Brainstem and Diencephalon

Question 1

What are the three parts to the brainstem?

Answer 1

• Midbrain
• Pons
• Medulla

Question 2

In which cranial fossa does the brainstem lie in?

Answer 2

Posterior

Question 3

Embryologically, which vesicles of the numeral tube give rise to the brainstem?

Answer 3

• Mesencephalon (midbrain)
• Rombencephalon (hindbrain)
• Metacephalon -> pons and medulla

Question 4

What are the cavities (of ventricular system) that lie in the brainstem?

Answer 4

Cerebral aqueduct

Question 5

What is the name of the groove which separates the pons from the medulla?

Answer 5

Pontomedullary junction

Question 6

Which nerves emerge from the pontomedullarly junction?

Answer 6

Abducens, facial and vestibularcochlear

Question 7

Which crania nerves that emerge from the pontomedullary junction has the longest intracranial course?

Answer 7

Abducens

Question 8

What is the clinical significance of the long intracranial course of the abducens nerve?

Answer 8

Vulnerable to injury by increased intracranial pressure or other mechanical factors such as intracranial fractures of cerebral artery aneurysms

Question 9

What would be the consequence of injury to the abducens nerve?

Answer 9

Loss of motor innervation to the lateral rectus -> eye adducts

Question 10

Name three structures of the surface of the medulla and state their function

Answer 10

• Pyramids - tracts carrying motor fibres (voluntary control)
• Decussation of the pyramids - where motor fibres in pyramids cross over
• Olives - contain olivary uncle; inferior olivary nucleus assists in cerebellar motor learning and functioning. The superior olivary nucleus belongs to the auditory system and assists with sound perception.

Question 11

What structure does the open part of the medulla open onto?

Answer 11

4th ventricle

Question 12

Through which foramen does the medulla pass to become the spinal cord?

Answer 12

Foramen magnum

Question 13

What is the middle cerebellar peduncle made up of?

Answer 13

Centripetal fibres - incoming fibres

Question 14

What part of the brain lies immediately superior to the midbrain?

Answer 14

Thalamus (part of diencephalon)

Question 15

What part of the brain lies immediately inferior to the midbrain?

Answer 15

Pons

Question 16

Name two features of the midbrain

Answer 16

Cerebellar peduncles and superior and inferior colliculi

Question 17

What are the fibres of the cerebral peduncles made up of and were are they destined for?

Answer 17

Centrifugal fibres -> outgoing fibres (mostly motor)

Question 18

Name two features of the posterior surface of the pons ?

Answer 18

Trigeminal nerve (CN V) and middle cerebellar peduncle

Question 19

What are the two components of the diencephalon?

Answer 19

Thalamus and hypothalamus

Question 20

Which two parts do the components of the diencephalon lie between?

Answer 20

Cerebrum and midbrain

Question 21

What are the surface projections visible on the surface of the hypothalamus called?

Answer 21

Mamillary bodies