The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the

outer ear The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. It gathers sound energy and focuses it on the eardrum (tympanic membrane). Structure Auricle Th ...

to the

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...

. The adult human ear canal extends from the pinna to the

eardrum In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear The outer ear, external ear, or auris externa is the extern ...

and is about in length and in diameter.

Structure

The human ear canal is divided into two parts. The elastic cartilage part forms the outer third of the canal; its anterior and lower wall are cartilaginous, whereas its superior and back wall are fibrous. The cartilage is the continuation of the cartilage framework of pinna. The cartilaginous portion of the ear canal contains small hairs and specialized sweat glands, called

apocrine Apocrine () glands are a type of exocrine gland, which are themselves a type of gland, i.e. a group of cells specialized for the release of secretions. Exocrine glands secrete by one of three means: holocrine, merocrine and apocrine. In apocrine ...

glands, which produce

cerumen Earwax, also known by the medical term cerumen, is a brown, orange, red, yellowish or gray waxy substance secreted in the ear canal of humans and other mammals. It protects the skin of the human ear canal, assists in cleaning and lubrication, a ...

( ear wax). The bony part forms the inner two thirds. The bony part is much shorter in children and is only a ring (''annulus tympanicus'') in the newborn. The layer of epithelium encompassing the bony portion of the ear canal is much thinner and therefore, more sensitive in comparison to the cartilaginous portion. Size and shape of the canal vary among individuals. The canal is approximately long and in diameter.Faddis, B. T. (2008). "Structural and functional anatomy of the outer and middle ear". In W. Clark & K. Ohlemiller (Eds.), ''Anatomy and physiology of hearing for audiologists'' (pp. 93–108). Thomson Delmar Learning. It has a sigmoid form and runs from behind and above downward and forward. On the cross-section, it is of oval shape. These are important factors to consider when fitting

earplug An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Since they reduce the sound volume, earplugs are often used to help prevent hear ...

Disorders

Due to its relative exposure to the outside world, the ear canal is susceptible to diseases and other disorders. Some disorders include: *

Atresia Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent. Examples of atresia include: *Aural atresia, a congenital deformity where the ear canal is underdeveloped. * Biliary atresia, a condition i ...

of the ear canal *Cerumen impaction * Bone exposure, caused by the wearing away of skin in the canal *Auditory canal

osteoma An osteoma (plural: "osteomata") is a new piece of bone usually growing on another piece of bone, typically the skull. It is a benign tumor. When the bone tumor grows on other bone it is known as "homoplastic osteoma"; when it grows on other tissu ...

(bony outgrowths of the temporal bone) *

Cholesteatoma Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of th ...

Contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are ...

of the ear canal * Fungal infection (

otomycosis Otomycosis is a fungal ear infection, a superficial mycotic infection of the outer ear canal. It is more common in tropical countries. The infection may be either subacute or acute and is characterized by malodorous discharge, inflammation ...

) *

Ear mite Ear mites are mites that live in the ears of animals and humans. The most commonly seen species in veterinary medicine is ''Otodectes cynotis'' (Gk. ''oto''=ear, ''dectes''=biter, ''cynotis''=of the dog). This species, despite its name, is also r ...

s in animals * Ear

myiasis Myiasis is the parasitic infestation of the body of a live animal by fly larvae (maggots) which grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some spec ...

, an extremely rare infestation of maggots *Foreign body in ear *

Granuloma A granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such substances include infectious ...

, a

scar A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a na ...

usually caused by

tympanostomy tube Tympanostomy tube, also known as a grommet or myringotomy tube, is a small tube inserted into the eardrum in order to keep the middle ear aerated for a prolonged period of time, and to prevent the accumulation of fluid in the middle ear. The ope ...

s *

Otitis externa Otitis externa, also called swimmer's ear, is inflammation of the ear canal. It often presents with ear pain, swelling of the ear canal, and occasionally decreased hearing. Typically there is pain with movement of the outer ear. A high fever is ...

(swimmer's ear), bacteria-caused inflammation of the ear canal *

Stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture). ''Stricture'' ...

, a gradual closing of the canal

Earwax

Earwax, also known as cerumen, is a yellowish, waxy substance secreted in the ear canals. It plays an important role in the human ear canal, assisting in cleaning and lubrication, and also provides some protection from

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

, and

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s. Excess or impacted cerumen can press against the eardrum and/or occlude the external auditory canal and impair hearing, causing

conductive hearing loss Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with ...

. If left untreated, cerumen impaction can also increase the risk of developing an infection within the ear canal.

Additional images

File:Gray187.png, Base of skull. Inferior surface. File:Gray189.png, Left infratemporal fossa. File:Gray907.png, External and middle ear, opened from the front. Right side. File:Gray908.png, Horizontal section through left ear; upper half of section. File:Slide1CAC.JPG, Lateral head anatomy detail. Facial nerve dissection.

References

External links