flexors and extensors have long tendons, some of which
are inserted into the bones of the wrist, and some into the bones
of the fingers: they serve to flex and extend the wrist and
fingers.

Muscles of the lower extremity. — These include the muscles
of hip, thigh, leg, and foot. The most important of these are : —

Glutei or gluteal muscles. Tibialis anticus. Soleus.

Posterior femoral. Extensors. Flexors.

Anterior femoral. Peroneal. Tibialis posticus.

Internal femoral. Gastrocnemius.

If we compare the muscles of the shoulder and arm with
those of the hip and leg, we shall see that the anterior muscles
of the former correspond roughly with the posterior muscles
of the latter, the muscles of the hip and leg, however, being
larger and coarser in texture than those of the shoulder and
arm.

The glutei, or three gluteal muscles, form the chief prominence
of the buttock. They are coarse in texture, and are largely
concerned in supporting the trunk upon the head of the femur,
and in bringing the body into the erect position when the
trunk is bent forwards upon the thigh.

The posterior femoral or hamstring muscles cover the back of
the thigh. There are three of these muscles, — the biceps, the
semitendinosus, and the semimembranosus. The chief of these
is the biceps, and is somewhat analogous to the biceps covering
the front of the arm. The action of the hamstring muscles is
to flex the knee and to extend the hip.

The principal anterior femoral muscles are the quadriceps and
sartorius. The quadriceps covers the front of the thigh, and
is analogous to the triceps covering the back of the arm; it is
the great extensor of the leg; it also flexes the hip, and antago-
nizes the action of the hamstring muscles. The sartorius, or
tailor's muscle, is a long, ribbon-like muscle, the longest in the
body: it crosses the thigh obliquely from its origin in the ilium
to its insertion in the tibia. It was formerly supposed to be
the muscle principally concerned in producing the posture
assumed by the tailor in sitting cross-legged, and hence its name.

Fig. go. — Muscles of thb
Thigh. 46, gluteus maximus;
36, 35, posterior femoral; 33, sar-
torius; 27, 26, internal femoral
or adductor.

I iT' »'|

Fig. 61. — Muscles of Leg.
Superficial View of the
Calf. 22, tendo Aehillis : 21,
gastrocnemius ; 18, soleus ; 16,
peroneal muscles.

Chap. VI.] THE MUSCLES. 71

The internal femoral or adductor muscles occupy the internal
portion of the thigh: they are all adductors of the thigh.

The tibialis anticus, the extensors, and the peroneal muscles
cover the front and outer side of the leg. The gastrocnemius
and the soleus, the flexors, and the tibialis posticus cover the
back of the leg. The action of the tibialis anticus and of one
of the three peroneal muscles is to Ilex the ankle, while the
action of the tibialis posticus and the other peroneal muscles is
to extend the ankle. The flexors and extensors act on the toes.

The gastrocnemius and soleus form the calf of the leg ; they
are inserted into a common tendon, the tendo Achillis, which
is the thickest and strongest tendon in the body, and is inserted
into the os calcis, or heel bone. The muscles of the calf possess
considerable power, and are constantly called into use in stand-
ing, walking, dancing, and leaping; hence the large size they
usually present.

The sole of the foot is protected by a fascia, called the plantar
fascia, which is very strong, and the densest of all the fibrous
membranes.

Most of the muscles are covered closely by sheets of fibrous
connective tissue (fascice), and this deep layer of tissue forms a
nearly continuous covering beneath the superficial or subcu-
taneous layer of areolar connective tissue, which in a former
chapter we saw to be continuous over the whole of the body.
Parts of the deep fasciae in the vicinity
of the larger joints, as at the wrist and
ankle, become blended into tight trans- Mz'.

verse bands which serve to hold the
tendons close to the bones, and receive
the name of annular ligaments. ^^^^W-- ; j

Relation of muscles to nerves. — The
function of the muscles is to contract \\^

so that their two ends are drawn to- ^r^ \ ]

gether, and a movement is thus pro- J^^^^^^~-['l

duced which by various systems of ^^^^Ssirr

levers can be converted into the par- fig. 62. — Nerve ending in
ticular form of motion required. For ^iZlT ^Zi;^::.^^^^.

example, the contraction of the mUS- torial ending of the axone, IS

cles of the calf draws the heel upward, ^^^^ ^' eways.

and in this way causes the whole body to be elevated on the toes.

72

ANATOMY FOR NURSES.

[Chap. VI.

Ill order to bring about a muscular contraction the muscle
must be stimulated. The way in which a muscle is normally
stimulated is through its nerve, which conducts the nerve
impulses from the central nervous system to the muscle fibres.
Arriving at the latter, the nerve impulses bring about the
complex chemical changes upon which the contraction of the
muscle depends. When the nerve impulses cease, the muscle
relaxes again.

TABLE OF CHIEF MUSCLES.

Occipito-frontalis. Head.

Temporal, i l

Masseter. 1- Muscles of Mastication.

Pterygoids. J

Exterior rectus.

Interior rectus. I ;■ Face.

Superior rectus.

Inferior rectus.

Superior oblique. |

Inferior oblique. J

Genio-glossus. 1
Stylo-glossus. J

Stern o-cleido-mastoid.
Intercostals. 1

Subcostals. I

Levatores costarum. \ Thorax.
Pectoral major. I

Pectoral minor. J

Diaphragm. Between Thorax and Abdomen.

Obliquus externus abdominis. 1

1

}■ Muscles of the Eye.

J
Tongue.

Neck.

Obliquus internus abdominis.
Transversalis abdominis.
Rectus abdominis.
Trapezius. | ^^^^

Latissimus dorsi. j

Deltoid. Shoulder.

> Abdomen.

Arm.

Biceps flexor cubiti. |
Triceps extensor cubiti. J

Pronators (2).

Supinators (2).

Flexors of the wrist (2).

Flexors of fingers and thumb (3)

Extensors of wrist (3).

Extensors of fingers and thumbs (6).

Forearm.

Chap. VI.]

THE MUSCLES

73

r Maximus. i
Glutei -1 Medius. 1- Hip.
I Minimus. J

Posterior femoral

Anterior femoral

Internal femoral

( Biceps flexor cruris.

j Semitendinosus.

I- Semimembranosus.

[ Quadriceps extensor cruris.

[ Sartorius.

I xVdductor longus.

J, Adductor brevis.

I

I Adductor magnus.

Thigh.

Tibialis anticus.

Tibialis posticus.

Peroneal (3).

Gastrocnemius.

Soleus.

Flexors of toes (4).

Extensors of toes (4).

Leg.

CHAPTER VII.

THE NEURONE OR NERVE-CELL. — ANATOMY OF THE NER-
VOUS SYSTEM. — PHYSIOLOGY OF THE NERVOUS SYSTEM ;
REFLEXES.

The neurone. — Just as the anatomical and physiological unit

of the muscular tissue is the muscle-cell, or as it is often called,
the muscle-fibre, so the unit of the ner-
vous system is the nerve-cell, or neurone.
Thus the structure of the nervous system
depends upon the position and relations
of the neurones which compose it; and
the activity of this system as a whole is
the sum of the activities of its neurones.

Although the neurones or nerve-cells
vary considerably in size and in form,
there are certain structural characteristics
which they all possess in common. The
typical neurone consists of a small mass
of granular cytoplasm which surrounds
a large vesicular nucleus. From this
cytoplasm arise processes of varying
length and form. The latter are of two
kinds. Usually in the first variety (den-
drones) the cytoplasm is granular and
closely resembles that surrounding the
nucleus ; they are usually short, and soon
after their origin break up into numerous
branches. In the second variety (axones)
the processes are not granular, but show

fine longitudinal striations ; they are often of great length and

branch only near their termination.

The nucleus, together with the cytoplasm surrounding it, is

often called the " cell-body," so we may regard the neurone, or

74

Fig. 63. — Diagram of
A Neurone. A, axone
arising from the cell-body
and branching at its ter-
mination ; D, dendrones ;
C and N, cell-body com-
posed of C, cytoplasm, and
N, nucleus.

Chap. VII.] THE NERVOUS SYSTEM. 75

nerve-cell, as being made up of a cell-body and its processes.
Inasmuch as the processes arise from the cell-body, the latter
is often spoken of as the " origin " of the fibres. By the origin
of a fibre, then, we mean the cell-body from which that fibre
springs.

Like the muscle-cell the neurone is irritable and responds to
stimuli, but its mode of response is quite different from that of
the muscle. If a muscle be stimulated, changes occur in its sub-
stance, which changes result in the contraction of the muscle.
If, however, we stimulate a neurone, we find that although there
is no visible alteration in the part stimulated, yet a change in
the substance of the neurone takes place which passes along
throughout the entire neurone, and even to adjacent neurones,
and so on from neurone to neurone often for a great distance.
This invisible change which sweeps like a wave along the
neurone is called the " nerve-impulse " ; and the fundameyital
property of the neurone is to conduct nerve-impulses.

We may roughly compare the passage of a nerve-impulse along
a neurone with the passage of the electrical current along a wire.

The result of the stimulus depends not upon any peculiarity
of the neurone itself, but upon its anatomical relations to other
neurones, and to other tissues of the body. Thus, if impulses
be conducted to a muscle-fibre, the muscle contracts ; but if
they be conducted to the brain, we have as the result a con-
scious sensation.

Under normal conditions an impulse always passes along a
neurone in the same direction, travelling towards the cell-body
by the dendrones, and away from it by the axones. Hence the
dendrones may be regarded as receiving processes ; the axones
as transmitting processes.

The nervous system of man and of the higher animals has
been divided into the following parts : —

1

Nerves

Tap a J ^P^°^^ \ Peripheral Nervous System.

1 Sympathetic J

Spinal Cord i

C Medulla oblongata I Cerebro- spinal Axis,

■o I Pons Varolii v or

] Cerebellum I Central Nervous System.

I Cerebrum j

76

ANATOMY FOR NURSES.

[Chap. VII.

Nerves. — Nerves, or as they are sometimes called, nerve-
trunks, are whitish cords which arise from the cerebro-spinal
axis, and, branching as they go, are distributed to all parts of
the body. Every organ and tissue has thus its supply of nerves
connecting it with the brain or spinal cord (Fig. 64).

If we examine a nerve
under the microscope, we
find that it is composed
of nerve-fibres, each fibre
being composed of an
axone enclosed in a sheath.
These fibres are of two
kinds, the medullated and
the non -medullated. The
former consists of a central
core, — the axone, — sur-
rounded by a thick sheath
of white fatty substance
forming what is known
as the medullary sheath.
Surrounding this is a
second sheath, the neuri-
lemma, which is very deli-
cate and has numerous
nuclei situated along its
innersurface. The second
variety of nerve-fibres
(the non-medullated)
have a similar structure
except that in them the
medidlary sheath is ab-
sent.^

Between the nerve-
fibres is a small amount
of connective tissue which
serves not only to bind the fibres together into bundles, or
funiculi^ but also to carry to or from the fibres the blood-
vessels and the lymphatics necessary for their nutrition.

1 In the white matter of the brain and spinal cord the fibres are without a
neurilemma, and in the gray matter the medullary sheath is also lacking.

Fig. 64. — Diagram illustrating the Gen-
eral Arrangement of the Cerebro-spinal

System.

Chap. VII.]

THE NERVOUS SYSTEM.

77

Connective tissue also surrounds these bundles in the form of a
sheath. The smaller nerves may consist of a single funiculus;
but the larger nerve-trunks contain several funiculi united by
connective tissue and surrounded by a common sheath of the
same material.

Although the nerves branch frequently throughout their
course, and these branches often meet and fuse with one
another, or with the branches of other nerves, yet each nerve-
fibre always remains quite distinct, never branching until it
reaches its termination, and never uniting with other nerve-
fibres. The nerve-trunk is thus merely an association of indi-
vidual fibres which proceed together towards the periphery.
At any time one or more indi-
vidual fibres may leave the
main body and pass to their
terminations, or may join an-
other nerve; but in any case
each fibre always remains per-
fectly distinct.

Physiologically speaking,
nerve-fibres are of two kinds, Fig. <;5. — NERVE-FiBKiLs. «. ncrve-

. 1 • 1 n • fibre, showing complete interruption of

those which normally transmit the white substance ; b, another norve-

impulses from the central ner- ^^'''' ^'^^"^ nucleus, in both these nerve-

^ . fibres the white substance is stained black

VOUS system to the periphery with osmic acid, and the axoue is seen run-

(the effereyit or mo^or fibres), "ing as an uninterrupted strand through

^ JJ ^' the centre of fibre, c, ordinary nerve-

and those which normally fibre unstained ; d, e, smaller nerve-fibre;

, -i • 1 • .1 /■, varicose nerve-fibre ; «, non-medullated

transmit impulses m the re- nerve-fibres.

verse direction (the afferent or

sensory fibres). Hence nerves are spoken of as motor, sensory,

or mixed ; according as they contain motor (efferent), sensory

(afferent), or both kinds of fibres.

The cell-bodies, from which the axones of the peripheral
nerve-fibres arise, are not scattered promiscuously throughout
the body, but are gathered together in certain definite regions
or groups. These form the gray matter of the cerebro-spinal
axis and the ganglia.

The ganglia. — A ganglion is a small collection of cell-bodies
connected by means of nerve-fibres (axones or dendrones) with
other ganglia, and with the central nervous system. The
ganglia may be divided into two large classes, the spinal and

78

ANATOMY FOR NURSES.

[Chap. VIL

the sympathetic ganglia. ^ (The spinal ganglia will be con-
sidered later.)

The sympathetic system. — The sympathetic system consists of
a double chain of ganglia, placed on each side of the spinal
column, and united to each other by longitudinal filaments.
The fibres that arise from them are mostly of the non-medul-
lated variety.

Fig. 66. — Section of the Internal Saphenous Nerve. Stained in osmic
acid and subsequently hardened in alcoliul. Drawn as seen under a very low magni-
fying power. (G. A. S.) ep, epineurium, or general sheath of the nerve, consisting
of connective tissue separated by cleft-like areolis, which appear as a network of
clear lines, with here and there fat-cells,/, /, and blood-vessels, v :, per, perineurium,
or particular sheath of funiculus ; end, endoneuriuni, or connective tissue within
funiculus, embedded in which are seen the cut ends of the medullated nerve-fibres.
The fat-cells and the nerve-fibres are darkly stained by the osmic acid.

These ganglia and nerves do not form an independent ner-
vous system, for each ganglion is connected by motor and sen-
sory fibres with the cerebral system. The sympathetic nerves
are distributed to the viscera and blood-vessels, of which the
movements are involuntary, and the general sensibility obtuse.
They form networks or plexuses upon the heart, about the

1 Isolated ganglia are also found in the course of some of the cranial nerves,
and in some of the organs of special sense.

Chap. VII.]

THE NERVOUS SYSTEM.

79

stomach, and other viscera in the trunk ; they also enter the
cranium, send branches to the organs of special sense, and,
in particular, influence
the pupil of the eye.
Their most important
distribution, however,
is in connection with
the blood-vessels.
They form plexuses
around the vessels,
especially the arteries,
and send fibres to ter-
minate in the involun-
tary muscular tissue
of which the walls of
these tubes are largely
composed. The nerves
thus distributed are
called " vaso-motor "
nerves.

In the sympathetic
ganglia the relation of
the neurones is such
that each nerve-fibre,
arriving at the gan-
glion from the spinal
cord, is brought into
contact with several
other neurones which
lie wholly in the sym-
pathetic system. Thus
an efferent impulse,
passing along an axone
from the cord, may
pass to the dendrones
of several sympathetic
cells, and then by their Fig. 67. — General View of the Sympathetic

axonps to thp -smnrifli System. 1, 2, 3, cervical ganglia ; 4, 1st thoracic
axones to ine smootn ganglion; 5, Ist lumbar ganglion; 6, 7, sacral gan-
muscles of the viscera, glion ; 9, 9, cardiac nerves ; 13, branch of pneumo-
, • •! T gastric nerve ending in seini-lunar ganglion; 14,

or to sinnlar endings, epigastric plexus.

80

ANATOMY FOR NURSES.

[Chap. VII.

As a result the impulse is distributed over an area supplied by
several sympathetic neurones. Similarly, sensory impulses,
originating in any part of the area supplied by a particular
group of sympathetic neurones, may be transmitted to a single
afferent dendrone which connects with the axones of several
sympathetic cells. These relations can best be understood by
studying the accompanying diagram (Fig. 68).

The spinal cord and spinal nerves. — The spinal cord is a
column of gray and white soft substance, extending from the
top of the spinal canal, where it is continuous with the brain, to
about the second lumbar vertebra, where it tapers off into a fine

thread. Before its
termination it gives
off a number of
fibres which form a
tail-like expansion,
called the eaiida
equina.

Like the brain,
the spinal cord is
protected and nour-
ished by three
membranes. These
membranes have
tlie same names and
practically exercise
the same functions
as those enveloping
the brain (for description of which see page 85). Tlie outer
membrane is not attached to the walls of the spinal canal, being
separated from them by a certain quantity of areolar and
adipose tissue, and a network of veins. Therefore, the spinal
cord does not fit closely into the spinal canal, as the brain does
in the cranial cavity, but is, as it were, suspended within it.
It diminishes slightly in size from above downwards, with the
exception of presenting two enlargements in the cervical and
dorsal regions, where the nerves are given off to the arms and
legs respectively. It is usually from sixteen to seventeen
inches (406 to 432 mm.) long, and has an average diameter of
three-fourths of an inch (10 mm.). The spinal cord is almost

Fig. 68. — Diagram showing the Relation of

THE CeREBRO-SpINAL TO THE SYMPATHETIC NEU-
RONES. A, a medullated fibre, axone, or dendrone,
coming from cerebro-spinal system and dividing into
numerous branches on reaching a sympathetic ganglion.
These branches connect with those of the cells, B, B, in
the ganglion, and these cells send their non-meduUated
fibres, axones, or deudrones, to supply the viscera,
C, C, C, C.

Chap. VIL]

THE NERVOUS SYSTEM.

81

completely divided into lateral
halves by an anterior and pos-
terior fissure, the anterior fis-
sure dividing it in the middle
line in front, and the posterior
fissure, in the middle line be-
hind. In consequence of the
presence of these fissures, only
a narrow bridge of the sub-
stance of the cord connects its
two halves, and this bridge is
traversed throughout its en-
tire length by a minute central
canal, — the canalis centralis.
On making a transverse section
of the spinal cord, the gray
matter is seen to be arranged
in each half in the form of a
half-moon or crescent, with one
end bigger than the other, and
with the concave side turned
outwards. The convex sides of
the gray matter in each half
approach one another, and are
joined by the isthmus or bridge
which contains the central
canal. The tips of each cres-
cent are called its horns or
cornua, the front or ventral
horns being thicker and larger
than the dorsal. The white
matter of the cord is arranged
around and between the gray
matter, the proportion of gray
and white matter varying in
different regions of the cord.
The white matter, as in the
brain, is composed of medul-
lated nerves, and the gray
matter of cell-bodies and fine

\Cocc.

Fig. 69. — Base of Brain, Spinal
Cord, and Spinal Nerves. — V, 5th
nerve ; VI, 6th nerve ; VII, a, facial nerve,
b, auditory nerve; VlII, piieunio-gastric
nerve ; VIII, a, glosso-pharyngeal, b,
spinal accessory ; IX, hypoglossal ; c^^c',
cervical nerve roots ; D^D^'^, dorsal nerve
roots ; U—Ip, lumbar nerve roots; S^, S^,
4th and 5th sacral nerves ; C'occ, coccyg-
eal nerves; i?. P., brachial plexus; L.P.,
lumbar plexus ; S. P., sacral plexus; Sa,
b, c, cervical sympathetic ganglia.

82

ANATOMY FOR NURSES.

[Chap. VII.

gray fibres (naked axones and dendrones), all held together
and supported by delicate connective tissue. The majority
of the raedullated fibres run in a longitudinal direction. There
is no real division between the brain and spinal cord, the brain
being built upon the cord, and together they form the great

Fia. 70. — Transverse Sections of the Spinal Cord at Different Levels.
(Gowers.) (Twice the natural size.)

nerve-centre or axis — the cerebro-spinal — which, by means
of the cranial and spinal nerves, is placed in connection with all
parts of the body.

The spinal nerves. — There are thirty-one pairs of spinal
nerves, arranged in the following groups, and named from
the regions through which they pass. They are : —

Chap. VII.]

THE NERVOUS SYSTEM.

83

Cervical

Dorsal

Lumbar

Sacral

Coccygeal

6 pairs
12 "
5 "
5 "

1 pair

^^hr^

The spinal nerves pass out of the spinal canal through the
intervertebral foramina, the openings between the vertebroe
spoken of in the lesson on the bones of the spine.

Each spinal nerve has two roots, a ventral root and a dorsal
root. The fibres connected with these two roots are collected
into one bundle, and
form one nerve just — ■ ^ '^

before leaving the canal
through the interverte-
bral openings. Before
joining to form a com-
mon trunk, the fibres
connected with the dorsal
root present an enlarge-
ment, this enlargement
being due to a ganglion,
or small nerve-centre.
The fibres of the ventral
root arise from the gray
matter in the ventral
horn, and are direct pro-
longations from the cell-
bodies there. The fibres
of the dorsal root, on the other hand, arise from the cell-bodies
in the ganglion, and ^row into the nerve-centres forming the gray
matter in the dorsal horn. All the fibres growing from the ven-
tral root are efferent fibres, and convey nervous impulses from
the spinal cord to the periphery. The fibres growing into the
dorsal root are afferent fibres, and convey nervous impulses from
the periphery to the spinal cord.

It should be borne in mind that the dorsal roots contain only
sensory fibres, and that these fibres always have their origin
outside of the cord (i,.e. in the spinal ganglia), while the ventral
roots contain only motor fibres, and these have their origin
within the central nervous system. This is true also of the

Fig. 71. — Diagram showing Anatomy of
THE Spinal Nerve Roots and Adjacent
Parts. G., gray matter of the spinal cord; W.,
white matter of the same; D.H., dorsal horn of
gray matter; F.//., ventral horn of gray matter ;
D.R., dorsal root of spinal nerve; Sp. ^., spinal
ganglion ; V.R., ventral root of spinal nerve ; Sp. N.,
spinal nerve; i^c, communicating branch {ramus
comniunicaus) ; S.G., sympathetic ganglion.

84

ANATOMY FOR NURSES.

[Chap. VII.

cranial nerves, except that in these either one root or the other
is often entirely lacking.

The relations of the roots, fibres, and so forth, can be best
understood from a study of the accompanying diagrams (Figs.
71, 72).

Degeneration and regeneration of nerves. — Since, as has been stated
in Chapter 1., the nucleus is essential for the nutrition of the whole cell, it
follows that if the processes of a neurone are cut off, they will suffer from
malnutrition and die. If, for instance, a spinal nerve be cut, all the periph-
eral part will die, since the fibres composing it have been cut off from
their cell-bodies situated in the cord, or in the spinal ganglia. The divided
ends of a nerve that has been cut across readily reunite by cicatricial
tissue, — that is to say, the connective tissue framework unites, — but the

S.E.

Fig. 72. — Diaoram showing Relation of Neurones composing the Spinal
Nerve-koots with Adjacent Nervous Structures. S.E., seusory epithelium
connected by a sensory neurone with spinal cord ; ^'.3/., striated muscle receiving the
axons from a motor-cell in the ventral horn of the gray matter in the cord ; Sp. F.,
spinal fibres, medullat«d, sensory, and the motor, pas.sing to the sympathetic gan-
glion where they connect with the sympathetic neurones; S.F., S.F., non-meduUated
fibres from the sympathetic neurones passing to the viscera, the axoues going to the
plain muscle {P.M.), the dendrones to the sensory endings (S.E.).

cut ends of the fibres themselves do not unite. On the contrary, the periph-
eral or severed portion of the nerve begins to degenerate, the medullary
sheath breaks up into a mass of fatty molecules and is gradually absorbed,
and finally the axone also disappears. In regeneration, the new fibres grow
afre.sh from the axones of the central end of the severed nerve-trunk, and
penetrating into the peripheral end of the trunk, grow along this as the
axone of the new nerve, each axone becoming after a time surrounded with
a medullary sheath. Restoration of function in the nerve may not occur
for several months, during which time it is presumed the new nerve-fibres are
slowly finding their way along the course of those which have been destroyed.

Chap. VIL] THE NERVOUS SYSTEM. 85

Brain and cranial nerves. — The brain, the most complex and
largest mass of nervous tissue in the body, is contained in the
complete bony cavity formed by the bones of the cranium. It
is covered by three membranes (also named meninges), — the
dura mater, pia mater, and arachnoid.

The dura mater, a dense membrane of fibrous connective tissue,
lines the bones of the skull, foi'ming their internal periosteum,
and covers the brain. It sends numerous j)rolongations in-
wards for the support and protection of the different parts of
the brain ; it also forms sheaths for the nerves passing out of
the skull. It may be called the protective membrane.

The pia mater is a delicate membrane of connective tissue,
containing an exceedingly abundant network of blood and
lymph vessels. It dips down into all the crevices and depres-
sions of the brain, carrying the blood-vessels which go to every
part. It may be called the vascular or nutritive membrane.

The arachnoid is a delicate membrane which is placed outside
the pia mater. It passes over the various eminences and de-
pressions on the surface of the brain, and does not dip down
into them like the pia mater. Beneath it, between it and the
pia mater, is space (sub-arachnoid space) in which is a certain
amount of fluid. The sub-arachnoid space at the base of the
brain is of considerable size, and contains a large amount of
this clear limpid fluid, called the cerebro-spinal fluid. This
fluid probably acts as a sort of protective water-cushion to the
delicate nervous structure, and prevents the effects of concus-
sions communicated from without.

The brain is a semi-soft mass of white and gray matter.
The white matter consists of very small, medullated nerve-
fibres, running in various directions, and supported by a deli-
cate connective tissue framework. The gray matter consists
of cells and fine gray fibres, also supported by connective
tissue.

The brain is divided into four principal parts : the cerebrum,
the cerebellum, the pons Varolii, and the medulla oblongata.

The medulla oblongata is continuous with the spinal cord,
which, on passing into the cranial cavity through the foramen
magnum, widens into an oblong-shaped mass. It is directed
backwards and downwards, its anterior surface resting on a
groove in the occipital bone, and its posterior surface forming

86

ANATOMY FOR NURSES.

[Chap. VIL

the floor of a cavity between the two halves or hemispheres of
the cerebellum. The cavity, called the fourth ventricle, is
an expanded continuation of a tiny central canal which runs
throughout the w^hole length of the spinal cord.

The cerebellum, or little brain, overhangs the fourth ventricle.
It is of a flattened oblong shape, and measures from three and a
half inches to four inclies (89 to 102 mm.) transversely, and
from two to two and a half inches (51 to 63 mm.) from before
backwards. It is divided in the middle line into two halves

Fig. 73. — The Base of the Brain. 1, longitudinal fissure; 2, 2, anterior lobes
of cerebrum; 3, olfactory bulb; 7, optic commissure; 9, 3d nerve; 11, 4th nerve;
13, 5th nerve; 14, crura cerebri; 15, (ith nerve; Iti, pons Varolii; 17, 7th nerve ; 19,
8th nerve; 20, medulla oblongata; 21, 9th nerve; 23, 10th nerve; 25, 11th nerve;
27, 12th nerve; 28, 29, 30, 31, 32, cerebellum.

or hemispheres by a central depression, each half being sub-
divided by fissures into smaller portions or lobes. The surface
of the cerebellum is traversed by numerous curves or furrows,
which vary in depth. In the medulla oblongata, the gray
matter is placed in the interior, and the white on the exterior ;
in the cerebellum, the gray is on the outside, and the white
within.

The pons Varolii, or bridge of Varolius, lies in front of the
medulla oblongata. It consists of alternate layers of transverse

Chap. VII.] THE NERVOUS SYSTEM. 87

and longitudinal white fibres, intermixed with gray matter.
The transverse fibres come mainly from the cerebellum, and
serve to join its two halves. The longitudinal fibres come from
the medulla oblongata. This bridge is a bond of union between
the cerebrum, cerebellum, and medulla oblongata.

The cerebrum is by far the largest part of the brain. It is
egg-shaped or ovoidal, and fills the whole of the upper portion
of the skull. It is almost completely divided by the median
fissure into two hemispheres, the two halves, however, being
connected in the centre by a broad transverse band of white
fibres, called the corpus callosum. Each half is subdivided into
lobes.

The longitudinal fibres of the medulla oblongata, passing
through the pons Varolii, become visible in front of the bridge
as two broad, diverging bundles. These two bundles form what
are called the crura cerebri, or pillars of the brain, and are situ-
ated on the under surface of each hemisphere. Between the
crura cerebri is a narrow passage (aqueduct of Silvius) lead-
ing from the fourth ventricle into a smaller cavity called the
third ventricle. In each side wall of the third ventricle is an
opening (foramen of Monro) which leads into two large cavi-
ties, the lateral ventricles, and which occupy the centre of each
half of the cerebrum. (It will be seen from the above descrip-
tion that the cavities in the centre of the brain are continuous
with the central canal in the spinal cord, and also that fibres
from the cord pass into the centre of the cerebrum.) Forming
the floors of the ventricles, lodged in the crura cerebri, and
scattered in their neighbourhood, are irregularly shaped masses
of gray matter, intricately connected with one another and with
the gray matter in the medulla oblongata. The surface of the
cerebral hemispheres is folded, the folds or convolutions being
deeper and more numerous in some brains than others ; the
whole of the convoluted surface is composed of gray matter,
i.e. of cell-bodies and naked processes.

The whole brain appears to consist of a number of isolated
masses of gray matter — some large, some small — connected
together by a multitude of meduUated fibres (white matter)
arranged in perplexing intimacy. But a general arrangement
may be recognized. The numerous masses of gray matter in
the interior of the brain may be looked upon as forming a more

88 ANATOMY FOR NURSES. [Chap. A^I.

or less continuous column, and as forming the core of the cen-
tral nervous system, while around it are built up the great
mass of the cerebrum and the smaller mass of the cerebellum.
This central core is connected by various bundles of fibres with
the spinal cord, besides being, as it were, a continuation of the
gray matter in tlie centre of the cord. It is also connected at
its upper end, by numberless fibres, to the gray matter on the
surface of the cerebrum.

The average weight of the brain in the male is 49| oz. (1403
grammes)^; in the female, 44 oz. (1247 grammes). It appears
that the weight of the brain increases rapidly up to the seventh
year, more slowly to between sixteen and twenty, and still more
slowly to between thirty and forty, when it reaches its maxi-
mum. Beyond this age the brain diminishes slowly in weight,
about an ounce every ten years. The size of the brain bears a
general relation to the capacity of the individual. Cuvier's
brain weighed ratlier more than 64 oz. (1814 grammes), while
the brain of an idiot seldom weighs more than 23 oz. (652
grammes). The number and depth of the cerebral convolu-
tions also bear a close relation to intellectual power ; babies and
idiots have few and shallow folds, while the brains of men of
intellect are always markedly convoluted.

The cranial nerves, — The cranial nerves, twelve in number on
each side, arise from the base of the brain and medulla oblon-
gata {vide Fig. 73), and pass out through openings in the base
of the skull. They are named numerically according to the
order in which they arise from the brain. Other names are
also given to them derived from the parts to which they are
distributed, or from their functions. Taken in their order
from before backwards, they are as follows : —

1. Olfactory (sensory).

2. Optic (sensory).

3. Oculomotor (motor).

4. Pathetic or Trochlear (motor).

5. Trifacial or Trigeminal (mixed).

6. Abducens (motor).

7. Facial (motor).

8. Auditory (sensory).

^ Avoirdupois weights are used in weighing the organs of the body. One oz.
avoirdupois = 28.35 grammes.

Chap. VILj THE NERVOUS SYSTEM. 89

9. Glossopharyngeal (mixed).

10. Pneumo-gastric or Vagus (mixed).

11. Spinal accessory (motor).

12. Hypo-glossal (motor).

The olfactory nerve is the special nerve of the sense of smell. Its origin
is in the olfactory bulb. Its peripheral dendrones pass through the perfo-
rated plate of the ethmoid bone and are distributed to the mucous mem-
brane lining the nasal chambers, while the central axones pass backward to
the brain.

The optic nerve is the special nerve of the sense of sight. Its cell-bodies
are situated in the retinal coat of the eye. Part of its central axones ter-
minate in the same side of the brain, while the remainder cross to terminate
in a similar region on the opposite side of the brain. This crossing of part
of the fibres from both eyes forms the optic commissure.

The oculomotor nerve supplies all the muscles of the eye except the
superior oblique and the external rectus. It originates in the gray matter
of the pons Varolii.

The pathetic or trochlear nerve supplies only the superior oblique mus-
cle of the eye. It arises close to the preceding nerve.

The trifacial is the largest of the cranial nerves. Like the spinal nerves
it has two roots, — a dorsal or sensory (upon which there is a sensory gan-
glion), and a ventral or motor. The fibres from the two roots coalesce into
one trunk, and then subdivide into three large branches : the ophthalmic,
the superior maxillary, and the inferior maxillary. The ophthalmic branch
is the smallest, and is a sensory nerve. It supplies the eyeball, the lachry-
mal gland, the mucous lining of the eye and nose, and the skin and muscles
of the eyebi'ow, forehead, and nose. The superior maxillary, the second
division of the fifth, is also a sensory nerve and supplies the skin of the
temple and cheek, the upper teeth, and the mucous lining of the mouth and
pharynx. The inferior maxillary is the largest of the three divisions of the
fifth, and is both a sensory and a motor nerve. It sends branches to the
temple and the external ear ; to the teeth and lower jaw ; to the muscles of
mastication ; it also supplies the tongue with a special nerve (the lingual)
of the sense of taste. The cell-bodies of the motor fibres are situated in
the pons; while those of the sensory fibres, as in the case of the spinal
nerves, are situated in a ganglion. This ganglion is called the Gasserian
ganglion.

The abducens nerve supplies the external rectus muscle of the eye.

The facial nerve is the motor nerve of all the muscles of expression in
the face ; it also supplies the neck and ear. Its cells of origin, like those of
the abducens nerve, are situated in the medulla.

The auditory nei-ve is the special nerve of the sense of hearing. It
arises from cells which compose the spiral ganglion in the internal ear, to
•which its dendrones are exclusively distributed.

The glosso -pharyngeal nerve is distributed, as its name indicates, to the
tongue and pharynx, being the nerve of sensation to the mucous membrane

90 ANATOMY FOR NURSES. [Chap. VIL

of the pharynx, of motion to the pharyngeal muscles, and the special nerve
of taste to part of the tongue.

The pneumogastric nerve has a more extensive distribution than any of
the other cranial nerves, passing through the neck and thorax to the upper
part of the abdomen. It contains both motor and sensory fibres. It sup-
plies the organs of voice and respiration with motor and sensory filaments;
and the pharynx, oesophagus, stomach, and heart with motor fibres.

The spinal-accessory nerve consists of two parts : one, the spinal portion,
and the other, the accessory portion to the tenth nerve. It is a motor nerve
supplying certain muscles of the neck. It differs from the other cranial
nerves in arising from the spinal cord, but it leaves the skull by the same
aperture as the pneumogastric and glosso-pharyngeal.

The hypoglossal nerve is the n)otor nerve of the tongue.

It will be observed that of the twelve pairs of cranial nerves, four and a
part of a fifth, are distributed to the eye, viz. the optic, motor occuli, pa-
thetic, abducens, and the ophthalmic branch of the fifth. The ear has one
special nerve, the auditory, and is sparingly supplied with motor and sensory
fibres from other nerves. The nose has also one special nerve, the olfac-
tory, and is more abundantly supplied than the ear, with motor and sensory
fibres from other nerves. The tongue has two special branch nerves of taste,
— the lingual, a branch of the fifth, and the glossal, a branch of the ninth;
it has also its own motor nerve, the hypoglossal.

The physiology of the nervous system. — The physiology of the
nervous system, though exceedingly complex in its details, is,
in its essentials, not difficult to understand.

The simplest nervous mechanism is the reflex arc, and the
simplest form of nervous activity is "reflex action." Two
neurones enter into the formation of a reflex arc, a sensory
neurone and a motor neurone. On applying an appropriate
stimulus to the peripheral end of the sensory neurone an im-
pulse is generated which passes along the sensory neurone to
the nerve centre, and back again to the periphery by the motor
neurone ; and, since the motor neurone terminates in a muscle
(or some similar mechanism), we get a muscular response as
the indirect result of stimulating the sensory nerve.

The kind of stimulus which will call forth the nerve impulse
depends on the peripheral terminatiori of the sensory 7ierve, and
the kind of response which an appropriate stimulus will call
forth depends on the mode of terminatio7i of the motor nerve.
Thus light falling on the retinal coat of the eye (the peripheral
termination of the sensory nerve) generates an impulse which
passes to the centre by the optic nerve, and returns again by
the oculomotor nerve to the periphery, the sphincter of the

Chap. VII.]

THE NERVOUS SYSTEM.

91

iris (the termination of the motor nerve), which by its contrac-
tion narrows tlie pupil. Hence arises the well-lino wn phe-
nomenon of the contraction of the pupil when light falls upon
the eye.

Or, again, food passing into the upper part of the intestine
stimulates the sensory nerves there. The impulse passes to the
spinal cord, is reflected from this centre toward the periphery,
and passing along the motor nerve stimulates to contraction the
appropriate muscular mechanism which causes a flow of bile
into the intestine.

N.C.

M.O.

Fig. 74. — Reflex Arc (schematic). — 5.0., sensory organ; S.N., sensory neurone ;
iV.C, nerve centre; M.N., motor neurone; M.O., motor organ.

Also, stimulation of taste fibres in the mouth causes a reflex
secretion of the salivary glands. Innumerable examples of this
kind might be given. Indeed, since physical life has been well

Fig. 75. — Reflex Arc, as it is approximately in Man. — 1, Nerve terminal,
or sensory epithelium ; 2, dendrone of sensory neurone ; 3, cell-body in dorsal root
ganglion; 4, axone of sensory neurone; 5, dendrone of motor neurone ; 6, cell-body
in ventral horn; 7, axone of motor neurone; 8, end organ — muscle-cell, gland-
cell, ett.

92 ANATOMY FOR NURSES. [Chap. VII.

defined as the continual response to external stimuli, reflex ac-
tion, which is the chief method of response, is the most impor-
tant vital phenomenon peculiar to animals possessing any nervous
system whatsoever.

A careful study of Figs. 74 and 75 will make the typical
reflex path perfectly intelligible to the student, and should on
no account be omitted.

All nervous action is fundamentally similar to this typical
reflex action. Usually the number of neurones involved is
greater, often very much greater, than two. The fewer tiie
neurones, the simpler and more obviously machine-like the
reaction. The more complex the path, the more uncertain and
variable the reaction. When the path of the impulse does not
mvolve the cerebrum, the reactions are unconscious and com-
paratively simple; but if the cerebral cortex be involved, tlie
passage of the nerve impulse is accompanied by the phenome-
non of consciousness, and the reaction may be exceedingly com-
plex, uncertain, and long delayed. These are the characteristics
of what we call voluntary reactions. But, although the phrase
•' reflex action " is usually confined to those actions which are
involuntary and of which we are unconscious, yet all nervous
action is essentially the same, differing only in the complexity
of the path followed by the impulse.

We will now conclude with a summary of the functions of
the various parts of the nervous system.

The nerves serve to connect the distant parts of the body
with the central nervous system.

The spinal ganglia contain the cells of origin of all the
peripheral sensory nerve fibres.

The sympathetic ganglia serve to distribute motor, and to
collect sensory, impulses. Also in a few cases an afferent im-
pulse may pass to a ganglion by the dendrone of one sympa-
thetic neurone, and leave it to pass back again to the periphery
by the axone of another, the spinal column not being included
in the arc. Thus the sympathetic ganglia may occasionally act
as a centre for reflex action.

The spinal cord, medulla, and pons act as centres for the more
simple reHexes. In the medulla there are also special centres
which govern more complex muscular movements, such as the
vaso-motor centre which controls the calibre of the blood-vessels,

Chap. VII.]

THE NERVOUS SYSTEM.

93

and hence the flow of blood to all parts of the body ; and the
respiratory centre which coordinates the actions of the muscles
of respiration.

Fig. 7fi. — Diagram of Nervous System, a, a, cortex of cerebral hemispheres ;
6, b, cell-body and dendrones of upper motor neurone, situated in cerebral cortex;
b', axone of upper motor neurone, branching at its termination near the dendrones
of lower motor neurone: B, B, cell-body and dendrones of lower motor neurone, situ-
ated in the ventral horn of gray matter in the spinal cord ; B' , axone of lower motor
neurone passing to its termination in a voluntary muscle tibre B" ■. C, cell-body and
dendrones of upper sensory neurone, situated in the medulla oblongata; C"C", axones
of upper sensory neurones, terminating in cortex; c, cell-body of lower sensory neu-
rone situated in the dorsal root-ganglion ; c'", dendrone of lower motor neurone, con-
ducting impulses from the periphery to the central nervous system; c", long axone
of lower sensory neurone, conducting impulses toward the brain ; c', short axone of
lower sensory neurone, conducting impulses direct to ventral horn. (For the sake of
simplicity the connections with the cerebellum are cynitted.)

94 ANATOMY FOR NURSES. [Chap. VIL

The cerebellum is a great coordinating centre for impulses
passing from the cerebral cortex to the voluntary muscles.

The cerebral cortex is involved in all conscious perceptions
or sensations, in memory, and in the voluntary movements.
Different parts of the cortex have been shown to have different
functions. Thus there are areas for visual and auditory sensa-
tions ; areas which control the voluntary movements of various
parts of the body, — the leg, the arm, the hand, etc., each having
its separate area.^ There is also a well-defined " speech centre."

1 All the fibres passing to and from the cortex cross over to the other side of
the body, so that an injury to one side of the brain causes paralysis of the oppo-
site side of the body.

CHAPTER VIII.

THE VASCULAR SYSTEM: THE BLOOD.

Having studied the four distinctive tissues of the body (the
epithelial, connective, muscular, and nervous), their structure,
position in the body, and the various functions they are espe-
cially adapted to perform, we shall next consider the vascular,
respiratory, alimentary, and excretory systems, by means of
which all the tissues are supplied with the materials necessary
for their life and growth, and relieved of all those waste and
superfluous matters which are the results of their activity.

All the tissues of the body are traversed by minute tubes,
called capillary blood-vessels, to which blood is brought by
large tubes, called arteries, and from which blood is carried
away by other large tubes, called veins. These capillaries form
networks, the meshes of which differ in form and size in the
different tissues. The meshes of these networks are occupied
by the elements (cells or their products) of the tissues ; and
filling up such spaces as exist between the capillary walls and
the elements of the tissue, is found a colourless fluid, resembling
in many respects the fluid portion of the blood, and called
lymph. As the blood flows through the capillaries, certain
constituents of the blood pass through the capillary wall into
the lymph, and certain constituents of the lymph pass through
the capillary wall into the blood within the capillary. There
is thus an interchange of material between the blood within the
capillary and the lymph outside. A similar interchange of
material is at the same time going on between the lymph and
the tissue itself. Hence, by means of the lymph acting as
middleman, a double interchange of material takes place
between the blood within the capillary and the tissue outside
the capillary. In every tissue, so long as life lasts and the

95

96 ANATOMY FOR NURSES. [Chap. VIII.

blood flows through the blood-vessels, a fluid is passing from
the blood to the tissue, and from the tissue to the blood. The
fluid passing from the blood to the tissue carries to the tissue
the material which the tissue needs for building itself up and
for doing its work, including the all-important oxygen. The
fluid passing from the tissue to the blood carries into the blood
certain of the products of the chemical changes which have
been taking place in the tissue — products which may be simply
waste, to be cast out of the body as soon as possible, or which
may be products capable of being made use of by some other
tissues. The tissues, by the help of the lymph, live on the blood,
and the blood may thus be regarded as an internal medium,
bearing the same relations to the tissue that the external
medium, the world, does to the whole individaal. Just as the
whole body lives on the air and food around it, so do the several
tissues live on the complex fluid by which they are all bathed,
and which is to them their immediate air and food.

The blood. — The most striking external feature of the blood
is its well-known colour, which is bright red approaching to
scarlet in the arteries, but of a dark-red or purple tint in the
veins. It is a somewhat sticky liquid, a little heavier than
water, its specific gravity being about 1.055; it has a saltish
taste, a slight alkaline reaction, and a temperature of about
100° F. (37.8° C).

Seen with the naked eye the blood appears opaque and homo-
geneous ; but when examined with a microscope it is seen to
consist of a transparent' almost colourless fluid, with minute
solid particles immersed in it. The colourless fluid is named
plasma, the solid particles corpuscles. These corpuscles are of
two kinds, the red or coloured, and the white or colourless. In
a cubic millimetre ^ of healthy blood there are on an average
5,000,000 red corpuscles and 10,000 white. The number of
white varies much more than that of the red ; the proportion
of white to the red is usually given at from 1 to 250 up to
1 to 1000.

Red corpuscles of the blood. — The red corpuscles have a nearly

circuUir outline like a piece of coin, and most of them have a

shallow, dimple-like depression on both sides; their shape is,

therefore, that of biconcave disks. The average size is ^^q-q of

1 A millimetre is equal to 0.089, or ^V of an English inch.

Chap. VIII.] THE VASCULAR SYSTEM.

97

an inch (0.008 mm.) in diameter, and about one-fourth that
in thickness. When viewed singly by transmitted light the
coloured corpuscles do
not appear red, but ^ /nTTT'^
merely of a reddish-yel-
low tinge, or yellowish-
green in venous blood.
It is only when the light
shines upon a number
of corpuscles that a dis-
tinct red colour is pro-
duced. When blood is
drawn from the vessels,
the red disks sink in
the plasma : they have
a singular tendency to
run together, and to

cohere by their broad kk;. TT.-Kku and white Corpuscles of

surfaces so as to form the Blood. Magnified. ^, moderately magnified,

the red corpuscles are seen in rouleaux; a, a,

cylindrical columns like white corpuscles ; B, C, D, red corpuscles, highly

■niloc! f\y rniilocm-sr nf magnified, Seen in different positions ; J5^, a red cor-

^ ... puscle swollen into a sphere by imbibition of water;

coins, and the piles join F, <?, white corpuscles, highly magnified; A", white

flnpni<!Plvp« f-no-pthpv in corpuscle treated with acetic acid ; if, /, red cor-

tnemselves tOgemei in puscles wrinkled or crenated.

an irregular network.

Generally the corpuscles separate on a slight impulse, and may

then unite again.

Each red corpuscle is composed of an external colourless enve-
lope u'ith coloured fluid contents. — Quain.

The envelope is a very delicate membrane of a fatty nature,
and may be ruptured or dissolved under certain conditions.
The colour of the fluid contents is due to a crystallizable sub-
stance called haemoglobin. 1 If water be added to a preparation
of blood under the microscope, the water passes into the cor-
puscle, and the concave sides of the corpuscle become bulged
out so that it is rendered globular. By the further action of
water the hemoglobin is dissolved out of the corpuscle, and
the colourless envelope remains as a faint circular outline. On
the other hand, the addition of salt to a preparation of blood by

1 Haemoglobin is a compound proteid, i.e. its molecules consist of a proteid
portion, and of a pigment portion, the latter containing one atom of iron.

