Wednesday, November 14, 2012

How many ribs do we have?

Biblically speaking, it is said that a woman was created out of a man’s rib. This is the origin of the false belief that women have more ribs then men. But in reality, each human being (both man and woman) has a total of 24 ribs. The ribs serve as a protection to the human’s heart, lungs, kidneys, and other internal organs. The protective cage-like formation of human ribs plays a vital role in the human skeleton. However, on some animals, it acts as a protection and support for their whole body.

Each rib is connected to the spinal bone at your back. The first 14 ribs (first 7 sets) are called “true ribs”. These ribs are directly attached to the sternum or breastbone by way of costal cartilage. The first pair of the true ribs is the shortest among all the ribs. This rib is hard to locate. It is shaped like a letter “C” and connected just below your neck. The remaining 6 pairs of the true ribs have a more usual appearance.

The next 5 sets of the human ribs are known to be “false ribs”. The first 3 sets (costae spuriae, vertebrochondral ribs, VIII-X) have a typical cartilaginous attachment to the sternum, while the eleventh and twelfth pairs are best known as the “floating ribs”. They don’t have an anterior link to the breastbone. Some people call them vertebral ribs since they are linked to the vertebrae. There are some instances that human beings may have 3 pairs of floating ribs, while some may also have a missing pair of floating ribs. These uncommon instances occur only in cases of genetic mutations. This kind of situation is not alarming though.

The spaces found in-between the human ribs contain intercostals nerves, arteries, and muscles. They are known to be as “intercostals spaces”.

The thoracic diaphragm sets apart the ribcage from the lower abdomen. Your thoracic diaphragm regulates your breathing. Every time you inhale, your muscles raise the cage up. The rib cage goes down when you exhale. The muscles that support this activity are sternocleidomastoid, pectoralis major and minor, and scalene.

The thoracic cavity and ribcage of the body are widened when the body’s diaphragm contracts. This activity draws air into your lungs and reduces the intra-thoracic pressure. This expansion activity is known as “belly breathing”. The normal adult rib cage extends its circumference by 3 to 5 cm during the inspiration.

The broadening of ribcage among males is due to the effects of testosterone during their puberty stage. This is the reason why males have wider shoulders and chests compared to females. It permits them to inhale a huge amount of air to bring in oxygen into their muscles.

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