Bone is the hardest substance in the human body after tooth enamel and is made up of a special type of connective tissue. Its characteristic features include the presence of a solid, saturated with mineral s alts, fibrous intercellular substance and stellate cells, equipped with numerous processes. The classification and structure of bones make it possible to understand how important the role of the musculoskeletal system in the body is.
Classification of bones
Each bone is an independent organ, consisting of two parts. The outer part is the periosteum, and the inner part is formed by a special connective tissue. Their cavities are the location of the most important human hematopoietic organ.
Classification of bones by shape provides for the following groups:
- long or tubular;
- short, otherwise called spongy;
- flat or wide;
- mixed, sometimes calledabnormal;
- airy.
A long (tubular) bone has an elongated, cylindrical or trihedral middle part. This part is called the diaphysis. And the thickened ends are the epiphyses. The presence of an articular surface in each epiphysis, covered with articular cartilage, determines the strength of the connection.
The skeleton of the limbs consists of tubular ones, in which they are called upon to act as levers. Further classification of bones of this type provides for their division into long and short. The first include the shoulder, femur, forearm and lower leg. To the second - metacarpal, metatarsal, phalanges.
In short (spongy) bones, the shape resembles an irregular cube or polyhedron. They are located in those places of the skeleton where a combination of strength and mobility is needed at the junctions. We are talking about the wrists, tarsus.
Participation in the formation of body cavities and the performance of a protective function are the prerogative of flat (wide) bones, which include the sternum, ribs, pelvis and cranial vault. Muscles are attached to their surfaces, and inside them, as in the case of tubular ones, there is bone marrow.
Short bones in the human wrist allow the hand to perform a variety of manipulations. And in the toes, they increase stability when a person is in a standing position.
The classification of bones provides for the presence of very complex bones of a mixed type. They are varied in shape andfunctions (arch and processes of the vertebral body).
The air-bearing organisms have a cavity lined with a mucous membrane and filled with air. Part of the skull bones belongs to this species. For example, frontal, ethmoid, maxilla, sphenoid.
Classification of bone joints
The whole set of bones forms a passive part of the musculoskeletal system, functioning as a system, largely due to the presence of various types of connections, providing a different degree of mobility.
Bone connections are either continuous or discontinuous. An intermediate type of connection is also distinguished, which is called symphysis.
Fibrous compounds
Classification of human bones is important in medicine to prevent damage to the musculoskeletal system. Along with this, the type of fabrics to be bonded is also important. This feature makes it possible to distinguish fibrous, bone and cartilaginous joints (synchondrosis) among continuous joints. Fibrous have a high level of strength and low mobility. Within this group of compounds, syndesmoses, sutures, and driving in are distinguished. Syndesmoses include ligaments and interosseous membranes.
Types of fibrous joints
Ligaments in structure are thick bundles or plates formed by dense fibrous connective tissue and a significant amount of collagen fibers. A ligament generally provides a connection between two bones and reinforces a joint by limiting their movement. Able to withstand heavy loads.
With helpinterosseous membranes connect the diaphysis of the tubular bones, and they are also places of muscle attachment. The interosseous membranes have openings through which blood vessels and nerves pass.
One of the varieties of fibrous joints is the sutures of the skull, dividing according to the configuration of the joined edges into spongy, scaly and flat. All types of sutures have an interlayer layer of connective tissue.
Injection is also a special type of fibrous connection observed at the junction of the tooth and the bone tissue of the dental alveolus. The tooth and bone wall do not touch. They are separated by a thin plate of connective tissue. It's called the periodontium.
Synchondrosis and synostosis
Classification of bone joints provides for the presence of synchondrosis, in which fastening is carried out with the help of cartilaginous tissue. The main characteristics of synchondroses are elasticity, strength.
When the cartilage layer between the bones is replaced by bone tissue, we are talking about synostosis. Mobility in this case goes to zero, and strength indicators increase.
Joints
The most mobile type of joint is the joints. The characteristic features of these discontinuous bonds are the presence of special components: articular surfaces, articular cavity, synovial fluid and capsule.
The articular surfaces are covered with hyaline cartilage, and the cavity is a slit-like space between the articular surfaces of the bones, surrounded by the articular capsule and containing a significant amount of synovialliquid.
Bone fractures
A fracture is a complete or partial violation of the integrity of the bone, which arose from an external injury or in the process of tissue change that caused the disease.
The full name of the fracture can be applied when taking into account a number of signs that make up, first of all, the type of the damaged one, in which the broken bone is localized. In addition, the name of the fracture includes the nature of the causes of its occurrence (traumatic or pathological).
Classification of bone fractures primarily involves their division into congenital and acquired. The presence of congenital fractures is due to disorders in fetal development and is quite rare. Among them, the most likely are those in which the skull, ribs, collarbones, shoulders and hips are affected. Fractures resulting from birth trauma have nothing to do with intrauterine development, therefore, they are of an acquired nature.
Acquired fractures can be traumatic or pathological. The former are the result of mechanical action and are localized either in the place of this action (direct) or outside this zone (indirect). Another group of fractures includes those formed due to damage to the bone tissue by a tumor or other inflammatory or dystrophic processes.
Open and closed fractures
Open fractures are characterized by damage to the skin and mucous membranes in places of traumatic impact, which led to a violation of their integrity. If availablethe wound and tissues are crushed, this provokes the risk of infection and the subsequent development of post-traumatic osteomyelitis.
With a closed fracture, the integrity of the skin is not violated.
Classification of bones, their connections and fractures allows us to most fully characterize the role of the skeleton in the functioning of the body as a whole and prevent damage to the musculoskeletal system.
