Anatomy of the Hand PDF

Anatomy of the hand Dr. Malak Alghamdi Assistant professor of anatomy COMJ [email protected] Objectives Describe the features of the skin of the hand Describe the attachment, innervation, actions and clinical testing of the hand muscles Describe the flexor and extensor retinacula s...

Anatomy of the hand Dr. Malak Alghamdi Assistant professor of anatomy COMJ [email protected] Objectives Describe the features of the skin of the hand Describe the attachment, innervation, actions and clinical testing of the hand muscles Describe the flexor and extensor retinacula spaces of the hand Describe the boundaries and contents of the carpal tunnel Describe the blood vessels and nerves of the hand Describe the palmer aponeurosis, sheaths, extensor expansion , synovial sheaths and space of Parona Skin of the hand Skin of palm palmer Thick and hairless Bound to underlying deep fascia by numerous fibrous bands Shows many flexure creases at sites of skin movement Sweat glands are present in large numbers dorsal Skin on dorsum Thin, hairy, and freely mobile on underlying tendons and bones Flexor retinaculum Thickening of deep fascia Converts carpal arch into carpal tunnel Attached medially to pisiform and hook of hamate; and laterally to tubercle of scaphoid and trapezium It holds long flexor tendons in position at wrist Carpal tunnel Formed anteriorly at wrist by: Carpal bones inferiorly Flexor retinaculum superiorly Pisiform and hook of hamate medially Tubercles of scaphoid and trapezium laterally Content: 4 tendons of flexor digitorum profundus 4 tendons of flexor digitorum superficialis Tendon of flexor pollicis longus Median nerve  Extensor retinaculum Thickening of deep fascia Form 6 separate tunnels (fibrous septa ) each is lined with synovial sheath Holds long extensor tendons in position Attached medially to pisiform and hook of hamate; and laterally to distal end of radius Synovial sheaths Fibrous Sheaths Surrounds tendons of flexor digitorum superficialis and profundus muscles Begin anterior to metacarpophalangeal joints and extend to distal phalanges Formed by fibrous arches and cruciate ligaments Attached posteriorly to margins of phalanges and to the palmar ligaments Hold tendons to bony plane and prevent tendons from bowing when digits are flexed  Extensor expansion Expansion of tendon of extensor digitorum and extensor pollicis longus over proximal phalanges Triangular, with: Apex: attached to distal phalanx, Central region: attached to middle/proximal phalanx (thumb) Corners (extensor hood): wrapped around sides of metacarpophalangeal joint Provide attachment to hand muscles Palmer aponeurosis Triangular condensation of deep fascia that covers palm Apex: continuous with palmaris longus tendon or anchored to flexor retinaculum Its fibers radiate to extensions at bases of digits Vessels, nerves, and long flexor tendons lie deep to palmar aponeurosis in palm  Hand muscles 4 Short muscles of thumb: 1 adductor pollicis + 3 thenar mm. 3 Short muscles of little digit: 3 hypothenar 4 Lumbricals 8 Interossei 4 palmer 4 dorsal All innervated by deep branch of ulnar nerve except thenar mm. and lateral 2 lumbricals innervated by median n.  Hand muscles Short muscles of thumb: adductor pollicis (@) and thenar muscles (1. Abductor pollicis brevis + 2. Flexor pollicis brevis + 3. Opponens pollicis) Thenar muscles are innervated by median nerve Adductor pollicis is innervated by deep branch of ulnar nerve @ 2 1 3 Short muscles of thumb Adductor pollicis Origin: Oblique head: 2nd and 3rd metacarpal, capitate Transverse head: 3rd metacarpal Insertion: Base of proximal phalanx of thumb Function: Adduction of thumb  Short muscles of thumb Abductor pollicis brevis (most lateral and superficial) Origin: scaphoid, trapezium, flexor retinaculum Insertion: base of proximal phalanx of thumb Function: abduction of thumb Flexor pollicis brevis Origin: flexor retinaculum Insertion: base of proximal phalanx of thumb Function: flexes metacarpophalangeal joint of thumb Short muscles of thumb Opponens pollicis Origin: flexor retinaculum Insertion: shaft of metacarpal bone of thumb Function: pulls thumb medially and forward across palm Movements of thumb  Short muscles of little finger Hypothenar muscles: abductor digiti minimi + flexor digiti minimi + opponens digiti minimi All hypothenat muscles innervated by deep branch of ulnar nerve Abductor digiti minimi Origin: pisiform bone Insertion: base of proximal phalanx of little finger Function: abducts little finger Short muscles of little finger Flexor digiti minimi Origin: flexor retinaculum Insertion: base of proximal phalanx of little finger Function: flexes little finger Opponens digiti minimi Origin: flexor retinaculum Insertion: medial border of 5th metacarpal bone Function: pulls 5th metacarpal forward as in cupping palm  Small muscles of hand Lumbricals (4) Origin: tendons of flexor digitorum profundus Insertion: extensor expansion of medial four fingers Innervation: 1st and 2nd (lateral two) à median nerve 3rd and 4th (medial two) à deep branch of ulnar nerve Function: flex metacarpophalangeal joints and extend interphalangeal joints of 4 fingers  Small muscles of hand Palmar interossei (4) Origin: first arises from base of 1st metacarpal; remaining three from anterior surface of shafts of 2nd, 4th, and 5th metacarpals Insertion: proximal phalanges of thumb and index, ring, and little fingers and dorsal extensor expansion of each finger Innervation: deep branch of ulnar nerve Function: adduct fingers toward center of third finger (PAD) Small muscles of hand Dorsal interossei (4) Origin: contiguous sides of shafts of metacarpal bones Insertion: proximal phalanges of index, middle, and ring fingers and dorsal extensor expansion Innervation: deep branch of ulnar nerve Function: abduct fingers from center of third finger (DAB)  Fascial spaces of palm Potential spaces filled with loose CT Fibrous septum from medial border of palmar aponeurosis attached to anterior border of 5th metacarpal bone Fibrous septum from lateral border of palmar aponeurosis attached to anterior border of 3rd metacarpal Divides palm into thenar space (contains 1st lumbrical) and midpalmar space (2nd – 4th lumbricals) Space of parona: between FDP anteriorly and pronator quadratus and the interosseous membrane posteriorly Blood vessels of hand By radial and ulnar arteries They form in palm two interconnected vascular arches (superficial and deep) Radial artery supply mainly thumb and lateral side of index finger ulnar artery supply the remaining digits and medial side of index finger  Blood vessels of hand deep palmar arch = radial a. + deep palmer branch of ulnar a. superficial palmar arch = ulnar a. + palmer branch of radial a.  Nerves of hand Supplied by ulnar, median, and radial nn. Ulnar n. Divides into deep branch (mainly motor) and superficial branch (mainly sensory) Deep branch of ulnar nerve Penetrates and supplies hypothenar muscles Supplies interossei, adductor pollicis, and two medial lumbricals. Contributes small articular branches to wrist joint Superficial branch of ulnar nerve Innervates palmaris brevis muscle Supply skin on palmar surface of little finger and medial half of ring finger  Nerves of hand Median nerve divides into: Recurrent branch: innervates three thenar muscles Palmar digital branches: Supply lateral two lumbrical muscles Innervate skin on palmar surfaces of lateral three and one-half digits and cutaneous regions over dorsal aspects of the distal phalanges (nail beds) of same digits  Nerves of hand Only superficial branch of radial nerve enters hand, passing over anatomical snuffbox It innervates skin over dorsolateral aspect of palm and dorsal aspects of the lateral three and one-half digits distally to approximately the terminal interphalangeal joints. Thank you!