Neuroanatomy/exam and localisation Flashcards
describe the innervation of the bladder
ANS
symp and somatic = relax detrusor and inc sphincter tone
fills and impulse to pons - says its full
parasymp - contracts detrusor
somatic inhibit = ext sphincter relax and symp are inhibited so int sphincter relaxes
UMN lesion to nerves supplying the bladder = ?
can’t express itself
LMN to bladder = ?
dribbles
desc the anatomy of the innervation to the eye
1st n stem –> t1-3
2nd n t1-3 –> cr cervical ganglion
2rd from here to eye
what does this ANS supply to the eye achieve
- dilate pupil
- orbitalis m (periorbita, eyelids, 3rd eyelid)
- ciliaris m
- sm m in b vessels and sweat glands
what is horners syndrome
- miosis
- upper lid ptosis
- 3rd eyelid protruding
- enopthalmos
what is the bbb
tightly joined endothelial cells alongside the foot-processes of astrocytes
what % of drugs get past the BBB
5%
how does the chemical trigger one work then
its not past the BBB
name the 3 layers of the meninges
dura mater
arachnoid
pia
desc the flow of CSF
lat ventricles –> inter ventricular forament
- -> 3rd v
- -> mesencephalic aqueduct
- -> 4th v
- -> lateral apertures
- -> subarachnoid space
which domestic spp has a surprisingly large vol of CSF
horse
what is the fact of olfactory, where is the cell body
smell - perception
cell bodies in olfactory epithelium (cribriform plate -ish ) not ganglion
synapse of olfactory bulb –> prirform lobe
why is the optic nerve not a true nerve
surrounded by oligodendrocytes and meninges
what m does the oculomotor control
D, V, M rectus
V oblique
and elevator palp superioris
oculomotor also has a parasymp fat what is it
pupillary constriction
what n controls the D oblique
trochlea - OF THE CONTRALATERAL SIDE
what about the L rectus - what controls that
abducens
what is the fact of the trigeminal
facial sensation
motor MM
out of the three trigeminal branches - which is the only one with the motor function for the MM
mandibular
what is the fact of the VII
motor to facial expression
sensory to R 2/3 tongue an palate - inc taste
PS to lacrimal, mandible and s-l glands
where does the facial nerve run on its way out of the brain
thru acoustic meatus –> stylomastoid foramen and middle ear ( at this point the PS fibres separate)
what is the relevance of the chords tympani
carries facial fibres from the middle eat to serve tongue in taste and sensation
what does the vestibulocochlea do
hearing and balance using R in inner ear –> medullar
GP nerves =
motor to pharynx and palate
sensory to cd 1/3 tongue and pharynx
PS to parotid and zygomatic glands
nuclei is with X in medulla
what is the role of the X
m- larynx, pharynx (with GP) and oesophagus
s - larynx, pharynx (with GP) and thoracic/abdo viscera
PA - ALL cr thoracic and abode viscera
what is the role of XI, why is it a CN
trapezius, sternocephalicus and brachiocephalicus
what does XII do
m - tongue
what are the fct LMN
efferent (m) neurones connecting CNS to muscle that needs innervating
describe the process of AP prop at NMJ
Ca++ channels open ACh released --> bind to post-syn R Na open depol contract
desc the ‘reflex’ arc basic
dendritic stim
sensory periph nerve –> D root and synapses in d column
direct reflex (patella) or interneurone (withdrawal)
then exit via V root to motor periph nerve
syn in muscle
why are reflexes useful to vets
localise the lesion
FL= C6-T2
HL = L3-S3
can you feel pain without reflex and have a reflex without pain>
yes. a reflex can localise lesions, but doesn’t affect prognosis if missing
perception of pain w/wo reflex is a negative prognostic factor! pain fibres shouldn’t be damage (v deep)
what is the UMN system and its fct
in the CNS, synapse with LMN in GM of SC.
initiate vol movement, maintain muscle tone and control activity
2 tracts - extra + pyramidal
what are the extra and pyramidal tracts
pyramidal = skills, c. cortex extrapyramidal = bstem. tonic mech for posture, spinal reflexes.
what is the diff bw unconscious and conscious proprioception? what tracts do nerves travel in?
- unconsc = segmental reflex, info –> cerebellum. spinocebellar DL tract - ipsilateral
- conscious = info –> cerebral cortex. fascicles gracilis and cuneatus - contralateral at medullar
what is the purpose of the endolymph and how is balanace identified
to move relative to perilymph (any labyrinth) with head movement. this connects to utriculus –> saccule and cochlear
what is the crust ampullaris?
end of semicircular canal (ampulla) is neuroepithelial hairs in gelatinous cupola.
what is the macula
uticulus and saccule there are oval plaques with neuroepithelium covered in gelatinous membrane with otoliths
where are the nuclei locations for the vestibular nuclei?