H

98 ANATOMY FOR NURSES. [Chap. VIII.

absorbing the water causes the corpuscles to shrink, and become
wrinkled or crenated. Tlie red corpuscles are practically small
flattened bags, or sacs, the form of which may be clianged by
altering the density of the plasma. They are very soft, flexible,
and elastic, so that they are readily squeezed through apertures
and passages narrower than their own diameters, and when
pressure is withdrawn, immediately resume their proper shape.

Function of the red corpuscles. — The red corpuscles, or ery-
throcytes, by virtue of the hiemoglobin which they contain, are
emphatically oxygen carriers. Exposed to the air in the lungs,
the hiemoglobin combines with the oxygen present in the air ;
this oxygen the haemoglobin carries to the tissues ; these, more
greedy of oxygen than hsemoglobin itself, rob it of its charge,
and the haemoglobin, thus deprived of its oxygen, hurries back
to the lungs for a fre.sh supply.^ The utility of the haemo-
globin consists in the ease with which under certain conditions
(those existing in the lungs) it takes up oxygen, and the
readiness with which under certain conditions (those existing
in the capillaries) it gives up this oxygen again. The colour
of the blood is dependent upon this combination of the
haemoglobin with oxygen ; when the haemoglobin has its full
complement of oxygen, the blood has a bright red hue ; when
the amount is decreased, it changes to a dark purplish hue.
The scarlet blood is usually found in the arteries, and is
called arterial ; the dark purple in the veins, and is called
venous blood.

White corpuscles of the blood. — The white, colourless corpus-
cles, or leucocytes, are few in number compared with the red,
and both on this account, and because of their want of colour,
they are not at first easily recognized in a microscopic prepara-
tion of blood. Their form is very various, but when the blood
is first drawn they are rounded or spheroidal. Measured in
this condition they are about 2~5Vo ^^ ^'^ ^"^^^ (0.010 mm.)
in diameter. The white corpuscle may be taken as the type of
a free animal cell. It is a small piece of protoplasm, contain-
ing a nucleus, and has no limiting membrane or cell-wall {vide

These corpuscles, or cells, possess the power of spontaneous

1 Processes which are characterized by combination with oxygen are known
as oxidation, while the reverse processes are known as reduction.

Chap. VIII.] THE VASCULAR SYSTEM. 99

movement, and are capable of changing their form and place.
While, when in a state of rest, they assume in general the
spheroidal form, we find that when they become active they
send out variously shaped processes, some fine and delicate,
others broad, and of very irregular shape. We often see, after
a process has been thrown out, that it becomes larger and
larger, the cell-body becoming correspondingly smaller, until
finally the whole cell passes over into the process, thus moving
forward. These amoeboid movements are always very slow,
and are greatly influenced by the temperature, density, and
amount of oxygen in the fluid in which the cells lie. By virtue
of this locomotive power the white blood cells perform certain
evolutions within the blood-vessels ; they also escape through
their walls, and sometimes singly, sometimes in vast numbers,
move through the lymph spaces in the surrounding tissues.
This is spoken of as the "migration of the white corpuscles."
In an "inflamed area" large numbers of white corpuscles are
thus drained away from the blood. These migrating corpuscles,
or wandering cells, may, by following the devious tracks of the
lymph, find their way back into the blood ; some of them, how-
ever, may remain and undergo various changes. Thus in in-
flamed areas, when suppuration follows inflammation, the white
corpuscles which have migrated may become "pus corpuscles."

Again, by virtue of their amoeboid movements, the white
corpuscles can creep around objects, enveloping them with their
own substance, and so putting them inside themselves. As an
illustration of this action of the white corpuscle, we may state
that, according to some observers in certain diseases in which
micro-organisms make their appearance in the blood, the white
corpuscles take up these micro-organisms into their substance,
and probably exert an influence over them, which modifies the
course of the disease of which these micro-organisms are the
essential cause.

Furthermore, the white corpuscles are not only capable of
taking up particles in the blood, but are also capable of giving
up products which they have changed or modified, to the blood,
and it follows that these metabolic changes must necessarily
affect the composition of the fluid plasma in which they lie.

The plasma of the blood. — The plasma is a clear, slightly
yellowish coloured fluid, consisting for the most part of water,

100 ANATOMY FOR NURSES. [Chap. VIII.

holding in solution or suspension proteid substances, fats,
various extractives, and salts.

The proteid substances are albumin, para-globulin, and fibrin-
ogen. The albumin and para-globulin occur in about equal
quantities; but the fibrinogen, though a most important ele-
ment in the blood, occurs in very small quantities. The fats are
scanty, except after a meal, or in certain diseased conditions.
The extractives, so named because they have to be extracted by
special methods from the blood, are very numerous. The most
important are perhaps urea, lactic acid, and sugar.

Tlie salts in the plasma are the chlorides and sodium salts,
the phosphates and potassium salts being found chiefly in the
corpuscles.

Of all these substances, albumin probably holds the first place
in regard to nutrition, providing, as it does, the greater part of
the material necessary for the daily nourishment and renovation
of the tissues. In this process it undergoes a variety of trans-
formations by which it is converted into the structural charac-
teristics of the tissues which it supplies.

Para-globulin is closely allied to albumin in its chemical rela-
tions, and no doubt also in its physiological action. Both sub-
stances are coagulated by heat, and solidified at a temperature
of 160° F. (71.1° C).

The fibrinogen of the plasma is the substance which produces
the fibrin of coagulated blood. It is very difficult to obtain
in the fluid condition, owing to the rapidity with which it
solidifies when blood is withdrawn from the circulation.

Of the mineral salts, the sodium chloride is the most abun-
dant, constituting nearly 40 per cent of all the saline ingredi-
ents. The mineral salts maintain the alkalinity of the blood,
a property which is essential to nutrition, and even to the
immediate continuance of life, since it enables the plasma to
take up the carbon dioxide from the tissues and return it to the
lungs for elimination.

The clotting of blood. — Blood when drawn from the blood-
vessels of a living body is perfectly fluid. In a short time it
becomes viscid, and this viscidity increases rapidly until the
whole mass of blood becomes a complete jelly. If the blood in
this jelly stage be left untouclied in a glass vessel, a few drops
of an almost colourless fluid soon make their appearance on the

Chap. VIII.] THE VASCULAR SYSTEM. 101

surface of the jelly. Increasing in number and running together,
the drops after a while form a superficial layer of pale straw-
coloured fluid. Later on, similar layers of the same fluid are
seen at the sides, and finally at the bottom of the jelly, which,
shrunk to a smaller size and of firmer consistency, now forms a
clot or crassamentum, floating in a liquid. The upper surface
of the clot is generally slightly concave. If a portion of the
clot be examined under the microscope, it is seen to consist of a
network of fine fibrils in the meshes of which are entangled the
red and white corpuscles of the blood. The fibrils are composed
of the fibrin ; and the liquid in which the clot is suspended is
blood minus corpuscles and fibrin, and is called serum. The
clotting of the blood is entirely dejDcndent upon the fibrin ; for
if fresh blood, before it has time to clot, be whipped with a
bundle of twigs, the fibrin will form on the twigs, and if the
whipping of the blood be continued until all the fibrin has been
deposited on the twigs, the blood left in the vessel will be found
to have lost all power of clotting.

The coagulation of blood is hastened by high temperature,
and by contact with any rough surface or non-livi'ig- material.
On the other hand, a low temperature retards, taid the addition
of salt in sufficient quantity prevents, coagulation. After death,
the blood usually remains a long time fluid in the vessels, and
it never clots so firmly and completely as when shed. It clots
first in the larger vessels, but not until several hours after death
in the smaller vessels.

The coagulability of the blood differs in difl^erent individuals,
and in rare cases is so slight that the most trivial operation in-
volving hemorrhage is attended with great danger.

The quantity of blood contained in the body is a balance
struck between the tissues which give to, and those which take
away from, the blood. Thus the tissues of the alimentarj^ canal
largel}^ add to the blood water and the material derived from
food, while the tissues of the excretory organs largely take
away water, urea, and the other substances resulting from the
waste of the tissues. From the result of a few observations
on executed criminals, it has been concluded that the total
quantity of blood in the human body is about -^^ of the body
weight.

General composition of the blood. — Not only do the several tis-

102 ANATOMY FOR NURSES. [Chap. VIII.

sues take up from the blood and give up to the blood different
thing's at different rates and at different times, but all the
tissues take up oxygen and give up carbon dioxide in varying
quantities. From this it follows, on the one hand, that the
composition and character of the blood must be forever varying
in different parts of the body ; and, on the other hand, that the
united action of all the tissues must tend to establish and main-
tain an average uniform composition of the whole mass of blood.
To sum up briefly, the blood is composed of —

Plasma

Proteid substances.

Fats.

Extractives.

Salts,
r Red
Corpuscles \ and

[ White.

The plasma is chiefly the carrier of nutriment to the tissues,
and of waste matter from the tissues. The red corpuscles are
pre-eminently the carriers of oxygen ; the white corpuscles may
be regarded as scavengers, us important protective elements in
many diseases, and jjossibly as contributors to the construction
of new tissue where such has been injured or destroyed.

Note. — When we remember that the tissues live on the blood, we recognize
the gravity of those diseased conditions in which important elements are being
constantly drained away from the blood, as, for example, the albumin in dis-
eases of the kidneys, the red corpuscles in hemorrhage, the water of the blood
in cholera, etc. Withdrawal of oxygen, as we all know, causes instant death,
and a constant supply of fresh air is a vital necessity of life. Nor is it of less
importance that the blood be kept free from those waste matters, — pre-eminently
carbon dioxide and urea, — which, in accumulating, poison the system, and. if
not excreted in sufficient amount, will as surely cause death as the withdrawal
from the blood of any of its most vital constituents.

CHAPTER IX.

THE VASCULAR SYSTEM CONTINUED: HEART; ARTERIES;
VEINS; CAPILLARIES.

The blood, as we have said, is the internal medium on which
the tissues live. It is carried through the body by branched
tubes named blood-vessels. It is driven along these tubes by
the action of the heart, which is a hollow muscular organ placed
in the centre of the vascular system. One set of vessels — the
arteries — conducts the blood out from the heart and distributes
it to the different parts of the body, whilst other vessels — the
veins — bring it back to the heart again. The blood from the
arteries gets into the veins by passing through a network of
fine tubes which connect the two, and which are named, on
account of their small size, the capillary (^i.e. hair-like) vessels.

All the tissues except the epithelial and cartilaginous tis-
sues are traversed by these networks of capillary vessels.
It is through the thin walls of the capillaries that the inter-
change of material which is continually going on between the
blood and the tissues takes place. It is in the capillaries, then,
that the chief work of the blood is done ; and the object of the
vascular mechanism is to cause the blood to flow throusfh these
vessels in the manner best adapted for accomplishing this work.

The use of the arteries is to carry and regulate the supply of
blood from the heart to the capillaries; the use of the veins, to
carry the blood from the capillaries back to the heart ; the use
of the heart, to drive the blood in a suitable manner through
the arteries into the capillaries, and from the capillaries back
along the veins to itself again. We shall see that the structure
of these several parts is adapted to these several uses.

The heart. — The heart is a hollow muscular organ, divided
by a longitudinal partition into a right and a left heart, each of
which is subdivided by a transverse constriction into two com-
partments, an upper and a lower, which communicate with each

103

104

ANATOMY FOR NURSES.

[Chap. IX.

other. Its general form is tliat of a blunt cone. It is situated
in the thorax, between the lungs, and, together with the adja-
cent parts of the great blood-vessels which carry blood to and
from it, is enclosed in a membranous covering, the pericardium.

The heart lies nearer
to the front than to
the back of the chest,
and is placed behind
the sternum and the
costal cartilages, the
broader end or base
being directed up-
wards, backwards, and
to the right, while the
pointed end or apex
points downwards, for-
wards, and to tlie left.
The impulse of the
heart against the wall

Fig 78. -The Heart AND LUKU«. x, nght ven- ^^ ^^^^ ^j^^^^ • ^^^^ -^^
tricle; o, right auricle; b, 7, pulmonary artery; 9,

aorta; 10, superior vena cava; 11, innominate ar- the spaCC between the

tery; 12, right subclavian vein ; 14, innominate vein; nr,^ , -i -,0.1 ,m

15,'left common carotid; 17, trachea; 20, pulmonary "^^'^ '^^^^^ SlXtU riDS, a

veins; 22 to 25, lungs, partially turned back to show little below and tO the

veins on left side. . . . c n 1 f,

inner side oi tlie left
nipple. It has, therefore, a very oblique position in the chest.
It is suspended and kept in position by the great vessels at the
base, and is also supported by the diaphragm. According to
Laennec, the heart in its normal condition is about equal in
size to the fist of the individual to whom it belongs.

The main substance of the lieart is composed of muscular
tissue. Between the muscle fibres is a certain amount of in-
terstitial tissue with numerous blood-vessels and lymphatics,
and, in some parts, nerves and ganglia. There is also a consid-
erable amount of fat, chiefly collected at the base of the heart,
and beneath the pericardium. The muscular tissue of the heart
differs from all other involuntary muscular tissue in possessing
transverse striae. The fibres continually branch and unite with
one another so as to form a kind of network or sponge-like sub-
stance. The arrangement of the fibres differs in the auricles
and the ventricles, and is very intricate; the fibres run trans-

Chap. IX.]

THE VASCULAR SYSTEM.

105

versely, longitudinally, obliquely, and in the apex of the ven-
tricles take a spiral turn or twist. The muscular walls of the
auricles are much thinner than those of the ventricles, and the
wall of the left ventricle is thicker than that of the right.
This difference in bulk is
to be accounted for, as
we shall see later on, by
the greater amount of
work the ventricles, as
compared with the auri-
cles, have to do. The
muscular walls of the
heart are abundantly
supplied with blood
and lymph. The nerves
which supply the heart
are partly derived from
the cerebro-spinal system,
and partly from the sym-
pathetic system. Con-
nected with the nerve
fibres supplying the heart fiq. 79. _ anterior View of heart, Dis-

are groups of nerve cells, sected, after Long Boiling, to sh..w the

° 7 Superficial Muscular Fibres. (Allen Thom-

Or ganglia. son.) The aorta {¥) and pulmonary artery (a')

Thp heart is covered ^^^^'^ been cut short close to the semilunar valves.

' a, right ventricle; b, left ventricle; c, c, groove

as mentioned above, by a between ventricles; d, c?', right auricle; e, e', left

1 • • auricle: /", superior vena cava; r/', r/", right and

membranous covering m ^^^^ pulmonary veins. The fibres are seen run-

the form of a sac. This ning in a circular, oblique, transverse, and longi-

, . tudinal direction.

membranous sac, or peri-
cardium, is one of the serous membranes of the body.^ It is a
sort of double bag ; one half of the bag, called the visceral por-
tion (yiscus, organ), is closely adherent to the heart substance,
and also covers the great blood-vessels for about an inch and a
half (38 mm.) from the base of the heart ; the other half, the
parietal portion, is continuous with, and reflected over, the vis-
ceral portion, so that it loosely envelops both it and the heart.
The pericardium forms a completely closed sac ; its internal
surfaces are very smooth and polished, they are lined by endo-
thelium (see note on p. Ill) and secrete a small quantity of
1 See note on serous membranes at end of chapter.

106

ANATOMY FOR NURSES.

[Chap. IX.

Fig. 80. — Diagram of Heart and Peri-
cardium. In A, heart and pericardium lying
separately. In B, pericardium lying around
heart. 7/, heart; P, pericardium; P.O. peri-
cardial cavity ; P.P. parietal portion of pericar-
dium ; V.P. visceral portion.

serous fluid. As their
opposing surfaces, owing
to the constant contrac-
tions of the heart, are
continually sliding one
upon the other, they are
admirably constructed to
protect the heart from any
loss of power by friction.
The interior of the
heart is lined by a deli-
cate, smooth membrane,
called the endocardium.
This pavement membrane lines all the cavities of the heart,

and is continued into
the blood-vessels, form-
ing their innermost coat.
The cavities of the
heart. — The heart is
divided from the base
to the apex, by a fixed
partition, into a right
and left half. The two
sides of the heart have
no communication with
ch other: the right
side always contains
venous, and the left
ide arterial, blood.
Each half is sub-
divided into two
0 cavities, the up-
per, called auri-
cle ; the lower,
ventricle. These
cavities com-
municate with
Fig. 81. — Right Side of Heart. A, cavity of right ven- .-, i

tricle ; 5, sup. vena cava; C, inf. vena cava; «, wall of right ^^^® anotner Dy
ventricle; 6, c, columnie carneae ; r/, pulmonary vein ; e,/, tri- means of COn-
cuspid valve; m, semilunar valve; o, wall of left ventricle ; . • - i
p, q, V, ascending aorta, arch and descending aorta. StriCtecl Open-

Chap. IX.]

THE VASCULAR SYSTEM.

107

ings, the auriculo-ventricular orifices, which are strengthened
by fibrous rings, and protected and guarded by valves. The
valve guarding the right auriculo-ventricular opening is com-
posed of three triangular flaps, and is hence named tricuspid.
The flaps are mainly formed of fibrous tissue covered by endo-
cardium. At their bases they are continuous with one another,
and form a ring-shaped membrane around the margin of the
auricular opening: their pointed ends are directed downwards,
and are attached by cords, the cliordoe tendi-
nece, to little muscular pillars, the cohmi-
noB carneoe^ provided in the interior
of the ventricles for this purpose.
The valve guarding the left
auricular oj)ening consists
of only two flaps, and is
named the bicuspid, or
mitral valve. It is
attached in the
same manner as
the tricuspid
valve, which it
closely resem-
bles in struc
ture, except
that it is much
stronger and
thicker in all
its parts.

Fio. SJ —

IjFFI biDh OF

[k\rt l.cav-
)f left aiiiiele;
ppTiinij of riglit
pulmonary veins , .''), left
pnlnionary veins , 6, auri-
i lll()-^ ('Utricular openiiiE: , 8, w all
of left ^entric]e, '» caMty of left ven-
tricle; a, mitral valve (its flaps are attached by the chord® tendineae to the mus-
cular pillars (6, h) ; d, arch of aorta) ; e, pulmonary artery.

These valves oppose no obstacle to the passage of the blood
from the auricles into the ventricles; but any flow forced back-
wards gets behind the flaps of the valve (between the flap and
the wall of the ventricle) and drives the flaps backwards and
upwards, until, meeting at their edges, they unite and form
a complete transverse partition between the ventricle and auri-
cle. Being retained by the chordse tendinese, the expanded
flaps of the valve resist any pressure of the blood which might
otherwise force them back to open into the auricle; the mus-
cular pillars, also, to which the chordse tendinese are attached.

108

ANATOMY FOR NURSES.

[Chap. IX.

contract and shorten at the same time, and thus keep them
taut.

Besides the openings between the auricles and ventricles, each
auricle has two or more veins opening into it, and each ventricle
has a large artery opening out of it. The openings of the veins do
not require valves, but both the arterial openings are provided
with a set of valves. These valves, called seanilunar valves, con-
sist of three semicircular flaps, each flap being attached at its
base to the inside of the artery where it joins the ventricle,
while its free edge projects into the interior of the vessel. The

vent.

vent.

Fig. 83. — Diagram to illustrate the Action of the Heart, aur, auricle;
vent, ventricle; v, veins; a, aorta; m, mitral valve; s, semilunar valves. In A,
auricle is seen contracting, ventricle dilated, mitral valve open, semilunar valves
closed. In B, auricle is seen dilated, ventricle contracting, mitral valve closed,
semilunar valves open.

flaps of these valves form a complete barrier, when closed, to
the passage of the blood from the arteries into the heart, but
offer no resistance to the flow from the heart into the arteries.
The beat of the heart. — So long as life lasts, the muscular
tissue of the heart contracts and relaxes unceasingly. We may
call the heart a muscular pump, the force of whose strokes is
supplied by the contraction of muscular fibres, the strokes being
repeated so many times a minute. It is constructed and fur-
nished with valves in such a way that, at each stroke, it drives
a certain quantity of blood with a certain force and a certain
rapidity from the ventricles into the arteries, receiving, during
the stroke, and the interval between that stroke and the next,
the same quantity of blood from the veins into the auricles.

Chap. IX.]

THE VASCULAR SYSTEM.

109

The contractions of the heart are rhythmical; that is to say,
they occur in a certain order. First, there is a simultaneous
contraction of the walls of both auricles; immediately following
this, a simultaneous contraction of both ventricles; then comes
a pause, or period of rest, after which the auricles and ven-
tricles contract again in the same order as before, and their
contractions are followed by the same pause as before. The
state of contraction of the
heart is called the systole ;
the state of relaxation and
dilatation, its diastole.

If the chest of an ani-
mal be opened and arti-
ficial respiration kept up,
the heart may be watched
beating, and a complete
beat of the whole heart
may be observed to take
place as follows : —

The great veins are
seen, while full of blood,
to contract in the neigh-
bourhood of the heart,
the wave of contraction
running on towards the
auricles, increasing in in-
tensity as it goes. Arrived at the auricles, which are now full
of blood, the wave of contraction passes on to them, and they
contract suddenly and quickl3^ During this contraction, the
walls of the auricles press towards the auriculo-ventricular ori-
fices, and the blood passes over the tricuspid and mitral valves
into the ventricles. The ventricles fill rapidly, and as soon as
the auricular contraction is over, they in turn are seen to con-
tract, their walls becoming very tense and hard; the apex is tilted
upwards, and the heart twists somewhat on its own axis. Dur-
ing the ventricular contraction the blood in the ventricles is
forced through the semilunar valves into the arteries, which are
seen to elongate and expand as the blood is pumped into them.

The work of the auricles and ventricles is very unequal. All
the auricles have to do is to pump the blood into the ventricles,

Fig. 84. — Section of Heart at Level of
Valves. P, pulmonary artery, with Haps of
semilunar valve open; A, aorta, with flaps of
semilunar valve open ; M, closed mitral valve ;
T, closed tricuspid valve.

110 ANATOMY FOR NURSES. [Chap. IX.

which at the time are nearly empty cavities with relaxed and
flaccid walls. The ventricles, on the contrary, have to pump the
blood into tubes which are already full; and if there were no
auriculo-ventricular valves, the blood would meet with less resist-
ance in pushing its way backward into the auricles than in push-
ing open the semilunar valves and forcing its way into the arteries.
Hence the necessity, first, of the tricuspid and mitral valves;
and, secondly, of the superior thickness and strength of the
walls of the ventricles, as compared with those of the auricles ;
and since the left side of the heart has a larger sj'stem of blood-
vessels to supply, and more resistance to overcome, than the
right side, it follows that the left ventricle needs a thicker
muscular wall than the right.

The beat of the heart is caused by the rhythmical contractions
of its muscular fibres. Whether these contractions are auto-
matic or dependent upon the ganglia lodged in the cardiac
muscular tissue, is uncertain. That the contractions of the
heart do not depend upon the general nervous system is certain,
for the heart will continue to beat for some little time after its
removal from the body. It probably depends upon complex
metabolic changes, not yet clearly understood.

The character of the beat, however, is governed and regulated
by two sets of nerves. The first set come from the cerebro-spinal
centre, and are supplied by the pneumogastric nerves. They are
the inhibitory fibres; that is to say, they slow and, with a strong
stimulation, will stop for a short time the action of the heart.
They weaken the systole, and prolong the diastole. The other
set come from the sympathetic nerves, and are accelerating fibres
which, upon stimulation, increase not only the rapidity, but the
force of the beat. The diastole is shortened, and the systole
strengthened.

The sounds of the heart. — If the ear be applied over the heart,
certain sounds are heard, which recur with great regularity.
The first sound is a comparatively long, booming sound; the
second, a short, sharp, sudden one. Between the first and
second sounds, the interval of time is very short, too short to
be measurable; but, between the second and the succeeding first
sounds there is a distinct pause. The first sound is generally
supposed to be caused by the contraction of the ventricular
walls; the second sound is undoubtedly caused by the sudden
closure of the semilunar valves.

Chap. IX.]

THE VASCULAE SYSTEM.

Ill

These sounds in certain diseases of the heart become changed
and obscure, and are replaced by various distinctive and charac-
teristic murmurs.

The arteries. — An artery is usually described as being com-
posed of three coats, — an inner or elastic, a middle or muscular,
and an external or areolar.

The inner coat of an artery consists of two layers : the inner
layer is composed of endothelium,^
and forms a smooth lining for the
tube; the outer layer is a fine net-
work of elastic connective tissue
fibres.

The middle or muscular coat con-
sists mainl}'" of circularly disposed
plain muscular fibres. It has also
in most large arteries layers of elas-
tic fibres, which form close felted
networks, the fibres running for the
most part in an oblique and longi-
tudinal direction.

The outer coat is formed of areo-
lar tissue, mixed with which are a
good many elastic fibres. The
strength of an artery depends largely
upon this coat; it is far less easily cut or torn than the other
coats, and it serves to resist undue expansion of the vessel.
The arteries are also protected by sheaths of connective tissue,
which surround and blend with the outer coat.

By virtue of their structure, the arteries are both contractile
and elastic. The proj)ortion of the muscular and elastic ele-
ments differs in different arteries; but, as a general rule, the
larger arteries are the more elastic, and the smaller the more
muscular. The elasticity and contractility of the arteries may
be demonstrated by the following example : —

If we tie a piece of a large artery at one end and inject fluid

1 Endothelium is the name now generally given to the variety of epithelium
lining {i.e. lying xmthin) certain parts of the body ; it is composed of flattened,
transparent cells joined edge to edge so as to form smooth membranes. It is
found on the free surfaces of the serous membranes ; as the lining membrane of
the heart, blood-vessels, and lymphatics ; on the surface of the brain and spinal
cord, and iu the anterior chamber of the eye.

Fig. 85. — Structure of an Ar-
tery. (Ledig.) A, internal coat,
with h, its inner layer of pavement
epithelium (endothelium); c, middle
coat, with transverse fibres; d, outer
coat, with longitudinal fibres.

112

ANATOMY FOR NURSES.

[Chap. IX.

into the other end, the artery swells out to a very great extent,
but will return at once to its former size when the fluid is let
out. This great elasticity of the arteries adapts them for
receiving the additional amount of blood thrown into them
at each contraction of the heart. Again, if we stimulate the
muscular coat of any of the smaller arteries, the artery will
shrink in size, the circularly disposed fibres contracting and
narrowing the calibre of the vessel. This contractility is under
the control of the nervous system, and as the organs of the
body that are at rest do not require so much blood as those that
are working actively, the nervous system, the master-regulator
of the body's work, is able to diminish or increase the supply of
blood to the capillaries in different parts by acting upon this
contractile muscular tissue in the arterial walls. The arteries
do not collapse when empty; and when an artery is severed, the
orifice remains open. The muscular coat, however, contracts
jl 15 somewhat in the neighbourhood of the

opening, and the elastic fibres cause the
artery to retract a little within its sheath. ^
The walls of the arteries are supplied with
both blood-vessels and nerves. The blood-
vessels are known as the vaso-vasorum ves-
sels and the nerves as the vaso-motor nerves.
The veins. — The veins have three coats,
and on the whole resemble the arteries in
structure. They differ from them, how-
ever, in having much thinner walls, and
in their walls containing relatively much
more white fibrous tissue and much less
yellow elastic tissue. They are, therefore, not so elastic or con-
tractile as the arteries, and their walls collapse when empty.
Many of the veins, especially those of the limbs, are provided
with valves, which are mechanical contrivances adapted to pre-
vent the reflux of the blood. The valves are semilunar folds of
the internal coat of the veins; the convex border is attached to
the side of the vein, and the free edge points towards the heart.
Should the blood in its onward course towards the heart be, for
any reason, driven backwards, the refluent blood, getting be-
tween the wall of the vein and the flaps of the valve, will press
1 This property of the severed artery is an important factor in the arrest of
hemorrhage.

Fig. 86. — ^, part of a
vein, laid open, with two
pairs of valves; B, longi-
tudinal section of vein,
showing valves closed.

Chap. IX.] THE VASCULAE SYSTEM. 113

them inwards until their edges meet in the middle of the chan-
nel and close it up. The valves have usually two flaps, some-
times one, and rarely three. The veins, like the arteries, are
supplied with both blood-vessels and nerves, the supply, how-
ever, being far less abundant.

The capillaries. — The walls of the capillaries are formed
entirely of a layer of simple endothelium composed of flat-
tened cells joined edge to edge by cement substance, and
continuous with the layer which lines the arteries and veins.
The capillaries communicate freely with one another and form
interlacing networks of variable form and size in the different
tissues. Their diameter is so small that often the blood-cor-
puscles must pass through them in single file, and in many parts
they lie so closely together that a pin's point cannot be inserted
between them. They are most abundant, and form the finest
networks in those organs where the blood is needed for other
purposes than local nutrition, such as, for example, for secretion
or absorption. In the glandular organs they supply the sub-
stances requisite for secretion; in the alimentary canal they
take up the elements of digested food; in the lungs they absorb
oxygen and give up carbonic acid; in the kidneys they discharge
the waste products collected from other parts; all the time, every-
where through their walls, that interchange is going on which is
essential to the renovation, growth, and life of the whole body.

It must be remembered that although the arteries, veins, and
capillaries have each the distinctive structure above described,
it is at the same time difficult to draw the line between the
smaller artery and larger capillary, and between the larger
capillary and smallest vein. The veins on leaving the capillary
networks only gradually assume their several coats, while the
arteries dispense with their coats in the same imperceptible way
as they approach the capillaries.

Serous membranes. — Serous membranes are thin and transparent, tol-
erably strong, extensile, and elastic. They are lined on the inner snrface by
a simple epithelial layer of flattened cells (endothelium). The surfaces are
moistened by a fluid resembling serum, and from which t^e membranes
obtain their name of serous membranes. Here and there between the cells
openings are seen, which are of two kinds. The smaller and more numerous
are false openings, and are termed pseudo-stomata; the larger or true aper-
tures are termed stomata, and open into subjacent lymphatics. The sub-
stance of serous membranes underneath the endothelium is composed of a

114

ANATOMY FOR NUESES.

[Chap. IX.

network of connective tissue containing a variable amount of white and
elastic fibres. Where the membrane is thick, this ground substance contains
blood-vessels and lymphatics, the lymphatics being exceedingly abundant.

Serous membranes form closed sacs, one part of which is attached to the
walls of the cavity which it lines, — the parietal portion, — whilst the other
is reflected over the surface of the organ or organs contained in the cavity,
and is named the visceral portion of the membrane. In this way the viscera
are not contained within the sac, but are really placed outside of it, and
some of the organs may receive a complete, while others receive only a par-
tial or scanty, investment.

In passing from one part to another the serous membrane in the abdomen
frequently forms folds, some of which are designated by special names, such
as the mesentery, meso-colon, and omentum.

Fig. 87.-

■Portion of Endothelium of Peritoneum. (Klein.) a, larger cells;
6, smaller ones, with here and there a pseudo-stoma between.

The chief serous membranes are the peritoneum, the largest of all, lining
the cavity of the abdomen; the two pleurEB, lining the chest and covering
the lungs ; the pericardium, covering the heart.

The peritoneum in the female is an exception to the rule that serous
membranes are perfectly closed sacs, as it has two openings by which the
Fallopian tubes communicate with its cavity.

The inner surface of a serous membrane is free, smooth, and polished;
the inner surface of one part is applied to the corresponding inner surface
of some other part, a very small quantity of fluid only being interposed
between the surfaces. The organs situated in a cavity lined by a serous
membrane, being themselves also covered by it, can thus glide easily against
its walls or upon each other, their motions being rendered smoother by the
lubricating fluid.

CHAPTER X.

THE VASCULAR SYSTEM CONTINUED: ARTERIAL DISTRIBUTION
AND VENOUS RETURN.

The arteries. — The arteries, which carry and regulate the
supply of blood from the heart to the capillaries, are distributed
throughout the body in a systematic manner, and before taking
up the circulation we must try to gain a general idea of this
system of distribution, in order that we may be able to locate
the position of these important vessels. The arteries usually
occupy protected situations, that they may be exposed as little
as possible to accidental injury. As they proceed in their
course they divide into branches, the division taking place in
different ways. An artery may at once resolve itself into two
or more branches, no one of which greatly exceeds the rest in
size ; or it may give off several branches in succession, and still
maintain its character as a trunk. An artery, after a branch
has gone off from it, is smaller than before, but usually con-
tinues uniform in diameter until the next secession. A branch
of an artery is less in diameter than the trunk from which it
springs, but the collective capacity of all the branches into
which an artery divides is greater than the parent vessel. Since
the area of the arterial system increases as its vessels divide, it
is evident that the collective capacity of the smaller vessels
and capillaries must be greater than the collective capacity of
the trunks from which they arise. As the same rule applies to
the veins, it follows that the arterial and venous systems may
be represented, as regards capacity, by two blunt cones whose
apices are at the heart, and whose bases are united in the cap-
illary system. The effect of this arrangement of the circulatory
vessels is to make the blood flow more slowly as it passes
through the more widely distributed vessels, and to accelerate
its speed in the larger and less numerous trunks, just as the
water of a river flows more rapidly through its narrow chan-
nels, and lingers in those that are broad.

115

116 ANATOMY FOR NURSES. [Chap. X.

The arteries unite at frequent intervals when they are said
to anastomose or inosculate. Such inosculations admit of free
communication between the currents of the blood, tend to pro-
mote equality of distribution and of pressure, and to obviate
the effects of local interruption. .

Arteries commonly pursue a tolerably straight course, but in
some parts of the body they are tortuous. The facial artery
in its course over the face, and the arteries of the lips, are
extremely tortuous, so that they may accommodate themselves
to the movements of the parts. The uterine arteries are also
tortuous, to accommodate themselves to the increase in size of
the uterus during pregnancy.

In describing the distribution of the arteries we shall first
consider the artery arising from the left ventricle of the heart,
the aorta, and its branches.

The aorta. — The aorta is the main trunk of the arterial sys-
tem. Springing from the left ventricle of the heart, it arches
over the root of the left lung, descends along the vertebral col-
umn, and after passing through the diaphragm into the abdomi-
nal cavity, ends opposite the fourth lumbar vertebra by dividing
into the risfht and left common iliac arteries. In this course
the aorta forms a continuous single trunk, which gradually
diminishes in size from its commencement to its termination
(from 28 to 17 mm.), and gives off larger or smaller branches
at various points. It may be divided into the ascending aorta,
the short part which is contained within the pericardium ; the
arch, the part extending from the ascending aorta, and forming
a well-marked curve in front of the trachea, and around the root
of the left lung to the border of the fourth dorsal vertebra ; the
descending thoracic aorta, the comparatively straight part extend-
ing to tlie (liai)hragm; the abdominal aorta, below the diaphragm.
Tlie ascending aorta gives off two small branches, the right and
left coronary arteries, which supply the substance of the heart
with bh)()(l. The arch gives off three large trunks, the innomi-
nate, the left common carotid, and the left subclavian arter3\

The innominate artery arises from the right upper surface of
the arch, ascends obliquely towards the right, until, arriving on
a level with the upper margin of the clavicle, it divides into
the right common carotid and right subclavian arteries. Its usual
lensrth is from one to two inches.

Chap. X.]

THE VASCULAR SYSTEM.

117

The left common carotid arises from the middle of the upper
surface of the arch of the aorta, and the left subclavian arises
from the left upper surface of the arch.

^■^r IS

10

io

Figs. 88, 89. — The Aorta. A, from before ; B, from behind, with the origin of its
principal branches. (R. Quain.) 1, 2, ascending aorta; 2, 3, arch of aorta; 4, innomi-
nate artery ; 5, left carotid ; (i, left subclavian ; 7,7,7, intercostal and lumbar arteries ;
8, 8, renal arteries; 0, 9, common iliac arteries ; 10, middle sacral arteries; 11, one of
the phrenic arteries; +, coeliac axis; 12, gastric; 1.3, hepatic; 14, splenic artery; 15,
superior mesenteric ; IG, inferior mesenteric : 17, 17, spermatic or ovarian arter'ps.

118

Al^ATOMY FOR NUESES.

[Chap. X.

The common carotid arteries. — As the left common carotid
arises from tlie middle of the upper surface of the arch of the
aorta, while the right common carotid arises at the division of
the innominate, the left carotid is an inch or two longer than
the right. They ascend obliquely on either side of the neck

Fig. 90. — The Carotid, Subclavian, and Axillary Arteries. 1, commcn
carotid artery ; 2, internal carotid ; 3 and 18, external carotid ; 8, facial artery ; 22,
subclavian artery ; 28, axillary artery ; 33, commencement of brachial artery.

until, on a level with the upper border of the thyroid cartilage,
"Adam's apple," they each divide into tw^o great branches, of
which one, the external carotid, is distributed to the superficial
parts of the head and face, and the other, the internal carotid, to
the brain and eye. At the root of the neck the common carotids

Chap. X.]

THE VASCULAR SYSTEM.

119

are separated from each other by only a narrow interval, corre-
sponding with the width of the trachea; but as they ascend
they are separated by a much
larger interval, corresponding with
the breadth of the larynx and
pharynx.

The external carotid has eight
branches, which are distributed
to the throat, tongue, face, and
walls of the cranium.

The chief branches of the in-
ternal carotid are the ophthalmic
and cerebral arteries. A remark-
able anastomosis exists between
the cerebral arteries at the base of
the brain. The arteries are joined
in such a manner as to form a
complete circle, and this anasto-
mosis, known as the " circle of
Willis," both equalizes the circula-
tion of the blood in the brain, and
also provides, in case of destruction
of one of the arteries, for the blood
reaching the brain through the
other vessels.

The subclavian arteries. — The
right subclavian arises at the
division of the innominate, and
the left subclavian from the arcli
of the aorta. The sul^clavian
arteries are the first portions of a
long trunk which forms the main
artery of the upper limb, and which
is artificially divided for purposes
of description into three parts ;
viz. the subclavian, axillary, and
brachial arteries. The subclavian
artery passes a short way up the ^'"^^^y-

thorax into the neck, and then turns downwards to rest on the
first rib. At the outer border of the first rib it ceases to be called

Fig. 91. — Deep Anterior View
OF THE Arteries of the Arm,
Forearm, and Hand. A, biceps
muscle; 1, brachial artery; 4, radial
artery ; 6, deep palmar arch ; 8, ulnar

120 ANATOMY FOR NURSES. [Chap. X.

subclavian, and is continued as the axillary. It gives off large
branches to the back, chest, and neck.

The axillary artery passes through the axilla, lying to the
inner side of the shoulder joint and upper part of the arm. It
gives off branches to chest, shoulder, and arm.

The brachial artery extends from the axillary space to just
below the bend of the elbow, where it divides into the ulnar and
radial arteries. It may be readily located, lying in the depres-
sion along the inner border of the biceps muscle. Pressure
made at this point on the artery, from before backwards against
the humerus, will control the blood supply to the arm.

The ulnar artery, the larger of the two vessels into which the
brachial divides, extends along the side of the forearm into
the palm of the hand, where it terminates in the superficial
palmar arch.

The radial artery appears, by its direction, to be a continua-
tion of the brachial, although it does not equal the ulnar in size.
It extends along the front of the forearm as far as the lower
end of the radius, below which it turns round the outer border
of the wrist, descends between the bones of the thumb and fore-
finger, and passes forward into the palm of the hand. It ter-
minates in the deep palmar arch. The superficial and deep
palmar arches supply the hand with blood.

The thoracic aorta extends from the lower border of the fourth
dorsal vertebra, on the left side, to the opening in the diaphragm
below the last dorsal vertebra, and has a length of from seven
to eight inches. The branches, derived from the thoracic aorta,
are numerous, but small. They are distributed to the walls of
the thorax, and to the viscera contained within it.

The abdominal aorta commences about the lower border of the
last dorsal vertebra, and terminates below by dividing into the
two common iliac arteries. The bifurcation usually takes place
about half-way down the body of the fourth lumbar vertebra,
which corresponds to a spot on the front of the abdomen,
slightly below and to the left of the umbilicus. Its length is
about five inches.

The abdominal aorta gives off numerous branches, which may
be divided into two sets ; viz. those which supply the viscera,
and those which are distributed to the walls of the abdomen.
The former set consists of the cceliac axis, the superior mesenteric.

Plate V — The Abdominal Aorta and its Principal Branches. (Tiede-
mann) o, ensiform appendix; b, inferior vena cava and c, (Esophagus, passing
through diaphragm ; /', f, right and left kidneys, with the supra-renal bodies ; g, g
ureters ; h, urinary bladder ; k, rectum, divided near its upper end. 1, 1, abdominal
aorta- 2 2', and 3, 3', right and left inferior phrenic arteries; 4, coeliac axis; 5,
superior mesenteric artery; 6, 6, renal arteries; 7, 7, spermatic or ovarian arteries;
8, inferior mesenteric artery ; 10, 10, common iliac arteries ; 11, placed between
external and internal iliac arteries.

121

122

ANATOMY FOR NURSES.

[Chap. X.

the inferior mesenteric, the supra-renal, the renal, and the sper-
matic or ovarian arteries, while in the latter are included the

phrenic, the lumbar, and the
middle sacral arteries.

The coeliac artery, or axis,
is a short, wide vessel, usually
not more than half an inch in
length, which arises from the
front of the aorta, close to the
opening in the diaphragm. It
divides into three branches;
viz. the gastric, which supplies
the stomach ; the hepatic,
which supplies the liver; and
the splenic, which supplies the
spleen, and in part the stom-
ach and pancreas.

The superior mesenteric ar-
tery arises from the fore part
of the aorta, a little below
the coeliac axis. It supplies
the whole of the small intes-
tine beyond the first portion
(the duodenum) close to the
stomach, and half of the large
intestine.

The inferior mesenteric ar-
tery arises from the front of
the aorta, about an inch and
a half above its bifurcation,
and supplies the lower half
of the largfe intestine. Con-
tinned under the name of the
superior hemorrhoidal artery.

Fig. 92. -Iliac and Femoral ARTERiES.it also supplies the rectum.
2, common iliac artery ; 4, external iliac ; 8, . .

femoral artery. Poupart's ligament, which -•- '^^ renal arteries are 01
lies between 4 and 8, is removed. ^.^^gg gi^e, in proportion tO

the bulk of the organs which they supply. They arise from the
sides of the aorta, about half an inch below the superior mesen-
teric artery, that of the right side being generally a little lower

Chap. X.]

THE VASCULAR SYSTEM.

123

down than that of the left. Each is directed outwards, so as to
form nearly a right angle with the aorta. Before reaching the
kidney, each artery divides into four or five branches.

The ovarian arteries, corresponding to the spermatic arteries in
the male, arise close together from the front of the aorta, a little
below the renal arteries. They supply the ovaries, and, joined
to the uterine artery, — a branch
of the internal iliac, — also assist
in supplying the uterus. During
pregnancy the ovarian arteries
become considerably enlarged.

The common iliac arteries, com-
mencing at the bifurcation of the
aorta, pass downwards and out-
wards for about two inches, and
then each divides into the internal
and external iliac arteries.

The internal iliac artery (whence
arises the hypogastric in the
foetus) supplies branches to the
walls and viscera of the pelvis.

The external iliac artery forms
a large continuous trunk, which
extends downwards in the lower
limb to just below the knee : it
is named in successive parts of its
course external iliac, femoral, and
popliteal. The external iliac is
placed within the abdomen, and
extends from the bifurcation of
the common iliac to the lower
border of Poupart's ligament,
where it enters the thigh and is
named femoral.

The femoral artery lies in the upper three-fourths of the
thigh, its limits being marked above by Poupart's ligament,
and below by the opening in the great adductor muscle, after
passing through which the artery receives the name of pop-
liteal. In the first part of its course the artery lies along the
middle of the depression on the inner aspect of the thigh,

Fig. 93. — View of Popliteal
Artery. A, biceps muscle; D, D,
gastrocuemius ; /, popliteal artery.

124

ANATOMY FOR NUESES.

[Chap. X.

I— 1

known as Scarpa's triangle. In this situation the beating of

the artery may be felt, and the circulation through the vessel

may be most easily controlled by pressure.
The popliteal artery,
continuous with the fem-
oral, is placed at the back
of the knee ; just below
the knee joint it divides
into the anterior and
posterior tibial arteries.

The posterior tibial ar-
tery lies along the back
of the leg, and extends
from the bifurcation of
the popliteal to the
ankle, where it divides fflffiii'ji^^'l'i

into the internal and iSUm wiM''i-
external plantar arteries.
About an inch below
the bifurcation of the
popliteal, the posterior
tibial gives off a large
branch, the peroneal ar-
tery.

The anterior tibial ar-
tery, the smaller of the
two divisions of the
popliteal trunk, extends
along the front of the
leg to the bend of the
ankle, whence it is pro-
longed into the foot
under the name of the
dorsal artery. This

Fig. 94. — Deep view of unites with the external
and internal plantar ar-

THK Arteries of the back
OF THE Leg. 1, popliteal
artery; 6, division of pop- tcrics to form the plan

liteal into anterior and pos- ^ | j^- j^ supplies dorsal artery,

tenor tibial arteries ; S, pos- ^^ •'

terior tibial ; 9, peroneal. blood to the f OOt.-^

Fig. 95. — Anterior vie\iv
OF Arteries of the Leg
4, anterior tibial artery; 9

1 Drawing an outline of the aorta with its branches as an arterial tree will
greatly aid the student in mastering the arterial distribution.

Chap. X.]

THE VASCULAR SYSTEM.

125

Venous return. — The arteries begin as large trunks, which
gradually become smaller and smaller until they end in the
small capillary tubes, while the veins begin as small branches
which at first are scarcely distinguishable from the capillaries.
These small branches, receiving the blood from the capillaries
throughout the body, unite to form
larger vessels, and end at last by
pouring their contents into the
right auricle of the heart through
two large trunks-, the superior vena
cava and the inferior vena cava.
The veins, however, which bring
back the blood from the stomach,
intestines, spleen, and pancreas,
do not take the blood di recti 3^ to
the heart, they first join to form
a large trunk, — the portal vein,
— and carry this blood to the
liver. When the portal vein enters
the liver, it breaks up into cap-
illaries, which, after branching
throughout the liver substance,
unite to form the hepatic veins:
by them the blood is conveyed
into the inferior vena cava. This
constitutes what is called the
portal circulation, and is the only
example in the body of a vein
breaking up into capillaries.

The veins consist of a super-
ficial and a deep set, the former
running immediately beneath the

skin and hence named subcuta- Fig.96.— Arteries of the Foot.

neOUS, the latter usually aCCOm- i' anterior tibial artery; 6, 7, 8,

'' branches of dorsal artery.

panying the arteries and named

vence comites. These two sets of veins have very frequent com-
munications with each other, and the anastomoses of veins
are always more numerous than those of arteries.

The systemic veins — that is, all the veins of the body with
the exception of the pulmonary and portal veins — are naturally
divided into two groups.

126

ANATOMY FOR NURSES.

[Chap. X.

