What are flat bones definition. Flat bones. Age-related changes in bones

The human skeletal system consists of an average of 206 bones, most of which are symmetrical; flexible cartilage that forms the structure of the ears, nose and parts of the ribs, as well as covering the articular surfaces of bones and joints, and dense ligaments that hold the bones in place at the joints. The skeletal system (skeleton) makes up 20% of the total body weight.

Types of bones

According to their shape, bones are divided into 4 main types: long, short, flat and mixed. The shape of a bone also indicates its mechanical function.

Long bones - the bones of the limbs (except the bones of the wrist, ankle and patella) are longer than they are wide. Each has a diaphysis (body) and two epiphyses (ends), which are usually wider than the body of the bone. These bones act as lifting mechanisms that cause the body to move when muscles contract. Some bones, especially the bones of the lower extremities, play an important role in maintaining body weight.

Short bones - the carpal and tarsal bones have an irregular cubic shape. They act as a kind of connecting bridge in the wrist and ankle area. Movement between these bones is limited; their main purpose is to maintain stability of the hand and foot as a whole.

Flat bones - sternum, ribs, scapula and skull roof bones. These bones are thin, flattened and slightly curved. The ribs and skull perform mainly protective functions (protection of internal organs), and the shoulder blades serve as the attachment surface for a large number of muscles.

Mixed bones - bones of the facial skull, spine, pelvis and hip. The vertical position of the body is maintained by an S-shaped flexible spine that supports the head. The pelvic bones support the balance of the upper body.

Cartilage tissue

Cartilage is a special connective tissue; cover the articular surfaces, form the structure of the ears, nose and parts of the ribs. Cartilage also forms elastic pads between the vertebrae (intervertebral discs). This elastic jelly-like fabric is highly durable, resistant to compression and abrasion. Articular cartilage tissue forms polished surfaces covered with a special synovial fluid (synovium), which has a low coefficient of friction.

The vertical position of the body is supported by an S-shaped flexible spine, which also supports the head. The pelvic bones support the balance of the upper torso, and the strong bones of the legs bear almost the entire weight of the body.

The bones of the skeletal system can be roughly divided into two categories: the axial skeleton (skull, spinal column, chest bones), accessory skeleton (bones of the upper and lower extremities), including the pelvic girdle and the shoulder girdle, which connects the limbs to the axial skeleton.

Bone structure

Bones are formed by living tissue; perform not only a supporting function, but also serve as a depot and source of calcium and other minerals. Red bone marrow produces blood cells. Bones are composed of cells surrounded by a matrix. This matrix consists of 35% protein, mainly collagen, which provides their strength and flexibility, and 65% mineral salts, mainly calcium and phosphorus, which increase strength. This combination makes bone 5 times stronger than steel. The cells that form bones include osteocytes (which build the matrix), osteoblasts (build bone tissue) and osteoclasts (destroy bone tissue). Working in dynamic equilibrium, osteoblasts and osteoclasts constantly renew bone tissue in accordance with the load placed on them by the muscles, and also accumulate or release calcium depending on the body's needs.
Bones are made up of two types of bone tissue. The compact tissue that forms the outer surface of the bone is most resistant to stress. It is formed by parallel cylinders - osteons. These are the structural units of bone from which the matrix is formed. Blood vessels pass through the central canal of each osteon. In small voids on the outer part of the osteons there are isolated osteocytes. Spongy bone tissue in its structure resembles a honeycomb filled with a jelly-like substance - bone marrow. Yellow bone marrow stores fat, and red bone marrow produces blood cells. Most bones are covered by a thin membrane called the periosteum, or periosteum.

Bones are a source of minerals

Bones perform not only mechanical functions - support, protection and movement. They also play an important role in the accumulation and maintenance of calcium and hematopoiesis.
Calcium is one of twenty minerals, in addition to magnesium and zinc, that are supplied to the body through food and play an important role in ensuring the normal functioning of the body. 99% of the calcium in the human body is found in the bones. Thanks to calcium, human bones and teeth remain hard. This mineral is necessary for normal muscle contraction, transmission of nerve impulses and blood clotting. The optimal level of calcium in the blood is maintained by two hormones (The thyroid gland secretes two iodine-containing hormones: triiodothyronine and thyroxine, and calcitonin, which does not contain iodine), which work in opposite directions - one releases bone calcium into the blood, and the other stimulates the release of calcium from the blood and accumulation it in bone tissue.
Blood cells, which include red blood cells, white blood cells and platelets, are produced in the red bone marrow. It is found in the bones of the skull, spine, clavicles, sternum, ribs, shoulder blades, pelvis and the upper epiphyses of the femur and humerus.

Bone connections

In the skeleton, a joint is formed at the junction of two or more bones. Joints allow bones to move. In addition, joints maintain the strength of the body because bones at joints are held firmly together by strong connective tissue fibers called ligaments. Ligaments are both rigid and flexible.
There are three types of connections. Fibrous joints, such as the cranial sutures, prevent movement. Partially movable cartilaginous joints, such as intervertebral discs, allow limited movement. Synovial joints (joints) have great mobility.
Most joints are synovial. Inside the synovial joint is an oily fluid (synovium) that coats the joint and lubricates the ends of the bones. Depending on the type of synovial joints (joints), the range of movements they provide varies.

A ball-and-socket joint, such as the shoulder or hip, allows for movement in many directions.

A trochlear joint, such as the elbow, knee or ankle, like door hinges, allows movement in only one plane.

A cylindrical joint, such as between the atlas and axial vertebrae, allows the bones to rotate or rotate relative to each other.

Flat, or inactive, joints between the bones of the wrist and tarsus provide sliding movements of a small span of the two bones relative to each other.

Ellipsoidal, or condylar, joints, such as those between the radius and carpal bones, allow movement from side to side, as well as forward and backward.

The saddle joint at the base of the thumb of the hand ensures its movement in two planes.

Intracartilaginous ossification

Ossification, or ossification, is the process of bone formation in the prenatal period, infancy, childhood and adolescence. Most bones (except for the skull and clavicles) are formed as a result of the process of intracartilaginous (encondral) ossification. Initially, the skeleton is formed by soft cartilage, which is gradually replaced by bone tissue - compact and spongy as a result of the activity of osteoblasts. During childhood, bones become longer and wider, allowing the body to grow. In adolescence, the growth process slows down and ossification practically ends.

Bone regeneration and repair

Throughout life, the shape and size of bones do not remain constant. The shape of bones changes as a result of mechanical forces caused by muscle tension and gravity. Self-healing of bones after fractures or cracks also occurs due to the regeneration process.

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Human skeleton: functions, departments

The skeleton is a collection of bones, cartilage that belongs to them, and ligaments connecting the bones.

There are more than 200 bones in the human body. The skeleton weighs 7-10 kg, which is 1/8 the weight of a person.

The following are distinguished in the human skeleton: departments:

head skeleton(scull), torso skeleton- axial skeleton;
upper limb belt, lower limb belt- accessory skeleton.

Human skeleton front

Skeletal functions:

Mechanical functions:

support and attachment of muscles (the skeleton supports all other organs, gives the body a certain shape and position in space);
protection - the formation of cavities (the skull protects the brain, the chest protects the heart and lungs, and the pelvis protects the bladder, rectum and other organs);
movement - a movable connection of bones (the skeleton together with the muscles makes up the motor apparatus, the bones in this apparatus play a passive role - they are levers that move as a result of muscle contraction).

Biological functions:

mineral metabolism;
hematopoiesis;
blood deposition.

