8 - Wrist

8 - Wrist - Foundations of Occupation Foundations of...

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Unformatted text preview: Foundations of Occupation Foundations of Occupation Kinesiology The Wrist Lecture 8 Summer 2010 Overview Overview • • • • • • Introduction: The Wrist Complex Joints and Soft Tissue Structures Range of Motion of Wrist Complex Dynamics of Motion at Wrist Complex Wrist Musculature Carpal Tunnel Syndrome “Man, through the use of his hands, as energized by mind and will, can influence the state of his own health” ­Mary Reilly A Video to Set the Stage… A Video to Set the Stage… • Hands in Motion... Function of Wrist Complex Function of Wrist Complex • Major contribution: – control of length tension relationships in the hand muscles – permit fine adjustments of grip • Loss of function in wrist cannot be replaced by compensatory movements of shoulder, elbow, or forearm. • Two compound joints : radiocarpal and midcarpal ­ collectively called the wrist complex Joints of the Wrist and Hand Joints of the Wrist and Hand • Radius • Ulna • Carpals: The Wrist Complex The Wrist Complex Scaphoid, Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate Hamate “Some lovers try positions that ome overs ry ositions hat they can’t handle” hey an’t • • Radioulnar disc Joints of Wrist Complex Joints of Wrist Complex • Radiocarpal Joint ­ formed by radius, radioulnar disc proximally and scaphoid, lunate, and triquetrum distally. – Proximal Carpal Row: scaphoid, lunate, triquetrum, and pisiform. – Pisiform is a sesamoid bone ­ increasing the perpendicular distance from the point of application to the axis of rotation of the flexor carpi ulnaris (anatomical pulley) Joints of Wrist Complex (cont’d) Joints of Wrist Complex (cont’d) • Midcarpal Joint ­ consists of the articulation between the scaphoid, lunate, and triquetrum proximally and trapezium, trapezoid, capitate, and hamate distally (distal carpal row) . – Functional joint ­ – Condyloid joint with two degrees of freedom. – Favors extension over flexion, and radial vs. ulnar deviation Wrist Joints Wrist Joints Soft Tissue Structures Soft Tissue Structures • Joint Capsules – Radiocarpal joint enclosed by strong but somewhat loose capsule. – Midcarpal joint has a joint capsule continuous with each carpal articulation. • Many Ligaments – provide support, application of passive forces • Essentially no muscular attachments on proximal carpal row Ligaments of the Wrist Ligaments of the Wrist Range of Motion of Range of Motion of Radiocarpal and Midcarpal Joints • Flexion • Extenson Extenson • Radial deviation Radial • Ulnar deviation Ulnar • Circumduction Circumduction Principles of Motion of Principles of Motion of Wrist Complex • Movement occurs at both proximal and distal carpal bones – Wrist flexion ­ proximal carpals slide dorsally on the distal radius and radioulnar disc – Radial deviation ­ proximal carpal bones slide ulnarly. • Both ligaments and bones serve to check movement • Carpal Rhythm Dynamics of Wrist Extension Dynamics of Wrist Extension • Movement initiated at the distal carpal row w/capitate at center • Involve movements which occur in the central column of the wrist (series of articulations among the radius, lunate, capitate, and 3rd metacarpal bone) • Wrist extension is based on synchronous convex­on­concave rotations at the radiocarpal & midcarpal joints • Extension occurs as the convex surface of the lunate rolls dorsally on the radius while simulataneously sliding palmarly. The head of the capitate rolls dorsally on the lunate & simultaneously slides in a palmar direction • During wrist extension, the dorsal radiocarpal ligaments become slackened and the palmar radiocarpal ligaments become taut • Full extension elongates the palmar radiocarpal ligaments, the palmar capsule, the wrist flexor muscles, and the finger flexor • Movement initiated at proximal carpal row. • Flexion occurs as the lunate begins to roll palmarly on the radius while simultaneously sliding dorsally. • The head of the capitate rolls palmarly on the lunate & simultaneously slides in a dorsal direction. • During wrist flexion, the palmar radiocarpal ligaments become slackened, and the dorsal radiocarpal ligaments become taut • Full wrist flexion elongates the dorsal radiocarpal ligaments, dorsal capsule, the