Long thoracic nerve supplies which of the following muscles?
**Core Concept**
The long thoracic nerve is a vital nerve that supplies the serratus anterior muscle, playing a crucial role in the movement and stability of the scapula.
**Why the Correct Answer is Right**
The long thoracic nerve arises from the brachial plexus, specifically from the C5, C6, and C7 nerve roots. It then descends along the lateral thoracic wall to innervate the serratus anterior muscle, which is responsible for rotating the scapula upward and forward, facilitating movements such as arm abduction and forward elevation. The serratus anterior muscle also helps in stabilizing the scapula against the thoracic wall during movements.
**Why Each Wrong Option is Incorrect**
**Option A:** The thoracodorsal nerve supplies the latissimus dorsi muscle, not the serratus anterior. The thoracodorsal nerve arises from the posterior cord of the brachial plexus and is responsible for the motor innervation of the latissimus dorsi muscle.
**Option B:** The ulnar nerve primarily supplies the intrinsic muscles of the hand and forearm, not the serratus anterior. The ulnar nerve arises from the medial cord of the brachial plexus and is responsible for the motor innervation of muscles such as the flexor carpi ulnaris and the interosseous muscles.
**Option C:** The axillary nerve supplies the deltoid and teres minor muscles, not the serratus anterior. The axillary nerve arises from the posterior cord of the brachial plexus and is responsible for the motor innervation of the deltoid and teres minor muscles.
**Clinical Pearl / High-Yield Fact**
The long thoracic nerve can be vulnerable to injury during surgical procedures such as mastectomies or thoracic surgeries. Damage to this nerve can result in winging of the scapula, a condition characterized by the protrusion of the scapula from the thoracic wall due to weakness of the serratus anterior muscle.
**Correct Answer: C. Serratus anterior muscle.**