4 x by pons and medulla which go out to:
- SC
- bstem
- cerebellum
what is the medial longitudinal fsciculus (MLF)
where axons of vestibular nerves meet nuclei of CNIII, IV and VI (coord eyes)
other than the MLF, where else do nerves from the vestibular nuclei go
SC - to + extensor m, inhibit flexors and inhibit contralateral extensor
RF - for motion sickness
thalamus - to perceive balance
cerebellum - inhib
what layer of the cerebellum continues to divide after birth
germinal layer
what is the fct of the cerebellum
reg motor activity
coordinate and refine movement
maintain equilibrium
regulate tone to maintain posture
what afferent (s) nerves synapse in the cerebellum
proprioceptive n - spinocerebellar tract vestib visual auditory UMN - allows reg of motor fct
desc the position of the optic disc
V-L
what are the % of axons that cross to controlat side at the optic chiasm
birds/fish = all H/R = 90% D = 75 C = 65 Us = 50
what part of the brain result in perception of sight
occipital cortex
what is the PLR and the motor response
PLR - most are contralateral PS oculomotor nerve
motor - R colliculus –> CN III, IV, VI and cervical SN –> move towards visual stim
how can you assess conscious perception of sight?
menace
how you can you asses s the PLR
shine a light
how is sound transmitted into nerve impulse
ossicles vibrate –> move perilymph, basilar membr moves and detected by hair cells which bend sterocilia = impulse
where is hearing consciously and reflexly detected
consciously = temporal bilaterally reflex= Cd colliculus
what causes noise induced deafness
XS noise exposure kills hair cells
where is the limbic system mainly and where does it mainly project to
based - c.cortex and diencephalon (thal and hypothal)
project - hypothal
where do UMN synapse for parasymp and symp NS
rostral = para cd = symp
what is hypocretin and where is it synthesised
regulates sleep
hypothalm
what inv has the hypothalm got with the adenohypophysis
regulates by secreting neuro-endocrine hormones
what is the point of the thalamus
conscious perception of all sensory paths
m n relay
projects diffusely with into from ARAS and cerebral cortex/thalamus
what is the ARAS
asc reticular activating system
what are the fct of the ARAS
arouse
conscious awake
prepare brain for info
where does the ARAS receive info from
everywhere
why does the ARAS have a role in how bored you get or how easily you learn>
should stimulate your brain to want to learn, be awake etc - so if not = easy bored etc
what parts of the brain control mentation.
forebrain and bstem
what are the levels of mentation
- alert
- disoreintated
- depressed
- stuporous
- comatose
what area controls behaviours
f-brain
what is hemineglect syndrome
when a structural lesion to fbrain, the animal ignores half the world
a lesion where could cause a head tilt
vestibular dz (either central or peripheral)
a lesion where could cause a body turn
fbrain.
called aversion syndrome
what is opisthotonus
bwds arching of head, neck and spine from muscle spazm, seen in tetanus etc
what are the differences bw:
- de-cerebrate rigidity
and
- de-cerebellate rigidity
de-cerebrate rigidity
- ALL limbs extended
- due to inhib UMN
- lesion = R bstem
- stuporous/comatose
de-cerebellate rigidity
- hyper-extension - FL only
- loss of the inhib of stretch and antigrav mechanism
- lesion = R cerebellum
- normal mentation
what is Schiff-sherrington?
hyper-extension of FL and paralysis of HL
lesion = T/L spine
where are the 3 places a lesion could be which would result in ataxia
spinal (subtle - reduced info from CNS)
vestibular (off balance)
cerebellar (drunken - rate, F and range differ)
what is the diff bw paralysis and paraplegia
loss of voluntary movement
also have mono, para, hemi, tetraparesis
what is non-ambulatory paresis
when with support, movement it seen - different from paralysis
what are the grades for spinal lesions
1-5
1 = no deficit, just pain; 3 = paresis, non-ambulatory; 5 = no pain sensation
name some postural tests
paw postition (upside down) hopping (lift 1 or 3 limbs) hip sway whelbarow extensor postural thrusts placing responses (at table, good for cat)
name some spinal reflexes
- withdrawals, myotactic FL & HL & panniculus
why are spinal reflexes useful
to ID whether UMN or LMN
desc the myotactic tests in the FL
ext carpi radialis - strike the m at belly –> ext carpus
biceps - strike over digital end of b.brachii and brachialis –> flex elbow and contract muscle
triceps - strike at insertion on olecranon –> ext of elbow and carpus
desc the myotactic in HL
patella - strike patella tendon –> ext limb
cr tibial - strike PX –> hock ext
gastrocnemius - strike –> hock ext
perineal - stim perineum with thermometer –> contracts
desc withdrawal
pinch digit –> reflex contraction of flex = withdraw limb. hppens wo need for pain sensitisation!
