A Treatise on Anatomy, Physiology, and Hygiene (Revised Edition), Calvin Cutter [adventure books to read txt] 📗
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865. What is the chief organ of taste? What other parts participate in the function? 866–870. Give the anatomy of the organs of taste. 866. Give the structure of the tongue. 867. Is this organ abundantly supplied with blood? From what source does the tongue derive its nerves?
Fig. 134.
Fig. 134. A view of one side of the neck, showing the nerves of the tongue. 1, A fragment of the temporal bone. 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, Muscles of the tongue, fauces, and neck. 5, The tongue. 13, The common carotid artery. 14, The jugular vein. 15, The external carotid. 16, The internal carotid. 17, The gustatory branch of the fifth pair of nerves. 20, The glosso-pharyngeal nerve. 21, The hypo-glossal, or the muscular nerve of the tongue. 24, The pneumogastric nerve. 25, The facial nerve.
868. What is the appearance of the surface of the tongue? Explain fig. 134.
868. The surface of the tongue is thickly studded with 386 fine papillæ, or vil´li, which give the organ a velvety appearance. These papillæ are of three varieties. The first is situated near the base of the tongue. They belong to the class of mucous follicles. They are larger than the others, and are called len-tic´u-lar, from being shaped like a lens. These, together with the tonsils, (sometimes called the almonds of the ears,) secrete mucus, to lubricate the food in the act of deglutition.
869. The instruments of taste are the two other sets of papillæ. One set consists of small, oval-shaped bodies, which are scattered over the whole surface of the tongue. They give it a rough appearance, and are called the fil´i-form papillæ.
870. The other set of papillæ is called the fun´gi-form. They are larger than the former, and consist of small, rounded heads, supported on short stalks, something in the shape of mushrooms, from which they derive their name. In the last two described sets of sensitive papillæ, the gustatory branch of the fifth pair of nerves ramifies.
Observation. By applying strong acids, as vinegar, to the tongue, with a hair pencil, these points will become curiously lengthened.
871. Taste is the sense which makes us acquainted with the savor of substances. When fluids are taken into the mouth, the papillæ dilate and erect themselves, and the particular impression excited is transmitted to the brain through 387 filaments of the gustatory nerve. This sense is closely connected with that of smell. The pleasures derived from it are strictly sensual and corporeal, and contribute in no way to the expansion of the mind, like those of hearing and seeing.
How many varieties of papillæ? Describe the first variety. What is the function of the lenticular papillæ? 869. Describe the filiform papillæ. 870. The fungiform papillæ? What nerve ramifies in the fungiform papillæ? How can these papillæ, or points, be seen? 871–875. Give the physiology of the organs of taste. 871. Define taste.
872. If dry, solid food is taken, the tongue carries it to the back side of the mouth, where it receives secretions from the salivary glands; the saliva, becoming impregnated with its flavor, flows over the sides of the tongue, and gives to the papillæ a perception of the savory juice; this impression is then communicated to the brain.
Observation. It is supposed that the salts which enter into the composition of the saliva, are very efficient agents in reducing substances to a proper state for making impressions on the nerves of taste. The fact that metals impart a peculiar taste, is owing to a galvanic shock, and not properly to what we understand by taste.
873. The primary use of taste is to guide animals in the selection of food, and to warn them against the introduction of noxious articles into the stomach. In all the inferior animals, we see that the original design of taste is still answered. But in man, this sense has been so abused and perverted, by the introduction of stimulants and condiments, and the endless admixture of different articles of food, that the simple action of this part seems to have been superseded almost entirely by acquired taste.
874. In children, this sense is usually acute, and their preference is for food of the mildest character. And it is also true, that every person has some peculiarities of taste, 388 or dislikes to particular articles of food. This may be either constitutional or from the influence of association.
With what sense is this closely connected? What is said of this sense? 872. Give the process by which we taste substances. How can we account for the taste of metals when applied to the tongue? 873. What is the primary use of taste? Where do we see it perverted? 874. How is this sense in children? What is true of every person in reference to taste?
Observation. This sense has been made to vary more than any other by the refinements of social life. Thus, the Indian’s like or dislike to particular kinds of food, generally extends to every person of the same tribe; but among civilized men, no two individuals can be found alike in all their tastes.
875. This sense is modified by habit, and not unfrequently those articles, which at first were disgusting, become highly agreeable by persevering in the use of them. By cultivation, this sense may be made very acute. Those persons whose business leads them to judge of the quality of an article by their taste, can discriminate shades of flavor not perceivable by ordinary persons. Epicures, and tasters of wines and teas, afford examples.
Observation. Many persons impair their taste by bad habits, as chewing and smoking tobacco, and using stimulating drinks, and pungent condiments with the food. These indulgences lessen the sensibility of the nerve, and destroy the natural relish for food.
