The ulnar nerve starts from the medial cord of the brachial plexus near the shoulder, runs down the inner arm and passes behind the inner side of the elbow—the spot commonly called the “funny bone.” It continues into the hand, where it powers many of the small muscles used for grip and fine control.

Location

Branches from the medial cord of the brachial plexus, mainly carrying C8 and T1 nerve fibres
Travels along the inner side of the upper arm
Passes behind the medial epicondyle at the elbow
Continues between forearm muscles and enters the hand on the little-finger side of the wrist

Function

Powers many small muscles that spread, close and coordinate the fingers
Assists some wrist and finger-flexing muscles
Helps produce a strong, controlled grip
Carries sensation from the little finger and part of the ring finger

Why It Matters at the Shoulder

Most isolated ulnar nerve irritation occurs at the elbow or wrist. However, the nerve begins in the lower part of the brachial plexus, so a plexus or lower-neck problem can sometimes produce a similar hand pattern.

The location of tingling alone cannot confirm where the nerve is irritated. Elbow position, neck symptoms, hand strength and the timing of symptoms all provide useful clues.

Common Problems

Cubital tunnel syndrome at the elbow
Compression at the wrist in Guyon's canal
Lower brachial plexus injury
Direct trauma near the elbow or along the arm

Symptoms That May Need Assessment

Persistent tingling in the little finger and ring finger
Loss of grip or finger-spreading strength
Visible wasting of the small hand muscles
Symptoms following neck, shoulder, elbow or wrist trauma

Prompt assessment is appropriate for sudden weakness, major sensory loss or symptoms accompanied by a cold or discoloured hand.

Brachial plexus — where the ulnar nerve begins
Referred neck and arm symptoms — symptoms from the neck can overlap with peripheral nerve irritation

References

StatPearls. "Anatomy, Shoulder and Upper Limb, Ulnar Nerve." https://www.ncbi.nlm.nih.gov/books/NBK499892/
StatPearls. "Ulnar Neuropathy." https://www.ncbi.nlm.nih.gov/books/NBK534226/

Ulnar Nerve