1. Nervous System II
Divisions of the Nervous System
Chapter 11
11-1

2. Membranous Coverings Meninges membranes surrounding CNS protect CNS
three layers
dura mater – outer, tough
arachnoid mater – middle, weblike
pia mater – inner, delicate
11-2

3. Meninges of the Spinal Cord
11-3

4. Ventricles interconnected cavities
within cerebral hemispheres and brain stem
continuous with central canal of spinal cord
filled with cerebrospinal fluid (csf)
lateral ventricles
third ventricle
fourth ventricle
cerebral aqueduct
11-4

5. Cerebrospinal Fluid secreted by choroid plexus
circulates in ventricles, central canal of spinal cord, and subarachnoid space
completely surrounds brain and spinal cord
clear liquid
nutritive and protective
helps maintain stable ion concentrations in CNS
11-5

6. Spinal Cord Structure extends foramen magnum to 2nd lumbar vertebra
11-6

7. Cross Section of Spinal Cord
11-7

8. Spinal Cord Functions center for spinal reflexes
conduit for nerve impulses to and from the brain
11-8

9. Reflex Arcs Reflexes – automatic, subconscious responses to stimuli
11-9

10. Knee-jerk Reflex
helps maintain posture
11-10

11. Withdrawal Reflex
protective
11-11

12. Crossed-Extensor Reflex
flexor muscles contract
flexor muscles on opposite side inhibited
extensor muscles on opposite side contract for balance
11-12

13. Tracts of the Spinal Cord
Ascending tracts conduct sensory impulses to the brain
Descending tracts conduct motor impulses from the brain to motor neurons reaching muscles and glands
11-13

14. Brain Functions interprets sensations determines perception
stores memory
reasoning
makes decisions
coordinates muscular movements
regulates visceral activities
determines personality
Major Parts
cerebrum
two cerebral hemispheres
diencephalon
brain stem
cerebellum
two cerebellar hemispheres
11-16

15. Structure of Cerebrum corpus callosum connects hemispheres
convolutions
bumps or gyri
sulci
grooves
longitudinal fissure
separates hemispheres
transverse fissure
separates cerebrum from cerebellum
11-19

16. Lobes of Cerebrum
Frontal
Parietal
Temporal
Occipital
Insula
11-20

17. Functions of Cerebrum interpretation initiating voluntary movements
storing memory
retrieving memory
reasoning
center for intelligence and personality
11-21

18. Functional Regions of Cerebral Cortex
Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system
11-22

19. Motor Areas Primary Motor Areas (red) Broca’s Area (purple)
frontal lobes
control voluntary muscles
Broca’s Area (purple)
anterior to primary motor cortex
usually in one hemisphere
controls muscles needed for speech
Frontal Eye Field
above Broca’s area
controls voluntary movements of eyes and eyelids
11-23

20. Motor Areas
11-24

21. Sensory Areas Cutaneous Sensory Area (yellow) Visual Area (blue)
parietal lobe
interprets sensations on skin
Visual Area (blue)
occipital lobe
interprets vision
Auditory Area (purple)
temporal lobe
interprets hearing
11-25

22. Sensory Areas
11-26

23. Association Areas
regions of cortex that are not primary motor or primary sensory areas
widespread throughout the cerebral cortex
analyze and interpret sensory experiences
provide memory, reasoning, verbalization, judgment, emotions
11-27

24. Association Areas Frontal Lobe Association Areas concentrating
planning
problem solving
judging
Temporal Lobe Association Areas
remember visual scenes
remember music
remember complex patterns
Parietal Lobe Association Areas
understanding speech
using words to express thought
Occipital Lobe Association Areas
combine visual images with other sensory experiences
11-28

25. Hemisphere Dominance
In over 90% of population, left hemisphere is dominant
Nondominant hemisphere controls
nonverbal tasks
motor tasks
understanding and interpreting musical and visual patterns
provides emotional and intuitive thought processes
Dominant hemisphere controls
speech
writing
reading
verbal skills
analytical skills
computational skills
11-29

26. Memory Short Term working memory closed circuit
circuit is stimulated over and over
when impulse flow stops, memory disappears
Long Term
changes structure and function of neurons
enhanced synaptic transmission
11-30

27. Basal Nuclei masses of gray matter deep within cerebral hemispheres
caudate nucleus, putamen, globus pallidus
produce dopamine
control certain muscular activities
11-31

28. Diencephalon between cerebral hemispheres and brainstem
surrounds third ventricle
thalamus
hypothalamus
optic tracts
optic chiasm
infundibulum
posterior pituitary
mammillary bodies
pineal gland
11-32

29. Diencephalon Thalamus
gateway for sensory impulses heading to cerebral cortex
receives all sensory impulses (except smell)
channels impulses to appropriate part of cerebral cortex for interpretation
Hypothalamus
maintains homeostasis by regulating visceral activities
links nervous and endocrine systems
11-33

30. Limbic System Consists of portions of frontal lobe
portions of temporal lobe
hypothalamus
thalamus
basal nuclei
other deep nuclei
Functions
controls emotions
produces feelings
interpret sensory impulses
11-34

