hi all doctor Alsup here in this learning objective video we will be reviewing the
afferent nerves that emanate from the nerve point of the neck while these nerves are
difficult to see in dissection they can convey really important information from the skin an
external environment back to the central nervous system in addition to understanding which nerves
afferently innervate the neck and neck and shoulder region we will speak regarding the
spinal cord levels and associated spinal nerves that will be the source of these afferent nerves
so let's get started let's identify where the nerve point of the neck is we have a nice kind
of dashed yellow circle indicating about the location of the nerve point of the neck it will
be at the midpoint of the posterior border about the midpoint give or take some of the posterior
border of the sternocleidomastoid muscle and so this is a common region for these cutaneous nerves
to emerge in this region before spreading out towards the territory it will innervate you will
often hear this nerve point of the neck referred to as Erb's point in anatomy terminology we've
really been moving away from using eponyms or naming areas after people but clinically this
practice often persists so you will often hear nerve point of the neck or Erb's point of the
neck now these cutaneous nerves are branches of the cervical plexus and what does this word
mean what does plexus mean it means a braid so let's talk about that what it was a braid have
to do with nerves so at plexus ease there will be a braiding or intermingling of axons from
various spinal cord levels so making nerves from the cervical plexus these nerves are rarely from
just one spinal nerve but usually from two or more the cervical plexus is derived from the ventral
primary rami or the VPR's of C through c4 we will talk a bit more about what a vpr is in the next
session so kind of hold on there I promise we'll get to that superficial branches of the cervical
plexus are mostly sensory heading towards the skin so you will often hear this type of nerve referred
to as a cutaneous nerve they will send signals back from the skin or from the skin back to the
central nervous system these tend to be smaller and more difficult to dissect the deeper branches
are mostly motor or efferent and we will talk more about these when we discuss the infrahyoid muscles
so that ansa cervicalis there are four nerves we will want to locate and understand which spinal
cord level the nerves have derived from and let's start with the lesser occipital nerve I'm going to
outline it right here here's that nerve point of the neck just to kind of get back into the
groove of things there the lesser occipital nerve is composed of fibers from c2 and sometimes c3
that's why I have c3 bracketed here this nerve will innervate the skin of the neck and scalp
behind or posterior to the ear so think behind the ear the great auricular nerve which I'm going to
outline here is composed of fibers from c2 and c3 it will a fairly innervate skin around the parotid
gland region and so it will also send branches kind of inferior to the year as well as of course
anterior to the ear the transverse cervical is derived also from c2 and c3 so I hope you have
noticed that all one of the four cutaneous nerves we're talking about are innervated or created
by or originating from fibers from c2 and c3 so this transverse cervical nerve is going to kind
of move transversely as the name would suggest and innervate the skin of the anterior cervical
neck region so basically all of that anterior neck region lastly the supraclavicular nerves are the
most expansive in terms of branches with medial intermediate and lateral branches originating from
c3 and c4 so you can see to here also coming from that nerve point of the neck it will have branches
kind of extending all over this region these branches will provide innervation to the skin of
the neck across the clavicle as you can see here and over the skin of the shoulder there has been
consistent research that in some individuals the great auricular as well as the transverse cervical
nerve branches may play a supportive role in sensory innervation of the mandibular teeth
this is a bit more complex than what we need you to know for this course and for our understanding
of this area so aka you will not be tested on that specifics but I wanted to mention that it may play
a role in terms of main tubular teeth innervation because your dental faculty may discuss this as
you move forward in your education so I wanted to at least mention it here but mainly focus on
the skin innovation or cutaneous innovation for testing purposes well that is it for the nerve
point of the neck and it's cutaneous branches let's have a question to review all right the
question for this session is an individual notices distinct numbness directly inferior to their ears
so there's numbness in their skin inferior to the ear which of the following nerves is most likely
affected to cause the lack of sensation in this area is it A. accessory nerve or cranial nerve
11 B. the ansa cervicalis C. great auricular nerve D. supraclavicular nerve or E. transverse cervical
nerve all right pause the video if needed and I hope you have found your way to the correct answer
which is C the great auricular nerve the great auricular nerve will serve the area's inferior
to and anterior to the ear so great auricular is correct we know that the accessory nerve is not
correct because it is solely efferent remember so it would not be an afferent nerve so that
would make that incorrect also we know that it will innervate the sternocleidomastoid in the
trapezius muscles so very wrong ballpark here it's not the ansa cervicalis either which is going to
be associated with those strap muscles or the infrahyoid muscles so this is something we'll
talk about in a bit more detail in that video the supraclavicular nerves are cutaneous nerves
from the nerve point of the neck but these will innervate skin across the clavicle in the shoulder
and the transverse cervical will apparently serve the skin across the anterior neck notice I didn't
put the lesser occipital nerve as an answer choice the sir occipital nerve would have been wrong but
it's territory which is that skin posterior to the ear is awfully close to the territory described
and the question stand so inferior to the ear and often cutaneous nerve territories will overlap
so I kept that one off as an option just to be safe alright so that is all we have here please
take your time to review these concepts and reach out with any questions have a great day