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

Functional Anatomy and Biomechanics of the Wrist and Hand Flashcards

1
Q

Introduction

A
  • 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.
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2
Q

Radiocarpal Joint (RC)

A
  • 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
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3
Q

Osteokinematics at RC Joint

A
  • 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
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4
Q

Arthrokinematics in RC Joint

A
  • 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
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5
Q

Carpal Joints

A
  • 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
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6
Q

Osteokinematics at Carpal Joint

A
  • 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
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7
Q

Arthrokinematics in Carpal Joints

A
  • 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
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8
Q

Carpal Tunnel

A
  • 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
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9
Q

Ligaments in the Wrist-Extrinsic Ligaments

A
  • dorsal radiocarpal ligaments
  • radial collateral ligaments
  • palmar radiocarpal ligaments: radiocapitate, radiolunate, radioscapholunate
  • ulnocarpal complex: articular disc, ulnar collateral ligament, palmar ulnocarpal ligament
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10
Q

Ligaments in the Wrist-Intrinsic

A
  • short ligaments
  • intermediate ligaments: lunotriquetral, scapholunate, scaphotrapezial
  • long ligaments: palmar intercarpal (lateral and medial), dorsal intercarpal
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11
Q

Hand

A
  • digital creases: distal, middle, proximal
  • palmar creases: distal, proximal, thenar
  • wrist creases: distal, proximal
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12
Q

Arches of the Hand

A
  • 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
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13
Q

Carpometacarpal Joints

A
  • 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
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14
Q

Osteokinematics at CMC Joints

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

Arthrokinematics in CMC Joints: Thumb

A
  • 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
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16
Q

Metacarpophalangeal Joints

A
  • 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
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17
Q

Osteokinematics at MCP Joints

A
  • 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
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18
Q

Arthrokinematics in 1st MCP Joint

A
  • joint orientation: metacarpals-inferior, anterior, lateral; phalanges: superior, posterior, medial
  • concave joint surface: phalanx
  • loose-pack: slight flexion
  • close-pack: full extension
19
Q

Arthrokinematics in MCP Joints 2-5

A
  • joint orientation: metacarpals-inferior, phalanges-superior
  • concave joint surface: phalanx
  • loose-pack position: slight flexion and slight ulnar deviation
  • close-pack position: full flexion
20
Q

Interphalangeal Joints

A
  • 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
21
Q

Osteokinematics at IP Joints

A

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

22
Q

Arthrokinematics at IP Joints

A
  • joint orientation: proximal phalanx-inferior, distal phalanx-superior
  • concave joint surface: distal phalanx
  • loose-pack position: slight flexion
  • close-pack position: full extension
23
Q

Functional Positions for Wrist and Hand

A
  • 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
24
Q

Innervation in Wrist and Hand

A
  • supplied by brachial plexus

- many hand conditions related to innervation

25
Q

Muscular Function in Wrist and Hand

A

-based in forearms and within hands themselves

26
Q

Wrist Extensors

A
  • 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
27
Q

Wrist Flexors

A
  • 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)
28
Q

Radial Deviators

A
  • ECRL
  • ECRB
  • EPL
  • EPB
  • FCR
  • abductor pollicis longus
  • FPL
29
Q

Ulnar Deviators

A
  • ECU

- FCU

30
Q

Extrinsic Hand Muscles

A
  • 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
31
Q

Extrinsic Flexors of the Fingers

A
  • includes: flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus
  • common origin
  • profundus is inserted into distal phalanx
  • superficialis is inserted into middle phalanx
  • FPL is inserted into distal phalanx
32
Q

Fibrous Digital Sheaths

A
  • have bands of tissues called flexor pulleys
  • lined with synovial membrane
  • extend for distal palmar crease to DIP
  • contribute to: active insufficiency (mm cross joint fibers cross so much that you can’t get max strength-fist with arm in neutral vs with wrist flexed); passive insufficiency (lengthen something and can’t produce as much force)
33
Q

