Overview
The long thoracic nerve powers serratus anterior, a muscle that holds the shoulder blade against the rib cage and helps rotate it during arm elevation.
Origin and Course
It usually arises from the C5, C6 and C7 nerve roots. It descends along the side of the chest on the superficial surface of serratus anterior, making its course unusually long and exposed.
Function
It is primarily a motor nerve. Serratus anterior protracts and upwardly rotates the scapula and prevents its medial border from lifting away from the chest wall.
Common Injuries
The nerve may be affected by traction, repetitive overhead activity, direct pressure, surgery or inflammation. Sometimes no single cause is found.
Pain and Weakness Patterns
Weakness can cause medial scapular winging, fatigue and difficulty lifting the arm overhead. Pain may occur around the shoulder blade, but winging also has other causes.
Clinical Relevance
Assessment may include observation during a wall push, strength testing and electrodiagnostic studies. Recovery varies with the cause and severity of nerve injury.
Related Anatomy
References
- Martin RM, Fish DE. Scapular winging: anatomical review, diagnosis, and treatments. Curr Rev Musculoskelet Med. 2008;1(1):1-11.
- Standring S, ed. Gray's Anatomy. 42nd ed. Elsevier; 2020.