1. GRCC BI 121
Instructor - Rierson
Nervous System

2. Introduction to the Nervous System
Describe the following structures and their relationship to the nervous system.
central nervous system (CNS)
peripheral nervous system (PNS)
neuron
neuroglia or glial cells

3. Components of the Nervous System
Central Nervous System (CNS):
Structurally divided into:
Brain
Spinal cord

4. Central Nervous System
Spinal Cord
Brain

5. Components of the Nervous System
Peripheral Nervous System (PNS):
Network of peripheral nerves
Structurally divided into:
Cranial nerves – 12 pairs; connect directly to brain
Spinal nerves – 31 pairs; connect directly to spinal cord

6. Peripheral nervous system
Peripheral nerves
Cranial nerves
Lumbar spinal nerves
Sacral spinal nerves
Coccygeal nerve
Cervical spinal nerves
Thoracic spinal nerves
Spinal nerves
The Peripheral Nervous System

7. Neuron
Specialized cell able to generate and transmit action potentials, throughout the body
The Peripheral Nervous System

8. Neuroglia (glial) cells
Specialized cells responsible for supporting neurons.
The Peripheral Nervous System

9. Cytology
2. Using a microscope image of a giant multipolar neuron, a slide of a nerve in longitudinal section, a slide of astrocytes, models, charts, and text illustrations, identify the structures of the following parts of the neuron and related structures and astrocytes. An # indicates those structures that can be seen on a microscope image.
cell body #
nucleus #
process #
axon #
synaptic (axon) terminals
collateral branch
dendrite #

10. Neuron
The Peripheral Nervous System

11. Axon Structure

12. Cytology (cont.)
2. Using a microscope image of a giant multipolar neuron, a slide of a nerve in longitudinal section, a slide of astrocytes, models, charts, and text illustrations, identify the structures of the following parts of the neuron and related structures and astrocytes.
astrocyte #
synaptic cleft
Schwann cell #
myelinated fiber (myelin) #
node #

13. 3. Neuron Classification
A. Identify and describe neurons with respect to their structure. Use the following terms:
unipolar neuron
bipolar neuron
multipolar neuron
B. Illustrate the spatial relationship of these different types of neurons to each other. Use the following terms:
sensory (afferent) neuron
motor (efferent) neuron
association neuron or interneuron

14. A. 4 major anatomical classes of neurons
Bipolar
Anaxonic
Dendrites
Dendritic
process
Cell body
Axon
Synaptic
terminals
Unipolar
Multipolar
Dendrites
Initial
segment
Dendrites
Axon
Neurons may be classified on the basis of structure or function
Axon
Axon
Synaptic
terminals
Synaptic
terminals

15. B. 3 Basic functional classes of neurons
association neuron

16. Nerve Structure
4. Using a prepared microscope slide of a nerve cross section, identify and describe the following structures:
Endoneurium
Perineurium
Fascicle
Epineurium

17. Spinal nerve structure
Connective Tissue
Layers of a Spinal Nerve
Epineurium
Perineurium
Endoneurium
Spinal nerves have a consistent anatomical structure and pattern of distribution
Schwann cell
Blood vessels
Fascicle
Myelinated
axon

18. Classification of Nerves
5. Distinguish between
mixed nerves
sensory (afferent) nerves
motor (efferent) nerves

19. Spinal Nerve Rami Each spinal nerve branches into:
Rami (singular ramus):
Dorsal ramus – innervates muscles, joints, skin of back
Ventral ramus – innervates structures in lateral and anterior trunk and limbs
In thoracic and upper lumbar segment, carry motor output of sympathetic division of autonomic nervous system ("fight or flight" response)

20. Spinal nerve branches ganglion Dorsal ramus Dorsal root Spinal nerve
Ventral
root
Ventral ramus
Sympathetic
Autonomic
Spinal nerves have a consistent anatomical structure and pattern of distribution

21. Cranial Nerves 12 pairs of cranial nerves
Classified as sensory, special sensory, motor, or mixed
Name relates to appearance or function
Roman numeral corresponds to position on brain

22. Protective Tissue Layers
6. Using illustrations, cadaver, and sheep brains, identify the following structures:
meninges
dura mater
subdural space
arachnoid mater
subarachnoid space
pia mater

23. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures. Note that not all structures will be seen on the cadaver and sheep brains. Those structures indicated by an (*) should be identified on the human cadaver while those indicated by an (#) should be identified on the sheep brain.
cerebral hemispheres *#
gyri(us) *#
sulci(us) *#
longitudinal fissure *#
central sulcus *
lateral sulcus *

24. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures.
frontal lobe *#
parietal lobe *#
occipital lobe *#
temporal lobe *#

25. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures.
cerebral cortex *#
cerebral white matter *#

26. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures.
olfactory bulbs/tracts *#
optic nerves/chiasma/tract *#
pituitary gland (hypophysis) *
mammillary bodies *#
corpus callosum *#

27. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures.
diencephalon *#
thalamus *#
hypothalamus *#
epithalamus *#
pineal body (gland) *#

28. Brain Structures
7. Using illustrations, cadaver, and sheep brains, identify the following structures.
brain stem *#
midbrain *#
pons *#
medulla oblongata *#
cerebellum *#
corpora quadrigemina *#

29. CSF & Ventricles
8. Using illustrations, cadaver, and sheep brains, identify the following structures/components. Those structures indicated by an (*) should be identified on the human cadaver while those indicated by an (#) should be identified on the sheep brain.
cerebrospinal fluid
lateral ventricles (#1 & #2)*#
third ventricle*#
central canal of the spinal cord
fourth ventricle*#
cerebral aqueduct

30. Cranial Nerves
9. List the cranial nerves by name and number, and one primary function for each nerve (see text for functions).
Using the cadaver, identify:
olfactory bulb and tract
optic nerve
optic chiasma
optic tract.

31. Cranial nerves
Optic Nerve (II)
Trochlear Nerve (IV)
Facial Nerve (VII)
Motor nerve to muscles of mastication
Motor nerve to facial muscles
Oculomotor Nerve (III)
Abducens Nerve (VI)
Trigeminal Nerve (V)
Sensory nerve
to tongue and soft palate
Vestibulocochlear
Nerve (VIII)
Olfactory bulb
Cochlear
branch
Olfactory tract
Trigeminal nerve (V)
Vestibular branch
Olfactory Nerve (I)
Facial nerve (VII)
Glossopharyngeal
Nerve (IX)
Pituitary gland
Pons
Vestibulocochlear nerve (VIII)
Medulla
oblongata
KEY
Glossopharyngeal nerve (X)
Sensory nerve to
posterior tongue
Sensory nerves
Motor nerves
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves
Vagus nerve (X)
Motor nerve to
pharyngeal muscles
Hypoglossal
Nerve (XII)
Accessory Nerve (XI)
To tongue
muscles
To sternocleidomastoid
and trapezius muscles
Vagus Nerve (X)

32. Cranial Nerves I, II, III Olfactory nerve (I): Optic nerve (II):
Function: special sensory
Innervation: olfactory epithelium
Optic nerve (II):
Innervation: retina of eye
Oculomotor nerve (III):
Function: motor
Innervation: extrinsic and intrinsic eye muscles and eyelid muscle (levator palpebrae superioris)

33. Olfactory Nerve (I) Sensory nerves Motor nerves Olfactory bulb
tract
Olfactory Nerve (I)
Pituitary
gland
Pons
Medulla
oblongata
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves
KEY
Sensory nerves
Motor nerves

34. Cranial nerves going to and from the eye
Optic Nerve (II)
Trochlear Nerve (IV)
Oculomotor Nerve (III)
Abducens Nerve (VI)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves
KEY
Sensory nerves
Motor nerves

35. Cranial Nerves IV, V, VI Trochlear nerve (IV): Trigeminal nerve (V):
Function: motor
Innervation: superior oblique muscle
Trigeminal nerve (V):
Function: mixed
Innervation: sensory – parts of face, lips, palate, tongue; motor – muscles of mastication
Abducens nerve (VI):
Innervation: lateral rectus muscle

36. Trigeminal nerve Trigeminal Nerve (V) KEY Motor nerve to muscles
of mastication
Sensory nerves
Motor nerves
Trigeminal Nerve (V)
Trigeminal
nerve (V)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

