They are flat bones in structure. Classification of bones

06.11.2019 -

Morphology, physiology and pathophysiology of the musculoskeletal system.

Movement plays huge role in living nature and is one of the main adaptive reactions to the environment external environment and a necessary factor in human development. Human movement in space is carried out thanks to the musculoskeletal system.

The musculoskeletal system is made up of bones, their joints and striated muscles.

Bones and their connections are the passive part of the musculoskeletal system, and 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, connected to each other using connective tissue of different structures.

Skeletal functions .

The skeleton performs mechanical and biological functions.

To mechanical functions skeletons include:

· protection,

· movement.

The bones of the skeleton form cavities (spinal canal, skull, thoracic, abdominal, pelvic) that protect the internal organs located in them from external influences.

Support is provided by attaching muscles and ligaments to various parts of the skeleton, as well as maintaining internal organs.

Movement is possible in places of movable bone connections - in joints. They are driven by muscles under the control of the nervous system.

To biological functions skeletons include:

· participation of bones in metabolism, especially in mineral metabolism - it is a depot of mineral salts (phosphorus, calcium, iron, etc.)

· participation of bones in hematopoiesis. The function of hematopoiesis is performed by red bone marrow contained in spongy bones.

Mechanical and biological functions mutually influence each other.

Each bone occupies a specific position in the human body and has its own anatomical structure and performs its inherent functions.

Bone consists of several types of tissues, the main place of which is occupied by hard 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.

Chemical composition of bone. Bone consists of 1/3 organic (ossein, etc.) and 2/3 inorganic (calcium salts, especially phosphates) substances. Under the influence of acids (hydrochloric, nitric, etc.), calcium salts dissolve, and the bone with the remaining organic substances will retain its shape, but will become soft and elastic. If you burn a bone, the organic substances will burn out, but the inorganic substances will remain. The bone will also retain its shape, but it will become very fragile. It follows that the elasticity of the bone depends on ossein, and mineral salts give it hardness.

IN childhood bones contain more organic matter, so children's bones are more flexible and rarely break. In older people chemical composition Inorganic substances predominate in the bones, the bones become less elastic and more fragile, and therefore break more often.

Classification of bones. According to the classification of M.G. Gain, bones are: tubular, spongy, flat and mixed.

Tubular bones They 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. ends tubular bones are called epiphyses. The cells of spongy tissue contain red bone marrow. Between the diaphysis and epiphyses are the metaphyses, which are areas of bone growth in length.

Spongy bones distinguish between long (ribs and sternum) and short (vertebrae, carpal bones, tarsus).

They are constructed of a spongy substance covered with a thin layer of compact. Spongy bones include sesamoid bones (patella, pisiform bone, sesamoid bones of the fingers and toes). They develop in muscle tendons and are auxiliary devices for their work.

Flat Bones, forming the roof of the skull, built from two thin plates of a 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 serve as 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 connections can be divided into 2 groups:

1) continuous connections - synarthrosis (immobile or sedentary);

2) discontinuous joints - diarthrosis or joints (mobile by 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 are synarthrosis.

There are 3 types of synarthrosis:

1) Syndesmosis – connection of bones using ligaments (ligaments, membranes, sutures). Example: skull bones.

2) Synchondrosis - connection of bones using cartilage tissue (temporary and permanent). The cartilage tissue located between the bones acts as a buffer, softening shocks and shocks. Example: vertebrae, first rib and vertebra.

3) Synostosis – connection of bones through bone tissue. Example: pelvic bones.

Discontinuous joints, 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 bones, is smooth and elastic, which reduces friction and softens shocks. The 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 is correspondingly concave, forming the articular cavity.

The joint capsule is attached to the bones that form the joint. Hermetically closes the joint cavity. It consists of two membranes: outer fibrous and inner synovial. The latter secretes a clear 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 inversions of the synovial membrane are formed - synovial bursae lying near the joint, at the junction of tendons or muscles. Synovial bursae contain synovial fluid and reduce friction of tendons and muscles during movement.

The articular cavity is a hermetically sealed, slit-like space between the articular surfaces. Synovial fluid creates a pressure in the joint below atmospheric pressure, which prevents the divergence of the articular surfaces. In addition, synovia is involved in fluid exchange and strengthening of the joint.

Question 3. The structure of the skeleton of the head, torso and limbs.