Classification of bones, features of their structure. Bone as an organ

Bone- a structural and functional unit of the skeleton and an independent organ. Each bone occupies a precise position in the body, has a certain shape and structure, and performs its characteristic function. All types of tissues take part in bone formation. Of course, the main place is occupied by bone tissue. Cartilage covers only the articular surfaces of the bone, the outside of the bone is covered with periosteum, and the bone marrow is located inside. Bone contains fatty tissue, blood and lymphatic vessels, and nerves. Bone tissue has high mechanical properties; its strength can be compared to the strength of metal. Relative bone density is about 2.0. Living bone contains 50% water, 12.5% organic protein substances (ossein and osseomucoid), 21.8% inorganic mineral substances (mainly calcium phosphate) and 15.7% fat.

In dried bone, 2/3 are inorganic substances, which determine the hardness of the bone, and 1/3 are organic substances, which determine its elasticity. The content of mineral (inorganic) substances in bone gradually increases with age, causing the bones of older and older people to become more fragile. For this reason, even minor injuries in old people are accompanied by bone fractures. The flexibility and elasticity of bones in children depend on the relatively higher content of organic substances in them.

Osteoporosis- a disease associated with damage (thinning) of bone tissue, leading to fractures and bone deformities. The reason is failure to absorb calcium.

The structural functional unit of bone is osteon. Typically, an osteon consists of 5-20 bone plates. Osteon diameter is 0.3 - 0.4 mm.

If the bone plates fit tightly to each other, then a dense (compact) bone substance is obtained. If the bone crossbars are loosely located, then spongy bone substance is formed, which contains red bone marrow.

The outside of the bone is covered with periosteum. It contains blood vessels and nerves.

Due to the periosteum, the bone grows in thickness. Due to the epiphyses, the bone grows in length.

Inside the bone there is a cavity filled with yellow bone marrow.

Internal structure of bone

Classification of bones according to form:

Tubular bones- have a general structural plan, they distinguish between a body (diaphysis) and two ends (epiphyses); cylindrical or triangular shape; length prevails over width; On the outside, the tubular bone is covered with a connective tissue layer (periosteum):

long (femoral, shoulder);
short (phalanxes of fingers).

Spongy bones- formed predominantly by spongy tissue surrounded by a thin layer of solid matter; combine strength and compactness with limited mobility; The width of the spongy bones is approximately equal to their length:

long (sternum);
short (vertebrae, sacrum)
sesamoid bones - located in the thickness of the tendons and usually lie on the surface of other bones (patella).

Flat Bones- formed by two well-developed compact outer plates, between which there is a spongy substance:

skull bones (roof of the skull);
flat (pelvic bone, shoulder blades, bones of the girdles of the upper and lower extremities).

Mixed dice- have a complex shape and consist of parts that differ in function, form and origin; due to their complex structure, mixed bones cannot be classified as other types of bones: tubular, spongy, flat (the thoracic vertebra has a body, an arch and processes; the bones of the base of the skull consist of a body and scales).

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Lecture: Classification of bones by shape and internal structure. Classification of bones.

The skeleton is divided into the following parts: the skeleton of the body (vertebrae, ribs, sternum), the skeleton of the head (bones of the skull and face), the bones of the limb girdles - upper (scapula, clavicle) and lower (pelvic) and the bones of the free limbs - upper (shoulder, bones forearm and hand) and lower (thigh, leg bones and foot).

The number of individual bones that make up the skeleton of an adult is more than 200, of which 36 - 40 are located along the midline of the body and are unpaired, the rest are paired bones.
Based on their external shape, bones are distinguished into long, short, flat and mixed.

However, such a division, established back in the time of Galen, based only on one characteristic (external form) turns out to be one-sided and serves as an example of the formalism of the old descriptive anatomy, as a result of which bones that are completely heterogeneous in their structure, function and origin fall into one group.

Thus, the group of flat bones includes the parietal bone, which is a typical integumentary bone that ossifies endesmally, and the scapula, which serves for support and movement, ossifies on the basis of cartilage and is built from ordinary spongy substance.
Pathological processes also occur completely differently in the phalanges and bones of the wrist, although both belong to short bones, or in the femur and rib, which are included in the same group of long bones.

Therefore, it is more correct to distinguish bones on the basis of 3 principles on which any anatomical classification should be built: form (structure), function and development.
From this point of view, we can outline the following bone classification(M. G. Gain):
I. Tubular bones. They are built of a spongy and compact substance that forms a tube with a medullary cavity; perform all 3 functions of the skeleton (support, protection and movement).

Of these, the long tubular bones (the shoulder and bones of the forearm, the femur and the bones of the leg) are struts and long levers of movement and, in addition to the diaphysis, have endochondral foci of ossification in both epiphyses (biepiphyseal bones); short tubular bones (carpal bones, metatarsals, phalanges) represent short levers of movement; Of the epiphyses, the endochondral focus of ossification is present only in one (true) epiphysis (monoepiphyseal bones).
P. Spongy bones. Constructed primarily of a spongy substance covered with a thin layer of compact.

Among them, there are long spongy bones (ribs and sternum) and short ones (vertebrae, carpal bones, tarsus). Spongy bones include sesamoid bones, i.e., similar to the sesamoid grains of the sesame plant, which is where their name comes from (patella, pisiform bone, sesamoid bones of the fingers and toes); their function is auxiliary devices for muscle work; development is endochondral in the thickness of the tendons. Sesamoid bones are located near the joints, participating in their formation and facilitating movements in them, but are not directly connected to the bones of the skeleton.
III.

Flat bones:
a) the flat bones of the skull (frontal and parietal) perform a predominantly protective function. They are built from 2 thin plates of a compact substance, between which there is diploe, a spongy substance containing channels for veins. These bones develop on the basis of connective tissue (integumentary bones);
b) the flat bones of the girdles (scapula, pelvic bones) perform the functions of support and protection, and are built mainly from spongy substance; develop on the basis of cartilage tissue.

Mixed bones (bones of the base of the skull). These include bones that merge from several parts that have different functions, structure and development. Mixed bones also include the clavicle, which develops partly endesmally and partly endochondrally.

7) structure of bone substance.
According to its microscopic structure, bone substance is a special type of connective tissue, bone tissue, the characteristic features of which are: solid fibrous intercellular substance impregnated with mineral salts and stellate cells equipped with numerous processes.

The basis of the bone is made up of collagen fibers with a substance that solders them, which are saturated with mineral salts and folded into plates consisting of layers of longitudinal and transverse fibers; In addition, the bone substance also contains elastic fibers.

These plates in dense bone matter are partly located in concentric layers around long branching channels passing through the bone substance, partly lie between these systems, partly embrace entire groups of them or stretch along the surface of the bone. The Haversian canal, in combination with the surrounding concentric bone plates, is considered a structural unit of compact bone substance - an osteon.

Parallel to the surface of these plates, they contain layers of small star-shaped voids that continue into numerous thin tubules - these are the so-called “bone corpuscles”, which contain bone cells that give off processes into the tubules. The tubules of the bone corpuscles are connected to each other and to the cavity of the Haversian canals, internal cavities and periosteum, and thus the entire bone tissue is penetrated by a continuous system of cavities and tubules filled with cells and their processes, through which the nutrients necessary for bone life penetrate.

Thin blood vessels pass through the Haversian canals; The wall of the Haversian canal and the outer surface of the blood vessels are covered with a thin layer of endothelium, and the spaces between them serve as the lymphatic pathways of the bone.

Cancellous bone does not have Haversian canals.

9) methods for studying the skeletal system.
Skeletal bones can be studied in a living person using x-rays. The presence of calcium salts in the bones makes the bones less “transparent” to X-rays than the surrounding soft tissue. Due to the unequal structure of the bones, the presence in them of a more or less thick layer of compact cortical substance, and inside of it the spongy substance, bones can be seen and distinguished on radiographs.
X-ray (x-ray) examination is based on the property of x-rays to penetrate body tissue to varying degrees.

