11 (C) Visual Ear Flashcards
The inner ear is located within which bone of the skull?
Petrous part of temporal
Ear lobes
Auricle
Middle ear is located within which bone of the skull?
Petrous part of temporal
What connects nasopharynx + middle ear
Eustachian tube
Why is there a greater risk in children of middle ear infections?
Eustachian tube more horizontal
Valsalva manoeuvre
Helps pressure differential between middle ear + outside
What are the ossicles
Malleus
Incus
Stapes
Pulsatile tinnitus is caused by what artery?
Internal carotid artery
thrombosis can occur in the ear because of what vein close by?
Internal jugular vein
Stapedius muscle is innervated by what?
Chorda Tympani is innervated by what?
Facial Nerve
Vestibular system is for?
Balance + equilibrium
Cochlea system is for?
Hearing
Petrous outer bone contains what fluid?
Perilymph (ECF)
Petrous inner bone contains what?
Endolymph (ICF)
High frequency sounds are heard at the …… of the Cochlear
Base
Low frequency sounds are heard at the …. of the Cochlear
Apex
What are the two chambers of the cochlear duct
Scala Vestibuli (SV) Scala Tympani (ST)
What deforms the endolymph in cochlear duct?
Perilymph
What does the organ of Corti sit above between the SV + ST?
What kind of organ is it?
Basilar membrane
Spiral Organ
What is the membrane found that has hair cells tips in the Organ Of Corti?
Tectorial membrane
Role of the organ of corti
Converts fluid pressure –> electrical signals
What key structure can be found at the apex of the cochlea where SV + ST meet
Helicotrema
Stapes hit what window?
Oval Window
Organ of corti is stimulated through what?
Deformation of cochlear duct by perilymph in SV + ST
CNV8 (cochlear nerve) enters the Rostral Medulla via what
Cerebellopontine Angle
Cochlear nerve goes through the spiral ganglion to go where?
Dorsal + ventral cochlear nuclei
Role of the trapezoid body?
Which side does it innervate
Connect Cochlear Nuclei –> Superior Olivary Nucleus
Its bilateral so innervates both SON
Where is the Superior Olivary Nucleus found?
Mid Pons
The SON receives what type of information
Bilateral
SON has fibres which go to which structure?
What fibres are used to go the structure?
Inferior Colliculus
Lateral lemniscus
Lateral Lemniscus fibres has what type of information
Bilateral Information
The inferior Colliculus is found at what level
Tectum of midbrain
The inferior colliculus sends information to what?
What type of fibres are used?
Medial Geniculate Nucleus (MGN)
Inferior Brachium of IC
The MGN sends fibres to what?
What type of fibres are used?
Auditory Cortex (Herchl’s)
Acoustic Radiation Fibres
High Pitch sounds are found at what part of the auditory cortex?
Posteromedial part
Low Pitch sounds are found at what part of the auditory cortex?
Anterolateral part
Low => anteroLateral
2* auditoy areas
Brocas Area + Wernicke’s
If there is an anterior Left Middle cerebral artery stroke, what can be affected?
Broca’s
If there is an posterior Left Middle Cerebral Artery stroke, what can be affected
Wernicke’s
Head + eye movement moves in response to sound. Where do CN 3,4,6 come from to initiate these movements?
Inferior Colliculus –> Tectum of midbrain
Highest Acuity can be found at what part of the retina
Fovea (macula)
Region of the retina on which light from the centre of the visual axis falls is called the
fovea centralis
Which part of the eye is highly vascularised
Choroid
Which structure is key in refraction to the lens
Cornea
Is the cornea vascularised?
No = avascular
the retina is an extension of what?
Diencephalon
the non neuronal part of the retina have what type of epithelium
Pigmented epithelium
What is the most common type of photoreceptor?
Rods
Which type of photoreceptor has HIGH level of convergence?
Rods
Cones are found only at … with what type of ratio
The macula
One Cone : One ganglion
Papilloedema is a swelling of what?
Optic Disk
What does a papilloedema prevent?
Venous drainage of eye due to compression of central retinal vein
The Geniculocalcarine tract is otherwise known as what?
