What tissues form the basis of the musculoskeletal system. Musculoskeletal system: structure, functions and diseases

The musculoskeletal system combines bones, bone joints and muscles. The main function of the apparatus is not only support, but also the movement of the body and its parts in space. The musculoskeletal system is divided into passive and active parts. To passive parts include bones and joints of bones . Active part is made up of muscles, which, due to the ability to contract, set the bones of the skeleton in motion. The skeleton is a complex of bones, different in shape and size. In the human skeleton, the bones of the trunk, head, upper and lower extremities are distinguished. The bones have various types of connections between themselves and perform the functions of support, movement, protection, depot of various salts. The skeleton is also called hard, tough skeleton.

Support function of the skeleton lies in the fact that the bones, together with their joints, form the support of the whole body, to which soft tissues and organs are attached. Soft tissues in the form of ligaments, fascia, capsules are called soft skeleton, because they also perform mechanical functions (attach organs to a solid skeleton, form their protection).

Functions supports and movement skeleton are combined with spring the function of articular cartilage and other structures that soften shocks and tremors.

Protective function It is expressed in the formation of bone receptacles for vital organs: the skull protects the brain, the spinal column protects the spinal cord, the chest protects the heart, lungs and large blood vessels. The reproductive organs are located in the pelvic cavity. Inside the bones is the bone marrow, which gives rise to the cells of the blood and the immune system. The functions of support and movement are possible due to the structure of bones in the form of long and short levers, movably connected to each other and set in motion by muscles controlled by the nervous system. In addition, the bones determine the direction of the course of blood vessels, nerves, as well as the shape of the body and its dimensions. Bones are a depot for salts of phosphorus, calcium, iron, magnesium, copper and other compounds, maintain the constancy of the mineral composition of the internal environment of the body. The skeleton consists of 206 bones (85 paired and 36 unpaired). The mass of the skeleton in newborns is about 11% of body weight, in children of different ages - from 9 to 18%. In adults, the ratio of skeletal mass to body mass until the elderly, senile age remains at the level of up to 20%, and then decreases slightly.

The structure of the bones. Each bone as an organ consists of all types of tissues, but the main place is occupied by bone tissue, which is a type of connective tissue.

The chemical composition of bones is complex. Bone is made up of organic and inorganic substances. Inorganic substances make up 65-70% of the dry mass of the bone and are mainly represented by phosphorus and calcium salts. In small amounts, the bone contains more than 30 other various elements. Organic matter makes up 30-35% of dry bone mass. These are bone cells, collagen fibers. Elasticity, elasticity of the bone depends on its organic substances, and hardness - on mineral salts. The combination of inorganic and organic substances in living bone gives it extraordinary strength and elasticity. In terms of hardness and elasticity, bone can be compared with copper, bronze, and cast iron. At a young age, in children, the bones are more elastic, resilient, they contain more organic substances and less inorganic ones. In elderly, old people, inorganic substances predominate in the bones. Bones become more brittle.

Each bone has dense (compact) and spongy substances. The distribution of compact and spongy substances depends on the place in the body and the function of the bones.

compact the substance is found in those bones and in those parts of them that perform the functions of support and movement, for example, inside tubular bones. In places where, with a large volume, it is required to maintain lightness and at the same time strength, a spongy substance is formed, for example, outside the tubular bones.

spongy the substance is also found in short and flat bones. Bone plates form crossbars of unequal thickness in them, intersecting with each other in different directions. The cavities between the crossbars are filled with red bone marrow. In tubular bones, the marrow is located in a canal in the bone called medullary cavity. In an adult, red and yellow bone marrow are distinguished. Red bone marrow fills the spongy substance of flat bones. The yellow bone marrow is located inside the tubular bones.

All bone, with the exception of the articular surfaces, is covered periosteum. The articular surfaces of the bone are covered with articular cartilage.

Classification of bones. There are tubular bones (long and short), spongy, flat, mixed and airy.

tubular bones located in those parts of the skeleton where movements are made on a large scale (for example, near the limbs). In a tubular bone, its elongated part is distinguished - the body of the bone, or diaphysis and thickened ends epiphyses. On the epiphyses are articular surfaces covered with articular cartilage, which serve to connect with adjacent bones. The area of ​​bone located between the diaphysis and the epiphysis is called metaphysis. Among the tubular bones, long tubular bones (humerus, femur, bones of the forearm and lower leg) and short ones (bones of the metacarpus, metatarsus, phalanges of the fingers) are distinguished. The diaphyses are built of compact bone, the epiphyses are made of spongy bone covered with a thin layer of compact bone.

Cancellous (short) bones consist of a spongy substance covered with a thin layer of compact substance. Spongy bones have the shape of an irregular cube or polyhedron. Such bones are located in places where a large load is combined with high mobility. These are the bones of the wrist, tarsus.

flat bones They are built from two plates of compact substance, between which the spongy substance of the bone is located. Such bones are involved in the formation of the walls of cavities, limb belts, perform the function of protection (bones of the skullcap, sternum, ribs).

mixed dice have a complex shape. They consist of several parts having a different structure. For example, vertebrae, bones of the base of the skull.

air bones have a cavity in their body lined with a mucous membrane and filled with air. For example, the frontal, ethmoid, maxillary bones.

Age-related changes in bones. During the individual development of a person after birth, the bones of the skeleton undergo significant age-related changes. So, in a newborn child, bone tissue has not yet replaced cartilaginous bone models in many places. During the first year of a child's life, bones grow slowly; from 1 to 7 years, bone growth accelerates in length due to cartilage and in thickness due to thickening of the compact bone substance due to the bone-forming function of the periosteum. From 8 to 11 years, growth slows down somewhat. After 11 years, the bones of the skeleton begin to grow rapidly again, bone processes are formed, and the bone marrow cavities acquire their final shape.

