7 Neuroanatomy: Brainstem II

Question 1

Midbrain

• What 2 major brainstem structures does the midbrain lie between?
• What important structure passes through the midbrain?
• There is an imaginary line that divides the diencephalon and the midbrain.
  
  • What 2 structures does this “line” connect?
    
    • How does this line relate to the cerebral aqueduct?
• What are the ventral boundaries of the midbrain?

Answer 1

Question 2

Midbrain

• What junction marks the merger of the cerebral aqueduct and 4th ventricle?
  
  • How does this relate to the isthmus of pons?
• What structure connects the midbrain to the cerebellum?

Answer 2

Question 3

Midbrain

• What are the 3 anatomically distinct components of the midbrain?
  
  • Which component contains the inf. and sup. colliculi?
  • Where does the periaqueductal gray fit?
  • Where does the substantia nigra fit?

Answer 3

Question 4

External Features of the Ventral Midbrain

• Where does the crus cerebri emerge, relative to the optic tracts?
  
  • Where do they disappear into?
• Where does CN III emerge, relative to the crus cerebri?
  
  • What fossa do they pass through?

Answer 4

Question 5

External Features of the Dorsal Midbrain

• Superior Colliculus
  
  • What area does its brachium extend from?
  • What 2 structures are on either side of this area?
• Inferior Colliculus
  
  • What structure does its brachium join up with?
• Trochlear Nerve
  
  • What junction does this nerve emerge from?

Answer 5

Question 6

Level of Inferior Colliculus

• Tectum
  
  • Is this on the rostral or caudal portion of the tectum?
  • What sensory pathway is the inferior colliculus an important relay component for?
    
    • Where dis this pathway receive ascending inputs from?
    • What is the name of the pathway that these inputs take to get to the inferior colliculus?
    • Where does this inferior colliculus send axons to?

Answer 6

Question 7

Level of Inferior Colliculus

• Tegmentum
  
  • What 2 structures surround the cerebral aqueduct here?
  • Central tegmental Area
    
    • What 3 important structures are in this area?
      
      • Which structure contains serotonergic neurons?
  • Lateral Tegmentum
    
    • What kind of pathways does contain?
    • What are the 4 pathways?

Answer 7

Question 8

Periaqueductal Gray Matter

• What structure does this surround?
• What does this structure represent the transition of?
• What are the 3 main important roles this area has?

Answer 8

Question 9

Nucleus of the Trochlear Nerve

• What structure does this nucleus lie beneath?
• What type of innervation does this nucleus have?
• What direction do the axons of it go?
• What happens to the axons before they exit the brain?
  
  • Do they exit ipsilaterally or contralaterally?
• What muscle does this cranial nerve innervate?
• What structure lies just beneath the nucleus of the trochlear nerve?
• How does damage to this nucleus manifest?

Answer 9

Question 10

Decussation of Superior Cerebellar Peduncles

• Where do the superior cerebellar peduncles originate from?
• At what level do they pass into the brainstem?
• What happens to the fibers of the superior cerebellar peduncles at the level of the inferior colliculus?
  
  • After this event, what 2 thalamic nuclei do the fibers terminate at?

Answer 10

Question 11

Level of Inferior Colliculus

• Crus Cerebri
  
  • Do these fibers contain ascending or descending fibers?
  • What kind of fibers are at the medial fifth of this structure?
    
    • The lateral fifth?
    • The middle 3/5th?
  • What region of the bodies are these fibers associated with?

Answer 11

Question 12

Substantia Nigra

• This structure is situated in the transitional area between what 2 structures?
• What is it functionally associated with?
• What are the 2 groups of cells in this structure?
  
  • Which group is medial?
  • Which neurotransmitters are released by each group?
  • Which group projects to the caudate nucleus and putamen?
  • Which group projects to the superior colliculus, thalamus, and pontine reticular formation?
• What common disease is associated with cell loss in the substantia nigra?
  
  • What kind of cells are lost in this disease?

Answer 12

Question 13

Level of the Superior Colliculus

• Tectum
  
  • Is the superior colliculus in the rostral or caudal portion of the tectum?
  • What kind of sensory innervation is the superior colliculus associated with?
  • What does it receive input from?
  • Where does it send projections to?
    
    • What is the name of the tract?
    • Why does it do this?
  • What ability does this structure mediate?

Answer 13

Question 14

Level of the Superior Colliculus

• Tegmentum
  
  • What cranial nerve nucleus here?
    
    • Before this nerve exists the area, what nucleus does it pass through?
  • What nucleus begins to replace the superior cerebellar peduncle?
  • What area contains dopaminergic fibers?
• What features are essentially the same as the inferior colliculus? (4)

Answer 14

Question 15

Oculomotor Nuclear Complex

• What is the v-shaped located between?
• What is this structure just rostral to?
• What are the 2 kinds of cells located in this here?
  
  • What are the corresponding nuclei’s names?

Answer 15

Question 16

Edinger-Westphal Nucleus

• What are the 2 cell types that make up this nucleus?
• Which eye muscles are innervated by this nucleus?
  
  • What reflexes are associated with this?
• What cell type is associated with stress, eating, and drinking?

Answer 16

Question 17

Red Nucleus

• What portion of the midbrain does this nucleus reside in?
  
  • What structure does it extend into?
• What important role does this nucleus play a role in?
  
  • How?
• How does it influence cerebellar activity?

Answer 17

Question 18

Level of Superior Colliculus

• Crus Cerebri
  
  • How does the structure and organization differ compared to the level of the inferior colliculus?

Answer 18

Question 19

Midbrain-Diencephalic Junction

• Where is the pretectal region located, relative to the midbrain?
  
  • What reflex is associated with this region?
• Posterior Commissure
  
  • Where is this structure located, relative to the periaqueductal gray?
  • Which nuclei synapse with cranial nerve nuclei that control extraocular eye movement?
    
    • What does this connection allow?
• What are the 3 thalamic structures associated with this area?
  
  • Which one is the largest?

Answer 19

Question 20

Pupillary Light Reflex

• Afferent Limb
  
  • What cranial nerve is associated with this?
  • What structures will have neural activity before the pretectal area/nucleus is innervated?
• Efferent Limb
  
  • What cranial nerve is associated with this?
  • What preganglionic nucleus sends parasympathetic fibers to the ciliary ganglion?
  • Where/how do postganglionic fibers travel after the ciliary ganglion?

Answer 20

Question 21

Vasculature of the Midbrain

• What arteries supply the medial regions? (2)
• What arteries supply the ventrolateral regions? (3)
• What arteries supply the posterior midbrain? (2)

Answer 21

Question 22

Weber Syndrome

• What arteries are lesioned in this syndrome?
  
  • What part of the crus cerebri is affected by this?
• This affects 2 fiber tracts and 1 nerve. What are they, and what deficits manifest?

Answer 22

Question 23

Claude Syndrome

• What arteries are implicated in this syndrome?
• What area of the midbrain does it affect?
• What nerves, nuclei, or fibers are affected, and what are their associated deficits?
• How do you differentiate this from Weber Syndrome?

Answer 23

Question 24

Benedikt Syndrome

• How is this syndrome similar to Weber Syndrome? To Claude Syndrome?
• What deficits can be observed in this syndrome?

Answer 24

Question 25

Parinaud Syndrome

• What are the 2 types of pathology that can cause this syndrome?
• What structure and area are always affected?
• What part of the midbrain is affected?
• What deficits can be observed?
  
  • What is the most notable deficit?

Answer 25