Difference between revisions of "Talk:Book - Buchanan's Manual of Anatomy including Embryology 12"

From Embryology
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ribs. (The movement round the  
 
ribs. (The movement round the  
 
axis A, B resembles the raising of  
 
axis A, B resembles the raising of  
the handle of a bucket.)  
+
the handle of a bucket.)
 
 
 
 
 
 
==CHAPTER XIII DEVELOPMENT OF VASCULAR SYSTEMS==
 
 
 
 
 
Principal Arteries and Veins.
 
 
 
It was shown at the beginning of this book (pp. 51, 91) that the vase
 
system, in its earliest stages, came into existence as the result of the establishn
 
of connections between networks of channels formed on the yolk-sac, in
 
body-stalk, and in the embryonic body; an extension from the body-stall
 
 
 
 
 
 
 
Fig. 670. —Scheme of Earliest Circulatory System. (Founded on Eternc
 
 
 
The lower figure is a diagrammatic section to show position of aortae and umbil
 
veins (UV). Am, amnion; N, neural groove; coe, intra-embryonic coelom
 
 
 
the chorion (where similar channels are possibly formed also) puts tl
 
anastomosing systems into relation with the growing villi.
 
 
 
The primitive circulation would seem to be possible through channels est
 
lished in this way at an early stage in embryonic formation; such might
 
represented schematically as in Fig. 670. In this figure it can be seen t
 
 
 
1116
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1117
 
 
 
 
 
ns (vitelline) pass up the wall of the yolk-sac to reach the posterior part of
 
! embryonic rim, where they join a vein coming from the body-stalk and
 
ming forward to enter the primitive heart-tube. This (C) is a very short
 
)e, doubled in origin, which runs back towards the bucco-pharyngeal area (bp),
 
ing off here two primitive aortcs, which pass back on each side of the area
 
the future membrane, and continue their course caudally to reach the bodylk. As they pass back in the embryo they give off vitelline branches downrds on to the wall of the yolk-sac; later, as the somites form, they will be found
 
give intersegmental branches running dorsally between the somites. When
 
:y reach the chorion they are distributed throughout it and to its villi.
 
 
 
The veins which return the blood in this early circulation must come into
 
stence, of course, with the * arteries,’ and can be said in general terms to
 
 
 
 
 
 
 
 
 
r. 671. — Schemes founded on Conditions in an Embryo of About
 
Twelve Somites, in which the Intra- and Extra-embryonic Ccelomic
 
Cavities are Continuous.
 
 
 
se from the common vascular network as enlargements of its ‘ peripheral ’
 
t, the ‘ central ’ vessels becoming arterial. Thus veins are found extending
 
the heart along the embryonic rim, which receive the blood returning through
 
body-stalk; these veins (uv), are the umbilical veins, which, passing forward
 
ng the margins of the embryonic plate, reach the anterior end of the heart,e in this margin. The vein is shown in black in the figure, where only the
 
sels of the left side are seen; actually there are two primitive aortae and two
 
bilical veins.
 
 
 
The conditions illustrated in the last figure are those present in the embryo,
 
which there are as yet no somites and no body cavity continuous with the
 
ernal coelom. The result of somite formation, with the reversal of the
 
erior end of the embryonic plate, is shown in the next figure (Fig. 671),
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
nt8
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
where the heart is now reversed, and the arterial end points forward, while
 
paired aortae run upwards beside the bucco-pharyngeal membrane and then ti
 
back; intersegmental branches are appearing now. It can be seen now, moreo\
 
that well-defined vitelline veins are reaching the venous end of the heart (n
 
posterior) by passing up the front of the yolk-sac; the earlier posterior ve
 
have disappeared. The splitting of the embryonic rim by the ccelomic extens
 
leaves the vitelline arteries on the splanchnic wall, but puts the umbilical ve
 
in the somatic wall, close to the continuity of this wall with the amnion; thi:
 
shown in the section in Fig. 671.
 
 
 
The paired aortae lie oh the roof of the primitive pharynx, and receive in t
 
situation ‘ aortic arches ’ from the ventrally placed arterial trunk and vessi
 
but behind the pharynx they fuse into a single vessel, which divides again ii
 
two as it approaches the hinder end; these two umbilical arteries pass into •
 
body-stalk.
 
 
 
Development of Principal Arteries.
 
 
 
The arterial end of the heart opens into a dilated arterial sinus, from wh
 
right and left arteries run into the pharyngeal arches, passing through th
 
to join the right and left dorsal aortee which are lying on the roof of the primit
 
pharynx. All told, there are six of these aortic arches (or pharyngeal artei
 
arches) on each side, but they are never present at any one moment in th
 
totality. They appear from before backward, like the mesodermal arches
 
which they lie. The first is possibly the direct descendant of the primitive ao:
 
of its side, passing dorsally round the bucco-pharyngeal membrane; in any c;
 
it is found very early, before reversal is nearly completed. The second aor
 
arch comes a little later. The third, when it appears, seems to take on the din
 
supply of blood to the dorsal aorta at its anterior end, where this vessel is givi
 
branches to the growing neural (brain) tube, and the first and second arcl
 
break up rapidly and disappear, except for their upper and lower ends for soi
 
little time. The fourth arch appears at about the same time as the third, i
 
fifth is very small and short-lived, like the rudimentary mesodermal arch in whi
 
it lies, and the sixth appears behind this. All these arterial arches, then, appt
 
as vessels running ventro-dorsally within their corresponding pharyngeal arch
 
and conveying blood from the ventrally-placed arterial sinus to the dor
 
aortae for distribution.
 
 
 
The presence of the arterial sinus makes the details of further developmt
 
slightly different in the human embryo from those in lower forms, but t
 
differences are only slight, and the main evolution of the adult pattern frc
 
that of the aortic arches is in line with the generalized vertebrate evolutic
 
Such a generalized conception of the system of aortic arches is that (Fig. 6;
 
given by Rathke many years ago, on which the special variations found amo
 
vertebrates can be worked out. The plan shows the arterial arrangemei
 
flattened out, so that, from the arterial stem, right and left ventral aortce r
 
forward (below the pharynx) and give off at intervals the six aortic arches
 
reach the d or sal aortas (above the pharynx). Small branches pass from i
 
sixth arches into the lungs, evidently the future pulmonary arteries, while f
 
anterior end of each dorsal aorta is carried (beyond the scheme) into the cran
 
cavity as a cerebral artery. It may be added here that eight intersegmen:
 
branches arise from each dorsal aorta, the lowest coming off about oppos
 
or just below the fourth arch on each side; seven of these arteries are cervic
 
but the first is cranial, accompanying the hypoglossal.
 
 
 
Disregarding the gill-bearing vertebrates, we may come at once to 1
 
Amniota, where the differences in the various phyla are classifiable easily on t
 
scheme. In the first place it is a general rule that the third aortic arch is devot
 
to supplying the brain, while the fourth becomes the main stem for the sup],
 
of the body. Thus the third arch plus the dorsal aorta in front of it becon;
 
the internal carotid, and the fourth arch becomes the ‘ arch 5 of the syster
 
aorta, from which facts it can be assumed that the dorsal aorta between 1
 
third and fourth arches loses its function, is stretched out, and disappea
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1119
 
 
 
 
 
e matter of the two fourth arches, these persist in the reptiles ; the right one
 
5 the systemic arch in birds, and the left one in mammals.
 
he human conditions are thus shown (Fig. 672) on the scheme as mammalian,
 
first two arches disappear, leaving the ventral aorta opposite them as
 
nal carotid; the third, with the dorsal aorta in front of it, forms the
 
nal carotid; the dorsal aorta behind it, between it and the fourth arch,
 
•pears; the ventral aorta between third and fourth becomes the common
 
id. The original symmetry is disturbed behind this. The fourth left arch
 
s part of the systemic arch, but not the whole of it; the dorsal part of this
 
is formed by dorsal aorta, and the ventral end is the beginning of the ventral
 
; this is represented on the right side by the innominate artery. The right
 
i arch becomes part of the right subclavian; the whole of the left subclavian
 
he terminal piece of the right subclavian are of intersegmental value. Behind
 
 
 
 
 
External Carotid
 
 
 
 
 
 
 
'ig. 672.—Scheme of the Aortic Arches and their Destination.
 
 
 
 
 
e the fifth arches disappear; the left sixth remains as the ductus arteriosus;
 
right sixth disappears except for its ventral end, from which the right
 
lonary artery arises. The common arterial trunk is divided by a septum
 
a dorsal part continuous with the sixth arches, and a ventral part for the
 
ral aortae, and this septum extends towards the heart in a spiral manner,
 
nee the changing relations of pulmonary artery and ascending aorta; this
 
vessel represents the common trunk and its systemic subdivision, binally,
 
right dorsal aorta disappears behind the right fourth arch, so that the rest
 
ie thoracic aorta comes from the fused vessels.
 
 
 
n the human embryo there is no ventral aorta giving origin, as in the scheme,
 
11 the arterial arches, but if we look at the arterial sinus as having the value
 
hortened ventral aortae conjoined, this difficulty disappears. In any case
 
difference is not of much importance, big. 673 gives, in the uppei row,
 
is showing the changes in the human embryo as seen from the left. The
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1120
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
external carotid showing here may be a new formation, but might be some dr<
 
out persisting remnant of the ventral supply to the early anterior arches,
 
the common carotid is either part of the third arch or a drawn-out portion o
 
sinus; it is a very difficult question to decide. The lower figure shows
 
 
 
 
 
 
 
biG. 673. —Plans to show Changes in Human Embryo: Upper Row f
 
 
 
Left, Lower from Right.
 
 
 
Aortic arches and their remnants numbered in Roman figures.
 
 
 
conditions on the right side; the carotid developments are as on the left, but
 
fourth arch is part of the subclavian, and the dorsal aorta disappears behind
 
 
 
In estimating and following the changes which occur in the art<
 
arches in the neck it must be remembered that the head grows forw
 
leaving structures behind it which were originally ventral to it; th
 
what is really meant when the heart, for example, is said to ‘ desce
 
 
 
 
 
 
 
 
 
Fig. 674.— Plans to show how the Embryonic Relations between Ner
 
and Arteries are exhibited in the Adult Condition.
 
 
 
The growth of the head and elongation of the neck straighten out
 
carotids, while the connection of the fourth arch with the trunk keeps it 1
 
the heart.
 
 
 
The relationship between the arterial stems (in the pharyngeal arc]
 
and the nerves of the arches is of interest from the point of view of the nor
 
relations in the adult, and also in cases where the adult conditions are unusu
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1121
 
 
 
 
 
The nerves of the first four arches lie near the grooves in front of them, and
 
thus in front of the arteries which lie more or less in the middle of the mesomal masses. In the sixth arch, however, possibly because its artery runs
 
k to it and is formed relatively late, the artery lies in front of the nerve. In
 
:ases the nerve, having crossed the dorsal aorta on its lateral side, then turns
 
ards to gain the visceral surface; thus they all cross obliquely the lines of
 
ir corresponding arteries, but whereas the first four cross in front of their
 
sels, the last crosses behind it. It follows that, when the neck is elongated
 
the vessels drawn out, they are drawn over the nerves of the arches behind
 
m. Thus the internal carotid (third arch) has the superior laryngeal (fourth arch
 
ve) deep to it, while its own nerve, the glosso-pharyngeal, is superficial to it
 
rsal aorta). The fourth aortic arch (arch of aorta and right subclavian) has the
 
irrent laryngeal deep to it, but this nerve on the left turns first round the
 
mentum arteriosum because it crosses behind that artery in the sixth arch.
 
 
 
The fifth arch, with its artery and nerve, is a tiny and transient formation,
 
only brought into description to complete the various systems. Its artery
 
may be as in Fig. 673, or may arise from the arterial sinus and end in one
 
of the neighbouring arches, or even in the dorsal vessel, or may even arise
 
from the proximal part of the sixth artery.
 
 
 
It disappears early and completely.
 
 
 
The right subclavian artery, as shown in the scheme, has its first part formed
 
n the fourth right aortic arch, and its terminal piece from the seventh cervical
 
srsegmental artery. Between these two there is a portion of the right dorsal
 
ta; there is considerable doubt about the limits of these various parts.
 
 
 
There are two well-known varieties of the right subclavian artery of developntal interest. In one the artery arises from the descending thoracic aorta,
 
the other it arises from the left end of the arch of the aorta; in both cases it
 
ses behind the oesophagus to gain the right side. The first of these varieties
 
ms to be an example of persistence of the right dorsal aorta ; the same explanation
 
iometimes given for the second variety, but with much less probability, and
 
would seem to be more probably an example of anastomosis between the two
 
sal aortw. In both cases the fourth aortic arch has evidently disappeared
 
the right side, and as a result the right recurrent nerve turns round the next
 
h in front— i.e., it runs directly downwards to the lower border of the larynx ,
 
sing deep to the internal carotid.
 
 
 
Intersegmental Branches : Vertebral Artery. —The first intersegmental artery
 
en by each dorsal aorta accompanies the hypoglossal nerve. After this come
 
en cervical intersegmental vessels. These pass back between the somites,
 
ich they supply, and give branches also to the neural formations lying
 
ernal to these. Since the cranial end of the dorsal aorta is about to be stretched
 
: in the internal carotid, and the next part of it is about to disappear, it is
 
dent that, if these intersegmental arteries are to continue to supply the
 
uctures mentioned, they must be provided with another artery of origin,
 
e provision is made very early in their history in the form of a longitudinal
 
istomosis connecting them together some little distance from their origins.
 
 
 
An anastomosis of such a sort is a normal occurrence among the intersegmental vessels in the trunk. Usually it remains very small or disappears,
 
but is seen occasionally in the adult, especially in the thoracic region.
 
In the ordinary way, however, it is only in the cervical region that it enlarges
 
and becomes functionally important.
 
 
 
This longitudinal anastomosis ends caudally in the seventh cervical intermental artery. Thus, when the origins from the dorsal aorta fail, the series
 
vessels obtains its blood from this seventh artery. The longitudinally running
 
'tebral artery is thus made up of these bits of interarterial anastomosis, the
 
ginal intersegmental vessels persisting as its branches. The portion above the
 
as, however, which has a different relation to the issuing nerve, is of another
 
[ue, being the enlarged intersegmental spinal or neural branch.
 
 
 
 
 
 
 
1122
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
The origin of a vertebral artery precedes that of the corresponding subcla 1
 
artery, so that the subclavian artery is originally a lateral branch of the verte
 
artery. As the development proceeds, however, the subclavian artery incre
 
in size, and greatly exceeds the vertebral artery, the latter vessel being :
 
regarded as a branch of the subclavian.
 
 
 
Origin of Left Vertebral Artery from Aortic Arch. —This, the commo
 
additional branch arising from the arch, is probably an example of the
 
sistence (see Fig. 675) of the sixth intersegmental origin from the dorsal ac
 
with the portion of this aorta remaining as far as the level of the fourth ac
 
arch.
 
 
 
The thoracic and abdominal intersegmental arteries have been refe
 
to already in connection with the aorta.
 
 
 
 
 
 
 
Fig. 675. —Development of Cervical, Intersegmental, and Vertebra
 
 
 
Arteries, according to Scheme.
 
 
 
The intracranial prolongation of the dorsal aorta on each side is an exan
 
of the enlargement of a neural branch arising from the beginning of this ari
 
and running dorsally into the paraxial tissue round the brain; the dorsal a<
 
itself lies on the upper in-turned ends of the visceral mesoderm of the arc
 
below the layer of paraxial mesoderm. This terminal neural branch en
 
the paraxial layer beside Rathke’s pouch, and, in the adult, pierces the d
 
mater here. Before reaching this, the internal carotid lies on the roof of
 
tubo-tympanic recess, covered by the otic capsule; much later, this cap:
 
extends its ossification partly round it, enclosing it in the carotid canal, bi
 
portion of the artery, still unenclosed, lies in front of this and crosses (as it
 
in the foramen lacerum) the anterior margin of the recess, the auditory tube,
 
 
 
The ramifications of the cerebral arteries are formed in accorda
 
with the growth of the parts of the brain, which is surrounded by a vasci
 
network from a relatively early stage. These vessels are dealt witl
 
part in the section on the central nervous system.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1123
 
 
 
 
 
•teries of Limbs. —The arteries of the upper limb have been already considered,
 
the lower limb, the accepted views on their development are in large part
 
lptions based on comparative anatomical observations, direct observation
 
» human embryo being an undertaking of great difficulty.
 
 
 
) W er Limb. —At the beginning of the second month the main artery accoms the sciatic nerve, passes deep to the rudiment of the popliteus, and runs
 
:en the primordia of the leg bones to the foot. This ‘ axial ’ vessel is
 
:cted with a small plexus on the extensor aspect of the limb, from which at
 
ir stage the femoral artery will form. As the femoral channel enlarges,
 
axis ’ vessel sends a secondary branch down superficial to the popliteus,
 
hen degenerates above the level of its connection with the femoral; this
 
dary branch divides to form the tibial arteries, anastomosing with the
 
lal interosseous trunk, which has already given off the anterior tibial, and
 
becomes a small branch of this. The inferior gluteal artery, the popliteal,
 
•art of its middle genicular branch, are remains of the original ‘ axis ' supply,
 
 
 
 
 
Fig. 676.— The Venous Trunks of the Septum Transversum of
 
 
 
the Human Embryo (His).
 
 
 
X.X. Upper separated portions of Umbilical Veins
 
R.U.V. Right Umbilical Vein
 
L.U.V. Left Umbilical Vein
 
 
 
V.P. Venous Loops round Gut
 
V.V. Vitelline Veins
 
 
 
the peroneal and perhaps part of the arterial structures in the sole are
 
ed from its interosseous prolongation; the two femoral arteries and the
 
snous branch of the descending genicular artery, when present, are remains
 
e femoral extensor plexus.
 
 
 
Development of the Principal Veins (p. 5 1 )
 
he primitive veins form two groups. One group returns the blood from the
 
sac and the placenta; and the other group returns the blood from the head
 
neck, anterior limbs, body-wall, mesonephric bodies, and posterior limbs,
 
first group comprises: (1) the vitelline veins, in connection with which the
 
il vein is developed; and (2) the umbilical veins. The second group consists
 
) the anterior cardinal or primitive jugular veins; (2) the posterior cardinal
 
;; and (3) the subcardinal veins; they drain into the veins (or ducts) of
 
2r on each side. The veins of each group are arranged in pairs, right and
 
 
 
 
 
J.V. Primitive Jugular Vein
 
:.V. Cardinal Vein
 
V.C. Right Duct of Cuvier
 
/.C. Left Duct of Cuvier
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1124
 
 
 
Sinus Venosus. —This is the venous space made by the confluence of
 
veins of the body; it discharges directly into the common atrium the bloo
 
receives from the veins. It is placed in the septum transversum (pp. 46 and
 
and consists of two ‘ horns,' each of which is made by the junction of the umbili
 
vitelline, and Cuvierian veins of its own side. As described in the developrr
 
of the heart, the right horn is taken up into the right atrium, the left horn becon
 
the coronary sinus. The vitelline veins reach the sinus venosus by rum
 
in the visceral wall to the septum transversum, the others get to the septuir
 
 
 
the body-wall. 1
 
 
 
1. Vitelline Veins and Portal Veins— These veins are developed early,
 
they return the blood from the yolk-sac. They enter the body of the emt
 
along the vitelline duct, and finally open into the sinus venosus after traver
 
the septum transversum. Within the body they ascend parallel with each ot
 
at first in front of, and subsequently on either side of, the duodenal portio
 
the primitive intestinal tube. In the latter region on the caudal side of
 
 
 
 
 
 
 
Fig. 677. _Schemes to show Formation of Portal Vein from Doi
 
 
 
Connecting Loop between the Right and Left Vitelline Veins.
 
 
 
hepatic bud they become connected by three transverse anastomotic ves
 
two of which lie across the ventral aspect of the gut, and one being placed 0
 
dorsal aspect. The first or lowest anastomotic vessel lies on the ventral as
 
of the gut; the second or middle vessel is dorsal to the gut; and the tnir
 
highest, like the first or lowest, is ventral to the gut. This is shown m tne
 
 
 
scheme in Fig. 677. , . ,
 
 
 
By means of these three anastomotic vessels two venous rings—lowe
 
caudal, and upper or cephalic—are formed around the duodenal portion oi
 
primitive intestinal tube, these rings constituting the sinus annularis. t
 
their formation the two divisions of the liver-bud are breaking up into ne
 
cylinders, and these are giving off secondary cylinders. Owing to these ne]
 
developments the vitelline veins cease to communicate directly with tne .
 
venosus. The portions of the vitelline veins above the upper duodenal ve
 
ring (shown in Fig. 676 to proceed from its sides) become surrounded
 
hepatic cylinders, and invaded by the secondary cylinders. In this ma
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1125
 
 
 
 
 
portions of the vitelline veins are freely subdivided into blood-channels,
 
 
 
1 are known as sinusoids (Minot). These sinusoids form a network which
 
>ies the meshes of the network formed by the branches of the hepatic cylinders,
 
veins which convey blood from the upper duodenal ring to the hepatic
 
oids are now known as the vence advehentes, and they become the right and
 
\ivisions of the portal vein. The veins which carry the blood from the
 
tic sinusoids to the sinus venosus are known as the vence revehentes, and they
 
ne the hepatic veins.
 
 
 
runk of the Portal Vein. —The portions of the two vitelline veins which
 
id in front of the primitive duodenum lie close together and parallel with
 
other. These portions fuse for a short distance, and form a single venous
 
, which opens into the first, or lowest, ventral anastomotic vessel, or, in
 
■ words, into the lower part of the lower duodenal venous ring. This short
 
receives the veins of the primitive intestinal tube, and it forms the root
 
e portal vein. The primitive portal vein, therefore, receives its blood from
 
tie yolk-sac, and (2) the primitive intestinal tube within the abdomen. The
 
r ventral anastomosis and the right vein immediately above it quickly
 
 
 
ipear (Fig. 677). . .
 
 
 
is the yolk-sac atrophies the portions of the vitelline veins between it and
 
commencement of the portal vein also atrophy, and the tributaries of the
 
il vein gradually assume their condition in adult life. The vitelline vein,
 
ever, does not disappear for a considerable time, but remains as a free cord
 
,4) passing out of the umbilicus up to the entrance of the umbilical loop into
 
belly. #
 
 
 
"he following parts of the sinus annularis, or double duodenal ring, undergo
 
phy (see Fig. 677):
 
 
 
1. Right half of lower ventral anastomotic vessel.
 
 
 
2. Right half of lower duodenal ring.
 
 
 
3. Left half of upper duodenal ring.
 
 
 
rhe following parts of the sinus annularis persist:
 
 
 
1. Left half of lower ventral anastomotic vessel.
 
 
 
2. Left half of lower duodenal ring.
 
 
 
3. Middle or dorsal anastomotic vessel.
 
 
 
4. Right upper half of duodenal ring.
 
 
 
5. Upper ventral anastomotic vessel.
 
 
 
These persistent portions, with the exception of the upper ventral anastomotic
 
el, form the greater part of the trunk of the portal vein, the upper ventral
 
stomotic vessel represents a part of the left division of the portal vein.
 
 
 
The portal vein has originally a spiral relation to the duodenal portion of
 
primitive intestinal tube—that is to say, it winds round the left side and
 
sal aspect of the duodenum, and then appears on its right side.
 
 
 
Divisions of the Portal Vein.— These are connected with the upper duodenal
 
ous ring. As previously stated, the veins which convey the blood from this
 
\ to the hepatic sinusoids are known as the vence advehentes, right and lefL.
 
; right division of the portal vein is formed by the right vena advehens, which
 
ings from the right half of the upper duodenal venous ring, dhe left division
 
firmed by (1) the upper ventral anastomotic vessel, and (2) the left vena
 
ehens
 
 
 
Umbilical Veins.— The two umbilical veins return the blood from the placenta
 
the sinus venosus. They are of small size during the period of the vitelline
 
mlation, but become enlarged as the placenta gradually forms, the two
 
ns unite and form a single trunk within the umbilical cord At the umbi icus
 
5 trunk enters the body of the embryo, and immediately divides into wo
 
bilical veins, right and left, which traverse the septum transversum and open
 
n the sinus venosus. As they traverse the septum transversum ey are
 
se to the developing liver.
 
 
 
 
 
 
 
1126
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
The left umbilical vein enlarges fairly rapidly, that on the right s
 
atrophying more slowly. Just before the 5 mm. stage the left vein effect
 
capillary junction with the left vitelline vein on the caudal aspect of the sept
 
transversum— i.e., on the caudal or visceral surface of the small liver. 1
 
connection between the umbilical and vitelline veins of the left side enlar
 
very rapidly, thus making the vessel on the visceral aspect of the liver wt
 
is usually referred to as the ‘ left umbilical vein ’; actually, of course, it is a vite
 
umbilical anastomosis, and the real umbilical vein passes up still beside the lb
 
but dwindles rapidly, and cannot be certainly traced after a fairly short inter
 
When the anastomotic vessel collapses, after birth, it makes the ligament
 
teres of the liver.
 
 
 
In this region part of this fibrous cord lies in the abdominal wall ;
 
part below the liver; the first of these parts is the true umbilical vein, w
 
the second is the vitello-umbilical anastomosis.
 
 
 
 
 
 
 
Fig. 678. —Scheme to show Early Circulation in Liver, and Direct
 
 
 
of Ductus Venosus.
 
 
 
The right umbilical vein also seems to develop some similar anastom
 
with the vitelline system, but owing to the atrophy of the vein the anastom
 
does not become evident.
 
