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How are human muscles located? Muscular system

PLAN

Introduction

1. The structure of skeletal muscles

2. Major muscle groups

3. Muscle work

4. Smooth muscles

5. Age features muscular system

Bibliography


Introduction

Whatever a person does - walking, running, driving a car, digging the ground, writing - he performs all his actions with the help of skeletal muscles. These muscles are the active part of the musculoskeletal system. They hold the body in an upright position, allow you to take a variety of poses. The abdominal muscles support and protect the internal organs, i.e. perform supporting and protective functions. Muscles are part of the walls of the chest and abdominal cavities, the walls of the pharynx, provide movements of the eyeballs, auditory ossicles, respiratory and swallowing movements. This is only a partial list of skeletal muscle functions.

Therefore, it is not surprising that the mass of skeletal muscles in an adult is 30-35% of body weight. A person has more than 600 skeletal muscles, they are formed by striated muscle tissue.


1. The structure of skeletal muscles

1 - Scheme of the structure of the muscle fiber:

a - myofibril

2 - Scheme of the structure of myofibrils:

a - shell

b - myosin

c - actin

g - a bridge between them

d - nerve fiber

Each muscle consists of parallel bundles of striated muscle fibers. Each bundle is dressed in a sheath. And the whole muscle is covered on the outside with a thin connective tissue sheath that protects the delicate muscle tissue. Each muscle fiber also has a thin shell on the outside, and inside it there are numerous thin contractile filaments - myofibrils and a large number of nuclei. Myofibrils, in turn, consist of the thinnest filaments of two types - thick (myosin protein molecules) and thin (actin protein). Because they are educated various types protein, under the microscope, alternating dark and light stripes are visible. Hence the name skeletal muscle tissue- cross-striped. In humans, skeletal muscle consists of two types of fibers - red and white. They differ in the composition and number of myofibrils, and most importantly, in the features of contraction. The so-called white muscle fibers contract quickly, but quickly get tired; red fibers contract more slowly, but may remain contracted for a long time. Depending on the function of the muscles, certain types of fibers predominate in them. Muscles do a lot of work, so they are rich in blood vessels, through which blood supplies them with oxygen, nutrients, and removes metabolic products. Muscles are attached to bones by inextensible tendons that fuse with the periosteum. Usually, the muscles are attached at one end above, and at the other below the joint. With this attachment, muscle contraction sets the bones in motion at the joints.

2. Major muscle groups

Depending on the location of the muscles can be divided into the following large groups: muscles of the head and neck, muscles of the trunk and muscles of the limbs.

1. Superficial finger flexor.

2. Large pectoral muscle.

3. Deltoid muscle.

4. The biceps of the shoulder.

5. Fibrous plate.

6. Radial flexor of fingers.

7. Serratus anterior.

8. Quadriceps muscle.

9. Tailor muscle of the thigh.

10. Tibialis anterior.

11. Cruciate muscle.

12. Calf muscle.

13. Biceps muscle.

14. Large gluteal muscle.

15. External oblique abdominal muscle.

16. Triceps of the shoulder.

17. Biceps femoris.

18. Deltoid muscle.

19. Trapezius muscle.

20. Infraspinatus muscle.

21. Rhomboid muscle.

22. Biceps muscle of the shoulder.

The muscles of the trunk include the muscles of the back, chest and abdomen. There are superficial muscles of the back (trapezius, latissimus dorsi, etc.) and deep muscles of the back. The superficial muscles of the back provide movement for the limbs and partly for the head and neck; deep muscles are located between the vertebrae and ribs and, when contracted, cause extension and rotation of the spine, maintain the vertical position of the body.

The muscles of the chest are divided into those attached to the bones of the upper limbs (pectoralis major and minor, serratus anterior, etc.), which move upper limb, and the actual chest muscles (pectoralis major and minor, serratus anterior, etc.), which change the position of the ribs and thereby ensure the act of breathing. This group of muscles also includes the diaphragm, located on the border of the chest and abdominal cavity. The diaphragm is a respiratory muscle. During contraction, it descends, its dome flattens (the volume of the chest increases - an inhalation occurs), when relaxed, it rises and takes the form of a dome (the volume of the chest decreases - an exhalation occurs). The diaphragm has three openings - for the esophagus, aorta and inferior vena cava.

The muscles of the upper limb are divided into muscles shoulder girdle and free upper limb. The muscles of the shoulder girdle (deltoid, etc.) ensure the movement of the arm in the area shoulder joint and movement of the scapula. The muscles of the free upper limb contain the muscles of the shoulder (the anterior group of flexor muscles in the shoulder and elbow joint- biceps muscle of the shoulder, etc.); the muscles of the forearm are also divided into two groups (anterior - flexors of the hand and fingers, back - extensors); hand muscles provide a variety of finger movements.

