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THE HAND

THE SKELETON OF THE HAND The skeleton of the hand is subdivided into three segments: the carpus, metacarpus and phalanges. The carpus: Eight carpal bones made up of two rows of four. 1- Proximal row: Scaphoid, Lunate,Triquetral, Pisiform. 2- Distal row: Trapezium, Trapezoid, Capitate and Hamate.

Cutaneous nerve supply Palm of the hand: Cutaneous branches of median nerve (lateral 2/3 of palm and lateral 3 ½ fingers) Cutaneous branches of ulnar nerve (medial 1/3 of palm and medial 1 ½ fingers)

Cutaneous nerve supply Dorsum of the hand: Cutaneous branches of radial nerve (lateral 2/3 and lateral 3 ½ fingers except the nail bed and adjacent skin by median nerve.) Cutaneous branches of ulnar nerve (medial 1/3 and medial 1 ½ fingers).

Flexor Retinaculum It is a thick and strong fibrous band that bridges over the carpal groove (made by carpal bones). It converts the carpal groove into an osseo-fibrous tunnel (carpal tunnel). The retinaculum is attached medially to pisiform and hamate, while laterally is attached to scaphoid and trapezium.

Structures superficial to flexor retinaculum: Ulnar nerve. Ulnar vessels. Palmar cutaneous branch of median nerve. Cutaneous branch of radial nerve. Tendon of palamaris longus.

Structures deep to the flexor retinaculum: Median nerve. Tendons of flexors of the forearm that insert into the hand with their synovial sheaths: a. Flexor carpi radialis. b. Flexor digitorum profundus. c. Flexor digitorum superficialis. d. Flexor pollicis longus.  

Palmar aponeurosis It is a triangular thickening of the deep fascia of the palm. Its apex is directs upwards while the base is divided into 4 slips; each for each of the medial 4 fingers. Function: Protection of the underlying vessels and nerves of the palm of the hand. 

Muscles of the hand 1-Hypothenar group: Thenar and hypothenar muscles. -Abductor digiti minimi. -Flexor digiti minimi. -Opponens digiti minimi.

2-Thenar group: They are 4 muscles : 1,2,3- Muscles of thenar eminence (abductor pollicis brevis, flexor pollicis brevis and opponens pollicis). 4-Adductor pollicis.

4-Adductor pollicis Origin. a-Transverse head. b-Oblique head. Third metacarpal bone b-Oblique head. Bases of 2nd , 3rd metacarpal bones

Nerve supply -Hypothenar muscles and adductor pollicis: Deep branch of ulnar nerve. -Other thenar muscles: Median nerve

Palmaris brevis Origin: Medial border of palmar aponeurosis. Insertion: Into the skin of the medial border of the hand. Nerve supply: Superficial branch of the ulnar nerve. Action: It deepens the hollow of the palm to make a firmer grip.

Central Muscles Of The Hand Interossei Palmar Interossei Dorsal Interossei Lumbricals

Palmar Interossei 2nd : Origin medial side of the 2nd metacarpal Insertion: medial side of the extensor expansion of the index finger. 3rd, 4th; Origin lateral side of the 4th and 5th metacarpals Insertion lateral side of the extensor expansion of ring and little fingers

Palmar Interossei Action: Nerve supply: deep branch of ulnar nerve Action: Flexion of metacarpo- phalageal joint of index, ring and little fingers Adduction of the thumb , index, ring little fingers towards the midline of the hand

Dorsal Interossei 4 slender fleshy muscles each arises by 2 heads from the metacarpal bone Origin: 1st : mt cpl I II 2nd II III 3rd III IV 4th IV V

1st dorsal interosseous muscle

Dorsal Interossei Insertion : -Extensor expansions Nerve supply: deep branch of ulnar nerve. Action: -Abduction of index, middle, and ring fingers towards the midline of the hand. -Flexion of the metacarpo- phalangeal joints and extension of interphalangeal joints of lateral four fingers (writing position).

