Structure and functions of the human skeleton. Structure of the skeleton
The skeleton, whose photo will be presented later,is a combination of bone elements of the body. The word itself has ancient Greek roots. In translation, the term means "dried". The skeleton is considered a passive part of the musculoskeletal system. It develops from the mesenchyme. Next, let us consider in more detail the skeleton: structure, functions, and so on.
Before talking about what featuresperforms a skeleton, it should be noted a number of distinctive features of this part of the body. In particular, some sexual characteristics of the structure are of interest. In total there are 206 bones that make up the skeleton (the photo illustrates all its elements). Almost all are united in a single whole through joints, ligaments and other joints. The structure of the skeleton of men and women is generally the same. There are no cardinal differences between them. However, differences are found only in a few altered forms or in the sizes of the individual elements and systems that they compose. The most obvious differences that the structure of the skeleton of men and women have, for example, include, for example, that the fingers and limbs of the first are somewhat longer and thicker than those of the latter. In this case tuberosity (areas of fixation of muscle fibers) are expressed, as a rule, stronger in men. In women, the pelvis is wider, and the thorax is narrower. As for sex differences in the skull, they are also insignificant. In this regard, it is often difficult for specialists to determine who owns it: a woman or a man. Along with this, in the latter, the superciliary arches and hillock protrude more strongly, the orbits are distinguished by a larger size, the paranasal sinuses are better expressed. In the male skull, the bone elements are somewhat thicker than in the female skull. Anteroposterior (longitudinal) and vertical parameters of this part of the skeleton in men are greater. Skull capacity of women of the order of 1300 cm3. In men, this figure is also greater - 1450 cm3. This difference is due to the smaller overall size of the female body.
In the skeleton, two zones are distinguished. In particular, it has a trunk and head section. The latter, in turn, includes the facial and brain parts. The cerebral part contains 2 temporal, 2 parietal, frontal, occipital and partially latticed bones. In the facial department there is an upper jaw (steam room) and a lower one. In their holes are fixed teeth.
In this department, we distinguish coccygeal (4-5 pcs.), sacral (5), lumbar (5), thoracic (12) and cervical (7) segments. Spinal arches form the vertebral canal. The pole itself has four bends. Due to this, it is possible to perform an indirect function of the skeleton associated with the upright. Elastic plates are located between the vertebrae. They help improve the flexibility of the spine. The appearance of the bends of the pillar is due to the need to soften the tremors during the movement: running, walking, jumping. Due to this, the spinal cord and internal organs are not subject to shaking. Inside the spine lies the canal. It surrounds the spinal cord.
It includes a sternum, 12 segments of the second departmentspine, as well as 12 rib pairs. The first 10 of them are joined to the breast bone by cartilages, the latter two do not have articulations with it. Thanks to the thorax it is possible to perform the protective function of the skeleton. In particular, it ensures the preservation of the heart and organs of the bronchopulmonary and partially digestive systems. Behind the rib plates have a movable articulation with vertebrae, in front (except for the lower two pairs) are connected to the breastbone by flexible cartilages. Due to this, the chest can narrow or expand with breathing.
In this part there are humeral bones,forearm (ulnar and radial elements), wrist, five metacarpal segments and finger phalanges. In general, the skeleton of the arm is divided into three sections. They include a brush, a forearm and a shoulder. The latter is formed by a long bone. The brush is connected to the forearm and consists of small wrists, a palm forming the palm, and flexible flexible fingers. Attachment of the upper limbs to the body is carried out by means of collarbones and scapulas. They form a humeral girdle.
In this part of the skeleton, 2 pelvic bones are isolated. Each of them includes the sciatic, lobny and iliac joints that have grown together. Also, the hip is referred to the lower extremity belt. It is formed by the corresponding (same name) bone. This element is considered the largest of all in the skeleton. The leg is also distinguished in the leg. The structure of this department includes two tibia - large and small. Hangs the lower extremity of the foot. It consists of several bones, the largest of which is heel. The joint with the trunk is carried out by means of pelvic elements. In humans these bones are massive and wider than in animals. Joints are used as the connecting elements of the limbs.
Types of articulations
There are only three of them. In the skeleton, the bones can be joined movably, semi-mobilely or immobile. The joint of the latter type is characteristic of cranial elements (except the lower jaw). The ribs with the sternum and the vertebrae are connected in a semi-mobile fashion. Ligaments and cartilages act as elements of articulation. The moving joint is peculiar to the joints. Each of them has a surface, a liquid present in the cavity, and a bag. As a rule, joints are strengthened by ligaments. Due to them, the amplitude of motion is limited. Articular fluid reduces friction of bone elements during movement.
What functions does the skeleton perform?
This part of the body has two tasks: biological and mechanical. In connection with the solution of the latter problem, the following functions of the human skeleton are distinguished:
- Motor. This task is performed indirectly, as the elements of the skeleton serve to attach the fibers of the musculature.
- Support function of the skeleton. Bony elements and their articulations form the skeleton. To him are attached organs and soft tissues.
- Spring. Due to the presence of articular cartilage and a number of structural features (bends of the spine, arch of the foot), amortization is carried out. As a result, shocks are eliminated and shocks are mitigated.
- Protective. In the skeleton there are bone formations, due to which the safety of important organs is ensured. In particular, the skull protects the brain, the sternum - the heart, the lungs and some other organs, the spine - the spinal structure.
Biological functions of the human skeleton:
- Hematopoietic. The bone marrow is located in the bones. It acts as a source of blood cells.
- Storing. Bone elements serve as depots for a large number of inorganic substances. They include, in particular, iron, magnesium, calcium, phosphorus. In this regard, the bones are involved in maintaining a stable mineral composition within the body.
If the body's position is incorrect duringa prolonged period (for example, a long sitting with a tilted head at a table, an uncomfortable posture, etc.), and also against a background of a number of hereditary causes (especially in combination with nutritional errors, insufficient physical development), a breach of the retention function of the skeleton may occur. In the early stages, this phenomenon can be eliminated quite quickly. Nevertheless, it is better to prevent it. For this purpose, experts recommend choosing a comfortable position at work, regularly doing sports, gymnastics, swimming and other kinds.
Another fairly commona pathological condition is deformation of the foot. Against the background of this phenomenon there is a violation of the motor function of the skeleton. Deformation of the foot can occur under the influence of diseases, become a consequence of injuries or prolonged overload of the foot during the growth of the body.Under the influence of strong physical activitya bone fracture may occur. Trauma of this type can be closed or open (with a wound). About 3/4 of all fractures are in the hands and feet. The main sign of injury is severe pain. Fracture can provoke subsequent deformation of the bone, a violation of the functions of the department in which it is located. If there is a suspicion of a fracture, the victim should be provided with an ambulance and hospitalized. Before taking any action, the patient is referred for radiographic examination. In the course of diagnosis, a site of localization of the fracture, presence and displacement of bone fragments is revealed.