Which nerve innervates the deltoid and teres minor?

Which nerve innervates the deltoid and teres minor?

• A. Musculocutaneous nerve
• B. Axillary nerve
• C. Radial nerve
• D. Median nerve

Answer: (B)

The deltoid and teres minor receive their motor signals from the axillary nerve. This nerve comes from the brachial plexus (C5–C6) and travels through the quadrangular space in the shoulder, where it gives branches to both the deltoid and the teres minor. It also provides sensation to the skin over the lateral shoulder via a small cutaneous branch. Understanding the role helps connect structure and function: the deltoid is the major muscle for lifting the arm away from the body after the initial 15 degrees, while the teres minor helps with external rotation. If the axillary nerve is damaged, you’ll see weakness in shoulder abduction beyond the early phase and trouble rotating the arm outward, often with numbness on the outer shoulder. The other nerves listed don’t innervate both of these muscles: the musculocutaneous nerve targets the anterior arm flexors, the radial nerve supplies the posterior arm and forearm extensors, and the median nerve covers many forearm and some hand muscles.

The deltoid and teres minor receive their motor signals from the axillary nerve. This nerve comes from the brachial plexus (C5–C6) and travels through the quadrangular space in the shoulder, where it gives branches to both the deltoid and the teres minor. It also provides sensation to the skin over the lateral shoulder via a small cutaneous branch.

Understanding the role helps connect structure and function: the deltoid is the major muscle for lifting the arm away from the body after the initial 15 degrees, while the teres minor helps with external rotation. If the axillary nerve is damaged, you’ll see weakness in shoulder abduction beyond the early phase and trouble rotating the arm outward, often with numbness on the outer shoulder.

The other nerves listed don’t innervate both of these muscles: the musculocutaneous nerve targets the anterior arm flexors, the radial nerve supplies the posterior arm and forearm extensors, and the median nerve covers many forearm and some hand muscles.