Limb buds first appear as small elevations on ventro lateral body end of fourth week.

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1 ANATOMY OF THE HAND DR SANTOSH KUMAR ASSOCIATE PROFESSOR JINNAH SINDH MEDICAL UNIVERSITY KARACHI 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 dermatome ( which is skin area supplied by a single spinal nerve ) ANATOMY Bony skeleton Muscles and soft tissues Vessels and nerves BONY SKELETON 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 row trapezium, trapazoid, capitate, hamate BONES OF THE HAND

2 5 Metacarpals Thumb is no. 1 Little finger is no. 5 PHALANGES All fingers have 3 phalanges distal Except thumb has 2 middle distal proximal proximal Most of tendon in the hand originate in muscles arising from the forearm Flexor on volar aspect of forearm must arise from common flexor tendon (medial epicondyle ) is a joint complex consisting of radio-carpal joint and many relationships between the carpal bones Review of carpals Proximal row = Pisiform, Triquetrum, Lunate, and Scaphoid* Distal row = Hamate, Capitate, Trapezoid, and Trapezium *Scaphoid has a notoriously poor blood supply and recovers poorly following injury Osteology Osteology Osteology Scaphoid Cross Section at Wrist All carpal bones articulate via gliding or plane joints A more or less joint exists between proximal row and distal row of bones called mid-carpal truly is a series of gliding joints

3 Scaphoid, Lunate and Triquetrum with Trapezium, Trapezoid, Capitate and Hamate Pisiform is not involved True Wrist = Radio-Carpal Ulnar-Carpal = interposed disc Distal radius with proximal carpals Condyloid joint 2 degrees of freedom Major Ligaments Palmar radio-carpal, palmar ulnocarpal, dorsal radio-carpal, dorsal ulno-carpal, radial and ulnar collateral Radio-Carpal Mid-Carpal Proximal row of carpals with distal row A series of gliding joints MAJOR Ligaments Capsule plus Pisohamate, pisometacarpal, capitotriquetral, palmar and dorsal carpometacarpal Flexion/Extension about degrees of ROM Radiocarpal v. Mid Carpal Flexion is initiated in mid carpal joint and 60% occurs there

4 Extension is also initiated at mid carpal but most occurs in radio-carpal. Need 35 degrees for good function at least 10 for any significant function. Abduction/Adduction about 15 to 20 degrees Intercarpal proximal row slides over distal row Carpo-Metacarpal Joints 2-5 Hamate with 4 and 5 Capitate with 3 Trapezoid with 2 Gliding joints with limited range mostly passive Palmar and Dorsal carpometacarpal ligaments C-M Joints C-M Joints C- M Thumb Trapezium with 1st met Saddle Adds rotary component very mobile Capsule support C-M Thumb Metacarpal Phalangeal Joints Ellipsoid Passive rotation Collateral Ligaments

5 Deep Transverse Metacarpal Ligaments Palmar Ligaments (Plates) Interphalangeal Joints Hinge Collateral Ligaments Palmar Ligaments (Plates) Definition of Finger Movements Reference is imaginary line through the middle of long (3 rd ) finger Adduction of 2-5 = towards that point Abduction = away 1, 4, and 5 Thumb Flexion Extension ABD ADD Rotation Opposition = flexion with adduction and rotation Finger Movements Finger Movements Flexor Tendons Tenosynovium (AKA Fibro-Osseous Tunnels) Anular Pulleys AKA Vaginal Ligaments

6 Anular and Cruciform Relationship to Palmar Plates Vinculum Longa and Breve