Quain's Elements of anatomy (Volume 3:1) online

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OF THK

UNIVERSITY OF CALIFORNIA.

^Received . , igo .

Accession No. k 3 4*0 I ' Class No.

iLOGY




:






QUAIN'S

ELEMENTS OF ANATOMY



BDITED BT



EDWARD ALBERT SCHAFER, F.R.S.

I'ROFESSOR OF PHYSIOLOGY AND HISTOLOGY IN UNIVERSITY COLLEGE, LONDON,



AND



GEORGE DANCER THANE,

OF ANATOMY IN UNIVERSITY COLLEGE, LONDON.



IN THREE VOLUMES.

VOL. III. PART I.
THE SPINAL CORD AND BRAIN.

BY PROFESSOR SCHAFER,
ILLUSTRATED BY 139 ENGRAVINGS.



LONGMANS, GREEN, AND CO.

39 PATERNOSTER ROW, LONDON

NEW YORK AND BOMBAY

1900

All rights reserved

stTDi

or TH



, ,

UNIVERSITY



BIOLOGY

UBRARY

G



BIBLIOGEAPHICAL NOTE.

Ninth Edition, 2 Vols., 8vo. November, 1882. Vol. I. Reprinted March, 1884 ;
October, 1887. FoZ. //. Reprinted December, 1883; 4pn7, 1887.

.flTeiw Edition, edited by E. A. Schafer and G. D. Thane, in 8 separately issued
Parts and Appendix, 1890-6.

Vol. III., Part I. (The Spinal Cord and Brain) , first separate issue, January, 1893.
Reprinted August, 1895 ; February, 1900 ; September, 1900.



BRADBURY, AGNEW, & CO. LD., PRINTERS, LONDON AND TONBB1DGK.



CONTENTS OF PAR




THE SPINAL CORD AND BRAIN.






TAGE

THE CEREBRO-SPINAL Axis . . . I

THE SPINAL COKU 2

External form . . . . . . 2

Fissures 6 .

Internal structure . . . . . 7
Grey Matter ..... ,7

Central Canal 9

White Matter 9

Features of different regions . . . 10

Microscopic structure . . . .12

General structure . . . . . 12

Distribution of Nerve-Cells . .14

of Anterior Horn . . . . 14

of Clarke's Column . . .16

of Middle Cell-Column . . . 17

of Posterior Horn ; Solitary Cells. 17

Commissures 18

Central Canal . . . . .19
Origin of Spinal Nerves . . . . 19
Anterior Roots . . . . 19

Posterior Roots . . . . 20
Collateral Fibres . . . .21

Conducting Tracts 22

Methods of investigation . . .22

Antero-lateral Column . . . . 24

Posterior Column . . . .26

Degenerations in Spinal Cord . . . 27

From section of Posterior Roots . .27

From Lesions of the Brain . . . 31

From Lesions of the Cerebellum . . 32

From Lesions of the Cord . . . 32

THE BRAIN OR ENCEPHALON . . -38

THE MEDULLA OBLONGATA AND PONS

VAUOLII 38

THE MEDULLA OBLONGATA . . .38

External characters 38

Posterior Area 43

Lateral Area . . . . . . 45

Olivary Body 45

Anterior Area 45

Pyramids 45

THE PONS VAROLII 46

Fourth Ventricle 47

Internal structure of Medulla Oblongata 51

Closed part 51

Ventricular part 53

Nucleus of Olivary Body . . .56

Formatio Reticularis . . . . 58

Arched Fibres . . . . .59

Internal structure of Pons Varolii . . 60

Course of Fibres from Cord through Bulb

and Pons 63

Transition from Pons to Mid-Brain . . 65



PAGE

THE CEREBELLUM . , . . 69
External form . . . . . . 69

Upper surface . . , . .71

Under surface 74

Arbor Vitse 83

Commissural Fibres in White Matter . 84

Peduncles 84

Microscopic structure . . . . 86
Degenerations following Lesions of. . 93
THE MID-BRAIN AND INTER-BRAIN . . 96
Aqueduct of Sylvius . . . .96
Third Ventricle . . . . . 97
Central Grey Matter of Aqueduct . . 98

