Median Nerve

What is the median nerve?

The median nerve helps you move your forearm, wrist, hand and fingers. It also provides sensation to the forearm and certain parts of the hand. (Your forearm is the lower part of the arm that extends from the elbow to the hand.) Pressure on the median nerve causes carpal tunnel syndrome.

What is the purpose of the median nerve?

The median nerve provides sensory and motor (movement) functions to your forearm, wrist and hands. The nerve starts at your armpit, but its functions all take place in your forearm or hand.

The median nerve stimulates muscles in your forearm, allowing you to:

• Bend and straighten your wrists, thumbs and first three fingers.
• Rotate your forearm and hand to turn your palm downward.

The median nerve is also responsible for touch, pain and temperature sensations to the:

• Bottom (palm) side of the thumb, index and middle fingers, and part of the ring finger.
• Forearm.
• Thumb side of the palm.
• Top (nail bed) side of the index and middle fingers.

Where is the median nerve?

The median nerve is one of five nerve branches of the brachial plexus. This complex network of nerves helps you move your shoulders, arms and hands. It also sends sensory information. The brachial plexus begins as nerve roots from the cervical spine in the neck. The nerves travel behind the collarbone (clavicle) through the armpit (axilla).

You have a left and right median nerve — one for each side of the body. The median nerve starts at the armpit and:

• Connects to nerve roots in the brachial plexus that run from the C5 to C8 cervical vertebrae and the T1 thoracic vertebra.
• Runs along the inside of the upper arm between the bicep and triceps tendons, next to the brachial artery.
• Crosses in front of the brachial artery and goes under the bicipital aponeurosis, a broad band of connective tissue in the cubital fossa (triangular space opposite the elbow joint).
• Travels with the ulnar nerve down the forearm, where it branches into smaller nerves.
• Enters the hand through the carpal tunnel, a space in the wrist that holds the median nerve and tendons.

What are the median nerve branches?

The median nerve branches include:

• Muscular branch: Controls movement in the forearm’s superficial muscles, close to the skin.
• Deep (volar interosseous) branch: Controls deeper muscles in the front part of the forearm.
• Palmar branch: Sends sensory information to and from the palm, thumb and some of the fingers.

What are the other nerves in the arm?

The nerves in the arm are part of your peripheral nervous system. This system sends signals from your brain to the upper limbs, lower limbs and certain organs.

Four other nerves also aid arm movements and sensations:

• Axillary nerve.
• Musculocutaneous nerve.
• Radial nerve.
• Ulnar nerve.

What conditions and disorders affect the median nerve?

Pressure on the median nerve can cause a pinched nerve (nerve entrapment) or neuropathy (nerve damage). Or you may develop a nerve compression syndrome, such as:

• Carpal tunnel syndrome: Tissue swelling inside the carpal tunnel puts pressure on the median nerve. You may experience finger pain, wrist pain and numbness.
• Anterior interosseous nerve syndrome: Damage to the anterior interosseous nerve (a motor branch of the median nerve) causes weakness or paralysis in the thumb and index finger. It can affect your ability to pinch items between your thumb and index finger. It also causes wrist pain.
• Pronator teres syndrome: The pronator teres muscle near the elbow pinches the median nerve. This condition causes dull, aching pain in the forearm. It can also cause thumb and finger numbness or paralysis.

What are the signs of median nerve problems?

Signs of a pinched median nerve include:

• Hand or wrist pain, numbness, weakness or tingling.
• Hand pain that wakes you at night.
• Pain, burning or tingling sensation in the forearm.
• Problems grasping items, writing or using a keyboard.
• Tenderness or pain in the elbow.
• Loss of muscle in the thumb (a rare symptom).

How can I protect my median nerves?

These steps can keep your nervous system healthy:

• Ask for help to quit smoking. (Nicotine slows blood flow to your nerves.)
• Improve your sleep habits.
• Strive to maintain a healthy weight through exercise and a nutritious diet.
• Take medicines and adopt lifestyle changes to improve conditions like diabetes and high blood pressure that can damage nerves.
• Try to meditate, write in a journal or find other healthful ways to cope with stress.

When should I talk to a doctor?

You should call your healthcare provider if you experience:

• Difficulty picking up or holding on to items.
• Pain, numbness or weakness in the forearm, wrist, thumb or fingers.
• Problems performing everyday tasks like buttoning a shirt.
• Unexplained elbow or wrist pain.

A note from Cleveland Clinic

The median nerves play a critical role in wrist, hand and finger movements. They also aid sensations. When there’s pressure on the median nerve, you may develop carpal tunnel syndrome. This pinched nerve problem causes pain, weakness or numbness in the wrist, hand or fingers. Your healthcare provider can diagnose the condition and suggest treatments for symptom relief.