The flat bones of the skeleton are the radial pelvic bones. Flat human bones
The human skeleton consists of the following parts: bones of free limbs - upper (bones of the hand and forearm, shoulder) and lower (bones of the foot and lower leg, thigh); bones of the limb belts - upper (collarbone and shoulder blade) and lower (pelvic); skeleton of the head (bones of the face and skull); bones of the body (sternum, ribs, vertebrae).
The adult human skeleton consists of more than 200 bones. The bones of the skeleton vary in shape, as mixed, flat, short and long. But such a division of bones (in form) is formal and one-sided. For example, the parietal bone belongs to the group of flat bones, while in fact it is a typical integumentary bone, ossifying endesmally. In addition, pathological processes in the bones and phalanges of the wrist are completely different, despite the fact that they belong to short bones. Based on this, it was proposed to distinguish bones according to three main principles: form (structure), functions and development.
The classification of bones is as follows:
Mixed bones.
flat bones- the bones of the belts and the bones of the skull.
Spongy bones - sesamoid, short, long.
Tubular bones - short and long.
Tubular bones are built from a compact and spongy substance, which form a tube with a bone marrow cavity. Tubular bones perform such functions as movement, protection and support. Long tubular bones include the bones of the lower leg, thigh, bones of the forearm and shoulder. They are long and persistent levers of movement, in both epiphyses they have foci of ossification. Short tubular bones include phalanges, metatarsus, and metacarpal bones. Short tubular bones are short levers of movement.
Of a spongy substance that is covered thin layer compact, predominantly spongy bones. There are short (tarsus, wrist bones, vertebrae) and long (sternum and ribs) spongy bones. Sesamoid bones are spongy bones. They look like sesame seeds, which is why they are given this name. Their main function is an auxiliary device for the work of muscles. They have endochondral development in the thickness of the tendons. Sesamoid bones are located near the joints, in whose formation they participate, and also contribute to movement in them. They are not directly connected to the bones of the skeleton.
The flat bones are flat bones of the skull(parietal and frontal), the main function of which is protective. They consist of a compact substance in the form of two thin plates. Between them there is a spongy substance - dirloe, which contains channels for veins. Such bones are integumentary, their development is based on connective tissue.
Morphology, physiology and pathophysiology of the musculoskeletal system.
Movement plays a huge role in wildlife and is one of the main adaptive reactions to the environment. external environment and a necessary factor in human development. The movement of a person in space is carried out thanks to the musculoskeletal system.
The musculoskeletal system is formed by bones, their joints and striated muscles.
Bones and their joints are the passive part of the musculoskeletal system, while muscles are the active part.
General anatomy of the skeleton. The human skeleton (skeletos) consists of more than 200 bones, 85 of them are paired, interconnected by means of a connective tissue with a different structure.
Skeleton Functions .
The skeleton performs mechanical and biological functions.
To mechanical functions skeleton include:
protection,
· motion.
The bones of the skeleton form cavities (vertebral canal, skull, chest, abdominal, pelvis) that protect the internal organs located in them from external influences.
Support is carried out by attaching muscles and ligaments to various parts of the skeleton, as well as maintaining internal organs.
Movement is possible in the places of movable joints of bones - in the joints. They are driven by muscles under the control of the nervous system.
to biological functions skeleton include:
The participation of bones in metabolism, especially in mineral metabolism - is a depot of mineral salts (phosphorus, calcium, iron, etc.)
Participation of bones in hematopoiesis. The function of hematopoiesis is performed by the red bone marrow contained in spongy bones.
Mechanical and biological functions mutually influence each other.
Each bone occupies a certain position in the human body, has its own anatomical structure and performs its own functions.
The bone consists of several types of tissues, the main place of which is occupied by solid connective tissue - bone.
The outside of the bone is covered periosteum, except for articular surfaces covered with articular cartilage.
Bone contains red bone marrow, adipose tissue, blood vessels, lymphatic vessels and nerves.
The chemical composition of the bone. The bone consists of 1/3 organic (ossein, etc.) and 2/3 inorganic (calcium salts, especially phosphates) substances. Under the action of acids (hydrochloric, nitric, etc.), calcium salts dissolve, and the bone with the remaining organic substances will retain its shape, but become soft and elastic. If the bone is burned, then the organic substances will burn, and the inorganic ones will remain. The bone will also retain its shape, but it will become very brittle. It follows that the elasticity of the bone depends on ossein, and mineral salts give it hardness.
AT childhood bones contain more organic matter, so the bones in children are more flexible and rarely break. In older people in chemical composition bones are dominated by inorganic substances, the bones become less elastic and more brittle, so they break more often.
Classification of bones. According to the classification of M.G. Weight gain, bones are: tubular, spongy, flat and mixed.
tubular bones are long and short and perform the functions of support, protection and movement. Tubular bones have a body, a diaphysis, in the form of a bone tube, the cavity of which is filled in adults with yellow bone marrow. The ends of tubular bones are called epiphyses. The cells of spongy tissue contain red bone marrow. Between the diaphysis and the epiphyses are the metaphyses, which are zones of bone growth in length.
spongy bones Distinguish between long (ribs and sternum) and short (vertebrae, carpal bones, tarsus).
They are built from a spongy substance covered with a thin layer of compact. Spongy bones include sesamoid bones (patella, pisiform bone, sesamoid bones of fingers and toes). They develop in the tendons of the muscles and are auxiliary devices for their work.
flat bones, forming the roof of the skull, built of two thin plates of compact substance, between which there is a spongy substance, diploe, containing cavities for veins; flat bones of the belts are built of spongy substance (scapula, pelvic bones). Flat bones perform the functions of support and protection,
mixed dice merge from several parts that have different functions, structure and development (bones of the base of the skull, collarbone).
