Session 4 Flashcards
(23 cards)
What are the different layers of the eye?
Sclera, choroid, retina
What are the different parts of the retina and what cells do they contain?
Pigmented layer (next to choroid) - retinal pigmented epithelium Neural layer - (from superficial to deep) rods and cones to bipolar cells to ganglion cells
Describe the route of nasal and temporal fibres from the eye
Nasal - decussate at the optic chiasm
Temporal - run ipsilaterally
Where do the optic tracts run into?
Lateral geniculate nucleus
Where do the optic ratiations run into?
Primary visual cortex
What fibres does the upper optic radiation carry and through what lobe does it travel?
Fibres from the superior retinal quadrants (corresponding to the inferior visual quadrants)
Travels through parietal lobe
What fibres does the lower optic radiation carry and through what lobe does it travel?
Fibres from the inferior retinal quadrants (corresponding to the superior visual quadrants)
Travels through temporal lobe
What fibres are responsible for the nasal/temporal visual fields?
Nasal - temporal fibres
Temporal - nasal fibres
What is a cause of right monocular blindness?
Lesion of left optic nerve
Children - optic nerve glioma/retinoblastoma
Middle aged - optic sheath meningioma
What is a cause of bitemporal hemianopia?
Lesion at the optic chiasm
Pituitary adenoma, anterior communicating artery aneurysm
Where is the lesion for a left homonomous hemianopia?
Right optic tract
What results from a lesion in the right superior radiation?
Left inferior quadrantanopia
What results in macular sparing?
A stroke affecting the posterior cerebral artery damages most of the occipital lobe except the occipital pole which is supplied by the middle cerebral artery. This region represents the macula so its function will be spared.
Describe the steps in the pupillary light reflex
Light stimulates the afferent nerve, CNII. Synapses in pretectal area, giving rise to neurones supplying both Edinger-Westphal nuclei. Both CNIII are stimulated to cause direct and consensual pupillary constriction.
What 3 aspects should be seen on an accommodation reflex?
Convergance, constriction, convexity of the lens
What are the main divisions of the midbrain?
Tectum located posteriorly to the cerebral aqueduct - houses 2 superior and 2 inferior colliculi
Cerebral peduncles anterolaterally - internally they are further separated by the substantia nigra into the tegmentum (posterior) and crus cerebri
`What structure in the ear contains vibration sensitive hair cells?
Organ of corti
Outline the steps in the auditory pathway
Cochlea -> cochlea nucleus -> superior olive -> inferior lemniscus -> medial geniculate nucleus -> auditory cortex (in temporal lobe)
What are some common causes of hearing impairment?
Loud noise, congenital defects, infections (rubella, glue ear), ototoxic compounds (aminoglycosides), trauma, age, acoustic neuroma
What methods of assessment of hearing function are there?
Otoscope
Audiograms - plots sensitivity against frequency
What treatments are there for hearing impairment?
Hearing aids, cochlea implants, hair cell regeneration, cochlear nucleus implants
What is the function of the outer hair cells in the ear?
Provide further amplification to sound
Depolarization of hair cells is due to the entry of which ion?
Potassium (unusual!)
