Long short and flat bones. Classification of bones
An 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 shell that contains 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, for example, the brain, located in the bones of the skull, lungs and heart, located in 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. Blood cells are born in the bone marrow: 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
Exist 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 (comes 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 kinds 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. Images
The name of the bones often indicates their structure. For example, cancellous bones are formed from spongy substance covered thin layer 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. She shapes ears, nose, 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. Thus connected, for example, radius with carpal bones. They can move from side to side within the same plane.
- Thanks to saddle joint thumb hands 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).
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 The belts are constructed of spongy substance (scapula, pelvic bones). Flat bones perform the functions of support and protection,
Mixed dice merge from several parts that have different functions, structure and development (bones of the base of the skull, collarbone).
Question 2. Types of bone joints.
All bone connections can be divided into 2 groups:
continuous connections - synarthrosis (immobile or sedentary);
discontinuous joints - diarthrosis or joints (mobile according to 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:
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.
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 a significant amount of 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.
Name
Structure
Flat bones are formed by two thin plates of compact substance, between which there is a spongy substance containing bone marrow. The spongy substance of the skull bones is called diploe.
Ossification
Ossification of the flat bones of the skull is carried out on the basis of connective tissue (endesmal ossification). The ossification of the remaining flat bones is carried out on the basis of cartilaginous tissue (enchondral ossification).
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Literature
- Sapin M. R., Bryksina Z. G. - Human anatomy. Enlightenment, 1995 ISBN 5-09-004385-X
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Excerpt characterizing Flat Bones
- No, I saw... Then there was nothing, suddenly I see that he is lying.– Andrey is lying down? He is sick? – Natasha asked, looking at her friend with fearful, stopped eyes.
“No, on the contrary,” on the contrary, a cheerful face, and he turned to me, “and at that moment as she spoke, it seemed to her that she saw what she was saying.”
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Soon after Christmas, Nikolai announced to his mother his love for Sonya and his firm decision to marry her. The Countess, who had long noticed what was happening between Sonya and Nikolai and was expecting this explanation, silently listened to his words and told her son that he could marry whomever he wanted; but that neither she nor his father would give him his blessing for such a marriage. For the first time, Nikolai felt that his mother was unhappy with him, that despite all her love for him, she would not give in to him. She, coldly and without looking at her son, sent for her husband; and when he arrived, the countess wanted to briefly and coldly tell him what was the matter in the presence of Nicholas, but she could not resist: she cried tears of frustration and left the room. The old count began to hesitantly admonish Nicholas and ask him to abandon his intention. Nicholas replied that he could not change his word, and the father, sighing and obviously embarrassed, very soon interrupted his speech and went to the countess. In all his clashes with his son, the count was never left with the consciousness of his guilt towards him for the breakdown of affairs, and therefore he could not be angry with his son for refusing to marry a rich bride and for choosing the dowryless Sonya - only in this case did he more vividly remember what, if things were not upset, it would be impossible to wish for a better wife for Nikolai than Sonya; and that only he and his Mitenka and his irresistible habits are to blame for the disorder of affairs.
IN skeleton The following parts are distinguished: the skeleton of the body (vertebrae, ribs, sternum), the skeleton of the head (bones of the skull and face), the bones of the limb girdles - upper (scapula, collarbone) and lower (pelvic) and the bones of the free limbs - upper (shoulder, forearm bones and hand) and lower (thigh, leg bones and foot).
Number of individual bones There are more than 200 that make up the skeleton of an adult, of which 36 - 40 are located along the midline of the body and are unpaired, the rest are paired bones.
According to external form There are long, short, flat and mixed bones.
However, this division, established back in the time of Galen, is only one attribute(external form) turns out to be one-sided and serves as an example of the formalism of the old descriptive anatomy, as a result of which bones that are completely different in their structure, function and origin fall into one group. Thus, the group of flat bones includes parietal bone, which is a typical integumentary bone that ossifies endesmally, and the scapula, which serves for support and movement, ossifies on the basis of cartilage and is built of ordinary spongy substance.
Pathological processes also occur completely differently in the phalanges and bones wrists, although both of them belong to short bones, or in the femur and rib, included in one group of long bones.
Therefore it is more correct distinguish bones based on 3 principles on which any anatomical classification should be built: form (structure), function and development.
From this point of view, we can outline the following bone classification(M. G. Gain):
I. Tubular bones. They are built of a spongy and compact substance that forms a tube with a medullary cavity; perform all 3 functions of the skeleton (support, protection and movement).
Of these are long tubular bones(shoulder and bones of the forearm, femur and bones of the leg) are struts and long levers of movement and, in addition to the diaphysis, have endochondral foci of ossification in both epiphyses (biepiphyseal bones); short tubular bones (carpal bones, metatarsals, phalanges) represent short levers of movement; Of the epiphyses, the endochondral focus of ossification is present only in one (true) epiphysis (monoepiphyseal bones).
II. Spongy bones. Constructed primarily of a spongy substance covered with a thin layer of compact. Among them, there are long spongy bones (ribs and sternum) and short ones (vertebrae, carpal bones, tarsus). Spongy bones include sesamoid bones, i.e., similar to the sesamoid grains of the sesame plant, which is where their name comes from (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. Sesamoid bones are located near the joints, participating in their formation and facilitating movements in them, but are not directly connected to the bones of the skeleton.
III. Flat bones:
A) flat bones of the skull(frontal and parietal) are performed mainly protective function. They are built from 2 thin plates of a compact substance, between which there is diploe, diploe, is a spongy substance containing channels for veins. These bones develop on the basis of connective tissue (integumentary bones);
b) flat bones belts(scapula, pelvic bones) perform the functions of support and protection, built mainly from spongy substance; develop on the basis of cartilage tissue.
IV. Mixed bones (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.