Structure & Function of the Spinal Accessory Nerve (CN XI)

The video tutorial provides an in-depth look at the spinal accessory nerve, also known as cranial nerve 11. It explains that this nerve is purely motor and innervates the trapezius and sternocleidomastoid muscles. The tutorial challenges traditional definitions of cranial nerves by highlighting that the spinal accessory nerve originates from the spinal cord, not the brain. It details the nerve's unique pathway, ascending through the foramen magnum and descending through the jugular foramen. The video also covers the clinical implications of nerve damage, such as ipsilateral issues with muscle function.

Which muscles are innervated by the spinal accessory nerve?

• Deltoid and pectoralis major

• Trapezius and sternocleidomastoid

• Latissimus dorsi and rhomboids

• Biceps and triceps

What is the primary function of a motor cranial nerve?

• To connect to the spinal cord

• To exit the cranium

• To transmit sensory information

• To enter the cranium

Where does the spinal accessory nerve originate?

• The medulla oblongata

• The spinal cord

• The brain

• The cerebellum

Through which foramen does the spinal accessory nerve ascend?

• Jugular foramen

• Foramen ovale

• Foramen rotundum

• Foramen magnum

What is a potential symptom of damage to the spinal accessory nerve?

• Difficulty swallowing

• Inability to elevate the scapula

• Loss of sensation in the arm

• Loss of taste

How does the sternocleidomastoid muscle function in neck movement?

• Flexion

• Contralateral rotation

• Ipsilateral rotation

• Extension

What happens to the trapezius muscle if the spinal accessory nerve is damaged?

• It enlarges

• It becomes hyperactive

• It atrophies

• It becomes more flexible