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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)
scafoid , lunate , traquetral , pisiform
Distal rowtrapezium , 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
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
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. 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
THANK YOU
THE END