hi everyone let's talk about the carotid sheath in this video we'll discuss the carotid sheath
its contents and its associations with other structures in the neck so the carotid sheath
is a combination of condensations of various deep cervical investing fascia so in the in
the cross section of the neck here we can see this represents the outermost boundary of the
carotid sheath and it's going to invest in around the neurovasculature and it tends to be thicker
surrounding the arterial aspects of the sheath and a little thinner about the the venous aspects
of the sheath to allow for blood flow in the veins here laterally outline the contents of
the carotid sheath see it descending down in the neck and crossing the carotid sheath here is the
superior belly of the omohyoid muscle reflected away is the sternocleidomastoid muscle but as
we can see it would be attaching down here so the carotid sheath would be deep to both the
SEM as well as the omohyoid we can see other infrahyoid muscles of the neck here so the
carotid chief is going to be lateral to those muscles it's also going to be if we look over
here on the the cross section there's the trachea and esophagus and then there's the the thyroid
gland so we'll be lateral to those structures as well we can let me erase some of this so that we
can see a couple of additional structures in here as well so on on this particular drawing
we can see the cervical sympathetic trunk on that side and on that side and we can see that
the carotid sheath is anterolateral to that and we can't see it on this illustration but let me
just draw it in right there the the limbs of the ancestor of a callous or sometimes
embedded in the sheath and sometimes they're a little anterior lateral on this photograph
we can see there's the anterior limb of answer descending and then there's the posterior limb
of ansa cervicalis some sources will say that the the ansa cervicalis is a content of the
sheath some will say that it's upon the sheath and some will say that it's outside of the sheath
I think that these these contradictions are more a function of anatomical variation than
they are a true disagreement so let's take a look at what all can be found within the
carotid sheath and their various relationships to one another so starting medially here this is
typically a very prominent feature of the sheath you have the common carotid artery
the common carotid artery is a medial
feature of the sheath it's something that is very heavily invested by the fossa that common
carotid artery is going to bifurcate into external and internal carotid arteries in
the internal carotid artery is going to continue superior lis within the sheath
whereas the external carotid artery originates within the sheath but it quickly moves anterior
to it and leaves laterally we have the internal jugular vein so IJ is a lateral function within
going down and nestled between I J and common carotid is the vagus nerve vagus is posterior
to these elements and oftentimes nestled between the common carotid and the the IJ if we think
about this sheath extending up to the base of the skull Vagus and IJ are coming out of the jugular
foramen think about what other structures are going to exit that foramen as well so jugular
foramen exiting the skull cranial nerves nine ten and eleven Glassopharyngeal the vagus and
accessory nerve so glossopharyngeal and accessory nerves are going to exit the skull within the
carotid sheath and then exit from the carotid sheath also in very close association with eye
we'll see deep cervical lymph nodes and you can find the jugular lymphatic trunk
associated with those deep cervical lymph nodes the the lymphatics in the neck are very tightly
associated with the ijv so question for you to round up our discussion of the carotid sheath
which lymphatic trunk may be found within the carotid sheath perhaps this is a soft ball for
you now let's think about the the arrangement of lymphatics in the in the root of the neck so
we're going to have a right lymphatic duct on the right side and the thoracic duct on
the left side and these ducts are going to receive trunks in at the venous angles
so the right goes into the right venous angle the thoracic goes in the vicinity of the left
venous angle those venous angles are where the internal jugular veins meet the subclavian veins
so there are three trunks that conceptually feed into these ducts that feed into the vicinity of
the Venus angles there's going to be subclavian Trunks on either side there will be jugular
trunks on either side and then ascending the thorax there will be Broncomediastinal trunks
and these trunks may independently enter into the vicinity of the venous angle but
conceptually we have them going into into ducts and so within the within the carotid
sheath would be the jugular trunk correct answer is B okay thank you for your time well