The neck muscles exist to support the head - they attach the head to the torso and allow movement.
The big muscles at the front back and side of the neck, provide the gross movements of the head:
The scalene muscles at the side of the neck can work together, both sides at the same time, or one side at a time.
There are actually 3 scalene muscles each side of the neck:
The scalenes start at the very top of the side of the spine and attach down on the side of the clavicle. So they all start in the centre line of the body; but (not surprisingly) they end at different points on ribs just under the clavicle the clavicle - the anterior one towards the front of the torso, the middle in the middle, and the posterior very slightly towards the back of the torso.
When a complete set of scalenes (anterior, middle, posterior) contract together at the same time they rotate the head in that direction .
When both sets (both sides of the neck) of scalenes work, they draw the rib cage up. So in fact, the scalenes get used all the time - every time we breathe in, the rib cage needs to be drawn up to allow the breath, so the scalenes are called into action.
So sternocleidomastoid (also known as SCM) is the muscle at the front of the neck. It's most important function is postural: helps keep the head upright. In an ideal world, the SCM works with the muscle at the back of the neck to keep your head upright. In the real world of desk work, driving and spending our days on smartphones, though, our heads are pretty much always forward.
I've blogged before about the head forward posture and the damage that you can do to your body (it's a good one to check out). Because our head is forward from where it should be most of the time, we develop muscles at the back of the neck (the neck extensors) a bit like my greyhound's - really powerful. The SCM just gets weaker and weaker because it's not being used.
This can then make certain movements harder. The actions of SCM are:
If SCM is weak, then rotating your head to the side is left to the scalenes which can then become overworked and tired.
It also means that, since sternocleidomastoid is underdeveloped that neck raises will be hard.
The big problem with a weak SCM is that any sudden or unexpected movements with force, might lead to a neck strain, so it's worth trying hard to keep your head upright rather than forward.
The muscles at the back of the neck (think of them as opposite SCM) are the 2 levator scapule. Each one runs from the top of the back (it actually starts along the inside top edge of the shoulder blade opposite the spine - then runs up to the top of the neck.
Like the sternocleidomastoid, levator scapula is a postural muscle whose main function is to keep the head upright, but in modern living tends to be overdeveloped because we keep our head forward all the time.
If you get an ache at the top of your shoulders, and most of us do, then it's pretty much always the levator scapulae which are to blame.
Lev scap has a lot of actions:
When lev scap works individually on one side, is actions are:
What's really interesting about these 3 sets of muscles (lev scap, scalenes and SCM) is how closely they lie to one another - especially towards the head. So if you get an issue in the muscles of your neck, it's really important to identify correctly which one is causing the problem, so that it can be sorted quickly.
As ever, if you think I can help, give me a call.