Auditory nerve

“ It is not the mere motion in the auditory organs which produces the sensation of sound; the nerve certainly perceives each movement in the ears, because none is possible apart from or without primary motion; only such a motion is no sound, but only a noise. What has been written in the tingling metal according to eternal laws, is transcribed or copied in the auditory nerve ”

“ The nerve which is concerned with the adjustment of the position of the body is a constituent of the auditory nerve. It comes from the semicircular canals. Never under any circumstances do the impulses which originate in these organs of orientation enter consciousness; but when a ship begins to roll, or worse, to heave, they churn up the gray matter of the hind-brain until its conductivity is so affected as to demonstrate their urgency beyond misunderstanding. ”

“ We know how the ear receives air-vibrations, how it collects and conducts them to the auditory nerves, carefully protecting itself, by the action of beautifully ordered springs and cushions, from the effects of vibrations violent enough to be dangerous to its own integrity. But even [132] when we have followed vibrations as far as the nerve, and recognised the subtle variation of its own substance by which the nerve conducts the impression of them to the brain, we have no inkling of the means by which the phenomenon of consciousness which we call “mind” is produced. ”

“ The sonorous figures are formed in the auditory organ, and even in the auditory nerves, just as they have been represented upon an infinitely small scale in the air. The nerve becomes in hearing a sonorous figure. ”

“ It may be cured, particularly at its commencement, by the application of such stimulants as are capable of exciting a discharge from the ceruminous glands; for which purpose thev should be introduced into the meatus auditorius.
In some cases of this kind, where the auditory nerve has been in some degree torpid, or rather perhaps where there has been a kind of paralysis, or want of action, in the muscles which brace the membrane of the tympanum, and keep the chain of bones in their proper state; a person has not been able to hear, except during a considerable noise. ”

“ How the auditory nerve transmits its impressions is not a matter of demonstration, but the probability is great that it transmits them as it receives them as impulses of motion waves of force that are conveyed to the brain and expended in the production of those physical motions which are the material conditions and accompaniments of consciousness. ”

“ Apart from increased resonance of the ear, or hyperaesthesia of the auditory nerve, producing special sensitiveness to sounds, an increased flow of blood through the ear, as well as muscular contractions and mucous plugs in the external ear, furnish the faint rudimentary noises which, in sleep, may constitute the nucleus around which hallucinations crystallise. ”

“ This observation may throw some light on the medical treatment of deaf people; as it may be learnt from their dreams whether the auditory nerve be paralytic, or their deafness be owing to some defect of the external organ. ”

“ When a bad smell causes a grimace, there is a reflex action through the same motor nerve, while the olfactory nerves constitute the afferent channels. In these cases, therefore, reflex action must be effected through the brain, all the nerves involved being cerebral. 'When the whole body starts at a loud noise, the afferent auditory nerve gives rise to an impulse which passes to the medulla oblongata, and thence affects the great majority of the motor nerves of the body. ”

“ Each afferent nerve comes from a determinate part of the periphery and is played upon and excited to its inward activity by a particular force of the outer world. Usually it is insensible to other forces: thus the optic nerves are not impressible by air-waves, nor those of the skin by light-waves. The lingual nerve is not excited by aromatic effluvia, the auditory nerve is unaffected by heat. Each selects from the vibrations of the outer world some one rate to which it responds exclusively. ”

“ The structure of the human ear is much more complicated than is generally supposed. It is an apparatus constructed to respond to the waves of sound. As a whole, it may be considered a peculiar form of nerve-ending.
The external ear forms only a part of a most elaborate apparatus whereby sound waves may be transmitted inwards to the real organ of hearing. The really sensitive part of the ear, in which the auditory nerve ends, is buried for protection deep out of sight in the bones of the head ”

“ The outer ear collects the vibrations, the middle ear conducts them, and the internal converts them into a special physiological condition of the hair-cells and the auditory nerve. This condition is communicated to the other links in the anatomical hearing chain, until the highest part of the brain, or cortex, is reached. Hearing, from the physiological point of view, is the outcome of a series of processes having their development in a corresponding series of centres, or collections of nerve-cells. ”

“ The internal ear is formed by an involution of the integument, and not by an outgrowth of the brain. But tissue, in connexion with it, becomes in part changed, thus forming the auditory nerve, which places the tegumentary sac in direct communication with the brain itself. ”