The muscles of the lower limb are divided into the muscles of the pelvis and the muscles of the free lower limb (muscles of the thigh, lower leg, foot). The pelvic muscles include the iliopsoas, large, middle and small gluteal, etc. They provide flexion and extension in the hip joint, as well as maintaining the vertical position of the body. Three groups of muscles are distinguished on the thigh: anterior (quadriceps femoris and others extend the lower leg and flex the thigh), posterior (biceps femoris and others extend the lower leg and flex the thigh) and the internal group of muscles that bring the thigh to the midline of the body and flex hip joint. Three groups of muscles are also distinguished on the lower leg: anterior (unbend the fingers and foot), posterior (calf, soleus, etc., flex the foot and fingers), external (bend and abduct the foot).

Among the muscles of the neck, superficial, middle (muscles of the hyoid bone) and deep groups are distinguished. Of the superficial, the largest sternocleidomastoid muscle tilts back and turns the head to the side. The muscles located above the hyoid bone form the lower wall of the oral cavity and lower lower jaw. The muscles located below the hyoid bone lower the hyoid bone and provide mobility to the cortan cartilage. deep muscles the necks tilt or turn the head and raise the first and second ribs, acting as breathing muscles.

The muscles of the head make up three groups of muscles: chewing, facial and voluntary muscles. internal organs head (soft palate, tongue, eyes, middle ear). Chewing muscles move the lower jaw. Mimic muscles attached at one end to the skin, the other - to the bone (frontal, buccal, zygomatic, etc.) or only to the skin ( circular muscle mouth). By contracting, they change the expression of the face, participate in the closing and expansion of the openings of the face (eye sockets, mouth, nostrils), provide mobility for the cheeks, lips, nostrils.

3. Muscle work

Muscles, contracting or tensing, produce work. It can be expressed in the movement of the body or its parts. Such work is done by lifting weights, walking, running. This is dynamic work. When holding parts of the body in a certain position, holding a load, standing, maintaining a pose, static work is performed. The same muscles can perform both dynamic and static work. By contracting, the muscles move the bones, acting on them as levers. The bones begin to move around the fulcrum under the influence of the force applied to them. Movement in any joint is provided by at least two muscles acting in opposite directions. They are called flexor muscles and extensor muscles. For example, when bending the arm, the biceps brachii muscle contracts, and triceps relaxes. This is because stimulation of the biceps through the central nervous system causes relaxation of the triceps. Skeletal muscles are attached on both sides of the joint and, when contracted, produce movement in it. Usually, the muscles that perform flexion - flexors - are located in front, and those that produce extension - extensors - are behind the joint. Only in the knee ankle joints the anterior muscles, on the contrary, produce extension, and the posterior muscles produce flexion. The muscles lying outside (laterally) from the joint - abductors - perform the function of abduction, and those lying medially (medially) from it - adductors - adduction. Rotation is produced by muscles located obliquely or transversely with respect to the vertical axis (pronators - rotating inwards, arch supports - outwards). Several muscle groups are usually involved in the implementation of the movement. Muscles that simultaneously produce movement in one direction in a given joint are called synergists (shoulder, biceps shoulder); muscles that perform the opposite function (biceps, triceps muscle of the shoulder) - antagonists. The work of various muscle groups occurs in concert: for example, if the flexor muscles contract, then the extensor muscles relax at this time. "Start up" the muscles in the course of nerve impulses. An average of 20 impulses per second enters one muscle. In each step, for example, up to 300 muscles take part and many impulses coordinate their work. The number of nerve endings in various muscles unequally. There are relatively few of them in the muscles of the thigh, and oculomotor muscles, making subtle and precise movements all day long, are rich in motor nerve endings. The cerebral cortex is unevenly connected with individual groups muscles. For example, huge areas of the cortex are occupied by motor areas that control the muscles of the face, hand, lips, and foot, and relatively small areas are occupied by the muscles of the shoulder, thigh, and lower leg. The size of individual zones of the motor area of ​​the cortex is proportional not to the mass of muscle tissue, but to the subtlety and complexity of the movements of the corresponding organs. Each muscle has a double nerve subordination. One nerve sends impulses from the brain and spinal cord. They cause muscle contraction. Others, moving away from the nodes that lie on the sides of the spinal cord, regulate their nutrition. The nerve signals that control the movement and nutrition of the muscle are consistent with the nervous regulation of the blood supply to the muscle. It turns out a single triple nervous control.

Or they are part of the internal organs themselves. The mass of muscles is much greater than the mass of other organs: in vertebrates it can reach up to 50% of the total body mass, in an adult - up to 40%. Animal muscle tissue is also called meat and, along with some other components of animal bodies, is eaten. In muscle tissue, chemical energy is converted into mechanical energy and heat.