Central Muscles Of The Hand 4/20/2017 THE HAND Central Muscles Of The Hand Lumbrical muscles 4 fleshy slender muscles originating as follows: 1st and 2nd from the lateral side of the tendons of flexor digitorum profundus for index and middle fingers respectively. 3rd from the adjacent sides of the tendons of flexor digitorum profundus for middle and ring fingers. 4rd from the adjacent sides of the tendons of flexor digitorum profundus for ring and little fingers. THE HAND

Lumbricals Nerve supply: Digital branch of median nerve Deep branch of ulnar nerve

Central Muscles Of The Hand Lumbricals Action: Flexion of metacrpo –phalngeal joint Extension of inter-phalngeal joint (writing position)

Some Clinical Applications

Arteries of the hand. Radial artery They form two arches: 1- Superficial palmar arch. 2- Deep palmar arch.

1-Superficial palmar arch It lies deep to palmar aponeurosis , at the level of fully extended thumb. Origin: mainly from ulnar artery and completed by superficial palmar branch of radial artery. It gives 4 digital arteries.

2-Deep palmar arch -It lies 3 cm proximal to the superficial palmar arch. Origin: mainly from radial artery, completed by deep branch of ulnar artery. Branches: palmar metacarpal arteries. Branches of radial artery: 1-Dorsal arch: formed by radial and ulnar arteries, on dorsum of hand. 2-Princeps pollicis: from radial artery (primary supply of thumb). 3-Radialis indicis: from radial artery, supplies radial side of index.

Veins of the hand 1-Superficial veins. 2-Deep veins.

Digital veins

Cephalic vein: is the lateral continuation of dorsal venous arch. Basilic vein: is the medial continuation of dorsal venous arch. The median cubital vein in cubital fossa.

Nerves of the hand 1-Median nerve A-origin

course: -It enters the hand by passing deep to the flexor retinaculum course: -It enters the hand by passing deep to the flexor retinaculum. -It divides into medial and lateral branches.

Branches in the hand The 2 branches give: 1- Cutaneous branches to the skin of: Lateral 2/3 of the palm, palmar aspect of the lateral 3 1/2 fingers, the nail beds and dorsum of terminal phalanges of these fingers. 2- Muscular branches (recurrent branch): to muscles of thenar eminence and the lateral 2 lumbricals.

Nerve injury

2-Ulnar nerve A-Origin

B-course: - It enters the hand by passing superficial to the flexor retinaculum. - It divides into superficial and deep branches.

Branches in the hand 1-Superficial branch : It gives cutaneous branches to supply the skin of medial 1/3 of palm and dorsum of the hand, & medial 11/2 fingers (palmar and dorsal aspects). Muscular branch  palmaris brevis. 2-Deep Branch: It gives muscular branches to all muscles of the hand EXCEPT muscles of thenar eminence and the lateral two lumbricals.

3-Radial nerve A-origin

B-course

Branches in the hand Dorsum of the hand: -Cutaneous branches of radial nerve (lateral 2/3 and lateral 3 ½ fingers except the nail bed and adjacent skin by median nerve)

4/20/2017 THE HAND THE HAND

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Anatomical snuff box Laterally: the tendons of the abductor pollicis longus and extensor pollicis brevis. Medially: the tendon of the extensor pollicis longus. the floor : the scaphoid and trapezium. The radial artery passes obliquely through the anatomical snuffbox, deep to the extensor tendons of the thumb and lies adjacent to the scaphoid and trapezium. Sup. :Terminal parts of the superficial branch of the radial nerve and the origin of the cephalic vein from the dorsal venous arch of the hand.

EXTENSOR RETINACULUM  It is a thickening of the deep fascia at the back of the wrist. It is attached laterally to the anterior border of the radius and medially to the triquetral and pisiform bones. It sends septa to the back of the lower end of the radius and ulna forming 6 extensor compartments