Number of ribs

he number of ribs was noted by the Flemish anatomist Vesalius in his key work of anatomy De humani corporis fabrica in 1543, setting off a wave of controversy, as it was traditionally assumed from the Biblical story of Adam and Eve that men's ribs would number one fewer than women's.^[1] Variations in the number of ribs occur. About 1 in 200 people has an additional cervical rib and there is a female predominance.^[2] Intrathoracic supernumerary ribs are extremely rare.^[3]

[edit] Medical issues

Rib fractures are the most common injury to the rib cage. These most frequently affect the middle ribs. When several ribs are injured, this can result in a flail chest.

Abnormalities of the rib cage include pectus excavatum ("sunken chest") and pectus carinatum ("pigeon chest"). Bifid or bifurcated ribs, in which the sternal end of the rib is cleaved in two, is a congenital abnormality occurring in about 1.2% of the population. The rib remnant of the 7th cervical vertebra on one or both sides is occasionally replaced by a free extra rib called a cervical rib, which can cause problems in the nerves going to the arm.

Rib removal is the surgical excision of ribs for therapeutic or cosmetic reasons.

[edit] Additional images

Anterior surface of sternum and costal cartilages.
		X-ray image of human chest, with ribs labeled.	Thoracic cage.
Side view of human rib cage. Seen are the 5-12 spareribs under lean muscle.