radiaalnärvi

Radiaalnärvi, also known as the radial nerve, is a peripheral nerve in the upper limb. It originates from the posterior cord of the brachial plexus, receiving nerve fibers from the C5, C6, C7, C8, and T1 spinal nerve roots. The radial nerve is the largest nerve of the brachial plexus and is primarily responsible for the extension of the elbow, wrist, and fingers, as well as supination of the forearm.

The radial nerve travels down the arm, initially in the posterior compartment of the arm, where it winds around the humerus in the radial groove. Here, it supplies the triceps brachii muscle, which extends the elbow. As it enters the forearm, it divides into two main branches: the deep radial nerve and the superficial radial nerve.

The deep radial nerve is primarily motor and innervates the muscles of the posterior forearm, including the extensor muscles of the wrist and fingers and the supinator muscle. Injuries to the deep radial nerve typically result in wrist drop and difficulty extending the fingers and thumb.

The superficial radial nerve is sensory and provides sensation to the dorsal aspect of the radial side of the hand, including the thumb, index finger, and the radial half of the middle finger. It also supplies sensation to the dorsal aspect of the thumb and index finger webspace.

Common causes of radial nerve injury include fractures of the humerus, especially those involving the radial groove, compression from prolonged pressure (e.g., "Saturday night palsy"), and penetrating trauma. Symptoms of radial nerve dysfunction can range from weakness in extending the wrist and fingers to sensory loss in the hand.