Cochlear Anatomy Flashcards
The cochlea is housed where?
Temporal bone
What boney element surrounds the cochlea?
Otic capsule
What are the types of temporal bone fractures? How often do they each occur? Which is worse?
here are two types of temporal bone fractures: longitudinal and transverse. Longitudinal fractures occur in 70% of the cases and result from a severe blow in the head. The severe blow can result in sensorineural and conductive hearing loss, balance problems, and facial serve damage and paralysis (20% of cases). Transverse fractures occur in 30% of the cases and result from a blow through the otic capsule and the internal auditory meatus. The damage results in profound sensorineural hearing loss, severe vertigo, and facial nerve damage and paralysis (50% of cases).
The cochlea has how many turns?
2.2-2.9 turns
How long is the average cochlea?
35 mm long
The central axis of the cochlea is called what?
Modiolus
What is the function of the spiral lamina?
The spiral lamina is a shelf-like structure that wraps around modiolus from base to apex. It serves as the connection point between the scala vestibuli and tympani. It is also important because auditory nerve fibers pass from the hair cells in the cochlea to the nuclei in the brainstem.
What are the two windows of the cochlea? Where are they located (which is superior)? What is attached to them?
he two windows of the cochlea are the oval and round windows. The oval window is superior to the round window and is attached to the stapes and consequently the vestibule and scala vestibuli. The round window is attached to the scala tympani. The window is a membrane that keeps the cochlear fluids in the cochlea.
What are the 3 scala and where are they located?
Scala vestibule (superior) Scala media or cochlear duct Scala tympani (inferior)
What divides the 3 scala and where are they located?
The three scala are divided by two membranes, the basilar and Reissner’s membranes. The basilar membrane divides the scala tympani and the scala media and Reissner’s membrane divides the scala vestibuli and the scala media.
Describe the size and stiffness of the basilar membrane.
The basal end of the basilar membrane is thinner, not as wide, and is stiffness dominated. The apical end of the basilar membrane is widest, thickest, and is mass dominated.
What is the main organ of hearing?
Organ of Corti
What gelatinous flap of collagen lies above the organ of corti?
Tectorial membrane
What is the purpose of the stria vascularis?
The stria vascularis has secretory and absorptive functions. It supplies blood and nutrients to the cochlea and is suspected to manufacture endolymph. It is also considered the source of the endocochlear potential.
What are the two types of hair cells? What are their shapes? How many are there of each?
The organ of Corti has two sensory cells: inner hair cells and outer hair cells. The outer hair cells are cylinder-shaped and are about 10 m in diameter. There are approximately 12,000 outer hair cells. The inner hair cells are structurally stronger than the outer hair cells. They are ovoid or flask shaped and are about 35 m in length. There are approximately 3,500 inner hair cells.