Question 2. Types of bone joints.
All bone joints can be divided into 2 groups:
1) continuous connections - synarthrosis (fixed or inactive);
2) discontinuous connections - diarthrosis or joints (mobile in function).
The transitional form of bone joints from continuous to discontinuous is characterized by the presence of a small gap, but the absence of an articular capsule, as a result of which this form is called a semi-joint or symphysis.
Continuous connections - synarthrosis.
There are 3 types of synarthrosis:
1) Syndesmosis - the connection of bones with the help of ligaments (ligaments, membranes, sutures). Example: skull bones.
2) Synchondrosis - connection of bones with the help of cartilaginous tissue (temporary and permanent). The cartilaginous tissue located between the bones acts as a buffer that softens shocks and tremors. Example: vertebrae, first rib and vertebra.
3) Synostosis - connection of bones through bone tissue. Example: pelvic bones.
Discontinuous connections, joints - diarthrosis. At least two are involved in the formation of joints. articular surfaces , between which is formed cavity , closed joint capsule . articular cartilage covering the articular surfaces of the bones, smooth and elastic, which reduces friction and softens shocks. Articular surfaces correspond or do not correspond to each other. The articular surface of one bone is convex and is the articular head, and the surface of the other bone, respectively, is concave, forming the articular cavity.
The articular capsule is attached to the bones that form the joint. Hermetically closes the articular cavity. It consists of two membranes: outer fibrous and inner synovial. The latter secretes a transparent liquid into the joint cavity - synovia, which moisturizes and lubricates the articular surfaces, reducing friction between them. In some joints, the synovial membrane forms, protruding into the joint cavity and containing significant amount fat.
Sometimes protrusions or eversion of the synovial membrane are formed - synovial bags lying near the joint, at the site of attachment of the tendons or muscles. Bursae contain synovial fluid and reduce friction between tendons and muscles during movement.
The articular cavity is a hermetically sealed slit-like space between the articular surfaces. Synovial fluid creates pressure in the joint below atmospheric pressure, which prevents the divergence of the articular surfaces. In addition, synovia is involved in the exchange of fluid and in strengthening the joint.
Question 3. The structure of the skeleton of the head, trunk and limbs.
The skeleton has the following parts:
1. axial skeleton
trunk skeleton (vertebrae, ribs, sternum)
The skeleton of the head (bones of the skull and face) form;
2. additional skeleton
girdles bones
Upper (scapula, clavicle)
Inferior (pelvic bone)
free limb bones
Upper (shoulder, bones of the forearm and hand)
Lower (thigh, bones of the lower leg and foot).
vertebral column is part of the axial skeleton, performs supporting, protective and locomotor functions: ligaments and muscles are attached to it, protects the spinal cord and participates in the movements of the trunk and skull. The spinal column has an S-shape due to the upright posture of a person.
The spinal column has the following divisions: cervical, consisting of 7, thoracic - of 12, lumbar - of 5, sacral - of 5 and coccygeal - of 1-5 vertebrae. The dimensions of the vertebral bodies gradually increase from top to bottom, reaching the largest sizes at the lumbar vertebrae; sacral vertebrae fuse into a single bone, due to the fact that they bear the weight of the head, torso and upper limbs.
The coccygeal vertebrae are a remnant of the tail that disappeared from humans.
Where the spine experiences the greatest functional load, the vertebrae and their individual parts are well developed. The coccygeal spine does not carry any functional load and therefore is a rudimentary formation.
The spinal column in the human skeleton is located vertically, but not straight, but forms bends in the sagittal plane. The curves in the cervical and lumbar regions are directed forward and are called lordosis , and in the thoracic and sacral - facing the bulge back - this kyphosis . The curves of the spine are formed after the birth of a child and become permanent by the age of 7-8 years.
With an increase in load, the bends of the spinal column increase, with a decrease in load, they become smaller.
The bends of the spinal column are shock absorbers during movements - they soften shocks along the spinal column, thus protecting the skull, and the brain located in it, from excessive concussions.
If the indicated bends of the spinal column in the sagittal plane are the norm, then the appearance of bends in the frontal plane (more often in the cervical and thoracic regions) is considered a pathology and is called scoliosis . The reasons for the formation of scoliosis can be different. So, schoolchildren can develop a pronounced lateral curvature of the spinal column - school scoliosis, as a result of improper landing or carrying a load (bag) in one hand. Scoliosis can develop not only in schoolchildren, but also in adults of certain professions associated with the curvature of the body during work. For the prevention of scoliosis, special gymnastics is necessary.
In old age spinal column becomes shorter due to the decrease in thickness intervertebral discs, the vertebrae themselves and loss of elasticity. The spinal column bends anteriorly, forming one large thoracic bend (senile hump).
The spinal column is a rather mobile formation. Thanks to the intervertebral discs and ligaments, it is flexible and elastic. Cartilages push the vertebrae apart, and ligaments connect them to each other.
chest form 12 thoracic vertebrae, 12 pairs of ribs and sternum.
Sternum consists of three parts: handle, body and xiphoid process. A jugular notch is located on the upper edge of the handle.
There are 12 pairs of ribs in the human skeleton. With their posterior ends, they are connected to the bodies of the thoracic vertebrae. 7 upper pairs of ribs with their front ends are connected directly to the sternum and are called true ribs . The next three pairs (VIII, IX and X) join with their cartilaginous ends to the cartilage of the previous rib and are called false edges . XI and XII pairs of ribs are located freely in the abdominal muscles - this oscillating ribs .
