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

lying connective tissue. It contains small vessels for the nourishment of the epithelium, and is pierced by minute canaliculi. Beneath this again is a layer of adenoid tissue, often well, often slightly marked. This tissue is greatly increased in catarrhal affections, but is probably a normal structure. The round cells are chiefly seen around the glands, but may be collected into lymphoid follicles. Below the adenoid layer are large masses of glands and venous spaces forming the bulk of the mucous membrane. The glands are racemose and mucus-secreting, and are most numerous in the posterior part of the nasal fossa. Around and below the glands are numerous large vascular spaces, forming a cavernous plexus. These venous sinuses have thick walls containing much muscular tissue. They receive their blood supply in a somewhat peculiar manner. The arterioles of the mucous membrane run up vertically towards the surface and branch extensively in the above-mentioned adenoid layer. From this the blood is again collected into small veins, which open into the large cavernous spaces. Thus the blood does not pass directly from the arteries into the sinuses, but goes through a previous capillary circulation.

The mucous membrane is traversed by numerous bundles of elastic fibres, which come off from the superficial layer of the periosteum, and end in the adenoid layer of the mucous membrane. Subdividing and reuniting they form an elastic network between the glands and the cavernous sinuses. Bundles of plain muscular fibres are also found around the veins and the acini of the glands, as well as running independently through the mucous membrane. These structures have led some authors to describe the nasal mucous membrane as being "largely composed of erectile tissue," but the designation is hardly accurate. The abundance and size of the venous sinuses and the large amount of muscular and elastic fibres in the mucous membrane allow of rapid and great variations in its thickness in response to the varying needs of the respiratory function.

The mucous membrane over the greater part of the ethmoidal region of the nose is intimately blended with the periosteum, while in the inferior meatus it is separated from it by the thick vascular and glandular layer above described. The mucous membrane around the ostia of the cavities in the infundibular region is very loosely attached, and tends to form folds which easily and rapidly become oedematous.

The olfactory region is very small it is limited to the median side of the superior turbinate and the corresponding area of the septum, but is somewhat irregular. The mucous membrane is brownish grey, and covered by columnar non-ciliated epithelium. It contains little connective tissue, but many lymphoid cells, some of which are pigmented. It also contains many serous glands which are less branched than those in the lower region of the nose; the acini are lined, or almost filled, with small columnar cubical cells. These are the tubular glands of Bowman.

The accessory sinuses are lined by a thin, pale mucous membrane covered throughout with ciliated columnar epithelium. The epithelial layer is usually two or three cells in thickness, and beneath it is a loose areolar tissue containing a few small racemose glands and blood-vessels. The deeper part of this layer is dense in structure and continuous with the periosteum covering the bone. This is my own experience and I believe that of most other observers. Wingrave, however, states that the mucous membrane is covered by a single layer of columnar epithelium which is cilitated only near the ostia of the sinuses: also that in the antrum the glands are found only on the inner wall.

FUNCTIONS OF THE NOSE.

The path of the air stream through the nose has been studied by Paulsen, Zwaardemaker, Scheff and Kayser, Franke and Schäffer, on models and on the dead body, and by Parker and others on the living. The results of these experiments practically agree, and show that the air in

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FIG. 21.-A DIAGRAMMATIC FIGURE SHOWING THE PATH OF THE AIR STREAM THROUGH THE NOSE. 1, Frontal sinus; 2, sphenoidal sinus; 3, superior turbinate; 4, middle turbinate; 5, entrance to the middle meatus; 6, inferior turbinate. The path of the air stream is indicated by the dotted lines. A, B, C represent three whorls or eddies.

inspiration does not take a straight course along the inferior meatus, but ascends in a curved direction from the anterior nares through the vestibule and atrium meatus medii into the middle and superior meatus, and then gradually descends towards the choanae. Parker in a series of cases noted the result of breathing air impregnated with the fine white dust of lycopodium. A broad band of deposited dust was seen along the septum and the outer wall of the nose ascending towards the anterior end of the