Os

Functions

The bones support the body structures, protect the internal bodies, and (in conjunction with the Muscle S) facilitate the movement; they are also implied in the formation of the blood cells, the Métabolisme of calcium, and the mineral storage of . They play finally a part in the detoxicifation of the organization by fixing and storing for example the Plomb (up to 95% of the total body burden at the Man), which can however be brutally salted out at the time of the Ménopause at the woman, or following a fracture by causing an intoxication with the lead of the organization (Saturnisme).

Interactions and organization

The whole of the bones of an animal constitutes its Squelette.

The zones of contact between 2 bones are called the Articulation S. These articulations can be fixed or more or less mobiles.

The bones are also connected the ones to the others by the means of Ligament S interosseux. They are bands of conjunctive Tissu, at the same time flexible and resistant.

The ligaments are to be differentiated from the Tendon S, which connect each one a bone to a skeletal Muscle.

The whole of the bones, the articulations, the interosseux ligaments, the tendons and the skeletal muscles forms the locomotor Appareil.

Types of bone

One distinguishes three types of bone:

the long bones present one their dimensions definitely larger than the two others. They present a body or Diaphyse and two ends or épiphyse S. Diaphyse and épiphyse is connected by a zone which is the seat of the growth: the Métaphyse or cartilage of growth. This one is ossified completely only at the end of the growth. Examples: Femur, tibia.

the diaphyse: it consists of called thick compact fabric cortical or Cortex. It is dug medullary canal filled of osseous Moelle yellow. It is surrounded by a membrane (the Périoste) which is rich in feeder vessels which take part in ossification in thickness.
épiphyses: they are located at the ends: a distal épiphyse (caudal) and a proximale (crâniale). They are made of spongy fabric. They are very rich in red marrow hematopoietic. They are covered with articular Cartilage.
the métaphyse: it is the area located between the diaphyse and the épiphyse.

the short bones have their three appreciably equal dimensions. They are composed of a core of spongy bone surrounded by cortical of compact bone. Examples: Vertèbre S.
the flat bones have a dimension definitely shorter than the two others. They are composed of two layers of compact bone, the tables external and intern, locking up a layer of spongy bone. Examples: Sternum, coast S, Scapula, parietal bones.
the intermediate bones : do not belong to any other type of bone. ()

the lengthened bones : the length prevails on other dimensions, but the size of the bone is smaller. Example: métacarpiens (hand), métatarsiens (foot).
the radiated bones : have a body of which leave the expansions. Example: Vertebrae
the arched bones : two forms: simple curve (example: coast S) or forms horseshoe (example: Mandible)
the papyraceous bones : fine osseous plate. Example: Palatine.
the pneumatic bones : bored cavities, called sine. Example: Os of the face (cranium).

Certain bones present small outgrowths which one names Apophyse S or process.

Morphology of the bone - Configuration External

One distinguishes on the surface from the bones from the reliefs:

Of the Projections (bumps):

Articular: osseous heads, presenting to their surface articular Cartilage.
Nonarticular: expansions of several types: process, tuberosities (bulky: is used for the motor traction), tubers (less bulky than the tuberosities), peaks, spines (example of spines on the vertebrae).

Of the Depressions (hollow):

Articular: the cotyles face the articular projections.
Nonarticular: several types: furrow, gutter, pit.

Structure of the bone - Configuration Internal

One distinguishes for any bone two parts in bone tissue itself:

a central part (spongy Os): This spongy fabric is rich in conjunctive cells fat and in blood elements but its resistance is weak (in the event of fracture, it is crushed easily). Located in particular in the bone trabéculaire of the long bones (inside the épiphyses).
a peripheral part (compact bone): It is a dense, hard and very resistant part osseous forming a more or less thick sleeve (giving rise to the medullary cavity in the long bones).

The bones are moreover surrounded by a fine conjunctive envelope (is located only at the surfaces not covered with Cartilage): the Périoste, contributing to the innervation, the growth and with the cicatrization of the bone.

The mineral part of the bones is made up primarily of calcium phosphate apatitic of which the structure depends on the type on the bone and its age.

Osseous cells

One distinguishes 2 categories of osseous cells: the Osteoblast S (and their derived cells: Ostéocyte S and bordering cells) and the Osteoclast S.

