Brainstem & Cerebellum Flashcards
What are the 3 general functions of the brainstem?
- Conduit
- Integrative
- Cranial nerve
How does the brainstem act as a conduit?
It allows ascending and descending pathways to reach the thalamus and cerebellum from the spinal cord
It contains relay nuclei
These are a collection of grey matter (nerve cell bodies) within the CNS

How does the brainstem have an integrative function?
It is involved in the control of cardiovascular, respiratory and consciousness
Consciousness is controlled by the reticular formation
It is involved in complex motor patterns (e.g. balance)
What does locked in syndrome result from?
An infraction of vessels in the ventral pons
as the reticular formation is intact, the patient is conscious but is unable to move
What is the ‘cranial nerve” function of the brainstem?
These are the head’s equivalent to spinal nerves
They are involved in sight, hearing, equilibrium and gustation
There are cranial nerve nuclei and reflex centres within the brainstem
What are the 3 structures within the brainstem?
- Midbrain
- Pons
- Medulla oblongata
What are the rostral, caudal, ventral and dorsal relationships of the brainstem?
Rostrally:
- midbrain is continuous with the diencephalon
Caudally:
- medulla is continuous with the spinal cord at the level of the foramen magnum
Ventrally:
- clivus of occipital bone
Dorsally:
- cerebellum

What components of the ventricular system run through the brainstem?
- IVth ventricle (IVth)
- Cerebral aqueduct (Caq)
This is continuous with the central canal of the spinal cord
These are cavities containing cerebral spinal fluid
Label the components of the ventricular system and brainstem


Which cranial nerves arise from the brainstem?
10 out of 12 cranial nerves arise from the brainstem
These are part of the PNS
They have sensory and motor parts

At any level of the brainstem, which 3 areas can be identified in cross section?
Tectum:
- the tectum is only present in the midbrain
Tegmentum:
- this contains cranial nerve nuclei and the reticular formation
Basal:
- descending motor fibres travel through here
Label the different areas in cross section of the brainstem


Where is the tectum found?
It is posterior to the ventricular system
The only region with substantial tectum (roof) is the midbrain (superior and inferior colliculi)

Where is the tegmentum found?
What does it contain?
Found anterior to the ventricular system
it contains cranial nerve nuclei and tracts, reticular formation and some ascending/descending pathways

Where is the basal found?
What does it contain?
It is found most anteriorly
it contains descending fibres from the cerebral cortex (pyramids, cerebral peduncles)

Which junction is labelled?

Pontomedullary junction (PMJ)
this is between the medulla of the brainstem and the pons

Where is the rhomboid fossa?
What is this?

It forms the floor of the IVth ventricle
It is exposed when the cerebellum is removed

Label the ventral view of the medulla


What is the passage of the cranial nerves visible on the ventral view of the medulla like?
IX and X are lateral to the olives in the anterolateral sulcus
XI is below X
IX, X and XI all leave through the jugular foramen
XII emerges between the pyramids and olives and leaves through the foramen magnum
What is behind the pyramids?
Descending motor fibres - the pyramidal tract
What happens at the decussation of pyramids?
Fibres travelling from the cerebrum cross over and travel on the opposite side of the spinal cord
Label the dorsal view of the medulla


What is the obex?
The point at which the IVth ventricle becomes continuous with the central canal of the spinal cord
What is the difference between the fasciculus cuneatus and fasciculus gracilis?
Fascicles contain a tract of white matter (axons)
Fasciculus cuneatus:
- contains ascending sensory information from the upper limb
Fasciculus gracilis:
- contains sensory information from the lower limbs
What is the difference between the open and closed medulla?
If you cut below the obex, this section is the closed medulla as there is brain tissue dorsally and centrally
If you cut above the obex, this is the open medulla as the IVth ventricle is anterior
What are the sections through the midbrain?


