American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which nerve is responsible for the sensation in the medial arm and axilla?

1. Thoracodorsal nerve

2. Intercostobrachial nerve

3. Lateral pectoral nerve

4. Medial brachial cutaneous nerve

The correct answer is: Intercostobrachial nerve

The intercostobrachial nerve is responsible for providing sensory innervation to the skin of the medial aspect of the arm and the axilla. This nerve usually arises from the second intercostal nerve and communicates with the medial brachial cutaneous nerve, allowing it to extend its sensory distribution into the upper limb and axillary area. Understanding the anatomy of the brachial plexus and its branches is crucial for recognizing the areas of cutaneous sensation they supply. While the thoracodorsal nerve and lateral pectoral nerve serve different functions—innervating muscles such as the latissimus dorsi and pectoralis major, respectively—they do not provide sensory information to the medial arm or axilla. The medial brachial cutaneous nerve primarily innervates the skin of the medial arm but does not extend into the axillary region as significantly as the intercostobrachial nerve. Thus, the intercostobrachial nerve is the key nerve associated with sensation in this specific area.