The accessory nucleus innervates which muscles?

The accessory nucleus innervates which muscles?

• A. Muscles of head and neck
• B. Chest muscles
• C. Leg muscles
• D. Diaphragm

Answer: (A)

The spinal accessory nucleus is the group of motor neurons in the cervical spinal cord that gives rise to the spinal accessory nerve. This nerve innervates the sternocleidomastoid and trapezius muscles, which control movements of the head, neck, and shoulders. That’s why the correct choice is muscles of the head and neck. The diaphragm is controlled by the phrenic nerve, chest muscles by thoracic nerves, and leg muscles by lumbosacral nerves, so those options don’t fit this nucleus’s targets.

The spinal accessory nucleus is the group of motor neurons in the cervical spinal cord that gives rise to the spinal accessory nerve. This nerve innervates the sternocleidomastoid and trapezius muscles, which control movements of the head, neck, and shoulders. That’s why the correct choice is muscles of the head and neck. The diaphragm is controlled by the phrenic nerve, chest muscles by thoracic nerves, and leg muscles by lumbosacral nerves, so those options don’t fit this nucleus’s targets.