738
UNIT 4
Maintenance of the Body
19
Table 19.10
Veins of the Head and Neck
Tree pairs of veins collect most of the blood draining from the
head and neck
(Figure 19.27a)
:
Te external jugular veins, which empty into the subclavians
Te internal jugular veins
Te vertebral veins, which drain into the brachiocephalic
vein
Although most extracranial veins have the same names as the
extracranial arteries, their courses and interconnections differ
substantially.
Most veins of the brain drain into the
dural venous sinuses
,
an interconnected series of enlarged chambers located be-
tween the dura mater layers. Te
superior
and
inferior sagittal
sinuses
are in the falx cerebri, which dips down between the
cerebral hemispheres. Te inferior sagittal sinus drains into the
straight sinus
posteriorly (Figure 19.27a and c). Te superior
sagittal and straight sinuses then empty into the
transverse si-
nuses
, which run in shallow grooves on the internal surface
of the occipital bone. Tese drain into the S-shaped
sigmoid
sinuses
, which become the
internal jugular veins
as they leave
the skull through the jugular foramen. Te
cavernous sinuses
,
which flank the sphenoid body, receive venous blood from the
ophthalmic veins
of the orbits and the facial veins, which drain
the nose and upper lip area. Te internal carotid artery and cra-
nial nerves III, IV, VI, and part of V, all run
through
the cavern-
ous sinus on their way to the orbit and face.
Description and Area Drained
External jugular veins.
Te right and le± external jugu-
lar veins drain superficial scalp and face structures served
by the external carotid arteries. However, their tributaries
anastomose frequently, and some of the superficial drain-
age from these regions enters the internal jugular veins
as well. As the external jugular veins descend through
the lateral neck, they pass obliquely over the sternoclei-
domastoid muscles and then empty into the subclavian
veins.
Vertebral veins.
Unlike the vertebral arteries, the ver-
tebral veins do not serve much of the brain. Instead they
drain the cervical vertebrae, the spinal cord, and some
small neck muscles. ²hey run inferiorly through the
transverse foramina of the cervical vertebrae and join the
brachiocephalic veins at the root of the neck.
Internal jugular veins.
²he paired internal jugular
veins, which receive the bulk of blood draining from
the brain, are the largest of the paired veins draining the
head and neck. Tey arise from the dural venous sinuses,
exit the skull via the
jugular foramina
, and then descend
through the neck alongside the internal carotid arteries.
As they move inferiorly, they receive blood from some
of the deep veins of the face and neck—branches of the
facial
and
superficial temporal veins
(Figure 19.27b). At
the base of the neck, each internal jugular vein joins the
subclavian vein on its own side to form a brachiocephalic
vein. As already noted, the two brachiocephalic veins
unite to form the
superior vena cava
.
(a) Schematic flowchart
Superior sagittal sinus
Inferior
sagittal sinus
Superficial
temporal vein
Ophthalmic
vein
Facial vein
Cavernous
sinus
Straight
sinus
Transverse
sinus
Occipital
vein
Posterior auricular
vein
Sigmoid sinus
External jugular
vein
Vertebral vein
Subclavian vein
Superior vena cava
Brachiocephalic veins
Middle thyroid vein
Superior thyroid vein
Internal jugular vein
Figure 19.27
Venous drainage of the head, neck, and brain.
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