Brain Stem Flashcards
What are the 2 parts of the brainstem?
the midbrain (mesencephalon)
the hindbrain (rhombencephalon)
What is the midbrain continuous with?
the forebrain
What is the hindbrain continuous with?
the spinal cord
In older textbooks, what were the 3 divisions of the brainstem?
midbrain
pons
medulla oblongata
the brainstem controls the muscles of:
the eye, face, mouth, and throat; control of the salivary and lacrimal glands
the brainstem controls the internal organs of the:
thorax
abdomen
the brainstem controls sensations from:
the face, mouth, and throat, including taste
the special sense organs for vision, hearing and balance
the brainstem controls the coordination of movement of:
the limbs
the trunk
the brainstem has centres for controlling:
breathing
micturition
defecation
the brainstem has centers for maintenance of:
alertness
the brainstem acts as a corridor for:
long motor and sensory pathways that connect the brain with the spinal cord
the brainstem is a place of origin of:
descending motor pathways
what are all of the key functions of the brainstem?
-the control of the muscles of the eye, face, mouth, and throat; control of the salivary and lacrimal glands;
-control of the internal organs of the thorax and abdomen;
-receiving sensation from the face, mouth, and thro
at, including taste;
-receiving sensation from the special sense organs for vision, hearing and balance;
-coordination of movement of the limbs and trunk
-centers for control of breathing, micturition, and defecation;
-centers for maintenance of alertness;
-acting as a corridor for long motor and sensory pathways that connect the brain with the spinal cord;
-and as a place of origin of descending motor pathways.
The brain stem is connected with the muscles and sensory organs of the head through what?
cranial nerves 3 - 12
What is the structure of the brainstem?
The brain stem has a basic cylindrical structure, but there are major outgrowths from the dorsal surface
What are the dorsal outgrowths on the midbrain called?
the superior colliculi
the inferior colliculi
what are the superior and inferior colliculi?
two pairs of rounded bumps on the dorsal surface of the midbrain
what is the superior colliculus a receiving center for?
visual pathways
what is the inferior colliculus a receiving center for?
auditory pathways
what is the large outgrowth from the hindbrain called?
the cerebellum
During early development, where does the cerebellum grow?
the rostral part of the hindbrain
(just caudal to the midbrain)
In a brainstem section, what may be stained to show a clear picture of the main pathways in the brain stem?
myelinated fibers
When staining for myelinated fibers, what do nuclei appear as?
they do not stain and appear as pale areas in these sections
What are sections of the caudal hindbrain similar to?
sections of the cervical spinal cord
describe the pyramidal decussation:
The relocation of the corticospinal tract from its lateral position in the spinal cord to a ventral position in the pyramid of the opposite side.
what direction does the corticospinal tract travel?
descending
What level of the brainstem is the pyramidal decussation at:
caudal hindbrain
What do the gracile and cuneate fasciculi terminate in?
the gracile and cuneate nuclei
what fibers of the gracile and cuneate fasciculus cross the midline?
the internal arcuate fibers
what is the newly formed crossed tract of the gracile and cuneate fasciculus called?
the medial lemniscus
after forming, where is the medial lemniscus situated?
dorsal to the pyramids
what direction does the medial lemniscus travel, and what does it reach?
rostrally
the thalamus
what is the crossing of fibers from the gracile and cuneate fasciculus called?
the somatosensory decussation
after the gracile and cuneate fibers cross the midline, what is progressively vacated?
the dorsal region of the brainstem
once vacated, what takes up the remaining space in the dorsal region of the brainstem?
the fourth ventricle
What is the most outstanding feature at the level of the caudal end of the 4th ventricle?
the inferior olive
the caudal end of the 4th ventricle is a thin tube that is continuous with:
the central canal
in more ___ sections, the 4th ventricle expands to cover most of the ___
- rostral
- whole dorsal surface of the hindbrain
What 3 large nuclei in the hindbrain project to the cerebellum?
the external cuneate nucleus
the inferior olive
the basilar pontine nuclei
What are the 3 large nuclei in the hindbrain that project to the cerebellum collectively referred to as?
precerebellar nuclei
The fibers traveling from the inferior olive and the pontine nuclei do what to reach the cerebellum?
cross the midline
Because the pontine nuclei are huge, when they cross the midline, the crossing:
forms a massive outgrowth on the ventral surface of the hindbrain
The fibers traveling from the hindbrain to the cerebellum form 2 thick bundles called:
the inferior cerebellar peduncle
the middle cerebellar peduncle
The inferior cerebellar peduncle contains what?
the crossed olivocerebellar fibers