Median Nerve: What to Know

Medically Reviewed by Dany Paul Baby, MD on October 04, 2022
5 min read

The median nerve is one of many peripheral nerves that extend throughout the body. This nerve in particular provides important control of the hand, wrist, and forearm and is commonly associated with injuries such as carpal tunnel syndrome. 

The median nerve is a peripheral nerve that sends motor commands to and receives sensory information from the forearms and hands. It is critical for moving the bottom of your arm, including your wrist and hand. The median nerve also detects sensory information from these areas, which is sent back to the brain and spinal cord. 

The median nerve isn’t the only nerve that helps move your hand, though. Its partners, the ulnar nerve and radial nerve, also direct hand and wrist movement and transmit sensation.

The peripheral nervous system is made up of numerous bundles of individual neurons. These bundles, called nerves, send information to the brain and spinal cord about the world around us and transmit signals back out to the body, activating muscles so that we can perform functions like breathing, eating, and moving. 

As a peripheral nerve, the median nerve is important for both movement and sensation. Median nerve anatomy helps inform us about its function. 

Movements are caused by the median nerve. Nerves send electrical pulses that stimulate muscles to contract or flex, causing movement. The median nerve specifically innervates parts of the forearm, wrist, and hand, allowing each muscle to contract or flex when needed.

The median nerve is responsible for several different movements in the lower arm, including: 

  • Bending and straightening of the wrist
  • Bending and straightening of the thumb, index, and middle fingers
  • Rotating the forearm

Sensations are detected by the median nerve. In addition to moving parts of the lower arm, the median nerve is also critical for detecting sensory information, such as the texture of an object you’re holding or the heat that you encounter if you’ve grabbed a hot pan.

The areas that provide sensory information to the median nerve include:

  • The palm side of the thumb, index, middle fingers, and half of the ring finger
  • The area above the second knuckle (closest to the nail) on your thumb, index, and middle fingers, as well as part of the ring finger
  • The part of the palm closest to the thumb
  • Parts of the forearm

The median nerve begins in the spinal cord's upper section, known as the cervical spine. Several nerves that travel to the arms and hands, including the median nerve, form a bundle of nerves in an area of the shoulder. They are referred to as the brachial plexus. 

Each nerve begins to branch out as it travels down the shoulders, through the armpits, and into the arms. The median nerve runs along the inside of the arm in a bundle with the brachial artery. As it approaches the elbow, the median nerve crosses over the brachial artery and under the tissue that connects the bicep to the forearm. 

Although the median nerve travels throughout the entire arm, it does not have much function until it reaches the forearm, wrist, and hand. The median nerve branches further when it reaches the wrist, though, and extends connections into the thumb, index finger, and middle finger.

The median nerve is important for moving your lower arm and detecting sensations such as touch and heat from your hand, wrist, and forearm. Injuries to the median nerve can impact movement and sensation in these areas.

Common signs of a median nerve injury may include:

  • Pain, weakness, or numbness in the hand, wrist, or forearm
  • A burning sensation in the lower part of the arm
  • Pain or tenderness around the elbow
  • Difficulty using your hand to grab items

If you’re experiencing severe pain or loss of sensation in your hand, wrist, or arm, contact your medical provider for treatment.

Like other nerves, the median nerve can be overextended or compressed. Several common conditions affecting the median nerve are due to compression (pinching) of the nerve.  

Common conditions caused by compression or other damage to the median nerve include:

Carpal tunnel syndrome. Carpal tunnel syndrome occurs when the median nerve becomes compressed at the wrist. Symptoms of carpal tunnel syndrome include pain or numbness in the fingers and wrist. Carpal tunnel syndrome can vary in severity, ranging from mild injuries that cause some numbness or tingling to severe injuries that disrupt the normal functioning of the hand.

Pronator teres syndrome. The pronator teres muscle, located near the elbow, can compress the median nerve. Compression at this level can cause pain in the forearm and paralysis or numbness in the fingers.

Anterior interosseous nerve syndrome. Compression of the anterior interosseous nerve, one branch of the median nerve, can cause paralysis in the fingers in more severe cases. Less severe compression may still cause weakness in the fingers, making it difficult to grab objects. 

Elbow trauma. Trauma to the elbow, such as a fracture, can affect the median nerve. While the fracture is healing, the median nerve can be stretched, compressed, or even torn. Damage to the median nerve can then cause pain and muscle weakness throughout the forearm and hand.

If you’re experiencing muscle weakness, pain, or a loss of sensation in your lower arm or hands, consult your physician for a diagnosis and treatment.

There are several things you can do to help keep your median nerves healthy and functioning as they should. 

Try to maintain a healthy lifestyle. Eating a nutritious diet, getting enough sleep, and exercising are all important for maintaining a healthy body and healthy nerves.

If you’re a smoker, seek out resources to help you quit. Nicotine slows blood flow to your nerves, preventing them from getting the nutrients they need to function properly. If you’re a regular smoker, ask for help or seek out resources to quit smoking. 

See your doctor sooner rather than later. Some median nerve injuries simply can’t be prevented, so it’s important to consult your physician as soon as you think something may be wrong. Mild median nerve injuries, such as mild carpal tunnel syndrome, can often be treated with noninvasive interventions, such as wrist splints.

Ignoring even a mild injury may cause more damage to the nerve and increase the severity of the injury over time, so speak to your doctor and ask about treatment options as soon as you notice a problem.