Ch. 15: Brain Stem

Question 1

4 D’s of Brainstem dysfunction

Answer 1

• Dysphagia (IX, X)
• Dysmetria (spinocerebellum)
• Dysarthria (V, VII, X, XII)
• Diplopia (III, IV, VI)

Question 2

Medulla

Answer 2

External

• Anterior: Pyramids
• CN Roots IX, X, XI, XII
• Dorsal: sensory tracts

Internal

• Ant: corticospinal tracts, medial lemniscus
• Post: spinothalamic tract, trigeminothalamic tract, reticular formation, autonomic control nuclei, CN nuclei IX, X, XII

Question 3

Pons

Answer 3

External

• ventral: bulge, CN Roots (V, VI, VII, VIII)
• Dorsal: cerebellar peduncles

Internal

• Basilar: corticospinal pontine nuclei, corticobrainstem tract
• Tegmentum: med lemniscus, spinothalamic tracts, trigeminothalamic tracts, autonomica control nuclei, CN nuclei (V, VI, VII, VIII)

Question 4

Midbrain

Answer 4

External

• ventral: cerebral peduncles, CN root III
• Dorsal: sup/inf colliculi, CN root IV

Internal

• basilar: cerebral peduncles, substantia nigra
• Tegmentum: red nucleus, pedunculopontine nucleus, occulomotor complex (III, IV), periaqueductal grey
• Tectum: sup/inf colliculi

Question 5

Brainstem Divisions

Answer 5

• Medulla, Pons, Midbrain

- Base, Tegmentum (sensory), Tectum (colliculi)

Question 6

Reticular formation

Answer 6

• cluster of cells down core of midbrain
• integrate sensory and cortical info
• regulate somatic motor, autonomic function and consciousness
• modify nociception info (level III)
• output: everywhere

Question 7

Reticular formation: role in sensation and cortical integration

Answer 7

• strong connection to basal ganglia
• help motor planning
• produce antidepressant NT (Serotonin)
• regulate mood

Question 8

Reticular formation: role in pain modulation

Answer 8

• level III pain control via connections to ventral horn

- (presynaptic inhibition from above, turned on by level IV)

Question 9

reticula formation: role in somatic, autonomic, and consciousness reg

Answer 9

• Motor: nonspecific activating tracts–>general excitability
• Autonom: part of pons/medulla involved in autonomic control
• consciousness: regulate consciousness and arousal and sleep wake cycles

Question 10

Reticular Formation output

Answer 10

• everywhere

- cortex, subcortex, b stem, s cord, cerebellum

Question 11

Cerebellum

Answer 11

• coordinate movement (gross/fine)
• motor planning with BG (direction, timing, rhythm, speed)
• cognitive function: mediate shift in attention

Question 12

Segmental S/Sx

Answer 12

• CN damage
• LMN S/Sx
• Ipsilateral

Question 13

Most 1-sided brainstem damage–>

Answer 13

• CN S/Sx ipsilateral (LMN)

- Contralat body (UMN)

Question 14

Disorders of Brainstem from:

Answer 14

• ischemia (stroke)
• compression (tumor/CSF)
• segmental damage=CN damage

Question 15

Vertical Tract Damage

Answer 15

• contralateral S/Sx (UMN)

- damage to DC/ML, Spinothalamic, corticospinal tracts

Question 16

One-sided brain stem damage–>

Answer 16

• Corticospinal tract: contralat paralysis limbs/trunk (UMN)
• ML: loss contralat sensatoin
• CN: ipsilateral (LMN)

Question 17

Disorders of Vital Function

Answer 17

• damage to cardiovascular and respiratory control centers in medulla
• one side damage to pons/medulla=ipsilateral S/Sx

Ex. Horner’s Syndrome