GROSS ANATOMY

Detailed explanation-1: -Answer and Explanation: The answer is c, spinal accessory nerve, also known as cranial nerve XI. The actions of shrugging the shoulders and turning the head can be performed by the upper fibers of the trapezius and the sternocleidomastoid muscles, respectively.

Detailed explanation-2: -11th Cranial nerve The 11th (spinal accessory) cranial nerve is evaluated by testing the muscles it supplies: For the sternocleidomastoid, the patient is asked to turn the head against resistance supplied by the examiner’s hand while the examiner palpates the active muscle (opposite the turned head).

Detailed explanation-3: -This nerve supplies the sternocleidomastoid and trapezius muscles, which have the following functions: Rotation of head away from the side of the contracting sternocleidomastoid muscle. Tilting of the head toward the contracting sternocleidomastoid muscle. Flexion of the neck by both sternocleidomastoid muscles.

Detailed explanation-4: -Accessory Nerve. The accessory nerve is a purely motor branch to the trapezius and sternocleidomastoid muscles: Sternocleidomastoid can be assessed by asking the patient to turn their head to each side, against the examiners resistance.