Upper Limb — MCQs

A 34-year-old man sustains a mid-shaft fracture of the humerus following a road traffic accident. During the axillary surgical approach for fixation, the operating surgeon identifies and tags a nerve (arrowed in Image 2) based on its intraoperative course and relationships — not solely on the fracture pattern. Postoperatively, the patient has weakness of elbow flexion and loss of sensation over the lateral forearm, consistent with injury to the tagged nerve. The nerve was identified intraoperatively as it pierced a muscle of the anterior axillary wall, and the image shows this tagged nerve with a clear arrow at the point of entry. Which statement best describes the course of the tagged nerve that accounts for both the motor and sensory deficits seen in this patient?