DORSUM OF HAND

 1.Skin: It is loose on the dorsum of hand. It can be pinched off from the underlying structures.   2.Superficial fascia: The fascia contains dorsal venous plexus, cutaneous nerves, and dorsal carpal arch.

a. Dorsal venous plexus: The digital veins from adja cent sides of index, middle, ring and little fingers form 3 dorsal metacarpal veins  These join with each other on dorsseeum of hand. The lateral end of this arch is joined by one digital vein from index finger and two digital veins from thumb to form cephalic vein. It runs proximally in the anatomical souffbox, curves, round the lateral border of wrist to come to front of forearm. In a similar manner, the medial end of the arch joins with one digital vein only from medial side of little finger to form basilic vein. It also curves around the medial side of wrist to reach front of forearm. These metacarpal veins may unite in different ways to form a dorsal venous plexus

b. Cutaneous nerves: These are superficial branch of radial nerve and dorsal branch of ulnar nerve. The nail beds and skin of distal phalanges of lateral nails is supplied by median nerve and 1% medial nails by ulnar nerve. The superficial branch of radial nerve supplies lateral half of dorsum of hand with two digital branches to thumb and one to lateral side of index and another common digital branch to adjacent sides of index and middle fingers. 

Dorsal branch of ulnar supplies medial half of dorsum of hand with proper digital branches to medial side of little finger two common digital branches for adjacent sides of little and ring fingers and adjacent sides of ring and middle fingers.

Structure of landmark

c. Dorsal carpal arch: It is formed by dorsal carpal branches of radial and ulnar arteries and lies close to the wrist joint. The arch gives three dorsal metacarpal arteries which supply adjacent sides of index, middle; ring and little fingers. One digital artery goes to medial side of little finger. The arch also gives branches to the dorsum of hand.

 3.Spaces on dorsum of hand: There are two spaces on the dorsum of hand:                              a. Dorsal subcutaneous space, lying just subjacent to skin. Skin of dorsum of hand is loose can be pinched and lifted off.                      b. Dorsal subtendinous space lies deep to the extensor tendons, between the tendons and the metacarpal bones. 

4 Deep fascia: The deep fascia is modified at the back of hand to form extensor retinaculum.

ANATOMICAL SNUFFBOX:

   The anatomical snuffbox is a triangular depression on the posterolateral side of the wrist. It is seen best when the thumb is extended. 

BOUNDARIES:                                                              It is bounded anteriorly by tendons of the abductor pollicis longus and extensor pollicis brevis, and posteriorly by the tendon of the extensor pollicis longus, It is limited above by the styloid process of the radius. The floor of the snuffbox is formed by the scaphoid, the trapezium and base of 1st metacarpal.

Anatomical snuffbox. 

CONTENTS:

The radial artery is deep while the superficial branch of radial nerve and cephalic vein are superficial. 

EXTENSOR RETINACULAM:

The deep fascia on the back of the wrist is thickened to form the extensor retinaculum which holds the extensor tendons in place. It is an oblique band, directed downwards and medially. It is about 2 cm broad vertically. 

ATTACHMENTS:

  LATERALLY:Lower part of the sharp anterior border of the radius. 

  MEDIALLY:

 i. Styloid process of the ulna

ii. Triquetral

iii. Pisiform

COMPARTMENTS:

The retinaculum sends down septa which are attached to the longitudinal ridges on the posterior surface of the lower end of radius. In this way, 6 osseofascial compartments are formed on the back of the wrist .

Each compartment is lined by a synovial sheath, which is reflected onto the contained tendons.

Muscle of the back of forearm. 

Dissection of the back of forearm.