Label the closed and open medulla sections

White matter is shown as black due to the staining
the nucleus within the olive (shown in rostral medulla) is part of the visual system

What are the functions of the anterior median fissure, anterolateral sulcus and posterolateral sulcus?
Anterior median fissure:
- separates the two pyramids of the medulla
- contains descending motor fibres
Anterolateral sulcus:
- separates pyramids from olives
- hypoglossal nerves emerge here
Posterolateral sulcus:
- dorsal to the olives
- vagus and glossopharyngeal nerves emerge here
Which pathway are the gracile and cuneate fascilicles part of?
They are part of the dorsal column pathway
this carries sensory information from the body to the brain
What 2 junctions are labelled?


Label the ventral view of the pons


What travels in the basilar groove?
Basilar artery
Which nerves arise from within the cerebellopontine angle?
VII (facial) and VIII (vestibulocochlear)
Label the dorsal view of the pons


What is the function of the cerebellar peduncles?
They connect the brainstem to the cerebellum
What forms the facial colliculus?
Fibres of the facial nerve (VII) loop around the nucleus of CN VI
they emerge at the pontomedullary junction
the facial colliculus is due to the fibres of CN VII looping around VI
Injury to CN VI can negatively affect VII
Label the cross sections of the caudal and rostral pons


How is the pons positioned?
It is transversely orientated and bridges between the two cerebellar hemispheres
Caudally:
- medulla (pontomedullary junction)
Rostrally:
- midbrain (pontomesencephalic junction)
Where do the nerves on the ventral view of the pons emerge from?
Cerebellopontine angle:
- this is where the medulla and pons join the cerebellum laterally
- facial and vestibulocochlear emerge here
Pontomedullary junction:
- abducens nerve emerges here
mid-pontine level:
- trigeminal nerve enters here
What are the functions of the 3 cerebellar peduncles?
Superior:
- connects the midbrain to the cerebellum
- forms roof of IVth ventricle
Middle:
- connects pons to cerebellum
Inferior:
- connects medulla to cerebellum
What junction is shown?

Pontomesencephalic junction of the midbrain

Label the ventral view of the midbrain


Where do CN III and IV emerge from?
CN III emerges from the interpeduncular fossa between the cerebral peduncles
CN IV emerges from the dorsal view of the midbrain
Label the ventral view of the midbrain


What is the role of the brachium of the superior and inferior colliculi?
The brachium connects the colliculi to the thalamus
What is significant about CN IV?
It is the only cranial nerve that emerges from the dorsal view of the midbrain
Label the midbrain at the level of the inferior colliculi?


What is the main feature of anterior view of the midbrain?
The main feature is the cerebral peduncle
This is separated by the interpeduncular fossa
The oculomotor nerve emerges from the interpeduncular fossa
What are the main features of the dorsal view of the midbrain?
The paired superior and inferior colliculi
What is the difference in function of the superior and inferior colliculi?
Superior colliculus:
- associated with the visual pathway
Inferior colliculus:
- Associated with the auditory pathway
Where does the trochlear nerve emerge from?
Inferior to the inferior colliculi and at junction with the pons
it is the only nerve to emerge from the dorsal surface
What is the reticular formation?
A complex, multisynaptic network of neurones within the tegmentum of the brainstem

What are the roles of the reticular formation?
Reticular nuclei:
- give rise to a descending motor pathway - reticulospinal tract
Vital autonomic centres:
- e.g. respiratory, cardiovascular
Cells giving rise to ascending reticular activating system:
- these cells pass to the cortex and are involved in consciousness
- damage leads to coma
- pain modulation
- sleep wake cycle
- arousal
Label the blood supply to the brainstem


Label the blood supply to the brainstem


Label the cranial nerves
Which ones are missing and where do they originate from?

I and II are extensions of the forebrain
IV comes from the dorsal aspect of the midbrain

What actions is the cerebellum primarily involved in?
It is primarily involved in coordination of movement, maintenance of balance and posture
What is the location of the cerebellum?
It is found under the occipital lobes of the cerebral hemispheres
it is attached to the brainstem by three paired cerebellar peduncles - superior, middle and inferior
Label the cerebellar peduncles


What are the views of the cerebellum?


Label the superior/dorsal surface of the cerebellum

The vermis is the middle portion between the 2 hemispheres

Label the inferior/ventral surfaces of the cerebellum

