Muscles play a key role in the implementation of movement as a fundamental property of a living organism. In humans, muscles make up from 40% to 50% of body weight (Odnoralov N.I., 1965; Begun P.I., Shukeylo Yu.A., 2000; Finando D., Finando S., 2001; Lockart R.D. et al. ,1969). The human muscular system has three important functions(Finando D., Finando S., 2001; Ivanichev G.A., Staroseltseva N.G., 2002):

• the first function is to maintain the body and internal organs;
• the second function is the movement of the body as a whole, its individual parts and internal organs;
• the third function is metabolic.

All muscles of the human body have common basic properties, which are important for the functioning of the muscular system and complement each other:

1. excitability - the ability to perceive a nerve impulse and respond to it;

2. contractility - the ability to shorten when receiving an appropriate stimulus;

3. extensibility - the ability to lengthen under the influence of external force;

4. elasticity - the ability to return to normal shape after contraction or stretching.

Human muscular system represented by the following three types of muscles:

1. skeletal muscles;

2. visceral muscles;

3. heart muscle.

The main object of this teaching aid are skeletal muscles associated with movements of the spine and limbs. They are designed to perform static and dynamic tasks of the human body. For statics they must answer as follows requirements:

1. resist the forces of gravity with minimal energy consumption, ensuring a force balance between parts of the musculoskeletal system;

2. ensure the constancy of the internal endorhythm of the constituent elements of the musculoskeletal system.

For speakers Human skeletal muscles must perform the following functions:

• make movements of various regions of the spine and limbs in a certain sequence in the form of moving the body or its parts adequately for the purpose, in the appropriate volume;
• limit the spread of this movement to neighboring regions, ensure unidirectional execution of the movement.

Skeletal muscles are striated muscles. The total number of skeletal muscles in the human body is more than 600 (P.I. Begun, Yu.A. Shukeylo, 2000). Each skeletal muscle is a single organ with a complex structural organization (Khabirov F.A., Khabirov R.A., 1995; Petrov K.B., 1998; Begun P.I., Shukeylo Yu A., 2000; Ivanichev G.A., Staroseltseva N. G., 2002). Every muscle fiber is a multinucleated cylindrical cell surrounded by a membrane - the sarcolemma. Muscle cells contain nuclei and myofibrils shifted to the periphery.

Transverse membranes divide each myofibril into sarcomeres - structural units of myofibrils that have the ability to contract. Each myofibril is a chain made up of filaments. There are thick filaments - dark, anisotropic, consisting of myosin, and thin myofilaments - white, isotropic, consisting of actin. The proteins actin and myosin make up the actinomyosin complex, which provides muscle contraction under the influence of adenosine triphosphoric acid. Each muscle fiber is surrounded by a connective tissue membrane - endomysium, a group of fibers - perimysium, and the entire muscle - epimysium.

Skeletal muscles are attached to bones through the connecting part of the muscle - tendon. The auxiliary apparatus of muscles includes fascia, bursae, tendon sheaths, sesamoid bones. Fascia is a fibrous membrane that covers muscles and their individual groups. Synovial bursae containing synovial fluid are extra-articular cavities that protect the muscle from damage and reduce friction. Tendon sheaths are designed to protect the muscle tendons from being closely attached to the bones, making it easier for the muscles to work. In the thickness of some muscles there are sesamoid bones that improve muscle function. The largest sesamoid bone, the patella, is located in the tendon of the quadriceps femoris muscle.

In striated muscle tissue there are three types of fibers(Saprykin V.P., Turbin D.A., 1997, Makarova I.N., Epifanov V.A., 2002):

Type 1 - red, slow;

Type 2 - fast:

A - intermediate, red,

B - white.

Human muscle contains both white and red fibers, but in different proportions. Slow red fibers of type 1 have a well-developed capillary network, a large number of mitochondria and high activity of oxidative enzymes, which determines their significant aerobic endurance when performing work for a long time (Ivanichev G.A., Staroseltseva N.G., 2002). Type A red fast fibers 2 occupy an intermediate position between red slow fibers and white fast fibers. A distinctive feature of intermediate red fibers, which are classified as fast, is their ability to use energy during glycolysis in both the aerobic and anaerobic Krebs cycles.

Fast red fibers are low-fatigue muscle fibers. White muscle fibers contain a large number of myofibrils, due to which a large contraction force is developed. They belong to type 2 fast fibers B. Fast muscle fibers contain more glycolytic enzymes, less mitochondria and myoglobin, and have a small capillary network. The aerobic endurance of these fibers is low. They get tired easily and quickly.

Human skeletal muscles consist of extrafusal muscle fibers, specialized for contractile function, and intrafusal muscle fibers, representing the neuromuscular spindle (Khabirov F.A., Khabirov R.A., 1995).

The complex apparatus for supporting movements includes afferent and efferent parts (Karlov V.A., 1999; Khodos X.-B.G., 2001).

Krasnoyarova N.A.

Anatomical and physiological features of skeletal muscles and tests for their study

Muscle structure:

A - appearance bipennate muscle; B - diagram of a longitudinal section of the multipennate muscle; B - cross section of the muscle; D - diagram of the structure of muscle as an organ; 1, 1" - muscle tendon; 2 - anatomical diameter of the muscle belly; 3 - gate of the muscle with neurovascular bundle (a - artery, c - vein, n - nerve); 4 - physiological diameter (total); 5 - subtendinous bursa; 6-6" - bones; 7 - external perimysium; 8 - internal perimysium; 9 - endomysium; 9"-muscular fibers; 10, 10", 10" - sensitive nerve fibers (carry impulses from muscles, tendons, blood vessels); 11, 11" - motor nerve fibers (carry impulses to muscles, blood vessels)

STRUCTURE OF SKELETAL MUSCLE AS AN ORGAN

Skeletal muscles - musculus skeleti - are active organs of the movement apparatus. Depending on the functional needs of the body, they can change the relationship between bone levers (dynamic function) or strengthen them in a certain position (static function). Skeletal muscles, performing a contractile function, transform a significant part of the chemical energy received from food into thermal energy (up to 70%) and, to a lesser extent, into mechanical work (about 30%). Therefore, when contracting, a muscle not only performs mechanical work, but also serves as the main source of heat in the body. Together with the cardiovascular system, skeletal muscles actively participate in metabolic processes and the use of the body's energy resources. The presence of a large number of receptors in the muscles contributes to the perception of the muscular-articular sense, which, together with the organs of balance and organs of vision, ensures the execution of precise muscle movements. Skeletal muscles, together with subcutaneous tissue, contain up to 58% water, thereby fulfilling the important role of the main water depots in the body.

Skeletal (somatic) muscles are represented by a large number of muscles. Each muscle has a supporting part - the connective tissue stroma and a working part - the muscle parenchyma. The more static load a muscle performs, the more developed its stroma is.

On the outside, the muscle is covered with a connective tissue sheath called the external perimysium.

Perimysium. It has different thicknesses on different muscles. Connective tissue septa extend inward from the external perimysium - the internal perimysium, surrounding muscle bundles of various sizes. The greater the static function of a muscle, the more powerful the connective tissue partitions are located in it, the more of them there are. On the internal partitions in the muscles, muscle fibers can be attached, vessels and nerves pass through. Between the muscle fibers there are very delicate and thin connective tissue layers called endomysium - endomysium.

The stroma of the muscle, represented by the external and internal perimysium and endomysium, contains muscle tissue (muscle fibers that form muscle bundles), forming a muscle belly of various shapes and sizes. The muscle stroma at the ends of the muscle belly forms continuous tendons, the shape of which depends on the shape of the muscles. If the tendon is cord-shaped, it is simply called a tendon - tendo. If the tendon is flat and comes from a flat muscular belly, then it is called an aponeurosis - aponeurosis.

