The long thoracic nerve is a nerve which innervates the serratus anterior, a muscle found on the side of the chest. The serratus anterior covers several ribs and wraps around to the scapula, holding the scapula in place and providing it with stability. Damage to the long thoracic nerve or the serratus anterior can lead to a condition known as winged scapula, in which the scapula does not lie flat. Depending on the nature of the damage, the condition may not be immediately apparent without a medical examination.

The origins of the long thoracic nerve can be found in the brachial plexus, a bundle of nerves which splits into a number of branches to innervate muscles in the arm, armpit, and chest. Classically, the long thoracic nerve splits from the fifth, sixth, and seventh cervical nerves in the brachial plexus, although sometimes the roots are only in the fifth and sixth cervival nerves.

This nerve wraps behind the brachial plexus and runs down the chest to fully innervate the serratus interior. This muscle has a series of fingerlike projections which attach to the ribs, causing the long thoracic nerve to branch considerably as it reaches its destination to fully cover the muscle.

There are a number of ways in which the long thoracic nerve can be injured. One of the most common is trauma, because the nerve sits relatively close to the surface of the skin, making it vulnerable to blows which may be incurred during sports, falls, fights, or car accidents. In addition to trauma, the nerve can also be injured through overextension, in which the nerve is strained during stretching. This may occur when someone is not properly warmed up, or when someone overreaches the comfort zone of a stretch. Certain torture methods such as the use of stress positions can also cause damage to the long thoracic nerve.

Iatrogenic damage to the long thoracic nerve can also be an issue. The term “iatrogenic” is used to describe injury or harm which occurs during the course of medical treatment. While doctors try to avoid making their patients worse while they try to help them get better, iatrogenic injuries can happen. In the case of the long thoracic nerve, surgery on the chest may result in damage to the nerve, classically in the case of axillary node dissection, in which the lymph nodes around a breast cancer are removed.