In the elderly and senile age in the spongy substance, a decrease in the number and thinning of the bone crossbars is observed, the compact substance becomes thinner at the diaphyses of tubular bones.

The growth and development of bones is influenced by social factors, in particular nutrition. Any deficiency of nutrients, salts or metabolic disorders that affect protein synthesis immediately affects bone growth. Thus, the lack of vitamin C affects the synthesis of organic substances of the bone substance. As a result, tubular bones become thin and brittle. Bone growth depends on the normal course of calcification processes, which is associated with the adequacy of the level of calcium and phosphorus in the blood and tissue fluid, with the presence of the amount of vitamin D necessary for the body. Thus, normal bone growth depends on a balanced course of calcification processes and protein synthesis. Usually these two processes proceed in the human body synchronously and harmoniously.

Violation of normal nutrition and metabolism causes changes in the spongy and compact substance of the skeletal system of an adult.

Bone changes occur under the influence of physical activity. With high mechanical loads, the bones, as a rule, acquire greater massiveness, and well-defined thickenings are formed in the places of tendon attachment of muscles - bone protrusions, tubercles, ridges. Static and dynamic loads cause internal restructuring of the compact bone substance, the bones become stronger. Properly dosed physical activity slows down the aging process of bones.

Muscular system.

Skeletal muscles are the active part of the musculoskeletal system; they are built from striated muscle fibers. Muscles are attached to the bones of the skeleton and, with their contraction, set the bone levers in motion. Muscles hold the position of the body and its parts in space, move the bone levers when walking, running and other movements, perform chewing, swallowing and breathing movements, participate in the articulation of speech and facial expressions, and generate heat.

There are about 600 muscles in the human body, most of which are paired. The mass of skeletal muscles in an adult reaches 35-40% of body weight. In newborns and children, muscles account for up to 20-25% of body weight. In the elderly and senile age, the mass of muscle tissue does not exceed 25-30%.

Skeletal muscles have properties such as excitability, conduction and contractility. Muscles are able, under the influence of nerve impulses, to be excited, to come into an active state. In this case, the excitation quickly spreads from the nerve endings to the contractile structures of the muscle fibers. As a result, the muscle contracts, sets the bone levers in motion.

Muscles have a contractile part abdomen, built from striated muscle tissue, and the tendon ends are tendons that are attached to the bones of the skeleton. However, in some muscles, the tendons are woven into the skin (mimic muscles), attached to the eyeball. Tendons are formed from formed dense fibrous connective tissue and are very durable. In the muscles located on the limbs, the tendons are narrow and long.

Muscle shape. The most common muscles are fusiform and ribbon-shaped. Fusiform muscles are located mainly on the limbs, where they act on long bony levers. Ribbon-like muscles have different widths, usually participate in the formation of the walls of the trunk, abdominal, chest cavities. The fusiform muscles can have two bellies separated by an intermediate tendon, two, three, or even four initial parts - the heads of the muscles. There are muscles long and short, straight and oblique, round and square. Muscles can have a pinnate structure, when muscle bundles are attached to the tendon from one, two or more sides. According to the function performed, as well as the effect on the joints, flexor and extensor muscles, adductors and abductors, constrictors and dilators are distinguished.

Muscle fatigue. Fatigue is a temporary decrease in performance, which is restored after rest. Excessive physical activity and the rhythm of work lead to muscle fatigue. At the same time, metabolic products accumulate in the muscle, which inhibit the work of muscle fibers, reduce their energy reserves. After rest, the muscle performance is restored, especially after active rest, i.e. after a change in the nature or type of work.

(musculoskeletal system or musculoskeletal system) - a complex of formations that gives shape and gives support to the human body, provides protection for internal organs and movement of the body in space. The system is formed by the skeleton and .

Skeleton The human body forms the basis of the body, determines its size and shape, and together with the muscles forms cavities in which the internal organs are located. The skeleton consists of 200 bones. Bones act as levers driven by muscles and protect organs from injury. Bones are involved in the exchange of phosphorus and calcium.

The human skeleton includes six departments:

1. spine (axial skeleton),
2. upper limb belt
3. lower limb belt,
4. upper limbs,
5. lower limbs.

Composition and structure of bones.

Bone tissue contains inorganic and organic substances. Living human bones contain 22% water, 5% protein, 21.8% inorganic matter, and 15.7% fat. Organic substances that make up bones (mainly ossein and osseomucoid) provide bones flexibility and resilience , and minerals (mainly calcium carbonate and phosphate) - hardness and strength . With age, the ratio of organic and mineral substances in the bone changes. So, in children, there are more organic substances in the bones, so their skeleton is elastic; the bones of older people, containing more minerals, are harder but brittle, which increases the likelihood of fractures at this age.

Externally, the bone is fused with periosteum(ensures bone growth in thickness), consisting of dense connective tissue and penetrated by a large number of blood, lymphatic vessels and nerves. It provides nutrition to the bone, as well as the growth of the bone in thickness. Bone contains two types of bone : outside - dense compact, and inside - spongy. The structural unit of compact bone tissue is osteon. Each osteon consists of 5-20 cylindrical bone plates inserted one into the other. In the center of the osteon passes central (Haversian) channel containing blood, lymphatic vessels and nerves. Spongy Substances o bone consists of a network of thin mutually intersecting bone crossbars, between which there are small cavities filled with red bone marrow. The location of the crossbars reflects the direction of the greatest stretching and compression of the bone. The distribution of compact and spongy substances in different bones depends on the function that these bones perform in the body.

There are tubular, spongy, flat and mixed bones. tubular bones(brachial, femoral) have the appearance of a tube with a cavity filled with yellow bone marrow. The ends of these bones are thickened and filled with spongy tissue containing red bone marrow. Tubular bones are able to withstand heavy loads. flat bones (shoulder blades, ribs, pelvic, cranial) consist of two plates of dense substance and a thin layer of spongy substance between them.

