Orthotics and Prosthetics Written Boards Practice Exam 2025 – Complete Study Guide

The function that would be most limited with a torn lateral cord of the brachial plexus is wrist flexion. The lateral cord contributes primarily to the musculocutaneous nerve and part of the median nerve, both of which are responsible for innervating muscles involved in wrist and finger flexion.

Injury to the lateral cord affects the musculocutaneous nerve, which innervates the biceps brachii muscle, critical for elbow flexion. It also impacts the median nerve's ability to innervate several muscles in the forearm and hand that are responsible for wrist flexion and fine motor movements.

This anatomical relationship highlights why wrist flexion would be unaffected by a tear in the lateral cord; instead, it significantly compromises the capacity to perform wrist flexion. Other functions, such as wrist extension and finger abduction, primarily involve nerves unaffected by damage to the lateral cord, while shoulder adduction is mainly facilitated by the lower trunk and posterior cord. Therefore, the most significant limitation stemming from a torn lateral cord is wrist flexion.