Rib cage It has the shape of a truncated cone, the upper end of which is narrow, and the lower one is wider. Due to upright posture, the chest is somewhat compressed from front to back.
The lower ribs form the right and left costal arches. Under xiphoid process the sternum, the right and left costal arches converge, limiting the infrasternal angle, the value of which depends on the shape of the chest.
Shape and size chest depends on: age, gender, body type, degree of development of muscles and lungs, lifestyle and profession this person. The chest contains vital organs - the heart, lungs, etc.
Distinguish 3 chest shape : flat, cylindrical and conical.
In people with well-developed muscles and lungs, brachymorphic body type, the chest becomes wide, but short and acquires conical shape. She is always in a state of inhalation. The infrasternal angle of such a chest will be obtuse.
In people of a dolichomorphic body type, with poorly developed muscles and lungs, the chest becomes narrow and long. This shape of the chest is called flat. Its front wall stands almost vertically, the ribs are strongly inclined. The chest is in a state of exhalation.
Do people have brachymorphic?? (meso) body type chest has cylindrical shape, occupying an intermediate position between the previous two. In women, the chest is shorter and narrower in the lower section than in men, and more rounded. In the process of growth and development, the shape of the chest is influenced by social factors.
Poor living conditions and malnutrition in children can significantly affect the shape of the chest. Children growing up with insufficient nutrition and solar radiation develop rickets (“English disease”), in which the chest takes the form of a “chicken breast”. The anteroposterior size predominates in it, and the sternum protrudes forward. In children with an incorrect posture when sitting, the chest is long and flat. The muscles are poorly developed. The chest is, as it were, in a collapsed state, which negatively affects the activity of the heart and lungs. For proper development chest and disease prevention in children need physical education, massage, proper nutrition, adequate lighting and other conditions.
Scull (cranium) is a receptacle for the brain and associated sense organs; in addition, it surrounds the initial sections of the digestive and respiratory tracts. In this regard, the skull is divided into 2 parts: cerebral and facial. The brain skull has a vault and a base.
Cerebral region of the skull in humans they form: unpaired - occipital, sphenoid, frontal and ethmoid bones and paired - temporal and parietal bones.
Facial region of the skull form a pair upper jaw, inferior nasal concha, palatine, zygomatic, nasal, lacrimal and unpaired - vomer, lower jaw and sublingual.
The bones of the skull are connected to each other, mainly by sutures.
In the skull of a newborn brain department the skull is relatively larger than the facial one. As a result, the facial skull protrudes slightly forward compared to the brain and makes up only an eighth of the latter, while in an adult this ratio is 1:4. Fontanelles are located between the bones that form the cranial vault. The fontanelles are the remains of a membranous skull, they are located at the intersection of the sutures. Fontanelles are of great functional importance. The bones of the cranial vault can go behind each other during childbirth, adapting to the shape and size of the birth canal.
The wedge-shaped and mastoid fontanelles overgrow either by the time of birth or immediately after birth. Newborns do not have stitches. Bones have smooth surfaces. Between the individual parts of the bones of the base of the skull that have not yet merged, there is cartilaginous tissue. Pneumatic sinuses in the bones of the skull are absent. The upper and lower jaws are poorly developed: the alveolar processes are almost absent, the lower ?? the jaw consists of two unfused halves. In adulthood, ossification of the sutures of the skull is observed.
Skeleton of the upper and lower limbs has a general structural plan and consists of two sections: belts and free upper and lower limbs. Through belts, free limbs are attached to the body.
Upper limb belt form two paired bones: the clavicle and the scapula.
Skeleton of the free upper limb consists of three sections: proximal - humerus; middle - two bones of the forearm - ulna and radius; and distal - bones of the hand.
The hand has three sections: the wrist, metacarpus and phalanges of the fingers.
Wrist form eight short spongy bones arranged in 2 rows. Each row consists of four bones.
metacarpus (metacarpus) is formed by five short tubular metacarpal bones
The bones of the fingers are the phalanges. Each finger has three phalanges located one behind the other. The exception is the thumb, which has only two phalanges.
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Human skeleton: functions, departments
The skeleton is a collection of bones, cartilage belonging to them and ligaments connecting the bones.
There are more than 200 bones in the human body. The weight of the skeleton is 7-10 kg, which is 1/8 of the weight of a person.
The human skeleton has the following departments:
- head skeleton(scull), torso skeleton- axial skeleton;
- upper limb belt, lower limb belt- additional skeleton.
Human skeleton front
Skeleton Functions:
- Mechanical functions:
- support and fastening of muscles (the skeleton supports all other organs, gives the body a certain shape and position in space);
- protection - the formation of cavities (the cranium protects the brain, the chest protects the heart and lungs, and the pelvis - 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).
- mineral metabolism;
- hematopoiesis;
- deposition of blood.
Classification of bones, features of their structure. Bone as an organ
Bone- structural and functional unit of the skeleton and an independent organ. Each bone occupies an exact position in the body, has a certain shape and structure, and performs its own function. All types of tissues are involved 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 adipose tissue, blood and lymphatic vessels, and nerves. Bone tissue has high mechanical properties, its strength can be compared with the strength of metal. The relative density of bone tissue is about 2.0. Living bone contains 50% water, 12.5% protein organic matter (ossein and osseomucoid), 21.8% inorganic minerals(mainly calcium phosphate) and 15.7% fat.
In dried bone, 2/3 are inorganic substances, on which the hardness of the bone depends, and 1/3 are organic substances, which determine its elasticity. The content of mineral (inorganic) substances in the bone gradually increases with age, as a result of which the bones of the elderly and old people become more fragile. For this reason, even minor injuries in the elderly are accompanied by bone fractures. The flexibility and elasticity of bones in children depend on the relatively high 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 not the absorption of calcium.
