What Unpaired Bones Are In The Human Body

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What Unpaired Bones Are In The Human Body
What Unpaired Bones Are In The Human Body

Video: What Unpaired Bones Are In The Human Body

Отличия серверных жестких дисков от десктопных
Video: All bones of the body in one chart ( Amazing concept). 2023, February

The human body, like the bodies of many other higher animals, is characterized by bilateral symmetry. However, it cannot be called ideal. Not all organs have their "double" located symmetrically. This also applies to the structure of the skeleton.

Human skeleton
Human skeleton

Some bones in the human skeleton are paired. The bones of the pelvis, upper and lower extremities, clavicle, scapula are located symmetrically. This also applies to the ribs - a person has 12 pairs of them.

There was once a belief, which some people still share today, that men have one rib less than women. The legend connects this with the biblical story of the creation of Eve from the rib of Adam. Back in the 16th century, the “father of modern anatomy” A. Vesaliy proved that this is not the case: men and women have the same number of ribs.

However, sometimes people are born with a 13th unpaired rib. This anomaly is called Adam's rib syndrome, although it occurs with the same frequency in both men and women. Living with an extra rib is not easy, it squeezes nerves, blood vessels and even internal organs, interfering with their work and causing numbness in the hands. Such people undergo an operation to remove an unpaired rib.

Unpaired skeletal bones

Unpaired bones are those that are located in the middle of the skeleton.

Unpaired bones include all the vertebrae that make up the vertebral column: 7 cervical vertebrae, 12 thoracic and 5 lumbar.

At the base of the spine in the form of a wedge between the pelvic bones is a large triangular bone - the sacrum. This is one of those bones by which you can tell if the skeleton is female or male. In women, the sacrum is shorter and wider than in men, and the male sacrum is more curved than the female.

The upper part of the sacrum is connected to the last vertebra, and the lower part is connected to the coccyx, another unpaired bone. The tailbone also consists of several rudimentary vertebrae. This is the "remnant" of the tail, inherited by humans from evolutionary ancestors.

Despite its rudimentary origin, the tailbone is not a useless part of the skeleton. Some muscles are attached to it, it takes on some of the load when a person sits or bends over.

Unpaired skull bones

The human skull is a highly complex structure made up of many bones. Some of them are also unpaired.

The skull is divided into two sections - cerebral and facial. Unpaired facial bones - occipital, frontal and wedge-shaped. Special attention should be paid to the frontal bone. It does not immediately become a single whole; at the birth of a person, this bone consists of two halves connected by a seam. In this form, it is easier for the skull to pass through the birth canal, the likelihood of birth injuries is less. By the age of five, the seam is overgrown, and only 10% of people have it until the age of 40.

The unpaired bones of the facial region are the vomer that forms the lower posterior part of the bony nasal septum, the hyoid bone located under the muscle of the tongue and resembles a horseshoe in shape, as well as the lower jaw. This is a very interesting bone. Of all the bones of the skull, only it is movably articulated with other bones, and most importantly, a number of its features "elevate" a person above other primates.

When artists want to depict a person endowed with great physical strength, but not distinguished by intelligence, they usually draw a person with a large, massive lower jaw. This sign is not accidental, it evokes an association with a monkey. Indeed, the size and mass of the lower jaw relative to the skull as a whole is much smaller in humans than in monkeys. Its small size made it possible for articulate speech. True, chewing food turned out to be difficult, which forced human evolutionary ancestors to create stone knives and master the processing of food on fire. Thus, the small size of the lower jaw has become one of the "engines" of human development.

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