The tendon is also distinguished between outer and inner sheaths (mesotendineum). The tendons are very dense, compact, form strong cords that have high tensile strength. Collagen fibers and bundles in them are located strictly longitudinally, due to which the tendons become a less fatigued part of the muscle. Tendons are attached to the bones, penetrating the fibers into the thickness of the bone tissue (the connection with the bone is so strong that the tendon is more likely to rupture than it comes off the bone). Tendons can move to the surface of the muscle and cover them at a greater or lesser distance, forming a shiny sheath called the tendon mirror.

In certain areas, the muscle includes vessels that supply it with blood and nerves that innervate it. The place where they enter is called the organ gate. Inside the muscle, vessels and nerves branch along the internal perimysium and reach its working units - muscle fibers, on which the vessels form networks of capillaries, and the nerves branch into:

1) sensory fibers - come from the sensitive nerve endings of the proprioceptors, located in all parts of the muscles and tendons, and carry out an impulse sent through the spinal ganglion cell to the brain;

2) motor nerve fibers that carry impulses from the brain:

a) to muscle fibers, ending on each muscle fiber with a special motor plaque,

b) to the muscle vessels - sympathetic fibers carrying impulses from the brain through the sympathetic ganglion cell to the smooth muscles of the blood vessels,

c) trophic fibers ending on the connective tissue base of the muscle. Since the working unit of muscles is the muscle fiber, it is their number that determines

muscle strength; The strength of the muscle depends not on the length of the muscle fibers, but on the number of them in the muscle. The more muscle fibers there are in a muscle, the stronger it is. When contracting, the muscle shortens by half its length. To count the number of muscle fibers, a cut is made perpendicular to their longitudinal axis; the resulting area of ​​transversely cut fibers is the physiological diameter. The area of ​​the cut of the entire muscle perpendicular to its longitudinal axis is called the anatomical diameter. In the same muscle there can be one anatomical and several physiological diameters, formed if the muscle fibers in the muscle are short and have different directions. Since muscle strength depends on the number of muscle fibers in them, it is expressed by the ratio of the anatomical diameter to the physiological one. There is only one anatomical diameter in the muscle belly, but physiological ones can have different numbers (1:2, 1:3, ..., 1:10, etc.). A large number of physiological diameters indicates muscle strength.

Muscles are light and dark. Their color depends on their function, structure and blood supply. Dark muscles are rich in myoglobin (myohematin) and sarcoplasm, they are more resilient. Light muscles are poorer in these elements; they are stronger, but less resilient. In different animals, in at different ages and even in different parts of the body the color of the muscles can be different: in horses the muscles are darker than in other species of animals; young animals are lighter than adults; darker on the limbs than on the body.

CLASSIFICATION OF MUSCLES

Each muscle is an independent organ and has a specific shape, size, structure, function, origin and position in the body. Depending on this, all skeletal muscles are divided into groups.

Internal structure of the muscle.

Skeletal muscles, based on the relationship of muscle bundles with intramuscular connective tissue formations, can have very different structures, which, in turn, determines their functional differences. Muscle strength is usually judged by the number of muscle bundles, which determine the size of the physiological diameter of the muscle. The ratio of the physiological diameter to the anatomical one, i.e. area ratio cross section muscle bundles to the largest cross-sectional area of ​​the muscle belly, makes it possible to judge the degree of expression of its dynamic and static properties. Differences in these ratios make it possible to subdivide skeletal muscles into dynamic, dynamostatic, statodynamic and static.

The simplest ones are built dynamic muscles. They have a delicate perimysium, the muscle fibers are long, run along the longitudinal axis of the muscle or at a certain angle to it, and therefore the anatomical diameter coincides with the physiological 1:1. These muscles are usually associated more with dynamic loading. Possessing a large amplitude: they provide a large range of movement, but their strength is small - these muscles are fast, dexterous, but also quickly tire.

Statodynamic muscles have a more strongly developed perimysium (both internal and external) and shorter muscle fibers running in the muscles in different directions, i.e. forming already

Classification of muscles: 1 – single-joint, 2 – double-joint, 3 – multi-joint, 4 – muscles-ligaments.

Types of structure of statodynamic muscles: a - single-pinnate, b - bipinnate, c - multi-pinnate, 1 - muscle tendons, 2 - bundles of muscle fibers, 3 - tendon layers, 4 - anatomical diameter, 5 - physiological diameter.

many physiological diameters. In relation to one general anatomical diameter, a muscle may have 2, 3, or 10 physiological diameters (1:2, 1:3, 1:10), which gives grounds to say that static-dynamic muscles are stronger than dynamic ones.

Statodynamic muscles perform a largely static function during support, holding the joints straight when the animal is standing, when under the influence of body weight the joints of the limbs tend to bend. The entire muscle can be penetrated by a tendon cord, which makes it possible, during static work, to act as a ligament, relieving the load on the muscle fibers and becoming a muscle fixator (biceps muscle in horses). These muscles are characterized by great strength and significant endurance.

Static muscles can develop as a result of a large static load falling on them. Muscles that have undergone deep restructuring and have almost completely lost muscle fibers actually turn into ligaments that are capable of performing only a static function. The lower the muscles are located on the body, the more static they are in structure. They perform a lot of static work when standing and supporting the limb on the ground during movement, securing the joints in a certain position.

Characteristics of muscles by action.

According to its function, each muscle necessarily has two points of attachment on bone levers - the head and the tendon ending - the tail, or aponeurosis. In work, one of these points will be a fixed point of support - punctum fixum, the second - a moving point - punctum mobile. For most muscles, especially the limbs, these points change depending on the function performed and the location of the fulcrum. A muscle attached to two points (the head and the shoulder) can move its head when its fixed point of support is on the shoulder, and, conversely, will move the shoulder if during the movement the punctum fixum of this muscle is on the head.

Muscles can act on only one or two joints, but more often they are multi-joint. Each axis of movement on the limbs necessarily has two muscle groups with opposite actions.

When moving along one axis, there will definitely be flexor muscles and extensor muscles, extensors; in some joints, adduction-adduction, abduction-abduction, or rotation-rotation are possible, with rotation to the medial side called pronation, and rotation outward to the lateral side called supination.

There are also muscles that stand out - the fascia tensors - tensors. But at the same time, it is imperative to remember that depending on the nature of the load, the same

a multi-joint muscle can act as a flexor of one joint or as an extensor of another joint. An example is the biceps brachii muscle, which can act on two joints - the shoulder and the elbow (it is attached to the shoulder blade, throws over the top of the shoulder joint, passes inside the angle of the elbow joint and is attached to the radius). With a hanging limb, the punctum fixum of the biceps brachii muscle will be in the area of ​​the scapula, in this case the muscle pulls forward, bends the radius and elbow joint. When the limb is supported on the ground, the punctum fixum is located in the area of ​​the terminal tendon on the radius; the muscle already works as an extensor of the shoulder joint (holds the shoulder joint in an extended state).

If muscles have the opposite effect on a joint, they are called antagonists. If their action is carried out in the same direction, they are called “companions” - synergists. All muscles that flex the same joint will be synergists; the extensors of this joint will be antagonists in relation to the flexors.

Around the natural openings there are obturator muscles - sphincters, which are characterized by a circular direction of muscle fibers; constrictors, or constrictors, which are also

belong to the type of round muscles, but have a different shape; dilators, or dilators, open natural openings when contracting.

According to anatomical structure muscles are divided depending on the number of intramuscular tendon layers and the direction of the muscle layers:

single-pinnate - they are characterized by the absence of tendon layers and muscle fibers are attached to the tendon of one side;

bipinnate - they are characterized by the presence of one tendon layer and muscle fibers are attached to the tendon on both sides;

multipinnate - they are characterized by the presence of two or more tendon layers, as a result of which the muscle bundles are intricately intertwined and approach the tendon from several sides.

Classification of muscles by shape

Among the huge variety of muscles in shape, the following main types can be roughly distinguished: 1) Long muscles correspond to long levers of movement and therefore are found mainly on the limbs. They have a spindle-shaped shape, the middle part is called the abdomen, the end corresponding to the beginning of the muscle is the head, and the opposite end is the tail. The longus tendon has the shape of a ribbon. Some long muscles begin with several heads (multi-headed)

on various bones, which enhances their support.

