Ulnar Nerve

The ulnar nerve is one of the three main nerves in your arm, running from your neck to your hand. It provides feeling to your little finger and part of your ring finger, and controls many small muscles in your hand. This nerve is often called the "funny bone" where it passes behind your elbow, causing a tingling sensation when bumped.

What is the Ulnar Nerve?

The ulnar nerve is a major nerve that travels from your neck, through your shoulder and arm, and into your hand. It is one of three main nerves that provide movement and sensation to your arm and hand. It is well-known for the tingling sensation you feel when you bump your "funny bone" at the elbow.

The ulnar nerve originates from a network of nerves in your shoulder called the brachial plexus. From there, it travels down the inside of your arm. As it passes your elbow, it goes through a narrow space called the cubital tunnel. This tunnel is located behind the bony bump on the inside of your elbow (medial epicondyle). This is the spot commonly known as your "funny bone" (MedlinePlus, Mayo Clinic). After passing the elbow, the ulnar nerve continues down your forearm and into your hand. Nerves are like electrical cables that carry messages between your brain and the rest of your body. The ulnar nerve contains both sensory fibers, which send information about touch and pain to your brain, and motor fibers, which send signals from your brain to your muscles to make them move (Mayo Clinic). Its path makes it vulnerable to pressure or injury, especially at the elbow. Understanding its route helps explain why certain symptoms appear in specific areas of the hand and fingers when the nerve is affected (MedlinePlus).

Function

The ulnar nerve has two main jobs: providing sensation and controlling movement. It gives you feeling in your little finger and half of your ring finger, as well as parts of your palm and the back of your hand. It also helps you move many small muscles in your hand, allowing for fine motor skills and grip strength.

The ulnar nerve is responsible for sensory function in specific areas of your hand. It provides feeling to your little finger and the ring finger closest to it (the ulnar half of the ring finger). This sensation extends to the palm side and the back of the hand in these areas. This means you can feel touch, temperature, and pain in these parts of your hand because of the ulnar nerve (MedlinePlus, Mayo Clinic). In addition to sensation, the ulnar nerve controls many muscles that allow for hand movement. In your forearm, it helps control some muscles that flex your wrist and fingers. More importantly, it controls most of the small, intricate muscles within your hand itself. These muscles are essential for fine motor skills (Mayo Clinic). These intrinsic hand muscles allow you to spread your fingers apart and bring them together. They also help you pinch objects, grip things firmly, and perform delicate tasks like writing or buttoning a shirt. Without a healthy ulnar nerve, these movements can become difficult or impossible, leading to weakness and clumsiness in the hand (MedlinePlus).

Related conditions

The most common condition affecting the ulnar nerve is ulnar nerve entrapment, often called cubital tunnel syndrome. This happens when the nerve gets compressed or stretched, usually at the elbow. It can cause numbness, tingling, pain, and weakness in the hand and fingers the nerve supplies.

Ulnar nerve entrapment occurs when the nerve is squeezed or irritated as it passes through the cubital tunnel at the elbow. This is similar to how a garden hose might get kinked, restricting the flow of water. When the ulnar nerve is compressed, it cannot send signals properly, leading to symptoms (Mayo Clinic). Common symptoms include numbness and tingling, particularly in the little finger and the ring finger. You might also experience pain in your forearm or hand. Over time, if the compression continues, you may notice weakness in your hand, making it hard to grip objects or perform fine motor tasks. In severe, long-standing cases, muscle wasting (atrophy) can occur in the hand (MedlinePlus, Mayo Clinic). Several factors can contribute to ulnar nerve entrapment. These include repeatedly bending the elbow, leaning on your elbow for long periods, or direct injury to the elbow area. Bone spurs or swelling around the elbow can also narrow the cubital tunnel, putting pressure on the nerve (MedlinePlus). While less common, the ulnar nerve can also be compressed at the wrist or other points along its path, though the elbow is the most frequent site of entrapment (Mayo Clinic).

Related tests

If a healthcare provider suspects an issue with your ulnar nerve, they may recommend specific tests to check its function and identify any damage. These tests help determine if the nerve signals are traveling correctly and if the muscles it controls are working as they should. Common tests include nerve conduction studies and electromyography.

A healthcare provider will usually begin with a physical examination. They will check for tenderness, assess your range of motion, and test the strength of the muscles controlled by the ulnar nerve. They may also tap on the nerve at the elbow to see if it reproduces your symptoms, a test known as Tinel's sign (Mayo Clinic). One key diagnostic tool is a nerve conduction study (NCS). This test measures how quickly electrical signals travel through your nerves. Small electrodes are placed on your skin over the ulnar nerve, and a mild electrical impulse is applied. If the nerve is compressed or damaged, the electrical signal will travel slower or be weaker than normal, indicating a problem (MedlinePlus, Mayo Clinic). Another common test is electromyography (EMG). This test assesses the electrical activity of your muscles. A thin needle electrode is inserted into specific muscles in your hand and forearm that are controlled by the ulnar nerve. It measures the electrical signals in these muscles both at rest and during contraction. Abnormal muscle activity can indicate nerve damage or muscle problems (MedlinePlus, Mayo Clinic). Sometimes, X-rays may also be used to rule out bone problems, such as fractures or bone spurs, that could be pressing on the nerve (Mayo Clinic).

Frequently asked questions

Why is it called the "funny bone"?

The "funny bone" is not actually a bone. It's the ulnar nerve passing close to the surface behind the bony part of your elbow. When you hit it, the tingling, painful sensation is due to the nerve being temporarily compressed or irritated (MedlinePlus, Mayo Clinic).

Can ulnar nerve problems cause permanent damage?

If ulnar nerve compression is severe or lasts a long time without treatment, it can potentially lead to permanent nerve damage, muscle weakness, and muscle wasting in the hand. Early diagnosis and management are important to prevent long-term issues (Mayo Clinic).

What does ulnar nerve pain feel like?

Ulnar nerve pain often feels like numbness, tingling, or a "pins and needles" sensation, especially in the little finger and half of the ring finger. It can also manifest as a burning sensation or a dull ache in the forearm or hand (MedlinePlus).

Does the ulnar nerve affect my thumb?

The ulnar nerve primarily affects the little finger and half of the ring finger. While it controls some hand muscles that contribute to overall hand function, it does not directly provide sensation or motor control to the thumb. The median nerve is mainly responsible for the thumb (Mayo Clinic).

Can I injure my ulnar nerve without hitting my elbow?

Yes, the ulnar nerve can be injured or compressed in ways other than a direct hit. Prolonged pressure on the elbow, repetitive bending of the elbow, or even swelling and bone spurs around the cubital tunnel can cause ulnar nerve entrapment (MedlinePlus).

Is cubital tunnel syndrome the same as carpal tunnel syndrome?

No, they are different conditions. Cubital tunnel syndrome involves the ulnar nerve at the elbow, affecting the little and ring fingers. Carpal tunnel syndrome involves the median nerve at the wrist, typically affecting the thumb, index, middle, and part of the ring finger (Mayo Clinic).

Sources

• MedlinePlus — Ulnar Nerve
• Mayo Clinic — Ulnar Nerve
• Cochrane Library — Ulnar Nerve