Introduction

As you know, bones and cartilage form our skeleton. This is no secret to anyone. But questions about how many bones a person has and what their features are often throw many people into a stupor. Today I will give answers to them.

How many bones does a person have?

This is one of the first questions that arises when studying the human skeleton. And no one knows the exact answer to it. IN different times They called different numbers - sometimes 300, sometimes 360. Nowadays there is an opinion among experts that there are 206 bones in the body of an adult. Precisely an adult, because in children infancy There are about 300 cartilages, the ossification of which ends at 20-25 years. Therefore, the answer to the question of how many bones a person has directly depends on the number of years he has lived.

What is the structure of human bones?

Bones are long (tubular), short and wide (or flat). Long bones have a cavity inside that is filled with yellow bone marrow. Due to their tubular structure, such bones are light and strong. The bone is covered on top by a thin connective tissue membrane, the periosteum, behind which is the wall of the tubular bone itself. It is made up of dense tissue called the compact substance. The main structural unit of the latter is the osteon; its structure includes bone plates in the amount of 5-20 pieces. In the center of the osteon there is a canal through which blood vessels.

At the ends tubular bones the compact substance passes into porous tissue - spongy substance, which forms the head of the bone. The bone plates of the cancellous substance are located in those directions in which the bones are exposed greatest stretch or compression. In the spaces between the spongy scales there is red bone marrow. It consists of hematopoietic stem cells, from which all forms of blood cells begin to develop.

Short and wide bones consist mainly of spongy substance.

Bone connections

There are three types of bone connections:

1. Fixed (seam).
2. Semi-mobile.
3. Movable (joint).

There are three types of movable ones:

• single-axis;
• two-axis;
• three-axis.

Bones can be connected using cartilage. All of them make up the musculoskeletal system of the body.

Structure of the human skeleton

It's easier to tell with a table:

Functions

Bones play an important role in shaping growth and posture. It doesn’t matter how many bones a person has, what matters is their overall structure - the skeleton. Because thanks to him we can move. The bones themselves play an important role for circulatory system, because they contain red bone marrow. Bones need to be protected - due to careless behavior they often break.

Find out how they are formed
and what are our bones made of?

Bones are living tissue, they are constantly in a state of updating. Bones form the basis of the skeleton, they are responsible for movement and contain bone marrow and vital minerals.

Bones are the rigid tissues of the body that form the basis human body. These tissues are living, they are constantly renewed and formed in the process of growth and resorption.

Bone tissue

Bone consists of calcified tissue that contains bone cells. Bone tissue is composed of flexible collagen fibers containing crystals of hydroxyapatite (calcium salt) and contains three main types of bone cells

• Osteoblasts are cells responsible for bone formation.
• Osteoclasts are cells that destroy bone tissue.
• Osteocytes are fully formed cells.

Forming and destroying bone cells ensure a constant circulation bone tissue throughout life.

Skeletal support

Joined together at joints by ligaments and driven by muscles, bones are essential for movement. The complex arrangement of bones creates a skeleton that protects soft, fragile parts of the body and allows flexibility in movement. Bones contain bone marrow, a soft, fatty substance that produces most of the body's blood cells. Bones also act as a storehouse for calcium and phosphorus, which are essential for many processes in the body.

Bone formation

Bone formation begins in the embryo and continues throughout the first twenty years of life. Development occurs from several ossification centers, and when they are completely ossified, no further elongation occurs.

The skeleton is made up of many different bones, from the flat bones present in the skull to the long tubular bones in the limbs. Each bone is designed for a different function.

Long tubular bones

The longest bones of the body are the bones of the upper and lower extremities.
Each long bone has three main components:

• The diaphysis is a tubular body consisting of a compact substance.
• Epiphysis - the end of each bone; place of bone articulation.
• Epiphyseal plate (growth plate) - consists of cancellous bone and a bone elongation plate.

Periosteum

The entire bone is covered with a two-layer periosteum. Its outer layer consists of fibrous connective tissue. The inner layer of the periosteum contains osteoblasts and osteoclasts - cells responsible for constant bone renewal.

Bone development

Skeletal development begins in the embryo and continues for two decades. This complex process, occurring under genetic control and regulated by endocrine, physical and biological processes.

The skeletal template is formed in the embryo from the simplest germ tissue. As the embryo develops, this tissue takes on the recognizable appearance of cartilage and individual “bones” begin to be visible.

