Caudal Midbrain

Question 1

Inferior colliculus

Answer 1

A stop in the auditory pathway where the lateral lemniscus ends and the brachium of the inferior colliculus begins, in turn carrying auditory information to the medial geniculate nucleus of the thalamus.

Question 2

Periaqueductal gray

Answer 2

Site of origin of the descending pain control pathway that relays in raphe nuclei of the rostral medulla and caudal pons (among other connections).

Question 3

Cerebral aqueduct

Answer 3

Continuous rostrally with the third ventricle and caudally with the fourth ventricle.

Question 4

Lateral lemniscus

Answer 4

Ending in the inferior colliculus; the next stop in the central auditory pathway. “Golf ball on a tee.”

Question 5

Trochlear nucleus

Answer 5

Lower motor neurons for the contralateral superior oblique muscle. GSE.

Question 6

Medial longitudinal fasciculus (MLF)

Answer 6

At this level, fibers from vestibular nuclei and abducens interneurons, active in coordinating eye movements.

Question 7

Raphe nuclei

Answer 7

Widely projecting serotonergic neurons that collectively blanket the CNS. Those in rostral brainstem levels like this project mainly to the cerebrum.

Question 8

Spinothalamic pathway

Answer 8

Mostly crossed fibers of second-order spinal neurons conveying pain and temperature information to the thalamus, reticular formation, and midbrain. At this level, it also includes a contribution from the spinal trigeminal nucleus.

Question 9

Medial lemniscus

Answer 9

The principal ascending pathway for tactile and proprioceptive information. Originates in the contralateral posterior column nuclei and terminates in the thalamus (VPL). At this level, it also includes a contribution from the trigeminal main sensory nucleus on its way to VPM.

Question 10

Reticular formation

Answer 10

No description.

Question 11

Decussation of the superior cerebellar peduncles.

Answer 11

Cerebellar output fibers crossing on their way to the red nucleus and thalamus (VL).

Question 12

Corticopontine fibers

Answer 12

From the ipsilateral cerebral cortex, in the cerebral peduncle.

Question 13

Corticospinal and corticobulbar fibers

Answer 13

From the ipsilateral precentral gyrus and adjacent cortex areas.

Question 14

Last few pontine nuclei

Answer 14

Source of pontocerebellar fibers that cross the midline and form the middle cerebellar peduncle.