Dorsum of hand

The dorsum of hand, or posterior aspect, is characterized by thin skin, visible superficial veins, and prominent tendons. Its unique anatomy facilitates a wide range of hand movements.

Key anatomical features

1. Skin and subcutaneous tissue

The skin on the dorsum of hand is notably thin and flexible, allowing for extensive movement over the underlying structures. Beneath the skin lies a loose layer of subcutaneous tissue containing a network of superficial veins, nerves, and lymphatic vessels.

2. Veins

A defining feature of the dorsum is the dorsal venous network, an arch-like arrangement of veins that is often visible beneath the skin. This network gives rise to the primary superficial veins of the arm: the cephalic vein on the thumb side and the basilic vein on the little finger side. These veins are commonly utilized for intravenous access due to their superficial location and accessibility.

3. Tendons

The dorsum of hand features prominent tendons from the extensor muscles of the forearm. Originating in the posterior compartment of the forearm, these muscles extend the wrist, fingers, and thumb via their respective tendons.

Key extensor tendons visible on the dorsum include:

• Extensor digitorum: Divides into four tendons that extend the index, middle, ring, and little fingers.

• Extensor indicis: Provides additional extension to the index finger.

• Extensor digiti minimi: Offers additional extension to the little finger.

• Extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus: These three tendons define the boundaries of the anatomical snuffbox, a triangular depression at the base of the thumb, clinically significant for evaluating scaphoid fractures.

4. Bones and Joints

The bony structure of the dorsum of the hand includes the posterior surfaces of the carpal bones (wrist bones) and the metacarpal bones (palm bones). The metacarpophalangeal (MCP) joints (knuckles) and the interphalangeal (IP) joints of the fingers are visible and palpable on the dorsum.

5. Nerves

Sensory innervation to the dorsum of the hand is primarily supplied by two main nerves:

• Superficial branch of the radial nerve: Innervates the lateral two-thirds of the hand, including the thumb, index finger, middle finger, and the lateral half of the ring finger (up to the proximal phalanges).

• Dorsal branch of the ulnar nerve: Provides sensation to the medial one and a half fingers (little finger and medial half of the ring finger) and the corresponding medial part of the dorsum.