Crura Cerebri 100

Crasta 100

Substantia Nigra 101

Tegmentum 102

Tract of Fillet . . . . . . 103

Dorsal part of Mid-Brain . . . 105
Corpora Quadrigemina . . . 105
Posterior Commissure .... 109

Geniculate Bodies 109

Optic Thalami no

Trigonum Habenulse . . . . 113

Subthalamic Tegment&l Region . .114
Pineal Body . . . . . . 114

Posterior Perforated Space . . . 115
Corpora Albicantia . . . . 115

Infundibulum, and Tuber Cinereum . 116

Pituitary Body 116

Lamina Cinerea . . - . .117
Optic Tracts and Chiasma . . .117
THE LATERAL VENTRICLES : CORPORA

STRIATA : CEREBRAL HEMISPHERES 122
Lateral Ventricles . . . . .122

Corpus Callosum 127

Septum Lucidum 129

Fornix 129

Tsenia Semicircularis . . . .131

Corpora Striata 131

External Capsule 135

Claustrum 135

Internal Capsule 136

Cerebral Hemispheres . . . . 137
External form . . . . .137

Fissures 141

Frontal Lobe 145

Parietal Lobe 149

Occipital Lobe 151

Temporal Lobe 152

Central Lobe or Island of Reil . .154
Limbic Lobe . . . . . . 155

Olfactory Lobe . . . . .159



43401



IV



CONTENTS OP PART I.



PAGE

THE CEREBRAL HEMISPHERES continued.
Variations in Fissures and Convolu-
tions 161

Causation of Gyri and Sulci . . . 162
Structure of White Matter . . .163
Structure of Grey Matter . . . 166
Differences of structure in different

parts 172

MEASUREMENTS OF THR BR*IN , . . 176
Dimensions . . . . .176
Extent of Grey Cortex . . . . 176
Thickness of Cortex . . . .177
Weight 178



PAGE
MEMBRANES OF BRAIN AND SPINAL CORD 181

Dura Mater 181

Subdural space 184

Pia Mater 184

Arachnoid Membrane . . . . 187
Subarachnoid Space ....
Ligamentum Denticulatum .
Glandulse Pacchionii ....
BLOOD-VESSELS OF BRAIN AND SPINAL
CORD * . .

Spinal Com . . . . . 191

Brain . 193

LYMPH-PATHS OF BRAIN AND SPINAL CORD 198



187
189
190

191




NEUEOLOGY.



THE CEREBRO-SPINAL AXIS.

By E. A. SCHAFER.

THE cerebro-spinal axis is divided into the
brain or encephalon, the enlarged part within the
skull, and the spinal cord within the vertebral
canal. It is symmetrical in form, consisting of
a right and a left half, separated to some extent
by fissures and cavities, but united by various
portions of white and grey nervous substance
which cross from one side to the other, and



Fig. 1. VIEW OF THE CEREBRO-SPINAL AXIS.

Bourgery. ) 1



(After



The right half of the cranium and trunk of the body
has been removed by a vertical section ; the membranes of
the right side of the brain and spinal cord have been cleared
away, and the roots and first part of the fifth and twelfth
cranial nerves, and of all the spinal nerves of the right
side, have been dissected out and laid separately on the
wall of the skull and on the several vertebrae opposite to
the place of their natural exit from the cranio-spinal cavity.

F, T, 0, frontal, temporal and occipital lobes of cere-
brum ; C, cerebellum ; P, pons Varolii ; m o, medulla
oblongata ; m s, m s, point to the upper and lower
extremities of the spinal marrow ; c e, on the last lumbar
vertebral spine, marks the cauda equina ; v, the three
principal branches of the nervus trigeminus ; C i, the
sub-occipital or first cervical nerve ; C vin, the eighth or
lowest cervical nerve ; D i, the first dorsal nerve ; D xu,
the last dorsal ; L i, the first lumbar nerve ; L v, the last
lumbar ; S i, the first sacral nerve ; S v, the fifth ; Co I,
the coccygeal nerve ; s, the left sacral plexus.

form the commissures of the brain and spinal
cord.

