Cervical rib

How it works

People normally have twelve pairs of ribs. Each pair grows from a bone of the spine in the chest. The neck has seven bones of its own, called cervical vertebrae. In the embryo, every vertebra has a small rib-like bud. In the chest the buds grow into ribs. In the neck they normally stop and merge into the vertebra¹. In some people the bud on the seventh neck vertebra keeps growing and becomes an extra rib¹.

A cervical rib can be a short stub of bone or a full rib that curves round to join the first normal rib¹. It can also be an incomplete rib attached to a band of fibrous tissue⁴. It sits above the collarbone, close to the nerves and the artery that run from the neck into the arm.

A cervical rib is more common in women⁴. It is often on one side only³. Most cause nothing at all. They are found by accident, on a chest X-ray taken for something else.

How common it is

The 1.1% figure is the rate in healthy people from a 2018 review that pooled 141 studies³. Older reference figures are lower, 0.2% to 0.5%¹. Most cervical ribs cause no symptoms, so many people who have one never find out¹.

Is it a problem?

Usually not. In a small number of people the extra rib presses on the nerves or blood vessels going to the arm. This is one cause of thoracic outlet syndrome². The signs are tingling, numbness, or aching in the arm and hand, or a hand that goes pale and cold, especially with the arm raised. If you have a known cervical rib and these symptoms, see a doctor. The rib can be removed by surgery if it is the cause². Without symptoms, nothing needs to be done.

History and culture

In some snakes and legless lizards, ribs reach as far up as the second neck vertebra¹. Crocodiles have ribs on every neck vertebra¹. The human cervical rib is a reminder that each neck vertebra still carries a small rib part, which in mammals normally fuses into the vertebra¹.