Types of bone connection

Movable the connection of the bones is provided by the joints, which are formed by a cavity at the end of one of the articulating bones and a head at the end of the other. The joints are reinforced with intra-articular ligaments, and the articular surfaces are covered with cartilage and enclosed in the articular bag. The synovial fluid inside the joint acts as a lubricant that reduces friction.

Semi-movable connection provided by cartilaginous layers between the bones. For example, there are cartilage discs between the vertebrae. The ribs are also connected to the sternum through cartilage. These connections provide relative mobility.

Fixed connections are formed due to the fusion of bones and the formation of bone sutures ( skull bones).

Human skeleton

The following sections are distinguished in the human skeleton: axial skeleton and limb skeleton(upper and lower). The axial skeleton, in turn, is divided into (spine and chest).

Scull consists of brain and facial sections. The bones of the skull (with the exception of the lower jaw) are rigidly articulated with each other. In newborn children, the space between the bones is filled with connective tissue (fontanelles), which makes the skull very elastic. The formation of sutures between the bones is completed by 3-5 years.

Spine(vertebral column) - the support of the body, it consists of 33-34 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused into a single sacrum) and 4-5 coccygeal. The vertebra consists of a body, an arc that closes the vertebral foramen, and seven processes: the spinous, two transverse, two upper articular and two lower articular.

Skeleton chest formed by the sternum, 12 pairs of ribs and thoracic vertebrae. Ribs are flat, arcuately curved bones, passing into cartilage in front. Behind they are articulated with the thoracic vertebrae. In front, 7 pairs of upper ribs (true ribs) are directly connected by the sternum, a flat bone that lies along the midline of the chest. The next three pairs (false ribs) with their cartilages join the cartilages of the superior ribs. The last two pairs (oscillating ribs) do not have cartilage and are freely located in the muscular wall of the body. Rising and falling, the ribs provide changes in the volume of the chest during breathing.

Skeleton upper limbs consists of the shoulder girdle and the skeleton of the free upper limbs (arms). The shoulder girdle consists of two paired bones - the scapula and the clavicle. The shoulder blade is a flat triangular bone adjacent to the back of the chest and articulates with the humerus and clavicle. The clavicle (a thin curved bone) is connected to the sternum at one end, and to the scapula at the other. The skeleton of the free upper limb consists of the shoulder, forearm and hand. The humerus, which forms the shoulder, is connected to the scapula (shoulder joint) and the bones of the forearm (elbow joint). The forearm consists of two bones - the ulna and the radius. The hand consists of 8 short bones of the wrist, 5 long bones of the metacarpus and phalanges of the fingers (the thumb has two phalanges, all the rest have three). The lower end of the radius with the three upper bones of the wrist form the wrist joint.

Skeleton lower extremities consists of the pelvic girdle and the skeleton of the free lower extremities (legs). The pelvic girdle is formed by a pair of massive pelvic bones, which are motionlessly articulated with the sacrum at the back, and in front are connected to each other with the help of a semi-joint (pubic symphysis). Each pelvic bone is formed by three fused bones (ilium, ischium, and pubis). On the sides of the pelvic bones are round depressions for articulation with the heads of the femurs. The skeleton of the free lower limb consists of the thigh, lower leg and foot. The thigh is formed by a large massive femur, the head of which forms the hip joint with the pelvic bone. The lower leg consists of the tibia and fibula. The tibia articulates with the femur to form the knee joint. In front of the knee joint, in the thickness of the tendons, there is a small triangular patella (patella). The bones of the lower leg form the ankle joint with the talus of the tarsus. The foot consists of 7 short bones of the tarsus, 5 long bones of the metatarsus and phalanges of five fingers (the first finger has two phalanges, the rest have three). The foot has the appearance of an arch.

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The whole set of bones and their connections (joints, ligaments, muscles), coordinated by interconnected nervous structures - this is how the musculoskeletal system (musculoskeletal system, locomotor system) is characterized in anatomy. Acting as a protector of the internal organs, this apparatus undergoes heavy loads and is subject to age-related changes to a greater extent than other body systems. Violations of the functional ability of the musculoskeletal system lead to a deterioration in mobility, so it is important to prevent them at the very beginning.

What is the musculoskeletal system

The muscular frame, connected in a certain way with the bone skeleton through joints and tendons, is a musculoskeletal system. Thanks to the coordinated work of the central nervous system and the endings of the bone levers, the conscious mobility of all parts of the body is carried out. At the macroscopic level, the structure of bones can be represented as follows:

• periosteum - a dense tissue covering the tubular bones, the nerve endings coming from it penetrate inside through micro-holes;
• compact tissue - the substance of the cortical layer of the bone, provides storage of chemical elements;
• trabecular substance - a spongy tissue consisting of bony septa arranged in space in a certain way to ensure the safety of arterial channels and bone marrow.

Structure

Bones, in their totality, the skeleton, muscles and connective structures - this is what is part of the musculoskeletal system. The musculoskeletal system owes its name to the fundamental elements, which, in addition to the main components, include the following compounds:

• synarthrosis;
• joints;
• tendons;
• ligaments.

Active part of the musculoskeletal system

Muscles, diaphragm, and organ walls make up the active part of the locomotor system. Muscle fiber, consisting of contractile filaments, provides the function of movement of all parts of the musculoskeletal system, including facial expressions. Chemical energy under the influence of impulses of the brain and spinal cord is converted into mechanical energy, which ensures the mobility of the system.

