Brain Stem Flashcards
What do medullary pyramids contain?
Descending corticospinal tract fibers from ipsilateral cerebral cortex (specifically from the motor and premotor cortex)
Where does major crossing of the corticospinal tract take place in the medulla?
Pyramidal decussation
True or False:
The fascicles of the pyramidal decussation interrupt the anterior median fissure at the base of the medulla.
True. It’s the fascicles of the corticospinal tract that decussate in the midline
What cranial nerves exit at the pontomedullary sulcus?
CN VI, VII, VIII
What cranial nerve is associated with the pontopeduncular sulucs?
CN III
What structure lies in the basilar groove?
Basilar artery
What structures do the middle cerebellar peduncle fibers connect?
pons and cerebellum
What is the name of the junction of the medulla, pons, and cerebellum?
Cerebellopontine angle
Pontocerebellar fibers originate from what nuclei?
Pontine nuclei
How do pontocerebellar fibers travel to the cerebellum?
Fibers originate from the pontine nuclei, cross the midline, and travel through the middle cerebellar peduncle to the contralateral cerebellar hemisphere
The floor of the fourth ventricle is also known as…
the rhomboid fossa
What divides the rhomboid fossa into a right and left half?
Posterior median sulcus
What divides the rhomboid fossa into a superior and inferior portion?
Striae medullares
What structure divides the MEDULLA into right and left halves?
Dorsal median sulcus
True or False:
Both fasciculus cuneatus and fasciculus gracilis are descending sensory tracts to their correlating nuclei.
False; they are ASCENDING sensory tracts
What information does the ascending fasciculus cuneatus carry to the cuneate nucleus within the cuneate tubercule?
sensory, specifically proprioception from T6 and above
What information does the ascending fasciculus gracilis carry to the gracile nucleus within the gracile tubercule?
sensory, specifically proprioception from T6 and below
What specific pathway involves the ascending sensory tracts of fasciculus cuneatus and gracilis?
Dorsal Column Medial Lemniscus Pathway
How does the medial lemniscus and dorsal column pathway function to carry sensations from the body?
They can pick up sensory information that travels through afferent tracts to the thalamus, then to the brain
What sensory signals does the Dorsal Column Medial Lemniscus Pathway pick up?
Fine touch, vibration, visceral pain, proprioception, 2-point discrimination
What is the significance of the sulcus limitans?
It separates the cranial nerve motor nuclei from the sensory nuclei.
We can find it lateral and at the base of the medial eminence.
Where can we find the striae medullaris?
Wrapping around the inferior cerebellar peduncle at the lower part of the fourth ventricle.
Also crosses over the vestibular area and medial eminence, but disappears into the median sulcus
What is the significance of striae medullaris?
Forms cochlear division of the vestibulocochlear nerve
True or False:
The facial colliculus overlies the facial nucleus.
False; it overlies the ABDUCENT nucleus
True or False:
The vagal colliculus overlies the vagal nucleus.
True
True or False:
The hypoglossal colliculus overlies the hypoglossal nucleus.
True
True or False:
Vestibular area overlies vestibular nuclei.
True; partly in pons and partly in medulla
What is the midbrain tegmentum?
The ANTERIOR surface of the midbrain
What structures can we find in the midbrain tegmentum? (There are 7)
- Reticular formation
- Periaqueductal gray (PAG) matter
- Cranial nerve nuclei
- Sensory and motor pathways (corticospinal and spinothalmic tract)
- Red nucleus
- Substantia nigra
- Ventral tegmental area (VTA)
Function of red nuclei?
Motor control (muscle tone)
Function of substantia nigra?
Motor control (release of dopamine)
What is the midbrain tectum?
The POSTERIOR surface of the midbrain
What structures can we find in the midbrain tectum?
- Corpora quadrigemina
- superior and inferior colliculi
Function of superior colliculi?
Visual reflexes
Function of inferior colliculi?
Forms part of auditory pathway
What is the name of the connecting arm of white matter between superior colliculus and lateral geniculate body of the thalamus?
brachium of the superior colliculus
What is the name of the connecting arm of white matter between inferior colliculus and medial geniculate body of the thalamus?
brachium of the inferior colliculus
What cranial nerve is the only one to emerge dorsally from the brain stem?
CN IV - Trochlear n.
What cranial nerves are associated with midbrain?
CN III and IV
Occulomotor n. and trochlear n.
