Part 1: Ear

The ears, specifically the internal ear, house the receptors for the special senses of hearing and balance, which are extraordinary in the cat. The ear consists of three anatomically and functionally distinct parts: the external ear, the middle ear, and the internal ear. The auricle includes a number of ridges and prominences that give the ear base its distinct appearance. The inner surface of the initial part of the external ear canal has numerous prominent ridges with furrows between them. The long, narrow scutiform cartilage, although not forming part of the external ear, is closely connected with it. The middle ear includes the tympanic membrane, the tympanic cavity and its contents, and the auditory tube. The pars tympanica makes up the lateral wall and surrounds the opening of the osseous external auditory meatus. The air-filled space of the tympanic cavity communicates via the auditory tube with the nasopharynx to maintain equal pressure on either side of the tympanic membrane.