Intro to Brainstem

Question 1

Hallmark of a brainstem lesion

Answer 1

• ipsilateral cranial nerve signs +
• contralateral long tract (e.g. spinothalamic, corticospinal, dorsal column)

Question 2

Cerebellum connections with the brainstem

Answer 2

• attached via fiber bundles = “peduncles”
• inferior cerebellar peduncle = spinal cord info ==> cerebellum & connects cerebellum to vestibular nucleus and inferior olive
• middle cerebellar peduncle = cerebral cortex info ==> cerebellum via pontine nuclei
• superior cerevellar peduncle = cerebellum info ==> cerebral cortex via thalamus

Question 3

Components of the brainstem

Answer 3

• superior to inferior:
  
  • midbrain
  • pons
  • medulla

Question 4

Cranial Nerves : I - XII

Answer 4

• CNI = Olfactory
• CNII = Optic Nerve
• CNIII = Oculomoter Nerve
• CNIV = Trochlear Nerve
• CNV = Trigeminal Nerve
• CNVI = Abducens Nerve
• CNVII = Facial Nerve
• CNVIII = Vestibulocochlear Nerve
• CNIX = Glossopharyngeal
• CNX = Vagus Nerve
• CNXI = Accesory Nerve
• CNXII = Hypoglossal

Question 5

Ventral portion of midbrain =

Dorsolateral surface of midbrain =

Dorsal aspect ventricular feature =

Answer 5

• ventral surface =
  
  • crus cerebri aka “cerebral peduncles”
  • exit point for CNIII (oculomotor)
• dorsolateral surface =
  
  • superior colliculi (2)
  • inferior colliculi (2)
• dorsal aspect ventricular feature =
  
  • cerebral aqueduct

Question 6

Ventral portion of pons =

Dorsal surface of pons =

Answer 6

• ventral portion =
• basilar pons = bulging portion
  
  • coextensive w/basilar artery
• dorals portion = surrounds ventral portion of 4th ventricle
  
  • embranced by superior and middle cerebellar peduncles

Question 7

Ventral surface of medulla =

Rostral surface of medulla =

Caudal surface of medulla =

Answer 7

• ventral surface
  
  • white matter tracts = “pyramids”
• rostral surface = floor of 4th ventricle
• caudal surface = joins with spinal cord

Question 8

Dorsal portion of brainstem = (name)

Answer 8

“tegmentum”

Question 9

Cranial nerves arising above midbrain

Answer 9

• CNI = olfactory
• CNII = optic

Question 10

CN arising @ midbrain

Answer 10

• CN III = oculomotor
  
  • medial
  • emerges just superior to pons
• CN IV = trochlear
  
  • arises from dorsal aspect

Question 11

CNs arising @ pons

Answer 11

• CN V = Trigeminal
  
  • lateral aspect
  • ~halfway between superior and inferior aspects of pons
• CN VI = Abducens
  
  • medial, inferior
• CN VII = Facial
  
  • just lateral to abducens, inferior
• CN VIII = Vestibulocochlear
  
  • “double nerve”
  • lateral, inferior

Question 12

CNs arising @ medulla

Answer 12

• CN IX = Glossopharyngeal
  
  • lateral, superior
• CN X = Vagus
  
  • lateral, just inferior to CN IX
• CN XI = Spinal Accessory
  
  • includes cervical nerve roots
  • extends to exit just inferior to CNX
• CN XII = Hypoglossal
  
  • lateral, inferior to CN X/CN XI

Question 13

Features of the medulla

Answer 13

• inferior olive
  
  • ventral, superior, lateral
• pyramids
  
  • ventral, medial
  • white matter tracts (corticospinal tract) running along ventral aspect
• deccusation of the pyramids
  
  • crossing of pyramidal axons

Question 14

Tract locations @ medulla

Answer 14

• corticospinal = @ pyramids
• dorsal column/medial lemniscus = ventro-medial
• spinothalamic = lateral
• spinal-trigeminal tract/nucleus = lateral, slightly dorsal to spinothalamic

Question 15

Tract locations @ pons

Answer 15

• corticospinal = ventral
• dorsal column/medial lemniscus = central
• spinothalamic = lateral, slightly dorsal

Question 16

Tract locations @ midbrain

Answer 16

• corticospinal = @ cerebral peduncles
• dorsal column/medial lemniscus = ventro-lateral
• spinothalamic = lateral, slightly dorsal