2) Short muscles are located in those parts of the body where the range of movements is small (between individual vertebrae, between vertebrae and ribs, etc.).

3) Flat (wide) the muscles are located mainly on the torso and girdles of the limbs. They have an expanded tendon called an aponeurosis. Flat muscles have not only a motor function, but also a supporting and protective function.

4) Other forms of muscles are also found: square, circular, deltoid, serrated, trapezoidal, spindle-shaped, etc.

ACCESSORY ORGANS OF MUSCLES

When muscles work, conditions are often created that reduce the efficiency of their work, especially on the limbs, when the direction of muscle force during contraction occurs parallel to the direction of the lever arm. (The most beneficial action of muscle force is when it is directed at right angles to the lever arm.) However, the lack of this parallelism in muscle work is eliminated by a number of additional devices. For example, in places where force is applied, bones have bumps and ridges. Special bones are placed under the tendons (or set between the tendons). At joints, the bones thicken, separating the muscle from the center of movement at the joint. Simultaneously with the evolution of the muscular system of the body, auxiliary devices develop as an integral part of it, improving the working conditions of the muscles and helping them. These include fascia, bursae, synovial sheaths, sesamoid bones, and special blocks.

Accessory muscle organs:

A - fascia in the area of ​​the distal third of the horse's leg (on a transverse section), B - retinaculum and synovial sheaths of muscle tendons in the area of ​​the horse's tarsal joint from the medial surface, B - fibrous and synovial sheaths on longitudinal and B" - transverse sections;

I - skin, 2 - subcutaneous tissue, 3 - superficial fascia, 4 - deep fascia, 5 own muscle fascia, 6 - tendon own fascia (fibrous sheath), 7 - connections of the superficial fascia with the skin, 8 - interfascial connections, 8 - vascular - nerve bundle, 9 - muscles, 10 - bone, 11 - synovial sheaths, 12 - extensor retinaculum, 13 - flexor retinaculum, 14 - tendon;

a - parietal and b - visceral layers of the synovial vagina, c - mesentery of the tendon, d - places of transition of the parietal layer of the synovial vagina into its visceral layer, e - cavity of the synovial vagina

Fascia.

Each muscle, muscle group and all the musculature of the body is covered with special dense fibrous membranes called fasciae - fasciae. They tightly attract muscles to the skeleton, fix their position, helping to clarify the direction of the force of action of the muscles and their tendons, which is why surgeons call them muscle sheaths. Fascia demarcates muscles from each other, creates support for the muscle belly during its contraction, and eliminates friction between muscles. Fascia is also called the soft skeleton (considered a remnant of the membranous skeleton of vertebrate ancestors). They also help in the supporting function of the bone skeleton - the tension of the fascia during support reduces the load on the muscles and softens the shock load. In this case, the fascia takes on the shock-absorbing function. They are rich in receptors and blood vessels, and therefore, together with the muscles, they provide muscle-joint sensation. They play a very significant role in regeneration processes. So, if, when removing the affected cartilaginous meniscus in the knee joint, a flap of fascia is implanted in its place, which has not lost connection with its main layer (vessels and nerves), then with some training, after some time, an organ with the function of the meniscus is differentiated in its place, the work of the joint and the limbs as a whole are restored. Thus, by changing the local conditions of biomechanical load on the fascia, they can be used as a source of accelerated regeneration of structures of the musculoskeletal system during autoplasty of cartilage and bone tissue in restorative and reconstructive surgery.

With age, fascial sheaths thicken and become stronger.

Under the skin, the torso is covered with superficial fascia and connected to it by loose connective tissue. Superficial or subcutaneous fascia- fascia superficialis, s. subcutanea- Separates the skin from the superficial muscles. On the limbs, it can have attachments on the skin and bone protrusions, which, through contractions of the subcutaneous muscles, contributes to the implementation of shaking of the skin, as is the case in horses when they are freed from annoying insects or when shaking off debris stuck to the skin.

Located on the head under the skin superficial fascia of the head - f. superficialis capitis, which contains the muscles of the head.

Cervical fascia – f. cervicalis lies ventrally in the neck and covers the trachea. There is a distinction between the cervical fascia and the thoracoabdominal fascia. Each of them connects to each other dorsally along the supraspinous and nuchal ligaments and ventrally along the midline of the abdomen - linea alba.

The cervical fascia lies ventrally, covering the trachea. Its superficial sheet is attached to the petrous part of the temporal bone, the hyoid bone and the edge of the atlas wing. It passes into the fascia of the pharynx, larynx and parotid. Then it runs along the longissimus capitis muscle, gives rise to intermuscular septa in this area and reaches the scalene muscle, merging with its perimysium. The deep plate of this fascia separates the ventral muscles of the neck from the esophagus and trachea, is attached to the intertransverse muscles, passes to the fascia of the head in front, and caudally reaches the first rib and sternum, following further as the intrathoracic fascia.

Associated with the cervical fascia cervical subcutaneous muscle - m. cutaneus colli. It goes along the neck, closer to

her ventral surface and passes to the facial surface to the muscles of the mouth and lower lip.Thoracolumbar fascia – f. thoracolubalis lies dorsally on the body and is attached to the spinous

processes of the thoracic and lumbar vertebrae and maklok. The fascia forms a superficial and deep plate. The superficial one is fixed on the macular and spinous processes of the lumbar and thoracic. In the area of ​​the withers, it is attached to the spinous and transverse processes and is called the transverse spinous fascia. The muscles that go to the neck and head are attached to it. The deep plate is located only on the lower back, is attached to the transverse costal processes and gives rise to some abdominal muscles.

Thoracic fascia – f. thoracoabdominalis lies laterally on the sides of the chest and abdominal cavity and is attached ventrally along the white line of the abdomen - linea alba.

Associated with the thoracoabdominal superficial fascia pectoral, or cutaneous, muscle of the trunk - m. cutaneus trunci - quite extensive in area with longitudinally running fibers. It is located on the sides of the chest and abdominal walls. Caudally it gives off bundles into the knee fold.

Superficial fascia of the thoracic limb - f. superficialis membri thoraciciis a continuation of the thoracoabdominal fascia. It is significantly thickened in the wrist area and forms fibrous sheaths for the tendons of the muscles that pass here.

Superficial fascia of the pelvic limb - f. superficialis membri pelviniis a continuation of the thoracolumbar and is significantly thickened in the tarsal area.

Located under the superficial fascia deep, or fascia itself - fascia profunda. It surrounds specific groups of synergistic muscles or individual muscles and, attaching them in a certain position on a bone base, provides them with optimal conditions for independent contractions and prevents their lateral displacement. In certain areas of the body where more differentiated movement is required, intermuscular connections and intermuscular septa extend from the deep fascia, forming separate fascial sheaths for individual muscles, which are often referred to as their own fascia (fascia propria). Where group muscle effort is required, intermuscular partitions are absent and the deep fascia, acquiring particularly powerful development, has clearly defined cords. Due to local thickenings of the deep fascia in the area of ​​the joints, transverse, or ring-shaped, bridges are formed: tendon arches, retinaculum of muscle tendons.

IN areas of the head, the superficial fascia is divided into the following deep ones: The frontal fascia runs from the forehead to the dorsum of the nose; temporal - along the temporal muscle; parotid-masticatory covers the parotid salivary gland and the masticatory muscle; the buccal goes in the area of ​​the lateral wall of the nose and cheek, and the submandibular - on the ventral side between the bodies of the lower jaw. The buccal-pharyngeal fascia comes from the caudal part of the buccinator muscle.

Intrathoracic fascia - f. endothoracica lines the inner surface of the thoracic cavity. Transverse abdominal fascia – f. transversalis lines the inner surface of the abdominal cavity. Pelvic fascia – f. pelvis lines the inner surface of the pelvic cavity.