Extrinsic Extensors of the Fingers

A
  • includes: extensor digitorum communis, extensor indicis, extensor digiti minimi
  • common origin (except EI)
  • extensor mechanism
34
Q

Extrinsic Extensor of Thumb

A
  • EPL, EPB, AbPL
  • pass wrist joint (help with radial deviation)
  • EPL can adduct the thumb
35
Q

Strength of Hand and Fingers

A
  • muscles in area act in many ways: co-contraction, neutralize, stabilize
  • flexors 2x the strength of the extensors
  • strength and strain affected by wrist position
  • neutral wrist position is generally safest wrist position: minimizes strain in region
36
Q

Grips

A
  • grip: all digits used
  • power grip: holding a hammer etc
  • precision grip: holding an egg
  • power pinch (key pinch): holding a key
  • precision pinch: holding a pin
  • hook grip: holding a suitcase (no thumb involvement)
37
Q

Therapeutic Exercise for Wrist and Hand

A
  • complete isolation of specific muscle very difficult
  • because forearm and hand mm work in combination functionally
  • stretching exercise, manual resistance, isotonic resistance commonly used in rehab
  • modify, modify, modify the 3 most important words in therapeutic exercise prescription
38
Q

Select Injuries in the Wrist and Hand

A
  • many wrist and hand injuries seen clinically MOI typically traumatic event, repetitive activity, or combination
  • give consideration to MOI in rehabilitation: can pt return to demand of high tensile load? is mm endurance a factor? etc
39
Q

Colles Fracture

A
  • most common wrist fracture
  • includes a dorsal displacement of distal radial
  • FOOSH is typical MOI (fall on outstretched hand)
  • postmenopausal women are highly susceptible-plus fx hip requires walker with forearm support
  • distal edema and mal-union are associated problems: dinner fork deformity results in permanent loss of full wrist flexion and ulnar deviation
40
Q

Scaphoid (Navicular) Fracture

A
  • carpal fractures occur 1/10th as often as distal radius fractures: of these 60-70% occur at the scaphoid
  • FOOSH with hand in supination is typical MOI-FOOSH in pronation is more common
  • diagnosis often based on clinical signs of local pain, edema, and little resolution of symptoms: fx often does not show on x-ray for weeks
  • high risk of malunion increases if not immobilized: thus, until ruled out, treat all tenderness at snuffbox as fx
41
Q

Boxer’s Fracture

A
  • fracture of 5th MC
  • often injured in fights
  • 5th ray more mobile than 2nd and 3rd: allows necessary mobility for cupping hand
  • usually casted after closed reduction but may need ORIF (open reduction internal fixation)
42
Q

Mallet Finger

A
  • aka baseball finger
  • caused by injury to extensor: long extensor tendon avulsed from base of phalanx
  • rx usually includes splinting for 6-8 weeks: positioned so DIP in extension or hyperextension, PIP in flexion
  • start AROM after splint removed
  • best if avulsion rather than injury solely to ligament-bone heals better than ligament
43
Q

Carpal Tunnel Syndrome

A
  • compression of median nerve as it passes thru carpal tunnel
  • carpal bones dorsal, transverse carpal ligament palmar
  • describes mini compartment syndrome with axonal damage
  • associated with prolonged hand usage
  • typically slow onset
  • typically affects women 40-60 yo more than men
  • usually dominant hand but bilateral is common
  • may have motor and sensory symptoms
  • anterior dislocation of lunate may cause CTS-quicker onset of sx
44
Q

De Quervain’s Tenosynovitis

A
  • irritation of tendon and its surrounding synovial sheath
  • affects common sheath of tendon shared by abductor pollicis longus (APL) and extensor pollicis brevis (EPB)
  • while sites and tissues are different, this is similar to CTS in terms of sheath irritation
  • common dysfunction in pts using thumb for repetitive pinching, wringing, and grasping motions with simultaneous wrist extension
  • middle age women most often affected

DPT 726: Orthopaedic Foundations (14 decks)

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