Spinal Accessory Nerve (CN XI) | Anatomy & Functions

The video tutorial discusses the spinal accessory nerve, also known as cranial nerve 11, which is a motor nerve innervating the trapezius and sternocleidomastoid muscles. It challenges the traditional definition of cranial nerves by explaining that the spinal accessory nerve originates from the spinal cord, not the brain. The nerve ascends through the foramen magnum and exits the cranium via the jugular foramen. The tutorial also covers the clinical implications of damage to this nerve, such as ipsilateral issues in muscle function and atrophy.

Which muscles are innervated by the spinal accessory nerve?

• Biceps and triceps

• Sternocleidomastoid and trapezius

• Trapezius and deltoid

• Latissimus dorsi and pectoralis major

What is the primary function of the spinal accessory nerve?

• Motor

• Sensory

• Autonomic

• Mixed

Where does the spinal accessory nerve originate?

• Spinal cord

• Medulla oblongata

• Pons

• Midbrain

Through which foramen does the spinal accessory nerve ascend?

• Foramen ovale

• Jugular foramen

• Foramen magnum

• Optic canal

Which cranial nerves descend through the jugular foramen?

• Cranial nerves 4, 5, and 6

• Cranial nerves 1, 2, and 3

• Cranial nerves 9, 10, and 11

• Cranial nerves 7, 8, and 9

What symptom might indicate damage to the right spinal accessory nerve?

• Inability to elevate the right scapula

• Weakness in rotating the head to the left

• Weakness in rotating the head to the right

• Inability to elevate the left scapula

What is the function of the sternocleidomastoid muscle?

• Flexion of the arm

• Elevation of the scapula

• Contralateral rotation of the head

• Ipsilateral rotation of the head