In vertebrates, muscles are divided into two main groups:

  • Somatic(i.e. enclosed in the walls of the body cavities (“soma”), containing the insides, and also forming the bulk of the limbs):
    • Skeletal muscles(they are also striated, or arbitrary). Attached to bones. Consist of very long fibers, length from 1 to 10 cm, shape - cylindrical. Their transverse striation is due to the presence of alternating birefringent transmitted light disks - anisotropic, darker, and single-refracting light - isotropic, lighter. Each muscle fiber consists of an undifferentiated cytoplasm, or sarcoplasm, with numerous nuclei located at the periphery, which contains big number differentiated striated myofibrils. The periphery of the muscle fiber is surrounded by a transparent membrane, or sarcolemma, containing fibrils of a collagen nature. Small groups of muscle fibers are surrounded by a connective tissue sheath - endomysium, endomysium; larger complexes are represented by bundles of muscle fibers, which are enclosed in loose connective tissue - the inner perimysium, perimysium internum; the entire muscle as a whole is surrounded by an external perimysium, perimysium externum. All connective tissue structures of the muscle, from the sarcolemma to the outer perimysium, are a continuation of each other and are continuously interconnected. The entire muscle is dressed in a connective tissue case - fascia, fascia. Each muscle has one or more nerves and blood vessels supplying it. Both of them penetrate into the thickness of the muscle in the area of ​​the so-called neurovascular field, area nervovasculosa. With the help of muscles, the balance of the body is maintained, movement is made in space, respiratory and swallowing movements are carried out. These muscles contract by force of will under the influence of impulses coming to them along the nerves from the central nervous system. Characterized by powerful and fast contractions and fast development fatigue.
  • Visceral(i.e., part of the viscera, functionally not adapted to the movement of the body in space):
    • Smooth muscles(involuntary). They are found in the walls of internal organs and blood vessels. They are characterized by length: 0.02 -0.2 mm, shape: fusiform, one oval core in the center, no striation. These muscles are involved in transporting the contents of hollow organs, such as food through the intestines, in the regulation of blood pressure, constriction and expansion of the pupil, and other involuntary movements within the body. Smooth muscles contract under the action of the autonomic nervous system. Characterized by slow rhythmic contractions that do not cause fatigue.
    • cardiac muscle. It exists only in the heart. This muscle contracts tirelessly throughout life, ensuring the movement of blood through the vessels and the delivery of vital substances to the tissues. The heart muscle contracts spontaneously, and the autonomic nervous system only regulates its work.

There are about 400 striated muscles in the human body, the contraction of which is controlled by the central nervous system.

Functions of the muscular system

  • motor;
  • protective (for example, protection of the abdominal cavity with the abdominal press);
  • forming (muscle development to some extent determines the shape of the body) and the function of other systems (for example, respiratory);
  • energy (conversion of chemical energy into mechanical and thermal).
Human organ systems
Cardiovascular system (heart, blood vessels) Lymphatic system Digestive system Endocrine system Immune system Sensory system (somatosensory system, visual system, olfactory sensory system, auditory sensory system, gustatory sensory system) Integumentary system Nervous system (central, peripheral) Musculoskeletal system (skeletal system, muscular system) genitourinary system (reproductive system, urinary system) Respiratory system

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See what the "Muscular system" is in other dictionaries:

    MUSCULAR SYSTEM- MUSCULAR SYSTEM. Contents: I. Comparative anatomy..........387 II. Muscles and their accessories. 372 III. Classification of muscles............375 IV. Muscle Variations...............378 V. Methodology for Examining Muscles on Fragility. . 380 VI.… … Big Medical Encyclopedia

    The muscular system, the totality of contractions, elements of muscle tissue, usually combined into muscles and interconnected by connective tissue. In unicellular and lower multicellular animals (Trichoplax, sponges) M. s. No. In intestinal ... ... Biological encyclopedic dictionary

    A collection of muscles and muscle bundles, usually united by connective tissue. Absent in unicellular and sponges, well developed in vertebrates (makes 1/3 1/2 body weight). Carries out the movement of the body, maintaining the balance of the body, and ... ... Big Encyclopedic Dictionary

    A collection of muscles and muscle bundles, usually united by connective tissue. Absent in unicellular and sponges, well developed in vertebrates (makes 1/3 1/2 body weight). Carries out the movements of the body, maintaining the balance of the body, and ... ... encyclopedic Dictionary

    Muscular system, a set of contractile elements, muscle cells, usually combined in animals and humans into Muscles and interconnected by connective tissue. In unicellular, sponges, coelenterates and some non-intestines ... ... Great Soviet Encyclopedia

    The totality of muscles and muscle bundles combined usually connects. cloth. Absent in unicellular and sponges, well developed in vertebrates (makes 1/3 1/2 body weight). Carries out the movements of the body, maintaining the balance of the body, as well as ... ... Natural science. encyclopedic Dictionary

    MUSCULAR SYSTEM- (Systema musculorum), a set of anatomical structures that provide a change in the position of the body (or its parts) in space. In structure M. page. includes muscles and their auxiliary elements: tendons, ligaments, synovial sheaths ... Veterinary Encyclopedic Dictionary

    MUSCULAR SYSTEM- [from Greek. systema (whole), composed of parts, connection] a set of contractile elements of muscle tissue, combined into muscles and interconnected by connective tissue ... Psychomotor: Dictionary Reference

    The muscular system is one of the main biological subsystems in higher animals, thanks to which movement in the body is carried out in all its manifestations. The muscular system is absent in unicellular and sponges, however, these animals are not without ... ... Wikipedia

Books

  • Atlas of Sectional Human Anatomy Musculoskeletal System, Meller T., Rife E., This book- a solid work created on the basis of great experience and deep knowledge of the authors in the field of MRI diagnostics, which uses the original way of presenting the material.… Category:

It is still desirable for an athlete and just an adult involved in fitness to know about the structure of muscles and what functions they perform. For this, a diagram of the structure of human muscles is given below. As well as a photo describing the large muscles of a person.

