Structures Flashcards
1
Q
What structures are in both the superior and inferior peduncle?
A
Cerebral peduncle
-basilar midbrain
- substantia nigra
Cerebral aqueduct and PAG
2
Q
Basilar midbrain
A
- both the superior and inferior peduncle
- descending corticospinal, corticobulbar, and corticopontine fibers
3
Q
The basilar midbrain portion of the cerebral peduncle is called
A
crus cerebri
4
Q
Substantia nigra
- _____ nucleus associated with ______
- ________ portion of the cerebral peduncle
- loss of these neurons results in _______
A
- both the superior and inferior peduncle
- dorsal portion of the cerebral peduncle
- extrapyramidal nucleus associated with basal nuclei
- parkinsons
5
Q
Cerebral aqueduct (of silvius) connects ____ and _____
A
- both the superior and inferior peduncle
- 3rd and 4th ventricles
6
Q
Key structures of superior midbrain includes:
A
- superior colliculus
- CN III nuclei
- Red nucleus
7
Q
Superior colliculus
A
- superior midbrain
- coordination of eye and head movements
8
Q
CN III nuclei
A
- superior midbrain
- oculomotor nerve nucleus: GSE
- edinger-westphal nucleus: GVE preganglionic parasympathetic, pupillary constriction
9
Q
Red nucleus
- type of nucleus?
- input from?
- contributes axons to?
A
- superior midbrain
- extrapyramidal motor nucleus
- receives input from the superior cerebellar peduncle
- contributes axons to the rubrospinal tract and inferior olivary nucleus
10
Q
What structures make up the inferior midbrain?
A
- inferior colliculus
- decussation of the superior cerebellar peduncle
- CN IV nucleus
11
Q
Inferior colliculus
A
- inferior midbrain
- auditory pathway reflexes and part of the conscious auditory pathway
12
Q
Decussation of the superior cerebellar peduncle (inferior midbrain)
A
- inferior midbrain
- efferent fibers from the deep cerebellar nuclei (dentate) cross the midline to synapse in the red nucleus and the VL nucleus of the thalamus
13
Q
CN IV nucleus
A
- inferior midbrain
- trochlear nucleus contributing GSE axons to the superior oblique muscle
- only CN to exit dorsally from brainstem
14
Q
Structures included in the Superior pons
A
- decussation of the superior cerebellar peduncle
- closure of the IVth ventricle
- superior cerebellar peduncle
15
Q
Decussation of the superior cerebellar peduncle (superior pons)
A
- Superior pons
- this fiber tract contains efferent axons from the deep cerebellar nuclei (dentate nucleus, mainly) bound for the contralateral red nucleu and the VL of the thalamus
- also contains the axons of the ventral spinocerebellar tract that are “re-crossing” the midline in this decussation
16
Q
Closure of the IVth ventricle
A
- Superior pons
- becoming the cerebral aqueduct
17
Q
Superior cerebellar peduncle
A
- Superior pons
- efferents of the cerebellum
- ipsilateral at this point, beginning its decussation
18
Q
Structures of the middle pons
A
- middle cerebellar peduncle
- CN V (3 of 4 nuclei)
19
Q
Middle cerebellar peduncle
A
- middle pons
- consists of descending pyramidal motor tracts (CST, CBT)
- transverse fibers of the pontocerebellar tract (crossing midline)
- deep pontine nuclei (receiving the corticopontine fibers)
20
Q
CN V nuclei in middle pons
A
- middle pons
- chief sensory : where GSA’s for touch and conscious proprioception synapse
- spinal tract and nucleus of V: extend caudally from here to C4; where the pain, temperature, and light touch GSA and GVA axons travel and synapse
- motor nucleus: where the SVE neurons arise and project axons to the muscles of mastication
- mesencephalic nucleus of V: SUPERIOR PONS TO SUPERIOR MIDBRAIN; GSA’s for unconscious proprioception from the face synapse
21
Q
Structures of the inferior pons
A
- caudal end of the basilar pons
- CN VI
- CN VII
22
Q
Caudal end of the basilar pons
A
- inferior pons
- caudal from here the corticospinal and corticobulbar tracts will be seen as the pyramids
23
Q
CN VI
A
- inferior pons
- the abducens nucleus for GSE’s to the lateral rectus muscle
24
Q
CN VII
A
- inferior pons
- facial nerve motor nucleus
- represents the SVE nucleus for muscles of facial expression
- (note facial colliculus)
25
Structures of the open medulla
- pyramids
- inferior cerebellar peduncle
- inferior olivary nucleus
- CN VIII nuclei
26
Pyramids
- open medulla
- as the transition from the basilar pons to the basilar medulla occurs, the corticospinal and the last fibers of the corticobulbar tracts takes up their namesake tract, the pyramids
- ventral most pyramidal shaped protrusions from the medulla
- will end as the decussation of the pyramids in the caudal-most closed medulla
27
inferior cerebellar peduncle
- open medulla
| - appear as the lateral "ears" of the tegmentum and represent the various spinal and olivary input to the cerebellum
28
Inferior olivary nucleus
- open medulla
- very convoluted nucleus of the ventrolateral tegmentum of the open (and most rostral of closed) medulla
- contributes to the "climbing fibers" to the contralateral cerebellum via the inferior cerebellar peduncle
29
structures of the closed medulla
- the obex
- the "necklace of cranial nerve nuclei"
- CN IX, X, XI (cranial portion), and XII
- the decussation of the medial lemniscus
- the decussation of the pyramids
30
The obex
- closed medulla
| - this is caudal end/beginning of the fourth ventricle
31
the necklace of cranial nerve nuclei
- closed medulla
- rostral to the decussation of the medial lemniscus
- sulcus limitans "folds" and the basilar nuclei are pushed dorsally, displacing the sensory (dorsal horn) nuclei laterally
- results in the consistent arrangement of these nuclei from medial to lateral: GSE, SVE, GVE, GVA, GSA, and SSA
32
CN IX, X, XI (cranial portion) and XII
- closed medulla
- all nuclei associated with these CN
- dorsal motor nucleus of X, nucleus ambiguus, hypoglossal nucleus.....etc
33
Decussation of the Medial Lemniscus
- closed medulla
- dorsal to central somatotopism is C, T, L, S
- fasciculi gracilis and cuneatus synapse in their nuclei
- the 2nd order afferents next cross the midline as the internal arcuate fibers and ascend to the medial lemniscus
34
Decussation of the pyramids
- closed medulla
- "final act" rostral to caudal in the brainstem
- lateral corticospinal tract will cross the midline and move dorsally to take up its more dorsolateral tegmental area of the cord white matter
- anterior corticospinal tract continues ipsilaterally until the level of input where it innervates the GSEs to the axial muscles bilaterally
