hello anatomy colleagues this is dr alsup again and welcome to station number 19 where we are
looking at some of the muscles associated with the neck and you can't talk about neck
musculature without talking about arguably the most dominant muscle in this area and that is the
sternocleidomastoid muscle as you can see on this particular image that is a straight anterior image
you can see that it is going to form this fairly large region on the lateral sides of the neck
and it is these other muscular muscles that will talk about the supra and infrahyoid muscles that
will be more in the midline and will be a little bit deeper than those structures there
but sternocleidomastoid is forming these very rope-like dominant muscles a bit more
superficially and you can really see it quite well on this kind of anterolateral image of the
sternocleidomastoid and it's going to have its superior attachments way up here towards the
ear so that mastoid process and a little bit on the occipital bone and then we'll have its
more inferior attachments on the manibrium of the sternum which you can't quite see here but
you can see the tendon extending there and as well as the clavicle thus the sterno meaning
sternum cleido meaning clavicle and then of course that mastoid up here in the superior attachment
so very dominant in this region you can see the external jugular vein is always going to run over
this particular muscle that's something that can be visible through the skin and it is going to
be superficial to the carotid sheath which is a really important neurovascular bundle when you
talk about some of the structures when you're in the vascular part of the course and again it
is going to be more lateral and superficial to those suprahyoid muscles and infrahyoid muscles
okay moving quite deep in terms of the neck so the sternocleidomastoid has been
reflected you can see it all the way up here in this image you will have one muscle
again that is quite deep it is going to have its distal attachment on the first rib which has been
cut here you can see a little bit of the lung right here so we are quite deep in this region
and this is going to be something you'll learn later but the arch of the aorta that is going to
give off some of the larger structures associated with the neck and the root of the neck to head to
the upper limb and we're focused mainly on this artery right here the subclavian artery
it will change its name around this region here into the axillary but the reason that i wanted to
point this out is because the anterior scalene which is this muscle here that i'm outlining
the anterior scalene is going to subdivide the subclavian artery into three parts
based on its relationship with the anterior scalene so if this portion right here that
is medial to the anterior scalene would be the first part the second part would be deep
to the anterior scalene so we can't see it here because the anterior scalene hasn't been reflected
and then the third part would be lateral to the um anterior scalene or distal to and then once
again once it passes this first rib region the name changes to the axillary artery this
is going to play a supplementary role in terms of respiration as well but a lot of times when
you hear about anterior scalene you mainly hear about it in its relationship with the subclavian
artery but also there's going to be a nerve right here that sits right on top or superficial to the
anterior scalene which is the phrenic nerve that's important in terms of innervating the diaphragm
so more about its anatomical relationships and less about its uh function in terms of contraction
and lastly you can't talk about the muscles of the neck without talking about the supra and the
infrahyoid muscles there are going to be four of each but i'm not going to have you identify any
of the specific ones but i do want you to have a basic understanding of where they are located
and their basic functions for me when i'm trying to identify these i always try to find the hyoid
bone which is a little bit difficult to see but is right here this will be the hyoid so any of the
muscles that are superior to that would be part of the suprahyoid muscles and then any muscles that
are inferior to that and still towards the midline region would be part of the infrahyoid muscles
so you can see them right over in these regions these super hyoid muscles
are going to play a role in terms of supporting the hyoid as are the infrahyoid muscles but the
suprahyoid muscles when they contract can play a role in terms of elevation of the hyoid you can
see that it's also forming kind of the floor of the mouth whereas these infrahyoid muscles are a
bit longer they're a bit strap like that's why you often hear these muscles referred to as the strap
muscles instead of the infrahyoid muscles and they can play a role in terms of um depressing
the hyoid or moving it inferiorly um and some of these will actually have a connection to the
thyroid cartilage which is part of the larynx so if we were to flex some of these infra if we were
to reflect the infrahyoid muscles you could see the larynx and you could see the thyroid gland
so there's a lot more structures associated with under or deep to the infrahyoid muscles
okay excellent so those are the muscles of the neck some are quite large
um and obvious like the sternocleidomastoids which you can see here that are reflected
oftentimes you have to reflect this to be able to see any of those deeper structures
we had the anterior scalene which is quite deep you would have to be at the level of the
subclavian artery to really see that and then of course the supra and infrahyoids
supra above the hyoid infra below the hyoid and mostly in the midline region all right
excellent thanks for your time and attention here and let us move on to the next station