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chapter 21. Wrist and Hand. Importance of the Hand. The hand is extremely complex and requires fine balance of all structures to function properly. Finger and hand injuries can be among the most devastating if not well cared for because we use our hands daily for hundreds of activities.
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chapter21 Wrist and Hand
Importance of the Hand • The hand is extremely complex and requires fine balance of all structures to function properly. • Finger and hand injuries can be among the most devastating if not well cared for because we use our hands daily for hundreds of activities.
Complexity of the Hand • 29 bones • 30+ tendinous insertions • Complex neurological system • 25% of the body’s pacinian corpuscles’ sensory endings are in the hands • 9 muscles in thumb; 7 in index finger • #1 and #2: dexterity activities • #3, #4, and #5: grasping activities
Skeletal Structure • Structures must maintain flexibility and strength to maintain adaptability. • Wrist joint: Concave radius joins with convex proximal carpal row.
Wrist Motions • Flexion • Extension • Abduction: radial deviation or radial flexion • Adduction: ulnar deviation or ulnar flexion • Combined motions: circumduction
Joints • Intercarpal joints: held in place by ligaments • Carpometacarpal joints: permit flexion, extension, abduction, adduction of metacarpals (MC) • Thumb, 4th, 5th MC: rotate to provide opposition • Metacarpophalangeal (MCP), interphalangeal (IP; proximal, distal [PIP, DIP]) joints: convex proximal segment, concave distal segment of each joint
Fascia of the Hand • Palmar fascia • Superficial = extension of transverse carpal ligament and palmaris longus tendon; goes to fingers • Deep = floor from thenar to hypothenar; serves to cushion and protect hand and maintain hand’s concavity • Dorsal fascia: in two layers but less dense
Tendon Sheaths and Pulleys • Extensor tendon sheaths are limited to the wrist area (extensor retinaculum at wrist). • An elaborate pulley system holds finger flexor tendons in place.
Tendons and Muscles • 20 extrinsic. • 19 intrinsic (#4 to #1, #3 to #5). • Extensor tendons are attached to proximal phalanx by sagittal bands on volar plate. • Beyond MCP joints, extensor tendons split into three segments: one attaches at middle phalanx and two converge and attach at distal phalanx. (continued)
Dorsal Soft-Tissue Zones • I and II: mallet or swan neck deformities • III and IV: boutonniere deformity • V and VI: adhesions of tendons and extensor hood • VII: adhesions of synovial sheaths, retinaculum • See figure 21.3b.
Tendons and Muscles • Flexor digitorum sublimis (FDS) splits and attaches at middle phalanx to flex PIP joint. • Flexor digitorum profundus (FDP) attaches to distal phalanx and flexes DIP joint. • FDS tendons have separate muscle bellies; FDP does not, so distal finger movement cannot be isolated.
Palmar Surface of the Hand Zones • I: Ruptures; poor tendon gliding, contracture, repair failures • II: Adhesions of tendons and sheaths • III: Intrinsic muscle adhesions • IV: Tendon adhesions • V: Tendon sheath adhesions • See figure 21.4b
Tendons and Muscles • Extrinsic muscles: gross motor activity • Intrinsic muscles: fine motor activity • Lumbricals originate on flexor tendons in palm and insert on extensor tendons to flex MCPs and extend IPs. • Dorsal and palmar interossei muscles are responsible for finger abduction and adduction.
Volar surface Thick Underlying fascial attachments Inelastic Hairless Ridges for grasping Dorsal surface Elastic Mobile Thinner Loose Pliable Must stretch 1 in. for fingers to close Skin of Hand
Edema in Hand • Frequently accumulates in dorsum. • Can lead to contractures. • Excessive swelling on dorsum can cause hand arches to collapse anteriorly and adduct the thumb. • Finger range of motion (ROM) can be impaired. • Edema causes reduced mobility and function of the hand in short term and in long term if fibrous formations occur.
Treating Hand Edema • Must reduce early edema • Measured by circumferential gauge or string wrapped around finger • Use of elevation, ice, compression, other modalities • See figure 21.5
Tendon Excursion • Inhibition of normal tendon gliding can inhibit normal hand function. • Repaired extensor tendon excursion should be limited to 5 mm during healing; exact degrees of motion vary from finger to finger. • There are implications for splinting and motion limitations.
Power Grips • Power grips = 20% 9 (see figure 21.55) • Fist • Hook • Cylinder • Spherical • Ulnar hand is used. Thumb opposes other fingers. • Fingers flex and rotate and move into ulnar deviation. Fingers point toward thenar eminence.
Prehensile Grips • Intricate tasks = 80% of time • Digital prehension pinch • Lateral prehension pinch • Tip-to-tip pinch • Fingers: flexed and abducted at MCP • Radial digits used
Splinting • Purposes: prevent damage or maintain or improve balance; based on three-point pressure system • Static splints: no moving parts; used to prevent movement, support and protect hand, maintain motion • Dynamic splints: used to gain motion or guide or assist movement
Splint Precautions • Avoid friction and pressure: Fit should be firm yet comfortable. • Check periodically for skin breakdown or redness; pad as needed. • Additional padding may change force of splint. • Adjust as needed as patient’s condition changes. • Take care over bony prominences.
Soft-Tissue Mobilization • Trigger points: • Extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), ECR (rarely has active trigger points) • Flexor carpi radialis (FCR), flexor carpi ulnaris (FCU) • Adductor pollicis • Palmar fascia release