Passive part

The skeleton, formed by bones of various types, is the passive part of the musculoskeletal system. The structural elements of this area are:

• scull;
• spine;
• chest (ribs and sternum);
• limbs (the upper ones consist of the bones of the forearm, shoulder, hand, the lower ones - of the bones of the femur, lower leg, foot).

Functions

You can understand what functions the system of organs of movement performs based on its name, but providing the ability to perform motor actions is far from an exhaustive list of all the functionality of the musculoskeletal system, which is described in the table:

Conditions for the correct formation of the musculoskeletal system

Despite the fact that the bones seem to be a permanent substance, they are renewed and changed throughout life. Every 10 years there is a complete replacement of the structural skeletal system, and certain conditions are necessary for the correct formation of its chemical composition. By adhering to the rules below, you can prolong the health of the musculoskeletal system and prevent the development of violations of the functionality of its departments:

• eating food containing sufficient amounts of calcium and phosphorus;
• ensuring the intake of vital vitamins in the body;
• maintaining muscle activity;
• stress level control;
• compliance with the rest regime;
• rejection of bad habits.

Musculoskeletal disorders

The causes that provoke the occurrence of disorders of the musculoskeletal system are divided into internal and external. Internal include those that affect the internal organs and systems, contributing to damage to bone tissue. This may be a lack of essential vitamins and minerals in the body (for example, rickets is a form of vitamin deficiency in which bone strength is lost, the cause is a lack of vitamin D). External causes are events uncontrolled by a person that affect the integrity of the bones of the musculoskeletal system, i.e. injury.

Incorrect body position during movement or at rest (posture) and flattening of the sole (flat feet) have a gradual but constant deforming effect on the locomotor system. All injuries that lead to disorders of the musculoskeletal system can lead to the development of serious diseases if they are not eliminated in the early stages.

Diseases

Partial or complete restriction of one of the functions of the musculoskeletal system is a symptom of the disease. The reason for its appearance divides diseases into primary and secondary. If this pathology occurs due to violations of the locomotor system, then it is considered primary. Secondary are those diseases of the musculoskeletal system that are caused by concomitant factors. Symptoms, probable causes and suggested treatments are listed in the table:

Comprehensive approach to treatment

The appearance of the first pain sensations, feelings of discomfort during movements, should serve as a reason for contacting a doctor. Most diseases of all departments of the musculoskeletal system can be easily cured at the initial stage of the pathological process. Medicine offers a number of preventive and therapeutic measures aimed at improving the spine, among which the following are effective:

• acupuncture;
• manual massages;
• the impact of natural and artificially created factors (magnetotherapy, ultrasound, current, laser);
• physiotherapy;
• prosthetics and other types of surgical intervention;
• medications.

Video

In the process of evolution, animals mastered more and more new territories, types of food, adapted to the changed living conditions. Evolution gradually changed the appearance of animals. In order to survive, it was necessary to actively search for food, better hide or defend against enemies, and move faster. Changing along with the body, the musculoskeletal system had to provide all these evolutionary changes. The most primitive protozoa do not have supporting structures, move slowly, flowing with the help of pseudopods and constantly changing shape.

The first support structure that appeared - cell membrane. It not only delimited the organism from the external environment, but also made it possible to increase the speed of movement due to flagella and cilia. Multicellular animals have a wide variety of supporting structures and adaptations for movement. Appearance external skeleton increased the speed of movement due to the development of specialized muscle groups. Internal skeleton grows with the animal and allows you to reach record speeds. All chordates have an internal skeleton. Despite significant differences in the structure of the musculoskeletal structures in different animals, their skeletons perform similar functions: support, protection of internal organs, and movement of the body in space. The movements of vertebrates are carried out by the muscles of the limbs, which carry out such types of movement as running, jumping, swimming, flying, climbing, etc.

Skeleton and muscles

The musculoskeletal system is represented by bones, muscles, tendons, ligaments and other connective tissue elements. The skeleton determines the shape of the body and, together with the muscles, protects the internal organs from all kinds of damage. Thanks to the connections, the bones can move relative to each other. The movement of bones occurs as a result of the contraction of the muscles that attach to them. In this case, the skeleton is a passive part of the motor apparatus that performs a mechanical function. The skeleton consists of dense tissues and protects the internal organs and the brain, forming natural bone containers for them.

In addition to mechanical functions, the skeletal system performs a number of biological functions. The bones contain the main supply of minerals that are used by the body as needed. The bones contain red bone marrow, which produces blood cells.

The human skeleton consists of a total of 206 bones - 85 paired and 36 unpaired.

The structure of the bones

The chemical composition of bones

All bones are composed of organic and inorganic (mineral) substances and water, the mass of which reaches 20% of the bone mass. Organic matter of bones ossein- has elastic properties and gives the bones elasticity. Minerals - salts of carbonate, calcium phosphate - give the bones hardness. The high strength of bones is provided by a combination of the elasticity of ossein and the hardness of the mineral substance of the bone tissue.

Macroscopic structure of the bone

Outside, all bones are covered with a thin and dense film of connective tissue - periosteum. Only the heads of the long bones do not have a periosteum, but are covered with cartilage. The periosteum contains many blood vessels and nerves. It provides nutrition to the bone tissue and takes part in the growth of the bone in thickness. Thanks to the periosteum, broken bones grow together.

Different bones have a different structure. A long bone has the appearance of a tube, the walls of which consist of a dense substance. Such tubular structure long bones gives them strength and lightness. In the cavities of tubular bones is yellow bone marrow- Loose connective tissue rich in fat.

The ends of long bones contain cancellous bone. It also consists of bony plates that form many crossed partitions. In places where the bone is subjected to the greatest mechanical load, the number of these partitions is the highest. In the spongy substance is red marrow whose cells give rise to blood cells. Short and flat bones also have a spongy structure, only from the outside they are covered with a layer of dam substance. The spongy structure gives the bones strength and lightness.