desc the panniculus response
pinch skin –> moves 2 x vertebral spaces cr’ally to synapse with lateral thoracic nerve for both L+R –> then synapse with brachial plexus –> bilat twitch
why is the panniculus reflex useful
can ID whether T3-L3 lesions or brachial plexus lesions (C6-T2) depending on when the reflex stops
what does the palpebral reflex test
V (opth or max) + bstem
–> VII (to blink)
what does the corneal reflex test
V (opthal) + bstem
–> VII (to blink)
what is physiological nystagmus controlled by
VIII (vestibulocochlear) + bstem. if lost - commonly inc IOP
–> III, IV, VI (to move eyeball)
what controls the menace reponse (learnt at 10-12wo)
II (optic) + fbrain, cerebellum and bstem
–> VII (facial - to move eyelids)
what is sensory to stim of nasal mucosa
V (opthalm) + fbrain, bstem
what controls the PLR
optic + bstem
–> III (to change pupil size + some parasymp/symp nn)
what is tested by the gag reflex
IX (GP) and X (vagus) + bstem
–> same output
name main signs of a forebrain lesion
- disorientation/depression
- contralat blindness (abn menace, normal PLR)
- normal gait
- ipsilat circuling/head turn/pressing
- decr postural responses in contralat limbs
- behavioural changes, hemi-neglect and seizures
why is the bstem so critical
- ARAS regulation centre for CV and resp CN III --> XII all sensory and motor tracts pass through vestibular nuclei
what are the signs of a bstem lesions
- depression, stupour coma
- CN 3-12 deficits
- vestibular signs
- paresis + dec postural resp of ALL/ipsilat limbs
- de-cerebrate rigidity (all limbs)
- R or CV abn
what are the signs of cerebellar lesions
- normal mentation
- normal vision + PLR but ipsilateral abn menace
- vestibular signs (controls bstem role)
- ataxia, wide-base stance, hypermetria
- intention tremor
- de-cerebellate rigidity
- delayed but hypermetric postural response
if there is a lesion in the vestibular system, there wil be path nystagmus, can you tell which side the lesion is
yes - on the side with the slowest nystagmus phase
the vestibular system has elements both in PNS and CNS. how can you tell from the signs where thelesion is
PNS = horizontal or rotationary nystagmus CNS = vertical mainly
what is a paradoxical head tilt?
one in the opp direction to lesions w signs of cerebellar dz
lesion is in the flocculonodular lobe or cd. cerebellar peduncle
is the lesion is C1-T2 or T3-S3 which limbs are effected?
All limbs
or HL
what reflexes test LMN
spinal reflexes
- C6-T2 = FL
- L4-S3 = HL
what would a lesion in C1-C5 cause
all or hemi paresis
normal spinal reflexes
norm tone
horners, resp issues, urinary retention
a lesion in C6-T2 =
all or hemi /deficits and paresis
reduced: tone, atrophy, spinal reflexes in FL and panniculus
horners, resp issues, urinary retention
a lesion in T3-L3
HL paresis and deficits
normal spinal reflexes
reduced panniculus cd to lesion
a lesions L4-S3
HL paresis and defects in 1+
reduced: tone, atrophy, spinal reflexes in HL, anal tone and perineal reflex
what are the signs of oa motor neuropathy
flaccid paralysis
reduced tone
atrophy
reduced spinal/CN reflexes
what are the signs of a sensory nerve neuropathy
decr sensitisation and self mutiliation increases (para-aesthesia)
reduced spinal/CN reflexes
give an examples of a cause of the following:
pre-syn, post-synaptic and enzymatic junctionopatby
pre - clost botulinum
post - myasthenia gravis
enzymatic - OPs
what are the only indication of myopathies
generalised weakness/exercise intol (stiff)
what are the 3 main causes of generalised myopathy
congen/inherited
inflam or infectious
metabolic
what does a painful myopathy suggest might be the cuase
inflam
space occupying
trauma