 
 
The anastomosis of the left umbilical vein with the left vitelline vein oc
 
at the level (in this last vessel) of the upper junctional loop with its fellow, as sh
 
in Fig. 677. As already stated, this upper loop becomes embedded in the lb
 
and forms a part of the left portal vein, whence the fact that the ligamen;
 
teres, buried between two lobes of the liver, runs to join the left division of
 
portal vein.
 
 
 
There is possibly some connection between the entrance of the umbi
 
blood at this level and the disappearance of the original vitelline
 
(A in Fig. 677) between this and the next anastomotic loop, the vol
 
of blood from the larger vein prohibiting entrance of vitelline blood it
 
below.
 
 
 
Ductus Venosus. —Blood from the left umbilical vein enters the live; j
 
increasing amount as the placenta grows, and before long there becomes evil
 
a dilatation into a large vessel of the vascular spaces in the liver lying bet\i
 
the point of entrance of the blood and that of its discharge into the infc
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1127
 
 
 
 
 
, cava. This vessel is termed the ductus venosus (or ductus Arantii). It
 
nds from the left portal vein, which has been formed from the uppermost
 
line loop and receives (Fig. 678) the vitello-umbilical anastomotic vessel;
 
,sses upwards and to the right, reaching the terminal part of the right hepatic
 
nage into the inferior vena cava, which becomes dilated to form its terminal
 
*
 
 
 
✓ •
 
 
 
After birth, when the placental circulation has ceased, the ductus venosus
 
becomes a fibrous cord, the ligamentum venosum.
 
 
 
 
 
minute portion of the lumen
 
he left umbilical vein remains
 
ious within the ligamentum
 
> of the liver. This pervious
 
ion communicates at the liver
 
. the left division of the portal
 
, and at the umbilicus it is
 
lected with the epigastric veins
 
:he abdominal wall. It thus
 
is a channel of communication
 
yeen the left division of the
 
al vein and the systemic veins
 
tie anterior abdominal wall. In
 
pervious portion the blood can
 
towards the umbilicus. This
 
stomosis between the portal and
 
emic circulations accounts for
 
enlargement of the veins of the
 
irior abdominal wall in cases of
 
:al obstruction within the liver.
 
 
 
2. The cardinal system of veins
 
iprises several vessels on each
 
;, which ultimately drain their
 
d into the sinus venosus through
 
right and left veins {or ducts) of
 
ier. A general idea of their
 
ribution can be gained from
 
. 679A. A large vessel, the primijugular or anterior cardinal (or
 
cardinal), drains the cranial part
 
the body, beginning in associa1 with the venous drainage of
 
brain, and passing back through
 
cervical region, where it re/es intersegmental veins, includthe subclavian (S). The posterior
 
dinal runs caudo-cranially, being
 
med in association primarily with
 
mesonephros (W) and receiving
 
srsegmental veins. The posterior
 
1 anterior cardinal veins join to
 
m the ‘duct of Cuvier,’ situated
 
the septum transversum, cranial
 
the liver ('LL and thus
 
 
 
 
 
 
 
Fig. 679.—Scheme of Main Venous
 
Drainages of Embryo.
 
 
 
SV, sinus venosus; DC, duct of Cuvier;
 
PJ, anterior cardinal or primitive jugular; C, posterior cardinal; UV and VV,
 
umbilical and vitelline veins.
 
 
 
 
 
(L), and thus running
 
ctly into the sinus venosus. # . .
 
 
 
rhe anterior cardinal or primitive jugular veins are two m number—right
 
left—and return the blood from the head, neck, and fore-limbs. Each vein
 
>ists of two parts—intracranial and extracranial. The intracranial part gives
 
, directly and indirectly, to the intracranial sinuses, whilst the extracranial
 
‘ becomes the internal jugular vein. The intracranial part is known as the
 
 
 
 
 
 
 
 
 
1128
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
principal or primary head vein. This vein at its anterior end is on the inner
 
of the trigeminal ganglion; passing backwards from this point, it lies just al
 
the outer part of the tubo-tympanic recess lateral to the facial ganglion and f
 
nerve, and reaches behind this the outer side of the glosso-pharyngeal and va
 
 
 
Its different relations with the several cranial nerve-roots indicate
 
it has been produced from two venous trunks, connected between the rc
 
these trunks are represented in lower vertebrates by the vena capitis late
 
and vena capitis medialis.
 
 
 
At its anterior end the principal head vein receives on each side the anti
 
cerebral veins, a plexiform set of vessels draining the mid-brain, the back ol
 
fore-brain, and the optic outgrowth. The anterior cerebral veins anastoi
 
 
 
 
 
 
 
Fig. 679A.— To show Main Trunk Veins in Young Embryo.
 
 
 
with their opposite fellows dorsally between the two small cerebral vesic
 
thus forming the rudiment of the superior sagittal sinus, which is elongated
 
the vesicles grow backwards (Fig. 680).
 
 
 
Between the trigeminal and facial ganglia the principal vein receive
 
middle cerebral vein or plexus, draining the front limb of the pontine flex
 
and anastomosing with the anterior veins.
 
 
 
A plexiform posterior cerebral vein opens into the principal head vein betw
 
the facial and glosso-pharyngeal ganglia; it drains the back of the poni
 
flexure and the myelencephalon. These details are shown in Fig. 680, f
 
scheme.
 
 
 
As the cerebral vesicles grow backwards, the anterior plexus becomes n
 
closely connected with the middle set, and its blood is returned by this set
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS 1129
 
 
 
asing amount. Ultimately the superficial middle cerebral vein, the sphenotal sinus, and the ophthalmic veins, are the only vessels left of the original
 
isive anterior venous plexus. The cavernous sinus is the persisting anterior
 
 
 
>f the principal head vein (second figure).
 
 
 
he middle cerebral vein, however, has in the meantime formed a secondary
 
’ding channel with the posterior cerebral vein, this channel lying above the
 
capsule and beside the pontine flexure within the developing cranium,
 
the blood which has already been seen to be derived from the anterior
 
1 into the middle set is carried back through this new channel, and the
 
lal principal vein in its intermediate part gets smaller and disappears, the
 
1 from its anterior end (cavernous sinus) now passing up the lower portion
 
e original trunk of the middle cerebral vein to reach the new channel, through
 
h it passes to the hinder part of the posterior vein, along which it runs down
 
-enter the hinder part of its old vessel, and thus leaves the cranium with
 
r agus.
 
 
 
 
 
 
 
680.— Semi-schematic Figures to show Changes in Venous Drainage
 
of Brain (founded on Streeter’s Figures).
 
 
 
 
 
Continuing their growth backwards (third figure), the cerebral vesicles carry
 
elongating longitudinal sinus with them, so that it ultimately comes to open
 
*th figure) into the posterior set of veins, from the lower part of which the
 
al sinus is made. The middle cerebral plexus is covered over by the growing
 
des, but is represented in the great cerebral veins and their tributaries, the
 
ar veins being also remnants of their connections with the anterior venous
 
The straight sinus is a new connection (arising on the dorsal side of the
 
-brain flexure when this closes) between the middle and posterior sets of
 
s. The inferior petrosal sinus represents the secondary re-establishment
 
direct connection between the original and persisting anterior and posterior
 
1 of the primary head vein, but the new channel is within the cranium, and is
 
 
 
a reappearance of the old vein. .
 
 
 
die extracranial part of the anterior cardinal vein, after the obliteration of
 
vena capitis lateralis, commences at the jugular foramen, whence it extends
 
lad, receiving in its course the cervical inter segmental veins. In the vicinity
 
te sinus venosus it meets the posterior cardinal vein of its own side, with which
 
lites. The venous trunk thus formed is called the duct of Cuvier, of which
 
e are two—right and left. These two ducts pass transversely, one on either
 
 
 
 
 
 
 
ii3o
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
side, to the sinus venosus, into which they open. At this stage the sinus venc
 
also receives the vitelline and umbilical veins of each side. The ducts of Cu
 
are in the septum transversum (see pp. 46 and 52).
 
 
 
As the heart descends from the region of the fore-gut, the ducts of Cu
 
become vertical, and are in line with the anterior cardinal veins. When
 
sinus venosus becomes merged into the right atrium, and the heart undergo^
 
slight rotation from right to left, the left duct of Cuvier is placed dorsal to
 
left atrium before opening into the right atrium.
 
 
 
Each anterior cardinal vein is joined, near its caudal extremity, by
 
corresponding subclavian vein.
 
 
 
Close to the junction the subclavian vein receives the external jugular V
 
This vein is a secondary formation, and is probably derived from a poste
 
auricular vein, being subsequently reinforced by a pre-auricular vein.
 
 
 
 
 
 
 
F IG . 681.— The Venous Plexus lying between the Two Primitive.Jugui
 
 
 
JUST BEGINNING TO FORM THE LEFT INNOMINATE CONNECTION (19 MM.)
 
 
 
A transverse anastomotic vessel is now formed, called the transverse jug
 
vein. It is developed (Fig. 681) in the ventral plexus connecting the
 
primitive jugulars. It extends from the junction of the left anterior cardinal
 
left subclavian veins to the right anterior cardinal vein at a point a little b<
 
the place where it receives the right subclavian vein. This transverse jug
 
vein, which extends obliquely from left to right, with a downward inclmal
 
gives rise to the left innominate vein. The venous blood from (i) the left
 
of the head and neck and (2) the left fore-limb now passes through the
 
innominate vein into the permanent superior vena cava. The right innomi
 
vein is formed by the short portion of the right anterior cardinal vein w
 
intervenes between the place where it receives the right subclavian vein and
 
place where the transverse jugular vein joins it. The portion of the right ante
 
cardinal vein, which lies immediately below the place where the transverse jug
 
vein joins it, forms the upper or extra-pericardial part of the permanent sup(
 
vena cava —that is to say, the part above the point where the vena azygos o]
 
into it. The lower or intrapericardial part of the superior vena cava is develc
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
n 3 J
 
 
 
 
 
. the right duct of Cuvier. The permanent superior vena cava therefore
 
isents (i) the lower part of the right anterior cardinal vein, and (2) the
 
; duct of Cuvier.
 
 
 
'he portion of the left anterior cardinal vein immediately below the left
 
unity of the transverse jugular vein forms the upper part of the left superior
 
costal vein, thus accounting for the ending of that vein in the left innominate
 
which, as stated, is formed by the transverse jugular vein.
 
 
 
'he left duct of Cuvier undergoes partial obliteration. Its terminal part,
 
l with the left lateral cornu of the sinus venosus, gives rise to the coronary
 
5. The portion next the terminal part also persists in the form of a very
 
ite vein, called the oblique vein of left atrium, which lies over the posterior
 
ct of the left auricle. The obliterated portion is represented by the vestigial
 
 
 
 
 
 
 
bo. 682. — Sectional Plans to illustrate Venous Modifications in
 
Cardinal Systems in the Middle Region of the Abdomen.
 
 
 
 
 
of left atrium, which is a small triangular fold of the serous pericardium in
 
t of the root of the left lung.
 
 
 
‘osterior Cardinal Veins. —These are two in number—right and left—and
 
return the blood from the mesonephroi, body-wall, and hind-limbs. They
 
>n either side of the aorta dorsal to the mesonephroi. The caudal end of
 
vein receives the inferior gluteal vein, which is the primitive vein of the
 
-limb. A little above this point it is joined at a later period by the external
 
vein, which has now been developed.
 
 
 
die cephalic end of each posterior cardinal vein joins the corresponding
 
nor cardinal vein, and the trunk so formed is the duct of Cuvier.
 
 
 
Amongst other tributaries, the posterior cardinal veins receive intersegmental
 
s, such as the lumbar and intercostal veins, and veins from the intermediate
 
mass.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1132
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
The posterior cardinal veins lie on the dorsal side of the mesonephroi,
 
cardinal veins run longitudinally on the inner and ventral sides of the mesonep
 
within which the cardinals and subcardinals are connected by anastomt
 
veins; they run into the cardinals at the two ends of the bodies. A third sy:
 
of veins develops on the dorsal side of the cardinal on each side, forming a pi
 
round the groups of sympathetic ganglion cells as these grow down from
 
posterior root ganglia. As this ‘ periganglionic ’ system enlarges with the gn
 
and extension of the nervous masses, it forms an extensive plexus, joi
 
laterally with the inter segmental veins , ventrally with the cardinal, and wit)
 
subcardinal internal to this. In many animal forms this venous system constil
 
a definite supracardinal vein on each side, with retro-aortic anastomoses, but
 
a development is not found in the human subject, and retro-aortic conned
 
are few and far between; hence it seems convenient to use the term
 
ganglionic as representing the human condition or modification of the supracarc
 
formations.
 
 
 
Progressing with the ganglionic and nervous growth, the perigangli
 
plexus extends forwards and inwards on each side as a juxta-aortic plexi
 
veins, and from this a pre-aortic plexus is quickly formed. The pre-ai
 
extension is seen in the thorax, and is very marked in the abdomen belov
 
level of the superior mesenteric artery; between these two parts the growt
 
the suprarenal and its association with the sympathetic and the formatio
 
the diaphragmatic crura seem to interfere with the formation of the pre-ai
 
plexus. The part of the left renal vein that lies in front of the aorta is made 1
 
this plexus below the superior mesenteric artery, putting the two subcard]
 
in connection owing to the extensive anastomoses between these and the gny
 
supracardinal vessels. Caudally, the aorta divides into two umbilical arte
 
and the supracardinal plexus is carried down on each side dorsal to these arte
 
extensions from this plexus here on the sacrum appear to be the origin of
 
left common iliac vein in this part.
 
 
 
The sectional plans shown in Fig. 682 will be of use probably in enabling
 
reader to follow the complicated changes going on in these different sets of ves
 
In I are shown the two mesonephric formations in section, beside the mei
 
mesentery. On the left an intersegmental vein (in) is seen opening into
 
posterior cardinal (C), which is situated on the dorsal and lateral side of
 
mesonephros, and is joined by a plexus within that body with the subcarc
 
(SC) in the medial part of the body near the base of the mesentery. On the r
 
side is shown a stage a very little later, in which a plexus of minute veins is
 
surrounding the sympathetic neuroblasts which have descended from the ne
 
crest; this ‘ periganglionic ' plexus is connected with the intersegmental \
 
and also (although this is not shown) actually with the posterior cardinal,
 
plexus, following the extension of the neuroblasts, shows a rapid ventral extern
 
as seen in II, towards the ventral aspect of the aorta, over which (III) it pa
 
and joins with the plexus of the other side. It is to be noted that this exten
 
is correlated with a marked anastomosis with the subcardinal, as seen in III,
 
in the same figure is shown the evident tendency of the intersegmental vei:
 
transfer its drainage to the plexus—that is, in general terminology, to trar
 
it to the supracardinal vessels. The connection with the subcardinals ii
 
marked that the transaortic plexus appears very soon to be intersubcardi
 
as is suggested in III, and becomes intersubcardinal in actuality before
 
(IV), as the original anastomosis with the plexus begins to atrophy or break
 
This break is favoured by the establishment of longitudinal anastomoses betv
 
the successive ‘ plexus ' units, so that their blood is now carried cranially
 
longitudinally running and definite supracardinal vessel, which only communic
 
with the subcardinals here and there. In the meantime the intersegme
 
veins have come to drain altogether via the ‘ plexus ’ into this longitud
 
vessel, and the posterior cardinal (in this abdominal region) disappears (c) f
 
the scene. These changes are shown in IV. The last figure (V) is a schem
 
illustrate the age-changes described above. The intersegmental veins in f
 
younger stages (below) are joined by a plexus with the subcardinal (SC), bu
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
1133
 
 
 
 
 
become older (higher) they establish a longitudinal drainage of their own
 
lose their connections with the subcardinal, except, for example, where the
 
renal vein is made.
 
 
 
'he changes just described are of the nature of general changes; their modificai and extensions, as shown in the development of the inferior vena cava
 
azygos systems, remain for description.
 
 
 
humming up these matters from the viewpoint of the respective cardinal
 
it may be said that the posterior cardinal is formed on each side in association
 
the mesonephros, which it drains, and also receives intersegmental veins,
 
he mesonephros degenerates the cardinal vein gets smaller, and disappears
 
pletely in the abdomen. Its intersegmental tributaries have previously
 
. transferred to the supracardinal (periganglionic) system. Changes in the
 
ax will be dealt with later.
 
 
 
die subcardinal is an accessory channel in the inner part of the mesonephros,
 
extent corresponds with this body, and it joins the main cardinal at its
 
smities. It is connected with this vein by a venous plexus throughout its
 
se, and also secondarily with the supracardinal system and its derivatives;
 
of these last is the left renal vein in front of the aorta, which in this way
 
mes practically an intersubcardinal connection.
 
 
 
rhe supracardinal system is not developed so completely in man as in most
 
le other mammals; its early state constitutes a ‘ periganglionic ’ system, but
 
term, it must be understood, is only a descriptive word applicable to the human
 
yo, and indicates its supracardinal arrangements. The veins of this system
 
lorsal to those described above, with which they are connected by free
 
.tomosis. They take over secondarily the intersegmental drainage, allowing
 
posterior cardinals to disappear, and they develop a longitudinal drainageel of their own, so that their contained blood is not (or is only in part) carried
 
the subcardinal; at the upper end, however, this longitudinal vessel opens
 
the subcardinal, as will be seen when treating of the thoracic vessels,
 
rhe compound systems of cardinal veins, as shortly described above, are
 
metrically placed on the right and left sides, in the abdominal and (future)
 
acic parts of the embryo. The development of the suprarenal glands, of
 
liver, and of the diaphragmatic structures altogether breaks the continuity
 
le systems, which can now be said to have thoracic and abdominal developts only indirectly connected. The abdominal development is concerned
 
he formation of the inferior vena cava and its associated vessels, while the
 
*os and left superior intercostal systems are produced from the thoracic
 
dopments; these vessels, therefore, can be considered at once.
 
 
 
 
 
Development of the Inferior Vena Cava.
 
 
 
The inferior vena cava, as regards its development, consists of two divisions
 
>wer or postrenal, and upper or prerenal.
 
 
 
These descriptive names are given to the two parts because it is at the
 
level of the left renal vein, which has been seen to be practically intersubcardinal, that the developmental values of the parts of the vein .change ;
 
the ‘ renal' term, therefore, applies to the venous level, and not necessarily
 
to the kidney itself.
 
 
 
Below the level of the left renal vein, the inferior vena cava is formed from the
 
it longitudinal vessel of the supracardinal system, which receives the intermental (lower lumbar) veins of the right side; a similar formation is found
 
■he left side. The posterior cardinals disappear when the intersegmental veins
 
their terminations, and the subcardinals also atrophy, as the mesonephros
 
ins to move down, only retaining the drainage of the gonad at this level;
 
s the supracardinal alone is left to carry on the drainage of the body-wall,
 
Further changes usually occur on the left side, where the longitudinal vessel
 
supplanted by a deeper longitudinal channel connecting the intersegmental
 
 
 
 
 
 
 
H34
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
veins on the transverse processes, deep to the psoas. Thus the more superb
 
vessel disappears; but it occasionally persists as a left inferior vena cava, extend
 
up to the left renal vein (see Fig. 684).
 
 
 
Sometimes the retro-aortic anastomosis, which is a feature of the suf
 
cardinal system in other forms, may make a partial appearance in the hun
 
individual, when one or more lower left lumbar veins will pass behind
 
aorta to empty into the inferior vena cava.
 
 
 
Above the level of the left renal vein the subcardinals on each side lie in fr
 
of the suprarenal glands, round the outer sides of which the posterior cardii
 
course cranially. Before long the right subcardinal establishes a commumcat
 
 
 
 
 
 
 
Fig. 683.— Cardinal and Subcardinal Veins, etc.
 
 
 
(Frederick T. Lewis, in the American Journal of Anatomy.)
 
 
 
with the veins (hepatic) emerging from the dorsal aspect of the liver; this C(
 
munication is situated in the right-hand part of the common dorsal mesentf
 
This junction, enlarging steadily, provides a new and direct channel by which
 
blood in the right subcardinal can reach the heart, and the left renal, ahead)
 
position, affords a means by which that from the left subcardinal can '
 
advantage also of the new channel. Thus the prerenal portion of the inte.
 
vena cava is of subcardinal origin from the entrance of the left renal vein to
 
relation with the suprarenal gland, where it receives the suprarenal vein.. Ab
 
this it is formed by the hepatic anastomosis and the common hepatic vein, wi
 
 
 
The supracardinal system-which empties itself fundamentally (w.
 
possible) into the subcardinal—forms the lower part of the main vein, but as s
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
ii35
 
 
 
 
 
ssible— i.e., where the subcardinal persists—opens into it. Thus the cony of the great vein is effected.
 
 
 
le kidneys, growing cranially, lie among the veins of the supracardinal
 
n, and drain into them. Thus the right renal vein is altogether supra ml in value, and joins the longitudinal supracardinal vessel as this reaches
 
bcardinal ending, thus a very little below the level of the left vein. The
 
snal vein, at its renal end, is of the same value as the whole of the right vein,
 
:s transaortic portion is not represented on the right side; it passes through
 
 
 
 
 
 
 
Fig. 684. —Schemes to show 1 Formation of Inferior Vena Cava.
 
 
 
 
 
ardinals (Sub) are plain; supracardinals (Sup) black; posterior cardinals
 
are not shown, as they are not concerned in the formation.
 
 
 
In A the supracardinal system is establishing its longitudinal vessel on
 
?ach side, and so communicates with subcardinal. Subcardinals pass
 
aeyond suprarenals (dotted ovals) and there is no connection with the
 
aepatic veins (H). They are joined by a transaortic (dotted) junction, and
 
receive veins (G, G) from the gonads.
 
 
 
In B the supracardinal no longer communicates with subcardinal, except
 
it R; here the renal vein is placed on each side. Subcardinals accordingly
 
iegenerate below entrance of gonad veins. Right subcardinal has now
 
diected a junction with hepatic veins behind liver.
 
 
 
In C any upper continuation of subcardinal above suprarenal is cut off
 
3 y diaphragm. Final values of parts of I.V.C. are apparent. The ascending
 
supracardinal (X) on left is replaced by the deeper (Y). The junctional part
 
)f left common iliac is an intersupracardinal (periganglionic) formation.
 
 
 
 
 
tion of the subcardinal, where this remnant exists to receive the left supraand left spermatic or ovarian veins.
 
 
 
he right and left veins of the gonad drain from the beginning into the
 
'rdinals, and thus, in the adult, reach the renal level because there is no
 
ordinal remaining below this.
 
 
 
he left suprarenal vein is probably a remnant of the left subcardinal, correcting with the part of the vena cava formed by the subcardinal above the
 
level; the current of blood in it, however, is reversed.
 
 
 
he posterior cardinal vein, having lost its intersegmental branches, disappears
 
the abdomen by the middle of the second month, having taken no part in
 
'rrnation of the inferior vena cava.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1136
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Thoracic Cardinal Formations.
 
 
 
The prolongation of the three cardinal systems into the thorax from
 
abdomen is interrupted first by the rapid enlargement of the suprarenal gla
 
This particularly affects the subcardinals, but these glands still, for a little i
 
discharge some of their blood by small veins into the thoracic parts of the
 
cardinals; soon, however, the extension of the diaphragm, over and be
 
them, cuts them off finally from this way of discharge and leaves them onl)
 
abdominal subcardinals for drainage.
 
 
 
The terminal piece of the posterior cardinal remains on both sides,
 
persisting portion is the part above the entrance of the subcardinal, exten
 
 
 
 
 
 
 
 
 
Fig. 685.— Schemes of Cardinal Systems in the Thorax.
 
 
 
On each side upper part of posterior cardinal (PC) persists. Longituc
 
supracardinal (Sup), connected at first with subcardinal (Sub), only ret
 
ultimately its terminal opening into this; thus this extreme terminal f
 
of subcardinal persists, the rest of subcardinal and of postcardinal
 
appearing below this point. On left side the original symmetry is fur
 
broken up, and retro-aortic junctions cross to right supracardinal.
 
 
 
A is early condition, B the final state. VC, duct of Cuvier; PJ, primi
 
jugular or anterior cardinal.
 
 
 
from this to the duct of Cuvier. The extreme terminal bit of the subcard
 
also persists, joining the posterior cardinal; immediately below this tern
 
section the longitudinal supracardinal vessel joins the subcardinal, and the
 
of the subcardinal disappears. This junction of the two veins corresponds r
 
or less with the entrance of the sixth thoracic intersegmental vein into the
 
of the supracardinal longitudinal vein. These details will be followed r
 
easily, perhaps, with the aid of the diagrams in Fig. 685.
 
 
 
On the right the azygos vein is formed, below the sixth intercostal level, 1
 
supracardinal elements; at this level a very short ring of subcardinal come
 
and above this it is persistent posterior cardinal.
 
 
 
On the left the conditions are at first symmetrical and similar, but as the
 
innominate vein forms and the intersupracardinal junctions appear behind
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
ii37
 
 
 
 
 
, the system is broken in variable ways. The termination of the posterior
 
tal is in the left superior intercostal vein, but the terminal piece of this is
 
true jugular (anterior cardinal). The lower hemiazygos is always supralal.
 
 
 
Development of the Lymphatic System.
 
