The sternum is a long, flat bone located in the middle of a person's chest.

In the sternum

or
the sternum
is a long flat bone located in the central part of the chest. It connects to the ribs through cartilage and forms the front of the rib cage, thereby helping to protect the heart, lungs, and major blood vessels from injury. Roughly shaped like a tie, it is one of the largest and longest flat bones in the body. Its three regions are the manubrium, the body, and the xiphoid process.[1] The word "sternum" comes from the ancient Greek στέρνον (stérnon), meaning "chest".

General information

The sternum is an unpaired bone in the human body. It has a convex front surface and a correspondingly concave rear surface. The sternum is attached by cartilage to the ribs, thus forming a cage. The task of the latter is to protect against injury to human organs such as the heart, lungs and blood vessels, through which biological fluid enters the tissues.

Helpful information

Every person is unique and inimitable. In this case, various anomalies are often encountered - for example, doubling of an organ, changes in its shape and size. It is surprising that this often goes unnoticed and does not affect health in any way.

It is also important that when any of the paired organs is removed, the other of this pair can take over its functions. And this almost always happens. At the same time, the person himself will feel the same as before.

The potential and endurance of the body are amazing; it is fragile and strong at the same time. Biological scientists and doctors have to find out the answers to a large number of mysteries of the human body. Work in this area is ongoing.

As you can see, the structure of the human body is simple and complex at the same time. Researchers still cannot fully unravel all the mysteries of the body. A person is able to carry out higher nervous activity thanks to the cerebral cortex, which is inaccessible to other biological species.

For these reasons, it is important for people to have at least a general understanding of their structure, which will help throughout their life, especially when checking their own health.

Description

The sternum is an oblong flat bone and consists of three parts: the manubrium, the body and the xiphoid process.

The first is the handle or handle. By itself it is quite thick. At the top is the jugular notch. There are notches on the sides that serve to connect the sternum to the clavicle bones.

The manubrium of the sternum is its widest part.

Below the clavicular notches on the side there is a 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.

Content

• 1 Structure 1.1 Manubrium
• 1.2 Body
• 1.3 Xiphoid process
• 1.4 Joints
• 1.5 Development

Body

This part of the sternum is almost three times longer than the manubrium, but narrower in width. In women it is shorter than in men.

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 rather weakly expressed and look like shallow transverse lines.

Synchondrosis of the manubrium of the sternum is the connection of the cartilage of the upper end of the body with the lower manubrium. 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 can be easily felt with fingers through the skin.

The lateral edge of the body includes four complete and two incomplete rib notches, which are the site for the connection of the sternum with cartilages. 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 four. Complete cuts are placed between the above-described incomplete ones and correspond to the third to sixth ribs.

Parts of the lateral sections, which lie between two notches of the ribs located next door, have a semilunar in-depth shape.

Human chest: functions

• As has been repeatedly noted, the main function of the human chest is to protect internal organs from external factors. However, the human body is a single whole, each part of which directly depends on the other. In addition to its direct purpose, the chest is a kind of attachment point for many types of muscles responsible for other important parts of the human body.
• The ribs of the chest also contain red bone marrow, which is the most important organ of the hematopoietic system. It produces new blood cells to replace dying or dying ones and is one of the main organs for the regeneration of cells of the immune system.

Image 5. Basic functions of the chest

• Therefore, if, during a strong blow, the chest fulfilled its main function, protecting the internal organs, but was itself damaged, the person may experience health problems. Their degree depends on the severity of the chest injury and the age of the victim. This can be fraught with fever, loss of immunity, neuralgia as a result of damage to the soft tissues of the chest, as well as pleurisy and other more dangerous diseases.

xiphoid process

This is the shortest element of the flat bone. In appearance and size, the xiphoid process has either a bifurcated apex or 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 that connects to the cartilage of the seventh rib.

An analogue of the articulation of the handle with the body of the sternum is synchondrosis of the xiphoid process. In old age, the shortest element of the flat bone hardens and fuses with the second part.

The upper end of the sternum provides support for the collarbones and also connects to the cleidomastoid muscle. The edges of the flat bone are connected by cartilage to the first seven pairs of ribs.