37. Cranial Nerves VII, VIII, IX
Facial nerve (VII):
Function: mixed
Innervation: sensory – taste receptors anterior 2/3 tongue; motor – muscles of facial expression, lacrimal gland, salivary glands
Vestibulocochlear nerve (VIII):
Function: special sensory
Innervation: cochlea (hearing), vestibule (motion and balance)
Glossopharyngeal nerve (IX):
Innervation: sensory – posterior 1/3 of tongue, pharynx, palate; motor – pharyngeal muscles and parotid salivary gland

38. Facial Nerve Facial Nerve (VII) Motor nerve KEY to facial muscles
Sensory nerves
Motor nerves
Sensory nerve
to tongue and
soft palate
Facial nerve (VII)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

39. Vestibulocochlear Nerve
Vestibulocochlear Nerve (VIII)
KEY
Cochlear
branch
Sensory nerves
Motor nerves
Vestibular branch
Vestibulocochlear nerve (VIII)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

40. Glossopharyngeal Nerve
KEY
Sensory nerves
Motor nerves
Glossopharyngeal Nerve (IX)
Sensory nerve to
posterior tongue
Glossopharyngeal
nerve (X)
Motor nerve to
pharyngeal muscles
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

41. Cranial Nerves X, XI, XII Vagus nerve (X): Accessory nerve (XI):
Function: mixed
Innervation: sensory – pharynx, ear, diaphragm, visceral organs; motor – palate and pharyngeal muscles; visceral organs
Accessory nerve (XI):
Function: motor
Innervation: skeletal muscles of palate, pharynx, larynx, sternocleidomastoid and trapezius muscles
Hypoglossal nerve (XII):
Innervation: tongue muscles

42. Vagus Nerve KEY Sensory nerves Motor nerves Vagus nerve (X)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

43. Accessory Nerve KEY Sensory nerves Motor nerves Accessory Nerve (XI)
To sternocleidomastoid
and trapezius muscles
Accessory Nerve (XI)
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

44. Hypoglossal Nerve KEY Sensory nerves Motor nerves Hypoglossal
Nerve (XII)
To tongue
muscles
The twelve pairs of cranial nerves are classified as sensory, special sensory, motor, or mixed nerves

45. Spinal Cord
10. Using illustrations and the cadaver, identify the following structures. Note that plexuses need only be identified by general area.
spinal cord*
cauda equina*
gray matter*
central canal
dorsal root
dorsal root ganglion*
ventral root
conus medullaris*
filum terminale*
white matter*

46. Spinal Cord

47. Spinal Nerves
10. Using illustrations and the cadaver, identify the following structures. Note that plexuses need only be identified by general area.
spinal nerves*
cervical plexus*
phrenic nerve*
brachial plexus*
musculocutaneous nerve*
median*
axillary nerve*
radial nerve *
ulnar nerve *

48. Nerve Plexuses Complex interwoven network of nerves
Results from fusing small skeletal muscles (each with separate ventral rami) into larger muscles during development
Four major plexuses:
Cervical
Brachial
Lumbar
Sacral

49. Spinal Nerve Plexuses Phrenic nerve Axillary nerve Musculocutaneous
Femoral nerve
Sciatic nerve
Median nerve
Ulnar nerve
Radial nerve
Thoracic nerves
Musculocutaneous
nerve
Axillary nerve
Phrenic nerve
Sacral plexus
Lumbar plexus
Brachial plexus
Cervical plexus C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 T8 T9
T10
T11
T12 L1 L2 L3 L4 L5 S1 S2 S3 S4 S5
Co1
Spinal nerves form nerve plexuses that innervate the skin and skeletal muscles

50. Cervical Plexus Ventral rami of spinal nerves C1–C5
Innervates muscles of neck and into thoracic cavity
Phrenic nerve:
Provides nerve supply to diaphragm

51. Cervical Plexus Phrenic nerve Nerve Roots of Cervical Plexus C1 C2 C3
Spinal nerves form nerve plexuses that innervate the skin and skeletal muscles
Phrenic nerve

52. Brachial Plexuses Brachial plexus: Ventral rami of spinal nerves C5–T1
Innervates pectoral girdle and upper limbs

53. Brachial Plexus Musculocutaneous nerve Median nerve Ulnar nerve
Radial nerve
Spinal nerves form nerve plexuses that innervate the skin and skeletal muscles
Ulnar nerve
Median nerve