 
 
ie lymphatic system consists of lymphatic vessels and lymphatic glands
 
des. There is also lymphoid or adenoid tissue, as in the thymus body,
 
tioid follicles and villi of the intestinal mucous membrane, lymphatic
 
es of the spleen, palatine tonsils, and pharyngeal tonsil. There are two
 
5 in the development of the lymphatic system—primary and secondary.
 
irimary stage is concerned in the formation of lymph-sacs, and the secondary
 
consists in the formation of lymphatic vessels and lymph-glands.
 
fmph-Sacs. —There are two pair of lymph-sacs and two single sacs, as
 
vs:
 
 
 
1. Jugular (2).
 
 
 
2. Retro-peritoneal (1).
 
 
 
3. Cisterna chyli (1).
 
 
 
4. Posterior (2).
 
 
 
pinions differ as to the development of these lymph-sacs. The view of
 
nee R. Sabin will be stated first. According to this lady the sacs are
 
oped as sproutings from the endothelial lining of veins, and this constitutes
 
rimary stage in the development of the lymphatic system,
 
lgular Sacs. —The jugular lymph-sacs, right and left, are the first to appear,
 
is situated on the outer side of the lower part of the primitive anterior
 
nal vein, which becomes the internal jugular vein. It is formed from part
 
capillary venous plexus, connected in early life with the anterior cardinal
 
A large part of this plexus disappears, whilst the connection of the
 
inder with the anterior cardinal vein is severed. There thus results a
 
died collection of capillaries, lined with endothelium and in close proximity
 
e outer side of the lower part of the anterior cardinal vein. These capillaries
 
ne dilated, and subsequently join to form the jugular lymph-sac of each side,
 
h is lined with endothelium, and which establishes a fresh connection with
 
ower part of the anterior cardinal vein, where it is joined by the subclavian
 
a valve being formed at the venous junction by a protrusion of part
 
ie lymph-sac at the place of junction. The jugular sac of each side is
 
ected externally with peripheral lymphatic vessels which extend to the
 
, neck, and fore-limb bud of the same side. The caudal end of the left sac
 
mes connected with the thoracic duct, whilst the caudal end of the right
 
becomes connected with the right lymphatic duct. The dorsal part of
 
sac becomes converted into a plexus of lymphatic vessels, from which
 
is of lymph-glands are developed.
 
 
 
tetro-peritoneal Sac. —The retro-peritoneal or pre-aortic lymph-sac is single,
 
is formed from a capillary venous plexus in the root of the mesentery, which
 
ns is connected with the great pre-aortic transverse anastomotic vessel which
 
nds between the two subcardinal veins. The capillary plexus in the root
 
tie mesentery becomes converted into a lymph-sac, without any venous
 
tection, and this constitutes the retro-peritoneal sac, which establishes a
 
munication with the cisterna chyli, and through it with the thoracic duct,
 
ultimately replaced by a plexus of lymphatic vessels, and from this plexus
 
ns of lymphatic glands are developed which lie along the ventral aspect of
 
abdominal aorta. From the retro-peritoneal sac lymphatic vessels pass
 
in the mesentery along the branches of the superior mesenteric artery, and
 
e form another lymphatic plexus, from which the mesenteric lymphatic
 
leal) glands are developed. Subsequently lymphatic (lacteal) vessels enter
 
wall of the small intestine.
 
 
 
’osterior Sacs. —The sciatic lymph-sacs, right and left, are developed from
 
llary venous plexuses in connection with the two primitive iliac veins. On
 
 
 
72
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1138
 
 
 
either side the sac extends from near the caudal end of the cisterna chyli alo
 
the outer side of the primitive iliac vein. It ultimately becomes convert
 
into lymphatic glands.
 
 
 
Cisterna Chyli .—The cisterna or receptaculum chyli is a single sac, situat
 
at the caudal end of the thoracic duct. It is developed from, and replaces
 
venous plexus. The thoracic duct connects the cisterna chyli with the 1
 
jugular lymph-sac, and the cisterna chyli communicates with each poster
 
sac. From each jugular sac a vessel grows caudalwards. On the right si
 
this vessel constitutes the right lymphatic trunk, and on the left side it forms 1
 
thoracic duct. As the thoracic duct approaches the developing aortic arch
 
divides and gives rise to two thoracic ducts, which embrace that arch and th
 
pass to join separately the cisterna chyli opposite the mesonephroi. Subsequen
 
these two ducts fuse, and one duct is formed.
 
 
 
The thoracic duct is developed from a series of venous capillaries, origina
 
having a connection with veins.
 
 
 
Lymphatic Vessels. —The formation of these vessels, along with that
 
ymph-glands, constitutes the second stage in the development of the lympha
 
 
 
 
 
Afferent Lymphatics
 
 
 
 
 
 
 
Fig. 686.—Diagrammatic Section of Lymphatic Gland (Sharpey, fr
 
 
 
Quain).
 
 
 
system. According to Sabin, the lymphatic vessels are formed from the en
 
thelial lining of the lymph-sacs, whilst the lymph-glands are. developed ft
 
plexuses of lymphatic capillaries. The development of the thoracic duct, as stat
 
takes place from several groups of venous capillaries. It is the largest lympha
 
vessel, and it connects the cisterna chyli with the left jugular sac.
 
 
 
The lymphatics derived from the jugular lymph-sacs pass to the head, ne
 
and fore-limb buds; those from the posterior lymph sacs extend to the hi]
 
limb buds; and those from the retro-peritoneal (mesenteric) lymph-sac en
 
the mesentery, within which lymph-glands (mesenteric) are developed
 
connection with them. From these mesenteric glands, in succession, m
 
lymphatic vessels pass to the intestinal tube.
 
 
 
The other view of the development of the lymphatic system, held by Hu
 
ington amongst others, is that the connection of the lymphatic vessels with
 
venous system is secondary\ and not primary, as Sabin holds. According
 
this other view the lymphatic vessels spring from lymph-spaces, which are forn
 
in the mesoderm (mesenchyme), and are lined with mesothelium. The endothe
 
cells of the lymphatic vessels are derived from this mesothelium, and not fr
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DEVELOPMENT OF VASCULAR SYSTEMS
 
 
 
 
 
ii39
 
 
 
 
 
lous endothelium, according to Sabin, and the vessels establish a connection
 
le venous system at a later period.
 
 
 
nph-Glands. —Some of these are formed in connection with the lymphdiilst others are formed in connection with peripheral lymphatic vessels,
 
are three stages in the development of a lymph-gland. The first stage
 
s in the formation of a plexus of lymphatic capillaries pervaded by con;-tissue septa. The second stage consists in the invasion of these septa
 
od-capillaries, surrounded by lymphocytes. The third stage consists in
 
mation of a lymph-sinus from the original plexus of lymphatic capillaries.
 
 
 
3 essential elements of a lymph-gland are thus threefold—namely: (1) a
 
of lymph-capillaries; (2) blood-capillaries, surrounded by lymphocytes,
 
connective-tissue septa; and (3) a lymph-sinus.
 
 
 
:h lymph-gland is connected with several lymphatic vessels. 1 hose which
 
;he gland are known as afferent vessels, and they open into the peripheral
 
deal part of the lymph-sinus. Those which emerge from the gland are
 
L efferent vessels, and they arise in the central or medullary part of the
 
-sinus. In no case does a lymphatic vessel pass uninterruptedly through
 
>h-gland. The gland is a station in the path of a lymphatic vessel, which
 
3nts the terminus of that vessel, but not the terminus of the lymph. That
 
after leaving the afferent vessel, flows in succession through the cortical
 
edullary parts of the lymph-sinus, and from the medullary part it flows
 
re efferent vessels. It is, therefore, so far as the lymph is concerned, a
 
f, so to speak, changing carriages at a glandular station. During this
 
s any injurious matter is taken up by the branched cells (phagocytes) of
 
nph-sinus, and the lymph is furnished with a contingent of lymphocytes.
 
 
 
Structure of Lymphatic Vessels.
 
 
 
lymphatic vessel, of large size, consists of three coats-—inner, middle,
 
iter. The internal coat {tunica intima) consists of a longitudinal network
 
stic fibres lined with endothelial cells. The middle coat {tunica media)
 
ts of plain muscular and elastic tissues disposed for the most part transy. The external coat {tunica externa) consists of (1) longitudinal bundles of
 
:tive tissue, and (2) plain muscular and elastic fibres, disposed for the
 
part longitudinally, lined with endothelium.
 
 
 
mphatic vessels are furnished with bloodvessels and nerves. Most ol
 
are also provided with valves, similar to those of the veins. Each valve
 
ts of two semilunar segments, facing one another, which are foldings of the
 
coat, containing connective and elastic tissues. They project slightly
 
ds each other, and their free edges are directed in the course of the lymfih1. The valves are situated at short intervals, and they serve to prevent
 
of lymph. When a lymphatic vessel becomes distended it presents a
 
d appearance, with constrictions between the projections, these constrictions
 
ponding to the attached margins of the valvular segments,
 
svelopment. —According to Sabin, the lymphatic vessels are developed from
 
Ldothelial lining of the primitive lymph-sacs (see Development of Lymphatic
 
m).
 
 
 
Structure of Lymphatic Glands.
 
 
 
lymphatic gland consists of a capsule, which encloses the glandular sube. The capsule is composed of connective tissue, containing elastic fibres.
 
:ie glandular substance presents two parts—superficial or cortical, and
 
al or medullary. Each of these parts is permeated by a supporting frarneof trabeculae derived from the capsule. Ihese trabeculae are composed o
 
active tissue, with a few plain muscular fibres. They subdivide the cortex
 
follicles, between which they form incomplete septa. In the medulla the
 
 
 
culae are arranged in a reticular manner. .. ,
 
 
 
be glandular substance is formed by lymphoid or adenoid tissue, wnic
 
sts of retiform tissue, with lymphocytes in its meshes. In the cortex o
 
 
 
 
 
1140
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
the gland this lymphoid tissue is disposed as lymph-follicles, and in the m
 
it forms lymph-cords. In both parts of the gland there are spaces betwe<
 
glandular substance and the supporting trabecular framework. These s
 
which are for the passage of lymph, constitute the lymph-sinus. This si
 
broken up at all parts of the gland by retiform tissue, the meshes of whi
 
partially lined with branched cells of the nature of phagocytes. The glai
 
substance, except the lymph-sinus, is permeated by blood-capillaries.
 
 
 
Lymphatic glands are furnished with bloodvessels, nerves, and lym
 
vessels. The arterioles pass to the glandular substance, being at first enshe
 
by the supporting trabeculae of connective tissue, and subsequently by the re
 
tissue of the glandular substance. The nerves are destined for the plain mu
 
tissue of the trabeculae and bloodvessels.
 
 
 
The lymphatic vessels are of two kinds—afferent and efferent. The a
 
vessels enter the gland over its surface, whilst the efferent vessels emerge
 
definite part of the gland, where there is a slight depression, called the t
 
The afferent vessels convey lymph to the cortical part of the lymph-sinus,
 
the efferent vessels convey lymph from the medullary part of that sinus,
 
much as the medullary part of the gland extends quite to the surface at the
 
where the depression, known as the hilum, exists, the efferent vessels e
 
from the gland through this hilum, which also gives passage to the arterie
 
veins.
 
 
 
Development. —Lymphatic glands are developed partly from the prii
 
lymph-sacs and partly from peripheral lymphatic vessels (see Developm*
 
Lymphatic System).
 
 
 
 
 
CHAPTER XIV
 
 
 
THE HEAD AND NECK
 
 
 
 
 
BACK OF THE SCALP AND NECK.
 
 
 
andmarks. —The external occipital protuberance can, as a rule, be
 
: out readily enough in the male, and the superior nuchal line,
 
ill developed, may be felt extending outwards from it. The
 
oid process of the temporal bone can be distinguished without
 
ulty behind the auricle. The occipital artery, with the greater
 
iital nerve on its inner side, lies about inches to the outer side
 
e external occipital protuberance. The occipital lymphatic gland,
 
[ands, may be felt, when enlarged, over the upper part of the
 
izius or semispinalis capitis muscle. The spine of the seventh
 
cal vertebra, or vertebra prominens, can easily be felt, and that
 
le sixth may also be made out. Extending from the external
 
)ital protuberance to the seventh cervical spine there is an elonI depression, called the nuchal furrow, which indicates the position
 
tie ligamentum nuchse. It is possible to feel the strong bifid
 
3 of the axis by sinking the finger deeply into the upper part of
 
luchal furrow near the occipital bone, but the spines of the third,
 
Hi, and fifth cervical vertebrae lie too deeply for detection. Lymic glands may be felt, when enlarged, along the posterior border
 
le sterno-mastoid muscle.
 
 
 
Jack and Side of the Neck—Fasciae. —The superhcial fascia presents
 
ing worthy of note. The deep fascia closely invests the cervical
 
ion of the trapezius, and is then prolonged over the posterior
 
lgle of the neck to the posterior border of the sterno-mastoid,
 
re it divides to ensheathe that muscle. It will be described in
 
lection with the deep cervical fascia.
 
 
 
Jutaneous Nerves. —The nerves of this region are as follows: the
 
)Ccipital; the greater occipital; the third occipital; the medial
 
iches of the posterior primary rami of the third, fourth, and fifth
 
ical spinal nerves; the lesser occipital; the great auricular; the
 
rior cutaneous nerve of neck; and the descending superficial
 
iches of the cervical plexus—namely, the supraclavicular nerves
 
Fig. 687).
 
 
 
Die suboccipital nerve is the posterior primary ramus of the first
 
ical nerve; it only occasionally supplies the skin on the outer
 
of the greater occipital area.
 
 
 
Fhe greater occipital nerve is the medial branch of the posterior
 
lary ramus of the second cervical nerve. It pierces the upper
 
 
 
1141
 
 
 
 
 
 
 
1142
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
part of the semispinalis capitis muscle, and sometimes the trape2
 
about -J inch from the middle line. It then runs upwards, with
 
inclination outwards, and accompanies the occipital artery to the era
 
integument, lying on the inner side of that vessel. Its branches
 
long, and have an extensive distribution, reaching as far as the vei
 
of the skull. Laterally it communicates with the small occif
 
nerve, and medially with the third occipital.
 
 
 
The third occipital nerve is a small offset from the me
 
branch of the posterior primary ramus of the third cervical ne
 
Having pierced the trapezius, it ascends medial to the gre;
 
occipital nerve, with which it communicates, and has a lim
 
distribution to the occipital integument inside that nerve.
 
 
 
The medial bran<
 
of the posterior prin
 
rami of the third, fou
 
and fifth cervical ne;
 
appear through
 
trapezius close to
 
middle line, and t
 
outwards to supply
 
skin of the back of
 
neck, that of the tl
 
furnishing, as j
 
stated, the third c
 
pital nerve.
 
 
 
The lesser occij
 
nerve is one of the
 
cending superfw
 
branches of the cerv
 
plexus, and arises fi
 
the anterior prim
 
ramus of the sec
 
cervical nerve, so
 
times receiving a bra
 
from that of the third. It appears at the posterior border of the stei
 
mastoid muscle, and ascends along that border to the occipital reg
 
Here it divides into mastoid and occipital branches, which supply
 
skin of the mastoid, outer part of the occipital, and adjacent porl
 
of the parietal regions. It furnishes an auricular branch to the 5
 
of the upper part of the inner surface of the auricle, and it commi
 
cates with the greater occipital, the posterior branch of the gi
 
auricular, and the posterior auricular branch of the facial,
 
lesser occipital nerve is sometimes double, and in these cases one port
 
of it usually pierces the anterior border of the trapezius.
 
 
 
The great auricular nerve, like the lesser occipital, is one of
 
ascending superficial branches of the cervical plexus, and arises
 
two roots from the anterior primary rami of the second and tl
 
cervical nerves. It turns round the posterior border of the stei
 
 
 
 
 
 
 
Occ. Front.
 
 
 
G. Occ. N.
 
Third Occ. N.
 
Less. Occ. N.
 
 
 
 
 
Fig. 687.—To show the Nerves and Vessels
 
on the Back of Scalp and Neck.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND-NECK
 
 
 
 
 
ii 43
 
 
 
 
 
istoid immediately below the lesser occipital nerve, and passes
 
wards and forwards upon that muscle towards the lobule of the
 
ricle, on approaching which it divides into anterior and posterior
 
anches. The posterior branch is distributed to the skin over the
 
istoid region, the skin of the inner surface of the auricle, and sends
 
e or two twigs through the cartilage of the auricle to the skin covery the lower part of the outer surface; and the anterior branch is dis
 
 
 
Auricularis Anterior
 
 
 
 
 
Auricularis Superior
 
 
 
 
 
Auricularis Posterior
 
 
 
 
 
Occipital Belly of
 
Occipito-frontalis
 
 
 
Greater Occipital Nerve
 
Semispinalis Capitis
 
Lesser Occipital Nerve
 
 
 
Splenius Capitis
 
 
 
 
 
Levator Scapulae
 
 
 
Great Auricular Nerve
 
 
 
Accessory Nerv e
 
anches from Third and Fourth
 
Cervical Nerves to Trapezius
 
Scalenus Medius
 
 
 
 
 
Lateral Supraclavicular
 
Nerve
 
 
 
 
 
Trapezius
 
 
 
 
 
 
 
' Frontal Belly of Occipitofrontalis
 
 
 
 
 
Orbicularis Oculi
 
 
 
Levator Labii
 
Superioris Alaeque Nasi
 
 
 
Levator Labii Superioris
 
- Zygomaticus Minor
 
Zygomaticus Major
 
 
 
Masseter
 
Orbicularis Oris
 
Depressor Labii Inferioris
 
_ Depressor Anguli Oris
 
Mentalis
 
 
 
Anterior Belly of Digastric
 
Stemo-hyoid
 
 
 
Superior Belly of Omo-hyoid
 
Sterno-mastoid
 
 
 
Anterior Cutaneous Nerve of the
 
Neck
 
 
 
— Medial Supraclavicular Nerve
 
 
 
— Intermediate Supraclavicular Nerve
 
 
 
 
 
Scalenus Anterior
 
 
 
»
 
 
 
Inferior Belly of Omo-hyoid Subclavian Artery (third part)
 
 
 
Fig. 688.—The Right Side of the Head and Neck.
 
The platysma has been removed, and the nerves are shown.
 
 
 
 
 
ibuted to the skin over the parotid gland and angle of the jaw. The
 
)sterior branch communicates with the lesser occipital and posterior
 
lricular nerves, and the anterior branch communicates in the parotid
 
and with the facial nerve.
 
 
 
The anterior cutaneous nerve of the neck (transverse cervical
 
irve), like the lesser occipital and great auricular, is a superficial
 
'anch of the cervical plexus, and arises by two roots from the anterioi
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
ii 4 4
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
primary rami of the second and third or third and fourth cervic
 
nerves. It appears at the posterior border of the sterno-mastc
 
close below the great auricular, and turns over that muscle deep
 
the external jugular vein to reach the front of the neck, where it w
 
be afterwards described.
 
 
 
The supraclavicular nerves from the cervical plexus appear at t
 
posterior border of the sterno-mastoid below the accessory, usua]
 
as a single trunk which arises by two roots from the anterior prima
 
rami of the third and fourth cervical nerves or from the fourth alor
 
This trunk, as it descends, divides into three branches—name]
 
medial, intermediate, and lateral —which pass downwards over t
 
clavicle, and will be afterwards referred to.
 
 
 
Deeper Structures.
 
 
 
Ligamentum Nuchse. —This is a strong fibrous band which occupi
 
the median line of the neck. Its superficial fibres are attached superior
 
to the external occipital protuberance, and interiorly to the spi
 
of the seventh cervical vertebra. Its deep fibres are attached
 
the external occipital crest, and to the spines of cervical vertebr
 
from the second to the sixth inclusive. They also extend into t
 
interspinous intervals between the interspinales muscles, where th
 
represent interspinous ligaments.
 
 
 
Muscles—Cervical Portion of the Trapezius — Origin. —fi) T
 
inner third of the superior nuchal line of the occipital bone, and t]
 
external occipital protuberance; and (2) the ligamentum nuchse.
 
 
 
Insertion. —(1) The posterior border of the outer third of ti
 
clavicle; and (2) the inner border of the acromion process of t]
 
scapula.
 
 
 
Nerve-supply. — (1) The accessory nerve (spinal root); ai
 
(2) branches from the cervical plexus, which are derived from t]
 
anterior primary rami of the third and fourth cervical nerves. T]
 
nerves enter the deep surface of the muscle after passing benea
 
its anterior border a little above the clavicle, and they here for
 
a plexiform communication with each other.
 
 
 
Blood-supply .—The superficial branch (superficial cervical arter
 
of the transverse cervical artery ramifies on and gives branches
 
the deep surface of the muscle.
 
 
 
The fibres are directed downwards, forwards, and outwards.
 
 
 
This part of the muscle lies on the semispinalis capitis just belo
 
the occiput, and below this on the splenius and levator scapuke; tl
 
superficial branch of the transverse cervical artery and superfici
 
branch of the ramus descendens (arteria princeps cervicis) of tl
 
occipital artery anastomose deep to it, and its nerves enter it. As
 
approaches its insertion its fibres lie over the supraspinatus, a fati
 
pad being interposed.
 
 
 
Action .—The cervical fibres, acting from their origin, elevate tl
 
outer end of the clavicle and the point of the shoulder. Acting froi
 
 
 
 
 
 
 
Fig. 689. —Dissection to show Muscles on Back of Neck.
 
 
 
Insertion and Posterior Border of the Sterno-mastoid.—This muscle
 
nserted into (1) the outer surface of the mastoid process of the
 
poral bone, and (2) the superior nuchal line of the occipital bone
 
r about its outer half, or more. The posterior border of the
 
$cle forms the anterior boundary of the posterior triangle of the
 
k, and has the following nerves related to it: (1) the lesser occipital
 
snds along it to the head; (2) the great auricular passes upwards
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1145
 
 
 
 
 
r insertion they extend the head, and incline the neck towards
 
same side, the face being directed towards the opposite side.
 
 
 
The anterior border of the muscle forms the posterior boundary
 
he posterior triangle of the neck.
 
 
 
)ccasionally a small muscle, called the transversus nuchse, is met with,
 
nding from the external occipital protuberance to the tendon of insertion
 
le sterno-mastoid. It may be fleshy or tendinous.
 
 
 
 
 
Cut. Muscles
 
Longiss. Cap.
 
Semispin. Cap.
 
 
 
 
 
Splenius Cerv.
 
Levator Scap.
 
 
 
 
 
Semisp. Cap.
 
Sterno-mastoid
 
Splenius Cap.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1146
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
and forwards superficial to it towards the lobule of the auricle; (3)
 
anterior cutaneous nerve of the neck crosses it in a forward directi
 
(4) the accessory appears from behind it, along with the branc
 
of the third and fourth cervical nerves to the trapezius; and (5)
 
supraclavicular branches of the cervical plexus emerge from unt
 
neath it.
 
 
 
Some deep cervical lymph glands are situated along the poste
 
border of the sterno-mastoid muscle. They will be described h
 
(see p. 1199).
 
 
 
The levator scapulae, rhomboids, serratus posticus super
 
splenius, semispinalis capitis, longissimus cervicis, longissimus cap:
 
semispinalis cervicis, intertransversales, and interspinales muscles
 
be found described in connection with the muscles of the back 1
 
p. 400 et seq.).
 
 
 
Second and Third Parts of the Occipital Artery. —At the mast
 
process this vessel lies very deeply. Having crossed the rectus cap
 
lateralis muscle, it enters the occipital groove on the inner aspeci
 
the mastoid process, where it is covered by the following structu
 
in order from the surface inwards: (1) sterno-mastoid; (2) spier
 
capitis; (3) longissimus capitis; (4) mastoid process; and (5)
 
posterior belly of the digastric. In its backward course the ve
 
rests in succession upon the insertions of the obliquus capitis supe
 
and semispinalis capitis, and it escapes from beneath the musi
 
covering it in the following order: posterior belly of the digast
 
longissimus capitis, splenius capitis, and sterno-mastoid. A
 
emerging from beneath the last-named muscle, it lies for a little
 
the posterior angle close to the apex, and then, frequently pierc
 
the occipital origin of the trapezius, it enters upon the third pari
 
its course. This part ascends along with the greater occipital ne
 
to the occipital region, where it divides into several long tortu
 
branches (Figs. 690 and 691).
 
 
 
Branches. —The branches of the second and third parts are
 
follows: mastoid, meningeal, descending, communicating, muscu
 
and occipital. The mastoid branch passes through the mast
 
foramen when there is one on the outer surface of the mastoid proc
 
and supplies the diploe and mastoid air-cells, as well as the adjac
 
dura mater. The meningeal branches enter the cranial cavity throi
 
the jugular foramen, and take part in the supply of the dura me
 
of the posterior fossa. The descending branch (arteria princeps cervi<
 
arises under cover of the splenius capitis, and at the outer bor
 
of the semispinalis capitis it divides into a superficial and deep brar
 
The superficial branch is distributed to the splenius capitis and trapez
 
and anastomoses in the latter muscle with the superficial brand
 
the transverse cervical artery. The deep branch passes deep to
 
semispinalis capitis, and anastomoses upon the semispinalis cerv.
 
with (1) the deep cervical artery, a branch of the costo-cervical tm
 
and (2) branches of the vertebral artery. The communicating branc
 
enter the suboccipital triangle, where they anastomose with branc
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1147
 
 
 
 
 
the vertebral artery. The muscular branches supply the contiguous
 
iscles. The occipital branches, which are the terminal branches,
 
; at first two in number, but these soon divide into several long
 
tuous branches, which supply the occipital belly of the occipitontalis and the integument as high as the vertex. They anastomose
 
 
 
 
 
 
 
g. 690. — To show Course of Occipital Artery (OA) as a Dotted Line on
 
 
 
the Under Side of Skull.
 
