Functional Anatomy and Biomechanics of the Wrist and Hand Flashcards Preview

DPT 726: Orthopaedic Foundations > Functional Anatomy and Biomechanics of the Wrist and Hand > Flashcards

Flashcards in Functional Anatomy and Biomechanics of the Wrist and Hand Deck (44)
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-the wrist and hand complex has many articulations
-used primarily for manipulation activities: many stable but mobile segments, wide potential of interplay of wrist and finger positions
-also helps to express thru touch, art, etc.


Radiocarpal Joint (RC)

-ellipsoid joint
-2 degrees of freedom: flexion/extension, radial/ulnar deviation
-involves distal end of radius and the carpals
-primary articulation with lunate and scaphoid: lesser contact with triquetrium


Osteokinematics at RC Joint

-wrist motion comprised of motion at many joints-including radiocarpal joint
-typical gross ROM values:
-wrist flexion ~70-90
-wrist extension ~70-80
-radial deviation ~15-20
-ulnar deviation ~30-40


Arthrokinematics in RC Joint

-joint orientation: radius and ulna-inferior, anterior, medial; carpals-superior, posterior, lateral
-concave joint surface: radius and ulna
-loose-pack position: slight flexion and ulnar deviation
-close-pack position: full extension


Carpal Joints

-2 rows of 4 carpals (proximal and distal)
-proximal includes: scaphoid, lunate, triquetrum, pisiform
-distal: trapezium, trapezoid, capitate, hamate
-articulation between rows is known as midcarpal joint
-intercarpal joint describes articulation between 2 carpal bones
-carpal tunnel: concave transverse arch crossing the carpals: passage for flexor tendons and median nerve


Osteokinematics at Carpal Joint

-midcarpal joint accounts for ~60* of total wrist flexion: 40% is due to scaphoid and lunate moving on radius
-gross ROM for wrist flexion ~70-90*-at least 10-15* needed for most ADL, may be limited by soft tissue resistance of wrist/finger extensors
-extension also initiated at mid carpal joint-most common motion occurs at RC joint
-RC joint accounts ~60* of total wrist extension ROM; midcarpal joint accounts for additional ~30*
-switch due to scaphoid moving with proximal carpals during flexion and distal carpals during extension
-wrist extension ROM ~70-80* and about 35* is needed for ADLs
-radial and ulnar deviation: proximal row of carpals glide over distal row; RD prox moves toward ulna, UD distal moves away from ulna
-radial deviation ~15-20
-ulnar deviation ~30-40


Arthrokinematics in Carpal Joints

-proximal row is oriented inferiorly, distal row oriented superiorly
-concave joint surface varies depends on specific joint
-loose-pack is slight flexion and ulnar deviation
-close pack is full extension


Carpal Tunnel

-palmar side of carpal bones form a concavity
-transverse carpal ligaments arch over tunnel: between pisiform, hook of hamate, and tubercle of scaphoid, and trapezium
-median nerve and extrinsic fingers flexors pass through the tunnel


Ligaments in the Wrist-Extrinsic Ligaments

-dorsal radiocarpal ligaments
-radial collateral ligaments
-palmar radiocarpal ligaments: radiocapitate, radiolunate, radioscapholunate
-ulnocarpal complex: articular disc, ulnar collateral ligament, palmar ulnocarpal ligament


Ligaments in the Wrist-Intrinsic

-short ligaments
-intermediate ligaments: lunotriquetral, scapholunate, scaphotrapezial
-long ligaments: palmar intercarpal (lateral and medial), dorsal intercarpal



-digital creases: distal, middle, proximal
-palmar creases: distal, proximal, thenar
-wrist creases: distal, proximal


Arches of the Hand

-3 and all linked
-weaknesses in one arch weakens the others
-proximal transverse: carpal bones, rigid, immobile
-distal transverse: heads of metacarpals, mobile
-longitudinal: flexible, mobile


Carpometacarpal Joints

-connect carpals to fingers via metacarpals
-each metacarpal and phalanx aka a ray
-CMC allows most motion in thumb and lesser motion in hand
-1st CMC: saddle between trapezium and metacarpal, provides thum with most of its motion
-thumb can touch each finger (opposition): very important in all gripping and prehension tasks
-CMC offers little motion in the hand: 2nd and 3rd very restricted, as much as 10-30* of CMC flexion/extension available in 4th and 5th
-concave transverse arch across the metacarpals-facilitates gripping function of the hand