Human muscle structure - diagram

Rice. 1. Human muscles (front view): 1 - frontal belly of the occipital-frontal muscle; 2 - circular muscle of the mouth; 3 - chin; 4 - sternohyoid; 5 - trapezoid; 6 - three-headed shoulder ; 7 - straight abdomen; 8 - external oblique abdomen; 9 - radial flexor brushes; 10 - pulling wide fascia hips; 11 - iliac-lumbar; 12 - comb, 13 - long adductor; 14 - tailor; 15 - straight thigh; 16 - tender; 17 - internal wide; 18 - abducting thumb; 19 - tendons long muscle, extensor fingers; 20 - long muscle, extensor fingers; 21 - soleus; 22 - anterior tibial; 23 - gastrocnemius; 24 - outer wide; 25 - a short muscle that extends the thumb; 26 - a long muscle that removes the thumb; 27 - ulnar extensor of the hand; 28 - short radial extensor of the hand; 29 - extensor of the fingers; 30 - long radial extensor of the hand; 31 - brachioradial; 32 - three-headed shoulder; 33 - front gear; 34- biceps shoulder; 35 - large chest; 36 - deltoid; 37 - front staircase; 38 - middle staircase; 39 - sternocleidomastoid; 40 - lowering the corner of the mouth; 41 - chewing; 42 - large zygomatic; 43 - temporal.

Rice. 2. Human muscles (back view): 1 - occipital belly of the occipital-frontal muscle; 2- trapezoid; 3 - deltoid; 4 - three-headed shoulder; 5 - double-headed shoulder: 6 - round pronator; 7 and 23 - brachioradial; 8 - radial flexor of the hand; 9 - long palmar; 10 - elbow flexor of the hand; 11 - superficial finger flexor; 12 and 13 - semi-membranous; 13 - semitendinosus; 14 - tender; 15 - two-headed thigh; 17 - gastrocnemius; 18 - soleus; 19 - large gluteal; 20 - short muscle that abducts the thumb; 21 - middle gluteal; 22 - external oblique abdomen; 24 - broadest back; 25 - front gear; 26 - large round; 27 - small round; 28 - cavity; 29 - sternocleidomastoid; 30 - belt head; 31 - chewing; 32 - semi-spinous heads; 33 - temporal.

Human muscles: photo with description

Let's briefly analyze the large muscles, and to make the structure of the human muscular system clearer, the names of the human muscles in pictures are given.

Upper shoulder girdle

Biceps brachii (biceps)- flexion of the shoulder (at the elbow joint)

Triceps brachii (triceps)- participates in shoulder extension

Deltoid muscle of the shoulder- performs the function of flexion and extension of the shoulder, as well as abduction of the shoulder

pectoralis major - performs the function of bringing the shoulder and rotating it inward

Muscles of the lower limbs

Biceps femoris - performs the following functions: rotation of the lower leg outward, extension of the thigh, flexion of the lower leg in knee joint. With a strengthened lower leg, the torso is unbent together with the gluteus maximus muscles.

Gluteus maximus muscle - flexes and rotates the thigh outward. Straightens and fixes the body.


Quadriceps femoris - extension at the knee joint.

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calf muscles- work of the foot and stabilization of the body when walking, running, jumping.

Abdominal muscles

The external oblique muscle of the abdomen, the transverse abdominal muscle, the internal oblique muscle of the abdomen and the rectus abdominis - forming a dense muscular frame, perform the function of supporting the internal organs. Flexion of the spinal column and torso tilt to the right and left, twisting.

back muscles

The latissimus dorsi muscle functions: bringing the shoulder to the body, pronation. Also expands chest(works as an auxiliary respiratory muscles).

trapezius muscle - functions: raising or lowering the scapula, and approaching the scapula to the spinal column.

The movements of the human body are carried out due to the activity of the muscular system. It is impossible to accurately specify the number of muscles. Experts count from 400 to 600 muscles in a person. For comparison, grasshoppers have about 900 muscles, some caterpillars have up to 4000.

Muscles cover the joints and bones, and the outlines of the body depend on them. The muscular system makes up a significant part of the total body weight of a person. In newborns, the mass of all muscles is 20-25% of body weight, in the elderly about 25-30%. At 17-18 years old, the mass of all muscles reaches 30-35% in girls and 40-45% in young people. In athletes with well-developed muscles, it can be up to 50% of body weight. For the entire period of growth of the child, the mass of muscles increases by 35 times. The muscles of a child are more elastic than the muscles of an adult. During puberty (12-16 years), along with the lengthening of the tubular bones, the muscles also intensively lengthen. Teenagers at this time look long-legged and long-armed. By the age of 12-14, muscle-tendon relations are established, which are characteristic of the muscles of an adult. Muscle development continues until the age of 25-30. In an adult, 50% of the total muscle mass is accounted for lower limbs, 30% - on the upper and only 20% - on the muscles of the head and torso. For the same volume, muscle is heavier than fat and can hold 60% more water.

