okay let's uh look at the neck first um the biggest um muscle around the neck is a sternal cido Musto and it kind of function across the whole cervical spine okay and um um it comes you know in a pair so if it work bilaterally you can see the muscle um at its insertion right here it's kind of um it it it'll extend the head at the C spine okay if it's close to the uh origin um right here it help to flex U the head okay and if it's um U work unilaterally just one side of it it'll um you see that the direction is going to go from um pull from here to here that would turn the head to the opposite side so for example right here um this girl who's driving um and taxing which is not good and which is illegal um but that's uh let's focus on her head so she's turning um to her right side to check the car or to check what's what's in the back SE so which side of uh the sternal cidal muso do you think that uh that would do this that would be the left side of the muscle kind of kind of contract to turn her head to the right okay and the sternal clom muso also called CM uh often times couple with other muscles to form a different movement um um one muscle um for the Deep cervical flexors uh it's called longus um cly right here it help uh when they work together it help prevent hyperextension of the of the the neck and also it help to um hold the head in position so that this individual Can Can U Can gaze right and it going to uh when this muscle is working with uh the SCM going to do the tuck the chin kind of movement which is something like a a ro a retraction of the neck okay and this muscle is uh this movement is really important because um um especially in kids you see uh like a cerebral posy um children um they typically well not typically a lot of them have difficulty swallowing or eating and uh a lot of them a lot of them have difficulty to tuck the the chin to have a more stable um head position while eating so the chewing the swallowing can be really hard for them if they don't have uh it's kind of challenging for them to to tuck the so this mus um going to function this way and SCM often times will cuto uh with spous cavitus splenius surfaces these are neck extensors okay to extend the neck uh when they do uh when they work uh bilaterally that will extend the neck when these two mus are going to work uh unilaterally that would roll rotate or let uh bend the neck to the same side okay so these are the neck muscles