joi, 3 ianuarie 2013

Supernumerary Ribs

People usually have 12 ribs on each side, but the number may be increased by the presence of cervical and/or
lumbar ribs or decreased by failure of the 12th pair to form. Cervical ribs (present in up to 1% of people)
articulate with the C7 vertebra and are clinically significant because they may compress spinal nerves C8 and T1
or the inferior trunk of the brachial plexus supplying the upper limb. Tingling and numbness may occur along the
medial border of the forearm. They may also compress the subclavian artery, resulting in ischemic muscle pain
(caused by poor blood supply) in the upper limb.