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Rib

life science Maturity 9-11 Next article →

Ribs are long, curved bones that make up the rib cage. This cage is part of the axial skeleton. It works like a protective shield for your body. The ribs surround the thoracic cavity to guard the heart and lungs. These are vital organs that need safety to work well. In some animals like snakes, the ribs protect the whole body.

Ribs labeled
Ribs labeled

Breathing is a special way the ribs work with your body. A muscle called the diaphragm sits below the rib cage. When this muscle contracts, it moves to change the space inside your chest. This action expands the thoracic cavity. Expanding this space helps draw air into your lungs. The ribs can move up or down to help this happen. This makes sure you can take in the air you need.

Ribs start to form while a baby is still growing in the womb. This happens during the fourth week of development. Small parts called costal processes grow from the vertebrae. By the fifth week, these parts become longer to form the ribs. During the sixth week, the ribs begin to separate from the spine. At first, the ribs are made of cartilage. Later, they turn into hard bone through a process called endochondral ossification.

Eptesicus fuscus ribcage
Eptesicus fuscus ribcage

Humans usually have 24 ribs, which are organized into 12 pairs. The first seven pairs are called true ribs because they join the sternum. The next five pairs are called false ribs. The very last two pairs are called floating ribs because they do not attach to the sternum. Some people, about 1 in 500, have an extra rib near the neck. This is known as a cervical rib.

Dog anatomy lateral skeleton view (full)
Dog anatomy lateral skeleton view (full)

Different animals have very different rib structures. Dogs usually have 26 ribs to support their bodies. Turtles have only eight pairs of ribs. These ribs actually grow into their hard outer shell. Birds have ribs with a wide projection called an uncinate process. This helps them attach their shoulder muscles. Even humans use ribs in interesting ways outside of the body. You might eat a rack of lamb or pork ribs as food.

Ribs labeled
Ribs labeled
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🖼️ Images & Media (3)
File:Ribs labeled.png
Ribs labeled.png
File:Dog anatomy lateral skeleton view (full).jpg
Dog anatomy lateral skeleton view (full).jpg
File:Eptesicus fuscus ribcage.jpg
Eptesicus fuscus ribcage.jpg
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