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Ulnar nerve entrapment

What is ulnar nerve entrapment?

The ulnar nerve travels from your shoulder to your little finger. It is located quite close to the skin’s surface without much muscle and bone to protect it. It is this nerve that is responsible for the painful sensation you get when you hit your funny bone. The ulnar nerve is particularly vulnerable to compression.

There are two types of ulnar nerve entrapment:

  • Cubital tunnel syndrome occurs on the inside of your elbow under a bump of bone commonly known as the funny bone (the medial epicondyle). This is the most common place for ulnar nerve entrapment.
  • Ulnar tunnel syndrome occurs when the nerve gets trapped in a canal at your wrist and is less common.

What causes ulnar nerve entrapment?

The ulnar nerve passes round the back of your elbow and through a tight tunnel between the muscles of your forearm. Entrapment occurs if this tunnel becomes too tight.

This can be the result of strain caused by repetitive movements with your arm or hand, previous elbow injury or associated with other medical conditions. Bending your elbow stretches your ulnar nerve behind the bump of your funny bone and keeping it bent for extended periods can cause irritation. This can occur if you hold a phone up to your ear for long periods of time or use a tool in a fixed position, for example. Other possible causes include an injury to your elbow, arthritis or a cyst. Wrist entrapment may also be caused by a cyst, which puts pressure on your wrist joint as it grows.

Among the factors that put you at greater risk of ulnar nerve entrapment are:

  • Obesity
  • Diabetes
  • High blood pressure
  • Autoimmune conditions
  • Thyroid conditions
  • Pregnancy

Ulnar nerve entrapment

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