Microscopic structure of the bone

Bone tissue refers to the connective tissue and has a lot of intercellular substance, consisting of ossein and mineral salts.

This substance forms bony plates arranged concentrically around microscopic tubules that run along the bone and contain blood vessels and nerves. Bone cells, and therefore bone, are living tissue; it receives nutrients from the blood, metabolism takes place in it and structural changes can occur.

Bone types

The structure of bones is determined by the process of long historical development, during which the body of our ancestors changed under the influence of the environment and adapted by natural selection to the conditions of existence.

Depending on the shape, there are tubular, spongy, flat and mixed bones.

tubular bones are found in organs that make rapid and extensive movements. Among the tubular bones there are long bones (humerus, femur) and short ones (phalanxes of fingers).

In tubular bones, a middle part is distinguished - the body and two ends - the heads. Inside the long tubular bones there is a cavity filled with yellow bone marrow. The tubular structure determines the strength of the bones necessary for the body while consuming the least amount of material for them. During the period of bone growth, cartilage is located between the body and the head of the tubular bones, due to which the bone grows in length.

flat bones limit cavities inside which organs are placed (cranial bones), or serve as surfaces for attachment of muscles (scapula). Flat bones, like short tubular bones, are predominantly spongy. The ends of long tubular bones, as well as short tubular and flat bones, do not have cavities.

spongy bones built mainly of spongy substance, covered with a thin layer of compact. Among them, long spongy bones (sternum, ribs) and short ones (vertebrae, wrist, tarsus) are distinguished.

To mixed bones include bones that are composed of several parts that have a different structure and function (temporal bone).

Protrusions, ridges, roughness on the bone - these are the places of attachment to the bones of the muscle. The better they are expressed, the stronger the muscles attached to the bones are developed.

Human skeleton.

The skeleton of man and most mammals has the same type of structure, consists of the same sections and bones. But man differs from all animals in his ability to work and intellect. This left a significant imprint on the structure of the skeleton. In particular, the volume of the human cranial cavity is much larger than that of any animal that has a body of the same size. The size of the facial part of the human skull is smaller than that of the brain, while in animals, on the contrary, it is much larger. This is due to the fact that in animals the jaws are an organ of protection and obtaining food and therefore are well developed, and the volume of the brain is smaller than in humans.

The bends of the spine associated with the shift of the center of gravity due to the vertical position of the body contribute to maintaining a person's balance and soften shocks. Animals do not have such curves.

The human chest is compressed from front to back and close to the spine. In animals, it is compressed from the sides and extended to the bottom.

The wide and massive human pelvic girdle looks like a bowl, supports the abdominal organs and transfers body weight to the lower limbs. In animals, body weight is evenly distributed between the four limbs and the pelvic girdle is long and narrow.

The bones of the lower extremities of a person are noticeably thicker than the upper ones. Animals do not have a significant difference in the structure of the bones of the fore and hind limbs. The great mobility of the forelimbs, especially the fingers, makes it possible for a person to perform various movements and types of work with his hands.

Torso skeleton axial skeleton

Torso skeleton includes the spine, consisting of five sections, and the thoracic vertebrae, ribs and sternum form chest(see table).

Scull

In the skull, brain and facial sections are distinguished. AT cerebral part of the skull - the cranium - is the brain, it protects the brain from shock, etc. The cranium consists of fixedly connected flat bones: the frontal, two parietal, two temporal, occipital and main. The occipital bone connects to the first vertebrae of the spine with the help of an elliptical joint, which ensures that the head tilts forward and to the side. The head rotates along with the first cervical vertebra due to the connection between the first and second cervical vertebrae. There is a hole in the occipital bone through which the brain connects to the spinal cord. The bottom of the cranium is formed by the main bone with numerous openings for nerves and blood vessels.

Facial the skull section forms six paired bones - the upper jaw, zygomatic, nasal, palatine, lower nasal concha, as well as three unpaired bones - the lower jaw, vomer and hyoid bone. The mandibular bone is the only bone of the skull that is movably connected to the temporal bones. All bones of the skull (with the exception of the lower jaw) are fixedly connected, which is due to the protective function.

The structure of the facial skull in humans is determined by the process of "humanization" of the monkey, i.e. the leading role of labor, the partial transfer of the grasping function from the jaws to the hands, which have become organs of labor, the development of articulate speech, the use of artificially prepared food, which facilitates the work of the chewing apparatus. The brain skull develops in parallel with the development of the brain and sensory organs. In connection with the increase in the volume of the brain, the volume of the cranium has increased: in humans, it is about 1500 cm 2.

Torso skeleton

The skeleton of the body consists of the spine and chest. Spine- the basis of the skeleton. It consists of 33-34 vertebrae, between which there are cartilaginous pads - disks, which gives the spine flexibility.

The human spinal column forms four bends. In the cervical and lumbar spine, they bulge forward, in the thoracic and sacral - back. In the individual development of a person, bends appear gradually, in a newborn the spine is almost straight. First, a cervical bend is formed (when the child begins to hold his head straight), then the chest (when the child begins to sit). The appearance of the lumbar and sacral curves is associated with maintaining balance in the vertical position of the body (when the child begins to stand and walk). These bends are of great physiological importance - they increase the size of the chest and pelvic cavities; make it easier for the body to maintain balance; soften shocks when walking, jumping, running.

With the help of intervertebral cartilage and ligaments, the spine forms a flexible and elastic column with mobility. It is not the same in different parts of the spine. The cervical and lumbar sections of the spine have greater mobility, the thoracic section is less mobile, as it is connected to the ribs. The sacrum is completely immobile.

