Chapter 14 - Brain & Cranial Nerves

Question 1

4 Principle Parts of the Brain

Answer 1

1. Brain Stem
2. Cerebellum
3. Diencephalon
4. Cerebrum

Question 2

Brain Stem (3 Parts)

Answer 2

1. Medulla Oblongata
2. Pons
3. Midbrain

Question 3

Medulla Oblongata

Answer 3

• Connects brain to spinal cord
• Relays sensory & motor info
• Autonomic regulation

Question 4

Pons

Answer 4

• Connects cerebellum to brain stem

- Involved in some somatic & visceral motor control

Question 5

Midbrain

Answer 5

• Processes visual & auditory info
• Head movements respond to visual & auditory stimuli
• Generates some voluntary somatic motor responses

Question 6

Cerebellum

Answer 6

Adjusts voluntary & involuntary motor activities based on sensory data & memory

Question 7

Diencephalon (3 Parts)

Answer 7

1. Hypothalamus
2. Thalamus
3. Epithalamus

Question 8

Hypothalamus

Answer 8

Contains centers involved w/ emotions, autonomic function & hormone production

Question 9

Thalamus

Answer 9

• Relay center for sensory data (3rd order relay neurons project to the somatosensory cortex or other sensory areas of the cortex)
• Transmits motor info from the cerebellum & basal nuclei to the primary motor cortex

Question 10

Epithalamus

Answer 10

• Contains the pineal gland

- Involved in emotional responses to olfactory stimuli

Question 11

Cerebrum

Answer 11

• Supported by the diencephalon
• Origin of thought, memory & voluntary motor functions
• Divided into right & left hemispheres

Question 12

3 Protections of the CNS

Answer 12

1. Bone
2. Cerebrospinal Fluid
3. Cranial & Spinal Meninges

Question 13

3 Cranial & Spinal Meninges

Answer 13

1. Dura Mater
2. Arachnoid Mater
3. Pia Mater

Question 14

Dura Mater

Answer 14

• Outermost membrane; one layer around spinal cord, periosteal & meningeal layers around brain
• Made of dense irregular connective tissue

Question 15

Arachnoid Mater

Answer 15

• Web-like middle membrane
• Thin strands attach to the pia mater
• Subarachnoid space contains cerebrospinal fluid

Question 16

Pia Mater

Answer 16

-Innermost membrane

Question 17

Dural Venous Sinuses

Answer 17

Venous spaces that collect venous blood & CSF

Question 18

3 Dural Membrane Extensions

Answer 18

1. Falx Cerebri: Runs down longitudinal fissure, anchors to ethmoid bone
2. Falx Cerebelli: Insulates the two halves of the cerebellum
3. Tentorium Cerebelli: Seperates cerebrum from cerebellum

Question 19

2 Head Injuries for Producing Bleeding

Answer 19

1. Epidural Hematoma: Blood between dura mater & cranial bone
2. Subdural Hematoma: Blood between dura mater & arachnoid mater

Question 20

4 Brain Ventricles for CSF Circulation

Answer 20

• 2 Lateral Ventricles: Each located in a brain hemisphere, separated by septum pellucidum
• 3rd Ventricle: Located between the 2 halves of the thalamus
• 4th Ventricle: Located between the brainstem & cerebellum

Question 21

Inter-ventricular Foramina

Answer 21

• 2 in total

- Act as the aqueduct of the midbrain (AKA “Aqueduct of Sylvius”)

Question 22

Cerebrospinal Fluid (3 Main Functions)

Answer 22

1. Mechanical Protection: Protective cushion for CNS
2. Chemical Protection: Supplies neurons & neuroglia w/ O2 & various nutrients (e.g, Na+, K+, Cl-), also maintains optimal environment
3. Circulatory System: Returns wastes to blood via dural venous sinuses; links brain & spinal cord to bloodstream

Question 23

3 Spaces for CSF Containment

Answer 23

1. Subarachnoid Space
2. Central Canal of Spinal Cord
3. Brain Ventricles & Interconnecting Channels

Question 24

Choroid Plexuses

Answer 24

Leaky capillaries covered by ependymal cells

*CSF = blood water “strained” through ependymal cells

Question 25

Blood-CSF Barrier

Answer 25

- Filters approx. 480 mL of CSF/day | - Renews CSF 3-6 times daily

Question 26

4 Steps of CSF Flow

Answer 26

1. CSF leaves 4th ventricle through 2 lateral apertures & 1 median aperture 2. Flows into subarachnoid space 3. Flows into central canal of spinal cord 4. Enters dural venous sinuses via arachnoid villi * CSF Removal must = CSF Production

Question 27

Hydrocephalus

Answer 27

- Abnormal accumulation of CSF within the brain - Blockage of CSF flow in infants = brain & head may enlarge due to CSF accumulation -> brain damage - CSF accumulation in older child/adult = brain cannot enlarge -> rapid ischemic brain damage

Question 28

Arterial Blood Supply to Brain (2 Arteries)

Answer 28

1. Internal Carotid Arteries | 2. Vertebral Arteries

Question 29

Venous Drainage of Brain (1 Vein)

Answer 29

1. Internal Jugular Veins

Question 30

Hypoglycemia & the Brain

Answer 30

Severe hypoglycemia can cause: - Dizzines & confusion - Unconsciousness - Convulsive seizures - Possible coma & death

Question 31

Ischemia & The Brain

Answer 31

- 1 to 2 mins. of low O2 leads to unconsciousness | - 4 mins. of ischemia leads to irreversible brain damage

Question 32

Circle of WIllis (AKA "Cerebral Arterial Circle")

Answer 32

- A ring of arteries supplying the brain & forming an anastomosis, surrounding the infundibulum - Union of the anterior cerebral arteries & posterior cerebral arteries - Anterior communicating artery & 2 posterior communicating arteries complete the Circle