The radial nerve is one of the major nerves of the upper extremity. Forming in the area of the shoulder joint at the confluence of several branches of the brachial plexus, the radial nerve courses down the arm, past the elbow joint, into the forearm, across the wrist, and all the way to the tips of your fingers.

The radial nerve provides important information to your brain about the sensations experienced in the upper extremity and also delivers information to the muscles of the upper extremity about when to contract. Injury to the radial nerve can cause abnormal function of the nerve leading to unusual sensations and impaired muscle function.

Anatomy

Nerves are structures within the body of the deliver messages to and from the brain. Along the path of the nerve, an electrochemical impulse can travel to deliver this information. The peripheral nerves exist within the extremities of your body, and deliver messages to and from the central nervous system, consisting of the brain and the spinal cord. The peripheral nerves of the upper extremity form from branches of nerves coming off of the spinal cord.

These branches come together to form a structure called the brachial plexus which sits between the shoulder and the neck. Branches of the brachial plexus form the major peripheral nerves of the upper extremity. One of these nerves is called the radial nerve; others include the median nerve and the ulnar nerve. The radial nerve travels down the arm, past the elbow joint, into the forearm, and across the wrist all the way into the fingers.

Along the course of the radial nerve, there are small branches of the nerve within the forearm to deliver messages to the muscles and to provide sensation back to the brain.

Function

There are two major functions of the radial nerve. One of these functions is to provide a sensation that is experienced in the hand, forearm, and arm. The other major function of the radial nerve is to deliver messages to specific muscles about when to contract.

Sensory Function

The radial nerve provides sensation information from the back of the hand, forearm, and arm. Other nerves provide sensation information to other parts of the upper extremity, but the radial nerve very reliably provides sensation to the back of the hand.

Motor Function

The radial nerve provides information to the muscles of the back of the arm and forearm about when to contract. Specifically, the triceps muscle in the back of the arm and the extensor muscles of the back of the forearm are the major muscle groups that are supplied by the radial nerve.

People who have abnormal radial nerve function will often experience symptoms of numbness or tingling in areas such as the back of the hand.

People who have abnormal radial nerve function may experience weakness of these muscles and symptoms such as a wrist drop. A wrist drop occurs when the muscles in the back of the forearm will not support the wrist, and people will, therefore, hold the wrist in a flexed posture. This symptom is often seen after severe injuries to the radial nerve.

Associated Conditions

There are many types of associated conditions to the radial nerve including lacerations, contusions, fractures, and more.

Nerve Lacerations

A nerve laceration can occur when there is a penetrating injury through the skin that severs the nerve. This type of problem can occur with injuries such as stab wounds or putting your hand through a glass window. It is typically obvious to determine the location of nerve damage when there is a penetrating injury.

Nerve Contusions

Nerve contusions typically occur when there is a blunt force of trauma that causes abnormal function of the nerve. A nerve contusion can occur as a result of a sports injury or a variety of other conditions that cause direct pressure to a nerve.

Fractures

Broken bones of the upper extremity may lead to associated damage to the nerves that travel near the damaged bone. The most common type of fracture associated with injury to the radial nerve are fractures of the humerus bone. The radial nerve wraps very tightly around the humerus bone and can be injured when there is a fracture of the bone. Most radial nerve injuries associated with fractures will heal spontaneously and do not require surgical intervention.

Saturday Night Palsy

A Saturday night palsy is the name given to the abnormal function of the radial nerve after sleeping in a position that causes direct pressure against the nerve. Often this occurs when an individual falls asleep with their arm draped over an armrest on a rigid chair. The name Saturday night palsy is given because sometimes this occurs when people are intoxicated and fall asleep in awkward positions in a location other than their bed.

Crutch Palsy

Crutch palsy occurs when there is pressure on the radial nerve in the armpit as a result of using crutches improperly. In order to use crutches properly, you should be supporting your body weight through your hands, but many people will place pressure in their armpit at the top of the crutch, which can cause irritation to the radial nerve in that location.

Treatment

Whenever there is an injury to a peripheral nerve, it is important to determine the location of the injury and the cause of the nerve damage. Since nerve injuries often cause symptoms at locations other than where the nerve damage is taking place, this can sometimes be a complicated diagnosis. However, once the location of the nerve dysfunction is identified, efforts should be taken to prevent ongoing or further damage to the nerve.

Padding the top of crutches and using the crutches properly can help to prevent crutch palsy.

This may be as simple as avoiding pressure or padding the area where the nerve irritation is taking place. In situations where there is structural damage to the nerve, it may be necessary to consider surgical intervention to remove pressure on the nerve or to repair an area of damage to the nerve. Much more commonly, efforts to relieve pressure on the nerve can be performed in a nonsurgical manner.

Most often, nerve irritation can be relieved with nonsurgical interventions although nerve function may take a long time to recover, and sometimes the effects of more significant nerve damage can be permanent.

A Word From Verywell

The radial nerve is one of the major nerves of the upper extremity that supplies information about sensations and delivers messages to the muscles of the upper extremity. Abnormal function of the radial nerve can occur as a result of the injuries to the nerve. Determining the specific location of nerve damage is the first step in guiding appropriate treatment. Once the location of the nerve damage has been identified, steps can be taken to prevent ongoing or furthering of the damage to the nerve.

Frequently Asked Questions

  • Which muscle does the radial nerve innervate?
  • The radial nerve innervates the triceps muscle located on the upper arm’s back side, as well as the extensor muscles located on the forearm’s back side. As a result, the radial nerve tells these muscles when they should contract.
  • What are the upper extremity major peripheral nerves?
  • The upper extremity major peripheral nerves include the radial nerve, median nerve, and the ulnar nerve. These nerves form together into branches called the brachial plexus, which connects to the spinal cord to receive and deliver information to the brain.

The radial nerve innervates the triceps muscle located on the upper arm’s back side, as well as the extensor muscles located on the forearm’s back side. As a result, the radial nerve tells these muscles when they should contract.

The upper extremity major peripheral nerves include the radial nerve, median nerve, and the ulnar nerve. These nerves form together into branches called the brachial plexus, which connects to the spinal cord to receive and deliver information to the brain.