In the muscle, the middle part is distinguished - the abdomen, consisting of muscle tissue, and the tendon, formed by dense connective tissue. The muscular part has the ability to contract and relax. The tendon does not contract, but only transmits the action of the muscle. With the help of tendons, muscles are attached to bones, but some muscles can also be attached to various organs, such as the eyeball, some muscles of the face and neck are attached to the skin. Many muscles, surrounding the body cavities, protect the internal organs. The work of muscles, as well as the state of rest, is regulated by the nervous system. Muscles are supplied with blood through arteries. Arteries, entering the muscles, branch to capillaries, which form a dense network in bundles of muscle fibers. One square centimeter of muscle is filled with 500 capillaries.

To take a step, a person needs to use 200 muscles. In fact, this number can be a little more or less, depending on how the load is distributed during walking, and other unique anatomical features.

Superficial human skeletal muscles

Front view

  1. frontal muscle;
  2. circular muscle of the eye;
  3. temporal muscle;
  4. trapezius muscle;
  5. pectoralis major;
  6. serratus anterior;
  7. biceps brachii;
  8. long adductor muscle;
  9. rectus femoris;
  10. sartorius;
  11. tibialis anterior;
  12. calf muscle;
  13. wide median muscle;
  14. broad lateral muscle;
  15. comb muscle;
  16. iliopsoas muscle;
  17. external oblique abdominal muscle;
  18. white line of the abdomen;
  19. rectus abdominis;
  20. shoulder muscle;
  21. forearm flexors;
  22. brachioradialis muscle

Back view

  1. hand flexors;
  2. triceps muscle of the shoulder;
  3. small round muscle;
  4. large round muscle;
  5. rhomboid muscle;
  6. latissimus dorsi back;
  7. gluteus maximus;
  8. large adductor muscle;
  9. thin muscle;
  10. semitendinosus muscle;
  11. biceps femoris;
  12. deltoid;
  13. sternocleidomastoid muscle;
  14. temporalis muscle.

According to the structure, the muscles are divided into striated (voluntary) and smooth (involuntary). Striated skeletal muscle tissue consists of numerous muscle fibers, which are elongated cylindrical formations with pointed ends from 1 to 40 millimeters in length (and according to some sources, up to 120 millimeters) and a diameter of 1 mm. The name "striated" muscle tissue arose because the muscle fibers of this tissue under a microscope look like alternating light and dark stripes.

Groups of muscle fibers are combined into muscle bundles that form a muscle. The muscle is covered by an outer inextensible sheath called fascia. The fascia separates the muscle from others, prevents it from moving to the side, and protects it from unnecessary friction between each other. Fascia can cover a whole group of muscles that are functionally interconnected.

Skeletal muscles are composed of muscle fibers that can be divided into 2 groups - slow muscle fibers (tonic fibers) and fast muscle fibers (phasic fibers). Vessels and nerves pass between the bundles of muscle fibers. These muscles form the executive apparatus motor system, and also enter the structure of some internal organs (tongue, pharynx, upper esophagus and others). As a rule, contraction of skeletal muscle tissue can be carried out with the participation of consciousness.

Smooth muscle tissue is one of the tissues that make up the walls of various hollow organs and is responsible for their ability to contract. It is necessary for the movement of blood through the vessels, intestinal motility, and the removal of urine from the bladder. Smooth muscles, unlike skeletal ones, are devoid of transverse bands, they lack tendons, and their functions do not depend on our will. Unlike cross-striped, for smooth muscles slow contraction is characteristic, the ability to be in a state of contraction for a long time, expending relatively little energy and not being fatigued.

Depending on the size and shape, there are long, wide and short muscles. Long muscles are located mainly on the limbs. They have a fusiform shape, and their middle part is called the abdomen, one of the ends corresponding to the beginning of the muscle is called the head, and the other is called the tail. Tendons long muscles are in the form of a narrow band.

The broad muscles are located predominantly on the trunk and have an extended tendon called tendon stretch, or aponeurosis.

Short muscles are located between the ribs and vertebrae.

According to the direction of the fibers, longitudinal, feathery, fan-shaped and circular muscles are distinguished.

In longitudinally fibrous muscles, the fibers run longitudinally, parallel to the longitudinal axis of the muscles; they make movements of great scope, but of relatively less force; such muscles have a spindle-shaped and ribbon-like shape.

In pennate muscles, the fibers are located at an angle to the longitudinal axis on both sides of the tendon, which passes through almost the entire muscle.

Up to 25% of all muscles are concentrated on the face and neck of a person, thanks to which our facial expressions are so diverse and eloquent. French scientists found that a crying person sets in motion 43 facial muscles, while a laughing person only 40. Just talking to each other, we include up to 100 muscles of the chest, neck, tongue, jaws and lips. A kiss sets in motion 29 muscles of the face, and with some "tricks" - 34 muscles. In order to pull the trigger of a rifle, you need to use only 4 muscles.