Ossification

Ossification occurs both directly around the first bone-forming cells of the fetus, and as a result of the replacement of the cartilaginous model with bones.

The formation of compact tissue begins at the sites of bone primary ossification centers. Osteoblasts located in cartilage secrete a gelatinous substance (osteoid), which hardens under the influence of mineral salts, forms bone. The cartilage cells die and are replaced by new osteoblasts.

Ossification long bones continues until only thin strips of cartilage remain at both ends. These cartilages (epiphyseal plates) are the site of growth secondary bone until the end of adolescence.

The sequence of formation of ossification centers occurs according to the scheme described above, which makes it possible to determine the age of skeletons by the degree of ossification.

Formed bone

When the bone reaches full length, ossification of the shaft, growth plate, and epiphyses occurs. They fuse and form homogeneous bone. After this, bone lengthening no longer occurs.

Human bones begin to form in the womb, but at first they are very soft. This is explained by the fact that the bulk of their mass is connective tissue. Bone growth stops and the skeleton is completely formed - around the age of 22 years.

In total, in the skeleton of an adult there are more than two hundred bones (surprisingly, the skeleton of a newborn consists of more than two hundred and seventy!), which differ from each other not only in shape, but also in content. In addition, each of them performs its own strictly defined function.

So, bones are divided into three groups: short, wide or flat, long, which are also called tubular. Let's talk separately about each group.

Wide bones do not have cavities inside. They are the strongest. Such bones in some cases create protection for internal organs and have a curved shape, for example, the skull.

Bones that resemble a pipe in cross section are called tubular, long. Their internal cavity contains bone marrow. Due to the fact that the bone is empty inside, it is quite light, but this does not negatively affect its strength. Tubular or long bones have a cylindrical shape along their main length, closer to the ends they widen somewhat, and at the ends they are completely spherical. For example: tubular bones are the bones of the upper and lower extremities.

Short bones, on the contrary, do not have internal cavities, however, despite this, they are less durable than tubular ones. These bones in the human skeleton are represented, for example, by vertebrae. Some bones of the wrist, as well as the heel of the foot, also belong to the group of short bones.

Despite different functions or shapes, the presence of cavities or their absence, bones have the same structure. All bones consist of three layers, which resemble the annual rings of tree trunks. The top layer is dense bone tissue (periosteum, inside which there are nerves and blood vessels). The next layer is a dense substance. It provides bones with strength. The third layer of bone consists of spongy bone. Outwardly, it is indeed very similar to an ordinary foam sponge (thin channels penetrate its entire plane).

Tubular bones have a thicker layer of dense bone substance than short and wide bones, which mostly have spongy tissue.

The skeleton bears the bulk of the human body, so it is not superfluous to recall that calcium and phosphorus strengthen bones, and their lack in the body inevitably leads to their fragility and fragility. Proper nutrition and consumption of foods with sufficient calcium and phosphorus content will help avoid these problems. Do not forget that excessive amounts can also have a negative effect on the condition of bones. physical activity. Keep in mind that neglect of your health in youth can cause serious illnesses musculoskeletal system in adulthood. In addition, over the years, bones become weaker.

What composition does a human bone have, their name in certain parts of the skeleton and other information you will learn from the materials of the presented article. In addition, we will tell you how they are connected to each other and what function they perform.

General information

The presented organ of the human body consists of several tissues. The most important of them is bone. So, let's look together at the composition of human bones and their physical properties.

Consists of two main chemicals: organic (ossein) - about 1/3 and inorganic (calcium salts, phosphate of lime) - about 2/3. If such an organ is exposed to a solution of acids (for example, nitric, hydrochloric, etc.), then the lime salts will quickly dissolve, and ossein will remain. It will also retain the shape of the bone. However, it will become more elastic and soft.

If the bone is burned well, it will burn, but inorganic ones, on the contrary, will remain. They will maintain the shape of the skeleton and its hardness. Although, in this case, human bones (photo presented in this article) will become very fragile. Scientists have proven that the elasticity of this organ depends on the ossein it contains, and its hardness and elasticity depend on mineral salts.

Features of human bones

Combination of organic and non organic matter makes human bone unusually strong and elastic. They are also fully convinced of this age-related changes. After all, young children have much more ossein than adults. In this regard, their bones are particularly flexible, and therefore rarely break. As for old people, the ratio of inorganic and organic substances changes in favor of the former. This is why the bone of an elderly person becomes more fragile and less elastic. As a result, old people experience a lot of fractures even with minor injuries.