The degree of absorption of X-ray radiation depends on the thickness, density and physico-chemical composition of human organs and tissues, therefore denser organs and tissues (bones, heart, liver, large vessels) are visualized on the screen (X-ray fluorescent or television) as shadows, and lung tissue due to the large amount of air, it is represented by an area of \u200b\u200bbright glow.

The following main radiological research methods are distinguished.

1. X-ray (Greek)

skopeo - consider, observe) - x-ray examination in real time. A dynamic image appears on the screen, allowing you to study the motor function of organs (for example, vascular pulsation, gastrointestinal motility); the structure of the organs is also visible.

2. Radiography (Greek) grapho- write) - an x-ray examination with registration of a still image on a special x-ray film or photographic paper.

With digital radiography, the image is recorded in the computer's memory. Five types of radiography are used.

Full-format radiography.

Fluorography (small-format radiography) - radiography with a reduced size of the image obtained on a fluorescent screen (lat.

fluor - current, stream); it is used for preventive examinations of the respiratory system.

Survey radiography is an image of an entire anatomical area.

Sight radiography is an image of a limited area of the organ being studied.

Wilhelm Conrad Roentgen (1845-1923) - German experimental physicist, founder of radiology, discovered X-rays (X-rays) in 1895.

Serial radiography is the sequential acquisition of several radiographs to study the dynamics of the process being studied.

Tomography (Greek) tomos - segment, layer, layer) is a layer-by-layer visualization method that provides an image of a layer of tissue of a given thickness using an X-ray tube and a film cassette (X-ray tomography) or by connecting special counting cameras from which electrical signals are sent to a computer (computed tomography).

Contrast fluoroscopy (or radiography) is an X-ray research method based on the introduction into hollow organs (bronchi, stomach, renal pelvis and ureters, etc.) or vessels (angiography) of special (radiopaque) substances that delay X-ray radiation, resulting in a clear image of the organs being studied is obtained on the screen (photo film).

10) the structure of bone as an organ, typical bone formations.
bone, os, ossis, As an organ of a living organism, it consists of several tissues, the most important of which is bone.

awn(os) is an organ that is a component of the system of organs of support and movement, having a typical shape and structure, characteristic architecture of blood vessels and nerves, built primarily from bone tissue, covered externally with periosteum (periosteum) and containing bone marrow (medulla osseum) inside.

Each bone has a specific shape, size and position in the human body.

The formation of bones is significantly influenced by the conditions in which bones develop and the functional loads that bones experience during the life of the body. Each bone is characterized by a certain number of sources of blood supply (arteries), the presence of certain places of their localization and the characteristic intraorgan architecture of blood vessels.

These features also apply to the nerves innervating this bone.

Each bone consists of several tissues that are in certain proportions, but, of course, the main one is lamellar bone tissue. Let us consider its structure using the example of the diaphysis of a long tubular bone.

The main part of the diaphysis of the tubular bone, located between the outer and inner surrounding plates, consists of osteons and intercalated plates (residual osteons).

The osteon, or Haversian system, is a structural and functional unit of bone. Osteons can be viewed in thin sections or histological preparations.

Internal bone structure: 1 - bone tissue; 2 - osteon (reconstruction); 3 - longitudinal section of osteon

The osteon is represented by concentrically located bone plates (Haversian), which in the form of cylinders of different diameters, nested within each other, surround the Haversian canal.

The latter contains blood vessels and nerves. Osteons are mostly located parallel to the length of the bone, repeatedly anastomosing with each other.

The number of osteons is individual for each bone; in the femur it is 1.8 per 1 mm2. In this case, the Haversian canal accounts for 0.2-0.3 mm2. Between the osteons there are intercalary, or intermediate, plates that run in all directions.

Intercalated plates are the remaining parts of old osteons that have undergone destruction. The processes of new formation and destruction of osteons constantly occur in bones.

Outside bone surrounded by several layers of general, or common, plates, which are located directly under the periosteum (periosteum).

Perforating channels (Volkmann's) pass through them, which contain blood vessels of the same name. At the border with the medullary cavity in the tubular bones there is a layer of internal surrounding plates. They are penetrated by numerous channels expanding into cells. The medullary cavity is lined with endosteum, which is a thin connective tissue layer containing flattened inactive osteogenic cells.

In bone plates shaped like cylinders, ossein fibrils are closely and parallel to each other.

Osteocytes are located between the concentrically lying bone plates of osteons. The processes of bone cells, spreading along the tubules, pass towards the processes of neighboring osteocytes, enter into intercellular connections, forming a spatially oriented lacunar-tubular system involved in metabolic processes.

The osteon contains up to 20 or more concentric bone plates.

The osteon canal contains 1-2 microvasculature vessels, unmyelinated nerve fibers, lymphatic capillaries, accompanied by layers of loose connective tissue containing osteogenic elements, including perivascular cells and osteoblasts.

The osteon channels are connected to each other, to the periosteum and the medullary cavity due to perforating channels, which contributes to the anastomosis of the bone vessels as a whole.

The outside of the bone is covered with periosteum, formed by fibrous connective tissue. It distinguishes between the outer (fibrous) layer and the inner (cellular).

Cambial precursor cells (preosteoblasts) are localized in the latter. The main functions of the periosteum are protective, trophic (due to the blood vessels passing here) and participation in regeneration (due to the presence of cambial cells).

The periosteum covers the outside of the bone, with the exception of those places where articular cartilage is located and muscle tendons or ligaments are attached (on the articular surfaces, tuberosities and tuberosities). The periosteum delimits the bone from surrounding tissues.

It is a thin, durable film consisting of dense connective tissue in which blood and lymphatic vessels and nerves are located. The latter penetrate from the periosteum into the substance of the bone.

External structure of the humerus: 1 - proximal (upper) epiphysis; 2 - diaphysis (body); 3 - distal (lower) epiphysis; 4 - periosteum

The periosteum plays a large role in the development (growth in thickness) and nutrition of the bone.

Its inner osteogenic layer is the site of bone tissue formation. The periosteum is richly innervated and therefore highly sensitive. A bone deprived of periosteum becomes nonviable and dies.

During surgical interventions on bones for fractures, the periosteum must be preserved.

Almost all bones (with the exception of most skull bones) have articular surfaces for articulation with other bones.

The articular surfaces are covered not by periosteum, but by articular cartilage (cartilage articularis). Articular cartilage is more often hyaline in structure and less often fibrous.

Inside most bones, in the cells between the plates of the spongy substance or in the bone marrow cavity (cavitas medullaris), there is bone marrow.

It comes in red and yellow. In fetuses and newborns, the bones contain only red (blood-forming) bone marrow. It is a homogeneous red mass, rich in blood vessels, blood cells and reticular tissue.

Red bone marrow also contains bone cells and osteocytes. The total amount of red bone marrow is about 1500 cm3.

In an adult, the bone marrow is partially replaced by yellow marrow, which is mainly represented by fat cells. Only bone marrow located within the medullary cavity can be replaced. It should be noted that the inside of the bone marrow cavity is lined with a special membrane called endosteum.

1. Long tubular (os thighs, shins, shoulders, forearms).

2. Short tubular (os metacarpus, metatarsus).

3. Short spongy (vertebral bodies).

4. Spongy (sternum).

5. Flat (shoulder blade).

6. Mixed (os skull base, vertebrae - spongy bodies, and flat processes).

7. Pneumatic (upper jaw, ethmoid, sphenoid).

Bone structure .

Bone of a living person is a complex organ, occupies a certain position in the body, has its own shape and structure, and performs its characteristic function.

Bone consists of tissues:

Bone tissue (occupies the main place).

2. Cartilaginous (covers only the articular surfaces of the bone).

3. Fat (yellow bone marrow).

Reticular (red bone marrow)

The outside of the bone is covered with periosteum.

