Brainstem Flashcards
what are the 3 parts of the brainstem?
- midbrain.
- pons.
- medulla oblongata.
what is the function of the brainstem?
to serve as a conduit for ascending and descending tracts.
to contain important reflex centres and the 12 cranial nerves.
the brainstem controls important automatic, involuntary reactions.
what does the brainstem connect?
the spinal cord to the brain.
what are the pyramidal tracts?
why are they named so?
the pyramidal tracts are the corticospinal and the corticobulbar tracts.
they are named as pyramidal tracts as they pass through the pyramids of the medulla.
what are the 3 types of cerebellar peduncles called?
- superior.
- middle.
- inferior.
where does corticospinal tract originate and terminate?
in the primary motor cortex (part of cerebral cortex) and the spinal cord.
where does the corticobulbar tract originate and terminate?
in the primary motor cortex and the medulla.
why does the cbulbar tract terminate earlier than the cspinal?
as the cbulbar controls muscles of the head and neck, therefore, the UMNs synapse with LMNs in various brainstem nuclei and cranial nerves.
Basically, they innervate the CNs so can stop once they have reached them.
what does the corticospinal tract control?
fine motor, skilled movements and execution of voluntary movement.
what does the corticobulbar tract control?
controls muscles of the head and face therefore facial expression, speech, and swallowing.
which 2 tracts run parallel and very closely to each other?
cbulbar and cspinal.
what does an ascending pathway refer to?
neural pathways in which info is sent from peripheral nerves to the cortex to the brain.
so from receptors to the brain.
what does the spinothalamic tract transmit info about?
pain, temp and light touch.
the spinothalamic tract is a part of what system?
anterolateral.
where does the spinothalamic tract originate and terminate?
it originates in nociceptors and terminates in the primary somatosensory cortex of the brain.
what is the second name for the dorsal column pathway?
the medial lemniscus pathway.
what info does the dorsal column pathway carry?
transmits info about fine touch, proprioception and vibration.
where does the dorsal column pathway originate and terminate?
it originates in cutaneous receptors and terminates in the primary somatosensory cortex of the postcentral gyrus.
name the components of the midbrain: (7)
tectum,
substantia nigra,
crus cerebri,
tegmentum,
cerebral aqueduct,
cerebral peduncle,
superior and inferior colliculi.
which 2 components of the midbrain make up the cerebral peduncles?
crus cerebri,
tegmentum.
which pathways are the superior and inferior colliculi’s respectively a part of?
superior = visual.
inferior = auditory.
what is the tectum?
the dorsal part of the midbrain.
what is the tegmentum?
the ventral part of the midbrain.
what is the substantia nigra?
a part of the midbrain and the basal ganglia that is important in reward and movement. it contains melanin, making it a dark colour.
what is the reticular formation?
a network of nerve pathways in the brainstem connecting the spinal cord, cerebrur and cerebellum.
it controls consciousness.
what are the 3 major nuclei of the reticular formation?
- raphe nuclei
- cholinergic reticular nuclei.
- noradrenergic neurons.
what is the raphe nuclei?
groups of neurones either in or adjacent to the midline of the brainstem.
what does the raphe nuclei do?
they synthesise and secrete serotonin.
when are raphe nuclei active?
in deep sleep.
what areas of the CNS to raphe nuclei project to?
spinal cord, brainstem, cerebellum, thalamus and cortex.
where are cholinergic reticular nuclei found?
in the pons and midbrain region.
when are cholinergic reticular nuclei active?
in awake state
where are noradrenergic neurons found?
in locus coeruleus.
when are noradrenergic neurons active?
in the awake state.
what do noradrenergic neurons regulate?
arousal and attention.
the reticular formation controls what?
- skeletal muscles.
- somatic and visceral sensations.
- ANS.
- endocrine NS.
- sleep, arousal and consciousness.
- pain modulation
why does a stroke occur?
when blood supply to the brain is cut off.
what are the 2 types of strokes?
- ischaemic
- haemorrhaegic
why does an ischaemic stroke occur?
because of inadequate blood supply. usually caused by blockage in the vessel.
why does a haemorrhagic stroke occur?
it’s caused by a rupture of blood vessels.