The Ostéoblaste S have a mésenchymateuse origin . They on the surface of the bone in growth, are aligned on osseous surfaces. They are cells cuboïdes, 20 micrometers diameter, with a large core contrary to the surface affixed on the bone. Their contours are irregular and they have prolongations allowing them the contact with other osteoblasts or ostéocytes. Their role is to work out immature bone tissue (osteoid fabric) and to allow its calcification by working out Protéine S initiating the Cristallisation (Bone Sialoproteine/phosphoproteines) and of the Enzyme S allowing the maintenance of calcification (alkaline phosphatase). They act also indirectly in the resorption of bone tissue by working out substances acting on osteoclast.

After a certain number of division, the osteoblast works out the osseous matrix around him; initially on the level of osseous surface then it is surrounded and changed into Ostéocyte.

Osseous matrix

The bone is a whole of fabrics. The bone tissue is a specialized conjunctive fabric. It thus consists of an extracellular matrix and cells. The extracellular matrix has 3 components: fundamental substance, structural fibers and glycoprotéines.

The fundamental substance consists of Glycosaminoglycane S sulphated like the chondroïtines sulfates and héparanes sulfates (with the anticoagulant role), of Hyaluronic acid, Eau, ions, salt deposits of Calcium. The mineral matrix accounts for approximately 70% of the weight of the dry bone. Among rock salt one finds crystals of Hydroxyapatite, calcium carbonates. The organic matrix is primarily made Collagène in the form of broad fibers arranged in plates, of Protéoglycane S and specific noncollagenic proteins of bone tissue as the ostéopontine (the extensive development of the crystals of hydroxyapatite would stop), the ostéonectine and the ostéocalcine. One finds also proteins hidden in the matrix, of nonosseous origin (fétuine, immunoglobulins…)

The fibers are mainly of collagen fibers of the type I (80%). One never finds collagen of the type II which is met only in the cartilage. The fibers are parallel the ones with the others and are organized according to the exerted compressive forces.

If the osteoblasts form bone tissue, the osteoclasts destroy it. They dig surfaces of erosion (or gaps of Howship).

Osseous development

The formation of the bone is done in two ways: the endomembraneuse ossification and the Ossification endochondrale. Endomembraneuse ossification is that of the bones of the cranial vault , of the jawbone; it has a mésenchymateuse origin . Ossification endochondrale is that of the long bones, of the Vertèbre S, the bones of the Pelvis and the base of cranium.

During endomembraneuse ossification, the mésenchymateux fabric, rich in Fibroblaste S gives osteoblasts after recruitment and differentiation. There is osteoid production of matrix. That is done in particular zones known as “centers primary ossification”. They are not very mineral-bearing. After the birth, these zones amalgamate and are mineralized completely.

Ossification endochondrale begin with primary centers of ossification in the average part of the cartilagineuse matrix. Contrary to endomembraneuse ossification it does not consist of a transformation of cartilagineux fabric into bone tissue. It is done in two stages: a destruction of the cartilagineuse matrix then its replacement by bone tissue. The primary education ossification of the Périchondre (future périoste) involves a transformation of the Chondrocyte S: they hypertrophy and degenerate. In this hypertrophic zone, calcium salts precipitate and give a calcified cartilage. The chondrocytes captive of this calcified matrix, degenerate and do not secrete any more an angio-inhibiter. It occurs a neovascularization; the chondroclastes dig cavities in the calcified cartilage. The fragments of cartilages escaping the chondroclastes are used as supports with the pre-osteoblasts arrived with the vascular buds. The pre-osteoblasts give osteoblasts which secrete the osteoid matrix, this one is mineralized to give bone. The osteoclasts are at the origin of the medullary canal. In periphery, one finds the plate épiphysaire which contains hyaline cartilage, seriated cartilage (due to the proliferation activates chondroblastes), hypertrophic cartilage, hypercalcifié cartilage, a line of erosion (which results from the action of the chondroclastes), an osteoid zone and an ossified zone. This plate persists until the bone reached its adult size. When the cartilage disappears, the épiphyse and diaphyse amalgamate: the growth is finished. Ossification endochondrale is at the origin of the growth in length of the bones.

