Osteology is the study of the bones which form the various parts of the skeleton.

The bones are joined together between them by articulations, they form the frame of the body, passive part of the locomotor apparatus whose muscles form the driving elements of them.

The bones have for certain in more one role of protection of internal organs: cranium, rib cage.

The skeleton includes/understands, a cartilagineuse part and an osseous part.

 

Installation of the skeletal system

 

The skeleton consists of 206 bones (200+ 6 bones of hearing), this number is variable because there is:

- bones surmuméraires (bone moreover) especially on the level of the foot and hand in particular bone sésamoïde

- double bones, patella bipartite

- irregular bones

The skeleton consists of an axial skeleton and an appendicular skeleton.

- The axial skeleton includes/understands: the bones of the head (cranium and face), the bone hyoïde only bone not articulated with another bone, located at the higher part of the neck, the spinal column (rachis) formed of a mobile segment and a fixed segment (sacrum, coccyx), on the rachis set the rib cage (12 pairs of coasts and the sternum)

- On this axial skeleton is fixed the appendicular skeleton which is symmetrical and homologous (even nonsuperposable morphology but)

- The appendicular skeleton is formed by the bones of the two upper limbs (thoracic members) and of the bones of the two lower limbs (pelvic members).

* The thoracic member is trained of the bones as of the belt scapular which fix the member at the rib cage , and a free part (humérus, radius, ulna, bone of the carpus, the métacarpiens, phalanges).

* The pelvic member is trained of the bones of the pelvic belt which fix the member at the fixed rachis, and of a free part (femur, patella, tibia, fibula, bone of the tarsus, the métatarsiens, phalanges).

 

Classification of the bones

This classification depends on the external conformation of the bones. The bones are varied and irregular, they can be brought back to a parallépipéde having three dimentions: length (L), width (L), thickness (E). There are three principal types of bone:

Long bones: L prevails compared to L and E, example the humérus, the long bones are divided into two parts an intermediate part the diaphyse or body of cylindrical or prismatic form; a bulky distal part the épiphyses which carry articular surfaces (covered with cartilage) of the zones of muscular and tendineuses insertions. The épiphyse more close to the trunk and the épiphyse proximale, the most distant épiphyse is known as distal. Between the body and the épiphyses the métaphyse is which carries the cartilage of growth at the time of the growth of the bone.

Short bones: their three dimentions are presques equal, cubic, some are small, bone of the carpus; others larger, bone of the tarsus.

Flat bones: the thickness is definitely lower by report/ratio has L and L, bone of the belts, cranium…

Intermediate types of bone: irregular or radiated bones (vertebrae, sphénoïde,…); papyraceous bones blades or thin osseous plates on the level of cranium; pneumatic bones with air cavities (sine) especially on the level of the face.

The bones present to between-them reports/ratios proportional to the size of the subject, harmonizes and proportion of the human body. Importance on the medico-legal and anthropological level to determine the age size and the sex of a subject starting from a bone.

Morphology

The bones are irregular on their surface of many projections or depressions with particular functions for the port of articular surfaces or insertions of muscles.

- Osseous Projections, they can be articular or not articular

* Articular projections: on the morphological level one distinguishes: the heads which are separate surfaces of the narrowed bone by a zone: the collar, condyles are sessile.

* Nonarticular projections which give insertions to ligaments, tendons and muscles according to their volumes one distinguishes: processes, tuberosities, tubers, spines, peaks, eminences; its projections can be under cutaneous thus palpable and are used as surgical reference mark.

- Osseous Depressions, also articular or not.

* Articular depressions: sockets articulating itself with the articular projections (acétabulum of the femoral articulation coxo.).

* Nonarticular depressions: Cavities of reception containing a body (cerebral pit, small cavity olécranienne); Muscular cavities of insertions (iliaque pit); Furrows of passage (gutters) for tendon (long portion of the biceps) for a nerve (furrow of the radial nerve) for an artery (méningée artery); foramens; incisures.

 

Structure of the bone

At the cut the bone has surface towards the depth: the périoste, the compact bone, of the spongy bone or a cavity.

- The périoste is a membrane conjonctivo-rubber band which covers like a sleeve the safe bone on the level of the épiphyses which are recouvertent of cartilage. It richly vascularized and is innervé and gives insertion to the muscles and tendons.

- The compact bone is a hard, dense and white subtance. Formed of let us ostéons and the plates arciformes.

- L' spongy bone made up of osseous plates, trabécules osseous, on the level of the épiphyses they form tension fields.

- The medullary canal located in the diaphyse contains marrow, of the vessels, the nerves.

Development of the bones

Ossification starts at the end of the embryonic period.

Two types of ossifications: of membrane, endochondrale.

Primary points of ossifications for the intra-uterine period (diaphyse)

Secondary points of ossifications (épiphyse) native period post.

Growth of the bone: length DC; width périoste; modelling of the bone.

 

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