Control lecture 3: Brainstem and cerebellum

Question 1

What are the functions of the brainstem?

Answer 1

•Conduit

–Allows ascending and descending pathways to reach thalamus and cerebellum from spinal cord

•Integrative

–Cardiovascular, respiratory and consicousness (reticular formation)

•Cranial nerve

–Head’s equivalent to spinal nerves

–Also sight, hearing, equilibrium and gustation

–Cranial nerve nuclei

Question 2

What are the boundaries of the brainstem?

Answer 2

Caudally – Medulla is continuous with the spinal cord at level of the foramen magnum

Rostrally – Midbrain is continuous with the diencephalon (thalamus, hypothalamus etc)

Ventrally – Clivus of occipital bone

Dorsally – Cerebellum

Question 3

Which compenents of the ventricular system run through the brainstem?

Answer 3

Fourth ventricle and cerebral aquaduct

Question 4

How many of the 12 cranial nerves arise from the brain stem?

Answer 4

10 (III-XII)

Question 5

From which of the primary brain vesicles is the most of brainstem derived excluding the midbrain (but including the cerebellum)?

Answer 5

Rhombencephelon

Question 6

From which of the primary vesicles is the midbrain derived?

Answer 6

Mesencephelon

Question 7

What kind of fibres do the pyramids (medulla) contain?

Answer 7

Descending motor fibres.

Question 8

What is the name of the groove that seperates the pons and medulla and what happens there?

Answer 8

The pontomedullary sulcus - basilar artery is formed here.

Question 9

Which cranial nerve comes off at the groove between the pyramid and olive and what is its function?

Answer 9

CNXII (12) - hypoglossal. Motor nerve to tongue.

Question 10

What is the name of the space between the cerebral peducles and which cranial nerve is given off here (ventral)?

Answer 10

Interpeduncular fossa - CNIII (3) - oculomotor nerve.

Question 11

Which part of the brainstem is attached to the middle cerebellar peduncle?

Answer 11

Pons

Question 12

Which part of the brainstem is attached to the inferior cerebellar peduncle?

Answer 12

Medulla oblongata.

Question 13

Which part of the brainstem connects to the superior cerebellar peduncle?

Answer 13

Midbrain.

Question 14

What are the gross divisions of the dorsal brainstem?

Answer 14

Superior and inferior colliculi

Question 15

Which is the only cranial nerve to come off the dorsal aspect of the brainstem, directly inferior to the inferior colliculus, and what does it do?

Answer 15

CNIV (4) - trochlear - controls one of the six mucles that move the eye.

Question 16

What is a fascicle?

Answer 16

A tract of white matter.

Question 17

What sort of information runs through the gracile or cuneate fasicles of the medulla oblongata?

Answer 17

Specific pinpoint touch and proprioception.

Question 18

What lies at the most superior part of the dorsal aspect of the medulla oblongata?

Answer 18

The cuneate and gracile nuclei

Question 19

What is the reticular formation?

Answer 19

Within the tegmentum of the brainstem is a complex, multisynaptic network of neurons – the reticular formation.

Question 20

What are the components of the reticular formation and what are its functions?

Answer 20

• Reticular nuclei – give rise to a descending motor pathway (reticulospinal tract, see Term 3)
• Vital autonomic centres – eg. respiratory, cardiovascular
• Cells giving rise to Ascending Reticular Activating System – pass to the cortex and involved in consciousness (damage = coma)
• Modulate pain
• Sleep wake cycle
• Arousal

Question 21

What are the three areas of the brainstem that can be identified in crossection?

Answer 21

Tectum (most dorsal), tegementum, and basal.

Question 22

Which is the only region of the brainstem to have a substantial tectum?

Answer 22

Midbrain - superior and inferior colliculi

Question 23

What structures would be found within the tegmentum?

Answer 23

Contains cranial nerve nuclei and tract, reticular formation and some ascending/descending pathways.

Question 24

What structures are found within the basal part?

Answer 24

Descending fibres from cerebral cortex (pyramids, cerebral peduncles).