Ears

Ears are made up of three parts:

• the outer ear
• the middle ear
• the inner ear

Parts of the Ear

The outer ear consists of the pinna, or auricle, and the ear canal. The pinna – the part of the ear that we see – collects and guides sound vibrations into the ear canal. It helps us determine the direction and source of sound.

The middle ear begins with the ear drum at the end of the ear canal. The middle ear contains three small bones, called the ossicles, or ossicular chain.  These bones are called the malleus, incus and stapes, also known as the hammer, anvil and stirrup. These bones connect the ear drum to the inner ear.  The bones sit in an air filled space which is ventilated by the eustachian tube - which leads from the back of the nose and throat to the middle ear.

The inner ear contains the sensory organs for hearing and balance. The cochlea is the hearing part of the inner ear. The semicircular canals in the inner ear are part of our balance system.

The cochlea is a bony structure shaped like a snail and about the size of a pea. The Organ of Corti is the sensory receptor inside the cochlea, a complex structure which includes thousands of hair cells or cilia sitting in fluid.

These hair cells are connected to nerves which lead to the auditory nerve. Nerve impulses are carried to a ‘relay station’ in the mid-brain and then on to other brain pathways that end in the auditory cortex (the hearing part of the brain) where the sound is interpreted. 

Also housed within the inner ear are the semicircular canals. These structures help control steadiness or balance. These balance organs share the space in our skull with the cochlea.

References and Further Reading

American Speech-Language-Hearing Association,  How We Hear