ANATOMY OF THE HAND BY Dr. J . M . Hassanain

Hand function is an important feature in humans over other primates who lack fine control and precision

EMBRYOLOGY OF THE UPPER LIMB Limb buds first appear as small elevations on ventro lateral body end of fourth week.

Each limb bud : Mesenchyme derived from somatic mesoderm which is covered by a layer of ectoderm

Distal end of bud form flipper like limbs. Later bones develop and myoblast aggregate to develop muscle mass .

Upper limb rotates laterally 90 degrees Specific dermatone ( which is skin area supplied by a single spinal nerve )

ANATOMY Bony skeleton Muscles and soft tissues Vessels and nerves

BONY SKELETON Wrist joint composed of multiple carpal bone articulating with the radius proximally and five metacarpals distally

Proximal row of carpal bone. (radial to ulnar) Proximal row of carpal bone (radial to ulnar) scafoid , lunate , traquetral , pisiform Distal row trapezium , trapazoid , capitate , hamate

BONES OF THE HAND 5 Metacarpals Thumb is no. 1 Little finger is no. 5

PHALANGES All fingers have 3 phalanges proximal middle distal Except thumb has 2 proximal distal

Most of tendon in the hand originate in muscles arising from the forearm Flexor on volar aspect of forearm must arise from common flexor tendor (medial epicondyle )

Extensors on dorsal aspect of the forearm arise from common extensor tender on lateral epicondyl

In the hand ulnar side hypo thenar muscles acting on the little fingers: Abductor digitiminimi Flexor digitiminimi brevis Opponens digitiminimi

Radial side thenar muscle acting on the thumb Flexor, adductor pollices Abductor pollices brevis Opponen pollices brevis

Long flexors fl. digitorum superficialus fl. digitorum profundus Act on all the fingers

Intrinsic Lumbrical Dorsal Ventral interrosies

Vascular Supply of Hand Radial artery : Superficial palmer branch superficial palmer arch ,which arises above the wrist Common palmer digital Deep palmer branches Deep palmer arch  palmer metacarpal arteries which joins the common digital Ulnar artery  superficial palmer branch joins on side of pisiform of superficial palmer branch Plate 439B /439A

VENOUS DRAINAGE OF HAND Via : Dorsal digital vein  dorsal venous arch Basillic vein in front of forearm

Peripheral nerve entrapment There is a disproportion between volume of the peripheral nerve and space within the extremity through which it passes

Applied Anatomy of Ulnar Nerve Arises directly from the medial cord of brachial plexus (C8-T1) Lies between axillary artery laterally and axillary vein medially

At inferior border of subscapularis muscle nerve receives fiber of C7 ( lat. root of ulnar nerve ) Descend in arm post. to pectoralis major muscle ( posterio medial to brachial artery)

8 cm above medial epicondyl with branch of superior ulnar collateral artery diverge medially from brachial artery to pierce medial intramuscular septum

Together descend on medial head of triceps Nerve passes in ulner groove dorsal aspect of medial epicondyl It innervates fl. carpi ulnaris 0.5-1 cm above medial epicondyl

Potential points of compression in the arm Ulnar nerve fibers ( medial cord ) 1st rib as nerve passes between rib & clavicle 8 cm proximal to medial condyl as nerve pierce intramuscular septum ( arcade of Struther ) Hypertrophy of medial head of triceps may force nerve anteriorly, as triceps contract, nerve get compressed

Ulnar Nerve at Elbow &Forearm In cubital fossa ulnar nerve passes through fibro-osseous tunnel As it leaves the canal it lies between the flexor corpi ulnanis and flexor digitorum profundus till middle of forearm

In distal 1/3 lies just radial to the flexor corpi ulnaris Straight line drawn from medial epicondyl to radial margin of pisiform marks the line of the nerve

Supply of ulnar nerve in forearm Muscular branch to fl. Digitorum profundus ( i.e. ulner ½ ) 3 cm distal to medial epicondyl Palmer cutanous branch Dorsal cutanous branch

Ulnar nerve enters hand From under fl corpi ulnaris muscle , nerve and artery Radial to pisiform , superficial to transverse carpel lig. and dorsal to superficial palmer lig. Ulnar nerve divide to : deep terminal branch superficial palmer branch

Muscle supplied by ulnar nerve Flexor corpi ulnaris Flexor digitorum profundus ( medial 2 tendons ) Flexor digiti minimi 2 ,3 ,4th web space interossei 3rd & 4th lumbricle Adductor pollicis 1st dorsal interosseous

