Osteology (OSTEOLOGIA) - the science of the bones
- Category: Musculoskeletal system
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Classification of bones:
- Tubular bones - have a body - diaphysis (diaphysis) and end - epiphysis. Between the diaphysis and the epiphysis is the "growth zone" - metaphysis, by which the bone grows in length. Tubular bones can be long and short. Long tubular bones perform locomotor function, short - supporting.
- Trabecular bones are short, have a shape of an irregular cube.
- Flat bones are wide, are involved in the formation of a body cavity serve a protective function.
- Mixed bones are complex. Have elements of the flat and trabecular bones.
- Pneumatic bones - have a cavity filled with air.
Every bone is an independent organ. Living human bone contains of 50% water, 28.15% of organic substances and 21.85% of inorganic compounds (compounds of calcium, phosphorus, magnesium, etc.). Macerated (bleached, dried) bone consists of 1/3 organic substances and 2/3 of inorganic chemicals. With the predominance of organic substances in the bone (children), the bone is more flexible; with the predominance of inorganic substances (older people) - the bone is crisp. The bone is composed of bone tissue. The outer layer of the bones are formed by compact substance (substantia compacta), which consists of lamellar bone tissue through which pass thin bone tubules (some of which are parallel to the surface of the bone, others - perpendicular). Bone tubules is a continuation of feeding channels (candles nutricia), which open on the surface of the bone. Through feeding channels occurs power supply and innervation of the bone, because through them pass arteries, veins and nerves. The structural unit of the bone is osteon or Haversian system.
Osteon is a central channel (canaliculus placed parallel to the surface of the bone) with a system of concentric plates that form the walls of the central channel. Concentric plates have the form of tubes inserted into each other. Spaces between the osteons filled with inserted (intermediate) plates. Under the the compact substance is located sponge substance (substantia spongiosa). Spongy substance is porous, and formed by bone beams between which is cavities. Bone beams placed not chaotic, but in the direction in which the bone gets load (compression and stretching). Spongy substance of skull bones placed between two plates of compact substance and is called diploe. Inner plate of compact substance is thin, easily brokes in trauma, is called glass plate (lamina vitrea). Inside of the bone is located medullary canal or the cavity (cavitas medullaris). The inner layer of bone tissue that covers the medullary canal, is called endosteum. Medullary canal is filled with bone marrow (medulla ossea). Bone marrow is the body of hematopoiesis and immune system. There are red bone marrow and yellow bone marrow. Red bone marrow (medulla ossea rubra) - placed in the cells of the spongy substance of flat and spongy bones, epiphysis of long (tubular) bones; consists of a mesh of reticular fibers and cells in the loops of which are located young and mature blood cells.
In newborns red bone marrow is located in all bones, in adult human red bone marrow mass is significantly reduced. Yellow bone marrow (medulla ossia flava) fills the bone marrow cavities of diaphyses of long bones, consists of rebirth reticular stroma with the adipose tissue. Blood-forming elements in the yellow bone marrow are missing. Outside the bone is covered with periosteum. Periosteum is a thin connective plate which consists of two layers rich in blood vessels and nerves. The outer layer of the periosteum is fibrous, the inner - growth, cambial (osteogenic). At the expense of the inner layer of the periosteum are formed young bone cells (osteoblasts) which are are precipitated at the surface of the bone and thus the bone grows in thickness.
Above the surface of the bone are the spines - apophysis. Skeleton is a collection of bones. The skeleton consists of bones of the body (51 bones), the bones of the head (29 bones), the bones of the upper extremities (64 bones), the bones of the lower extremities (62 bones). The skeleton performs supporting function (to the bones are attached muscles, fascia), safety (forming the walls of the cavitiesin which are organs), motor (muscle perform movements of the bones in the joints, causing the body moves), biological (involved in metabolism), hematopoietic (bones contain bone marrow).