I. Those from which the blood is carried to the heart by the
superior vena cava, viz. the veins of the head and neck and

upper limbs, together with those of
the spine and a part of the walls of
the thorax and abdomen. In this
group we may include the veins of
the heart, which, however, pass directly
into the right auricle without entering
the superior vena cava.

II. Those from which the blood is
caiTied to the heart by the inferior vena
cava ; viz. the veins of the lower limbs,
the lower part of the trunk, and the
abdominal viscera.

1. The blood returning from the
head and neck flows on each side into
two principal veins, the external and
internal jugular.

The external jugular commences near
the angle of the jaw by the union of
two smaller veins, and descends almost
vertically in the neck to its termination
in the subclavian vein.

The internal jugular, receiving the
blood from the cranial cavity, descends
the neck close to the outer side of the
internal and common carotid arteries.
It unites at a right angle with the
subclavian to form the innominate vein.^

The blood from the upper limbs is
returned by a superficial and deep set
of veins. The superficial are much
larger than the deep, and take a greater

Fia. 97. — Sketch of the
PRINCIPAL Venous Trunks.
1, superior vena cava; 2, in-
ferior vena cava ; .'5, right sub-
clavian and innominate veins;
4, left subclavian and innomi-
nate veins ; 5, 5, right and left
internal jugular veins; 8, right
azygos vein ; 10, left azygos
vein ; 13, 13, common iliac veins ;
14, 14, sacral veins.

1 Note on Venous Circulation of the
Skull. — The blood from the skull is returned
from the smaller veins to the internal jugular
veins by channels which are not strictly veins,
but sinuses. These sinuses are spaces left be-
tween the layers of the dura mater, and are lined
by a continuation of the lining membrane of the
veins.

Chap. X.]

THE VASCULAR SYSTEM.

127

share in returning the blood, especially from the distal portion
of the limb. The deep veins accompany the arteries, and are
called by the same names. Both
sets are provided with valves, and
terminate in the subclavian vein.

The blood from the spine, walls
of thorax, and abdomen is chiefly
returned by the right and left azygos
veins, which are longitudinal vessels
resting against the thoracic portion
of the spinal column. They com-
municate below with the inferior
vena cava, and terminate above in the
superior vena cava : they thus form a
supplementary channel by which blood
can be conveyed from the lower part
of the body to the heart in case of
obstruction in the inferior vena cava.

The innominate veins, commencing
on each side by the union of the sub-
clavian and internal jugular, behind
the inner end of the clavicle, transmit
the blood returning from the head
and neck, the upper limbs, and a
part of the thoracic wall ; they end
below by uniting to form the superior
vena cava. Both innominate veins
are joined by many side tributaries :
they also receive, at the junction of
the subclavian and internal jugular,
the lymph ; on the left side from the
thoracic duct, and on the right from
the riglit lymphatic duct.

The superior or descending vena cava

/. 11 ,, . p.i •1. Fig. 98. — Superficial veins

is formed by the union of tlie right of Lower Extremity. -l, veins

and left innominate veins. It is about of the foot; 2, internal saphenous

,, • 1 1 1 • . .1 vein: .", superficial veins of calf ;

three inches long, and opens into the 4, superficial veins of thigh,
right auricle, opposite the third rib.

II. The blood from the lower limbs is also returned by a
superficial and deep set of veins. They are more abundantly

128 ANATOMY FOR NURSES. [Chap. X.

supplied with valves than the veins of the upper limbs. The
deep veins accompany the arteries. The two largest superficial
veins are the internal or long saphenous, and the external or short
saphenous vein. The internal saphenous extends from the ankle
to within an inch and a half of Poupart's ligament. It lies
along the inner side of the leg and thigh, and terminates in the
femoral vein. The external saphenous arises from the sole of
the foot, and, passing up the back of the leg, ends in the deep
popliteal.

Both the deep and superficial veins of the lower limbs pour
their contents into the external iliac. The blood is returned
from the pelvis by the internal iliac veins, which, uniting with
the external iliac, form the two common iliac veins. They
extend from the base of the sacrum to the fourth lumbar
vertebra, and then the two common iliacs unite to form the
inferior vena cava.

The inferior or ascending vena cava returns the blood from
the lower limbs, pelvis, and abdomen. It begins at the junction
of the two common iliacs, and thence ascends along the right
side of the aorta, perforates the diaphragm, and terminates by
entering the right auricle of the heart. The inferior vena cava
receives many tributaries, the chief of which are the lumbar,
ovarian, renal, and hepatic veins.

The pulmonary artery. — The pulmonary artery conveys the
dark venous blood from the right side of the heart to the
lungs. The main trunk is a short, wide vessel (diameter
30 mm.) which arises from the right ventricle and runs for
a distance of two inches backwards and upwards (vide Fig. 78).
Between the fifth and sixth dorsal vertebrse, it divides into
two branches, — the right and left pulmonary arteries, — which
pass to the right and left lungs.

The pulmonary veins. — The pulmonary veins convey the red
arterial blood from the lungs to the left side of the heart.
They are usually four in number, two from each lung. The
two left veins frequently terminate in the left auricle by a
common opening. The pulmonary veins have no valves.

Chap. X.]

THE VASCULAR SYSTEM.

129

PLAN OF ARTERIAL DISTRIBUTION.

r R, and L. coronary,

r R- c. carotid.
i- I Innominate R. subclavian - ax-

Arch of Aorta I ,-ii„ , , . ,

\ ^ lUary — brachial.

L. c. carotid.

L L. subclavian.

n.

Thoracic

Aorta

IIL
Abdominal
Aorta

Common Iliac
arteries.

r Intercostal.
J Pericardial.
1 Bronchial.

I CEsophageal.

f Gastric.
Coeliac axis j Hepatic.

^ Splenic.
Sup. mesenteric.
Inf. mesenteric.
Renal.
Ovarian.
Phrenic.
Lumbar.
. Sacral.

f Superficial
Ulnar j palmar
I- arch.
(-Deep
Radial paj^^gj,

I. arch.

oral — popliteal I Ant. tibial, dorsal. J ^rch.

I- Int. iliac.

PLAN OF VENOUS RETURN.

The veins from the
head, face, and neck >
unite to form J

The deep-seated and
superficial veins
from the upper
limbs unite to form j

External [the external jugular terminates in sub-
I clavian veins] and internal jugular veins.

Right and
left subcla-
vian veins.

The deep-seated and •]
superficial veins External
from the lower [ iliacs
limbs unite to form J

The veins from pelvis 1 Internal
unite to form j iHacs

The internal ju-
gular unites
with the sub-
clavians to
form

Right 1
and left

•_ y VENA

Sup.

innomi-
nate

J CAVA.

. Right and left 1 Inferior vena
common iliacs / cava.

130 ANATOMY FOR NURSES. [Chap. X.

The right and left azygos veins connected with the inferior vena cava
below, and superior vena cava above, form a supplementary channel.

The veins from stomach, spleen, pancreas, and intestines unite to form
the portal vein, which breaks up into capillaries in the liver, and is returned
to the inferior vena cava by the hepatic veins.

CHAPTER XL

THE VASCULAR SYSTEM CONTINUED: THE GENERAL CIRCULA-
TION; THE PULSE AND ARTERIAL PRESSURE; VARIATIONS
IN THE CAPILLARY CIRCULATION.

The general circulation of the blood. — At each beat of the heart
the contraction of the ventricles drives a certain quantity of
blood, probably amounting to four ounces, with great force into
the aorta and pulmonary artery. The aorta delivers this sup-
ply of blood from the left ventricle, through its branches, to the
capillaries in all parts of the body. In the capillaries, the
blood is robbed of oxygen and other constituents necessary for
the life and growth of the tissues, is loaded with carbon diox-
ide and other waste matters, and is returned by the superior
and inferior vense cavoe to the right side of the heart. From
the right side of the heart, the blood is conveyed by the pul-
monary artery to the capillaries in the lungs,i where it receives
a fresh supply of oxygen and gives up the carbon dioxide with
which it has become loaded during its circulation through the
body. Thus a double circulation is constantly and simultane-
ously going on, the artery from the left side of the heart send-
ing the pure oxygenated blood to the general system, and the
artery from the right side of the heart sending the impure blood
to the lungs for purification. The more extensive circulation
is usually called the general or systemic circulation, while the
lesser circulation is generally known as the pulmonary.

Some features of the arterial circulation. — The flow of blood
into the arteries is most distinctly remittent ; sudden, rapid

1 It is to be observed that the lungs receive blood from two sources. From
the bronchial arteries (branches of the aorta) they receive arterial blood, by
means of which the tissues of the lungs are nourished ; and from the pulmonary
artery they receive venous blood, which, in passing through the lungs, is arte-
rialized by exposure to the air.

131

132

ANATOMY FOR NURSES.

[Chap. XL

discharges alternating with relatively long intervals during
which the arteries receive no blood from the heart. Every time
the heart beats just as much blood flows from the veins into the

right auricle as escapes
from the left ventricle into
the aorta, but this inflow
is much slower and takes
a longer time than the
discharge from the ven-
tricles.

The pulse. — When the
finger is placed on an ar-
tery a sense of resistance
is felt, and this resistance
seems to be increased at
intervals, corresponding to
the heart-beat, the artery
at each heart-beat being
felt to rise up or expand
under the finger. This
constitutes the pulse ; and,
in certain arteries which
lie near the surface, this
pulse may be seen with the
eye. When the finger is
placed on a vein very lit-
tle resistance is felt ; and,
under ordinary circum-
stances, no pulse can be
perceived by the touch or
by the eye.

Fig 99.-DIAGRAM OF Circulation, i.left ^^ g^^^j^ expansion of an
side of heart; R, right side of heart; a, a, a, ar- _ •••

terial system; b, b, capillaries; c, c, c, veins; artery is produced by a
^^im., alimentary caiial; 7.W., liver; p, portal ,.• r .1 1 .

vein; //, hepatic vein ; /.j/wpA., lymphatic duct contiacuon OI tne lieaiT,

and tributaries; Pulni., lungs; Pa, pulmonary the pulsC, aS felt in any
artery; Pw, pulmonary vein. r- • t

superficial artery, is a con-
venient guide for ascertaining the character of the heart's action.^

1 The nurse should practice "taking the pulse " in the following arteries : —
carotid, temporal, radial, dorsalis pedis,

facial, brachial, femoral,

Chap. XI.] THE VASCULAR SYSTEM. 133

The radial artery at the wrist, owing to its accessible situation,
is usually employed for this purpose. Any variation in the
frequency, force, or regularity of the heart's action is indicated
by a corresponding modification of the pulse at the wrist.

The average frequency of the pulse in man is seventy-two
beats per minute. This rate may be increased by muscular
action. Even the variation of muscular effort entailed between
the standing, sitting, and recumbent positions will make a
difference in the frequency of the pulse of from eight to ten
beats per minute. Age has a marked influence in the same
direction. According to Carpenter, the pulse of the foetus is
about 140, and that of the newly born infant 130. During the
first, second, and third years, it gradually falls to 100 ; by the
fourteenth year to 80 ; and is reduced to the adult standard by
the twenty-first year. At every age, mental excitement may
produce a temporary acceleration, varying in degree with the
peculiarities of the individual.

As a rule, the rapidity of the heart's action is in inverse ratio
to its force. A slow pulse, within physiological limits, is
usually a strong one, and a rapid pulse comparatively feeble.
The same is true in disturbance of the heart's action in disease ;
the pulse in fever, or other debilitating affections becoming
weaker as it grows more rapid.

Arterial tension. — When an artery is severed, the flow of
blood from the proximal end (that on the heart side) comes in
jets corresponding to the heart-beats, though the flow does not
cease between the beats. The larger the artery, and the nearer
to the heart, the greater the force with which the blood issues,
and the more marked the remittance of the flow.

When a corresponding vein is severed, the flow of blood,
which is chiefly from the distal end (that away from the heart),
is not remittent, but continuous ; the blood comes out with
comparatively little force, and " wells up," rather than '' spurts
out."

The continuous uninterrupted flow of blood in the veins is
caused by the elasticity of the arterial walls. On account of
the small size of the capillaries and small arteries the blood
meets with a great deal of resistance in passing through them ;
and, in consequence, the blood cannot get through the capilla-
ries into the veins so rapidly as it is thrown into the arteries by

134 ANATOMY FOR NURSES. [Chap. XL

the heart. The whole arterial system, therefore, becomes over-
distended with blood, and the greater the resistance, the greater
the pressure on, and distension of, the arterial walls. The fol-
lowing illustration will explain how the elasticity of the arter-
ies enables them to deliver the blood in a steady flow to the
veins through the capillaries.

If a syringe be fastened to one end of a long piece of elastic
tubing, and water be pumped through the tubing, it will flow
from the far end in jerks. But if we stuff a piece of sponge
into this end of the tubing, or offer in any way resistance to
the outflow of the water, the tubing will distend, its elasticity
be brought into play, and the water flow from the end not in
jerks, but in a stream, which is more and more completely con-
tinuous the longer and more elastic the tubing.

Substitute for the syringe the heart, for the sponge the cap-
illaries and small arteries, for the tubing the whole arterial sys-
tem, and we have exactly the same result in the living body.
Through the action of the elastic arterial walls the separate jets
from the heart are blended into one continuous stream. The
whole force of each contraction of the heart is not at once
spent in driving a certain quantity of blood onwards ; a part
only is thus spent, the rest goes to distend the elastic arteries.
But during the interval between that beat and the next, the
distended arteries are narrowing again, by virtue of their elas-
ticity, and so are pressing the blood on in a steady stream into
the capillaries with as much force as they were themselves dis-
tended by the contraction of the heart.

The degree of tension to which the arterial walls are sub-
jected depends upon the force of the heart-beat, and upon the
resistance offered by the smaller arteries, the normal general
blood pressure being mainly regulated by the " tone " of the
minute arteries.

Variations in the capillary circulation. — Most of the changes
in the capillary circulation are likewise dependent upon the
condition of the smaller arteries. When under certain nervous
influences they contract, the blood supply to the capillaries is
greatly lessened ; when, on the other hand, they dilate, the
blood supply is greatly increased. The phenomena produced
by these local variations in the blood supply of certain parts are
very familiar to us ; the redness of skin produced by an irritat-

Chap. XL] THE VASCULAR SYSTEM. 135

ing application, the blushing or paling of the face from mental
emotion, the increased flow of blood to the mucous membranes
during digestion, being all instances of this kind.

But the condition of the capillary walls themselves also exerts
an influence upon the capillary circulation. If some trans-
parent tissue, preferably the web of a frog's foot, be watched
under the microscope, it will be observed that in the small
capillaries the corpuscles are pressed through the channel in
single file, each corpuscle as it passes occupying the whole bore
of the capillary. In the larger capillaries and smaller arteries
and veins the red corpuscles run in the middle of the channel,
forming a coloured core, between which and the sides of the
vessels is a colourless layer containing no red corpuscles, and
called the " peripheral zone." In the peripheral zone are fre-
quently seen white corpuscles, sometimes clinging to the walls
of the vessel, sometimes rolling slowly along, and in general
moving irregularly, stopping awhile, and then suddenly moving
on again.

These are the phenomena of the normal circulation, but a
different state of things sets in when the condition of the blood-
vessels is altered in inflammation. i If an irritant, such as a
drop of chloroform, be applied to the portion of transparent
tissue under observation, the following changes may be seen to
occur : the arteries dilate, the blood flows in greater quantity
and with more rapidity, the capillaries become filled with cor-
puscles, and the veins appear enlarged and full. This condition
of distension may pass away, and the blood-vessels return to
their normal state, the effect of the irritant having merely pro-
duced a temporary redness.

The irritant, however, usually produces a more decided
change. The white corpuscles begin to gather in the periph-
eral zones, and this takes place though the vessels still re-
main dilated and the stream of blood still continues rapid,
though not so rapid as at first. Each white corpuscle exhibits
a tendency to stick to the sides of the vessels, and, driven away
from the arteries by the stronger arterial current, becomes
lodged in the veins. Since white corpuscles are continually

1 The following account of the changes occurring in inflammation does not
strictly belong to a text-book on physiology, but I have ventured to introduce it,
as especially interesting to nurses, out of " Foster's Physiology."

136 ANATOMY FOR NURSES. [Chap. XL

arriving on the scene, the inner surface of the veins and cap-
illaries soon become lined with a layer of these cells. Now,
though the vessels still remain dilated, the stream of blood
begins to slacken, and the white corpuscles lying in contact
with the walls of the vessels are seen to thrust themselves
through the distended walls into the lymph spaces outside.
This migration of the white cells is accomplished by means of
their amoeboid movements. They thrust elongated processes
through the walls, and then, as these processes increase in size,
the body of the cell passes through into the enlarged process
beyond, the perforation appearing to take place in the cement
substance between the endothelial cells forming the walls of
the vessels. Through this migration, the lymph spaces around
the vessels in the inflamed area become crowded with white
corpuscles. At the same time the lymph not only increases in
amount, but changes somewhat in its chemical characters : it
becomes more distinctly and readily coagulable, and is some-
times spoken of as "exudation fluid." This change of the
lymph with the increased quantity, together with the dilated
crowded condition of the blood-vessels, gives rise to the swell-
ing which is one of the features of inflammation.

If the inflammation, now passes away, the white corpuscles
cease to emigrate, cease to stick so steadily to the sides of the
vessels, the stream of blood quickens again, the vessels regain
their ordinary caliber, and a normal circulation is re-established.
But this inflammatory condition, instead of passing off, may go
on to a further stage ; and, if this is the case, more and more
white corpuscles, arrested in their passage, crowd and block the
channels, so that, though the vessels remain dilated, the stream
becomes slower and slower, until at last it stops altogether, and
stagnation or " stasis " sets in. Tlie red corpuscles, in this con-
dition of things, are driven in among the white corpuscles, the
vessels are filled and distended with a mingled mass of red and
white corpuscles, and it may now be observed that the red cor-
puscles also begin to find their way through the distended and
altered walls of the capillaries into the lymph spaces outside.
This is called the diapedesis of the red corpuscles.

This stagnation stage of inflammation may be the beginning
of further mischief and of death to the inflamed tissue, but it,
too, may like the earlier stages, pass away.

Chap. XI.] THE VASCULAR SYSTEM. 137

General summary of the circulation. — The perfect circulation
of tlie blood is dependent upon certain factors, the chief of
which are : (1) the character of the heart-beat ; (2) the con-
traction and relaxation of the minute arteries ; (3) the elas-
ticity and extensibility of the arterial walls ; (4) the perfect
adjustment of the valves.

The character of the heart-beat is mainly determined by the
condition of its muscular substance, and any interference with
the nutrition of the heart leading to degeneration of its mus-
cular walls very seriously affects the heart's action.

The contraction and relaxation of the smaller arteries is under
the influence of the nervous system. The muscular tissue found
in the walls of these vessels is supplied with non-medullated
nerve-fibres. Stimulation of one set of these fibres (vaso-
constrictor) causes contraction of the muscle-fibres and con-
striction of the arteries ; stimulation of a second set (vaso-
dilator) causes a relaxation of the muscle-fibres, and dilatation of
the arteries. The widening and narrowing of these arteries not
only affects the local circulation in different parts of the body,
but the amount of resistance they oppose to the arterial impulse
also influences in some degree the character of the heart-beat.

The elasticity and extensibility of the arteries change with
the age of the individual. As we grow older the arterial walls
grow stiffer and more rigid, and become less well adapted for
the unceasing work they are called upon to perform. The valves
also show signs of age as years advance, and even if not injured
by disease, do not adjust themselves so perfectly as in early life.

Still, the heart has a marvellous facility for adjusting itself
to changed conditions, and the circulation of the blood may
go on for years with the integrity of the vascular mechanism
greatly impaired.

FcETAL Circulation. — The peculiarities of the fcetal cir-
culation, leaving details aside, are : the direct communication
between the two auricles of the heart through an opening
called the foramen ovale ; the communication between the pul-
monary artery and descending portion of the arch of the aorta
by means of a tube called the ductus arteriosus ; and the com-
munication between the placenta and the foetus by means of
the umbilical cord.

The arterial blood for the nutrition of the foetus is carried from

138 ANATOMY FOR NURSES. [Chap. XL

the placenta along the umbilical cord by the umbilical vein.
Entering the foetus at the umbilicus the blood passes upwards
to the liver and is conveyed into the inferior vena cava in two
different ways. The larger quantity first enters the liver, and
alone, or in conjunction with the blood from the portal vein,
ramifies through the liver before entering the inferior vena
cava by means of the hepatic veins. The smaller quantity of
blood passes directly from the umbilical vein into the inferior
vena cava by a tube called the ductus venosus.

In the inferior vena cava the blood from the placenta becomes
mixed with the blood returning from the lower extremities of
the foetus. It enters the right auricle and guided by a valve,
the Eustachian valve, passes through the foramen ovale into the
left auricle. In the left auricle it mixes with a small quan-
tit}^ of blood returned from the lungs by the pulmonary veins.
From the left auricle the blood passes into the left ventricle,
and is distributed by the aorta almost entirely to the upper
extremities. Returned from the upper extremities by the su-
perior vena cava the blood enters the right auricle and, passing
over the Eustachian valve, descends into the right ventricle,
and from the right ventricle into the pulmonary artery. As
the lungs in the foetus are solid, they require very little blood,
and the greater part of the blood passes through the ductus
arteriosus into the descending aorta, where, mixing with the
blood delivered to the aorta b}^ the left ventricle, it descends
to supply the lower extremities of the foetus, the chief portion
of this blood, however, being carried back to the placenta by
the two umbilical arteries.

From this description of the foetal circulation, it will be seen : —

1. That the placenta serves the double purpose of a respi-
ratory and nutritive organ, receiving the venous blood from
the foetus, and returning it again charged with oxygen and
additional nutritive material.

2. That the greater part of the blood traverses the liver
before entering the inferior vena cava ; hence the large size of
this organ at birth.

3. That the blood from the placenta passes almost directly
into the arch of the aorta, and is distributed by its branches to
the head and upper extremities ; hence the large size and per-
fect development of those parts at birth.

Plate VI. — Plan of F<i;tal Circulation. In this plan, the figured arrows rep-
resent the kind of blood, as -well as the direction -which it takes in the vessels. Thus,
arterial blood is iigured ; venous blood ; mixed (arterial and venous)

139

140 ANATOMY FOR NURSES. [Chap. XL

4. That the blood in the descending aorta is chiefly derived
from that which has already circulated in the upper extremities,
and, mixed with only a small quantity from the left ventricle,
is distributed to the lower extremities ; hence the small size and
imperfect development of these parts at birth.

Development of blood-vessels and corpuscles. — The blood-vessels and
red corpuscles are formed very early in the embryo. They are developed in
that portion of the primitive tissue called the mesoblast. The cells which
are to form the vessels become extended into processes of varying length,
"which grow out from the cells in two or more directions. The cells become

Fig. 100. — Isolated Capillary Network formed by the Junction of
Several Hollowed-out Cells, and containing Coloured Blood-corpuscles
IN A Clear Fluid, p, p, pointed cell-processes extending in different directions
for union with neighbouring capillaries.

united with one another, either directly or by the junction of their processes,
so that an irregular network is thus formed. Meanwhile the nuclei in the
cells multiply, and each nucleus surrounds itself with a small amount of
cell protoplasm. The corpuscles thus formed acquire a reddish colour, and
the protoplasmic network in which they lie becomes hollowed out into a
system of branched canals containing fluid, in which the nucleated coloured
corpuscles float. The protoplasmic walls of the vessels gradually change
into the flattened cells which compose the wall of the capillaries, and which
form the lining membrane of the arteries and veins. The remaining coats
of the larger vessels are developed later from other cells which apply them-
selves to the exterior of these tubes.

The first white corpuscles do not appear in the vessels so early as the
coloured ones. /They probably occur in the beginning as free cells and
wander in fronvthe outside.

The new vessels which form in the healing of wounds and in the restora-
tion of lost parts are produced by a process which is essentially the same as
above described. Blood-corpuscles, however, are not produced within them,
and it is stUl a matter of doubt as to where and how the red corpuscles
originate after birth. The white corpuscles are undoubtedly produced to a
large extent in the lymphatic nodes and other lymphoid structures.

I

CHAPTER XII.

VASCULAR SYSTEM CONCLUDED: LYMPHATIC VESSELS AND
LYMPH. LYMPHATIC GLANDS AND BODIES OF ALLIED
STRUCTURE.

The lymphatics. — In addition to the blood-vessels, which form
a continuous series of tubes for the passage of the blood, there
is another system of vessels in the body, which arise in the
different tissues, and pour their contents into the great veins
near the heart. The fluid which these vessels contain is ab-
sorbed from the tissues, and is called, from its transparent
watery appearance, " lymph " (lympha^ water), while the ves-
sels themselves are known as lymphatics.

The lymphatics may be divided into two sets : the lacteals,
which take up the milk-like fluid, called chyle, from the intes-
tines and carry it to the thoracic duct ; and the lymphatics
proper, which drain off the lymph from all parts of the body
and return it to the blood through the thoracic and right lym-
phatic ducts. These two sets of vessels, however, are alike in
structure, and will be considered together under the general
name of lymphatics.

The lymphatics are found in nearly all the tissues that are
supplied with blood. The larger trunks usually accompany the
deep-seated blood-vessels, and the smaller vessels form networks
in all parts of the body where the extensively distributed and
penetrative connective tissue is found.

The lymphatics have their origin in the connective tissue.
They may be said to begin as irregularly shaped or tubular
spaces in the areolae, and are distinguished from the lymph
spaces in the tissue outside by being lined with a single layer
of flat, transparent endotheloid cells having a peculiar den-
tated outline, by means of which they are readily recognized.

141

142

ANATOMY FOR NURSES.

[Chap. XII.

These united lympli vessels form very irregular labyrinths,
communicate freely with one another, and are altogether wider
than the blood capillaries. Tliey form the link between the
lymph in the tissues outside of themselves and the regular
lymphatic vessels into which tliey open.^

Fia. 101. — A Small Portion of a Lymphatic Plexus. Magnified 110 diam-
eters. (Ranvier.) L, lymphatic vessel ■with characteristic endothelium; C, cell
spaces of the connective tissue abutting here and there against the lymphatics.

In structure, the larger lymphatic vessels closely resemble
the veins, except that their walls are somewhat thinner and
more transparent, and are more abundantly supplied with
valves. The valves are constructed and arranged in the same
fashion as those of the veins, but follow one another at such
short intervals, that, when distended, they give the vessel a
beaded or jointed appearance. They are usually wanting in
the smaller networks. The valves allow the passage of mate-
rial from the smaller to the larger lymphatics, and from these
into the veins, and obstruct the flow of anything in the oppo-
site direction. The lymphatics do not carry to the tissues.
Their office is to carry away from the tissues into the veins all
the material the tissues do not need.

1 The serous cavities may be regarded as expanded lymph spaces, as they
open by means of their stomata into the lymphatics, and the fluid v^'hich
moistens their surfaces is really lympb and not serum.

Chap. XII.] THE VASCULAR SYSTEM. 143

The lymphatics, having attained a certain size, do not unite
into larger and larger trunks, but continue of the same diameter
until they finally enter two trunks or ducts through which their
contents are poured into the veins. The lymphatics from the
right arm, and right side of the head, neck, and upper part of
the trunk, enter the right lymphatic duct. The vessels from
the rest of the body, including the lacteals, or lymphatics of the
intestines, enter the thoracic duct. As we have stated else-
where (page 127), these ducts pour their contents into the blood
at the juhction of the internal jugular and subclavian veins.

The lymph, like the blood in the veins, is returned from the
limbs and viscera by a deep and by a superficial set of vessels.
In their course from origin to termination most of the lym-
phatics pass through small masses of tissue, called lymphatic
glands, a description of which will be given later on.

The thoracic duct. — The thoracic duct, from fifteen to eigh-
teen inches (381 to 457 mm.) long in the adult, extends from
the second,lumbar vertebra to the root of the neck. It lies in
front of the bodies of the vertebriB gradually inclining towards
the left until, when on a level with the seventh cervical verte-
bra, it turns outwards and arches downwards and forwards to
terminate in the angle formed by the junction of ^he left inter-
nal jugular and subclavian veins. The size is usually compared
to that of a goose quill. It is dilated below where it receives
the lymphatics from the lower limits and the chyle from the
lacteals, the dilatation being known as the receptaculum chi/li,
receptacle of the chyle. The duct is provided with valves,
and in other respects closely resembles the larger lymphatics
in structure. It is often alternately contracted and enlarged
at irregular intervals.

The right lymphatic duct is a short vessel usually from a quar-
ter to half an inch (6.3 to 12.7 mm.) in length. It pours its
contents into the blood at the junction of the right internal
jugular and subclavian veins.

The lymph. — The lymph is blood minus certain constituents.
When examined with the microscope, it is seen to consist of a
clear liquid with corpuscles floating in it. The liquid part
resembles tlie plasma of tlie blood in its composition, except
that it contains relatively more water and less solids. It clots
when removed from the body, though not so firmly as the

144 ANATOMY FOE NURSES. [Chap. XIL

blood. The lymph corpuscles, usually called leucocytes, agree
in their characters with the white corpuscles of the blood.
They vary in number in different parts, being more numerous
in the lymph which has passed through the lymphatic glands
than in that which enters these bodies, thus indicating the lym-
phatic glands as a source of these corpuscles.

The chyle in the lacteals during digestion has a white aspect
dependent upon the fatty particles absorbed from the food, and
suspended in it like oil globules in milk. After fasting the
lacteals contain lymph which differs very little from the lymph
found in the ordinary lymphatics.

The lymph, broadly speaking, is blood minus its red corpuscles.
The chyle is lymph plus a very large quantity of minutely
divided fat.

Movements of the lymph. — The onward progress of the lymph
from the tissues to the veins is maintained chiefly by three
things. (1) The difference of the pressure upon the lymph in
the tissues, and the pressure in the large veins of the neck. As
we have already seen in our last chapter the pressure exerted
upon the blood in the capillaries is greater than that exerted
upon the blood in the veins. This pressure in the smaller blood-
vessels is communicated through the blood-plasma to the lymph,
and thus, though the lymph is not subjected to the same amount
of pressure as the blood in the capillaries, it still stands at a
higher pressure than the blood in the veins. We may consider
the lymphatics to form a system of vessels leading from a region
of higher pressure, viz. the lymph-spaces of the tissues, to a
region of lower pressure, viz. the interior of the large veins of
the neck. (2) On account of the numerous valves in the
lymphatics every pressure upon the tissues in which they lie
will, by compressing the vessels, cause an outward flow of their
contents. Active muscular exercise and the manipulation of
the tissues, as practised in massage, markedly affect the lymph
flow. (3) During each inspiration the pressure on the thoracic
duct is less than on the lymphatics outside the thorax, and the
lymph is accordingly "sucked" into the duct. During the
succeeding expiration the pressure on the thoracic duct is in-
creased, and some of its contents, prevented by the valve from
escaping below, are pressed out into the veins.

The lymph in the various lymph-spaces of the body varies in

Chap. XII.] THE VASCULAR SYSTEM. 145

amount from time to time, but under normal circumstances,
never exceeds certain limits. Under abnormal conditions, these
limits may be exceeded, and the result is known as cedema or
dropsy. Similar excessive accumulations may also occur in the
larger lymph-spaces, the serous cavities.

The possible causes of oedema are, on the one hand, an ob-
struction to the flow of lymph from the lymph-spaces, and on
the other hand, an excessive transudation, the lymph gathering
in the lymph-spaces faster than it can be carried away by a
normal flow. CEdema is almost always due to the latter cause,
viz. excessive transudation.

The inflammatory oedema, due to changes in the walls of the
blood-vessels, we have already touched on in speaking of the
capillary circulation. In this kind of oedema the transudation
is, besides being crowded with migrating corpuscles, more dis-
tinctly coagulable than ordinary lymph. Allied to this inflam-
matory cedema is the "effusion," which appears in the serous
cavities when they are inflamed, as in pleurisy and peritonitis.

Functions of the lymph. — The lymph derived from the blood
delivers to the elements of the tissues the material each element
needs to maintain its functional activity, and returns to the
blood the products of this activity, which products may be
simple waste, or matters capable of being made use of by some
other tissue. There is thus a continual interchange going on
between the blood and the lymph. How this interchange
is effected may be partially understood by the following
illustration.

If a tumbler be completely divided vertically into two com-
partments by a moist piece of membrane, and a watery solution
of common salt be placed in one compartment, and a watery
solution of sugar in the other, it will be found after a time that
some of the salt has found its way into the solution of sugar,
and, vice versa, some of the sugar into the salt solution. Such
an interchange is said to be due to diffusion ; and if the process
were allowed to go on for some hours, the same proportion of
salt and sugar would be found in the solutions on each side
of the dividing membrane. So in the living body. The lymph,
originally like the blood-plasma (it is blood-j^lasma forced to
transude through the capillaries by the pressure of the blood),
becomes altered by the metabolic changes of the tissues which

146

ANATOMY FOR LUESES. [Chap. Xll.

it bathes, and we have two different fluids, separated by the
moist membrane which forms the walls of the blood-vessels, —
the lymph in the tissues outside the walls of the capillaries
and the blood inside the capillary walls, — and the same con-
ditions may be said to exist as in the salt and sugar solutions

just spoken of. And now the same
phenomena take place ; for though
the pressure is higlier in the blood-
vessels than in the lymph outside,
some of tlie constituents of the lymph
pass into the blood by the process of
diffusion.

These constituents, which, as we
cannot too often emphasize, are prod-
ucts resulting from the activity of
the tissues, are carried away by the
blood to other tissues, which will
either make use of them, or, as in
the kidneys, take them up to make
excretory fluids, and so remove them
from the body.

In consequence of the different
wants and wastes of different tissues
at different times, both the lymph
and blood must vary in composition
in different parts of the body. But
the loss and gain is so fairly bal-
anced that the average composition
is pretty constantly maintained. The
blood, on account of the higher press-
ure, loses more liquid to the lymph
than it receives back, but this ex-

„ ,^„ ^ cess is returned back asrain to the

Fig. 102. — Lymphatics and i i j i i .

Lymphatic Glands of Axilla blood by the lymphatics when they

AND Arm. empty their contents into the veins.

Lymphatic glands.^ — The lymphatic glands are small, solid

bodies, placed in the course of the lymphatics through which

1 Lymph nodes is the more appropriate name for these structures, but the
term " lymphatic glands " being still so generally used, it has been thought best
for the present to retain it in the text.

Chap. XII.] THE VASCULAR SYSTEM.

147

the contents of most of these vessels have to pass in their prog-
ress towards the thoracic and right lymphatic ducts. These
bodies are collected in numbers alongside of the great muscles
of the neck, and also in the thorax and abdomen, especially in
the mesentery, where they are called the mesenteric glands, and
alongside of the aorta, vena cava inferior, and the iliac vessels.
A few, usually of small size, are found on the external parts of
the head, and considerable groups are situated in the axilla,
and also in the groin where they receive the name of inguinal
glands. Some three or four lie on the popliteal vessels, and
usually one is placed a little below the knee, but none farther
down. In the arm they are found as low as the elbow joint.

The size of the lymphatic glands is very various, some being
not much larger than a hemp seed, and others as large as an al-
mond, or even larger than this. In shape, they are usually oval.

A lymphatic gland is covered by an envelope, or capsule, of
connective and muscular tissue. This capsule sends fibrous

Fio. 103. — Diagrammatic Section of Lymphatic Gland. (Sharpey.) a.L,
afferent lymphatic: e.I.. efferent lymphatic; c, capsule, or envelope; </-, trabeculse ;
^5, lymph-sinus; l.h, pulpy substance of gland.

bands (trahec\dce) into the substance of the gland, dividing the
exterior portion into more or less regular compartments, and
the interior into irregular labyrinths. This framework is occu-

148

ANATOMY FOR NURSES.

[Chap. XII.

pied by reticular or lymphoid tissue,^ the fine meshes of which
are filled with leucocytes. Between this pulpy substance of the
gland and the skeleton framework there is a narrow space (left
white in the diagram) which looks as if the pulp had originally
filled the framework and then shrunk away slightly on all sides.
The spaces thus left form channels for the passage of the lymph,
which, entering the more convex surface by afferent vessels,
issues, after circulating through the gland, by efferent vessels
below. In its passage through the gland the lymph takes up
fresh leucocytes, which are continually multiplying by cell
division in the glandular substance. The lymphatic glands are
plentifully supplied with blood.

Solitary follicles and Peyer's patches. — Closely connected with
the lymphatic vessels in the intestines are small, rounded bodies

Fig. 104. — Vertical Section of a Portion of a Peter's Patch, with Lac-
teal Vessels Injected, a, villi, with their lacteals coloured black ; d, surface of
rounded follicle, or solitary gland ; e, central part; /, ff, h, i, and k, lymph-channels,
or lacteal vessels, coloured black.

of the size of a small pin's head, called solitary glands or follicles.
These bodies consist of a rounded mass of fine lymphoid tissue,
the meshes of which are crowded with leucocytes. Into this
mass of tissue one or more small arteries enter and form a

1 Reticular or lymphoid tissue is that variety of connective tissue in which
the branched connective tissue cells unite to form delicate networks. The
meshes of the network are occupied by fluid in which the leucocytes often, in
large numbers, wander to and fro.

Chap. XII.] THE VASCULAR SYSTEM. 149

capillary network, from which the blood is carried away by one
or more small veins. Surrounding the mass are lymph channels
which are continuous with the lymphatic vessels in the tissue
below.

A Peyer's patch, or " agminated gland," as it is often called, is
simply a collection of these follicles. A well-formed Peyer's
patch consists of fifty or more of these solitary follicles, ar-
ranged in a single layer, close under the epithelium of the
intestinal mucous membrane, and stretching well down into
the tissue beneath. These patches are circular or oval in shape,
and from twenty to thirty in number. They are largest and
most numerous in the portion of the intestine called the ileum.
They increase in size during digestion.

The tonsils are two thick masses of lymphoid tissue, placed
one on each side of the fauces or throat, into which they pro-
ject. They are covered by stratified epithelium, and their sur-
faces are pitted with apertures which lead into recesses or crypts
in the substance of the tissue.

The spleen. — The spleen differs in many important particu-
lars from lymphatic glands, but may be conveniently studied in
conjunction with them, as it resembles these glands in structure,
and is possibly connected functionally with the blood.

Like the lymphatic glands, the spleen is covered by a fibrous
and muscular capsule which sends fibrous bands to form a net-
work in the interior of the oraran. In the meshes of the fibrous
framework lies a soft pulpy substance containing a large
amount of blood, and, therefore, of a deep red colour. This
soft, red pulp is dotted with whitish specks, which are small
masses of lymphoid tissue, and are called the Malpighian cor-
puscles of the spleen.

The blood supplied to the spleen appears to escape from the
minute subdivisions of the arteries into the red pulp before
entering the exceedingly thin-walled veins by which it is con-
veyed from the gland. The pulp contains numerous red cor-
puscles, and many bodies which appear to be red corpuscles in
process of decay or destruction, and it is surmised that the red
corpuscles are in some way destroyed, and that additional white
corpuscles are formed, within the spleen.

The spleen is covered by a portion of the peritoneum, the
serous membrane covering the viscera of the abdomen, and

150 ANATOMY FOR NURSES. [Chap. XII.

lies upon the left side of the stomach, in tlie abdominal cavity.
It is an elongated, flat body, varying greatly in size at different
periods of life. The size is increased during and after diges-
tion, and is always large in well-fed, and small in starved,
animals. In certain diseases, and more especially in typhoid
and malaria, a temporary enlargement takes place. In pro-
longed or chronic malaria, a permanent enlargement of the
spleen occurs, and forms the so-called "ague cake."

CHAPTER XIII.

THE RESPIRATORY APPARATUS: LARYNX; TRACHEA; LUNGS.
RESPIRATION; EFFECTS OF RESPIRATION UPON THE AIR
WITHIN THE LUNGS, UPON THE AIR OUTSIDE THE BODY,
UPON THE BLOOD; MODIFIED RESPIRATORY MOVEMENTS.

The respiratory apparatus. — Respiration is the main process
by means of which the body is supplied with oxygen and re-
lieved of carbon dioxide.

A respiratory apparatus consists essentially of a moist and per-
meable membrane, with blood-vessels containing carbon dioxide
on one side, and air or fluid containing oxygen on the other.
In most aquatic animals, the respiratory organs are external in
the form of gills ; in terrestrial or air-breathing animals, the
respirator}^ organs are situated internally under the form of
lungs, and are placed in communication with the external air
by a tube or windpipe.

In man, the respiratory apparatus may be conveniently di-
vided into the larynx, trachea, and lungs.

The larynx. — The larynx is situated between the base of the
tongue and the top of the trachea, in the upper and front part
of the neck. Above and behind lies the pharynx, which opens
into the oesophagus or gullet, and on either side of it lie the great
vessels of the neck.

The larynx is made up of nine pieces of cartilage, united
together by ligaments, and moved by numerous muscles. It is
lined throughout by mucous membrane,^ which is continuous
abovf with that lining the pharynx, and below with that lining
the trachea. In form, the larynx is narrow and rounded below

^ Mucous membranes resemble the skin in structure, and may be said to
form an internal skin for the cavities of the body which open exteriorly. They
always have a basis of connective tissue, are lined with epithelium, and secrete
a sticky substance called mucus. For a further description, see page 166.

151

152

ANATOMY FOR NURSES.

[Chap. XIII.

where it blends with the trachea, but broad above, and shaped
somewhat like a triangular box, with flat sides and prominent
ridge in front. This prominence, popularly called " Adam's
apple," is formed by the union of the two largest pieces of
cartilage (the thyroid) of which the larynx is composed.

Across the middle of the larynx is a transverse partition,

formed by two folds of the lining
mucous membrane, stretching from
side to side, but not quite meeting
in the middle line. They thus
leave in the middle line a chink or
slit, running from front to back,
called the glottis or rima glottidis.
Imbedded in the mucous mem-
branes at the edges of the slit are
fibrous and elastic ligaments, which
strengthen the edges of the glottis
and give them elasticity. These
ligamentous bands, covered with
the mucous membrane, are firmly
attached at either end to the car-
tilages of the larynx, and are
called the vocal cords. The space
left between their edges, the glottis,
varies in shape and size, according
to the action of the muscles upon
the laryngeal walls. When the
MENT OF Gullet and Larynx, as larynx is at rest during quiet

EXPOSED BY A Section A LITTLE TO , , . , 1 ,,••», 1 1

THE Left OF THE Median Plane OF breathmg, the glottlS IS V-shaped;
THE Head, a, vertebnu; 6, gullet; during a deep inspiration, it be-

c, trachea; d, larynx; e, epiglottis; " i -i n •

/, soft palate; g, opening of Eus- comes almost round; wJnle, during
tachian tube; k, tongue; I, hard ^j-^g production of a high note, the

palate ; o, p, q, inferior turbinate i <• i ^

bones of left nasal chamber. edges of the cords approximate so

closely as to leave scarcely any
opening at all. The glottis is protected by a leaf-shaped lid of
fibro-cartilage, called the epiglottis, which shuts down upon the
opening during the passage of food or other matters into the
oesophagus.

The vocal cords produce the voice. A blast of air, driven by
an expiratory movement out of the lungs, throws the two

— The Mouth, Nose, and
WITH THE Commence-

Chap. XIII.]

KESPIRATION.

153

elastic cords into vibrations. These impart their vibrations to
the column of air above them, and so give rise to the sound
which we call the voice.

The larynx is placed in communication with the external air
by two channels : the one, supplied by the nasal passages, is
always open ; the other, furnished by the mouth, can be opened
and closed at will.
One advantage of this
arrangement is, that
when exposed to a
very cold temperature,
we can close our
mouths and breathe
through the nasal pas-
sages, which, being nar-
row, thickly lined, and
freely supplied with
blood - vessels, warm
the air before it reaches
the lungs.

The trachea. — The
trachea or windpipe is
a fibrous and muscu-
lar tube, the walls of
which are strengthened
and rendered more
rigid by hoops of car- Fig. lUU. — The Larynx as seen by Means of
tilace embedded in the ^^^ Laryngoscope in Different Conditions
* . of the Glottis. A, while singing a high note ; B,

llbrOUS tissue. ihese in qniet breathing; C, during a deep inspiration.
hoODS are C-shaned ^' ^^^^ "^ tongue ; e, upper free edge of epiglottis ;
■'■, . ^'> cushion of the epiglottis; p/i, part of anterior

and incomplete behind, wall of pharynx; cv, the true vocal cords; cvs, the
the cartilaginous rings ^^^^^^^cal cords; rr, the trachea with its rings; b,
o o the two bronchi at their commencement.

being completed by

bands of plain muscular tissue where the trachea comes in con-
tact with the oesophagus. Like the larynx it is lined by mucous
membrane, and has a ciliated epithelium upon its inner surface.
The mucous membrane, which also extends into the bronchial
tubes, keeps the internal surface of the air passages free from
impurities ; the sticky mucus entangles particles of dust and
other matters breathed in with the air, and the incessant

154

ANATOMY FOE NURSES. [Chap. XIIL

movements of the cilia continually sweep this dirt-laden
mucus upwards and outwards.

The trachea measures about four and a half inches (114 mm.)

Corn II

iXG. 107. — Front View of Cartilages of Larynx. Trachea and bronchi.

in length, and three-quarters of an inch (19 ram.) from side to
side. It extends down into the thorax from the lower part of
the larynx to opposite the third dorsal vertebra, where it divides
into two tubes, — the two bronchi, — one for each lung.

Chap. XIIL]

RESPIRATION.

155

The lungs. — The lungs consist of the bronchial tubes and
their terminal dilatations, numerous blood-vessels, lympliatics,
and nerves, and an abundance of fine, elastic, connective tissue,
binding all together.

The two bronchi, into which the trachea divides, enter the
right and left lung respectively, and then break up into a great
number of smaller branches which are called the bronchial
tubes. The two bronchi resemble the trachea in structure ; but
as the bronchial tubes divide and subdivide their walls become
thinner, the small plates of cartilage drop off, the fibrous tissue
disappears, and the finer tubes are composed of only a thin
layer of muscular and elastic tissue lined by mucous membrane.
Finally, these finer tubes end in
dilated cavities, the walls of \yhich,
consisting of a single layer of flat-
tened epitheloid cells, surrounded
by a fine, elastic, connective tissue,
are exceedingly thin and delicate.

Immediately beneath the layer of
flat cells, and lodged in the elastic
connective tissue, is a very close
network of capillary blood-vessels ;
and the air reaching the terminal
dilatations by the bronchial tubes is
separated from the blood in the cap-
illaries by only the thin membranes
forming their respective walls.

The terminal dilatations do not end as simple, rounded sacs,
like children's air-balloons, but each bronchiole ends in an
enlargement having more or less the shape of a funnel, and
called an infundihulum. Each of these infundibula is sub-
divided into secondary chambers or cavities, called alveoli^ the
walls of which are honey-combed with "bulgings.''^ In this
way the amount of surface exposed to the air and covered by
the capillaries is immensely increased. ^

Fig. 108. — Two Alveoli of
THE Lung. Highly magnified.
6, 6, bulgiugsof the alveoli, a, a.

