Prof. Andrew Leisewitz
BVSc, MMedVet(Med), PhD
Dept. of Comp. Animal Clinical Studies
Faculty of Veterinary Science
The external ear consists of the external acoustic meatus which collects and locates the origin of sounds. The middle ear consists of the tympanic membrane, the ossicles, the auditory tube, and the tympanic cavity. It serves to transducer incoming airborne sound waves into waves in a liquid medium. The inner ear consists of the cochlea, the vestibule, and the semicircular canals. These structures relate the head to gravity, allowing the visual system to compensate for movement and to perceive both linear and rotational acceleration.
The tympanum is a thin, semitransparent membrane with a rounded elliptical outline. The shorter dimension is nearly vertical. The long axis is directed ventral, medial and cranial. The feline tympanum is more circular and smaller. The majority of the external surface is rough, thin and glistening (the pars tensa) with the outline of the manubrium of the malleus being clearly visible. The manubrium exerts tension on the tympanum giving it a concave shape as seen from the outside (like the speaker cone of a loudspeaker). The pars flaccida is more opaque, pink, or white in colour. It is confined to the upper quadrant of the membrane.