Lecture 2: Brainstem

Question 0

What cranial nerves exist in the brainstem?

Answer 0

Cranial nerves 3-12 are in the brainstem so if we have a lesion there, we will see cranial nerve problems

Question 1

The brainstem
Contains?
Damage to it results in?
Pictures on slides 3 and 4

Answer 1

Brainstem
• Contains:
• Cranial nerve nuclei (n=11/12)
• Long tracts transmitting somatosensory impulses from body to thalamus.
• Long tracts transmitting motor impulses from primary motor cortex to spinal cord.

Damage results in:
• Somatosensory or motor dysfunction • Cranial nerve malfunction

Question 2

The brainstem is composed of the?

Answer 2

Midbrain
Pons
Medulla
Axons from primary motor cortex passes down through the brainstem, decussate and medulla oblongata and enter spinal cord…..

Question 3

Motor axons forming the pyramidal tract descend through?

Slide 6

Answer 3

Motor cortex➡ corona radiata➡ internal capsule ➡ midbrain (cerebral crus)➡ pons➡ medulla oblongata (pyramids) ➡spinal cord

Question 4

Label the shit out of slide 7 and 8

Answer 4

Yep

Question 5

What does the Tectum contain?

What does the tegmentum contain?

Answer 5

• Quadrigeminal
plate:
• Superior colliculus x2
• Inferior colliculus x2
• (Colliculus = “small mound”)
• Dorsal surface of cerebral aqueduct.

Tegmentum “Covering”
• Located between
tectum and base.
• Ventral to cerebral aqueduct.
• Dorsal to substantia nigra.
• Contains:
• red nucleus
• nucleus of CN III
• nucleus of CN V
• Reticular formation

Slides 10 and 11

Question 6

Red nucleus
The colour is from what?
Receives inputs from___ and ______.
Gives rise to the _______➡ which controls flexor muscle tone.

Answer 6

• Colour from high content of Fe (iron).
• Receives inputs from cerebral cortex and cerebellar nuclei.
• Gives rise to rubrospinal tract => controls flexor muscle tone.
Slide 11

Question 7

Substantia nigra
• Brown colour due to _____.
• Projects to ______.
• Death of dopaminergic cells => Parkinson’s disease => bradykinesia & hypokinesia (which is?)

Answer 7

• Brown colour due to high content of melanin.
• Projects to striatum (caudate nucleus + putamen) & thalamus.
• Death of dopaminergic cells => Parkinson’s disease => bradykinesia & hypokinesia (difficulty in initiating and performing voluntary movements).
Slide 12

Question 8

Describe the basis pedunculi, know we’re it is and what it contains?

Answer 8

Cerebral peduncle = tegmentum + basis pedunculi.
• Contains corticospinal and corticopontine tracts
Slide 14

Question 9

What is the mesencephalon blood supply?

Answer 9

Posterior communicating artery
Posterior cerebral artery
Superior cerebellar artery
Slide 15

Question 10

The cerebral aqueduct 
Located between \_\_\_\_\_ and\_\_\_\_\_\_.
• Surrounded by\_\_\_\_\_\_\_\_ \_\_\_\_\_.
• Interconnects \_\_\_ and \_\_\_ventricles.
• Blockage = \_\_\_\_\_\_

Answer 10

Located between tectum and
tegmentum.
• Surrounded by periaqueductal grey matter.
• Interconnects 3rd and 4th ventricles.
• Blockage = hydrocephalus.

Question 11

Label the coronal section of the brain on slide 17
Also the pons extends from ___ to ______
Anterior (ventral) surface consists of ____ bundles of fibres that become continuous laterally with _______.
Slide 18
The base of the pons contains?
The tegmentum contains?
The pons is connected to the cerebellum by the _____

• Contains nuclei that mediate several auditory and _____ functions.
• Input from ______and communicates with _____for balance.
• Sensory input from face and sends motor neurons to muscles of face for voluntary and involuntary facial expression.
Supplied by the _____ artery

Answer 11

Yee
Anterior (ventral) surface consists of transverse bundles of fibres that become continuous laterally with middle cerebellar peduncle.

Part of brainstem between medulla oblongata
and midbrain.
• Base: contains corticospinal (descending motor) and corticopontine tracts.
• Tegmentum: contains cranial nerve nuclei, reticular nuclei, major ascending sensory pathways.
• Connected to cerebellum via middle cerebellar peduncle.

• Contains nuclei that mediate several auditory and balance functions.
• Input from vestibular system and communicates with cerebellum for balance.
• Sensory input from face and sends motor neurons to muscles of face for voluntary and involuntary facial expression.
Supplied by the basilar artery
Gives rise to CN 5, 6, 7, 8
Slides 21, 20, 19

Question 12

The medulla oblongata
Slide 22
• Pyramid extends through rostral 2/3 of _______.
• Pyramids contain ________ fibres primarily projecting from the primary motor cortex in the precentral gyrus.
• 90% of _______ fibres decussate (cross-over) in the caudal 1/3 of medulla oblongata to pass dorso-laterally to form the _____corticospinal tract.
• 10% of ______ fibres don’t decussate and form the _______corticospinal tract.

Answer 12

• Pyramid extends through rostral 2/3 of medulla oblongata.
• Pyramids contain corticospinal fibres primarily projecting from the primary motor cortex in the precentral gyrus.
• 90% of corticospinal fibres decussate (cross-over) in the caudal 1/3 of medulla oblongata to pass dorso-laterally to form the lateral corticospinal tract.
• 10% of corticospinal fibres don’t decussate and form the anterior corticospinal tract.