1. THE NERVOUS SYSTEM 4. Right vs. Left Hemisphere
Hemispheres are separate brains which “talk” to each other through
commissural fibers
a. Corpus callosum
b. Anterior and posterior commissures
Left brain (hemisphere)
- 90%
- language
- speaking
- writing
- personality: logical, realistic, analytical

3. THE NERVOUS SYSTEM Right brain (hemisphere) - 10% - tactile - visual
- auditory
- personality: intuitive, nonverbal, creative
Split brain
- congenital
- surgery—cure major motor seizures
If left hemisphere damaged in children, language center often can be
transferred to right hemisphere

9. THE NERVOUS SYSTEM H. Cranial Nerves
- How the brain communicates with the body without using the spinal cord
pairs
2. Differ from spinal nerves
- no plexuses
- no dorsal or ventral roots
3. Transmit afferent impulses
from special senses (equilibrium, vision, hearing, taste, and smell) and
proprioceptors
4. Transmit efferent impulses
to eyes, face, jaw, tongue, pharynx, larynx, and parasympathetic to
viscera

10. Plexus

11. Roots

12. THE NERVOUS SYSTEM 5. Order: Know order.
Know functions for I, II, V, VIII, X
On I olfactory
Occasion II optic
Our III oculomotor
Trusty IV trochlear
Truck V trigeminal
Acts VI abducens
Funny VII facial
Very VIII vestibulocochlear
Good IX glossopharyngeal
Vehicle X vagus
Any XI accessory
How XII hypoglossal

15. THE NERVOUS SYSTEM 6. Olfactory nerve (I) - smell
- terminates in olfactory bulb at base of frontal lobe
7. Optic nerve (II)
- vision
- afferent fibers terminate in primary visual area of occipital lobe
8. Trigeminal nerve (V)
- afferent impulses from scalp, mouth, cornea
- efferent impulses to muscles of mouth (chewing) &
soft palate (swallowing)

20. THE NERVOUS SYSTEM 9. Vestibulocochlear nerve (VIII)
- two separate nerves from inner ear
a. vestibular = semicircular canals
- Function: equilibrium
b. cochlear = cochlea
- Function: hearing
10. Vagus nerve (X)
- afferent = taste, abdominal & thoracic organs
- efferent = soft palate, pharynx, larynx, heart, and smooth muscles,
and glands

33. THE NERVOUS SYSTEM SENSORY AND MOTOR SYSTEMS
 Transfer of information between the brain and the body
 Occurs through the spinal cord
A. Sensory pathways
- Resulting in sensory perceptions
- All ascending
- Require 3 neurons
a. receptor medulla or spinal cord
(1st order neuron)
b. medulla or spinal cord thalamus
(2nd order neuron)
c. thalamus cerebral cortex
(3rd order neuron)

34. THE NERVOUS SYSTEM 1. Spinothalamic tracts - two types a. Anterior
- tickle, itch, localized touch, pressure
b. Lateral
- pain and temp
1) Adjacent sensory impulses
- Can block pain transmission
2) Enkephalins & endorphins
- brain’s own pain killers

40. THE NERVOUS SYSTEM B. Motor pathways
- Resulting in response at effector organ
- All descending
- Require 2 neurons
a. cerebral cortex spinal cord
(upper motor neuron)
b. spinal cord muscle
(lower motor neuron)
1. Corticospinal tracts (pyramidal)
- Impulses result in voluntary skeletal muscle movement
- 90% of fibers cross over at medulla

48. THE NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM (ANS)
Consists of motor neurons to smooth muscle, cardiac muscle, and glands.
- Depending on the type of receptor, the neurotransmitter released may either
excite or inhibit the effector.
Two neurons
1. Preganglionic
- cell body located in brain and spinal cord
2. Postganglionic
- completely outside of CNS

53. THE NERVOUS SYSTEM Comparison Chart Sympathetic Parasympathetic
CNS Division
(outlet)
adrenergic*
cholinergic*
thoracolumbar
craniosacral
2. General Response
fight or flight
rest & digest
3. Function
prepare for emergency
(stress)
recovery
4. Heart Rate
increase
decrease
5. Lung Bronchi
dilation
constriction
6. Adrenal Medulla
(Adrenalin)
secretion
7. Efferent
preganglionic
preganglionic
postganglionic
postganglionic

55. THE NERVOUS SYSTEM Adrenergic fibers - Release norepinephrine
- All sympathetic postganglionic neurons (axons)
- Long-lived impulse
Cholinergic fibers
- Release acetylcholine
- All parasympathetic postganglionic neurons (axons)
- All (sympathetic and parasympathetic) preganglionic neurons (axons)
- Short-lived impulse