The cerebro-spinal axis is enveloped within
the skull and vertebral canal by three connective
tissue membranes, between which are spaces
occupied by a clear fluid (cerebro-spinal fluid).
These envelopes, which will be described later,
are, 1st, a firm fibrous membrane named the
dura mater, which is placed most externally ;
2nd, a delicate membrane called the arachnoid;
and, 3rd, a highly vascular membrane named the
pia mater, which is next to, and closely invests
the surface of the brain and cord.




VOL. III.



THE SPINAL CORD.



SPINAL CORD.

The spinal cord or spinal marrow (medulla spinalis) is about 18 inches (45
centimeters) long, and extends from the margin of the foramen magnum of the occi-
pital bone to about the lower part of the body of the first lumbar vertebra. Above,
it is continued into the bulb (medulla oblongata) ; below, it tapers conically and
ends in a slender filament, thefilum terminals or central ligament of the spinal cord.

Although the cord usually ends near the lower border of the body of the first
lumbar vertebra, its termination is sometimes a little above or below that point, as




Fig. 2. SECTIONS SHOWING THE GENERAL RELATIONS OF THE SPINAL CORD TO THE INCLOSING THECA,

AND OF THIS TO THE VERTEBRAL CANAL. (Key and RetziuS. )

A, through the fifth cervical vertebra ; B, through the tenth dorsal vertebra : C, through the first
lumbar vertebra and the foramen of exit of the twelfth dorsal nerve-roots ; D, through the disk between
the second and third lumbar vertebrae ; E, through the first sacral vertebra. In A, B, and C, the cord,
covered by pia mater, is seen in the centre, with the ligamentum denticulatum attached to it on either
side ; the nerve-roots on either side form small groups which, since they pass obliquely downwards to
their foramina of exit, are cut across ; the dura matral sheath is separated by a considerable space from
the cord, and by a quantity of loose areolar and fatty tissue from the wall of the vertebral canal. This
tissue is in smaller amount in C. D and E are below the termination of the cord, and show sections of
the nerve-bundles of the cauda equina within the dural sheath, which is very large in D, but compara-
tively small in E, the vertebral canal in the latter being largely occupied by adipose tissue. In this are
seen the sections of two large veins. The arachnoid is not represented in any of these sections.

opposite to the last dorsal or to the second lumbar vertebra. The position of the
lower end of the cord also varies according to the state of curvature of the vertebral
column, in the flexion forwards of which the end of the cord is slightly raised. In
the fetus, at an early period, the embryonic cord occupies the whole length of the
vertebral canal ; but, after the third month, the canal and the roots of the lumbar
and sacral nerves begin to grow more rapidly than the cord itself, so that at birth the
lower end reaches only to the third lumbar vertebra. After birth the thoracic part
of the cord lengthens proportionately more than the other parts, so that in the infant
the roots of the lo.ver dorsal nerves come off relatively higher up than at a later age
(Pfitznerj.



THECA. 3

The cord is enclosed in the vertebral canal within a sheath (theca) considerably
longer and larger than itself, formed by the dura mater, and separated from the walls
of the canal by venous plexuses, and much loose areolar tissue (fig. 2). "The cavity of
the sheath between the pia mater and the dura mater is occupied by cerebro-spinal
fluid, and is divided by the curtain-like arachnoid into the spaces, subdural and sub-
arachnoid, above mentioned. Within the latter the cord, covered closely by pia
mater, is suspended, being kept in position by a ligament on each side (ligamentum
denticulatum), which fixes it at frequent intervals to its sheath, and by the roots of
the spinal nerves which pass across the space from the surface of the cord towards
the intervertebral foramina.

The spinal nerves come off in pairs at intervals along the cord. The portion
of spinal cord to which each pair of roots is attached is termed a " segment," but
there is in man and mammals complete continuity from segment to segment, and
not even a sign of constriction between them. Each nerve is attached to the surface
of the cord by two roots, one of which is anterior or ventral and non-gangliated, 1 the
other is posterior or dorsal and is provided with a ganglion. The uppermost two
or three nerve-roots cross the subarachnoid and subdural spaces nearly horizontally
(figs. 1 and 5), but the rest pass across with a more and more oblique downward
inclination until their direction is almost vertical, and indeed the lower part of the
theca below the termination of the cord Cfig. 2, D, E), is occupied by the descending
roots of the lumbar and sacral nerves, passing to the foramina between the corre-
sponding vertebrae. This mass of nerve-roots, which conceals the delicate filum
terminale, is named the cauda equina (figs. 4, 5, 6).

