Special Sense (Ear) Flashcards
What are the 3 anatomical regions of the ear?
external ear middle ear (tympanic cavity) inner ear (labyrinth)
What are the external and middle ears mainly involved in?
reception and transmission of sound waves to inner ear, where sound waves are converted to electrical impulses and conveyed to brain
What does the inner ear contain?
organ of balance
External Ear
What does the external ear include? (2)
- auricle
- external acoustic meatus
External Ear
What is the auricle?
has cartilaginous core covered by thin skin
External Ear
What does the auricle carry?
some contours that collect sound and transfer it to external acoustic meatus
External Ear
What is the lobule?
inferior part of auricle, and its cartilage is replaced by connective tissue
External Ear
What is the external acoustic meatus?
S-shaped long canal extending from auricle to tympanic membrane (ear drum)
External Ear
Is the external acoustic meatus bony or cartilaginous?
lateral ⅓ is cartilaginous
medial ⅔ is bony
External Ear
What does the thin skin covering the external acoustic meatus contain?
ceruminous glands (modified sweat glands) that secrete cerumen (ear wax) that slows growth of microorganisms in external acoustic meatus, and reduces risk of infection
Middle Ear (Tympanic Cavity)
What is the middle ear?
irregular cubic space contained within petrous part of temporal bone
Middle Ear (Tympanic Cavity)
What is the middle ear lined by?
mucous membrane that is continuous with that of nasopharynx
Middle Ear (Tympanic Cavity)
What are the 3 ossicles?
malleus, incus, and stapes
Middle Ear (Tympanic Cavity)
What do the 3 ossicles do?
amplify and convey sound from tympanic membrane to inner ear
Middle Ear (Tympanic Cavity)
How are ossicles jointed to each other?
by synovial joints
Middle Ear (Tympanic Cavity)
What are the 2 small skeletal muscles in the middle ear?
What do they do?
tensor tympani and stapedius
dampen sound
Middle Ear (Tympanic Cavity)
What are the 4 walls of the tympanic cavity with more distinct features?
lateral wall
medial wall
anterior wall
superior wall
Middle Ear (Tympanic Cavity)
What does the lateral wall carry?
tympanic membrane separating middle and external ears
Middle Ear (Tympanic Cavity)
What is the medial wall?
thin bony plate that separates tympanic cavity from inner ear
Middle Ear (Tympanic Cavity)
What does the medial wall carry?
2 openings
- fenestra vestibuli (oval window) covered by stapes
- fenestra cochlea (round window) covered by membrane
Middle Ear (Tympanic Cavity)
What is the anterior wall connected to?
nasopharynx via auditory tube
Middle Ear (Tympanic Cavity)
What is the superior wall?
(roof) separates tympanic cavity from middle cranial fossa
Inner Ear (Labyrinth)
Where is the inner ear?
housed within petrous part of temporal bone
Inner Ear (Labyrinth)
What are the 2 divisions of the inner ear?
osseous and membranous divisions
- bony labyrinth
- membranous labyrinth
Inner Ear (Labyrinth)
What is the bony labyrinth?
series of boney cavities divided into semicircular canals, vestibule, and cochlea
Inner Ear (Labyrinth)
What does the bony labyrinth contain?
perilymph - fluid similar to CSF that surrounds enclosed membranous labyrinth
Inner Ear (Labyrinth) - Bony Labyrinth
What are semicircular canals?
3 tubes that open into vestibule
Inner Ear (Labyrinth) - Bony Labyrinth
What is the vestibule?
connected to middle ear (via oval window) and cochlea
Inner Ear (Labyrinth) - Bony Labyrinth
What is the cochlea?
shell-shaped part of bony labyrinth
Inner Ear (Labyrinth) - Bony Labyrinth
How is the cochlea divided?
lumen of this tube is partially divided into two sections by bony septum (lamina)
- scala vestibuli
- scala tympani
Inner Ear (Labyrinth) - Bony Labyrinth
Where is the scala vestibuli?
located in upper section of lumen that ends to fenestra vestibuli (oval window)
Inner Ear (Labyrinth) - Bony Labyrinth
Where is the scala tympani?
located in lower section of lumen that ends to fenestra cochlea (round window)
Inner Ear (Labyrinth) - Membranous Labyrinth
Where is the membranous labyrinth?
suspended in bony labyrinth
Inner Ear (Labyrinth) - Membranous Labyrinth
What is the membranous labyrinth formed by?
series of membranous sacs and ducts
Inner Ear (Labyrinth) - Membranous Labyrinth
What is the membranous labyrinth filled with?
What is it surrounded with?
filled with endolymph
surrounded by perilymph
Inner Ear (Labyrinth) - Membranous Labyrinth
What does the membranous labyrinth include? (4)
- membranous semicircular ducts
- utricle
- saccule
- cochlear duct
Inner Ear (Labyrinth) - Membranous Labyrinth
Where are the membranous semicircular ducts?
located within bony semicircular canal, and open to utricle
Inner Ear (Labyrinth) - Membranous Labyrinth
What is the ampula?
dilated part of membranous semicircular duct that contains crista that carries equilibrium receptors
Inner Ear (Labyrinth) - Membranous Labyrinth
Where are the utricle and saccule?
inside vestibule, and are connected to each other by a duct
saccule is also connected to cochlear duct
Inner Ear (Labyrinth) - Membranous Labyrinth
What is the macula?
elevation in saccule that carries equilibrium receptors
Inner Ear (Labyrinth) - Membranous Labyrinth
What is the vestibular nerve?
arises from crista and macula
Inner Ear (Labyrinth) - Membranous Labyrinth
What does the cochlear duct carry?
organ of corti (organ of hearing) that gives rise to cochlear nerve
