Which nerve supplies the posterior medial aspect of the arm?

Which nerve supplies the posterior medial aspect of the arm?

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

Answer: (A)

The sensation of the medial side of the upper arm comes from the intercostobrachial nerve, a sensory branch of the second intercostal nerve. It travels from the thoracic wall into the axilla and provides cutaneous innervation to the medial aspect of the proximal arm, which includes the posterior-medial region near the axilla. The other nerves listed supply different regions: the axillary nerve covers the lateral shoulder/arm area, the musculocutaneous nerve supplies the lateral forearm, the median nerve supplies the lateral palm and forearm, and the posterior cutaneous nerve of the arm covers the posterior aspect of the arm but not the medial side. Therefore, the intercostobrachial nerve best explains the posterior medial arm skin innervation.

The sensation of the medial side of the upper arm comes from the intercostobrachial nerve, a sensory branch of the second intercostal nerve. It travels from the thoracic wall into the axilla and provides cutaneous innervation to the medial aspect of the proximal arm, which includes the posterior-medial region near the axilla. The other nerves listed supply different regions: the axillary nerve covers the lateral shoulder/arm area, the musculocutaneous nerve supplies the lateral forearm, the median nerve supplies the lateral palm and forearm, and the posterior cutaneous nerve of the arm covers the posterior aspect of the arm but not the medial side. Therefore, the intercostobrachial nerve best explains the posterior medial arm skin innervation.