The carpal nerve, more accurately known as the median nerve as it travels through the carpal tunnel, provides sensation to the thumb, index finger, middle finger, and the thumb-side half of the ring finger, and controls muscles at the base of the thumb.
Sensory Function
- Touch: The median nerve is responsible for transmitting sensory information related to touch, pressure, pain, and temperature from the skin of the thumb, index finger, middle finger, and radial half of the ring finger. This allows us to feel and interact with the world around us.
- Proprioception: While not the primary nerve for proprioception in the hand, the median nerve contributes to our sense of hand position and movement.
Motor Function
- Thumb Movement: The median nerve controls the thenar muscles, which are located at the base of the thumb. These muscles are crucial for fine motor movements such as opposition (bringing the thumb across the palm to touch the fingers), abduction (moving the thumb away from the palm), and flexion (bending the thumb).
- Wrist Flexion: Although primarily innervated by the ulnar and radial nerves, the median nerve provides some contribution to wrist flexion.
Relationship to Carpal Tunnel Syndrome
The median nerve passes through the carpal tunnel, a narrow passageway in the wrist. Carpal tunnel syndrome occurs when this tunnel becomes narrowed or the tissues within it swell, compressing the median nerve. This compression can lead to symptoms such as:
- Numbness and tingling in the thumb, index, middle, and ring fingers
- Pain in the wrist and hand
- Weakness in the thenar muscles, making it difficult to perform fine motor tasks
Summary
In summary, the median nerve, commonly referred to in the context of carpal tunnel syndrome as the "carpal nerve," has both sensory and motor functions, providing feeling to parts of the hand and controlling crucial thumb movements. Damage or compression of this nerve, as seen in carpal tunnel syndrome, can significantly impair hand function.