54. Spinal Nerves
10. Using illustrations and the cadaver, identify the following structures. Note that plexuses need only be identified by general area.
lumbar plexus*
sacral plexus*
femoral nerve*
sciatic nerve *
common fibular nerve
tibial nerve

55. Lumbar and Sacral Plexuses
Lumbar plexus:
Arises from lumbar segments of spinal cord
Innervates pelvic girdle and lower limbs
Sacral plexus:
Arises from sacral segments of spinal cord

56. Lumbar & Sacral Plexuses
Femoral nerve
Sciatic nerve
Common fibular nerve
Spinal nerves form nerve plexuses that innervate the skin and skeletal muscles

57. Sensory Pathways & Reflexes

58. Reflexes Rapid, automatic response to specific stimuli
Preserve homeostasis by allowing rapid adjustments in function
Reflex arc:
Receptor
Sensory neuron
Information processing
Motor neuron
Effector

59. Stretch Reflex One of simplest and fastest reflex arcs
Monosynaptic (one synapse involved)
For example, patellar reflex:
Receptor – tap patellar tendon with hammer, receptors in quadriceps muscle stretched
Sensory neuron – carries stretch message directly to motor neuron
Information processing – in patellar reflex, processing is in cell body of motor neuron
Motor neuron – carries message back to effector
Effector – quadriceps muscle stimulated to contract

60. Steps in a Stretch Reflex Arc
Activation of a
Sensory Neuron
STEP 1
Arrival of the
Stimulus and
Receptor
STEP 3
Information Processing in the CNS
STEP 4
Activation of a Motor Neuron
STEP 5
Response of a Peripheral
Effector
Motor neuron (stimulated)
Sensory neuron (stimulated)
Contraction
Response
(muscle spindle)
REFLEX
ARC
Spinal
cord
Stretch
KEY
Steps in a Stretch Reflex Arc
Reflexes are rapid, automatic responses to stimuli

61. Withdrawal Reflex More complex than stretch reflex
Involves multiple neurons
Moves affected parts of body away from stimulus
Receptor – pain receptors responding to tissue damage
Sensory neuron – carries pain message to spinal cord
Information processing – sensory neuron stimulates interneuron, which activates motor neuron
Motor neuron – carries message back to effector
Effector – skeletal muscle contraction to pull away from stimulus

62. Steps in a Withdrawal Reflex arc
The activation of a
Sensory Neuron
STEP 1
The arrival
of a Stimulus
and Activation of
a Receptor
STEP 3
Information
Processing
STEP 5
The Response
of a Peripheral
Effector
STEP 4
The Activation
of a Motor
Neuron
Dorsal root
ganglion
To higher centers
REFLEX
ARC
Receptor
Stimulus
Sensory neuron (stimulated)
Excitatory interneuron
Motor neuron (stimulated)
KEY
Steps in a Withdrawal Reflex arc
Reflexes are rapid, automatic responses to stimuli

63. Reflex Tests Activities in brain can facilitate or inhibit reflexes
Facilitation of reflex – reinforcement
Stretch reflexes often tested during physical exam to provide information about status of spinal cord segments:
Biceps reflex
Triceps reflex
Ankle-jerk reflex

64. Clinical Reflex Tests Biceps reflex Ankle-jerk reflex Triceps reflex
Reflexes can be used to determine the location and severity of damage to the CNS

65. Babinski Sign and Plantar Reflex
In infants, stroking foot on lateral side of sole results in fanning of toes – called positive Babinski sign
As descending motor pathways develop, they inhibit this reflex
In normal adults, stroking foot on lateral side of sole results in curling toes – called plantar reflex (negative Babinski sign)
Positive Babinski sign in adult indicates damage to CNS

66. Babinski Sign
Reflexes can be used to determine the location and severity of damage to the CNS

67. Plantar reflex
Reflexes can be used to determine the location and severity of damage to the CNS

68. Abdominal Reflex Descending motor tracts can facilitate reflexes
Light stroking of abdominal muscles produces reflexive twitch moving navel toward stimulus
Absence of reflex may indicate possible damage to descending tracts

69. Abdominal reflex
Reflexes can be used to determine the location and severity of damage to the CNS

70. Module 8.6 Reflexes can be used to determine the location and severity of damage to the CNS