The Ear

Auditory ossicles ( middle ear)

1: MALLEUS 2: INCUS 3: STAPES

The auricotemporal nerve

A branch of the CN V3, supplies the skin of the auricle anterior to the external acoustic meatus.

Cochlear Duct

Spiral tube, Waves of hydraulic pressure created in the perilymph of the vestibule by the vibrations of the base of the stapes ascend to the apex of the cochlea by one channel, the scala vestibule. The organ is stimulate to respond by deformation of the cochlear duct induced by the hydraulic pressure waves in the perylipmh.

-auditory ossicles -stapedius and tensor tympani muscles - chords tympani nerve -Tympanic plexus

The contents of the middle ear

Motion of sickness

The maculae of the membranous labyrinth are primary static organs, which have small dense particles ( otoliths) embedded among hair cells. Under influence of gravity stimulates and awards. Also respond of motion of acceleration and desaccelaration.

otitis media

The secondary to upper respiratory infections. Infections membrane lining the tympanic cavity.

The tympanic membrane

separates the external ear from the middle ear.

The great auricular nerve

supply the cranial surfaces and the posterior part of the lateral surface

Walls of the Tympanic cavity

Is shaped like a lozenge or narrow doc with concave sides. It has six walls: 1: Tegmental wall 2: Jugular wall 3: Membranous wall 4: labyrinthine wall 5: anterior carotid wall 6: Mastoid wall

Middle ear

Is the narrow filled chamber in the petrous part of the temporal bone.

Paralysis of Stapedius

Lesion of the facial nerve, associated withe excessive acuteness if hearing hyperacusis or hypercusia. Uninhibited movements of the stapes.

Incus

Located between the malleus and the stapes and articulates with them. It has a body and two limbs. The short limb is connected by a ligament to the posterior walls of the tympanic cavity.

The external and middle parts

Mainly concerned with transference of sound to the internal ear, which contain the organ of equilibrium .

Tensor tympani and the stapedius

Muscles associated with the auditory ossicles. Two muscles dampen or resist movements of the auditory ossicles , one also dampens movements ( vibration) of the tympanic membrane.

High Tone Deafness

Persistent exposure to excessively loud sounds, causes degeneration in the spiral organ ( cochlea)

The parts of the external ear

Pinna, auricle, helix, trigus

Malleus

Attached to the tympanic membrane. Its rounded superiorly by the head of the malleus lies in the epitympanic recess. Articulates with the incus. The main function as lever, with the longer of its two process and its handle attached to tympanic membrane.

Meniere syndrome

Blockage of the cochlear aqueduct and recurrent attacks of tinnitus , hearing loss and vertigo. (pressure in the ear) Endolymph increase volumen.

Semicircular canals

Communicate with the vestibule of the bony labyrinth . Occupies the three planes in space. ( 1.5 mm each one s.s.)

utricule

Communicates with the saccule though the utriculosaccular duct from which the endolymph arises. Have specialized areas of sensory epithelium called maculae/

External ear

Composed of the shell-like auricle (pinna) which collects sound , and external acoustic meatus canal.

Pharyngotympanic tube

Connects to the tympanic cavity to the nasopharynx , where it opens posterior to the inferior nasal meatus. The function is equalize the pressure in the middle ear with the atm.

Ear

Consist of external, middle and internal parts

The modiolus

Contains canals for blood vessels and for distribution of the branches of the cochlear nerve. The basal turn, communicates with the subarachnoid spaces superior to the jugular foramen.

Internal ear

Contains the vestibule cochlear organ concerned with the reception of the sound and the maintenance of the balance . The membranous labyrinth , contains endolymph , is suspenden within the peryl. ( fluids involved in stimulating the end organs for balance and hearing.

Mastoiditis

Infections of the mastoid antrum and mastoid cells result from a middle ear infection that causes inflammation of the mastoid process.

Otic Barotrauma

Injuried caused by an imbalance in the pressure between ambient air and the air in the middle ear.

Dizziness and Hearing Loss

Injuries of the peripheral auditory system causes there major system hearing loss , vertigo ( semicircular ducts) , and tinnitus ( cochlear duct).

Mastoid antrum

Is a cavity is separated from the middle cranial fossa by a thin plate of the temporal bone called legmen tympani. Is related to the canal for the facial nerve.

Internal acoustic meatus

Is a narrow canal that runs laterally . Pass CN VII and CN VIII ( vestibulocochlear) and its division and blood vessels.

Bony labyrinth

Is a series of cavities ( cochlea vestibule and semicircularies canals ) contained within the otic capsule of the petrous part of the part of the temporal bone. Is the fluid-filled space, which is sorrowed by the otic capsule, and is most accurately represented by a cast of the otic capsule after removal of the surrounding bone.

Conductive hearing loss and sensorineural loss

Two types of hearing loss 1: Anything in the external or middle. 2: Resulting from defects in the cochlea , cochlear nerve or cortical connections

Membranous labyrinth

consist of communicating sacs and ducts that are suspenden in the bony labyrithn . Contains the endolymph , a watery fluid similar in composition to intracellular fluids , thus different in the composition to the intracellular fluids. Its composed by two divisions , the vestibular labyrinth and the cochlear labyrithn.

The vestibulocochlear nerve

divides near the lateral end of the internal acoustic meatus into parts : cochlear and vestibular nerve.

Auditory Ossicles

form a mobile chain of the small bones across the tympanic cavity from the tympanic membrane to the oval window

Semicircular ducts

has an ampulla each one at the end contains a sensory area, the ampullarf crest/ Stimulates primary sensory neurons, whose cells bodies are in the vestibular ganglia. The crest are sensors for recording movements of the endolymph in the ampulla resulting rotates the head.

External Acoustic meatus

is a canal that leads inward though the tympanic part of the temporal bone from the auricle to the tympanic membrane. S-Shaped canal

Tensor tympani

is a short muscle that arise from the superior surface of the cartilganeous part of the pharyngotympanic tuve, the action is prevent damage to the internal ear when one is exposed to loud sounds. Supplied by CN V3

Vestibule of the bony labyrinth

is a small oval chamber that contains the trickle and saccule and parts of the balancing apparatus . The vestibule features the oval window of its lateral wall, occupied by the stapes. Transmits reg endolympathic duct.

Stapedius

is a tiny muscle inside the pyramidal eminence a hollow coneshaped prominence on the posterior wall of the tympanic cavity. Proverbs excessive movement of the shapes. Supplied by CN VII

The tragus

is a tongue like projection overlapping the opening of the external acoustic meatus.

macula of the utricule

is in the floor of the utricule. The hair cells in the maculae are innervated by fibers of the vestibular division of the vestitubulocochlear nerve. The primary sensory neurons are in the vestibular ganglia, which are in the internal acoustic meatus.

Endolympathic duct

is located under the dura mater on the posterior surface of the petrous part pf the temporal bone. Reservoir for excess endolymph, formed by blood capillaries in the membranous labyrinth.

Cochlea

is shell -shaped part of the bony labyrinth that contains the cochlear duct , the part of the internal ear concerned with hearing. ( 2.5 turns).

Stapes

is the smallest ossicle. It has a head , two lids ( crura) and a base. The head articulates with the incus. The base is considerably smaller than the tympanic membrane; as a result the vibratory force of the stapes is increases approx. 10 times over that of the tympanic membrane.

The tympanic membrane

moves in response to air vibrations that pass to it through the external acoustic meatus. Movements of the membrane are transmitted by the auditory ossicles though the middle ear to the internal ear.