Twelve pairs of curved flat bones forming the bony cage around the heart and lungs
Ribs — twelve pairs, in both sexes.
Anatomy · Bones
Rib
Twelve pairs
Thorax · chest wall
The ribs are twelve pairs of curved, flat bones that form the protective cage of the thorax. Each articulates behind with the thoracic vertebrae and ends in front in a costal cartilage. They protect the heart and lungs and move during breathing to expand the chest. Men and women both have twelve pairs.
How to spot them
- ▸A long, flat, curved bone with a head, neck, tubercle and shaft
- ▸The head has two facets and articulates with two adjacent thoracic vertebrae; the tubercle meets a transverse process
- ▸A groove runs along the inner surface of the lower edge, protecting a vein, artery and nerve
- ▸Ends in front in costal cartilage; seven pairs reach the sternum directly
What to know
A groove on the inner surface of its lower border shelters, from top to bottom, a vein, an artery and a nerve
Rib — the costal groove for the intercostal neurovascular bundle (VAN).
The first pair are short, broad and flat, with grooves on the upper surface for the subclavian vessels
Rib — rib 1 is atypical.
The lowest two pairs have no front attachment at all and end in the muscles of the abdominal wall, hence a 'floating' name
Rib — floating ribs 11 and 12.
Where two or more adjacent ones break in two or more places, a segment of the chest wall moves paradoxically as we breathe
Rib — flail chest.
An extra one may arise from the seventh neck vertebra in a small minority of people and can compress the nerves and vessels to the arm
Rib — a cervical rib, causing thoracic outlet syndrome.
Contrary to the Book of Genesis story, men do not have one fewer of these than women
Rib — both sexes have twelve pairs.
Key ideas
- Ribs 1 to 7 are 'true' or vertebrosternal ribs, attached to the sternum by their own costal cartilage; 8 to 10 attach via the cartilage above (false); 11 and 12 are floating.
- Ribs 1, 2, 10, 11 and 12 are atypical; ribs 3 to 9 are typical.
Quick-fire facts
- •Twelve pairs of ribs anchor behind to T1 to T12
- •Ribs 1 to 7 are true ribs and 8 to 12 false; 11 and 12 are also called floating
- •Costal groove order from above to below: vein, artery, nerve
- •A typical rib has a head (two facets), a neck, a tubercle and a body (shaft)
- •The costovertebral joint is at the rib head; the costotransverse joint is at the tubercle
- •The first rib is short and wide and has one facet on the head, as there is no thoracic vertebra above it
- •Rib fractures most often occur in the middle ribs; complications include damage to the lungs, spleen or diaphragm
- •The ribs have a role in ventilation, moving to expand the chest as the lungs inflate
Drill it — 8 cards
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Sources
- TeachMeAnatomy — The Ribs
- OpenStax — Anatomy and Physiology 2e, 7.4 The Thoracic Cage