Flashcards in Forebrain Dz Deck (20):
what is the forebrain? what is it formed of?
area of brain rostral to the tentorium cerebelli (divides cerebellum and forebrain)
- formed of telencephalon (cerebrum) and thalamus (part of diencephalon)
Know where different regionsof the cortex lie
- olfactory bulbs and tracts
- forntal lobes
- parietal lobes
- temporal lobes
- occipital lobes q
Which cranial nerves do not exit the brainstem?
1 + 2
- all others exit the brainstem
Where do the olfactory bulbs and tracts lead to and what are they responsible for?
- perception of smell
- cell bodies in nasal epithelium
- cribiform plate
- limbic system
- cribiform lobe
what is specieal about CN1 and 2?
not really nerves
- olfactory tracts are collections of lots of small fibres
temporal lobe responsible for..
- adutiroy area
- vestibular concious perception
- pyriform lobe olfactory and limbic system (emotion)
frontal lobes responsible for..
- mainly motor area
- corticospinal and corticonuclear tracts of CONTRALATERAL body
parietal lobes repsonsible for..
sensory mainly, some motor areas (or to motor areas? hard to tell from notes..)
occipital lobes responsible for..
visual concious perception
Outline the visual pathway
- optic nerve [retinal ganglion cells, glial cells and meninges, myelinated extension of the brain]
- optic chiasm (lateral retina remains ipsilateral, medial retina decussates)
- optic tract
- lateral geniculate nucleus
- optic radiation
- occipital lobe
What is papilloedema?
- bulging of the optic nerve into the vitreous d/t optic neuritis
Outline the path of the menace response
- visual pathway
-occipital lobe association fibres to motor cortex
- projection fibres to PONTINE nucleus in pons (brainstem)
- transverse fibres to contralateral cerebellar cortex
- efferent cerebellar fibres to facial nuclei
- facial nerve to obicularis oculi m.
When may the menace be absent for reasons other than tract problems?
- first 10-12 weeks (learned response)
- disorientated patients
CLinical signs of forebrain dysfunction
> mental status
- altered (depression/delerium/confusion/stupor/coma)
- behavioural changes ( thalamic) eg. hemi-neglect syndrome where one visual FIELD is lost [eg. will only eat half of dinner etc.]
- always indicate forebrain involvement by definition
- normal OR
- head pressing
- body turn [pleurothotonus], head turn or circling towards side of lesion
> postural reaction deficits
- loss of concious postural reactions (eg. paw placement) on contralateral limb to lesion
> decreased facial sensation
- contralateral to lesion
- trigem branches all 3 have sensory component (+ mandibular has motor)
- pathway to parietal and frontal lobes
> NORMAL spinal reflexes
- (unless multifocal dz causing them elsewhere)
Which side of the brain do visual deficits in hemi-neglect syndrome indicate the lesion is on?
opposite side to visual defect side
Which side is the lesion with a left head turn?
What type of ataxia does forebrain involvmenet cause?
What are the 3 branches of trigem? Which are sensory and which are motor?
- all sensory
- mandibular only = motor to mm. of mastication
Which parasite can cause ^Intracranial pressure in the cat?
- Taenia parasitic cysts
- ^ ICP squashes cerebellum
-> transtentorial herniation and herniation of cerebellum through foramen magnum