Which nerve provides innervation to the serratus anterior muscle?

The serratus anterior muscle is primarily innervated by the long thoracic nerve. This nerve originates from the brachial plexus, specifically from the roots of C5, C6, and C7. Its primary function is to innervate the serratus anterior, which plays a crucial role in the movement of the scapula, particularly in protraction and upward rotation. The serratus anterior is essential for actions like reaching forward and lifting the arms overhead.

The significance of the long thoracic nerve is highlighted by its unique pathway, running along the lateral thoracic wall and providing motor input to the muscle that stabilizes the scapula against the thoracic wall. This innervation allows for effective shoulder function and contributes to overall upper limb mobility. If the long thoracic nerve is injured, it can lead to a condition known as "winged scapula," where the scapula protrudes abnormally, affecting shoulder mechanics.

The other nerves listed, such as the accessory nerve, thoracodorsal nerve, and medial pectoral nerve, have different roles in the innervation of other muscles or providing different functions in the shoulder girdle and chest, but they do not innervate the serratus anterior.