Lesions of the musculocutaneous nerve can result in all of the following, EXCEPT:
**Core Concept**
The musculocutaneous nerve is a mixed nerve that innervates the biceps brachii, brachialis, and coracobrachialis muscles, providing motor function to the elbow flexors and forearm supinators. It also provides sensory innervation to the lateral aspect of the forearm.
**Why the Correct Answer is Right**
The musculocutaneous nerve innervates the biceps brachii, brachialis, and coracobrachialis muscles, leading to weakness or paralysis of elbow flexion and forearm supination. This results in difficulty performing activities that require flexion of the elbow, such as lifting the arm or carrying heavy objects. The sensory loss from the musculocutaneous nerve affects the lateral aspect of the forearm, which may cause numbness or tingling in this area.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because the musculocutaneous nerve does indeed innervate the biceps brachii, leading to weakness or paralysis of elbow flexion.
* **Option B:** This is incorrect because the musculocutaneous nerve does indeed provide sensory innervation to the lateral aspect of the forearm.
* **Option C:** This is incorrect because the musculocutaneous nerve does indeed innervate the brachialis muscle, leading to weakness or paralysis of elbow flexion.
**Clinical Pearl / High-Yield Fact**
The musculocutaneous nerve is often tested clinically by assessing the strength of elbow flexion and forearm supination, as well as the presence of sensory loss on the lateral aspect of the forearm.
**Correct Answer: D.**