What organs form the musculoskeletal system

In the musculoskeletal system, two parts are distinguished: passive and active. The passive part is a skeleton formed by bones and their joints. The active part is represented by skeletal muscles formed by striated muscle tissue, diaphragm, and walls of internal organs.

Human skeleton

The skeleton has two main functions: mechanical and biological.

Mechanical function includes:

Support function - bones, together with their joints, constitute the support of the body, to which soft tissues and organs are attached;

The function of locomotion (albeit indirectly, since the skeleton serves to attach skeletal muscles);

Spring function - due to articular cartilage and other structures of the skeleton (arch of the foot, bends of the spine), softening shocks and concussions;

Protective function - the formation of bone formations to protect important organs: the brain and spinal cord; heart, lungs. The genitals are located in the pelvic cavity. The bones themselves contain red bone marrow.

Biological function is understood as:

Hematopoietic function - the red bone marrow located in the bones is the source of blood cells;

Storage function - bones serve as a depot for many inorganic compounds: phosphorus, calcium, iron, magnesium and therefore participate in maintaining a constant mineral composition of the internal environment of the body.

The human skeleton is formed by different types of bones. In terms of shape and structure, bones are divided into:

Tubular bones (long and short) are the bones of the skeleton of free limbs.

Spongy bones: long - ribs and sternum; short - vertebrae, wrist bones, tarsus;

Flat bones - bones of the skull roof, scapula, pelvic bone, built of spongy substance surrounded by a plate of compact substance;

Mixed bones - temporal and base of the skull.

The bones of the skeleton can be connected in two ways.

The first way is to connect the bones when there is no gap between them. Such connections are called continuous. Continuous connections can be formed by connective tissue (for example, ligaments between the arches of the vertebrae), cartilaginous tissue (the connection of the ribs with the sternum) and the fusion of bones together (the bones of the skull grow together to form a suture, and the pelvic bones - without forming a suture).

The second method of connection is called an intermittent connection - a gap remains between the bones. These connections are called joints. Depending on the shape of the articular surfaces and the degree of joint mobility (the number of axes along which movement occurs in the joint), the following types of joints are distinguished

Uniaxial Flat Joints between the articular processes of the vertebrae

Cylindrical articulation between the ulna and radius

Blocky interphalangeal joints

Biaxial Saddle Carpal-Carpal joint

Ellipsoid Between the occipital bone and the first cervical vertebra; wrist

Triaxial Ball Shoulder Joint

Walnut hip joint

The connection of bones can be further divided according to the degree of mobility of the joints. So, the joints will refer to movable joints, and the connection by bone fusion - to fixed joints (skull bones, the connection of the pelvic bones with the sacrum).

Connections of bones with the help of cartilaginous and dense connective tissue refer to movable joints (connection of the bodies of the cervical, thoracic, lumbar vertebrae).

The human skeleton consists of the skeleton of the head, or skull, the skeleton of the torso, which is subdivided into the spine and thorax, which consists of ribs and sternum, and the skeleton of the limbs. The limb skeleton is subdivided into free limb skeleton and limb girdle skeleton.

The active part of the musculoskeletal system is represented by muscles. The muscles distinguish between the central part, or the contractile (abdomen), built of striated muscle tissue, and the terminal parts, or irreducible, - tendons formed by dense fibrous connective tissue. With the help of tendons, muscles are attached to the bones of the skeleton, which is why they are called skeletal. The shape of the muscles depends on the location of the muscle fibers relative to the tendon axis.

According to the function performed, respiratory, chewing, and facial muscles are distinguished, and according to the effect on the joints: flexors, extensors, abductors, adductors, rotational, compressors. If two muscles in a joint perform the same action, such muscles are called synergists, if the muscles perform opposite actions, they are called antagonists.

