What muscle is primarily innervated by the long thoracic nerve?

The muscle that is primarily innervated by the long thoracic nerve is the serratus anterior. This nerve is responsible for supplying motor function to this muscle, which plays a crucial role in the movement and stabilization of the scapula during arm elevation and overhead activities. The serratus anterior is often referred to as the "boxer's muscle" because it is essential for actions such as punching and pushing, as it helps to protract the scapula and hold it against the thoracic wall.

Proper functioning of the serratus anterior is important for shoulder biomechanics, and weakness or paralysis of this muscle can lead to a condition known as scapular winging, where the scapula protrudes away from the back. This highlights the importance of the long thoracic nerve in maintaining shoulder stability and function.