**Core Concept**
The posterior dislocation of the elbow, also known as a posterior elbow dislocation, is a rare injury where the ulna and radius bones are displaced posteriorly relative to the humerus. This injury often results in damage to nearby structures, including nerves.

**Why the Correct Answer is Right**
The radial nerve is most commonly involved in a posterior elbow dislocation due to its proximity to the elbow joint and its course through the radial tunnel. As the radius and ulna bones are displaced posteriorly, they can compress or stretch the radial nerve, leading to symptoms such as numbness, tingling, or weakness in the hand and forearm. The radial nerve is responsible for controlling the extensor muscles of the wrist and fingers, as well as providing sensation to the back of the hand and fingers.

**Why Each Wrong Option is Incorrect**
* **Option A:** The median nerve is not typically involved in posterior elbow dislocations, as it is located more medially and is not as closely associated with the elbow joint.
* **Option B:** The ulnar nerve is more commonly involved in injuries such as cubital tunnel syndrome or valgus stress injuries, rather than posterior elbow dislocations.
* **Option C:** The musculocutaneous nerve is not typically involved in posterior elbow dislocations, as it is located more proximally and is not as closely associated with the elbow joint.

**Clinical Pearl / High-Yield Fact**
In cases of posterior elbow dislocation, it is essential to perform a thorough neurological examination to assess for radial nerve damage, as this can impact the patient's ability to extend their wrist and fingers. Early recognition and treatment of radial nerve injury can improve outcomes and prevent long-term disability.

**Correct Answer: C. Ulnar nerve.**