1. Spinal Nerves, Dermatomes, and Cranial Nerves
Handout for Cranial Nerves

2. Spinal Nerves 1. 31 pairs 2. spinal canal emergence 3. distribution
a. 8 cervical
b. 12 thoracic
c. 5 lumbar
d. 5 sacral
e. 1 coccygeal

3. Cervical Plexus
Brachial plexus

4. Lumbar Plexus
Sacral and Coccygeal
Plexus

5. Typical Spinal Nerve 1. mixed nerve 2. connective tissues
a. endoneurium
b. perineurium
-- fascicles
c. epineurium

6. Dermatomes

7. Cranial Nerves
pairs
2. motor components -- arise from brain stem gray matter
3. sensory components -- arise in ganglia outside brain

8. Cranial Nerves

9. Cranial Nerves Names name mnemonic I. olfactory On II. optic Old
III. oculomotor Olympus'
IV. trochlear Towering
V. trigeminal Top
VI. abducens A
VII. facial Finn
VIII. auditory And
IX. glossopharyngeal German
X. vagus Viewed
XI. accessory A
XII. hypoglossal Hop

10. Cranial Nerve Functions
name function mnemonic
I. olfactory sensory Some
II. optic sensory Say
III. oculomotor motor Marry
IV. trochlear motor Money
V. trigeminal both But
VI. abducens motor My
VII. facial both Brother
VIII. auditory sensory Says
IX. glossopharyngeal both Bad
X. vagus both Business
XI. accessory motor Marrying
XII. hypoglossal motor Money

11. Nervous Integration Handout Spinal Tracts
A. Sensation
1. Levels of sensation
2. Modality
3. Components of a sensation
4. Generator potentials and
receptor potentials
5. Adaptation of sensory receptors
B. General senses
1. Cutaneous sensations
2. Proprioceptive sensations
C. Physiology of sensory pathways
1. Posterior column-medial lemniscus
pathway
2. Anterolateral (spinothalamic)
pathways
3. Somatosensory cortex
D. Physiology of motor pathways
1. Direct (pyramidal) pathways
2. Indirect (extrapyramidal) pathways

12. The three essential functions of the nervous system are:
1. sense changes
2. integrate and interpret
3. respond
How do the various components of the nervous system cooperate in performing these functions?

13. Sensation versus Perception
A sensation may or not be perceived (conscious awareness of the stimulus)
Modality-the type of stimulus or sensation it produces –vision, hearing, taste.

14. Levels of Sensation 1. spinal 2. brain stem 3. thalamus
4. cerebral cortex

15. Components of a Sensation
1. stimulation
2. transduction
3. conduction
4. translation

16. Generator Potentials 1. always produce depolarization
2. will initiate an action potential in a sensory
neuron if the stimulus is strong enough to
form threshold depolarization
3. all receptors except those for vision, hearing,
equilibrium, smell, and taste create generator
potentials

17. Receptor Potentials 1. may produce depolarization or hyperpolarization
2. never directly initiate an action potential in a sensory neuron
3. directly regulates release of neurotransmitter onto a sensory neuron that may initiate threshold depolarization

18. Types of Receptors 1. interceptors (visceroceptors) 2. exteroceptors
3. proprioceptors
__________________________
mechanoreceptors
thermoreceptors
chemoreceptors
nociceptors
photoreceptors

19. Adaptation of sensory receptors
1. fast-adapting (phasic) receptors
Adapt very quickly
Specialized for signaling changes in a particular stimulus
Pressure, touch, hot, smell
2. slow-adapting (tonic) receptors
Adapt slowly, continuing to initiate impulses as long as stimulus persists
Pain, body position, cold, chemical composition of blood

20. Cutaneous Sensations 1. tactile, thermal, pain 2. receptor locations
3. receptor distribution

21. Proprioceptive Sensations
1. proprioceptors
2. locations
3. body position sense
4. adapt slowly

22. Physiology of Sensory Pathways
1. most sensory input decussates
2. somatosensory cortex
3. perception
4. Three neurons are required
a. first-order neuron b. second-order neuron
c. third-order neuron

23. Tracts of the Spinal Cord

24. Posterior Column Pathway
1. fasciculus gracilis &
fasciculus cuneatus
2. nucleus gracilis &
nucleus cuneatus
3. decussation in medulla
4. medial lemniscus
Thalamus
Somatosensory Cortex
discriminative touch
stereognosis
kinesthesia
vibration
weight, discrimination
conscious proprioception

25. Anteriolateral Pathways
lateral spinothalamic
-Pain, thermal
anterior spinothalamic tracts
-Itch,tickle,pressure,crude touch
decussate at gray commissure

26. Somatosensory Cortex 1. homunculus 2. areas of representation
3. receptor to cortical
neuron ratio = 1:1

27. Motor Cortex 1. reflex vs voluntary action 2. homunculus
3. areas of representation
4. motor neuron to motor
unit ratio = 1:1
5. upper motor neuron
6. lower motor neuron

28. Direct Pyramidal Motor Pathways
1. lateral corticospinal tracts
-- decussate at medulla
2. anterior corticospinal tracts
-- decussate at gray commissure
3. corticobulbar tracts
-- decussate in brain stem

29. Indirect (extrapyramidal) pathways for coordination and control of movement
cerebral nuclei
thalamus
cerebellum
brainstem gray matter
spinal cord association neurons
lower motor neurons
skeletal muscles
upper motor neurons of the pyramidal tracts
cerebral cortex
upper motor neurons of the extrapyramidal tracts:
rubrospinal
tectospinal
vestibulospinal
reticulospinal

30. INDIRECT (EXTRAPYRAMIDAL) MOTOR PATHWAYS
cerebral nuclei
thalamus
cerebellum
brainstem gray matter
spinal cord association neurons
lower motor neurons
skeletal muscles
upper motor neurons of the pyramidal tracts
cerebral cortex
upper motor neurons of the extrapyramidal tracts:
rubrospinal
tectospinal
vestibulospinal
reticulospinal
end