Midbrain Anatomy Flashcards
Tectum, Tegmentum, and Crus cerebri. Which is where?
- Tectum = dorsal
- Tegmentum = central
- crus cerebri = ventral
What is contained in the Tectum?
-2 superior and 2 inferior colliculi
What is contained in the Tegmentum?
- Cerebral aqueduct & PAG
- Red nucleus
- decussation of superior cerebellar peduncles
- Substantia nigra (separates tegmentum from the crus cerebri)
What is contained in the crus cerebri?
-mostly corticobulbar and corticospinal pathways
What does the substantia nigra divide?
-tegmentum and crus cerebri
What are the nuclei of the midbrain separated by colliculus level?
Superior colliculus:
- Red nucleus
- CN III nucleus
Inferior colliculus:
- Substantia nigra
- CN IV nucleus
Where do CN IV fibers leave the midbrain?
- dorsal aspect
- just inferior to inferior colliculus
Where do CN III fibers leave the midbrain?
- ventral aspect
- just medial to crus cerebri
What role does the periaqueductal grey play?
-rich in enkephalins for modulation of autonomics and pain
What is contained within the medial longitudinal fasciculus?
- feeds from vestibular nuclei to nucleus of III, IV, and VI
- think eye movement
(white matter)
What is contained in the central tegmental area of the midbrain?
-reticular formation
=serotonin fibers which regulate wakefulness
Where is the location of the decussation of the superior cerebella peduncle?
-level of inferior colliculus in midbrain
What runs in the crus cerebri (cerebral peduncle) from medial to lateral?
Medial 1/5 = frontopontine fibers
Middle 3/5 = corticobulbar (med) and corticospinal (lat) fibers
Lateral 1/5 = parietal, occipital, and temporal lobes to pontine nuclei
What are the two parts of the substantia nigra?
- pars compacta (medially)
- Pars reticulata (laterally)
What is contained in the two parts of the substantia nigra?
Pars compacta = dopamine fibers to basal ganglia – important in Parkinson’s disease
Pars reticulata = GABA fibers to thalamus