Auditory canal

“ If the auditory canal be very small there may not be sufficient room to insert the instruments through the speculum. In such cases, if there be no middle-ear suppuration, it is wiser to leave the condition alone. If, however, suppuration exists, either the conservative treatment must be continued or the complete mastoid operation recommended.
2. Hæmorrhage, especially on curetting away the granulations, may be sufficient to prevent a view of the deeper parts. It can, however, usually be arrested quickly by plugging the auditory canal with gauze soaked in adrenalin and cocaine solution. ”

“ If the stricture or point of occlusion of the auditory canal is limited and composed of membranous and fibrous tissues, a good result can be usually obtained, and there is no reason why complete recovery of hearing should not take place if the labyrinth and tympanic cavity are normal. ”

“ The external ear consists of an expanded portion known as the pinna or auricle, and of a passage, the auditory canal or meatus, leading inwards from it. The surface of the auricle is convoluted to collect and transmit the vibrations of air by which sound is produced the auditory canal conducts these vibrations to the tympanic membrane. Many animals move the auricle in the direction of the sound. Thus the horse pricks up its ears when it hears a noise, the better to judge of the direction of sounds. ”

“ The auricle of the human ear presents many irregularities of surface. If these irregularities are abolished by filling them up with a soft material such as wax or oil, leaving the entrance to the canal free, experiment shows that the intensity of sounds is weakened, and that there is more difficulty in judging of their direction. When waves of sound strike the auricle, they are partly reflected outwards, while the remainder, impinging at various angles, undergo a number of reflections so as to be directed into the auditory canal. ”

“ Probably all the laity, so to speak, when first they realize that their hearing is diminished, believe that the wax has accumulated and has blocked the auditory canal. The sensation to them is certainly one of obstruction, and they seem justified in picking at the canal of the ear in attempting to remove the obstructing substance. ”

“ If the patient before operation hears conversation at a greater distance than 12 feet he should be told that the hearing power may be reduced to this amount. If, however, there be considerable deafness, due to polypi or granulations blocking up the tympanic cavity and auditory canal, the hearing power may be improved by the operation. The ultimate hearing depends on the condition of the stapes within the fenestra ovalis: if it remains freely movable, the hearing power may be extremely good. ”

“ With successive sharp taps of the mallet, the gouge is made to cut through the pedicle, care being taken that the instrument is not driven in too deeply, on to the tympanic membrane.
The growth, which can now be felt to be movable within the meatus, can usually be removed by grasping it between the blades of forceps, or can be expelled by syringing the ear. After its removal the auditory canal should be plugged for a few minutes with a solution of cocaine and adrenalin chloride. ”

“ We all have our limits, and that limit may be quickly found by these whistles in every case. The facility of hearing shrill sounds depends in some degree on the position of the whistle, for it is highest when it is held exactly opposite the opening of the ear. Any roughness of the lining of the auditory canal appears to have a marked effect in checking the transmission of rapid vibrations when they strike the ear obliquely. ”

“ This concha makes a curve much like the curve a deaf man makes with his hand behind his ear to catch the sound. Animals often have to raise their ears to catch the sound well, but ours stand always ready. When the air-waves have passed in at the hole of your ear, they move all the air in the passage, which is called the auditory, or hearing, canal. This canal is lined with little hairs to keep out insects and dust, and the wax which collects in it serves the same purpose. But is too much wax collects, it prevents the air from playing well upon the drum, and therefore makes you deaf. ”

“ The external auditory meatus, the passage to the middle ear, is curved and is about an inch and a quarter long. Near its outer portion are a number of fine hairs slanting outwards to prevent the entrance of insects. Embedded in the deeper parts of the canal are glands which secrete the cerumen, or ear-wax, which keeps the canal moist, and helps to protect it against foreign bodies and insects. ”

“ The gill-sacs, seven in number, open externally by separate orifices, but internally they open into a median branchial canal, situated below the oesophagus and opening into the mouth in front. There is a well-developed branchial basket. Dorsal arcualia are present throughout the precaudal as well as in the caudal region. A rudimentary spiral valve is present. The brain consists of parts usually present in other Craniates, including cerebral hemispheres and a cerebellum. The auditory organ {426}has two semicircular canals, and the eyes are not degenerate. ”

“ Injury to the anterior canal causes diagonal rolling of the eyeball. In destruction of all the canals various pendulum-like movements are performed, and standing often becomes impossible. Stimulation of one auditory nerve is followed by rotation of the eye and rotation 73of the body on its axis toward the injured side. The passage of a galvanic current through the head between the mastoid processes, or from one external auditory meatus to the other, causes rolling of the eyeballs. ”

“ Across the end of this canal, a membrane or skin called the tympanum is stretched, like the parchment over the head of a drum, and it is this membrane which moves to and fro as the air-waves strike on it. A violent box on the ear will sometimes break this delicate membrane, or injure it, and therefore it is very wrong to hit a person violently on the ear. ”

“ If this process is going on in the same medium (the air) in which our ear is situated, the membrane will at every condensation be forced toward the hollow of the drum, and at every rarefaction will move itself in the opposite direction.
These vibrations necessitate a similar motion of the auditory ossicles, and thereby a transference to the auditory nerves is effected.
The greater the condensation of a sound-conducting medium at any given moment, the greater also will be the amplitude of vibration of the membrane and of the auditory ossicles and of their action ”