Osteokinematics at CMC Joints

-1st CMC 50-80* flexion/extension; 40-80* abduction/adduction; 10-15* rotation
-opposition can occur through ROM ~90*


Arthrokinematics in CMC Joints: Thumb

-joint orientation: trapezium-inferior, anterior, lateral; metacarpal-superior, posterior, medial
-concave joint surface: trapezium concave posterior to anterior, 1st MC concave lateral to medial
-loose-pack midway between flex/ext and abd/add
-close-pack position: full opposition
-abduction: convex on concave-palmar roll and dorsal glide
-adduction: convex on concave-dorsal roll and palmar glide
-flexion: concave on convex, medial roll and glide
-extension: concave on convex, lateral roll and glide


Metacarpophalangeal Joints

-MCP joints in fingers are condylar, allowing 2 DF: flexion/extension; abduction/adduction
-joints well-reinforced in fingers by dorsal hoods, palmar plates, collateral or deep transverse ligaments
-grip strength best with wrist in 20-30* extension-places finger flexors in best position to produce forces
-1st MCP is hinge joint, not connected to others via deep transverse ligaments


Osteokinematics at MCP Joints

-flexion ROM 70-90*: most in little finger and least in index
-extension ROM ~25*: affected by position of wrist
-abduction/adduction ROM ~20*: abduction limited when fingers flexed, restricted by increased tension on collateral ligaments
-ROM for 1st MCP: flexion 30-90*, extension ~15*


Arthrokinematics in 1st MCP Joint

-joint orientation: metacarpals-inferior, anterior, lateral; phalanges: superior, posterior, medial
-concave joint surface: phalanx
-loose-pack: slight flexion
-close-pack: full extension


Arthrokinematics in MCP Joints 2-5

-joint orientation: metacarpals-inferior, phalanges-superior
-concave joint surface: phalanx
-loose-pack position: slight flexion and slight ulnar deviation
-close-pack position: full flexion


Interphalangeal Joints

-all fingers have 3 segments 2 IP joints: PIP and DIP
-thumb has 2 segments and 1 IP
-ip are true hinge joints: reinforced laterally by collateral ligaments


Osteokinematics at IP Joints

-flexion: 110 at PIP, 50 at DIP and IP joint in thumb


Arthrokinematics at IP Joints

-joint orientation: proximal phalanx-inferior, distal phalanx-superior
-concave joint surface: distal phalanx
-loose-pack position: slight flexion
-close-pack position: full extension


Functional Positions for Wrist and Hand

-most ADLs require: 45-50* in sagittal plane and 20-25* in frontal plane
-when fused the wrist is often placed in 10-15* extension and 10* ulnar deviation


Innervation in Wrist and Hand

-supplied by brachial plexus
-many hand conditions related to innervation


Muscular Function in Wrist and Hand

-based in forearms and within hands themselves


Wrist Extensors

-primary: ECRL, ECRB, ECU
-secondary: extensor digitorum communis, extensor indicis, extensor digiti minimi, extensor pollicis longus
-common attachment at lateral epicondyle
-none attaches distally on the carpals
-enclosed by extensor retinaculum
-6 fibro-osseous tunnels: enclose tendons and sheaths


Wrist Flexors

-primary: FCR, FCU, palmaris longus
-secondary: FDP, FDS, FPL
-common attachment on medial epicondyle
-palmaris longus absent in 10* of population
-only flexor carpi ulnaris attaches to carpal bones (pisiform)


Radial Deviators

-abductor pollicis longus


Ulnar Deviators



Extrinsic Hand Muscles

-digit flexors: FDS, FDP, FPL
-finger extensors: EDC, EI, EDM
-thumb extensors: EPL, EPB, AbPL
-thenar eminence: opponens pollicis, AbPB, FPB
-hypothenar eminence: opponens digiti minimi, AbDM, FDM, palmaris brevis
-adductor pollicis
-4 lumbricals
-4 palmar and dorsal interossei