IN In the area of ​​the thoracic limb, the superficial fascia is divided into the following deep ones: fascia of the scapula, shoulder, forearm, hand, fingers.

IN area of ​​the pelvic limb, the superficial fascia is divided into the following deep ones: gluteal (covers the croup area), fascia of the thigh, lower leg, foot, fingers

During movement, fascia plays an important role as a device for sucking blood and lymph from underlying organs. From the muscle bellies, the fascia passes to the tendons, surrounds them and is attached to the bones, holding the tendons in a certain position. This fibrous sheath in the form of a tube through which the tendons pass is called fibrous tendon sheath - vagina fibrosa tendinis. The fascia may thicken in certain areas, forming band-like rings around the joint that attract a group of tendons that are thrown across it. They are also called ring ligaments. These ligaments are especially well defined in the area of ​​the wrist and tarsus. In some places, the fascia is the site of attachment of the muscle that tenses it,

IN in places of high tension, especially during static work, the fascia thickens, its fibers acquire different directions, not only helping to strengthen the limb, but also acting as a springy, shock-absorbing device.

Bursae and synovial vaginas.

In order to prevent friction of muscles, tendons or ligaments, soften their contact with other organs (bone, skin, etc.), facilitate sliding during large ranges of movement, gaps are formed between the sheets of fascia, lined with a membrane that secretes mucus or synovium, depending on which synovial and mucous bursae are distinguished. Mucous bursae - bursa mucosa – (isolated “bags”) formed in vulnerable places under the ligaments are called subglottis, under muscles - axillary, under tendons - subtendinous, under the skin - subcutaneous. Their cavity is filled with mucus and they can be permanent or temporary (calluses).

The bursa, which is formed due to the wall of the joint capsule, due to which its cavity communicates with the joint cavity, is called synovial bursa - bursa synovialis. Such bursae are filled with synovium and are located mainly in the areas of the elbow and knee joints, and their damage threatens the joint - inflammation of these bursae due to injury can lead to arthritis, therefore, in differential diagnosis, knowledge of the location and structure of synovial bursae is necessary, it determines the treatment and prognosis of the disease.

Somewhat more complexly built synovial tendon sheaths – vagina synovialis tendinis , in which long tendons pass, throwing over the carpal, metatarsal and fetlock joints. The synovial tendon sheath differs from the synovial bursa in that it has much larger dimensions (length, width) and a double wall. It completely covers the muscle tendon moving in it, as a result of which the synovial sheath not only performs the function of a bursa, but also strengthens the position of the muscle tendon over a significant extent.

Horse subcutaneous bursae:

1 - subcutaneous occipital bursa, 2 - subcutaneous parietal bursa; 3 - subcutaneous zygomatic bursa, 4 - subcutaneous bursa of the angle of the mandible; 5 - subcutaneous presternal bursa; 6 - subcutaneous ulnar bursa; 7 - subcutaneous lateral bursa of the elbow joint, 8 - subglottic bursa of the extensor carpi ulnaris; 9 - subcutaneous bursa of the abductor of the first finger, 10 - medial subcutaneous bursa of the wrist; 11 - subcutaneous precarpal bursa; 12 - lateral subcutaneous bursa; 13 - palmar (statar) subcutaneous digital bursa; 14 - subcutaneous bursa of the fourth metacarpal bone; 15, 15" - medial and lateral subcutaneous bursa of the ankle; /6 - subcutaneous calcaneal bursa; 17 - subcutaneous bursa of the tibial roughness; 18, 18" - subfascial subcutaneous prepatellar bursa; 19 - subcutaneous sciatic bursa; 20 - subcutaneous acetabular bursa; 21 - subcutaneous bursa of the sacrum; 22, 22" - subfascial subcutaneous bursa of the maclocus; 23, 23" - subcutaneous subglottic bursa of the supraspinous ligament; 24 - subcutaneous prescapular bursa; 25, 25" - subglottic caudal and cranial bursa of the nuchal ligament

Synovial sheaths form within fibrous sheaths that anchor long muscle tendons as they pass through joints. Inside, the wall of the fibrous vagina is lined with synovial membrane, forming parietal (outer) leaf this shell. The tendon passing through this area is also covered with a synovial membrane, its visceral (inner) sheet. Sliding during tendon movement occurs between the two layers of the synovial membrane and the synovium located between these leaves. The two layers of the synovial membrane are connected by a thin two-layer and short mesentery - the transition of the pariental layer to the visceral layer. The synovial vagina, therefore, is a thin two-layer closed tube, between the walls of which there is synovial fluid, which facilitates the sliding of a long tendon in it. In case of injuries in the area of ​​​​the joints where there are synovial sheaths, it is necessary to differentiate the sources of the released synovium, finding out whether it flows from the joint or the synovial sheath.

Blocks and sesamoid bones.

Blocks and sesamoid bones help improve muscle function. Blocks - trochlea - are certain shaped sections of the epiphyses of tubular bones through which muscles are thrown. They are a bony protrusion and a groove in it where the muscle tendon passes, due to which the tendons do not move to the side and the leverage for applying force increases. Blocks are formed where a change in the direction of muscle action is required. They are covered with hyaline cartilage, which improves muscle gliding; there are often synovial bursae or synovial sheaths. The blocks have a humerus and a femur.

Sesamoid bones - ossa sesamoidea - are bone formations that can form both inside muscle tendons and in the wall of the joint capsule. They form in areas of very strong muscle tension and are found in the thickness of the tendons. Sesamoid bones are located either at the top of a joint, or on the protruding edges of articulating bones, or where it is necessary to create a kind of muscle block in order to change the direction of muscle efforts during its contraction. They change the angle of muscle attachment and thereby improve their working conditions, reducing friction. They are sometimes called “ossified tendon areas,” but it must be remembered that they only go through two stages of development (connective tissue and bone).

The largest sesamoid bone, the patella, is set into the tendons of the quadriceps femoris muscle and slides along the epicondyles of the femur. Smaller sesamoid bones are located under the digital flexor tendons on the palmar and plantar sides of the fetlock (two for each) joint. On the joint side, these bones are covered with hyaline cartilage.

CLASSIFICATION OF MUSCLE FIBERS.

Morphological classification

Cross-striped (cross-striated)

Smooth (non-striated)

Classification by type of control of muscle activity

Cross-striped muscle tissue of skeletal type.

Smooth muscle tissue of internal organs.

Cardiac-type striated muscle tissue

CLASSIFICATION OF SKELETAL MUSCLE FIBERS

STRIPED MUSCLES represent the most specialized apparatus for carrying out rapid contractions. There are two types of striated muscles - skeletal and cardiac. SKELETAL muscles are composed of muscle fibers, each of which is a multinucleated cell resulting from the fusion of a large number of cells. Depending on contractile properties, color and fatigue, muscle fibers are divided into two groups - RED and WHITE. The functional unit of muscle fiber is the myofibril. Myofibrils occupy almost the entire cytoplasm of the muscle fiber, pushing the nuclei to the periphery.

RED MUSCLE fibers (type 1 fibers) contain a large number of mitochondria with high activity of oxidative enzymes. The strength of their contractions is relatively small, and the rate of energy consumption is such that they have enough aerobic metabolism (they use oxygen). They participate in movements that do not require significant efforts, - for example, in maintaining a pose.

WHITE MUSCLE FIBERS (type 2 fibers) are characterized by high activity of glycolytic enzymes, significant contractile force and such high speed energy consumption for which aerobic metabolism is no longer sufficient. Therefore, motor units consisting of white fibers provide fast but short-term movements that require jerking efforts.

CLASSIFICATION OF SMOOTH MUSCLES

Smooth muscles are divided into VISCERAL(UNITARY) AND MULTI-UNITARY. VISCERAL SMOOTH muscles are found in all internal organs, ducts of the digestive glands, blood vessels and lymphatic vessels, skin. TO MULIPIUNITARY include the ciliary muscle and the iris muscle. The division of smooth muscles into visceral and multiunitary is based on the different densities of their motor innervation. IN VISCERAL SMOOTH MUSCLES, motor nerve endings are present on a small number of smooth muscle cells.

