52 Auditory and vestibular pathways Flashcards
The oval window is covered with ________ (bone) and they are linked by ________.
Stapes;
ligaments
The round window is covered with _________________, a layer of fibrous tissue between epithelium on either side.
Secondary tympanic membrane
What is the bony and the membranous labyrinth?
The hard bone of the cochlear;
membranous = contains the endolymph
Describe the route of drainage of the endolymph.
Aqueduct of vestibule contains the endolymphatic duct > sac > drains the endolymph into the dural venous sinuses.
Describe the route of drainage of the perilymph.
Perilymph exits to the subarachnoid space by the perilymphatic duct/ cochlear aqueduct.
What are the difference between the bony labyrinth and the membranous labyrinth in vestibular functions?
Bony VS membranous:
- semicircular canals VS semicircular ducts
- vestibule - aqueduct of vestibule VS utricle and saccule - endolymphatic duct and sac
What are the difference between the bony labyrinth and the membranous labyrinth in auditory functions?
Bony VS membranous:
Cochlea VS cochlear duct
What are the sensory epithelium (hair
cells + supporting cells) in the parts of
- Ampulla of semicircular duct?
- Utricle and saccule?
- Cochlear duct?
- Crista ampullaris
- Macula
- Spiral organ
The cochlea is a __________-filled tube which wraps around itself approximately ____ times.
perilymph;
2.5
In 3 different parts, the hairs (kinocilia and sterocilia) of sensory cell project into the
overlying gelatinous mass:
Cupula, otolith membrane, tectorial membrane
The bony cochlea turns around a central bony _____________, which forms the axis of the cochlear
turns.
modiolus
The spiral lamina is a ridge of bone that divides the cochlear cavity into two chambers:
the ___________ and the _____________.
scala vestibule;
scala tympani
The ____________ is suspended in the
endolymph within the scala media. It rests on the __________ membrane as its spirals within the cochlear turns.
organ of Corti;
basilar
What is spiral ligament? Function?
- thickened endosteum (fibrous cushion between stria vascularis and bony otic capsule)
- gives perilymph
____________ is a portion of the spiral ligament that is vascularised and secretes _____________.
Straie vascularis;
endolymph
The apical regions of the supporting and pillar cells of organ of Corti are tightly joined together to form the ______________ which is permeable/impermeable.
Reticular lamina;
impermeable
How can the brain control the sensitivity of hair cells?
Cortex > superior colliculus > CN8 > outer hair cells > beat to control apposition of the tectorial membrane
In scala vestibuli and tympani, what is the relative ionic concentrations of Na+ and K+?
[Na+] > [K+] in perilymph
The auditory pathway is bilateral but predominantly ____________.
Contralateral
Cochlear nucleus:
Dorsal nu: contralateral;
Ventral nu: bilateral
State the flow of the main auditory pathway.
Superior olivary nucleus >
Lateral lemniscus >
Inferior colliculus >
Medial geniculate nucleus
What is the trapezoid body?
From ventral cochlear nucleus, collection fibers on ventral aspect passing through the SON and the medial lemniscus (to contralateral side)
State the 4 functions of SON.
- Sound localization
(different arrival time and intensity between ears) - Modulation of sensitivity: SON > outer hair cells
- Acoustic reflex for dampening sound : SON > CN7 > stapedius m.(CN7) + tensor tympani (motor V)
- Attention (Tectospinal tract):
auditory signals > reticular formation, superior colliculus > neck muscles
Semicircular canal contains _________________ at the ampulla that detects angular acceleration.
Crista (ampullaris)
Utricle and saccule are the ____________ that contains _________ which are at right angle to each other.
otolith organs;
macula
Macula of utricle: horizontal plane;
Macula of saccule: vertical plane
