Structure and function of skeletal
Passive part of the musculoskeletal system is a set of human bones and their joints - skeleton (sceleton) (Fig. 1). The skeleton consists of bones of skull , spine and rib cage (the so-called axial skeleton), and the bones of the upper limbs and lower limbs bones (skeleton extension).
The skeleton is characterized by high strength and flexibility, which provides a way to connect bones to each other.
Flexible connection of most bones attached to the skeleton provides the necessary flexibility and freedom of movement. In addition to the continuous fibrous and cartilaginous joints (they basically are interconnected bones of the skull) in the skeleton, there are several types of less rigid joints of bones. Each type of connection depends on the desired degree of mobility and the type of loads at the site of the skeleton. Compounds with limited mobility or polusustavami called the symphysis, and discontinuous (synovial) compounds - joints. The complex geometry of the articular surfaces are exactly the degrees of freedom corresponds to the connection.
The bones of the skeleton are involved in processes of hematopoiesis and mineral metabolism, and bone marrow is an important part of the immune system. In addition, the components of the skeleton are the bones of the support for organs and soft tissues of the body, protects vital internal organs.
Human skeleton continues to form throughout life, bone is constantly being updated and grow, responding to the growth of the whole organism, some bones (eg, coccygeal or sacral), which the children are separated, as they grow older are fused into one bone. By the time of birth of bones of the skeleton has not yet been formed and many of them are composed of cartilaginous tissue.
|A - appearance in front;
B - back view:
1 - skull;
2 - chest;
3 - the bones of the upper extremity;
4 - spine;
5 - pelvic bone;
6 - the bones of the lower extremities.
The skull of the fetus at the age of 9 months is not a rigid structure, its components do not separate the bones healed, which should provide a relatively easy passage through the birth canal. Other features: not fully developed bone zone of the upper extremities (shoulder blade and collarbone), the majority of carpal and tarsal cartilage yet, the moment of birth is not formed and the bones of the chest (in the newborn xiphoid cartilage and the sternum is represented by separate, not fused between a bony points). The vertebrae are separated at this age, relatively thick intervertebral discs and the vertebrae themselves are just beginning to take shape: the body and vertebral arch is not fused and are bony points. Finally, the pelvic bone at this point consists only of the ischial bone rudiments, the pubic and iliac bones.
The skeleton of an adult consists of more than 200 bones, and his weight (on average) in men is approximately 10 kg, in women about 7 kg. The internal structure of each of the bones optimally adapted to the bone could successfully carry out all the many functions that are assigned to it by nature. Involvement of bones that make up the skeleton in metabolism is provided by blood vessels which penetrate every bone. The nerve endings that penetrate into the bone, let her, as well as throughout the skeleton as a whole to grow and evolve, to adequately respond to changes in living environment and external conditions of existence of the body.
Structural unit of the reference unit, which forms the bones of the skeleton, as well as cartilage, ligaments, tendons and fascia is the connective tissue (textus connectivus). A common characteristic of the structure of various connective tissue is that they are all composed of cells and intercellular substance, which consists of fibrous structures and amorphous material. Connective tissue performs various functions: as a part of the trophic - formation of the stroma, the power cells and tissues, the transport of oxygen, carbon dioxide, as well as mechanical, protective, that is, combines different types of tissues and organs protects against damage, viruses and microorganisms.
|1 - skull;
2 - the bones of the upper extremity;
3 - chest;
4 - spine;
5 - pelvic bone;
6 - the bones of the lower extremity
The connective tissue is divided into proper connective tissue and connective tissue with special reference (bone and cartilage) and hematopoietic (myeloid and lymphatic tissue) properties.
Actually connective tissue is divided into fibrous and connective tissue with special properties, which include reticular, pigment, fat and mucous tissue. Fibrous tissue is represented by a loose connective tissue unformed accompanying blood vessels, ducts, nerves and organs separating from each other and from the cavities of the body, forming with the stroma of organs, as well as dense and unformed decorated with connective tissue that forms ligaments, tendons, aponeuroses, fascia, perinevrii, fibrous membrane and elastic tissue.
Bone (textus osseus) forms bony skeleton of the head and limbs, axial skeleton body, protects organs, located in the skull, chest and pelvic cavities, is involved in mineral metabolism. In addition, bone tissue determines the shape of the body. It consists of cells, which are the osteocytes, osteoblasts and osteoclasts, and of the intercellular substance containing collagen fibers of bone and bone ground substance, which deposited minerals that make up 70% of the total bone mass. Thanks to so many basic salts of bone substance is characterized by increased strength.
Bone tissue is divided into coarse-fibered, or retikulofibroznuyu characteristic of embryos and young organisms, and lamellar tissue component of the bones of the skeleton, which, in turn, is divided into the sponge contained in the epiphysis of bones, and compact, which is in the diaphysis of long bones.
Cartilage (textus cartilagineus) formed by cells and chondrocytes intercellular substance of high density. Cartilage perform a support function and belong to the various parts of the skeleton. Distinguish fibrous cartilage that is part of the intervertebral discs and joints pubic bone, hyaline, cartilage forming the articular surfaces of bones, the ends of the ribs, trachea, bronchi, and elastic, which forms the epiglottis and auricle.
a., aa. — arteria, arteriae (artery, the artery)
lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)
m., mm. — musculus, musculi (muscle, the muscle)
n., nn. — nervus, nervi (nerve, the nerve)
r., rr. — ramus, rami (branch)
s. — seu (or)
v., vv. — vena, venae (vienna)