“ The semicircular canals have been much studied by the physiologists. They found that injury to these structures brought lack of equilibrium and inability to walk, swim or fly in a straight course. If, for example, the horizontal canal in the left ear is destroyed, the animal continually deviates to the left as he advances, and so is forced into a "circus movement". They found that the compensatory movements normally made in reaction to a movement impressed on the animal from without were no longer made when the canals were destroyed. ”

“ From the stomach or its pouches arise sixteen radial canals, four perradial, four interradial and eight adradial (fig. 2b) . The perradial and interradial canals consist of a main stem giving off branches, and both stem and branches reach to the marginal ring-canal, the main stem ending in one of the eight tentaculocysts, which are lodged in the notches between the lobes of the umbrellar margin. The adradial canals are unbranched and run to the middle point of one of the marginal lobes. The system of canals shows great variation even in the same species. ”

“ These physical agitations or vibrations are transmitted to the air. Omitting the account of the anatomical path by which they reach the inner ear, we find them at last setting up vibrations in a many-fibred membrane, the basilar membrane, which is in direct connection with the ends of the auditory nerve. It is supposed that to every possible rate of vibration, that is, every possible tone, or partial tone, there corresponds a fibre of the basilar membrane fitted by its length to vibrate synchronously with the original wave-elements. The complex wave is thus analyzed into its constituents. ”

“ After the fundamental fact that such curious phenomena as the canals are visible is the scarcely less important one that they are not always so. At times the canals are invisible, and this invisibility is real, not apparent; that is, it is not an invisibility due to distance or obscuration of any kind between us and them, but an actual invisibility due to the condition of the canal itself. With our present optical means, at certain seasons they cease to exist. ”

“ How many there may be it is not possible to state, as the better the seeing, the more of them there seem to be. In spite, however, of their great number, there is no instance of one unconnected with a canal. What is more, there is apparently none that does not lie at the junction of several canals. Reversely, all the junctions appear to be provided with spots. Plotted upon a globe they and their connecting canals make a most curious network over all the orange-ochre equatorial parts of the planet, a mass of lines and knots, the one marking being as omnipresent as the other. ”

“ A Professor Douglass, of Arizona, has lately suggested that the canals are nothing but the black rays that can be seen radiating from a black spot, on a light ground, when looked at with a small screen placed in front of the pupil of the eye, so that the light enters only around the edges. According to Professor Douglass, the black oases are the only real things in the canal system, while the canals themselves have no tangible existence, and are nothing more than these black rays issuing from the dark spots. ”

“ If your hearing is perfect, the best way to take care of the ears is to let them alone. Never try to dig into the canal that leads to the middle ear. The ears must of course be washed to keep them clean, but in washing the ear you should not touch the delicate canal leading to the drum. ”

“ In a series of experiments interesting enough but barren of utility, the water of a canal, river, or bay has often served as a conductor for the telegraph. Among the electricians who have thus impressed water into their service was Professor Morse. In 1842 he sent a few signals across the channel from Castle Garden, New York, to Governor's Island, a distance of a mile. With much better results, he sent messages, later in the same year, from one side of the canal at Washington to the other, a distance of eighty feet, employing large copper plates at each terminal. ”

“ It would, therefore, be no matter of surprise if more powerful instruments should, in moments of perfect seeing, reveal numerous apparent gaps in the lines. So far from proving they were not canals, such gaps are exactly what we should expect to find in connection with canals; and the lines would probably appear as irregular light and dark patches in alignment, because we do not see the canals themselves, but only the vegetation on the land which they traverse. Probably there are also many oases yet to be discovered along the canal lines. ”

“ The function of the organs of hearing, therefore, is to impart faithfully to the auditory nerve, every condensation and rarefaction occurring in the surrounding medium. The function of the auditory nerve is to bring to our consciousness the vibrations of matter resulting at the given time, both according to their number and their magnitude. Here, first, certain combinations acquire a distinct name: here, first the vibrations become musical tones or discords (Misstöne) . ”

“ In this instrument the idea of the human ear is still carried out. The tin funnel, with its flaring embouchure, still represents the auditory tube and pinna. The tympanum, no longer at the very end of the tube, is strained across a circular aperture in the lid. Upon it rests the strip of platinum foil which serves as an electrode, and resting in loose contact with this lies the little angular piece of metal which Reis called the “Hämmerchen.” ”

“ This deep-sea sounding is a very necessary feature of cable laying, as unexpected depths of water or unlooked for changes in submarine geography, when not taken into account, might prove disastrous to the cable being laid. The sounding apparatus is of great interest, being a compact little affair consisting of a small engine that with a self-acting brake helps regulate the wire sounding-line as it is lowered into the water, and after sounding heaves it up again. ”

“ By every condensation the tympanum of our ear is pressed inwards, by every rarefaction it is pressed outward and thus the tympanum performs oscillations like a pendulum. The smaller or greater number of the oscillations made in a second gives us by help of the small bones in our ear and the auditory nerve the idea of a higher or lower tune. ”

“ This is best accomplished by forcing air up the Eustachian tube and through the middle ear by either the Politzer or Valsalva method of inflation. The fluids thus forced out into the external canal can be removed by the use either of warm water and the syringe if large in amount, or by cotton on a cotton-holder if small in quantity: the latter plan is less irritating, and also completely dries the external canal. No local application ought to be made as long as any pain exists. ”