Ears
Marie Lyons, Arvind Singh in Your First ENT Job, 2018
The external ear consists of the pinna and the outer ear canal (seeFigure 1.1). The outer third of the ear canal is cartilaginous, hair-bearing and wax-producing. It is also not particularly sensitive, which makes it relatively easy to inspect with an auroscope. The inner third is bony and exquisitely sensitive. Push too deep into the bony ear canal and the patient will certainly protest! The outer ear canal ends at the eardrum, which in a healthy ear is a pale grey structure (seeFigure 1.2). The most obvious features are the handle of the malleus and antero-inferiorly the cone of light (see below). When you are shown a picture of the eardrum you can always identify which side it is on by the direction in which the malleus is pointing. If the eardrum is on the right side, the malleus will point upwards and superiorly to the right from the middle of the eardrum. If it is on the left side, the malleus will point to the left (amaze your boss at quizzes!).
Anatomy
Stanley A. Gelfand in Hearing, 2017
The major divisions of the ear are shown in Figure 2.2, and their relative positions within the head are given in Figure 2.3. The outer ear is made up of the pinna (auricle) and ear canal (external auditory meatus). The eardrum (tympanic membrane) separates the outer and middle ears, and is generally considered to be part of the latter. The middle ear also includes the tympanic (middle ear) cavity; the ossicular chain with its associated muscles, tendons, and ligaments; and the eustachian (auditory) tube. The inner ear begins at the oval window. It includes the sensory organs of hearing (the cochlea) and of balance (the semicircular canals, utricle, and saccule). While the balance system is certainly important, the concern here is hearing, and accordingly the balance apparatus is mentioned only insofar as it is directly associated with the auditory system.
Hearing
Patrick Rabbitt in The Aging Mind, 2019
We hear by detecting tiny fast vibrations in air pressure. These are funnelled by the elaborate whorled outer ear, the pinna, which focusses their energy along the auditory canal to reach the eardrum. Humans underestimate the value of having an outer ear because, within the range of ear sizes that our species currently grows, large external pinnae do not bring obvious gains in sound detection to compensate for their possible inconveniences. If Prince Charles still has exceptionally acute hearing, his outstanding pinnae are not responsible. Nevertheless, people with damaged outer ears do lose some sensitivity and, especially, find it harder to recognise where, in the space about them, sounds come from. The large, elaborate and delightful outer ears of foxes who live by locating rabbit-rustling, and of rabbits who survive by detecting fox-creeping, show how useful large and mobile pinnae can be for collecting and channelling sound. The charming ear-twitches of foxes and dogs also show that partially rotatable pinnae can be an advantage in checking a sound direction and in maximising the sound available. Few humans can furl and twist their ears, but we do manage, though less well than dogs and foxes, to get fixes on faint noises by turning our heads about.
Otic drug delivery systems: formulation principles and recent developments
Published in Drug Development and Industrial Pharmacy, 2018
Xu Liu, Mingshuang Li, Hugh Smyth, Feng Zhang
The human ear consists of three major parts: the outer ear, the middle ear, and the inner ear (Figure 1). The outer ear extends from the auricle, or pinna, along the ear canal and ends at the tympanic membrane (eardrum). A healthy ear canal is slightly acidic, with a pH value between 5.0 and 5.7, which can inhibit bacterial growth [41,42]. At the end of the ear canal lies the tympanic membrane, which separates the middle ear from the outer ear. The middle ear includes the ossicular chain, which consists of the malleus, incus, stapes, and a mucosal lining that keeps the middle ear environment moist. The Eustachian tube provides a conduit between the middle ear and the upper airway to allow for equalization of middle ear pressure [43].
Emerging therapies for human hearing loss
Published in Expert Opinion on Biological Therapy, 2022
Elise Ajay, Niliksha Gunewardene, Rachael Richardson
The peripheral hearing pathway begins at the outer ear where the pinna picks up sound waves and funnels them through the ear canal to vibrate the eardrum. The motion of the eardrum is mechanically transmitted through the middle ear via the ossicles, with the smallest of these bones, the stapes, connected to the cochlea of the inner ear via the oval window membrane. The movement of the oval window translates to vibration of the basilar membrane. This motion stimulates the cochlear hair cells, generating nerve impulses in spiral ganglion neurons which transmit to the auditory cortex via the brainstem. The sensorineural and structural elements of the cochlea and the ascending auditory pathway are shown in Figure 1.
Hearing health information in Malaysian public schools: a step towards addressing a public health concern
Published in International Journal of Audiology, 2021
Nur Amirah Zakaria, Nashrah Maamor, Nor Haniza Abdul Wahat
Defects of hearing occur when the sense of hearing of a person does not function well. Defects of hearing are normally caused by damage to the ear due to infection by microorganisms, injury, the ageing process or continuous exposure to loud sounds. Damages to the outer ear and middle ear can be corrected easily. For example, the clearing of foreign objects in the ear canal. Punctured eardrum and damaged ossicles can also be corrected using medicine or surgery. Damage to the inner ear is more difficult to correct.