The structural functional unit of the bone is osteon. Usually osteon consists of 5-20 bone plates. The diameter of the osteon is 0.3–0.4 mm.
If the bone plates are tightly adjacent to each other, then a dense (compact) bone substance is obtained. If the bone crossbars are located loosely, then a spongy bone substance is formed, in which the red bone marrow is located.
Outside, 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 is a cavity filled with yellow marrow.
The internal structure of the bone
Bone classification in the form:
- tubular bones- have a general structural plan, they distinguish between the body (diaphysis) and two ends (epiphyses); cylindrical or trihedral shape; length prevails over width; outside the tubular bone is covered with a connective tissue layer (periosteum):
- long (femoral, shoulder);
- short (phalanges of fingers).
- long (sternum);
- short (vertebrae, sacrum)
- sesamoid bones - located in the thickness of the tendons and usually lie on the surface of other bones (patella).
- skull bones (skull roof);
- flat (pelvic bone, shoulder blades, bones of the belts of the upper and lower extremities).
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Lecture: Classification of bones according to shape and internal structure. Classification of bones.
In the skeleton, the following parts are distinguished: the skeleton of the body (vertebrae, ribs, sternum), the skeleton of the head (bones of the skull and face), the bones of the limb belts - the upper (scapula, collarbone) and lower (pelvic) and the bones of the free limbs - the upper (shoulder, bones forearms and hands) and lower (femur, bones of the lower leg 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.
According to the external shape, the bones are long, short, flat and mixed.
However, such a division, established back in the time of Galen, according to only one sign (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 structure, function and origin fall into one group.
So, 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 proceed quite differently in the phalanges and bones of the wrist, although both are short bones, or in the thigh and rib, enrolled 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: forms (structures), functions and development.
From this point of view, the following classification of bones(M. G. Prives):
I. Tubular bones. They are built from a spongy and compact substance that forms a tube with a bone marrow cavity; perform all 3 functions of the skeleton (support, protection and movement).
Of these, long tubular bones (shoulder and bones of the forearm, femur and bones of the lower leg) are resistant 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, metatarsus, phalanges) represent short levers of movement; of the epiphyses, the endochondral focus of ossification is present in only one (true) epiphysis (monoepiphyseal bones).
P. Spongy bones. They are built mainly of spongy substance, covered with a thin layer of compact.
Among them, long spongy bones (ribs and sternum) and short ones (vertebrae, carpal bones, tarsals) are distinguished. Spongy bones include sesamoid bones, that is, sesame plants similar to sesame grains, hence their name (patella, pisiform bone, sesamoid bones of the fingers and toes); their function is auxiliary devices for the work of muscles; development - endochondral in the thickness of the tendons. Sesamoid bones are located near the joints, participating in their formation and facilitating movements in them, but they are not directly connected with the bones of the skeleton.
III.
Flat bones:
a) flat bones of the skull (frontal and parietal) perform mainly a protective function. They are built from 2 thin plates of a compact substance, between which there is a diploe, diploe, a spongy substance containing channels for veins. These bones develop on the basis of connective tissue (integumentary bones);
b) flat bones of the belts (scapula, pelvic bones) perform the functions of support and protection, 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. To mixed bones the clavicle can also be attributed, partly developing endosmally, partly endochondral.
7) the structure of the bone substance.
By microscopic structure bone substance is a special type of connective tissue, bone tissue, characteristics which: hard, fibrous impregnated with mineral salts intercellular substance and stellate, equipped with numerous processes, cells.
The basis of the bone is made up of collagen fibers with their soldering substance, which are impregnated with mineral salts and are formed into plates consisting of layers of longitudinal and transverse fibers; in addition, elastic fibers are also found in the bone substance.
These plates in the dense bone substance are partly located in concentric layers around the long branching channels passing in 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 to be the structural unit of the compact bone substance, the osteon.
Parallel to the surface of these plates, they contain layers of small star-shaped voids, continuing into numerous thin tubules - these are the so-called "bone bodies", in which there are bone cells that give rise to tubules. The tubules of the bone bodies are connected to each other and to the cavity of the Haversian canals, the internal cavities and the periosteum, and thus the entire bone tissue is permeated with a continuous system of cavities and tubules filled with cells and their processes, through which the nutrients necessary for bone life penetrate.
Fine 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.
The bones of the skeleton can be studied in a living person by X-ray examination. The presence of calcium salts in the bones makes the bones less "transparent" to X-rays than the soft tissues surrounding them. Due to the unequal structure of the bones, the presence in them of a more or less thick layer of compact cortex, and inside of it the spongy substance can be seen and distinguish bones on radiographs.
X-ray (X-ray) examination is based on the property of X-rays in varying degrees penetrate through body tissues.
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 a large number air is represented by an area of \u200b\u200bbright glow.
There are the following main radiological methods of research.
1. X-ray (gr.
skopeo- consider, watch) 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); organ structure is also visible.
2. Radiography (gr. grapho- write) - X-ray examination with the registration of a still image on a special x-ray film or photographic paper.
With digital radiography, the image is fixed in the computer's memory. Five types of radiography are used.
Full size radiography.
Fluorography (small format radiography) - radiography with a reduced image size obtained on a fluorescent screen (lat.
fluor- current, flow); it is used in preventive studies of the respiratory system.
Plain radiography - an image of the entire anatomical region.
Aiming radiography - an image of a limited area of \u200b\u200bthe organ under study.
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 under study.