Five sections are distinguished in the spine (see the diagram "Departments of the spine"). The size of the vertebral bodies increases from the cervical to the lumbar due to the greater load on the underlying vertebrae. Each of the vertebrae consists of a body, a bony arch, and several processes to which muscles are attached. There is a hole between the vertebral body and the arch. The openings of all vertebrae form spinal canal in which the spinal cord is located.

Rib cage formed by the sternum, twelve pairs of ribs and thoracic vertebrae. It serves as a container for important internal organs: the heart, lungs, trachea, esophagus, large vessels and nerves. Takes part in respiratory movements due to the rhythmic raising and lowering of the ribs.

In humans, in connection with the transition to upright posture, the hand is also freed from the function of movement and becomes an organ of labor, as a result of which the chest experiences traction from the attached muscles of the upper limbs; the insides do not press on the front wall, but on the lower one, formed by the diaphragm. This causes the chest to become flat and wide.

Skeleton of the upper limb

Upper limb skeleton consists of a shoulder girdle (scapula and collarbone) and a free upper limb. The shoulder blade is a flat triangular bone adjacent to the back of the chest. The clavicle has a curved shape, resembling the Latin letter S. Its significance in the human body lies in the fact that it puts the shoulder joint at some distance from the chest, providing greater freedom of movement of the limb.

The bones of the free upper limb include the humerus, the bones of the forearm (radius and ulna) and the bones of the hand (the bones of the wrist, the bones of the metacarpus and the phalanges of the fingers).

The forearm is represented by two bones - the ulna and the radius. Due to this, it is capable of not only flexion and extension, but also pronation - turning in and out. The ulna in the upper part of the forearm has a notch that connects to the block of the humerus. The radius connects to the head of the humerus. In the lower part, the radius has the most massive end. It is she who, with the help of the articular surface, together with the bones of the wrist, takes part in the formation of the wrist joint. On the contrary, the end of the ulna here is thin, it has a lateral articular surface, with the help of which it connects to the radius and can rotate around it.

The hand is the distal part of the upper limb, the skeleton of which is the bones of the wrist, metacarpus and phalanx. The wrist consists of eight short spongy bones arranged in two rows, four in each row.

skeleton hand

Hand- the upper or forelimb of man and monkeys, for which the ability to oppose the thumb to everyone else was previously considered a characteristic feature.

The anatomical structure of the hand is quite simple. The arm is attached to the body through the bones of the shoulder girdle, joints and muscles. Consists of 3 parts: shoulder, forearm and hand. The shoulder girdle is the most powerful. Bending the arms at the elbow gives the arms greater mobility, increasing their amplitude and functionality. The hand consists of many movable joints, it is thanks to them that a person can click on the keyboard of a computer or mobile phone, point a finger in the right direction, carry a bag, draw, etc.

The shoulders and hands are connected by means of the humerus, ulna and radius bones. All three bones are connected to each other with the help of joints. At the elbow joint, the arm can be bent and extended. Both bones of the forearm are connected movably, therefore, during movement in the joints, the radius rotates around the ulna. The brush can be rotated 180 degrees.

Skeleton of the lower extremities

Skeleton of the lower limb consists of a pelvic girdle and a free lower limb. The pelvic girdle consists of two pelvic bones articulated behind the sacrum. The pelvic bone is formed by the fusion of three bones: the ilium, ischium, and pubis. The complex structure of this bone is due to a number of functions it performs. Connecting with the hip and sacrum, transferring the weight of the body to the lower limbs, it performs the function of movement and support, as well as a protective function. In connection with the vertical position of the human body, the pelvic skeleton is relatively wider and more massive than in animals, since it supports the organs lying above it.

The bones of the free lower limb include the femur, lower leg (tibia and fibula), and foot.

The skeleton of the foot is formed by the bones of the tarsus, metatarsus and phalanges of the fingers. The human foot differs from the animal foot in its vaulted shape. The vault softens the shocks received by the body when walking. The toes are poorly developed in the foot, with the exception of the big one, since it has lost its grasping function. The tarsus, on the contrary, is strongly developed, the calcaneus is especially large in it. All these features of the foot are closely related to the vertical position of the human body.

The upright posture of a person has led to the fact that the difference in the structure of the upper and lower extremities has become much greater. Human legs are much longer than arms, and their bones are more massive.

Bone joints

In the human skeleton, there are three types of bone connections: fixed, semi-movable and movable. Fixed the type of connection is the connection due to the fusion of bones (pelvic bones) or the formation of sutures (skull bones). This fusion is an adaptation to bear the heavy load experienced by the human sacrum due to the vertical position of the torso.

semi-movable connection is made with cartilage. The bodies of the vertebrae are interconnected in this way, which contributes to the inclination of the spine in different directions; ribs with a sternum, which ensures the movement of the chest during breathing.

Movable connection, or joint, is the most common and at the same time complex form of bone connection. The end of one of the bones that form the joint is convex (the head of the joint), and the end of the other is concave (the articular cavity). The shape of the head and cavity correspond to each other and the movements carried out in the joint.

articular surface articulating bones are covered with white shiny articular cartilage. The smooth surface of the articular cartilage facilitates movement, and its elasticity softens the jolts and jolts experienced by the joint. Usually, the articular surface of one bone that forms the joint is convex and is called the head, while the other is concave and is called the cavity. Due to this, the connecting bones fit tightly to each other.

Articular bag stretched between the articulating bones, forming a hermetically closed joint cavity. The articular bag consists of two layers. The outer layer passes into the periosteum, the inner one secretes a fluid into the joint cavity, which plays the role of a lubricant, ensuring the free sliding of the articular surfaces.

