Lecture 56 Our Ears Flashcards
The temporal bone contains sensory organs for ____ and ___.
balance and hearing
Describe the temporal bone’s petrosal pathway (of CN VII).
first branch of CN VII is greater petrosal nerve
second branch of CN VII is the chorda tympani
How many ears do humans have?
six (three paired structures per side; inner, middle, and external ears)
What are the two major components of the external ear?
auricle (pinna)
external auditory canal
The external ear terminates medially at the outer surface of what structure?
the tympanic membrane
What are the three major components of the middle ear?
inner surface of the tympanic membrane (laterally)
ossicles (malleus, incus, stapes)
communications to the eustachian tube and mastoid air sinus
What are the three major components of the inner ear?
the organs for balance (vestibular sysem)
the organs for hearing (cochlea)
path of the Vestibulo-Cochlear Nerve (CN VIII)
What does the Eustachian tube lead to from the middle ear?
nasopharynx
What five structures comprise the vestibular system?
three semicircular canals
utricle
saccule
What nerves comprise auricular sensation?
CN V (Trigeminal)- auriculotemporal branch
CN VII (Facial)- small area; posterior canal wall
CN IX (Glossopharyngeal)- medial, inner part of tympanic membrane
CN X (Vagus)- most of the ear canal
Greater Auricular Nerve (C2,C3)
Lesser Ocipital Nerve (C2)
What are the functions of the external ear?
sound capture, direction, and amplification
heat dissipation
communication and mood signaling
How is the middle ear kept at atmospheric pressure?
periodic opening of the Eustachian tube
What are the three auditory ossicles?
malleus, incus, stapes
The stapes is fastened into what structure, which separates the middle and inner ear?
oval window (of the cochlea)
What two muscles are found in the middle ear and are attached to the long process of the malleus and the neck of the stapes respectively?
tensor tympani
stapedius
What nerve passes through the middle ear on its way to the lingual nerve and provides taste to the anterior 2/3 of the tongue (SVA) and secretomotor to submandibular adn sublingual salivary glands (GVE)?
chorda tympani
What two synovial joints between the ossicles can develop arthritis?
incudomalleolar and incudostapedial joints
What is the most common childhood ailment in the US?
acute otits media
What recess connects the middle ear to the mastoid air cells?
Epitympanic recess
The malleus, incus, and stapes are derived from which branchial arches?
1 and 2
What structures make up the bony cavities of the bony labyrinth of the middle ear? What are thy lined with?
vestibule, semicircular canals, and cochlea
periosteum and contain perilymph
What structures make up the membranous ducts and sacs or membranous labyrinth of the inner ear? What are these spaces lined with?
Semicircular ducts, cochlear duct, utricle, and saccule
spaced lined with endolymph
The inner ear is situated in what part of the temporal bone?
petrous part of the temporal bone
Describe the orientations of the three semicircular canals.
one horizontal and two vertical
What is contained within the vestibule?
two otolith organs, the utricle and the saccule
Movement of the stapes upon the membrane at the oval window will commence a wave-like action that moves the fluids of the inner ear which, in turn, affects specialized cells know as what in the cochlea? This movement is sensed by what structure?
hair cells
cochlear nerve for hearing
What affects the hair cells located in the semicircular canals, utricle, and saccule of the vestibular system? This movement is sensed by what structure?
head movements
vestibular nerve for balance
What is described as being the functional unit of the inner ear?
hair cells within the organ of corti
What is conductive hearing loss and how is it fixed?
failure in efficient conduction of sound waves through the outer ear, tympanic membrane, or middle ear
stapedectomy
What is sensorineural hearing loss and how is it fixed?
damage of the cochlear nerve, inner ear hair cells, and/or brain (ex. presbycusis)
cochlear implants