 
 
passes deep to mastoid process and muscles attached to this (digastric, longissimus capitis, sterno-mastoid, and splenius). It is lateral to rectus lateralis
 
(RL), rectus major (R.Mj), superior oblique (SO), and semispinalis capitis
 
(SSC). It emerges between splenius and trapezius (T).
 
 
 
th one another, with the posterior auricular, the posterior branch
 
the superficial temporal, and their fellows of the opposite side.
 
 
 
The occipital venous plexus communicates with the posterior
 
iricular and the posterior branch of the superficial temporal veins,
 
receives the parietal emissary vein, which emerges through the
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1148
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
parietal foramen, and so a communication is established with t]
 
superior sagittal sinus; a communication is also formed with tl
 
sigmoid sinus by means of the mastoid emissary vein through tl
 
mastoid foramen. Sometimes it receives a small occipital emissa\
 
vein which emerges through an opening at the external occipit
 
protuberance, and then a communication would be established wii
 
the confluence of the sinuses.
 
 
 
Two or three occipital veins leave the occipital plexus. Tl
 
external vessel is known as the posterior external jugular vein. Havii
 
 
 
been reinforced by tributaries from the superficial structures at tl
 
upper part of the back of the neck, the posterior external jugular ve
 
passes on to the sterno-mastoid, where it opens into the extern
 
jugular. The middle occipital vein (inconstant) accompanies tl
 
occipital artery, and usually opens into the internal jugular. Tl
 
internal occipital vein, having in some cases pierced the trapeziu
 
passes beneath the semispinalis capitis, and enters the suboccipit
 
triangle. In this situation it joins the suboccipital plexus, from whi(
 
the deep cervical and vertebral veins emerge.
 
 
 
Occipital Lymph Glands. —These glands are usually two in numbe
 
and he superficial to the occipital portion of the trapezius, or the upp
 
part of the semispinalis capitis. They receive their afferent lymphati
 
from the back part of the scalp, and their efferent lymphatics pass
 
the deep cervical glands.
 
 
 
Deep Cervical Artery. —This vessel is in most cases a branch of tl
 
costo-cervical trunk of the second part of the subclavian. Havii
 
passed backwards between the transverse process of the seveni
 
cervical vertebra and the neck of the first rib, it ascends upon tl
 
semispinalis cervicis, under cover of the semispinalis capitis, towar<
 
the level of the spine of the axis, where it anastomoses with the de(
 
branch of the ramus descendens of the occipital. In its course
 
furnishes a spinal branch, which enters the vertebral canal throu^
 
the intervertebral foramen for the eighth cervical nerve, and mu
 
cular branches, which anastomose with branches of the vertebr
 
artery.
 
 
 
The deep cervical vein begins within the suboccipital triangle
 
the suboccipital plexus, which receives the internal occipital vei
 
It descends in company with the deep cervical artery to the low'
 
part of the neck, where it passes forwards between the transver:
 
process of the seventh cervical vertebra and the neck of the first ri
 
and ends by joining the vertebral vein just before that vessel terminate
 
in the innominate vein.
 
 
 
In addition to the muscular branches of the occipital and dee
 
cervical arteries, the deep muscles of the back of the neck receh
 
twigs from the second part of the vertebral artery, which travers*
 
the foramina transversaria of the upper six cervical vertebrae. The:
 
twigs pass backwards through the intertransverse spaces, and anas!
 
mose with branches of the ramus descendens of the occipital artei
 
and the deep cervical artery.
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1149
 
 
 
 
 
Suboccipital Region—Muscles—Rectus Capitis Posterior Major
 
 
 
Origin .—The ridge leading to one of the tubercles in which the
 
ne of the axis ends.
 
 
 
Insertion .—The outer part of the inferior nuchal line of the occipital
 
ne, and the subjacent area.
 
 
 
 
 
 
 
Nerve-supply .—The posterior primary ramus of the suboccipital
 
rve.
 
 
 
The direction of the fibres is upwards and outwards, in spite of its
 
ime.
 
 
 
Action. —(1) To rotate the face towards the same side; and (2) to
 
tend the head.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1150
 
 
 
The muscle is pyramidal, and its insertion is largely covered
 
the obliquus capitis superior.
 
 
 
Rectus Capitis Posterior Minor— Origin.— The posterior arch
 
the atlas close to the tubercle.
 
 
 
Insertion. —The inner third of the inferior nuchal line of the occipi
 
bone, and the subjacent area as low as the foramen magnum.
 
 
 
Nerve-supply .—The posterior primary ramus of the suboccipi
 
nerve.
 
 
 
The direction of the fibres is upwards in an expanded manner.
 
 
 
Action. —To extend the head.
 
 
 
The muscle is fan-shaped, and lies deeper than, and medial
 
the rectus capitis posterior major.
 
 
 
Obliquus Capitis Inferior — Origin.- —The outer and upper aspect
 
the spine of the axis.
 
 
 
Insertion. —The lower surface of the transveise process of the at
 
at its back part.
 
 
 
Nerve-supply. —The posterior primary ramus of the suboccipi
 
nerve.
 
 
 
The direction of the fibres is outwards and slightfy upwards.
 
 
 
Action .—To rotate the atlas along with the head, so that the fa
 
looks towards the same side.
 
 
 
The muscle is thick and fleshy. At its origin it is interpos
 
between the rectus capitis posterior major superiorly and the high
 
bundle of the semispinalis cervicis interiorly. The greater occipi
 
nerve winds round its lower border.
 
 
 
Obliquus Capitis Superior — Origin. —The upper surface of the trai
 
verse process of the atlas at its back part.
 
 
 
Insertion .—The occipital bone between the outer parts of i
 
superior and inferior nuchal lines.
 
 
 
Nerve-supply. —The posterior primary ramus of the suboccipi
 
nerve.
 
 
 
The direction of the fibres is upwards and very slightly inwards.
 
 
 
Action .—(1) To extend the head, and (2) to act as a slight late
 
flexor of the head.
 
 
 
The muscle is triangular.
 
 
 
Suboccipital Triangle. —This triangle is situated under cover of 1
 
upper part of the semispinalis capitis close below the occipital bone.
 
 
 
Boundaries — Supero-medial. —The rectus capitis posterior maj
 
External. —The obliquus capitis superior. Inferior. —The obliqi
 
capitis inferior. The roof is formed by the semispinalis capitis a
 
longissimus capitis, and the floor by half of the posterior arch
 
the atlas and half of the posterior atlanto-occipital membrane. *
 
contents are (1) the third part of the vertebral artery, (2) the si
 
occipital plexus of veins, and (3) the posterior primary ramus of
 
first cervical nerve. The greater occipital nerve turns upwards rou
 
the inferior oblique and crosses the inner part of the triangle deep
 
the semispinalis capitis, and the deep division of the ramus descend*
 
of tde occipital artery runs down near this.
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1151
 
 
 
 
 
lird Part of the Vertebral Artery. —The vertebral artery, having
 
i through the foramen transversarium of the atlas, enters upon
 
bird part of its course, and takes a winding course backwards
 
 
 
 
 
Recti Capitis Posteriores Minores
 
 
 
 
 
Rectus Capitis Posterior
 
Major
 
 
 
 
 
Tubercle on Posterior
 
Arch of Atlas
 
 
 
 
 
Spine of Axis-
 
 
 
Interspinales
 
 
 
 
 
 
 
,Suboccipital Triangle
 
 
 
 
 
Obliquus Capitis
 
Superior
 
 
 
 
 
’-.Mastoid Process
 
 
 
 
 
Vertebral Artery
 
(Third Part)
 
 
 
Posterior Primary Ramus
 
of Suboccipital Nerve
 
' Transverse Process of
 
-- Atlas
 
 
 
'''* Obliquus Capitis Inferior
 
Greater Occipital Nerve
 
 
 
 
 
Semispinalis Cervicis (upper
 
two bundles)
 
 
 
 
 
Fig. 692.—The Suboccipital Triangle.
 
 
 
 
 
inwards. It lies in the vertebrarterial groove of the atlas, the
 
;rior primary ramus of the first cervical nerve being beneath it,
 
it passes under an arched band of the posterior atlanto-occipital
 
 
 
 
 
 
 
693.—Atlas seen from Above, to show Position of Vertebral Artery
 
 
 
and Suboccipital Nerve.
 
 
 
hrane, which is sometimes ossified. It thus leaves the suboccipital
 
igle, pierces the dura mater, and enters the cranial cavity through
 
oramen magnum. The third part of the vessel furnishes muscular
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1152
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
branches to the adjacent muscles, which anastomose with the rai
 
descendens of the occipital and the deep cervical of the costo-cerv
 
trunk.
 
 
 
Suboccipital Plexus of Veins. —This plexus is formed by bram
 
which proceed from (i) the vertebral venous plexuses, (2) the adjat
 
muscles, and (3) the occipital periosteum. It receives the inte:
 
occipital vein, and the blood is conveyed away from it by the d
 
cervical vein, already described, and the vertebral vein, which wil
 
afterwards considered.
 
 
 
Posterior Primary Division of the First Cervical or Suboccii
 
Nerve. —This division passes backwards as a single nerve in the ve
 
brarterial groove of the atlas, lying between the bone and the tl
 
part of the vertebral artery. On entering the suboccipital triangl
 
divides into branches which supply the obliqui, recti posteriores,
 
semispinalis capitis muscles. A filament joins the greater occip
 
nerve.
 
 
 
Posterior Primary Rami of the Cervical Spinal Nerves.—
 
 
 
cervical nerves are eight in number, the first being known as the s
 
occipital nerve. Each breaks up into an anterior and a poste
 
primary ramus. The posterior primary ramus of the first or s
 
occipital is single, and has just been described. The posterior prim
 
rami of the lower six arise in the intervertebral foramina, and e
 
soon divides into a lateral and medial branch. The upper two cerv
 
nerves make their exit behind the articular masses, and their poste
 
primary rami cross the vertebral arches behind these; the second div:
 
into medial and lateral branches. The lateral branches of all are
 
tributed to the deep muscles, and do not become cutaneous.
 
medial branch of the posterior primary ramus of the second, whic
 
of large size, constitutes the greater occipital nerve. It winds nr
 
the lower border of the obliquus capitis inferior, and pierces
 
semispinalis capitis, to which it gives branches. Later it r
 
pierce the trapezius to reach its cutaneous distribution, which
 
been already described. The medial branches of the third, fou:
 
and fifth are directed inwards superficially to the semispin
 
cervicis, to which, as well as to the semispinalis capitis, they {
 
branches. Close to the cervical spines they pass backwards me^
 
to the spinalis capitis (biventer cervicis), and, having pierced
 
splenius and trapezius, they reach the integument, which they sup]
 
The medial branch of the posterior primary ramus of the third, be]
 
piercing the trapezius, gives off a small ascending branch, knowr
 
the third occipital. It passes upwards, lying at first under cove:
 
the trapezius, and then passing through it to reach the occipital inte
 
ment. The medial branches of the posterior primary rami of
 
sixth, seventh, and eighth are directed inwards towards the cerv
 
spines beneath the semispinalis cervicis, and are distributed to
 
adjacent muscles. They do not furnish any branches to the inte
 
ment.
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii53
 
 
 
 
 
The Scalp and Temporal Region.
 
 
 
ascise. —The place of the deep fascia beneath the skin may be
 
to be taken by the epicranial aponeurosis of the occipito-frontalis
 
:le. The aponeurosis becomes thin and fascial over the temporal
 
ns. Where it is thick and aponeurotic it is firmly attached to
 
overlying skin by fibrous processes, between which are small
 
r lobules, so that the subcutaneous laver is firm and somewhat
 
ular in appearance. The vessels and nerves are distributed in this
 
*, which loses its fibrous nature in the temporal regions and becomes
 
lerficial soft fatty layer.
 
 
 
uperficial Nerves and Vessels. —The superficial nerves of the
 
ero-lateral aspect; the greater, small, and third occipital nerves;
 
the mastoid branch of the great auricular , have been described
 
idy. In the fronto-parietal region two sensory nerves are met
 
—namely, the supra-orbital and supratrochlear —both of which
 
lerived from the frontal nerve, which is one of the branches of the
 
:halmic division of the fifth cranial nerve. In the temporal region
 
the temporal branches of the facial nerve , the auriculo-temporal
 
 
 
 
 
 
 
1 n
 
 
 
u 6
 
Uf.
 
*Y «r
 
 
 
 
 
Skull
 
 
 
 
 
Fig. 694.—Diagram of Section through Scalp.
 
 
 
 
 
e, and the zygomatico-temporal nerve. Of the arteries of the
 
p, the third part of the occipital artery, in the posterior region, has
 
1 described. Those of the fronto-parietal region are three in
 
ber—namely, the supra-orbital , supratrochlear , and anterior branch
 
he superficial temporal. The superficial temporal artery ramifies
 
he side of the head in the temporal region.
 
 
 
Qie supra-orbital nerve, which is of large size, leaves the orbit
 
•ugh the supra-orbital foramen. It then ascends, lying at first
 
) to the upper part of the orbicularis oculi and the frontal belly
 
he occipito-frontalis muscle, but subsequently piercing the latter
 
cle in two branches, medial and lateral. The lateral branch is the
 
er of the two, and its offsets extend as far back as the lambdoid
 
ire. As the supra-orbital nerve passes through the supra-orbital
 
'h it furnishes one or two twigs to the mucous membrane of the
 
tal sinus and to the diploe of the frontal bone, and after leaving
 
notch it sends downwards branches to the integument of the upper
 
id. After this the nerve supplies the integument of the frontoetal region.
 
 
 
rhe medial and lateral branches of the supra-orbital nerves sometimes leave
 
orbit separately, and each may form a notch or foramen of its own.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1154
 
 
 
The supratrochlear nerve, which is of small size, is medial to
 
supra-orbital nerve. It leaves the orbit close to the medial angi
 
process of the frontal bone, where it lies above the pulley of the s-upe
 
oblique muscle of the eyeball. It then ascends deep to the upper j
 
of the orbicularis oculi and the frontal belly of the occipito-front
 
muscle, and, piercing the former muscle, it has a limited distribui
 
to the frontal integument close to the median line. As the nt
 
leaves the orbit it furnishes twigs to the inner part of the integurr
 
of the upper eyelid.
 
 
 
The supra-orbital artery is a branch of the ophthalmic, and emei
 
from the orbit with the supra-orbital nerve. It is distributed to
 
structures covering the frontal bone, and anastomoses with the su]
 
trochlear branch of the ophthalmic artery and the anterior brand
 
the superficial temporal artery. In the supra-orbital notch it fumis
 
one or two branches to the mucous membrane of the frontal sinus
 
to the diploe of the bone, and after leaving the notch it sends do
 
wards branches to the integument of the upper eyelid (Fig. 698).
 
 
 
The supra-orbital vein passes downwards and inwards to a p(
 
just above the medial angle of the orbit, where it joins the suj
 
trochlear vein. In this manner the angular vein is formed, whic
 
the commencement of the anterior facial vein. The supra-orbital ^
 
receives tributaries from the frontal region and the upper eyelid, ;
 
in the region of the medial angle of the orbit it communicates with
 
superior ophthalmic vein. It also communicates with the supe
 
ophthalmic vein through the supra-orbital notch, and this commun
 
tion receives the frontal diploic vein, which returns the blood from
 
diploe of the frontal bone and mucous membrane of the frontal sir
 
 
 
The supratrochlear artery (frontal artery), like the supra-orbita
 
a branch of the ophthalmic, and leaves the orbit with the supratroch.
 
nerve. It is distributed to the structures over the frontal bone me*
 
to the supra-orbital artery, with which it anastomoses, as well as v
 
its fellow of the opposite side.
 
 
 
The supratrochlear vein (frontal vein), of large size, passes do
 
wards near the median line, and at a point just above the medial ar
 
of the orbit is joined by the supra-orbital vein, the resultant ve
 
being the angular vein. At the root of the nose it communicates v
 
its fellow of the opposite side by a transverse vessel, called the m
 
arch.
 
 
 
The supra-orbital and supratrochlear veins communicate with e
 
other, and with the tributaries of the anterior branch of the superfi
 
temporal vein.
 
 
 
Occipito-frontalis. —This muscle consists of the following pa
 
(1) two occipital bellies, (2) two frontal bellies, and (3) the epicra
 
aponeurosis.
 
 
 
Each occipital belly arises from (1) the highest nuchal line of
 
occipital bone; and (2) the outer surface of the mastoid process of 1
 
temporal bone immediately above the insertion of the sterno-mas
 
muscle.
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii55
 
 
 
 
 
Insertion .—The epicranial aponeurosis.
 
 
 
Each belly forms a thin, broad sheet, the length of the fasciculi
 
Lg about ij inches. The two bellies, right and left, are separated
 
ards the median line by a portion of the epicranial aponeurosis,
 
ch here dips down between them.
 
 
 
Each frontal belly, right and left, is separated superiorly by a
 
row angular portion, of the epicranial aponeurosis, but interiorly
 
/ are in contact. Origin .—(1) The subcutaneous tissue of the
 
 
 
 
 
Fig. 695.—To show Occipital Belly of Occipito-frontalis.
 
 
 
)row and root of the nose, where the fibres blend with the upper
 
- of the orbicularis oculi and the corrugator supercilii; and (2) slightly
 
1 the zygomatic process of the frontal bone, and from the nasal
 
 
 
e.
 
 
 
Insertion ,—The epicranial aponeurosis a little below the level of
 
fronto-parietal suture.
 
 
 
Hie fasciculi are about 3^ inches long, and the innermost fibres
 
riorly are regarded by some as being prolonged downwards upon
 
nasal bone as the procerus muscle.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1156
 
 
 
Epicranial Aponeurosis. —This is the intermediate tendon of
 
occipito-frontalis muscle. It forms an aponeurotic stratum ben<
 
the superficial fascia, and is connected firmly to the skin by fib
 
processes, which separate the subcutaneous tissue into lobules,
 
deep surface is loosely connected by areolar tissue to the subja*
 
periosteum. Posteriorly it gives insertion to the two occipital be
 
and in the interval between these it dips down to be attached to
 
inner part of the superior nuchal line of the occipital bone and
 
external occipital protuberance. Anteriorly it gives insertion to
 
two frontal bellies. Laterally, below the superior temporal :
 
it is prolonged downwards over the temporal fascia as a deh
 
 
 
 
 
 
 
Fig. 696. —Shows Frontal Portion of Occipito-frontalis.
 
 
 
expansion, which gives origin to the auricularis superior and auricul
 
anterior muscles. It is connected to the superior temporal line I
 
thickening of the loose areolar tissue between it and the bone.
 
 
 
Nerve-supply .—Each occipital belly is supplied by the poste
 
auricular branch of the facial nerve, and each frontal belly is supp
 
by the temporal branches of the facial nerve.
 
 
 
Action .—The two occipital bellies draw backwards the epicra
 
aponeurosis, and along with it the scalp. The two frontal bellies
 
from above, elevating the eyebrows, and throwing the skin of
 
frontal region into transverse wrinkles. When the occipital and fro'
 
bellies act simultaneously the scalp is drawn backwards, and
 
eyebrows are forcibly raised. In certain cases the frontal bellies 1
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii57
 
 
 
 
 
n the reverse direction, their lower attachment being fixed by other
 
muscles, such as the orbicularis oculi, corrugator supercilii, and
 
crus. When this is done the scalp may be alternately twitched
 
r ard and backward, a simian habit which may be acquired by
 
:tice.
 
 
 
Pericranium. —This is the periosteum of the cranium, and it is
 
sly connected by areolar tissue to the superjacent epicranial
 
leurosis.
 
 
 
 
 
Parotid Duct.
 
Buccinator Muscle_
 
 
 
Facial Artery
 
Submental Artery
 
 
 
Lingual Artery
 
Sup. Lar. Art. and Nerve
 
Thyro-hyoid Muscle
 
Superior Thyroid Artery
 
 
 
 
 
Inf. Belly of Omo-hyoid
 
 
 
Subclavian Artery
 
(third part)
 
 
 
 
 
 
 
Transverse Facial Artery
 
 
 
 
 
Superficial Temporal Artery
 
 
 
- Maxillary Artery
 
 
 
 
 
Posterior Auricular
 
Artery
 
---- Occipital Artery
 
 
 
 
 
-Stylo-hyoid Muscle
 
 
 
 
 
-Post. Belly of Digastric
 
 
 
-Hypoglossal Nerve
 
 
 
-Nervus Descendens
 
 
 
Cervicalis
 
External Carotid
 
Artery
 
 
 
 
 
Stemo-mastoid
 
— Trapezius
 
 
 
 
 
_Transverse Cervical Artery
 
 
 
-.Suprascapular
 
Artery
 
 
 
 
 
Fig. 697. —The Left Side of the Head and Neck.
 
The platysma has been removed.
 
 
 
 
 
The temporal branches of the facial nerve pass upwards a little in
 
tt of the auricle, and supply the following muscles: the frontal
 
Y of occipito-frontalis, upper part of the orbicularis oculi, corrusupercilii, auricularis superior and auricularis anterior. They
 
municate with the auriculo-temporal, zygomatico-temporal, and
 
'a-orbital nerves.
 
 
 
Hie auriculo-temporal nerve is a branch of the mandibular nerve,
 
'h is the third division of the fifth cranial nerve. It emerges just
 
nd the capsule of the mandibular joint, turns upwards round the
 
of the zygoma, and ascends immediately in front of the auricle in
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1158
 
 
 
company with the superficial temporal artery, lying between that, ves
 
and the auricle
 
 
 
Branches.—In this part of its course the nerve furnishes
 
following branches! (1) two branches to the external auditory meat
 
which enter the canal between its osseous and cartilaginous walls, a
 
supply the integument of the meatus, the upper of the two branc.
 
giving an offset to the tympanic membrane; (2) two auricular brand
 
which supply the skin of the tragus and outer aspect of the auri
 
over less than its upper half; and (3) superficial temporal brand
 
which supply the integument above and in front of the auricle, and
 
the temporal region generally.
 
 
 
The zygomatico-temporal nerve (temporal branch of temporo-ma
 
nerve) from the maxillary is of small size, and pierces the tempc
 
fascia about 1 inch above the anterior part of the zygoma, and cl
 
behind the frontal process of the zygomatic bone. Having cc
 
municated with one of the temporal branches of the facial nerve
 
has a limited distribution to the integument of the anterior part
 
the temporal region.
 
 
 
The superficial temporal artery is one of the terminal branches
 
the external carotid artery, from which it arises within the pare
 
gland on a level with the neck of the mandible. Leaving the gla
 
it ascends in front of the auricle in company with the auriculo-tempc
 
nerve, which lies between the vessel and the auricle, and after a cou
 
of about 2 inches it divides into its two terminal branches.
 
 
 
Branches.—These are as follows: (1) transverse facial; (2) articul
 
(3) auricular; (4) middle temporal; (5) zygomatic; and (6) termina
 
namely, anterior and posterior.
 
 
 
The transverse facial artery will be described in connection w
 
the face. It arises within the parotid gland, and in its course furnis
 
glandular branches. The articular branches supply the mandiby
 
joint. The auricular branches supply the outer aspect of the auri'
 
and in part the external auditory meatus. The middle tempc
 
artery pierces the temporal fascia immediately above the zygoma, c
 
then ascends in a groove on the outer surface of the squamous p
 
of the temporal bone deep to the temporalis. It gives branches to
 
temporalis, and anastomoses with the deep temporal branches of
 
maxillary artery. The zygomatic artery passes forwards close above
 
zygoma, where it lies between the two layers of the temporal fas<
 
It is distributed to the outer part of the orbicularis oculi muscle,
 
anterior branch passes forwards and upwards in a tortuous man:
 
and is distributed to the structures covering the frontal bone, wher
 
anastomoses with the supra-orbital and supratrochlear branches 0T
 
ophthalmic artery, and with its fellow of the opposite side,
 
posterior branch takes an arched course upwards and backwa
 
above the auricle, supplying the adjacent structures, and anas
 
mosing with the posterior auricular and occipital arteries, and v
 
its fellow of the opposite side (see Fig. 698).
 
 
 
The arteries of the scalp are peculiar in many ways. In the f
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii59
 
 
 
 
 
; they are very superficial, lying in the fatty layer of the scalp
 
deep to the skin; they are thus very liable to injury, and in old
 
le, where their walls are hardening and the superficial fat diminishthey may easily be seen in the temporal region,
 
n the second place they are very tortuous, a condition which is
 
lly associated with arteries supplying movable parts, and in
 
ige this tortuosity increases.
 
 
 
'hirdly, they not only anastomose with one another, as most
 
'ies do, but they anastomose freely across the middle line, thus
 
lg wonderful vitality to a piece of scalp which has been torn away
 
>st completely.
 
 
 
 
 
 
 
L. Testut’s ‘ Anatomie Humaine ’).
 
 
 
fourthly, when cut they bleed most profusely, because their walls
 
prevented from collapsing by the dense connective tissue between
 
skin and the epicranium in which they lie. For this reason, too,
 
difficult to pick them up when they have to be tied,
 
fhe superficial temporal vein is formed in front of the auricle by
 
union of an anterior and a posterior branch, the former communing freely with the supra-orbital and supratrochlear veins, and the
 
T with the posterior auricular vein and the occipital venous plexus,
 
ve the zygoma it is joined by the middle temporal vein, which
 
inates in a plexus in the temporal fossa, and pierces the temporalis
 
temporal fascia, receiving in its course the zygomatic vein. The
 
Official temporal vein then descends over the zygoma and enters
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
n6o
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
the parotid gland, within which it receives the auricular, articu
 
and transverse facial veins. Finally, it joins the maxillary vein ah
 
the level of the neck of the mandible to form the posterior facial's
 
(temporo-maxillary vein).
 
