The human skeleton is a set of organized solid formations of bone tissue that make up the framework for other components of the human body. So, the tendons attached to the muscles are attached to the bones. The cranium and chest of a man, the pelvic area and the abdominal cavity, formed due to the muscles attached to the bones and fasciae (connective tissue membranes covering organs, vessels and nerves), serve as a receptacle for internal organs. Also dense bone tissue provides their mechanical protection from external influences, and innervation of muscles leads to a change in the position of bones and joints in the manner of the lever, thereby realizing the movement of the human body. Due to its rigidity and stability, the skeleton retains the entire mass of the human body and raises it above the ground.
Structure of the skeleton
For the convenience of studying, the skeleton is conventionally divided into 4 sections: the skeleton of the head (skull), the skeleton of the trunk, to which the human thorax and the spine are related, as well as the skeleton of free upper and lower extremities with belts. Belt of the upper limb includes scapula and clavicle, and the lower girdle - the pelvic bone of the pelvic articulation.
The human spinal column , in turn, has 5 departments and 4 bends: the cervical, thoracic, lumbar, sacral and fused vertebrae of the coccyx. Due to these bends, the spine acquires the shape of the Latin "S", and thanks to this structure, a person's straightening and maintaining balance during movement are ensured.
Anatomy of the thoracic
The human thorax has the shape of a truncated pyramid and is a natural receptacle for the heart with large vessels, lungs with trachea and bronchi, thymus, esophagus and multiple lymph nodes. Its frame consists of 12 thoracic vertebrae, sternum and 12 pairs of ribs between them. Differences of the thoracic vertebrae are small articular surfaces on the transverse processes, to which the ribs are attached. The first - the seventh pair of ribs are fixed directly to the sternum, the eighth - the tenth pair with cartilaginous ends are attached to the cartilages of the overlying ribs, and the ends of the last two pairs remain free. The special structure of the human thorax, namely the semi-mobile articulation of the ribs with the vertebrae and the sternum, supported by cartilages and a complex ligamentous apparatus, allows it to expand with inspiration and contractively contract during exhalation, participating in respiratory movements. The thoracic cavity is an anatomical space that is located inside the chest and is delimited from below by the diaphragm. Just like the human chest, it has four walls, which are strengthened by the muscles and fascia that form for the last vagina. Also in the walls there are multiple natural openings for the passage of blood and lymph vessels and peripheral nerves. People with different complexions have different forms of the chest. Therefore, the physique is determined by the magnitude of the epigastric angle, the direction of the ribs and the distance between them.