Nervous System

Question 0

Rhombencephalon

Answer 0

Most primitive parts of brain
Myelencephalon:
-medulla > basic autonomic function (❤️, breathing)
-switching point for white & gray matter
Metencephalon:
-cerebellum
•coordination & equilibrium(balance) >motor functions
•body & vermis (worm), very folded
•large in fish, birds, mammals
•arbor vitae: white matter on inside of cerebellum

Question 1

Embryology of brain

Answer 1

Prosencephalon = forebrain
-telencephalon and diencephalon 
Mesencephalon = midbrain
-no formal subdivision 
Rhombencephalon
-metencephalon and mesencephalon

Question 2

Mesencephalon

Answer 2

Mesen = middle
Pons = floor of midbrain
-autonomic relay point
Optic lines transmit to superior colliculus
-fish & amphibs start to enlarge
Auditory info transmits to inferior colliculus (below)
-amniotes start to enlarge 
*tectum = roof of midbrain

Question 3

Prosencephalon : diencephalon

Answer 3

1) epithalamus
-pineal gland
•median (parietal) eye
-choroid plexus = secretes CSF in any ventricle
2) thalamus
-relay center to cerebrum
-interpret pain, temp.
-sleep, wakefulness
3) hypothalamus
-homeostasis center > regulation
-optic chiasma ventral
-pituitary ventral (landmark)

Question 4

Prosencephalon : telencephalon

Answer 4

Cerebral hemispheres
-increase in size (amniotes ~20x larger)
-duplication of centers that process stimuli 
 •cerebral cortex (sensory/motor)
 •hippocampus (recent memory)
 •basal ganglia (motor/decision making)
-olfactory bulbs and lobes
-corpus callosum or commissure
 •decussating (crossing) nerve tracts

Question 5

All brain regions

Answer 5

Internal hollow ventricles
Cerebrospinal fluid (nutrients, salt + H2O balance) secreted by choroid plexus
Hydrocephalus ("water on the brain") occurs when intraventricular foramina are blocked -> CSF can't drain

Question 6

Neuron

Answer 6

• cell body
• dendrites
• axon

Question 7

Synapse

Answer 7

Gap between neurons

Question 8

Nerve

Answer 8

Axons bundled together in connective tissue sheath (epineurium)

Question 9

Neuroglia

Answer 9

Half of the mass of brain and spinal cord are neurons

Other half are Neuroglia (supporting cells)

Question 10

Functions of Neuroglia cells

Answer 10

• secrete myelin
• remove debris

In CNS: oligodendroglial
In PNS: Schwann cells

*nodes of ranvier = spaces between myelin

Question 11

Sensory nerves

Answer 11

Cell bodies in PNS (usually in ganglia)

Receives messages from PNS (external or internal stimuli)

Question 12

Motor nerve

Answer 12

Cell bodies in CNS

Sends out messages to muscles and glands (Effectors)

Question 13

Mixed nerve

Answer 13

Contain both sensory and motor nerves

Most vertebrate nerves are mixed

Question 14

Spinal cord

Answer 14

Shorter than the vertebral column (gap used for spinal taps, epidural)
Swellings in cervical & lumbar regions

Gray matter 
-inside of spinal cord
-cytoplasm of cell bodies
White matter
-outside of spinal cord
-axons (myelin sheath)

Question 15

Spinal cord nerves

Answer 15

Spinal nerves are split into branches near spinal cord

Question 16

Dorsal root of spinal nerve

Answer 16

Enters spinal cord does ally
Carries sensory fibers
Sensory ganglion just outside the spinal cord

Question 17

Ventral root of spinal nerve

Answer 17

Leaves the spinal cord ventrally (inside)

Carries motor fibers

Question 18

Interneurons IN spinal cord

Answer 18

Help coordinate between sensory and motor fibers

Relay point

Question 19

Reflex arc

Answer 19

1. Sensory receptor
2. Sensory neuron
3. Into dorsal root of spinal cord
4. Interneuron in spinal cord
5. Out ventral root of spinal cord
6. Motor neuron
7. To muscle

Question 20

Autonomic nervous system

Answer 20

Subdivision of PNS
Involuntary nervous system
Enervates viscera
Thoracic and lumbar regions -> sympathetic system
-fight or flight (rev up ❤️, decrease digestion)
Craniosacral system -> parasympathetic
-rest and repose

Question 21

Cranial nerves

Answer 21

• Amniotes (reptiles, birds, mammals) and sarcopterygii (lung fish, lobe-finned fish) have 12 cranial nerves
• Amphibs and fish have 10 cranial nerves
• Other 2 nerves were originally spinal nerves that became incorporated into the brain case

OOOTTAFAGVAH (names I-XII)
SSMMBMBSBBMM (sensory-motor-both)

Question 22

Nerve I

Answer 22

Olfactory
Sensory
-smell
-some tetrapods have separate vomeronasal nerves

Question 23

Nerve II

Answer 23

Opic
Sensory
-vision
-nerves cross in optic chiasma

Question 24

Nerve III

Answer 24

Oculomotor
Motor
-moves eyes

Question 25

Nerve IV

Answer 25

Trochlear
Motor
-moves eyes

Question 26

Nerve V

Answer 26

Trigeminal
Both
-face and jaw innervation

Question 27

Nerve VI

Answer 27

Abducens
Motor
-moves eyes

Question 28

Nerve VII

Answer 28

Facial
Both
-taste, facial expression, saliva, tears

Question 29

Nerve VIII

Answer 29

Auditory
Sensory
-also called vestibulocochlear
-hearing, equilibrium

Question 30

Nerve IX

Answer 30

Glossopharyngeal
Both
-back of tongue, taste, senses carotid blood pressure, swallowing

Question 31

Nerve X

Answer 31

Vagus
Both
-senses aortic blood pressure, senses taste, slows heart, stimulates digestion

Question 32

Nerve XI

Answer 32

Accessory
Motor
-swallowing muscles
-also called “spinal accessory”

Question 33

Nerve XII

Answer 33

Hypoglossal
Motor
-hyoid, tongue, speaking