FUNCTIONS OF SKELETAL AND SMOOTH MUSCLES.

FUNCTIONS AND PROPERTIES OF SMOOTH MUSCLES

1. ELECTRICAL ACTIVITY. Smooth muscles are characterized by unstable membrane potential. Fluctuations in membrane potential, regardless of neural influences, cause irregular contractions that maintain the muscle in a state of constant partial contraction - tone. The membrane potential of smooth muscle cells does not reflect the true value of the resting potential. When the membrane potential decreases, the muscle contracts; when it increases, it relaxes.

2. AUTOMATION. The action potentials of smooth muscle cells are autorhythmic in nature, similar to the potentials of the conduction system of the heart. This indicates that any smooth muscle cells are capable of spontaneous automatic activity. Automaticity of smooth muscles, i.e. the ability for automatic (spontaneous) activity is inherent in many internal organs and vessels.

3. RESPONSE TO TENSION. In response to stretch, smooth muscle contracts. This is because stretching reduces the cell membrane potential, increases AP frequency and, ultimately, smooth muscle tone. In the human body, this property of smooth muscles serves as one of the ways to regulate the motor activity of internal organs. For example, when the stomach is filled, its wall stretches. An increase in the tone of the stomach wall in response to its stretching helps maintain the volume of the organ and better contact of its walls with incoming food. In blood vessels, stretching caused by fluctuations in blood pressure.

4. PLASTICITY b. Voltage variability without a natural connection with its length. Thus, if a smooth muscle is stretched, its tension will increase, but if the muscle is held in the state of elongation caused by stretching, then the tension will gradually decrease, sometimes not only to the level that existed before the stretch, but also below this level.

5. CHEMICAL SENSITIVITY. Smooth muscles have high sensitivity to various physiologically active substances: adrenaline, norepinephrine. This is due to the presence of specific receptors on the smooth muscle cell membrane. If you add adrenaline or norepinephrine to a preparation of intestinal smooth muscle, the membrane potential increases, the frequency of AP decreases and the muscle relaxes, i.e., the same effect is observed as when the sympathetic nerves are excited.

FUNCTIONS AND PROPERTIES OF SKELETAL MUSCLES

Skeletal muscles are an integral part of the human musculoskeletal system. In this case, the muscles perform the following functions:

1) provide a certain posture of the human body;

2) move the body in space;

3) move individual parts of the body relative to each other;

4) are a source of heat, performing a thermoregulatory function.

Skeletal muscle has the following essential PROPERTIES:

1)EXCITABILITY- the ability to respond to a stimulus by changing ionic conductivity and membrane potential.

2) CONDUCTIVITY- the ability to conduct an action potential along and deep into the muscle fiber along the T-system;

3) CONTRACTIBILITY- the ability to shorten or develop tension when excited;

4) ELASTICITY- the ability to develop tension when stretching.

The human body is a complex and multifaceted system, each cell, each molecule of which is closely interconnected with others. Being in harmony with each other, they are able to ensure unity, which, in turn, manifests itself in health and longevity, however, with the slightest failure, the entire system can collapse in an instant. How does this complex mechanism work? How is its full functioning maintained and how can we prevent imbalance in a system that is harmonious and at the same time sensitive to external influences? These and other questions are revealed by human anatomy.

Fundamentals of Anatomy: Human Sciences

Anatomy is a science that tells about the external and internal structure of the body in a normal state and in the presence of all kinds of abnormalities. For ease of perception, anatomy considers the human structure in several planes, starting with small “grains of sand” and ending with large “bricks” that make up a single whole. This approach allows us to distinguish several levels of studying the organism:

• molecular and atomic,
• cellular,
• fabric,
• organ,
• systemic.

Molecular and cellular levels of a living organism

The initial stage of studying the anatomy of the human body considers the body as a complex of ions, atoms and molecules. Like most living beings, man is formed by all kinds of chemical compounds, which are based on carbon, hydrogen, nitrogen, oxygen, calcium, sodium and other micro- and macroelements. It is these substances, individually and in combination, that serve as the basis for the molecules of substances that make up the cellular composition of the human body.

Depending on the characteristics of shape, size and functions, different types of cells are distinguished. One way or another, each of them has a similar structure inherent in eukaryotes - the presence of a nucleus and various molecular components. Lipids, proteins, carbohydrates, water, salts, nucleic acids, etc. react with each other, thereby ensuring the performance of their assigned functions.

Human structure: anatomy of tissues and organs

Cells of similar structure and function, in combination with the intercellular substance, form tissues, each of which performs a number of specific tasks. Depending on this, 4 groups of tissues are distinguished in the anatomy of the human body:

• Epithelial tissue It has a dense structure and a small amount of intercellular substance. This structure allows it to cope well with protecting the body from external influences and absorbing nutrients from the outside. However, epithelium is present not only in the outer shell of the body, but also in internal organs, for example, glands. They are quickly restored with virtually no outside intervention, and therefore are considered the most versatile and durable.
• Connective tissues can be very diverse. They are distinguished by a large percentage of intercellular substance, which can be of any structure and density. Depending on this, the functions assigned to connective tissues vary - they can serve as support, protection and transport. nutrients for other tissues and cells of the body.
• A feature of muscle tissue is the ability to change its size, that is, to contract and relax. Thanks to this, she copes well with body coordination - moving both individual parts and the whole organism in space.
• Nervous tissue is the most complex and functional. Its cells control most of the processes occurring inside other organs and systems, but they cannot exist independently. All nervous tissue can be divided into 2 types: neurons and glia. The former ensure the transmission of impulses throughout the body, and the latter protect and nourish them.

A complex of tissues localized in a certain part of the body, having a clear shape and performing general function, is an independent body. As a rule, an organ is represented by various types of cells, however, a certain type of tissue always predominates, and the rest are rather auxiliary in nature.

In human anatomy, organs are conventionally classified into external and internal. The external or external structure of the human body can be seen and studied without any special instruments or manipulations, since all parts are visible to the naked eye. These include the head, neck, back, chest, torso, upper and lower limbs. In turn, the anatomy of internal organs is more complex, since its study requires invasive intervention, modern scientific and medical devices, or at least a visual didactic material. Internal structure represented by organs located inside the human body - kidneys, liver, stomach, intestines, brain, etc.

Organ systems in human anatomy

Despite the fact that each organ performs a specific function, they cannot exist separately - for normal life, complex work is necessary to support the functionality of the whole organism. That is why the anatomy of organs is not the highest level of studying the human body - it is much more convenient to consider the structure of the body from a systemic point of view. By interacting with each other, each system ensures the performance of the body as a whole.

In anatomy, it is customary to distinguish 12 body systems:

• musculoskeletal system,
• integumentary system,
• hematopoiesis,
• cardiovascular complex,
• digestion,
• immune,
• genitourinary complex,
• endocrine system,
• breath.

To study the human structure in detail, let’s consider each of the organ systems in more detail. Brief excursion the basis of the anatomy of the human body will help you navigate what the full functioning of the body as a whole depends on, how tissues, organs and systems interact and how to maintain health.

Anatomy of the musculoskeletal system

The musculoskeletal system is a frame that allows a person to move freely in space and maintains the volumetric shape of the body. The system includes the skeleton and muscle fibers, which closely interact with each other. The skeleton determines the size and shape of a person and forms certain cavities in which internal organs are placed. Depending on age, the number of bones in the skeletal system varies above 200 (in a newborn 270, in an adult 205–207), some of which act as levers, while the rest remain motionless, protecting organs from external damage. In addition, bone tissue is involved in the exchange of microelements, in particular phosphorus and calcium.