  1. abdomen
  2. tendon
  3. tendon arch
  4. tendon bridge
  5. aponeurosis, or tendon sprain

A - fusiform muscle
B - unipennate muscle
B - bipennate muscle
G - biceps muscle
D - digastric muscle
E - rectus muscle with tendon bridges
G - wide muscle

There are many fibers in the pennate muscles, but they are short. By contracting, these muscles produce movements of great strength. If the muscle fibers are located and attached on one side of the tendon, then such a muscle is called single-feathered, resembling half a feather. When the fibers adjoin on both sides of the tendon shaft, the muscle is called bipennate.

In fan-shaped muscles, the muscle fibers run in a fan-like fashion. Starting from a wide platform, the fibers converge in a fan-like manner to a narrow attachment bridge: these muscles are distinguished by great strength (for example, the temporalis muscle).

The circular muscles are formed by fibers that go in a circle, they surround the natural external openings (eye, mouth, anus, vagina) and close them during their contraction.

By function, the muscles are divided into flexors, extensors, adductors, abductors, rotators inwards (arch supports) and outwards (pronators).

The main property of muscle tissue, on which the work of muscles is based, is contractility. When a muscle contracts, it shortens. The bones moving in the joints under the influence of muscles form levers in a mechanical sense. Since the movements are performed in 2 opposite directions (flexion-extension, adduction-abduction), at least 2 muscles located on opposite sides are necessary for the smoothness and proportionality of the movement. With each flexion, not only the flexor acts, but also the extensor, which gradually yields to the flexor and keeps it from excessive contraction. Such muscles, acting in mutually opposite directions, are called antagonists. Unlike antagonists, muscles that act in the same direction are called synergists. Depending on the nature of the movement and the functional combination of muscles, the same muscles can act either as synergists or as antagonists.

For their work, the muscles use the chemical energy released by the cells during the splitting of molecules. Muscles require 20% to 40% of all chemical energy produced to work. Coefficient useful action(efficiency) of muscles reaches 50%. For comparison, the efficiency of a car engine is only 20-30%.

The anatomy of human muscles, their structure and development, perhaps, can be called the most relevant topic that causes the maximum public interest in bodybuilding. Needless to say that it is the structure, work and functions of muscles that is the topic that personal trainer should pay Special attention. As in the presentation of other topics, we will begin the introduction to the course with a detailed study of the anatomy of the muscles, their structure, classification, work and function.

Doing healthy lifestyle life, proper nutrition and systematic physical activity contribute to the development of muscles and reduce the level of fat in the body. The structure and work of human muscles will be understood only with a consistent study of the human skeleton first and only then the muscles. And now, when we know from the article that it, among other things, performs the function of a frame for attaching muscles, it is time to study what main muscle groups form the human body, where they are located, how they look and what functions they perform.

Above you can see what the human muscle structure looks like in the photo (3D model). First consider the musculature of the body of a man with the terms applied to bodybuilding, then the musculature of the body of a woman. Looking ahead, it is worth noting that the structure of muscles in men and women fundamental differences does not have, the muscles of the body are almost completely similar.

Human muscle anatomy

Muscles called the organs of the body, which forms an elastic tissue, and the activity of which is regulated by nerve impulses. The functions of muscles are, among other things, the movement and movement in space of parts of the human body. Their full functioning directly affects the physiological activity of many processes in the body. The work of muscles is regulated by the nervous system. It promotes their interaction with the head and spinal cord, and also participates in the process of converting chemical energy into mechanical energy. The human body forms about 640 muscles (different methods for counting differentiated muscle groups determine their number from 639 to 850). Below is the structure of human muscles (diagram) using the example of a male and female body.

The structure of the muscles of a man, front view: 1 - trapezoid; 2 - serratus anterior; 3 - external oblique muscles of the abdomen; 4 - rectus abdominis; 5 - tailor muscle; 6 - comb muscle; 7 - long adductor muscle of the thigh; 8 - thin muscle; 9 - tensioner of the wide fascia; 10 - pectoralis major muscle; 11 - small pectoral muscle; 12 - front head of the shoulder; 13 - middle head of the shoulder; 14 - brachialis; 15 - pronator; 16 - long head of the biceps; 17- short head biceps; 18 - long palmar muscle; 19 - extensor muscle of the wrist; 20 - long adductor muscle of the wrist; 21 - long flexor; 22 - radial flexor of the wrist; 23 - brachioradialis muscle; 24 - lateral thigh muscle; 25 - medial thigh muscle; 26 - rectus femoris; 27 - long peroneus muscle; 28 - long extensor of the fingers; 29 - anterior tibial muscle; 30 - soleus muscle; 31 - calf muscle

