True about sternocleidomastoid are -a) It arises from sternum and clavicleb) Turns head to the opposite sidec) Shortened in congenital torticollisd) Supplied by the cranial accessory nervee) Supplied by occipital artery
High-Yield Explanation
Sternocleidomastoid arises by two heads : (i) Sternal head (from sternum), and (ii) clavicular head (from clavicle).
Contraction of one side of sternocleidomastoid causes : (i) Tilting (bending) of head on same side, and (ii) Turning (rotation) of face and head on opposite side, which can be appreciated as turning of chin to opposite side.
Congenital shortening of sternocleidomastoid causes torticollis (wry neck).
Sternocleidomastoid is supplied by spinal part of accessory nerve (spinal accessory nerve), not by cranial part (cranial accessory).
It is supplied by superior thyroid, suprascapular, and occipital arteries.