midbrain Flashcards
How long is the midbrain?
The midbrain is about 2 cm (0.8 in) in length.
- What does the midbrain connect?
The midbrain connects the pons and cerebellum to the forebrain.
- What is the cerebral aqueduct?
The cerebral aqueduct is a narrow fluid-filled channel running through the midbrain.
- What are the four colliculi called together?
The four colliculi are called the corpora quadrigemina.
- What is the function of the superior colliculi?
The superior colliculi control visual reflexes.
- What is the function of the inferior colliculi?
The inferior colliculi control auditory reflexes.
- Where does the trochlear nerve (CN IV) emerge?
The trochlear nerve emerges below the inferior colliculi.
- How does the trochlear nerve travel after emerging?
The trochlear nerve wraps around the midbrain to the cavernous sinus.
- What does the superior brachium connect?
The superior brachium connects the superior colliculus to the lateral geniculate body and optic tract.
- What does the inferior brachium connect?
The inferior brachium connects the inferior colliculus to the medial geniculate body.
- What is the interpeduncular fossa?
The interpeduncular fossa is a deep depression between the crus cerebri.
- What is the posterior perforated substance?
The posterior perforated substance is a region with many small blood vessels.
- Where does the oculomotor nerve (CN III) emerge?
The oculomotor nerve emerges from the medial side of the crus cerebri.
- What are the two parts of the cerebral peduncles?
The two parts of the cerebral peduncles are the crus cerebri (front) and the tegmentum (back).
- What does the crus cerebri contain?
The crus cerebri contains descending tracts.
- What does the tegmentum contain?
The tegmentum contains nuclei and pathways.
- Where is the substantia nigra located?
The substantia nigra is between the crus cerebri and tegmentum.
- What is the function of the substantia nigra?
The substantia nigra controls muscle tone and connects with the cortex, spinal cord, and basal nuclei.
- What is the function of the cerebral aqueduct?
The cerebral aqueduct connects the third and fourth ventricles.
- What lines the cerebral aqueduct?
The cerebral aqueduct is lined with ependymal cells.
- What is the tectum?
The tectum is the part of the midbrain posterior to the cerebral aqueduct.
- What does the tectum contain?
The tectum contains the superior and inferior colliculi for visual and auditory processing.
- What is located in the inferior colliculus?
The inferior colliculus contains a gray matter nucleus.
- What pathway is the inferior colliculus a part of?
The inferior colliculus is part of the auditory pathway.
- Where does the inferior colliculus receive fibers from?
The inferior colliculus receives fibers from the lateral lemniscus.
- Where does the inferior colliculus send fibers?
The inferior colliculus connects to the medial geniculate body via the inferior brachium.
- Where is the trochlear nucleus located?
The trochlear nucleus is located in the central gray matter.
- How do trochlear nerve fibers exit?
The trochlear nerve fibers exit below the inferior colliculi and cross completely in the superior medullary velum.
- Where is the mesencephalic nucleus of the trigeminal nerve found?
The mesencephalic nucleus of the trigeminal nerve is found next to the cerebral aqueduct.
- Where does the superior cerebellar peduncle decussate?
The superior cerebellar peduncle decussates in the central part of the tegmentum before the cerebral aqueduct.
- Where is the reticular formation in the midbrain?
The reticular formation is located laterally in the midbrain tegmentum.
- Where is the medial lemniscus in the midbrain?
The medial lemniscus is located behind the substantia nigra.
- Where are the spinal and trigeminal lemnisci in the midbrain?
The spinal and trigeminal lemnisci are lateral to the medial lemniscus.
- Where is the lateral lemniscus in the midbrain?
The lateral lemniscus is behind the trigeminal lemniscus.
- What are the three descending tracts in the crus cerebri?
The descending tracts in the crus cerebri are corticospinal, corticonuclear, and corticopontine fibers.
- Where are corticospinal and corticonuclear fibers located in the crus cerebri?
Corticospinal and corticonuclear fibers are in the middle part of the crus cerebri.
- Where are frontopontine fibers located in the crus cerebri?
Frontopontine fibers are in the medial part of the crus cerebri.
- Where are temporopontine fibers located in the crus cerebri?
Temporopontine fibers are in the lateral part of the crus cerebri.
- What is the function of the superior colliculus?
The superior colliculus controls visual reflexes.
- What are the three main inputs to the superior colliculus?
The superior colliculus receives input from the optic nerve, visual cortex, and spinotectal tract.
- What are the two major outputs of the superior colliculus?
The superior colliculus sends output via the tectospinal and tectobulbar tracts.
- What reflexes does the superior colliculus control?
The superior colliculus controls reflex movements of the eyes, head, and neck.
- Where does the light reflex pathway end?
The light reflex pathway ends in the pretectal nucleus.
- How does the light reflex pathway reach the eye muscles?
The pathway relays to the Edinger-Westphal nucleus → oculomotor nerve → eye muscles.
- Where is the red nucleus located?
The red nucleus is located between the cerebral aqueduct and the substantia nigra.
- Why does the red nucleus appear reddish?
The red nucleus appears reddish due to iron pigment and rich blood supply.
- What are the three major afferent (input) connections of the red nucleus?
The red nucleus receives input from the cerebral cortex, cerebellum, and basal nuclei.
- How does the cerebral cortex connect to the red nucleus?
The cerebral cortex connects to the red nucleus via corticospinal fibers.
- How does the cerebellum connect to the red nucleus?
The cerebellum connects to the red nucleus via the superior cerebellar peduncle.
- What are the four major efferent (output) pathways from the red nucleus?
The red nucleus sends output to the spinal cord (rubrospinal tract), reticular formation (rubroreticular tract), thalamus, and substantia nigra.
- Where is the reticular formation located in the midbrain?
The reticular formation is in the tegmentum, lateral and posterior to the red nucleus.
- What is the function of the midbrain reticular formation?
The midbrain reticular formation plays a role in arousal and motor control.
- What are the main functions of the midbrain?
The midbrain relays sensory and motor information, controls vision and hearing reflexes, and contains important pathways for movement and coordination.
