There are bilateral cervical ribs. These occur in 0.5-1% of the population. About 10% of these cause compressive symptoms, ranging from nerve compression (eg pain, paresthaesia and muscle wasting along the medial border of the hand) to subclavian artery post stenotic aneurysm. The remainder are aymptomatic, but are occasionally mistaken for a sinister mass lesion on clinical examination. They may be large or small, single or bilateral, and may articulate with the first rib. If they consist only of a fibrous band they will not be visible on radiographs. They can be confused with hypoplastic first ribs; remember that the 7th cervical transverse processes point downwards, while the first thoracic transverse processes are angled upwards.