The importance of the musculoskeletal system. The musculoskeletal system includes the skeleton and muscles, united into a single musculoskeletal system. The functional meaning of this system lies in its very name. The skeleton and muscles are the supporting structures of the body, limiting the cavities in which the internal organs are located. With the help of the musculoskeletal system, one of the most important functions of the body is carried out - movement. Movement is the main external manifestation of the body's activity and, at the same time, a necessary factor in its development. conditions of restriction of movements sharply slow down both physical and mental development. It has been shown that if newborn animals are deprived of the possibility of free movement, then already in the first month their weight becomes 3 times less than that of individuals of the same litter. Motor activity, especially hand movements, is one of the necessary conditions for the normal development of the brain, its speech function and thinking. Motor activity also plays an important role in metabolic processes, has a positive effect on the work of all internal organs.
Knowledge of the age characteristics of the organs of movement and the conditions conducive to their normal development is necessary for the development of effective means and methods of physical education, labor training, and organization of the daily routine.
The skeleton is the structural basis of the body. The skeleton forms the structural basis of the body and largely determines its shape and size (Fig. 28).

The skeleton consists of bones, there are more than 200 of them in an adult. The role of bones is not limited to the function of support. The mineral salts that are part of their tissues are one of the most important elements of metabolic processes. The bones also contain one of the main organs of hematopoiesis - the bone marrow.
Each bone is a complex organ made up of bone tissue, periosteum, bone marrow, blood and lymphatic vessels, and nerves.
The bone, with the exception of the connecting surfaces, is covered by the periosteum. It is a thin connective tissue membrane that is rich in nerves and blood vessels that penetrate from it into the bone through special openings. Ligaments and muscles are attached to the periosteum. The inner layer of the periosteum consists of cells that grow and multiply, ensuring the growth of bone in thickness, and in the case of fractures, the formation of callus.
The structure of bones provides their main property - mechanical strength. Bone properties are also provided by their chemical composition. Bones contain 60% minerals, 30% organic, 10% water.
Bone minerals are represented by salts of calcium, phosphorus, magnesium; many trace elements (aluminum, fluorine, manganese, lead, strontium, uranium, cobalt, iron, molybdenum, etc.) have been found. In an adult, about 1200 g of calcium, 530 g of phosphorus, 11 g of magnesium are concentrated in the skeleton; 99% of all calcium in the human body is found in bones. Among organic substances - fibrous protein - collagen, carbohydrates, enzymes. Minerals, especially calcium, make bones hard, organic substances give them elasticity. In children, organic matter predominates in bone tissue; their skeleton is flexible, elastic, and therefore easily deformed, bent under prolonged and heavy load and incorrect body positions. With age, the content of minerals in bones increases, which makes bones less elastic and more fragile.
Organic and mineral substances make the bone strong, firm and elastic and, in combination with the structural features of the bone tissue, the arrangement of its plates oriented in the direction of pressure and tension forces, give the bone properties superior to many building materials and metals. So, bone is 30 times harder than brick and 2.5 times harder than granite. Bone is stronger than oak. It is 9 times more durable than lead and is almost as strong as cast iron.
The human femur in an upright position can withstand the pressure of the load up to 1.5 tons, and the tibia - up to 1.8 tons.
Bone growth and development. Young bones grow in length due to cartilage located between their ends and the body. By the time bone growth ends, cartilage is replaced by bone tissue. During the growth period, the amount of water in the bones of the child decreases, and the amount of minerals increases. At the same time, the content of organic matter decreases.
The development of the skeleton in men ends by the age of 20-24. In this case, the growth of bones in length stops, and their cartilaginous parts are replaced by bone tissue. The development of the skeleton in women ends 2-3 years earlier.
The structure and function of the joints. Distinguish between motionless, inactive and mobile joints of bones, or joints.
The immovable connection of bones occurs by their fusion. At the same time, movements are extremely limited or completely absent. The immobility of the bones of the cerebral skull, for example, is achieved by the fact that the numerous protrusions of one bone enter the corresponding depression of the other. This connection of bones is called a suture.
Small mobility is achieved by elastic cartilage pads between the bones. Such spacers are located between the individual vertebrae. As the muscles contract, these pads contract and the vertebrae move closer together. When walking, running, jumping, cartilage acts as a shock absorber, softening sharp shocks and protecting the body from shock.
Movable joints of bones are more common, they are provided by true joints. The articulating ends of the bones are covered with hyaline cartilage 0.2-0.6 mm thick. This cartilage is elastic, has a smooth, shiny surface, which significantly reduces friction between the bones and thus facilitates their movement. The area of ​​bone articulation is surrounded by an articular capsule (capsule) of very dense connective tissue.