Periosteum(or periosteum) is a thin two-layer connective tissue plate.

The inner layer consists of loose connective tissue, it contains osteoblasts.

They are involved in the growth of bone thickness and restoration of its integrity after fractures.

The outer layer is made of dense fibrous fibers. The periosteum is rich in blood vessels and nerves, which penetrate deep into the bone through thin bone canals, supplying blood and innervating it.

Located inside the bone Bone marrow.

Bone marrow there are two types:

Red bone marrow– an important organ of hematopoiesis and bone formation.

Rich in blood vessels with blood elements. It is formed by reticular tissue, which contains hematopoietic elements (stem cells), osteoclasts (destroyers), and osteoblasts.

During the prenatal period and in newborns, all bones contain red bone marrow.

In an adult, it is contained only in the cells of the spongy substance of flat bones (sternum, skull bones, ilium), in spongy (short bones), and epiphyses of long bones.

As they mature, blood cells enter the bloodstream and are distributed throughout the body.

Yellow bone marrow is represented mainly by fat cells and degenerated cells of reticular tissue.

Lipocytes give bone its yellow color. Yellow bone marrow is located in the cavity of the diaphysis of long bones.

Bone plate systems are formed from bone tissue.

If the bone plates fit tightly to each other, then it turns out dense or compact bone substance.

If the bone crossbars are located loosely, forming cells, then spongy bone substance, which consists of a network of thin anastomosed bone elements - trabeculae.

The bone crossbars are not located randomly, but strictly regularly along the lines of compression and tension forces.

Osteon is a structural unit of bone.

Osteons consist of 2-20 cylindrical plates, inserted one into the other, inside which runs the (Haversian) canal.

A lymphatic vessel, artery and vein pass through it, which branch into capillaries and approach the lacunae of the Haversian system. They ensure the influx and outflow of nutrients, metabolic products, CO2 and O2.

On the outer and inner surfaces of the bone, bone plates do not form concentric cylinders, but are located around them.

These areas are pierced by Volkmann's canals, through which pass blood vessels that connect with the vessels of the Haversian canals.

Living bone contains 50% water, 12.5% organic protein substances (ossein and osseomucoid), 21.8% inorganic mineral substances (mainly calcium phosphate) and 15.7% fat.

Organic substances cause elasticity bones, and inorganic ones - hardness.

Tubular bones are made up of body (diaphysis) And two ends (epiphyses). Epiphyses are proximal and distal.

On the border between the diaphysis and the epiphysis is located metaepiphyseal cartilage, due to which the bone grows in length.

Complete replacement of this cartilage with bone occurs in women by 18-20 years, and in men by 23-25 years. From this time on, the growth of the skeleton, and therefore the person, stops.

The epiphyses are built from spongy bone substance, the cells of which contain red bone marrow. The outside of the epiphyses is covered articular hyaline cartilage.

The diaphysis consists of a compact bone substance.

Inside the diaphysis there is medullary cavity, it contains yellow bone marrow. The outside of the diaphysis is covered periosteum. The periosteum of the diaphysis gradually passes into the perichondrium of the epiphyses.

Spongy bone consists of 2 compact bone plates, between which there is a layer of spongy substance.

Red bone marrow is located in spongy cells.

Bones united into a skeleton (skeletos) - from Greek, meaning dried.

3.
Types of bones and their connections

The human skeleton contains more than 200 bones.
All bones of the skeleton, according to their structure, origin and functions, are divided into four types: Tubular (humerus, ulna, radius, femur, tibia, fibula) - these are long tube-shaped bones that have a canal inside with yellow bone marrow.

Provide rapid, varied movements of the limbs.
Spongy (long: ribs, sternum; short: carpal bones, tarsus) - bones predominantly consisting of spongy substance, covered with a thin layer of compact substance. Contains red bone marrow, which provides hematopoietic function.
Flat (shoulder blades, skull bones) - bones whose width prevails over thickness to protect internal organs.

They consist of plates of compact substance and a thin layer of spongy substance.
Mixed - consist of several parts with different structures, origins and functions (the vertebral body is spongy bone, and its processes are flat bones).

Various types of bone connections provide the functions of parts of the skeleton.
A fixed (continuous) connection is a fusion or fastening of connective tissue to perform a protective function (connecting the bones of the roof of the skull to protect the brain).
A semi-movable connection through elastic cartilaginous pads forms bones that perform both protective and motor functions (connections of the vertebrae with intervertebral cartilaginous discs, ribs with the sternum and thoracic vertebrae)
The bones have a movable (discontinuous) connection thanks to the joints, which ensures the movement of the body.

Different joints provide different directions of movement.

articular surfaces of articulating bones; articular (synovial) fluid.
The articular surfaces correspond to each other in shape and are covered with hyaline cartilage.

The joint capsule forms a sealed cavity with synovial fluid. This promotes gliding and protects the bone from abrasion.
Illustrations:
http://www.ebio.ru/che04.html

What does arthrology study? The section of anatomy devoted to the study of the connection of bones is called arthrology (from the Greek arthron - “joint”). Bone joints unite the bones of the skeleton into a single whole, holding them close to each other and providing them with greater or lesser mobility. Bone joints have different structures and have physical properties such as strength, elasticity and mobility, which are associated with the function they perform.

CLASSIFICATION OF BONE JOINTS. Although bone joints vary greatly in structure and function, they can be divided into three types:
1.

Continuous joints (synarthroses) are characterized by the fact that the bones are connected by a continuous layer of connective tissue (dense connective tissue, cartilage or bone). There is no gap or cavity between the connecting surfaces.

2. Semi-continuous joints (hemiarthrosis), or symphyses, are a transitional form from continuous to discontinuous joints.

They are characterized by the presence in the cartilaginous layer located between the connecting surfaces of a small gap filled with liquid.

Such compounds are characterized by low mobility.

3. Discontinuous joints (diarthrosis), or joints, are characterized by the fact that there is a gap between the connecting surfaces and the bones can move relative to each other.

Such compounds are characterized by significant mobility.

Continuous connections (synarthroses). Continuous connections have greater elasticity, strength and, as a rule, limited mobility.

Depending on the type of connective tissue located between the articulating surfaces, three types of continuous connections are distinguished:
Fibrous joints, or syndesmoses, are strong joints of bones using dense fibrous connective tissue that fuses with the periosteum of the connecting bones and passes into it without a clear boundary.

Syndesmoses include: ligaments, membranes, sutures and impaction (Fig. 63).

Ligaments serve primarily to strengthen the joints of bones, but can limit movement in them. Ligaments are built from dense connective tissue rich in collagen fibers.

However, there are ligaments that contain a significant amount of elastic fibers (for example, the yellow ligaments located between the vertebral arches).

Membranes (interosseous membranes) connect adjacent bones over a considerable distance, for example, they are stretched between the diaphyses of the bones of the forearm and lower leg and cover some bone openings, for example, the obturator foramen of the pelvic bone.

Often, the interosseous membranes serve as the origin of the muscle.

Seams- a type of fibrous joint in which there is a narrow connective tissue layer between the edges of the connecting bones. Connections of bones by sutures are found only in the skull. Depending on the configuration of the edges, there are:
- serrated sutures (in the roof of the skull);
- scaly suture (between the scales of the temporal bone and the parietal bone);
- flat sutures (in the facial skull).

Impaction is a dento-alveolar junction in which between the root of the tooth and the dental alveolus there is a narrow layer of connective tissue - the periodontium.

Cartilaginous joints, or synchondroses, are connections between bones using cartilaginous tissue (Fig.

64). This type of connection is characterized by high strength, low mobility and elasticity due to the elastic properties of cartilage.

There are synchondrosis permanent and temporary:
1.