31. Brain Stem
Three Parts
Midbrain
Pons
Medulla Oblongata
11-35

32. Midbrain between diencephalon and pons
contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain
cerebral aqueduct
cerebral peduncles – bundles of nerve fibers
corpora quadrigemina – centers for visual and auditory reflexes
11-36

33. Pons rounded bulge on underside of brainstem
between medulla oblongata and midbrain
helps regulate rate and depth of breathing
relays nerve impulses to and from medulla oblongata and cerebellum
11-37

34. Medulla Oblongata enlarged continuation of spinal cord
conducts ascending and descending impulses between brain and spinal cord
contains cardiac, vasomotor, and respiratory control centers
contains various nonvital reflex control centers (coughing, sneezing, vomiting)
11-38

35. Reticular Formation
complex network of nerve fibers scattered throughout the brain stem
extends into the diencephalon
connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum
filters incoming sensory information
arouses cerebral cortex into state of wakefulness
11-39

36. Types of Sleep Slow Wave person is tired
decreasing activity of reticular system
restful
dreamless
reduced blood pressure and respiratory rate
ranges from light to heavy
alternates with REM sleep
Rapid Eye Movement (REM)
some areas of brain active
heart and respiratory rates irregular
dreaming occurs
11-40

37. Cerebellum inferior to occipital lobes
posterior to pons and medulla oblongata
two hemispheres
vermis connects hemispheres
cerebellar cortex – gray matter
arbor vitae – white matter
cerebellar peduncles – nerve fiber tracts
dentate nucleus – largest nucleus in cerebellum
integrates sensory information concerning position of body parts
coordinates skeletal muscle activity
maintains posture
11-41

38. Peripheral Nervous System
Cranial nerves arising from the brain
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
Spinal nerves arising from the spinal cord
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
11-42

39. Cranial Nerves
11-46

40. Cranial Nerves I and II Olfactory (I) sensory
fibers transmit impulses associated with smell
Optic (II)
sensory
fibers transmit impulses associated with vision
11-47

41. Cranial Nerves III and IV
Oculomotor (III)
primarily motor
motor impulses to muscles that
raise eyelids
move the eyes
focus lens
adjust light entering eye
Trochlear (IV)
primarily motor
motor impulses to muscles that move the eyes
11-48

42. Cranial Nerve V Trigeminal (V) mixed opthalmic division
sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
maxillary division
sensory from upper teeth, upper gum, upper lip, palate, and skin of face
mandibular division
sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip
motor to muscles of mastication and muscles in floor of mouth
11-49

43. Cranial Nerves VI and VII
Abducens (VI)
primarily motor
motor impulses to muscles that move the eyes
Facial (VII)
mixed
sensory from taste receptors
motor to muscles of facial expression, tear glands, and salivary glands
11-50

44. Cranial Nerves VIII and IX
Glossopharyngeal (IX)
mixed
sensory from pharynx, tonsils, tongue, and carotid arteries
motor to salivary glands and muscles of pharynx
Vestibulocochlear (VIII)
sensory
sensory from equilibrium receptors of ear
sensory from hearing receptors
11-51

45. Cranial Nerve X Vagus (X) mixed
somatic motor to muscles of speech and swallowing
autonomic motor to viscera of thorax and abdomen
sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
11-52

46. Cranial Nerves XI and XII
Accessory (XI)
primarily motor
motor to muscles of soft palate, pharynx, larynx, neck, and back
Hypoglossal (XII)
primarily motor
motor to muscles of the tongue
11-53

47. Spinal Nerves mixed nerves 31 pairs 8 cervical (C1 to C8)
12 thoracic (T1 to T12)
5 lumbar (L1 to L5)
5 sacral (S1 to S5)
1 coccygeal (Co)
11-54

48. Dermatome
an area of skin that the sensory nerve fibers of a particular spinal nerve innervate
11-56

49. Autonomic Nervous System
functions without conscious effort
controls visceral activities
regulates smooth muscle, cardiac muscle, and glands
efferent fibers typically lead to ganglia outside CNS
Two Divisions
sympathetic – prepares body for fight or flight situations
parasympathetic – prepares body for resting and digesting activities
11-60

50. Sympathetic Division
11-64

51. Parasympathetic Division
11-66

52. Control of Autonomic Activity
Controlled largely by CNS
Medulla oblongata regulates cardiac, vasomotor and respiratory activities
Hypothalamus regulates visceral functions
Limbic system and cerebral cortex control emotional responses
11-70

53. Life-Span Changes Brain cells begin to die before birth
Over average lifetime, brain shrinks 10%
Most cell death occurs in temporal lobes
By age 90, frontal lobe has lost half its neurons
Number of dendritic branches decreases
Decreased levels of neurotransmitters
Fading memory
Slowed responses and reflexes
Changes increase risk of falling
Sleep problems common
11-71

54. Clinical Application Cerebral Injuries and Abnormalities Concussion
brain jarred against cranium
loss of consciousness
temporary loss of memory
mental cloudiness
headache
recovery usually complete
Cerebral Palsy
motor impairment at birth
caused by blocked cerebral blood vessels during development
seizues
learning disabilities
Cerebrovascular Accident
stroke
sudden interruption in blood flow
brain tissues die
11-72