What is true of the Indian? 875. Is this sense modified by habit? Give instances. How is this sense sometimes impaired?
876. This sense is located in the air-passages of the Nose. To understand the function of smell, the structure of the nose and nasal cavities, with the distribution of the olfactory nerves, must be first examined.
877. The NOSE is composed of the Bones, Fi´bro-car´tilages, and Mu´cous Mem´brane, together with its integuments.
878. The BONES of the nose are the nasal, and the nasal processes of the upper jaw.
879. The FIBRO-CARTILAGES give form and stability to the framework of the nose, providing at the same time, by their elasticity, against injuries. They are five in number.
880. The MUCOUS MEMBRANE, which lines the interior of the nose, is continuous with the skin externally, and with the lining membrane of the parts of the throat. The entrance of the nostrils is provided with numerous hairs, which serve as guardians to the delicate membrane of the nose.
881. The NASAL FOSSÆ, or nostrils, are two irregular, compressed cavities, extending from the nose to the pharynx. These cavities are bounded superiorly by the sphenoid and 390 ethmoid bones; inferiorly, by the hard palate. In the middle line they are separated from each other by a bony and fibro-cartilaginous septum; upon the outer wall of each fossa, in the dried skull, are three projecting processes, termed spongy bones. In the fresh fossa, these are covered by a mucous membrane.
876. Where is the sense of smell located? 877–884. Give the anatomy of the organs of smell. 877. Name the parts that enter into the structure of the nose? 878. What bones form the framework of the nose? 879. What is the use of the cartilages? 880. What relation has the mucous membrane with other membranes of the nose? 881. Describe the nasal cavities.
882. The space that intervenes between the superior and middle spongy bone, is called the superior me-a´tus, or channel; the space between the middle and inferior bone, is the middle meatus; and that between the inferior bone and the floor of the fossa, is the inferior meatus.
Fig. 135.
Fig. 135. A vertical section of the middle part of the nasal cavities. 7, The middle spongy bones. 8, The superior part of the nasal cavities. 10, The inferior spongy bones. 11, The vomer. 12, The upper jaw. 13. The middle channel of the nose. 14, The lower channel of the nose. 17, The palatine process of the upper jaw-bone. 18, The roof of the mouth covered by mucous membrane. 19, A section of this membrane.
883. The MEATUSES are passages that extend backward, from the nostrils, into which are several openings. They are lined by a mucous membrane, called the pi-tu´i-ta-ry, or schneiderian, from 391 Schneider, who first showed that the secretion of the nasal fossæ proceeded from the mucous membrane, and not from the brain.
882. What terms are applied to the spaces between these processes? What does fig. 135 represent? 883. Define the meatuses. By what are they lined?
884. Upon the mucous membrane of the nasal passages, the olfactory nerve ramifies, and also a branch of the fifth pair of nerves. This membrane is of considerable extent in man; and in those animals whose sense of smell is very acute, it is still more extensive.
Fig. 136.
Fig. 136. A side view of the passage of the nostrils, and the distribution of the olfactory nerve. 4, The olfactory nerve. 5, The fine and curious divisions of this nerve on the membrane of the nose. 6, A branch of the fifth pair of nerves.
885. The sense of smell enables us to discern the odor or scent of any thing. When substances are presented to the nose, the air that is passing through the nostrils brings the odoriferous particles of matter in contact with the filaments of the olfactory nerves, that are spread upon the membrane 392 that lines the air-passages, and the impression is then transmitted to the brain.
884. What nerves ramify upon this membrane? What is represented by fig. 136? 885–899. Give the physiology of the organs of smell. 885. How does the mind become sensible of odoriferous particles?
886. This sense, with that of taste, aids man as well as the inferior animals, in selecting proper food, and it also gives us pleasure by the inhalation of agreeable odors. The sense of smell, like that of taste and touch, may be improved by cultivation. It likewise varies in different persons.
Observation. Sometimes this sense seems to possess a morbid degree of acuteness in respect to odors, which is highly inconvenient and even dangerous. With some individuals, the smell of certain fruits, flowers, cheese, &c., produce nausea and even convulsions.
887. In the inferior animals generally, the sense of smell is more acute than in man. Thus the bloodhound will track the hare over the ground for miles, guided only by the odor that it leaves in its flight. He also traces the progress of his master through thickly-crowded streets, distinguishing his footsteps from those of a thousand others, and amidst the odorous particles emanating from a thousand sources.
Observation. In some of the higher orders of the inferior animals, there is an astonishing acuteness of smell in regard to effluvia that come from living animals. To these animals, it possesses an importance in them far beyond what it has in man, by making them acquainted with the presence of their enemies or their prey, when the eye and ear are incapable of acting. It is related by travellers in Africa,
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