Permanent synchondrosis is a type of connection in which cartilage between the connecting bones exists throughout life (for example, between the pyramid of the temporal bone and the occipital bone).
2.

Temporary synchondrosis is observed in cases where the cartilaginous layer between the bones persists until a certain age (for example, between the pelvic bones), then the cartilage is replaced by bone tissue.

Bone joints, or synostoses, are connections between bones using bone tissue.

Synostoses are formed as a result of replacement by bone tissue of other types of bone joints: syndesmoses (for example, frontal syndesmosis), synchondroses (for example, sphenoid-occipital synchondrosis) and symphyses (mandibular symphysis).

Semi-continuous connections (symphyses). Semi-continuous joints, or symphyses, include fibrous or cartilaginous joints, in the thickness of which there is a small cavity in the form of a narrow slit (Fig.

65), filled with synovial fluid. Such a connection is not covered with a capsule on the outside, and the inner surface of the gap is not lined with synovial membrane.

In these joints, slight displacements of the articulating bones relative to each other are possible. The symphyses are found in the sternum - the symphysis of the manubrium of the sternum, in the spinal column - the intervertebral symphyses and in the pelvis - the pubic symphysis.

Lesgaft, the formation of a particular joint is also determined by the function assigned to this part of the skeleton. In the parts of the skeleton where mobility is necessary, diarthrosis forms (on the limbs); where protection is needed, synarthrosis (connection of the skull bones) is formed; in places experiencing supporting load, continuous joints or sedentary diarthrosis (joints of the pelvic bones) are formed.

Discontinuous connections (joints). Discontinuous joints, or joints, are the most advanced types of bone connections.

They are distinguished by great mobility and a variety of movements.

Required elements of the joint (Fig. 66):

1. Dry surface. At least two articular surfaces are involved in the formation of a joint. In most cases they correspond to each other, i.e.

congruent. If one articular surface is convex (head), then the other is concave (glenoid cavity). In a number of cases, these surfaces do not correspond to each other either in shape or in size - they are incongruent. The articular surfaces are usually covered with hyaline cartilage. Exceptions are the articular surfaces in the sternoclavicular and temporomandibular joints - they are covered with fibrous cartilage.

Articular cartilages smooth out unevenness of the articular surfaces and also absorb shocks during movement. The greater the load a joint experiences under the influence of gravity, the greater the thickness of the articular cartilage.

2. The joint capsule is attached to the articulating bones near the edges of the articular surfaces. It firmly fuses with the periosteum, forming a closed articular cavity.

The joint capsule consists of two layers. The outer layer is formed by a fibrous membrane made of dense fibrous connective tissue.

In places it forms thickenings - ligaments, which can be located outside the capsule - extracapsular ligaments and in the thickness of the capsule - intracapsular ligaments.

Extracapsular ligaments are part of the capsule, forming one inextricable whole with it (for example, the coracohumeral ligament). Sometimes more or less separate ligaments are found, for example, the collateral fibular ligament of the knee joint.

Intracapsular ligaments lie in the joint cavity, running from one bone to another.

They are composed of fibrous tissue and covered by a synovial membrane (for example, the ligament of the femoral head). Ligaments, developing in certain places of the capsule, increase the strength of the joint, depending on the nature and amplitude of movements, playing the role of brakes.

The inner layer is formed by a synovial membrane, built from loose fibrous connective tissue.

It lines the inside of the fibrous membrane and continues onto the surface of the bone, which is not covered by articular cartilage. The synovial membrane has small outgrowths - synovial villi, which are very rich in blood vessels that secrete synovial fluid.

3. The articular cavity is a slit-like space between the articular surfaces covered with cartilage. It is bounded by the synovial membrane of the joint capsule and contains synovial fluid.

There is negative atmospheric pressure inside the articular cavity, which prevents the divergence of the articular surfaces.

4. Synovial fluid is secreted by the synovial membrane of the capsule. It is a viscous transparent liquid that lubricates the cartilage-covered articular surfaces of bones and reduces their friction against each other.

Auxiliary elements of the joint (Fig.

67):

1. Articular discs and menisci- these are cartilaginous plates of various shapes, located between articular surfaces that do not completely correspond to each other (incongruent).

Discs and menisci can shift with movement. They smooth out the articulating surfaces, make them congruent, and absorb shocks and shocks during movement. Discs are found in the sternoclavicular and temporomandibular joints, and menisci are found in the knee joint.

2. Articular lips are located along the edge of the concave articular surface, deepening and complementing it. With their base they are attached to the edge of the articular surface, and with their inner concave surface they face the joint cavity.

The labrum increases joint congruence and promotes more even pressure from one bone to another. Articular lips are present in the shoulder and hip joints.

3. Synovial folds and bags. In places where the articulating surfaces are incongruent, the synovial membrane usually forms synovial folds (for example, in the knee joint).

In thin places of the joint capsule, the synovial membrane forms bag-like protrusions or inversions - synovial bursae, which are located around the tendons or under the muscles lying near the joint. Being filled with synovial fluid, they facilitate friction of tendons and muscles during movements.

The skeleton is divided into the following parts: the skeleton of the body (vertebrae, ribs, sternum), the skeleton of the head (bones of the skull and face), the bones of the limb girdles - upper (scapula, collarbone) and lower (pelvic) and the bones of the free limbs - upper (shoulder, bones forearm and hand) and lower (thigh, leg bones and foot).

Based on their external shape, bones are divided into tubular, spongy, flat and mixed.

I. Tubular bones. They are part of the skeleton of the limbs and are divided into long tubular bones(shoulder and bones of the forearm, femur and bones of the leg), having endochondral foci of ossification in both epiphyses (biepiphyseal bones) and short tubular bones(clavicle, metacarpal bones, metatarsals and phalanges of the fingers), in which the endochondral focus of ossification is present only in one (true) epiphysis (monoepiphyseal bones).

II. Spongy bones. Among them there are long spongy bones(ribs and sternum) and short(vertebrae, carpal bones, tarsus). Spongy bones include sesamoid bones, i.e., sesame plants similar to sesame grains (patella, pisiform bone, sesamoid bones of the fingers and toes); their function is auxiliary devices for muscle work; development is endochondral in the thickness of the tendons.

III. Flat Bones: A) flat bones of the skull(frontal and parietal) perform a predominantly protective function. These bones develop on the basis of connective tissue (integumentary bones); b) flat bones belts(scapula, pelvic bones) perform the functions of support and protection, develop on the basis of cartilaginous tissue.

IV. Mixed dice(bones of the base of the skull). These include bones that merge from several parts that have different functions, structure and development. Mixed bones also include the clavicle, which develops partly endesmally and partly endochondrally.

BONE STRUCTURE IN X-RAY
IMAGE

X-ray examination of the skeleton reveals directly on a living object both the external and internal structure of the bone. On radiographs, a compact substance, which gives an intense contrasting shadow, and a spongy substance, the shadow of which has a network-like character, are clearly distinguishable.

Compact substance epiphyses of tubular bones and the compact substance of spongy bones has the appearance of a thin layer bordering the spongy substance.

In the diaphyses of tubular bones, the compact substance varies in thickness: in the middle part it is thicker, towards the ends it narrows. In this case, between the two shadows of the compact layer, the bone marrow cavity is noticeable in the form of some clearing against the background of the general shadow of the bone.

Spongy substance on the radiograph it looks like a looped network consisting of bone crossbars with clearings between them. The nature of this network depends on the location of the bone plates in a given area.

X-ray examination of the skeletal system becomes possible from the 2nd month of uterine life, when ossification points. Knowledge of the location of ossification points, the timing and order of their appearance is extremely important in practical terms. Failure to merge additional ossification points with the main part of the bone can cause diagnostic errors.

