with the maxillary antrum; in one of the series, it came into relationship with the frontal sinus. The upper wall divides the sinus from the cranial cavity, and is usually composed of dense bone 2-4 mm. thick, but it may be thin or even defective (Zuckerkandl). The other walls are thick, and are of no surgical importance. Turner gives the average dimensions of the sphenoidal sinuses as 18 mm. in all three diameters, but they are extremely variable, and are rarely symmetrical.

may be very large, while the other forms a mere slit (see Fig. 17), or one sinus, or even both, may be absent. Kicer found both sinuses absent

FIG. 18.-HORIZONTAL SECTION THROUGH UPPER PART OF NOSE, VIEWED FROM BELOW. a. Sphenoidal sinus (the cavities in this specimen are unusually symmetrical); b. superior turbinate; c. bony cyst in anterior end of middle turbinate; d. roof of antrum; e. nasal polypus; septum; g. anterior end of middle turbinate; h. lachrymal duct; i posterior ethmoidal cell.

7 times in 195 skulls. It is important to remember that the larger the sinus the thinner its walls will probably be.

The ostium of the sphenoidal sinus is situated in its anterior wall near the upper part, close to the nasal septum, and leads directly into the fourth or highest meatus. It is round or oval, and varies from 1-4 mm. in diameter. From its situation it follows that the opening is normally invisible by anterior rhinoscopy, but it may generally be brought into view by the removal of the posterior half or more of the middle turbinate. It may also be visible when atrophy of the middle turbinate is associated with an unduly roomy nose, as in some cases of atrophic rhinitis. The opening is 7-8 cm. distant from the anterior nares; 8.3 cm. in men, 7.6 cm. in women, according to Grünwald. When an attempt is made to

catheterize the sinus the probe, with its point bent slightly outwards and downwards, should be passed across the middle of the inferior border of the middle turbinate. It is pushed gently backwards, upwards and slightly outwards, until the anterior surface of the sphenoid is reached, when, with a little manipulation, the probe may be felt to slip through an opening and to pass onwards for another 1-2 cm.

Development. The sphenoidal sinus is usually apparent about the third to fourth year (Symington), and gradually increasing in size, attains its full relative development about the sixth or seventh year. It is developed within the sphenoidal turbinate, which forms the anterior or nasal wall of the sinus Coffin states that a distinct cavity may be seen

in the first year.

On the upper

The cranial relations of this sinus are very important. surface of the superior wall in the middle line lie the optic commissure and the pituitary body: and on each side of the middle line, separated from the sinus by a very thin bony septum, lie the internal carotid artery and the optic nerve. On its outer side the sphenoidal sinus comes into close relationship with the cavernous sinus and the numerous nerves contained in it. This is the usual arrangement, but frequently the optic nerve is separated from the sphenoidal sinus by one of the posterior ethmoidal cells (Onodi).

The great extent of the accessory sinuses of the nose may be gathered from the fact that the average total capacity of the accessory sinuses on one side only is 44.6 c.cm., which is about 10 c.cm. greater than that of both nasal cavities proper (Braune and Clasen). I have confirmed these measurements in two skulls by the rather laborious method of making casts of all the various cavities and then measuring the casts. The heads were soaked in melted paraffin wax and aspirated until all the air had been removed and every cell and cavity was filled with paraffin. The preparation was then allowed to cool and the bones and soft parts dissolved off with strong hydrochloric acid.

The blood supply of the nose is derived chiefly from the sphenopalatine branch of the internal maxillary artery. The posterior nasal branches of this artery supply the greater part of the outer wall of the nose, including the inferior and middle turbinates. The naso-palatine branch supplies the posterior two-thirds of the nasal septum. These vessels send branches to the mucous membrane lining the sphenoidal, ethmoidal and frontal sinuses. The anterior ethmoidal branch of the ophthalmic artery supplies a small area of the anterior part of the outer wall of the nose and of the septum: the posterior ethmoidal branch of the same artery supplies some of the ethmoidal cells. A few other arterial twigs enter the nose anteriorly and posteriorly.

