Lecture 34 - Ears Flashcards
What are the three parts of the ear?
Inner - Middle - Outer
What is the inner ear within?
Temporal bone
What is the middle ear within?
Petrous and tympanic portions of the temporal bone
What is the bony labyrinth of the inner ear filled with?
Perilymph
What is suspended in the perilymph?
Membranous labyrinth
What is the membranous labyrinth filled with?
Endolymph
Besides endolymph what else is within the membranous labyrinth?
Organs that transduce movement into neuronal signals
What are the two sections of the membranous labyrinth?
Vestibule and cochlea
What is within the vestibule?
Contains all organs of balance and orientation
What innervates the vestibule?
Vestibular branch of CN VIII
What is within the cochlea?
Contains the organ of hearing
What innervates the cochlea?
Cochlear branch of CN VIII
What happens when the stereocilia toward the kinocilium?
Increase the firing rate of the sensory nerve
What happens if the stereocilia bend away from the kinocilium?
Decrease the firing rate
What are the two portions of the of vestibule?
Utricle and saccule
What are cristae?
Crests of hair cells stimulated by fluid flow around semicircular ducts in response to rotation
Where are crista?
Located in the ampulla at the end of the three semicircular ducts
What stimulates the spiral organ?
Sound waves transmitted from the surrounding perilymph into the endolymph
What decides where the sound is transferred from perilymph to endolymph?
Frequency
What amplifies sound on land?
Tympanic membrane
What is the function of the middle ear?
Transmit sound vibrations from lateral external ear to medial inner ear
What are the three ear bones?
Stapes - Incus - Malleus
What does the stapes articulate with?
The oval window
What does the stapes do?
Causes the vibrations in the perilymph of the inner ear
What does the malleus articulate with?
Fixed to the tympanic membrane
What does the malleus do?
Passes vibrations from the external ear to the inner ear
What are the two muscles that interact with the ossicles?
Tensor tympani Stapedius
What nerve innervates the tensor tympani?
Mandibular nerve CN V3
What nerve innervates the Stapedius?
Facial nerve CN VII
What is the function of the muscles in the ossicles?
Act to clarify hearing and protect from excessively loud noises
Where is the tensor tympani?
Comes from the anterior wall of the middle ear and inserts onto the body of the malleus
Where is the stapedius?
Comes from the posterior wall and inserts on the head of the stapes
What nerve does the sensory from the mucosa lining of the middle ear come from?
Glossopharyngeal nerve
What nerve carries preganglionic PNS axons from CN IX to the otic ganglion?
Minor pterosal nerve
What is carried on the major petrosal nerve?
Preganglionic PNS axons from CN VII to the pterygopalatine ganglion
What is the chorda tympani a branch of?
Facial nerve
What nerve crosses the tympanic membrane?
Chorda tympani
What nerve does the chorda tympani hitchhike on?
Lingual
What maximizes the function of the tympanic membrane?
Pressure on both sides must be equal
What does the auditory tube connect?
Middle ear to the nasopharynx
What is the normal state of the auditory tube?
Closed
What is the function of the auditory tube?
To equalize pressure
What muscles open the auditory tube?
Tensor and levator veli palatini
What structures lay within the same region as the guttural pouch?
Stylohyoid External carotid artery Glossopharyngeal nerve Vagosympathetic trunk Hypoglossal nerve
What happens when there is facture of the stylohyoid?
Difficulty moving the tongue
What happens where there is a lesion of the vagus or glossopharyngeal nerves?
Difficulty swallowing or laryngeal hemiplegia
What can lead to horner syndrome?
Lesion of the sympathetic chain
What is otitis media?
Infection of the middle ear
What surgical method can be used with severe ear infections?
Drained via opening tympanic bulla rostromedially into the nasopharynx
What is the function of the Auricle?
Funnel and focus sound in the external auditory canal
What grouping are the auricular muscles a part of?
Muscles of facial expression
What does the caudal auricular artery come off of?
External carotid
What are the branches off the caudal auricular?
Medial - Lateral - Intermediate - Deep
What does the caudal aurcular a. provide blood to?
Caudal surface of the ear
What provides sensory to the ear?
Ventral and dorsal rami of C2
What does the Ventral rami of C2 provide sensory to?
Lateral side of caudal ear
What nerve comes off the ventral rami of C2?
Great auricular nerve
What nerve comes off the dorsal rami of C2?
Great occipital n.
What does the greater occipital n. provide sensory to?
Medial, caudal portion of the ear
What does the auriculotemporal n. provide sensory for?
Rostral portion of the ear and a lot of the lower jaw and lateral face
What is the auriculotemporal n. a branch of?
Trigeminal - CN V3 (mandibular)
What does the vagus nerve provide sensory for?
Rostral portion of ear medial region
What is the path of the vagal nerve in regards to ear sensory?
Hitchhikes on facial nerve in the petrous portion of the temporal bone
What are the functions of the ear?
Balance and orientation Hearing
