The right and left sternocleidomastoid muscles of humans ori

The right and left sternocleidomastoid muscles of humans originate on the upper surfaces of breast bone and collar bones, pass along both sides of the neck, and insert just behind the ears on the mastoid processes. Describe the action that occurs if both sides contract together.

Solution

If one sternocleido mastokd contracts, it flexes the cervical vertibral column to the same side and rotates the head to the opposite side. When both the sides contract together , it flexes the neck amd extends the head.