Lecture 2

Question 1

What percentage of the intracranial vault does each component make? Brain, Blood and CSF

Answer 1

Brain: 80 - 85%
Blood: 5 - 10%
CSF: 10 - 15%

Question 2

What are the 2 main blood supplies to the brain?

Answer 2

Bilateral Carotid arteries

Bilateral Vertebral arteries

Question 3

Where does the left carotid artery arise from?

Answer 3

The aortic arch

Question 4

Where does the right carotid after arise from?

Answer 4

The Innominate Artery

Question 5

What do the carotid arteries bifurcate into?(2)

Answer 5

1. External carotid artery

2. Internal carotid artery

Question 6

Where does the internal carotid artery enter the skull?

Answer 6

At the base of the skull

Question 7

Where does the External carotid artery enter the skull?

Answer 7

It does NOT enter the skull, it remains superficial to the skull

Question 8

What 3 main areas do the internal carotid arteries supply?

Answer 8

1. Circle of Willis
2. Ophthalmic artery (supplies the eye)
3. Bifurcates into the anterior & middle cerebral arteries

Question 9

What arteries arise from the subclavian arteries and supply the Circle of Willis?

Answer 9

The vertebral arteries

Question 10

Where do the vertebral arteries arise from?

Answer 10

Subclavian arteries

Question 11

What part of the brain do the vertebral arteries supply?

Answer 11

Circle of Willis

Question 12

Describe how the venous blood of the brain drains?

Answer 12

Drains into the VENOUS SINUSES which lie between the layers of the DURA MATER & drain into the INTERNAL JUGULAR VEIN

Question 13

Describe 4 important aspects of venous sinuses of the brain:

Answer 13

1. Valveless
2. Blood can flow back & forth
3. Negative pressure (air embolism)
4. Little influence by autonomic system

Question 14

Describe why there brain is subject to air embolisms?

Answer 14

Venous sinuses have negative pressure, which can lead to air embolism

Question 15

What do the meninges cover (2) and what do the consist of (3)?

Answer 15

• Covers BRAIN & SPINAL CORD

- Consists of DURA MATER, ARACHNOID MEMBRANE, PIA MATER

Question 16

The ____A_____ is anchored to the brain by ____B_____, which forms the _____C_____.

Answer 16

A. Pia mater
B. Astrocytes
C. Blood-brain barrier

Question 17

The Blood-brain barrier allows passage/transport of: (4 - with examples)

Answer 17

1. Small molecules (H2O, O2, CO2)
2. Lipophilic molecules (EtOH, heroin)
3. Passive transport of glucose
4. Active transport of amino acids/NT precursors

Question 18

The blood-brain barrier PREVENTS the passage of: (2)

Answer 18

1. Large molecules (dopamine)

2. Charge (ionized) molecules

Question 19

What does the dura mater consist of? What is between these layers?
What is the function of the dura mater?

Answer 19

• Consists of outer & inner layer
• Dural Sinus between the layers
• Drains the CSF

Question 20

List the layers from the brain to the skull:

Answer 20

1. Brain
2. Pia mater
3. Subarachnoid space
4. Arachnoid membrane
5. Dura mater
6. Skull

Question 21

Where is an epidural hematoma located? What is usually the artery of origin?

Answer 21

• Bleeding between the skull & dura mater

- Usually originating in meningeal arteries

Question 22

Where is a subdural hematoma located? What is usually the artery of origin?

Answer 22

• Bleeding between the dura & arachnoid mater

- Usually originating from tears in BRIDGING VEINS

Question 23

Where is a subarachnoid hematoma located? What is usually the cause?

Answer 23

• Bleeding between the arachnoid membrane & Pia mater

- Usually from a ruptured cerebral aneurysm

Question 24

Is a subarachnoid hemorrhage the most common cause of stroke?

Answer 24

No, it is less common. It is a neurological emergency

Question 25

What produces CSF and where?

Answer 25

- Produced by the Choroid Plexus | - Produced in the cerebral ventricles

Question 26

What does CSF surround and what is it’s 3 main functions?

Answer 26

- Surrounds the brain & spinal cord 1. Cushions 2. Supports 3. Facilitates transport of nutrients

Question 27

What is roughly the total volume of CSF? How much CSF is produced daily?

Answer 27

- Roughly 150 mL | - Roughly 500 mL produced daily

Question 28

What is Cranial Nerve VII?

Answer 28

Facial nerve

Question 29

What 2 important muscles does CN VII innervate?

Answer 29

1. Muscles of facial expression (motor) | 2. Orbicularis Oculi

Question 30

When is CN VII frequently monitored? Examples?

