spinal accessory nerve
Pronunciation: SPY-nal ak-SES-or-ee
Eleventh cranial nerve innervating trapezius muscle; injury during neck dissection causes shoulder dysfunction.
Full Definition
The spinal accessory nerve, also known as cranial nerve XI, provides motor innervation to the sternocleidomastoid and trapezius muscles. In head and neck oncology, this nerve is particularly vulnerable during posterior triangle neck dissections and radical neck dissections. Injury or sacrifice of this nerve results in trapezius muscle paralysis, leading to shoulder drop, scapular winging, and chronic pain syndrome known as shoulder syndrome. Preservation of this nerve is a key distinction between radical and modified radical neck dissections.
Usage
Usage note: Nerve preservation is a defining feature of modified radical neck dissection.
In Context
- "The spinal accessory nerve was sacrificed during the radical neck dissection." — Operative note
- "Physical therapy was initiated for spinal accessory nerve dysfunction and shoulder syndrome." — Rehabilitation plan