Rib

:This article is about the bones called ribs. For other meanings, see rib (disambiguation).

Rib Anatomy

The third through ninth ribs are "typical ribs" since they share the same structure. The each have a head that has two facets separated by a crest. One head articulates with the rib's corresponding vertebra and one head articulates with the vertebra superior (above) to it. They have a neck that connects the head with the shaft. The neck meets the shaft at a tubercle. The shaft is thin, flat, and curved. The curve is most prominent at the costal angle. The concave (inside) surface has a groove to protect the intercostal nerve and vessels.

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The atypical ribs are the 1st, 2nd, and 10th to 12th.

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The first rib has a shaft that is wide and nearly horizontal, and has the shapest curve of the seven true ribs. Its head has a single facet to articulate with the first thoracic vertebra (T1). It also has two grooves for the subclavian vessels, which are separated by the scalene tubercle.

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The second rib is thinner, less curved, and longer than the first rib. It has two facets to articulate with T2 and T1, and a tubercle for muscles to attach to.

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The 10th to 12th ribs have only one facet on their head, and the 11th and 12th ribs are short with no necks or tubercles.

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