The skeleton has the following parts:

1. axial skeleton

· skeleton of the body (vertebrae, ribs, sternum)

· the skeleton of the head (bones of the skull and face) form;

2. extra skeleton

bones of limb girdles

Upper (scapula, collarbone)

Lower (pelvic bone)

bones of free limbs

Upper (shoulder, forearm and hand bones)

Lower (thigh, leg bones and foot).

Spinal column is part of the axial skeleton, performs supporting, protective and locomotor functions: ligaments and muscles are attached to it, protects the spinal cord located in its canal and participates in the movements of the torso and skull. The spinal column is S-shaped due to human upright posture.

The spinal column has the following departments : cervical, consisting of 7, thoracic - of 12, lumbar - of 5, sacral - of 5 and coccygeal - of 1-5 vertebrae. The size of the vertebral bodies gradually increases from top to bottom, reaching its greatest size at the lumbar vertebrae; The 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 the remnants of the disappeared tail in humans.

Where the spine experiences the greatest functional load, the vertebrae and their individual parts are well developed. The coccygeal spine does not bear any functional load and is therefore a rudimentary formation.

The spinal column in the human skeleton is located vertically, but not straight, but forms bends in the sagittal plane. Bends in the cervical and lumbar regions directed forward and are called lordoses , and in the thoracic and sacral - convexly facing backward - this is kyphosis . The curves of the spine form after the birth of a child and become permanent by the age of 7-8 years.

When the load increases, the curves of the spinal column increase; when the load decreases, they become smaller.

The curves 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 shocks.

If the indicated bends of the spinal column in the sagittal plane are normal, then the appearance of bends in the frontal plane (usually in the cervical and thoracic regions) is considered a pathology and is called scoliosis . The causes of scoliosis can be different. Thus, schoolchildren may develop a pronounced lateral curvature of the spinal column - school scoliosis, as a result of improper sitting or carrying a load (bag) in one hand. Scoliosis can develop not only in schoolchildren, but also in adults in certain professions associated with curvature of the torso during work. To prevent scoliosis, special gymnastics is necessary.

In old age spinal column becomes shorter due to a decrease in thickness intervertebral discs, the vertebrae themselves and loss of elasticity. The spinal column bends anteriorly, forming one large thoracic curve (senile hump).

The spinal column is a fairly mobile formation. Thanks to intervertebral discs and it is flexible and elastic to the ligaments. Cartilage pushes the vertebrae away from each other, and ligaments connect them to each other.

chest form 12 thoracic vertebrae, 12 pairs of ribs and the sternum.

Sternum consists of three parts: the manubrium, the body and the xiphoid process. The 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 connect with the bodies of the thoracic vertebrae. The 7 upper pairs of ribs, with their anterior ends, connect 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 ribs . The XI and XII pairs of ribs are located freely in the abdominal muscles - this is oscillating ribs .

Rib cage has the shape of a truncated cone, the upper end of which is narrow and the lower end 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 right and left costal arches of the sternum converge, limiting the substernal angle, the magnitude of which depends on the shape chest.

Shape and size chest depends on: age, gender, physique, degree of development of muscles and lungs, lifestyle and profession this person. Vital cells are located in the chest important organs- heart, lungs, etc.

There are 3 chest shapes : flat, cylindrical and conical.

In people with well-developed muscles and lungs, a brachymorphic body type, the chest becomes wide, but short and acquires conical shape. She seems to be in a state of inhalation all the time. The substernal angle of such a chest will be obtuse.

In people with a dolichomorphic body type, with poorly developed muscles and lungs, the chest becomes narrow and long. This chest shape is called flat. Its front wall is almost vertical, the ribs are strongly inclined. The chest is in a state of exhalation.

In humans, brachymorphic?? (meso) body type the 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. During the process of growth and development, social factors influence the shape of the chest.

Poor living conditions and poor nutrition in children can have a significant impact on the shape of the chest. Children growing up with a lack of nutrition and solar radiation develop rickets (“English disease”), in which the chest takes on the shape of a “chicken breast.” The anteroposterior size predominates in it, and the sternum protrudes forward. In children with incorrect sitting posture, the chest is long and flat. The muscles are poorly developed. The chest seems to be 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, sufficient lighting and other conditions.

Scull (cranium) is a container for the brain and sensory organs associated with the latter; in addition, it surrounds the initial sections of the digestive and respiratory tracts. In this regard, the skull is divided into 2 parts: the brain and the facial. Brain skull has a vault and a base.

