Abstract
The region of the roof and posterior wall of the epipharynx which makes up the boundary between the nasal fossae and the pharynx and a part of the upper respiratory tract forms a sharp angle and, by nature of its anatomical structure, is subjected to intense irritation and is markedly influenced by mechanical and physical forces as well as by bacterial action. The morphological and histopathologic changes of this region of the pharynx were studied.
Gross examination of 191 bleached skulls, consisting of 134 males and 57 females, revealed the presence of a particular form of ossification in this region in 41.4 per cent of the specimens.
On closer study of the shape and locality of this ossification, it was concluded that no pathologic process was involved because of the unvarying site of the bone formation, that it was not a senile phenomenon because it was found in all age groups, and that it served no supportive function as its delicate structure crumbled easily on touch. In view of the fact that the crest of this bone formation and the underlying archlike bone seemed to show parallel movements and the fact that the bone formation projected into the epipharynx and was inclined toward the pharyngeal wall, resulting in narrowing of the nasopharyngeal fossa, it was speculated that its formation was related to an adaptative response to respiratory air currents.
Next, pathohistological examination of this region in 64 cadavers, consisting of 44 males and 20 females, revealed in general inflammatory findings in each case. Among those in which the histological findings showed strong tendencies toward fibrotic changes, formation of the bony tissue was observed in 31 specimens. As the roof and posterior wall of the epipharynx is continuously exposed to respiratory air currents, dust-laden air and bacteria, incessantly stimulated during upper inflammatory inflammations or naso-sinusitis, which is prevalent in our country, or intermittently to irritation by choanal discharge, the high incidence of bone formation in those with strong fibrosis of this area suggests that the bone formation results from ossification in the fi brous tissue due to the chronic stimulation produced by these conditions.