The relation between the spines of the vertebras and the places of attachment of
the nerve-roots to the cord is illustrated by the appended diagram (fig. 3) from
Keid, which is founded upon observations made on six adult subjects. From this it
will be seen that there is a much larger amount of variation than might have been
supposed. This is especially the case with the dorsal nerve-roots, some of which
show variations of their position of origin extending over a distance covered by as
many as three spinous processes. Certain general facts can, however, be made out
which are not without practical interest. Amongst these are the position of the
second cervical nerve opposite the arch of the atlas ; that of the first dorsal or
thoracic nerve, opposite the sixth or seventh cervical spine ; that of the seventh
thoracic nerve, opposite the fourth or fifth dorsal spines, and of the sacral nerves, the
range of which extends from the eleventh dorsal to the first lumbar spine. The
line of origin of the sacral nerves very nearly corresponds in vertical extent with the
body of the first lumbar vertebra.

No doubt this variation is largely accounted for by the variations in length and
obliquity of the spinous processes of the vertebrae, and accordingly we find that
there is least fluctuation of relative position at the top and bottom of the series.
The anterior and posterior (ventral and dorsal) nerve-roots belonging to the same
segment of the cord leave it practically at the same level (Reid).

The cervical enlargement (see next page) about corresponds in vertical extent
with the spines of the cervical vertebrae, while the lumbar enlargement corresponds
with the spines of the tenth, eleventh, and twelfth thoracic and the interval between
the last named and the first lumbar.

In section the cord is nearly circular, especially in the thoracic region, but it is
somewhat flattened before and behind. In the thoracic region, it measures about
ten millimeters (0*4 inch) from side to side, and about eight from before back. The

1 Some animals (e..g.,cat) have a few ganglion-cells interpolated amongst the fibres of the anterior or
ventral nerve-roots. Hoche finds that in the anterior roots of the lower lumbar and sacral nerves of
man, just at their junction with the cord, ganglion-cells, like those of the posterior root, are almost
constantly present, lying singly or in groups, and connected with some of the issuing nerve-fibres by a
T-shaped iunction.

B 2



THE SPINAL CORD.
A



4 CERVICAL



3" CERVICAL



> 7 CERVICAL



S' OORSAL-<



>7TH DORSAL



|3 >9 DORSAL,



f-3*0 LUMBA3



4TM LUM8AR<



LOCCYCEAL - <



Fig. 3. DlAaRAM SHOWING THE
VARYING RELATIONS OF THE ROOT-
ORIGINS OF THE SPINAL NERVES
TO THE SPINES OF THE VERTEBRAE.

( After R. W. Reid.)




' Jo



Fig. 4. A, VENTRAL (ANTERIOR) AND B, DORSAL (POSTERIOR) VIEWS OF THE MEDULLA OBLONGATA AND

SPINAL CORD WITH SECTIONS. (Allen Thomson. )

The cord has been divested of its membranes and of the roots of the nerves. The filiform prolonga-
tion, represented separately in B', has been removed. C, a transverse section through the middle of the



EXTERNAL FORM.



medulla oblongata ; D, a section through the middle of the
cervical enlargement of the cord ; E, through the upper
dorsal region ; F, through the lower dorsal region ; G, through
the middle of the lumbar enlargement; and H, near the lower
end of the conus medullaris.

1 to 6 refer to parts of the medulla oblongata ; the
remaining numbers to parts of the spinal cord.

