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.
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
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
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
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
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
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
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
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
10
Q
Ligaments in the Wrist-Intrinsic
A
- short ligaments
- intermediate ligaments: lunotriquetral, scapholunate, scaphotrapezial
- long ligaments: palmar intercarpal (lateral and medial), dorsal intercarpal
11
Q
Hand
A
- digital creases: distal, middle, proximal
- palmar creases: distal, proximal, thenar
- wrist creases: distal, proximal
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
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
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*
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
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
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
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
Muscular Function in Wrist and Hand
-based in forearms and within hands themselves
26
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
27
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)
28
Radial Deviators
- ECRL
- ECRB
- EPL
- EPB
- FCR
- abductor pollicis longus
- FPL
29
Ulnar Deviators
- ECU
| - FCU
30
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
31
Extrinsic Flexors of the Fingers
- 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
Fibrous Digital Sheaths
- 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
Extrinsic Extensors of the Fingers
- includes: extensor digitorum communis, extensor indicis, extensor digiti minimi
- common origin (except EI)
- extensor mechanism
34
Extrinsic Extensor of Thumb
- EPL, EPB, AbPL
- pass wrist joint (help with radial deviation)
- EPL can adduct the thumb
35
Strength of Hand and Fingers
- 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
Grips
- 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
Therapeutic Exercise for Wrist and Hand
- 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
Select Injuries in the Wrist and Hand
- 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
Colles Fracture
- 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
Scaphoid (Navicular) Fracture
- 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
Boxer's Fracture
- 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
Mallet Finger
- 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
Carpal Tunnel Syndrome
- 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
De Quervain's Tenosynovitis
- 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