All major ossification points appear in the bones of the skeleton before the onset of puberty, called puberty. With its onset, the fusion of the epiphyses with the metaphyses begins. This is radiographically expressed in the gradual disappearance of clearing at the site of the metaepiphyseal zone, corresponding to the epiphyseal cartilage separating the epiphysis from the metaphysis.

Aging bones. In old age, the skeletal system undergoes the following changes, which should not be interpreted as symptoms of pathology.

I. Changes caused by atrophy of bone substance: 1) a decrease in the number of bone plates and bone loss (osteoporosis), while the bone becomes more transparent on an x-ray; 2) deformation of the articular heads (disappearance of their round shape, “grinding down” of the edges, appearance of “corners”).

II. Changes caused by excessive deposition of lime in the connective tissue and cartilaginous formations adjacent to the bone: 1) narrowing of the articular X-ray gap due to calcification of the articular cartilage; 2) bone growths - osteophytes, formed as a result of calcification of ligaments and tendons at the site of their attachment to the bone.

The described changes are normal manifestations of age-related variability in the skeletal system.

SKELETON OF THE TORSO

The elements of the trunk skeleton develop from the primary segments (somites) of the dorsal mesoderm (sclerotome), lying on the sides of the chorda dorsalis and the neural tube. The spinal column is composed of a longitudinal series of segments - vertebrae, which arise from the nearest halves of two adjacent sclerotomes. At the beginning of the development of the human embryo, the spine consists of cartilaginous formations - the body and the neural arch, lying metamerically on the dorsal and ventral sides of the notochord. Subsequently, individual elements of the vertebrae grow, which leads to two results: firstly, to the fusion of all parts of the vertebra and, secondly, to displacement of the notochord and its replacement by vertebral bodies. The notochord disappears, remaining between the vertebrae as a nucleus pulposus in the center of the intervertebral discs. The superior (neural) arches enclose the spinal cord and merge to form unpaired spinous and paired articular and transverse processes. The lower (ventral) arches give rise to ribs that lie between the muscle segments, covering the general body cavity. The spine, having passed the cartilaginous stage, becomes bone, with the exception of the spaces between the vertebral bodies, where the intervertebral cartilage connecting them remains.

The number of vertebrae in a series of mammals fluctuates sharply. While there are 7 cervical vertebrae, in the thoracic region the number of vertebrae varies according to the number of preserved ribs. A person has 12 thoracic vertebrae, but there can be 11-13 of them. The number of lumbar vertebrae also varies; in humans there are 4-6, more often 5, depending on the degree of fusion with the sacrum.

If the XIII rib is present, the first lumbar vertebra becomes like the XIII thoracic vertebra, and only four lumbar vertebrae remain. If the XII thoracic vertebra does not have a rib, then it is similar to the lumbar vertebra ( lumbarization); in this case there will be only eleven thoracic vertebrae, and six lumbar vertebrae. The same lumbarization can occur with the first sacral vertebra if it does not fuse with the sacrum. If the V lumbar vertebra fuses with the I sacral vertebra and becomes similar to it ( sacralization), then there will be 6 sacral vertebrae. The number of coccygeal vertebrae is 4, but ranges from 5 to 1. As a result, the total number of human vertebrae is 30-35, most often 33. A person’s ribs develop in the thoracic region, but the ribs remain in the remaining regions in a rudimentary form, merging with the vertebrae.

The human torso skeleton has the following characteristic features, determined by the vertical position and development of the upper limb as a labor organ:

1) a vertically located spinal column with bends;

2) a gradual increase in the vertebral bodies from top to bottom, where in the area of the connection with the lower limb through the girdle of the lower limb they merge into a single bone - the sacrum;

3) wide and flat chest with a predominant transverse dimension and the smallest anteroposterior dimension.

SPINAL COLUMN

Spinal column, columna vertebralis, has a metameric structure and consists of separate bone segments - vertebrae, vertebrae, superimposed sequentially on one another and belonging to short spongy bones.

The spinal column acts as an axial skeleton, which supports the body, protects the spinal cord located in its canal, and participates in the movements of the torso and skull.

General properties of vertebrae. According to the three functions of the spinal column each vertebra, vertebra (Greek spondylos), has:

1) the supporting part, located in front and thickened in the form of a short column, – body, corpus vertebrae;

2) arc, arcus vertebrae, which is attached to the body at the back with two legs, pedunculi arcus vertebrae, and closes vertebral foramen, foramen vertebral; from a collection of vertebral foramina in the spinal column is formed spinal canal, canalis vertebralis, which protects the spinal cord from external damage. Consequently, the vertebral arch primarily performs a protective function;

3) on the arch there are devices for the movement of the vertebrae - shoots. Moves backward along the midline from the arc spinous process, processus spinosus; on the sides on each side - on transverse, processus transversus; up and down - paired articular processes, processus articulares superiores et inferiores. The latter limit from behind clippings, incisurae vertebrales superiores et inferiores, from which, when one vertebra is superimposed on another, they are obtained intervertebral foramina, foramina intervertebralia, for the nerves and vessels of the spinal cord. The articular processes serve to form intervertebral joints, in which movements of the vertebrae occur, and the transverse and spinous processes serve to attach ligaments and muscles that move the vertebrae.

In different parts of the spinal column, individual parts of the vertebrae have different sizes and shapes, as a result of which the vertebrae are distinguished: cervical (7), thoracic (12), lumbar (5), sacral (5) and coccygeal (1-5).

The supporting part of the vertebra (body) in the cervical vertebrae is relatively little expressed (in the first cervical vertebra the body is even absent), and in the downward direction the vertebral bodies gradually increase, reaching their largest sizes in the lumbar vertebrae; the sacral vertebrae, which bear the entire weight of the head, torso and upper limbs and connect the skeleton of these parts of the body with the bones of the lower limbs, and through them with the lower limbs, grow together into a single sacrum (“in unity is strength”). On the contrary, the coccygeal vertebrae, which are a remnant of the tail that disappeared in humans, look like small bone formations in which the body is barely expressed and there is no arch.

The vertebral arch, as a protective part in places where the spinal cord is thickened (from the lower cervical to the upper lumbar vertebrae), forms a wider vertebral foramen. Due to the end of the spinal cord at the level of the second lumbar vertebra, the lower lumbar and sacral vertebrae have a gradually narrowing vertebral foramen, which completely disappears at the coccyx.

The transverse and spinous processes, to which muscles and ligaments are attached, are more pronounced where more powerful muscles are attached (lumbar and thoracic regions), and on the sacrum, due to the disappearance of the tail muscles, these processes decrease and, merging, form small ridges on the sacrum. Due to the fusion of the sacral vertebrae, the articular processes, which are well developed in the mobile parts of the spinal column, especially in the lumbar, disappear in the sacrum.

Thus, in order to understand the structure of the spinal column, it is necessary to keep in mind that the vertebrae and their individual parts are more developed in those sections that experience the greatest functional load. On the contrary, where functional requirements decrease, there is also a reduction in the corresponding parts of the spinal column, for example, in the coccyx, which in humans has become a rudimentary formation.

An important part of the human musculoskeletal system is the skeleton, which consists of more than two hundred different bones. It allows people to move and supports internal organs. In addition, they are a concentration of minerals, as well as a membrane that contains bone marrow.

Skeletal functions

The various types of bones that make up the human skeleton primarily act as a means of support and support for the body. Some of them serve as a container for certain internal organs, such as the brain, located in the bones of the skull, lungs and heart, located in the chest, and others.

We also owe the ability to perform various movements and move around to our own skeleton. In addition, human bones contain up to 99% of the calcium found in the body. Red bone marrow is of great importance in human life. It is located in the skull, spine, sternum, collarbones and some other bones. Blood cells are born in the bone marrow: red blood cells, platelets and leukocytes.

