hello anatomy colleagues this is dr alsup and we are going to work our way through the
nerves that we need to be able to identify for the anterior neck and thorax session
so we're going to start with the nerves that are more associated with the neck
and then we'll move to the thorax starting with the accessory nerve or cranial nerve 11.
now recall cranial nerve 11 is going to efferently innervate the sternocleidomastoid so sometimes
it's helpful to kind of identify the muscles as well as the trapezius muscle so you can see this
is the trapezius on the back here's that rope-like sternocleidomastoid and in this particular image
the sternocleidomastoid has been reflected you can just see a little bit of the trapezius
and this the accessory nerve you at least in terms of how we would assess we would always want to be
able to see it between the sternocleidomastoid and the trapezius so it is the small nerve right
here that is between the sternocleidomastoid and the trapezius these are going to be more of those
fibers from the spinal nerves you can really nicely see it here on this image i'm going
to outline it right here and so you can see it clearly going between the sternocleidomastoid and
the trapezius what is unique about the accessory nerve in comparison to some of the other nerves
is that it has almost a coiled appearance so it's kind of squiggly in comparison to some of
the other nerves that we will see and it's on a little bit of the larger side these nerves
right here are going to be nerves of the the cervical plexus that are more afferent fibers
but again that anatomical relationship that is key for accessory as you can see that is going to be
between the sternocleidomastoid and the trapezius and it is on the larger more squiggly side
next is the ansa cervicalis sansa cervicalis i hope you recall is going to be innervating
the strap muscles or those infrahyoid muscles so the hyoid is going to be right here
your strap muscles are going to be over in this region and the anticervicalis is typically found
either within or on top of the carotid sheath and in this particular dissection the carotid
sheath has been removed but you can see carotid sheath content so here's your common carotid
your inter your vagus would be deep and the internal jugular vein and i'm going to outline
where your ansa cervicalis is you can see it's this really pretty loop around this region then
you kind of lose it back here and you can see some of it the muscular branches of ancient cervicalis
heading to those strap muscles so close relationship to the carotid sheath contents
um but a superficial relationship and then of course it's going to be this nice
loop with some muscular branches heading towards those strap muscles
the vagus nerve or cranial nerve 10 will be our good friend throughout the year it will
keep kind of popping up it is going to exit the jugular foramen in this region and then
it will descend through the neck region as part of the carotid sheath content so again we're looking
at a slightly different dissection but here is the common carotid artery so very nice very large in
the neck region here's your internal jugular vein you can see a bit of that ansa cervicalis that i'm
outlining right here and then here is the vagus and the vagus, for a nerve, is quite large
it's usually going to be intermediate and deep in terms of its location within the carotid sheath
so you can see the carotid are common carotid is medial the internal jugular is lateral and
here's that vagus nerve kind of in the middle of those two structures and deep
lastly we'll move down towards the thorax region you are going to have your pectoral nerves that
are going to be associated with the pectoral muscles uh kind of getting our bearings in
terms of which ones which this is going to be the pectoralis major that has been reflected
in order for us to be able to see the pectoralis minor and the neurovasculature in this region
recall that both the medial and the lateral pectoral nerves are going to innervate
the pec major and only the medial pectoral nerve will innervate the pectoralis minor and another
key anatomical relationship when we're talking about the medial pectoral nerve is that it is
going to pierce the pectoralis minor in turn and what i mean by that is that literally it will
kind of go in between the muscular fibers of pec minor and you can see that here and here so these
are both branches of the medial pectoral nerve and you can see that it's also extending up and
heading towards the deep side of the pectoralis major in order to innervate it it's a little bit
more difficult to tell which one of these is going to be the lateral pectoral nerve
but it's going to be this one right in this region now keep in mind in a practical setting we would
ask you to identify the nerve or say the artery so you wouldn't have to differentiate between
which one's the nerve and the artery and these neurovascular bundles but you can see that it
is heading towards the deep side of the pectoralis major and it is not piercing the pectoralis minor
so that seems like that is a good indication that we are looking at the lateral pectoral nerve
alright excellent so those are the the nerves of the anterior neck and thorax that you are going to
need to be able to identify and understand those anatomical relationships please take your time to
review and as always if you have any questions or clarification that you need please always
feel free to reach out to myself or any of my colleagues thank you for your time and attention