1 These protrusions may be illustrated by a pea-pod, the walls of which are
filled with " bulgings," made by the pressure of the peas.

2 The pulmonary alveoli are often spoken of under the general name of air-
sacs, and the " bulgings " are known as air-cells. The term "air-cells," though
common, is misleading.

156

ANATOMY FOR NURSES. [Chap. XIII

Speaking roughly, the lungs may be said to consist of a film-
like elastic membrane covered by a close network of blood-
vessels. The membrane is arranged in the form of irregularly
dilated pouches at the end of fine tubes. These tubes open into
larger and larger tubes, and finally into the windpipe, which
places them in communication with the external air.

By virtue of their structure, the larger bronchial tubes
remain permanently open ; the smaller tubes, however, are sub-

' 6"

Fig. 109. — Anterior View of Lungs and Heart. 1, heart; 2, inferior vena
cava; 3, superior vena cava; 4, right innominate vein; 5, left innominate vein;
6, jugular vein; 7, subclavian vein; 8, arch of aorta; 8', subclaAnan artery; 9, left
pulmonary artery; 9', 9', carotid artery; 10, trachea; 11, left bronchus; 12, rami'
fications of right bronchus exposed in upper lobe of right lung ; 13, 14, middle lobe j
15, lower lobe ; IG, upper lobe of left lung; 17, lower lobe of left lung.

ject to collapse when empty ; they also may contract under
certain nervous influences. The terminal dilatations are emi-
nently elastic and continually expand and contract ; they are
bathed with lymph, and are always moist.

The two lungs occupy almost all the cavity of the thorax
which is not taken up by the heart. The right lung is the
larger and heavier; it is broader than the left, owing to the
inclination of the heart to the left side ; it is also shorter by one

Chap. XIII.] RESPIRATIOK 157

inch, in consequence of the diaphragm ri.sing higher on the
right side to accommodate the liver. The right lung is divided
by fissures into three lobes. The left lung is smaller, narrower,
and longer than the right, and has only two lobes. Each lung
is enclosed in a serous sac, the pleura, one layer of which is
closely adherent to the walls of the chest and diaphragm ; the
other closely covers the lung. The two layers of the pleural
sacs, moistened by lymph, are normally in close contact ; they
move easily upon one another, and prevent the friction that
would otherwise occur between the lungs and the walls of the
chest with every respiration.

The pressure of the atmospheric air upon the lungs through
the air-passages is greater than it can possibly be upon them
from the outside through the chest walls, on account of the
resistance which the solid chest walls offer to this pressure ;
and, ordinarily, it is impossible for the distended lungs to
pull away the layer of the plural sac which adheres to them
from the layer which is attached to the chest wall. If, how-
ever, the chest wall be punctured, the air from the outside
will rush in, distend the pleura, and, squeezing the air out of
the air-sacs into the air-passages, cause the lungs to shrivel up
and collapse.

Respiration. — The lungs, then, are placed in an air-tight tho-
rax, which they, together with the heart and great blood-vessels,
completely fill. By the contraction of certain muscles (see page
66), the cavity of the thorax is enlarged ; the lungs are cor-
respondingly distended to fill the enlarged cavity, and, by this
distension, the air within the air-sacs becomes expanded and
more rarefied than the air outside. Being thus expanded and
rarefied, the pressure of the air within the lungs becomes less
than that of the air outside, and this difference of pressure
causes the air to rush through the trachea into the lungs, until
an equilibrium of pressure is established between the air inside
the lungs and that outside. This constitutes an inspiration.
Upon the relaxation of the inspiratory muscles, the elasticity
of the lungs and of the chest walls causes the chest to return to
its original size, in consequence of which the air within the
lungs becomes more contracted and denser than the air outside,
the pressure within becomes greater than the pressure without,
and the air rushes out of the trachea until equilibrium is once

158 ANATOMY FOR NURSES. [Chap. XIII

more established. This constitutes an expiration. An inspira-
tion and an expiration make a respiration.

As in the heart, the auricular systole, the ventricular systole,
and then a pause, follow in regular order, — so in the lungs,
the inspiration, the expiration, and then a pause succeed one
another. Each respiratory act in the adult is ordinarily repeated
from fifteen to eighteen times per minute. But this rate varies
under different circumstances, one of the most important of
which is age. The average rate in the newly born infant has
been found to be forty-four per minute, and at the age of live
years, twenty-six per minute. It is reduced between the ages
of fifteen and twenty to the normal standard.

A condition of rest or activity readily influences the number
of respirations per minute. They are always less frequent
during sleep, and are markedly increased by severe muscular
exercise.

Respiration is an involuntary act. It is possible for a short
time to increase or retard the rate of respiration within certain
limits by voluntary effort, but this cannot be done continuously.
If we intentionally arrest the breathing or diminish its fre-
quency, after a short time the nervous impulse becomes too
strong to be controlled, and the movements will recommence
as usual. If, on the other hand, we purposely accelerate res-
piration to any great degree, the exertion soon becomes too
fatiguing for continuance, and the movements return to their
normal standard.

The nervous impulses which cause the contractions of the
respiratory muscles arise in the medulla oblongata, travel down
the spinal cord, and out along the plirenic and intercostal
nerves. If the portion of the medulla oblongata, where these
nervous impulses arise, be removed or injured, respiration
ceases, and death at once ensues. This part of the medulla is
known as the respiratory centre.

The effects of respiration upon the air within the lungs. — At
birth the lungs contain no air. The walls of the air-sacs are in
close contact, and the walls of the smaller bronchial tubes or
bronchioles collapsed and toucldng one another. The trachea
and larger bronchial tubes are open, but contain fluid and not
air. When the chest expands with the first breath taken, the
inspired air has to overcome the adhesions existing between

Chap. XIII.] KESPIRATION. 169

the walls of the bronchioles and air-sacs. The force of this
first inspiratory effort, spent in opening out and unfolding, as it
were, the inner recesses of the lungs, is considerable. In the
succeeding expiration, most of the air introduced by the first
inspiration remains in the lungs, succeeding breaths unfold the
lungs more and more, until finally the air-sacs and bronchioles
are all opened up and filled with air. The lungs thus once
filled with air are never completely emptied again until after
death.

The air remaining in the lungs after expiration is called the
old or stationary air into which fresh air is introduced with
every inspiration, the fresh or tidal air, as it is called, giving
up its oxygen to, and taking carbon dioxide from, the old or
stationary air. Thus the stationary air transacts the business
of respiration, receiving, on the one hand, constant supplies of
oxygen from the tidal air which it delivers to the blood in the
capillaries on the walls of the air-sacs ; and, on the other hand,
returning, in exchange to the tidal air, the carbon dioxide it
has received from the blood in these capillaries.

In ordinary respiration the lungs are not distended to their
fullest extent, but by more forcible muscular contraction the
capacity of the chest can be further enlarged, and a certain
additional amount of air will rush into the lungs. This addi-
tional amount is often spoken of as complemental air. In
laboured breathing the contraction of the respiratory muscles
not usually brought into play, such as the muscles of the throat
and nostrils, becomes very marked.

The entry and exit of the air are accompanied by respiratory
sounds or murmurs. These murmurs differ as the air passes
through the trachea, the larger bronchial tubes, and the bron-
cliioles. They are variously modified in lung disease, and are
then often spoken of under the name of " rales."

The effects of respiration upon the air outside the body. — With
every inspiration a well-grown man takes into his lungs about
thirty cubic inches (492 cubic centimetres) of air. The air
he takes in differs from the air he gives out mainly in three
particulars : —

1. Whatever the temperature of the external air, the expired
air is nearly as hot as the blood ; namely, of a temperature
between 98° and 100° F. (36.7° and 37.8° C).

ICO ANATOMY FOR NURSES. [Chap. XIII.

2. However dry the external air may be, the expired air is
quite, or nearly, saturated with moisture. ^

3. The expired air contains about four or five per cent less
oxygen, and about four per cent more carbon dioxide than the
external air, the quantity of nitrogen suffering but little change.
Thus : —

Oxygen. Nitrogen. Carbon Dioxide.

Inspired air contains . . . 20.81 79.15 0.04

Expired air contains . . . 16.033 79.587 4.38

(Foster.)

In addition the expired air contains a certain amount of effete
matter of a highly decomposable and impure character. The
quantity of water given off in twenty-four hours varies very
much, but may be taken on the average to be about nine ounces
(266 cubic centimetres). The quantity of carbon given off at the
same time is pretty nearly estimated by a piece of pure charcoal
weighing eight ounces (248 grammes).

If a man breathing fifteen to sixteen times a minute takes in
thirty cubic inches (492 cubic centimetres) of air with each
breath, and exhales the same quantity, it follows that in twenty-
four hours from three hundred and fifty to four hundred cubic
feet (9910 to 11,326 cubic decimetres) of air will have passed
through his lungs. And if such a man be shut up in a close
room measuring seven feet (2.1 metres) each way, all the air
in the room will have passed through his lungs in twenty-four
hours.

Since at every breath the external air loses oxygen and gains
carbon dioxide and other waste and poisonous matters, it is
imperative that some provision be made for constantly renewing
the atmospheric surroundings of people in dwelling houses.
This is accomplished by ventilation, which consists of a system
of mechanical contrivances, by means of which foul air is con-
stantly removed and fresh air as constantly supplied.

The minimum amount of air space every individual should
have to himself is 800 cubic feet (22,652 cubic decimetres), —
a room nine feet (2,7 metres) high, wide, and long contains 729

1 This moisture evaporates from the blood. It is thought by some authorities
that most of the moisture is collected by the breath from the mucous membrane
of the respiratory tract. A certain quantity, liowever, evaporates from the
blood through the walls of the capillaries, and, escaping with the carbon dioxide
through the membrane of the alveoli, is carried upwards in every expiration.

Chap. XIII.] KESPIKATION. 161

cubic feet (20,642 cubic decimetres), — and this space should
be accessible by direct or indirect channels to the outside air.

Effects of respiration upon the blood. — While the air in passing
into and out of the lungs is robbed of a portion of its oxygen
and loaded with a certain quantity of carbon dioxide, the blood
as it streams along the pulmonary capillaries is also undergoing
important changes. As it leaves the right ventricle it is venous
blood of a dark purple colour ; when it enters the left auricle
it is arterial blood and of a bright scarlet colour. In passing
through the capillaries of the body from the left to the right
side of the heart it is again changed from the arterial to the
venous condition. The question arises, how is this change of
colour effected?

As we have already seen, the blood in the thin-walled, close-
set pulmonary capillaries is separated from the air in the air-
sacs by only the moist delicate membranes which form their
respective walls. By diffusion the oxygen in the air passes
through these moist membranes into the venous blood in the
pulmonary capillaries, combines with the reduced haemoglobin
which has lost its oxygen in the tissues, and turns it into oxy-
hsemoglobin ; the purple colour shifts immediately into scarlet,
and the red corpuscles hasten onwards to carry this oxy-hoemo-
globin to the tissues. Passing from the left ventricle to the
capillaries in the tissues the oxy-haemoglobin gives up some of its
oxygen, the colour shifts back again to a purple hue, and the red
corpuscles return with this reduced haemoglobin to the lungs.

The oxygen given up by the blood readily combines with the
unstable chemical compounds of which the tissues are composed.
In this process, called oxidation} complex bodies are broken up
into simpler ones, such as carbon dioxide and water, and there
is thus liberated a great deal of energy which is manifested in
the increasing of muscular activity, and in the production of
heat. The carbon dioxide passes by diffusion into the venous
blood, and is carried by it to the right side of the heart and
thence to the lungs, a certain quantity, however, escaping from
the blood through the kidneys and skin. A small and insig-

1 This process of oxidation may be illustrated by the burning of a fire ; the
oxygen which is in the air combines with the carbon of the wood, heat and light
are generated, and oxidized products in the form of carbon dioxide and ashes
produced.

162 ANATOMY FOR NURSES. [Chap. XIII.

nificant amount of oxygen is introduced into the blood through
the skin, and, with the food, through the alimentary canal ; but,
as we have stated in the beginning of this chapter, respiration
is the main process by means of which the body is supplied with
oxygen and relieved of carbon dioxide.

The respiration and circulation are profoundly and intimately
connected, any change in the blood immediately affecting the
respiration.

It would appear that stimulation of the respiratory centre in
the medulla oblongata depends primarily upon the condition of
the blood. If the blood is very rich in oxygen the res^Dirations
are feeble and shallow ; if, on the other hand, the blood is highly
venous the respirations are deeper and more frequent, and if the
blood remains venous, gradually become forced and laboured
until we get the condition called " dyspnoea." Should the blood
get more and more venous, the impulses generated in the respir-
atory centre become more and more vehement. These nervous
impulses, instead of confining themselves to the usual nerves
distributed to the ordinary respiratory muscles, overflow on to
other nerves and put into action other muscles until there is
scarcely a muscle in the body that is not affected. The muscles
which are thus more and more thrown into action are especially
those tending to carry out or to assist expiration ; and at last if
no relief is afforded the violent respiratory movements give way
to general convulsions of the whole body. By the violence of
these convulsions the whole nervous system becomes ex-
hausted, the convulsions soon cease, and death is ushered in
with a few infrequent and long-drawn breaths.

It has been surmised that the excitability of the respiratory
nerve-centre is due to certain chemical substances which act as
stimulants. AVhen the blood is rich in oxygen this substance is
oxidized or burned, and removed so fast that it is able to exert
but little influence on the respiratory nerve-centre ; when, how-
ever, the blood is poor in oxygen, this substance accumulates
and the nerve-centre is powerfully stimulated. Thus when the
blood needs oxygen, the respirations are increased to get, if
possible, more air into the lungs; if the blood is too rich in
oxygen, the respirations become abnormally quiet and shallow.

Modified respiratory movements. — Various emotions may be
expressed by means of tlie respiratory apparatus.

Chap. XIII.] EESPIRATION. 163

Sighing is a deep and long-drawn inspiration, chiefly through
the nose.

Yaivning is an inspiration, deeper and longer continued than
a sigh, drawn through the widely open mouth, and accompanied
by a peculiar depression of the lower jaw.

Hiccough is caused by a sudden, inspiratory contraction of the
diaphragm ; the glottis suddenly closes and cuts off the column
of air just entering, which, striking upon the closed glottis,
gives rise to the characteristic sound.

In sobbing, a series of convulsive inspirations follow each
other slowly, the glottis is closed, so that little or no air enters
the chest.

Coughing consists, in the first place, of a deep and long-drawn
inspiration by wliich the lungs are well filled with air. This is
followed by a complete closure of the glottis, and then comes a
forcible and sudden expiration, in the midst of which the glottis
suddenly opens, and thus a blast of air is driven through the
upper respiratory passages.

In sneezing, the general movement is the same, except that
the opening from the pharynx into the mouth is closed by the
contraction of the pillars of the throat and the descent of the soft
palate, so that the force of the blast is driven entirely through
the nose.

Laughing consists essentially in an inspiration, followed by a
whole series of short spasmodic expirations, the glottis being
freely open during the whole time, and the vocal cords being
thrown into characteristic vibrations.

In crying, the respiratory movements are the same as in
laughing; the rhythm and the accompanying facial expressions
are, however, different, though laughing and crying often be-
come indistinguishable.

CHAPTER XIV.

ALIMENTATION.

Section I. Preliminary remarks on secreting glands and mucous
membranes.

Section II. Food-principles ; proteids, fats, carbo-hydrates, water, saline
and mineral substances : chemical composition of the body : average compo-
sition of milk, bread, and meat. Concluding remarks.

Section I. In our last chapter, we described the methods by-
means of which the blood is supplied with one of its most vital
constituents, oxygen. In the next three chapters, we shall con-
sider how the blood is supplied with those materials through
the alimentary canal, which it also constantly requires to main-
tain the life and growth of the body.

The subject of alimentation, or the process by which the
body is nourished, naturally falls into three divisions, viz. : —

(1) Food.

(2) Digestion.

(3) Absorption.

In order, however, to make the subject more intelligible, it
will be necessary to make a few preliminary remarks upon the
construction of secreting glands and mucous membranes.

Secreting glands. — The secreting glands differ from other
glands, such as the lymphatic glands, the tonsils, Peyer's
patches, etc., by being always devoted to the function of
secretion, and by discharging the secretions they form through
little tubes or ducts which open exteriorly. The lymphatic
glands and bodies of allied structure are often spoken of as
ductless glands, in order to distinguish them from these true
secreting glands provided with ducts.

A secretion is a substance elaborated from the blood by cell

164

Chap. XIV.]

ALIMENTATION.

165

action, and poured out upon the external or internal surfaces
of the body. An excretion resembles a secretion, except that
whereas the secretion is formed to perform some office in the
Dody, the excretion is formed only to be thrown out of the body.

Fig. 110. — Diagram showing Various Forms of Secreting Glands. 1, gen-
eral plan of a secreting membrane; a, epithelial cells; b, basement membrane;
c, coimective tissue in which lie the blood-vessels (d) ; 2-7, simple and compound
tubular and saccular glands ; d, duct.

A secretory apparatus consists essentially of a layer of secret-
ing cells placed in close communication with a network of blood-
vessels. The simplest form in which a secretory apparatus
occurs is in the shape of a plain, smooth surface, composed of

166 ANATOMY FOR NURSES. [Chap. XIV.

a single layer of epithelial cells, resting usually on a thin mem-
brane, on the under surface of which is spread out a close net-
work of blood-vessels. In order to economize space and to
provide a more extensive secreting surface, the membrane is
generally increased by dipping down and forming variously
shaped depressions or recesses, these depressions or recesses
being called the secreting glands.

The secreting glands are of two kinds, simple and compdund.
The simple glands are generally tubular or saccular cavities, the
tube in the tubular variety being sometimes so long that it coils
upon itself, as in the sweat glands of the skin ; they all open
upon the surface by a single duct. In the compound glands,
the cavities are subdivided into smaller tubular or saccular
cavities, opening by small ducts into the main duct which pours .
the secretion upon the surface.

However simple or complicated the involuted surface, the
secreting process is essentially the same ; and in this process
the nucleated cells play the most important part. These cells
take into their interior those substances from the blood which
they require to make the special secretion they are set apart
to form, converting this selected material into chemical com-
pounds, which either act as solvents, as in the digestive juices,
or perform some other office in the body. The secretion the
cells elaborate escapes from them either by exudation or by the
bursting and destruction of the cells themselves. Cells filled
with secreting matter may also be detached and carried out
entire with the fluid part of the secretion; and, in all cases,
new cells speedily take the place of those which have served
their office. The glands are provided with lymphatics, and fine
nerve fibrils have also been found to terminate in them. That
they are under the influence of the nervous system is shown by
the fact that impressions made on the nervous system affect
the secretions, a familiar instance of which is the flow of saliva
into the mouth, caused by the sight, or smell, or even the
thought of food.

The position and functions of the several glands will be de-
scribed later in connection with digestion and elimination.

Mucous membranes. — The mucous membranes, unlike the
serous membranes, line passages and cavities which communi-
cate with the exterior. They are all subject to the contact

Chap. XIV.] ALIMENTATION. 167

of foreign substances introduced into the body, such as air
and food, and also to the contact of secreted matters ; hence
their surface is coated over and protected by mucus, a thicker
and more sticky fluid than the lymph which moistens the
serous membranes. The mucous membranes of different parts
are continuous, and they may nearly all be reduced to two
great divisions ; namely, the gastro-pneumonic and the genito-
urinary.

The gastro-pneumonic mucous membrane covers the inside
of the alimentary canal, the air-passages, and the cavities com-
municating with tliem. It commences at the edges of the lips
and nostrils, proceeds through mouth and nose to the throat,
and thence is continued throughout the entire length of the
alimentary canal to the anus. At its origin and termination it
is continuous with the external skin. It also extends through-
out the windpipe, bronchial tubes, and air-sacs. From the inte-
rior of the nose the membrane may be said to be prolonged into
the lachrymal passages, and under the name of conjunctival
membrane, over the fore part of the ej^eball and inside of the
eyelids, on the edges of which it again meets with the skin.
From the upper part of the pharynx a prolongation extends, on
each side, along the passage to the ear ; and offsets in the ali-
mentary canal go to line the salivary, pancreatic, and biliary
ducts, and the gall-bladder.

The genito -urinary mucous membrane lines the inside of the
bladder, and the whole urinary tract from the interior of
the kidneys to the meatus urinarius, or orifice of the ure-
thra ; it also lines the vagina, uterus, and Fallopian tubes in
the female.

The mucous membranes are attached to the parts beneath
them by areolar tissue, here named " submucous," and which
differs greatly in quantity as well as in consistency in different
parts. The connection is in some cases close and firm, as in
the cavity of the nose. In other instances, especially in cavities
subject to frequent variations in capacity, like the gullet and
stomach, it is lax; and when the cavity is narrowed by con-
traction of its outer coats, the mucous membrane is thrown into
folds or rugcB which disappear again when the cavity is dis-
tended. But in certain parts the mucous membrane forms
permanent folds that cannot be effaced, and which project con-

168 ANATOMY FOR NURSES. [Chap. XIV.

spicuously into the cavity which it lines. The best marked
example of these folds is seen in the small intestine, where
they are called valvulm conniventes, and which are doubtless
provided for increasing the amount of absorbing surface for the
products of digestion. The redness of mucous membranes is
due to their abundant supply of blood.

A mucous membrane is composed of a layer of connective
tissue called the corium, and of a layer of epithelium which
covers the surface. The epithelium is the most constant part
of a mucous membrane, being continued over certain parts to
which the other parts of the membrane cannot be traced. It
may be scaly and stratified, as in the throat ; columnar, as in
the intestine ; or ciliated, as in the respiratory tract. The
mucus which moistens its surface is either derived from little
glands in the mucous membrane, or from the columnar cells
which cover the surface. The corium of a mucous membrane
is composed of either areolar or lymphoid connective tissue.
It is usually bounded next to the epithelium by a basement
membrane, and next to the submucous tissue by a thin layer of
plain muscular tissue termed the muscularis mucosce : this layer
is not always present. The connective tissue layer varies much
in structure in different parts ; the lymphoid variety is in cer-
tain places greatly increased in amount, packed with lymphoid
cells, and forms the solitary follicles and Peyer's patches de-
scribed in Chapter XII.

The small blood-vessels conveying blood to the mucous mem-
branes divide in the sub-mucous tissue, and send smaller branches
into the corium, where they form a network of capillaries just
under the basement membrane. The lymphatics also form net-
works in the corium and communicate with larger vessels in
the sub-mucous tissue below. The free surface of the mucous
membrane is in some parts smooth, but in others is beset with
little eminences called papillae and villi.

The papillce are best seen on the tongue ; they are small
processes of the corium, mostly of a conical shape, containing
blood-vessels and nerves, and covered with epithelium.

The villi are most fully developed on the mucous coat of
the small intestine. Being set close together like the pile
of velvet, they give a shaggy or villous appearance to the
membrane. They are little projections of the mucous mem-

Chap. XIV.J

ALIMENTATION.

169

brane, covered with epithelium, and containing blood-vessels
and lacteals, and are favourably arranged for absorbing nutri-
tive matters from the intestines.

Section II. Food. — Under the term
" food " we include all substances, solid or
liquid, necessary for nutrition. The ques-
tion at once arises : What are these sub-
stances, and how are they obtained ?

If we analyze the food we daily take into
our mouths and introduce into the aliment-
ary canal, we find it separable into two
divisions ; viz. that which is nutritious,
and that which is innutritions. The nutri-
tious portion, that which can be digested,
absorbed, and made use of by the body,
is generally spoken of under the name
of food-stuffs or food-principles : the innutri-
tious portion, usually by far the smaller of
the two divisions, never enters the body
at all, properly speaking, but passes through
the alimentary canal and is excreted in the
form of feces.

Food-stuffs are composed mainly of the elementary chemical
substances, — oxygen, carbon, hydrogen, nitrogen, — and may,
according to the varying proportions in which these chemical
elements combine, form five distinct and different classes of
food-stuffs. These are : —

Fig. 111. — An Intes-
tinal Villus. «, a, a,
columnar epithelium ;
h, b, capillary network;
c, c, longitudinal muscle
fibres ; d, lacteal vessel.

1. Proteids.

2. Fats.

3. Carbo-hydrates.

4. Water.

5. Saline or mineral matters.

Proteids. — Proteids form a large proportion of all living
bodies, and are an essential part of all living structures. They
contain on an average in every 100 parts about : —

Carbon 53 parts

Hydrogen 7 "

Oxygen 24 "

Nitrogen 16 "

170 ANATOMY FOR NURSES. [Chap. XIV.

with usually a little sulphur and sometimes a trace of phos-
phorus and iron. They are the only food-stuffs that contain
nitrogen in any appreciable quantity, and are sometimes classed
as " nitrogenous " food-stuffs. Proteids occur in the form of
albumin in the white of egg (egg-albumin), in milk, in blood
and lymph (serum-albumin) ; in the form of casein in milk and
cheese ; of myosin and sy^itonin in muscle ; of vitellin in tlie
yolk of eggs ; of gluten in flour. Allied to proteids but of
less nutritive value are the chondrin, obtained from cartilage,
and the gelatin, obtained from other varieties of connective
tissue, by boiling.

All proteids yield peptones very readily at the temperature
of the body under the action of the acid gastric, and alka-
line pancreatic juice. These peptones are highly soluble bodies
and readily absorbed.

The foods that are most rich in the various forms of proteids
are meat, milk, eggs, cheese, all kinds of fish, wheat, beans,
and oatmeal.

Fats. — Fats are composed of carbon, hydrogen, and oxygen.
They contain on an average in every 100 parts : —

Carbon 76.5 parts

Hydrogen 12 "

Oxygen 11.5 "

The most important fats are stearin, palmitin, margarin, and
olein, which exist in .varying proportions in the fat of animals
and vegetable oils, and in milk, butter, lard, etc. The brains
of animals and the yolk of eggs contain a complex phosphor-
ized fat, called lecithin. Fatty matters are very abundant
in olives, sweet almonds, chocolate, castor-oil bean, hemp, and
flaxseed. Most of the fatty substances of food are liquefied
at the temperature of the body, and are readily oxidized,
probably on account of the large amount of carbon which
they contain.

Carbo-hydrates. — In the carbo-hydrates there is sufficient
oxygen present to saturate all the hydrogen and to form
water ; hence their name. In the fats, there is not quite so
much oxygen as hydrogen ; water is, therefore, not formed
in them, and in this particular they differ from the carbo-
hydrates.

Chap. XIV.] ALIMENTATION. 171

The carbo-hydrates contain in every 100 parts about : —

Carbon 44 parts

Hydrogen 6 "

Oxygen 50 "

The principal carbo-hydrates are starch and sugars. Starch is
found in wheat, Indian corn, oats, and all grains, in potatoes,
peas, beans, roots and stems of many plants, and in some fruits.
In a pure state, it appears as a white powder, as in arrowroot
and cornstarch. Under the influence of dry heat, starch may
be converted into a soluble substance, called dextrine; and,
under the action of certain of the digestive juices, at the tem-
perature of the body, into sugar. Of sugars there are several
kinds : cane sugar or sucrose, obtained chiefly from the sugar-
cane, beet sugar, and maple sugar ; grape sugar or glucose, found
in grapes, peaches, and other fruits (it is also readily manufac-
tured from starch); rtialt sugar or maltose, obtained from malt;
milk sugar or lactose, obtained from milk.

Carbo-hydrates are readily oxidized ; together with fats, they
are often classed as " non-nitrogenous " food-stuffs.

Water is a compound of oxygen and hydrogen, water being
produced whenever two molecules of hydrogen unite with one
of oxygen. Next to air, water is the most necessary principle
of life. It forms about seventy per cent of the entire bodily
weight. It is an essential constituent of all tlie tissues, as
well as forming the chief part of all the fluids of the body.
It acts as a solvent upon various ingredients of the food, lique-
fying them and rendering them capable of absorption. Most
of the water of the body is taken into it from without, but it
is also formed within the body by the union of hydrogen and
oxygen in the tissues.

Mineral salts. — The mineral substances chiefly necessary for
nutrition are : —

Chloride
Phosphate
Sulphate
Carbonate J

- of soda and potash.

Phosphate! „ ,. ,

^ , ^ 01 lime and magnesia.

Carbonate J

172

ANATOMY FOR NURSES.

[Chap. XIV.

Of these substances, chloride of soda, sodium chloride or com-
mon salt, is the most important mineral ingredient of food. It
is contained in nearly everything we eat, but usually not in
sufficient quantity to supply all the needs of the body, and we
therefore add it as a separate article of diet. It is present in
most of the fluids of the body, notably in the blood. The rest
of the mineral substances are usually contained in sufficient
quantity in an ordinary diet, though occasionally it becomes
necessary to supply them independently. Of all the mineral
salts, phosphate of lime exists in the largest quantity in the
body ; it enters largely into the composition of the bones, teeth,
and cartilages, and gives firmness and solidity to the tissues.
It is present in very small quantities in the bodily fluids, with
the exception of the milk, which contains a notable amount of
phosphate of lime, and which serves for the ossification of the
growing bones of infants and young children.

Chemical composition of the body. — Professor Atwater gives
the following average composition of the body of man, weigh-
ing 148 pounds : —

Oxygen 92.4

Carbon 31.3

Hydrogen 14.6

Nitrogen 4.6 ,

Calcium 2.8

Phosphorus 1.4

Potassium 34

Sulphur 24

Chlorine 12

Sodium 12

Magnesium .04

Iron 02

Fluorine 02.

The human body, from a chemical point of view, may be
regarded as a mixture of three large classes of chemical sub-
stances ; viz. proteids, fats, and carbo-hydrates associated with
water and mineral salts.

In our first chapter we said that protoplasm was the basis of
the life of the body, and from that point of view we may look
upon the human body as an assemblage of variously modified
protoplasm. But it comes to the same thing, for the chemical

142.9

5.1

Chap. XIV.] ALIMENTATION. 173

composition of protoplasm, so far as it has been possible to
analyze it, lias been found to agree closely with that of the
fully developed organism.

The processes of nutrition that take place in the cell are
essentially the same as those which take place in the fully
developed body. In both cases, non-living chemical substances
are taken in from without, and converted into material which
is endowed with that mysterious property we call life.

To support life, the different food-stuffs must be taken in
proper proportion; and, in order that all the tissues and fluids
of the body may continue in good condition and perform their
functions properly, they must be supplied with all the ingredi-
ents necessary to their constitution. A man may be starved to
death at last by depriving him of lime phosphate as surely,
though not as rapidly, as if he were deprived of albumin or fat.
Many a patient in less well-instructed times has been slowly
killed by deprivation of water, or by exclusive feeding on beef-
teas and jellies.

Average composition of milk, bread, and meat. — The following
analyses of the composition of three staple articles of diet —
milk, bread, and meat — are taken from Dalton.

Average composition of milk in 100 parts : —

Water 86.4

Proteids 4.3

Sugar 5.2

Fat 3.7

Mineral salts .4

Average composition of wheaten bread in 100 parts : —

Starchy matters 56.7

Proteids 7.0

Fatty matters 1.3

Mineral salts 1.0

Water 34.0

Average composition of beef flesh : —

Water 77.5

Proteids 16.0

Pat 5.0

Mineral salts 1.5

174 ANATOMY FOR NURSES. [Chap. XIV.

Concluding remarks. — The quantity and also the kind of food
each individual daily requires depends chiefly upon the nature
and the amount of the work he is called upon to perform, and
the conditions of the climate in which he lives. Universal
experience has taught us that the best sustainers of life are
milk and bread and water, with a certain amount of meat and
fat. These should form the basis of all our diets, though not
to the exclusion of other food-stuffs, for it has also been proved
that a mixed diet is always to be preferred to one that consists
constantly of the same articles of food.

To determine the relative digestibility of foods is a very diffi-
cult matter in view of the individual peculiarities of different
people. Strawberries may agree perfectly with ninety-nine
people, and with the hundredth, act as a powerful poison.
Some persons, as we all know, cannot tolerate milk or eggs,
and yet, from a chemical point of view, these foods are emi-
nently suitable articles of diet.

The best diet is that which contains all the articles of food
necessary for the wants of the body in proper proportions, which
is agreeable to the individual, and which gives the minimum
amount of work to the digestive organs.^

Food to be of any use to the body must be digested and
assimilated. We may partake of an ideal diet and yet remain
imperfectly nourished, if our digestive organs are out of order,
or our power to absorb and assimilate digested products in any
way impaired. In our next chapter we shall describe the ali-
mentary canal, the accessory digestive organs, and the methods
by means of which the food is reduced to a condition available
for the uses of the body.

1 For valuable information on the relative value of foods and preparation of
the same for the sick, the student is referred to Boland's " Handbook of Invalid
Cookery."

CHAPTER XV.

ALIMENTATION CONTINUED : THE DIGESTIVE APPAEATUS ; ALI-
MENTARY CANAL, AND ACCESSORY ORGANS.

The digestive apparatus consists of the alimentary canal, and
the accessory organs, the teeth, salivary glands, pancreas, and
liver.i

Alimentary canal. — The alimentary canal is a musculo-mem-
branous tube extending from the mouth to the anus. It is
about six times the length of the bod}^, and the greater part of
it is coiled up in the cavity of the abdomen. The diameter of
the tube is by no means uniform, being considerably dilated in
certain parts of its course. It is composed of three coats from
the mouth to where it passes through the diaphragm, and of
four coats in the abdominal cavity. These coats are : (1) the
mucous, (2) the sub-mucous (both described in the last chapter) ;
(3) the muscular ; (4) the serous. The muscular coat is com-
posed for the most part of unstriped muscular fibres, the layers
of which are disposed in various wa3^s, the most general arrange-
ment being in a longitudinal and circular direction. By the
alternate contraction and relaxation of fibres arranged in this
fashion (the contractions starting from above), the contents of
the tube are propelled from above downwards. The serous coat
is derived from the peritoneum, which is the serous membrane
lining the walls, and covering the viscera, of the abdomen.

Into the interior of the alimentary canal are poured secre-
tions from the glands in the mucous membrane with which it is
lined, and also secretions from the accessory glands, which lie
outside the canal and are connected with its interior by ducts.

The alimentary canal for convenience of description may be
divided into : —

1 Plate VII. shows relative position of digestive organs in abdominal cavity.

175

Plate VII. — Regions of the Abdomen and their Contents (Edge op Costal
Cartilages in Dotted Outline).

For convenience of description the abdomen may be artificially divided into nine
regions by drawing two circular lines round the body parallel tvnth the cartilages of
the ninth ribs, and the highest point of the crests of the ilia ; and two vertical lines
from the cartilage of the eighth rib on each side to the centre of Poupart's ligament.
The viscera contained in these different regions are as follows : —

Eight Hypochondriac. —
The right lobe of the liver and
the gall-bladder, hepatic flexure
of the colon, and part of the
right kidney.

Epigastric Eegion. — The
middle and pyloric end of the
stomach, left lobe of the liver,
the pancreas, the duodenum,
parts of the kidneys and the
suprarenal capsules.

Left Hypochondriac. — The
splenic end of the stomach, the
spleen and extremity of the pan-
creas, the splenic flexure of the
colon, and part of the left kid-
ney.

Right Lumbar. — Ascend-
ing colon, part of the right kid-
ney, and some convolutions of
the small intestines.

Eight Inguinal (Iliac). —
The cajcum, appendix cseci.

Umbilical Region. — The
transverse colon, part of the
great omentum and mesentery,
transverse p.art of the duode-
num, and some convolutions of
the jejunum and ileum, and
part of both kidneys.

Hypogastric Region. — Con-
volutions of the small intes-
tines, the bladder in children,
and in adults if distended, and
the uterus during pregnancy.

Left Lumbar. — Descending
colon, part of the omentum,
part of the left kidney, and
some convolutions of the small
intestines.

Left Inguinal (Iliac). —
Sigmoid flexure of the colon.

176

Chap. XV.]

ALIMENTATION.

177

Mouth, containing tongue and teeth.
Pharynx.

Oesophagus.
Stomach.

/"Duodenum.
Small intestine-j Jejunum.

Uleum.

(Caecum.
Colon.
Rectum.

.TempoT

Mouth or buccal cavity (vide Fig. 113). — The mouth is a nearly
oval-shaped cavity with a fixed roof and movable floor. It is
bounded in front by the lips, on the sides by the cheeks, below
by the tongue, and above by the palate. The palate con-
sists of a hard portion
in front formed by
bone covered by mu-
cous membrane, and
of a soft portion be-
hind containing no
bone. The hard palate
forms the partition
between the mouth
and nose ; the soft
palate arches back-
wards and hangs like
a curtain between the
mouth and the phar-
ynx. Hanging from
the middle of its lower
border is a pointed
portion of the soft pal-
ate called the uvula ;

and arching outwards and downwards from the base of the
uvula on each side to the back of the tongue are two curved
folds of muscular tissue covered by mucous membrane, called
the pillars of the fauces. Just before reaching the tongue,
the two pillars, on either side, are separated by a triangular
space in which lie the small masses of lymphoid tissue called
the tonsils. The fauces is the name given to the aper-

FiG. 112. — The Salivary Glands.

178 ANATOMY FOR NUESES. [Chap. XV.

ture leading from the mouth into the pharyjix or throat
cavity.

The mucous membrane lining the mouth contains many
minute glands which pour their secretion upon its surface,
but the chief secretion of the mouth is supplied by the sali-
vary glands, which are three pairs of large compound saccular
glands 1 called the parotid, submaxillary, and sublingual, respec-
tively. Each parotid gland is placed just in front of the eai-,
and its duct passes forwards along the cheek, until it opens
into the interior of the mouth opposite the second upper molar.
The submaxillary and sublingual glands are situated below
the jaw and under the tongue, the submaxillary being placed
further back than the sublingual. Their ducts open in the
floor of the mouth beneath the tongue. The secretion of these
salivary glands, mixed with that of the small glands of the
mouth, is called saliva.

The tongue. — The tongue is a freely movable muscular organ
attached by its base to the hyoid bone. Besides being the
special seat of the sense of taste, it is a useful aid in mastication
and deglutition.2

The teeth. — The semicircular borders of the upper and lower
jaw-bones (the alveolar processes) contain thirty-two sockets for
the reception of the teeth ; extending over the bones and a little
way into each socket is a dense insensitive fibrous tissue covered
by smooth mucous membrane, the gums.

There are two sets of teeth developed during life : the first
or milk teeth, and the second or permanent teeth. The cutting
of the milk teeth begins usually at six months and ends with
the second year ; there are only twenty of these teeth, and they
are replaced during childhood by the permanent teeth .^

Each tooth consists of two portions, the crown and the fang :
the crown projects into the cavity of the mouth, the fang is
embedded in the socket. According to their shape and use the
teeth are divided into incisors, canines, bicuspids, and molars.

1 For description of compound glands see Section I. Chapter XIV.

2 A detailed description of the tongue will be found in the chapter on the
organs of special sense.

8 The milk teeth are usually cut in the following order, the teeth appearing
first in the lower jaw: central incisors, 7th month ; lateral incisors, 7th to 10th
month ; front molars, 12th to 14th month ; canine, 14th to 20th month ; back
molars, 18th to 36th month. '

Chap. XV.]

ALIMENTATION.

179

Beginning in the middle line of each jaw and counting from
before backwards, there are four incisors, two canines, four
bicuspids, and six molars in the upper and in the lower jaw.
The incisors have wide sharp edges, and are specially adapted
for cutting the food ; the canines, or eye teeth, have a sharp
pointed edge, are longer than the incisors, and are specially
useful for tearing food asunder,
or, as in dogs and other car-
nivora, for holding prey. The
bicuspids, or false grinders, are
broader, with two points or cusps
on each crown : these teeth have
only one fang, the fang, however,
being more or less completely
divided into two. The molars,
or true grinders, have broad

crowns with small pointed pro-
jections, which make them well
fitted for crushing and bruising
the food : they each have two or
three fangs. The twelve molars
do not replace the milk teeth, but
are gradually added with the
extension of the jaws, the last or
hindermost molars not appearing
until twenty-one years of age :
they are often on this account
called "wisdom teeth."

The teeth are composed of
three bone-like tissues, enamel,
dentine, and cement; these sub-
stances are all harder than bone,
enamel beinsr the hardest tissue
found in the body. In the inte-
rior of each tooth is a cavity, the pulp-cavity, which is filled
with a highly vascular and nervous tissue called the dental pulp.
The teeth are developed from epithelium in much the same way
as the hairs; for description of which see page 192.

The pharynx. — The pharynx or throat cavity is a musculo-
membranous bag, shaped somewhat like a cone, with its broad

Fig. 113. — The Mouth, Nose, and
Pharynx, with the Larynx and
Commencement of Gullet, seen
in Section, a, vertebral column ; 6,
gullet; c, trachea; d, larynx; e, epi-
glottis ; /, soft palate, between/ and e
is the opening at back of cavity or
fauces ; g, opening of Eustachian tube;
h, nasal cavity; k, tongue; I, hard
palate; m, sphenoid bone at base of
skull ; n, roof of nasal cavity ; o, p, q,
placed in nasal cavity.

180 ANATOMY FOR NURSES. [Chap. XV.

end turned upwards, and its constricted end downwards to end
in the oesophagus. It is about four and a half inches (114 mm.)
long, and lies behind the nose, mouth, and larynx. Above, it
is connected with the base of the skull, and behind, with the
cervical vertebrae ; in front and on each side are apertures
which communicate with the nose, ears, mouth, and larynx.

Of these apertures there are seven : two in front above, lead-
ing into the back of the nose, the posterior nares ; two, one on
either side above, leading into the Eustachian tubes which com-
municate with the ears ; one midway in front, the fauces ; and
two below, one opening into the larynx and the other into the
oesophagus. The mucous membrane lining the pharynx is well
supplied with glands, and at the back of the cavity there is a
considerable mass of lymphoid tissue. The muscular tissue in
the walls of the pharynx is of the striped variety, and when the
act of swallowing is about to be performed the muscles draw
the pharyngeal bag upwards and dilate it to receive the food ;
they then relax, the bag sinks, and other muscles contracting
upon the food, it is pressed downwards and onwards into the
oesophagus.

The oesophagus or gullet. — The oesophagus is a comparatively
straight tube, about nine inches (228 mm.) long, extending from
the pharynx, behind the trachea, and through the diaphragm, to
its termination in the upper or cardiac end of the stomach.
The muscular fibres in the walls of the oesophagus are arranged
in an external longitudinal and in an internal circular layer.
The mucous membrane is disposed in longitudinal folds which
disappear upon distension of the tube. The mucous mem-
brane in the mouth, pharynx, and oesophagus is covered for
the most part by stratified epithelium.

The stomach. — The stomach is the most dilated portion of
the alimentary canal. It is curved upon itself, so that below it
■ presents along, rounded outline, called the greater curvature,
and above a constricted, concave outline, called the lesser
curvature.

It is placed transversely in the abdominal cavity, immediately
beneath the diaphragm, the larger expanded end lying in con-
tact with the spleen, and the smaller end under the liver. The
stomach has necessarily two openings : the one leading into the
oesophagus is usually termed the cardiac aperture ; the other,

Chap. XV.]

ALIMENTATION.

181

leading into the small intestine, the pyloric. The pyloric aper-
ture is guarded by a kind of valve composed of circular mus-
cular fibres, which form a constricted ring projecting into the
pyloric opening. By this arrangement, the food is kept in the
stomach until it is ready for intestinal digestion, when the cir-
cular fibres relax and allow it to pass.

When moderately distended, the stomach measures about
four inches (102 mm.) vertically and twelve inches (305 mm.)
from side to side. It has four coats. The outer serous coat is
formed by a fold of the peritoneum. The fold is slung over
the stomach, in much the same way as we sling a towel over a

Fig. 114. — Vertical and Longitudinal Section of Stomach, Gall-bladder,
AND Duodenum. 1, oesophagus; 2, cardiac orifice of stomach; 5, lesser curvature;
6, greater curvature; 8, rugre in interior of stomach; 9, pyloric orifice; 10, 11,
13, interior of duodenum, showing valvulffi conniventes; 12, duct conveying bile, and
P, duct conveying pancreatic juice, into the duodenum; 14, gall-bladder; 15, com-
mencement of jejunum.

clothes-line, and covers it before and behind. The anterior and
posterior folds unite at the lower border of the stomach and
form an apron-like appendage, the omentum, which covers the
whole of the intestines. The omentum often contains a large
amount of fat.

The muscular coat of the stomach consists of three layers of
unstriped muscular tissue : an outer, formed of longitudinal
fibres ; a middle, of circular ; and an inner, of less well-devel-

182

ANATOMY FOK NURSES.

[Chap. XV.

oped, obliquely disposed fibres. The alternate contraction and
relaxation of these fibres causes the food to be carried round
and round the stomach, and at the same time, subjects it to
considerable pressure.

The mucous membrane is very soft and thick, the thickness
being mainly due to the fact that it is densely j)acked with small
tubular glands ; it is covered with columnar epithelium, and in
its undistended condition is thrown into folds or rugai. The
surface is honeycombed with tiny shallow
pits, into which the ducts or mouths of the
tubular glands open. The glands are of
two kinds, one kind secretes mucus, and the
other the special secretion of the stomach,
the gastric juice. The stomach is supplied
with nerves from the sympathetic system,
and also with branches from the pneumo-
gastric nerve, which comes from the cerebro-
spinal system.

The small intestine. — The small intestine
fills the greater part of the front abdominal
cavity. It is a convoluted tube about
twenty feet (G.O metres) in length, and
gradually diminishes in size from its com-
mencement to where it joins the large
intestine. The small intestine is divided
by anatomists into three portions. The
first ten or twelve inches (254 to 305 mm.)
is called the duodenum ; the succeeding
two-fifths, the jejunum ; and the rest, the
ileum. The intestines are invested by a fold of the peritoneum
in much the same way as the stomach. In this situation, the
fold of the peritoneum is called the mesentery, and between
its two layers are numerous blood-vessels, lymphatics, and
lymphatic glands.

The muscular coat of the small intestine has only two layers :
an outer, thinner and longitudinal ; and an inner, thicker and
circular.

The mucous coat is highly developed. In the first place it
is largely increased by being arranged in permanent folds, the
valvulte conniventes (^vide Fig. 114), which project transversely

Fig. 115. — An Intes-
tinal Villus. «, a, a,
columnar epithelium ;
6, b, capillary network;
c, c, lymphoid tissue
and muscle fibres; d,
lacteal vessel.

Chap. XV.]

ALIMENTATION.

183

into the interior of the tube. The onward course of the food
is delayed by being caught in the hollows formed hy these
folds, and thus more thoroughly subjected to the action of the
digestive juices : this arrangement also affords a larger surface
for absorption. The valvulse conniventes are not found in the
beginning of the duodenum, but begin to appear one or two
inches from the pylorus ; about the middle of the jejunum they
begin to decrease in size, and in the lower part of the ileum
they almost entirely disappear.

