Neuro Anatomy 5 - Vestibular/ Auditory and Visual Pathways Flashcards
What bone are the organs of hearing and balance in the inner ear located in?
Temporal bone
What is the name of the bony canal within the petrous portion of the temporal bone that transmits nerves and vessels from within the posterior cranial fossa to the auditory and vestibular apparatus?
Internal acoustic meatus
How many turns does the cochlea make?
2.5
What is the name of the hearing transducing structure?
Organ of corti
What type of neurones in the cochlea are stimulated by hair cells?
Bipolar neurons
What is the name for the group of bipolar neurones at the cochlea which are stimulated by hair cells?
Spiral ganglion
Where does the spiral ganglion transmit action potentials from and to?
From organ of corti
To cochlear nuclei in medulla
Where does CN VIII enter the CNS?
Laterally on the pons-medullary junction
Where do first order neurones from the cochlea pass?
From the spiral ganglion to the ventral cochlear nucleus (via the cochlear nerve) in the medulla where they synapse
Where does the 1st order neurone of the auditory pathways synapse?
On ventral or dorsal cochlear nucleus in the medulla
What is the name for the structure formed when some of the 2nd order neurones of the auditory pathway cross?
Where is this?
Trapezoid body
Pons
Do signals from the cochlea pass up the ipsilateral/ contralateral side?
Travel up both sides (from the trapezoid body - pons)
Where do the 2nd order neurones of the auditory pathway synapse?
Some = superior olivary nucleus at pons
All (including those that have synapses at superior olivary nucleus) = inferior colliculus of midbrainb
Where is the next synapse of the auditory pathway after the inferior colliculus of the midbrain?
Medial geniculate body in the thalamus
What do the auditory neurones from the medial geniculate body in the thalamus travel via to reach the primary auditory area of the cerebral cortex?
Sublentiform part of the internal capsule
Where is the primary auditory area of the cerebral cortex located?
Superior temporal gyri
What is the word for any of the number of small swellings in the roof of the midbrain involved in vision and hearing?
Colliculus
What 2 nuclei are important in sound localisation and as relays for spatial and tensor tympani reflexes?
Superior olivary nucleus
Nucleus of lateral lemniscus
What is another name for the auditory association cortex?
Wernicke’s area
Where is Wernicke’s area located?
Posterior section of superior temporal gyrus
Where are fibres carrying information regarding low frequency sounds end within the auditory cortex?
Anterolateral part
Where do fibres carrying information regarding high frequency sound end in the auditory cortex?
Posteromedial part
What is aphasia?
Inability to se language
Where is Broca’s area?
Within the frontal lobe of the dominant hemisphere (usually left)
What functions does Broca’s area have?
Functions linked to speech production
What area is damage in Broca’s/ motor/ expressive aphasia?
Broca’s area
Describe Broca’s aphasia?
Patient has difficult in producing language, often using few words and only saying the most important words in a sentence
They do not usually have difficulty comprehending language
What area is damaged in Wenicke’s/ sensory/ receptive aphasia?
Wernicke’s area
Describe Wernicke’s aphasia?
Patient has difficult comprehending language
Patients can manifest defects ranging from words out of order to meaningless words
What does maintenance of equilibrium use information from?
Vision
Proprioception
Vestibular apparatus (labyrinth)
How many vestibular nuclei are there?
How does information from the vestibular ganglion travel to these?
4
Via CN VIII
Describe the connections of the vestibular nuclei?
Many - to spatial awareness, inputs to eyes, inputs to cerebellum, inputs directly to spinal cord (particularly to anti-gravity muscles), to thalamus
Is projection of vestibular information onto the cerebral cortex unilateral or bilateral?
Bilateral
Where on the cerebral cortex does vestibular information converge?
Less well defined that for other senses -> no primary vestibular cortex
Area of parietal cortex just posterior to area of postecentral gyrus that represents the hand and mouth
Area just rostral to the primary auditory cortex
Posterior insular cortex
Does the optic nerve have oligodendrocytes or schwann cells?
Oligodendrocytes (more similar to a piece of brain tissue than a cranial nerve)
Where is the first synapse in the visual pathway?