 
 
Extrinsic Muscles of the Auricle.—These are three in number,
 
follows: (i) auricularis superior; (2) auricularis anterior; and (3) aur:
 
laris posterior.
 
 
 
Auricularis Superior (Attollens Aurem)— Origin. —The lateral par
 
the epicranial aponeurosis and temporal fascia.
 
 
 
Insertion. —The inner or cranial surface of the auricle over
 
convexity corresponding to the fossa of the antihelix on its 01
 
surface.
 
 
 
Nerve-supply. —The temporal branches of the facial nerve,
 
posterior part of the muscle may be supplied by the posterior aurici
 
branch of the facial nerve.
 
 
 
The muscle is very thin, pale, and fan-shaped, and. its fibres c
 
verge in a downward direction.
 
 
 
Action. —To raise the auricle, though all the auricular muscles
 
vestigial in man and practically functionless.
 
 
 
Auricularis Anterior (Attrahens Aurem)— Origin .—The lateral p
 
of the epicranial aponeurosis in front of the auricularis superior, v
 
which muscle it is continuous. Also from the temporal fascia.
 
 
 
Insertion. —The anterior part of the helix of the auricle.
 
 
 
Nerve-supply. —The temporal branches of the facial nerve.
 
 
 
The muscle is directed backwards.
 
 
 
Action. —To draw forwards the auricle.
 
 
 
Auricularis Posterior (Retrahens Aurem)— Origin. —The upper p
 
of the outer surface of the mastoid process of the temporal bone.
 
 
 
Insertion. —The inner or cranial surface of the auricle over
 
convexity of the concha.
 
 
 
Nerve-supply. —The posterior auricular branch of the facial nerv
 
 
 
The muscle is directed forwards.
 
 
 
Action. —To draw back the auricle.
 
 
 
The auricularis posterior is more distinct than the other two muse
 
and is usually arranged in two bundles.
 
 
 
Behind the ear, in the mastoid region, which is not a part of
 
scalp proper, there are certain structures which have some conned
 
with the scalp. These comprise posterior auricular nerves (branc
 
of the facial and vagus), posterior auricular vessels, and poste
 
auricular lymph glands.
 
 
 
Posterior Auricular Nerve.—This is a branch of the facial ne;
 
immediately after it emerges from the facial canal through the st;
 
mastoid foramen. It passes upwards between the mastoid pro<
 
and the auricle, where it lies deeply in company with the postej
 
auricular artery, and it divides into two branches—auricular ;
 
occipital. The auricular branch supplies the auricularis poste;
 
muscle on its deep aspect, and those intrinsic muscles of the aur
 
which lie on its inner or cranial aspect. It may also send a bra
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1161
 
 
 
 
 
yards beneath the auricularis posterior to supply the posterior
 
t of the auricularis superior. The occipital branch passes back■ds, lying deep to the lesser occipital nerve and posterior branch
 
the great auricular, and supplies the corresponding half of the
 
ipital belly of the occipito-frontalis muscle. The posterior auricular
 
ve communicates with the lesser occipital and great auricular
 
ves, and also with the auricular branch of the vagus.
 
 
 
The Auricular Branch of the Vagus Nerve (Nerve of Arnold). —This
 
t branch of superior ganglion of the nerve. Having traversed the
 
stoid canaliculus in the petrous part of the temporal bone, it
 
srges through the tympano-mastoid fissure between the mastoid
 
cess and tympanic plate, and then divides into two branches. One
 
nch takes part in the supply of the inner or cranial surface of the
 
icle, and also supplies the lower and back part of the external
 
litory meatus; and the other branch joins the posterior auricular
 
ve.
 
 
 
Posterior Auricular Artery. —This vessel is one of the two posterior
 
nches of the external carotid artery, the other branch being the
 
ipital artery. Having passed backwards and upwards on the
 
loid process under cover of the parotid gland, it lies deeply between
 
i mastoid process and the auricle in close relation to the posterior
 
icular nerve, and divides into two branches—auricular and occipital,
 
e auricular branch supplies the inner or cranial surface of the auricle
 
i adjacent structures, and it anastomoses with the posterior branch
 
the superficial temporal artery. The occipital branch passes backrds to the occipital belly of the occipito-frontalis muscle, and
 
istomoses with the occipital artery.
 
 
 
The posterior auricular vein is of fairly large size, and returns the
 
od from the lateral portion of the scalp posteriorly and the inner
 
face of the auricle. Its radicles communicate with the occipital
 
xus and with the posterior branch of the superficial temporal vein,
 
e vessel passes downwards and forwards over the upper part of the
 
rno-mastoid muscle, and terminates on this muscle about the level
 
the angle of the mandible by joining the posterior division of the
 
sterior facial vein to form the external jugular vein.
 
 
 
Mastoid Lymph Glands (Posterior Auricular Lymph Glands). These
 
all glands lie close to the insertion of the sterno-mastoid muscle,
 
ey receive their afferent lymphatics from the lateral part of the back
 
the scalp and the back of the auricle, and their efferent lymphatics
 
$s to the upper deep cervical lymph glands.
 
 
 
Temporal Fascia. —This is a strong aponeurosis which covers the
 
nporalis. Superiorly it is attached from before backwards to the
 
nporal border of the zygomatic bone, the superior temporal line of
 
i frontal and parietal bones, and the supramastoid crest. of the
 
nporal bone. Interiorly it divides into two laminae, which aie
 
ached to the outer and inner margins of the upper border of the
 
somatic arch. Between these two laminae there are a small amount
 
adipose tissue, and the zygomatic branch of the superficial temporal
 
 
 
 
 
1162
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
artery, and the zygomatico-temporal nerve. Superficial to the fasc
 
there are the delicate prolongation of the lateral portion of the e]
 
cranial aponeurosis and the auriculares superior et anterior muscl<
 
with the superficial temporal vessels and auriculo-temporal nen
 
Superiorly the fascia gives origin by its deep surface to superfic:
 
fibres of the temporalis, but it is separated from that muscle towar
 
the zygoma by fat.
 
 
 
The temporalis muscle is described on p. 1302.
 
 
 
Lymphatic Vessels of the Scalp—Frontal Region. —These pass
 
the parotid lymph glands. The anterior lymphatics pass directly
 
the parotid lymph glands, and the posterior lymphatics terminate in t
 
mastoid lymph glands.
 
 
 
The Scalp as a Whole. —Before leaving the scalp it may be w<
 
to review its general structure and to notice that it is made up of fi
 
layers.
 
 
 
(1) The skin is very thick, and nee^6 a firm incision to penetrate:
 
 
 
(2) The subcutaneous tissue binds the skin closely to the epicrani
 
aponeurosis, with which it moves; it contains lobular, granulated f
 
in which are the bloodvessels and nerves as well as the roots of t.
 
hair follicles. On account of the presence of the nerves as well as of t.
 
density of the connective tissue any suppuration in this layer will
 
strictly localized and very painful.
 
 
 
(3) The epicranial aponeurosis is formed by the very thin, flatten
 
tendon of the occipito-frontalis muscle.
 
 
 
(4) The subaponeurotic layer, sometimes known to surgeons as t.
 
‘ dangerous layer * of the scalp, is composed of very loose connectf
 
tissue, and is little more than a lymph space. The looseness of tj
 
cellular tissue allows the first three layers to move freely over t]
 
skull, and if septic matter reaches it and suppuration follows, t]
 
pus readily spreads all over the space and tends to bag at the mo
 
dependent points in front and behind. The absence of nerves and tl
 
looseness of the tissue account for the little pain which accompani
 
suppuration in this layer.
 
 
 
(5) The periosteum or pericranium covers the skull bones, and
 
continuous with the dura mater at the sutures as long as these a
 
unclosed. For this reason a subpericranial collection of blood
 
pus will be limited to the area of one skull bone, while a subepicrani
 
collection, as has been seen, has no such definition.
 
 
 
Basal Part of the Cranial Cavity.
 
 
 
Dura Mater on the Base of the Skull. —A full and general accoui
 
of the membranes of the brain will be found on p. 1598 ^ se ^->
 
short description of the dura mater, as it is seen on the base of tl
 
skull after removal of the brain, will be given here.
 
 
 
The dura mater is seen to be continuous with the falx cerebri in t
 
middle line in front. Just outside this it covers the cribriform pla
 
of the ethmoid at the bottom of a well-marked hollow which contai
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1163
 
 
 
olfactory bulb. External to this it covers the irregularities of the
 
tal plate of the frontal and the lesser wing of the sphenoid behind
 
. In the middle fossa it lines the so-called ‘ optic groove/ and at
 
 
 
I end of this is carried into the optic foramina. Behind the groove
 
>rms the diaphragma sella, covering the hypophyseal fossa, while
 
; pierced by the internal carotid artery just behind the foramen.
 
 
 
diaphragma sellae shows a central hole for the infundibulum of
 
hypophysis cerebri. The membrane is attached to the clinoid
 
:esses and the interclinoid ligaments, and stretches outwards from
 
;e to line the hollow of the greater wing and upper surfaces of the
 
•ous bone. It is carried upwards and forwards here to cover the
 
erior orbital fissure and gain the lower aspect of the lesser wing,
 
mall fold of dura mater projects from the edge of the lesser wing
 
he sphenoid, the sphenoidal fold , and a small ‘ lunula ’ overhangs
 
optic foramen. At the upper border of the petrous bone the
 
nbrane projects upwards and inwards as the tentorium cerebelli,
 
ch is a two-layered reflection of the dura mater. Below the
 
torium it lines the posterior fossa, and presents apertures through
 
ch all the nerves which come from the pons and medulla pass to
 
:h their bony foramina. A small fold, the falx cerebelli, projects
 
he middle line behind. The dura mater becomes continuous with
 
spinal dura at the foramen magnum, but the exact position of this
 
mien is not easily distinguished when the membrane is in position,
 
ng to the smooth, continuous slope formed by it as it passes from
 
basi-occiput over the odontoid process and its ligaments into the
 
tebral canal.
 
 
 
Certain structures lie deep to the dura mater, between it and the
 
y skull— i.e., between the inner layer, which we have been consider, and the outer layer, which covers the bones. These are venous
 
ises, nerves, and arteries. The venous sinuses on the base of the
 
 
 
II are (see p. 1603 et seq. for further details):
 
 
 
The sigmoid, running downwards and then forwards in the posterior
 
>a to reach the jugular foramen.
 
 
 
The inferior petrosal, passing forwards and upwards from the
 
ular foramen to the apex of the petrous bone along its lower edge.
 
The superior petrosal, running forward along the upper edge of the
 
rous bone at the base of the tentorium cerebelli.
 
 
 
The cavernous, placed on the side of the body of the sphenoid
 
ere this joins the greater wing, and formed by the junction of the
 
) petrosal sinuses; in front it is continuous with the superior ophImic vein and with the spheno-parietal sinus, which lies in the fold
 
lura mater along the lesser wing of the sphenoid.
 
 
 
The circular sinus is a spongy venous network which surrounds
 
: pituitary body and connects the two cavernous sinuses.
 
 
 
The transverse sinus lies under the central basal dura mater, and
 
n the form of a network joining the inferior petrosal sinuses.
 
 
 
The cranial nerves must necessarily pierce the dura mater to
 
ch and pass through the base of the skull, and the situations of the
 
 
 
 
 
1164
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
points of passage through the membranous and bony parts do n
 
always correspond. Those nerves which leave the skull in relati(
 
with the greater wing of the sphenoid pass through the dura mat
 
at points some distance behind their bony foramina, and in the inte
 
vening parts of their courses lie deep to the inner layer of dura mate
 
lying near or in relation with the cavernous sinus. These nerv
 
 
 
 
 
Frontal Sinus
 
 
 
 
 
Anterior Fossa
 
 
 
 
 
Optic Nerve
 
Ophthalmic Artery
 
 
 
 
 
Oculo-motor Nerve / •
 
 
 
 
 
Trochlear Nerve
 
 
 
 
 
Region of Cavum
 
Trigeminale
 
 
 
Trigeminal Nerve
 
 
 
 
 
Facial Nerve
 
 
 
Auditory Nerve
 
 
 
G losso-pharyngeal
 
Nerve
 
 
 
Vagus Nerve
 
 
 
 
 
 
 
Posterior Border c
 
Small WingofSphi
 
 
 
 
 
Ant. Intercav., S:
 
Hypophysis C«
 
 
 
 
 
.-Cavernous S
 
-- Abducent N
 
 
 
 
 
;— Middle Foss
 
 
 
 
 
4 - - Basilar Plex
 
 
 
 
 
Sup. PetrosE
 
Sinus
 
 
 
Inf. Petrosa]
 
Sinus
 
 
 
 
 
" Sigmoid Sin
 
 
 
 
 
'•Cerebellar Fossa
 
 
 
 
 
Accessory Nerve
 
 
 
 
 
Transverse Sinus
 
 
 
 
 
Hypoglossal Nerve]
 
 
 
 
 
Cerebral Fossa
 
 
 
 
 
Spinal]Cord j Confluence of Sinuses
 
Occipital Sinus
 
 
 
 
 
Fig. 699. —The Internal Base of the Skull, showing the Cranial Nervi
 
 
 
and Venous Sinuses.
 
 
 
are the oculo-motor, trochlear, trigeminal, and abducent; the oth<
 
cranial nerves pierce the dura mater opposite their bony foramina.
 
 
 
It is not quite correct to say that the cranial nerves ‘ pierce ’ the dura mat
 
at the places where their apertures of exit are seen; they carry out with the
 
a covering from the membrane, so that they could be described rightly 1
 
evaginating it. The covering layer, however, is so thin in most cases, and
 
so soon lost in the ordinary fibrous sheath of the nerve, that little exceptk
 
is taken to the descriptive expression ‘ piercing.' In the case of the trigemin
 
nerve, however, the evaginated covering of dura mater is better marked, and '
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1165
 
 
 
:he whole, looser; it envelops the roots of the nerve and the trigeminal
 
jlion, and is known as the cavum trigeminale (.Meckel's cave). The cavum
 
jminale, therefore, lies between the dura and the skull. The optic nerve,
 
eover, should not be described as ‘ piercing ’ the membrane, for the eye and
 
lervous stalk are developmentally parts of the brain itself, and the dura
 
er is carried along the nerve to become directly continuous with the sclerotic
 
: of the eye, which represents the same layer.
 
 
 
Some other nerves, such as the superficial petrosals and the nasoiry in a part of its course, lie deep to the dura mater, and will be
 
bribed later.
 
 
 
All the meningeal vessels lie between skull and dura mater, and do
 
pierce the inner membranous layer. The only things which pass
 
Dugh this layer are the cranial nerves and the cerebral vessels;
 
$e last are represented by (a) the internal carotid, which, lying
 
irst between dura and bone with the cavernous sinus, pierces the
 
nbrane medial to the anterior clinoid process to reach the brain;
 
 
 
. ( b ) the vertebral arteries, which pierce the membrane below the
 
11 and run up through the foramen magnum to reach the brain,
 
tain cerebral veins pierce the dura mater at various points (see p.
 
8 ) to open into extradural sinuses.
 
 
 
Hie aqueduct of cochlea is described as passing through the dura to reach
 
subarachnoid space, and the endolymphatic duct lies between the membrane
 
the bone.
 
 
 
Cranial Nerves at the Base of the Skull. —The cranial nerves are
 
inged in twelve pairs, and as they leave the cranial cavity they
 
five sheaths from the meninges of the brain.
 
 
 
The olfactory bulb rests upon one half of the cribriform plate of
 
ethmoid bone, with dura mater interposed. Through the fora1a of that plate it receives about twenty olfactory filaments, which
 
;e as the axons of the olfactory cells of the olfactory mucous
 
[nbrane of the nasal fossa.
 
 
 
The optic nerve passes forwards and outwards from the optic
 
asma to the optic foramen, through which it enters the orbit. It
 
.ccompanied by the ophthalmic artery, which lies below and lateral
 
t. Before reaching the foramen it is crossed by the anterior cerebral
 
ery, and the internal carotid comes through the dura mater just
 
dnd and lateral to it.
 
 
 
The third or oculo-motor nerve pierces the dura mater, which
 
ns the upper and outer wall of the cavernous sinus, a little in front
 
the posterior clinoid process of the sphenoid bone.
 
 
 
The fourth or trochlear nerve, of small size, pierces the dura mater
 
a point a little behind the posterior clinoid process of the sphenoid
 
ie, lateral to the third nerve, and in or just beneath the free margin
 
the tentorium cerebelli. Afterwards it traverses the outer wall of
 
: cavernous sinus.
 
 
 
The fifth or trigeminal nerve consists of two roots—sensory and
 
tor. These two roots pierce the dura mater near the apex of the
 
rous part of the temporal bone below the tentorium, and enter
 
 
 
 
 
 
 
n66
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
a'recess of the dura mater, called the cavurn ingeminate (Meckel's cav
 
where they will be presently described.
 
 
 
The sixth or abducent nerve pierces the dura mater £ inch behi
 
the level of the posterior clinoid process, and near the apex of t
 
petrous bone, where it enters the inferior petrosal sinus. It lies
 
little to the inner side of the fifth nerve.
 
 
 
The seventh or facial nerve, the eighth or auditory nerve, accoi
 
panied by the internal auditory artery, enter the internal meatus.
 
 
 
The ninth or glosso-pharyngeal nerve, the tenth or vagus ner
 
and the eleventh or accessory nerve pass through the middle compa:
 
 
 
 
 
 
 
Fig. 700.—Showing the Venous Sinuses on the Petrous Bone, and
 
 
 
Relation with the Trigeminal Nerve.
 
 
 
Also shows great superficial petrosal nerve.
 
 
 
ment of the jugular foramen. This foramen is divided into thi
 
compartments—namely, antero-medial, middle, and postero-later
 
The antero-medial compartment gives passage to the inferior petro.j
 
sinus. The middle compartment transmits the glosso-pharyngeal, vagi
 
and accessory nerves, in this order from before backwards. T
 
glosso-pharyngeal nerve pierces the dura mater separately, a
 
receives special sheaths from the dura mater and arachnoid membrai
 
The vagus and accessory nerves pass together through a sin^
 
aperture in the dura mater, and receive common sheaths from t
 
dura and arachnoid membrane. The postero-lateral compartment trai
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1167
 
 
 
 
 
5 the sigmoid sinus, which terminates in the internal jugular vein,
 
the vein is deep to the dura, this part of the foramen cannot be
 
1 directly when the dura mater is in position.
 
 
 
The twelfth or hypoglossal nerve pierces the dura mater in two
 
dies, which pass through separate apertures. As these bundles
 
5 through the anterior condylar canal they unite to form one nerve,
 
ween the points of exit of the hypoglossal and the last three nerves
 
jugular tubercle is seen, forming a very useful landmark.
 
 
 
Structures passing through the Foramen Magnum. —(1) The medulla
 
mgata, with its membranes, passes out and becomes the spinal
 
i. (2) The spinal root of the accessory nerve of either side, having
 
mded from the interval between the posterior roots of the cervical
 
lal nerves and the ligamentum denticulatum, enters the cranial
 
ity. It then turns outwards behind the jugular tubercle to the
 
Idle compartment of the jugular foramen, where it meets the
 
rial root of the nerve, with which it becomes closely connected
 
it passes through the foramen. (3) The vertebral artery of each
 
j enters the cranial cavity after having pierced the dura mater.
 
The two anterior spinal branches of the vertebral arteries descend
 
the front of the medulla oblongata, and, inclining inwards towards
 
h other, they unite in passing through the foramen magnum to
 
n the anterior spinal artery, the membrana tectoria, and the apical
 
ment of the odontoid process.
 
 
 
Trigeminal Ganglion (Gasserian Ganglion) (Fig. 700).—The trilinal ganglion occupies the trigeminal impression (Gasserian imssion) on the superior surface of the petrous part of the temporal
 
Le near the apex, where its posterior part lies in a recess of the
 
a mater, called the cavum trigeminale ( Meckel’s cave). It is someit semilunar, being convex in front and concave behind, and measures
 
y \ inch from before backwards. It is associated with the sensory
 
t of the fifth nerve, which, before entering the posterior concave
 
ect of the ganglion, becomes expanded, its fasciculi at the same
 
e becoming separated and assuming a plexiform arrangement,
 
lially the ganglion is intimately related to the back part of the
 
ernous sinus, and by its inner and lower aspect to the internal
 
otid artery in the foramen lacerum, and on this aspect it receives
 
icate filaments from the internal carotid sympathetic plexus. The
 
tor root of the fifth nerve, small in size, lies below the deep surface
 
:he ganglion; but there is no blending of the two sets of fibres, the
 
tor root passing independently in an outward direction to the
 
imen ovale. The greater superficial petrosal nerve, on its way to
 
foramen lacerum, passes beneath the ganglion, though not in the
 
r um trigeminale.
 
 
 
The ganglion contains cells similar to those of a spinal ganglion,
 
1 it receives its blood from the middle and accessory meningeal
 
eries. It is important in connection with modern surgery to notice
 
■t the front part of the ganglion does not lie in the cavum trininale, but has a close investment of dura mater. Hence the front
 
 
 
 
 
 
 
1168
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
part may be removed without opening the subarachnoid space
 
allowing cerebro-spinal fluid to escape.
 
 
 
Branches. —The branches of the ganglion arise from its anteri
 
convex aspect, and are known as divisions. They are as follow
 
the first or ophthalmic division; the second or maxillary divisio
 
and the third or mandibular division. The ophthalmic and maxilla
 
nerves are entirely sensory, but the mandibular nerve, being join
 
by the motor root, is both sensory and motor.
 
 
 
The first division of the trigeminal nerve, or the ophthalmic ner\
 
is the smallest of the three branches of the ganglion. It passes fc
 
wards in the outer wall of the cavernous sinus, where it lies below t]
 
fourth nerve. On approaching the superior orbital fissure it divid
 
into branches in the following order from behind forwards: (i) nas
 
ciliary (nasal), (2) lacrimal, and (3) frontal. All these three branch
 
enter the orbit through the superior orbital fissure. As the ophthaln
 
nerve passes forwards it receives a communicating branch from t'
 
internal carotid sympathetic plexus, and it furnishes the nervus tento>
 
to the tentorium cerebelli. It also communicates with each of t
 
oculo-motor, trochlear, and abducent nerves.
 
 
 
The naso-ciliary nerve, having passed through the orbit, re-ente
 
the skull by running between the orbital plate of the frontal and t'
 
upper surface of the ethmoid. It then lies deep to the dura mater <
 
the cribriform plate near its anterior extremity, and soon disappea
 
by passing down between this bone and the nasal area of the frontal
 
 
 
The second division of the trigeminal nerve, or the maxillary ner
 
(superior maxillary nerve), passes horizontally forwards for a she
 
distance in the lower part of the outer wall of the cavernous sinus, ai
 
it leaves the cranial cavity through the foramen rotundum, whi
 
leads to the pterygo-palatine fossa. Before leaving the cranial cavi
 
it furnishes the delicate meningeal nerve to the dura mater of tl
 
middle fossa.
 
 
 
The third division of the trigeminal nerve, or the mandibular ner
 
(inferior maxillary nerve), is the largest of the three branches of t.
 
ganglion. It passes downwards to the foramen ovale, through whi
 
it leaves the cranial cavity, and so enters the infratemporal foss
 
It is accompanied by the motor root of the fifth nerve, which joi
 
it as it passes through the foramen ovale. The nervus spinosus fre
 
the mandibular nerve is not given off until after the parent trui
 
has issued through the foramen ovale, and it enters the cranial cavi
 
through the foramen spinosum in company with the middle meninge
 
artery. It then divides into two branches, anterior and posterior. T
 
anterior branch supplies the dura mater over the greater wing of t
 
sphenoid bone, and the posterior branch passes through the fissr
 
between petrous and squamous parts of the temporal bone to supp
 
the mucous membrane of the mastoid air-cells.
 
 
 
Greater Superficial Petrosal Nerve. —This nerve is a branch of the gangli
 
of the facial nerve in the facial canal. It enters the middle fossa of the be
 
of the skull through its hiatus, and passes forwards and inwards in a groove
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1169
 
 
 
 
 
anterior surface of the petrous part of the temporal bone. Having passed
 
sath the trigeminal ganglion embedded in the dura mater, it enters the upper
 
of the foramen lacerum, where it is placed on the outer side of the internal
 
tid artery, and it joins the deep petrosal nerve from the internal carotid
 
pathetic plexus. In this manner the nerve of the pterygoid canal is formed,
 
:h enters the latter canal by its opening on the anterior aspect of the foramen
 
rum, and so reaches the spheno-palatine ganglion in the pterygo-palatine
 
i. The greater superficial petrosal nerve is accompanied by the superficial
 
osal branch of the middle meningeal artery.
 
 
 
jesser Superficial Petrosal Nerve. —This nerve represents the continuation
 
ugh the tympanic plexus of the tympanic branch (Jacobson's nerve) of the
 
30-pharyngeal nerve. It is reinforced by a small branch from the ganglion
 
he facial nerve, Avhich joins it as it traverses a small canal in the petrous
 
of the temporal bone beneath the canal for the tensor tympani muscle,
 
nerve enters the middle fossa through a small opening on the lateral side
 
he hiatus for the greater superficial petrosal nerve. It then passes for a
 
3 forwards and inwards, and leaves the cranial cavity through the canaliculus
 
iminatus (when present), or through the fissure between the petrous temporal
 
the greater wing of the sphenoid, or, it may be, through the foramen ovale,
 
r which it terminates in the otic ganglion.
 
