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Wrist Anatomy

palmar wrist anatomy

Carpal Ossification Sequence

carpal-tunnel-anatomy

 

 

Muscles of the Hand and Wrist

Muscle Innervation Origin Insertion Action Nerve Root
Thenar Muscles          
Abductor pollicis brevis (APB) median Scaphoid, trapezoid base of proximal phalanx, radial side abduct thumb  C8, T1
Opponens pollicis median trapezium thumb metacarpal abduct, flex, med. Rotation  C8, T1
Flexor pollicis brevis (FPB) median(superficial head), ulnar(deep head) trapezium, capitate base of proximal phalanx, radial side flex MCP  C7, C8
Adductor pollicis Ulnar capitate, 2nd/3rd metacarpals base of proximal phalanx, ulnar side Adduct thumb  C8, T1
Hypothenar Muscles          
Palmaris Brevis (PB) ulnar TCL, palmar aponeurosis Ulnar palm Retract skin  
Abductor dibiti minimi ulnar pisiform base of proximal phalanx, ulnar side abduct small finger  C8, T1
Flexor digiti minimi brevis(FDMB) Ulnar hamate, TCL base of proximal phalanx, ulnar side flex MCP  C8, T1
Opponens digiti minimi(ODM) Ulnar hamate, TCL small finger metacarpal abduct, flex, lat rotation  C8, T1
Intrisinsic Muscles          
Lumbricals median, ulnar(ulnar two) flexor digitorum profundus(FDP) lateral bands(radial) extend PIP  
Dorsal interosseous(DIO)(DAB) Ulnar adjacent metacarpals proximal phalanx base/extensor apparatus abduct, flex MCP  C8, T1
Volar interosseous(VIO) Ulnar adjacent metacarpals proximal phalanx base/extensor apparatus Adduct, flex MCP  C8, T1

 

Pronator Quadratus

  • Johnson RK. Stabilization of the distal ulna by transfer of the pronator quadratus origin. Clin Orthop Relat Res. 1992;275:130-2.
  • Stuart PR. Pronator quadratus revisited. J Hand Surg [Br]. 1996;21:714-22.
  • Johnson RK, Shrewsbury MM. The pronator quadratus in motions and in stabilization of the radius and ulna at the distal radioulnar joint. J Hand Surg [Am]. 1976;1:205-9.

Extensor Compartment Contents and Patholigc Conditions

  1. 1 APL, EPB DeQuervain's Tenosynovitis
    2 ECRB, ECRL Intersection Syndrome
    3 EPL Rupture at Lister's Tubercle
    4 EDC, EIP Extensor Tenosynovitis
    5 EDM Rupture (RA)
    6 ECU Extensor Carpi Ulnaris Subluxation

Posterior Interosseous Nerve (PIN)

Transverse Carpal Ligament

  • Radial attachment: tuberosity of the scaphoid and the trapezium
  • Ulnar attachment: pisiform and hook of the hamate

Carpal Tunnel

  • Boundaries: volarly=transverse carpal ligament; Radially=scaphoid tuberosity and trapezium; Ulnarly=pisiform and the hook of the hamate; Dorsally=carpal bones and the deep volar radiocarpal ligament and volar interosseous ligaments
  • Contents: median nerve, 4 flexor digitorum superficialis tendons, 4 flexor digitorum profundus tendons and flexor pollicis longus

Motor branch of median nerve

  • has many variations; can branch off extraligamentous, subligamentous, transligamentous etc. (Lanz U, J Hand Surg 1977;2:44)

Palmar Cutaneous Nerve

  • typically arises from the radial side of the median nerve 5cm proximal to the radial syloid and passes distally just under the FCR tendon. It passes through the transverse carpal ligament radial to the longitudinal axis of the ring finger to supply sensation to the palm. (Hobbs R, J Hand Surg 1990;15A:38) Injury can lead to painful neuroma.

Sensory Branch of Radial Nerve

  • becomes subcutaneous 5-10cm proximal to radial styloid in the interval between brachioradialis and ECRL. It bifurcates before wrist.
  • Dorsal branch 1-3cm radial to Listers. Supplies 1st and 2nd web spaces.
  • Palmar branch passes within 2cm of 1st dorsal compartment provides sensation to dorsolateral thumb after passing directly over EPL.
  • See also Wartenberg's Syndrome.

Palmar Cutaneous Branch of the Median nerve

  • arises from the Median nerve @4-6cm proximal to the volar wrist crease and travels between the FCR and median nerve. Supplies sensation to the thenar area.

Dorsal Cutaneous Branch of Ulnar Nerve

  • arises deep to FCU, becomes SQ 5cm from pisiform-has multiple branches

Kaplan's Cardinal Line

  • a guideline for locating the recurrent motor branch of the median nerve. Recurrent branch is located at the intersection of a line drawn along the ulnar border of the middle finger, with a line drawn between the radial aspect of the thumb web space in abdcuction and the pisiform.

Guyons Canal

  • approximately 4cm long beginning to the proximal extent fo the transvers carpal ligament and ending at the aponeurotic arch of the hypothenar muscles.
  • Ulnar nerve bifurcates into the superficial and deep branches within Guyons canal.
  • Ulnar artery is radial to the ulnar nerve.

 

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