List bones of the human skeleton

Osseous diseases

In addition to the pathologies induced by osseous fractures or a deformation of the spinal column, a imperfect Osteogenesis (Disease of the bones of glass or constitutional osseous brittleness), by anomalies of growth (disease of Ollier, of genetic cause) or of osseous cal type or osseous spines, or by the problems arising from the Rheumatism S, or sometimes from an osseous hypermineralisation (which implies a hypovascularisation); the cancer and the postmenopausic Ostéoporose are the principal grave diseases which directly relate to the bone at the Man.
Une sufficient physical-activity and a sufficient contribution out of calcium make it possible to decrease the risk or the importance of the osteoporosis considered by WHO the second public health issue behind the cardiovascular diseases; around 45 years, the osseous matter loss (which is highest at 18 years) accelerates to reach on average 40% at the woman between 45 and 80 years and 25% at the man.

The cancer of the primitive bone is rare. It is especially about:

the Ostéosarcome relates to primarily the long bones. It is extremely rare before 6 years or after 40 years and is more frequent among boys than the girls. (200 cases per annum in France, including 150 in the child = 5% of cancers of the 12-25 years, according to the Infocancer site)
the “ sarcome (or tumor) of Ewing ” or “ malignant osseous tumor of the child and the young adult ” which touches the flat bones preferentially. This cancer is even rarer than the ostéosarcome (2 to 3 new cases per annum in France per million children of less than 15 years, with a peak at the 10-20 years), but it constitutes for less than 20 years, the second most frequent Tumeur malignant, behind the ostéosarcome.

In fact secondary cancers (resulting from Métastase S) are most current.

In all the cases, one generally associates the Chimiothérapie and the Chirurgie (of which the surgery reconstructrice) which recently profited from many progress but which remains heavy, long, expensive and sometimes painful for the patient.

Os set lead poisoning

The Saturnisme is not an osseous disease, but a “lead poisoning induced” or “secondary” can be the consequence of a fracture, and it can be transmitted of the mother to the child;
Indeed, any fracture involves in physiological answer a release (fast, normal and important) of calcium in blood. This calcium is primarily taken in the bones. However it is in these same bones as 80% to approximately 95% of the lead absorptive by the patient (human), or the neat animal was stored in the previous years and decades (the cycle of lead or average time of stay of lead in the bone is estimated to be 20 years at the man).
Ceci explains, why at an individual not presenting abnormal plombemy before the fracture or at the time of the fracture, but having stored lead in the bones before, a Saturnisme can be induced by the release of a significant quantity of lead “osseous” in blood. This type of lead poisoning has very little chance to be detected if the doctor were not alerted on this risk by the patient (who often of it is not conscious). The symptoms are put on the account of the state of shock or of the Traumatisme related to the accident.
- If the patient is an expectant mother or nursing, this lead can respectively poison the fetus or the embryo and the baby allaité.
- If it or the patient is a person preparing to have children, it is possible that this lead can cause provisional infertility (lead is indeed known as being Reprotoxique at the man, at least as a factor of délétion of the Spermatogenèse, and its effects on the female fertility seem not to be very studied).

Uses

The animal or human bones dead had varied uses. They were used to produce Bijou utility X and objects. Flûte S were carved in human tibiae. The bones of Mammoth S and whale S were used to build dwellings during prehistory.

The conservation and sometimes the exposure of elements symbolic systems (cranium in particular) of skeletons of animals or human were used per many religions (Ossuaire S, Catacombe S.) or uses warlike or different.

The human skeleton was also preserved for the training of the anatomy at the artists and doctors or paramedical professions.

The bones were calcined or crushed to produce Engrais rich in calcium, and sometimes to be directly consumed. It is still the case, with the risk to obtain a manure polluted by the Plomb or other poisons (radionuclides) which are accumulated by the Mammifère S in the bones. 80% of the lead introduced and assimilated by the organization of the mammals are fixed in the bones.

Their incorporation in the animal flours given to herbivores is at the origin of the disease of the Mad cow, and perhaps of CWD, two diseases animal with prion S. the consumption of human remainders by the human ones was in a recent past at the origin of cases grouped of variable of the disease of Kerustfeld Jacob.

The study of the bones of deaths allows by genetic analysis, physics (which isotopic) and biochemical to obtain retrospective information on the individual and his environment, thus T one has which been able to prove that the Roman rich person of antiquity poisoned themselves with the lead of their crockery. For the recent periods, it is one of the fields of the Legal medicine, but the archeologist can study the bones of Momie S or prehistoric men with close objectives and average techniques divided.

See too

Osteology
human Skeleton
osseous Fracture
osseous Surgery
Articulation

External bonds

Site of the association of the " people of small size.
Site of the association of imperfect osteogenesis.

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