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Anatomy lab#8
Lec. Date: 27-3-2011
The carotid triangle
Borders:
Posteriorly :
By sternocleidomastoid muscle
Anteriorly :
By superior belly of omohyoid
Superiorly :
By 2 muscles : posterior belly of digastric muscle and
stylohyoid muscle
Contents:
1-carotid sheath
it’s a tubular extension of deep cervical fascia extending
from base of the skull to the root of neck at arch of aorta.
contents : -aortic arch
-common carotid artery.
-external carotid artery.
- internal carotid artery.
- internal jugular vein.
- vagus nerve
- sympathetic trunk
2-Common carotid artery
It starts behind the sternocalvicular joint, ascend within
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carotid sheath, ends at superior border of thyroid cartilage
by dividing into : internal carotid artery and external
carotid artery.
3-internal carotid artery
It’s direct continuation of common carotid artery, starts at
upper border of thyroid cartilage, ascend inside carotid
sheath, ends at base of skull by entering through carotid
canal then passes through foramen lacerum then
cavernous sinus then cerebral.. So it is divided into 4
parts:
1- cervical ( no branches)
2- petrous
3- cavernous
4- cerebral which divides into: anterior cerebral artery and
middle cerebral artery.
** note that posterior cerebral artery is branch from
basilar artery which is a branch from vertebral artery.
4- external carotid artery
It starts at upper border of thyroid cartilage, ascends
within carotid sheath, ends behind neck of mandible
within parotid gland by dividing into superficial temporal
artery and maxillary artery.
** it divides into 8 branches :
5 below the bridge(posterior belly of digastric) :
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- superior thyroid artery.
-ascending pharyngeal artery.
-lingual artery.
-facial artery.
-occipital artery.
3 above the bridge :
-posterior auricular artery.
-superficial temporal artery.
-maxillary artery.
5-internal jugular vein
Starts within jugular foramen as a continuation of sigmoid
sinus, descend within carotid sheath, ends at root of the
neck by uniting with subclavian vein to form the
brachiocephalic vein.
**it is valveless except at inferior end (inferior bulb) it
has bicuspid valve.
6-vagus nerve
It is between internal jugular vein and common carotid
artery and internal carotid artery, it passes through jugular
foramen between arteries and veins, continues down all
through carotid sheath.
** it gives left recurrent laryngeal nerve which forms
below aortic arch and right recurrent laryngeal nerve
which forms below and at level of right subclavian artery
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and return back.. Both of them ascend to pass between
trachea and esophagus.
** vagus nerve is a parasympathetic nerve.
7- hypoglossal nerve
It passes through hypoglossal canal, entering the
submandibular triangle then passing below 2 muscles (
posterior belly of digastric and stylohyoid) then entering
the carotid triangle .
** it carries C1 nerve.
** sandwiched between 2 muscles ( mylohyoid and
hypoglossal).
** it goes to the tongue.
** it gives 2 branches of C1 ( superior root of ansa and
another root which will supply 2 muscles( geniohyoid and
stylohyoid))
8- ansa cervicalis
**Ansa means loop.
It is loop of nerves originated from cervical plexus
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( c1-c3).
It has:
Superior root : C1 nerve carried through CN XII after
leaving the skull.
Inferior root : from C2, C3 nerves of cervical plexus .
** they unit anterior to internal jugular vein.
** it supplies all muscles in the anterior triangle.
9- sympathetic trunk
It is a beaded trunk (beads= ganglions) where nerves synapase
within them… found in thoracolumber region.
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Done by : Shahad Almashta
Good luck all 