 
 
External Petrosal Nerve. —This nerve, which is inconstant, passes from the
 
pathetic plexus on the middle meningeal artery backwards and outwards
 
:he anterior surface of the petrous part of the temporal bone, and it leaves
 
cranial cavity through a minute aperture situated within the thin margin
 
tie hiatus for the greater superficial petrosal nerve. It ends in the ganglion
 
re facial nerve.
 
 
 
 
 
Interior of the Cavernous Sinus.—The interior of this sinus ia
 
ken up by a network of delicate trabeculae. The outer wall of
 
sinus contains the following
 
rial nerves, in order from above
 
mwards: the oculo-motor, the
 
ihlear, the ophthalmic division
 
:he trigeminal, and the maxilr division of the fifth. These
 
ves, as they pass forwards,
 
separated from the bloodrent by the endothelial lining
 
the outer wall of the sinus.
 
 
 
J cavity of the sinus is travel by (1) the cavernous portion
 
the internal carotid artery,
 
rounded by a plexus of symhetic filaments; and (2) the
 
Lucent nerve, which lies in
 
>e contact with the outer side of the artery. These structures are
 
) separated from the blood-current by the endothelial lining of the
 
is.
 
 
 
For the processes and other sinuses of the dura mater see p. 1601.
 
Cavernous Portion of the Internal Carotid Artery.—This part of the
 
irnal carotid artery lies within the cavernous sinus, which occupies
 
carotid groove on the lateral aspect of the body of the sphenoid
 
ie. It is separated from the blood-current by the endothelial
 
 
 
74
 
 
 
 
 
Internal Carotid Artery
 
Abducent.Nerve
 
Oculo-motor Nerve
 
Trochlear Nerve
 
Ophthalmic Nerve
 
 
 
 
 
Sella Turcica
 
 
 
 
 
 
 
Maxillary Nerve
 
 
 
Left Sphenoidal Sinus
 
 
 
Fig. 701.—Diagram of the Left Cavernous Venous Sinus and its Outer
 
Wall, showing the Relative Positions of the Contained Structures
 
(Posterior View).
 
 
 
 
 
 
 
 
 
 
 
1170
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
lining of the sinus. The course of the vessel is at first upwan
 
between the lingula of sphenoid and the posterior petrosal process
 
the sphenoid; then forwards as far as the anterior clinoid process
 
the sphenoid; and finally upwards medial to the anterior clinc
 
process. In the latter situation it pierces the dura mater, whi
 
forms the roof of the cavernous sinus, and enters upon the cerebi
 
part of its course.
 
 
 
The vessel is accompanied by the internal carotid sympathe
 
plexus, and the abducent nerve lies in close contact with its out
 
side, all being invested by the endothelial lining of the sinus.
 
 
 
 
 
 
 
Fig. 702.—Right Internal Carotid put in Position on Base of Skui
 
 
 
and Crossed by Sixth Nerve.
 
 
 
Great superficial petrosal nerve is also seen.
 
 
 
Branches.—These are as follows: hypophysial, to the hypophys
 
cerebri; ganglionic, to the trigeminal ganglion; cavernous, to the w£
 
of the cavernous sinus, and to the oculo-motor, trochlear, trigemim
 
and abducent nerves; meningeal, to the dura mater of the midd
 
cranial fossa; and the ophthalmic artery. The latter vessel arises fro:
 
the cavernous portion of the internal carotid on the inner side of tl
 
anterior clinoid process, and it enters the orbit, with the optic nerv
 
through the optic foramen, lying at first beneath the nerve, and the
 
on its outer side.
 
 
 
The Medial Part of the Internal Carotid Sympathetic Plexus (Caveri
 
ous Plexus).—This plexus is situated principally on the inner and low<
 
aspects of the bend which the cavernous portion of the internal caroti
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1171
 
 
 
 
 
•y describes medial to the anterior clinoid process. Its branches
 
as follows; (1) vascular, to the internal carotid artery and its
 
ches; (2) hypophysial, to the hypophysis cerebri; (3) communing, to the oculo-motor, trochlear, ophthalmic division of the tri[nal, and abducent cranial nerves; and (4) the sympathetic root of
 
;iliary ganglion. The last-named branch enters the orbit through
 
superior orbital fissure.
 
 
 
"he hypophysis cerebri (pituitary body) is a small oval mass which
 
tuated in the hypophysial fossa, or sella turcica, of the sphenoid
 
It lies under cover of a circular fold of the dura mater, called the
 
hragma sellce, in the centre of which is an opening for the passage
 
le infundibulum. Its long measurement extends transversely, and
 
msists of two lobes—anterior and posterior. The anterior lobe is
 
larger of the two, and the posterior lobe is connected with the
 
rior part of the tuber cinereum by means of the infundibulum,
 
rhe infundibulum projects downwards from the anterior part of
 
tuber cinereum to the posterior lobe of the pituitary body. Its
 
sr part is hollow, and contains
 
mnel-shaped diverticulum of the
 
ty of the third ventricle.
 
 
 
tructure. —The anterior lobe consists of
 
ral tubules lined with epithelium, and
 
sted by capillary bloodvessels. The
 
jrior lobe, though developed from the
 
1, is destitute of nervous elements. It
 
imposed of a reticulum of connective
 
e, which contains branched cells. Bern the two lobes is the middle part.
 
 
 
)evelopment. —The anterior lobe is deped from a diverticulum of the buccal
 
tomatodaeal ectoderm, which is known
 
ie pouch of Rathke. The diverticulum
 
rs upwards, and, when the cranio•yngeal canal of early life becomes closed,
 
connection of the diverticulum with the
 
:al ectoderm is severed. The diverurn later on becomes converted into
 
lies, which form the anterior lobe, dhe
 
Brior lobe of the pituitary body and the
 
ndibulum, which is connected with it, are
 
sloped as a diverticulum which grows
 
nwards from that part of the diencephalon
 
:h forms the floor of the third ventricle. #
 
 
 
cavity of the diverticulum remains permanent in the upper part of its
 
ndibular portion, but elsewhere it becomes obliterated. The lower part of
 
diverticulum thereafter becomes converted into a reticulum of connective
 
ie with branched cells, which forms the posterior lobe.
 
 
 
 
 
 
 
Fig. 703. —Diagram of Anteroposterior Section through
 
the Hypophysis.
 
 
 
A, anterior lobe: PT, its pars
 
tuberalis. Pars Interm., pars
 
intermedia. N, neural or posterior lobe. INF, infundibulum. OPT. CH, optic chiasma.
 
 
 
 
 
Side of the Neck.
 
 
 
The side of the neck has a quadrilateral outline, the boundaries
 
which are as follows: superior, the lower border of the mandible
 
. a line prolonged from the angle of that bone over the mastoid
 
 
 
 
 
1172
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
process to the inner third of the superior rruchal line of the occipi
 
bone; inferior , the clavicle and one half of the upper border of 1
 
manubrium sterni; anterior , the middle line of the neck; and posteri
 
the outer border of the trapezius in the neck.
 
 
 
Landmarks.—The body and angle of the mandible can easily
 
felt, and the clavicle, together with the upper border of the manubrii
 
sterni, is conspicuous. A deep depression, called the supraster:
 
fossa, is perceptible above the upper border of the manubrium ster
 
lying between the sternal h'eads of origin of the sterno-mastoid muscl
 
The outline of the sterno-mastoid muscle is readily discernible when 1
 
head is turned so as to direct the face towards the opposite should
 
The muscle extends in a diagonal direction from the sterno-clavicu
 
joint to the mastoid process and outer half or two-thirds of the super
 
nuchal line of the occipital bone, and it divides the side of the ne
 
into two triangles—anterior and posterior. A small triangular inter
 
may be felt between the sternal and clavicular heads of origin of t
 
sterno-mastoid just above the inner end of the clavicle, in which t
 
common carotid artery and internal jugular vein lie deeply. T
 
external jugular vein crosses the sterno-mastoid muscle in the directi
 
of a line extending from a point just behind the angle of the mandil
 
to a point above the centre of the clavicle, and it is accompanied
 
the superficial cervical glands. The common carotid artery lies unc
 
cover of the anterior border of the sterno-mastoid muscle in the directi
 
of a line drawn from the sterno-clavicular joint to a point midw
 
between the angle of the mandible and the tip of the mastoid proc(
 
of the temporal bone. The vessel extends along this line as high
 
the level of the upper border of the thyroid cartilage, above which
 
is replaced by the external carotid artery. The internal jugular vt
 
is close to the outer side of the common carotid artery, and the vag
 
nerve lies deeply between the two vessels. If deep pressure is ma
 
over the common carotid artery on a level with the cricoid cartila
 
of the larynx, the anterior tubercle of the transverse process of t
 
sixth cervical vertebra may be felt. It is known as the carotid tuber
 
(of Chassaignac.)
 
 
 
The bifurcation of the innominate artery lies behind the upp
 
border of the right sterno-clavicular joint, and the left common carol
 
artery lies behind the left sterno-clavicular joint, while the lower pa
 
of the internal jugular vein on each side is behind the inner end
 
the clavicle. Near the middle line of the neck the anterior jugul
 
vein descends vertically. The spinal root of the accessory ner
 
passes downwards and outwards beneath the anterior border of t
 
sterno-mastoid to pierce the deep part of that muscle at about t
 
junction of the upper fourth and lower three-fourths. The nerve
 
met with fully 1 inch below the tip of the mastoid process, and in t
 
direction of a line let fall vertically from the mastoid tip. It is ve
 
nearly on a level with the body of the hyoid bone. Along the posteri
 
border of the sterno-mastoid some superficial cervical lymph glan
 
may be felt.
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii 73
 
 
 
 
 
Important structures occupy the middle line of the neck, and can
 
usually distinguished without difficulty. These are as follows, in
 
sr from above downwards: (1) the body of the hyoid bone, lying
 
; below the mandible, and having the greater horn projecting
 
kwards and upwards on either side; (2) the thyro-hyoid membrane;
 
the thyroid cartilage, with its laryngeal prominence (pomum
 
imi) in the middle line, leading up to the V-shaped thyroid notch
 
the upper border, and its expanded ala on either side, each of which
 
s behind in a superior and an inferior horn; (4) the crico-thyroid
 
ment; (5) the narrow anterior part of the cricoid cartilage, which
 
icides with the level at which the superior belly of the omo-hyoid
 
 
 
 
 
 
 
scle crosses the carotid sheath; and (6) the rings of the trachea,
 
ich, however, are covered superiorly by the isthmus of the thyroid
 
nd, and inferiorly by the sterno-hyoid and sterno-thyroid muscles
 
1 adipose tissue.
 
 
 
The lateral lobes of the thyroid gland may be felt on either side of
 
larynx and trachea as low as about the fifth ring; and in young
 
Idren the thymus extends upwards upon the trachea for some
 
tance above the manubrium sterni.
 
 
 
The greater horn of the hyoid bone is the guide to the lingual artery
 
, hypoglossal nerve for operative purposes, the structures lying just
 
ve the greater horn.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1174
 
 
 
The upper border of the thyroid cartilage is on a level with the di
 
between the bodies of the third and fourth cervical vertebra.
 
 
 
The narrow anterior part of the cricoid cartilage is on a level wi
 
the disc between the bodies of the fifth and sixth cervical vertebrae,
 
which level the pharynx becomes the oesophagus. In this situatior
 
foreign body, when swallowed, is liable to become impacted.
 
 
 
Below the cricoid, in the middle line, one or two rings of the trach
 
may be felt above the thyroid isthmus, and it is here that a hi
 
tracheotomy is performed, an easy operation since the windpipe is
 
 
 
 
 
 
 
Fig. 705. —Superficial Dissection.
 
 
 
 
 
close to the skin. Below the isthmus the trachea rapidly recedes,
 
that a low tracheotomy is often a difficult and sometimes a ve
 
dangerous operation; dangerous because, often in children and son
 
times in the adult, the left innominate vein lies in the suprasterr
 
region above the level of the manubrium sterni, and so in the way
 
the knife. Ignorance of this fact has meant, and may mean aga
 
the loss of a life.
 
 
 
Above the middle third of the clavicle, between the sterno-mash
 
and trapezius muscles, there is a depression known as the greai
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii 75
 
 
 
 
 
aclavicular fossa, which indicates the position of the subclavian
 
lgle, with the third part of the subclavian artery and the trunks
 
ie brachial plexus of nerves.
 
 
 
Platysma (Platysma Myoides)— Origin .—The superficial fascia which
 
>rs the clavicular parts of the pectoralis major and deltoid muscles.
 
Insertion. —(1) The outer part of the body of the mandible from
 
symphysis menti to the anterior border of the masseter muscle;
 
(2) the angle of the mouth, where the fibres blend with those of
 
depressor anguli oris and orbicularis oris.
 
 
 
Nerve-supply .—The cervical branch of the facial nerve, which comlicates with branches of the anterior cutaneous nerve of the neck.
 
The fibres are directed upwards and forwards or inwards over the
 
dele and side of the neck.
 
 
 
Action. —(1) To draw the angle of the mouth downwards and outds; (2) to act as a feeble depressor of the mandible; (3) to raise the
 
1 of the neck and upper pectoral region as far out as the acromion
 
cess, throwing it into obliquely-disposed folds.
 
 
 
The muscle forms an extensive, thin, pale sheet, which is embedded
 
hin the superficial fascia. In the region of the symphysis menti
 
innermost fibres decussate across the middle line with those of the
 
>osite side, the fibres of the right muscle being superficial. The
 
scle covers the external and anterior jugular veins, the superficial
 
nches of the cervical plexus of nerves, the subclavian triangle, and
 
sterno-mastoid, sterno-hyoid, omo-hyoid, and digastric muscles.
 
 
 
The platysma in man is a remnant of a subcutaneous muscular sheet, called
 
panniculus carnosus, which exists in many animals, and by which the twitchof the skin is produced.
 
 
 
Jugular Veins.—The jugular veins are four in number on either
 
e—anterior, external, posterior external, and internal.
 
 
 
The anterior jugular vein begins in the roof of the digastric triangle,
 
Lere it is formed by the union of radicles which communicate with
 
3 submental vein, and are joined by radicles which have descended
 
>m the structures over the body of the mandible. It descends
 
rtically near the median line, lying at first superficial to the deep
 
rvical fascia, but subsequently entering the suprasternal space. II
 
en describes a bend, and, passing outwards behind the sternoistoid muscle, and in front of the scalenus anterior, it opens
 
to the lower part of the external jugular vein. It may, however,
 
>en into the subclavian vein. It communicates with the external
 
gular vein by one or more tributaries, and usually receives a branch
 
3 m the facial vein which descends along the anterior border of the
 
erno-mastoid and joins it towards the lower part of the neck,
 
urther, it communicates with its fellow, of the opposite side by a
 
ansverse branch, the jugular arch, which crosses in front of the
 
achea, and lies in the suprasternal space.
 
 
 
The anterior jugular veins are usually asymmetrical, one or other
 
sing of small size. Occasionally there is only one vein, which divides
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1176
 
 
 
into two vessels interiorly. The anterior jugular vein is destitute ^
 
valves.
 
 
 
The external jugular vein commences close behind the angle of tl
 
mandible in the substance of the parotid gland, where it is formed t
 
the union between the posterior division of the posterior facial ve:
 
and the posterior auricular vein. On leaving the parotid gland
 
descends almost vertically to a point above the centre of the clavicl
 
In its course the vessel crosses the sterno-mastoid muscle, lying supe
 
ficial to its sheath, and deep to the superficial fascia containing tl
 
fibres of the platysma. At this level the main part of the anteri<
 
 
 
 
 
 
 
Fig. 706. —Superficial Veins of Neck.
 
 
 
SF, CF, superficial and common facial. TM, posterior facial or temporo-maxillar
 
PA, posterior auricular. PJ, EJ, AJ, posterior, external, and anterior juguls
 
 
 
cutaneous nerve of -the neck runs forward deep to the vein, and offse
 
of the nerve pass superficial to it. Having crossed the sterno-masto
 
muscle, the vein descends not far from its posterior border, where
 
lies in the roof of the subclavian triangle over the third part of tl
 
subclavian artery. Up to this point the vessel is superficial to tl
 
deep cervical fascia, but it now pierces that fascia and opens into tl
 
subclavian vein.
 
 
 
The course of the external jugular vein is indicated by a line draw
 
from a point close behind the angle of the mandible to a point abo^
 
the centre of the clavicle. Its tributaries are as follows: (1) poster!
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1177
 
 
 
 
 
3rnal jugular, which joins it about the middle of the neck; (2) trans;e cervical; (3) suprascapular; and (4) anterior jugular, the latter
 
;e joining it not far from its termination. It also communicates
 
1 the anterior jugular vein by one or more branches. The vessel
 
rovided with valves, both at its termination and about i\ inches
 
ve this point, and the transverse cervical and suprascapular veins
 
 
 
 
 
isterior Auricular
 
Lymph Glands
 
 
 
Occipital Vein
 
 
 
;al Lymph Gland
 
 
 
>r Auricular Vein
 
 
 
terior Division of
 
;erior Facial Vein
 
 
 
iperficial Cervical
 
Lymph Glands
 
 
 
 
 
osterior External
 
Jugular Vein
 
 
 
mal J ugular Vein
 
 
 
 
 
:rse Cervical Vein_
 
 
 
 
 
 
 
 
 
P, ,
 
 
 
whi 1 \n\
 
 
 
 
 
_Supratrochlear Vein
 
 
 
-Supra-orbital Vein
 
 
 
- Angular Vein
 
 
 
 
 
Superficial Temporal Vein
 
Maxillary Vein
 
 
 
 
 
Posterior Facial Vein
 
Anterior Facial Vein
 
 
 
Ant. Div. of Posterior
 
Facial Vein
 
 
 
Submandibular Lymph
 
Glands
 
 
 
Common Facial Vein
 
Internal J ugular Vein
 
Lingual Vein
 
 
 
Superior Thyroid Vein
 
 
 
 
 
Middle Thyroid Vein
 
 
 
 
 
Anterior Jugular Vein
 
 
 
. Suprasternal Lymph
 
Gland
 
 
 
 
 
. 1 ■"
 
 
 
 
 
Suprascapular Vein and.Supraclavicular;
 
Lymphatic Glands
 
 
 
 
 
r. 707. —The Superficial Veins and Superficial Lymph Glands of the
 
 
 
Right Side of the Head and Neck.
 
 
 
The platysma muscle has been removed.
 
 
 
 
 
i also furnished with valves where they open into the external
 
;ular vein, or near their orifices.
 
 
 
The external jugular vein is sometimes very small, or even absent,
 
I it may communicate with the cephalic vein by a vessel which
 
sses over the clavicle.
 
 
 
r
 
 
 
Development. —The external jugular vein was formerly regarded as being
 
sloped from the anterior cardinal vein; but according to most authorities
 
anterior cardinal vein gives rise to the internal jugular vein, the external
 
ular being of later development.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1178
 
 
 
The posterior external jugular vein represents the most exter:
 
occipital vein, and is formed by tributaries which issue from the ou
 
part of the occipital plexus, reinforced by veins from the superfic
 
structures at the back of the neck. It usually receives the mast'
 
emissary vein and passes downwards and forwards, joining the exter:
 
jugular vein about the middle of the neck.
 
 
 
The internal jugular vein will be found described on p. 1211.
 
 
 
Superficial Cervical Lymph Glands.— These are about six in numb
 
and they lie upon the sterno-mastoid muscle, along the course of 1
 
external jugular vein, and deep to the superficial fascia and platysi
 
muscle. They receive their afferent lymphatics from the adjac<
 
superficial structures, the occipital and mastoid lymph glands, a
 
some of those of the parotid and submandibular lymph glands. Tb
 
efferent lymphatics pass to the deep cervical lymph glands.
 
 
 
Deep Cervical Fascia. —The deep cervical fascia is divided ii
 
(1) a superficial investing layer, which completely invests the neck
 
the form of a collar; and (2) deep processes or laminae, which inv
 
the muscles, viscera, and chief bloodvessels and nerves.
 
 
 
Investing Layer. —This layer is attached posteriorly to the li\
 
mentum nuchae; superiorly to (1) the superior nuchal line of the oc
 
pital bone, (2) the mastoid process of the temporal bone, (3) the zyj
 
matic arch, and (4) the body of the mandible, under cover of 1
 
platysma, as far forwards as the symphysis menti; and interiorly
 
the clavicle and upper border of the manubrium sterni, being pierc
 
above the centre of the clavicle by the external jugular vein. Ale
 
the middle line of the neck anteriorly it is continuous with the invest]
 
layer of the opposite side.
 
 
 
The investing layer invests the cervical portion of the trapezi
 
and from the anterior border of that muscle it passes forwards 0 1
 
the posterior triangle of the neck to the posterior border of the sten
 
mastoid. In doing so it furnishes a deep process, which ensheat]
 
the inferior belly of the omo-hyoid muscle. This process also embra^
 
the intermediate tendon of that muscle, after which it passes dov
 
wards and inwards to be attached to the back of the inner end of 1
 
clavicle and the first rib. In this manner the horizontal position
 
the inferior belly of the omo-hyoid is accounted for. When the
 
vesting layer of the deep cervical fascia reaches the posterior bore
 
of the sterno-mastoid it splits into two laminae, which ensheathe tl
 
muscle, the superficial lamina being underneath the external jugu
 
vein and platysma. At the anterior border of the sterno-mastoid 1
 
two laminae reunite, and the fascia passes forwards over the anter
 
triangle of the neck to the median line, where it is continuous with 1
 
corresponding layer of the opposite side.
 
 
 
Between the upper part of the anterior border of the sterno-masb
 
and the angle of the mandible the investing layer is of considera
 
strength, and draws that border of the muscle forwards and upwar
 
so as to render it convex and keep it over the line of the leading vess<
 
Between the mastoid process and the angle of the mandible the
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1179
 
 
 
 
 
ting layer is prolonged upwards over the parotid gland as the parotid
 
:ia, which is very dense, and is attached superiorly to the lower
 
der of the zygomatic arch.
 
 
 
Below the level of the thyroid gland the investing layer divides
 
0 two laminae, anterior and posterior, both of which are superficial
 
the infrahyoid muscles. At the middle line these laminae are conuous with those of the opposite side, and inferiorly they are attached
 
the anterior and posterior margins of the upper border of the
 
nubrium sterni. Between them there is an interfascial interval,
 
led the suprasternal space (space of Burns). This interval contains
 
:olar tissue, one or more lymphatic glands, the lower portions of the
 
terior jugular veins, with the jugular arch which here connects
 
im, and the sternal heads of the sterno-mastoid muscles.
 
 
 
Deep Processes or Laminae.— The deep laminae, as stated, invest the
 
iscles, viscera, and chief bloodvessels and nerves. The most imrtant are derived from that lamina of the investing layer which
 
ms the posterior wall of the sheath of the sterno-mastoid muscle,
 
d they are three in number—namely, carotid sheath, pretracheal
 
icia, and prevertebral fascia—all of which have an intimate initial
 
nnection.
 
 
 
The carotid sheath contains in separate compartments (1) the
 
mmon carotid artery and the constituents of the ansa hypoglossi,
 
the internal jugular vein, and (3) the vagus nerve, the latter being
 
ntained within the back part of the septum, which separates the
 
tery from the vein.
 
 
 
The pretracheal fascia, which is at first intimately connected with
 
e anterior wall of the carotid sheath, passes forwards behind the
 
frahyoid muscles, in which situation it splits to ensheathe the
 
yroid gland, trachea, and oesophagus, and then it passes to the
 
sdian line, where it is continuous with the pretracheal fascia of the
 
•posite side. The pretracheal fascia is attached superiorly to the
 
>dy of the hyoid bone, and inferiorly it descends over the trachea
 
Ld bloodvessels into the superior mediastinum of the thorax, where it
 
ends with the fibrous pericardium.
 
 
 
The prevertebral fascia, which is at first intimately connected with
 
e posterior wall of the carotid sheath, passes forwards behind the
 
larynx and oesophagus, and in front of the prevertebral muscles,
 
t the middle line it is continuous with the corresponding fascia of
 
e opposite side; superiorly it is attached to the base of the skull;
 
id inferiorly it descends over the longus cervicis muscle into the
 
isterior mediastinum of the thorax. Along a line corresponding to
 
le inner wall of the carotid sheath the pretracheal fascia furnishes a
 
condary lamina, called the bucco-pharyngeal fascia, which covers
 
ie constrictor muscles of the pharynx and the buccinator muscle,
 
etween the bucco-pharyngeal and prevertebral fasciae there is an
 
terval, called the retro-pharyngeal space, which contains the loosely
 
'ranged connective tissue uniting the two fasciae. This space extends
 
high as the base of the skull, and inferiorly is continuous with the
 
 
 
 
 
ii8o
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
posterior mediastinum of the thorax. Another process of the pi
 
vertebral fascia passes downwards and outwards in front of t
 
scalenus anterior muscle. After this it invests the third part of t
 
subclavian artery and subclavian vein, together with the nerve-trun
 
of the brachial plexus, and, passing behind the clavicle, it becom
 
continuous with the axillary sheath, which latter blends with t
 
posterior aspect of the clavi-pectoral fascia. In the region of the su
 
clavian triangle there is an interfascial space between this proce
 
of the pretracheal fascia and the investing layer of the deep cervic
 
fascia. This space extends downwards behind the clavicle to the poi
 
where the axillary sheath and clavi-pectoral fascia join. It contai
 
 
 
 
 
Stemo- thyroid
 
Sterno-hyoid
 
 
 
Investing Layer of Deep Cervical Fascia
 
Superior Belly of Omo-hyoid
 
Pretracheal Fascia
 
Prevertebral Fascia
 
 
 
 
 
Suprasternal Space
 
Trachea
 
 
 
Muscular Compartment
 
 
 
Lateral Lobe of Thyroid Gland
 
 
 
 
 
Carotid Sheath
 
 
 
 
 
Scalenus Anterior
 
 
 
 
 
Scalenus Medius
 
 
 
 
 
Levator Scapulae
 
 
 
Semispinalis Capitis
 
 
 
 
 
 
 
(Esophagus
 
 
 
Descendens hypoglossi
 
^ Common Carotid Artery
 
Internal Jugular Vein
 
- Vagus Nerve
 
Platysma
 
 
 
 
 
Splenius
 
 
 
 
 
Sympathetic Trunk
 
 
 
Longus Cervicis
 
- Stemo-mastoid
 
 
 
 
 
External Jugular V<
 
 
 
 
 
' Vertebral Vessels
 
 
 
 
 
Trapezius
 
 
 
 
 
Semispinalis Cervicis
 
 
 
 
 
Tig. 708. Diagram of a Transverse Section of the Neck at the Lev
 
of the Sixth Cervical Vertebra, showing the Arrangement of ti
 
Deep Cervical Fascia and the Positions of Other Structures.
 
