Human anatomy is one of the most interesting sections in biology, which continues to be studied to this day. Despite the fact that all people should be born with the same skeletal 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 on only 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 is attached by cartilage to the ribs, thus forming a cage. The task of the latter is to protect against injury such human organs as the heart, lungs and blood vessels, through which the biological fluid enters the tissues.
Description
The sternum is an oblong flat bone and consists of three parts: the handle, the body and the xiphoid process.
The first is a handle or handle. By itself, it is quite thick. At the top is the jugular notch. Notches are located on the sides, which serve to connect the sternum with the clavicular bones.
The handle of the sternum is the widest part of it.
Below the clavicular notches 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. It is shorter for women than for men.
Interesting fact: the surface of the sternum, located in front, has traces left after the connection of its parts during the period of embryonic development. True, they are rather weakly expressed and look like shallow transverse lines.
Synchondrosis of the handle of the sternum is the connection of the cartilages of the upper end of the body with the lower handle. It forms an obtuse open angle. The protrusion can be found at the level of the articulation of the second rib with the sternum. The structure is easily felt through the skin with fingers.
The lateral edge of the body includes four complete and two incomplete cuts of the ribs, which are the place for connecting the sternum with cartilage. The first incomplete recess is located in the upper part, corresponding to the cartilage of the second rib; the other is below and coincides with the fourth. Full cuts fit between the above described incomplete ones and correspond to the third - sixth ribs.
Parts of the lateral sections that lie between the two notches of the ribs,located in the neighborhood, have a semilunar deepened shape.
Xioid process
This is the shortest element of a flat bone. In appearance and size, the xiphoid process is either with a forked apex or with a hole located in the middle.
The top, which has a blunt or sharp shape, can be directed both forward and backward. In the upper lateral section, there is an incomplete notch that connects to the cartilage of the seventh rib.
An analogue of the articulation of the handle with the body of the sternum is the xiphoid process synchondrosis. In old age, the shortest element of the flat bone hardens and fuses with the second part.
The upper end of the sternum is the support for the collarbones and also connects to the clavicular mastoid muscle. The edges of the flat bone are connected with the first seven pairs of ribs with the help of cartilage.
Structure
The bones of the sternum are composed of a spongy substance, which, in turn, is covered with a dense one. The thickest part is in the manubrium (between the cartilages of the clavicle).
Injury susceptibility
Fracture of the sternum is a fairly rare case. This type of serious injury is most common in car accidents, such as when the driver's chest hits the steering wheel.
The most common is a comminuted fracture, when the bones are crushed into several pieces. Patients complain of chest pain and difficulty breathing. At the site of injurythere is swelling and a bump in the form of "steps", as the deformed parts of the bone are bevelled.
In the process of research, it turned out that regular mechanical shocks to the chest can also cause a fracture.
When this area is injured, internal organs and tissues often suffer. Often, a fracture of the sternum is accompanied by a contusion of the lung.
Interesting facts
Human bones are a very interesting topic of discussion. Below are some interesting facts that prove 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 got to 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 patient's damaged chest with a new 3D-printed prosthesis.
3. The sternum ossifies as early as 6 months of gestation, and the ribs begin to harden as early as 5-8 weeks.
4. The parameters of the chest depend on the level of development of skeletal muscles. More developed musculature entails an increase in the size of the sternum.
5. By the age of 15, when sex differences begin to manifest themselves, there is an intensive growth in the sagittal size of the sternum. In girls, the upper ribs rise automatically during inhalation, inboys, on the contrary, are lower.
6. During heart surgery, the sternum is often split in two to reach the organ.
7. An incorrect sitting position of a child (for example, at a desk) can lead to a deformity of the chest, resulting in disorders in the cardiovascular system, and sometimes in the lungs.
Conclusion
Above, we briefly described what the sternum is and what parts it consists of. This is an important bone that connects pairs of ribs, forming a cage that protects internal organs from damage. Medicine does not stand still, scientists have already learned how to replace irretrievably damaged parts of the skeleton, and the sternum is no exception. This allowed to save even more human lives. Nature never ceases to amaze with its wisdom. Thanks to this, humanity will continue to study the micro- and macroworlds for a long time, revealing more and more secrets.
