Types of bones. Human Anatomy: Bones

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

Skeleton Functions

The various types of bones that make up the human skeleton are primarily used as a means of supporting and supporting the body. Some of them serve as a receptacle for certain internal organs, for example the brain located in the bones of the skull, lungs and heart located in the chest, and others.

The ability to make different movements and move we also owe our own skeleton. In addition, human bones contain up to 99% of calcium in the body. Great value in the life of a person has a red bone marrow. It is located in the skull, spine, sternum, clavicles and some other bones. Blood cells originate in the bone marrow: erythrocytes, platelets and leukocytes.

Structure of the bone

Anatomy of the bone has extraordinary properties that determine its strength. The skeleton should withstand a load of 60-70 kg - this is the average person weight. In addition, the bones of the trunk and extremities work as levers, allowing us to make movements and perform various actions. This is achieved due to their surprising composition.

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

Human bones are permeated with special tubules, along which blood vessels flow. 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 those areas where resistance to high loads is required, the main is a dense compact substance. Such a bone consists of a set of cylindrical plates placed one into another. Spongy substance resembles bees' honeycombs in appearance. In its cavities is the red bone marrow, and in adults - also yellow, in which fat cells are concentrated. The bone is covered by a special connective tissue membrane - the periosteum. It is permeated with nerves and blood vessels.

Classification of bones

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

1. By Location:

• Cranial bones;
• Bones of the trunk;
• Bones of the extremities.

2. Development of the following types of bones:

• Primary (appear from connective tissue);
• Secondary (formed from cartilage);
• Mixed.

3. There are the following types of human bones in structure:

• Tubular;
• Spongy;
• Flat;
• Mixed.

Thus, science knows the different types of bones. The table provides an opportunity to more clearly present this classification.

Tubular bones

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

At the ends of the tubular bone is the epiphysis - this is the area formed by the spongy substance. Inside it is placed a red bone marrow. The section between the diaphysis and the epiphysis is called a metaphysis.

In the period of active growth of children and adolescents, cartilage is located in it, due to which the bone grows. Over time, the anatomy of the bone changes, the metaphysis completely turns into bone tissue. The long tubular bones include the thigh, shoulder, and bones of the forearm. A slightly different structure has tubular small bones. They have only one true epiphysis and, accordingly, one metaphysis. To such bones belong the phalanx of the fingers, the bones of the metatarsus. They perform the function of short levers of movement.

Spongiform types of bones. Pictures

The name of the bones often indicates their structure. For example, spongy bones are formed from a 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, sternum and ribs. Short spongy bones are involved in the work of muscles and are a kind of auxiliary mechanism. These include the bones of the wrist, vertebrae.

Flat Bones

These types of human bones, depending on their location, have different structures and perform certain functions. The skull bones are, first of all, a defense for the brain. They are formed by two thin plates of dense material, between which is spongy. There are holes for veins in it. Flat skull bones develop from connective tissue. The scapula and pelvic bones also belong to the type of flat bones. They are formed almost entirely from a spongy substance that develops from a cartilaginous tissue. Such types of bones serve not only to protect, but also to support.

Mixed bones

Mixed bones are a combination of flat and short spongy or tubular bones. They develop in different ways and perform those functions that are necessary on this or that part of the human skeleton. Such types of bones, as mixed, are found in the body of the temporal bone, vertebrae. These include, for example, the clavicle.

Cartilage tissue

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

Bonding

There are different types of connection of bones, which determine the degree of their mobility. Skull bones, for example, have a thin layer of connective tissue. At the same time they are absolutely motionless. Such a compound is called fibrous. Between the vertebrae are also areas of connective or cartilaginous tissue. This connection is called semi-mobile, since the bones, albeit with a restriction, can move slightly.

The joints that form synovial joints have the highest mobility. The bones in the joint bag are held by the ligaments. These fabrics are both flexible and durable. In order to reduce friction, in the joint is a special oily liquid - synovia. It envelops the ends of bones covered with cartilaginous tissue, and facilitates their movements.

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

• Spherical joint. With this connection, it is possible to move the bones at once in many directions. To such joints include humeral, hip.
• Block joint (elbow, knee). Assumes movement only in one plane.
• Cylindrical joint allows bones to move relative to each other.
• Flat joint. He is inactive, provides a small movement between the two bones.
• Ellipsoidal joint. Thus, for example, the radial bone is connected to the bones of the wrist. They can move from side to side within the same plane.
• Thanks to the saddle joint, the thumb of the hand can move in different planes.

Influence of physical activity

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

Negatively affects the condition of bones for a long stay in bed, a sedentary lifestyle. The tissues become thinner, lose their strength and elasticity, become brittle.

The shape of bones changes under the influence of physical exertion. The places where they are affected by the muscles can become flatter. With a particularly intense pressure, small depressions may even occur over time. In areas of strong stretching, where bones act on the bones, thickenings, various irregularities, and tubercles may form. Especially such changes are characteristic for people professionally engaged in sports.

The shape of bones is also affected by a variety of injuries, especially those acquired in adulthood. When a fracture grows together, all sorts of deformations can occur, which often have a negative effect on a person's ability to effectively manage his body.

Age changes in bones

In different periods of a person's life, the structure of his bones is not the same. In infants, almost all bones consist of a spongy substance that 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 the cartilage, which is gradually replaced by bone tissue. This transformation lasts up to 20 years in women and up to about 25 in men.

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

Such fractures heal for a long time. There is a special disease that is typical for the elderly, especially women - osteoporosis. For its prevention when reaching the age of 50 years, you need to see a doctor for some studies to assess the condition of bone tissue. With appropriate treatment, the risk of fractures is significantly reduced and the time of their healing is shortened.