Ulnar Nerve

What is the ulnar nerve?

The ulnar nerve helps you move your forearm, hand and certain fingers. Your forearm extends from the elbow to the hand. The ulnar nerve also sends sensory information like touch, temperature and pain to the brain.

Ulnar nerve entrapment occurs when there’s pressure on the ulnar nerve. It can cause hand and finger pain and weakness.

What is the purpose of the ulnar nerve?

The ulnar nerve controls nearly all of the small muscles in the hand. Although the ulnar nerve begins at the armpit, it doesn’t perform a function until it enters the forearm.

As a motor (movement) nerve, the ulnar nerve stimulates muscles in the forearm, hand and fingers so you can:

• Bend and straighten the pinky and ring fingers.
• Grip and hold items.
• Perform fine motor tasks like writing with a pen, buttoning a shirt or turning pages in a magazine.

As a sensory nerve, the ulnar nerve gives feeling to the:

• Pinky finger.
• Side of the ring finger closest to the pinky finger.
• Palm and back of the hand on the pinky side.

Where is the ulnar nerve?

The ulnar nerve is one of five nerve branches of the brachial plexus. This nerve bundle sends sensory information and helps you move your shoulders, arms and hands.

The brachial plexus starts as nerve roots in the cervical spine in the neck. The nerves then go behind the collarbone (clavicle), through the armpit (axilla) and down the arm.

People have a left and right ulnar nerve — one to serve each arm. The ulnar nerve starts at the brachial plexus in the armpit and:

• Connects to the C8 cervical vertebra and the T1 thoracic vertebra (the middle of the brachial plexus).
• Runs down the front of the upper arm near the axillary and brachial arteries.
• Travels through the cubital tunnel, a tissue opening located under a bony bump in the elbow (medial epicondyle). This area is known as the funny bone.
• Goes beneath muscles on the inside of the forearm, running alongside the median nerve and the ulna (the long bone in the forearm).
• Divides into smaller nerve branches.
• Enters the palm on the pinky finger side through an opening called Guyon’s canal (ulnar tunnel) that also holds the ulnar artery.

What are the ulnar nerve branches?

The ulnar nerve branches include:

• Muscular branch: Controls movement in the front of the forearm.
• Dorsal cutaneous branch: Sends sensory information between the brain and the middle back of the hand, pinky finger and ring finger.
• Palmar cutaneous branch: Sends sensory information to and from the middle part of the palm and pinky and ring fingers.

What are the other nerves in the arm?

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

Four other nerves also aid arm movements and sensations:

• Axillary nerve.
• Median nerve.
• Musculocutaneous nerve.
• Radial nerve.

What conditions and disorders affect the ulnar nerve?

Ulnar nerve entrapment is the most common ulnar nerve problem. Pressure on the ulnar nerve in the elbow or wrist causes a pinched nerve, nerve (neuropathic) pain and neuropathy (nerve damage).

Ulnar nerve entrapment is a type of nerve compression syndrome. Types include:

• Cubital tunnel syndrome: Prolonged pressure affects the ulnar nerve inside the cubital tunnel in the elbow.
• Ulnar tunnel syndrome (Guyon’s canal syndrome): Pressure on the ulnar nerve inside the Guyon’s canal in the wrist causes symptoms similar to carpal tunnel syndrome (a pinched median nerve in the wrist).

Some people experience an ulnar nerve dislocation. The ulnar nerve stretches and slips out of place, often after a traumatic injury. You may feel or hear a snap in the elbow. And you might have an intense pins-and-needles feeling in the fingers and hand.

What is the link between the ulnar nerve and the funny bone?

The ulnar nerve runs underneath the first layer of skin near the elbow. When you bump your elbow against a hard surface, you may temporarily pinch the ulnar nerve. The impact causes a shock-like tingling or burning sensation known as “hitting your funny bone.”

Who is at risk for ulnar nerve problems?

People who put a lot of repeated pressure on their elbows and wrists, or perform repetitive elbow and wrist-bending movements, are more likely to develop ulnar nerve problems. Ulnar problems commonly affect:

• Baseball players, golfers and tennis players.
• Bicyclists.
• Construction workers.
• People who smoke.
• Typists, writers and others who use a keyboard heavily.
• Weightlifters.

What causes ulnar nerve problems?

In addition to overuse injuries, other causes of ulnar nerve problems include:

• Accidents and trauma.
• Arthritis.
• Broken bones and bone spurs.
• Complications from surgeries to treat carpal tunnel or shoulder fractures.
• Diabetes.
• Dislocated elbow.
• Pressure from casts or splints or using crutches.
• Sleeping with your elbows bent.
• Tumors or cysts, including ganglion cysts.

What are the signs of ulnar nerve problems?

Signs of a pinched ulnar nerve include:

• Curvature of the pinky and ring fingers (like a claw).
• Elbow pain or wrist pain.
• Hand weakness that affects your ability to grasp items or perform tasks like writing or typing.
• Muscle loss in the hand and affected fingers (a rare symptom).
• Numbness or tingling in the pinky and ring fingers.

How can I protect my ulnar nerves?

These steps can keep your nervous system healthy:

• Be sure to get enough sleep.
• Find healthy ways to cope with stress, like journaling or meditating.
• Get help to quit smoking. Nicotine and tobacco slow blood flow that keeps nerves healthy.
• Maintain a healthy weight through exercise and a nutritious diet.
• Take medicines and make lifestyle changes to manage conditions that damage nerves, such as diabetes and high blood pressure.

When should I talk to a doctor?

You should call your healthcare provider if you experience:

• Curving inward of the ring or pinky finger.
• Loss of grip strength or inability to grasp items.
• Pain, numbness or tingling sensation in the elbow, wrist, pinky finger or ring finger.
• Problems performing tasks like buttoning a shirt or writing.

A note from Cleveland Clinic

The ulnar nerves help you grip items and perform daily tasks. They also help parts of your hand and certain fingers feel sensations. Pressure on the ulnar nerve can lead to ulnar nerve entrapment in the elbow (cubital tunnel syndrome) or wrist (Guyon’s canal syndrome). The tingling feeling when you bang your elbow on a hard surface — hitting your funny bone — is an ulnar nerve response.