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QUAIN'S ANATOMY



E. A. SCHAFER & G. D. THANE



VOL. !;. P r - 1.

OSTEOLOGY



(,. D. THANE



I

SIl




MEDICAL .SCHOOL




John Marshall Williamson
Memorial



v



QUAIN'S

* "^

ELEMENTS OF ANATOMY . "



EDITED



EDWARD ALBERT SCHAFER, F.R.S.

PROFESSOR OI r PHYSIOLOGY AND HISTOLOGY IN UNIVERSITY COLLEGE, LONDON,



GEORGE DANCER THANE,

*>

PROFESSOR OF ANATOMY IN UNIVERSITY COLLEGE, . LONDON.

IN THREE VOLUMES.

VOL: IT. PART i.

OSTEOLOGY

BY PROFESSOR THANE.
ILLUSTRATED BY 168 ENGRAVINGS.

Ctntlj <tfttton.



LONDON :
LONGMANS, GREEN, AND CO.,

1890,

15






BHADBUKV.



LONDON

& CO. UMD.,



W, WH1TKFK.AK*




CONTENTS OF PAET I,



DESCRIPTIVE ANATOMY.



OSTEOLOGY.



I.



II.



III.



1

The Skeleton and Bones generally
THE VERTEBRAL COLUMN
Vertebne . . . . . .

General Characters .
Groups of Vertebne . . . .

Cervical Vertebne . . ' .
Dorsal Vertebne . . . .

Lumbar Vertebrae

Sacral Vertebra; . . . .

Coccygeal Vertebne .-
The Vertebral Column as a whole .
Ossification of the Vertebra; .
Serial Homology of the Vertebra' .
THE THORAX . . . . .

The Sternum or Breast-Bone

The Ribs

The Costal Cartilages
The Thorax as a whole . . .
Ossification of the Sternum and

Ribs

THK BOXES OF THE HEAD . . .
Occipital Bone ....

Parietal Bone . . . , .
Frontal Bone ....

Temporal Bone . . . .

Sphenoid Bone ....

Ethmoid Bone . . . . .

Superior Maxillary Bone

Palate Bone . . . . .

Vomer. .

Malar Bone . . , .

Nasal Bone .....

Lachrymal Bone

Inferior Turbinate Bone . . .

Inferior Maxillary Bone

Hyoid Bone ... .

THE SKULL AS A WHOLE

The Sutures . . . .

External Surface of the Skull .
Interior of the Cranium .
Nasal Cavities and Communi-
cating Air-Sinuses .
Ossification of the Bones of the
Head ..'..'.
GENERAL MORPHOLOGY OF THE BONES
OF THE HEAD . . . .

List of the Typical Component
Parts of the Bones of the
Head classified according to
their Origin ....

Various Forms of Skull
IV. BONES OF THE UPPER LIMB .

Clavicle . . . . . .

Scapula . . .



