726
UNIT 4
Maintenance of the Body
19
Table 19.5
Arteries of the Head and Neck
Four paired arteries supply the head and neck. Tese are the com-
mon carotid arteries, plus three branches from each subclavian
artery: the vertebral arteries, the thyrocervical trunks, and the
costocervical trunks
(Figure 19.22b)
. Of these, the common ca-
rotid arteries have the broadest distribution (Figure 19.22a).
Each common carotid divides into two major branches (the
internal and external carotid arteries). At the division point,
each internal carotid artery has a slight dilation, the
carotid si-
nus
, that contains baroreceptors that assist in reflex blood pres-
sure control. Te
carotid bodies
, chemoreceptors involved in
controlling respiratory rate, are located close by. Pressing on the
neck in the area of the carotid sinuses can cause unconscious-
ness (
carot
5
stupor) because the pressure created mimics high
blood pressure, eliciting vasodilation, which interferes with
blood delivery to the brain.
Description and Distribution
Common carotid arteries.
Te origins of these two arteries
differ: Te right common carotid artery arises from the bra-
chiocephalic trunk; the le± is the second branch of the aortic
arch. Te common carotid arteries ascend through the lateral
neck, and at the superior border of the larynx (the level of the
“Adam’s apple”), each divides into its two major branches, the
external
and
internal carotid arteries
.
Te
external carotid arteries
supply most tissues of the head
except for the brain and orbit. As each artery runs superiorly, it
sends branches to the thyroid gland and larynx
(superior thy-
roid artery)
, the tongue
(lingual artery)
, the skin and mus-
cles of the anterior face
(facial artery)
, and the posterior scalp
(occipital artery)
. Each external carotid artery terminates by
splitting into a
superficial temporal artery
, which supplies the
parotid salivary gland and most of the scalp, and a
maxillary
artery
, which supplies the upper and lower jaws and chewing
muscles, the teeth, and the nasal cavity. A clinically important
branch of the maxillary artery is the
middle meningeal artery
(not illustrated). It enters the skull through the foramen spino-
sum and supplies the inner surface of the parietal bone, squa-
mous part of the temporal bone, and the underlying dura mater.
Te larger
internal carotid arteries
supply the orbits and
more than 80% of the cerebrum. Tey assume a deep course
and enter the skull through the carotid canals of the tempo-
ral bones. Once inside the cranium, each artery gives off one
main branch, the ophthalmic artery, and then divides into the
anterior and middle cerebral arteries. Te
ophthalmic arter-
ies
(of-thal
9
mik) supply the eyes, orbits, forehead, and nose.
Each
anterior cerebral artery
supplies the medial surface of the
frontal and parietal lobes of the cerebral hemisphere on its side
and also anastomoses with its partner on the opposite side via a
short arterial shunt called the
anterior communicating artery
(Figure 19.22d). Te
middle cerebral arteries
run in the lateral
sulci of their respective cerebral hemispheres and supply the
lateral parts of the temporal, parietal, and frontal lobes.
Vertebral arteries.
Te vertebral arteries spring from the subcla-
vian arteries at the root of the neck and ascend through foramina
in the transverse processes of the cervical vertebrae to enter the
skull through the foramen magnum. En route, they send branches
Brachiocephalic trunk
Aortic arch
(a) Schematic flowchart
Cerebral arterial circle
R. and L. anterior
cerebral arteries
Anterior
communicating
artery
R. and L.
posterior
communicating
arteries
Basilar
artery
R. and L.
common
carotid
arteries
R. and L.
subclavian
arteries
Superior
thyroid
artery
Lingual
artery
Facial
artery
Occipital
artery
Maxillary
artery
Superficial
temporal
artery
Ophthalmic
artery
R. middle
cerebral
artery
R. posterior
cerebral
artery
R. and L.
vertebral
arteries
R. and L.
internal
carotid
arteries
R. and L.
external
carotid
arteries
Figure 19.22
Arteries of the head, neck, and brain.
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