Chapter 4 - wrist and hand

• Carpus (wrist)


  Proximal region of the hand consisting of 8 small bones

  
• Intercarpal joints


  Articulations among carpal bones
• Carpal bones


  • Scaphoid
  • Lunate
  • Triquetrum
  • Pisiform
  • Trapezium
  • Trapezoid
  • Capitate
  • Hamate

  
• In about 70% of carpal fractures, only the scaphoid is broken
• Force of a fall on an outstretched hand

  Transmitted from the capitate through the scaphoid to the radius
• Carpal tunnel


  Concave space formed by the pisiform and hamate (on the ulnar side), and the scaphoid and trapezium (on the radial side), and flexor retinaculum
• The long flexor tendons of the digits and thumb and the median nerve pass through the carpal tunnel

  
• Carpal tunnel syndrome


  Narrowing of the carpal tunnel, due to such factors as inflammation
• Metacarpus / metacarpal bones


  Intermediate region of the hand consisting of 5 bones

  
• Phalanges


  Bones of the digits, 14 in each hand

  
• Digits


  • Thumb
  • Index finger
  • Middle finger
  • Ring finger
  • Little finger
• Phalanx


  Single bone of a digit
• Parts of a phalanx

  • Proximal base
  • Intermediate shaft (body)
  • Distal head
• The thumb (pollex) has two phalanges
• Finger joints


  Carpometacarpal joint
• Muscles that move the wrist, hand and digits

  • Anterior (flexor) compartment muscles
  • Posterior (extensor) compartment muscles

  
• Anterior (flexor) compartment muscles


  • Superficial
  • Deep

  
• Superficial anterior (flexor) compartment muscles

  • Flexor carpi radialis
  • Palmaris longus
  • Flexor carpi ulnaris
  • Flexor digitorum superficialis

  
• Flexor carpi radialis


  Originates from medial epicondyle of humerus, inserts on 2nd and 3rd metacarpal, flexes and radially deviates the wrist, innervated by median nerve

  
• Flexor carpi ulnaris


  Originates from medial epicondyle of humerus, inserts on flexor retinaculum and palmar aponeurosis, weakly flexes the wrist, innervated by ulnar nerve

  
• Palmaris longus


  Originates from medial epicondyle of humerus and superior border of ulna, inserts on pisiform, hamate, and base of 5th metacarpal, flexes and ulnarly deviates the wrist, innervated by median nerve
• Palmaris longus is missing in about 10% of individuals
• Flexor digitorum superficialis


  Originates from medial epicondyle of humerus, coronoid process of ulna, anterior surface of radius, inserts on middle phalanx of each finger, flexes phalanx of each finger at PIP joint, MCP joint, and wrist joint, innervated by median nerve

  
• Flexor pollicis longus


  Originates from anterior surface of radius and interosseous membrane, inserts on base of distal phalanx of thumb, flexes distal phalanx of thumb at IP joint, innervated by median nerve

  
• Flexor digitorum profundus


  Originates from anterior medial surface of body of ulna, inserts on base of distal phalanx of each finger, flexes distal and middle phalanges of each finger at IP joints and proximal phalanx at MCP joints, and wrist, innervated by median and ulnar nerve

  
• Extensor carpi radialis longus


  Originates from lateral supracondylar ridge of humerus, inserts on 2nd metacarpal, extends and abducts hand at wrist joint, innervated by radial nerve

  
• Extensor carpi radialis brevis


  Originates from lateral epicondyle of humerus, inserts on 3rd metacarpal, extends and abducts hand at wrist joint, innervated by radial nerve

  
• Extensor digitorum


  Originates from lateral epicondyle of humerus, inserts on distal and middle phalanges of each finger, extends distal and middle phalanges of each finger at IP joints, proximal phalanges at MCP joints, and wrist, innervated by radial nerve

  
• Extensor digiti minimi


  Originates from lateral epicondyle of humerus, inserts on tendon of extensor digitorum on fifth phalanx, extends proximal phalanx of little finger at MCP joint and extend wrist joint, innervated by deep radial nerve

  
• Extensor carpi ulnaris


  Originates from lateral epicondyle of humerus and posterior border of ulna, inserts on fifth metacarpal, extends and ulna deviates the wrist, innervated by deep radial nerve
• Abductor pollicis longus


  Originates from posterior surface of middle of radius and ulna and interosseous membrane, inserts on first metacarpal, abducts and extends thumb at CMC joints and abducts hand at wrist joint, innervated by deep radial nerve

  
• Extensor pollicis brevis


  Originates from posterior surface of middle of radius and interosseous membrane, inserts on base of proximal phalanx of thumb, extends proximal phalanx of thumb at MCPJ, 1st MCP of thumb at CMCJ and wrist, innervated by deep radial nerve
• Extensor pollicis longus


  Originates from posterior surface of middle of radius and interosseous membrane, inserts on base of distal phalanx of thumb, extends distal phalanx of thumb at IPJ, 1st MCP of thumb at CMCJ and wrist, innervated by deep radial nerve
• Extensor indicis


  Originates from posterior surface of ulna, inserts on tendon extensor, digitorum of index finger, extends distal and middle phalanges of index finger at IPJ, proximal phalanx of index finger at MCPJ, and wrist, innervated by deep radial nerve
• Intrinsic muscles of the hand

  Produce the weak but intricate and precise movements of the digits, divided into thenar, hypothenar, and intermediate groups
• Thenar muscles


  • Abductor pollicis brevis
  • Opponens pollicis
  • Flexor pollicis brevis
  • Adductor pollicis

  
• Abductor pollicis brevis


  Originates from flexor retinaculum, scaphoid, and trapezium, inserts on lateral side of proximal phalanx of thumb, abducts thumb at CMC joint, innervated by median nerve

  
• Opponens pollicis


  Originates from flexor retinaculum, and trapezium, inserts on lateral side of 1st metacarpal of thumb, opposes thumb at CMCJ, innervated by median nerve

  
• Flexor pollicis brevis


  Originates from flexor retinaculum, trapezium, capitate, trapezoid, inserts on lateral side of proximal phalanx of thumb, flexes thumb at CMCJ and MCPJ, innervated by ulnar nerve

  
• Adductor pollicis


  Originates from capitate and 2nd and 3rd metacarpals; transverse head; 3rd metacarpal, inserts on medial side of proximal phalanx of thumb, adducts thumb at CMCJ and MCPJ, innervated by ulnar nerve