Bone structure

The anatomy of bone has extraordinary properties that determine its strength. The skeleton must withstand a load of 60-70 kg - this is the average weight of a person. In addition, the bones of the trunk and limbs act as levers that allow us to move and perform various actions. This is achieved due to their amazing composition.

Bones consist of organic (up to 35%) and inorganic (up to 65%) substances. The first include protein, mainly collagen, which determines the firmness and elasticity of tissues. Inorganic substances - calcium and phosphorus salts - are responsible for hardness. The combination of these elements gives the bones special strength, comparable, for example, to cast iron. They can be perfectly preserved for many years, as evidenced by the results of various excavations. may disappear as a result of calcination of tissues, as well as when exposed to sulfuric acid. Minerals are very resistant to external influences.

Human bones are penetrated by special tubules through which blood vessels run. In their structure, it is customary to distinguish between compact and spongy substances. Their ratio is determined by the location of the bone in the human body, as well as the functions it performs. In areas where resistance to heavy loads is required, a dense, compact substance is the main material. Such a bone consists of many cylindrical plates placed one inside the other. The spongy substance resembles a honeycomb in its appearance. In its cavities there is red bone marrow, and in adults there is also yellow bone marrow, in which fat cells are concentrated. The bone is covered by a special connective tissue membrane - the periosteum. It is permeated with nerves and blood vessels.

Classification of bones

There are various classifications that cover all types of bones of the human skeleton depending on their location, structure and functions.

1. By location:

cranial bones;
trunk bones;
limb bones.

2. According to development, the following types of bones are distinguished:

primary (appears from connective tissue);
secondary (formed from cartilage);
mixed.

3. The following types of human bones are distinguished by structure:

tubular;
spongy;
flat;
mixed.

Thus, science knows different types of bones. The table makes it possible to more clearly present this classification.

Tubular bones

Tubular long bones consist of both dense and spongy substance. They can be divided into several parts. The middle of the bone is formed by a compact substance and has an elongated tubular shape. This area is called the diaphysis. Its cavities first contain red bone marrow, which is gradually replaced by yellow bone marrow containing fat cells.

At the ends of the tubular bone there is an epiphysis - this is an area formed by spongy substance. Red bone marrow is placed inside it. The area between the diaphysis and the epiphysis is called the metaphysis.

During the period of active growth of children and adolescents, it contains cartilage, due to which the bone grows. Over time, the anatomy of the bone changes, the metaphysis completely turns into bone tissue. Long bones include the thigh, shoulder, and forearm bones. Tubular small bones have a slightly different structure. They have only one true epiphysis and, accordingly, one metaphysis. These bones include the phalanges of the fingers and metatarsal bones. They function as short movement levers.

Spongy types of bones. Images

The name of the bones often indicates their structure. For example, cancellous bones are formed from spongy substance covered with a thin layer of compact. They do not have developed cavities, so the red bone marrow is placed in small cells. Spongy bones are also long and short. The first include, for example, the sternum and ribs. Short spongy bones are involved in the work of muscles and are a kind of auxiliary mechanism. These include the vertebrae.

Flat Bones

These types of human bones, depending on their location, have different structures and perform certain functions. The bones of the skull are, first of all, protection for the brain. They are formed by two thin plates of dense substance, between which there is a spongy substance. It contains holes for veins. The flat bones of the skull develop from connective tissue. The scapula and also belong to the type of flat bones. They are formed almost entirely from spongy substance, which develops from cartilage tissue. These types of bones serve not only as protection, but also as support.

Mixed dice

Mixed bones are a combination of flat and short spongy or tubular bones. They develop in different ways and perform those functions that are necessary in a particular area of the human skeleton. These types of bones, such as mixed ones, are found in the body of the temporal bone and vertebrae. These include, for example, the collarbone.

Cartilage tissue

Cartilage tissue has an elastic structure. It forms the ears, nose, and some parts of the ribs. It is also located between the vertebrae, as it perfectly resists the deforming force of loads. It has high strength, excellent resistance to abrasion and compression.

Connection of bones

There are different ones that determine the degree of their mobility. The bones of the skull, for example, have a thin layer of connective tissue. At the same time, they are absolutely motionless. This connection is called fibrous. Between the vertebrae there are also areas of connective or cartilaginous tissue. This connection is called semi-mobile, since the bones, although limited, can move slightly.

The joints that form synovial joints have the highest mobility. The bones in the joint capsule are held in place by ligaments. These fabrics are both flexible and durable. In order to reduce friction, the joint contains a special oily fluid - synovium. It envelops the ends of the bones, covered with cartilage tissue, and facilitates their movement.

There are several types of joints. Just as the name of bones is determined by their structure, the name of joints depends on the shape of the bones that they connect. Each type allows you to perform certain movements:

Ball and socket joint. With this connection, the bones move in many directions at once. These joints include the shoulder and hip.
Block joint (elbow, knee). Involves movement exclusively in one plane.
Cylindrical joint allows bones to move relative to each other.
Flat joint. It is inactive and provides small-scale movements between two bones.
Ellipsoid joint. In this way, for example, the radius bone is connected to the bones of the wrist. They can move from side to side within the same plane.
Thanks to saddle joint the thumb can move in different planes.

Effect of physical activity

The degree of physical activity has a significant impact on the shape and structure of bones. The same bone can have its own characteristics in different people. With constant, impressive physical exertion, the compact substance thickens, and the cavity, on the contrary, shrinks in size.

Long stays in bed and a sedentary lifestyle negatively affect the condition of bones. Fabrics become thinner, lose their strength and elasticity, and become fragile.

The shape of the bones also changes under the influence of physical activity. The areas where the muscles act on them may become flatter. With particularly intense pressure, small indentations may even appear over time. In areas of severe stretching, where ligaments act on the bones, thickenings, various irregularities, and tubercles can form. Such changes are especially typical for people who are professionally involved in sports.

The shape of bones is also influenced by various injuries, especially those sustained in adulthood. When a fracture heals, all sorts of deformations can occur, which often negatively affect the ability to effectively control your body.

Age-related changes in bones

At different periods of a person’s life, the structure of his bones is not the same. In infants, almost all bones consist of spongy substance, which is covered with a thin layer of compact. Their continuous, up to a certain time, growth is achieved due to an increase in the size of cartilage, which is gradually replaced by bone tissue. This transformation continues until the age of 20 in women and until approximately 25 in men.

The younger a person is, the more organic substances are contained in the tissues of his bones. Therefore, at an early age they are elastic and flexible. In an adult, the volume of mineral compounds in bone tissue is up to 70%. At the same time, from a certain point, a decrease in the amount of calcium and phosphorus salts begins. Bones become fragile, so older people often experience fractures even as a result of a minor injury or careless sudden movement.

Such fractures take a long time to heal. There is a special disease characteristic of older people, especially women - osteoporosis. To prevent it, when you reach the age of 50, you need to consult a doctor to conduct some studies to assess the condition of the bone tissue. With appropriate treatment, the risk of fractures is significantly reduced and their healing time is shortened.

Everyone needs to know the human skeleton with the names of the bones. This is important not only for doctors, but also for ordinary people, because information about the body, its skeleton and muscles will help strengthen it, feel healthy, and at some point can help out in emergency situations.

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Types of bones in the adult body

The skeleton and muscles together make up the human locomotor system. The human skeleton is a whole complex of bones of different types and cartilage, interconnected by continuous joints, synarthrosis, symphyses. Bones are divided according to their composition into:

tubular, forming the upper (shoulder, forearm) and lower (thigh, lower leg) limbs;
spongy, foot (in particular, tarsus) and human hand (wrist);
mixed - vertebrae, sacrum;
flat, this includes the pelvic and cranial bones.