AGE
3
5
5

6
6

9
ii

16
18
19

21
23
23

28
29



71

73
78



79
82
86
86
87



I'AUK

Humerus . . . . . 91

Ulna 95

Radius . . . . 97

Carpus. . . . . .100

Scaphoid Bone . . . . 101

Lunar Bone . . . . 101

Pyramidal Bone . ... 101

Pisiform Bone . . . . 101

Trapezium Bone . . . . 102

Trapezoid Bone . . .102
Os Magnum . . . . . 102

Unciform Bone . . . .103

Metacarpus . . . . . 103

Digital Phalanges . . .105
Ossification of the Bones of the

Upper Limb . . . . 106

'. THE PELVIS AND LOWER LIMB . 1 10
Hip-bone . . . . . i 10

Ilium . . . . .110

Os Pubis 113

Ischium . . . . -113

The Pelvis 115

Position of Pelvis . . . 1 1 7

Differences according to Sex . .118

Femur. . . . . .118

Patella . . . . . . 124

Tibk 124

Fibula 127

Tarsus . . . . .129

Calcaneum or Os Calcis . .129

Astragalus . . . .130

Navicular Bone . . . . 131

Cuneiform Bones . . . 131

Cuboid Bone . . . . 132

Metatarsus . . . . . 133

Phalanges . . . . 135

The Bones of the Foot as a whole . 135

Ossification of the Bones of the

Lower Limb . . . .136
MORPHOLOGY OF THE BONKS OF THK

LIMBS ..... 140
Relation to the Axial Skeleton . 140
Homological Comparison of

Upper and Lower Limbs . 140
Shoulder and Pelvic Girdles . 140
Bones of the Limbs . . . 142
Hand and Foot . . .143
Table of the Homologous Bones
in the Thoracic and Pelvic
Limbs . . . .144
Carpus and Tarsus . . . 144
Scapula and Ilium . . 145
Adaptation of the Skeleton to the
Erect Attitude . . . . 145



286'"' 3



DESCEIPTIVE ANATOMY,



DESCRIPTIVE ANATOMY may be treated of in two methods : viz., the Systematic
and the Topographical.

In the first or Systematic Anatomy, the several organs and parts of the body are
considered in a systematic order, according to their structure, their connection with
each other, and their relation to the purposes of life ; while in the second, or
Topographical Anatomy, the parts are described in the order of their position
or association in any region of the body. The first method is best adapted for the
elementary and complete study of the structure of organs, the second is more
immediately useful in the study of particular regions in their relation to Medicine
and Surgery. The object of the present work being mainly to serve as a guide for
systematic study, the topographical details will for the most part be included under
and combined with the general description of organs, and only some of the more
important regions will receive separate notice.

The plan of construction of the body and the general arrangement of its chief
parts have been explained in the Introduction at the beginning of Yolume I. The
several systems and regions now to be described will be treated of under the following
heads :

1. Osteology, the Bones.

2. Arthrology, the Articulations.

3. Myology, the Voluntary Muscles, with which will be combined the Fasciae and

Aponeuroses.

4. Angeiology, the Heart, the Blood- Vessels, and the Lymphatics.

5. Neurology, the Spinal Cord and Brain, the Nerves, and the Organs of the

Senses.

6. Splanchnology, the Organs of Respiration, the Organs of Digestion, the

Urinary Organs, and the Organs of Reproduction.

7. Superficial Anatomy, and Topographical Anatomy of some Regions.

Descriptive terms. In anatomical descriptions the body is always supposed
to be in the erect attitude, and terms of relation are employed strictly with reference
to this position. Thus, superior and inferior correspond respectively to cephalic and
caudal, anterior and posterior to ventral and dorsal. The body being bilaterally
symmetrical, it might be divided into similar and nearly equal halves by a vertical
plane directed from before backwards. This is known as the median plane, and the
line along which the median plane meets the surface of the body is called the middle
or median line. The words internal or mesial and external or lateral denote

VOL. II. B



2 DESCRIPTIVE ANATOMY.

respectively nearer to or farther from the median plane. Sagittal indicates a dorso-
ventral direction in or parallel to the median plane, and coronal or frontal a direction
perpendicular to the foregoing in a transverse vertical plane. The terms superficial
and deep, central and peripheral, proximal and distal, are often used, and need
no explanation. In many cases precision may be obtained by reference to certain
fixed relations of parts, such as the vertebral and sternal ends of the ribs, the radial
and ulnar, or tibial and fibular borders, and the flexor and extensor surfaces of
the limbs. Preaxial and postaxial, applied, for instance, to parts of the limb,
signify, respectively, on the primitive cephalic or caudal aspect of the axis of
the member.



OSTEOLOGY.

By G. D. THANE.

THE SKELETON.

THE skeleton or solid framework of the body is mainly formed of the bones, but
is completed in some parts by the addition of cartilages. The bones are bound
together by means of ligaments, and are so disposed as to support the softer parts,
protect delicate organs, and give attachment to the muscles by which the different
movements are executed.

