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In anatomy, the ribs (la. costae) are those bones which form the rib cage, these surround the thorax (chest) of vertebrates. The function of the ribs is to protect the lungs, heart, and other internal organs of the thoracic cavity.

The human skeleton has 24 ribs, 12 on each side (a small proportion have one pair more or less). They are attached to the vertebral column behind, and the first seven pairs are connected to the sternum in front and are known as true ribs (C. verae, I-VII). The eighth, ninth, and tenth are attached in front to the cartilaginous portion of the next rib above and are known as false ribs (C. spuriae, VIII-X). The lower two, that is the eleventh and twelfth , are not attached in front and are called floating ribs (C. fluitantes, XI-XII). The spaces between the ribs are known as intercostal spaces; they contain the intercostal muscles, nerves, and arteries. The rib cage allows for breathing due to its elasticity.

There is a legend that male humans have one rib fewer than female humans. This is false, and originates from the Bible's description of the creation of Eve (from the rib of Adam).

See also: breastplate, zootomy