Definition of Cervical rib

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Cervical rib: A supernumerary (extra) rib which arises from the seventh cervical vertebra. It is located above the normal first rib. A cervical rib is present in only about 1 in 200 (0.5%) of people. It may cause nerve and artery problems.

There are normally 12 pairs of ribs in all. Each pair of ribs is attached to the building blocks of the spine (the vertebrae) in the back. The 12 normal pairs of ribs consist of:

True ribs: The first seven ribs attach to the sternum (the breast bone) in the front and are known as true (or sternal) ribs.
False ribs: The lower five ribs do not directly connect to the sternum and are known as false ribs.

The presence of a cervical rib means the individual has 13 ribs: 1 cervical rib + 7 true ribs + 5 false ribs = 13 ribs.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=2684
Last Editorial Review: 3/26/1998 2:24:00 PM

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