Exam #3: Organization of the Brainstem

Question 1

What is the only pure sensory CN nucleus located in the brainstem?

Answer 1

CN VIII

Question 2

What is the importance of the sulcus limitans?

Answer 2

This is the anatomic demarcation of motor & sensory function:

• Medial= motor
• Lateral= sensory
• Intermediate= both

Question 3

Embryologically, what structure are the sensory nuclei derived from?

Answer 3

Alar plate

Question 4

Embryologically, what structure are the motor nuclei derived from?

Answer 4

Basal plate

Question 5

What cell type lines the ventricular system/ central canal?

Answer 5

Ependymal

Question 6

What is the mylencephalon?

Answer 6

Medulla

Question 7

What is the landmark for the rostral medulla?

Answer 7

Open 4th ventricle

Question 8

What is the significance of the open 4th ventricle in the medulla, from an embryological standpoint?

Answer 8

Formation of the 4th ventricle causes the sensory nuclei to transition from a dorsal position to a dorsolateral position

Question 9

What is the mesencephalon?

Answer 9

Midbrain

Question 10

What is the metencephalon?

Answer 10

Cerebellum & pons

Question 11

What are the landmarks for the caudal medulla?

Answer 11

Caudal= closed 4th ventricle

• Olivary nuclei
• Pyramids

Question 12

What long tracts are contained in the pyramids of the medulla?

Answer 12

Corticospinal tract

Question 13

What is the function of the corticospinal tracts?

Answer 13

Motor output (UMN)

Question 14

What is the function of the medial lemniscus?

Answer 14

Proprioception & discriminative touch

Question 15

What are the internal arcuate fibers associated with?

Answer 15

DC/ML

*These are the fibers that cross from the DC to the ML

Question 16

What does the open 4th ventricle signify on cross-section?

Answer 16

Rostral medulla

Question 17

What are the landmarks for the caudal pons?

Answer 17

Basis pontis
Open 4th ventricle
Cerebellum

Question 18

What is the landmark for the caudal midbrain?

Answer 18

SCP decussation

Question 19

What CN nuclei is associated with the caudal midbrain?

Answer 19

Trochlear

Question 20

What is the landmark for CN IIII?

Answer 20

Red nucleus

Question 21

Where do the pyramids decussate?

Answer 21

Caudal medulla (spinomedullary junction)

• Lateral cross
• Anterior don’t

Question 22

Where does the spinothalamic tract cross?

Answer 22

At the spinal level innervated

Question 23

Where does the DC/ML decussate?

Answer 23

Caudal medulla via the internal arcuate fibers

Question 24

What is the function of the solitary nucleus?

Answer 24

Taste from CN X, IX, & VII

Thus, it is in the medulla ( CN IX & X) and the pons (VII)