Tubular bones: structure and function. Long tubular bones

Human tubular bones are bony formations of elongated cylindrical shape, less often trihedral. A strictly defined configuration does not exist. As a rule, the length of such a bone repeatedly prevails over the width. However, the proportions can be very different. The formation and growth of the tubular bone is accompanied by several factors, chief of which is the presence of calcium as a chemical element involved in the construction of bone tissue.

The process of formation of cellular structures is quite long. A lack of calcium often leads to bending of the bones. The excess of this important element can also negatively affect the formation of the skeleton in childhood. In order to prevent the deformation of bones in a growing organism in time, it is necessary to observe the balance of the chemical elements involved in the process.

Long and short tubular bones

The human skeleton is a logical construction endowed with a number of functional programs. Each part of the body fulfills its task, and the vital activity of the whole organism depends on the overall coordination of individual sections. Tubular bones of man represent the most important part of the skeleton, they are entrusted with supporting-motor function. In this case, the activity of the body is possible only if all participants in the process interact. Some functions of bone complexes are programmed to move in a constant mode, such as walking or running. The cyclical repetition of the same actions becomes automatic, impulses are no longer born in the brain or even in the central nervous system, but in the muscle tissue involved in the process.

Tubular bones are connected to each other by means of tendons and muscles. Movable parts of the skeleton interact on the principle of a hinged mechanism. Such devices in the human body are joints, each of which is covered with a special hyaline cartilage, which prevents friction. At the point of mutual contact, the surfaces slide along a certain amplitude, their motion is rational and occurs in a strictly limited regime. The body of the tubular bone is vulnerable, any deviations from the given motion vector cause tension and pain. In the event of an extreme disruption of normal motor regimen, the joint may come out of the natural engagement, and thus a dislocation will occur.

The long tubular bones of the human skeleton belong to the basic supporting formations, sufficiently strong and reliable. Nevertheless, they should be protected, not overloaded and often give rest. Long tubular bones are divided into separate types:

• Tibia;
• Small tibia;
• Femoral;
• Beam;
• Shoulder;
• Ulna.

Short tubular bones:

• Metatarsal;
• Metacarpal;
• Phalanx of fingers.

Most often short tubular bones are a continuation of long ones.

Which tubular bones are levers that somehow participate in the movement of the body? These are tibia and femoral. Short tubular bones provide the function of lever movements in a more limited range.

Structure

Tubular bones consist of a central part, a diaphysis, which is an elongated cavity, terminating at both ends with epiphyses. In the diaphysis there is a yellow brain, and the epiphyses have a solid spongy consistency and are covered with cartilaginous layers.

The epiphysis is the enlarged end of the tubular bone, rounded, having a definite shape, designed for articulation with the adjacent joint. The totality of two or three parts forms a complete joint functioning in a certain motor program of the organism. The contacting fragments of the joints are of the opposite type, when the surface of one half of the convex shape and the other is concave.

Periosteum

Outside, the tubular bones are covered with a periosteum, a connective tissue layer. This is a living organic formation, the purpose of which is to protect functions.

Organic

The tubular substance of the bone consists of organic and inorganic substances. The proportions of their content fluctuate throughout the life of a person. Childhood is the period of dominance of organic substances in the body, which gives bones flexibility. With age, the composition of substances is gradually changing, its legal place is occupied by inorganic substances that provide strength. It is mainly calcium salts.

Physiological device

• A compact substance consists of a variety of bone plates covering the bone with a continuous dense layer. Solid scales are combined into structural units, the so-called osteons. Formed fragments are cylindrical formations of an organic property, within which pass nerves and small blood vessels.
• The spongy substance is located under compact layers, differs from them by a porous structure. In the process of formation of a spongy substance, trabeculae are involved - peculiar bone septa. Much depends on their strength.
• The bone marrow is the main hematopoietic organ in the human body, which is located inside the tubular bones. It is divided into two types: yellow and red. The first is formed by fat cells and is located in the diaphysis - the main part of the tubular bone. The red bone marrow is located in the porous part of the epiphysis and is a reticular tissue densely permeated with small blood vessels. On these channels newly formed cells fall into the mainstream. New blood cells are generated due to stem cells living in the bone marrow. The process does not stop for a second. There are also osteoclasts and osteoblasts, which update bone structures, destroying the obsolete ones.

Growth

Tubular bones grow in the process of development of special epiphyseal plates. The cartilage layer between the epiphyses and the diaphysis can grow intensively in childhood and grow slowly in the period of adolescence, and then of maturity. The process is regulated hormonal and does not stop until its physiological completion.

The most active growth of bones occurs during physiological stretching. The first period lasts from 5 to 7, the second - from 11 to 15 years. Further, the growth of bone formations continues, but at a slowed pace. Finally, the phase of skeleton formation ends at 20 years.

Fractures

The pathological violation of the integrity of individual structures of the skeleton as a result of excessive load can be qualified as fractures of tubular bones.

The main causes of fractures:

• Mechanical injuries;
• Various diseases that cause a decrease in bone strength (osteomyelitis, osteoporosis).

Types of fractures:

• Metaphyseal;
• Epiphyseal;
• Diaphyseal.

Signs of a fracture:

• Pain, sharply increasing with exercise;
• Swelling that occurs after a while at the site of injury;
• Extensive hematoma, appearing 90 minutes after injury;
• Failure of the function of the damaged limb.

Signs of an absolute nature:

• The unnatural position of the limb;
• Chaotic mobility of individual parts;
• Characteristic crunch (creping) in the place of damage;
• Bone fractures in the wound, revealed with open fractures.

Recovery

Regeneration and healing of bone tissue occurs due to the formation of new cells at the site of injury. Recovery of a tubular bone can take from several weeks to several months. The healing process requires absolute rest.

The regeneration involves the cambial layer of the periosteum and the stem cells of the yellow brain.

The healing process is divided into four stages:

1. Autolysis - the active concentration of leukocytes at the site of fracture and dissolution of dead tissue fragments.
2. Proliferation is the reproduction of bone cells as a reaction to damage with the simultaneous production of cartilaginous tissue, which is then mineralized.
3. Restoration of blood supply, disrupted as a result of trauma, the formation of a compact substance.
4. Complete recovery of the bone marrow canal, return of functional abilities.

Diagnostics

Diagnosis of fractures should be carried out under stationary conditions. To identify the full picture of damage, an X-ray examination with determination of the absolute and relative signs of the fracture is necessary.

After diagnosis, a course of treatment is carried out, which consists of manipulating the application of a fixing gypsum tire. If necessary, traction methods are used. Then follows a long observation of the patient's condition and drug treatment.