This description, intentionally, has been made without reference to the anatomical relation of the parts, but to give a clear idea of what is seen in the laryngeal mirror. The reader should therefore always bear in mind that the laryngeal image, being a reflected one, is reversed, and that, on account of giving a bird's-eye view of the larynx from a point above and behind the organ, distances are materially diminished; and the image is also reversed in an antero-posterior direction, so that the epiglottis appears to be posterior when in reality it is anterior.
RHINOSCOPY.—Rhinoscopy, or the art of inspecting the nasal cavities and the naso-pharyngeal space, is divided into two portions—viz. anterior and posterior rhinoscopy; and it will be convenient to observe this division in the following description of the methods employed. But before proceeding with the description it will be well to briefly review the topographic anatomy of the parts, because in most works on general anatomy the nasal and naso-pharyngeal cavities are discussed in a few sentences, and they are rarely if ever examined in the dissecting-room, so that the student has but a very imperfect knowledge of the relation of the parts belonging to these cavities. (See Fig. 11.) The nasal cavities, which are wedge-shaped, with a narrow arched roof, extend from the nostrils to the upper portion of the vault of the pharynx. Their outer walls are formed by the nasal process of the superior maxillary and lachrymal bones in front; in the middle, by the ethmoid and inner surface of the superior maxillary bones; behind, by the vertical plate of the palate bone and the internal pterygoid process of the sphenoid and the turbinated bones. These latter run before backward, three on each side, and are designated as the inferior, middle, and superior, the latter being the smallest of the three. The sinuses or spaces between these turbinated bones are called meatuses; so that the space between the floor of the nose and the lower turbinated bone is called the inferior meatus, the one between the lower and middle turbinated bones is the middle meatus, and the one between the middle and superior turbinated bones is the superior meatus.
| FIG. 11. |
| VERTICAL SECTION OF HEAD, SLIGHTLY DIAGRAMMATIC. |
| 1. Superior turbinated bone. 2. Middle turbinated bone. 3. Lower turbinated bone. 4. Floor of nasal cavity. 5. Vestibule. 6. Section of hyoid bone. 7. Ventricular band. 8. Vocal cord. 9 and 23. Section of thyroid cartilage. 10 and 24. Section of cricoid cartilage. 11. Section of first tracheal ring. 12. Frontal sinus. 13. Sphenoidal cells. 14. Pharyngeal opening of Eustachian tube. 15. Rosenmüller's groove. 16. Velum palati. 17. Tonsil. 18. Epiglottis. 19. Adipose tissue behind tongue. 20. Arytenoid cartilage. 21. Tubercle of epiglottis. 22. Section of arytenoid muscle. |
The nasal cavities are separated from each other by a septum or division wall composed of the perpendicular plate of the ethmoid bone and the vomer posteriorly and the cartilaginous septum anteriorly, thus presenting a smooth surface as the inner wall of each cavity. The floor is formed by the palatine process of the superior maxillary bone and by the palate bone, and runs in a slanting, downward direction from before backward. The roof is formed by the nasal bones and nasal spine of the frontal in front, in the middle by the cribriform plate of the ethmoid, and posteriorly by the under surface of the body of the sphenoid bone. Directly communicating with the nasal cavities are other cavities situated in the bones of the skull, the lining mucous membrane of which no doubt is largely affected by the pathological processes in nasal diseases: these are the antra of Highmore, large triangular cavities situated in the body of the superior maxillary bone and communicating with the nasal cavities by an irregularly-shaped opening in the middle meatus; then the frontal sinuses, two irregular cavities situated between the two tables of the frontal bone. The communication between them and the nasal cavities is established by the infundibulum, a round opening in the middle meatus, and finally the sphenoidal cells or sinuses, found in the body of the sphenoid bone, communicating with the nasal cavities by small openings in the superior meatus. That portion of the nasal cavities which projects beyond the end of the nasal bone is surrounded by cartilages forming the alæ of the nose.
In the cartilaginous septum of the lower animals we find a small cavity lined with mucous membrane, called after its discoverer Jacobson's organ, the minute anatomy of which has lately been described by Klein.18 This organ in man is, however, only rudimentary. The nasal cavities are lined with mucous membrane, which varies greatly in thickness in different localities, and which materially decreases the size of the cavities in the living subject from that seen in the denuded skull. This mucous membrane is covered by ciliated epithelium in man, with the exception of that portion which lines the vestibule—i.e. that portion of the cavity of the nose surrounded by cartilage only—which is covered by pavement epithelium.
18 Quarterly Journal of Mic. Science, January, 1881.
In the lower animals we find that in the olfactory region the ciliated epithelium is either absent, or that ciliated and non-ciliated epithelium alternates in patches.19 The author has not been able to find a statement in the literature on the subject as to the kind of epithelium found in the accessory cavities in man, but it is very probable that the mucous membrane of the frontal sinuses and the antra of Highmore is covered with ciliated epithelium; otherwise it would be difficult, if not impossible, for the secretions of that mucous membrane to pass through the narrow channels into the nasal cavities. The color of the normal nasal mucous membrane is of a light pink shade in what is termed the respiratory portion, while it is of a yellowish hue in the olfactory region, that portion of the mucous membrane which covers the roof and the outer walls of the nasal cavities down to the upper margin of the middle turbinated bone and the septum down to about the same level. It is in this region that the nerve-ends of the olfactory nerve are distributed. Immediately beneath the mucous membrane, and between it and the periosteum of the bony walls and the perichondrium of the cartilaginous portion of the septum, we find a tissue which bears a striking resemblance to the erectile tissue of the genital organs.20 It is composed of a network of fibrous tissue, the trabeculæ of which contain a few organic muscular fibres. Its meshes of various sizes and shapes are occupied by venous sinuses lined with endothelium. These are supplied with blood by small arterioles and capillaries, which are quite numerous in the fibrous tissue and can readily be demonstrated under the microscope. In this arrangement of elements of the nasal mucous membrane we find a ready explanation of the fact that liquids of greater or less density than the serum of the blood when introduced into the nasal cavities produce pain, for we have here the most favorable conditions for osmosis, which will cause either a contraction or a distension of the sinuses. In the larger masses of fibrous tissue between the sinuses or caverns we find imbedded the glands, with their ducts opening out between the epithelial cells of the mucous membrane. There are two kinds of glands in this region, which have been described by Klein21—viz. serous and mucous glands.
19 Haenle, Anatomy des Menschen, vol. ii.
20 Haenle, loc. cit.