Anatomically, the skeleton consists of 6 key sections: the girdle of the upper and lower limbs, plus the limbs themselves, the spinal column and the skull. Depending on the functions performed, the composition of bones includes inorganic and organic matter in different proportions. More strong bones mainly consist of mineral salts, elastic - from collagen fibers. Outer layer bones is represented by a very dense periosteum, which not only protects bone tissue, but also provides it with the nutrition necessary for growth - it is from it that vessels and nerves penetrate into the microscopic tubules of the internal structure of the bone.

The connecting elements between individual bones are joints - a kind of shock absorbers that allow you to change the position of body parts relative to each other. However, connections between bone structures can be not only mobile: semi-movable joints are provided by cartilage of varying densities, and completely motionless joints are provided by bone sutures at the fusion sites.

The muscular system powers this entire complex mechanism, and also ensures the functioning of all internal organs through controlled and timely contractions. Skeletal muscle fibers are adjacent directly to the bones and are responsible for the mobility of the body, smooth muscle fibers serve as the basis for blood vessels and internal organs, and cardiac muscle fibers regulate the functioning of the heart, ensuring adequate blood flow, and therefore human vitality.

Superficial anatomy of the human body: integumentary system

The external structure of a person is represented by the skin, or, as it is commonly called in biology, the dermis, and mucous membranes. Despite their apparent insignificance, these organs play vital role in ensuring normal life activity: together with the mucous membranes, the skin is a huge receptor platform, thanks to which a person can tactilely sense various shapes effects, both pleasant and hazardous to health.

The integumentary system not only performs receptor function- its tissues are able to protect the body from destructive external influences, remove toxic and poisonous substances through micropores and regulate fluctuations in body temperature. Constituting about 15% of the total body weight, it is the most important boundary membrane that regulates the interaction of the human body and environment.

The hematopoietic system in the anatomy of the human body

Hematopoiesis is one of the main processes that maintain life inside the body. As a biological fluid, blood is present in 99% of all organs, providing them with adequate nutrition and, therefore, functionality. Together, the organs of the circulatory system are responsible for the formation of the formed elements of blood: red blood cells, leukocytes, lymphocytes and platelets, which serve as a kind of mirror reflecting the state of the body. It is with a general blood test that the diagnosis of the absolute majority of diseases begins - the functionality of the hematopoietic organs, and therefore the composition of the blood reacts sensitively to any change within the body, from a banal infectious or cold disease to dangerous pathologies. This feature allows you to quickly adapt to new conditions and recover faster by using the immune system and other reserve capabilities of the body.

All functions performed are clearly divided between the organs that make up the hematopoietic complex:

• lymph nodes guarantee the supply of plasma cells,
• bone marrow forms stem cells, which later transform into formed elements,
• peripheral vascular systems serve to transport biological fluid to other organs,
• The spleen filters the blood from dead cells.

All this together is a complex self-regulating mechanism, the slightest failure in which is fraught with serious pathologies affecting any of the body systems.

Cardiovascular complex

The system, which includes the heart and all vessels, from the largest to microscopic capillaries with a diameter of several microns, ensures blood circulation within the body, nourishing, saturating with oxygen, vitamins and microelements and cleansing every cell of the human body from decay products. This gigantic, complex network is most clearly demonstrated by human anatomy in pictures and diagrams, since it is practically impossible to theoretically understand how and where each specific vessel leads - their number in the adult body reaches 40 billion or more. However, this entire network is a balanced closed system, organized into 2 circles of blood circulation: large and small.

Depending on the volume and functions performed, vessels can be classified as follows:

1. Arteries are large tubular cavities with dense walls that consist of muscle, collagen and elastin fibers. Through these vessels, blood saturated with oxygen molecules is carried from the heart to numerous organs, providing them with adequate nutrition. The only exception is pulmonary artery, through which, unlike the others, blood moves to the heart.
2. Arterioles are smaller arteries that can change the size of the lumen. They serve as a link between large arteries and the small capillary network.
3. Capillaries are the smallest vessels with a diameter of no more than 11 microns, through the walls of which nutrient molecules leak from the blood into nearby tissues.
4. Anastomoses are arteriole-venular vessels that provide a transition from arterioles to venules, bypassing the capillary network.
5. Venules are as small as capillaries, vessels that provide the outflow of blood deprived of oxygen and useful particles.
6. Veins are larger vessels than venules, through which depleted blood with decay products moves to the heart.

The “engine” of such a large closed network is the heart - a hollow muscular organ, thanks to the rhythmic contractions of which blood moves through the vascular network. During normal operation, the heart pumps at least 6 liters of blood every minute, and approximately 8 thousand liters per day. It's no surprise that heart disease is one of the most serious and common - as we age, this biological pump wears out, so any changes in its functioning must be carefully monitored.

Human anatomy: organs of the digestive system

Digestion is a complex multi-stage process during which food entering the body is broken down into molecules, digested and transported to tissues and organs. This whole process begins in oral cavity, where, in fact, nutritional elements are supplied as part of the dishes included in the daily diet. There, large pieces of food are crushed and then moved into the pharynx and esophagus.

The stomach is a hollow muscular organ in the abdominal cavity and is one of the key links in the digestive chain. Despite the fact that digestion begins in the oral cavity, the main processes take place in the stomach - here some substances are immediately absorbed into the bloodstream, and some undergo further breakdown under the influence of gastric juice. The main processes occur under the influence of hydrochloric acid and enzymes, and mucus serves as a kind of shock absorber for further transport of food mass into the intestines.

In the intestines, gastric digestion is replaced by intestinal digestion. The bile coming from the duct neutralizes the effect of gastric juice and emulsifies fats, increasing their contact with enzymes. Further, throughout the entire length of the intestine, the remaining undigested mass is broken down into molecules and absorbed into the bloodstream through the intestinal wall, and everything that remains unclaimed is excreted in the feces.

In addition to the main organs responsible for transporting and breaking down nutrients, the digestive system includes:

• Salivary glands, tongue - are responsible for preparing the bolus of food for splitting.
• The liver is the largest gland in the body, which regulates the synthesis of bile.
• The pancreas is an organ necessary for the production of enzymes and hormones involved in metabolism.

The importance of the nervous system in the anatomy of the body

The complex, united by the nervous system, serves as a kind of control center for all processes of the body. It is here that the functioning of the human body is regulated, its ability to perceive and respond to any external stimulus. Guided by the functions and localization of specific organs of the nervous system, it is customary to distinguish several classifications in the anatomy of the body:

Central and peripheral nervous systems

The CNS, or central nervous system, is a complex of substances in the brain and spinal cord. Both are equally well protected from traumatic external influences by bone structures - the spinal cord is enclosed inside spinal column, and the head one is located in the cranial cavity. This structure of the body makes it possible to prevent damage to the sensitive cells of the brain substance at the slightest impact.

The peripheral nervous system extends from the spinal column to various organs and tissues. It is represented by 12 pairs of cranial and 31 pairs of spinal nerves, through which various impulses are transmitted with lightning speed from the brain to the tissues, stimulating or, conversely, suppressing their work depending on the various factors and a specific situation.

Somatic and autonomic nervous systems

The somatic department serves as a connecting element between the environment and the body. It is thanks to these nerve fibers that a person is able not only to perceive the surrounding reality (for example, “the fire is hot”), but also to respond adequately to it (“this means you need to remove your hand so as not to get burned”). This mechanism allows you to protect the body from unmotivated risks, adapt to the environment and correctly analyze information.

Vegetative system more autonomous, therefore reacts more slowly to outside influence. It regulates the activity of internal organs - glands, cardiovascular, digestive and other systems, and also maintains optimal balance in internal environment human body.

Anatomy of the internal organs of the lymphatic system

The lymphatic network, although less extensive than the circulatory network, is no less important for maintaining human health. It includes branched vessels and lymph nodes through which a biologically significant fluid moves - lymph, located in tissues and organs. Another difference between the lymphatic network and the circulatory network is its openness - the vessels carrying lymph do not close into a ring, ending directly in the tissues, from where excess fluid is absorbed and subsequently transferred to the venous bed.

