TCRN – MAXILLOFACIAL UPDATED
COMPREHENSIVE STUDY GUIDE 2026
◉ The brain makes up approximately _____% of the volume of the
skull and is _____% water.
Answer: 80%
75%
◉ CSF makes up about _____% of the volume of the skull.
Answer: 10%
◉ There is approximately _____ mL of CSF.
Answer: 125-150 mL
◉ Blood makes up about _____% of the volume of the skull and _____%
of the blood is venous.
Answer: 10%
80%
◉ The pressure of water, CSF and blood against the skull is known as
_____.
Answer: ICP - Intracranial pressure
,◉ What are the normal ICPs for children and adults?
Answer: Child - 0-5 mmHg
Adult - 5-12 mmHg
◉ ICP pressures above _____ mmHg in any age group is considered
elevated.
Answer: 20 mmHg
◉ ICP pressures above 20 mmHg do what?
Answer: Compromise blood flow into the skull and contribute to
cerebral hypoxia and hypoglycemia.
◉ What can happen if ICP pressures climb too high?
Answer: The brain may be forced out of the skull through any
opening (such as skull fractures, tentorial plate or foramen
magnum).
◉ ICP above _____ mmHg is severe and life-threatening.
Answer: 40 mmHg
◉ ICP between _____ and _____ mmHg is termed "moderate
intracranial hypertension".
,Answer: 20 and 40 mmHg
◉ ICP above 20 mmHg is abnormally high and is known as _____.
Answer: Early increased ICP
◉ What should resting ICP be?
Answer: Less than 10 mmHg
◉ When ICP increases, pressure is exerted downwards on brain
tissue, affecting the cerebral cortices _____ and _____.
Answer: Reticular Activating System (RAS) and Cranial Nerves
◉ List 6 things caused by pressure on the RAS (Reticular Activating
System).
Answer: 1. Progressive restlessness
2. Confusion
3. Disorientation
4. Lethargy or combativeness
5. Changes in speech
6. Loss of judgement
◉ List 4 motor functions caused by increased ICP.
, Answer: 1. Monoplegia
2. Hemiplegia
3. Over-pronation or supination of the wrists
4. Pronator drift
◉ List 5 eye changes caused by increased ICP.
Answer: Diplopia
Blurred Vision
Visual field defects (loss of sight in part of one visual field)
Conjugate deviation of eyes or gaze palsies
Oval pupils with hippus
◉ Increased ICP causes _____ losses.
Answer: Sensory
◉ List 3 things caused by pressure on the hypothalamus.
Answer: Nuchal rigidity
Temperature changes
Vomiting (usually without nausea)
◉ Describe how to test for pronator drift.
COMPREHENSIVE STUDY GUIDE 2026
◉ The brain makes up approximately _____% of the volume of the
skull and is _____% water.
Answer: 80%
75%
◉ CSF makes up about _____% of the volume of the skull.
Answer: 10%
◉ There is approximately _____ mL of CSF.
Answer: 125-150 mL
◉ Blood makes up about _____% of the volume of the skull and _____%
of the blood is venous.
Answer: 10%
80%
◉ The pressure of water, CSF and blood against the skull is known as
_____.
Answer: ICP - Intracranial pressure
,◉ What are the normal ICPs for children and adults?
Answer: Child - 0-5 mmHg
Adult - 5-12 mmHg
◉ ICP pressures above _____ mmHg in any age group is considered
elevated.
Answer: 20 mmHg
◉ ICP pressures above 20 mmHg do what?
Answer: Compromise blood flow into the skull and contribute to
cerebral hypoxia and hypoglycemia.
◉ What can happen if ICP pressures climb too high?
Answer: The brain may be forced out of the skull through any
opening (such as skull fractures, tentorial plate or foramen
magnum).
◉ ICP above _____ mmHg is severe and life-threatening.
Answer: 40 mmHg
◉ ICP between _____ and _____ mmHg is termed "moderate
intracranial hypertension".
,Answer: 20 and 40 mmHg
◉ ICP above 20 mmHg is abnormally high and is known as _____.
Answer: Early increased ICP
◉ What should resting ICP be?
Answer: Less than 10 mmHg
◉ When ICP increases, pressure is exerted downwards on brain
tissue, affecting the cerebral cortices _____ and _____.
Answer: Reticular Activating System (RAS) and Cranial Nerves
◉ List 6 things caused by pressure on the RAS (Reticular Activating
System).
Answer: 1. Progressive restlessness
2. Confusion
3. Disorientation
4. Lethargy or combativeness
5. Changes in speech
6. Loss of judgement
◉ List 4 motor functions caused by increased ICP.
, Answer: 1. Monoplegia
2. Hemiplegia
3. Over-pronation or supination of the wrists
4. Pronator drift
◉ List 5 eye changes caused by increased ICP.
Answer: Diplopia
Blurred Vision
Visual field defects (loss of sight in part of one visual field)
Conjugate deviation of eyes or gaze palsies
Oval pupils with hippus
◉ Increased ICP causes _____ losses.
Answer: Sensory
◉ List 3 things caused by pressure on the hypothalamus.
Answer: Nuchal rigidity
Temperature changes
Vomiting (usually without nausea)
◉ Describe how to test for pronator drift.
