Wrist and Hand Anatomy

Bone Anatomy

• Scapoid• Lunate• Triquetrium• Pisiform• Trapeziod• Trapezium• Capitate• Hamate

Hand and Wrist Anatomy

• 14 phalanges– 2 sesamoid bones (thumb)

• 5 metacarpals• 8 carpal bones• Distal Radius– Forms small ulnar notch to accept the ulnar head– Radial styloid process

• Distal Ulna– Ulnar styloid process arises from medial surface– Ulnar head

Articulations

• Distal Radioulnar– Formed by ulnar head and ulnar notch– Allows 1 degree freedom of movement• Pronation/supination

– Radius glides around the ulna

• Radiocarpal joint– Reinforced by ligamentous thickening– Formed by distal radius articulating with scaphoid,

lunate and triangular fibrocartilage disk(TFCC)– Ellipsoid joint (2 degrees freedom)• Flexion/extension• Radial/ulnar deviation

• Intercarpal Joints– Palmar/dorsal/interosseous ligaments between

each carpal– Very little gliding

• Midcarpal Joints– Proximal/distal carpal row separated by a single

joint cavity with small fibrous projections connecting the rows

– Limited mobility in flex/ext, radial/ulnar deviation

• Carpometacarpal Joint (CMC)– MC1/trapezium– MC2/trapezoid– MC3/capitate– MC4and 5/hamate (forms 1 articulation)

• 1st CMC (thumb)– Saddle joint• 2 degrees of freedom(3)

– Flexion/extension– Abduction/adduction

• Accessory rotation– Allows for opposition

• 2-4 CMC– Plane/synovial joint– 1 degree freedom• Flexion/extension

• 5th CMC– 2 degree freedom• Flexion/extension• Abduction/adduction

• Metacarpophalangeal Joint (MCP)– Two degrees freedom of movement• Flexion/extension• Abduction/adduction

– Thumb can abduct at any point/fingers only when extended

– Collateral ligaments• Varus/valgus force

– When fingers are in flexion they tighten and limit abduction/adduction

• Interphalangeal Joint– One degree freedom of movement• Flexion/extension

– Collateral ligaments

Ligament Support

• Volar Carpal Ligaments– Volar Radiocarpal

Ligament• Three bands

– Volar Ulnocarpal Ligament

– Scapholunate Interosseous Ligament

– Lunotriquetral Ligament

Ligament Support

• Dorsal Carpal Ligaments– Dorsal Radiocarpal

Ligament– Dorsal Intercarpal

Ligament– Radial Collateral

Ligament– Ulnar Collateral

Ligament

Carpal Tunnel

• Fibro-osseous structure– Floor is proximal carpal bones– Roof is transverse carpal ligament

• Tunnel contains 10 structures– Median n., flexor pollicis longus tendon, 4 slips of flexor

digitorium superficialis, 4 flexor digitorium profundus

• Compression results in paresthesia 2-4 fingers and decrease grip

Hand

• Wrist flexors (median n.)– Superficial

• Flexor carpi radialis• Palmaris longus• Flexor carpi ulnaris• Flexor digitorium superficialis• Pronator teres

– Deep• Flexor digitorium profundus• Flexor pollicis longus• Pronator quadratus

• Palmar (intrinsic)– Thenar• Abductor pollicis brevis• Flexor pollicis brevis• Opponens Pollicis• Tendon FPL• Adductor pollicis

• Hypothenar– Abductor digiti minimi– Opponens digiti minimi– Flexor digiti minimi brevis

• Central– Tendons FDS/FDP

• Superficialis (PIP)• Profundus (DIP)

• Lumbricales– Radial side profundus tendon(extensor hood)

• Flex MP/ext PIP/DIP

• Palmar aponeurosis• Interossei– 4 palmar/4 dorsal

Extrinsic Hand Muscles

Extensor Indicis

• O– Dorsal surface lower ½ body

of ulna– Interosseus membrane

• I – Ulnar side of index finger’s

EDC tendon

• N– Radial (posterior interosseus)