 
 
 
 
the inferior belly of the omo-hyoid muscle, the suprascapular ar
 
transverse cervical vessels, the lower part of the external jugular vei
 
and the terminal portion of the anterior jugular vein.
 
 
 
Interfascial Compartments. —It has been stated that the det
 
cervical fascia reaches the median line of the neck anteriorly in thr
 
layers—namely, investing (in two divisions), pretracheal, and pr
 
vertebral. It is therefore evident that there are four interfasci
 
compartments as follows: (1) the suprasternal space (space of Burn!
 
which is situated between the two divisions of the investing layer, ai
 
contains the structures already enumerated; (2) the muscular cor
 
partment, which is situated between the investing layer and the pr
 
tracheal layer, and contains the infrahyoid muscles; (3) the viscer
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1181
 
 
 
 
 
partment, which lies between the pretracheal and prevertebra
 
rs, and contains the larynx, trachea, thyroid gland, pharynx,
 
phagus, and carotid sheath, the retro-pharyngeal space being in
 
subdivision of this compartment behind the bucco-pharyngeal
 
ia; and (4) the vertebral compartment, which lies between the
 
vertebral layer and the attachment of the fascia to the ligamentum
 
iae posteriorly, and contains the vertebral column, spinal cord, and
 
vertebral and postvertebral muscles.
 
 
 
rhe suprasternal and muscular compartments are shut off from
 
thoracic cavity. The visceral compartment in front of the trachea
 
mtinuous with the superior mediastinum of the thorax, and behind
 
oesophagus it, along with the retro-pharyngeal space, is continuous
 
1 the posterior mediastinum.
 
 
 
Parotid Process of the Deep Cervical Fascia. —This process is given
 
a little below the angle of the mandible, and it passes upwards on
 
deep surface of the parotid gland to the skull. Along with the
 
Dtid fascia superficial to the gland it forms a dense sheath which
 
ely invests the glandular substance. The parotid process furnishes
 
aths to the posterior belly of the digastric, styloid, and pterygoid
 
scles, and it also gives an investment to the superficial part of the
 
mandibular gland. Connected with the parotid process there are
 
sral bands, usually called ligaments, which are as follows: (1) sphenoadibular; (2) stylo-mandibular; (3) pterygo-mandibular; and
 
 
 
pterygo-spinous.
 
 
 
The spheno-mandibular ligament will be described in connection
 
h the mandibular joint, of which it is sometimes regarded as an
 
essory medial ligament (see p. 1316).
 
 
 
The stylo-mandibular ligament extends from the styloid process of
 
temporal bone near its tip to the angle and adjacent part of the
 
terior border of the ramus of the mandible, where it is placed
 
ween the masseter and internal pterygoid muscles.
 
 
 
The pterygo-mandibular ligament is a narrow band which extends
 
hi the hamulus of the medial pterygoid plate of the sphenoid bone
 
the posterior extremity of the mylo-hyoid line of the mandible
 
$e to the last molar socket. Anteriorly it gives origin to fibres of
 
buccinator muscle, and posteriorly to fibres of the superior condor muscle of the pharynx.
 
 
 
The pterygo-spinous ligament is a narrow band which extends from
 
harp spine on the posterior border of the lateral pterygoid plate of
 
sphenoid bone, towards its upper part, to the spine process of the
 
lenoid. This ligament is liable to become ossified.
 
 
 
The foregoing description is orthodox and traditional, and every fact stated
 
be demonstrated by a good dissector; but there are some observers who
 
3rd the whole of these fascial planes as artifacts, and believe that all the
 
irstices between the structures in the neck are filled with loose connective
 
ue which, when it is cleaned from the surrounding parts, collapses into
 
Y definite sheets. If this is the case, it should be possible, by varying the
 
action of the incisions, to produce sheets in any plane. As a matter of fact,
 
> can be done.
 
 
 
 
 
Il82
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Sterno-mastoid — Origin .—The sternal head, which is narrow ar
 
round, arises from the upper and outer part of the anterior surfa*
 
of the manubrium sterni. It is tendinous in front, and fleshy behin
 
The clavicular head, which is broad and flat, arises from a rough rid|
 
about ij inches long on the upper surface of the clavicle at its inn
 
end.
 
 
 
Insertion .—The outer surface of the mastoid process of the ter
 
poral bone, and the superior nuchal line of the occipital bone ov
 
about its outer half or two-thirds.
 
 
 
 
 
 
 
Fig. 709. —Showing Sterno-mastoid and the Muscular Floor of
 
 
 
Posterior Triangle.
 
 
 
 
 
 
 
 
 
Nerve-supply .—The accessory nerve, and a branch from the cervic
 
plexus, more particularly from the anterior primary ramus of the secor
 
cervical nerve.
 
 
 
The spinal root of the accessory nerve passes deep to the anteri
 
border of the muscle fully 1 inch below the tip of the mastoid proces
 
and in passing downwards and backwards it pierces the deep part
 
the muscle, giving off as it does so its branches to it.
 
 
 
The muscle is directed upwards, outwards, and backwards.
 
 
 
Action .—To flex the head towards the side on which the muse
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1183
 
 
 
aced, the face being turned towards the opposite side. This is
 
position of the head in torticollis or wry-neck, a condition which
 
be due to an organic contraction to the muscle, affecting both
 
s, or, it may be, the sternal head alone. When both muscles act
 
ther from their origin they flex the head towards the thorax,
 
when the head has been already thrown back the sterno-mastoid
 
ls capable of extending it still farther instead of flexing it. It
 
t be remembered, however, that a certain amount of flexion of
 
lead may take place between any of the cervical vertebrae. When
 
muscles act together from their insertion they elevate the upper
 
of the anterior thoracic wall in forced inspiration.
 
 
 
"he sternal and clavicular heads are separated by a triangular
 
Jar interval for a short distance above the sterno-clavicular joint,
 
before their junction the fibres of the clavicular head to a large
 
nt pass behind those of the sternal head, so that overlapping
 
s place. The muscle is surrounded by a strong sheath, which is
 
led by the deep cervical fascia. The platysma covers a large part
 
:, and the external jugular vein, the anterior cutaneous nerve of
 
: and great auricular nerves, and the superficial cervical lymph
 
ds are related to its superficial surface under cover of the platysma.
 
principal deep relations are as follows: in the lower part of the
 
: it covers the first and second parts of the subclavian artery, the
 
10-hyoid, sterno-thyroid, omo-hyoid, and scalenus anterior muscles,
 
l the phrenic nerve lying upon the last-named muscle. In this
 
rtion it also covers the anterior jugular vein, and the transverse
 
ical and suprascapular arteries. Higher up it covers the cervical
 
;us of nerves, the levator, scapulae, scalenus medius, and scalenus
 
erior muscles, and the accessory and the hypoglossal nerves. At
 
insertion it covers the splenius capitis, longissimus capitis, and
 
:erior belly of the digastric muscles, and a portion of the occipital
 
ry, in this order from the surface downwards. The anterior border
 
he muscle forms the posterior boundary of the anterior triangle of
 
neck, and covers the carotid sheath, with its contents, as high as
 
level of the upper border of the thyroid cartilage ; and above that
 
1 it covers the external and internal carotid arteries. This border
 
overlaps slightly the lateral lobe of the thyroid gland.. The
 
;erior border forms the anterior boundary of the posterior triangle
 
he neck, and along it there lie the following structures: the superI cervical lymph glands, the lesser occipital nerve, great auricular,
 
nrior cutaneous nerve of neck, the accessory, and the descending
 
srficial branches of the cervical plexus of nerves, and a portion of
 
external jugular vein.
 
 
 
The sterno-mastoid muscle, from its diagonal position upon the
 
; of the neck, divides the quadrilateral space into two triangles terior and anterior.
 
 
 
Posterior Triangle. —This is the region which lies behind the sterno>toid muscle.
 
 
 
Boundaries — Anterior. —The posterior border of the sterno-mastoid.
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1184
 
 
 
Posterior .—The anterior border of the trapezius. Inferior (base).—
 
middle third of the clavicle. The apex is at the superior nuchal
 
of the occipital bone, where the sterno-mastoid and trapezius may n
 
but the apex is usually truncated. The roof is formed by the ;
 
superficial and deep fasciae, and for a short distance interiorly by
 
platysma. The lesser occipital nerve lies in the upper part of
 
roof, and the descending superficial branches of the cervical pi
 
and the external jugular vein lie in the lower part of the roof,
 
floor is formed by the following muscles, in order from above dc
 
wards: (1) small angle of the semispinalis capitis, provided the trapt
 
 
 
 
 
 
 
is not well developed at the occiput; (2) the splenius capitis; (3)
 
levator scapulae; (4) the scalenus medius and scalenus poster
 
(5) the scalenus anterior; and (6) the first digitation of the sern
 
anterior if the clavicle is depressed.
 
 
 
The posterior triangle is subdivided by the inferior belly of
 
omo-hyoid into a large upper portion, called the occipital trian
 
and a small lower portion, called the subclavian triangle.
 
 
 
Occipital Triangle—Boundaries — Anterior .—The posterior boi
 
of the sterno-mastoid. Posterior .—The anterior border of
 
trapezius. Inferior (base). —The inferior belly of the omo-hy
 
The muscles in its floor are (1) a small angle of the semispinalis caj
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1185
 
 
 
instant), (2) splenius capitis, (3) levator scapulae, and (4) scalenus
 
.ius and posterior. The contents are the superficial branches of the
 
ical plexus, the accessory nerve, the branches of the cervical
 
:us to the levator scapulae and trapezius, a small part of the occipital
 
ry close to the apex, and some superficial cervical lymph glands.
 
 
 
t should be realized that the foregoing gives a picture of the triangle as seen
 
le dissected body. In life and in the undissected part it is little more than
 
tter, the anterior edge of the trapezius being only about \ inch from the
 
srior border of the sterno-mastoid.
 
 
 
 
 
Parotid Duct
 
Buccinator Muscle
 
 
 
Facial Artery
 
Submental Artery
 
 
 
 
 
Lingual Artery
 
Sup. Lar. Art. and Nerve
 
Thyro-hyoid Muscle
 
Superior Thyroid Artery
 
 
 
 
 
 
 
.Transverse Facial Artery
 
 
 
 
 
, Superficial Temporal Artery
 
 
 
- Maxillary Artery
 
 
 
/_Posterior Auriculat
 
 
 
wma ^ . Artery
 
 
 
Occipital Artery
 
 
 
 
 
-Stylo-hyoid Muscle
 
 
 
-Post. Belly of Digastric
 
 
 
-Hypoglossal Nerve
 
 
 
_Descendens Hypogloss'
 
 
 
_External Carotid
 
 
 
Artery
 
 
 
 
 
-Sterno-mastoid
 
 
 
.— w Trapezius
 
 
 
 
 
_Transverse Cervical Artery
 
 
 
-. Suprascapular
 
Artery
 
 
 
 
 
Inf. Belly of Omo-hyoid
 
 
 
Subclavian Artery
 
(third part)
 
 
 
 
 
, y 1, An
 
 
 
Fig. 711.—The Left Side of the Head and Neck.
 
The platysma has been removed.
 
 
 
 
 
 
 
Cervical Plexus. —The cervical plexus lies deep to the upper part
 
:he sterno-mastoid muscle, and immediately in front of the slips
 
•rigin of the scalenus medius. It is formed by the anterior primary
 
ii of the first three cervical nerves and the greater part of that of
 
fourth, a small branch of the latter descending to join the anterior
 
nary ramus of the fifth, and so taking part in the brachial plexus,
 
h of the anterior primary rami of the first four cervical nerves is
 
nected with the superior cervical ganglion of the sympathetic by
 
'ey ramus communicans.
 
 
 
 
 
75
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1186 A MANUAL OF ANATOMY
 
 
 
The anterior primary ramus of the first cervical nerve lies at f
 
in the vertebrarterial groove of the atlas below the vertebral arte
 
It then passes forwards in a groove on the outer surface of the supei
 
articular process of the atlas, having the vertebral artery on its or
 
side. It next emerges between the rectus capitis lateralis mu;
 
(to which it gives a branch) and the rectus capitis anterior, ;
 
descends in front of the root of the lateral mass of the atlas to join
 
ascending branch of the second nerve. From the loop so forr
 
 
 
 
 
Vagus
 
 
 
 
 
Lesser Occip. N.
 
 
 
 
 
N.toTh
 
 
 
Int. La
 
 
 
Ne
 
 
 
 
 
Accessory Nerve ..
 
 
 
 
 
Ext. Li
 
Nerv
 
 
 
 
 
Descent
 
Hvpog
 
Desc. C
 
 
 
 
 
Ansa
 
 
 
 
 
Ant. Jv
 
 
 
 
 
Fig. 712.—Deep Relations of Sterno-mastoid, showing Cervical
 
 
 
Plexus, etc.
 
 
 
 
 
branches are given to the rectus capitis anterior and the longus cap
 
muscles, and one or more branches pass to the hypoglossal nerve,
 
destination of their fibres being the ramus descendens cervicalis 2
 
the nerves to thyro-hyoid and genio-hyoid.
 
 
 
The anterior primary rami of the second, third, and fourth cervi
 
nerves, having emerged between the corresponding intertransversa
 
muscles, form a superficial and a deep part of the plexus, of wh
 
the superficial is altogether cutaneous, while the deep is divided h
 
 
 
 
 
Phrenic
 
 
 
 
 
Upper Cord of
 
Brachial Plexus
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1187
 
 
 
 
 
tor and communicating branches. It will also be found that the
 
p plexus consists of an external and an internal set of branches.
 
Superficial Group. —The branches of this group are ascending,
 
nsverse, and descending.
 
 
 
The ascending and transverse branches arise from the second and
 
:d cervical nerves.
 
 
 
The ascending nerves are the lesser occipital and great auricular
 
; p. 1141). The transverse branch is the anterior cutaneous nerve
 
:he neck.
 
 
 
The anterior cutaneous nerve of the neck (superficial cervical nerve)
 
 
 
;es by two roots from the anterior primary rami of the second and
 
 
 
 
 
 
 
Fig. 713. —Scheme of Cervical Plexus.
 
superficial plexus red ; deep plexus black. I., E., medial and^lateral sides.
 
 
 
 
 
'rd cervical nerves, and, turning round the posterior border of the
 
Tno-mastoid muscle, it passes forwards superficial to that muscle,
 
ng deep to the platysma and the external jugular vein. Having
 
iched the anterior triangle of the neck, it divides into two branches,
 
:ending and descending, which are distributed to the integument
 
er the anterior triangle. The offsets of the ascending branch commicate freely with the cervical branch of the facial nerve deep to the
 
itysma.
 
 
 
The descending branches are the medial, intermediate, and lateral
 
3 raclavicular nerves, and they arise in common from the third and
 
irth cervical nerves. As they descend they form distinct nerves,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
n88
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
which lie on the roof of the subclavian triangle under cover of t
 
platysma. For their distribution see p. 412.
 
 
 
Deep Group. —The nerves of this group are arranged in two sets
 
external and internal.
 
 
 
External Set .—These nerves are muscular. The second ner
 
furnishes a branch to the sterno-mastoid, which communicates in tb
 
muscle with the branch of the accessory nerve. The third and four
 
 
 
 
 
 
 
Fig. 714. —Superficial Branches of Cervical Plexus.
 
 
 
SO, lesser occipital; GA, greater auricular; TC, anterior cutaneous;
 
DC, descending supraclavicular; XI, accessory nerve.
 
 
 
 
 
nerves furnish (a) two branches to the trapezius, which communicc
 
with the accessory nerve deep to the upper part of the muscle formi
 
the subtrapezial plexus; ( b) two branches to the levator scapulae; a
 
(c) branches to the scalenus medius.
 
 
 
Internal Set .—The nerves of this set are communicating a
 
muscular.
 
 
 
The communicating branches are as follows: (1) connecting brand
 
(grey rami communicantes) pass from the superior cervical gangli
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1189
 
 
 
 
 
the sympathetic; (2) communicating branches pass to the vagus
 
d hypoglossal nerves from the highest loop of the plexus; and
 
two rami communicantes cervicales pass from the second and third
 
rves forwards and downwards, usually superficial, but sometimes
 
ep to the internal jugular vein, and join the descendens hypoglossi,
 
aether or separately, to form the ansa hypoglossi.
 
 
 
The muscular branches are distributed to the rectus capitis lateralis,
 
:tus capitis anterior and longus capitis, upper part of the scalenus
 
terior, longus cervicis, and the diaphragm. The nerve to the
 
iphragm is the phrenic, which, from its importance, requires a special
 
scription.
 
 
 
The phrenic nerve arises, as a rule, by two roots, the larger of
 
lich is derived from the anterior primary ramus of the fourth cervical
 
rve, and the other from that of the third. In some cases the fifth
 
rvical nerve, which enters into the brachial plexus, furnishes an
 
ditional small root. In the neck the nerve descends in front of the
 
ilenus anterior muscle, which it crosses obliquely downwards and
 
wards, passing deep to the intermediate tendon of the omo-hyoid
 
uscle, the transverse cervical and suprascapular arteries, the anterior
 
gular vein, and, on the left side, the thoracic duct. At the root of
 
e neck the nerve, having left the scalenus anterior, passes behind
 
e terminal part of the subclavian vein, and crosses in front of the
 
ternal mammary artery from without inwards. Having come into
 
ntact with the inner surface of the cupola of the pleura, it disappears
 
kind the inner end of the clavicle, and enters upon the thoracic part
 
its course (see p. 1015).
 
 
 
The right nerve at the root of the neck is superficial to the second
 
irt of the right subclavian artery, with the intervention of the
 
alenus anterior muscle. The left nerve at the root of the neck is
 
iterior and parallel to the first part of the left subclavian artery.
 
 
 
The phrenic nerve is sometimes reinforced towards the root of the
 
ick by a branch from the nerve to the subclavius muscle, and when
 
is takes place the root from the fifth cervical nerve is usually absent,
 
efore leaving the neck the phrenic nerve receives a twig from the
 
iddle or inferior cervical ganglion of the sympathetic.
 
 
 
No branches arise from the phrenic nerve in the neck.
 
 
 
Lower Group of Deep Cervical Lymph Glands (Supraclavicular
 
pmph Glands). —These glands lie in the anterior part of the subclavian
 
iangle, and are related superficially to the intermediate supraclavicular
 
'rve and deeply to the upper and middle trunks of the brachial plexus.
 
'iperiorly they are continuous with the upper deep cervical lymph
 
ands. They receive their afferent vessels from the following sources:
 
 
 
1. The back of the neck.
 
 
 
2. The axillary lymph glands.
 
 
 
3. The upper part of the pectoral region.
 
 
 
4. Occasionally the lymphatics along the cephalic vein, which
 
ay ascend over the clavicle.
 
 
 
5- The internal mammary lymph glands.
 
 
 
 
 
 
 
 
 
1190
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Their efferent vessels form the subclavian trunk, which, with t
 
jugular trunk, opens into the thoracic, or into the right lymphai
 
duct.
 
 
 
Subclavian or Supraclavicular Triangle. —The subclavian triangle
 
the lower division of the posterior triangle of the neck, and is separate
 
from the upper division or occipital triangle by the inferior belly
 
 
 
 
 
 
 
Fig. 715. —Common Carotid and Subclavian Arteries exposed by Remow
 
of Sterno-mastoid, Omo-hyoid, and Internal Jugular Vein.
 
 
 
the omo-hyoid muscle. Situated above the middle third of the clavicl*
 
it is of small size until the deep cervical fascia, which ensheathes tt
 
inferior belly of the omo-hyoid, has been divided.
 
 
 
Boundaries — Superior .—The inferior belly of the omo-hyoid muscf
 
Inferior .—The middle third of the clavicle. Anterior .—The clavicuk
 
part of the sterno-mastoid muscle. Roof .—The skin; superficial fasci
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1191
 
 
 
 
 
platysma muscle; medial, intermediate, and lateral supraclavicular
 
es; a part of the external jugular vein; and the deep cervical fascia,
 
if.—The scalenus medius and posterior muscles, and the serratus
 
:rior.
 
 
 
rhe extent of the triangle is affected by (T) the height to which
 
inferior belly of the omo-hyoid ascends above the clavicle, and
 
the extent of the clavicular attachments of the sterno-mastoid
 
trapezius muscles. The depth of the triangle is influenced by the
 
tion of the shoulder, being greater when the shoulder is raised
 
carried forwards, and less when it is depressed and carried
 
kwards.
 
 
 
Contents. —The contents are: (1) the greater portion of the third
 
t of the subclavian artery; (2) small portions of the transverse
 
 
 
 
 
 
 
Brachial Plexus
 
Cephalic Vein
 
Musculo-cutaneous Nerve
 
Deltoid
 
 
 
 
 
Trapezius
 
 
 
1 Suprascapular Vessels
 
 
 
\ Transverse Cervical Artery
 
 
 
Inferior Belly of Omo-hyoid
 
 
 
Scalenus Anterior
 
/ Sterno-mastoid
 
 
 
 
 
-Clavicle in section
 
 
 
 
 
Subclavius
 
 
 
 
 
Axillary Artery
 
- Axillary Vein
 
 
 
Pectoralis Major (cut)
 
 
 
 
 
Pec!oralis Minor
 
Lateral Root of Median Nerve
 
 
 
 
 
Medial Cutaneous
 
Nerve of Arm
 
 
 
Axillary Vein
 
 
 
Ulnar Nerve
 
 
 
 
 
Medial Root of Median Nerve
 
Medial Cutaneous Nerve of Forearm
 
 
 
 
 
Fig. 716. —Subclavian and Axillary Regions.
 
 
 
 
 
vical artery and vein; (3) the lower portion of the external jugular
 
in; (4) the nerve-trunks of the brachial plexus; and (5) the nerve
 
the subclavius muscle, the suprascapular nerve, and the nerve
 
serratus anterior
 
 
 
Third Part of the Subclavian Artery. —1 his part of the vessel extends
 
>m the outer border of the scalenus anterior muscle to the outer
 
rder of the first rib, where it becomes the axillaiy artery. Its course
 
downwards and outwards, and for the greater part of its extent it
 
s in the subclavian triangle. Its last inch or so, howevei, passes
 
 
 
hind the clavicle and subclavius muscle.
 
 
 
Relations- — Anterior .—The skin; superficial fascia and platysma;
 
edial, intermediate, and lateral supraclavicular nerves; deep cervical
 
>cia; clavicle and subclavius muscle; transverse cervical vessels;
 
prascapular vessels; nerve to the subclavius muscle; and the termina
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1192
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
portion of the external jugular vein. The last-named vessel cro:
 
in front of the artery close to the sterno-mastoid muscle, and in ■
 
situation is joined by the transverse cervical and suprascapular ve
 
A plexiform arrangement of veins is sometimes met with in from
 
the artery, which may be rendered more complex by a branch ascenc
 
superficial to the clavicle from the cephalic vein. Posterior .—'
 
scalenus medius, the lower nerve-trunk of the brachial plexus in
 
vening. Superior .—The upper and middle nerve-trunks of the brad
 
plexus, the latter being nearest the vessel. Inferior .—The upper s
 
face of the first rib and the subclavian vein, the vein being on a m
 
anterior plane than the artery, and lying behind the clavicle.
 
 
 
It is most important to understand that, though the first rib is spoken o
 
an inferior relation, its surface is so oblique that it is just as much behinc
 
below.
 
 
 
The third part of the subclavian artery does not always give
 
any branch. In very many cases, however, the deep branch of
 
transverse cervical artery arises from it, instead of from the latter arte
 
 
 
which is a branch of the first, p
 
of the subclavian. In these ca
 
the posterior scapular art
 
passes outwards between
 
nerve - trunks of the brad
 
plexus.
 
 
 
The direction of the third p
 
of the artery is indicated b^
 
line drawn from a point on i
 
posterior border of the ster
 
mastoid muscle, about J ir
 
above the clavicle, to the cen
 
of that bone. The artery may
 
compressed as it passes over 1
 
first rib, the guide to it at t
 
point being the centre of i
 
clavicle. In order to tie the si
 
clavian artery in the dead bo<
 
after fully depressing the clavi(
 
feel for the outer edge of the scalenus anterior muscle, and follow
 
to its insertion on the first rib. The structure which lies immediat
 
behind the muscle here is the artery; and great care must be taken i
 
to mistake it for the lower trunk of the brachial plexus.
 
