ANATOMY

Detailed explanation-1: -The ipsilateral activation of the XI nerve can activate the intrinsic laryngeal muscles fibers for the correct movement of the vocal cords of the same side. The main functions remain those of contracting the trapezius muscle and the sternocleidomastoid.

Detailed explanation-2: -The spinal component of the accessory nerve provides motor control of the sternocleidomastoid and trapezius muscles. The trapezius muscle controls the action of shrugging the shoulders, and the sternocleidomastoid the action of turning the head.

Detailed explanation-3: -The accessory nerve is a motor nerve that supplies the sternocleidomastoid and trapezius muscles. Some texts consider the ‘cranial’ root, which arises from the caudal portion of the nucleus ambiguus, as part of the accessory nerve.

Detailed explanation-4: -Cranial Nerve XI (Spinous Accessory) The sternocleidomastoid (SCM) and trapezius muscles, which aid in stabilization and movement of the cervical spine and shoulders, receive their innervation from the eleventh cranial nerve (the spinous accessory nerve).