The structure of the muscles of a man, rear view: 1 - back head of the shoulder; 2 - a small round muscle; 3 - large round muscle; 4 - infraspinatus muscle; 5 - rhomboid muscle; 6 - extensor muscle of the wrist; 7 - brachioradialis muscle; 8 - elbow flexor of the wrist; 9 - trapezius muscle; 10 - straight spinous muscle; 11 - the latissimus dorsi; 12 - thoracolumbar fascia; 13 - biceps of the thigh; 14 - a large adductor muscle of the thigh; 15 - semitendinosus muscle; 16 - thin muscle; 17 - semimembranous muscle; 18 - calf muscle; 19 - soleus muscle; 20 - long peroneal muscle; 21 - abductor muscle of the big toe; 22 - long head of the triceps; 23 - lateral head of the triceps; 24- medial head triceps; 25 - external oblique muscles of the abdomen; 26 - gluteus medius; 27 - gluteus maximus

The structure of the muscles of a woman, front view: 1 - scapular hyoid muscle; 2 - sternohyoid muscle; 3 - sternocleidomastoid muscle; 4 - trapezius muscle; 5 - pectoralis minor muscle (not visible); 6 - pectoralis major muscle; 7 - dentate muscle; 8 - rectus abdominis; 9 - external oblique muscle of the abdomen; 10 - comb muscle; 11 - tailor muscle; 12 - long adductor muscle of the thigh; 13 - tensioner of the wide fascia; 14 - thin muscle of the thigh; 15 - rectus femoris; 16 - intermediate broad muscle of the thigh (not visible); 17 - lateral wide muscle of the thigh; 18 - wide medial muscle of the thigh; 19 - calf muscle; 20 - anterior tibial muscle; 21 - long extensor of the toes; 22 - long tibial muscle; 23 - soleus muscle; 24 - front bundle of deltas; 25 - middle beam of deltas; 26 - brachialis shoulder muscle; 27 - a long bunch of biceps; 28 - a short bundle of biceps; 29 - brachioradialis muscle; 30 - radial extensor of the wrist; 31 - round pronator; 32 - radial flexor of the wrist; 33 - long palmar muscle; 34 - elbow flexor of the wrist

The structure of the muscles of a woman, rear view: 1 - rear bundle of deltas; 2 - a long bundle of triceps; 3 - lateral bundle of triceps; 4 - medial bundle of triceps; 5 - ulnar extensor of the wrist; 6 - external oblique muscle of the abdomen; 7 - extensor of the fingers; 8 - wide fascia; 9 - biceps of the thigh; 10 - semitendinosus muscle; 11 - thin muscle of the thigh; 12 - semimembranosus muscle; 13 - calf muscle; 14 - soleus muscle; 15 - short peroneal muscle; 16 - long flexor thumb; 17 - a small round muscle; 18 - large round muscle; 19 - infraspinatus muscle; 20 - trapezius muscle; 21 - rhomboid muscle; 22 - the latissimus dorsi; 23 - extensors of the spine; 24 - thoracolumbar fascia; 25 - small gluteal muscle; 26 - gluteus maximus

Muscles are quite varied in shape. Muscles that share a common tendon but have two or more heads are called biceps (biceps), triceps (triceps), or quadriceps (quadriceps). The functions of the muscles are also quite diverse, these are flexors, extensors, abductors, adductors, rotators (inward and outward), raising, lowering, straightening and others.

Types of muscle tissue

The characteristic features of the structure make it possible to classify human muscles into three types: skeletal, smooth and cardiac.

Types of human muscle tissue: I - skeletal muscles; II - smooth muscles; III- cardiac muscle

  • Skeletal muscles. The contraction of this type of muscle is completely controlled by the person. Combined with the human skeleton, they form the musculoskeletal system. This type of muscle is called skeletal precisely because of their attachment to the bones of the skeleton.
  • Smooth muscles. This type of tissue is present in the cells of internal organs, skin and blood vessels. The structure of human smooth muscles implies their presence for the most part in the walls of hollow internal organs, such as the esophagus or bladder. They also play an important role in processes that are not controlled by our consciousness, for example, in intestinal motility.
  • Heart muscle (myocardium). The work of this muscle is controlled by the autonomic nervous system. Its contractions are not controlled by human consciousness.

Since the contraction of smooth and cardiac muscle tissue is not controlled by human consciousness, we will focus in this article on skeletal muscles and their detailed description.

Muscle structure

muscle fiber is a structural element of muscles. Separately, each of them is not only a cellular, but also a physiological unit that is able to contract. The muscle fiber has the appearance of a multinucleated cell, the diameter of the fiber is in the range from 10 to 100 microns. This multinucleated cell is located in a shell called the sarcolemma, which in turn is filled with sarcoplasm, and already in the sarcoplasm are myofibrils.

Myofibril is a filamentous formation, which consists of sarcomeres. The thickness of myofibrils is usually less than 1 µm. Given the number of myofibrils, they usually distinguish between white (they are also fast) and red (they are also slow) muscle fibers. White fibers contain more myofibrils, but less sarcoplasm. It is for this reason that they shrink faster. Red fibers contain a lot of myoglobin, which is why they got their name.