Features of the human skeleton associated with labor activity and upright posture

Labor activity

The body of a modern person is well adapted to labor activity and upright posture. Bipedal locomotion is an adaptation to the most important feature of human life - work. It is he who draws a sharp line between man and higher animals. Labor had a direct impact on the structure and function of the hand, which began to influence the rest of the body. The initial development of upright walking and the emergence of labor activity led to a further change in the entire human body. The leading role of labor contributed to the partial transfer of the grasping function from the jaws to the hands (which later became labor organs), the development of human speech, the use of artificially prepared food (facilitates the work of the chewing apparatus). The brain part of the skull develops in parallel with the development of the brain and sensory organs. In this regard, the volume of the cranium increases (in humans - 1,500 cm 3, in great apes - 400–500 cm 3).

bipedalism

A significant part of the signs inherent in the human skeleton is associated with the development of a bipedal gait:

• supporting foot with a strongly developed, powerful thumb;
• brush with a very developed thumb;
• the shape of the spine with its four curves.

The shape of the spine has developed due to a springy adaptation to walking on two legs, which ensures smooth movements of the body, protects it from damage during sudden movements and jumps. The trunk is flattened in the thoracic region, which leads to compression of the chest from front to back. The lower limbs have also undergone changes due to upright posture - widely spaced hip joints give stability to the body. In the course of evolution, the gravity of the body was redistributed: the center of gravity moved down and took a position at the level of 2–3 sacral vertebrae. A person has a very wide pelvis, and his legs are widely spaced, this makes it possible for the body to be stable when moving and standing.

In addition to the spine with a curved shape, five vertebrae in the sacrum, compressed chest, one can note the elongation of the scapula and the expanded pelvis. All this resulted in:

• strong development of the pelvis in width;
• fastening of the pelvis with the sacrum;
• powerful development and a special way to strengthen the muscles and ligaments in the hip area.

The transition of human ancestors to upright walking led to the development of the proportions of the human body, which distinguish it from monkeys. So for a person shorter upper limbs are characteristic.

Walking and labor led to the formation of asymmetry of the human body. The right and left halves of the human body are not symmetrical in shape and structure. A prime example of this is the human hand. Most people are right-handed, with about 2-5% left-handers.

The development of upright walking, accompanying the transition of our ancestors to living in open areas, led to significant changes in the skeleton and the whole organism.

Musculoskeletal system

The apparatus is a functional combination of heterogeneous systems and their constituent organs. The term apparatus is also used to designate small structures that have a definite and important functional significance, for example, the perceiving apparatus of a nerve cell (receptor). The apparatus is understood as a set of individual organs and systems that differ in structure, topography and development, but are united by a common function.

An organ is understood as a set of evolutionarily formed various tissues, among which one or more prevail, determining its specific form, internal structure, topography, development and function. Organs are made up of tissues that have cells and intercellular substance. The system includes organs that are homogeneous in development, structure and function.

Structural and functional units of organs represent a set of main and auxiliary cells, together with the vessels and nerves that provide them. As a result, the scheme of building an organism looks like a hierarchical, integral and subordinate structure: organism - apparatuses and systems of organs - organs - structural and functional units - tissues - cells - cellular elements and intercellular substance - biochemical compounds - molecules and atoms .

The human musculoskeletal system includes three systems - bone, articular and muscle. They have a common origin from the mesoderm, but a different structure and topography, although they are united by a single function of supporting the body and its movement, which is associated with overcoming the earth's gravity (anti-gravity apparatus). The passive part in it is made up of bones and their compounds related to the solid skeleton, the active part is muscles. The apparatus also has a soft skeleton, represented by fascia, ligaments, membranes, and fiber.

All bone connections are divided into continuous, intermittent (synovial or joints) and semi-discontinuous.

Skeletal, striated muscles, using bones and joints as a system of movable levers, provide movement in space. Under conditions of reduced or absent gravity during space flights, atrophic changes occur in the musculoskeletal system, which requires the creation of artificial devices for constant impact on its organs (Chibis-type astronaut suits are also used in medicine in the treatment of children with cerebral palsy).

The origin and development of the musculoskeletal system is associated with the mesoderm, which appears in the third week of the embryonic period. At the beginning, the dorsal string (the rudiment of the spinal column) is formed, a segmented mesoderm of the body of the embryo is formed around it. Subsequently, somites arise from the segmented mesoderm and chord, which include three components: sclerotome, myotome, and dermatome. Bones and joints develop from the sclerotome, skeletal muscles develop from the myotome, and skin develops from the dermatome.

The musculoskeletal system includes muscles and bones.

The passive part of the human musculoskeletal system is a complex of bones and their joints - the skeleton. The skeleton consists of the bones of the skull, spine and chest (the so-called axial skeleton), as well as the bones of the upper and lower extremities (additional skeleton). The skeleton is characterized by high strength and flexibility, which is provided by the way the bones are connected to each other.

The movable connection of most bones gives the skeleton the necessary flexibility and provides freedom of movement. In addition to fibrous and cartilaginous continuous joints (they mainly connect the bones of the skull), there are several types of less rigid bone joints in the skeleton. Each type of connection depends on the required degree of mobility and the type of load on a given part of the skeleton. Joints with limited mobility are called semi-joints or symphyses, and discontinuous (synovial) joints are called joints. The complex geometry of the articular surfaces exactly corresponds to the degree of freedom of this connection.

The human skeleton continues its formation throughout life: the bones are constantly renewed and grow, responding to the growth of the whole organism; separate bones (for example, coccygeal or sacral), which exist separately in children, fuse into a single bone as they grow older. By the time of birth, the bones of the skeleton have not yet been completely formed and many of them consist of cartilaginous tissue.

The internal structure of each of the bones of the skeleton is optimally adapted so that the bone can successfully perform all the numerous functions that nature has assigned to it. The participation of the bones that make up the skeleton in the metabolism is provided by blood vessels penetrating each bone. Nerve endings penetrating the bone allow it, as well as the entire skeleton as a whole, to grow and change, adequately responding to changes in the living environment and external conditions of the organism's existence.

