Study of mastoid canals in dried human skulls

ABSTRACT

To search for vascular tunnels or canals in the mastoid region which may not been reported before in Egyptian population, and may be of surgical importance. The study was carried on 30 complete dried Egyptian skulls, and 20 hemisected skulls or separated temporal bones. Another 10 hemisected heads preserved in formalin, and injected with gelatin/lead oxide mixture were also used. These heads were used to detect structures traversed the mastoid canal if present. Examination of dried bones revealed the presence of canal or tunnel on the outer surface of the mastoid processes in 37.5% of studied specimens. These canals were anterior to the occipitomastoid suture by a distance ranged from 0.5 to 1.8 cm. The canals were anteroinferior to the asterion by a distance ranged from 1 to 2.3 cm. The length of the canal varied from 0.2 to 2 cm. The lower opening of the canal was anterior or anterosuperior to the mastoid foramen. Dissection of injected heads showed that the canals contained a branch of occipital artery. The mastoid canals are not peculiarly confined to Indian population but they also found in skulls of Egyptian population. The presence of these canals in some skulls may be due to ossification of squamotemporal bone over the vessels during development of the mastoid process. The mastoid canals traversed by the auricular branch of occipital artery, which lied anterior to the mastoid foramina. This branch could be injuried if unnoticed by the surgeon. It is necessary for surgeons operating in this area to be aware of this vascular arrangement to anticipate and avoid troublesome bleeding