Human bone anatomy

The structural unit of an organ, which is visible at low magnification of a microscope or through a magnifying glass, is a peculiar system bone plates, located concentrically around a central canal through which nerves and blood vessels pass.

It should be especially noted that the osteons do not adhere closely to each other. Between them there are spaces that are filled with bone interstitial plates. In this case, osteons are not arranged randomly. They fully correspond to the functional load. Thus, in tubular bones osteons are parallel to the length of the bone, in spongy bones they are perpendicular to the vertical axis. And in flat ones (for example, in the skull) - its surfaces are parallel or radial.

What layers do human bones have?

Osteons, together with interstitial plates, form the main middle layer of bone tissue. From the inside it is completely covered with an inner layer of bone plates, and on the outside - by the surrounding one. It should be noted that the entire last layer is penetrated by blood vessels that come from the periosteum through special channels. By the way, larger skeletal elements, visible to the naked eye on an x-ray or on a cut, also consist of osteons.

So, let's look at the physical properties of all bone layers:

• The first layer is strong bone tissue.
• The second is connective, which covers the bone from the outside.
• The third layer is loose connective tissue that serves as a kind of “clothing” for the blood vessels that approach the bone.
• The fourth is that covering the ends of the bones. It is in this place that these organs increase their growth.
• The fifth layer consists of nerve endings. In case of problems of this element receptors send a kind of signal to the brain.

The human bone, or rather its entire internal space, is filled with yellow). Red is directly related to bone formation and hematopoiesis. As you know, it is completely permeated with vessels and nerves that nourish not only itself, but also all the internal layers of the organ represented. Yellow bone marrow promotes skeletal growth and strengthening.

What are the different shapes of bones?

Depending on location and functions, they can be:

• Long or tubular. Such elements have a middle cylindrical part with a cavity inside and two wide ends, which are covered with a thick layer of cartilage (for example, human leg bones).
• Wide. These are the pectoral and pelvic bones, as well as the bones of the skull.
• Short. Such elements are distinguished by irregular, multifaceted and rounded shapes (for example, wrist bones, vertebrae, etc.).

How are they connected?

The human skeleton (we will look at the names of the bones below) is a set of individual bones that are connected to each other. This or that order of these elements depends on their direct functions. There are discontinuous and continuous connections of human bones. Let's look at them in more detail.

Continuous connections. These include:

• Fibrous. The bones of the human body are connected to each other using a lining of dense connective tissue.
• Bony (that is, the bone is completely fused).
• Cartilaginous (intervertebral discs).

Intermittent connections. These include synovial, that is, between the articulating parts there is an articular cavity. Bones are held in place by a closed capsule and supporting muscle tissue and ligaments.

Thanks to these features, the arms, bones of the lower extremities and the torso as a whole are capable of moving the human body. However motor activity people depends not only on the compounds presented, but also on the nerve endings and bone marrow that are contained in the cavity of these organs.

Skeletal functions

In addition to mechanical functions that maintain shape human body, the skeleton provides the ability to move and protect internal organs. In addition, it is a site of hematopoiesis. So, in bone marrow new blood cells are formed.

Among other things, the skeleton is a kind of repository for most of the body's phosphorus and calcium. That's why he plays vital role in exchange minerals.

Human skeleton with bones name

The adult human skeleton consists of approximately 200-odd elements. Moreover, each part of it (head, arms, legs, etc.) includes several types of bones. It should be noted that their name and physical features vary significantly.

Head bones

The human skull consists of 29 parts. Moreover, each section of the head includes only certain bones:

1. Brain department, consisting of eight elements:

2. The facial region consists of fifteen bones:

• palatine bone (2 pcs.);
• vomer;
• (2 pcs.);
• upper jaw (2 pcs.);
• nasal bone (2 pcs.);
• lower jaw;
• lacrimal bone (2 pcs.);
• lower turbinate(2 pcs.);
• hyoid bone.

3. Middle ear bones:

• hammer (2 pcs.);
• anvil (2 pcs.);
• stirrup (2 pcs.).

Torso

Human bones, the names of which almost always correspond to their location or appearance, are the easiest organs to study. So, various fractures or other pathologies are quickly identified using a diagnostic method such as radiography. It should be especially noted that some of the largest human bones are the bones of the torso. These include all spinal column, which consists of 32-34 individual vertebrae. Depending on the functions and location they are divided into:

• thoracic vertebrae (12 pcs.);
• cervical (7 pieces), including epistropheus and atlas;
• lumbar (5 pcs.).

