hi let's talk about the common carotid artery in its branches in this video we'll discuss the major
branches of the common internal and external carotid arteries as well as some of the major
elements of cerebral and cerebellar circulation so the common carotid artery on the right side
arises from the brachiocephalic trunk and on the left side arises as a direct branch of the arch
of the aorta it ascends the neck bound within a condensation of the deep cervical fascia called
the carotid sheath and within that carotid sheath we have the common carotid artery as well as the
internal jugular vein as well as what we can't see here cranial nerve 10 the vagus nerve and
sometimes bound within the sheath is going to be ansa cervicalis from the cervical plexus now the
common carotid artery will bifurcate into the external and internal carotid this bifurcation
can be quite variable the external carotid artery is more anterior the internal carotid artery is
more posterior that external carotid artery is going to supply the neck the face and the scalp
with blood whereas the internal carotid artery has no branches in the neck it ascends up through the
carotid canal of the temporal bone to service the contents of the cranial cavity and it will also
serve the orbit and a portion of the brow from the orbit so here is the external carotid artery
so in the Kennebec image here this is a posterior view of the vertebral column has been segmented
interflow to doubt of the way and we can see that bifurcation of the common carotid into the
external and the internal carotid you have a nice carotid sinus here we don't have a carotid body
to see at this point but those are the Barrow in chemoreceptors respectively for blood flow to the
brain we can see a massive amount of ramification of the external carotid here going every which way
without precisely seeing the targets many of these would be very difficult to identify on their own
so let's turn our attention to the illustration and discuss these branches so first of all this
is a very stylistic illustration this muscle here the sternocleidomastoid would overlie the
the carotid sheath and its contents but here it's Illustrated is behind it so we can see here's the
bifurcation of common carotid here's external carotid here and its first major branch is the
superior thyroid artery that superior thyroid artery is going to supply the thyroid with blood
as well as the the superior portion of the larynx with blood the next branch is the lingual artery
going out into the sublingual space to supply the tongue in surrounding structures with blood
and then a very close branch oftentimes sharing a common trunk with a lingual artery we have
the facial artery that facial artery tends to jump into the face right about here at the pre
masseteric notch and it's going to supply the the face with blood we also have a sending pharyngeal
the ascending pharyngeal supplies the pharynx with blood in particular the middle and inferior
pharyngeal constrictors in stylopharyngeus then we have another posterior lis oriented branch
here the occipital artery the occipital artery is going to supply the posterior aspect of the
scalp with blood it also sends some branches to SCM sternocleidomastoid and can supply parts of
the posterior most suprahyoid muscles with blood there's also a posterior auricular artery that
posterior auricular artery is going to serve the auricle with blood at least the posterior aspect
of it and serve portions of the posterior scalp just behind the auricle of the ear with blood and
then we have the two terminal branches of the external carotid there's the maxillary artery
the maxillary artery serves the deep face with blood so that's running through the m4 temporal
fossa and the superficial temporal artery the superficial temporal artery serves the lion's
share of the scalp with blood it can also send an accessory facial artery to supply the face with
blood as well next we have the internal carotid artery that internal carotid artery does nothing
in the neck it ascends straight up to the basic cranium where it's going to enter the cranium
through the carotid canal of the temporal bone so it's going to jog for a little while it will
pop up on either side of the sella turcica and its first branch moving anteriorly is the ophthalmic
artery that ophthalmic artery is going to supply the orbit in the eye and the forehead with blood
that's running through the optic canal of the sphenoid bone and then the remainder of the
internal carotid artery is going to bifurcate into two major branches there's an anterior cerebral
artery and a middle cerebral artery to supply the anterior portions in the middle portions of
the cerebrum with blood now we can see probably best here that between the anterior cerebral
arteries there can be an anterior communicating artery as we can see the the branch here so this
is a branch that when present is an open and a stenosis between the internal carotid arteries
on the contralateral sides this is a tremendous opportunity to share the supply of blood to the
the brain coming off of the anterior off of the internal carotid artery sometimes is a posterior
communicating branch we can see that going this way or the posterior communicating artery it it
may be present it may not be present it's not guaranteed to be bilaterally present if it's on
one side it may not be on the other and if it is present it is going to anastomosis with the
posterior cerebral artery which is the terminal branch of the vertebral arteries so as we look
down here we can see that the vertebral arteries and you may remember these as arising from the
first part of the subclavian arteries they are traveling through the transverse foramina of
cervical vertebra 6 through 1 and then they come through foramen magnum when they come
through foramen magnum they're going to give off very cutely named Hika which stands for posterior
inferior cerebellar artery to supply the posterior aspect of the cerebellum with blood and from pika
we have posterior spinal arteries one on either side and as the vertebral arteries continue to
ascend they're going to give off branches that coalesce into an anterior spinal artery so just
one anteriorly and then they continue to ascend and they're going to come together to coalesce
into the basilar artery from the basilar artery will have eicha which is the anterior inferior
cerebellar arteries coming off on either side to supply the cerebellum with blood and then
the basal er continues it will branch into the superior cerebellar arteries and then the
posterior cerebral arteries and a very important classical anatomical relationship between these
two arteries will run cranial nerve three the oculomotor nerve so if there is an issue with
an aneurysm here that can impinge on cranial nerve three leading to issues of movements of
the eyes so here is a cadaveric view of this in totality we refer to it as the cerebral arterial
Circle of Willis when it's completely intact here only about 20% of individuals contain a an intact
meaning a 360 degree circle of Willis so here we see the internal carotid arteries there are the
middle cerebral arteries the anterior cerebral arteries we can see a an anterior communicating
artery there and then coming back posteriorly those are the posterior communicating branches
that's impressive that it's they're happy about that ascending up here's the vertebral arteries
and we notice that the right one is larger the left one there's pica on one side pica on the
other I'm not seeing that the posterior spinal is there arising posterior to the spine we can
see the anterior spinal there and then we have the basilar artery ascending there's aikka coming off
of the basilar artery and as the basilar artery continues we have the posterior cerebellar and
then the posterior cerebral artery and if you look close between the two here we can see the third
cranial nerve oculomotor so that is the cerebral arterial Circle of Willis it is an impressive bit
of arterial plumbing we have that leads us to the assessment question which is which branch of the
internal carotid artery if present would confer significant collateral blood flow to areas of
the cerebrum would it be the anterior cerebral artery the basilar artery the middle cerebral
artery the ophthalmic artery or the posterior communicating artery well the basilar artery
isn't of up sorry anterior cerebral artery that's a typical branch of the internal carotid artery
the basilar artery is a typical coalescence of the vertebral arteries middle cerebral artery
again another typical branch of internal carotid ophthalmic another typical branch but this is
serving the eye and the orbit the the only good answer here is the posterior communicating artery
because this is going to connect blood flow from the internal carotid artery to blood flow from
the vertebral artery so two very separate sources of blood one from internal carotid the other from
vertebral which is coming from the subclavian artery thank you very much for your time