The ear is divided into three portions: the outer, the middle, and the inner ear. The outer ear is the visible portion that can be a strong indicator of the general mood of your horse, a tip-off as to where its attention is directed, and even a sentinel to a well-timed kick. The outer ear is also called the auricle or pinna—the word auricular often refers to the ear or structures associated with it. The stiffness and shape of the outer ear are created by a large amount of cartilage. In fact, most of the outer ear is made up of cartilage with its thin covering of skin and muscles attaching to the base. The ear canal in the horse is long and generally does not allow the examination of the ear drum as can be done in people and other smaller animals. The ear drum—technically called the tympanic membrane—lies at the end of the ear canal; it is the membrane that picks up sound waves and starts the process of hearing.

On the inner side of the tympanic membrane starts the middle ear (tympanic cavity), which contains the three smallest bones in the body: the malleus, incus, and stapes (Latin for hammer, anvil, and stirrup, respectively). The malleus has one end attached to the tympanic membrane and starts a chain with the other bones attached end to end. The end of the stapes sits on a deeper membrane that separates the middle ear from the inner ear.

Within the inner ear is a complicated labyrinth of channels that are fluid-filled. The channels are lined with thousands of sensory cells that signal both the auditory nerve (involved with hearing) and the vestibular nerve (involved with balance). It is via this complex and delicate system that sound waves are transmitted to the brain and become what we hear