Optic Radiations
do nasal fibres cross at the optic canal?
yes
Superior trajectory tracts carry what type of information
Lower field
Inferior trajectory tract is otherwise known as what
What information does it carry
Meyers Loops
Upper field
What key structure is represented most posteriorly in the cortex?
Macula –> towards tip of occipital pole
A scotoma is what?
Localised patch of blindness
the pre-tectal area can be found where?
Midbrain
Consenual reflex =
Light in one eye = constriction in other eye
if no direct pupillary reflex, there is damage to what?
CN II
The accomodation reflex is used in what?
looking from far objects to close objects
What are the 3 stages of the accomodation reflex?
Cilliary muscle contraction = lens rounded
Pupil constriction = sphincter pupillae
Ocular Converge = medial rectus
What part of CN3 is used in sphincter pupillae + ciliary muscle
What is used in medial rectus muscle
SP + Ciliary = CN3 Parasympathetic
Medial Rectus = Motor nerve CN3
What parts of the visual cortex are used in the accomodation reflex?
Primary visual cortex
Association visual cortex
How is the association visual cortex used?
association visual cortex –> Edniger-westphal nucleus –> eye
Edniger-westphal is found where
Midbrain
Aqueous humour is found between what
Lens + Cornea
Aqueous humour is secreted by what?
Cilliary Body
what is the circular muscle of the eye
Sphincter pupillae
what is the radial muscle of the eye
what innervates it
Dilator Pupillae
SNS
Cataracts
Cloudy lens
Reabsorbtion of the aqueous humour is done where? What canal is present?
Sclera + canal of Schlemm
Middle ear –> mastoid air cells
Mastoid Antrum
Maculae detect =>
Linear Acceleration
Christae ampullaris =>
Angular acceleration + deceleration
Conduction deafness causes =>
Obstructed / altered transmission to tympanic membrane
Sensorineural deafness =>
Deafness caused by inner ear problems
Meyer’s loop lesion on the left side of the cortex
Superior Right Homonymous quadrantanopia
Primary pain and temperature afferents from the external ear are carried by which tract
Spinal tract
A person with congenital absence of the retinal rod cells will lack what?
will lack visual acuity
Frontal eye field is found where
Frontal medial
Decussation of ascending auditory fibres across the midline occurs between which brain regions?
Inferior colliculus
Information from vestibular passes to what structure of the cerebellum (lobe)
Flucculonodular lobe
information regarding the position of the left side of the body enter which peduncle of the cerebellum?
Left inferior
Low pitch sound will be interpreted by which part of the cochlear duct?
low pitch = Distal Cochlear Duct
Lower motor neurons from facial nerve wrap around which cranial nerve as they exit the brainstem?
Abducens
Axons found within the optic nerve have what cell type?
Ganglion
Cell bodies of the primary cochlear nerve fibre are located where?
Spiral Ganglion (organ of corti)
tectorial membrane passes into what space?
Cochlear Duct
Tensor tympani is innervated by what?
Trigeminal
Visual axis passes directly onto what?
Macula
visual information from the eye passes to what part of the nucleus?
Lateral geniculate nucleus
information regarding the right upper field vision travels via what to the occipital radiations?
Left meyers Loops
What is the difference between relative and absolute visual acuity?
Relative visual acuity is the visual acuity of an uncorrected eye
Absolute visual acuity is the visual acuity of a corrected eye (e.g. using glasses or contact lenses).
Convex lenses are used for
Hyperopia (far-sightedness)
Concave lenses are used for
Myopia (short-sightedness)
What specific deficit leads to red-green colour-blindness? Why are males more likely to be colour blind
than females?
X chromosome of the 23rd chromosome pair
males => 1 X
females => 2X (recessive)
Conductive deafness in terms of bone conduction
subject will be deaf to ordinary air conduction but will show no deafness to bone conduction.
Sensorineural deafness in terms of bone conduction
the subject will be deaf to both air and bone conduction
frontal eye field is found where? (lobe)
Lateral surface of the frontal lobe