Again, the surface of the mucous membrane is increased by
the linger-like projections which are so close set as to give a

Fig. 116. — Sectiox through the Lymphoh) Tissue of a Solitary Glanb.
(Cadiat.) a, centre of the gland, with the lymphoid tissue fallen away; b, epithe-
lium of mucous memhrane ; c, c, villi, with epithelium partly broken away ; d, crypts,
or glands, of Lieberkiihu.

shaggy or velvety appearance to the membrane. These projec-
tions or villi, as they are termed, extend throughout the whole
length of the small intestine, and are especially provided for
purposes of absorption. Each villus is a portion of the mucous
membrane, and consists of an external layer of columnar cells
attached to a basement membrane, and of a central mass of lym-
phoid tissue. In the centre of each villus is the rootlet of a
lacteal vessel, while under the basement membrane is a network
of capillaries. The blood-vessels and lymphatics of the villi
communicate with networks of both vessels in the sub-mucous

184

ANATOMY FOR NURSES.

[Chap. XV.

coat below. Besides these projections formed for absorption,
the mucous membrane is thickly studded with secretory glands ;
the larger number of these, found all over the surface of the
intestine, are called the glands or crypts of Lieberkiihn. These
glands are supposed to secrete the intestinal juice, suceus en-
tericus.

Again, in the corium of the mucous coat the lymphoid tissue
is collected into numerous solitary ghmds or follicles, and into
groups of glands, the Peyer's patches, the functions of which
are not yet clearly understood.

The large intestine. — The large intestine is about five feet
(1.5 metres) long, and from two and a
half to one and a half inches (63 to 38
mm.) wide; it extends from the ileum
to the anus. It is divided into the
Ctecum, with the vermiform appendix,
the colon, and the rectum.

The ccecum {ccecus, blind) is a large
blind pouch at the commencement of
the large intestine. The small intes-
tine opens into the side wall of the
large intestine about two and a half
inches (63 mm.) above its — the large
intestine's — commencement, the coecum
forming a cul-de-sac below the opening.

Fig. 117. — Cmcvm, show- * j.j_ i j j. xt. i i r j_i

iNGiTs Appendix, Entrance Attached to the iower end 01 the csecum

OF Ileum, and Ileo-c^cal ig a narrow, worm-likc tube about the

Valve. 1, caecum; 2, com- . c ^ ^ ■^ t

meiicement of colon; 3, en- size ot a lead pencil, the veriiiitorm

trance of ileum into the large
intestine; 4, ileo-cpecal valve;

appendix. The Ccecum and appendix
6, aperture of vermiform ap- lie just beneath the abdominal Avail in

pendix; 7, vermiform appen. ^^^^ ^^-^^^^ -^-^^ ^^^^.^^^ ^^, .^^^ p^^^^ y^^^

The opening from the ileum into the large intestine is provided
with two large projecting lips of mucous membrane which allow
the passage of material into the large intestine, but effectually
prevent the passage of material in the opposite direction. These
mucous folds form what is known as the ileo-csecal valve.

The colon may be subdivided into the ascending, transverse,
and descending colon, and the sigmoid flexure. The ascending
portion runs up on the right side of the abdomen until it reaches
the liver, then bends abruptly to the left, and is continued

Chap. XV.] ALIMENTATION. 185

straight across the abdomen as the transverse colon until, reach-
ing the left side, it turns abruptly and passes downwards as the
descending colon. Reaching the left iliac region on a level with
the margin of the crest of the ileum, it makes a curve like the
letter S, — hence its name of sigmoid flexure, — and finally ends
in the rectum. The rectum is from six to eight inches (152 to
203 mm.) long ; it passes obliquely from the left until it reaches
the middle of the sacrum, then it follows the curve of the sacrum
and the coccyx, and finally arches slightly backwards to its
termination at the anus. The anal opening is guarded by two
circular muscles called, respectively, the internal and external
sphincters.

The large intestine has the usual four coats, except near its
termination, where the serous is wanting. The muscular coat,
along the Ctecum and colon, has a peculiar arrangement. The
longitudinal fibres are gathered up in three thick bands, and
these bands, being shorter than the rest of the tube, the walls are
puckered between them. The mucous coat possesses no villi
or valvules conniventes, but is usually thrown into effaceable
folds, somewhat like those of the stomach. It contains nu-
merous glands, resembling the crypts of Lieberkiihn found in
the small intestine.

Accessory organs of digestion. — The accessory organs of diges-
tion are the teeth and salivary glands (which have already been
sufficiently described), the pancreas, and the liver.

The pancreas. — The pancreas is a compound, secreting gland,
closely resembling the salivary glands in structure, except that
the secreting cavities are saccular in the salivary glands, and
more distinctly tubular in the pancreas. The cavities are
grouped in small lobes or lobules, each lobule having its own
duct. The lobules are joined together by connective tissue to
form lobes, and the lobes, united in the same manner, form the
gland. The small ducts open into one main duct, which, run-
ning lengthwise through the gland, pierces the coats of the duo-
denum and pours its contents into the interior of the intestine.
The secretion formed in the pancreas is called the pancreatic juice.

In shape, the pancreas somewhat resembles a dog's tongue.
It is a flat, elongated organ, about six to eight inches (152 to
203 mm.) in length, one and a half inches (38 mm.) in width,
and from half an inch to an inch (12.7 to 25.4 mm.) thick.

18G

Al^ATOMY FOR NURSES.

[Chap. XV.

It lies beneath the greater curvature of the stomach and at the
back of the abdominal cavity.

The liver. — The liver is the largest gland in the body, weigh-
ing ordinarily from fifty to sixty ounces (1-118 to 1701 grammes),
and measuring ten to twelve inches (251 to 305 mm.) from side
to side, six to seven (152 to 178 mm.) from above downwards,
and three inches (76 mm.) from before backwards in its thick-
est part. It is a dark reddish-brown organ, placed in the upper
right and middle portion of the abdomen, and extending some-
what into the left hypochondriac region. The upper convex

Fig. 118. — Posterior View of Pancreas. 1, pancreas; 2, pancreatic duct; 6,
opening of coninion duct, formed by union of pancreatic and clioledoclius ducts, into
duodenum; A, pyloric end of stomach; B, duodenum; C, part of gall-bladder; JJ,
cystic duct ; E, hepatic duct ; F, choledochus duct.

surface fits closely into the under surface of the diaphragm.
The under concave surface of the organ fits over the right kid-
ney, the upper portion of the ascending colon, and the pyloric
end of the stomach. The liver is unequally divided into two
lobes, the right being much larger than the left. It is covered
by a layer of peritoneum, and is also suspended and kept in
position by ligamentous bands.

The liver not only differs in size from the other secreting
glands ; it also offers other striking peculiarities. First, it re-
ceives its supply of blood from two different sources ; namely,
arterial blood from the hypatic artery, and venous blood from
the stomach, spleen, pancreas, and intestines, by means of the

Chap. XV.]

ALIMENTATION.

187

portal vein.i Secondly, the different parts of the secretory
apparatus, the cells, blood-vessels, and ducts, instead of being
arranged as elsewhere in distinct tubes or sacs, are closely
united and massed togetlier. The secreting cells are collected
into small polyhedral or many-sided masses, called hepatic
lobules ; the blood-vessels form networks around and in the
lobules ; while the ducts which carr}^ away the secretion (bile)
begin Avithin the lobules in the form of tiny channels, running
between the cells.

Fig. 119. — Unde:i Sukface of Liver, i, right lobe; 2, left lobe; 3, 4, 5, smaller
lobes; 9, inferior vena cava; 10, gall-bladder; 11, 11, transverse fissure, or "gate of
the liver," containing bila duct, hepatic artery, and portal vein.

The whole liver is invested in an envelope or capsule of con-
nective tissue (Glisson's capsule), and the lobules are divided
from one another by very delicate partitions of areolar tissue,
each lobule being about the size of a pin's head and filled witli
the special liver cells.

The large portal vein and the small hej^atic artery enter the
liver together on its under surface at what is called the " gate
of the liver," the bile duct passing out at the same place. Tlie
branches of these three vessels, enclosed by loose connective
tissue, in which are lymphatics and nerves, accompany one
another in their course through the organ. The smallest
1 Cf. note on lungs, p. 131.

188

ANATOMY FOR NURSES.

[Chap. XV.

branches penetrate between the lobules, and, surrounding and
lying between each lobule, are known as the mterlohular
branches. From the interlobular branches of the portal vein,
thus surrounding the circumference of each lobule, run capillary-
vessels, somewhat like the spokes of a wheel. These capillaries,
converging towards the centre, merge into a veinlet, the intra-
lobular vein, which running down the middle of the lobule,
empties into a vein at its base. This vein, lying at the base of
each lobule, is called the suhlohular vein, and empties its con-
tents into the hepatic veins, by means of which the blood is
conveyed from the back of the liver into the inferior vena cava.

Fia. 120. — Diagrammatic Representation of Two Hepatic Lobules. The
left hand lobule is represented with the intralobular vein cut across; in the right
hand one the section takes the course of the intralobular vein, p, interlobular
branches of the portal vein; /*, intralobular branches of the hepatic veins; s, sub-
lobular vein ; c, capillaries of the lobules. The arrows indicate the direction of the
course of the blood. The liver-cells are only represented in one part of each lobule.

Thus each lobule is a mass of hepatic cells, pierced everywhere
with a network of blood capillaries.

The bile ducts commence between the hepatic cells in the
form of fine canaliculi lying between the adjacent sides of two
cells and forming a close network, the meshes of which corre-
spond in size to the cells. At the circumference of the lobules,
these fine canaliculi pass into the interlobular bile ducts which,
running in connection with the blood-vessels, finally empty into
the two bile ducts which leave the liver at the opening, spoken
of above as the "gate of the liver."

The cells of the liver manufacture bile from the blood, and

Chap. XV.]

ALIMENTATION.

189

discharge this into the minute bile canaliculi, whence it passes
into the bile ducts to be conveyed into the small intestine.
The cells, however, perform another important function, in that
they change some of the substances brought to them in the
blood from the digestive organs in such a manner as to render
these substances suitable for the nutrition of the body ; but, at

Fig. 121. — Lobule of Rabbit's Liver, Vessels and Bile Ducts Injected.
a, central or intralobular vein; b, b, interlobular veins; c, interlobular bile duct.

present, it will be sufficient to consider the secretion of bile as
the only function of the liver.

The bile is taken from the liver by a right and left duct,
which soon unite to form the hepatic duct. The hepatic duct
runs downwards and to the right for an inch and a half (38 mm.),
and then joins at an acute angle the duct from the gall-bladder,

190 ANATOMY FOR NURSES. [Chap. XV.

termed the cystic duct. The hepatic and cyslic ducts tof^ether
form the common bile duct (^ductus communis choledochus^,
which runs downwards for about three inches (76 mm.) and
enters the duodenum at the same opening as the pancreatic
duct.

The gall-bladder {vide Fig. 119) is a pear-shaped sac, lodged
in a depression on the under surface of the right lobe of the
liver. It is lined by columnar epithelium, and its walls are
formed of fibrous and muscular tissue. It is held in position
by the peritoneum, and serves as a reservoir for the bile. Dur-
ing digestion the bile is poured steadily into the intestine ; in
the intervals it is stored in the gall-bladder.

To recapitulate : the digestive apparatus may be said to con-
sist of a tube and of important accessory organs placed in close
connection and communication with it. For convenience of
description, the tube may be divided into sections, each of which
is furnished with mechanical and chemical appliances for reduc-
ing the food into a soluble condition. First, the mouth cavity,
which is provided with muscular cheeks and movable jaw,
tongue, teeth, and the chemical solvent, saliva, secreted by the
salivary glands ; secondly, the two passages, the pharynx and
oesophagus, serving to convey the food into the next section,
the stomach, which is furnished with muscular walls for crush-
ing and churning the food, and with glands to secrete the acid
digestive solvent, the gastric juice ; thirdly, the small intestine,
supplied with bile and pancreatic juice, and with a highly
specialized mucous membrane adapted to both digestive and
absorptive purposes ; and lastly, the large intestine, having
feeble digestive properties, but serving to absorb all the nutri-
tious portion of the food still remaining, and to pass the residue
onwards to be finally thrown out of the body in the form of
feces.

CHAPTER XVI.

ALIMENTATION CONCLUDED: DIGESTION; CHANGES THE FOOD
UNDERGOES IN THE MOUTH, STOMACH, SMALL AND LARGE
INTESTINE; SUMMARY OF DIGESTION; ABSORPTION.

Digestion. — Digestion is the process by means of which the
food we take into our mouths is transformed into a condition
of solution or emulsion suitable for absorption into the blood.
This transformation is rapid or gradual according to the nature
of the food-stuffs the digestive solvents are called upon to dis-
solve. We all know practically, for instance, that it takes much
longer to digest a piece of beefsteak than a cup of bouillon, and
that when we wish to save the digestive powers as much as pos-
sible we place a person upon "liquid diet."

The digestion of the various food-stuffs depends entirely on
the action of a class of substances known as enzymes or fer-
ments. Although the exact composition and method of action
of enzymes is not understood, it may be said that an enzyme is
a substance a small amount of which, under certain conditions,
can by its presence convert certain other substances into still
other substances without itself being destroyed, or weakened
in any way. Thus, a small amount of the enzyme, pepsin, can
in an acid solution convert proteids into another class of sub-
stances known as peptones, without diminution in the quantity
or strength of the pepsin used. The enzymes are usually the
products of living organisms, and are not found in inorganic
matter.

Remembering that the three solid food-stuffs are proteids,
fats, and carbohydrates, we will proceed to describe how each
of these is transformed into a soluble condition in its course
through the alimentary canal.

191

192 ANATOMY FOR NURSES. [Chap. XVI.

Changes the food undergoes in the mouth ; mastication and deg-
lutition. — When solid food is taken into the mouth it is cut
and ground by the teeth, being pushed between them again and
again by the muscular contractions of the cheeks and the move-
ments of the tongue until the whole is thoroughly crushed and
ground down. During this process of mastication the salivary
glands are excited to very active secretion, the saliva is poured
in large quantities into the mouth, and mixing with the food
moistens it and reduces it to a soft pulpy condition. A certain
amount of air caught in the bubbles of the saliva also becomes
entangled in the food.

The food thus softened and moistened is collected from every
part of the mouth by the movements of the tongue, brought
together upon its upper surface, and then pressed backwards
through the fauces into the pharynx. The elevation of the
soft palate prevents the entrance of food into the nasal cham-
bers, while the epiglottis bars its entrance into the air passages,
and it is guided safely and rapidly through the pharynx into the
oesophagus. Here it passes beyond the control of the will ; it
is grasped by the oesophageal muscles and by a continuous and
rapid peristaltic action is carried onwards and downwards into
the stomach.

Saliva. — Mixed saliva (spittle) as it appears in the mouth
is a glairy, frothy, cloudy fluid, the glairiness or ropiness being
due to mucus; micro-organisms are also present in it to some
extent, and other foreign matters derived from the food.

Saliva is mainly water containing but little solid matter, its
specific gravity varying from 1002 to 1006. It depends for its
special action, as a digestive solvent, upon an enzyme or fer-
ment which it contains called ptyalin.

The action of saliva upon the food. — The chief function of
saliva is to soften and moisten the food and to assist in masti-
cation and deglutition. It has, however, a certain digestive
action upon food-stuffs, especially starch. Upon the fats and
proteids it has very little effect except to render them softer
and better prepared for the action of the other digestive
juices.

By the ptyalin-ferment present in saliva, starch, which is an
insoluble substance, is changed into malt sugar or maltose, a
highly soluble and absorbable product. This change is best

Chap. XVI.] ALIMENTATION. 193

effected at tlie temperature of the body, in a slightly alkaline
solution, saliva that is distinctly acid hindering or arresting
the process. Boiled starch is changed more rapidly and com-
pletely than raw, but the food is never retained in the mouth
long enough for the saliva to more than begin the transforma-
tion of starchy matters. After leaving the mouth, further con-
version of starch into sugar is arrested by the acid reaction of
the gastric juice, and digestion of this class of food-stuffs is
practically suspended until they again come in contact with
the alkaline secretions in the upper part of the small intestine.

During the processes of mastication, insalivation, and deglu-
tition, the food is first reduced to a soft pulpy condition ; sec-
ondly, any starch it may contain begins to be changed into
sugar ; thirdly, it acquires a more or less alkaline reaction.

Changes the food undergoes in the stomach. — The entrance of
food into the stomach acts as a stimulant to the whole organ.
The blood-vessels dilate, the glands pour out an abundant secre-
tion upon the mucous lining, and the different layers of the
muscular coat are excited to a continuous action. Delayed in
the stomach by the contraction of the pyloric ring-muscle, the
puljDy mass of food is carried round and round, and thoroughly
mixed with the gastric juice until it is dissolved into a thick,
grayish soup-like liquid, called chyme. The chyme thus formed
is from time to time ejected through the pylorus, accompanied
by morsels of solid, less well-digested matter. This ejection
may occur within a few minutes after the entrance of food into
the stomach, but does not usually begin until from one to two
hours after, and lasts from four to five, at the end of which
time the stomach is, after an ordinary meal, completely emptied.

Gastric juice. — Gastric juice, secreted by the small, tubular
glands ill llie mucous lining of the stomach, is a thin, colour-
less, or pale yellow fluid, of an acid reaction. It contains few
solids, and is dependent for its specific action upon two enzymes
called pejysin and rennin. Pepsin is only properly active in an
acid solution, and we therefore find that free hydrochloric acid
in the proportion of 0.2 per cent is always present in normal
gastric juice.

Action of gastric juice upon the food. — The gastric juice has
no action upon starch, and upon fats it has at most a limited
action; that is, if adipose tissue be eaten, it will dissolve the

194 ANATOMY FOR NURSES. [Chap. XVI.

envelopes of the fat-cell and set the fat free, but it has no
power to emulsify them. The essential property of gastric
juice is the power it has of decomposing proteid matters and
of converting them into a soluble substance called peptone.
Whatever the proteid may be, whether the albumin of eggs,
the gluten of flour in bread, the myosin in flesh, the result is
the same, pepsin, in conjunction with an acid at the temperature
of the body, transforms them into peptones.

Peptones readily dissolve in water, and pass with ease through
animal membranes. They are probably absorbed, as soon as
formed, by the blood-vessels in the walls of the stomach, though
some pass in the chyme through the pylorus into the small
intestine.

Changes the food undergoes in the small intestine. — The chyme
on entering the duodenum, after an ordinary meal, is a mixture
of various matters. It contains some undigested proteids ; some
undigested starch ; oils from fats eaten ; peptones formed in the
stomach, but not yet absorbed ; salines and sugar which have
also escaped complete absorption in the stomach ; all mixed with
a good deal of water and the secretions of the alimentary canal.
This acid mixture passing into the duodenum excites reflexly
the secretory action of the pancreas, and stimulates the bile to
flow from the gall-bladder ; the glands of Lieberkiihn also be-
come active, and all these secretions proceed to further change
the food-stuffs that have escaped digestion in the stomach.

Bile. — Bile, secreted in the lobules of the liver and stored in
the gall-bladder until needed, is a fluid of a bright golden red
colour, with an alkaline reaction. The chief solid constituents
of bile are cholesterin, the bile-salts, and the colouring-matters
or pigments.

Action of bile on food. — Upon proteids and starch, bile has
little or no digestive action. On fats, it has a slight solvent
action, and, in conjunction with pancreatic juice, has the power
to emulsify them. When bile is prevented from flowing into the
alimentary canal, the contents of the intestine undergo changes
which do not otherwise take place, and which lead to the devel-
opment of various products, especially of ill-smelling gases.
Lastly, the passage of fats through membranes is assisted by
wetting the membranes with bile or with a solution of bile-
salts. It is known that oil will pass to a certain extent through

Chap. XVI.] ALIMENTATION. 195

a filter-paper, kept wet with a solution of bile-salts, whereas it
will not pass, or passes with extreme difficulty, through one kept
wet with distilled water.

Pancreatic juice. — Healthy pancreatic juice is a clear, some-
what viscid tiuid, with a very decided alkaline reaction. It is
actively secreted by the pancreas during digestion and flows
into the intestine in conjunction with the bile. The Germans
call the pancreas the " abdominal salivary gland," though the
pancreatic juice has a far more extensive action than the saliva.

Among other important constituents the pancreatic juice con-
tains an enzyme called trypsin, which, like pepsin, has the power
to transform proteids into peptones ; trypsin, however, requires
an alkaline medium to effect this transformation, while pepsin,
as we have already seen, requires the medium to be acid.

Action of pancreatic juice upon food. — On starch pancreatic
juice acts with great energy, rapidly converting it into mal-
tose. On proteids it practically exercises the same influence
as the gastric juice, for by it proteids are changed into peptones.
On fats it has a twofold action : it emulsifies them, and it splits
them up into fatt}^ acids and glycerine. If we shake up olive
oil with water, the two cannot be got to mix : as soon as the
shaking ceases, the oil floats to the top ; but if we shake up
olive oil with pancreatic juice, the oil remains evenly suspended
in it. The reason of this is, that the oil has been minutely
divided into tiny droplets, and each droplet surrounded by a
delicate envelope supplied from the albumin in the pancreatic
juice, so that they cannot fuse together to form the large drops,
which would soon float to the top.^ Secondly, the fats that are
not emulsified are broken up into glycerine and fatty acids. The
glycerine is absorbed, and the fatty acids in the presence of an
alkali form soaps which are soluble in water and capable of
absorption. It is probable that the greater part of the fat is
absorbed by the latter method.

Thus pancreatic juice is remarkable for the power it has of
acting on all the food-stuffs, — starch, fats, and proteids.

Succus entericus, or intestinal juice. — Succus entericus is a
clear, yellowish fluid, having a faintly alkaline reaction and

1 The pancreatic juice, in thus emulsifying the fats, gives the white colour to
the chyle, which is its most striking external characteristic, the innumerable
tiny oil-drops reflecting all the light that falls on its surface.

196 ANATOMY FOR NURSES. [Chap. XVI.

containing a certain quantity of mucus. It is said to have a
solvent action upon all the food-stuffs, but at best its powers
are slow and feeble, and we have no satisfactory reason for
supposing that the actual digestion of food in the intestine is
to any great extent aided by it.

During the passage of the food through the small intestine
the remaining proteids, starch, and fats are converted into pep-
tones, sugar, and emulsified fats or soluble soaps, and these
products as they are formed pass either into the lymphatics,
or into the blood-vessels in the intestinal walls, so that the
contents of the small intestine, by the time they reach the ileo-
csecal valve, are largely deprived of their nutritious constitu-
ents. So far as water is concerned, the secretion of water into
the small intestine maintains such a relation to the absorption
from it that the intestinal contents at the end of the ileum,
though otherwise much changed, are about as fluid as in the
duodenum.

Changes in the large intestine. — We have no very definite
knowledge of the particular changes which take place in the
large intestine. The contents are acid, although the secretions
of the intestinal wall are alkaline, and certain acid fermenta-
tions must therefore take place in them. These are probably
due to the action of micro-organisms ; but however this may
be, the chief work of the colon is absorption.

By the abstraction of all the soluble constituents, and espe-
cially by the withdrawal of water, the liquid contents become,
as they approach the rectum, changed into a firm and solid
mass of waste matters, ready for ejection from the body, and
called feces.

The feces. — The feces consist of the undigested and indigesti-
ble substances of the food : among them are the elastic fibres of
connective tissue ; the cellulose, which is the chief constituent
of the envelopes encasing the cells of plants ; the indigestible
mucin of mucus. These three materials, together with some
water, some undigested food-stuffs, and some excretory sub-
stances found in the various secretions poured into the aliment-
ary canal, form the bulk of the material expelled from the body.

To sum up the digestive processes : —

The transformation of the food we take into our mouths into
products capable of absorption is mainly a chemical process.

Chap. XVI.] ALIMENTATION. 197

The mechanical subdivision, bruising, and crushing of the food,
accomplished by the teeth and the muscular contractions of the
walls of the alimentary canal, is merely a process of preparation
for the solvent action of the digestive juices. Of these juices
there are five, each having a special action.

(1) The saliva, containing the digestive enzyme ptyalin,
transforms starch into sugar.

(2) The gastric juice, containing the enzyme rennin, and
pepsin (an enzyme acting in the presence of an acid), trans-
forms proteids into peptones.

(3) The pancreatic juice, containing trypsin (an enzyme
acting in the presence of an alkali), transforms proteids into
peptones, and, by virtue of other constituents, transforms
starch into sugar, and emulsifies fats or turns them into solu-
ble soaps.

(4) Bile, containing cholesterin, bile-salts, and other matters,
assists the pancreatic juice in saponification and emulsion of
fats, promotes absorption of the same, and modifies putrefactive
changes in the intestine.

(5) Intestinal juice, containing mucus, transforms all food-
stuffs in a feeble fashion not clearly demonstrated nor under-
stood.

All material that these solvents fail to transform into a soluble
and absorbable condition is gradually worked downwards by
the peristaltic contractions of the alimentary canal, and finally
leaves the body as waste and useless matter.

Note. — For the sake of simplicity, we have considered digestion in a broad
way as the conversion of practically non-diffusible proteids and starch into more
diffusible peptones and higiily diffusible sugar, and as the emulsifying and split-
ting up of fats. There is reason to believe that some of the sugar may be
changed into lactic acid, or even into butyric or other acids, and that some of
the proteids are carried beyond the peptone condition. But there is no doubt
that the greater part of the proteid is absorbed as peptone, that carbohydrates
are mainly absorbed as sugar, and that the greater part of the fat passes into
the body as an emulsion.

Absorption. — We have now to consider how the products of
digestion find their way out of the alimentary canal into the
tissues of the body ; for, properly speaking, though the food
may be digested and ready for nutritive purposes, it is, until
it passes through the walls of the alimentary canal, still practi-
cally outside the body.

198 ANATOMY FOK NURSES. [Chap. XVL

There are two paths by means of which the products of diges-
tion find their way into the blood : (1) by the capillaries in the
walls of the stomach and intestines ; and (2) by the lymphatics
in the walls of the small intestine (the lacteals).

(1) The network of capillary blood-vessels is spread, as we
have seen (page 168), immediately beneath the basement mem-
brane of the mucous coat lining the interior of the alimentary
canal, and matters in solution pass readily by diffusion or osmo-
sis from the interior of the stomach and intestines into the
blood-vessels in their walls. All the blood from the digestive
organs is taken by the portal vein to the liver, and the products
of digestion are modified by the action of the liver before they
are returned to the general circulation by the hepatic veins.
The hepatic veins pour their contents into the inferior vena
cava, and the blood, enriched with the products of digestion,
finally finds its way into the right side of the heart, whence it
is taken to the lungs for purification before being sent to all
parts of the body.

During the passage of the blood through the liver the liver-
cells not only take from it the material they need to form the
bile; they also take from it material to form a starchy sub-
stance, called glycogen. This glycogen, stored in the liver-cells,
is gradually doled out, as it is needed, to the blood. It is not
doled out, however, in the form of glycogen, which closely
resembles starch, and is, therefore, insoluble, but in the form
of sugar (dextrose or glucose). Thus the liver is a very com-
plex organ whose cells elaborate bile and glycogen, and by
some ferment-body, contained within themselves, convert the
glycogen into glucose. J

(2) Matters in solution can pass into the blood-vessels, but
some other provision is necessary for the absorption of the
emulsified fats. We find, accordingly, in the villi, which so
closely cover the internal surface of the small intestine, little
rootlets or beginnings of lymphatic vessels, which are set apart
for the absorption of the fatty products of digestion.

These lymphatic rootlets or lacteals, as they are generally
called, occupy the centre of each villus. The emulsified fats
pass, probably aided by the bile, into the bodies of the columnar
cells on the surface of the villi, and from thence find their way
into the interior of the villus, and finally into the beginning of

Chap. XVI.] ALIMENTATION. 199

the lacteal. The lacteals carry this fatty matter or chyle to
the larger lymphatics in the mesentery, and these empty their
contents into the thoracic duct which opens above into the great
veins on the riglit side of the neck.

Thus the food in solution after passing through the liver,
and the emulsified food after passing through the lymphatics,
find their way into the right side of the heart. It is not to be
understood that matters in solution do not find their way into
the lacteals, nor, on occasion, emulsified fats into the blood-
vessels, but, broadly speaking, the food-products find their way
into the blood in the manner above described.

Final destination of food-stuffs. — It is impossible to say defi-
nitely what becomes of the different food-principles after they
have once entered the current of the blood. In general, it may
be said that the carbohydrates are used for the production of
heat and work, and that the fats may be stored in the body and
used as fuel. The proteids do all that can be done by the fats
and carbohydrates, and, in addition, form the basis of blood,
muscles, and all the connective tissues.

Still we cannot say that the carbohydrates perform a cer-
tain work in the body and nothing else, or that the pro-
teids and fats do. It is, however, generally understood that
the proteids, fats, and carbohydrates each do an individual
work of their own better than either of the others can do
it. They are also necessary in due proportion to the nutri-
tion of the body and work together as well as in their separate
functions.

The body has always a store of material laid by for future
use. If this were not the case, a person deprived of food
would die immediately, as he does when deprived of oxygen.
The great reserve forces of the body are stored in the form
of adipose tissue and glycogen. The glycogen is given out
during the intervals of eating to supply material for heat
and energy; the adipose tissue is not so readily available,
but may be called upon during prolonged deprivation from
food. For a certain time the heat of the body may be main-
tained and work done on these substances, although no food
except water be taken.

In conclusion we may say the food in the blood supplies the
wants of the body in five different ways : —

200 ANATOMY FOR NURSES. [Chap. XVL

" 1. It is used to form all the tissues of the body.

" 2. It is used to repair the waste of all the tissues.

" 3. It is stored in the body for future use.

" 4. It is consumed as fuel to maintain the constant tempera-
ture which the body must always possess in a state of health.

"5. It produces muscular and nervous energy." (Professor
At water.)

CHAPTER XVII.

ELIMINATION; GENERAL DESCRIPTION OF THE URINARY OR-
GANS; STRUCTURE AND BLOOD-SUPPLY OF KIDNEY; SECRE-
TION OF URINE; COMPOSITION AND GENERAL CHARACTERS
OF URINE.

In the last four chapters we have seen that the blood is con-
stantly supplied by means of the respiratory and digestive
mechanisms, with all the chemical substances it requires to
maintain the life, growth, and activity of the body. These sub-
stances, entering the current of the blood, are carried to all the
tissues, and are incessantly combining with the chemical sub-
stances of which these tissues are composed. These combina-
tions are not left to chance ; each tissue has a special affinity
for the chemical substance in the blood which it requires for its
own growth and special form of activity ; the secretory cell of
the liver picks out substances from which it can manufacture
bile and glycogen ; the muscle fibre assimilates those that will
promote the changes upon which depends the power of con-
tractility. We know that the proteid compounds contain the
most essential elements for the formation of all kinds of tissue,
and that phosphate of lime is a necessary ingredient in the
hardening of bone, but we are utterly ignorant of how it comes
about that each tissue element is enabled to select the particular
material it needs and to reject that which it does not require.

Our bodies are masses of changing atoms, some of which, if
we may so express it, are on the " up grade," to construct the
various tissues, and some are on the " down grade," to form the
waste matters which are the final products of the tissues' activ-
ity. These changes, which are incessantly going on while life
lasts, are described under the general term of metabolism ; the
constructive changes being spoken of as anabolic, and the de-
structive as katabolic, changes. The final products then of

201

202 ANATOMY FOR NURSES. [Chap. XVII.

the metabolism of the body will be certain waste matters, and
we shall now proceed to describe the mechanism of the organs
by means of which these wastes are removed from the body.

Elimination. — In passing through the blood and tissues of the
body, the proteids, fats, and carbohydrates are transformed into
urea (or some closely allied product), carbon dioxide, and water,
the nitrogen of the urea being furnished by the proteids alone.
Many of the proteids contain sulphur and also have phosphorus
attached to them in some combination, and some of the fats
taken as food contain phosphorus ; these elements are converted
by oxidation into phosphates and sulphates, and are excreted in
that form in company with the other salts of the body.

Broadly speaking, then, the waste products are urea, carbon
dioxide, salts, and water. These leave the body by one or other
of three main channels, the lungs, the skin, and the kidneys.
Some part, it is true, leaves the body by the bowels, for, as we
have seen, the feces contain, besides undigested portions of food,
substances which have been secreted into the bowels, and are
therefore waste products ; but the amount of these is very small
and, except in diseased conditions, of no special importance.

The waste matters discharged relatively by the lungs, skin,
and kidneys may be stated as follows : —

By the lungs • The greater part of the carbon dioxide.

A considerable quantity of water.
By the skin : A variable but, on the whole, large quantity of

water.

A little carbon dioxide.

A small quantity of salts.
By the kidneys : All, or nearly all, the urea and allied bodies.

The greater portion of the salts.

A large amount of water.

A very small quantity of carbon dioxide.

We have already studied the mechanism by means of which
the lungs rid the blood of carbon dioxide and water, and it now
remains for us to consider the mechanism of the skin and kid-
neys. In the present chapter we shall devote ourselves to the
consideration of the kidneys, which secrete the urine, and the
other urinary organs, the ureters, bladder, and urethra, which
collect the urine and conduct it to the outside of the body.

Chap. XVII.]

ELIMINATION.

203

Position and General Description of the Urinary Organs.

The kidneys. — The kidneys are two compound tubular secret-
ing glands placed at the back of the abdominal cavity, one on
each side of the lumbar vertebrae. They are bean-shaped, with
the concave side turned towards the spine, and the convex side
directed outwards. Each kidney is about four inches (102 mm.)
long, two (51 mm.) broad, and one (25.4 mm.) thick, and ex-
tends from the eleventh rib
to nearly the crest of the
ilium, the right being a lit-
tle lower than the left in
consequence of the large
space occupied by the
liver. They are covered
by a tough envelope of
fibrous tissue called the
capsule of the kidney, and
are usually embedded in
a considerable quantity of
fat.

The ureters. — The ure-
ters are the excretory ducts
of the kidneys. They arise
in the middle of the con-
cave side, or hilus, of each
kidney, and proceed ob-
liquely downwards and in-
wards through the lumbar
region of the abdomen into
the pelvis, to open ob-
liquely by two constricted
orifices into the base of the
bladder. Each ureter is of the diameter of a goose quill, from
sixteen to eighteen inches (406 to 457 mm.) long, and consists
of muscular tissue lined by mucous membrane. The muscular
coat is arranged in two la3^ers, an outer circular and an inner
longitudinal. Outside the muscular coat is a layer of fibrous
connective tissue carrying the blood-vessels and nerves with
which the tube is supplied.

Fig. 122. — The Renal Organs viewed
FROM Behind. R, right kidney; A, aorta;
A?', right reual artery ; Vc, inferior vena cava ;
Vr, right renal vein; U, right ureter; Vu,
bladder; fJa, urethra.

204 ANATOMY FOR NURSES. [Chap. XVIL

The bladder. — The bladder is the reservoir of the urine. It
is situated in the pelvic cavity behind the pubes, and is held in
position by ligaments. During infancy it is conical in shape
and projects above the upper border of the pubes into the hypo-
gastric region. In the adult, when quite empty, it is placed
deeply in the pelvis ; when slightly distended, it has a round
form ; but when greatly distended, it is ovoid in shape and
rises to a considerable height in the abdominal cavity. (J-^ide
Plate VII.) When moderately distended, it measures about
five inches (127 mm.) in length, and three inches (76 mm.)
across, and the ordinary amount of urine which it contains is
about one pint (0.473 litre). The bladder consists of plain
muscular tissue lined by a strong mucous membrane, and is
covered partially by a serous coat derived from the peritoneum.
The muscular coat has three layers, the principal fibres of which
run longitudinally and circularly, the circular fibres being col-
lected into a layer of some thickness around the constricted
portion or neck, where the bladder becomes continuous with
the urethra. These circular fibres around the neck form a
sphincter muscle which is normally in a state of contraction,
only relaxing at intervals, when the accumulation of urine
within the bladder renders its expulsion necessary.

The base of the bladder is directed downwards and back-
wards, and in the female lies in contact with the front wall of the
vagina and the lower part of the neck of the uterus. The neck
of the bladder is directed obliquely downwards and forwards.

The urethra. — The urethra is a narrow, membranous canal,
about an inch and a half (38 mm.) in length in the female, and
extending from the neck of the bladder to the external orifice
or meatus urinarius. It is placed beneath the symphysis pubis,
and is embedded in the anterior wall of the vagina. Its direc-
tion is obliquely downwards and forwards, its course being
slightly curved, the concavity directed forwards and upwards.
It admits of considerable dilatation, its normal diameter, how-
ever, being about a quarter of an inch (6,3 mm.). It is lined
by a mucous coat, which is continuous, externally, with that of
the vulva, and, internally, with that of the bladder. The exter-
nal muscular coat is also continuous with that of the bladder,
but between the mucous and muscular coats is a layer of thin,
spongy tissue, containing a network of large veins.

Chap. XVII.J

ELIMINATION.

205

The structure of the kidney. — The kidney is a secreting gland,
constructed upon the general plan of a compound secreting
gland, but possessing special features peculiar to itself. If we
cut a kidney in two lengthwise, it is seen that the upper end of
the ureter expands into a basin-like cavity, into which the solid
portion of the kidney projects in conical-shaped masses. This
dilated cavity of the ureter is called the pelvis or basin of the
kidney, and this
pelvis is irregu-
larly subdivided
into smaller, cup-
like cavities, called
calices, which re-
ceive the pointed
projections of the
kidney substance.

The substance of
the kidney is read-
ily seen by the
naked eye to con-
sist of two distinct
parts : an outer,
darker, and more
solid portion, called
the cortex (bark),
and an inner, lighter
striated portion,
called the medulla
(marrow), which is
not a solid mass but
more or less dis-
tinctly divided into pyramidal-shaped sections. The pointed
projections or papillce of the pyramids are received by the irregu-
larly disposed cup-like cavities of the pelvis. The bulk of the
kidney substance, both in the cortex and medulla, is composed
of little tubes or tubules, closely packed together, having only
just so much connective tissue as is sufficient to carry a large
supply of blood-vessels and a certain number of lymphatics and
nerves. The different appearance of cortex and medulla is due
to the shape and arrangement of tubules and blood-vessels.

Fig. 123. — Section through the Kidney show-
ing THE Medullary and Cortical Portions, and
THE Beginning of the Ureter, ct, cortex; M, me-
dulla; py, papilla of pyramidal section projecting into
one of the calices of pelvis; E.A, renal artery; R.V,
renal vein ; U, ureter.

206

ANATOMY FOR NURSES. [Chap. XVIL

Examined under the microscope, it is seen that the urinifer-
ous tubules begin as little rounded dilatations, called capsules,
in the cortex of the kidney. These capsules are joined to the

tubules by a constricted
neck, and the tubules, after
running a very irregular
course, open into straight
collecting tubes, which
pour their contents
through their openings in
the pointed ends or papil-
Ige of the pyramids, into
the pelvis of the kidney.
<iVide Fig. 126.)

The tubules are com-
posed of basement mem-
brane, lined throughout by
epithelium cells. The cells
vary in the different parts
of a tubule, some being
more especially adapted
to secretory purposes than
others.

The blood-supply of the
kidney. — For its size, the
kidney is abundantly sup-
plied with blood. The
renal artery, coming di-
rectly from the aorta,
divides as it enters the
hilus of the kidney into
branches, which, slipping
around the pelvis, pass
inwards between the pyra-
mids. On reaching the
boundary line between the
cortex and the medulla, the branches divide laterally to form
more or less complete arches (the veins also divide in a similar
manner to form venous arches). From the arterial arches ves-
sels pass upwards through the cortex, giving off at intervals

Fig. 124. — Vascular Supply of Kidney,
(Cadiat.) a, part of arterial arch; b, arterial
branch passing upwards through the cortex ;
c, glomerulus; d, efferent vessel ; e, meshwork
of capillaries ; /, straight arterial vessels of
medulla ; ff, venous arch ; fi, straight veins of
medulla.

Chap. XVII.]

ELIMINATION.

207

flV^"'^^,

tiny arteries, each of which enters the dilated commencement
or capsule of a uriniferous tubule. These tiny arteries, enter-
ing the capsule, are spoken of as afferent vessels. They push
the thin walls of the capsule before them, break up into a knot
of capillary vessels, called a glomerulus, and finally issue from
the capsule as efferent vessels. These efferent vessels do not
immediately join to form veins, but break up into a close mesh-
work of capillaries around the tubules, before they unite to
form the larger vessels and pour their contents into the veins
forming the venous arches, between the cortex and medulla.
In this way the cortex of the kidney is supplied with blood.
The medulla also receives its blood-supply mainly from the
arterial arches. The blood passes down-
wards in straight vessels between the uri-
niferous tubules, to be returned by more
or less straight veins to the venous arches,
whence it is conveyed by large branches
into the renal vein, which leaves the kid-
ney at the hilus and pours its contents
into the inferior vena cava.

The renal artery in passing into the
kidney is accompanied by a network of
nerves, called the renal plexus. They
are chiefly vaso-motor nerves, and regu-
late the contraction and relaxation of the
renal blood-vessels.

' Secretion of urine. — Urine is secreted
from the blood in two ways. It is partly removed by a process
of transudation or filtration, and partly by the secretory action
of the cells lining the uriniferous tubules.

(1) Into the dilated extremity or capsule of each tubule a
small artery enters and pushing the wall of the capsule before
it breaks up into a bunch of looped capillaries. The blood in
the loop of capillaries or glomerulus is only separated from the
interior of the tubule by the thin walls of the capillaries and
the inverted wall of the capsule, which closely covers the
glomerulus. The artery entering the capsule is larger than
the issuing vessel, and, during its passage through the glo-
merulus, the blood is subjected to considerable pressure. As a
result of this, a transudation of the watery constituents of the

Fig. 125. — Plan of
THE Blood-vessels con-
nected WITH THE Tu-
bules.

208

AJSTATOMY FOR NURSES. [Chap. XVIL

blood, with some dissolved salts, takes place through the walls
of the blood-vessels and of the capsule into the tubule.

(2) After leaving the capsule, the efferent vessel communi-
cates with other similar vessels which together form a mesh-
work of capillaries closely surrounding the tubules, so that the

blood is again brought into close
communication with the interior
of the tubules. The tubules are
lined with secreting cells, and
these cells appear to have the
power of selecting from the blood
the more solid waste matters
(especially the urea) which fail
to filter through the flat cells
forming the wall of the capsule.
Thus the elimination of urine
is a double process, being par-
tially accomplished by transuda-
tion, and partially by the selective
action of the secreting cells lining
the tubules.

Excretion of urine. — The uri-
niferous tubules commence in a
dilated extremity, the capsule, and,
after a very devious course, ter-
minate in the collecting tubules
which open on the pointed projec-
tions or papillae of the pyramids.
The fluid they contain passes into
Fig. 126. — Diagram of the the pelvis of the kidney, whence it

Course of Two Ukixiferous Tu- • ^„ ..,• j „i +i,„ „4-„,„ -.^j.^

BULEs. M, Maipighiau capsule, or ^^ Carried along the ureters into

dilated extremity ; c, convoluted por- the bladder, partly by pressure and

tionoftube; //, loop, consisting of a •, n ^11,1

descending and ascending limb; D, gravity, and partly by the peri-
collecting tubui© staltic contractions of the muscular
walls of the ureters. In the bladder the urine collects, its re-
turn into the ureters being prevented by the oblique entrance
of these tubes into the walls of the bladder.

Micturition is normally caused by the accumulation of urine
within the bladder. The accumulation stimulates the muscular
walls to contract, the resistance of the sphincter at the neck of

Chap. XVII.] ELIMINATION. 209

the bladder is overcome, and the urine is ejected through the
urethra. Involuntary micturition may occur as a result of
spinal injury involving tlie nerve centres which send nerves
to the bladder. It may be due to a want of " tone " in the
muscular walls, or it may result from some abnormal irritation.

General characters of the urine. — Normal urine may be de-
scribecl as a transparent watery fluid, of a pale yellow colour,
acid reaction, specific gravity of 1020, and possessing an odour
which can only be described as " characteristic " or " urinous."
Each one of these characters is liable to some variation within
the limits of health as well as in disease.

The transparency of urine may be diminished in health by the
presence of mucus, derived from the genito-urinary tract, or by
the deposit of salts. In disease the urine may become clouded
by the presence of pus.

The colour of urine depends mainly upon the amount of water
it contains ; also upon a diminution or increase of colouring
matters. In the copious urine of hysteria the colour is very
light, while in the diminished flow in fevers it is very high.
Abnormal colouring matters are derived from food or medicine,
or result from some diseased condition.

The reaction of urine should always be tested from a collec-
tion of urine passed during twenty-four hours as it is aifected
by diet and exercise. To test the reaction of urine, litmus
paper is used. Acid urine turns blue litmus paper red; alka-
line urine turns red litmus paper blue. When the colour of
the paper remains unchanged the urine is said to be neutral.
The reaction of mixed urine is normally acid.

The specific gravity depends upon the amount of solid waste
matters present in the urine. In health, it may vary from 1015
to 1025. When the solids are dissolved in a large amount of
water, the specific gravity will naturally be lower than when,
from a deficiency of water, the urine is more concentrated. It
is notably heightened by the presence of sugar in the disease
called Diabetes Mellitus.

The composition of urine. — The chief constituents of normal
urine are water, urea, uric acid, colouring matters, and salts. Of
these constituents, urea is by far the most important, for it is
the chief solid waste product of the body. To eliminate urea is
the special work of the kidneys, and if for any reason they fail

210 ANATOMY FOR NURSES. [Chap. XVII.

to execute their work, the accumulation of urea in the system
leads to termination of life. Urea is the final product of all
proteid substances, and consequently a diet rich in proteids
will increase the amount of urea in the system. When the
kidneys are disabled, it is customary for physicians to lighten
their work as far as possible by regulating the diet.

Of the salts, chloride of sodium occurs in the largest quan-
tity ; it sometimes disappears temporarily from the urine wi:en,
in certain inflammatory diseases, it is needed by the biood.

The chief abnormal constituents that are liable to appear in
the urine are albumin, giving rise to a condition calleci albu-
minuria, and sugar, giving rise to glycosuria. The " ca>. ts,"
which are found in urine in the various forms of Bright's ilis-
ease, are shed from the tubules in the shape of cylindrical
moulds.

The quantity of urine passed in twenty-four hours. — The normal
quantity of urine passed in twenty-four hours is from forty to
fifty ounces (1.18 to 1.48 litres), or about three pints (1.42
litres). This will vary in health with the condition of the skin,
and the amount of fluid taken into the body. The excretion of
water by the kidneys is closely related to that excreted by the
skin. When the body is exposed to cold, the blood-vessels in the
skin are constricted, and the discharge of water in the form of
sweat is checked ; at the same time the blood-vessels of the kid-
neys are dilated, there is a full and rapid stream of blood through
the glomeruli, and an increased flow of urine results. On the
other hand, when the body is exposed to warmth, the cutaneous
vessels are widely dilated, and the skin perspires freely, while
the renal vessels being constricted, only a small and slow stream
of blood trickles through the glomeruli, and the urine which is
secreted is scanty. The effect on secretion, however, is more
marked by the amount of fluid absorbed through the alimentary
canal; an increased secretion of water always follows an ordi-
nary meal, and when large quantities of water are drunk the
amount of urine is correspondingly increased.