In the lower animals the term skeleton has a wider signification than in man,
comprehending two sets of parts, viz., 1st, those of the endoskeleton, or the deeper
osseous and cartilaginous framework which corresponds to the human skeleton ; and
2nd, those of the exoskeleton, or dermal skeleton, comprising the integument and
various hardened structures connected with it. All vertebrate animals possess an
eudoskeleton ; but in some of them the exoskeleton attains greater proportions
than in others, and is combined by means of hardened parts more f ully with portions
of the endoskeleton. In most invertebrate animals the dermal or exoskeleton alone
exists.

In man, as in the higher vertebrates, the greater part of the endoskeleton is
formed of bone, a calcified animal tissue, which, when freed by putrefactive macera-
tion from its fat and various soft adherent parts, and subsequently dried, is capable
of remaining unchanged for a very long period of time. It is customary and con-
venient thus to study the bones chiefly in the macerated and dried state, that is,
deprived of their accessory soft parts.

The accessory soft parts connected with the fresh bones consist chiefly of the
external fibrous and vascular covering termed periosteum, and of the medulla,
marrow or fat, which fills their larger internal cavities. The bones are permeated
by blood-vessels, and they are provided also with absorbent vessels and with nerves
in small quantity.

The ends of the bones, when jointed moveably with others, are covered by a thin
layer of dense permanent cartilage, called articular cartilage; and the adjacent
bones are united together by fibrous ligaments which may be considered as con-
tinuous with the periosteum covering the rest of the bones. In some instances
distinct bones are directly united by means of ligament or cartilage without any
joint-cavity intervening. Thus the osseous system as a whole may be considered to
be enveloped by a fibrous covering.

The bones are originally formed by a process termed ossification from soft sub-
stance. This process commences in the greater number of bones in cartilage ; in
some it begins in fibrous tissue or membrane ; and in all instances the farther
growth of the bone substance takes place largely in the latter way. The deposit of
bone begins generally at one spot, which is therefore called the primary centre of
ossification ; but there may be several of these from the first. The main part of the
bone thus formed from the primary centre is sometimes named the diaphysis. In
most bones, after considerable advance in growth by extension from the primary

B 2



4 OSTEOLOGY.

centre, ossification occurs at comparatively later periods in one or more separate
points, forming secondary or tertiary centres ; and the portions of bones so formed,
which remain united to the main part for a time by intervening cartilage, are termed
epiphyses. In many instances entire consolidation of the bone by the osseous union
of the epiphyses does not take place till the full size has been attained, and this may
be as late as the twenty-third or even the twenty-fifth year of life.

In their outward form the bones present much diversity, but have been reduced
by anatomists to the following classes : 1. Long or cylindrical, such as the chief
bones of the limbs. These consist of a body or shaft, cylindrical or prismatic in
shape, and two extremities which are usually thicker than the shaft, and have smooth
cartilaginous surfaces for articulation with neighbouring bones. The shaft is
generally hollow and filled with marrow, by which sufficient size and strength are
attained without undue increase of weight. 2. Tabular or fiat bones, like the
scapula, ilium, and the bones forming the roof and sides of the skull. 3. Short
bones, which are more or less cubical or oblong, as in the carpus and tarsus.
4. Irregular or mixed bones, mostly situated symmetrically across the median plane
of the body, and often of a complex figure, such as the vertebrae.

In these differently shaped bones the osseous substance occurs in two forms, viz., the
compact and the spongy. There is, however, no essential difference in structure or propertie3
between these beyond that of thickness or thinness of the component material.

