**4. Conclusion**

76 Injury and Skeletal Biomechanics

**Figure 8.** Spectral representation of healthy person, age 23, slow in range 0-1,6 Hz and range 0.04 Hz of REG, TCD and Respiration. Arrow (RED) show off central arterial pressure, Arrow Green – fluctuations

of intracranial origin and BUE arrow show component of chest respiratory movements.

All above presented data show, that skull, its brain part is a moveable system. For the skull bone two kinds of movement are special. The first is rapid, during 0.1-0.15s skull expanding by pulse increased arterial pressure. This is too short time to involve CSF to balance intracranial blood volume and increase of volume of arteries mainly on skull basement increase pressure into the skull, which causes deforming its pattern by articular movements of bones in sutures which totally increase internal volume of skull by not much value – about 0.2-0.3% to compare with total volume cranial cavity. However, it is enough to accept additional 3-6 ml of blood, which are extremely important for maintain circulatorymetabolic supply of brain functioning. If this kind of skull mobility diminishes by some reason, brain circulatory insufficiently could appear, which may be reason of some such pathology situation, as brain dementia of circulatory origin. That is why on early steps of civilization, skull trepanation served as method of treatment.

Other kind of the skull bone movements is based on slow fluctuation of skull bone position, evoked by internal forces, finally expressed as periodical changes of intracranial pressure, which include processes in vertebral cord also. Actually, cranio-spinal space is represented

### 78 Injury and Skeletal Biomechanics

as nearly united system. Intracranial liquid system is an initial movement of this slow fluctuation process. It is not yet final point of view how developing all connected with this processes and origin of this initial liquids movement is not clear yet. However, the fact of slow skull bone motions is looks definite confirmed.

The Role of Skull Mechanics in Mechanism of Cerebral Circulation 79

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Although the current role in skull bone movements play mechanical properties of sutures, because separate bone of skull are mechanically too strong to be deformed by arterial pressure forces or other origin forces, which occur inside cranial cavity. Thus, final result of the skull expanding of slow skull bone motions are depends on not structure and biomechanics of some particular suture, but of skull, as united complicated bio-mechanical system. Biomechanical properties single elements composed skull as united moveable system and this is a new property, which is appeared on systemic level. Mechanical properties of the united mechanical system may be different, to compare with any single elements.