In addition, the bones of the body include the sacrum, coccyx, rib cage, ribs (12 × 2) and sternum.

All of the above skeletal elements are designed to protect internal organs from possible external influence(bruises, blows, punctures, etc.). It should also be noted that in case of fractures, the sharp ends of the bones can easily damage soft fabrics body, which will entail severe internal hemorrhage, most often leading to fatal outcome. In addition, the fusion of such organs requires much more time than for those located in the lower or upper extremities.

Upper limbs

The bones of the human hand include the most large number small elements. Thanks to this skeleton of the upper limbs, people are able to create household items, use them, etc. Like the spinal column, the human arms are also divided into several sections:

• Shoulder - humerus(2 pieces).
• Forearm - ulna (2 pieces) and radius(2 pieces).
• Brush that includes:
  - wrist (8 × 2), consisting of the scaphoid, lunate, triquetrum and pisiform bones, as well as the trapezium, trapezoid, capitate and hamate;
  - metacarpus, consisting of metacarpal bone(5 × 2);
  - finger bones (14 × 2), consisting of three phalanges (proximal, middle and distal) in each finger (except the thumb, which has 2 phalanges).

All the human bones presented, the names of which are quite difficult to remember, allow you to develop hand motor skills and perform simple movements that are extremely necessary in everyday life.

It should be especially noted that the constituent elements of the upper extremities are most often subject to fractures and other injuries. However, such bones also grow together faster than others.

Lower limbs

The bones of the human leg also include a large number of small elements. Depending on their location and functions, they are divided into the following departments:

• Belt lower limb. This includes pelvic bone, which consists of the ischium and pubis.
• The free part of the lower limb, consisting of the thighs ( femur- 2 pieces; patella - 2 pieces).
• Shin. Consists of tibia(2 pieces) and fibula (2 pieces).
• Foot.
• Tarsus (7 × 2). It consists of two bones each: calcaneus, talus, navicular, medial sphenoid, intermediate sphenoid, lateral sphenoid, cuboid.
• Metatarsus, consisting of metatarsal bones(5 × 2).
• Finger bones (14 × 2). Let's list them: middle phalanx(4 × 2), proximal phalanx (5 × 2) and distal phalanx (5 × 2).

The most common bone disease

Experts have long established that it is osteoporosis. It is this deviation that most often causes sudden fractures, as well as pain. Unofficial name the disease presented sounds like a “silent thief.” This is due to the fact that the disease proceeds unnoticed and extremely slowly. Calcium is gradually washed out of the bones, which entails a decrease in their density. By the way, osteoporosis often occurs in old age or adulthood.

Aging bones

As mentioned above, in old age the human skeletal system undergoes significant changes. On the one hand, bone loss begins and the number of bone plates decreases (which leads to the development of osteoporosis), and on the other hand, excess formations in the form bone growths(or so-called osteophytes). Calcification of articular ligaments, tendons and cartilage also occurs at the site of their attachment to these organs.

Aging of the osteoarticular apparatus can be determined not only by the symptoms of the pathology, but thanks to this diagnostic method, like radiography.

What changes occur as a result of bone substance atrophy? Such pathological conditions include:

• Deformation of the articular heads (or the so-called disappearance of their rounded shape, grinding of the edges and the appearance of corresponding angles).
• Osteoporosis. When examined on an x-ray, the bone of a sick person looks more transparent than that of a healthy person.

It should also be noted that patients often exhibit changes in bone joints due to excessive deposition of lime in the adjacent cartilaginous and connective tissue tissues. As a rule, such deviations are accompanied by:

• Narrowing of the articular x-ray gap. This occurs due to calcification of the articular cartilage.
• Strengthening the relief of the diaphysis. This pathological condition accompanied by calcification of the tendons at the site of bone attachment.
• Bone growths, or osteophytes. This disease is formed due to calcification of the ligaments at the site of their attachment to the bone. It should be especially noted that such changes are especially well identified in the hand and spine. In the remaining parts of the skeleton, 3 main ones can be traced X-ray sign aging. These include osteoporosis, narrowing of joint spaces and increased bone relief.

For some people, these symptoms of aging may appear early (around 30-45 years old), while for others they may appear late (around 65-70 years old) or not appear at all. All the changes described are completely logical normal manifestations of the activity of the skeletal system in older age.