Tomography (gr. tomos- segment, layer, layer) is a method of layer-by-layer imaging that provides an image of a tissue layer of a given thickness using an X-ray tube and a film cassette (X-ray tomography) or with the connection of special counting chambers from which electrical signals are fed to a computer (computed tomography).
Contrast fluoroscopy (or radiography) is an X-ray method of investigation based on the introduction into hollow organs (bronchi, stomach, renal pelvis and ureters, etc.) or vessels (angiography) of special (radiocontrast) substances that delay x-rays, as a result of which a clear image of the studied organs is obtained on the screen (photographic film).
10) the structure of the 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 architectonics of blood vessels and nerves, built mainly of bone tissue, covered on the outside with a 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 the bones develop and the functional loads that the 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 intraorganic architectonics of the vessels.
These features also apply to the nerves innervating this bone.
The composition of each bone includes several tissues that are in certain ratios, but, of course, lamellar bone tissue is the main one. 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 the structural and functional unit of the bone. Osteons can be seen on thin sections or histological preparations.
The internal structure of the bone: 1 - bone tissue; 2 - osteon (reconstruction); 3 - longitudinal section of the osteon
The osteon is represented by concentrically arranged bone plates (Haversian), which, in the form of cylinders of different diameters, nested in each other, surround the Haversian canal.
In the latter, blood vessels and nerves pass. 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 channel accounts for 0.2-0.3 mm2. Between the osteons are intercalary, or intermediate, plates that go in all directions.
Intercalated plates are the remaining parts of old osteons that have undergone destruction. In the bones, the processes of neoplasm and destruction of osteons are constantly taking place.
Outside bone surround several layers of general, or common, plates, which are located directly under the periosteum (periosteum).
Perforating canals (Volkmann's) pass through them, which contain blood vessels of the same name. At the border with the medullary cavity in tubular bones there is a layer of inner surrounding plates. They are permeated with 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 the bone plates, having the shape of cylinders, ossein fibrils are tightly and parallel to each other.
Between the concentrically lying bone plates of osteons are osteocytes. The processes of bone cells, spreading along the tubules, pass towards the processes of neighboring osteocytes, enter into intercellular junctions, forming a spatially oriented lacunar-tubular system involved in metabolic processes.
The osteon contains up to 20 or more concentric bone plates.
In the canal of the osteon, 1-2 vessels of the microvasculature pass, unmyelinated nerve fibers, lymphatic capillaries, accompanied by layers of loose connective tissue containing osteogenic elements, including perivascular cells and osteoblasts.
The osteon channels are interconnected, with the periosteum and the medullary cavity by perforating channels, which contributes to the anastomosis of the bone vessels as a whole.
Outside, the bone is covered with a periosteum formed by fibrous connective tissue. It distinguishes between the outer (fibrous) layer and the inner (cellular) layer.
In the latter, cambial progenitor cells (preosteoblasts) are localized. The main functions of the periosteum are protective, trophic (due to the blood vessels passing through 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, tubercles and tuberosities). The periosteum separates 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 from the periosteum penetrate 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 an important role in the development (growth in thickness) and nutrition of the bone.
Its inner osteogenic layer is the site of bone formation. The periosteum is richly innervated, therefore it is highly sensitive. The bone, deprived of the periosteum, becomes unviable, dies.
At surgical interventions on the bones for fractures, the periosteum must be preserved.
Almost all bones (with the exception of most bones of the skull) have articular surfaces for articulation with other bones.
The articular surfaces are covered not by the periosteum, but by articular cartilage (cartilage articularis). The articular cartilage in its structure is more often hyaline and less often fibrous.
Inside most bones in the cells between the plates of the spongy substance or in the medullary cavity (cavitas medullaris) is the bone marrow.
It comes in red and yellow. In fetuses and newborns, the bones contain only red (hematopoietic) bone marrow. It is a homogeneous mass of red color, rich in blood vessels, shaped elements blood and reticular tissue.
In red bone marrow also contains bone cells, osteocytes. The total amount of red bone marrow is about 1500 cm3.
In an adult, the bone marrow is partially replaced by yellow, which is mainly represented by fat cells. Only the bone marrow located within the marrow cavity is subject to replacement. It should be noted that the inside of the medullary cavity is lined with a special membrane called the endosteum.
1. Long tubular (os thigh, lower leg, shoulder, forearm).
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 processes are flat).
7. Air (upper jaw, ethmoid, wedge-shaped).
The structure of the bones .
Bone living person is a complex organ, occupies a certain position in the body, has its own shape and structure, performs its characteristic function.
Bone is made up of:
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)
Outside, the bone is covered with periosteum.
Periosteum(or periosteum) - 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 the bone in thickness and the restoration of its integrity after fractures.
The outer layer is composed of dense fibrous fibers. The periosteum is rich in blood vessels and nerves, which through thin bone tubules penetrate deep into the bone, supplying and innervating it.
Located inside the bone Bone marrow.
Bone marrow is of two types:
red bone marrow- an important organ of hematopoiesis and bone formation.
Saturated with blood vessels and blood elements. It is formed by reticular tissue, which contains hematopoietic elements (stem cells), osteoclasts (destroyers), osteoblasts.
In the prenatal period and in newborns, all bones contain red marrow.
In an adult, it is found only in the cells of the spongy substance of flat bones (sternum, skull bones, ilium), in spongy (short bones), epiphyses of tubular bones.
As blood cells mature, they enter the bloodstream and are carried throughout the body.
The yellow bone marrow is represented mainly by fat cells and degenerate cells of the reticular tissue.
Lipocytes give bone yellow. Yellow bone marrow is located in the cavity of the diaphysis of tubular bones.
