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The auricle or pinna consists of elastic cartilage and is covered by perichondrium and epithelium.
The pinna functions to channel sound through the external auditory canal.
The lateral one third of the external auditory canal is composed of cartilage covered by epithelium containing wax producing glands and hair.
Medial two thirds of the auditory canal is osseous and covered by a thin layer of epithelial cells.
Auditory canal lined with skin.
The middle ear within the temporal bone is a mucosa lined sinus that houses the ossicular chain.
The tympanic membrane converts sound waves into mechanical energy and transmits this change through the ossicular chain to the cochlea.
The tympanic membrane is adherent to the malleus and is divided into the pars flaccida superiorly and the larger pars tensa inferiorly.
Tympanic membrane line on its external surface with squamous cell epithelium.
Lateral aspect of the auditory canal contains sebaceous glands and modified sweat glands.
The eustachian tube provides communication between the middle ear and nasopharynx.
The eustachian tube protects the middle ear from nasopharyngeal infections, aerates the middle ear, and drains fluid from the middle ear space.
The eustachian tube opens by the action of the tensor veli palatini muscle during swallowing and yawning.
Eustachian tube is nearly horizontal in infants and elongates to a more vertical position as the face grows.
Eustachian tube may fail to protect the middle ear from nasopharyngeal bacteria and this results in acute otitis media.
The eustachian tube may fail to clear middle ear fluid due to its obstruction and this can lead to otitis media with associated effusion.
Mastoid cavity is pneumatized bone process of the temporal that communicates with the middle ear.
The ossicular chain consisting of the malleus, incus and stapes which conduct mechanical energy from the tympanic membrane to the oval window of the inner ear.
Sound is amplified 22 times by the difference in the surface area between the tympanic membrane and the oval window, and the lever action of the ossicular chain.
The inner ear encases the sensory end of the cochlea and the vestibular systems, the hearing and balance systems, respectively.
The cochlea contains the end organ of hearing, the organ of Corti.
The vestibular system consists of three semicircular canals at 90 degree angles to each other and they sense spatial orientation an angular acceleration, and the utricle and saccule which sense linear acceleration.
Cerumen is formed by the sweat gland secretions and desquamated epithelial cells.
Cerumen impaction accounts for 12 million patient visits annually in the U.S.
Excessive or impacted ear canals from cerumen found In 1 in 10 children, 1 in 20 adults and in more than one third of elderly individuals.
Symptoms secondary to cerumen impaction include impaired hearing, tinnitus, itching, ear canal fullness, pain discharge odor and cough.
Cerumen impaction prevents visualization of the ear canal and the tympanic membrane.
Cerumen impaction treatment includes cerumenolytic agents, irrigation and manual removal.
Impulses generated by the cochlea and vestibular system are transmitted centrally via the vestibulo-cochlear nerve.
The VIIIth cranial nerve travels through the temporal bone and middle ear space.