1, pyramids ; 1', their decussation ; 2, olivary bodies ;
3, lateral columns ; 4, fourth ventricle ; 4', calamus scrip-
torius ; 5, funiculus gracilis ; 6, funiculus cuneatus ; 7,
7, anterior median fissure of the spinal cord ; 8, 8, postero-
lateral groove corresponding to the attachments of the pos-
terior nerve-roots ; 9, 9, posterior median fissure ; x , taper-
ing extremity of the cord ; x , x , in B', filum terminate.

cord is not, however, of uniform diameter
throughout, but is swollen out in the cervical
and lower dorsal regions, two enlargements
being thereby produced an upper or cervical
(brachial), and a lower or lumbar (crural) (fig. 4).
Of these the cervical enlargement is of greater
size and extent than the lumbar. It extends from
the upper limit of the cord to the body of the first
or second thoracic vertebra ; it is largest oppo-
site the fifth or sixth cervical vertebra, where it
measures from 13 to 14 mm. from side to side.
The lower or lumbar enlargement begins at the
tenth thoracic vertebra, is largest opposite the
twelfth (11 13 mm. across), and from this
point becomes gradually smaller ; its antero-pos-
terior diameter is more nearly equal to the

Fig. 5. DIAGRAMMATIC VIEW FROM BEFORE OF THE SPINAL

CORD AND MEDULLA OBLONGATA, INCLUDING THE ROOTS
OF THE SPINAL AND SOME OF THE CRANIAL NERVES, AND
ON ONE SIDE, THE GANGLIATED CHAIN OF THE SYMPA-
THETIC. (Allen Thomson.) $.

The spinal nerves are enumerated in order on the right
side of the figure. Br, brachial plexus : Cr, anterior
crural, 0, obturator, and So, great sciatic nerves, coming
off from lumbo-sacral plexus ; x , x , filum terminate.

a, b. c, superior, middle and inferior cervical ganglia of
the sympathetic, the last united with the first thoracic,
d ; d', the eleventh thoracic ganglion ; I, the twelfth
thoracic (or first lumbar) ; below s s, the chain of sacral

Ha.






transverse than is the case in the cervical en-
largement. Below the lumbar enlargement the Ti/^l ftfflllvv' 111
cord tapers in the form of a cone (conus medul-
laris), from the apex of which the small fili-
form prolongation is continued downwards.

The cervical and lumbar enlargements have
an evident relation to the large size of the
nerves which supply the upper and lower limbs,
and which are connected with those regions of
the cord. At the commencement of its develop-
ment in the embryo the spinal cord is destitute
of these enlargements, which, in their first appearance and subsequent progress,
correspond with the growth of the limbs.

The terminal filament (filum terminale, central ligament) (fig. 6, b, b) descends



SC



6



THE SPINAL CORD.



in the middle line amongst the nerves composing the cauda equina, and, reaching
the lower end of the sheath opposite to the second sacral vertebra, perforates the dura
mater, and receiving an investment from it, passes on to be attached with this to the
periosteum of the lower end of the sacral canal, or to the back of the coccyx. It is
a prolongation of the pia mater, enclosing for about half its length an enlarged
continuation of the central canal of the cord (see p. 9j, with a little grey matter
near the upper end. Below the termination of the canal, the filum is mainly com-
posed of connective tissue, with blood-vessels prolonged
from the anterior spinal vessels, and on either side there
run in it three or four small bundles of medullated nerve-
fibres, some of which have a few ganglion-cells. These
nerve-bundles are regarded by Eauber as representing
rudimentary coccygeal nerve-roots. They have no con-
nection with the coccygeal nerves proper.

The filum terminale is distinguished by its silvery
hue from the nerves among which it lies.



Fig. 6. VlEW FROM BEHIND OP THE LOWER END OF THE SPINAL

CORD WITH THE CAUDA EQUINA AND DURAL SHEATH. (Allen

Thomson. ) ^

The sheath has been opened from behind and stretched towards
the sides ; on the left side all the roots of the nerves are entire ; on
the right side both roots of the first and second lumbar nerves are entire,
while the rest have been divided close to the place of their passage
through the sheath. The tones of the coccyx are sketched in their
natural relative position to show the place of the filum terminale
and the lowest nerves.

a, placed on the posterior median fissure at the middle of the
lumbar enlargement of the cord ; b, b. the terminal filament, drawn
slightly aside by a hook at its middle, and descending within the
dural sheath ; b', b', its prolongation beyond the sheath and upon
the back of the coccygeal bones ; c, the dural sheath ; d, double
foramina in this for the separate passage of the ventral and dorsal
(anterior and posterior) roots of each of the nerves ; e, ligamentum
denticulatum ; Dx, and DXII, the tenth and twelfth thoracic (dorsal)
nerves ; Li, and Lv, the first and fifth lumbar nerves ; Si, and Sv,
the first and fifth sacral nerves ; Ci, the coccygeal nerve.



