The outer ear cannel is separated from the middle ear by a thin membrane called the eardrum or tympanic membrane. The ear drum is very fragile and can be damaged by ear disease or during ear cleaning. The inner ear connects to the brain and contains nerves and centers for balance and hearing. The following picture shows a diagram of the right ear as it appears if you are looking at the dog's head from the front. A CT scan of the head is pictured on the right.
Dogs have many more ear problems than cats.
Dogs with heavy floppy ears have the most problems with ear infections. Some breeds have lots of hair in and around the ear canal which causes them to develop ear infections. Dogs that spend lots of time in the water also are prone to developing ear infections. Dogs with skin allergies may have ear problems as part of the allergy. The outer ear flap is usually covered with fur.