The outer ear is made up of three parts, one of which is visible. The pinna is the part of the ear that sits on the outside of the head. The auditory canal and tympanic membrane are inside the head.
The pinna is the visible part of the outer ear, and consists of cartilage covered by skin that acts to amplify sound and help an individual tell what direction noise is coming from. The very bottom of the ear is called the lobule, and is commonly pierced for earrings. The section of the ear above that is the antitragus, which joins to the helix and antihelix that arch to the top of the ear and form the shape. The hollow where the ear begins to turn downward again is called the fossa triangularis, and the innermost part of the ear is called the cymba conchae. The cavum conchae is the area of the outer ear that is at the entrance to the ear canal, a hole that is covered by the tragus.
A number of different conditions cause abnormalities in the appearance of the pinna, and may impact an individual's hearing. Turner syndrome and Down syndrome can result in abnormally formed ears in infants and children, while those who are middle-aged can develop skin tags on the pinna. These tags are generally painless and easily removed.
The auditory canal is a tube that runs between the pinna and the tympanic membrane, or eardrum. This is the part of the outer ear that contains small hairs that help protect the inner ear from dust and other particles. There are also glands in the auditory canal that produce sweat and wax, substances that also help to capture foreign particles and protect the delicate parts of the inner ear.
The boundary between the inner and outer ear is the tympanic membrane, also known as the eardrum. This thin membrane vibrates with sounds from the outside, and tearing or rupturing of this membrane can result in hearing loss and balance problems. In addition to being the first part of the ear that is crucial in turning sound waves into a form that the brain can recognize as sound, the eardrum also continues the role of the auditory canal and helps to protect the more vulnerable areas of the middle and inner ear from infections and outside damage. This is the portion of the ear frequently damaged by trauma or loud noises.