Bone plates are formed from bone tissue.
If the bone plates are tightly adjacent 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.
Bone crossbars are not arranged randomly, but strictly regularly along the lines of compression and tension forces.
Osteon is the structural unit of bone.
Osteons consist of 2-20 cylindrical plates inserted one into the other, inside which a (Haversian) canal passes.
A lymphatic vessel, an artery and a vein pass through it, which branch out to capillaries and approach the lacunae of the Haversian system. They provide inflow and outflow of nutrients, metabolic products, CO2 and O2.
On the outer and inner surfaces of the bone, the bone plates do not form concentric cylinders, but are located around them.
These areas are pierced by Volkmann's canals through which blood vessels pass, which connect with the vessels of the Haversian canals.
Living bone contains 50% water, 12.5% protein organic matter (ossein and osseomucoid), 21.8% inorganic minerals (mainly calcium phosphate), and 15.7% fat.
Organic substances cause elasticity bones, and inorganic 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 the age of 18-20, and in men by the age of 23-25. From that time on, the growth of the skeleton, and hence the person, stops.
The epiphyses are built of spongy bone substance, in the cells of which there is red bone marrow. Outside, the epiphyses are covered articular hyaline cartilage.
The diaphysis consists of a compact bone substance.
Inside the diaphysis is medullary cavity It contains yellow bone marrow. Outside, 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 in the skeleton (skeletos) - from Greek, means dried.
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According to the form, function, structure and development of the bones are divided into three groups.
Human bones vary in shape and size, occupy a certain place in the body. There are the following types of bones: tubular, spongy, flat (wide), mixed and airy.
tubular bones act as levers and form the skeleton of the free part of the limbs, are divided into long (shoulder, thigh bones, bones of the forearm and lower leg) and short (metacarpal and metatarsal bones, phalanges of fingers).
In long tubular bones there are dilated ends (epiphyses) and a middle part (diaphysis).
The area between the epiphysis and the diaphysis is called metaphysis. Epiphyses, bones are completely or partially covered with hyaline cartilage and are involved in the formation of joints.
Spongy(short) bones located in those parts of the skeleton where bone strength is combined with mobility (carpal bones, tarsus, vertebrae, sesamoid bones).
flat(wide) bones participate in the formation of the skull roof, chest and pelvic cavities, perform protective function, have a large surface for muscle attachment.
mixed dice have a complex structure and various shapes.
This group of bones includes vertebrae, the bodies of which are spongy, and the processes and arches are flat.
air bones contain a cavity in the body with air, lined with a mucous membrane.
These include the upper jaw, frontal, sphenoid and ethmoid bones of the skull.
ANOTHER OPTION!!!
- By location: cranial bones; body bones; limb bones.
- By development, the following types of bones are distinguished: primary (appear from connective tissue); secondary (formed from cartilage); mixed.
- The following types of human bones are distinguished by structure: tubular; spongy; flat; mixed.
Thus, science knows different kinds bones. The table makes it possible to more clearly present this classification.
3.
Types of bones and their connections
The human skeleton contains over 200 bones. 
All bones of the skeleton are divided into four types according to their structure, origin, and functions:
Provide fast and diverse limb movements.
Spongy (long: ribs, sternum; short: bones of the wrist, tarsus) - bones, mainly consisting of a spongy substance covered with a thin layer of compact substance. They contain red bone marrow, which provides the function of hematopoiesis.
Flat (shoulder blades, skull bones) - bones, the width of which prevails over the thickness to protect the internal organs.
They consist of plates of compact substance and a thin layer of spongy substance.
Mixed - consist of several parts that have different structure, origin and functions (the vertebral body is a spongy bone, and its processes are flat bones).
Various types of bones 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 (connection of the bones of the skull roof to protect the brain).
A semi-movable connection through elastic cartilage pads is formed by bones that perform both protective and motor functions (connections of the vertebrae by intervertebral cartilage discs, ribs with the sternum and thoracic vertebrae)
Mobile (discontinuous) connection due to the joints have bones that provide 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 bag forms a sealed cavity with synovial fluid. This promotes gliding and protects the bone from abrasion.
Illustrations:
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What does arthrology study? The section of anatomy devoted to the doctrine 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 more or less mobility. Bone joints have a different structure and have such physical properties as strength, elasticity and mobility, which is 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 connections (synarthrosis) are characterized by the fact that the bones are connected by a continuous layer of connective tissue (dense connective, cartilage or bone). There is no gap or cavity between the connecting surfaces.
2. Semi-discontinuous connections (hemiarthrosis), or symphyses - this is a transitional form from continuous connections to discontinuous ones.
They are characterized by the presence in the cartilaginous layer, located between the connecting surfaces, a small gap filled with fluid.
Such compounds are characterized by low mobility.
3. Discontinuous connections (diarrhosis), 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 (synarthrosis). Continuous connections have greater elasticity, strength and, as a rule, limited mobility.
Depending on the type of connective tissue located between the articulating surfaces, there are three types of continuous connections:
Fibrous connections, or syndesmoses, are strong bone connections with the help of dense fibrous connective tissue, which fuses with the periosteum of the connecting bones and passes into it without a clear boundary.
Syndesmoses include: ligaments, membranes, sutures and driving in (Fig. 63).
Ligaments serve mainly to strengthen the joints of bones, but they 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, yellow ligaments located between the vertebral arches).
Membranes (interosseous membranes) connect adjacent bones for a considerable length, for example, they are stretched between the diaphyses of the bones of the forearm and lower leg and close some bone openings, for example, the obturator foramen of the pelvic bone.