The surfaces of bones present various eminences, depressions, and other marks, to designate
which the following terms are in common use. Any marked bony prominence is called a
process or apophysis ; a slender, sharp, or pointed eminence is named a spine, or spinovs
process ; a blunt one a tubercle ; a broad and rough one a tuberosity. The terms crest, line,
and ridge are usually applied to a prominent border, or to an elevation running some way
along the surface of a bone. A head (caput, capitulum, or capitellum) is a rounded process
usually supported on a narrower part named the necli (cervix). The term condyle, somewhat
variously applied by anatomists, is most frequently employed to denote an eminence bearing
a rounded articular surface.

The cavities and depressions of bones are very variously named. An aperture or perfora-
tion, when short, is & foramen; when continued some way as a passage it is a canal or
meatus. A narrow slit is a fissure, an open excavation or hollow in one bone or in several
together is a fossa. This term is also sometimes applied to the socket of a joint, as in the
fflenoid or shallower, and the cotyloid or deeper form of joint-cavity. Sinus and antrum are
names applied to considerable cavities in the interior of certain bones. Besides these, various
other terms are employed which do not require explanation, such as notch (incisura), groove,
furrow (sulcus), &c.

The number of bones in the skeleton varies at different periods of life, some
which are originally distinct becoming united together as the process of ossification
advances. The following is a statement of the number usually reckoned as distinct
in middle life :

Single bones. Pairs. Total.

The vertebral column . . . 26 - ... 26

Axial , The skull ..... 6 8 22

Skeleton. 1 The hyoid bone . . . .1 ... 1

^ The ribs and sternum ... 1 12 25

Appendicular f The upper limbs . . .... 32 64

Skeleton. ( The lower limbs ....... 31 62

34 83 200

Besides the bones included in the above enumeration, there exist likewise the three
pairs of auditory ossicles, and various bones formed in tendons and called sesamoid,
the most constant of which are, besides the patella and pisiform bone, reckoned in
the table above as limb-bones, a pair in each thumb and great toe.



/

,)



THE VERTEBRAL COLUMN.



SPINOUS PROCESS



TRANSVERSE
PROCESS



SUP. ARTIC. PROCESS



I. THE VERTEBRAL COLUMN.

The vertebral column is composed of a series of bones called vertebrae, which are
united together, for the most part, by joints and elastic substance in such a manner
that, although the amount of motion allowed between each pair is slight, the
aggregate is sufficient to give the column very considerable flexibility. The vertebra
are originally thirty-three in number. Of these, the upper twenty-four remain
separate in the adult, retaining their mobility, and are hence called moveaUe or true
vertebrae. They are succeeded by five others, which rapidly diminish in size from
above downwards, and which are united into one mass called the sacrum ; beyond
the sacrum are four dwindled terminal members of the series, which as age
advances, likewise become more or less united, and form the coccyx. These sacral
and coccygeul vertebrae are known as thefaed we false vertebrae.

General characters of the vertebrae. The general characters are best seen
in the vertebrae placed near the
middle of the column, of which
the tenth dorsal vetebra, shown
in fig. 1, may serve as an example.
Each has more or less the form of
a ring, and presents for considera-
tion a body, arch, processes, and
the enclosed spinal foramen.

The body or centrum is a short
cylinder or disc, which forms the
anterior part of the vertebra. Its
superior and inferior surfaces are
flattened and connected to the
next vertebrae by strong and elas-
tic intervertebral discs. On the
front and sides it is convex hori-
zontally, but slightly concave
from above downwards ; its pos-
terior surface forms part of the
ring, and is slightly concave from

Side to Side. J.hese vertical pjg_ j TENTH DORSAL VERTEBRA, FROM ABOVE. (Drawn
surfaces are pierced by numerous by D- Gnn.)

small foramina for the passage

of blood-vessels, and near the middle of the posterior surface are one or two much
larger than the others.

The arch (neural) consists of two symmetrical portions which spring, one on each
side, from the posterior surface of the body, and meet in the median plane behind.
The anterior part of each half, thick and narrow, is called the pedicle ; the posterior
part is broad and flat, and is called the lamina. The concavities on the upper and
lower borders of the pedicles are named vertebral notches (fig. 2, B), and consti-
tute, by the apposition of those of contiguous vertebrae, the intervertebral foramina,
a series of rounded apertures, which communicate with the vertebral canal, and
transmit the spinal nerves and blood-vessels.