Human chest: soft tissue

As previously mentioned, the human chest consists not only of bone structures, but is also equipped with multiple muscle tissues, which give it the greatest plasticity and force the respiratory system to function properly. In addition, they serve as an additional protective element of the internal organs, filling the empty areas between the ribs and turning the chest into one dense protective structure.

Also, with the help of muscle tissue, the chest is attached to the shoulder girdle, thanks to which the ribs receive their mobility. Under normal conditions, these muscles are not used by the body. They begin their work only in case of physical or emotional stress to enhance breathing.

Image 3. Soft tissues of the chest: cross-section of the diaphragm

The main muscles of the chest can be divided into two elements:

• The diaphragm is an unpaired muscle that serves as a separating element between the thoracic and abdominal cavities, controls internal pressure and is responsible for the correct functioning of the lungs (their expansion and contraction). Conventionally, the border of the diaphragm runs along the lower edge of the ribs.
• Intercostal muscles are tissues that play a significant role in the functioning of the respiratory system. They also connect the ribs to each other, and during the process of breathing they tend to contract and expand.

Susceptibility to injury

A sternal fracture is a fairly rare occurrence. This serious injury occurs most often in car accidents, for example, when the driver's chest hits the steering wheel of the car.

The most common fracture is a comminuted fracture, when the bones are broken into several pieces. Patients complain of chest pain and difficulty breathing. At the site of injury, there is a swelling and a bump in the form of “steps”, as the deformed parts of the bone are beveled.

During the research, it turned out that regular mechanical blows to the chest can also cause a fracture.

When this area is injured, internal organs and tissues are often damaged. Often a fracture of the sternum is accompanied by a contusion of the lung.

Other animals

The sternum in vertebrate anatomy is a flat bone that lies in the middle anterior part of the rib cage. it is endochondral in origin.[10] It probably first appeared in quadrupeds as an extension of the pectoral girdle; it is not found in fish. In amphibians and reptiles it is usually a shield-shaped structure, often composed entirely of cartilage. It is absent in both turtles and snakes. In birds it is a relatively large bone, usually with a huge keel projection to which the flight muscles are attached.[11] Only in mammals does the sternum take on the elongated, segmented shape seen in humans.

Arthropods

Main article: Sternum (arthropod anatomy)

In arachnids, the sternum is the ventral (lower) part of the cephalothorax. It consists of a single sclerite located between the coxa and opposite the carapace.

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 peculiarity is the volume of some parts. 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 has been printed. This breakthrough was made by university doctors from the Spanish Salamanca Hospital. They replaced a patient's damaged ribcage with a new 3D printed prosthesis.

3. Ossification of the sternum occurs already at the 6th month of uterine life, and the ribs begin to harden already at 5-8 weeks.

4. The parameters of the chest depend on the level of development of skeletal muscles. More developed muscles entail an increase in the size of the sternum.

5. By the age of 15, when gender differences begin to manifest themselves, there is an intensive increase in the sagittal size of the sternum. In girls, the upper ribs automatically rise during inhalation, while in boys, on the contrary, the lower ribs rise.

6. During heart surgery, the sternum is often divided into two halves to reach the organ.

7. Incorrect sitting position of a child (for example, at a desk) can lead to deformation of the chest, as a result of which disorders develop in the cardiovascular system, and sometimes in the lungs.

Etymology

English sternum

this is a translation of the Ancient Greek στέρνον,
Sternon
.[12] The Greek writer Homer used the term στέρνον to refer to
the male breast
,[13][14] and the term στῆθος,
stithos
to refer to
the breasts of both sexes
.[13][14] The Greek physician Hippocrates used στέ ρνον for designations
chest
,[13][14] and στῆθος to
sternum
.[13][14] The Greek physician Galen was the first to use στέρνον in the present meaning of
sternum
.[13][14]

The sternum as a strong bony part of the chest[15] may be related to the ancient Greek στερεός / στερρός, (stereo / stereo)

,[15] meaning
solid
or
solid
.[14] The English term "sternum" is actually more similar to the Latin
ribcage
,[16][17] comes from Classical Latin
os
, bone[18] and
ribcage
, chest or chest.[18]
Oddly enough, the rib cage
is also used in classical Latin as
the sternum
.[18]