Often, the interosseous membranes serve as the site of the beginning of the muscle.
seams- a kind of fibrous connection, in which there is a narrow connective tissue layer between the edges of the connecting bones. The connection of bones by seams is found only in the skull. Depending on the configuration of the edges, there are:
- jagged sutures (in the roof of the skull);
- scaly suture (between the scales of the temporal bone and parietal bone);
- flat sutures (in the facial skull).
Impaction is a dento-alveolar connection, 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 synchondrosis, are joints of bones with the help of cartilaginous tissue (Fig.
64). This type of connection is characterized by high strength, low mobility and elasticity due to the elastic properties of cartilage.
Synchondroses are permanent and temporary:
1.
Permanent synchondrosis is such a type a connection in which cartilage exists between the connecting bones throughout life (for example, between the pyramid of the temporal bone and the occipital bone).
2.
Temporary synchondrosis is observed in cases where the cartilage layer between the bones is preserved until certain age(for example, between the bones of the pelvis), in the future, the cartilage is replaced by bone tissue.
Bone joints, or synostoses, are the joints of bones with the help of bone tissue.
Synostoses are formed as a result of the replacement of bone tissue with other types of bone joints: syndesmoses (for example, frontal syndesmosis), synchondroses (for example, sphenoid-occipital synchondrosis) and symphyses (mandibular symphysis).
Semi-discontinuous connections (symphyses). Semi-continuous connections, or symphyses, include fibrous or cartilaginous connections, in the thickness of which there is small size cavity in the form of a narrow slit (Fig.
65), filled with synovial fluid. Such a connection is not covered by a capsule from the outside, and the inner surface of the gap is not lined with a synovial membrane.
In these joints, small displacements of the articulating bones relative to each other are possible. Symphyses are found in the sternum - the symphysis of the sternum handle, in the spinal column - the intervertebral symphyses and in the pelvis - the pubic symphysis.
Lesgaft, the formation of a particular joint is also due to the function assigned to this part of the skeleton. In the links of the skeleton, where mobility is necessary, diarthroses are formed (on the limbs); where protection is needed, synarthrosis (connection of the bones of the skull) is formed; in places experiencing a support load, continuous connections are formed, or inactive diarthrosis (joints of the pelvic bones).
Discontinuous connections (joints). Discontinuous joints, or joints, are the most perfect types of connection of bones.
They are distinguished by great mobility, a variety of movements.
Mandatory elements of the joint (Fig. 66):
1. Surface joint. At least two articular surfaces are involved in the formation of a joint. In most cases, they correspond to each other, i.e.
are congruent. If one articular surface is convex (head), then the other is concave (articular 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 cartilage smooths out the roughness of the articular surfaces, and also absorb shocks during movement. How heavy load experiences the joint under the influence of gravity, the greater the thickness of the articular cartilage.
2. The articular capsule is attached to the articulating bones near the edges of the articular surfaces. It is firmly fused with the periosteum, forming a closed articular cavity.
The joint capsule consists of two layers. The outer layer is formed by a fibrous membrane, built from dense fibrous connective tissue.
In some places, it forms thickenings - ligaments that can be located outside the capsule - extracapsular ligaments and in the thickness of the capsule - intracapsular ligaments.
Extracapsular ligaments are part of the capsule, making up with it one inseparable whole (for example, the coraco-brachial ligament). Sometimes there are more or less isolated ligaments, such as the collateral peroneal ligament of the knee joint.
Intracapsular ligaments lie in the joint cavity, moving from one bone to another.
They consist of fibrous tissue and are 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 the synovial membrane, built from loose fibrous connective tissue.
It lines the fibrous membrane from the inside and continues to the surface of the bone, 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.
Negative inside the joint cavity Atmosphere pressure, 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 articular surfaces of bones covered with cartilage 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 not completely corresponding to each other (incongruent) articular surfaces.
Disks and menisci are able to move with movement. They smooth the articulating surfaces, make them congruent, absorb shocks and shocks when moving. There are discs in the sternoclavicular and temporomandibular joints, and menisci in the knee joint.
2. articular lips located along the edge of the concave articular surface, deepening and supplementing 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.
Articular lips increase the congruence of the joints and contribute to a more even pressure of one bone on 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 the thinned places of the articular capsule, the synovial membrane forms bag-like protrusions or eversion - synovial bags, which are located around the tendons or under the muscles lying near the joint. Being filled with synovial fluid, they facilitate the friction of tendons and muscles during movement.
Name
Structure
Flat bones are formed by two thin plates of compact substance, between which is a spongy substance containing bone marrow. The spongy substance of the bones of the skull is called "diploe".
Ossification
Ossification of the flat bones of the skull is carried out on the basis of connective tissue (endesmal ossification). Ossification of the remaining flat bones is carried out on the basis of cartilaginous tissue (endochondral ossification).
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Literature
- Sapin M. R., Bryksina Z. G. - Human Anatomy. Enlightenment, 1995 ISBN 5-09-004385-X
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An excerpt characterizing Flat Bones
- No, I saw ... That was nothing, suddenly I see that he is lying.- Andrey lies? He is sick? - Natasha asked with frightened fixed eyes looking at her friend.
- No, on the contrary - on the contrary, a cheerful face, and he turned to me - and at the moment she spoke, it seemed to her that she saw what she was saying.
- Well, then, Sonya? ...
- Here I did not consider something blue and red ...
– Sonya! when will he return? When I see him! My God, how I fear for him and for myself, and for everything I am afraid ... - Natasha spoke, and without answering a word to Sonya's consolations, she lay down in bed and long after the candle was put out, with her eyes open, lay motionless on bed and looked at the frosty, moonlight through the frozen windows.
