The Paranasal Cavities

Abstract

ANATOMY AND PHYSIOLOGYWasson1 presents a roentgen study of the changes in the nasal sinuses after birth to determine at what time the sinuses become fully aerated and what influence this might have on subsequent events with reference to the respiratory tract. He concludes that, in general, the antrums and the ethmoid sinuses of an infant do not become fully aerated until from four to eight weeks after birth and that the state of aeration is an important influence on the condition of these sinuses during the first two years of life.Eckert-M\l=o"\bius 2 presents a comparative study of the nasal accessory sinuses in man and in mammals. With regard to the function of the accessory sinuses, the author rejects the idea that they play any part in the improvement of the sense of smell or that they have arisen to reduce the weight of the skull. He feels, moreover, that the sinuses did not arise as a response to adjustments necessary for the spacing of the teeth and insertion of the muscles of mastication. Their one function is to help warm and moisten the inspired air. Air sinuses have developed in the large and quickly moving mammals with an active respiration (elephant, giraffe and buffalo), while the slow moving mam¬ mals, especially if they live in a watery medium where the inspired air does not require moistening (hippopotamus and walrus), have only rudimentary accessory sinuses or none at all. Numerous illustrations accompany the paper. sixth cranial nerve in the skull and measured in 19 wet specimens from adults the exact distance between the bony floor of Dorello's canal, through which the nerve passes, and the nearest point of the interior of the sinus. A clear description of the course of the nerve from the brain stem to its entrance into the orbit is given in the paper. The author's explanation of the more frequent involvement of the abducens nerve as compared to the involvement of the third or the fourth nerve is that the sixth nerve alone travels through the firm boundaries of Dorello's canal and is therefore more easily compressed.Measurements from the interior of the sinus to Dorello's canal are clearly tabulated. The author found great variations in the specimens examined. The shortest distance was 2 mm. ; the longest, 22 mm. ; the average on the right, 8.3 mm., and on the left, 7.7 mm. As a rule, the distance on one side varied no more than 4 mm. from the other.Of the 38 specimens examined, 2 measured 2 mm., 4 measured 3 mm. or less, 8 measured 4 mm. or less and 11 measured 5 mm. or less. The author ends his paper by speculating on what could be considered the distance of vulnerability of the nerve. The paper is worthy of careful perusal.In a roentgenographic study of 9 cases of homolateral atrophy of the cerebrum, Dyke, Davidoff and Masson 4 found a thickening of the skull and an enlargement of the air sinuses on the corresponding side. The cerebral atrophy may be from any cause such as trauma at birth or infection. As a result of the atrophy of the brain, a localized shrinkage within the skull takes pla...