Lateral geniculate nucleus in the thalamus
How do 2nd order neurones in the visual pathway project from the lateral geniculate nucleus (thalamus) to the visual cortex?
Via optic radiations
Path of first order neurones in optic pathway?
Optic nerve -> optic chiasma -> optic tract -> (synapse in thalamus on lateral geniculate nucleus)
Due to the lens, how are objects projected onto the retina?
Reversed and upside down
What part of the retina is something that is in the temporal visual field of the right eye projected onto?
Nasal part of the right retina
Does each optic tract, lateral geniculate nucleus, optic radiation and visual cortex deal with visual information from the ipsilateral or contralateral visual field?
Contralateral
Some information from the optic tract also travels to what structure? (apart from the lateral geniculate nucleus)
Superior colliculi
Aside from the visual pathway, what other inputs does the superior colliculi have?
Visual cortex
Frontal eye fields
Spinal cord
What are the outputs of the superior colliculi?
CN III, IV and VI
Motor nucleus of VII
Spinal cord
Where is the primary visual cortex locate?
Region around the calcarine sulcus in the occipital lobe
Where is the visual association cortex located?
In the region around the primary visual cortex in the occipital lobe
What gyrus is information from the lower visual field projected to?
Gyrus superior to the calcimine sulcus
What gyrus is information from the upper visual field projected to?
Gyrus inferior to the calcimine sulcus
What pole of the visual cortex does the macula project to?
Posterior pole (occupies a much greater proportion of cortex relative to size of visual field it covers)
What do fibres of the geniculocalcarine tract initially form?
part of the internal capsule
What do fibres of the geniculocalcarine tract that are carrying visual information from the upper half of the visual field initially do?
Loop atnerior around the temporal part of the lateral venatical in Meyer’s loop
Which part of the brain controls movement of eyes in response to visual stimuli e.g. tracking moving objects?
Visual cortex
Which part of the brain controls conscious movement of the eyes i.e. movements independent of moving visual stimuli?
Frontal eye fields
Where are the frontal eye fields located?
Frontal cortex
Is tracking movements of the eyes smooth or jumpy?
Smooth
Movements of command tend to be jumpy - saccadic eye movements
Where do parasympathetic fibres supplying constrictor pupillae originate?
Edinger-Westphal nucleus
What CN does parasympathetic fibres supplying constrictor pupillae travel within?
CN III
Where is the constrictor pupillae located?
Midbrain
Where do nerves supplying the majority of the eye muscles originate?
Oculomotor nucleus in the midbrain
Where do nerves supplying the superior oblique muscles originate from?
Trochlear nucleus of the midbrain
Where does the trochlear nerve decussate?
Between the inferior colliculi in the midbrain
Where do nerves supplying the lateral rectus muscle originate?
Abducens nucleus of the pons
What is the consensual light reflex of the pupillary light reflex when light is shone into the right eye?
Left pupil constricts
What causes the consensual light reflex of the pupillary light reflex?
The pretectal fibres project bilaterally to the Edinger-Westphal nucleus
What 3 changes are involved in the accommodation reflex?
Convergence of gaze
Contraction of ciliary muscles
Pupillary constriction
What is the name for blindness for half the field of vision in one or both eyes?
Heminaopia
Optic nerve
What is it called when all of the vision is lost in one eye?
Where is the problem most likely?
Monocular blindness
Optic nerve
What is it called when the temporal portions of vision are lost in both eyes?
Where is the problem most likely?
Bitemporal hemianopia
Optic chiasm
What is it called when the left visual field is lost in both eyes?
Where is the problem most likely?
Homonymous hemianopia
Optic radiation
In right handed people, which hemisphere is usually dominant?
Left
What types of fibres in the white matter of the cerebral hemispheres connect cortical sites lying in the same hemisphere?
What types of fibres in the white matter of the cerebral hemispheres
What types of fibres in the white matter of the cerebral hemispheres connect one hemisphere to the other, usually connecting areas with similar function?
Commissural fibres
What types of fibres in the white matter of the cerebral hemispheres connect hemispheres to deeper structure including thalamus, corpus striatum, brain stem and spinal cord?
Projection fibres
