Spinal Accessory Nerve XI

Question 1

What is the function?

Answer 1

Somatic Motor- innervating STERNOCLEIDOMASTID and TRAPEZIUS muscles

Question 2

Describe the anatomical course?

Answer 2

Spinal portion of the nerve: arises from the upper spinal cord(C1-C5 roots) and enters cranial cavity via the FORAMEN MAGNUM, then heads to the JUGULAR FORAMEN

The cranial portion:

• Arises from the medulla oblongata
• exits cranial cavity via JUGULAR FORAMEN
• then the nerve passes near the internal carotid artery heading to the STERNOCLEIDMASTIOD and then TRAPEZIUS muscle

Question 3

How do you test the spinal accessory nerve?

Answer 3

Ask patient to turn their head against your hand. This allows us to test the nerve because it provides MOTOR INNERVATION to the STERNOCLEIDMASTOID muscle which allows you to turn your head to the opposite side of the muscle

Testing via upper fibres of trapezium-patient shrugs shoulders whilst you try to push them back down

Question 4

What causes damage in this nerve and what are the consequences?

Answer 4

One pair damages =patient cant turn their head against resistanc e(weakness of sternocleidmastoid muscles) on the affected side

damage due to complication of a posterior triangle lymph node biopsy or excision