wrist extensor muscles, and the finger extensor muscles • This creates approximately 0­85 degrees of flexion Dynamics of Wrist Flexion – Dynamics of Wrist Flexion – Reverse of Extension Dynamics of Ulnar Deviation Dynamics of Ulnar Deviation • Ulnar Deviation • At the radiocarpal joint: scaphoid, lunate & triquetrum roll ulnarly & slide (a significant distance) radially • At the midcarpal joint: capitate rolls ulnarly and slides slightly radially. Full range of ulnar deviation causes the triquetrum to contact the articular disc • Proximal row of carpals pushed against the styloid process of the radius because of the compression of the hamate against the triquetrum • Compression helps stabilize the wrist for activities requiring large gripping forces. Dynamics of Radial Deviation Dynamics of Radial Deviation • Radial Deviation • At the radiocarpal joint: scaphoid, lunate, & triquetrum roll radially & slide ulnarly • At the midcarpal joint: capitate rolls radially and slides ulnarly • Amount of radial deviation at the radiocarpal joint is limited because of the radial side of the carpus impinging against the styloid process of the radius • Most wrist radial deviation happens at the midcarpal joint (hamate & triquetrum separate by the end of full range). Carpal Rhythm Summary Carpal Rhythm Summary • Radial and ulnar deviation are both greatest when wrist is in neutral. • In wrist extension, carpals are in close­packed position so very little radial or ulnar deviation is possible. • In flexion, carpals are loose­packed and spread out so further movement of proximal carpal row cannot occur. Wrist Musculature Wrist Musculature Volar Dorsal • Palmaris Longus • Flexor Carpi Radialis (FCR) • Flexor Carpi Ulnaris (FCU) • Extensor Carpi Radialis Longus and Brevis • Extensor Carpi Ulnaris • Extensor Digitorum • Extensor Digiti Minimi • Extensor Indicis Abductor Pollicis Longus Extensor Pollicis Longus and Brevis • Flexor Digitorum Superficialis (FDS) • Flexor Digitorum Profundus (FDP) • • • Flexor Pollicis Longus (FPL) Flexor and Extensor Flexor and Extensor Retinaculum Cross Section of Wrist Cross Section of Wrist Wrist Flexors Wrist Flexors • All pass under the flexor retinaculum except Palmaris Longus. (distal transverse carpal ligament) • FCR, FCU are primary wrist flexors. (names tell you function) • These primary wrist flexors have proximal attachments on medial epicondyle of humerus through a common flexor tendon. • FCR, FCU ­ prime movers for wrist flexion, PL assists. • FCR ­ prime mover for radial deviation (pure wrist flexor) Wrist Extensors Wrist Extensors • Extensor retinaculum prevents bow stringing of long extensor tendons when hand is hyperextended at wrist joint. • ECRL, ECRB, ECU act directly on the wrist. • Proximally, each of these arise from a common extensor tendon attached to the lateral epicondyle of the humerus. • ECRL ­ prime mover for wrist extension, radial deviation; acting as a stabilizing synergist during forceful finger flexion. • ECRB ­ medial position (attachment at base of 3rd metacarpal) makes it most consistent extensor. Most important stabilizer during forceful finger flexion, stabilizing action of long finger flexors at wrist, avoiding active insufficiency. Also prime mover for radial deviation. • ECU ­ prime mover for wrist extension and ulnar deviation Synergistic Actions of the Wrist Muscles • Wrist Extension – • Wrist Flexion – – activation of radial and ulnar wrist extensors balances the wrist in extension. Deviations are cancelled out. – activation of radial and ulnar wrist flexors with cancellation of deviation. – activation of FCR and ECRL/ECRB with cancellation of flexion and extension. – FCU and ECU activated and flexion / extension cancelled out. • Radial Deviation – • Ulnar Deviation – Purpose of Carpal Tunnel is to protect the structures that pass through from compression and damage. (Median nerve and long finger flexors) Carpal Tunnel Carpal Tunnel Carpal Arch ­ formed by both rows of carpal bones, accentuated by the hook of the hamate and anterior extension of the trapezium Carpal Tunnel Carpal Tunnel Carpal Tunnel Syndrome Carpal Tunnel Syndrome • A repetitive motion disorder • Results in swelling and nerve compression – – – Painful movement Numbness Weakness ...
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