The spinous process (neural spine) projects backwards from the arch in the
median plane. The transverse processes, placed one on each side, project outwards
from the arch at the junction of the pedicle with the lamina. The articular pro-
cesses (zygapophyses), two superior and two inferior, project upwards and downwards
opposite the attachment of the transverse processes ; their articular surfaces, coated




6



THE VERTEBRAL COLUMN.



with cartilage, in the superior pair look backwards, and in the inferior forwards, so
that the former face the latter in adjoining vertebras.

The foramen is bounded anteriorly by the body, posteriorly and laterally by the
arch. The series of rings thus formed, united by ligaments, constitutes the spinal
or neural canal, which lodges the spinal cord.

Texture. The bodies of the vertebrae are almost entirely composed of spongy substance,
the principal lamellae being vertical : on the surface is a thin layer of compact tissue.
Venous canals, commencing at the larger foramina behind, traverse the cancellated structure.
The arch and processes contain a much smaller proportion of spongy substance, being covered
with compact tissue of considerable density in some places.



INF. ARTIC.PROC.



SUP.ARTIC.PROC.



GROUPS OF VERTEBRJE.

The vertebrae are divided into five groups, named from the regions which they
occupy, cervical, dorsal, lumbar, sacral, and coccygeal.

Cervical vertebrae. These are seven in number ; they are the smallest of the

moveable vertebras, and are spe-
cially characterized by the pre-
sence of foramina in the trans-
verse processes. The first and
second are so peculiar in form,
as to require a separate descrip-
tion. The following are the
common characters of a cervical
vertebra.

The lody is small, and much
broader from side to side than
from before backwards ; in depth
nearly the same in front and
behind. Its upper surface is trans-
versely concave from the upward
projection of its lateral margins,
and is sloped down in front. The
under surface, on the contrary,
is rounded off at the sides, while
its anterior margin forms a marked
projection downwards.

The pedicles spring from the
body about midway between the

upper and lower borders, and are directed outwards and backwards ; the lamina are
slender, long and flat. The superior and inferior notches are nearly equal in depth.
The spinous process is short, only slightly depressed, and bifid.
The tranverse processes are short, and present at their extremities two tubercles,
anterior and posterior. Each process is deeply grooved above for a spinal nerve, and
its base is perforated vertically by a round foramen (vertebrarterial), through which
in the upper six the vertebral artery and vein pass. It is united with the rest of the
vertebra by two parts ; by the posterior, at the place of junction of the pedicle and
lamina, like a dorsal transverse process ; by the anterior, to the body of the vertebra,
in the same position as the heads of the ribs.

The articular processes are placed at the extremities of a short, stout, vertical
column of bone ; their articular surfaces are nearly flat and oblique, the superior
looking backwards and upwards, the inferior forwards and downwards.




NF. VERTEBRAL NOTCH



Fig. 2. FOURTH CERVICAL VERTEBRA : A, FROM ABOVE
B, FROM THE RIGHT SIDE. (Drawn by D. Gunn. )



THE FIRST CERVICAL VERTEBRA.



The foramen is triangular, with rounded angles, and larger than in the dorsal or
lumbar vertebras.

The first cervical vertebra, or atlas, differs remarkably from the others in
the absence of a body and spinous process, having the form merely of a large ring
with articular and transverse processes.

The interior of the ring is wider behind than in front. Its posterior part cor-



ODONTOID PROCESS




TIC. PROCESS



RANSV. PROC.



TRANSV. PROC.



