4.4

Question 1

Reticular formation

Answer 1

Cells of the reticular formation are not collected into typical nuclei.
Extends throughout the brainstem
RF send signals to the entire cerebrum

Question 2

Reticular formation: core of the brainstem

Answer 2

Cranially merges with nuclei of the thalamus.
Caudally extends through the brainstem.
Spinal cord analogue is the intermediate grey matter.

Question 3

Reticular formation functions through

Answer 3

• skeletal muscle
• ANS
• endocrine system
• biological rhythm

Question 4

Function of reticular formation

Answer 4

Control of consciousness
Somatic and visceral sensation
Regulation of the respiratory and cardiovascular system
control of muscle tone
Posture maintenance
Movement

Question 5

Afferents of reticular formation

Answer 5

Sensory
Moto
ANS
Hypthalamus/limbic

Question 6

Efferents of reticular formation

Answer 6

Every level of CNS

Question 7

How does the reticular formation control motor function

Answer 7

Corticoreticular fibers synapse with motor interneurons
- function in locomotion and postural control
Control muscle tone and reflex activity
- reflex inhibition
Maintains horizontal gaze steady when the head moves.

Question 8

How does the reticular formation control pain sensation

Answer 8

Pain pathway from the body = ALS (indirect and direct)
Pain pathway from the head = trigeminothalamic pathway
- collateral branches extend to reticular formation
- RF sends signals to the:
* hypothalamus and limbic systems -> emotional response
* reticulobulbar and reticulospinal tracts -> serotonergic inhibition of pain

Question 9

How does the reticular formation control the ANS

Answer 9

RF receives afferents from
- cerebral cortex
- hypothalamus
- limbic system
- ascending sensory pathways
The reticulobulbar tract and reticulospinal tracts carry signals to the ANS center of the brainstem.

Question 10

Arousal and consiousness

Answer 10

Sensory stimuli -> behavioral arousal
- attention is focused
- general alertness increases
Action of the RF = arousal
Consciousness requires the cerebral cortex and RF

Question 11

Ascending reticular activating system

Answer 11

Ascending pathways (including ALS)
1. send collateral branches to the RF
2. RF to the thalamus and hypothalamus
3. thalamus to the cerebral cortex
- this maintains the sleep-wake cycle

Question 12

Consciousness

Answer 12

Loss of consciousness can result from multiple injuries
- metabolic derangement (diabetes, hypoxia)
- drugs
- encephalopathies
- trauma
- vascular accidents

Question 13

Confusion

Answer 13

Impairments speed and clarity, associated with inattentiveness and disorientation

Question 14

Drowsiness

Answer 14

inability to remain awake without external stimulation

Question 15

Stupor

Answer 15

only vigorous external stimulation van arouse the patient; once aroused, responses remain markedly impaired

Question 16

Coma

Answer 16

deep sleep-like state; patient cannot be aroused even with vigorous or repeated external stimulation

Question 17

Purpose of glasgow coma scale

Answer 17

Communicate severity of brain damage in the moment
Assess likelihood of recovery

Question 18

Increased intracranial pressure

Answer 18

Trauma –> swelling –> increased ICP
The only outlet for the cranium is the foramen magnum –> pressure on the brainstem
* medulla –> damage to respiratory centers –> apnea
* midbrain –> RF damage and hypersomnia –> coma

Question 19

SCI T6 or above

Answer 19

Descending reticulospinal tracts innervate sympathetic signals to the ANS organs of the thorax

Early –> reduced SNS activity
Late –> reflex SNS hyperactivity

Question 20

Decorticate

Answer 20

Injury at the level of the cerebral cortex or below
- flex arms

Question 21

Decerebrate

Answer 21

Injury at the level of the midbrain of below
- extension

Question 22

Minimally conscious state

Answer 22

Patient is capable of some rudimentary behavior such as following a simple command
Always in an inconsistent way

Question 23

Locked in syndrome

Answer 23

Only an inability of the patient to respond adequately with motor activity and speech

Question 24

Akinetic mutism

Answer 24

Patient is motionless and mute

Question 25

Catatonia

Answer 25

Individual appears unresponsive
Most often seen with psychosis