Additional filtration occurs in the lymph nodes, allowing the lymph to be cleared of molecules of viruses, bacteria and toxins. By their reaction, doctors usually know that something has started in the body. inflammatory process, - the locations of the lymph nodes become swollen and painful, and the nodules themselves noticeably increase in size.

The main activities of the lymphatic system are as follows:

• transport of lipids absorbed from food into the bloodstream;
• maintaining a balanced volume and composition biological fluids body;
• evacuation of accumulated excess water in tissues (for example, with edema);
• protective function of lymph node tissue, in which antibodies are produced;
• filtering molecules of viruses, bacteria and toxins.

The role of immunity in human anatomy

On immune system is responsible for maintaining the health of the body under any external influence, especially of a viral or bacterial nature. The anatomy of the body is thought out in such a way that pathogenic microorganisms, when they get inside, quickly encounter the immune system, which, in turn, must not only recognize the origin of the “uninvited guest,” but also correctly respond to its appearance by connecting other reserves.

The classification of immune organs includes central and peripheral groups. The first includes bone marrow and thymus. Bone marrow It is represented by spongy tissue that is capable of synthesizing blood cells, including leukocytes, which are responsible for the destruction of foreign microbes. And the thymus, or thymus gland, is the site for the proliferation of lymphatic cells.

Peripheral organs responsible for immunity are more numerous. These include:

• Lymph nodes are the place of filtration and recognition of pathological microelements that have entered the body.
• The spleen is a multifunctional organ in which the deposition of blood elements, its filtration and the production of lymphatic cells are carried out.
• Areas of lymphoid tissue in organs are the place where antigens “work,” reacting with pathogens and suppressing them.

Thanks to the efficiency of the immune system, the body can cope with viral, bacterial and other diseases without seeking help from drug therapy. Strong immunity allows you to resist foreign microorganisms at the initial stage, thereby preventing the occurrence of the disease or at least ensuring its mild course.

Anatomy of the sense organs

The organs responsible for assessing and perceiving the realities of the external environment are the sense organs: vision, touch, smell, hearing and taste. It is through them that information reaches the nerve endings, which is processed at lightning speed and allows you to react correctly to the situation. For example, the sense of touch allows you to perceive information coming through the receptive field of the skin: to gentle stroking, a light massage, the skin instantly reacts with a barely noticeable increase in temperature, which is ensured by blood flow, while in case of painful sensations (for example, due to thermal effects or tissue damage), felt on the surface of dermal tissues, the body instantly reacts by narrowing blood vessels and slowing blood flow, which provides protection from deeper damage.

Vision, hearing and other senses allow us not only to react physiologically to changes in the external environment, but also to experience various emotions. For example, seeing a beautiful picture or listening to classical music, the nervous system sends signals to the body to relax, tranquility, and complacency; someone else's pain, as a rule, evokes compassion; and bad news means sadness and concern.

Genitourinary system in the anatomy of the human body

In some scientific sources, the genitourinary system is considered as 2 components: urinary and reproductive, however, due to the close relationship and adjacent location, it is still customary to combine them. The structure and functions of these organs vary greatly depending on gender, since they are responsible for one of the most complex and mysterious processes of interaction between the sexes - reproduction.

In both women and men, the urinary group is represented by the following organs:

• Kidneys are paired organs that remove excess water and toxic substances from the body, and also regulate the volume of blood and other biological fluids.
• Bladder- a cavity consisting of muscle fibers in which urine accumulates until it is excreted.
• Urethra, or urethra- the path along which urine is evacuated from the bladder after it is filled. For men it is 22–24 cm, and for women it is only 8.

Reproductive component genitourinary system varies greatly depending on gender. So, in men, it includes the testicles with appendages, seminal glands, prostate, scrotum and penis, which together are responsible for the formation and evacuation of seminal fluid. Women's reproductive system is more complex, since it is the fair sex who bears the responsibility for bearing a child. It includes the uterus and fallopian tubes, a pair of ovaries with appendages, the vagina and external genitalia - the clitoris and 2 pairs of labia.

Anatomy of the endocrine system organs

Endocrine organs mean a complex of various glands that synthesize special substances in the body - hormones responsible for the growth, development and full flow of many biological processes. The endocrine group of organs includes:

1. The pituitary gland is a small “pea” in the brain that produces about a dozen different hormones and regulates the growth and reproduction of the body, is responsible for maintaining metabolism, blood pressure and urination.
2. The thyroid gland, located in the neck, controls the activity of metabolic processes, is responsible for balanced growth, intellectual and physical development personality.
3. The parathyroid gland is a regulator of calcium and phosphorus absorption.
4. The adrenal glands produce adrenaline and norepinephrine, which not only control behavior stressful situation, but also affect heart contractions and the condition of blood vessels.
5. The ovaries and testes are exclusively sex glands that synthesize hormones necessary for normal sexual function.

Any, even the most minimal, damage to the endocrine glands can cause serious hormonal imbalance, which, in turn, will lead to malfunctions in the functioning of the body as a whole. That is why blood testing for hormone levels is one of the basic studies in the diagnosis of various pathologies, especially those related to reproductive function and all kinds of developmental disorders.

The function of breathing in human anatomy

The human respiratory system is responsible for saturating the body with oxygen molecules, as well as removing waste carbon dioxide and toxic compounds. Essentially, these are tubes and cavities connected in series, which are first filled with inhaled air and then expel carbon dioxide from inside.

The upper respiratory tract is represented by the nasal cavity, nasopharynx and larynx. There the air is warmed to a comfortable temperature, preventing hypothermia of the lower parts of the respiratory complex. In addition, nasal mucus moisturizes too dry streams and envelops dense tiny particles that can injure sensitive mucous membranes.

The lower respiratory tract begins with the larynx, in which not only the breathing function is carried out, but also the voice is formed. When the vocal cords of the larynx vibrate, a sound wave arises, but it is transformed into articulate speech only in the oral cavity, with the help of the tongue, lips and soft palate.

Next, the air flow penetrates the trachea - a tube of two dozen cartilaginous half-rings, which is adjacent to the esophagus and subsequently splits into 2 separate bronchi. Then the bronchi, which flow into the lung tissue, branch into smaller bronchioles, etc., until the formation of the bronchial tree. The very same lung tissue, consisting of alveoli, is responsible for gas exchange - the absorption of oxygen from the bronchi and the subsequent release of carbon dioxide.

Afterword

The human body is a complex and unique structure that is capable of independently regulating its work, responding to the slightest changes in the environment. Basic knowledge of human anatomy will definitely be useful to anyone who seeks to preserve their body, since the normal functioning of all organs and systems is the basis of health, longevity and full life. Understanding how this or that process occurs, what it depends on and how it is regulated, you will be able to suspect, identify and correct the problem in time, without letting it take its course!

Muscles are one of the main components of the body. They are based on tissue whose fibers contract under the influence of nerve impulses, allowing the body to move and stay in its environment.

Muscles are located in every part of our body. And even if we don’t know about their existence, they still exist. It is enough, for example, to go to Gym or do aerobics - the next day you will start to ache even those muscles that you didn’t even know you had.

They are responsible not only for movement. At rest, muscles also require energy to maintain their tone. This is necessary so that at any moment a certain one can respond to a nerve impulse with the appropriate movement, and does not waste time on preparation.

To understand how muscles are structured, we suggest remembering the basics, repeating the classification and looking into the cellular. We will also learn about diseases that can worsen their function, and how to strengthen skeletal muscles.

General concepts

According to their filling and the reactions that occur, muscle fibers are divided into:

• striated;
• smooth.

Skeletal muscles are elongated tubular structures, the number of nuclei in one cell can reach several hundred. They consist of muscle tissue that is attached to various parts bone skeleton. Contractions of striated muscles contribute to human movements.

Varieties of forms

How are muscles different? The photos presented in our article will help us figure this out.

Skeletal muscles are one of the main components of the musculoskeletal system. They allow you to move and maintain balance, and are also involved in the process of breathing, voice production and other functions.