Answer 30

- During surgery around the face | - Parotidectomy, acoustic neuroma, cochlear implant

Question 31

What is CN IX?

Answer 31

Glossopharyngeal nerve

Question 32

What 3 important structures does CN IX provide SENSORY innervation to?

Answer 32

1. Baroreceptors of carotid sinus 2. Chemoreceptors of carotid body 3. Posterior oral mucosa (gag reflex)

Question 33

What important structures does CN IX provide MOTOR innervation to?

Answer 33

The pharynx (swallowing)

Question 34

What can likely happen during CEA?

Answer 34

CN IX can be stimulated via the baroreceptors of the carotid sinus —> leading to bradycardia and hypotension

Question 35

What is CN X? What 3 forms of innervation does it provide?

Answer 35

- Vagus nerve 1. Sensory 2. Motor 3. Parasympathetic

Question 36

Which parts of the pharynx does CN X supply? (3)

Answer 36

1. Pharyngeal muscles 2. Mucous membranes 3. Palate

Question 37

Which part of the Larynx does CN X supply? (2)

Answer 37

1. Superior laryngeal nerve | 2. Recurrent laryngeal nerve

Question 38

Which nerve innervates the cricothyroid muscle? What is the function of the cricothyroid muscle?

Answer 38

- The external branch of the SLN | - Tenses and ADDUCTS the vocal cords

Question 39

What happens with injury to the external SLN?

Answer 39

Changes in voice quality, but generally NOT dangerous

Question 40

What does the RLN innervate?

Answer 40

All of the INTRINSIC muscles of the larynx EXCEPT for the cricothyroid muscle

Question 41

A unilateral RLN injury produces ____A____ vocal cord paralysis, affecting the _____B_____ muscle. Resulting in a ____C____ position of the affected cord, which causes postoperative _____D_____

Answer 41

A. Abductor vocal cord paralysis B. Posterior cricoarytenoid muscle C. Paramedian position D. hoarseness

Question 42

Bilateral RLN injury results in __A__ paralysis, which can manifest as ___B___ vs. ___C___. Symptoms include ___D___ and often requires ____E____ or ___F___.

Answer 42

``` A. Bilateral vocal cord paralysis B. Partial airway obstruction C. Complete airway obstruction D. Respiratory distress with stridor E. Emergent reintubation F. Tracheostomy ```

Question 43

Which systems does CN X provide parasympathetic innervation to? (3)

Answer 43

1. Heart 2. Lungs 3. GI system

Question 44

Which part of the heart does CN X provide parasympathetic innervation to?(2) What does this stimulation result in?

Answer 44

- Innervation to sino-atrial and atrio-ventricular nodes of the heart - Stimulation causes reduction in resting heart rate, & are constantly active

Question 45

What aspect does of the lungs does CN X provide parasympathetic innervation to? What is the result of stimulation? (2)

Answer 45

- parasympathetic to the pulmonary plexus | - Stimulation causes VASODILATION and BRONCHOCONSTRICTION

Question 46

What aspect of the GI system does CN X provide parasympathetic innervation to? What does stimulation result in?

Answer 46

- Innervates the majority of ABDOMINAL ORGANS | - Stimulates SMOOTH MUSCLE CONTRACTION & GLANDULAR SECRETIONS in these organs

Question 47

What can vagal stimulation during GI surgery & endoscopy lead to?

Answer 47

Significant bradycardia and even asystole

Question 48

What is CN I and it’s function?

Answer 48

- Olfactory | - Smell

Question 49

What is CN II and it’s function?

Answer 49

- Optic | - Sight

Question 50

What is CN III and it’s function?

Answer 50

- Oculomotor | - Eyelid & eyeball movement; pupil and lens adjustment

Question 51

What is CN IV and it’s function?

Answer 51

- Trochlear | - Moves eyeballs

Question 52

What is CN V and it’s function?

Answer 52

- Trigeminal | - Facial muscles (chewing) and facial sensation

Question 53

What is CN VI and it’s function?

Answer 53

- Abducens | - Moves eyeballs

Question 54

What is CN VII and it’s function?

Answer 54

- Facial | - Taste, tears, saliva, facial expressions

Question 55

What is CN VIII and it’s function?

Answer 55

- Vestibulocochlear | - auditory

Question 56

What is CN IX and it’s function?

Answer 56

- Glossopharyngeal | - Swallowing, saliva, taste

Question 57

What is CN X and it’s function?

Answer 57

- Vagus | - Control of PNS (heart, lungs, GI)

Question 58

What is CN XI and it’s function?

Answer 58

- Accessory | - Movement of Head & shoulder; swallowing

Question 59

What is CN XII and it’s function?

Answer 59

- Hypoglossal | - Tongue muscles - speech and swallowing