Final answer:
The radial nerve is at risk when placing medial-lateral interlocks in a humeral nail due to its proximity to the surgical field. Damage to this nerve can lead to functional impairment of the forearm muscles. Proper surgical technique and anatomical knowledge are crucial to avoid such complications.
Step-by-step explanation:
The nerve at risk with medial-lateral (ML) interlocks in a humeral nail is the radial nerve. This nerve is inherently at risk during surgical fixation of fractures to the humerus because it runs in close proximity to the bone, particularly in the posterior aspect of the mid-shaft region. When ML interlocking screws are placed in a humeral nailing procedure, there is potential for iatrogenic injury to the radial nerve, especially if the surgical technique is not meticulous, or if the anatomy has been distorted due to the fracture.
Given that the radial nerve helps control the forearm muscles and provides sensation to parts of the hand, any damage to it can result in significant functional impairment. The ulnar collateral ligament is an intrinsic ligament on the medial side of the elbow joint connecting the medial epicondyle of the humerus to the medial ulna. Although it is not directly associated with the placement of a humeral nail, understanding its position and the anatomy of the elbow is critical in any orthopedic procedure to prevent damage to the adjacent structures including this ligament and the ulnar nerve which runs in proximity.