There are more than 600 muscles in the human body. As a percentage, their total mass is 40% of the total body mass. Muscles are classified by shape and structure:

• thick fusiform;
• thin lamellar.

Classification makes learning easier

The division of skeletal muscles into groups is carried out depending on their location and significance in activity various organs bodies. Main groups:

Muscles of the head and neck:

• facial expressions - are used when smiling, communicating and creating various grimaces, while ensuring the movement of the constituent parts of the face;
• chewing - promote a change in the position of the maxillofacial region;
• voluntary muscles of the internal organs of the head (soft palate, tongue, eyes, middle ear).

Skeletal muscle groups of the cervical spine:

• superficial - promote inclined and rotational movements of the head;
• middle ones - create the lower wall of the oral cavity and promote downward movement of the jaw and laryngeal cartilages;
• deep ones tilt and turn the head, create elevation of the first and second ribs.

The muscles, photos of which you see here, are responsible for the torso and are divided into muscle bundles of the following sections:

• thoracic - activates the upper torso and arms, and also helps to change the position of the ribs when breathing;
• abdominal section - allows blood to move through the veins, changes the position of the chest during breathing, affects the functioning of the intestinal tract, promotes flexion of the torso;
• dorsal - creates motor system upper limbs.

Muscles of the limbs:

• upper - consist of muscle tissue of the shoulder girdle and the free upper limb, help move the arm in the shoulder articular capsule and create movements of the wrist and fingers;
• lower - play the main role in a person’s movement in space, are divided into the muscles of the pelvic girdle and the free part.

Structure of skeletal muscle

In its structure it has great amount oblong in shape with a diameter of 10 to 100 microns, their length ranges from 1 to 12 cm. Fibers (microfibrils) are thin - actin, and thick - myosin.

The former consist of a protein that has a fibrillar structure. It's called actin. Thick fibers are composed of different types of myosin. They differ in the time it takes to decompose the ATP molecule, which causes different contraction rates.

Myosin in smooth muscle cells is dispersed, although there is a large amount of protein, which, in turn, is significant in prolonged tonic contraction.

The structure of skeletal muscle is similar to a rope or stranded wire woven from fibers. It is surrounded on top by a thin sheath of connective tissue called the epimysium. From its inner surface, deeper into the muscle, thinner branches of connective tissue extend, creating septa. Separate bundles of muscle tissue are “wrapped” in them, each containing up to 100 fibrils. Narrower branches extend from them even deeper.

The circulatory and nervous systems penetrate through all layers into the skeletal muscles. The arterial vein runs along the perimysium - this is connective tissue, covering bundles of muscle fibers. Arterial and venous capillaries are located nearby.

Development process

Skeletal muscles develop from the mesoderm. Somites are formed on the side of the neural groove. After time, myotomes are released into them. Their cells, taking on a spindle shape, evolve into myoblasts, which divide. Some of them progress, while others remain unchanged and form myosatellite cells.

A small part of myoblasts, due to the contact of the poles, creates contact with each other, then the plasma membranes disintegrate in the contact zone. Thanks to the fusion of cells, symplasts are created. Undifferentiated young people move in with them muscle cells, located in the same environment with the myosymplast of the basement membrane.

Functions of skeletal muscles

This muscle is the basis of the musculoskeletal system. If it is strong, it is easier to maintain the body in the desired position, and the likelihood of stooping or scoliosis is minimized. Everyone knows about the benefits of playing sports, so let’s look at the role that muscles play in this.

The contractile tissue of skeletal muscles performs many functions in the human body. various functions which are needed for correct location body and the interaction of its individual parts with each other.

Muscles perform the following functions:

• create body mobility;
• protect the thermal energy created inside the body;
• promote movement and vertical retention in space;
• promote contraction of the airways and help with swallowing;
• form facial expressions;
• promote heat production.

Ongoing support

When muscle tissue is at rest, there is always a slight tension in it, called muscle tone. It is formed due to minor impulse frequencies that enter the muscles from the spinal cord. Their action is determined by signals penetrating from the head to the spinal motor neurons. Muscle tone also depends on their general condition:

• sprains;
• level of filling of muscle cases;
• blood enrichment;
• general water and salt balance.

A person has the ability to regulate the level of muscle load. As a result of prolonged physical exercise or severe emotional and nervous stress, muscle tone involuntarily increases.

Skeletal muscle contractions and their types

This function is the main one. But even it, despite its apparent simplicity, can be divided into several types.

Types of contractile muscles:

• isotonic - the ability of muscle tissue to shorten without changes in muscle fibers;
• isometric - during the reaction, the fiber contracts, but its length remains the same;
• auxotonic - the process of contraction of muscle tissue, where the length and tension of the muscles are subject to changes.

Let's look at this process in more detail.

First, the brain sends an impulse through a system of neurons, which reaches the motor neuron adjacent to the muscle bundle. Next, the efferent neuron is innervated from the synoptic vesicle, and a neurotransmitter is released. It binds to receptors on the sarcolemma of the muscle fiber and opens a sodium channel, which leads to depolarization of the membrane causing, when present in sufficient quantities, the neurotransmitter to stimulate the production of calcium ions. It then binds to troponin and stimulates its contraction. This, in turn, pulls back tropomeasesin, allowing actin to combine with myosin.

Next, the process of actin filament sliding relative to the myosin filament begins, resulting in skeletal muscle contraction. A schematic diagram will help you understand the process of compression of striated muscle bundles.

How skeletal muscles work

The interaction of a large number of muscle bundles contributes to various movements of the body.

The work of skeletal muscles can occur in the following ways:

• synergistic muscles work in one direction;
• Antagonist muscles promote opposite movements to produce tension.

The antagonistic action of muscles is one of the main factors in the activity of the musculoskeletal system. When performing any action, not only the muscle fibers that perform it, but also their antagonists are included in the work. They promote resistance and give the movement concreteness and grace.

When acting on a joint, striated skeletal muscle performs complex work. Its character is determined by the location of the joint axis and the relative position of the muscle.

Some functions of skeletal muscle are poorly understood and often not discussed. For example, some of the bundles act as a lever for the operation of the bones of the skeleton.

Muscle work at the cellular level

The action of skeletal muscles is carried out by two proteins: actin and myosin. These components have the ability to move relative to each other.

For muscle tissue to work, it is necessary to consume energy contained in chemical bonds. organic compounds. The breakdown and oxidation of such substances occurs in the muscles. There is always air present here, and energy is released, 33% of all this is spent on the performance of muscle tissue, and 67% is transferred to other tissues and spent on maintaining a constant body temperature.

Diseases of the skeletal muscles

In most cases, deviations from the norm in muscle functioning are due to the pathological state of the responsible parts of the nervous system.

The most common pathologies of skeletal muscles:

• Muscle cramps are an imbalance of electrolyte in the extracellular fluid surrounding muscle and nerve fibers, as well as changes in osmotic pressure in it, especially its increase.
• Hypocalcemic tetany is an involuntary tetanic contraction of skeletal muscle observed when the extracellular Ca2+ concentration falls to approximately 40% of normal levels.
• characterized by progressive degeneration of skeletal muscle fibers and myocardium, as well as muscle disability, which can lead to fatal outcome due to respiratory or heart failure.
• Myasthenia gravis is a chronic autoimmune disease in which antibodies to the nicotinic ACh receptor are formed in the body.

Relaxation and restoration of skeletal muscles

Proper nutrition, lifestyle and regular exercise will help you become the owner of healthy and beautiful skeletal muscles. It is not necessary to exercise and build muscle mass. Regular cardio training and yoga are enough.

Do not forget about the mandatory intake of essential vitamins and minerals, as well as regular visits saunas and baths with brooms, which allow you to enrich with oxygen muscle tissue and blood vessels.

Systematic relaxing massages will increase the elasticity and reproduction of muscle bundles. Visiting a cryosauna also has a positive effect on the structure and functioning of skeletal muscles.