What is the function of the long thoracic nerve?

• A. Innervates the pectoralis major
• B. Innervates the serratus anterior muscle
• C. Innervates the latissimus dorsi
• D. Innervates the pectoralis minor

Answer: (B)

The long thoracic nerve primarily innervates the serratus anterior muscle, which plays a critical role in the movement and stabilization of the scapula. This muscle is essential for various actions such as protraction of the scapula, which is important for overhead movements and lifting tasks. When the serratus anterior is properly functioning, it helps hold the scapula against the thoracic wall, allowing for a greater range of motion and stability of the shoulder joint. Damage to the long thoracic nerve can lead to winging of the scapula, highlighting the nerve's importance in shoulder and upper limb function.

Other options would not be correct in this context as they pertain to different muscles innervated by other nerves.