The internal structure of the human muscle: 1 - bone; 2 - tendon; 3 - muscular fascia; 4 - skeletal muscle; 5 - fibrous sheath of skeletal muscle; 6 - connective tissue sheath; 7 - arteries, veins, nerves; 8 - beam; 9 - connective tissue; 10 - muscle fiber; 11 - myofibril

Muscle work is characterized by the fact that the ability to contract faster and stronger is characteristic of white fibers. They can develop force and contraction speed 3-5 times faster than slow fibers. Physical activity of the anaerobic type (work with weights) is performed mainly by fast muscle fibers. Long-term aerobic physical activity (running, swimming, cycling) is performed mainly by slow muscle fibers.

Slow fibers are more resistant to fatigue, while fast fibers are more resistant to prolonged physical activity not adapted. As for the ratio of fast and slow muscle fibers in human muscles, their number is approximately the same. In most of both sexes, about 45-50% of the muscles of the limbs are slow muscle fibers. No matter how significant the sex differences in the ratio various types there are no muscle fibers in men and women. Their ratio is formed at the beginning of the human life cycle, in other words, it is genetically programmed and practically does not change until old age.

Sarcomeres (constituent components of myofibrils) are formed by thick myosin filaments and thin actin filaments. Let's dwell on them in more detail.

actin- a protein that is a structural element of the cytoskeleton of cells and has the ability to contract. Consists of 375 amino acid residues, and makes up about 15% of muscle protein.

Myosin – main component myofibrils - contractile muscle fibers, where its content can be about 65%. The molecules are formed by two polypeptide chains, each of which contains about 2000 amino acids. Each of these chains has a so-called head at the end, which includes two small chains consisting of 150-190 amino acids.

Actomyosin- a complex of proteins formed from actin and myosin.

FACT. For the most part, muscles are made up of water, proteins and other components: glycogen, lipids, nitrogenous substances, salts, etc. The water content ranges from 72-80% of the total muscle mass. Skeletal muscle consists of a large number of fibers, and characteristically, the more of them, the stronger the muscle.

Muscle classification

The human muscular system is characterized by a variety of muscle shapes, which in turn are divided into simple and complex. Simple: spindle-shaped, straight, long, short, wide. The complex muscles include the multi-headed muscles. As we have already said, if the muscles have a common tendon, and there are two or more heads, then they are called two-headed (biceps), three-headed (triceps) or quadriceps (quadriceps), as well as multi-tendon and digastric muscles. Complex muscles include the following types of muscles with a specific geometric shape: square, deltoid, soleus, pyramidal, round, serrated, triangular, rhomboid, soleus.

Main functions muscles are flexion, extension, abduction, adduction, supination, pronation, raising, lowering, straightening and more. The term supination refers to outward rotation, and the term pronation refers to inward rotation.

In the direction of the fibers muscles are divided into: straight, transverse, circular, oblique, single-pinnate, double-pinnate, multi-pinnate, semitendinous and semimembranosus.

In relation to the joints, taking into account the number of joints through which they are thrown: single-joint, two-joint and multi-joint.

Muscle work

In the process of contraction, the actin filaments penetrate deep into the spaces between the myosin filaments, and the length of both structures does not change, but only the total length of the actomyosin complex is reduced - this method of muscle contraction is called sliding. The sliding of actin filaments along myosin filaments requires energy, and the energy necessary for muscle contraction is released as a result of the interaction of actomyosin with ATP (adenosine triphosphate). In addition to ATP, water, as well as calcium and magnesium ions, play an important role in muscle contraction.

As already mentioned, the work of the muscles is completely controlled by the nervous system. This suggests that their work (contraction and relaxation) can be controlled consciously. For the normal and full functioning of the body and its movement in space, the muscles work in groups. Most of the muscle groups of the human body work in pairs, and perform opposite functions. It looks like when the “agonist” muscle contracts, the “antagonist” muscle stretches. The same is true and vice versa.

  • Agonist- a muscle that performs a specific movement.
  • Antagonist- a muscle that performs the opposite movement.

Muscles have the following properties: elasticity, stretching, contraction. Elasticity and stretching give the muscles the ability to change in size and return to their original state, the third quality makes it possible to create force at its ends and lead to shortening.

Nerve stimulation can cause the following types muscle contraction: concentric, eccentric and isometric. Concentric contraction occurs in the process of overcoming the load when performing a given movement (lifting up during pull-ups on the crossbar). Eccentric contraction occurs in the process of slowing down movements in the joints (lowering down during pull-ups on the crossbar). Isometric contraction occurs at the moment when the force created by the muscles is equal to the load exerted on them (keeping the body hanging on the bar).

Muscle Functions

Knowing the name and location of this or that muscle or muscle group, we can proceed to the study of the block - the function of human muscles. Below in the table we will look at the most basic muscles that train in the gym. As a rule, six main muscle groups are trained: chest, back, legs, shoulders, arms and abs.

FACT. The biggest and strongest muscle group in the human body it is the legs. The most big muscle- berry. The strongest is the calf, it can hold weight up to 150 kg.

Conclusion

In this article, we examined such a complex and voluminous topic as the structure and functions of human muscles. Speaking of muscles, of course, we also mean muscle fibers, and the involvement of muscle fibers in the work involves interaction with them. nervous system, since the execution of muscle activity is preceded by the innervation of motor neurons. It is for this reason that in our next article we will move on to consider the structure and functions of the nervous system.



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