Bone is the hardest substance after tooth enamel, which is present in the human body and consists of a special type of connective tissue. Its characteristic features include the presence of a solid, saturated with mineral salts, fibrous intercellular substance and stellate cells equipped with numerous processes. The classification and structure of the bones make it possible to understand how important the role of the musculoskeletal system is in the body.
Bone classification
Each bone is an independent organ consisting of two parts. The outer part is the periosteum, and the inner is formed by a special connective tissue. Their cavities are the location of the most important human blood-forming organ.
Classification of bones by shape provides for the following groups:
- long or tubular;
- short, otherwise called spongy;
- flat or wide;
- mixed, sometimes called abnormal;
- airborne.
In a long
(tubular) bone, the middle part is elongated, cylindrical or trihedral. This part is called diaphysis. And the thickened ends are epiphyses. The presence of an articular surface covered by articular cartilage at each epiphysis determines the strength of the joint.
The skeleton of the limbs consists of tubular, in which they are called to fulfill the functions of levers. Further classification of bones of this type provides for their division into long and short. The first include the humeral, femoral, forearm and lower leg. To the second - metacarpal, metatarsal, phalanges of the fingers.
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 joints. We are talking about wrists, tarsi.
Participation in the formation of body cavities and the fulfillment 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, is the bone marrow.
Short bones in the wrist of a person allow using a brush to perform a variety of manipulations. And in the toes increase stability when a person is in a standing position.
The classification of bones provides for the presence of a very complex structure of bones of a mixed type. They are diverse in form and function (arc and processes of the vertebral body).
The airways in the body have a cavity lined with a mucous membrane and filled with air. Part of the bones of the skull belongs to this species. For example, frontal, ethmoid, upper jaw, sphenoid.
Classification of bone compounds
The entire set of bones forms a passive part of the musculoskeletal system, functioning as a system, in many respects, due to the presence of various types of joints, providing a different degree of mobility.
Bone joints are continuous and discontinuous. An intermediate type of compound, which is called symphysis , is also isolated.
Fibrous Compounds
The 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 allows us to distinguish fibrous, bone and cartilage compounds (synchondrosis) among continuous compounds. Fibrous have a high level of strength and low mobility. Within this group of compounds, syndesmosis, sutures and pumping are distinguished. Syndromes include ligaments and interosseous membranes.
Types of fibrotic compounds
Ligaments in structure are thick bundles or plates formed by a dense fibrous connective tissue and a significant amount of collagen fibers. The ligament, as a rule, provides the connection of two bones and reinforcement of the joint, restricting their movement. Able to withstand heavy loads.
With the help of interosseous membranes, the diaphysis of the tubular bones are connected, and also they are the places of muscle attachment. The interosseous membranes have openings through which blood vessels and nerves are held.
One of the varieties of fibrous joints is the sutures of the skull, dividing in accordance with the configuration of the joined edges into spongy, scaly and flat. All types of seams have an interlayer layer of connective tissue.
Injection is also a special type of fibrous connection observed at the junction of the tooth and bone tissue of the dental alveoli. Tooth and bone wall do not touch. They are separated by a thin plate consisting of connective tissue. It is called periodontium.
Synchondrosis and synostosis
Classification of bone compounds involves the presence of synchondrosis, in which the bond is carried out using cartilage tissue. The main characteristics of synchondrosis are elasticity, strength.
When the cartilaginous 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 are joints. The characteristic features of these discontinuous fastenings are the presence of special components: articular surfaces, articular cavity, synovial fluid and capsule.
The joint surfaces are covered by 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 synovial fluid.
Bone fractures
A fracture is a complete or partial violation of the integrity of the bone that 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, which primarily constitute the type of damage 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 provides for their division into congenital and acquired. The presence of congenital fractures is due to impaired intrauterine development and is quite rare. Among them, the most likely can be called those in which the skull, ribs, collarbones, shoulders and hip suffer. Fractures resulting from birth trauma are not related to fetal development, therefore, they are acquired in nature.
Acquired fractures can be traumatic and 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 that are 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 effects, which led to a violation of their integrity. If there is a wound and the tissues are crushed, then 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.
The classification of bones, their joints and fractures allows us to more fully characterize the role of the skeleton in the functioning of the body as a whole and prevent damage to the musculoskeletal system.