A joint is a movable part of the skeleton, whether it be the junction of the spine or tubular bones .

The main elements of the joint include the articular surfaces of the connecting bones, the articular capsule, the articular cavity and the articular fluid. Each joint of bones at its ends has cartilaginous formations in the form of a smooth shiny growth, this formation is called hyaline cartilage. There is an additional shock absorber in the knee joint - the meniscus, since the knee joints bear the greatest load of all joints. During walking, running, jumping or other manipulations (compression, chewing, etc.), cartilaginous layers and articular fluid, cushioning, dampen the rigidity of the support in the joint. In the spine, this role is played by the intervertebral discs with the nucleus pulposus.

The ends of the bones that form the joint, on the sides and among themselves, are connected by strong ligaments that prevent the bones from separating and shifting to the side. Outside, the joint is closed by a capsule in which there are separate additional chambers called bursae (bags). Some bursae are connected to the joint cavity. In some diseases, more often after an injury, synovial fluid accumulates in the bursa, which sometimes becomes inflamed. This condition is called bursitis. There is a large bursa in the knee joint called a volvulus. It is located in the upper part of the knee joint, above the patella. With inflammation of the knee joint and the formation of a large amount of synovial fluid in its cavity, swelling forms in the upper part of the joint, where the large bursa (volvulus) is located. In this case, they speak of synovitis. Joints, depending on the number of connecting bones, are simple and complex. If the joint has two bones, then the joint is considered simple (small joints of the fingers and toes). When three bones form a joint, the joint is called a compound joint (elbow and knee joints). In addition, the joints vary in shape. They are spherical, block-shaped, saddle-shaped, etc. The shoulder and hip joints are spherical, movements in them can be performed in any direction. An example of a block joint is the knee, elbow, and small joints of the hands and feet. The saddle joint is known as the first metacarpophalangeal joint. These are the joints of the phalanx of the first toe and the metacarpal bone.

> Muscles

Muscles help a person move. Human skeletal musculature has about 600 muscles. Muscles attach to bones in such a way that a person can perform any movement of the head, arm, leg or fingers. Here we do not touch on muscles that are not related to the work of the musculoskeletal system - mimic, chewing, smooth muscle tissue, etc. Each muscle of our body consists of separate bundles - muscle fibers. They give it a striped look. Therefore, all skeletal musculature is called striated.

There is no uniform classification of muscles. Muscles are classified according to the shape and direction of the muscle fibers.

In terms of the shape and direction of muscle fibers, the most common are spindle-shaped muscles characteristic of the limbs, and broad muscles involved in the formation of the walls of the trunk.

Depending on their number, the muscle is called two-, three-, quadriceps.

The main function of the muscles is tension and relaxation, and flexion and extension. In case of inflammation of any of the organs around which there are muscles, they, by straining, perform a protective function, protecting the diseased or damaged organ from further damage. Here's a quick rundown of what you need to know about the most famous human muscles and their functions.

> Function of the musculoskeletal system

Support - fixation of muscles and internal organs;

protective - protection of vital organs (brain and spinal cord, heart, etc.);

motor - providing simple movements, motor actions (posture, locomotion, manipulation) and motor activity;

spring - softening shocks and shaking;

The skeleton performs a supporting, protective function, the function of movement, hematopoiesis and is involved in metabolism, especially mineral (bones are a depot of salts of P, Ca, magnesium, iron, etc.). Muscles, attaching to bones, move them relative to each other during contraction, which provides movement. Muscles perform a supporting function, maintain a certain position of the body.

The protective function of muscles is that they are part of the walls that limit the body cavities and protect the internal organs from mechanical damage.

Spring function. During walking, running, jumping or other manipulations (compression, chewing, etc.), cartilaginous layers and articular fluid, cushioning, dampen the rigidity of the support in the joint. In the spine, this role is played by the intervertebral discs with the nucleus pulposus.