“ At most the high note is felt as a thinner, brighter streak against a darker background. In an article on Space, published in the Journal of Speculative Philosophy for January, 1879, I ventured to suggest that possibly the auditory nerve termini might be "excited all at once by sounds of any pitch, as the whole retina would be by every luminous point if there were no dioptric apparatus affixed." ”

“ The suspension of the operations of the senses is not therefore due to any loss of function in the optic nerve, the [Pg 63] auditory nerve, the olfactory nerve, the gustatory nerve, or the cranial or spinal nerves concerned in the sense of touch, but solely to the inability of the brain to take cognizance of the impressions conveyed to it. In regard to the cause of this torpor, I have given my views in a previous chapter. ”

“ If any one in the dark presses the ball of his eye, by applying his finger to the external corner of it, a luminous appearance is observed; and by a smart stroke on the eye great slashes of fire are perceived. (Newton's Optics.) So that when the arteries, that are near the auditory nerve, make stronger pulsations than usual, as in some fevers, an undulating sound is excited in the ears. Hence it is not the presence of the light and sound, but the motions of the organ, that are immediately necessary to constitute the perception or idea of light and sound. ”

“ On the supposition that the anterior root serves the muscular sense, we have no right to expect anything than what we find. The muscular sensations are as special as those of sight or hearing, and every special sense responds only in its special form: the optic nerve, when irritated, produces sensation of light, but no pain; the auditory nerve a sensation of sound, but none of temperature, light, or pain. ”

“ Communication exists externally with the middle ear by the round and oval windows and internally with the internal auditory canal, through which passes the eighth cranial or auditory nerve, the special nerve of hearing, which is distributed to the inner ear only. ”

“ From the membrane vibrations pass along the chain of bones, (3, 4, 5.) The bone 5 communicates with the internal ear, (7, 8, 9, 10, 11, 11, 11, 12, 12, 12.) From the internal ear the impression is transmitted to the brain by the nerve, (13.)
971. The auditory nerve, like the optic, has but one function, that of special sensibility. The nerves which furnish the ear with ordinary sensibility, proceed from the fifth pair.
HYGIENE OF THE ORGANS OF HEARING.
972. Hearing, like the other senses, is capable of very great improvement. ”

“ Connexions can be traced to the optic tract, the higher visual centre on the mesial surface of the occipital lobe, the deep origin of the third or oculo-motor nerve as well as to the mesial and lateral fillet. The inferior pair of quadrigeminal bodies are more closely in touch with the organs of hearing, and are connected by the lateral fillet with the cochlear nucleus of the auditory nerve. ”

“ Thus, when a feeling resulting from a disturbance in the optic nerve is interpreted as one of external light vaguely felt to be acting on the eye, or one resulting from some action set up in the auditory fibre as a sensation of external sound vaguely felt to be entering the ear, we see that the error of localization is a consequence of the other error already characterized.
As I have already observed, an excitation of a nerve at any other point than the peripheral termi [Pg 62] nation, occurs but rarely in normal life. ”

“ The case is different with motor nerves, with those of the sympathetic system, and with (what is more to our purpose) nerves of sensation. It seems clear that mechanical injuries, or even touches, excite them in the direction of their own special functions. Auditory nerves feel a shock as a sound,—optic nerves receive it as a sudden and brilliant light. We are doubly assured from these effects of the true functions belonging to the several sets of nerves. Disease and injury are great discoverers of what ought to be healthy susceptibilities. ”

“ Except the auditory nerve, all have a greater consistence at their origin than these last. 4th. They adhere but little to the corresponding cerebral portion, so that they are almost always raised in detaching the pia mater; thus it requires great precaution, to prevent breaking the nerves from the brain when it is taken out of the skull. The adhesion of the pathetic, the motores communes and the facial, is particularly weak. We should almost say, from a slight examination, that there was only contiguity.
The spinal marrow gives origin to thirty or thirty-one pair of nerves, viz. ”

“ The parts which intervene between the optic and auditory nerves, being proportionably less, for instance, in brutes, will not admit of so great a variety of associations between the several ideas of these senses, because the optic and auditory nerves cannot have so great a variety of connexions and communications with each other. ”