A<unk>  in humans is an extra<unk>  which arises from the seventh<unk>  vertebra. Their presence is a congenital abnormality located above the normal first<unk> . A<unk>  is estimated to occur in 0.2% to 0.5% (1 in 200 to 500) of the population. People may have a<unk>  on the right, left or both sides. Most cases of<unk> s are not clinically relevant and do not have symptoms;<unk> s are generally discovered incidentally, most often during x-rays and CT scans. However, they vary widely in size and shape, and in rare cases, they may cause problems such as contributing to thoracic outlet syndrome, because of pressure on the nerves that may be caused by the presence of the<unk> . A<unk>  represents a persistent ossification of the C7 lateral costal element. During early development, this ossified costal element typically becomes re-absorbed. Failure of this process results in a variably elongated transverse process or complete<unk>  that can be anteriorly fused with the T1 first<unk>  below.
Cervical rib
Boracic lint
Triangles of the neck
Iliac spine
Posterior triangle of the neck
Anterior triangle of the neck
Thoracic inlet
Costovertebral angle