9.3 Brainstem Flashcards
What are the 4 cranial nerves above the pons?
1, 2, 3, 4
What are the 4 canial nerves attaching to the pons?
5, 6, 7, 8
What are the 4 cranial nerves attaching to the medulla?
9, 10, 11, 12
What are the 4 medial structures of the brainstem?
Coticospinal tract, medial lemniscus, medial longitudinal fasiculus, motor nucleus (3, 4, 6, 12)
What are the 4 lateral structures of the brainstem?
Spinocerebellar tract, spinothalamic, sensory nucleus (5) and sympathetic pathway
Where does swallowing, vomiting, ocughing and sneezing get generated and how
In the medulla by the pre motor nuclei innervating CN IX and X
Where does chewing get generated and how?
In the pons by the supratrigeminal premotor nucleus
Where does conjugate eye movements get generated and how?
Mid brain: by the pre motor nuclei innervating III, IV and VI
Where does the locomotor pattern generator occur and how?
In the pons/midbrain: by the pedunco-pontine nucleus and part of the locus coeruleus with input into the reticulospinal tract
Where does information about the internal environment get mapped onto?
The solitary nucleus - gets information from 9 and 10
Where do pain pathways map onto?
The thalamus, reticular formation, superior colliculus and periaqueductal grey matter
Where are the CV and Resp control centres?
Dorsolateral medulla (open medulla)
What supplies the pone?
paramedian, short circumferential and long circumferential branches of the basilar artery
What would a lesion in the basilar artery cause?
Locked in syndrome
What is the general arrangement of inputs to the brainstem?
Motor = medial, sensory = lateral, visceral = intermediate
Where is the pyramidal decussation and what occurs here and what will you be able to see?
Where the brainstem (medulla) and the spinal cord meet - corticospinal tracts will cross here
You will be able to see the fasiculus gracilis and cuneatus as well as the nucleus gracilis, you can also see the spinal trigneminal nucleus
What occurs at the sensory decussation and what can you see?
Fibres from the DC system will be crossing (nucleus gracilis and cuneatus) to form the medial lemniscus via the internal arcuate fibres
This is where you will start to see the inferior olivary nucleus
Why is it termed the open medulla?
The DC fibres have crossed leaving the central canal open dorsally as the 4th ventricle
What will you no longer see at the open medulla?
The nucleus gracilis and cuneatus as there fibres have cossed to form the medial lemniscus already
What is the new feature you will see at the open medulla?
The fourth ventricle and the inerior cerebellar peduncles
Where do fibres from the inferior cerbellar peduncles go from and to?
Fibres from the dorsal cerebellar and cuneo-cerebellar tracts and from the inferior olivary nucleus to the cerebellum
What occurs at the level of the pons?
The pontine fibres which have their cell bodies in the pontine nuclei cross the midline and enter the C/L cerebellum through the middle cerebellar peduncle
What will you see ventrally at the level of the inferior colliculus?
Substantia nigra and cerebral peduncles
What is the main feature at the level of the inferior colliculus?
Crossing of the superior cerebellar peduncles
What can you see in the interpeduncular fossa at the level of the infecior colliculus?
CN III
What are the new features in the midbrain at the level of he inferior colliculus?
substantia nigra, cerebral aqueduct and cerebral peduncles
What is the superior colliculus involved in?
visual reflexes, including a map of visual and somatosensory space
What is the new feature at the superior colliculus?
Red nucleus which is the fibres from the crossing of the superior cerebellar peduncles
What separates the cerebral peduncles and what are the composed of?
The interpeduncular fossa
Composed of all descending tracts that originate in the cerebral corex
What is the function of the reticular formation?
Resp/CV control
Arousal
Control of gate
Autonomic functioning
What happens to the NTs in the reticular formation?
They diffuse away from the site to have a greater range of action
What are the 3 regions of the reticular formation and what is their role?
Median/Raphe: source of serotenergic system
Paramedian: magnocellular and gigantocellular (efferent) - origin of reticulospinal
Lateral: Parvocellular (efferent) - sensory inputs
what is the role of the seratonergic system?
regulating mood and appetite (think SSRI = depression)
What is the role of the dopaminergic system and where do the cells originate from?
Initiation of movements, reward system
Originate from: Substantia nigra and ventral tegmental nucleus
What is the role of the noradrenergic system and where do the cells originate from?
Regulate attention, arousal and the sleep/wake cycle
Originate from locus coerelus
Where do cholinergic cells originate from?
Septal and basal forebrain nuclei and the pontomesencephalotegmental complex
What is the function of teh solitary nucleus and tract?
integrate and map sensory information from the internal environment and co-ordinate autonomic output to the brain stem and spinal cord
What are the inputs into the solitary nucleus?
VII, IX and X (carrying info from chemoreceptors)