Sensory Supply of Ulnar Nerve Dorsal cutanous branch of ulnar : skin dorsoulnar side of hand , little finger and ulnar ½ of index finger Medial cutanous nerve of forearm : C8-T1 skin over biceps elbow crease middle 1/3 of arm palmer skin down to forearm

Anatomical Sites of Compression Points in elbow and forearm Anconeus epitrochlearis muscle Fibrous arcade between 2 heads of fl. carpi ulnaris Gelberman 416, 417 ,421,422 fig 29.2,29.3 ,29.4,29.5

Site of compression in hand &wrist Palmaris brevus muscle Fibrous origin of fl digitiminmi Ulnar artery aneurysm or thrombosis Distal ulnar tunnel ganglia

MEDIAN NERVE Arises from lateral & medial cords of brachial plexus Contain fibers C5 –T1 Forms antrolat to 3rd portion of axillary artery in upper 1/3 of arm

In the arm it descends post In the arm it descends post. to pectoralis major muscle, lateral to brachial artery, antromedial to brachialis muscle, posteromedial to biceps In mid portion of arm, median nerve crosses ant to brachial artery to lie on its medial side to enter the cubital fosse

The nerve enters forearm between humeral and ulnar head of pronater teres Then runs between fl digitorum superficialis and fl digitorum profundus, later emerges 5 cm above wrist radial to tendon of palmaris longus

MEDIAN NERVE IN THE WRIST It enters the wrist dorsal to transverse carpal lig through the carpal tunnel

Boundaries Of Carpal Tunnel Dorsally: radio carpal lig. Radially: scaphoid & trapezium Palmorly: transverse carpal lig. Ulnary: hood of hamate & pisiform

After exiting carpal tunnel Median nerve splits to two parts Common digital nerve to thumb Proper digital nerve to radial side of index Ulnar division of median nerve; common digital to 2nd & 3rd web

Muscle supplied by median nerve Forearm Pronator teres Flexor digitorum superficialis Flexor carpi radialis Palmaris longus Flexor digitorum profundus Flexor pollicis longus Pronator quadratus

HAND Flexor pollicis brevis Abductor pollicis brevis Opponens pollicis First lumbrtical Second lumbrical

Anatomical compression points of the median nerve ARM: Pectoralis minor muscle Anomalous axillary arch muscles Anomalous vascular arches in the axilla Deltopectoral fascia Supracondyloid process Ligament of Struthers

FOREARM Lacertus fibrosus Pronator teres muscle Flexor digitorum superficialis arch Anomalous muscles Ulnar collateral or radial artery branches

HAND / WRIST Carpal tunnel Palmar cutaneous branch within the transverse retinacular ligament

RADIAL NERVE Arises from the post cords of the brachial plexus behind 3rd part of axillary artery Neural element of C5 – C8 Proximal 1/3 of arm nerve descends behind brachial artery ant to subscapularis ,teres major ,latissmus dorsi muscle and long head of triceps

At junction of upper and middle 1/3 of arm deviates dorsolaterally between medial and long head of triceps lying adjacent to spiral groove of humerus

10 cm above lat humeral epicondyl lying between the brachialis and brachioradialis then lies between brachialis and extensor carpi radialis ant to tip of lat epicondyl dividing into : Superficial Deep branches

Radial Nerve In Forearm Superficial branch ant to supinator muscle proximal 1/3 then deep to brachioradialis The sup branch pierces the fascia on the brachioradialis on the ulnar side of tendons 7cm above wrist On the dorsoradial side of wrist it divides into 5 dorsal digital nerves and only one branch to extensor carpi radilalis brevus muscle

Post interosseous nerve (deep terminal branch of radial nerve ) innervates extensor muscle of wrist It is seperated from the radium by deep head of supinator After leaving the supinator it lies between the abductor pollies and other extensors of forearm

In distal forearm it penetrates the extensor pollies brevus to lie in the interosseous membrane Distally it divides to give sensory innervation to the wrist

Muscles supplied by radial nerve Triceps : long head medial head lateral head Anconeus Brachioradialis Extensor carpi longus Extensor carpi radialis brevis

Muscles supplied by radial nerve Extensor carpi ulnaris Extensor digitorum communis Extensor digiti minimi Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indicis proprius

Anatomical compression points of the radial nerve ARM: Accessory subscapularis teres latissimus Lateral head of the triceps muscle Lateral intermuscular septum

FOREARM: Posterior interosseous nerve within radial tunnel Fibrous bands attached to radiocapitelar joint Extensor carpi radialis brevis muscle Arcade of Frohse Fibrous bands within the supinator muscle

Superficial radial nerve Between brachioradialis muscle & radial shaft Between brachioradialis and extensor carpi radialis longus tendons

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