Cranial nerve XI innervates which muscles?

Cranial nerve XI innervates which muscles?

• A. Latissimus dorsi
• B. Pectoralis major
• C. Trapezius and sternocleidomastoid
• D. Deltoid

Answer: (C)

The important idea here is knowing which muscles receive motor input from the accessory nerve (cranial nerve XI). This nerve’s primary role is to supply two muscles: the sternocleidomastoid and the trapezius. The sternocleidomastoid allows you to rotate your head to the opposite side and flex your neck, while the trapezius helps with moving and stabilizing the shoulder, including elevating the scapula. The other muscles listed have different nerve supplies: latissimus dorsi by the thoracodorsal nerve, pectoralis major by the medial and lateral pectoral nerves, and deltoid by the axillary nerve.

The important idea here is knowing which muscles receive motor input from the accessory nerve (cranial nerve XI). This nerve’s primary role is to supply two muscles: the sternocleidomastoid and the trapezius. The sternocleidomastoid allows you to rotate your head to the opposite side and flex your neck, while the trapezius helps with moving and stabilizing the shoulder, including elevating the scapula. The other muscles listed have different nerve supplies: latissimus dorsi by the thoracodorsal nerve, pectoralis major by the medial and lateral pectoral nerves, and deltoid by the axillary nerve.