Wrist and Hand Anatomy

Bone Anatomy Scapoid Lunate Triquetrium Pisiform Trapeziod Trapezium Capitate Hamate

Hand and Wrist Anatomy 14 phalanges 5 metacarpals 8 carpal bones 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 5th CMC Plane/synovial joint 1 degree freedom 2 degree freedom Flexion/extension 5th CMC 2 degree freedom 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 Tunnel contains 10 structures 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 Lumbricales Palmar aponeurosis Interossei 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 I N F 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 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 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 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 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 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 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 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 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 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 I N F Trapezium Transverse Carpal Ligament Radial side of 1st metacarpal shaft N Median F Opposition

Intrinsic Hand Muscles Hypothenar Eminence

Abductor Digiti Minimi Pisiform I Ulnar side base of 5th proximal phalanx N Ulnar F MCP ABD of 5th digit

Opponen Digiti Minimi O I N F 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 I N F Hamate bone Transverse carpal ligament Ulnar side of proximal 5th phalanx N Ulnar F MCP Flexion of 5th digit

Other Intrinsic Hand Muscles

Adductor Pollicis O I N F Oblique Head Transverse 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 I N F 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 I N F 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 I N F Tendons of FDP 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 I N F Flexor retinaculum 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 Radial Axillary (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 Median Nerve Brachial Artery Musculocutaneous Nerve UlnarArtery Where’s Radial Nerve? Radial Artery Median Nerve Ulnar Nerve

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