INF. ARTIC. PROCESS



Fig. 3. ATLAS AND AXIS, FROM BEFORE. (Drawn by D. Gunn.)

responds to the foramina of the other vertebrae ; its narrower anterior part is
occupied by the odontoid process of the axis, and in the recent state is separated
from the posterior by the transverse ligament. In front of the ring is the anterior
arch, on the anterior aspect of which is a small tubercle, and on the posterior a
smooth surface for articulation with the odontoid process. At the sides of the ring
are the lateral masses, which are thick and strong, bearing the articular processes
above and below, and extending outwards into the transverse processes. The articular




POSTERIOR ARCH

ERTEBRAL GROOVE

SUP. ARTIC. PROC.



FOR TRANSV.
LIGAMENT



TUBE

ANTERIOR ARCH
ARTIC. SURF. FOR ODONTOID PROC



Fig. 4. ATLAS, FROM ABOVE. (Drawn by D. Gunn.)
The position of the transverse ligament is indicated by dotted lines.

processes differ from those of other vertebrae in being situated in front of the places
of exit of the nerves. The superior, larger than the inferior, are oval, and converge
in front ; their articular surfaces are concave for the reception of the condyles of
the occipital bone, and look upwards and inwards ; they are frequently divided by a
transverse groove into two. Below the inner margin of each, towards the front, is a
smooth rounded tubercle, to which the transverse ligament is attached. The inferior
articular processes are smaller than the superior, flat, nearly circular, looking down-
wards and slightly inwards.

The posterior arch presents in the middle line a rough elevation, the rudiment of
a spinous process ; at its junction with the lateral masses, it is hollowed out above



8



THE VERTEBRAL COLUMN.



so as to form a smooth transverse groove the vertebral groove, in which lie the verte-
bral artery and first spinal (suboccipital) nerve ; the groove corresponds to the
superior notches of the other vertebrae.

The transverse processes are larger and project farther outwards than those of the
subjacent vertebra?. They are flattened from above downwards, and have a large
foramen. Their extremities are not bifid, but broad and rough.

Varieties. The posterior arch of the atlas is sometimes imperfect, the gap in th.e bone
being 1 bridged across by a fibrous band. A similar defect in the anterior arch is comparatively
rare, but its complete absence has been observed. 1 The transverse process, especially the
anterior bar, may also be the seat of defective ossification, and the foramen of the vertebral
artery is then completed by ligament. A bony arch over the vertebral groove is frequently met
with. Less common is the formation of a canal for the vertebral artery on the outer side of
the superior articular process.

The second vertebra or axis (vert, dentata) forms a pivot on which the
first vertebra rotates carrying the head.

The lody is characterized by the presence of a large blunt tooth-like process called




F. ARTIC.PROC.




Fig. 5.-



-AXIS, FROM THE RIGHT SIDE.

by D. Gunn.)



(Drawn



Fig. 6. SEVENTH CERVICAL VERTEBRA, FROM
ABOVE. (Drawn by D. Gunn. )



odontoid (proc. dentatus). This consists of an enlarged part termed the head, and a
lower part or neck. It has in front a smooth surface for articulation with the
atlas, and behind a smooth groove to receive the transverse ligament. The lower
surface of the body resembles that of the succeeding vertebrae. Its anterior surface
is marked by a low median vertical ridge, with a depression on each side.

The superior articular surfaces, placed like those of the atlas in front of the notch,
lie close to the base of the odontoid process, partly on the body and partly on the
pedicles of the vertebra. These surfaces look upwards and slightly outwards. The
inferior articular processes are similar in form and position to those of the succeeding
vertebrae.

The spinous process is very large, rough, deeply bifid, and grooved on its inferior
surface. The lamina are very thick and strong.

The transverse processes are short, and the anterior tubercle almost obsolete. The
foramen for the vertebral artery is inclined obliquely upwards and outwards.

The seventh cervical vertebra has a long spinous process, which is not
bifurcated, but ends in a broad tubercle projecting under the skin, whence the name



1 Dwight, Journ. Anat., xxi, 539.


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