Musculus sternocleidomastoideus

The video tutorial explains the sternocleidomastoid muscle, its origin, anatomy, and function. It highlights the muscle's role in head movement and its anatomical relations with vascular and nerve structures. The muscle's innervation by the accessory nerve and its function in head rotation and breathing are also discussed.

What is the role of the accessory nerve in relation to the sternocleidomastoid muscle?

How does bilateral contraction of the sternocleidomastoid muscle affect the head?