Snapshot A 32-year-old woman presents to the emergency room with severe right arm pain after being involved in a motor vehicle collision. She has a comminuted open fracture of the right distal radius and ulna. She is taken to the operating room where lesions to the distal ulnar artery and nerve are noted. She undergoes multiple surgical procedures over the following several months until her radius and ulna appear well healed. However, she has residual hand weakness and is unable to completely open her hand after making a fist. On exam, her 4th and 5th metacarpophalangeal joints are hyperextended while her 4th and 5th interphalangeal joints are flexed. Introduction Lesions to different nerves of the upper extremity will lead to specific hand distortions ulnar claw hand hand of benediction Klumpke total claw hand Relevant anatomy muscles lumbricals innervation 2nd/3rd digit lumbricals innervated by median nerve 4th/5th digit lumbricals innervated by ulnar nerve actions metacarpophalangeal (MCP) joint flexion proximal interphalangeal (PIP) and distal interphalangeal (DIP) joint extension extensor digitorum communis (EDC) innervation posterior interosseous nerve (branch of the radial nerve) actions finger extension flexor digitorum superficialis (FDS) innervation anterior interosseous nerve actions PIP flexion flexor digitorum profundus (FDP) innervation 2nd/3rd digits innervated by anterior interosseous nerve (branch of the median nerve) 4th/5th digits innervated by ulnar nerve actions DIP flexion dorsal and palmar interossei innervation ulnar nerve actions dorsal interossei abduct the fingers palmar interossei adduct the fingers thenar eminence musculature muscles flexor pollicis brevis abductor pollicis brevis opponens pollicis innervation recurrent branch of median nerve flexor pollicis brevis also receives its innervation from the ulnar nerve actions thumb flexion, abduction, and opposition Ulnar Claw Hand Physical exam 4th and 5th MCP joints are extended 4th and 5th PIP and DIP joints are flexed weakness in finger abduction and adduction patient is able to make a fist but is not able to completely open their 4th and 5th digits Pathoanatomy nerve involved distal ulnar nerve (at the wrist) muscles involved weakened 4th and 5th lumbricals weakened dorsal and palmar interossei Hand of Benediction Physical exam 2nd and 3rd MCP, PIP, and DIP joints are extended weakness in thumb abduction and opposition patient cannot make a fist due to inability to flex 2nd and 3rd digits Pathoanatomy nerve involved median nerve at the forearm or elbow muscles involved weakened 2nd and 3rd lumbricals weakened FDP to 2nd and 3rd digits weakened thenar musculature Klumpke Total Claw Hand Physical exam MCP joints are hyperextended PIP and DIP joints are flexed wrist is hyperextended weakness in thumb abduction and opposition forearm is supinated Pathoanatomy nerve involved lower trunk of the brachial plexus (C8/T1) muscles involved all intrinsic muscles of the hand lumbricals dorsal and palmar interossei thenar eminence wrist flexors forearm pronators