L6 - brainstem and cerebellum Flashcards
conduit
allows passage of long pathways between brain and spinal cord
general functions of the brainstem
- conduit
- integrative
- cranial nerves
reticular formation
control of consciousness, CVS, respiratory functions and perception of pain
integrative functions of the brainstem
receives motor information and modulates and influences this to make it more accurate and precise
main structures of the brainstem
midrain
pons
medulla oblongata
rostral location of the brainstem
midbrain is continuous with diencephalon
caudal location of brainstem
medulla is continuous with spinal cord
ventral location of the brainstem
lobed of the occipital bone
dorsal location of the brainstem
cerebellum
how many cranial nerves arise from the brainstem
10
ventricular structures running through the brainstrm
4th ventricle and cerebral aqueduct
location of 4th ventricle
between pons and medulla anteriorly and cerebellum posteriorly
location of cerebral aqueduct
level of midbrain
subdivisions of the brainstem
tectum
tegmentum
basal area
location of tectum
the roof
most dorsal
posterior to ventricular system
location of tegmentum
anterior to ventricular system
cranial nerve pathways and nuclei found here
location of basal area
most ventral
descending motor fibres found here
locked in syndrome
results from stroke at the level of the pons
why do eyes still move in locked in syndrome
these nerves arise above the pons
why are heart and breathing unaffected in locked in syndrome
we find these centres in the tegmentum
junction between pons and medulla
pontomedullary junction
pyramids
bumps in the brainstem as there is white matter fibres or cell bodies of neurones underneath them
decussation of pyramids
interrupt the anterior medial fissure and consists of descending motor fibres crossing over from one pyramid to the other
what separates the pyramids and olives
antero-lateral sulcus
where to olives lie
lateral to pyramids
hypoglossal nerve origin
antero-lateral sulcus
what cranial nerves arise from the postero-lateral sulcus
9,10,11
glossopharyngeal, vagus, accessory
where is the postero-lateral sulcus
lateral to olives
rhomboid fossa
floor of 4th ventricle
which side of the medulla are pyramids and olives found
ventral
on which side of the medulla can the floor of the 4th ventricle be seen
dorsal
structures seen on dorsal view of medulla
cuneate tubercle
gracile tubercle
cuneate facsiculus
gracile fasciculus
what are tubercles
swellings of fascicule at the top
what lies underneath the gracile and cuneate tubercles
white matter fibres and nuclei
which fibres are located on the dorsal side of the medulla
ascending sensory fibres
where are descending motor fibres found
desiccation of pyramids on ventral view of medulla
where are ascending sensory fibres found
dorsal view if medulla
most rostral part of the medulla
open medulla
most caudal part of the medulla
closed medulla
obex
marks the point where the 4th ventricle ends and becomes continious with the central canal which passes through the caudal medulla and into the spinal cord
closed medulla structures
- central canal in the middle
- cuneate and gracile tubercle at dorsal end
- pyramids at vental end
open medulla structures
- 4th ventricle
- no tissue of the medulla posteriorly
- olives looks like squashed paper bags
- inferior cerebellar peduncle
- basal area and tegmenjtum visible
junction between midbrain and pons
ponto-mesencephalic junction
function of pons
bridges two cerebellar hemispheres
fibres on pons
transverse pontine fibres
basilar groove
where basilar artery sits
which cranial nerves originate from the pons
5,6,7,8
trigeminal, abducens, facial, vestibulocochlear
where does CN6 originate
lateral to the midline of the pons
where does CN7 and CN8 originate
cerebellarpontene angle
cerebellarpontene
junction between pons and cerebella
cerebellar peduncles
where the brainstem attaches to the cerebella
superior cerebella peduncle
cerebellum to midbrain
middle cerebella peduncle
cerebellum to pons
inferior cerebella peduncle
cerebellum to medulla
which peduncle connects the cerebellum to the medulla
interior
which peduncle connects the cerebellum to the pons
middle
which peduncle connects the cerebellum to the midbrain
superior
facial colliculis
bump existing as something underlying them - formed due to some fibres of the facial nerve
structures in the tegmentum of the pons
starts picking up some of the middle cerebellar peduncle and cranial nerve nuclei
where is the nucleus of the facial nerve seen
caudal pons
nucleus of facial nerve
- Some fibres loop around the nucleus of the abducens nerve to emerge at the cerebellapontene angle
- These are called the internal genu of the facial nerve
prominent features of rostral pons prosection
- transverse fibres
- cerebral aqueduct at dorsal end
- basilar groove at dental end
rostral junction of pons
pontomesencephalic
caudal junction of the pons
pontomedullay
where does CN5 enter
mid-pontine level
main feature on dorsal view of pons
cerebellar peduncles
rostral most component of the brainstem
midbrain
key structures on the ventral view of the midbrain
maxillary bodies and cerebral peduncles
continuations of the midbrain rostrally
diencephalon
cerebral peduncles
a collection of descending motor fibres from the cortex
interpeduncular fossa
space between the cerebral peduncles
which cranial nerves emerge from the interpeduncular fossa
oculomotor
where does CN4 emerge from
midbrain dorsally and makes its way around the midbrain
most prominent features of the dorsal view of the midbrain
4 colliculi
- 2 superior
- 2 inferior
importance of superior colliculi
visual system
importance of inferior colliculi
auditory system
how are the colliculi attached to the thalamus
projections called brachium
what does the midbrain look like on a cross section
mickey mouse
substantia nigra
- contain dopamine containing neurones
- grey matter of the midbrain
location of substantial nigra
posterior to cerebral peduncles
most prominent feature of cross section of midbrain
cerebral aqueduct on the dorsal end
what do the cerebral peduncles look like on a cross section of the midbrain
mickey mouse ears
ascending reticular activating system
pass to the cortex and involved in consciousness
reticular nuclei
gives rise to descending motor pathway
which artery lies over the abducens nerve
anterior cerebral artery
location of oculomotor nerve CN3
sandwiched between superior cerebellar artery and posterior cerebral artery
role of cerebellum
coordination of movement, maintenance of balance and posture
location of cerebellum
- under occipital lobes of the cerebral hemispheres
- dorsal to the brainstem
ventral view of cerebellum
like looking through the 4th ventricle (from pons)
lobes of cerebellum
anterior and posterior
how are the anterior and posterior lobes of the cerebellum separated
primary fissure
how are the hemispheres of the cerebellum separated
vermis
floccunodular lobe
formed by the floccule and nodules in the middle of the cerebellum at the level of the horizontal fissure
location of flocculi
tucked under peduncles
location of tonsils
posterior to medulla
what could happen to the cerebellum in an increase in intracranial pressure
herniation of the tonsils which could compress the medulla
how is the cerebellum separated from the occipital lobes of the telencephalon
tentorium cerbelli
what are peduncles
white matter tracts
arterial supply to the cerebellum
- posterior inferior cerebellar artery
- superior cerebellar artery
- anterior inferior cerebellar artery
clinical signs of someone with cerebellar damage
- intention tremor (low frequency tremor in the hand)
- past pointing (inability to place a finger accurately on a selected point)
- dysdiadochokinesis (Inability to execute rapidly alternating movements, particularly of the limbs)
- uncontrollable eye movemnt
test for dysdiadochokinesis
tapping the right hand fast on the back of the left hand
test for past pointing
finger to nose test - ask them to touch your finger than their touch nose
location of cerebral aqueduct
behind the midbrain
origins of the brainstem
mesencephalon
myelencephalon
metencephalon
structure which lies above the midbrain
diencephalon
location of substantia nigra
posterior to peduncles in the midbrain
