The anatomy of the wrist & hand

Done by:Mohad mubarak Sameer esawi

A- Bones

8 bones form the wrist or carpus;

5 bones form the metacarpus or palm.

The remaining 14 are

digital bones.

These eight bones of the wrist are arranged in two rows of four ( proximal and distal rows).

The proximal raw : pisiform –tiquetrum-lunate-scaphoid

The distal raw: hamate – capitate-trapezoid-trapezium

metacarpal bone & phalangeal bone divide into :Base- shaft – head

the 14 phalnges are divided to Proximal-Middle – distal .

Exept the the thumb which contain only the proximal & the distal

B- The joints of the hand.

1- wrist :the distal end of the radius articulates with two bones of the proximal raw of the carbal bone which are the lunate & the scaopoid & triquetrum to form the wrist joint

2- Intercarpal joints :

Articulation between the carpal bones .

3- carpometacarpal joints : The base of metacarpals articulate with the distal raw of the carpal bones .1st metacarpal ….. Trapezium2nd metacarpal ….trapezoid , trapezium ., capitate .3rd metacarpal …….capitate.4th metacarpal ……hamate , capitate .5th metacarpal …..hamate.4- metacarpophalangeal joint :The head of the metacarpals articulate with the base of thr proximal phalnges 5- interphalangeal joint :Which are 9 joints articulate between the phalnges .Ther is distal & proximal phalangeal joints .exept the thumb .

C- Muscles and tendonsThe muscles of the hand subdivided into :1- The intrinsic muscles are located within the hand itself.1- thenar .2- hypothenar .3- lumbrical.4- Interossei.

2- The extrinsic muscles are located proximally in the forearm and insert to the hand skeleton by long tendons.1- extensor .2- flexor.

Extrinsic extensorsThey can be divided into:A - primary action is wrist extension

Extend & abduct the hand @ wrist joint

Extend & adduct the hand @ the wrist joint

2- primary action is at the digits

Extends the MCP of the thumb Extends the IP joint of the thumb

Abducts and extends the CMC of the thumb

Extends the fingers from II –V @ the MCJ, Extend little finger @ the MCP

p.S : all of the extrinsic extnsor group innerated by the radial nerve .

Extrinsic flexorsThere are 3 layers of extrinsic flexors: 1- the superficial muscle: their primary action at the wrist or palm.

Adduct & flex & abduct

2- the intermediate muscle : Flexes PIP joints of 2-5 digits, assists in flexion of the MCP joints and in wrist flexion.

3- the deep muscles : primary action at the digits.

. Flexes DIP joint of digits 2-5; assists in flexion of proximal PIP and MCP joints of digits 2-5; may assist in flexion of wrist Flexes IP joint of thumb p.S : all the extrinsic flexor are innervated b the median nerve exept the FCU by ulnar nerve .

Intrinsic muscles

Situated totally within the hand. Divided into 4 groups:1 -Thenar2- Hypothenar3- Lumbrical 4- Interossei

1- ThenarThe thenar group consists of :

.

Abducts the CMC and MCP joints of the thumb. Pull the thumb medially & dorward across the palm

Flexes the MCP Adducts of the thumbp.S : all the muscle of the thenar are innervated by median nerve except (AP) by deep branch of the ulnar nerve .

Opponens pollicis

2-HypothenarThe hypothenar group consists of:

Flexes the MCP joint of the little finger Abducts, assists in opposition

pull the 5th metacarpal forward & medially

p.S : all the muscle of this group innervated by the deep branch of the ulnar .

LumbricalsThe lumbrical muscles contribute to:

Flexion of the MCP joints & Extension of the interphalangeal joints.

p.s Nerve to Lumbricals I, II, MedianNerve to Lumbricals III, IV: deep branch of the Ulnar

InterosseiThe interossei group consists of :3 palmar muscles4 dorsal muscles

Innervated by thedeep branch of the ulnar nerve

Dorsal interossei abduct the fingers

Palmar interossei adduct the fingers to the hand axis.

End of the 1st part By Mohad Mubarak

NervesThe hand is innervated by 3 nerves: 1- median nerve. 2- ulnar nerve.3- radial nerve.

Each one has a sensory and motor components.

Median nerve#Originates from the lateral and

medial cords of the brachial plexus (C5-T1).

#Palmar cutaneous branch provides sensation at the thenar eminence.

#Recurrent motor branch innervates the thenar and lumbrical muscles.

Sensory digital branches providesensation to:1-Thumb2-Index3-Ring finger (radial side)

Innervates the muscles involved in the power grasping function of the hand. It originates at the medial cord of the brachial plexus (C8-T1).Motor branches innervate:Flexor carpi ulnaris Flexor digitorum profundus

@Palmar cutaneous branch provides sensation at the hypothenar eminence.

The dorsal branch provides sensation to:

1-Ulnar portion of the dorsum of the hand and small finger.

2-Part of the ring finger.

@At the hand, the superficial branch forms the digital nerves.

Provide sensation at the small finger and ulnar aspect of the ring finger

Ulnar nerve

Radial NerveInnervating the wrist extensors

Originates from the posterior cord of the brachial plexus (C6-8).

At the elbow, motor branches innervate the brachioradialis and extensor carpi radialis longus muscles.

BLOOD SUPPLYThe radial and ulnar arteries, which are

branches of the brachial artery, provide the blood supply to the hand.

The radial artery runs distally in the forearm between the brachioradialis and flexor

carpi radialis muscles.The ulnar artery runs distally

in the forearm under the flexor carpi ulnaris muscle.

The superficial palmar arch : is formed mainly by the ulnar artery with a contribution of the radial artery, the arch gives raise to

common palmar digital arteries wich supply the palm & each divide into a pair of proper palmar digital arteries which supply the finger

Deep palmer arch :Is formed mainly by the radial artery with a contribution from a branch of the ulnar artery . It give raise to palmar metacarpal arteries which supply the palm and anastomose with the common palmar digital arteries to the superficial palmar arch

VeinsVeins generally follow the deep

arterial system as venae comitantes.

A superficial venous system also exists at the dorsum of the

hand

Contributes to the cephalic and basilic vein in the upper

extremity.

Dorsal digital veins : pass along the sides of the fingers and are joined to one another by oblique communicating branches. Those from the adjacent sides of the fingers unite to form three dorsal metacarpal veins Dorsal metacarpal veins: which end in Dorsal venous network of hand opposite the middle of the metacarpus.

Dorsal venous network of hand It is found on the back of the hand and gives rise to veins such as the cephalic and the basilic veins .

Palmar metacarpal veins : drains the metacarpal region of the palm, eventually draining into the deep palmar venous arch. & then to the radial veins which drain the lateral aspect of the arm

Proper palmar digital : which drain into the common palmar digital veins then drain to the superficial palmar venous arch and eventually draining to the ulnar veins which drain the medial aspect of the arm .