The supra-renal capsules. — Lying immediately above each kid-
ney are two small flattened bodies of a yellowish colour. They
are usually classified with the ductless glands, as they have no
excretory duct. Each organ is invested by a fibrous capsule
which sends fibres into the sflandular substance : these fibres

Chap. XVII.]

ELIMINATION.

211

form a framework for the soft, pulpy substance of the gland,
and within the spaces of the framework are groups of cells.

The supra-renal capsules are plentifully supplied with blood-
vessels, nerves, and lymphatics, and they contain some striking
colouring matters. In disease of these organs, the skin fre-
quently becomes "bronzed," from an increase of pigment or
colouring matter. Their special normal functions are unknown.

AMOUNT OF THE SEVERAL URINARY CONSTITUENTS
PASSED IN TWENTY-FOUR HOURS, EXPRESSED IN
GRAMMES AND GRAINS. (Martin.)

Urine in 24 hours.

1500 grammes.

23,250 grains.

in 1000 parts.

Water

1428.00

22,134.00

952.00

Solids

72.00

1,116.00

48.00

The soUds consist of —

33.00
0.50

511.50

7.75

22.00

Uric acid

0.33

Hippuric acid

0.40

6.20

0.27

Kreatinin

1.00

15.50

0.66

Pigments and fats

10.00

155.00

6.66

Sulphuric acid

2.00

31.00

1.33

Phosphoric acid

3.00

46.50

2.00

Chlorine

7.00

108.50

4.70

Ammonia

0.75

12.00

0.50

Potassium

2.50

38.75

1.70

Sodium

11.00

170.50

7.33

0.25

3.80

0.16

Magnesium

0.20

3.00

0.13

71.60

1110.00

47.77

CHAPTER XVIII.

ELIMINATION CONCLUDED: THE SKIN. NAILS AND HAIR.
BODILY HEAT: PRODUCTION OF HEAT; LOSS OF HEAT.
DISTRIBUTION OF HEAT; REGULATION OF HEAT.

Having described the mechanism by means of which the lungs
rid the body of carbon dioxide and water, and of how the kid-
neys relieve it of urea, salts, and water, it now remains for us to
explain how the skin plays its part in elimination by yielding
up water, and a certain amount of carbon dioxide and salts.

The skin. — The skin is not, like the kidneys, set apart to per-

"^■^;^?w.3;::ffip

Fig. 127. — Section of Epidermis. (Ranvier.) H, horny layer, consisting of
s, superficial horny scales; sw, swollen-out horny cells; s.l. clear layer; M, Malpig-
hian layer, consisting of s.fir. granular layer; p, many-sided or prickle cells: c,
columnar cells. Nerve fibrils may be traced passing up between the epithelium cells
of the Malpighian layer.

212

Chap. XVIII.] THE SKIK 213

form one special function. It is an important excretory organ,
but it is also an absorbing organ ; it is likewise the principal
seat of the sense of touch, and serves, too, as a protective cover-
ing for the deeper tissues lying beneath it.

The skin, like a mucous membrane, consists of two distinct
layers ; an epithelial covering, and a connective tissue basis.
The epithelium is a stratified epithelium and is called the epi-
dermis, or scarf-skin; the connective tissue layer is called the
derma, cutis vera (true skin), or corium. The epidermis is com-
posed of layers of cells, the deeper of which are soft and pro-
toplasmic, while the superficial layers are hard and horny.
Between the two layers is a fairly distinct line of granular-
looking cells, the granules in which have been thought to form
the horny matter in the superficial cells. In the coloured races
the single layer of elongated cells next the corium contains
pigment granules.

The growth of the epidermis takes place by the multiplication
of the cells in the deeper or Malpighian layer. As these cells
multiply by cell-division, they push upwards towards the surface
those previously formed. In their upward progress they
undergo a chemical transformation, and the soft protoplasmic
cells become converted into the flat, horny scales which are
constantly being rubbed off the surface of the skin.

The thickness of the epidermis varies in different parts of the
body, measuring in some places not more than 2X0^^ of an
inch (0.106 mm.), and in others as much as ^jt\\ of an inch
(1.06 ram.). It is thickest in the palms of the hands and on
the soles of the feet where the skin is most exposed to friction
and pressure, but it forms a protective covering over every
part of the true skin, upon which it is closely moulded.

No blood-vessels pass into the epidermis ; it, however, receives
fine nerve-fibrils between the cells of the Malpighian layer.

The cutis vera or true skin is a highly sensitive and vascular
layer of connective tissue. It is, like the mucous membranes,
attached to the parts beneath it by a layer of areolar tissue,
here named "subcutaneous," which layer, with very few excep-
tions, contains fat. The connection in some parts is loose and
movable, as on the front of the neck ; in others, close and firm,
as on the palmar surface of the hand and on the sole of the
foot.

214

ANATOMY FOR NURSES. [Chap. XVIII.

The cutis vera is often described as consisting of two layers,
a superficial or papillary layer, and a deeper or reticular layer.

The surface of the superficial or papillary layer is increased
by protrusions in the form of small conical elevations, called
papillpe, and whence this layer derives its name. Tliese papillae
contain for the most part looped blood-vessels, but they also con-
tain the terminations of medullated nerve-fibres in the shape of
little bodies, called tactile corpuscles.

The papillse seem chiefly to exist for the purpose of giving
the skin its sense of touch, being always well developed where

Fig. 128. — Section of Skin showing Two Papilla and Deeper Layers of
Epidermis. (Biesiadecki.) a, vascular papilla, with capillary loop passing from
subjacent vessel, c; b, nerve-papilla, containing tactile corpuscle, t; d, nerve passing
up to tactile body ; /,/, section of spirally winding nerve-tibres.

the sense of touch is exquisite. The papilla? containing tactile
bodies are specially large and numerous on the palm of the
hand and the tips of the fingers, and on the corresponding
parts of the foot, while on the face and back they are small and
irregularly scattered.

The reticular layer of the corium is a continuation of the
papillary layer, there being no real division between them, and
is made up of bundles of white fibrous and elastic tissue which
gradually blend below with the subcutaneous areolar tissue. It
contains networks of blood-vessels, lymphatics, and nerves.

Chap. XVIIL]

THE HAIRS.

215

The appendages of the skin are the nails, the hairs, the
sebaceous glands, and the sweat-glands. They are all devel-
oped as thickenings, or as down-growths, of the Malpighian
layer of the epidermis.

The nails. — The nails are composed of clear, horny cells of
the epidermis, joined together so as to form a solid, continuous
plate. Underneath each nail, the true skin is modified to form
what is called the bed or matrix of the nail. This bed is very
vascular, and is raised up into numerous papillae. At the
hinder part of the bed of the nail the skin forms a deep fold, in
which is lodged the root of the nail.

The growth of the nail is accomplished
by constant multiplication of the soft
cells in the Malpighian layer at the root.
These cells are transformed into dry hard
scales which unite into a solid plate, and
the nail, constantly receiving additions
from below, slides forward over its bed and
projects beyond the end of the finger.
When a nail is thrown off by suppuration,
or torn off by violence, a new one will grow
in its place provided any of the cells of
the Malpighian layer are left.

The average rate of growth of the nails
Fig. 129. — Piece of ig about qV of an inch (0.79 mm.) per week.

Human Hair. (Highly mi i •" rr.ii-

maguitied.) «, cuticle; The hairs.— Ihe hairs are growths of
b, fibrous substauce; c, the epidermis, developed in little pits, the

medulla. ^ • c ■^^■ ^ i-i 11 !•

hair-ioliicles, which extend downwards into
the deeper part of the true skin, or even into the subcu-
taneous tissue. The hair grows from the bottom of the little
pit or follicle, the part which lies within the follicle being
known as the root. The substance of the hair is composed
of coalesced horny cells, arranged in different layers, and we
usually distinguish three parts in the stem or shaft of hairs.
An outer layer of delicate, scale-like cells, the cuticle ; a middle,
horny, thick, and coloured portion, formed of elongated cells,
the fibrous substance ; and a central pith formed of angular cells,
the medulla.

The root of the hair is enlarged at the bottom of the follicle
into a bulb or knob, and this bulb is composed of soft-growing

216 ANATOMY FOR NURSES. [Chap. XVIII.

cells fitting over a vascular papilla which projects into the
bottom of the follicle. The hair grows from the bottom of
the follicle by multiplication of the soft cells which cover the
papilla, these cells becoming elongated to form the fibres of the
fibrous portion, and otherwise modified to form the medulla and
cuticle. New hairs are produced indefinitely, so long as the
papillie and soft cells remain intact.

The follicles containing the hairs are narrow pits formed by
the involutions of the true skin and the epidermis. They slant

obliquely upwards, so that the
hairs they contain lie down on
the surface of the body. Con-
nected with each follicle are
small muscles of plain muscular
tissue which pass from the sur-
face of the true skin, on the side
to which the hair slopes, obliquely

Fig. 130. — Section of the Skin downwards, tO be attached tO

SHOWING THE HAIRS AND SEBACEOUS ^hc bottOm Of thc folHcle. WhcU

Glands, o, the epidermis; o, corium;

c, muscles, attached to hair-follicles aud these muscles COlltract, aS they

to uuder surface of epidermis. ^^-^^ ^^^^^1^^, ^j^^ influence of cold

or terror, the little hairs are pulled up straight, and stand " on
end " ; the follicle also is dragged upwards so as to cause a
prominence on the surface of the skin, whilst the cutis vera,
from which the little muscle arises, is correspondingly depressed:
in this way the roughened condition of the skin known as
" goose-skin " is produced. Hairs grow on an average at the
rate of half an inch (12.7 mm.) per month. They are found all
over the body, except on the palms of the hands and the soles of
the feet, and on the last joints of the fingers and toes.

The sebaceous glands. — The sebaceous glands are small saccu-
lar glands, the ducts of which open into the hair-follicles. They
are lined with epithelium, and secrete a fatty, oily substance
(sebum) which they discharge into the hair-follicles. Several
sebaceous glands may open into the same follicle, and their size
is not regulated by the length of the hair. Thus, some of the
largest are found on the nostrils and other parts of the face,
where they often become enlarged with pent-up secretion. The
sebum lubricates the hairs and renders them glossy ; it also
exudes, more or less, over the whole surface of the skin, and

Chap. XVIII.] ELIMINATION CONCLUDED.

217

keeps it soft and flexible. An accumulation of this sebaceous
matter upon the skin of the foetus furnishes the thick, cheesy,
oily substance, called the vernix caseosa.

The sudoriferous or sweat-glands. — All over the surface of the
skin are minute openings or pores. These pores are the open-
ings through which the sweat-glands pour their secretions upon
the surface of the body. The sweat-glands are tubular glands
with their blind ends coiled into little balls which are lodged
in the true skin or subcutaneous tissue ; from the ball the tube
is continued as the excretory duct of the gland up through
the true skin and epidermis, and finally 0]3ens on the surface
by a slightly widened orifice. Each tube is lined by a secreting

epithelium continuous
with the epidermis. The
coiled end is closely in-
vested by a meshwork of
capillaries, and the blood
in the capillaries is only
separated from the cav-
ity of the glandular tube
by the thin membranes
which form their respec-
tive walls. The secre-
tory apparatus in the
skin is somewhat simi-
lar to that which obtains
in the kidney ; in the
one case the blood-
vessels are coiled up within the tube, while in the other the
tube is coiled up within the meshwork of blood-vessels.

The sweat-oflands are abundant over the whole skin, but
they are most numerous on the palm of the hand and on the sole
of the foot; in the groin, and especially in the axilla, they are
larger than in other parts of the body. At a rough estimate,
the whole skin probably possesses from two to two and a half
millions of these glands, and their combined secreting power is
therefore very great.

Perspiration or sweat. — The sweat is a transparent colourless
fluid, of a distinctly salt taste and with a strong, distinctive odour.
When the secretion is scanty it has an acid reaction, but when

Fig. 131. — Coiled End of a Sweat-Gland
a, the coiled end; h, the duct; c, network of capil
laries, inside which the sweat-inland lies.

218 ANATOMY FOR NURSES. [Chap. XVIII.

abundant it is alkaline. The chief normal constituents of sweat
are water, salts, fatty acids, and, some authorities state, a slight
amount of urea. In various forms of kidney disease urea may
be present in considerable quantity, the skin supplementing to
a certain extent the deficient work of the renal organs.

Quantity of perspiration. — Under ordinary circumstances, the
perspiration that we are continually throwing off evaporates
from the surface of the body without our becoming sensible of
it. This insensible perspiration, as it is called, usually amounts
to about a pint (0.473 litre) in the course of twenty-four hours.
The amount, however, varies to a very great extent — with the
condition of the atmosphere ; the amount of exercise taken ;
the quantity of fluid drunk ; the action of the kidneys. Varia-
tions also occur under the influence of mental emotions, the
action of drugs, or are induced by certain diseased conditions.
When more sweat is poured upon the surface of the body than
can be removed at once by evaporation, it appears on the skin
in the form of scattered drops, and we then speak of it as sen-
sible perspiration.

Less important functions of the skin. — Besides being an impor-
tant excretory organ, the skin is to a slight extent an absorbing
organ. In the sound, healthy skin, it is doubtful whether
matters in solution can be absorbed through the epidermic
covering, but if the horny layers of the epidermis be removed
by blistering, or in any other manner, substances in solution
readily pass into the blood-vessels in the true skin. Oily sub-
stances, especially when well rubbed in, are absorbed without
removal of the epidermis.

Oxygen in small amount is also taken in through the skin,
but this gain to the body is balanced by the carbon dioxide
which is thrown off.

To sum up : the skin excretes a large amount of water and a
small amount of carbon dioxide and salts ; it absorbs a small
amount of oxygen and, under certain conditions, oily substances
and watery solutions ; it is a protective organ and a tactile organ ;
it su[)ports two appendages, viz. the hair and nails, and keeps
itself flexible, and the hair glossy, by the secretion of sebum.

There is still another function of the skin to be considered
before closing this chapter, and that is the part it plays in regu-
lating the temperature of the body.

Chap. XVIII.] BODILY HEAT. 219

Bodily heat. — In order that the bodily functions may be prop-
erly performed, it is necessary for the body to maintain a certain
temperature. Just as plants are killed by the frost, or withered
by the heat of the sun, so our tissues die if the bodily tempera-
ture falls below, or rises above, a certain limit. Our bodies,
however, differ from plants in that they generate and regu-
late their own temperature, and possess the power of adapting
themselves to extremes of external heat and cold, without
necessarily suffering any vital injury. But, although the ex-
ternal tempei'ature of the atmosphere may vary considerably
without hurting us, the bodily temperature must be kept at
an average standard of 98.6° F. (37° C.) if we are to remain in
a state of health. Slight variations are compatible with health,
the temperature being normally a trifle higher after eating or in
the evening of the day, but any variation over a degree above or
below 98.6° F. is indicative of danger.

Production of heat. — Heat in the body is produced by the
chemical changes that are constantly going on in the tissues.
Wherever metabolic changes are taking place, there heat is set free.
These changes take place more rapidly in some tissues than in
others, and in the same tissues at different times. The muscles
always manifest a far higher rate of activity than the connec-
tive tissues, and consequently the former evolve a larger pro-
portion of the bodily heat than the latter. We might liken the
different tissues of the body to so many fireplaces stored with
fuel, the fuel in some of the fireplaces being more easily ignited
and burning more rapidly than in others. The muscles and the
secreting glands, especially the liver, are supposed to be the
main sources of heat, as they are the seats of a very active
metabolism.

Loss of heat. — The heat thus continually produced is as con-
tinually leaving the body by the skin and the lungs, and by the
urine and feces. It has been calculated that in every 100 parts
about : —

88 per cent is lost by conduction and radiation from the surface of
the skin and the evaporation of the perspiration.
9 per cent is lost by warming the expired air and the evapora.tion

of the Avater of respiration.
3 per cent is lost by warming the urine and feces.

220 ANATOMY FOR NURSES. [Chap. XVIII

Distribution of heat. — The blood, as we know, permeates all
the tissues in a system of tubes or blood-vessels. Wherever
oxidation takes place and heat is generated, the temperature of
the blood circulating in these tissues is raised. Wherever, on
the other hand, the blood-vessels are exposed to evaporation,
as in the moist membranes in the lungs, or the more or less
moist skin, the temperature of the blood is lowered. The gain
and loss of heat balance one another with great nicety, and
the blood, circulating rapidly, now through warmer, and again
through cooler tubes, is kept at a uniform temperature of about
100° F. (37.8° C). In this way the whole body is warmed in
somewhat the same way as we warm a house, the warm blood
in the blood-vessels heating the tissues, as the hot water in the
hot- water pipes heats the rooms in steam-heated dwellings.

Regulation of heat. — We have seen that active changes in
the body produce heat. The action of the muscles is a source
of heat, the activity of the glands during digestion, the active
changes taking place in the tissues during inflammation or
suppuration, or the changes caused by some specific micro-
organism, and we may say that there are normal and abnormal
sources of heat.

Normally, production of heat is balanced by loss of heat, and
the chief regulator of this gain and loss is undoubtedly the
skin. This is well seen in the case of muscular exercise.
Every muscular contraction gives rise to heat, and yet during
severe muscular exercise the temperature of the body does not
rise, or rises only to a trifling extent. This is accounted for
by the fact that when the muscular exertion causes the blood
to circulate more quickly than usual, the blood-vessels in the
skin dilate, the sweat-glands at the same time are excited to
pour out a more abundant secretion, and the heated blood pass-
ing in larger quantities through the cutaneous vessels (which
are kept well cooled by the evaporation of the perspiration)
the general average temperature of the body is maintained.

In pyrexia, or fever, rise of temperature is due to some cause
which, while increasing the metabolism of the tissues, at the
same time interferes with the process by means of which the
body rids itself of superfluous heat. We all know how hot and
dry the skin is liable to become in fevers ; how we try to restore
its function and lower the temperature by baths, sponging, and

Chap. XVIII.] BODILY HEAT. 221

packs ; liow we recognize tlie first signs of restored function —
the moist, warm sweat in tlie palm of the hand — as a pretty
sure sign tliat the fever is " broken." If a very higli tempera-
ture persists for any length of time, the metabolism of the tis-
sues goes on at such a rapid rate that the capital of the body
is soon exhausted. Every organ works with feverish activity,
the heart and lungs increase their action, the pulse and respira-
tion become more and more hurried, and consequently more and
more feeble, until finally, unless relief is obtained, the patient
dies of exhaustion.

In exposure to variations of external temperature the skin is
also the chief agent in regulating the heat of the body. Expos-
ure to cold stimulates the nerve fibres which bring about reflexly
a constriction of the blood-vessels. As a result, less blood is sent
to the surface to be cooled, and the average blood-temperature
is maintained. On the other hand, exposure to warmth causes
reflexly a dilatation of the cutaneous blood-vessels, and more
blood is sent to the surface to be cooled. Briefly, when the
external temperature is high, the cutaneous blood-vessels dilate,
and the sweat is also usually poured out upon the surface of
the skin ; when the external temperature is low, the cutaneous
blood-vessels contract, and the skin usually remains dry.

By clothing we can aid the functions of the skin and the
maintenance of heat ; though, of course, clothes are not in them-
selves sources of heat. The object of clothing is, in winter, to
prevent conduction and radiation of heat from the skin, and, in
summer, to promote it. Of the materials used for clothes, linen
is a good conductor ; calico or muslin not quite so good, while
wool, silk, and fur are all bad conductors.

Subnormal temperature. — In some maladies the temperature
falls distinctly below the normal. This is no doubt chiefly due
to diminished metabolism. In cases of starvation, the fall of
temperature is very marked, especially during the last days of
life. The diminished activity of the tissues first affects the cen-
tral nervous system ; the patient becomes languid and drowsy,
and finally unconscious ; the heart beats more and more feebly,
the breath comes more and more slowly, and the sleep of uncon-
sciousness passes insensibly into the sleep of death.

CHAPTER XIX.

THE SPECIAL SENSES: PRESSURE, TEMPERATURE, PAIN, MUSCLE-
SENSE, TASTE, HEARING, EQUILIBRIUM, VISION.

In the chapter on the Nervous System it was stated that the
result of the stimulation of a neurone depends not upon any
peculiarity of the neurone itself, but upon its anatomical rela-
tions to other neurones. For exam23le, the neurones of which
the optic nerve is composed are not essentially different from
those which compose the trigeminal nerve, or from those which
compose the facial nerve ; but, as we will proceed to show, the
results and the methods of their stimulation differ according to
their anatomical relationships : —

1. The dendrones of the optic nerve terminate in the retinal
epitlielium. This retinal epithelium is of such a nature that it
responds only to the stimulation of light falling into the eye.
The impulses thus aroused pass along the optic axones to the
central nervous system, where they connect with the dendrones
of other neurones situated in the cord, or in the brain, and
cause on the one hand reflexes, and on the other voluntary
movements accompanied by the phenomenon of consciousness.

2. The dendrones of the trigeminal nerve, which supjily the
skin of the face, terminate in various ways, so that some are
stimulated only by heat, some by cold, some by pressure, and
the impulses thus aroused pass to the central nervous sj^stem
along axones which have connections similar to those of the
optic nerve.

3. The dendrones of the facial nerve lie within the central
nervous system, and they are normally stimulated by impulses
which pass to them from other neurones in the brain or spinal
cord. These impulses they transmit along their axones which
terminate in the muscles of the face, and which are thus, volun-

222

Afferent

OR

Sensory.

Chap. XIX.] ORGANS OF SPECIAL SENSE. 223

tarily or reflexly, caused to contract. All peripheral nerve
fibres may thus be classified by the way in which they termi-
nate, or, what is the same thing, by their physiological function.
The following is such a classification : —

_ \ Voluntary (endintr in the voluntary musclesV

Efferent k i / / ^ • ^ j j-i ^ j-

I Involuntary (e.g. vaso-constrictor and vaso-dilator ; cardio-

, , j accelerator and cardio-inhibitory, etc.).

[^ Secretory (ending in gland cells).

r Reflex sensory (unaccompanied by the phenomena of conscious-
ness).
Special sensory (accompanied by conscious sensation), viz. : —
Pressure. Pain. Hearing.

Heat. Muscle-sense. Equilibrium.

Cold. Taste. Vision.

In the preceding chapters ^ attention has been called to
different varieties of efferent nerves, and to the fact that any
of these nerves might be stimulated reflexly through appropriate
afferent {i.e. reflex sensory) nerves. We have now to consider
those afferent fibres, the special sensory, which are concerned
with the special senses, and in connection therewith to study
the structures in which these nerves terminate, and which are
called the organs of special sense.

Touch or pressure. — The special organs of the sense of touch
(Fig. 128) are distributed over the entire surface of the body,
being more or less numerous in all parts of the true skin.
Stimulation of these organs produces a sensation of touch, and
we distinguish not only differences in the intensity of the stimu-
lus, but also the locality in which the stimulus is applied. The
sensations produced by the stimulation of the touch endings in
different parts of the body resemble each other, but are not iden-
tical. We have learned by experience to associate these differ-
ences (which are called the "local signs ") with the locality in
which the end organ stimulated is situated. Thus if the hand be
stimulated we have three perceptions in consciousness : first,
that we have been touched; secondly, we are conscious of the
degree of pressure, i.e. of the intensity of the stimulus; and
thirdly, we are aware of tlie fact that it is the hand which has
been touched.

1 Nerves to Voluntary Muscles, page 72 ; Vaso-constrictor Nerves, page 137 ;
Vaso-dilator Nerves, page 137 ; Cardio-accelerator, page 110 ; Cardio-inhibitory
Nerves, page 110 ; Secretory Nerves, page 166.

224 ANATOMY YOU NURSES. [Chap. XIX

The power of discriminating between different pressures,
and also the power to localize impressions, varies in different
regions of the body.

A careful study of the skin shows that the organs of touch
are separated from each other by an appreciable distance, so
that we may speak of " pressure points or areas " which are sepa-
rated from one another by points or areas which are insensitive
to pressure.

Temperature. — In addition to the end organs of the sense of
touch, there are also structures in the skin which are only
stimulated by changes in temperature. These structures are
of two kinds: stimulation of one causing the feeling of cold;
stimulation of the other, the feeling of heat. The distribution
of the end organs of the sense of heat and cold is punctiform
like the pressure sense, and we may therefore speak also of
"heat and cold" points, each of these points having its own
local sign.

Pain. — The nerve endings of the sense of pain are very
widely distributed throughout almost the whole body.

Muscular sense. — The end organs of the muscular sense are
situated in the tendons and between the fibres of the muscles.
They convey to us the sense of the tension and pressure under
which our muscles are placed, and from this we infer the position
of the various parts of the body. Thus their function is to aid
in coordinating muscular action, in preserving equilibrium, and
in estimating weight or resistance.

Common sensation. — Under this heading may be grouped a
number of sensations often of a very indefinite character. They
are the various obscure sensations proceeding from the viscera,
which may give us the feeling of well-being or of the reverse.
The sensations of hunger, of thirst, and possibly of fatigue
belong to this class.

The sense of taste. — The special organ of the sense of taste is
the tongue, which is a movable muscular organ covered with
mucous membrane. This mucous membrane closely resembles
the skin in structure, except that the papillce it contains are
more highly developed. The papilhe project as minute
prominences and give the tongue its characteristic rough
appearance.

Some of the papilla) are simple and resemble those found in

Chap. XIX.] ORGANS OF SPECIAL SENSE.

225

the skin; the remainder are compound,^ and are only found on
the surface of the tongue. Of these compound papillse there
are three varieties. The hirgest, the circumvallate papilloe, are
about eight or ten in number, and form a V-shaped row near the
root of the tongue, with its open angle turned toward the lips.

Fig. 132. — The Upper Surface of the Tongue. 1, 2, circumvallate papillae;
3, fungiform papillae ; i, filiform papillae ; 6, mucous glands.

The next in size are the fungiform papilloe^^ found principally on
the tip and sides of the tongue. The smallest and most numer-
ous are the filiform papillce, found all over the tongue, excepting

1 A compound papilla i.s one large one bearing several smaller ones on its surface.

2 The fungiform papillae resemble fungi, having an expanded upper portion
resting on a short, thick pedicle. The circumvallate papillae resemble the fungi-
form, except that they are surrounded by a wall of smaller papillae.
Q

226 ANATOMY FOR NUESES. [Chap. XIX.

the root, and bearing on their free surface a form of ciliated
epithelium. In some animals the hair-like processes on the fili-
form papillcB are horny in structure, and their tongues are cor-
respondingly roughened, so that they supplement the teeth in
the bruising and crushing of food. In man these hair-like pro-
cesses are exceedingly delicate, and seem to be specially con-
nected with the sense of touch, which on the tip of the tongue
is highly developed, and which serves to guide the tongue in its
variable and complicated movements.

In the circumvallate, some of the fungiform papillse, and
scattered also over the mucous membrane of the tongue and
soft palate, are little clusters of cells lying in cavities of the
epithelium, called taste-buds. The bases of these cell-clusters,
or taste-buds, are supplied with nerve-fibres. The nerve-fibres
are derived from the glosso-pharyngeal and from the lingual or
gustatory, a branch of the trigeminal. The former supplies
the back of the tongue, and section of it destroys taste in that
region ; the latter is distributed to the front of the tongue, and
section of it, similarly, deprives the tip of the tongue of taste.^

We often confound taste with smell. Substances which have
a strong odour, such as onions, are smelled as we hold them in
our mouths; and if our sense of smell is temporarily suspended,
as it sometimes is by a bad cold in the head, we may eat garlic
and onions and not taste them. Hence the philosophy of hold-
insf the nose when we wish to swallow a nauseous dose.

The sense of smell. — The nose is the special organ of the
sense of smell. It consists of two parts, — the external fea-
ture, the nose, and the internal cavities, the nasal fosste. The
external nose is composed of a triangular framework of bone
and cartilage, covered by skin and lined by mucous membrane.
On its under surface are two oval-shaped openings — the nos-
trils — separated by a partition. The margins of the nostrils
are provided with a number of stiff hairs which arrest the pas-
sage of dust and other foreign substances carried in with the
inspired air.

The nasal fossae are two irregularly wedge-shaped cavities,
separated from one another by a partition or septum, and com-
municating with the air in front by the anterior nares or nostrils,

1 The exact location of the cell-bodies, of which these nerve-fibres are the
dendrones, is uncertain, as is also the way in which their axones enter the brain.

Chap. XIX.] ORGANS OF SPECIAL SENSE.

227

while behind they open into the back of the pharynx by the
two posterior nares. Fourteen bones enter into the formation
of the nasal cavities : the floor
is formed by the palate and
part of the superior maxillary
bones ; the roof is chiefly
formed b}^ the perforated (crib-
riform) plate of the ethmoid
bone, and by the two small
nasal bones ; and in the outer
walls we find, in addition to
processes from other bones,
the three scroll-like turbinated
bones. The turbinated bones,
which are exceedingly light

and spongy, project into the

, .^. 1 T • 1 xi Fig. 133. — Vertical Longitudinal

nasal cavities, and divide them section of Nasal Cavity. 1, olfactory

into three incomplete passages nerve; w, branch of fifth nerve; h, hard

from before backwards, — the

superior, middle, and inferior meatus. The palate and superior
maxillary bones separate the nasal and mouth cavities, and the
cribriform plate of the ethmoid forms the partition between the
cranial and nasal cavities.

The mucous membrane (sometimes called the Schneiderian ^
membrane), which closely covers the nasal passages, is thickest
and most vascular over the turbinated bones. In some nasal
troubles it becomes much thickened and swollen, and occludes
the nasal passages to such an extent as to compel us to breathe
through the mouth. It contains numerous mucous glands which
secrete mucus for the purpose of keeping the membrane moist,
— a condition which is essential to perfection of the sense of
smell.

The sense of smell is confined to the upper air passages of the
nose. Here the mucous membrane is remarkable in that it
contains nerve-cells. These cells have short, thick dendrones
which terminate in a bunch of short, hair-like projections pro-
truding beyond the surface of the mucous membrane, so that

1 From Schneider, the first anatomist who showed that the secretions of the
nose proceeded from the mucous membrane, and not, as was formerly supposed,
from the brain.

228 ANATOMY FOR NURSES. [Chap. XIX.

the neurones are stimulated directly, and not through the inter-
vention of modified epithelial cells. The axones of these cells
unite to form numerous bundles of fibres which pass upward
through the cribriform plate of the ethmoid bone and terminate
in the olfactory bulb of the brain.

Odorous particles in the air, passing through the lower, wider
air passages, pass by diffusion into the higher, narrower nasal
chambers, and falling on the mucous membrane provided with
olfactory nerve-endings, produce sensory impulses which, ascend-
ing to the brain, give rise to the sensation of smell.

If we wish to smell anything particularly well, we sniff the
air up into the higher nasal chambers, and thus bring the odor-
ous particles more closely into contact with the olfactory nerves.

Each substance we smell causes its own particular sensation,
and we are not only able to recognize a multitude of distinct
odours, but also to distinguish individual odours in a mixed
smell. The sensation takes some time to develop after the con-
tact of the odorous stimulus, and may last a long time. When
the stimulus is repeated, the sensation very soon dies out, the
sensory terminal organs quickly becoming exhausted. Mental
associations cluster more strongly round sensations of smell
than round any other impressions we receive from without. A
whiff of fresh-mown grass ! What associations will it not con-
jure up for those happy mortals who spent their childish days
in country lanes and fields.

The ear. — The ear is the special organ of the sense of hear-
ing, and is made up of three portions, — the external ear, the
middle ear or tympanum, and the internal ear or labyrinth.

The external ear consists of an expanded portion, named pinna
or auricle, and the auditory canal or meatus.

The auricle is composed of a thin plate of yellow fibro-car-
tilage, covered with skin, and joined to the surrounding parts
by ligaments and a few muscular fibres. It is very irregular
in shape, and appears to be an unnecessary appendage to the
organ of hearing, except that the central depression, the concha,
serves to some extent to collect sound-waves, and to conduct
them into the auditory canal.

The auditory canal is a tubular passage, about an inch and a
quarter (32 mm.) in length, leading from the concha to the
drum-membrane. It is slightly curved upon itself, so as to

Chap. XIX.] ORGANS OF SPECIAL SEi^SE.

229

be higher in the middle than at either end. It is lined by a
prolongation of the skin, which in the outer half of the canal is
very thick and not at all sensitive, and in the inner half is thin
and highly sensitive. Near the orifice the skin is furnished
with a few hairs, and further inwards, with modified sweat-
glands, the ceruminous glands, which secrete a yellow, pasty
substance, resembling wax.

The middle ear or tympanum is a small, irregularly flattened
cavity, situated in the petrous portion of the temporal bone,
and lined with mucous membrane. It is separated from the

Fig. 134. — Semi-diagrammatic Section through the Right Ear. M, concha;

G, the external auditory canal ; T, tympanic, or drum-membrane ; P, tympanum,
or middle ear; o, oval window; r, round window. Extending from T to o is seen.
the chain of the tympanic bones ; i?, Eustachian tube ; T, i?, <S, bony labyrinth; V,
vestibule; 2?, semicircular canal; iS, cochlea; 6, Z, i', membranous labyrinth in semi-
circular canal and in vestibule. A, auditory nerve dividing into branches for vesti-
bule, semicircular canal, and cochlea.

external auditory canal by the drum membrane (pnemhrana
tympani), and from the internal ear by a bony wall in which
there are two small openings covered with membrane, — the
oval window or fenestra ovalis, and the round window ov fenes-
tra rotunda. The cavity of the middle ear is so small that
probably five or six drops of water would completely fill it.
It communicates below with the pharynx b}^ the small passage
called the Eustachian tube, through which air enters the cavity
and serves to keep the atmospheric pressure equal on each
side of the drum-membrane. The middle ear also communi-

230 ANATOMY FOR NURSES. [Chap. XIX.

cates above with a number of bony cavities in the mastoid por-
tion of the temporal bone.^ The cavities, called mastoid cells,
are lined with mucous membrane, which is continuous with that
covering the cavity of the tympanum.

Stretching across the tympanic cavity is a chain of tiny mov-
able bones, three in number, and named from their shape the
malleus or hammer, the incus or anvil, and the stapes or stirrup.
The hammer is firmly attached to the drum-membrane, and the
stirrup is fastened into the oval window (also covered by mem-
brane) leading into the inner ear. The anvil is placed between
the hammer and stirrup, and attached to both by delicate
articulations. These little bones are set in motion with every
movement of the drum-membrane. Vibrations of the mem-
brane are communicated to the hammer, taken up by the anvil
and transmitted to the stirrup, which is driven slightly forward,
and sets in motion the membrane covering the oval opening
leading into the internal ear.

The internal ear or labyrinth receives the ultimate termina-
tions of the auditory nerve, and is, therefore, the essential part
of the organ of hearing. It consists of (1) a bony labyrinth,
which is composed of a series of peculiarly shaped cavities, hol-
lowed out of the petrous portion of the temporal bone, and
named from their shape the vestibule, the semicircular canals,
and cochlea (snail-shell). This bony labyrinth is lined by a
serous membrane, which secretes a watery fluid called the peri-
lymph ; and lying within tlie l)ony labyrinth and peri-lymph is
(2) a membranous labyrinth, which is composed of a series of
sacs or tubes, fitting more or less closely within the vestibule,
semicircular canals and cochlea, the two former being concerned
with the sense of equilibrium, the last with the sense of hear-
ing. The membranous labyrinth is filled with a watery fluid
called endo-lympli. In its walls terminate the dendrones of the
auditory nerve. Before its termination, the auditory nerve
divides into two branches, the cochlear supplying the cochlea,
the vestibular supplying the vestibule and semicircular canals.
The cells of origin of these two branches constitute two ganglia
situated in the region of the labyrinth. Their dendrones are
distributed to the epithelial lining of the membranous sac, while

1 The mastoid portion of the temporal bone is that rounded mass of bone
■which one readily distinguishes behind the auricle.

Chap. XIX.] ORGANS OF SPECIAL SENSE. 231

the axones form the trunk of the auditory nerve and pass back
to the meduUa oblongata.

The sense of hearing. — The cochlea consists essentially of a
spirally wound canal containing a long series of fibres stretched
across it like strings. These fibres increase in length from the
base of the cochlea upward, and in their action resemble the
wires in a piano, for vibrations of the endo-lymph of a certain
rate set up vibrations in the fibres of a certain length.

All bodies which produce sound are in a state of vibration
and communicate their vibrations to the air with which they
are in contact, and thus the air is thrown into waves, just as a
stick waved backwards and forwards in water throws the water
into waves.

When air-waves, set in motion by sonorous bodies, enter the
external auditory canal, they set the drum-membrane vibrating,
stretched membranes taking up vibrations from the air with
great readiness. These vibrations are communicated to the
chain of tiny bones stretching across the middle ear, and their
oscillations cause the membrane leading into the internal ear to
be alternately pushed in and drawn out, and vibrations are in
this w^ay transmitted to the peri-lymph. Each vibration com-
municated to the peri-lymph travels as a wave over the ves-
tibule, semicircular canals, and cochlea, and is transmitted
through the membranous walls to the endo-lymph. The vibra-
tions of the endo-lymph stimulate the cochlear nerve endings,
and nervous impulses are conveyed by the auditory nerve to
those parts of the brain, stimulation of which gives rise to the
sensation of sound.

The effect produced by a sonorous vibration continues for a
short time after the cessation of its cause. Usually the interval
between two different impulses is sufficient to allow the first
impression to disappear before the second is received, and the
ear distinguishes them in succession. But if they follow each
other at equal intervals, with a certain rapidity, they produce
the impression of a continuous sound ; and this sound has a
higher or lower pitch according to the rapidity of its vibra-
tions. It has been discovered that sound-waves following each
other with a rapidit}^ of less than sixteen times per second, are
separately distinguishable ; but above that frequency they are
mergfed into a continuous sensation. When the sound-waves

232 ANATOMY FOR NURSES. [Chap. XIX.

recur at irregular intervals, the only characters perceptible in
the sound are its intensity and quality. But if they succeed
each other at regular intervals, the sound produced has a
position in the musical scale as a high or low note. The more
frequent the repetitions, the higher the note ; but a limit is at
last reached, at which the ear fails to perceive the sound, and
an excessively high note is therefore inaudible. Sonorous
vibrations, perceptible to man as musical notes, range between
sixteen per second for the lowest notes, and 38,000 for the
highest. (Dalton.)

The sense of equilibrium. — Among the various means (such as
sight, touch, muscular sense), whereby we are enabled to main-
tain our equilibrium, coordinate our movements, and become
aware of our position in space, one of the most important is the
action of the vestibule and semicircular canals. The vestibule
consists practically of a sac, from the walls of which project
sensory hairs, in relation at their bases with the dendrones of
the vestibular nerve. Among these hairs rest several small
calcareous bodies called otoliths. Each semicircular canal con-
sists of a curved tube enlarged at one end (ampulla). In this

ampulla are hairs around which the
dendrones of the vestibular nerve
terminate.

The hairs in the ampullce are stimu-
lated by the flowing of the endo-
lymph, and the canals are so arranged
(Fig. 135) that any movement of the

Fig. 135. — Diagram show- head causes an increase in the pressure

ING Relative Position OF THE n ■, -, , .

Planes in which the Semi- of the eudo-lymph in One ampulla,

CIRCULAR Canals lie. rl, ^^^^ ^ corresponding diminution in

anterior vertical canal; P.V., the ampulla of the parallel canal on

posterior vertical canal; //., ,i -j. • i rni it

horizontal canal; a, ampulla of ^^^^ opposite Side. Thus a nodduig

Rt. anterior vertical canal; a', of the head to the right WOUld cause a

ampulla of Lt. posterior verti- „ pit ir jt-.i

cai canal. now 01 cudo-lymph irom a to 6 m the

right anterior vertical canal, but from
h' to a' in the left posterior vertical canal. Hence the pressure
upon the hairs is decreased in a, but increased in «'. Such
stimulations of the sensory hairs are transmitted by the den-
drones of the vestibular nerve, through the cell-bodies of the
vestibular ganglion and the axones of the auditory nerve, to

Chap. XIX.] ORGANS OF SPECIAL SENSE. 233

the brain, and it is the function of the semicircular canals
to give us a knowledge of the position of the head when at
rest. The intensity and direction of the pressure of the oto-
liths upon the sensory hairs of the vestibule are also thought
to give us a like knowledge ; namely, the position of the head
when at rest.

The sense of sight. — The eye is the special organ of the sense
of sight, and consists of the eyeball, or eye proper, and of acces-
sory protective appendages, such as the eyebrows, eyelids, lach-
rymal glands, etc.

The eyeball is contained in a bony cavity, the orbit, which is
padded with fat and lined with a membranous capsule, — the
capsule of Tenon. This capsule is a serous sac, one layer of
which is attached to the posterior portion of the eyeball, while
the other lines the orbital cavity : in this way the eyeball is
isolated from surrounding structures, and free movement with-
out friction is insured. The orbit is shaped like a four-sided
pyramid ; the apex, directed backwards and inwards, is pierced
by a large opening — the optic foramen — through which pass
the nerves and blood-vessels distributed to the eyeball. The
base of the orbit, directed outwards and forwards, forms a strong
bony edge for protecting the eyeball from injury.

The eyeball is spherical in shape, but its transverse diameter
is less than the antero-posterior, so that it projects anteriorly,
and looks as if a section of a smaller sphere had been engrafted
on the front of it.

The eyeball is composed of three coats or tunics, and contains
three refracting media or humours. They are as follows : —

Tunics. — 1. Sclerotic and cornea.

2. Choroid, iris, and ciliary processes.

3. Retina.

Refracting media. — 1. Aqueous.

2. Crystalline lens and capsule.

3. Vitreous.

The sclerotic (derived from the Greek word signifying hard)
covers the posterior five-sixths of the eyeball. It is composed
of a firm, unyielding, fibrous membrane, thicker behind than in
front, and serves to protect the delicate structures contained
within it. It is opaque, white and smooth externally, and

234

ANATOMY FOE, NUESES. [Chap. XIX.

behind is pierced by the optic nerve. Internally it is stained
brown where it comes in contact with the choroid coat. The
cornea (derived from Latin cornu, horn, and therefore also sig-
nifying hard) covers the anterior sixth of the eyeball. It is
directly continuous with the sclerotic coat, which, however,
overlaps it slightly above and below, as a watch-crystal is over-
lapped by the case into which it is fitted. The cornea, like the
sclerotic, is composed of fibrous tissue, which is both firm and
unyielding, but, unlike the sclerotic, it has no colour, and is

Fig. 136. — The Left Eyeball in Horizontal Section from Before Back.
1, sclerotic; 2, junction of sclerotic and cornea; 3, cornea; 4, 5, conjunctival mem-
brane; 7, ciliary muscle ; 10, choroid ; 11, 13, ciliary processes ; 14, iris ; 15, retina;
16, optic nerve ; 17, artery entering retina ; 18, fovea centralis ; 19, region where
sensory part of retina ends ; 20, ''1, 28, are placed on the lens ; 28, suspensory liga-
ment placed around lens; 29, vitreous humour; 30, aqueous humour in anterior
chamber.

perfectly transparent : it has been aptly termed the " window
of the eye." Both the cornea and the anterior portion of the
sclerotic are covered by reflections of the mucous membrane
lining the eyelids. This is called the conjunctiva, and, kept
well lubricated by the secretions of the eye, gives the eyeball
its peculiar shining and glossy aspect. The sclerotic is supplied
with very few blood-vessels, and the existence of nerves in it is
doubtful ; while the cornea has no blood-vessels, but is well
supplied with nerves.

Chap. XIX.] ORGAJ^S OF SPECIAL SENSE. 235

The choroid, or vascular coat of the eye, is a thin dark-brown
membrane lining the inner surface of the sclerotic. It is com-
posed of connective tissue, the cells of which are large and
filled with pigment, and it contains a close network of blood-
vessels. It extends to within a short distance of the cornea,
and then is folded inwards and arranged in radiating folds, like
a plaited ruffle, around the lens and just behind the edge of
the cornea. The choroid coat, properly speaking, terminates
anteriorly in the ciliary processes, arranged, as above stated, in
a radiating circle round the lens ; but closely connected with
the anterior margin of the choroid is the iris.

The iris (^iris, rainbow) is a coloured, fibro-muscular curtain
hanging in front of the lens and behind the cornea. It is
attached to the choroid, with which it is practically continuous,
and is also connected to the sclerotic and cornea at the point
where they join one another. Except for this attachment, it
hangs free in the interior of the eyeball. In the middle of the
iris is a circular hole — the pupil — through which light is
admitted into the eye-chamber. The iris, like the choroid,
is composed of connective tissue containing a large number of
pigment cells and numerous blood-vessels. It contains in
addition two sets of plain muscular fibres. One set forms a flat
band round the margin of the pupil, and is called the sphincter
or contractor of the jjupil ; the other set consists of radiating
fibres converging from the circumference to the centre, and is
called the dilator of the pupil. The action of these muscle-fibres
is affected by light. Under the influence of a bright light
the pupil involuntarily contracts so that less light is admitted
into the eye-chamber ; in a dim light the pupil involuntarily
dilates to admit as much light as possible. The posterior surface
of the iris is covered by a thick layer of pigment-cells designed
to darken the curtain and prevent the entrance of light. The
anterior surface of the iris is also covered with pigment cells, and
it is chiefly these latter which cause the beautiful colours seen in
the iris. The different colours of eyes, however, are mainly due
to the amount, and not to the colour, of the pigment deposited.

The retina, the innermost coat of the eyeball, is the most
essential part of the organ of sight, since it is the only one
directly sensitive to light. The sclerotic is the protective, the
choroid the vascular or nutritive, and tlie retina is the visual or

236

ANATOMY FOR NURSES. [Chap. XIX.

perceptive, layer of the eyeball. It forms a nearly transparent
membrane situated between the inner surface of the choroid
and the outer surface of the vitreous humour, and extending
from the exit of the optic nerve to the commencement of the
ciliary processes. The structure of the retina is interesting
in that it consists not only of a sensory epithelium and a single
group of neurones, but contains also a second series of neurones.

A study of the development of
the retina explains this remark-
able fact, for it shows that the
retina is in part really an out-
lying portion of the brain.

The accompan3dng figure shows
the relation of the neurones and
epithelial cells. Here it will be
observed that it is the axones of
the second series of neurones which
collect together to form the optic
nerve, and after penetrating the
choroid and sclerotic coats, pass
back to terminate in the brain
(Fig. 137).

The retina is usually described
as consisting of eight layers and
two limiting membranes ; of these
layers, that called the layer of
rods and cones is the most remark-
able. It is composed of specialized
epithelial cells which are directly
concerned in producing the sensa-

by their (lendrones impulses from the tion of light. Rays of light pro-
rod and cone cells and transmitting d^ce nO effect Upon the Optic nerve
them by their axones to No, the . , •, • . , • c •^

Without the intervention ot tlie
rods and cones. This is proved
by the fact that at the exit of
the optic nerve there are no rods
and cones, and this spot is quite blind, rays of light falling upon
it producing no sensation. There is one point of the retina
which is of great importance, and that is the macula lutea, or
yellow spot. It is situated about ^V of an inch (2.12 mm.)