Dxii



S>Li



Fissures. The spinal cord is incompletely divided
into a right and left half by two fissures which pass in
from the middle of the anterior and posterior surfaces,
and penetrate through the greater part of its thickness.
I i Of these two median fissures the anterior or ventral (fig.

'/I * 7, 1) is wider and therefore more distinct than the pos-

terior or dorsal, although it does not, in most parts,
penetrate to more than one-third the thickness of the
cord, while the posterior fissure may reach more than
half-way from back to front. The anterior contains a
fold of the pia mater and also many blood-vessels, which
are thus conducted to the centre of the cord. At the
bottom of this fissure is a transverse N connecting portion
of white substance named the anterior or white com-
missure.

The posterior (fig. 7, 2) is not an actual fissure, for,
although the lateral halves of the cord are quite separate

dorsally, there is not so much a fold of the pia mater between them, as merely a
septum of connective tissue and blood-vessels prolonged from that membrane which



INTERNAL STRUCTURE. ?

passes in nearly to the centre of the cord (posterior septum}. Its position is marked,
especially in the lumbar enlargement and in the cervical region, by a superficial
furrow. At its end is the posterior or grey commissure.

Besides these two median fissures, a lateral furrow is seen on each side of the cord,
corresponding with the line of attachment of the posterior roots of the spinal nerves.
It is named the postero-lateral groove (fig. 7, c, 4). Each lateral half of the cord is

Fig. 7. DIFFERENT VIEWS OF A PORTION

OF THE SPINAL CORD FROM THE
CERVICAL REGION WITH THE HOOTS

OF THE NERVES. Slightly enlarged.
(Allen Thomson. )

In A, the anterior or ventral surface
of the specimen is shown, the anterior
nerve- root of the right side having been
divided ; in B, a view of the right side is
given ; in C, the upper surface is shown ;
in D, the nerve-roots and ganglion are
shown from below. 1, the anterior
median fissure ; 2, posterior median
fissure ; 3, antero-lateral impression,
over which the bundles of the anterior
nerve-root are seen to spread (this im-
pression is too distinct in the figure) : 4,
postero-lateral groove into which the
bundles of the posterior root are seen to
sink ; 5, anterior root ; 5', in A, the
anterior root divided and turned up
wards ; 6, the posterior root, the fibres
of which pass into the ganglion, 6' ; 7,
the united or compound nerve ; 7', the
posterior primary branch, seen in A and
D to be derived in part from the ante-
rior and in part from the posterior root.

divided superficially by the postero-lateral groove into a posterior and an antero-
lateral part. The attachment of the anterior roots, however, subdivides the latter
into anterior and lateral portions.

An antero-lateral groove has sometimes been described in the line of origin of the anterior
roots of the nerves, but usually has no real existence. The fibres of these roots in fact,
unlike the posterior, do not dip into the spinal cord in one narrow line, but spread over a
space of some breadth.

On the posterior surface of the cord, at least in the upper part, there is on each
side of the middle line a slightly marked longitudinal furrow (fig. 11) situated about
one millimeter from the posterior median fissure, and marking off, in the cervical
region, a slender tract, the postero-me&ial column. This sulcus, which is better
marked in some individuals than in others, is termed the postei'ior intermediate
furrow. An incomplete connective tissue septum (posterior intermediate septum)
extends from the furrow into the white substance of the cord. The larger remaining
part of the posterior column is termed the postero-lateral column.




INTERNAL STRUCTURE OF THE SPINAL CORD: RELATIVE PROPORTIONS OF GREY

AND WHITE MATTER.

Grey matter. When the spinal cord is cut across (figs. 8, 11, 14) it is seen that
the grey matter occupies the more central parts, being almost completely enclosed by
the white matter. The grey matter appears in the form of two irregularly crescentid
portions on either side, united across the middle line by the posterior grey commis-
sure before mentioned, so that its section may be compared in shape to the letter H.



THE SPINAL CORD.



The concave side of each lateral crescent faces outward, and in consequence of the
depth of the posterior median fissure the commissure of grey matter joins the crescents