Nerve entrapment occurs when a nerve becomes compressed as it travels through tight spaces in the body. The ulnar nerve is commonly entrapped at the elbow, where it passes through the cubital tunnel, or at the wrist in Guyon's canal. Symptoms include numbness, tingling, and weakness. Treatment involves modifying activities that cause compression, splinting, and sometimes surgery to decompress the nerve. The double crush syndrome can occur when a nerve is compressed at multiple sites, worsening symptoms.