This intricate leverage mechanism corrects the impedance mismatch between gas and liquid allowing airborne sound waves to move hair cells in the fluid-filled cochlea, generating neural signals that are transmitted to the auditory cortex via the cochlear nerve. The middle ear ossicles connect the TM to the much smaller oval window of the inner ear. The pinna or auricle directs sound waves into the external auditory Meatus (EAM), which then funnels sound waves toward the ear drum or tympanic membrane (TM), causing it to displace and move the ossicular chain of bones in the air-filled middle ear. The mammalian ear is a crucial and fascinating sensory organ formed from the integration of three parts ( Figure 1). That we can “hear” these waveforms involves a complex array of neurophysiological mechanisms which begin at the outer ear and end at the auditory cortex.
#Opening of auditory tube series
Sound is essentially a series of pressure waves in our airborne environment. Hearing places us within our external environment, allowing us to experience a multi-dimensional world, to listen and to communicate. Together this knowledge allows clinical questions to be approached from a developmental biology perspective. Here we review our current understanding of ear canal development how this biological lumen is made what determines its location and how its structure is maintained throughout life. Recent studies have built on decades-old knowledge of ear canal development and suggest a novel multi-stage, complex and integrated system of development, helping to explain the mechanisms underlying congenital canal atresia and stenosis. Defects in development, or later blockages in the canal, lead to congenital or acquired conductive hearing loss.
Unique anatomical adaptations, such as its migrating epithelium and cerumen glands, equip the ear canal for its function as both a conduit and a cul-de-sac. Within our complex hearing pathway, the ear canal is responsible for funneling sound waves toward the tympanic membrane (ear drum) and into the middle ear, and as such is a physical link between the tympanic membrane and the outside world. This review focuses on the often-neglected outer ear, specifically the external auditory meatus (EAM), or ear canal. The mammalian ear is made up of three parts (the outer, middle, and inner ear), which work together to transmit sound waves into neuronal signals perceived by our auditory cortex as sound.
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