Brain section of the skull in humans they form: unpaired - occipital, sphenoid, frontal and ethmoid bones and paired - temporal and parietal bones.

Facial part of the skull form pairs - 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, the cerebral part of the skull is relatively larger than the facial part. As a result, the facial skull protrudes slightly forward compared to the brain skull and makes up only an eighth of the latter, while in an adult this ratio is 1:4. Between the bones that form the cranial vault are the fontanelles. The fontanelles are the remains of the membranous skull; they are located at the intersection of the sutures. The fontanelles are of great functional importance. The bones of the cranial vault can overlap each other during childbirth, adapting to the shape and size of the birth canal.

The sphenoid and mastoid fontanels close either at the time of birth or immediately after birth. Newborns have no stitches. Bones have smooth surfaces. There is cartilaginous tissue between the individual parts of the bones of the base of the skull that have not yet fused. There are no air sinuses in the bones of the skull. 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: the belts and the free upper and lower limbs. By means of 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 - the 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.

Pastern (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 thumb, having only two phalanges.

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 forearm bones, femur and leg bones), 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 from 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 include the clavicle, which develops partly endesmally and partly endochondrally.

BONE STRUCTURE IN X-RAY
IMAGE

X-ray examination skeleton reveals directly on a living object simultaneously both external and internal structure bones. 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 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 on an x-ray the bone becomes more transparent; 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 of 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, which lie 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 total number The number of human vertebrae is 30-35, most often 33. The ribs in humans develop in the thoracic region, while in the remaining sections the ribs remain in a rudimentary form, merging with the vertebrae.

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

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 plays the role of an axial skeleton, which is the support of the body and the protection of what is in its canal spinal cord and participates in the movements of the torso and skull.

General properties 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 departments 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.

Important part musculoskeletal system a human is a skeleton consisting of more than two hundred different bones. It allows people to move and supports internal organs. In addition, they are a concentration minerals, as well as the membrane that contains the 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. IN bone marrow blood cells are born: 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 make movements 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 includes 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, the main one is a dense compact substance. Such a bone consists of many cylindrical plates placed one inside the other. Spongy substance appearance resembles a honeycomb. 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, which 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 they distinguish the following types bones:

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 substances. 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. Pictures

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 structure 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 are evolving in various ways and perform those functions that are necessary in a particular area of the human skeleton. Types of bones such as mixed bones are found in the body temporal bone, 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

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

Negatively affects bone health long stay in bed, sedentary lifestyle. 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

IN different periods Throughout 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.

How younger man, the more organic substances are contained in the tissues of his bones. Therefore in 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.

Tubular bones They 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 the tubular bones are called epiphyses. The cells of spongy tissue contain red bone marrow. Between the diaphysis and epiphyses are the metaphyses, which are areas of bone growth in length.

Spongy bones distinguish between long (ribs and sternum) and short (vertebrae, carpal bones, tarsus).

Flat Bones , forming the roof of the skull, built from two thin plates of a compact substance, between which there is a spongy substance, diploe, containing cavities for veins; the flat bones of the belts are built of spongy substance (scapula, pelvic bones). Flat bones serve as 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 connections can be divided into 2 groups:

continuous connections - synarthrosis (immobile or sedentary);

discontinuous joints - diarthrosis or joints (mobile according to function).

Continuous connections are synarthrosis.

There are 3 types of synarthrosis:

Syndesmosis is the joining of bones using ligaments (ligaments, membranes, sutures). Example: skull bones.

Synchondrosis is a connection of bones using cartilage tissue (temporary and permanent). The cartilage tissue located between the bones acts as a buffer, softening shocks and shocks. Example: vertebrae, first rib and vertebra.

Synostosis is the joining of bones through bone tissue. Example: pelvic bones.

Discontinuous joints, 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 are smooth and elastic, which reduces friction and softens shocks. The 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 is correspondingly concave, forming the articular cavity.

Skeletal system The human body 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 at the joints where they connect. 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, perform important role to maintain 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 an attachment surface large quantity 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 body, and strong bones legs carry almost the entire weight of the body.

The bones of the skeletal system can be divided into two categories: the axial skeleton (skull, spinal column, chest bones), the 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% of 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% calcium in human body are contained precisely in the bones. Thanks to calcium human bones and the teeth remain hard. This mineral is necessary for normal muscle contraction, transmission nerve impulses and blood clotting. The optimal level of calcium in the blood is maintained by two hormones ( 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 its accumulation 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, for example 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.