Introduction The most common ulnar neuropathies are cubital tunnel syndrome caused by ulnar nerve compression at the elbow ulnar tunnel syndrome caused by ulnar nerve compression at the wrist in Guyon's canal Anatomy The ulnar nerve is a branch of the medial cord of the brachial plexus ulnar sensory function sensory branches dorsal cutaneous branch palmar cutaneous branch superficial terminal branches ulnar nerve innervates forearm flexor carpi ulnaris flexor digitorum profundus III and IV thenar adductor pollicis deep head of flexor pollicis brevis (FPB) fingers dorsal and palmar interossei 3rd and 4th lumbrical (1st and 2nd by median nerve) digiti minimi abductor digiti minimi opponens digiti minimi flexor digiti minimi Ulnar nerve at elbow see medial approach to elbow pierces intramuscular septum at Arcade of Struthers enters cubital tunnel which is formed by roof formed by Osborne's ligament (travels from the medial epicondyle to the olecranon) floor formed by posterior and transverse bands of MCL Ulnar nerve at wrist nerve enters Guyon's canal which is created by floor formed by tranverse carpal ligament, pisohamate ligament, pisometacarpal ligament, and opponens digiti minimi roof formed by volar carpal ligament ulnar wall formed by Pisiform and abductor digiti mini radial wall formed by Hook of hamate Presentation Symptoms same for both cubital and ulnar tunnel syndrome paresthesias over small finger and ulnar half of 4th finger and ulnar dorsum of the hand exacerbating activities include cell phone use (excessive flexion) night symptoms caused by sleeping with arm in flexion Physical exam deformity claw hand deformity sensory decreased sensation in ulnar 1 1/2 digits motor weakened grasp weak pinch provocative tests for cubital tunnel syndrome Tinnel sign positive over cubital tunnel Studies Radiographs usually normal EMG / NCV helpful to establish the diagnosis Treatment Nonoperative NSAIDS, activity modification, and night time bracing Operative ulnar nerve decompression