• F– MCP and IP Ext of 2nd digit

Extensor Pollicis Longus

• O– Posterior 1/3 ulna– Interosseus membrane

• I– Posterior surface of base of

thumb distal phalanx

• N – Radial (posterior interosseus)

• F– CMC, MCP and IP Ext of 1st

digit

Extensor Pollicis Brevis

• O– Dorsal 2/3 of radius

• I– Dorsal surface of base of

proximal 1st phalanx

• N– Radial (posterior interosseus)

• F– CMC & MCP Ext of thumb– CMC ABD of thumb

Abductor Pollicis Longus

• O– Posterior distal 2/3 of ulna– Posterior middle 1/3 of radius– Interosseus membrane

• I– Radial side of base of 1st

metacarpal

• N– Radial (posterior interosseus)

• F– CMC ABD & Ext of thumb

Flexor Pollicis Longus

• O – Anterior middle ½ of radius– Interosseus membrane

• I – Palmar surface of base of

distal 1st phalanx

• N– Median (anterior interosseus)

• F– IP Flexion of thumb

Extensor Digiti Minimi

• O– Lateral epicondyle of

humerus• I– Extensor expansion of 5th

digit• N– Radial (posteior

interosseus)• F– MCP and IP extension of

5th digit

Flexor Digitorum Superficialis• O

– Medial epicondyle of humerus

– Coronoid process– Middle ½ anterior radius

• I– Four tendons separating into

two parts that insert into sides of bases of middle 2-5 phalanxes

• N– Median

• F– MCP flexion digits 2-5– PIP flexion digits 2-5

Flexor Digitorum Profundus

• O– Anteriomedial surface of ulna– Interosseus membrane

• I– Four tendons inserting into

distal phalanxes of digits 2-5

• N– Media 2-3 digits– Ulna 4-5 digits

• F– DIP flexion of 2-5 digits

Intrinsic Hand Muscles

Thenar Eminance

Abductor Pollicis Brevis

• O– Scaphoid tuberosity– Trapezium ridge– Transverse carpal ligament

• I– Lateral base f proximal 1st

phalanx

• N– Median

• F– CMC & MCP ABD of thumb

Flexor Pollicis Brevis• O

– Superficial head – trapezium– Deep head – trapezoid,

capitate and palmar ligaments of distal carpal bones

• I– Base of prximal 1st phalanx on

radial side– Extensor expansion

• N– Superficial – median– Deep – Ulnar

• F– CMC & MCP Flexion of thumb

Opponens Pollicis

• O– Trapezium– Transverse Carpal

Ligament• I– Radial side of 1st

metacarpal shaft• N– Median

• F– Opposition

Intrinsic Hand Muscles

Hypothenar Eminence

Abductor Digiti Minimi

• O– Pisiform

• I– Ulnar side base of 5th

proximal phalanx

• N– Ulnar

• F– MCP ABD of 5th digit

Opponen Digiti Minimi

• O– Hook of hamate– Transverse carpal ligament

• I– Ulnar border of entire 5th

metacarpal bone

• N– Ulnar

• F– MCP flexion & rotation of 5th

digit

Flexor Digiti Minimi

• O– Hamate bone– Transverse carpal

ligament• I– Ulnar side of proximal 5th

phalanx• N– Ulnar

• F– MCP Flexion of 5th digit

Other Intrinsic Hand Muscles

Adductor Pollicis• O

– Oblique Head• Capitate bone• Bases of 2-3 metacarpals

– Transverse Head• Proximal 2/3 of palmar

surface of 3rd metacarpal

• I– Ulnar side of base of 1st

proximal phalanx• N

– Ulnar• F

– CMC ADD of thumb

Palmar Interossei• O

– 1st – ulnar side base of 1st metacarpal bone

– 2nd – ulnar side of 2nd MC bone– 3rd – radial side of 4th MC bone– 4th – radia side of 5th MC bone