Soon after Christmas, Nikolai announced to his mother his love for Sonya and his firm decision to marry her. The countess, who had long noticed what was happening between Sonya and Nikolai, and was expecting this explanation, silently listened to his words and told her son that he could marry whomever he wanted; but that neither she nor his father would give him blessings for such a marriage. For the first time, Nikolai felt that his mother was unhappy with him, that despite all her love for him, she would not give in to him. She, coldly and without looking at her son, sent for her husband; and when he arrived, the countess wanted to briefly and coldly tell him what was the matter in the presence of Nikolai, but she could not stand it: she burst into tears of annoyance and left the room. The old count began to hesitantly admonish Nicholas and ask him to abandon his intention. Nikolai replied that he could not change his word, and his father, sighing and obviously embarrassed, very soon interrupted his speech and went to the countess. In all clashes with his son, the count did not leave the consciousness of his guilt before him for the disorder of affairs, and therefore he could not be angry with his son for refusing to marry a rich bride and for choosing Sonya without a dowry - he only on this occasion more vividly recalled that, if things had not been upset, it would be impossible for Nicholas to wish for a better wife than Sonya; and that only he, with his Mitenka and his irresistible habits, is to blame for the disorder of affairs.
Skeletal system human being consists of an average of 206 bones, most of which are symmetrical; flexible cartilage that forms the structure auricles, nose and part of the ribs, as well as covering the articular surfaces of bones and joints, and tight ligaments that hold the bones in their joints at the joints. The skeletal system (skeleton) makes up 20% of the total body weight.
Bone types
According to the shape of the bones are divided into 4 main types: long, short, flat and mixed. The shape of the bone also indicates its mechanical function.
Long bones - the bones of the limbs (except for the bones of the wrist, ankle and patella) are longer than they are wide. Each has a diaphysis (body) and two epiphyses (ends) that are usually wider than the body of the bone. These bones work as lifting mechanisms, causing the body to move as the muscles contract. Some bones, especially the bones of the lower extremities, perform important role to maintain body weight.
Short bones - the bones of the wrist and tarsus have an irregular cubic shape. They act as a kind of connecting bridge in the wrist and ankle area. The movements between these bones are limited, their main purpose is to maintain the stability of the hand and foot as a whole.
Flat bones - sternum, ribs, scapula and bones of the roof of the skull. 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 an attachment surface for a large number of muscles.
Mixed dice - dice facial skull, spine, pelvis and hip. The vertical position of the body is supported 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. Cartilages also form elastic pads between the vertebrae ( intervertebral discs). This elastic jelly-like fabric has high strength, resistance to pressure and abrasion. Articular cartilage tissue forms polished surfaces covered with a special synovial fluid (synovia) with 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 body, and strong bones legs carry almost the entire weight of the body.
The bones of the skeleton can be roughly divided into two categories: the axial skeleton (skull, spinal column, chest bones), the accessory skeleton (bones of the upper and lower limbs), 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 a source of calcium and other minerals. Blood cells are produced in the red bone marrow. Bones are made up 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. Bone-forming cells include osteocytes (from which the matrix is built), osteoblasts (build up bone tissue) and osteoclasts (destroy bone tissue). Working in dynamic balance, 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 needs of the body.
Bones are made up of two types of bone tissue. The compact tissue that forms the outer surface of the bone is the most resistant to stress. It is formed by parallel cylinders - osteons. These are the structural units of the 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 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 - a source of minerals
Bones perform not only mechanical functions - support, protection and movement. They also play an important role in the accumulation and retention of calcium and hematopoiesis.
Calcium is one of the twenty minerals, besides magnesium and zinc, that enter the body with food and play an important role in ensuring the normal functioning of the body. 99% calcium in human body are found in the bones. Thanks to calcium human bones and the teeth remain hard. This mineral is essential for normal muscle contraction, transmission of nerve impulses, and blood clotting. The optimal level of calcium in the blood is maintained by two hormones ( Thyroid 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 its accumulation in bone tissue.
Blood cells, which include erythrocytes, leukocytes, and platelets, are produced in the red bone marrow. It is found in the bones of the skull, spine, collarbones, sternum, ribs, shoulder blades, pelvis, and upper epiphyses of the femur and humerus.
Bone joints
In the skeleton, a joint is formed at the junction of two or more bones. The joints allow the bones to move. In addition, the joints support the strength of the body, as the bones are firmly held in the joints by strong connective tissue fibers called ligaments. Ligaments are both rigid and flexible at the same time.
There are three types of connections. Fibrous connections such as skull sutures preclude 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 junction is an oily fluid (synovia) 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 also varies.
A ball-and-socket joint, such as the shoulder or hip, allows movement in many directions.
A block joint, such as an elbow, knee or ankle joint, like door hinges, allows movement in only one plane.
A cylindrical joint, such as between the atlas and the 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 between the radius and the bones of the wrist, allow movement from side to side, as well as forward and backward.
The saddle joint at the base of the big finger ensures its movement in two planes.
Intracartilaginous ossification
Ossification, or ossification, is the process of bone formation during the prenatal period, infancy, childhood and adolescence. Most of the bones (except the skull and clavicles) are formed as a result of the process of intracartilaginous (enkondral) 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, the bones become longer and wider, allowing the body to grow. In adolescence, the growth process slows down, and ossification is almost complete.
Regeneration and restoration of bones
Throughout life, the shape and size of the bones do not remain constant. The shape of the bones changes as a result of mechanical influences caused by muscle tension and gravity. Self-healing of bones after fractures or cracks also occurs due to the regeneration process.