Fig. 137. — Diagram showino
Relations of the Neurones and
Sensory Epithelium in the Ret-
ina. E, epithelial layer of nucleated
rod and cone cells, rods being direct-
ed towards choroid coat of retina;
Ni, neurones of first series receiving

neurones of the second series. The
axones of the neurones of the second
series pass along the inner surface
of the retina to the blind spot, where
they unite to form the optic nerve.

Chap. XIX.] ORGANS OF SPECIAL SENSE. 237

to the outer side of the exit of the optic nerve. In its
centre is a tiny pit (^fovea centralis) which is the centre of
direct vision ; that is, it is the part of the retina which is
always turned towards the object looked at. From this point
the sensitiveness of the retina grows less and less in all direc-
tions. In the fovea centralis the rods and cones are exceedingly
numerous, while the other retinal elements have been pushed
aside, as it were, forming an elevated margin around the pit.

Light may be described as consisting of vibrations in the
ether which pervades space. These ethereal vibrations enter
the eye through the cornea, pass in through the pupil and
refracting media, and strike on the retina. They penetrate the
transparent retina until they fall upon the rod and cone cells.
In these there occur certain substances which are acted upon by
the light (much as the film of a photographic plate is acted upon
by the light). The chemical changes which these substances
undergo stimulate the adjacent dendrones, and the impulse
passes througli the cell-bodies and the axones to the second
series of neurones, and then through their dendrones and cell-
bodies to their axones. These last converge towards the blind
spot, where they unite to form the optic nerve, which, passing
from the eye to the brain, conducts the sensory impulses derived
from the chemical changes occurring in the rods and cones to
the visual centre, and the perception of light is produced.

As in the case of the end organs of touch, each had its local
sign (see page 223), so each rod and cone has its own particular
local sign, but this local sign is not associated in our minds with
the part of the retina stimulated, as we associate touch with a
certain portion of the skin stimulated. In the case of the retina,
the local sign is associated with the source of the light which
acts as the stimulus. Thus when the upper part of the retina is
stimulated, we know that the source of light, the object which
we see, is below the line of direct vision ; and when the lower,
the right, or the left-hand portion of the retina is stimulated,
we know that the object lies above the line of direct vision, or
to the left or right of it, as the case may be.

The refracting media of the eye. — The interior of the eyeball
is divided into two chambers by the crystalline lens and iris.
The "anterior chamber," the portion in front of the iris, is filled
with a colourless, transparent watery fluid, the aqueous humour.

238 ANATOMY FOR NURSES. [Chap. XIX.

The " posterior chamber " is filled with a semi-fluid gelatinous
substance, the vitreous humour or body, so called from its glassy
and transparent apj^earance. Its refractive power, though
slightly greater than that of the aqueous humour, does not
differ much from that of water. It distends the greater part
of the sclerotic, supports the retina, which lies upon its surface,
and preserves the spheroidal shape of the eyeball.

The crystalline lens is a transparent refractive body, with con-
vex anterior and posterior surfaces, placed directly behind the
pupil, where it is retained in position by the counterbalancing
pressure of the aqueous humour and vitreous body, and by its
own suspensory ligament. It is a fibrous body, composed of
long riband-shaped cells and enclosed in an elastic capsule. Its
refractive power is greater than that of the aqueous or vitreous
humour, and it acts by virtue of its double-convex form as a
converging lens, bringing parallel or diverging rays to a focus
on the posterior surface of the retina. The function of the
crystalline lens is to bring to a focus all the rays of light
emanating from each separate point in the object seen, so that
all the light from each point falls on and stimulates a corre-
sponding point on the retina. For if the eye consisted only of
a sensitive retina, impressions of light could be received, but the
form of objects would not be distinguished.

The action of the lens in thus focussing the rays of light at
a particular point may be illustrated in the following manner :
If a sheet of white paj)er be held at a short distance from a
candle-flame, in a room with no other light, the whole of the
jDaper will be moderately and uniformly illuminated by the
diverging rays. But if a double-convex lens, Avith suitable cur-
vatures, be interposed between the j^aper and the light, the
outer portions of the paper will become darker, and its central
portion brighter, because a portion of the rays are diverted
from their original course and bent inward. By varying the
distance of the lens from the paper, a point will at last be found
where none of the light reaches the external parts of the sheet,
but all of it is concentrated upon a single spot ; and at this spot
will be seen a distinct image of the candle and its flame, i.e.
each point of the flame is now represented by a single point on
the paper ; and if for the paper we were to substitute the
retina, each point would stimulate one, and only one, small area
of the retina.

Chap. XIX.] OKGANS OF SPECIAL SENSE.

239

Perception of the figure of external objects therefore depends
on the action of the crystalline lens in converging all the i&js,
emanating from a given point, to a focus on the retina. When
the lens of the eye is too convex, and its refractive power
excessive, the rays of light convei'ge too soon and cross one
another before reaching the retina , consequent!}-, the image
produced is not concentrated and distinct, but. dispersed more
or less over the surface of the retina, is diffused and dim. On
the other hand, if the lens
is too flat, the rays do not
converge soon enough, and
the imacre is ag^ain diffused
and indistinct. To remedy
a too great convexity of the
lens in the short-siglited or
myopic eye, concave specta-
cles are used to disperse the
rays ; to remedy the flattened
lens in the hypermetropic or
long-sighted eye, we employ
convex glasses to concen-
trate and focus the rays
more quickly.

A normal eye is capable

of distinct vision through- fig. 138. -Diagram illustrating Rays

out an immense range. We of Light convebging in a Normal Eye,

,, . .,,. » (A), A Myopic Eye, (B), and a Hyper-

can see the stars milnons ot metropic Eye (C).
miles away, and with the

same eye, though not at the same time, we can see objects within
a few inches of us. To be able to see objects millions of
miles away and within a short range, the eye has to accom-
modate or adjust itself to different distances. This ac-
commodation is accomplished mainly by the lens changing its
convexity. In accommodation for near objects, the lens becomes
more convex and the pupil of the eye likewise contracts. This
convexity is brought about by muscular effort,^ and is always
more or less fatiguing. The accommodation for distant objects
is a pa.ssive condition, the convexity of the lens being unaltered

1 Connected with the lens are tiny muscles, — the ciliary muscles, — contraction
of which alters the shape of the lens.

240 ANATOMY FOR NURSES. [Chap. XIX.

and the pupil of the eye dilated, and it is on this account that
the eye rests for an indefinite time upon remote objects without
fatigue.

The eyeball is often compared to a photographer's camera.
It is essentially a hollow spherical box filled with fluids, hav-
ing its interior surface darkened by pigment, and containing a
system of lenses by means of which images can be formed, and
a screen upon which they can be received. In front is a cur-
tain or diaphragm (the iris), with a variable central aperture
(the pupil) to regulate the amount of light admitted.

The colour of light is considered to be analogous to the pitch of
sound. As the latter is determined by the number of vibrations
of the atmosphere which strike the ear in a second, so the former
depends on the number of the waves of ether which strike the
retina in a second. The lowest note of an ordinary musical scale
has, as we have already remarked, sixteen vibrations per second;
the highest, 38,000 per second. The number of ether-waves
which strike the retiua in a second to produce the sensation of
red (which lies at the bottom, so to speak, of the colour-scale)
is estimated at 474,439,680,000,000. The number required to
cause the sensation of violet, which lies at the other extreme of
our colour-perception, is estimated at 699,000,000,000,000 !

The muscles which move the eyeball are the four straight or
recti and the two oblique. They have been sufficiently de-
scribed on page 60.

The appendages of the eye are the eyebrows, eyelids and
lachrymal glands.

The eyebrows are composed of two arched eminences of
thickened skin, connected with three muscles, which by their
action control to a limited extent the amount of light admitted
into the eye. The eyebrows are furnished with numerous
short, thick hairs, lying obliquely on the surface.

The eyelids are two folds, projecting from above and below
in front of the eye. They are covered externally by the skin
and internally by a mucous membrane, the conjunctiva, which
is reflected from them over the globe of the eye. They are
composed for the most part of connective tissue, which is
dense and fibrous under the conjunctiva, where it is known
as the tarsus.

Embedded in the tarsus is a row of elongated sebaceous glands

Chap. XIX.] ORGANS OF SPECIAL SENSE.

241

(the Meibomian glands ^), the ducts of which open on the edge
of the eyelid. The secretion of these glands is provided to
prevent adhesion of the eyelids.

Arranged in a double or triple row at the margin of the lids
are the eyelashes ; those of the upper lid, more numerous and
longer than the lower, curve upwards ; those of the lower lid
curve downwards, so that they do not interlace in closing the
lids. The upper lid is attached to a small muscle which is
called the elevator of the upper lid ; and arranged as a sphincter
around both lids is the orbicularis palpebrarum muscle, which
closes the eyelids, and is the direct antagonist of the elevator of
the upper lid.

The slit between the edges of the lids is called the palpe-
bral fissure. It is the size of this fissure which causes the
appearance of large and small eyes, as the size of the
eyeball itself varies but little. The outer angle of this fissure
is called the external canthus ; the inner angle, the iyiternal
eanthus.

The eyelids obviously serve for the protection of the eye ;
movable shades which by their closure exclude light, par-
ticles of dust, and other
injurious substances.

The lachrymal gland is
a compound gland, closely
resembling the salivary
glands in structure. It
secretes the tears, and is
lodged in a depression at
the outer angle of the
orbit. It is about the size
and shape of an almond.
Its ducts run obliquely
beneath the conjunctiva,
and open by a series of
minute orifices upon the
upper surface of the eye.

After passing over the surface of the eyeball, the tears are carried
away through minute openings in the inner angle of the eye into

1 By inverting the eyelids, these glands may be seen through the conjunctiva
lying in parallel rows.

Fig. 139. — The Lachrymal Apparatus.

242 ANATOMY FOR NURSES. [Chap. XIX.

the lachrymal sac, which is the upper dilated portion of the
nasal duct.

The nasal duct is a membranous canal, about three-quarters
of an inch (19 mm.) in length, which extends from the lach-
rymal sac to the inferior meatus of the nose, into which it opens
by a slightly expanded orifice.

The tears consist of water containing a little salt and albu-
min. They are ordinarily carried away as fast as formed, but
under certain circumstances, as when the conjunctiva is irri-
tated, or when painful emotions arise in the mind, the secretion
of the lachrymal gland exceeds the drainage power of the nasal
duct, and the fluid, accumulating between the lids, at length
overflows, and runs down the cheeks.

CHAPTER XX.

FEMALE GENERATIVE ORGANS.

The internal female generative organs are the vagina, uterus,
Fallopian tubes, and ovaries.

The vagina. — The vagina is a distensible and curved musculo-
membranous canal, extending from the vulva to the uterus.
The posterior wall is about three and a half inches (89 mm.)
long, while the anterior wall is only three inches (76 mm.).
The front or anterior wall is united by connective tissue with
the posterior walls of the bladder and urethra, the partition or
septum between the bladder and vagina being called the vesico-
vaginal, and that between the urethra and vagina, the urethro-
vaginal, septum. And, if we divide the posterior wall of the
vagina into five sections, we find that the middle three-fifths is
connected with the rectum, the united walls of rectum and
vagina forming the recto-vaginal septum ; ^ the lower fifth is
separated from the rectum and is joined to the perineum ; ^
while the upper fifth extends up behind the neck of the uterus.

The vagina is made up of three coats, an outer, fibrous ;
middle, muscular ; and inner, mucous. The muscular coat in-
creases during pregnancy, and the mucous coat is arranged in
transverse folds or rugse, which allow of dilatation of the canal
during labour and birth.

The uterus. — The uterus is a thick-walled, hollow, pear-
shaped organ, situated in the middle of the pelvic cavity.
Its upper end is a little below the level of the superior strait
of the pelvis (vide page 46); its lower end projects into the
vagina. The bladder lies in front of it ; the rectum, behind ;

1 Perforations of the vesico-vaginal and recto-vaginal partitions constitute
vesico-vaginal and recto-vaginal fistulae.

2 The perineum is a triangular section of tissue, made up of muscles strength-
ened vfith very strong fascia, placed between the rectum and vagina, and forming
the floor of the pelvis.

243

244 ANATOMY FOR NURSES. [Chap. XX.

the vagina, below; and the small intestine rests upon it
above. Its length is roughly estimated to be about three
inches (76 mm.); its greatest width, one and one-half inches
(38 mm.); and its thickness, one inch (25.4 mm.). At the
end of pregnancy it attains the length of a foot (305 mm.)

Fig. 140. — Section of Female Pelvis, showing Relative Position of Viscera.

or more, and measures about eight to ten inches (203 to
254 mm.) transversely.

The uterus is divided for purposes of description into three
parts, the fundus, body, and neck. The fundus is the roinided
portion projecting above a line drawn transversely through the
upper part of the organ. The body is the portion extending
from the rounded section, the fundus, to the constricted section,
the neck. The neck or cervix extends from the body of the
uterus into the vagina.

Chap. XX.] FEMALE GENERATIVE ORGANS. 245

Owing to the thickness of its walls, the cavity of the uterus
is comparatively small. The cavity is triangular in shape (v)»
and has three openings, one at each upper angle, communicating
with the Fallopian tubes, and one, the os internum, or internal
mouth, opening into the cavity of the cervix below. The cav-
ity of the cervix, which is, of course, continuous with the
cavity in the body, is constricted above, where it opens into
the body by means of the os internum, and below, where it
opens exteriorly by means of the os externum, ^ or external
mouth. Between these two openings, the cavity of the cervix
is somewhat enlarged.

The walls of the uterus consist mainly of bundles of plain
muscular tissue, arranged in layers which run circularly, longi-
tudinally, spirally, and cross and interlace in every direction.
A part of the external surface is covered by a portion of the
peritoneum in the form of broad ligaments, and the inner sur-
face is lined by a mucous membrane. This mucous membrane
is continuous with that lining the vagina and Fallopian tubes.
It is highly vascular, provided with numerous mucous glands,
and is covered with ciliated epithelium.

The uterus is abundantly supplied with blood-vessels, lym-
phatics, and nerves. The blood reaches the uterus by means
of the uterine arteries from the internal iliacs, and the ovarian
arteries from the aorta. Where the neck joins the body of
the uterus, the arteries from both sides are united by a branch
vessel, called the circumflex artery. If this branch is cut dur-
ing a surgical operation, or a tear of the neck during partu-
rition extends so far as to sever it, the hemorrhage is very
profuse. The arteries are remarkable for their tortuous course
and frequent anastomoses. The veins are of large size and cor-
respond in their behaviour to the arteries.

During pregnancy all the tissues of the uterus become much
enlarged, undergoing what is called a physiological hupertropliy.
The uterus increases in weight from two or three ounces (57 to
85 grammes) to two or three pounds (907 to 1360 grammes).
After parturition, it goes back to nearly its former size. The
tissues all go through a gradual shrinkage, or what is called a
physiological atrop>hy. The enlarged muscles especially undergo

1 The OS externum is bounded by two folds or lips of the mucous membrane,
the anterior of which is thick, and the posterior narrow and long.

246

ANATOMY FOR NURSES.

[Chap. XX.

fatty degeneration and absorption, called " involution," in con-
tradistinction to "evolution " or development. This process of
involution is not accomplished under six weeks, and sometimes
requires longer.

The uterus is not firmly attached or adherent to any j)art of
the skeleton. It is, as it were, suspended in the pelvic cavity,
and kept in position by ligaments. A full bladder pushes it
backward ; a distended rectum, forward. It alters its position,
by gravity, with change of posture. During gestation it rises
into the abdominal cavity.

The uterus has five pairs of ligaments attached to it, the
chief of which are the broad and round ligaments. The broad

"rtsffie pasted throii^^

Fig. 141. — The Uterus and its Appendages. Anterior View.

ligaments are folds of peritoneum slung over the front and back
of the uterus, and extending laterally to the walls of the pelvis.
The anterior fold covers the front of the uterus as far as the
middle of the cervix, when it turns up and is reflected over
the back wall of the bladder. The posterior fold covers the
back of the uterus, and extends far enough below to also
cover the upper one-fiftli of the back wall of the vagina, when
it turns up and is reflected over the anterior wall of the rectum.
Thus the uterus, Avith, and between its two broad ligaments,
forms a transverse partition in the pelvic cavity, the bladder,
vagina, and urethra being in the front compartment, and the
rectum in the back compartment. The round ligaments are
two rounded fibro-muscular cords, situated between the folds
of the broad ligament. They are about four and a half inches
(114 mm.) long, and extend from the upper angle of the uterus
forwards and outwards to be inserted into the vulva.

Chap. XX.] FEMALE GENERATIVE OEGANS. 247

Fallopian tubes. — The Fallopian ^ tubes or oviducts are pro-
vided for the purpose of conveying the ova from the ovaries
into the cavity of the uterus. They are two in number, one on
each side, and pass from the upper angles of the uterus in a
somewhat tortuous course between the folds and along the
upper margin of the broad ligament, towards the sides of the
pelvis. Each tube is about four inches (102 mm.) in length,
and is described as consisting of three portions : (1) the isth-
mus^ or inner constricted half ; (2) . the ampulla, or outer
dilated portion, which curves over the ovary ; and (3) the
wfiDidibidmn, or trumpet-shaped extremity, the margins of
whicli are frayed out into a number of fringe-like processes
called fimhrice. One of these fimbriae is attached to the ovary.
The uterine opening of the Fallopian tube is minute, and will
only admit a fine bristle ; the abdominal opening (ostium ab-
dominale) is comparatively much larger.

The Fallopian tube consists, like the uterus, of three coats :
the external or serous coat, derived from the peritoneum ; the
middle or muscular coat, having a layer of longitudinal and of
circular fibres ; and the internal or mucous coat, continuous at
the inner end with the mucous lining of the uterus, and at the
distal end with the serous lining of the abdominal cavity. This
is the only instance in the body in which a mucous and serous
lining are continuous with one another.

When the ovum is ready for entrance into the Fallopian tube,
the fimbriae of the free end grasp the ovary, the tiny germ-cell
is safely conducted into the trumpet-shaped extremity, and is
thence carried along by the peristaltic motion of the oviduct
into the uterus. This transmission of the cell is also assisted
by the ciliated epithelium lining the tube, the motion of the
cilia wafting it onwards.

The ovaries. — The ovaries are two small almond-shaped
bodies, situated one on each side of the uterus, between the
anterior and posterior folds of the broad ligament, and below
the Fallopian tubes. Each ovary is attached by its inner end
to the uterus by a short ligament — the ligament of the ovary;
and by its outer end to the Fallopian tube by one of the fringe-
like processes of the fimbriated extremity. The ovaries each
measure about one and a half inches (38 mm.) in length, three-
1 Named after Fallopius, an Italian anatomist.

248

ANATOMY FOR NURSES.

[Chap. XX

fourths of an inch (19.0 mm.) wide, and one-third of an inch
(8.5 mm.) thick, and Aveigh from one to two drachms (1.8 to
3.5 grammes). Their function is to produce, develop, and

Fig. 142. — Section of an Ovary. Very highly magnified. (Waldeyer.)
a, germ-epithelium; b, egg-tubes; c, c, small follicles; d, more advanced follicle;
e, discus proligerus and ovum; /, second ovum in same follicle (this occurs but
rarely); g, outer tunic of the fdllicle; h, inner tunic; ;', membrana granulosa;
k, collapsed retrograded follicle ; I, I, blood-vessels ; y, involuted portion of the
germ-epithelium of the surface ; z, place of the transition from peritoneal to ger-
minal or ovarian epithelium.

mature the ova, and to discharge them when fully formed
from the ovary.

The ovaries consist of a framework of connective and muscu-
lar tissue, usually called the stroma or bed of the organ ; and
of numerous vesicles or follicles of different sizes, called the
Graafian follicles.

Chap. XX.] FEMALE GENERATIVE ORGANS. 249

The stroma contains many blood-vessels and lymphatics. The
outer portion is more condensed than the interior, and the whole
is covered by a peculiar layer of columnar epithelium-cells,
called germinal epithelium.

The Graafian follicles are cavities dotted about in the stroma
in large numbers. The smaller ones lie near the surface. The
larger are more deeply embedded, and only approach the sur-
face when they are ready to discharge their contents. The
follicles have each their own proper wall or tunic, derived from
the connective tissue of the stroma, and each is lined by a layer
or layers of granular epithelium-cells, and contains an ovum.
The granular layer of cells, closely lining the cavity of the follicle,
is termed the memhrana granulosa, but at one or other side it is
heaped up into a mass of cells which j)rojects into the cavity of
the follicle and envelops the ovum. This mass of cells which
immediately surrounds the ovum is called the discus proligerus.

As the follicle matures, fluid collects in the cavity, and, in-
creasing in amount, the follicle gradually becomes larger and
more tense. It now approaches the surface and begins to form
a protuberance like a small boil upon the outside of the ovary.
Finally the wall of the ovary and the wall of the follicle burst
at the same point, and the fluid (liquor foUlculi^ containing the
ovum, with the loose, irregular mass of cells, the discus pro-
ligerus, clinging to it, is set free. At the moment of rupture,
the ovum is received by the Fallopian tube and afterwards con-
veyed to the uterus. After the follicle has discharged its con-
tents, it has done its work, and it passes through a series of
degenerative changes, and eventually disappears. Thus in the
same ovary some of the follicles are mature, or approaching
maturity ; others are undergoing development ; while others
are retrograding and disappearing.

The ova are formed from the germ-epithelium on the surface
of the ovary, the cells of which become enlarged and dip down
into the stroma in the form of little elongated masses. From
these groups of cells the Graafian follicles and the ova are pro-
duced. The ovum is a single cell about -^^ inch (0.203 mm.)
in diameter. It has (1) a thick, surrounding envelope or
membrane, called the vitelline membrane or zona pellucida ;
(2) within the membrane or cell-wall is the protoplasm of
the cell, filled with fatty and albuminous granules, and usually

2o0 ANATOMY FOR NURSES. [Chap. XX

called the vitellus or yolk ; (3) imbedded in the vitellus or yolk
is a transparent, sharply outlined nucleus, the germinal vesicle ;
and (4) in the germinal vesicle is a small dark nucleolus, the
germinative spot.

It is impossible for us to trace the growth and development
of a fecundated ovum. The subject is too complicated for us
to attempt to describe it in a book of this kind, and we shall,
therefore, content ourselves with briefly describing the first two
or three steps.

Soon after leaving the ovary, the germinal vesicle and ger-
minal spot in a fecundated ovum disappear, and the protoplasm
begins to divide inside the vitelline membrane into two halves,
in each of which appears a nucleus. The halves divide into
quarters, the quarters into eighths, and so the subdivision con-
tinues until a great number of minute cells are produced, which
soon arrange themselves, close to each other like bricks in a
wall, upon the inner surface of the vitelline membrane. The
cells thus in close contact with one another form a membrane,
called the epiblast. Upon this membrane a second one soon
appears, formed in the same way and lining its inner surface.
This is called the hypoblast. Subsequently a third membrane,
the mesoblast, is developed between the epi- and hypoblast, and
from these three membranes all the tissues and complicated
structures of the body are evolved.

Upon the arrival of the ovum in the uterus, it is grafted
upon the mucous membrane. It usually lodges upon the upper
surface of the uterus, between two folds of the mucous lining,
which soon grow up all around it, and, as it were, bury the germ
in a circular grave. From the thickened mucous membrane
lying between the ovum and the uterine wall, the placenta is
ultimately formed for the nourishment of the embryo.

The mammary glands. — The mammary gland is a compound
gland, formed of branching ducts ending in secretory recesses.
The whole organ is divided by connective tissue partitions into
a number of lobes, each of which possesses its own excretory
duct opening by a separate orifice upon the surface of the
nipple, the gland being in fact not a single gland, but several
glands bound together. Just before opening on to the nipple,
each excretory duct is widened into a flask-shaped enlarge-
ment.

Chap. XX.] FEMALE GENERATIVE ORGANS. 251

The walls of the ducts and of the secreting recesses are
formed of a basement membrane lined by epithelium-cells.
During lactation the secreting cells become much enlarged,
and fatty globules are formed within them. The fatty glob-
ules appear to be set free by the breaking down of the inner
part of the cell, the protoplasm becoming dissolved also, and
forming the proteid substances of the milk. At the beginning
of lactation the cells are imperfectly broken up, so that numerous
cells containing comparatively large masses of fat (the colostrum
corpuscles) appear in the secretion.

Human milk has a specific gravity of from 1028 to 1034, and
when quite fresh possesses a slightly alkaline reaction. Its
average composition in every 100 parts is : —

Proteids 2

Fats 2.75

Sugar 5

Salts 0.25

Water 90

100

{Foster.)

GLOSSARY.

Abdu'cens. [From the Lat. ab, "from," and duco, to "lead."] A term ap-
plied to the sixth pair of cranial nerves which supply the external recti
(abductor), muscles of the eye.

Acetab'ulum. [From the Lat. acetwn, " vinegar."] A name given to the
cavity in the os innominatum, resembling in shape an old-fashioned
vinegar vessel.

Acro'mion. [From the Gr. akron, " summit," and dnos, the " shoulder."]
The triangular-shaped process at the summit of the scapula.

Ad'enoid. [From the Gr. aden, a "gland," and eidos, "form" or "resem-
blance."] Pertaining to, resembling a gland.

Ad'ipose. [From the Lat. adeps, " fat."] Fatty.

Afferent. [From the Lat. ad, " to," and fero, to " bear," to " carry."] Bear-
ing or carrying inioards, as from the periphery to the centre.

Ag'minated. [From the Lat. agmen, a " multitude," a " group."] Arranged
in clusters, grouped.

Albu'min. [From the Lat. albus, " white."] Animal albumin is the chief
solid ingredient in the tuhile of eggs.

Albuminu'ria. [A combination of the words " albumin " and " urine."]
Presence of albumin in the urine.

Aliment'ary. [From the Lat. alimentum, " food."] Pertaining to aliment or
food.

Alimenta'tion. The act of receiving nourishment.

Alve'olar. [From the Lat. alveolus, a " little hollow."] Pertaining to the
alveoli, the cavities for the reception of the teeth.

AmcE'ba. [From the Gr. ameibo, to "change."] A single-celled, proto-
plasmic organism, which is constantly changing its form by protrusions
and withdrawals of its substance.

Amce'boid. Like an amoeba.

Amphiarthro'sis. [From the Gr. ampJio, " both," and arthron, a " joint."]
A mixed articulation ; one which allows slight motion.

Anaboric. [From the Gr. anaballo, to "tnrow" or "build up."] Pertaining
to anabolism, the process by means of which simpler elements are built
up into more complex.

Anasthe'sia. [From the Gr. a, an, " without," and aisthanomai, to " per-
ceive," to " feel."] A condition of insensibility.

2oZ

254 GLOSSAKY.

Anastomo'sis. [From the Gr. ana, " by," " through," and stoma, a " mouth."]
Comniunication of branches of vessels with one another.

Aor'ta. [Gr. ao?-te from cero, to "raise up."] The great artery that rises up
from the left ventricle of the heart.

Aponeuro'sis. [From the Gr. apo, "from," and neuron, a "nerve."] A
fibrous membranous expansion of a tendon ; the nerves and tendons
were formerly thought to be identical structures, both appearing as
white cords.

Arach'noid. [From the Gr. arachne, a "spider," a " spider's web," and eidos,
" form " or " resemblance."] Resembling a tveb.

Are'olar. [From the Lat. areola, a " small space," dim. of area.'] A term
applied to a connective tissue containing small spaces.

Ar'tery. [From the Gr. aer, "air," and iereo, to "keep."] Literally, an
air-keeper (it being formerly believed that the arteries contained air.)
A tube which conveys blood from the heart to all parts of the body.

Arthro'dia. [From the Gr. arthron, a " joint."] A movable joint.

Artic'ular. Pertaining to an articulation or joint.

Asphyx'ia. [From the Gr. a, " without," and spliyxis, the " pulse."] Liter-
ally, without pulse. Condition caused by non-oxygenation of the
blood.

At'rophy. [From the Gr. a, " without," and trophe, " nourishment."] Wast-
ing of a part from lack of nutrition.

Aud'itory. [From the Lat. audio, auditum, to "hear."] Pertaining to the
sense or organ of hearing.

Aur'icle. [From the dim. of Lat. auris, the "ear."] A little ear, a term
applied to the ea?--shaped cavities of the heart.

Auric' ulo-ventric'ular. Pertaining to the auricles and ventricles of the heart.

Ax'one. The name now given to the prolonged processes of the neurone, or
nerve-cell. The axis-cylinder of the nerve-fibre.

Az'ygos. [From the Gr. a, " without," and zygos, a "yoke."] Without a
fellow.

Bi'ceps. [From the Lat. bis, " twice," and caput, the " head."] A term

applied to muscles having a double origin or two heads.
Bicus'pid. [From the Lat. bis, " twice," and cuspis, the " point of a spear."]

Having two points.
Brach'iaL [From the Lat. brachium, the " arm."] Belonging to the arm.
Buc'caL [From the Lat. bucca, the "cheek."] Pertaining to the cheek;

the mouth cavity formed chiefly by the cheeks.
Bur' sal. [From the Gr. bursa, a " bag."] Pertaining to bursce, membranous

sacs.

Cae'cum. [From the Lat. ccecus, " blind."] The blind gut.

Ca'lices, pi. of Ca'lyx. [From the Gr. Z.a/^x, a "cup."] Anatomists have

given this name to small cup-Yike membranous canals, which surround'

the papilla? of the kidney, and open into its pelvis.
Canalic'ulus, pi. Canalic'uli. [Dim. of Lat. canalis, a "channel."] A small

channel or vessel.

GLOSSARY. 255

Can'cellated. [From the Lat. cancelli, " lattice-work."] A term used to

describe the spongy lattice-work texture of bone.
Can'thus. [(ir. Kanthos, the " angle of the eye."] The angle formed by the

junction of tlie eyelids, the internal being the greater, the external the

lesser, canthus.
Cap'illary. [From the Lat. capilhis, "hair."] A minutely fine vessel, resem-
bling a hair in size.
Car'bon. An elementary body, one of the principal elements of organized

bodies.
Carbon Di-ox'ide. COg. Carbonic acid.

Car'dio-inhib'itory. [From the Lat. kardia, " heart," and inhibeo, to " re-
strain."] An agent which restrains the heart's action.
Carot'ids. [Perhaps from the Gr. karos, "stupor," because pressing on them

produces stupor.] The great arteries conveying blood to the head.
Ca'sein. [From the Lat. caseus, " clieese."] The albumin of milk; the

curd separated from milk by the addition of rennet, constituting the

basis of cheese.
Caud'a Equi'na. [Lat.] "Horse-tail." A term applied to the termination

of the spinal cord, which gives off a large number of nerves which, when

unravelled, resemble a horse's tail.
Cel'lulose. Basis of vegetable fibre.
Cerebel'lum. [Dim. of Lat. cerebrum, the "brain."] The hinder and lower

part of the brain ; the little brain.
Cer'ebrum. [Lat. the "brain."] Chief portion of brain.
Ceru'minous. [From the Lat. cerumen, "ear-wax."] A term applied to the

glands secreting cerumen, ear-wax.
Choles'terin. [From the Gr. xule, "bile," and stear, "fat."] A tasteless,

inodorous, fatty substance found in the bile, blood, and nervous tissue.
Chon'drin. [From the Gr. chondros, "cartilage."] A kind of gelatin

ol)tained by boiling cartilaf/e.
Chor'dae Tendin'eae. [Lat.] Tendinous cords.

Cho'roid. [From the Gr. chorion, "skin," and eidos, "form" or "resem-
blance."] A skin-like membrane : the second coat of the eye.
Chyle. [From the Gr. t?//os, "juice."] Milky fluid of intestinal digestion.
Chyme. [From the Gr. kymos, "juice."] Food that has undergone gastric

but not intestinal digestion. (Both chyle and chyme signify literally

liquid or juice.)
Cica'trix. [Lat. a " scar."] The mark or scar left after the healing of a

wound.
Cil'ia. [Lat. the "eyelashes."] Hair-like processes of certain cells.
Cil'iary. Pertaining to the cilia.
Cil'iated. Provided with cilia.
Circumval'late. [From the Lat. circumvallo, " to surround with a wall."]

Surrounded by a wall.
Clav'icle. [From the dim. of Lat. clavis, a "key."] The collar-bone, so

named from its shape.
Coc'cyx. [Lat. the " cuckoo."] The lower curved bone of the spine,

resembling a cuckoo's bill in shape.

256 GLOSSARY.

Coch'lea. [Lat. a " snail," a " snail-shell " ; hence, anything spiral.] A

term applied to a cavity of the internal ear.
Coe'liac. [From the Gr. koilos, " hollow."] Pertaining to the abdominal

caoity.
Co'lon. [Gr. kolon.'] That portion of the large intestine which extends

from the caecum to the rectum.
Colos'trum. First milk secreted after labour.
Colum'nae Car'ne£B. [Lat.] "Fleshy columns"; muscular projections in the

ventricles of the heart.
Colum'nar. Formed in columns : having the form of a column.
Com'missure. [From the Lat. con, "together," and milto, missum, to "put."]

A joining or uniting together. Something which joins together.
Con'cha. [Lat. a "shell."] A term applied to the hollow portion of the

external ear.
Con'dyloid. [From the Gr. kondylos, a "knob," or "knuckle," and eidoSy

"likeness."] A term applied to joints and processes of bone having

flattened knobs or heads.
Conjuncti'va. [From the Lat. con, "together," and jungo,junctum, to " join."}

A term applied to the delicate mucous membrane which lines both eye-
lids and covers the external portion of the eyeball.
Co'rium. [Lat. the "skin."] The deep layer of the skin ; the derma.
Cor'nea. [Fi'om the Lat. cornu, a " horn."] The transparent anterior portion

of the eyeball.
Coro'nal. [From the Lat. corona, a " crown."] Pertaining to the crown.
Cor'onary. [From the Lat. corona, a " crown."] A term applied to vessels,

ligaments, and nerves which encircle parts like a crown, as the coronary

arteries of the heart.
Cor'pus Callo'sum. [Lat.] " Callous body," or substance. A name given to

the hard substance uniting the cerebral hemispheres.
Cor'puscle. [From the dim. of Lat. corpus, a " body."] A sinall body or

particle.
Cor'tex. [Lat. " bark."] External layer of kidney : external layer of brain.
Cos'tal. [From the Lat. costa, a " rib."] Pertaining to the ribs.
Cra'nium. [Lat.] The skull.
Crassamen'tum. [From the Lat. crassus, " thick."] The thick deposit of

any fluid, particularly applied to a clot of blood.
Crena'ted. [From the Lat. crena, a "notch."] Notched on the edge.
Crib'riform. [From the Lat. cribrum, a " sieve," and /orma, "form."] Perfo-
rated like a siei^e.
Cru'ra Cer'ebri. [From the Lat. cms (pi. crura), a "leg."] Legs or pillars

of the cerebrum.
Cry'pt. [From the Gr. krypto, to "hide."] A secreting cavity: a folli.^le

or glandular cavity.
Cu'ticle. [From the dim. of Lat. cutis, the "skin."] A term applied to the

upper or epidermal layer of the skin.
Cu'tis Ve'ra. [Lat.] The true skin ; that underneath the epidermal layer.
Cys'tic. [From the Gr. kystis, the "bladder."] Pertaining to a cyst, — a

bladder or sac.

GLOSSARY. 257

Cy'toplasm. [From the Gr. kiitos, a " cell," and plasso, to " form."] The
name given by Kolliker to the contents of a cell: same as proto-
plasm.

Decussa'tion. [From the Lat. decusso, decussatum, to "cross."] The crossing
or running of one portion athwart another.

Del'toid. Having a triangular shape ; resembling the Gi'eek letter A (delta).

Den'drone. The name given to the branching processes of the neurone which
begin to divide and subdivide as soon as they leave the nerve-cell.

Dex'trin. A soluble substance obtained from starch.

Dex'trose. CgHj^Og. A form of sugar found in honey, grapes, and other
fruits.

Diabe'tes Mel'litus. [From the Gr. dia, "through," baino, "to go," and meli,
" honey."] Excessive flow of sugar-containing urine.

Dial'ysis. [From the Gr. dialyo, to "dissolve."] Separation of liquids by
membranes.

Diapede'sis. [From the Gr. dia, "through," and pedad, to "leap," to "go."]
Passing of the blood-corpuscles through vessel walls without rupture :
sweating of blood.

Di'aphragm. [From the Gr. diaphrasso, to " divide in the middle by a parti-
tion."] The partition muscle diciding the cavity of the chest from that
of the abdomen.

Diarthro'sis. [From the Gr. dia, "through," as implying no impediment,
and arthron, a " joint."] A freely movable articulation.

Dias'tole. [From the Gr. diastello, to " dilate."] The dilation of the heart.

Dip'loe. [From the Gr.diploo, to "double," to "fold."] The osseous tissue
between the tables of the skull.

Diox'ide. [From the Gr. dis, " twice," and " oxide."] A compound contain-
ing two atoms of oxygen to one of base, or metal.

Dis'cus Prolig'erous, or germ disk. A term applied to a mass of cell cling-
ing to the ovum when it is set free from the ovary.

Dis'tal. [From the Lat. dis, " apart," and sto, to " stand."] Away from the
centre.

Dor' sal. [From the Lat. dorsum, the " back."] Pertaining to the back or
posterior part of an organ.

Duc'tus Arterio'sus. [Lat.] Arterial duct.

Duc'tus Veno'sus. [Lat.] Venous duct.

Duode'num. [From the Lat. rfuoc/e^u', "twelve each."] First part of small
intestines, so called because about twelve fingers' breadth in length.

Du'ra Ma'ter. [Lat.] The " hard mother," called dura because of its great
resistance, and mater because it was formerly believed to give rise to
every membrane of the body. The outer membrane of the brain and
spinal cord.

Dyspnoe'a. [From the Gr. dys, "difficult," and pneo, to "breathe."] Diffi-
cult breathing.

Efferent. [From the Lat. effero, to " carry out."] Bearing or carrying out-
wards, as from the centre to the periphery.

258 GLOSSARY.

Elimina'tion. [From the Lat. e, " out of," and liyiien, liminis, a " threshold."]
The act of expelling waste matters. Eliminate signifies, literally, to
throw out of doors.

Em'bryo. The ovum and product of conception up to the fourth mouth,
when it becomes known as the foetus.

Enarthro'sis. [From the Gr. en, "in," and arthron, a "joint."] An articu-
lation in which the head of one bone is received into the cavity of
another, and can be moved in all directions.

Endocar'dium. [From the Gr. endon, " within," and kardia, " the heart."]
The lining membrane of the heart.

En'dolymph. [From the Gr. endon, "within," and Lat. lympha, "water."]
The fluid in the membranous labyrinth of the ear.

Endothe'lium. [From the Gr. endon, "within," and thele, the "nipple."] A
term applied to single layers of flattened transparent cells applied to
each other at their edges, and lining certain surfaces and cavities of the
body. In contradistinction to ephithelium.

En'siform. [From the Lat. ensis, a " sword," and forma, " form."] Shaped
Like a sicord.

En'zyme or Enzy'ma. [From the Gr. en, "in," and zume, "leaven."] A term
applied to a class of ferments.

Ep'iblast. [From the Gr. ejn, "upon," and blastos, a "germ," or "sprout."]
The external or upper layer of the geiininal membrane.

Epider'mis. [From the Gr. epi, "upon," and derma, the "skin."] The outer
layer of the skin.

Epiglot'tis. [From the Gr. epi, "upon," and glottis, tlie "glottis."] The
cartilage at the root of the tongue which forms a lid or cover for the
aperture of the larynx.

Epithe'lial. [From the Gr. epi, "upon," and thele, the "nipple."] Pertain-
ing to the epithelium, the cuticle covering the nipple, or any mucous
membrane.

Eth'moid. [From the Gr. ethmos, a "sieve," and eidos, "form," "resem-
blance."] Sieve-like. A bone of the cranium, part of which is pierced
by a number of holes.

Eusta'chian Tube. A tube extending from behind the soft palate to the
drum of the ear, first described by Eustachius.

Fallo'pian. A term applied to tubes and ligaments first pointed out by the

anatomist Fallopius.
Fas'cia, pi. Fas'ciae. [I^at.] A bandage, — that which binds ; a membranous

fibrous covering.
Fau'ces. [Lat., pi. of faux, faucis, the " throat."] The cavity at the back of

the mouth from which the larynx and pharynx proceed.
Fem'oral. Pertaining to the femur.
Fe'mur. [Lat.] The thigh.
Fenes'tra. [Lat.] A window.

Fibril'la, pi. Fibril'lge. [Dim. of Lat. f bra, a "fibre."] A little fibre.
Fibrin'ogen. A proteid in blood plasma, main constituent of fibrin.
Fib'ula. [Lat. a "clasp."] The long splinter bone of the leg.

GLOSSAKY. 259

Fil'iform. [From the Lat. Jilum, a " thread," and forma, " form."] Thread-
like.

Fim'briae. [Lat. " threads," a " fringe."] A border or /nn^e.

Fim'briated. Fringed.

Fis'sion. [From the Lat. Jindo, Jissum, to "cleave."] A cleaving or breafe-
ing up into two parts.

Foe'tus. The child in utero from the fifth month of pregnancy till birth.

Follicle. [From the dim. of Lat. follis, a " bag."] A little bag ; a smaQ
gland.

Fontanelle'. [Fr.] A little fountain. A term applied to the membranous
spaces between the cranial bones in the new-born infant, in which the
pulsation of the blood in the cranial arteries was imagined to rise and
fall like the water in a fountain.

Fora'men. pi. Foram'ina. [Lat.] An opening, hole, or aperture.

Foramen Mag'num. [Lat.] A large opening.

Fora'men Ova'le. [Lat.] An oval opening.

Fos'sa, pi. Fos'ssB. [From the hat. fodio, fossum, to "dig."] A depression
or sinus; literally, a ditch.

Fo'vea Centralis. [Lat.] Central depression.

Fun'dus. [Lat.] The base or bottom of any organ which has an external
opening.

Fun'giform. [From the Lat. fungus, a " mushroom," and forma, " form."]
Having the shape of a mushroom.

Funic'ulus. [Dim. of Lat. funis, a " rope."] A little cord, or bundle of
aggregated fibres.

Fu'siform. [From the Lat. /us«s, a "spindle," and /orma, "form."] Spin-
dle-shaped.

Ganglia, pi. of Ganglion. [From the Gr. gagglion, a " knot."] A knot-VikQ
arrangement of nervous matter in the course of a nerve.

Gas'tric. [From the Gr. gaster, the "stomach."] Pertaining to the stomach.

Gastrocne'mius. [From the Gr. gaster, the "belly," and kneme, the "leg."]
The belly-shaped muscle of the leg.

Genioglos'sus. [From the Gr. geneion, the " chin," and glossa, the " tongue."]
A muscle connected with the chin and tongue.

Ginglymus. [From the Gr. gigglymos, a "hinge."] A hinge-]omt.

Gladi'olus. [Dim. of Lat. gladius, a "sword."] The middle piece of the
sternum.

Glair'y. [From the Lat. clarus, "clear"; Fr. clair-l Like the c^ear white
part of an egg.

Gle'noid. [From the Gr. glene, a "cavity," and eidos, "form," "resem-
blance."] A name given to a shallow cavity.

Glomer'ulus. [Dim. of Lat. glomus, a " clue of thread," or " ball."] A
botanical term signifying a small, dense, roundish cluster : a terra
applied to the fta^Mike tuft of vessels in capsules of the kidneys.

Glos'so-pharynge'al. [From the Gr. glossa, the " tongue," and pharygx, the
"pharynx."] Belonging to the tongue and pharynx.

Glot'tis. [Gr. the " mouthpiece of a flute."] The aperture of the larynx.

260 GLOSSARY.

Glute'i, pi. of Glute'us. [From the Gr. gloutoi, the " buttocks."] The mus-
cles forming the buttocks.

Gly'cogen. Literally, producing glucose. Animal starch found in liver,
which may be changed into glucose.

Glyco'suria. [From the Gr. glukus, " sweet," and ouron, " urine."] A con-
dition in which an abnormal amount of sugar is present in the
tirine.

Graafian Fol'licles, or Ves'icles. A term applied to the hollow bodies in
tlie ovaries, containing the ova.

Gramme. [From the Gr. gramma^ The unit of weight of the Metric
System. It is equivalent to 15.43 grains Troy.

Gus'tatory. [From the Lat. gusto, gustatuni, to " taste."] Belonging to the
sense of taste.

Haemoglo'bin. [From the Gr. haima, "blood," and Lat. globus, a "globe,"
or "globule."] A complex substance which forms the principal part of
the blood-globules, or red corpuscles of the blood.

Haemorrhoi'dal. [From the Gr. haima, "blood," and rheo, to "flow."] Per-
taining to haemorrhoids, small tumours of the rectum, which frequently
bleed.

Haver'sian Canals. Canals in the bone, so called from their discoverer, Dr.
Clopton Havers.

Hepat'ic. [From the Gr. hepar, hepatos, the "liver."] Pertaining to the
lioer.

Hi'lum, sometimes written Hi'lus. [Lat.] A small fissure, notch, or depres-
sion. A term applied to the concave part of the kidney.

Homoge'neous. [From the Gr. homos, " the same," and genos, " kind."] Of
the same kind or quality throughout ; uniform in natui'e, — the reverse
of heterogeneous.

Hu'merus. [Lat. tlie "shoulder."] The arm-bone which concurs in form-
ing the shoulder.

Hj^ aline. [From the Gr. hyalos, "glass."] Glass-\\ke, resembling glass in
transparency.

Hjr'drogen. An elementary gaseous substance, which in combination with
oxygen produces water, II2O.

Hy'oid. [From the Gr. letter v, and eidos, " form," " resemblance."] The
bone at the root of the tongue, shaped like the Greek letter v. '

Hypermetro'pia. [From the Gr. hyper, " over," " beyond," metron, " measure,"
and dps, the " eye."] Far-sightedness.

Hyper'trophy. [From the Gr. hyper, " over," and trophe, " nourishment."]
Excessive growth ; thickening or enlargement of any part or organ.

Hj^poblast. [From the Gr. hypo, " under," and blastos, a " sprout " or
" germ."] The internal or wider layer of the germinal membrane.

Hypochon'driac. [From the Gr. hyjw, " under," and chondros, a " carti-
lage."] A term applied to the region of abdomen under the cai-tilages
of the false ribs.

Hypoglos'sal. [From the Gr. hypo, " under, " and glossa, the " tongue."] A
name given to a nerve which terminates under the tongue.

GLOSSARY. 261

ireum. [From the Gr. eileo, to " twist."] The longest twisting portion of

tlie small intestine.
Il'iac. Pertaining to the ilium.
irium, pi. Il'ia. [From the Gr. eileo, to " twist."] The upper part of the

OS innominatum ; the haunch-bone ; perhaps so called because the crest

of the bone turns or twists upon itself.
Infundib'ula. [Lat. pi. of infundibulum, a "funnel."] FMnne^shaped canals.
In'guinal. [From the Lat. inguen, inguinis, the " groin."] Pertaining to

the groin.
Inos'culate. [From the Lat. in, "into," and osculum, a "little mouth."] To

unite, to open into each other.
Insaliva'tion. The process of mixing the saliva with the food in the act of

mastication.
In'sulate. [From the Lat. insula, an " island."] To isolate or separate from

surroundings.
Intercel'lular. Lying letween cells.

