Eye and ear, including pathways Flashcards
What is the eye socket called?
the orbit
What are the main holes of the orbit?
optic canal
superior orbital fissure
Inferior orbital fissure
Which nerve travels through the optic canal?
the optic nerve
Which cranial nerves travel through the superior orbital fissure?
oculomotor
trochlear
abducens
opthalmic division of the trigeminal nerve
What are the extraocular muscles?
lateral rectus medial rectus superior rectus inferior rectus superior oblique inferior oblique levator palpebrae superioris
Which muscle lifts the upper eyelid?
levator palpebrae superioris
What is the function of lateral rectus?
pulls the eye laterally (abduction)
What is the function of medial rectus?
pulls the eye medially (adduction)
What is the function of superior rectus?
pulls the eye up and medially rotates it (intorsion)
What name is given to the action of medially rotating the eye?
intorsion
What name is given to the action of laterally rotating the eye?
extorsion
What is the function of inferior rectus?
pulls the eye down and laterally rotates it (extorsion)
What is the function of superior oblique?
intorsion
What is the function of inferior oblique?
extrosion
When examining eye movements, which muscles do we test first?
lateral and medial rectus as these have isolated movements
After testing lateral and medial rectus, which muscles are tested next?
superior and inferior rectus
Which nerves supply the extraocular muscles
superior oblique- trochlear
lateral rectus- abducens
all others- oculomotor
What is the outermost layer of the eye?
fibrous layer
What comprises the fibrous layer of the eye?
the sclera
the cornea
Which part of the eyeball do the extraocular muscles attatch to?
the sclera
Which layer of the eye lies beneath the fibrous layer?
the vascular layer
What does the vascular layer of the eye consist of?
choroid
ciliary body
Iris
What is the function of choroid?
provides nourishment to the outer layers of the retina
What is the inner layer of the eye formed by?
the retina
What are the anterior and posterior chambers of the eye filled with?
aqueous humour
Is the optic nerve sensory, motor or both?
sensory
Light coming from the right falls onto which part of the retina?
the left side of the retina
Which part of the retina does light from below fall onto?
the upper part of the retina
Which part of the retina do the nerves that cross over to the other side of the brain arise from?
the nasal side of retina
Which part of the retina do the nerves that stay on the same side of the brain arise from?
temporal side of the retina
What does contralateral mean?
relating to or denoting the side of the body opposite to that on which a particular structure or condition occurs.
What does ipsilateral mean?
belonging to or occurring on the same side of the body.
Where is the lateral geniculate body?
the thalamus
Where in the brain do the fibres of the optic tracts synapse ?
lateral geniculate body
which gland sits immediately under the optic chiasm?
the pituitary gland
What is the medical word for vision?
opia
What is the medical word for no vision?
anopia
What is the medical word to describe when you can’t see half vision?
hemianopia
What is the medical word fro when you can’t see half vision and it’s in the same half for each eye?
homonymous hemianopia
Where does the upper optic radiation carry fibres from?
Fibres from the superior retinal quadrants
Which lobe does the upper optic radiation travel through?
the parietal lobe
Which lobe does the lower optic radiation travel through?
temporal lobe (pathway known as meyer’s loop)
Which optic radiation contains fibres from the inferior retinal quadrants?
lower optic radiation
Which optic tract contains fibres from the left temporal retina and the right nasal retina?
left optic tract
Which half of the retina has fibres that stay on the same side?
temporal half of retina
In the pupillary reflex, where do fibres synapse instead of the lateral geniculate body? From here, which nucleus do fibres then go to?
pretectal nucleus
Edinger-westphal nucleus
What is the fourth cranial nerve?
trochlear
What is the sixth cranial nerve?
abducens
What does the outer ear consist of?
the pinna
the ear canal
the tympanic membrane
What is the first third of the ear canal made of?
cartilage
What is the last two thirds of the ear canal made of?
bone
What is the top part of the tympanic membrane called?
the pars flaccida
What is the bottom part of the tympanic membrane called?
the pars tensa
What are the bones of the middle ear?
malleus
incus
stapes
What are the muscles of the inner ear?
tensor tympani
stapedius
Which canal connects the middle ear to the nasopharynx?
eustation tube
Which of the middle ear bones is attached to the eardrum?
malleus
Which bone of the middle ear presses up against the oval window?
stapes
Which bone does stapedius attach to?
stapes
Which bone does tensor tympani attach to?
malleus
What is the role of the middle ear?
amplification
tympanic membrane has a large surface area
stapes footplate has small surface area
What is the function of stapedius and tensor tympani?
stiffen the ossicular chain
prevent damage to the middle ear
How is stapedius stimulated?
acoustically
How is tensor tympani stimulated?
both voluntarily and involuntarily
What is the primary role of the eustachion tube?
ventilation- keeps pressures on both sides of the eardrum equal
What is the inner ear comprised of?
the vestibulocochlear apparatus
What are the two openings of the cochlea?
round window
oval window
What are the three compartments of the cochlea?
scala tympani, scala media , scala vestibuli
What are the two ionic fluids in the cochlea?
Endolymph
Perilymph
Where in the cochlea will you find endolympth?
in the scala media
Where in the cochlea will you find perilymph?
scala vestibuli
scala tympani
Which cochlea fluid is rich in K+?
Endolymph
Which cochlea fluid is rich in Na+
Perilymph
Where in the cochlea will you find the oval window?
scala vestibuli
Where in the cochlea will you find the round window?
scala tympani
Where is the basilar membrane the most narrow?
at the base by the oval window
Where are high frequencies detected along the basilar membrane?
the base- this is where the basilar membrane is narrow and stiff
What is the function of inner hair cells?
mechanical transduction
what is the function of outer hair cells?
fine tuning, increasing resolution
Which type of hair cells has the ability to stiffen the basilar membrane so that only the part of the basilar membrane meant to detect that specific frequency will vibrate ?
Outer hair cells
the movement of what causes an influx of K+ rich endolymph into inner hair cells and depolarisation as mechanically gated calcium channels open
stereocilia
How is the frequency (pitch) of sound encoded?
encoded in nerve by location along the basilar membrane
How is the intensity (loudness) of sound encoded?
encoded in nerves by numbers responding and firing rate
Describe the central auditory pathway
ECOLI Eight nerve Cochlear nucleus superior Olivary complex Lateral lemniscus Inferior colliculus
Inferior colliculus > medial geniculate body > auditory cortex
Which lobe is the auditory cortex in ?
the temporal lobe
What are the two types of hearing loss? Where is the defect in each type?
Conductive hearing loss- outer/middle ear defect
Sensorineural hearing loss- Inner ear defect