BMB 1 - Brainstem Nuclei & Tracts Flashcards
Identify the three major portions of the brainstem in this image.
What are the three longitudinal portions of the brainstem?
Basis (basement - dark gray)
Tegmentum (floor - light gray)
Tectum (roof - labeled)
Which longitudinal tract of the brainstem contains tracts from the cortex (especially the corticospinal)?
The basis (basement - dark gray)
The tegmentum of the brainstem (the light gray) contains which cranial nerve nuclei?
III - XII
(all but I and II)
What structures are associated with the tectum?
Midbrain integrative structures - e.g. center for vision (superior colliculus) or hearing (inferior colliculus)
Identify the cranial nerves which emerge from the midbrain.
CN III and IV
Identify the cranial nerves which emerge from the pons.
V, VI, VII, VIII
Identify the cranial nerves which emerge from the medulla.
IX, X, XI, and XII
Which cranial nerves exit ventrally?
Which cranial nerves exit dorsally?
All but IV;
IV only
Where does the trochlear nerve exit the midbrain?
Dorsally; inferior to the inferior colliculus
Where does the trigeminal nerve exit the brainstem?
Near the middle cerebellar peduncle
Where does the abducens nerve exit the brainstem?
Medially; along the pontomedullary junction
Where does the facial nerve exit the brainstem?
Along the pontocerebellar junction;
lateral to CN VI
Where does the vestibulocochlear nerve exit the brainstem?
Along the pontocerebellar junction;
lateral to CN VII
Where does the glossopharyngeal nerve exit the brainstem?
The groove dorsal to the olive in the postolivary sulcus
Where does the vagus nerve exit the brainstem?
The groove dorsal to the olive in the postolivary sulcus
Where does the accessory nerve exit the brainstem?
It does not;
it exits the cervical spinal cord (not technically a cranial nerve)
Where does the hypoglossal nerve exit the brainstem?
Between the pyramid and the olive (in the pre-olivary sulcus)
In what structures do the dorsal columns end?
The gracile and cuneate tubercles
Of the cerebellar peduncles, which provide the major input to the cerebellum?
The middle cerebellum peduncles
Of the cerebellar peduncles, which provide the major output from the cerebellum?
The superior and inferior cerebellar peduncles
From caudal to rostral, what are the four main parts of the internal organization of the brainstem?
Closed medulla >
Open medulla >
Pons >
Midbrain
Of the four main parts of the internal organization of the brainstem (closed medulla, open medulla, pons, midbrain), in which do the fasciculus cuneatus and fasciculus gracilis terminate?
The closed medulla
This is a cross-section of what portion of the brainstem?
The closed medulla
(the otter)
This is a cross-section of what portion of the brainstem?
The open medulla
(the bulldog)
This is a cross-section of what portion of the brainstem?
The pons
(Snidely Whiplash)
This is a cross-section of what portion of the brainstem?
Midbrain
(the stingray)
What are the shape mnemonics for the four main parts of the internal brainstem organization as seen in cross-section?
Midbrain
Pons
Open medulla
Closed medulla
Stingray
Snidely Whiplash
Bulldog
Otter
In which of the four main parts of the internal brainstem organization does most sensory decussation occur (via the medial lemniscus pathway)?
Midbrain
Pons
Open medulla
Closed medulla
The closed medulla
Where are the nuclei gracilis and cuneatus in the brainstem?
The closed medulla
In which of the four main parts of the internal brainstem organization are the second-order sensory neuron cell bodies?
Midbrain
Pons
Open medulla
Closed medulla
The closed medulla
(the nucleus cuneatus and gracilis)
In which of the four main parts of the internal brainstem organization are the hypoglossal nuclei?
Midbrain
Pons
Open medulla
Closed medulla
The open medulla
In which of the four main parts of the internal brainstem organization is the inferior cerebellar peduncle?
Midbrain
Pons
Open medulla
Closed medulla
The open medulla
In which of the four main parts of the internal brainstem organization are the olives?
Midbrain
Pons
Open medulla
Closed medulla
The open medulla
The brainstem olive is connected to the cerebellum and helps facilitate _____________ movement.
The brainstem olive is connected to the cerebellum and helps facilitate pre-programmed movement.
In a cross-section of the pons (which looks like Snidely Whiplash), which part of the cross-section looks like a mustache way at the bottom of the section?
The ponto-cerebellar fibers
The substantia nigra and superior colliculi are both found in what section of the brain?
The midbrain
In cross-section of the midbrain (which looks like a stingray), describe where the superior colliculi and substantia nigra are.
Describe how the corticospinal tracts travel through the brainstem.
(The majority of decussation occurring towards the caudal portion)
Where do 90% of corticospinal fibers decussate (i.e. where does pyramidal decussation occur)?
The lower medulla
The corticospinal fibers come from Brodmann area 4, travel through the ___________ of the midbrain, travel through the _____ pontis of the pons, and decussate at the lower medulla.
The corticospinal fibers come from Brodmann area 4, travel through the cerebral peduncle of the midbrain, travel through the basis pontis of the pons, and decussate at the lower medulla (to then become the _lateral_ corticospinal tract in the spinal cord).
True/False.
The corticospinal tract travels mainly through the tegmentum of the brainstem (light gray).
False.
The corticospinal tract travels mainly through the ventral (basis) of the brainstem (dark gray area in previous image).
Describe where in the cross-sections of the brainstem you would find the corticospinal tract.
Note: this includes the midbrain, pons, pontomedullary junction, open medulla, and closed medulla.
Describe the pathways of the medial lemniscus and spinothalamic tracts through the brainstem.
Describe the locations of the medial lemniscus and spinothalamic tracts on cross-section of the closed medulla.
Describe the post-decussation pathway of the medial lemniscus as seen on cross-section of the open medulla, pons, midbrain, and inferior colliculus.
Describe the locations of the medial lemniscus and spinothalamic tracts on cross-section of the open medulla, pons, and midbrain.
The chief sensory tract (CN V) synapses in the ___________ nucleus, and the trigeminothalamic tract (CN V) synapses in the ___________ nucleus.
The chief sensory tract (CN V) synapses in the chief sensory nucleus, and the trigeminothalamic tract (CN V) synapses in the spinal tract of V nucleus.
Describe the location of the spinal nucleus of V in the closed medulla in relation to the medial lemniscus pathways.
Describe the locations of the spinal tract of V in the open medulla, pons, pontomedullary junction, and midbrain.
Identify the portions of the midbrain indicated by arrows.