• I– Extensor expansion of 2,4 and

5th digits• N

– Ulnar• F

– ADD of 1st, 2nd, 4th and 5th digits toward midline of hand

Dorsal Interossei• O

– 1st lateral head – ulnar side of 1st metacarpal bone

– 1st medial head – radial side of 2nd metacarpal bone

– 2nd, 3rd, 4th space between metacarpal bones

• I– 1st – radial side 2nd proximal

phalanx– 2nd – radial side of 3rd

– 3rd – ilnar side of 3rd

– 4th – ulnar side of 4th

• N– Ulnar

• F– ABD of 2nd, 3rd, and 5th finger

from midline

Lumbricales

• O– Tendons of FDP

• I– Extensor expansion on dorsal

aspect of each digits radial side

• N– 1 and 2 – median– 3 and 4 – ulnar

• F– MCP flexion 2-5 digits– DIP & PIP ext 2-5 digits

Palmaris Brevis

• O– Flexor retinaculum

• I– Palmar surface skin on

ulnar side of hand• N– Ulnar

• F– Wrinkles skin of hand on

ulnar side

Cords Give off Branches!! (in axilla)

• Lateral Musculocutaneous

Median

• Medial Ulnar

• Posterior RadialAxillary

(thoracodorsal)(subscapular)

PUT IT ALL TOGETHER…...

pg 416

Innervation by Posterior Cord• Radial Nerve (largest branch)– Course: Through arm, around humerus, around lateral

epicondyle, then divides– Innervates: all posterior muscles of arm and forearm• Triceps brachii, anconeus, supinator, brachioradialis

– Divides in forearm: • Superficial = skin of arm and dorsolateral surface of hand• Deep = extensor muscles of forearm (eg E. carpi radialis L + B)

– Damage to Radial Nerve = wristdrop• Inability to extend the hand, st inability to fully extend forearm

Innervation by Posterior Cord (continued)

• Axillary Nerve (runs w/ humeral circumflex a.)– Innervates: • Deltoid and Teres minor (motor inn)• Capsule of shoulder, skin of shoulder (sensory inn)

• Subscapular Nerve {branches of C5 + C6 rami}

– Innervates: Subscapularis, Teres major

• Thoracodorsal Nerve (runs w/thoracodorsal a+v)– Innervates: Latissimus dorsi

Innervation by Lateral Cord• Musculocutaneous– Course: branches to arm, distal to elbow becomes

cutaneous for lateral forearm skin– Innervates• Biceps brachii, brachialis, coracobrachialis (motor inn)• Skin distal to elbow (sensory)

• Suprascapular (runs w/suprascapular a+v) {C5, C6}– Innervates: Supraspinatus, Infraspinatus

Innervation by both Lateral and Medial Cords

• Median– Course: middle of brachial plexus, does not branch in arm, distal

to elbow provides many branches to most forearm flexors, passes through carpal tunnel to hand to lateral palmar intrinsics

– Innervates: most muscles of anterior forearm (motor inn)• (eg) most flexors, some intrinsics (thumb)

– Innervates: skin of lateral 2/3 hand on palm side, dorsum of fingers 2+3 (sensory inn)

– Nerve Damage = “Ape” Hand• Inability to Oppose Thumb

Innervation by Medial Cord

• Ulnar– Course: runs along medial side of arm, behind medial

epicondyle, superficial to carpal tunnel into hand, branches to supply intrinsics and skin

– Innervates: • FCU and part of FDP, most intrinsics (motor inn)• Skin of medial 2/3 of hand A+P (sensory inn)

– Nerve Damage: Clawhand• Inability to extend fingers at interphalangeal joints,

results in permanent flexion = claw

Cutaneous Innervation to the Hand

Ulnar Nerve

Brachial Artery

Median Nerve

Ulnar NerveMedian Nerve

Radial Artery

Musculocutaneous Nerve UlnarArtery

Where’s Radial Nerve?

Thank you…