[Anatomy and physiology of the human eye].

tory canal. The external auditory canal then channels the vibration toward the eardrum, or tympanic membrane (TM). This in turn causes the eardrum to vibrate, which sets into motion the mechanical structures of the middle ear. The middle ear ossicles, or middle ear bones. These 3 tiny bones are attached to the TM and move as it moves. They transmit the sound waves further along the auditory chain to the inner ear. This motion is processed in the inner ear via mobilization of sensory membranes and their associated sensory hair cells. The hair cells of the inner ear convert the mechanical movement into a representative nerve impulse. Finally, the nerves associated with hearing transmit this stimulation to the brain for interpretation (Figure 4-1). Although this description sounds fairly straightforward, the anatomy and complexity of the transformation of a simple vibration to interpretation of a sound signal is not simple at all.