Human anatomy is one of the most interesting sections in biology, which is still being studied. Despite the fact that all people should be born with the same skeleton structure, evolution does not stand still and throws up new unique cases. The body of an adult consists of 206 bones, but in this material we will focus only on one of them. We will tell you what the sternum is, what parts it consists of, what role it plays in the human body.
General information
The sternum is an unpaired bone in the human body. It has a convex front surface and, accordingly, a concave back. The sternum joins the cartilage to the ribs, thereby forming a cell. The objective of the latter is to protect against injuries of such human organs as the heart, lungs and blood vessels, through which biological fluid flows to the tissues.
Description
The sternum is an elongated flat bone and consists of three parts: the arm, body and the xiphoid process.
The first is a pen or grip. In itself, it is quite thick. At the top is the jugular notch. On the sides are recesses that serve to connect the sternum to the clavicular bones.
The sternum handle is the widest part of it.
Below the clavicular grooves on the side is the notch of the first rib, fused with its cartilage. Under it there is a small depression - the upper part of the attachment point of the second rib.
Body
This part of the sternum is almost three times longer than the handle, but narrower in width. In women, it is shorter than in men.
An interesting fact: the surface of the sternum, located in front, has traces left after the connection of its parts during embryonic development. True, they are expressed rather weakly and look like shallow transverse lines.
Synchondrosis of the sternum arm is the connection of the cartilage of the upper end of the body with the lower arm. It forms a dull open angle. The protrusion can be found at the level of articulation of the second rib with the sternum. The structure is easily palpated through the skin with your fingers.
The lateral edge of the body includes four full and two incomplete notches of ribs, which are a place for connecting the sternum to the cartilage. The first incomplete notch is located in the upper part, corresponding to the cartilage of the second rib; the other is below and coincides with the four. Full cuts fit between the above incomplete and correspond to the third to sixth ribs.
Parts of the lateral departments that lie between two recesses of the ribs located in the neighborhood have a lunate deepened shape.
Xiphoid process
This is the shortest element of a flat bone. In appearance and size, the xiphoid process is either with a bifurcated apex, or with a hole in the middle.
The apex, which has a blunt or sharp shape, can be directed both forward and backward. In the upper lateral section, there is an incomplete notch connected to the cartilage of the seventh rib.
An analogue of the articulation of the handle with the body of the sternum is the synchondrosis of the xiphoid process. In old age, the shortest element of a flat bone hardens and fuses with the second part.
The upper end of the sternum is support for the clavicles, and also connects to the clavicular mastoid muscle. The edges of the flat bone with the help of cartilage are associated with the first seven pairs of ribs.
Structure
The bones of the sternum area are composed of a spongy substance, which, in turn, is covered with a dense. The thickest part is in the manubrium (between the clavicle cartilages).
Susceptibility to injuries
A sternum fracture is a rather rare case. Such a serious injury is most often received in car accidents, for example, when the driverās chest crashes against the steering wheel of a car.
Most often, a fragmentation fracture occurs when the bones are split into several parts. Patients complain of chest pain and shortness of breath. At the site of injury, a swelling and tubercle in the form of "steps" are observed, since the deformed parts of the bone are mowed.
In the process of research, it turned out that a fracture can cause regular mechanical shock to the chest.
With trauma to this area, internal organs and tissues often suffer. Often a sternal fracture is accompanied by a bruise of the lung.
Interesting Facts
Human bones are a very interesting topic to discuss. Below are some interesting facts proving this statement:
1. There is almost no difference between the male and female skeleton. The only feature is the volume of some parts. So, for example, the size of the sternum in girls is narrower than in men.
2. In 2015, 3D modeling reached the skeleton. The world's first human sternum was printed. This breakthrough was made by university doctors from the Spanish hospital of Salamanca. They replaced the patientās damaged chest with a new, 3D-printed prosthesis.
3. Ossification of the sternum occurs already at 6 months of uterine life, and the ribs begin to harden already at 5-8 weeks.
4. Chest parameters depend on the level of skeletal muscle development. More developed muscles entail an increase in the size of the sternum.
5. By the age of 15, when sexual differences begin to manifest themselves, there is an intensive growth of the sagittal size of the sternum. In girls, the upper ribs automatically rise during inspiration, in boys, on the contrary, the lower ribs.
6. In the process of performing surgical operations on the heart, the sternum is often divided into two halves in order to reach the organ.
7. An improper sitting position of a child (for example, at a desk) can lead to deformation of the chest, as a result of which disturbances develop in the cardiovascular system, and sometimes the lungs.
Conclusion
Above we briefly told what the sternum is, and what parts it consists of. This is an important bone that connects the pairs of ribs, forming a cell that protects the internal organs from damage. Medicine does not stand still, scientists have already learned to replace irreversibly defeated parts of the skeleton, and the sternum is no exception. This allowed to save even more human lives. Nature does not cease to amaze with its wisdom. Thanks to this, humanity will continue to study the micro and macro worlds, revealing more and more secrets.