• Few people know, but the hyoid bone is the only bone in the human body that is in no way connected to the others. Topographically, it is located on the neck. However, traditionally it is classified as facial area skulls Thus, the hyoid element of the skeleton is suspended from its bones with the help of muscle tissue and connected to the larynx.
• The longest and strong bone skeleton is the femur.
• The smallest bone in the human skeleton is located in the middle ear.

The skeleton of any adult human includes 206 different bones, all of them different in structure and role. At first glance, they appear hard, inflexible and lifeless. But this is a mistaken impression; various things are constantly happening in them. metabolic processes, destruction and regeneration. They, together with muscles and ligaments, form special system which is called " musculoskeletal tissue", the main function of which is musculoskeletal. It is formed from several types of special cells that differ in structure, functional features and meaning. Bone cells, their structure and functions will be discussed further.

The structure of bone tissue

Features of lamellar bone tissue

It is formed by bone plates having a thickness of 4-15 microns. They, in turn, consist of three components: osteocytes, ground substance and collagen thin fibers. All bones of an adult are formed from this tissue. The collagen fibers of the first type lie parallel to each other and are oriented in a certain direction, while in neighboring bone plates they are directed in the opposite direction and intersect almost at a right angle. Between them are the bodies of osteocytes in the lacunae. This structure of bone tissue provides it with the greatest strength.

Cancellous bone

The name "trabecular substance" is also found. If we draw an analogy, the structure is comparable to an ordinary sponge, built from bone plates with cells between them. They are arranged in an orderly manner, in accordance with the distributed functional load. The epiphyses of long bones are mainly built from spongy substance, some are mixed and flat, and all are short. It can be seen that these are mainly light and at the same time strong parts of the human skeleton that experience loads in various directions. The functions of bone tissue are directly related to its structure, which in this case provides a large area for metabolic processes carried out on it, gives high strength combined with low weight.

Dense (compact) bone substance: what is it?

The diaphyses of the tubular bones consist of a compact substance; in addition, it covers their epiphyses from the outside with a thin plate. It is pierced by narrow channels, through which nerve fibers and blood vessels pass. Some of them are located parallel to the bone surface (central or Haversian). Others exit onto the surface of the bone (nutrient openings), through which arteries and nerves penetrate inward, and veins penetrate outward. The central canal, together with the bone plates surrounding it, forms the so-called Haversian system (osteon). This is the main content of the compact substance and they are considered as its morphofunctional unit.

Osteon is a structural unit of bone tissue

Its second name is the Haversian system. This is a collection of bone plates that look like cylinders inserted into each other, the space between them is filled by osteocytes. In the center is the Haversian canal, through which the blood vessels that ensure metabolism in bone cells pass. Between adjacent structural units there are intercalary (interstitial) plates. In fact, they are the remnants of osteons that existed previously and were destroyed at the moment when the bone tissue underwent restructuring. There are also general and surrounding plates; they form the innermost and outer layers of the compact bone substance, respectively.

Periosteum: structure and significance

Based on the name, we can determine that it covers the outside of the bones. It is attached to them with the help of collagen fibers, collected in thick bundles, which penetrate and intertwine with the outer layer of bone plates. It has two distinct layers:

• external (it is formed by dense fibrous, unformed connective tissue, it is dominated by fibers located parallel to the surface of the bone);
• the inner layer is well defined in children and less noticeable in adults (formed by loose fibrous connective tissue, in which there are spindle-shaped flat cells - inactive osteoblasts and their precursors).

The periosteum performs several important functions. Firstly, trophic, that is, it provides the bone with nutrition, since it contains vessels on the surface that penetrate inside along with the nerves through special nutrient openings. These channels feed the bone marrow. Secondly, regenerative. It is explained by the presence of osteogenic cells, which, when stimulated, transform into active osteoblasts that produce matrix and cause the growth of bone tissue, ensuring its regeneration. Thirdly, the mechanical or support function. That is, ensuring the mechanical connection of the bone with other structures attached to it (tendons, muscles and ligaments).

Functions of bone tissue

Among the main functions are the following:

1. Motor, support (biomechanical).
2. Protective. Bones protect the brain, blood vessels and nerves, internal organs, etc. from damage.
3. Hematopoietic: hemo- and lymphopoiesis occurs in the bone marrow.
4. Metabolic function (participation in metabolism).
5. Reparative and regenerative, consisting in the restoration and regeneration of bone tissue.
6. Morph-forming role.
7. Bone tissue is a kind of depot of minerals and growth factors.