Skeleton of the lower limbs of man: structure and functions
The human musculoskeletal system isA complex system that works continuously from birth to the last day of life, performing a number of vital functions. Maintaining a constant body shape, upright, protecting organs and tissues are its main functions. Interacting with other departments and organs of the human body, they create and maintain its integrity and help to adapt in various conditions of life.
The entire musculoskeletal system of the human body is represented by two sections: the passive (skeleton and its parts) and the active (muscular system).
The skeleton is a collection of all the bones of the body, which are joined together by joints and ligaments.It forms a kind of skeleton that fulfillsprotective function for internal organs and body systems. Also, the skeleton provides support, and through it the body moves in space and its position is determined. The motor function is performed by means of the combined coordinated actions of bones, joints, muscles and nerve endings. The basic function is that the bones of the skeleton serve as the basis for attaching soft tissues and organs, which allows them to stay in their places at all times and not to fall off. The protective function is provided by the presence of cavities in which the vital organs of the human body are located. So, the heart and lungs are closed by the thorax, the brain is hidden in a strong cranium. Also, the skeleton is inherent in the blood-forming function - in the bones of the skeleton is located the red bone marrow, which takes part in the hematopoiesis.
The skeleton of any person consists of more than 200bones. They are formed by bone tissue, which is represented by a large number of mineral and organic compounds. Minerals give bones hardness and strength, and organic substances are responsible for flexibility and elasticity. The proportion of inorganic compounds in the bones of the skeleton accounts for about 70%. With age, this figure increases, which leads to an increase in the fragility of bones and reduce their strength. For this reason, at a more mature age, bone fusion will take more time.
Structure of the bone
Any bone in the human body consists of boneplates, beams and beams. The only difference is how compact these elements are located. On a section of the tubular bone, it can be seen that the bone substance is dense outside, and the inside is more friable. In the spongy substance, the bars are arranged so that they form cells. If the bone elements are densely located to each other in the form of concentric circles, then inside cavities are formed, in which the vessels and nerves are located. The compact substance is localized outside and makes the bone firm, while the spongy substance, due to its structure, reduces the bone mass. The ratio of them can be different and depends on the performed function, shape and location in the body.
Outside, the bones are covered with the periosteum. Exceptions are the surfaces of the joints, which are covered with hyaline cartilage. The pimple is represented by a dense connective tissue, which is fused with the body of the bone. It contains a large number of blood vessels carrying nutrients to the bone, as well as osteoblasts involved in the formation of new bone cells. Therefore, the periosteum promotes the growth of bones in thickness and their fusion in fractures.
Anatomy. Skeleton of lower extremities
Musculoskeletal complex has a very complexstructure. All its features are directly related to the functions performed. The skeleton of the lower limbs of a man consists of two sections interconnected. One of them is fixed and serves as the basis for fixing the bones of the second one. The first is represented by the pelvic girdle and its bones - the skeleton of the lower extremity belt. Its special feature is the fixed location of bones. The second - the bones directly involved in the movement of the body - the skeleton of a free lower limb. For bones in its composition, it is characteristic that the position in different planes can change, and for some, rotation.
The skeleton of the lower limbs of a person is adaptedfor performing the following functions: supporting, motor and spring. Thanks to the well-coordinated work of the joints, ligaments and muscular connections, the movement of the body during walking, running or jumping is amortized. This allows you to reduce the burden on the overlying parts of the body and organs.
The skeleton of the lower extremities located below the pelvic bones is represented by the femur, shank and foot. The shin bones are tibial and fibular.
Bone thigh is the most massive and strongest inthe human body, the upper part is connected to the pelvic bone and forms the hip joint. Bundles of the hip joint are the strongest. Since they are concentrated on the main load to maintain the integrity of the joint.
The lower part of the femur is attached totibia, forming a joint of the knee, which is covered with a patella. The knee joint is capable of flexion, extension and rotation. Its bunches are cross-shaped.
The tibia, connecting with the ram, forms an ankle joint. The foot consists of bones of the tarsus, metatarsus and phalanges of the fingers. It increases the footprint and provides shock absorption to the body.
Muscles that connect the skeleton of the lower limbsof the person are the most massive and strong in the body, due to the fact that they are the greatest burden associated with the retention and movement of the entire human body.
In the junction of the bones of the lower limbslocated thick cartilage pads that provide the body pryamostoyanie and cushioning when jumping and running. They consist of elastic connective tissue that can be compressed under the influence of stress and take their initial state. Any cartilaginous tissue has high recovery speed, i.e. restoration, in case of damage or erasure.
Structure of the foot
The skeleton of the tarsus is represented by 7 bones thatare arranged in two rows between the shin and the plus. The heel bone is slightly located back and performs a supporting function. The metatarsus is represented by 5 tubular bones that are connected to the phalanx of the fingers through the joints. The skeleton of the toes consists of phalanges: the first finger is represented by two phalanges, the rest is three.
The foot is characterized by flexion, extension,lead and turns. Movement of all bones is carried out by the muscles of the lower leg and foot. This determines a large number of options when determining the human body in space.
Stop, constantly in contact with shoes, canto vary. On it appear calluses, corns or outgrowths, which leads to painful sensations. This is due to the fact that the shape and structure of the foot is different for different people. It depends on the proportions of the body, its mass and lifestyle. With improper shoe selection, flat feet can develop - a decrease in the arch of the foot, which also causes certain inconveniences.
Thus, it can be seen that the skeleton of the lowerhuman limb performs a very important function in the body. It determines the posture of the human body when walking, while reducing the load on the overlying organs and systems, thereby prolonging their service life. The musculoskeletal system of man by means of himself unites all organs and systems into a single whole. The structure of the skeleton of the lower limbs of man fully corresponds to the functions performed.