WHAT ARE CERVICAL RIBS OR FIRST RIB ABNORMALITIES?
A cervical rib is a supernumerary (or extra) rib which arises from the seventh cervical vertebra. It is a congenital abnormality located above the normal first rib. A cervical rib is present in only about 1 in 500 (0.2%) of people;] in even rarer cases, an individual may have two cervical ribs. Cervical ribs are sometimes known as "neck ribs".
Cervical ribs are a much more frequent source of thoracic outlet syndrome, and in more than 95% of these patients, the symptoms are neurologic, not vascular. Rudimentary first ribs, however, uncommonly produce exclusively neurologic symptoms and usually manifest with vascular pathology.
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cervical ribs and transverse process is shown in this diagram.
en.wikipedia.org/wiki/Cervical_rib