Interlob'ular. That which lies between the lobules of any organ.
Inter' stice. [From the Lat. inter, "between," and sto or sisto, to "stand."]

The space which stands between things ; any space or interval between

parts or organs.
Intersti'tial. Pertaining to or containing interstices.
Intralob'ular. That which lies within the lobules of any organ.
I'ris. [Lat. the "rainbow."] The coloured membrane suspended behind

the cornea of the eye. It receives its name from the variety of its

colours.
Is'chium. [From the Gr. ischtio, to " support."] The lower portion of the

OS innominatum; that upon which the body is supported in a sitting

posture.

Jeju'num. [From the Lat. jejunus, "fasting," "empty."] The part of the
small intestine comprised between the duodenum and ileum. It has
been so called because it is almost always found empty after death.

Ju'gular. [From the Lat. jugulum, the " throat."] Pertaining to the throat.

Kataboric. [From the Gr. kataballo, to "throw down."] Pertaining to
katabolism, the process by means of which the more complex elements
are rendered more simple and less complex. The opposite of anabolism.

Lach'rymal. [From the Lat. lachryma, a " tear."] Belonging to the tears.

Lac'tation. [From the Lat. lac, lactis, "milk."] The period of giving 7nilk.

Lac'teal. A term applied to the lymphatic vessels in the intestines which
absorb the milk-like fluid, the chyle, from the intestines.

Lac'tic Acid. An acid obtained from sour 7nilk.

Lacu'na, pi. Lacu'nas. [Lat. a "cavity," an "opening."] A little hollow
space.

Lambdoi'dal. [From the Gr. letter A (Lambda), and eidos, "form," '^ resem-
blance."] Resembling the Gr. letter A.

Lamel'la, pi. Lamellae. [Lat.] A thin plate or layer.

Lar'ynx. The upper part of the air passage, between the trachea and the
base of the tongue.

262 GLOSSARY.

Latis'simus Dor'si. [Lat. superlative of latftx, "broad," "wide," and dorsum,
the " back."] The tvidest muscle of the back.

Lec'ithin. [From the Gr. lekitJios, the " yellow of egg."] A complex, fatty-
substance found in the brain ; in the 7/olk of eggs.

Leu'cocyte. [From the Gr. leukos, "white," and kytos, a "cell."] A term
used to denote the white or pale corpuscles in the blood and lymph.

Lig'ament. [From the Lat. ligo, liffatum, to "bind."] Anything that binds
or unites.

Lin'ea Alba. [Lat.] The ichite line formed by the crossing of the apo-
neurotic fibres in the middle line of the abdomen.

Lin'ea Ilio-pectine'a. [Lat.] A line forming the brim of the pelvis, so
named from subjacent bone and muscle.

Litre. [From the Gr. litra.'] The unit of the measure of capacity of the
Metric System. It is equivalent to 33.81 fluid ounces, United States
pharmacopeia, and 35.196 imperial fluid ounces, British pharmacopeia.

Lob'ule. [From the dim. of Lat. lobus, a " lobe."] A small lobe.

Lum'bar. [From the Lat. lumbus, the " loin."] Pertaining to the loins.

Lymph. [From the Lat. li/mpha, " water."] A colourless fluid, resembling
ivater in appearance.

Lymphat'ic. Pertaining to lymph ; a vessel or tube containing lymph.

Lymphoid. [From the Lat. lympha, " water," and Gr. eidos, " form," " re-
semblance."] Having resemblance to lymph.

Mac'ula Lute'a. [Lat.] Yellow spot.

Ma'lar. [From the Lat. mala, the "cheek."] Pei'taining to the cheek.

Malle'olus, pi. Malle'oli. [Dim. of Lat. malleus, a "hammer."] A name
given to the pointed iirojections formed by the bones of the leg at the
ankle-joint.

Malpig'hian Bod'ies. [So called in honor of Malpighi, a celebrated Italian
anatomist.] A term applied to small bodies or corpuscles found in the
kidney and spleen.

Manu'brium. [Lat. a "haft," a "handle."] Name given to the upper por-
tion of the breast bone.

Mar'garin. One of the three chief constituents of fat.

Mas'seter. [From the Gr. massaomai, to " chew."] One of the muscles of
mastication.

Mas'toid. [From the Gr. maslos, the "breast," and eidos, "form," "resem-
blance."] Shaped like the breast.

Ma'trix. [Lat.] The womb. Producing or containing substance.

Max'illary. [From the Lat. maa;i7/a, a " jaw."] Pertaining to the maxillcc
or jaws.

Mea'tus. [From the Lat. 7neo, meatum, to "pass."] A passage or
canal.

Medul'la Oblonga'ta. [Lat.] The " oblong marrow " ; that portion of the
brain which lies within the skull, upon the basilar process of the occip-
ital bone.

Meibo'mian. A term applied to the small glands between the conjunctiva
and tarsal cartilages, discovered by Meibomius.

GLOSSAEY. 263

Mes'entery. [From the Gr. mesos, "middle," and enteron, the "intestine."]
A duplicature of the peritoneum covering the small intestine, which
occupies the middle or centre of abdominal cavity.

Mes'oblast. [From the Gr. mesos, " middle," and blastos, a " germ " or
" sprout."] The middle layer of the germinal membrane.

Mesocolon. A duplicature of the peritoneum covering the colon.

Metab'olism. [From the Gr. metabole, " change."] The changes taking
place in cells, whereby they become more complex and contain more
force, or less complex and contain less force. The former is construc-
tive metabolism, or anabolism ; the latter, destructive metabolism, or
katabolism.

Metacar'pus. [From the Gr. meta, " after," and karpos, the " wrist."] The
part of the hand comprised between the icrist and fingers.

Metatar'sus. [From the Gr. meta, " after," and tarsos, tlie " instej)."] That
part of the foot comprised between the instep and toes.

Metre. [From the Gr. metron, a " measure."] The primary unit of the
Metric System. The measure of length from which the units of weiglit
and capacity are derived. It is equivalent to 39.37 inches. A milli-
metre is one-tliousandth part of a metre.

Mi'tral. Resembling a mitre.

Mo'lar. [From the Lat. mola, a "mill."] A term applied to the teeth which
bruise or grind the food.

Molec'ular. Pertaining to molecules.

Mol'ecule. [From the dim. of Lat. moles, a "mass."] The smallest quantity
into which the mass of any substance can physically be divided. A
molecule may be chemically separated into two or more atoms.

Monox'ide. [From the Gr. monos, " single," and " oxide."] A compound
containing one atom only of oxygen combined with one of base, or
metal.

Mo'tor Oc'uli. [Lat.] INIover of the eye.

Moto'rial. That which causes movement.

Mu'cin. The chief constituent of mucus.

Mu'cous. A term applied to those tissues that secrete mucus.

Myocar'dium. [From the Gr. mys, niyos, a "muscle," and kardia, the "heart."]
The muscular structure of the heart.

Myo'pia. [From the Gr. myo, to " contract," and ops, the " eye."] Near-
sightedness.

My'osin. Chief proteid substance of muscle.

Na'ris, pi. Na'res. [Lat.] A nostril.

Neurilem'ma. [From the Gr. neuron, a " nerve," and lemma, a " coat " or

" covering."] Xerve-sheath.
Wi'trogen. A colourless gas forming nearly four-fifths of the atmosphere : the

diluent of the oxygen in the air. Literally, that which generates nitre.
Nucle'olus, pi. Nucle'oli. [Dim. of Lat. nucleus, a "kernel."] A smaller

nucleus witliin the nucleus.
Nu'cleus, pi. Nu'clei. [Lat. a " kernel."] A minute vesicle embedded in

the cell protoplasm (cytoplasm).

264 GLOSSAEY.

Occipi'tal. [From the Lat. occiput, occipitis, the "back of the head."] Per-
taining to the occiput, the back pai't of the head.

Odon'toid. [From the Gr. odons, odontos, a " tooth," and eidos, " form," " re-
semblance."] Tooth-like.

(Ede'ma. [From the Gr. oideo, to " swell."] A swelling from effusion of
serous fluid into the areolar tissue.

(Esoph'agus. [Gr. oisophagos, from oio, (f ut.) oiso, to " carry," and phagema,
"food."] The gullet.

Olec'ranon. [From the Gr. olene, the " elbow," and kranon, the " head."]
The head of the elhow.

O'lein. [From the Lat. oleum, " oil."] One of the three chief constituents
of fat. Oil (^oleuin) signifies literally, juice of the olive (l^at. olea).

Olfac'tory. [From the Lat. olfacio, olfactum, to " smell."] Belonging to the
sense of smell.

Omen'tum. [Lat. "entrails."] A duplicature of the peritoneum with more
or less fat interposed.

Ophthal'mic. [From the Gr. ophthalmos, the " eye."] Belonging to the eye.

Op'tic. [From the Gr. opto, to "see."] That which relates to sight.

O'ra Serra'ta. [Lat.] Serrated border.

Orbicula'ris. [From dim. of Lat. orhis, an "orb" or "circle."] Name of the
circular muscles.

Or'bitaL [From the Lat. orbita, a "track," "rut of a wheel."] Pertaining
to the 07-bit, the bony cavity in which the eyeball is suspended.

Os, pi. Ora. [Lat.] A mouth.

Os, pi. Ossa. [Lat.] A bone.

Osmo'sis. [From the Gr. usmos, "impulsion."] Diffusion of liquids through
membranes.

Os'sa Innomina'ta, pi. of Os Innomina'tum. [Lat.] " Unnamed bones." The
irregular bones of the pelvis, unnamed on account of their non-resemblance
to any known object.

Os'teoblasts. [From the Gr. osteon, a " bone," and blastos, a " germ " or
"sprout.*'] The germinal cells deposited in the development of Jione.

O'toliths. [From the Gr. ovs, the "ear," and lithos, a "stone."] Particles
of calcium carbonate and phosphate found in the internal ear.

O'vum, pi. O'va. [Lat. an " egg."] The human germ-cell.

Oxida'tion. The action of oxidizing a body ; that is, combining it with oxy-
gen, the result of which combination is an oxide.

Ox'ygen. A tasteless, odourless, colourless gas, forming part of the air,
water, etc., and supporting life and combustion.

Pal'mitin. A solid, crystallizable substance of fat, found in the nervous tissue.

Pal'pebra, pi. Pal'pebrae. [Lat.] The eyelid.

Pan'creas. A compound secreting gland ; one of the accessory organs of

nutrition. The sweetbread of animals.
Papil'lae. [Lat. pi. of papilla, a "nipple," a "pimple."] Minute eminences

on various surfaces of the body.
Paraglob'ulin. A. proteid substance of the blood plasma.
Pari'etaL [From the Lat. paries, parietis, a "wall."] Pertaining to a ivalL

GLOSSARY. 265

Parot'id. [From the Gr. para, " near," and ovs, otos, the " ear."] The large

salivary gland under the ear.
Parturi'tion. [From the Lat. parturio, 2^a7-turitum, to " bring forth."] The

act of bringing forth, of giving birth to young.
Patel'la. [Lat. "a little dish."] A small, io«i'/-shaped bone; the knee-pan.
Pec'toral. [From the Lat. pectus, pectoris, the "breast."] Pertaining to the

breast or chest.
Ped'icle. [From the dim. of Lat. pes, pedis, a " foot."] A stalk.
Pel' vie. [From the Lat. pelvis, a "basin."] Pertaining to the pelvis, the

basin or bony cavity forming the lower part of the abdomen.
Pep'sin. [From the Gr. pepto, to " digest."] A ferment principle in gastric

juice, having power to convert proteids into peptones.
Pep'tone. [From the Gr. pepto, to " digest."] A term applied to proteid

material digested by the action of the digestive juices.
Pericar'dium. [From the Gr. peri, " about," " around," and kardia, the

" heart."] The serous membrane covering the heart.
Perichon'drium. [From the Gr. joen, "about," "around," and chondros, a

" cartilage."] The serous membrane covering the cartilages.
Per'ilymph. [From the Gr. peri, "about," "around," and the Lat. hjmpha,

" water."] The fluid in the osseous, and surrounding the membranous,

labyrinth of the ear.
Perios'teum. [From the Gr. peri, "about," "around," and osteon, a "bone."]

The membrane covering the bones.
Periph'eral. [From the Gr. peri, " about," " around," and phero, to " bear,"]

Pertaining to the periphery or circumference ; that which is away from

the centre and towards the circumference.
Peristal'sis. [From the Gr. peristello, to " surround," to " compress."]

Peristaltic action. A term applied to the peculiar movement of the

intestines, like that of a worm in its progress, by which they gradually

propel their contents.
Peritone'um. [From the Gr. periteino, to " stretch around," to " stretch all

over."] The serous membrane lining the walls and covering the con-
tents of the abdomen.
Perone'al. [From the Gtv. perone, the "fibula."] Pertaining to the fbula ;

a term applied to muscles or vessels in relation to the fbula.
Pe'trous. [From the Gr. petrd, a "rock."] Having the hardness of rock.
Pey'er's Glands. The clustered glands in the intestines, so named after the

anatomist, Peyer, who well described them.
Phalan'ges. [Lat. pi. of phalanx, a " closely serried array of soldiers."] A

name given to the small bones forming the fingers and toes, because

placed alongside one another like a phalanx.
Phar'ynx. [From the Gr. pharao, to " plough," to " cleave."] The cleft or

cavity forming the upper part of the gullet.
Phren'ic. [From the Gr. phren, the " diaphragm."] Pertaining to the dia-
phragm.
Pi'a Ma'ter. [Lat. pia (fern.), "tender," "delicate," and mater, "mother."]

The most internal of the three membranes of the brain. See Dura

Mater.

266 GLOSSAEY.

Pig'ment. [From the hat. pigmentum, "paint," "colour."] Colouring matter.

Pin'na. [Lat. a " feather " or " wing."] External cartilaginous flap of the
ear.

Placen'ta. [Lat. a " thin, flat cake."] A Jlat, circular, vascular substance
wliich forms the organ of nutrition for the fcetus in utero.

Plan'tar. [From the Lat. planta, " the sole of the foot."] Pertaining to the
sole of the foot.

Plas'ma. [From the Gr. plas.io, " to form."] A tenacious plastic fluid con-
taining the coagulating portion of the blood; that in which the blood-
corpuscles float; the liquor sanguinis.

Pleu'ra. [Gr. the " side."] A serous membrane divided into two portions,
lining the right and left cavities of the chest, and reflected over each
lung.

Plex'us. [From the Lat. plecto, plexum, to " knit " or " weave."] A netivork
of nerves or veins.

Pneumogas'tric. [From the Gr. pneumun, a "lung," and gaster, the "stom-
ach."] Pertaining to the hnigs and stomach.

Polyhe'dral. [From the Gr. puhjs, " many," and hedra, a " base," a " side."]
Many-sided.

Pons Varo'lii. [Lat.] " Bridge of Varolius." The white fibres which form
a bridge connecting the different parts of the brain, first described by
Varolius.

Poplite'al. [From the Lat. poples, poplitis, the " ham," the " back part of the
knee."] The space behind the knee-joint is called the popliteal space.

Prismat'ic. Resembling a prism, which, in optics, is a solid, glass, triangular-
shaped body.

Prona'tion. [From the l^at. pronus, "inclined forwards."] The turning of
the hand with the jialm forwards.

Prona'tor. The group of muscles which turn the hand palm forwards.

Pro'teids. A general term for the albuminoid constituents of the body.

Pro'toplasm. [From the Gr. protos, "first," a.ud plasso, to "form."] AJirst-
f armed organized substance ; primitive organic cell matter.

Pseudostom'ata. [From the Gr. j^seudes, " false," and stoma, stomatos, a
" mouth."] False openings.

Pter'ygoid. [From the Gr. j)teron, a "wing," and eidos, "form," " resem-
bhuice."] Wing-like.

Pty'alin. [From the Gr. ptyalon, "saliva."] A ferment principle in saliva,
having power to convert starch into sugar.

Pu'bes, gen. Pu'bis. [Lat.] The external part of the generative region ;
the portion of the os innominatum forming the front of the pelvis.

Pul'monary. [From the Lat. puhno, Tpil. pulmones, the "lungs."] Relating
to the lungs.

Pylor'ic. Pertaining to the pylorus.

Pylor'us. [From the Gr. pi/le, a " gate " or " entrance," and owos, a
"guard."] The lower orifice of the stomach, furnished with a circular
valve which closes during stomach digestion.
Pyrex'ia. [From the Gr. pj/resso, (fut.) pip-exo, to "have a fever."] Eleva-
tion of temjierature ; fever.

GLOSSARY. 267

Quad'riceps. [From the Lat. (jualuor, " four," and caput, the " head."] A
term applied to the extensor muscle of the leg, having four heads or
parts.

Ra'dius. [Lat. a " rod," the " spoke of a wheel."] The outer bone of the

fore-arm, so called from its shape.
Rale. [From the Fr. rdler, to "rattle in the throat."] A rattling, bubbling

sound attending the circulation of air in the lungs. Different from the

murmur produced in health.
Rec'tus. [Lat.] Straight.

Re'nal. [From the Lat. ren, rents, the " kidneys."] Pertaining to the kid-
neys.
Ren'nin. (Rennet.) The milk curdling enzyme which constitutes the active

principle of rennet.
Retic'ular. [From the Lat. reticulum, a "small net."] Resembling a small

net.
Ret'iform. [From the Lat. rete, a " net," and forma, " form."] Having the

form or structure of a net.
Ret'ina. [From the Lat. rete, a " net."] The most internal membrane of

the eye ; the expansion of the optic nerve.
Ri'ma Glot'tidis. [Lat. rima, a "chink" or "cleft."] The opening of the

glottis.
Ru'gSB. [Lat. pi. of ruga, a "wrinkle."] A term applied to the folds or

wrinkles in the mucous membrane, especially of the stomach and vagina.

Sa'crum. [Lat. neut. of sacer, " sacred."] The large triangular bone above
the coccyx, so named because it was supposed to protect the organs con-
tained in the pelvis, which were offered in sacrifice and considered
sacred.

Sag'ittal. [From the Lat. sagitta, an " arrow."] Arrow-shaped.

Sal'ivary. Pertaining to the saliva, the fluid secreted by the glands of the
mouth.

Saphe'nous. [From the Gr. sapJics, " manifest."] A name given to the two
large superficial veins of the lower limKs.

Saponifica'tion. [From the Lat. sapo, saponis, "soap," and facio, to "make."]
Conversion into soap.

Sarcolem'ma. [From the Gr. sa7-x, sarkos, "flesh," and lemma, a "cover-
ing."] The covering of the individual muscle fibrils.

Sar'cous. [From the Gr. sarx, sarkos, "flesh."] Fleshy, belonging to fesh.

Sarto'rius. [From the Lat. sartor, a " tailor."] The name of the muscle
used in crossing the legs, as a tailor does when he sits and sews.

Scap'ula. [Lat.] The shoulder-blade.

Sclerot'ic. [Lat. scleroticus, from Gr. skleroo, to " harden."] Hard, tough.

Seba'ceous. A term applied to glands secreting sebum.

Se'bum or Se'vum. [Lat. sevum, "suet."] A fatty secretion resembling
suet, which lubricates the surface of tlie skin.

Semilu'nar. [From the Lat. semis, " half," and luna, the " moon."] Having
the shape of a halfynoon.

268 GLOSSARY.

Se'rous. Having the nature of serum.

Se'rum. [Lat.] The watery fluid separated from the blood after coagula-
tion.
Ses'amoid. [From the Gr. sesamon, a "seed of the sesamuni," and eidos,
"form," "resemblance."] Resembling a grain of sesamum. A term
applied to the small bones situate in the substance of tendons, near
certain joints.
Sig'moid. From the Gr. letter 5, sigma, and eidos, " form," " resemblance."]

Curved like the letter S.
Sole'us. [From the Lat. solea, a "sandal."] A name given to a muscle

shaped like the sole of a shoe.
Specific Grav'ity. The comparative density or gravity of one body con-
sidered in relation to another assumed as the standard. In measuring
the specific gravity of liquids or solids, water is usually taken as the
standard of comparison, being reckoned as a unit.
Sphe'noid. [From the Gr. sphen, a "wedge," and eidos, "form," "resem-
blance."] Like a wedge.
Sphinc'ter. [From the Gr. sphiggo, to "bind tight," to "close."] A circu-
lar muscle which contracts the aperture to which it is attached.
Squa'mous. [From the Lat. squama, a " scale."] Scale-Wke.
Sta'sis. [From the Gr. stao, to " stop."] Stagnation of the blood current.
Ste'arin. One of the three chief constituents of fat.
Ster'num. [Lat.] The breast-bone.

Stim'ulus, pi. Stim'uli. [Lat. a "goad."] Anything that excites to action.
Sto'ma, pi. Stom'ata. [From the Gr. stoma, stomatos, a " mouth."] A

mouth; a small opening.
Strat'ified. [From the Lat. stratum, a " layer," and facio, to " make."]

Formed or composed of strata or layers.
Stri'ated. [From the Lat. strio, striatum, to "make furrows."] That which

has strice, furrows or lines.
Stro'ma. [From the Gr. stroma, a " bed."] The foundation or hed tissue of

an organ.
Styloglos'sus. [From the Gr. stylos, a " pillar," and glussa, the " tongue."]
A muscle connected with a, pointed style-like process of the temporal bone
and the tongue.
Subcla'vian. Under the clavicle.
Subcuta'neous. [From the Lat. sub, "under," and cutis, the "skin."] Under

the skin.
Sudoriferous. [From the Lat. sudor, " sweat," and fero, to " carry," to

" bear."] A term applied to the glands secreting sweat.
Supina'tion. [From the Lat. supino, supinatum, to "bend backwards," to
" place on the back."] The turning of the hand with the palm back-
wards, the posterior surface of the hand being supine.
Su'pinators. The muscles which turn the hand with the palm backwards.
Suprare'nal. [From the Lat. sw^cr, "over," and ren, renis, the "kidney."]

Above the kidney.
Su'ture. [From the Lat. suo, sutum, to "sew together."] That which is
sewn together, a seam; the seam uniting bones of the skull.

GLOSSARY. 269

Sym'physis. [From the Gr. syn, "together," and phyo, to "produce," to

"grow."] A union of bones, usually of symmetrical bones in the

median line, as the pubic bones and bones of the jaw.
Synarthro'sis. [From the Gr. syn, "together," and arthron, a "joint."] A

form of articulation in which the bones are immovably joined together.
Synchondro'sis. [From the Gr. syn, " together," and chondros, " cartilage."]

Union by an intervening growth of cartilage.
Syndosmo'sis. [From the G\\ syn, "together," and desmos, a "ligament."]

Union by ligaments.
Syno'via. [Supposed to be from the Gr. syn, " together," implying union

or close resemblance, and oon, an " Qg%"'\ A fluid resembling the white

of an egg.
Syno'vial. Pertaining to synovia.
Syn'tonin. [From the Gr. synteino, to "stretch," to "draw," referring to

the peculiar property of muscular fibre.] A name given by Lehmann

to a substance obtained from muscular fibre by the action of dilute

muriatic acid.
Sys'tole. [From the Gr. systello, to " draw together," to " contract."] The

contraction of the heart.

Tar'sus. [From the Gr. tarsos, the " instep."] The instep : the cartilage of
the eyelid.

Ten'do Achil'lis. [Lat.] "Tendon of Achilles." The tendon attached to
the heel, so named because Achilles is supposed to have been held by the
heel when his mother dipped him in the river Styx to render him invul-
nerable.

Thorac'ic. [From the Gr. thorax, a " breastplate," the " breast."] Pertain-
ing to the thorax.

Thy'roid. [From the Gr. thyreos, an "oblong shield," and eidos, "form,"
" resemblance."] Resembling a shield. A name given to an opening in
the ossa innominata : to the piece of cartilage forming the anterior
prominence of the larynx : to the gland placed in front of the larynx.

Tib'ia. [Lat. a "flute" or "pipe."] The shin-bone, called tibia, from its
fancied resemblance to a reed-pipe.

Tibia'lis Anti'cus. [Lat.] The muscle situate at the anterior part of the
tibia.

Tibia'lis Pos'ticus. [Lat.] The muscle situate at the posterior part of the
tibia.

Tone. [Gr. tonos, from teino, to " stretch."] A distinct sound. The state
of tension proper to each tissue. A term used to express the normal
excitability, strength, and activity of the various organs and functions
of the body in a state of health.

Trabec'ulae. [Lat. pi. of trabecula, a "little beam."] A term applied to
prolongations of fibrous membranes which form septa, or partitions.

Tra'chea. [Lat.] The windpipe.

Transversa'lis. [Lat. from trans, "across," and verto, versum, to "turn," to
" direct."] A term applied to a muscle which runs in a transverse direc-
tion.

270 GLOSSARY.

Trape'zius. A name given to the two upper superficial muscles of the back,

because together they resemble a trapezium, or diamond-shaped quad-
rangle.
Tri'ceps. [From the Lat. tres, " three," and caput, the " head."] A term

applied to a muscle having a triple origin, or three heads.
Tri'cuspid. [From the Lat. tres, "three," and cuspis, cuspidis, a "point."]

Having three points.
Trochan'ter. [From the Gr. trochao, to " turn," to " revolve."] Name given

to two projections on the upper extremities of the femur, which give

attachment to the rotator muscles of the thigh.
Tryp'sin. The ferment principle in pancreatic juice which converts proteid

material into peptones.
Tuberos'ity. [From the Lat. tuber, tuheris, a, "swelling."] A protuberance.
Tur'binated. [Lat. turbinatus, from turbo, tm-binis, a " top."] Formed like

a top; a name given to the bones in the outer wall of the nasal

fossie.
Tym'panum. [From the Gr. tympanon, a " drum."] The drum or hollow

part of the middle ear.

Ul'na. [Lat. the "elbow."] The inner bone of the fore-arm, the olecranon

process of which forms the elbow.
Umbil'icus. [Lat. the "navel."] Around cicatrix or scar in the median

line of the abdomen.
TJ'rea. [From the Lat. urina, "urine."] Chief solid constituent of urine.

Nitrogenous product of tissue decomposition.
Ure'ter. [From the Gr. oureu, to " pass urine."] The tube through which

the urine is conveyed from the kidney to the bladder.
Ureth'ra. [From the Gr. owed, to " pass urine."] The canal throiigh which

the urine is conveyed from the bladder to the meatus urinarius.
U'vula. [Dim. of Lat. uva, a "grape."] The small, elongated, fleshy body

hanging from the soft palate.

Vag'inaL [From the Lat. vagina, a " sheath."] Sheath-Vike.

Val'vulae Conniven'tes. [Lat.] A name given to transverse folds of the
mucous membrane in the small intestine.

Vas'a Vaso'rum. [Lat.] " The vessels of the vessels." The small blood-
vessels which supply the walls of the larger hlood-vessels with blood.

Vas'cular. [From the Lat. vasculum, a "little vessel."] Relating to vessels;
full of vessels.

Va'so-constric'tor. [From the Lat. vas, a " vessel," and constrincjuo, to " con-
strict."] An agent which brings about con:<triction of blood-i'e.s\se/.v ; spe-
citically a nerve when stimulated, or a drug which acts in this way when
administered.

Va'so-dila'tor. [From the Lat. vas, a " vessel," and dilator, a " dilator."]
An agent which brings about dilatation of h\ood-vessels.

Ve'nae Ca'vae, pi. of Ve'na Ca'va. [Lat.] " Hollow veins." A name given
to the two great veins of the body which meet at the right auricle of the
heart.

GLOSSAEY. 271

Ve'nae Com'ites. [Lat.] " Attendant veins." Veins which accompany the
arteries.

Ven'tral. [From the Lat. venter, ventris, the "belly."] Belonging to the
belly cavity.

Ven'tricle. [From the dim. of Lat. venter, the "belly."] A small cavity.

Ver'miform. [From the Lat. vermis, a "worm," and forma, "form."] Worm-
shaped.

Ver'nix Caseo'sa. [Lat.] "Cheesy varnish." The fatty varnish found on
the new-born infant, which is secreted by the sebaceous glands of the
skin.

Ver'tebrae, pi. of Ver'tebra. [Lat. from verto, to " turn."] The bones of the
spine.

Vil'li. [Lat. pi. of villus, "shaggy hair."] The conical projections on the
valvulte conniventes, making the mucous membrane look shaggy.

Vis'cera. [Lat.] The internal organs of the body.

Vitel'line. [From the Lat. vitellus, the "yolk of an egg."] A term applied
to the yolk membrane.

Vitel'lus. [Lat. from vita, " life."] The yolk of an egg.

Vit'reous. [From the Lat. vitrum, " glass."] G^Zass-like. A name applied to
the transparent, jelly-like substance which fills the back part of the eye-
ball behind the crystalline lens.

Vo'mer. [Lat. a "ploughshare."] The thin plate of bone shaped some-
what like & ploughshare which separates the nostrils.

Vul'va. The external female genitals.

Zo'na Pellu'cida. [Lat.] " Pellucid zone." The broad, transparent ring
which surrounds the yolk in the centre of the ovum.

INDEX.

A.

Abdomen, divisions of, 176.

Absorption, 197.

Adipose tissue, 17.

Adjustment of eye, how accomplished, 239.

Air, composition of, 160.

Albumin, 100.

Alimentary canal, 175.

Alimentation, 164.

Amoeboid movement, 5, 99.

Aorta, 116.

Aponeuroses, 16, 62.

Arachnoid membrane, 85.

Arterial distribution, plan of, 129; some
features of, 131.

Arterial tension, 133.

Arteries, of head and neck, 118; of lower
limb, 123; structure of. 111; table of,
129; of upper limb, 119.

Artery, innominate, 116; pulmonary, 128.

Articulations, freely movable, 49; im-
movable, 48 ; slightly movable, 48.

Atoms, 3.

Auditory canal, 228.

Axones, 74.

B.

Bile, 188, 194.

Bladder, 204.

Blood, the, 96; circulation of, 131; clot-
ting of, 100 ; functions of, 95, 102 ; gen-
eral composition of, 101 ; red corpuscles
of, 96 ; white corpuscles of, 98.

Blood-vessels, 95.

Body, chemical composition of, 172.

Bone, description of, 20; development of,
22 ; regeneration of, 22.

Bones, of cranium, 33; of face, 37; flat,
25 ; irregular, 25 ; long, 24 : of lower ex-
tremity, 28; short, 25; table of, 47; of
upper extremity, 25.

Brain, description of, 85.

Bread, composition of, 173.

Bursae, 51.

C.

Cajcum, 184.

Canal, alimentary, 175; auditory, 228;
central, of spinal cord, 81.

Canals, Haversian, 21.

Capillaries, 113.

Carbo-hydrates, 170.

Carbonic dioxide, excretion of, 161; pro-
portion of, in air, 160.

Cavity, buccal, 177; dorsal, 2; pelvic, 45;
thoracic, 42; ventral, 2.

Cell, the, 3.

Cerebellum, 86, 94.

Cerebrum, 87, 94.

Chordae tendinse, 107.

Choroid of the eye, 235.

Chyle, 144.

Cilia, 11.

Circulation, arterial, 131; capillary, 134;
fffital, 1.37; general, 131; portal, 125;
pulmonary, 131 ; summary of, 137.

Coccyx, 41.

Colon, 184.

Conjunctiva, 240.

Connective tissue proper, 14,

Connective tissues, classification of, 13.

Contractility, muscular, 53, 54.

Cord, spinal, 80.

Corpuscles, tactile, 214, 223; red, 96;
white, 98.

Cranial nerves, 88.

Cranium, 43.

Crystalline lens, 238.

Cutis vera, 213.

Cytoplasm, 3, 74.

D.

Dendrones, 74.

Development of blood-vessels and cor-
puscles, 140 ; bone, 22 ; muscular tissue^
.56.

Diaphragm, 66.

Diastole, 109.

Diet, 174.

273

274

INDEX.

Digestion, 191.

Digestive juices, bile, 194; gastric, 193;

intestinal, 195; pancreatic, 195; saliva,

192.
Diploe, 25.
Duct, cystic, 190; hepatic, 189; nasal, 242;

pancreatic, 185; right lymphatic, 143;

thoracic, 143.
Dura mater, 85.

E.

Ear, the, 228.

Elastic tissue, 16.

Elimination, 202.

Endothelium, 111.

Enzyme, 191.

Epidermis, 213.

Epithelium, 9.

Equilibrium, sense of, 232.

Eustachian tube, 180, 229.

Eye, the, 233; choroid coat of, 235; crys-
talline lens of, 238; sclerotic coat of,
233 ; refracting media of, 237 ; retina of,
235.

Eyebrows, 240.

Eyelids, 240.

F.

Fallopian tubes, 243, 247.

FasciiB, 10, 71.

Fats, 170 ; absorption of, 198 ; digestion of,
195.

Feces, 19<;.

Fibres, non-striated muscular, 54; stri-
ated muscular, 53.

Fibrin, 100.

Fibrinogen, 100.

Fibro-cartilage, 18.

Fibrous tissue, 15.

Foetal circulation, 137.

Fontanelles, 44.

Food, 1(59.

Food-stuffs, classification of, 169.

Foramen, thyroid, 30; magnum, 33,

G.

Gall-bladder, 190.

Ganglia, 77; sympathetic, 78, 92 ; spinal,
83, 92.

Gastric juices 193.

Glands, lachrymal, 241; lymphatic, 146;
mammary, 2.50; Meibomian, 241; sali-
vary, 178; sebaceous, 216; secreting,
164; solitary, 148; sweat, 217.

Glottis, 1,52.

Glycogen, 198.

Gullet, 180.

H.

Hfenioglobin, 97.
Hairs, the, 215.

Hearing, sense of, 231.

Heart, beat of the, 108; cavities of the,
10(j; description of the, 103; sounds of
the, 110.

Heat, bodily, 219; distribution of, 220;
loss of, 219 ; production of, 219 ; regula-
tion of, 220.

Humours of the eye, 237.

Ileo-crecal valve, 184.
Inliammation, 136.
Insensible perspiration, 218.
Intestinal juice, 195.
Intestine, large, 184; small, 182.
Iris, 235.

Joints, classification of, 42 ; movements
of, 49, 50, 51 ; table of, 52.

Juice, gastric, 193; intestinal, 195; pan-
creatic, 195.

K.

Kidneys, blood-supply of, 206; position
of, 203 ; structure of, 205.

Labyrinth of ear, 230.

Lachrymal glands, 241.

Lacteals, 183, 198.

Larynx, 151.

Ligament, Poupart's, 64.

Ligamenta subflava, 16.

Ligaments, 15, 49; annular, 71; broad,
246; round, 246.

Light, 240.

Linea alba, 64.

Liver, the, 186.

Lungs, 155, 157.

Lymph, 143; functions of, 145; move-
ments of, 144.

Lymphatic glands, 146 ; vessels, 142.

Lymphatics, 141.

M.

Mammary glands, 250.

Marrow, 220.

^Mastication, 192.

ISIeat, composition of, 173.

Medulla oblongata, 85, 92.

Mcdullated nerve fibres, 76.

Meibomian glands, 241.

Membranes, mucous, 166; serous, 113;

synovial. 49, 51.
Metabolism, 4, 201.
Milk, composition of, 173, 251.
Mineral salts, 100, 171.

INDEX.

275

Molecules, 3.

Mouth, the, 177.

Muscles, action of abdominal, 64; attach-
ment of, 5(j ; of head and face, 58 ; of lower
extremity, G9 ; of neck and trunk, 61 ;
relation of nerves to, 71; table of, 72;
of upper extremity, 67.

Muscular tissue, description of, 53; de-
velopment of, 56 ; regeneration of, 56.

N.

Nails, the, 215.

Nares, anterior, 226 ; posterior, 227.

Nerves, afferent or sensory, 77 ; cranial, 88
degeneration and regeneration of, 84
description of, 76 ; efferent or motor, 77
spinal, 82; vaso-motor, 79.

Nervous system, divisions of, 75; physiol-
ogy of, iX).

Neurone, the, 74.

Nitrogenous waste, excretion of, 210.

Nose, the, 226.

Nucleus of cell, 3, 5.

O.

OEdema, 145.
(Esophagus, 150.
Ovaries, 247.
Ovum, 249.
Oxidation, 98, 161.

Oxygen, combination of, with haemo-
globin, 98, 161.

Plasma of the blood, 102.

Pleura, 114, 157.

Pons Varolii, 86, 92.

Pressure, atmospheric, 157; sense, 223.

Process, acromion, 26; alveolar, 38; an-
terior superior spinous, of ilium, 30;
odontoid, 40; olecranon, 27.

Processes of bone, 25.

Proteids, 169.

Protoplasm, 4.

Ptyalin, 192.

Pulse, the, 1.32.

Pylorus of stomach, ^81.

Pyramids of kidney, 205.

Pyrexia, 220.

R.

Receptacle of chyle, 143.

Rectum, 185.

Reflex action, 90.

Rennin, 193.

Respiration, 66, 151, 157; costal, 66;
diaphragmatic, 66; effect of, upon air
outside body, 159; effect of, upon air
within lungs, 158 ; effect of, upon blood,
161.

Respiratory movements, modified, 162.

Retina, 235.
Ribs, 43.

S.

Sacrum, 40.
Saliva, 192.
Salivary glands, 178.
Scarpa's triangle, 124.
Sebaceous glands, 178.
Secreting glands, 164.
Secretion, 194.
Sensation, common, 224.
Serous membranes, 113.
Sight, long and near, 239; sense of, 233.
Skeleton, the, 24.
Skin, the, 212.
Skull, 43.

Smell, sense of, 226.
Sound, 231.
Special senses, 222.

Sphincter muscle of bladder, 204; of rec-
tum, 185.
Spinal cord, 80, 92; nerves, 82.
Spiue, the, 39, 41.
Spleen, the, 149.
Stomach, 180.

Subnormal temperature, 221.
Succus entericus, 195.
Supra-renal capsules, 210.
Sutures, 48, 52.
Sweat-glands, 217.
Symphysis pubis, 30.
Synovia, 51.

System, sympathetic, 78.
Systole, 109.

Taste, sense of, 224.

Tears, 241.

Teeth, 178.

Temperature, blood, 96; of body, 219;
sense of, 224; subnormal, 221.

Tendons, 16.

Tension, arterial, 133.

Thorax, 42.

Tissue, adipose, 17; areolar, 14; carti-
laginous, 18; connective, proper, 14;
elastic, 16; epithelial, 8; fibrous, 15;
muscular, 53; nervous, 74; osseous, 20.

Tissues, classification of, 7.

Tongue, the, 178, 224.

Tonsils, 149.

Touch, sense of, 223.

Trachea, 153.

Tube, Eustachian, 180, 229 ; Fallopian, 243,
247.

Tympanum, 229.

Urea, 209.
Ureters, 203.
Urethra, 204.

U.

276

INDEX.

Urine, composition of, 209; excretion of ,
208 ; secretion of, 207.

Uterus, 243.

Uvula, 177.

V.

Vagina, 243.

Valves of heart, 106 ; in veins, 112.

Valvulse conniventes, 182.

Vascular system, 95.

Vein, portal, 125.

Veins, of head and neck, 126; of lower
limb, 127; pulmonary, 128; right and
left azygos, 127; structure of, 112; sys-
temic veins, 125 ; table of, 129 ; of upper
limb, 126.

VeuEB comites, 125.

Ventricles of the brain, 86; of the heart,

106, 107.
Vermiform appendix, 184.
Vertebrae, description of, 39, 40.
Villi, 168.
Vocal cords, 152.

W.

Waste products, 202.
Water, composition of, 171.

Z.

Zona pellucida, 249.

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JVORKS ON MEDICINE AND SURGERY

UNNA

The Histopathology of the Diseases
of the Skin. By Dr. F. G. Unna.

Translated fiom the German, with the
assistance of the Author, by NORMAN
Walker, M.D.,F.R.C.P. (Ed.), Assist-
ant Physician in Dermatology to the
Royal Infirmary, Edinburgh. With
double-colored Plate containing 19
Illustrations and 42 addhional Illustra-
tions in the text. 8vo. Cloth, pp.
xxvii + 1205. Price $ 10.50 ?iet.

VERWORN

General Physiology : An Outline of
the Science of Life. By Max Ver-
WORN, M.D., Ph.D., A.O., Professor
of Physiology in the Medical Faculty
of the University of Jena. Translated
from the Second German Edition and
edited by FREDERIC S. Lee, Ph.D.,
Adjunct Professor of Physiology in
Columbia University. With 285 Illus-
trations. 8vo. Cloth, pp. xvi + 615.
Price $ 4.00 net.
WARING

Manual of Operative Surgery. By H.

J. Waring, M.S., M.B., B.Sc. (Lond.),
F.R.C.S., Demonstrator of Operative
Surgery and Surgical Registrar, Late
Senior Demonstrator of Anatomy St.
Bartholomew's Hospital; Surgeon to the
Metropolitan- Hospital and Erasmus
Wilson Lecturer to the Royal College
of Surgeons, England. i2mo. Cloth.
Illustrated, pp. xxvi + 661.

Price $ 3.25 net.
WARING

Diseases of the Liver, Gall Bladder,
and Biliary System ; Their Pathology,
Diagnosis and Surgical Treatment.
By H. |. Waring, A-I.S., B.Sc. (Lond.),
F.R.C.S., Demonstrator of Operative
Surgery, and Senior Demonstrator of
Anatomy St. Bartholomew's Hospital,
etc. 8vo. Cloth. 58 Illustrations.
pp. xiv + 385. Price $ 3.75 net.

WARNER

Three Lectures on the Anatomy of
Movement. A Treatise on the Action
of Nerve-Centres and Modes of Growth.
Delivered at the Roval College of Sur-
geons of England. By Francis War-
ner, M.D. i2mo. Cloth. 18 Illus-
trations, pp. xiv -f- 135.

Price 75 cents net.

By the Same Author

The Nervous System of the Child :
Its Growth and Health in Education.
Bv Francis WarNf.r, M.D. (Lond.),
FlR.C.P., F.R.C.S. (Eng.), Physician to
and Lecturer at the London Hospital,
etc. i2mo. Cloth, pp. xvii + 233.

Price $ i.oo net.

The Study of Children and Their
School Training. By Francis War-
ner, M.D. i2mo. Cloth. pp.
xix + 264. Price $ i.oo net.

WATSON

Practical Handbook of the Diseases
of the Eye. By D. Chalmers Wat-
son, M.B., CM., Ophthalmic Surgeon,
Marshall Street Dispensary, Edin-
burgh ; late Clinical Assistant, Oph-
thalmological Department. Royal
Infirmary, Edinburgh. With 9 colored
Plates and 24 Illustrations in the text.
l2mo. Cloth, pp. X + 236.

Price $ 1.60 net.

WEBSTER

Diseases of Women. A Text-Book for
Students and Practitioners. By J.
C. Webster, B.A., M.D. (Edin.),
F.R.C.P. (Ed.), Demonstrator of Gynae-
cology, McGill University ; Assistant
Gynaecologist, Royal Victoria Hospital,
Montreal, etc. Illustrated with 241 Fig-
ures. i2mo. Cloth, pp. xxii-|-688.
Price $ 3.50 net.
WHITE

A Text-Book of General Therapeutics.

By W. Hale White, M.D., F.R.C.P.,
Senior Assistant-Physician to and Lec-
turer on Materia Medica and Thera-
peutics at Guy's Hospital. i2mo.
Cloth, pp. xi + 371. Illustrated.

Price $ 2.50 net.
WIEDERSHEIM

The Structure of Man : An Index to
His Past History. By Dr. R. Wie-
DERSHEIM, Professor in the University
of Freiburg, Translated by H. and M.
Bernard. The Translation edited
and annotated and a Preface written by
G. B. Howes, F.L.S., Professor of
Zoology, Royal College of Science,
London. 105 Illustrations. 8vo.
Cloth, pp. xxi + 227. Price $ 2.60 net.

WILLIAMS

The Roentgen Rays in Medicine and
Surgery as an Aid in Diagnosis, and
as a Therapeutic Agent. By Francis
H. Williams, M.D. 391 Illustrations.
8vo. Cloth, pp. XXX -j- 658.

Price $ 6.00 net.
Half morocco. Price $ 7.00 net,

WILLIAMSON

Diabetes Mellitus and Its Treatment.

By R. T. Williamson, M.D. (Lond.).
M.R.C.P., Medical Registrar, Manches-
ter Royal Infirmary; Hon. Med. Officer,
Pendleton Dispensary ; Assistant to the
Professor of Medicine, Owens College,
Manchester. With 18 Illustrations.
8vo. Cloth, pp. xi -f 417.

Price ^4.50 net.
WILLOUGHBY

Handbook of Public Health and De-
mography. By Edward F. Wil-
LOlicniiV, M.D. (Lond.), Diploma in
State Medicine of the London Univer-
sity and in Public Health of Cambridge
University. i6mo. Cloth. pp.
xvi + 509. Price $ 1.50

WILSON

The Cell in Development and Inherit-
ance. By Edmund B. Wilson, Ph.D.,

tVORKS ON MEDICINE AND SURGERY

Professor of Zoology, Columbia Uni-
versity. Second Edition, Revised and
Enlarged. 8vo. Cloth. 194 Illustra-
tions, pp. xxi + 483. Price ^ 3.50 Wif/.

By the Same Author

An Atlas of the Fertilization and Kar-
yokinesis of the Ovum. By Edmund
B. Wilson, Ph.D., Professor in Inver-
tebrate Zoology in Columbia Univer-
sity ; with the co-operation of Edward
Leaming, M.D., F.R.P.S., Instructor
in Photography at the College of Physi-
cians and Surgeons, Columbia Univer-
sity. Royal 4to. Cloth.

Price $ 4.00 net.
WILSON

Clinical Studies in Vice and in In-
sanity. By George R. Wilson,
M.D., Medical Superintendent, Maris-
bank Asylum. 8vo. Cloth, pp. xi +
234. Price $ 3.00 net.

WORSNOP

The Nurse's Handbook of Cookery ; A
Help in Sickness and Convalescence.
By E. M. Worsnop, First-Class Di-

plomee of the National Training School
of Cookery, South Kensington, and for
sixteen years Teacher of Cookery under
the London School Board. Assisted
by M. C. Blair. Second Edition.
i2mo. Cloth, pp. 106. Price 75 cents.

ZIEGLER

A Text-Book of Special Pathological
Anatomy. By ERNST Ziegler, Pro-
fessor of Pathology in the University
of Freiburg. Translated and Edited
from the Eighth German Edition, by
Donald MacAlister, M.A., M.D.,
Linacre Lecturer of Physic and Tutor
of St. John's College, Cambridge, and
Henry W. Cattell, M.A., M.D.,
Demonstrator of Morbid Anatomy in
the University of Pennsylvania. Bvo.
562 Illustrations.

Sections I-VIII. pp. xix -f 575 + xxxii.

Cloth, Price $ 4.00 w^/".
Sheep, Price $ 5.00 net.

Sections IX-XV. pp. xv + 576-1221 -f xxxL
Cloth, Price $ 4.00 «^^.
Sheep, Price % 5.00 net.

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