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Wrist & Hand I Notes The wrist joint is the articulation of the radius (on the thumb side of the wrist) with the proximal row of carpal bones (mostly the scaphoid and lunate) and the ulna and ulnar disc with the lunate and triquetrum. The wrist also includes the proximal row of carpals (scaphoid, lunate, triquetrum) with the distal row of carpals (trapezium, trapezoid, capitate, hamate). It is synovial joint, specific classification being an ellipsoid joint. The movements possible are at two axes and are flexion/extension and ab/adduction. Abduction and adduction are more commonly referred to as radial deviation (abduction) and ulnar deviation (adduction). As usual, make sure to review the bones on either the A.D.A.M. CD or in the text. Joint wrist: Classification synovial: ellipsoid joint Movements Possible & Comments flexion/extension (s-s axis/sagittal plane) abduction/adduction (front-to-back axis/frontal plane) (1) distal radius and ulna with proximal row of carpals and (2) proximal with distal row of carpals Lecture Slides Left Distal Humerus - Anterior View A - Medial epicondyle B - Trochlea C - Capitulum D - Lateral Epicondyle The wrist (and finger) flexors generally arise at least in part from the medial epicondyle; the extensor arise from the lateral epicondyle. Flexor Carpi Radialis (FCR, red), Palmaris longus (PL, yellow), Flexor Carpi Ulnaris (FCU, green) Prox Attachment: medial epicondyle Distal Attachment: FCR, base of 2nd and 3rd metacarpals; PL, palmar aponeurosis; FCU, pisiform bone Action: Together they flex the wrist; FCR with ECRL & B radially deviate; FCU with ECU ulnarly deviates Innervation: FCR - Median n. (C6, 7); FCU - Ulnar n. (C8, T1) Extensor Carpi Radialis Longus (ECRL, red) and Brevis (ECRB, blue); Extensor Carpi Ulnaris (ECU, yellow) Prox Attachment: lateral epicondyle Distal Attachment: ECRL & ECRB, bases of 2nd and 3rd metacarpals; ECU, base of 5th metacarpal Action: Together they extend the wrist; ECRL & B with FCR radially deviate; ECU with FCU ulnarly deviates Innervation: Radial n. (ECRL & ECRB C6, 7; ECU C7, 8) Lab Pics Anterior view of supinated right forearm; hand is inferior: Flexor Carpi Radialis (FCR, to your left), Flexor Carpi Ulnaris (FCU, to your right) Both are anterior to the wrist side-to-side axis for wrist flexion/extension so function as wrist flexors. Axis for ulnar/radial deviation is a front-to-back axis (as are all axes for abduction/adduction) and is pictured in green. Neither FCR or FCU travel through the axis so both function in deviation. FCR travels to the radial side of the axis so radially deviates the hand at the wrist joint. FCU travels to the ulnar side and is an ulnar deviator. Posterior view of pronated right forearm; hand is superior: Extensor Carpi Radialis Longus & Brevis (ECRL & ECRB, to your left), Extensor Carpi Ulnaris (ECU, to your right) All three are posteriorr to the wrist side-to-side axis for wrist flexion/extension and function as wrist extensors. Axis for ulnar/radial deviation is a front-to-back axis and is pictured in green. Neither ECRL or ECU travel through the axis, but ECRB is very close to the axis in this example. ECRL and ECU are knwon to be good deviators; ECRB is a poor deviator. ECRL travels to the radial side of the axis so radially deviates the hand at the wrist joint. ECU travels to the ulnar side and is an ulnar deviator.