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Gross EAR CN VIII
WVSOM -- Gross Anatomy -- Ear and Cranial Nerve VIII
Question | Answer |
---|---|
How do you differentiate between the external, middle and inner ear? | External ear and middle ear are divided by the tympanic membrane. the Inner ear and middle ear is separated by the labyrinth wall |
What makes up the external ear? | Auricle, external acoustic meatus, typmanic membrane |
What is the middle ear? | air filled cavity in petrous portion of temporal bone |
What makes up the middle ear? | bony ossicles, stapedius m., tensor tympani m. corda tympani n. |
What are the 6 walls of the middle ear? | roof: tegmental wall, Floor: jugular wall, Lateral: membrounous wall, medial: labryinth wall, posterior: mastoid wall, anterior: carotid wall |
What are the bony ossicles? | malleus, incus, stapes |
What are the two portions of the two portions of the inner ear? | bony portion adn membranous portion |
What is contained in the bony portion of the inner ear? | perilymph, cochlea, vestibule, and semicircular canal |
What makes up the membranous portion of the inner ear? | surrounded by the bony portion and filled with endolymph; contains cochlear duct, utricle, saccule, and semicircular ducts |
What are the utricle/saccule? | both contain a macula and is an equilibrium sensor containing otolith or an otolithic membrane which are in contact with hair cells attached to nerve branches of CN VIII |
What are the semicirular ducts? | Contain CRIST AMPULLARIS. Is an equilibrium sensor. Each crista consists of a copula which is in contact with hair cells attched to branches of CN VIII |
What is the cochlear duct | ORGAN OF CORTI (hearing). Consists of tectorial membrane that contacts hair cells attached to the cochlear portion of teh vestibulocochlear nerve |
What is the auricle? | elestic cartilage covered by skin. Blood supply by teh superficial temporal andposterior auricular branches of the external carotid artery. Innervated by the greater auricular never (Cervical Plxus) and auriculotemporal (V3) |
What makes up the auricle? | helix antihelix tragus antitragus lobule |
What is the external acoustic meatus? | 2-3 cm long canal in the temporal bone that leads to the tympanic membrane. Innervated by the auriculotemporal nerve |
What does the tympanic membrane get derived from? | first pharyngeal pouch |
What innervates the tympanic membrane? | External: auriculotemporal n. and auricular branch of CN X Internal: Innervated by CN IX |
Why do infections follow from teh nasopharynx to the tympanic cavity? | forms a route for infection t pass from the nasopharynx to the middle ear cavity. Easily blocked by swelling of the mucous membrane since in adults, its walls are in apposition. Otitis mediua is usually secondary to upper respiratory |
Why are infections more common in children? | their eustacian tubes are shorter adn more horizontal. They get clogged easier |
What happens if infection is not treated in teh middle ear. | infection of the mastoid air cells occurs (masotiditis) |
Explain the movement of the inner ear and impulses to teh vestibulocochlear nerve. | Movement of the inner ear fluids results in displacement of hair cells associated with the special sensory receptors htus intiated nerver pulses in eitehr the cochlear or vestibular portion of CN VIII |