Chapter 20: Brainstem region

Question 1

cerebellar peduncles

Answer 1

• Inferior peduncle- what I am really doing- afferent from spinocerebellar tracts
• Middle peduncle- what I meant to do
• Superior peduncle- Change it if I need to

Question 2

Base of the brainstem

Answer 2

the most anterior piece (primarily has motor tracts, in particular the corticospinal tract)

Question 3

Tegmentum

Answer 3

The body of the brainstem- located more posterior- tracts of sensory, spinothalamic tract, spinocerebellar tract (unconscious touch and proprioception) (touch and pain have come back together in the brainstem so they go back to the same spot)

-Medial lemniscus (conscious touch and proprioception)

Question 4

Anatomy of brainstem: Tectum

Answer 4

tectum is the roof of the ventricle- four bumps are called the colliculi/colliculus- involved in the response that turns the head to a visual stimulus. Orient vision to stimulus without even thinking. Turn head in response to visual information. Involuntary (superior colliculi).

-cerebral aqueduct would be and membrane of cerebellum creates the fourth ventricle.

Question 5

Reticular formation

Answer 5

Loose cluster of cells up and down the middle of the brainstem- has 4 major outputs we are concerned about

*in a coma, no sleep/wake cycle, the reticular formation is asleep/not active

Question 6

4 outputs of reticular formation

Answer 6

1) output up to the head, regulates consciousness and sleep/wake cycle and it regulates our level of “arousal” within the central nervous system.

output to all 3 horns:
2) Dorsal horn- neurons from reticular formation come down to the dorsal horn and influence the synapse of the pain pathway (level 3 that project down to level 2, descending pain control pathway, to close the gate and not let pain signals come through the synapse).

3) Lateral horn- From brainstem down to the lateral horn- autonomic control- control from the pons and the medulla down to the spinal cord. They influence the peripheral autonomic neurons. For the purpose of autonomic or visceral control.
4) Anterior horn- Reticular formation broad output to the ventral horn- cell bodies of LMN- it slightly depolarizes all of the lower motor neurons and lowers their threshold so that when we decide to either fight or flee we can have an outcome/easier to activate what we want when we want it. Increase excitability of LMNs.

Question 7

Cerebellum

Answer 7

• coordinates movement
• helps plan movement
• helps shift attention from one point of focus to another point of focus.

Question 8

Arterial supply

Answer 8

Vertebrobasilar circulation:
Vertebral arteries turns in to the basilar artery that splits into two posterior cerebral arteries.
(posterior inferior cerebellar artery comes out of vertebral artery), anterior and superior cerebellar arteries come out of the basilar artery.

Cranial nerves to what blood supply.

• Vertebral- 9, 10, 11, 12
• Basilar- 5, 6, 7, 8
• Posterior cerebral- 3, 4

Question 9

Disorders in brainstem region: vertical tract signs

Answer 9

-Vertical tracts for body pass through brainstem
-Damage to these vertical tracts in the brainstem will produce contralateral signs and symptoms in the body.
(motor and sensory on same side, pain on opposite side because it crosses.

Big 3

• Corticospinal-coming down (caudal medulla)- damage at any point of brainstem will be on the opposite side of the damage.
• Dorsal column medial lemniscus- going up and crosses midline at caudal medulla (damage on the right side of the brainstem has signs and symptoms on the same side of the body)
• Spinothalamic- going up (cut at any point in the brainstem- lose pain and temp on the other side of the body- contralateral).

*peripheral nerves have Signs and symptoms on the same side as damage. (CN are segments of the brainstem).

Question 10

damage to the brainstem

Answer 10

Damage to the body (corticospinal tract and medial lemniscus) is opposite, to the face (CN) it is the same side of damage to one side of the brainstem.

*brainstem is the only location we can get face the same side and body the opposite side.

Question 11

Disorders in the brainstem: damage sides

Answer 11

• Vertical tracts (for body)- contralateral
• Cranial nerve- ipsilateral
• Cerebellum- ipsilateral (always ipsilateral to the damage)
• Autonomic- always ipsilateral.

Question 12

Disorders of vital function: reticular formation

Answer 12

• The reticular formation has autonomic control, if brainstem gets damaged it can influence autonomic control.
• Heart, lungs, blood pressure.

Question 13

4 D’s of brainstem dysfunction

Answer 13

Dysphagia- (CN IX and X)

Dysarthria- (CN V, VII, X, XII) trouble with mechanical production of speech

Diplopia- (CN III, IV, VI)

Dysmetria- (cerebellum and spinocerebellar)

*If you see these collectively you can suspect the brainstem has been damaged as well as some tracts that run through the cerebellum.

Question 14

Brain tumors

Answer 14

Will likely cause increased intracranial pressure
-possible signs/symptoms of ICP:
-Headache
-Nausea
Vomiting
-Cranial Nerve disorders
-Hydrocephalus

*can affect consciousness and sleep wake cycle.