The structural unit of the supporting apparatus, which forms the bones of the skeleton, as well as cartilage, ligaments, fascia and tendons, is connective tissue. A common characteristic of connective tissues of various structures is that they all consist of cells and an intercellular substance, which includes fibrous structures and an amorphous substance. Connective tissue performs various functions: as part of trophic organs - the formation of the stroma of organs, nutrition of cells and tissues, transport of oxygen, carbon dioxide, as well as mechanical, protective, that is, it combines various types of tissues and protects organs from damage, viruses and microorganisms.

Connective tissue is subdivided into connective tissue proper and specifically connective tissue with supporting (bone and cartilage tissues) and hematopoietic (lymphatic and myeloid tissues) properties.

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 P, Ca, magnesium, iron, etc.). Muscles, attached to the 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 the muscles is that they are part of the walls that limit the cavities of the body and protect the internal organs from mechanical damage.

During ontogenesis, muscles stimulate the maturation of the CNS.

During the period of embryogenesis, the developing organism receives a limited amount of irritations.

When the fetus moves, muscle receptors are irritated and impulses from them go to the central nervous system, and this allows nerve cells to develop. That is, the CNS directs and stimulates the growth and development of muscles, and the muscles influence the formation of the structure and function of the CNS.

Chemical composition, development, structure and connection of bones

A bone is an organ, since it has all the characteristics characteristic of it: it has a certain shape, structure, function, development, position in the body and is built from several tissues, mainly bone. The chemical composition of the bone of an adult: water - 50%, inorganic substances - 22%, organic substances, which are collectively called ossein - 28% (including fat, collagen, carbohydrates, nucleic acids).

Bone tissue forms the bone skeleton of the head and limbs, the axial skeleton of the body, protects the organs located in the skull, chest and pelvic cavities, participates in mineral metabolism. In addition, bone tissue determines the shape of the body.

Bone tissue is subdivided into coarse fibrous tissue, characteristic of embryos and young organisms, and lamellar tissue, which makes up the bones of the skeleton, which, in turn, is divided into spongy, contained in the epiphyses of bones, and compact, located in the diaphysis of tubular bones.

Cartilaginous tissue is formed by chondrocyte cells and an increased density of intercellular substance. Cartilages perform a supporting function and are part of various parts of the skeleton.

The bone of a newborn is characterized by a large amount of water, in addition, the bones of children have more ossein, which gives the bones elasticity and elasticity. The bones of older people have a greater amount of inorganic substances, which makes the bones brittle and brittle.

The bone skeleton of an adult has 203-206 bones, and a child - 356.

The bone in its development goes through three stages:

• 1) connective tissue, or membranous (3-4 weeks of intrauterine development);
• 2) cartilaginous (5-7 weeks of intrauterine development);
• 3) bone (ossification points appear from the 8th week of intrauterine development).

Almost all bones go through these 3 stages and then they are called secondary bones. But there are bones that go through only stages 1 and 3, then they are called primary bones. These include: the bones of the cranial vault, most of the bones of the facial skull, the middle part of the clavicle.

The structural unit of bone is called the osteon or Haversian system. Osteon is a system of bony, concentrically arranged plates around a canal in which vessels and nerves pass (Haversian canal). Osteons in their totality form a compact bone substance located under the periosteum, a thin plate that covers the bone from above. Under the compact substance is the spongy substance of the bone. It has crossbars that form a single beam system that ensures uniform distribution of load forces on the entire bone.

Bone tissue, like any other connective tissue, consists of cells (there are three types: osteocytes, osteoblasts and osteoclasts) and intercellular substance (it includes collagen fibers and inorganic salts).

The periosteum is a connective tissue plate, which consists of two layers: fibrous (outer) and cambial (inner). The cambial layer is represented by osteoblasts that form the bone during the growth of the organism, that is, they carry out the growth of the bone in thickness. Through the periosteum, nutrition and innervation of the bone is carried out. The periosteum covers almost all bones except the flat bones of the skull.

The shape distinguishes between long, short, flat and mixed bones. Long and short bones, depending on the internal structure, as well as on the developmental features, can be divided into tubular and spongy.

Bone growth in length is carried out by replacing cartilage with bone.

This process is called the ossification process. It can go in two ways: enchondral - ossification points appear inside the cartilage, and perichondral - ossification points appear on the surface of the cartilage.

In the epiphyses, short bones, in the processes of bones, ossification is carried out according to the endochondral type, and in the diaphysis, along the perichondral type. The growth of long bones begins with the appearance of foci of ossification (bone cuff) in the middle part of the diaphysis, which are formed due to the division of osteoblasts. The bone cuff grows towards the epiphyses. At the same time, osteoclasts create a bone cavity inside the bone by lysis of the cartilaginous middle.

For the normal growth of bones and their formation, proper nutrition is necessary: ​​the child’s food should contain a sufficient amount of salt P and Ca, vitamin A (lack of it narrows the vessels of the periosteum), C (with its deficiency, bone plates are not formed), D (with a deficiency, the exchange of P and Sa).

Bone joints are divided into two main groups: continuous joints - synarthroses and discontinuous connections - dirthroses.

Synarthrosis is the connection of bones with the help of connective tissue (cartilaginous or bone).

These connections are sedentary or immobile. They occur where the angle of displacement of one bone relative to another is small.

Depending on the tissue connecting the bones, all synarthroses are divided into: syndesmoses - bones are connected using fibrous connective tissue (fibrous); synchondrosis - bones are connected with the help of cartilage; synostoses - fixed connections with the help of bone tissue.

Diarthroses are discontinuous mobile joints, which are characterized by the presence of four main elements: the articular capsule, articular cavity, synovial fluid, articular surfaces.