Skeletal pneumaticity

Under pneumatization (from gr πνεῦμα [ pneuma ] "breath ", " breathing " ) refers to the formation of air-filled cavities in human and animal skulls and bones of birds. Such bone is called " air-filled bones " ( Ossa pneumatica ). While the aspect of weight savings is obvious in the bones of birds, the sense of pneumatization is not as clear in the skull. In humans, the weight savings is only about two percent.

Pneumatization of the skull

The pneumatic cavities of the skull develop by the mucosal epithelium of the nose or the middle ear baggy pushes into the mesoderm or between the compact cortical layers of bone.

Result of this process on the one hand, the sinuses, the final development in humans only after completion of skull growth in the 20 to 25 age is reached. Some animals have no sinuses ( seals, whales ), in others they reach a much greater extent than in humans.

The hazards arising from the middle ear pneumatization of the temporal bone is largely completed with the fifth to sixth year. Result of this operation, the pneumatic cells, especially in the mastoid process ( mastoid process ). These are small cavities lined by mucous membrane that together and in the totality of the mastoid by openings of different sizes with the antrum and thus be in communication with the middle ear. The degree of pneumatization of the temporal bone can be very different, there are temporal bones with almost completely missing ( " inhibited " ) pneumatization, which is usually regarded as a consequence of frequent ear infections in childhood. On the other hand, the pneumatization may far up in the temporal squama ( squama ), forward into the zygomatic extension ( zygomatic process ) and extend to the tip of the petrous pyramid. It can be in the mastoid typically individual groups of cells or cell lines differ, which have various names, such as angle cells, threshold cells, terminal cells, etc. Accordingly, in extensive pneumatization squamous cells ( in the temporal squama ), Zygomaticuszellen ( in the zygomatic process ), perilabyrinthäre cells ( located around the maze ) and pyramid tip cells differentiated.

Pneumatization of the long bones in birds

In birds, the large tubular bones such as the humerus, the coracoid, the pelvis, the sternum and the vertebrae are pneumatized, with some species also the thigh bone, the scapula and the clavicle. This pneumatization produced by outgrowths of the air sacs, which extend into said bone.