Which nerve, arising from the posterior cord, must be identified and preserved during axillary lymph node dissection to prevent weakness of adduction, extension and internal rotation of the shoulder?

• A Long thoracic nerve
• B Intercostobrachial nerve
• C Medial pectoral nerve
• D Thoracodorsal nerve ✓

Explanation

The thoracodorsal nerve carries fibres from C6, C7 and C8, arises from the posterior cord, and runs on the posterior axillary wall with the subscapular vessels to supply latissimus dorsi. Division weakens shoulder adduction, extension and internal rotation. The long thoracic nerve supplies serratus anterior, the medial pectoral nerve supplies pectoral muscles, and the intercostobrachial nerve is purely sensory to the medial arm.

Reference: Moore's Clinically Oriented Anatomy, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.