Ribs
Costae
The ribs are the twelve pairs of curved bones that run from the thoracic spine around the chest, forming the rib cage that shields the heart and lungs.
At a glance
About the ribs
There are twelve ribs on each side, curved bars of bone that make up most of the wall of the chest. Each is numbered after the thoracic vertebra it meets at the back, from the first rib under the clavicle to the twelfth at the top of the lumbar region. At the front each ends in a costal cartilage. The first seven pairs are true ribs, whose cartilages reach the sternum directly. The last five are false ribs: the eighth to tenth join the cartilage above them, while the eleventh and twelfth, the floating ribs, end free in the muscles of the flank.
A typical rib has a head, a neck, a tubercle and a long shaft. The head carries two facets separated by a small crest: the lower, larger one meets the vertebra of the same number and the upper one meets the vertebra above. A short flattened neck about 3 cm long leads to the tubercle, whose smooth part meets the transverse process of its own vertebra. A little further out the shaft turns sharply forward at the angle, where it is also twisted along its length; the angle anchors the iliocostalis, and the rough stretch between angle and tubercle the longissimus. Along the lower inner edge a costal groove shelters the intercostal vein, artery and nerve.
The series changes from top to bottom. Length increases down to about the seventh rib and then falls away. The tubercle is prominent in the upper ribs and fades below, while the gap between tubercle and angle widens from the second rib to the tenth. The first rib is short, broad and flat; the second is a transitional form; the third to ninth are typical; and the tenth to twelfth have a single facet on the head.
Clinically, the costal groove explains why needles and drains enter the chest just above a rib rather than below it, and the first rib is central to thoracic outlet compression of the vessels and nerves to the arm.
Anthromica
See the ribs where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
