brainstem Flashcards
what constitutes the brainstem
pons, medulla and mid brain
functions of the brainstem (in general)
- reflexive and unconscious behaviour
- modulation of various arousal and conscious states
- important in ANS control
- cranial nerves arise from here
where does the brainstem extend from/to
from the mamillary bodies (rostrally) to the pyramidal decussation (caudally)
dorsal and ventral external aspects of the midbrain
- dorsal - superior and inferior colliculi
- ventral - cerebral peduncles with interpenduncular fossa
what forms the facial colliculi
the abducens nucleus and the fibres of cranial nerve 8 (facial nerve)
dorsal and ventral external aspects of the pons
- dorsal - facial colliculi
- ventral - cerebellar peduncles
dorsal and ventral external aspects of the medulla
- dorsal –> caudally there are dorsal columns and nuclei - gracile and cuneate tubercle
- ventral –>rostrally - inferior olivary nuclei, caudally - pyramidal decussation
what is the tegmentum
that part of the brainstem that is continuous with the spinal cord
what is the tectum
the superior and inferior colliculi of the midbrain
what is contained in the tegmentum
the cranial nerves and the reticular formation
what is contained in the basis of the brainstem
decending motor fibres and things that help control it
function of the cranial nerves
supply somatic and visceral motor and sensory information to the head
which cranial nerve does not exit the brainstem ventrally
CN IV
which cranial nerves are exclusively motor
3, 4 and 6 - control eye movements
11 and 12
which cranial nerves are exclusively sensory
1, 2 and 8 - smell, sight and balance
which cranial nerves are mixed nerves
5, 7, 9 and 10
what is the rule of 4 for cranial nerves
4 cranial nerves exit the medulla (9-12)
4 cranial nerves exit the pons (5-8)
4 cranial nerves exit above the pons (1-4)
what arrives from the alar plate and basal plate developmentally
alar plate - sensory nuclei
basal plate - motor nuclei
what is the positioning of the motor and sensory nerves in the brainstem
motor - closer to the midline
sensory - more laterally
what are the 3 motor columns within the brainstem
general somatic motor
brachial motor
general visceral
what are the 3 sensory columns within the brainstem
general and special visceral
general somatic
special somatic
what is the reticular formation
a network of scattered cell bodies throughout the dorsal brainstem (like a spread out nuclei)
the reticular formation is continuous with…
- certain nuclei in the thalamus
- intermediate grey of the spinal cord
basic function of the rostral reticular formation (in midbrain and upper pons)
maintain alert conscious state
basic function of caudal brainstem (pons and medulla)
do things similar to the spinal cord - survival reflexes
variety of important motor reflex and autonomic functions
what are the 4 projection systems of the ascending reticular activating system and where are they
noradrenergic - locus ceruleus
dopaminergic - substantia nigra
serotonergic - dorsal raphe
cholinergic
what is the function of the ventrolateral medullary reticular formation
regulates the visceral functions of the vagus nerve
(GI - swallowing, vomiting
respiratory - rhythm, coughing, hiccupping, sneezing
cardiovascualr)
3 major long fibre tracts through the brainstem
dorsal column-medial lemniscus system
anterolateral system
corticospinal system
where does the corticospinal tract decussate
at the pyramidal decussation
which structures are associated with the basis (ventral) part of the midbrain, pons and medulla
midbrain - cerebral peduncles, substantia nigra, red nuclei
pons - CB nuclei, middle cerebellar peduncle
medulla - inferior olivary nuclei
explain the orientation and anatomy of the columns through the spinal cord
3 sensory columns - lateral
3 motor columns - medial
What are the 12 cranial nerves
olfactory optic occulomotor trochlear trigeminal Abducent Facial Vesticulocochlear Glossopharyngeal Vagus Accessory spinal Hypoglossal
What are the foramina associated with the first 4 cranial nerves
olfactory = cribiform plate optic = optic canal occulomotor = superior orbital fissure Trochlear = superior orbital fissure
what are the foramina associated with the trigeminal nerve
orbital branch = superior orbital fissure
maxillary branch = formaen rotundum
mandibular branch = formamen ovale
what is the foramina associated with cranial nerves 6-12
abducent = superior orbital fissure
facial = internal acoustic meatus –> stylomastoid foramen
vestibulocochlear = internal acoustic meatus
glossopharyngeal, vagus and accessory = jugular foramen
hypoglossal = hypoglossal canal
which brainstem “column/s” is the olfactory nerve associated with?
special sensory column
which brainstem “column/s” is the optic nerve associated with?
special sensory column
which brainstem “column/s” is the occulomotor nerve associated with?
somatic motor column
and
visceral efferent column - Edinger-Westfal nucleus
which brainstem “column/s” is the trochlear nerve associated with
somatic motor column
which brainstem “column/s” is the trigeminal nerve associated with?
mandibular branch - branchial arch column
and
somatic sensory column