Changes

*The auditory ossicles are attached to the wall of the tympanic cavity by many ligaments and mucosal folds.

*The auditory ossicles are attached to the wall of the tympanic cavity by many ligaments and mucosal folds.

*The tympanic cavity is located within the petrous temporal bone, and can be divided into dorsal, middle and ventral parts:

*The tympanic cavity is located within the petrous temporal bone, and can be divided into dorsal, middle and ventral parts:

- ''Dorsal'': or '''epitympanum''', conatining 2 of the auditory ossicles – the '''malleus''' and '''incus'''

- ''Dorsal'': or '''epitympanum''', conatining 2 of the auditory ossicles – the '''malleus''' and '''incus'''

- ''Ventral'': or '''hypotympanum''', or fundic cavity, which is the largest compartment. It is housed by the tympanic bulla which is a thin-walled, bulbous expansion of the temporal bone.

- ''Ventral'': or '''hypotympanum''', or fundic cavity, which is the largest compartment. It is housed by the tympanic bulla which is a thin-walled, bulbous expansion of the temporal bone.

*The oval window is positioned rostrodorsally, to which one end of the stapes is attached by an annular ligament. It functions to connect the tympanic cavity with the inner ear.

*The oval window is positioned rostrodorsally, to which one end of the stapes is attached by an annular ligament. It functions to connect the tympanic cavity with the inner ear.

[[image: Canine Ear Canal.jpg|thumb|250px|right|The Canine Middle Ear]]

[[image: Canine Ear Canal.jpg|thumb|250px|right|The Canine Middle Ear]]

The auditory ossicles are supported by ligaments and muscles, which alter their position and influences the tension of the tympanic membrane.  The ratio of the malleus:incus in dogs and cats is 2-3 times that of man, and may explain the increased acuity of hearing.  Opposite the lateral tympanic membrane on the medial aspect of the cavity is a bony promontory.  Associated structures close to or in channels in the wall of the tympanic cavity (bulla) are the '''facial nerve''', '''vagus nerve''' and branches of the '''carotid and lingual arteries'''.  Post-ganglionic fibres of the '''cervical sympathetic trunk''' run in the region of the dorsomedial wall of the tympanic cavity.

The auditory ossicles are supported by ligaments and muscles, which alter their position and influences the tension of the tympanic membrane.  The ratio of the malleus:incus in dogs and cats is 2-3 times that of man, and may explain the increased acuity of hearing.  Opposite the lateral tympanic membrane on the medial aspect of the cavity is a bony promontory.  Associated structures close to or in channels in the wall of the tympanic cavity (bulla) are the '''facial nerve''', '''vagus nerve''' and branches of the '''carotid and lingual arteries'''.  Post-ganglionic fibres of the '''cervical sympathetic trunk''' run in the region of the dorsomedial wall of the tympanic cavity.