Anatomy And Physiology Flashcards
What is the acronym for quadrantanopias?
PITS
Parietal inferior
Temporal superior
In bitemporal hemianopia, if the upper quadrant defect was worse than the lower quadrant defect what would this suggest?
Suggests that there is inferior chiasmal compression eg a pituitary tumour
The reverse suggests Superior chiasmal compression eg craniopharyngioma.
What is damaged in horners syndrome?
Sympathetic trunk
Give rise to: miosis (small pupil), ptosis (droopy eyelid), anhidrosis (reduced sweating)
Which nerve is affected in a relative afferent pupillary defect (Marcus gunn pupil)?
Optic nerve (or severe retinal disease) Seen in the swing light test
What are the 3 layers of the eye made of?
Fibrous layer (cornea and sclera) - connect tissue
Vascular layer - has the choroid (posterior) and the cillary body (anterior) and the iris
Inner layer - lens projects light onto rentina
What receptors are found on the retina?
Rods - more of them register in greyscale, edge of the retina for peripheral vision
Cones - fine detail and colour (found in the centre of retina) (only work in bright light, blue and green receptors) localise in the fovea
Why do we have a blank spot in out vision, where does it occur?
There are no rods/cones above the optic disc causing a blind spot
Why is the pupil small in horners syndrome?
Sympathetic does dilation
Parasympathetic does constiction
In horners sympathetic lesion - eg no dilation on affected side
What muscles open and close the eye and the nerve supply?
Open - levator palpebrae superioris - cn3. Superior tarsal muscle - sympathetic
Close - orbicularis oculi muscle - temporal and zygomatic branches of cn7
Testing for horners syndrome?
Apraclonidine (iopidine) test
Dilates the affected pupil
Cocaine 4% - dilates unaffected pupil
Causes of horners syndrome
Central - going down - assoc with other brainstem or spinal cord problems eg Wallenberg syndrome
Pregangilonic - going back up - brachial plexus or thorax or lung or neck trauma
Postganglionic - assends with internal carotid artery to cavernous sinus, joins trigeminal plexus and becomes long cillary nerve
Post gang NOT get andhydrosis
Which structure compresses the top and bottom of the optic chiasm?
Top - crainiophragimia (lesion lower quadrant)
Bottom - pituitary (lesion upper quadrant)