 
 
For the manner in which the collateral circulation is carried
 
after ligation of the third part of the subclavian artery, see p. 441.
 
 
 
The subclavian vein, in the region of the subclavian triangle,
 
situated behind the clavicle, where it lies below and anterior to 1
 
artery. On the upper surface of the first rib it is anterior to the scaler
 
anterior, and it receives the external jugular vein, and in some ca
 
the anterior jugular vein,
 
 
 
 
 
 
 
Fig. 717.— Plan of Branches of
 
Subclavian Artery.
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii 93
 
 
 
 
 
L'he transverse cervical artery lies in the subclavian triangle for
 
Lort distance only, close to where the inferior belly of the omoid passes deep to the sterno-mastoid. It passes outwards behind
 
former muscle into the lower part of the occipital triangle, where
 
ivides into its superficial and deep branches, the former entering
 
trapezius, and the latter passing in front of the levator scapulae,
 
r which it descends along the base of the scapula in front of the
 
nboid muscles.
 
 
 
rhe transverse cervical vein opens into the external jugular vein,
 
•e being a valve at or near its ending.
 
 
 
rhe suprascapular artery is not in the subclavian triangle, but lies
 
ind the clavicle, close to its upper aspect. It will be described in
 
nection with the first part of the subclavian artery (see p. 1243).
 
 
 
The suprascapular vein also lies behind the clavicle, and it opens
 
> the external jugular vein, there being a valve at or near its ending.
 
The external jugular vein will be found described on p. 1176.
 
 
 
Brachial Plexus. —The brachial plexus is situated in the lower part
 
he posterior triangle of the neck, behind the clavicle, and in the
 
>er part of the axilla. Its complex formation is rendered simple
 
arranging it into four stages—namely (1) nerve-roots, (2) nervenks, (3) divisions of nerve-trunks, and (4) nerve-cords.
 
 
 
First Stage .—The nerves which form the plexus are the anterior
 
nary rami of the fifth, sixth, seventh, and eighth cervical, and the
 
ater part of that of the first thoracic. Superiorly the plexus is
 
lforced by a small descending branch from the fourth cervical,
 
ich joins the fifth, and interiorly it is occasionally reinforced by a
 
,nch from the second thoracic, which joins the first. As regards the
 
t thoracic nerve, the part of it which does not join the plexus, and
 
ich is of small size, enters the first intercostal space to become the
 
t intercostal nerve. The nerves, as thej^ emerge at the side of the
 
k, are placed between the scalenus anterior and scalenus medius,
 
which they give branches.
 
 
 
Second Stage .—The fifth and sixth cervical nerves join at the
 
;er border of the scalenus anterior to form the upper trunk ; the
 
r enth cervical remains meanwhile single, and forms the middle
 
nk ; and the eighth cervical and greater part of the first thoracic
 
ite between the scalene muscles to form the lower trunk. There
 
! thus three trunks—upper, middle, and lower.
 
 
 
Third Stage.—A little above the clavicle each of the three trunks
 
^aks up into anterior and posterior divisions.
 
 
 
Fourth Stage.— The anterior divisions of the upper and middle
 
inks unite to form the lateral cord of the plexus; the anterior
 
dsion of the lower trunk, which is of large size, forms the medial
 
rd; and all three posterior divisions (that of the lower trunk being
 
small size) unite to form the posterior cord. There are thus three
 
rds—lateral, medial, and posterior. As a variety, the anterior
 
/ision of the middle trunk may subdivide into two branches, one
 
tering the lateral cord and the other the medial.
 
 
 
 
 
H 94
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Branches of the Plexus above the Clavicle. —The branches are c<
 
veniently divided into two groups—supraclavicular, arising above 1
 
clavicle, and coming from nerve-roots and nerve-trunks; and inf
 
clavicular, arising below the clavicle, and coming from nerve-cords.
 
 
 
Supraclavicular Branches .—These are muscular branches fr<
 
the four cervical nerves to the scalene muscles and longus cervicis.
 
 
 
One root of the phrenic nerve (inconstant) from the front of 1
 
fifth cervical.
 
 
 
The Nerve to the Rhomboids. —This branch arises from the ba
 
of the fifth cervical, close to or along with the highest root of 1
 
 
 
 
 
 
 
Iug. 718. —The Brachial Plexus.
 
 
 
\ ellow=spinal nerves and their branches; blue=trunks; red=lateral cord
 
 
 
purple=medial cord; grey=posterior cord.
 
 
 
neive to serratus anterior, and it takes a backward course throu
 
the scalenus medius.
 
 
 
The Nerve to the Serratus Anterior (Nerve of Bell or Posteri
 
Thoracic Nerve). —This branch arises by three roots from the ba
 
of the fifth, sixth, and seventh cervical nerves. The upper two ro(
 
pierce the scalenus medius muscle below the nerve to the rhomboi(
 
either conjointly or separately, whilst the lowest root passes in fro
 
of the scalenus medius, and joins the trunk formed by the oth(
 
neai the first rib. The nerve then courses behind the brachial plex
 
and the first part of the axillary artery to the axillary surface of t
 
serratus anterior, which it supplies.
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
ii95
 
 
 
 
 
*
 
 
 
he Nerve to the Subclavius. —This small branch arises from the
 
of the upper trunk, its fibres being derived from the fifth cer. It descends in front of the third part of the subclavian artery,
 
passing behind the clavicle, enters the subclavius muscle on
 
leep aspect. This nerve sometimes communicates with the
 
nic nerve.
 
 
 
he Suprascapular Nerve. —This is a large nerve which arises from
 
Dack of the upper trunk, its fibres being derived from the fifth
 
 
 
 
 
 
 
Fig. 719. —Plan of Triangles of Neck.
 
 
 
sixth cervical. It is directed downwards, outwards, and backds beneath the trapezius and inferior belly of the omo-hyoid to
 
upper border of the scapula, on approaching which it meets the
 
rascapular artery. It is distributed to the supraspinatus and
 
ispinatus muscles and shoulder-joint.
 
 
 
[t will be seen that all the branches of the brachial plexus belong
 
er to the anterior or posterior divisions, even if they come off before
 
>e divisions become separate, and that their distribution gives a clue
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1196
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
to the division to which they belong. The nerves to the scale]
 
medius and posterior, as well as that to the rhomboids, the sup
 
scapular, and to serratus anterior, are, from their distribution, clea
 
dorsal or posterior in their origin; while the nerves to the scale]
 
anterior, longus cervicis, and subclavius are equally clearly anteric
 
 
 
Below the clavicle the lateral and medial cords give off all the antei
 
branches, while the posterior come entirely from the posterior cord.
 
 
 
For the infraclavicular branches of the brachial plexus, see p. 4
 
 
 
Anterior Triangle. —This triangle is situated in front of the ster:
 
mastoid muscle, and its base is directed upwards.
 
 
 
Boundaries — Anterior. —The middle line of the neck—that is
 
say, a line extending from the chin to the upper border of the mai
 
brium sterni. Posterior. —The anterior border of the sterno-mast
 
muscle. Superior. —The lower border of the mandible and a 1
 
drawn from the angle of that bone to the mastoid process. 1
 
triangle is covered by the skin, superficial cervical fascia, platysr
 
and deep cervical fascia. Superficial to the deep fascia there
 
the following structures: the anterior jugular vein, the ramificati<
 
of the anterior cutaneous nerve of neck, and the cervical branch of 1
 
facial nerve.
 
 
 
The anterior triangle is subdivided into three triangles by i
 
superior belly of the omo-hyoid muscle inferiorly, and posterior be
 
of the digastric muscle superiorly. The subdivisions from bel
 
upwards are called muscular, carotid, and submandibular.
 
 
 
The muscular triangle is bounded anteriorly by the middle line
 
the neck; posteriorly by the anterior border of the sterno-mastoid; a
 
superiorly by the superior belly of the omo-hyoid.
 
 
 
The carotid triangle is bounded inferiorly by the superior be
 
of the omo-hyoid; superiorly by the posterior belly of the digast
 
and stylo-hyoid; and posteriorly by the anterior border of the sten
 
mastoid.
 
 
 
The submandibular triangle (submaxillary triangle) is bound
 
 
 
postero-inferiorly by the lower part of the posterior belly of the digasti
 
the stylo-hyoid, and by the body of the hyoid bone: antero-inferio
 
by the mid-line of the neck; and superiorly by one half of the be
 
of the mandible, and a line drawn from the angle of that bone to t
 
sterno-mastoid muscle.
 
 
 
Contents of the Triangles—Muscular Triangle (Fig. 719).—The ai
 
of this triangle is occupied by the sterno-hyoid and sterno-thyn
 
muscles; hence the name muscular triangle. Under cover of th<
 
muscles there are the carotid sheath with its contents, the late
 
lobe of the thyroid gland, the trachea, and the larynx. The oesophag
 
lies behind the trachea, with a slight inclination towards the 1
 
side at the root of the neck, and the recurrent laryngeal nerve 1
 
in the groove between the trachea and the oesophagus. The infer
 
thyroid artery has a tortuous course inwards behind the lower p;
 
of the carotid sheath, and the trunk of the sympathetic descer
 
behind both.
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1197
 
 
 
 
 
arotid Triangle. —This triangle contains the upper part of the
 
non carotid, and the beginnings of the external and internal
 
:id arteries, all of which are overlapped by the anterior border
 
le sterno-mastoid, when the connective tissue which ensheathes
 
muscle is undisturbed. The common carotid and internal carotid
 
ies, together with the vagus nerve, are contained within the
 
tid sheath, and the descendens hypoglossi lies in front of the
 
th, or within it, being situated in either case in front of the common
 
tid artery. The sterno-mastoid artery and the superior thyroid
 
cross the sheath near the bifurcation of the common carotid
 
 
 
 
 
.Transverse Facial Artery
 
 
 
 
 
Parotid Duct -Buccinator Muscle
 
Facial Artery -Submental Artery
 
 
 
 
 
Lingual Artery —
 
Sup. Lar. Art. and Nerve
 
Thyro-hyoid Muscle _.
 
Superior Thyroid Artery
 
 
 
 
 
 
 
Inf. Belly of Omo-hyoid-,
 
 
 
Subclavian Artery
 
(third part)
 
 
 
 
 
, Superficial Temporal Artery
 
 
 
HPI"' Maxillary Artery
 
 
 
Posterior Auriculav
 
 
 
r Artery
 
 
 
/r _ Occipital Artery
 
 
 
>itW
 
 
 
,,,, . .-. - JIlifL. _Stylo-hyoid Muscle
 
 
 
WyMSm---- Post - Bel, y of Di s astric
 
 
 
!£- _Hypoglossal Nerve
 
 
 
-Descendens Hypoglossi
 
 
 
Jj_External Carotid Artery
 
 
 
 
 
-Sterno-mastoid
 
 
 
Trapezius
 
 
 
_Transverse Cervical Artery
 
 
 
_. Suprascapular
 
f\ Artery
 
 
 
 
 
^iwii iin^wiu !ii wu M1 1 \w ' An '
 
 
 
Fig. 720.—The Left Side of the Head and Neck.
 
The platysma myoides has been removed.
 
 
 
 
 
*ry, and the carotid body lies behind the vessel about the same
 
d. The deep cervical lymph glands lie just lateral to the course
 
he internal jugular vein. The origins of the superior thyroid, lingual,
 
ial, and occipital arteries are contained in this triangle, and the
 
ending pharyngeal branch of the external carotid lies deeply between
 
t vessel and the internal carotid. The internal jugular vein in this
 
ingle receives the common facial, lingual, and superior thyroid veins,
 
e hypoglossal nerve lies along the lower border of the posterioi
 
ly of the digastric muscle, and it here gives off, fiom behind
 
wards, the descendens hypoglossi and the nerves to thyio-hyoid
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
1198
 
 
 
 
 
and genio-hyoid, the former passing downwards in front of, or witl
 
the carotid sheath, and the latter passing forwards and downwards
 
an acute angle with the parent trunk. The internal branch of
 
superior laryngeal nerve lies deeply behind the bloodvessels, and
 
external laryngeal branch of that nerve descends parallel and deep
 
the superior thyroid artery, and passes deep to the upper end of
 
posterior border of the sterno-thyroid muscle. The vagus nerve
 
within the carotid sheath, and the sympathetic trunk is behind
 
The accessory nerve lies deeply, its course being downwards and ba
 
wards beneath the sterno-mastoid, the deep portion of which usual!
 
pierces about an inch below the angle of the mandible.
 
 
 
Digastric Triangle.—This triangle is divided into two parts, antei
 
and posterior, by the stylo-mandibular ligament. The anterior p
 
contains the superficial part of the submandibular gland, the antei
 
facial vein being superficial to it, and the facial artery being embed(
 
in its upper and back part. In this triangle the facial artery gives
 
its ascending palatine, tonsillar, glandular, and submental brand
 
The muscles in the floor of the anterior part of the triangle are
 
mylo-hyoid and a part of the hyo-glossus. The superficial part of
 
submandibular gland is superficial to the mylo-hyoid muscle, a
 
conceals the mylo-hyoid nerve and submental artery, which are
 
direct contact with the muscle. The hypoglossal nerve lies upon t]
 
part of the hyo-glossus muscle which appears in the anterior part
 
the triangle, but it soon disappears beneath the posterior free bon
 
of the mylo-hyoid muscle. It is important to notice that it lies para
 
to and just above the greater horn of the hyoid bone, which forms
 
important structure in the floor of the triangle, and shows a little
 
the insertion of the thyro-hyoid muscle below it.
 
 
 
The anterior jugular vein and the anterior cutaneous nerve of 1
 
neck have been already described (see pp. /1173 and 1187). 1
 
cervical branch of the facial nerve will be found described on p. 12
 
 
 
Submandibular Lymph Glands (Submaxillary Lymphatic Glands)
 
These glands lie upon the superficial surface of the submandibu
 
salivary gland, under cover of the deep cervical fascia. They forn
 
chain beneath the corresponding half of the base of the mandit
 
which extends from near the angle of the bone to near the origin of 1
 
anterior belly of the digastric muscle. The central gland of the chi
 
is closely related to the facial artery as that vessel is about to asce
 
 
 
 
 
over the base of the mandible,
 
from the following sources:
 
 
 
1. The front of the scalp.
 
 
 
2. The side of the nose.
 
 
 
3. A few from the lower eyelid.
 
 
 
4. The lower part of the cheek.
 
 
 
5. Half of the upper lip.
 
 
 
6. The lateral part of the lower lip
 
 
 
7. The anterior third of the lat
 
eral border of the tongue.
 
 
 
 
 
They receive their afferent vess
 
 
 
 
 
8.
 
 
 
 
 
9
 
10.
 
 
 
 
 
11.
 
 
 
12.
 
 
 
 
 
The subjacent portion of
 
floor of the mouth.
 
 
 
Half of the upper gum.
 
 
 
The lateral part of the lo^
 
gum.
 
 
 
The facial lymph glands.
 
 
 
The submandibular and si
 
lingual salivary glands.
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1199
 
 
 
 
 
Their efferent vessels pass to the upper deep cervical lymph glands,
 
ch are on a level with the upper border of the thyroid cartilage of
 
larynx.
 
 
 
The submental lymph glands lie beneath the chin, and are two or
 
;e in number. They receive their afferent lymphatics from the tip
 
he tongue, the front of the floor of the mouth, and the inner part
 
the lower lip; and their efferent lymphatics pass to the subidibular lymphatic glands. It must be borne in mind that these
 
Lphatic vessels, like those elsewhere in the body, frequently comnicate across the middle line.
 
 
 
The prelaryngeal lymph glands, when present, are situated in front
 
the crico-thyroid ligament, and are one or two in number. They
 
give their afferent lymphatics from the interior of the larynx,
 
dw the rima glottidis, and from the adjacent part of the thyroid
 
nd. Their efferent lymphatics pass to the inferior deep cervical
 
lph glands. The upper part of the larynx drains into the superior
 
p cervical lymph glands along a course accompanying that of the
 
>erior laryngeal vessels.
 
 
 
The para- and pretracheal lymph glands lie in front and at the sides
 
the trachea, from which, as well as from the adjacent part of the
 
a*oid gland, they receive their afferent lymphatics. Their efferent
 
iphatics pass to the inferior deep cervical lymph glands.
 
Occasionally a few lymph glands are met with along the course
 
the anterior jugular vein.
 
 
 
Deep Cervical Lymph Glands. —These glands lie deep to the sternostoid muscle, and are very numerous. They are arranged in two
 
tups, superior and inferior.
 
 
 
The superior deep cervical lymph glands lie along the internal
 
;ular vein above the level of the upper border of the thyroid cartilage,
 
ey receive their afferent lymphatics from the cranial cavity, the
 
ernal maxillary glands, some of the parotid and submandibular
 
nph glands, the root of the tongue, the upper part of the thyroid
 
nd, the upper part of the larynx, and the lower part of the pharynx,
 
eir efferent lymphatics pass to the inferior deep cervical lymph
 
nds. One large gland of this group is very constant, and lies close
 
the angle of the mandible. It drains the dorsum and sides of the
 
igue, but not the tip as a rule.
 
 
 
The inferior deep cervical lymph glands lie along the lower part of
 
j internal jugular vein, and extend outwards and backwards deep to
 
 
 
1 sterno-mastoid as far as its posterior border. These lymph glands
 
J continuous inferiorly with the deep cervical lymph glands lying
 
the subclavian triangle, and, through these, with the axillary glands,
 
ey receive their afferent lymphatics from the superior deep cervical
 
nph glands, the upper superficial cervical lymph glands, the lower
 
rt of the thyroid gland and larynx, and the cervical portions of the
 
ichea and oesophagus. Their efferent lymphatics unite to form a
 
^gle vessel, called the jugular trunk, which opens on the left side into
 
 
 
2 thoracic duct, and on the right side into the right lymphatic duct.
 
 
 
 
 
1200
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Infrahyoid Muscles. —These are the omo-hyoid, sterno-hyoi
 
sterno-thyroid, and thyro-hyoid.
 
 
 
Omo-hyoid. —This muscle consists of two bellies, superior (anteric
 
and inferior (posterior), and an intermediate tendon. Origin .—I
 
means of the inferior belly from (i) the upper border of the scapu
 
close to the inner side of the suprascapular notch, and (2) the supr
 
scapular ligament, which bridges over the suprascapular notch.
 
 
 
Insertion .—By means of the superior belly into the outer third
 
the lower border of the body of the hyoid bone immediately later
 
to the insertion of the sterno-hyoid muscle.
 
 
 
Nerve-supply .—The superior belly is supplied by the ramus desce
 
dens hypoglossi, and the posterior belly derives its branches from t]
 
ansa hypoglossi.
 
 
 
 
 
 
 
Greater Horn
 
 
 
 
 
Lesser Horn
 
 
 
 
 
Omo-hyoid (Sup. Belly)
 
 
 
 
 
1
 
 
 
 
 
Fig. 721.—The Hyoid Bone, showing its Muscular Attachments.
 
 
 
The inferior belly is contained in the posterior triangle of the nec
 
and separates the occipital from the subclavian triangle. Its course
 
forwards and slightly upwards, and it passes deep to the stern
 
mastoid muscle, where its fibres terminate in the intermediate tendo
 
It is ensheathed by a deep process of the deep cervical fascia as th
 
fascia crosses the posterior triangle, and this process is attached to t
 
back of the inner end of the clavicle and the first rib, which explai
 
the almost horizontal position occupied by the inferior belly.
 
 
 
The superior belly proceeds from the intermediate tendon, ai
 
passes upwards and slightly inwards to the body of the hyoid bor
 
As it emerges from beneath the anterior border of the sterno-mastc
 
muscle the superior belly crosses the carotid sheath on a level wi
 
the narrow anterior part of the cricoid cartilage, and in the anteri
 
triangle of the neck it forms the separation between the muscular ai
 
carotid triangles.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1201
 
 
 
 
 
rno-hyoid — Origin. —(i) The posterior surface of the manubrium
 
at its upper and outer part; (2) the posterior sterno-clavicular
 
jnt; and, sometimes, (3) the posterior surface of the clavicle at
 
Ler end.
 
 
 
sertion. —The inner two-thirds of the lower border of the body of
 
roid bone, extending from the middle line to the insertion of the
 
or belly of the omo-hyoid.
 
irve-supply. —The ansa hypoglossi.
 
 
 
ie muscle is flat and ribbon-like, and rests upon the sternod and thyro-hyoid.
 
 
 
irno-thyroid — Origin. —(r) The posterior surface of the manusterni at its upper and outer part below the origin of the sterno; and (2) the posterior surface of the first costal cartilage.
 
sertion. —The oblique line on the -outer surface of the lamina of
 
Lyroid cartilage.
 
 
 
irve-supply. —The ansa hypoglossi. The nerves enter this and
 
st muscle quite at the lower part of the neck,
 
ie muscle is broader, but shorter, than the sterno-hyoid underwhich it lies. Within the thorax the right muscle lies in front
 
3 innominate artery, and the left in front of the left common
 
d artery and left innominate vein. In the neck each muscle
 
upon the carotid sheath and the corresponding right or left lobe
 
5 thyroid gland.
 
 
 
ie sterno-hyoid muscles as they leave the thorax are separated
 
1 interval, in which situation the sterno-thyroid muscles lie in
 
contact. As the muscles ascend the sterno-hyoids converge, but
 
erno-thyroids diverge.
 
 
 
tyro-hyoid — Origin. —The oblique line on the outer surface of
 
tmina of the thyroid cartilage.
 
 
 
\sertion. —(1) The outer half of the lower border of the body of
 
yoid bone; and (2) the basal half of the greater horn of that
 
 
 
erve-supply. —A special branch of the hypoglossal, though originlerived from the first and second cervical nerves. The nerve
 
3 the surface of the muscle close to its posterior border,
 
ie muscle is quadrilateral. Its superficial surface supports the
 
ior belly of the omo-hyoid and the sterno-hyoid muscles, and its
 
surface is related to the lamina of the thyroid cartilage, the
 
-hyoid membrane, the internal branch of the superior laryngeal
 
;, and the superior laryngeal artery.
 
 
 
e nerves which supply the infrahyoid group of muscles are derived from
 
'st, second, and third cervicals through the hypoglossal and ansa hypo
 
ction of the Infrahyoid Muscles — Omo-hyoid. —(1) lo depress
 
yoid bone; and (2) to render tense the deep cervical fascia in the
 
part of the neck.
 
 
 
erno-hyoid. —To depress the hyoid bone,
 
erno-thyroid. —To depress the thyroid cartilage.
 
 
 
 
 
76
 
 
 
 
 
 
 
 
 
 
 
1202
 
 
 
 
 
A MANUAL OF ANATOMY
 
 
 
 
 
Thyro-hyoid.— (i) To depress the hyoid bone; and (2) to ele
 
the thyroid cartilage, as in the production of high notes, or in
 
glutition.
 
 
 
Structures in the Median Line of the Neck. —The median line of
 
neck is divisible into two regions, suprahyoid and infrahyoid.
 
 
 
Suprahyoid Region. —The innermost fibres of the two platy
 
muscles decussate at the median line for a short distance below
 
chin. On either side of the median line, under cover of the platy<
 
is the anterior belly of the digastric muscle. The anterior bellic
 
 
 
 
 
Posterior Belly of Digastric—
 
and Stylo-hyoid
 
Hyo-glossus Muscle and
 
Hypoglossal Nerve
 
 
 
 
 
Ster. Head of St.-mas. -Crico-thyroid Muscle -
 
 
 
Cricoid Cartilage
 
Lat. Lobe of Thyroid Gland
 
 
 
Trapezius
 
 
 
Clavicular Head of
 
Stemo-mastoid
 
Brachial Plexus
 
 
 
 
 
Subclavian Artery
 
(third part)
 
 
 
Clavicle
 
 
 
 
 
 
 
Anterior 'Belly of Diga:
 
jf Mylo-hyoid
 
 
 
 
 
Body of Hyoid Bone
 
_ Superior Belly of Omo
 
' - Stemo-hyoid
 
 
 
 
 
Thyro-hyoid
 
 
 
 
 
Thyroid Cartilage
 
Sterno-thyroid
 
Superior Belly of Omo
 
Crico-thyroid Ligamen
 
 
 
 
 
Stemo-hyoid
 
 
 
 
 
Isthmus of Thyr
 
Gland
 
 
 
 
 
■s Inferior Thyroid
 
y of Veins
 
 
 
Cla. Head of St.-i
 
 
 
 
 
,T\T
 
 
 
-\r Sterno-thyroid
 
 
 
 
 
Sternal Head of Sternomastoid
 
 
 
 
 
Sterno-thyroid
 
 
 
 
 
Sterno-hyoid
 
 
 
 
 
Fig. 722.—Dissection of the Front of the Neck.
 
 
 
The area bounded on either side by the anterior belly of the digastric a
 
below by the body of the hyoid bone is the submental triangle.
 
 
 
 
 
opposite sides are near each other at the chin, but as they des<
 
with an inclination outwards they diverge from each other, and 1
 
between them a triangular interval sometimes called the subm<
 
triangle. The base of this triangle is formed by the body of the h
 
bone, and each lateral boundary is constructed by the anterior 1
 
of the digastric, the apex being placed at the chin. The area oi
 
triangle is occupied by the anterior portions of the mylo-hyoid mus
 
which meet at the median line in a tendinous raphe, and super!
 
to these muscles there are the submental lymph glands.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE HEAD AND NECK
 
 
 
 
 
1203
 
 
 
 
 
Epiglottis
 
 
 
 
 
Greater Horn of Hyoid Bone~
 
 
 
Lesser Horn of Hyoid Bone Body of