Important! Bone tissue, despite its increased strength, is capable of growing and regenerating. Metabolic processes occur in it, and blood is even formed in the red bone marrow. With age, bone tissue is rebuilt and becomes able to adapt to various loads.

Types of bones

How many bones are there in the human body?

The structure of the human skeleton undergoes many changes throughout life. At the initial stage of development, the fetus consists of fragile cartilaginous tissue, which over time is gradually replaced by bone tissue. A newborn baby has more than 270 small bones. With age, some of them can grow together, for example, the cranial and pelvic ones, as well as some vertebrae.

It is very difficult to say exactly how many bones are in the body of an adult. Sometimes people have extra ribs or bones in their feet. There may be growths on the fingers, a slightly smaller or larger number of vertebrae in any part of the spine. The structure of the human skeleton is purely individual. On average for an adult have from 200 to 208 bones.

Functions of the human skeleton

Each department performs its own highly specialized tasks, but the human skeleton as a whole has several common functions:

Support. The axial skeleton is the support for all the soft tissues of the body and a system of levers for the muscles.
Motor. Movable joints between bones allow a person to make millions of precise movements using muscles, tendons, and ligaments.
Protective. The axial skeleton protects the brain and internal organs from injury and acts as a shock absorber during impacts.
Metabolic. The composition of bone tissue includes a large amount of phosphorus and iron, which are involved in the exchange of minerals.
Hematopoietic. The red marrow of the long bones is the place where hematopoiesis occurs - the formation of erythrocytes (red blood cells) and leukocytes (cells of the immune system).

If certain skeletal functions are impaired, diseases of varying severity may occur.

Functions of the human skeleton

Skeletal departments

The human skeleton is divided into two large sections: axial (central) and accessory (or skeleton of the limbs). Each department performs its own tasks. The axial skeleton protects the abdominal organs from damage. The skeleton of the upper limb connects the arm to the torso. Due to the increased mobility of the hand bones, it helps to perform many precise movements with the fingers. The functions of the skeleton of the lower extremities are to connect the legs to the body, move the body, and provide shock absorption when walking.

Axial skeleton. This section forms the basis of the body. It includes: the skeleton of the head and torso.

Skeleton of the head. The cranial bones are flat, motionlessly connected (with the exception of the movable lower jaw). They protect the brain and sense organs (hearing, vision and smell) from concussions. The skull is divided into the facial (visceral), cerebral and middle ear sections.

Skeleton of the torso. Bones of the chest. In appearance, this subsection resembles a compressed truncated cone or pyramid. The rib cage includes paired ribs (out of 12, only 7 are articulated with the sternum), vertebrae of the thoracic spine and the sternum - the unpaired breast bone.

Depending on the connection of the ribs with the sternum, true (upper 7 pairs), false (next 3 pairs), floating (last 2 pairs) are distinguished. The sternum itself is considered the central bone included in the axial skeleton.

It consists of a body, an upper part - the manubrium, and a lower part - the xiphoid process. The bones of the chest have high-strength connection with the vertebrae. Each vertebra has a special articular fossa designed for attachment to the ribs. This method of articulation is necessary to perform the main function of the body skeleton - protecting the human life-support organs: the lungs, part of the digestive system.

Important! The bones of the chest are subject to external influences and are prone to modification. Physical activity and proper sitting position at the table contribute to the proper development of the chest. A sedentary lifestyle and slouching lead to tightness of the chest organs and scoliosis. An improperly developed skeleton can lead to serious health problems.

Spine. The department is central axis and main support the entire human skeleton. The spinal column is formed from 32-34 individual vertebrae that protect the spinal canal with nerves. The first 7 vertebrae are called the cervical, the next 12 are called the thoracic, then there are the lumbar (5), 5 fused to form the sacrum, and the last 2-5 to form the coccyx.

The spine supports the back and torso, provides, through the spinal nerves, the motor activity of the entire body and connects the lower part of the body with the brain. The vertebrae are connected to each other semi-movably (in addition to the sacral ones). This connection is carried out through intervertebral discs. These cartilaginous formations soften shocks and shocks during any human movement and provide flexibility to the spine.

Limb skeleton

Skeleton of the upper limb. Skeleton of the upper limb represented by the shoulder girdle and the skeleton of the free limb. The shoulder girdle connects the arm to the body and includes two paired bones:

The collarbone, which has an S-shaped bend. At one end it is attached to the sternum, and at the other it is connected to the scapula.
A spatula. In appearance it is a triangle adjacent to the body from the back.

The skeleton of the free limb (arm) is more mobile, since the bones in it are connected by large joints (shoulder, wrist, elbow). Skeleton represented by three subdivisions:

The shoulder, which consists of one long tubular bone - the humerus. One of its ends (epiphysis) is attached to the scapula, and the other, passing into the condyle, to the forearm bones.
Forearm: (two bones) the ulna, located in line with the little finger and the radius - in line with the first finger. Both bones on the lower epiphyses form a radiocarpal articulation with the carpal bones.
A hand that includes three parts: the bones of the wrist, metacarpus and digital phalanges. The wrist is represented by two rows of four spongy bones each. The first row (pisiform, triangular, lunate, scaphoid) is used for attachment to the forearm. In the second row there are the hamate, trapezium, capitate and trapezoid bones, facing towards the palm. The metacarpus consists of five tubular bones, with their proximal part they are motionlessly connected to the wrist. Finger bones. Each finger consists of three phalanges connected to each other, in addition to the thumb, which is opposed to the others, and has only two phalanges.

Skeleton of the lower limb. The skeleton of the leg, as well as the arm, consists of a limb girdle and its free part.

Limb skeleton

The girdle of the lower extremities is formed by the paired bones of the pelvis. They grow together from paired pubic, ilium and ischial bones. This occurs by the age of 15-17, when the cartilaginous connection is replaced by a fixed bone one. Such strong articulation is necessary to support the organs. Three bones to the left and right of the body axis form the acetabulum, which is necessary for the articulation of the pelvis with the head of the femur.

The bones of the free lower limb are divided into:

Femoral. The proximal (upper) epiphysis connects to the pelvis, and the distal (lower) epiphysis connects to the tibia.
The patella (or kneecap) covers, formed at the junction of the femur and tibia.
The lower leg is represented by the tibia, located closer to the pelvis, and the fibula.
Bones of the foot. The tarsus is represented by seven bones, making up 2 rows. One of the largest and well-developed bones is the heel bone. The metatarsus is the middle section of the foot; the number of bones included in it is equal to the number of toes. They are connected to the phalanges using joints. Fingers. Each finger consists of 3 phalanges, except the first, which has two.

Important! Throughout life, the foot is subject to changes; calluses and growths may form on it, and there is a possible risk of developing flat feet. This is often due to the wrong choice of shoes.

Sex differences

Structure of a woman and a man no fundamental differences. Only certain parts of some bones or their sizes undergo changes. Among the most obvious are narrower breasts and a wider pelvis in a woman, which is associated with labor. Men's bones, as a rule, are longer, more powerful than women's, and have more traces of muscle attachment. It is much more difficult to distinguish a female skull from a male one. The male skull is slightly thicker than the female, it has a more pronounced contour of the brow ridges and the occipital protuberance.

What are flat bones definition. Flat bones. Age-related changes in bones

Lecture: Classification of bones by shape and internal structure. Classification of bones.

3. Types of bones and their connections

Skeletal functions

Bone structure

Classification of bones

Tubular bones

Spongy types of bones. Images

Flat Bones

Mixed dice

Cartilage tissue

Connection of bones

Effect of physical activity

Age-related changes in bones

Types of bones in the adult body

How many bones are there in the human body?

Functions of the human skeleton

Skeletal departments

Limb skeleton

Sex differences

3.
Types of bones and their connections