Radial Nerve Function in Hand: Symptoms, Causes & Treatment

The radial nerve, one of the five major nerves in the arm, plays a pivotal role in hand function. It originates from the posterior cord of the brachial plexus and extends down the arm, branching out to innervate various muscles and provide sensation to the posterior aspect of the hand and thumb. This article delves into the intricate functions of the radial nerve in the hand, its anatomical course, and the consequences of its injury.

Anatomical Course and Branches

The radial nerve winds around the humeral shaft, passing through the radial tunnel at the elbow, and then descends along the posterior aspect of the forearm. It enters the hand through the first dorsal interosseous space, dividing into two main terminal branches: the superficial and deep palmar branches.

Superficial Palmar Branch

The superficial palmar branch supplies sensation to the anatomical snuffbox, the dorsal aspect of the thumb, and the index finger. It also innervates the thenar muscles, responsible for abduction and opposition of the thumb.

Deep Palmar Branch

The deep palmar branch provides sensation to the lateral three and a half fingers and the dorsum of the hand. It also innervates the interossei and lumbricals, which are crucial for fine motor movements of the hand.

Motor Functions

The radial nerve is responsible for several essential motor functions in the hand. It innervates the muscles that extend the wrist, fingers, and thumb. Some of the key muscles it supplies include:

• Extensor carpi radialis longus and brevis: Extend and abduct the wrist
• Extensor digitorum: Extends the metacarpophalangeal (MCP) joints of the fingers
• Extensor pollicis longus and brevis: Extend the thumb
• Extensor digiti minimi: Extends the little finger

Sensory Functions

The radial nerve provides sensation to the posterior aspect of the hand and the thumb. It is responsible for proprioception, which is crucial for hand positioning and coordination. The areas of sensation include:

• Dorsal aspect of the thumb
• Index finger
• Lateral half of the middle finger
• Lateral two and a half fingers on the dorsum of the hand

Radial Nerve Injuries

Injuries to the radial nerve can result in significant functional impairment. Common causes include trauma, compression, or entrapment. Symptoms may include:

• Weakness or paralysis of the hand extensors
• Loss of sensation in the posterior aspect of the hand
• Dropping objects due to difficulty gripping

Prompt evaluation and treatment by a healthcare professional are crucial to maximize recovery and restore hand function.