The veins leave the nose with the corresponding arteries. The ethmoidal veins join with the ophthalmic vein and communicate with the veins of the dura mater and of the olfactory bulb, and sometimes with

the longitudinal sinus by the vein in the foramen caecum (often obliterated). The spheno-palatine vein empties into the pterygoid plexus. Small veins also pass out at the anterior margin of the nose to join the plexus on the upper lip, and other small twigs pierce the bony framework of the nose and join the commencement of the facial vein.

The lymphatic vessels of the nose are numerous and form a large network over the mucous membrane. The majority of the vessels pass backwards, and unite with those of the throat and palate, and then enter the deep cervical glands which lie behind and below the angle of the jaw. The lymphatics of the ethmoidal region form connections with the subdural and subarachnoid spaces of the brain through the lymphatic spaces which surround the branches of the olfactory nerve. These communications, which can readily be demonstrated by injection, are extremely interesting, and may explain the cerebral symptoms-headache, inability to fix the attention, mental dulness, depression, neurasthenia-which are so commonly associated with ethmoidal disease, nasal polypi, etc. They may also serve as channels of infection in suppurative affections of the nose and ethmoidal cavities.

The nerve supply like the vascular is derived from two origins. The anterior portion of the nose, both the outer wall and the septum as far back as the naso-palatine canal, that is the part corresponding to the original embryonic fronto-nasal process, is supplied by the nasal branch of the first division of the fifth nerve. The posterior region of the nose, an outgrowth from the middle part of the skull united with the upper jaw, is supplied chiefly by the second division of the fifth nerve through the spheno-palatine ganglion. This, ganglion gives off two small upper nasal branches which enter the back part of the nasal fossae and supply the upper and posterior part of the septum, the corresponding parts of the superior and middle turbinate bones and some of the posterior ethmoidal cells. The largest branch, the naso-palatine nerve, crosses the roof of the nose and runs downwards and forwards along the septum. It gives off branches which supply the greater part of the outer wall of the nose including the middle and inferior turbinates and the greater part of the septum. The frontal sinus is supplied by the nasal nerve and the antrum by branches of the superior maxillary nerve.

HISTOLOGY.

Physiologically the nasal fossae may be divided into three parts, characterised by differences in function and in the structure of the lining membrane; these are the vestibule, the respiratory and the olfactory regions.

The vestibule, or part immediately within the by a protrusion inwards of the skin of the face. vestibule is studded with short stout hairs, or

anterior nares, is formed The anterior part of the vibrissae, and contains

large sebaceous and sweat glands. It is lined by stratified squamous epithelium. Behind this is a transition area: the skin gradually loses its characteristics, hair-follicles, glands, etc., disappear, and the epithelium becomes first round or cubical, then conical or columnar with large nuclei, and ultimately ciliated. The dividing line between the mucous

membrane and the skin is thus not sharp, and marked individual differences are met with.

The respiratory region of the nose lies immediately behind the vestibule, and comprises by far the largest part of the nasal cavity. It is lined throughout by a thick vascular mucous membrane covered by columnar ciliated epithelium.

The mucous membrane over the greater part of the nose is 1 mm. or more in thickness. In certain places it much exceeds this, thus, over the inferior turbinate and inferior meatus it is 2-3 mm., and over the lower edges of the middle and inferior turbinates about 7 mm. thick. There is

also a local thickening on the septum opposite the anterior end of the middle turbinate, known as the tubercle of the septum. This eminence is due chiefly to a collection of glands, but a few venous sinuses are also present. On the posterior end of the inferior turbinate the membrane is often divided into folds by more or less deep longitudinal sulci. Also on the posterior part of the septum thick parallel folds of mucous membrane may often be seen. These are most marked in the foetus, but are

FIG. 20.-SECTION OF THE MUCOUS MEMBRANE OVER THE INFERIOR TURBINATE. (After Zuckerkandl.) E. Ciliated epithelium; b. basement membrane; S. lymphoid tissue; v. vascular sinuses.

present in 30 per cent. of adults, and may be greatly hypertrophied in disease. These folds consist to a large extent of lymphoid tissue, which is often collected into nodules. In the lower part of the nose the normal colour of the membrane is reddish; in the upper and posterior part it is brown or grey.

The epithelium covering the inferior turbinate consists of several layers, the most superficial of which is formed by columnar ciliated cells; between these cells appear a few mucus-secreting beaker cells. Beneath the epithelium is a thick basement membrane continuous with the under