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Damage to the bones of the skull

From fractures flat bones become crucial damage to the bones of the skull. Mechanical trauma to the skull is associated mainly with a direct impact on its vault, which can withstand the load from 1600 up to 8000 N. The closer on the design of the vault of the skull to the hemisphere, the ceteris paribus more resistant to external influences. The stability of the Foundation of the external loads much less that fully offset by depreciation ability curvature of the spine in the neck. The skull is a complex set of flat bones and in the external load is destroyed varies depending on its form (brachycephaly, dolichocephaly), on the one hand, and mechanisms of external influence on the other.

fracture of the vault of the skull
Fig. 23. Fracture of the vault of the skull from the blow oblong object.
comminuted fracture of the vault of the skull
Fig. 24. Comminuted ("spider") fracture of the vault of the skull from hit by an object with a wide hitting the surface.
depressed fracture of the vault of the skull
Fig. 25. Depressed fracture of the vault of the skull.
terrace-like a fracture of the vault of the skull
Fig. 26. Terrace-like a fracture of the vault of the skull.

Originally cracks of calvarium appear under the influence of a blunt object with a force of about 4000 N. Have the value of the direction and speed at which there is a collision of the head with a blunt object (the time of the collision - 0,04 - 0,07).
So, if speed collision of 4.4 m/s in the direction of the front (the strike power 4000-6000 M) are formed cracks in the anterior cranial fossa. The increase in the rate of collisions (5.5 m/s, the impact force of about 7500 H) causes the continuation of a fracture of the front in the middle cranial fossa, and at a speed of 5.8 m/s (the force of the blow over 10 000 H) fracture is distributed cranial fossa.
Blow hard blunt object of an oblong shape, with a relatively small diameter forms a fracture (crack) according to dlinnykh. At the site of contact damaging of the object with the bone occurs area depressing more elongated oval shape. The main crack, corresponding to the long axis of this ellipse, has lots of scratches on the outside of the plate (Fig. 23).
Blunt object with a wide plane when hitting the cranial vault rouses various fractures. The main direction of the crack (fracture) largely depends on the shape of the skull vault in the place of collision - the so-called contact area. Such contact area, depending on the concentration of power voltages and defines the appearance of cracks that can spread to the skull base. If in the zone of collision power voltage are distributed relatively evenly, at the considerable force of impact is formed "spider" fracture. First, at some distance from areas of external influence on the perimeter there are longitudinal cracks, which are distributed both in the direction of external influence and to the point of application of force. The vault of the skull as though divided into separate segments, which would break already in the transverse direction, forming a circle fractures (Fig. 24).
Kick flat solid object in the parietal area causes a fracture of the vault and skull base is very diverse species that depends on the shape of the skull, the thickness of his bones, strength, shock, etc.
The impact of solid objects with a relatively small hitting surface (up to 16 cm2) causes the formation of pressed or perforated, fractures (for example, a hammer blow). The force of the blow is 2000-5000 N (Fig. 25).
Damage of calvarium by blunt objects at the tangential impact in the initial period is reduced essentially to the scheduling of the edge of the face contact parts are striking object in the fabric, and then (with the continuing immersion of the object) - pressure and slide the edge. Formed the so-called terrace-like fracture (Fig. 26).