Origin
It arises from the lower cervical vertebrae and the higher thoracic vertebrae.
Insertion
Between the superior and inferior nuchal lines.
Blood supply
Deep cervical artery, occipital artery.
Nerve supply
Greater occipital nerve.
Action
It helps to straighten the neck and head, turns the head side to side, and bends the neck (from ear to shoulder).
Disease/Injury
If this muscle is restricted, it hampers the rotation of neck. Blow to the back of head, stress, cervical spondylosis can cause pain in this muscle.
Muscle Exercise
You can practice neck flexion – Bring the head forward so that chin hits the chest and face staring down the floor. Repeat this slowly for 5 times. You can also practice neck extension. Slowly move your head back so that you can face the ceiling, keep it for few seconds and come back to the normal position again. Repeat this for 5 times.
Interesting fact
If there is pain in head like a band encircling top of head and going towards the eyes, it may be because of semispinalis capitis muscle dysfunction.