1. The Nervous System: The Brain and Cranial Nerves
AHS 101

2. Regions of the Brain Cerebral hemispheres Diencephalon Brain stem
Cerebellum
Figure 7.12
Slide 7.27
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3. Protection of the Central Nervous System
Scalp and skin
Skull and vertebral column
Meninges
Figure 7.16a
Slide 7.44a
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4. Protection of the Central Nervous System
Cerebrospinal fluid
Blood brain barrier
Figure 7.16a
Slide 7.44b
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5. Meninges Dura mater Double-layered external covering
Periosteum – attached to surface of the skull
Meningeal layer – outer covering of the brain
Layers separate in certain places to form large veins called dural sinuses
Folds inward in several areas
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6. Meninges Arachnoid layer Pia mater Middle layer Web-like
Internal layer
Clings to the surface of the brain
Slide 7.45b
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7. Cerebrospinal Fluid Clear liquid similar to blood plasma composition
Formed by the choroid plexus
Forms a watery cushion to protect the brain
Circulated in arachnoid space, ventricles, and central canal of the spinal cord
Returns to blood via villi in the dural sinuses
Slide 7.46
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8. Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17a
Slide 7.47a
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9. Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17b
Slide 7.47b
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10. Blood Brain Barrier
Includes the least permeable capillaries of the body
Excludes many potentially harmful substances
Useless against some substances
Fats and fat soluble molecules
Respiratory gases
Alcohol
Nicotine
Anesthesia
Slide 7.48
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11. Cerebral Hemispheres (Cerebrum)
Paired (left and right) superior parts of the brain
Include more than half of the brain mass
Figure 7.13a
Slide 7.28a
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12. Cerebral Hemispheres (Cerebrum)
The surface is made of ridges (gyri) and grooves (sulci)
Figure 7.13a
Slide 7.28b
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13. Lobes of the Cerebrum
Fissures (deep grooves) divide the cerebrum into lobes
Surface lobes of the cerebrum
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Slide 7.29a
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14. Lobes of the Cerebrum Slide 7.29b Figure 7.15a
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15. Specialized Areas of the Cerebrum
Somatic sensory area – receives impulses from the body’s sensory receptors
Primary motor area – sends impulses to skeletal muscles
Broca’s area – involved in our ability to speak
Slide 7.30
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16. Sensory and Motor Areas of the Cerebral Cortex
Figure 7.14
Slide 7.31
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17. Specialized Area of the Cerebrum
Cerebral areas involved in special senses
Gustatory area (taste)
Visual area
Auditory area
Olfactory area
Slide 7.32a
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18. Specialized Area of the Cerebrum
Interpretation areas of the cerebrum
Speech/language region
Language comprehension region
General interpretation area
Slide 7.32b
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19. Specialized Area of the Cerebrum
Figure 7.13c
Slide 7.32c
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20. Memory and Learning Short-term memory Long-term memory
Retention of information for few seconds or minutes
Information lost unless reinforced
Long-term memory
Storage of information that can be recalled later

21. Diencephalon Sits on top of the brain stem
Enclosed by the cerebral hemispheres
Made of three parts
Thalamus
Hypothalamus
Epithalamus
Slide 7.34a
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22. Diencephalon Slide 7.34b Figure 7.15
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23. Thalamus Surrounds the third ventricle
The relay station for sensory impulses
Transfers impulses to the correct part of the cortex for localization and interpretation
Slide 7.35
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24. Hypothalamus Under the thalamus
Important autonomic nervous system center
Helps regulate body temperature
Controls water balance
Regulates metabolism
Slide 7.36a
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25. Hypothalamus An important part of the limbic system (emotions)
The pituitary gland is attached to the hypothalamus
Slide 7.36b
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26. Epithalamus Forms the roof of the third ventricle
Houses the pineal body (an endocrine gland)
Includes the choroid plexus – forms cerebrospinal fluid
Slide 7.37
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27. Brain Stem Attaches to the spinal cord Parts of the brain stem
Midbrain
Pons
Medulla oblongata
Slide 7.38a
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28. Brain Stem Slide 7.38b Figure 7.15a
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29. Midbrain Mostly composed of tracts of nerve fibers
Has two bulging fiber tracts – cerebral peduncles
Has four rounded protrusions – corpora quadrigemina
Reflex centers for vision and hearing
Cranial nerves III and IV originate from the midbrain
Slide 7.39
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30. Pons
The bulging center part of the brain stem between the midbrain and medulla
Mostly composed of fiber tracts that carry impulses between the cerebellum and the rest of the nervous system
Includes nuclei involved in the control of breathing
Slide 7.40
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31. Medulla Oblongata The lowest part of the brain stem
Merges into the spinal cord
Includes important fiber tracts
Contains important control centers
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting
Slide 7.41
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32. Medulla Oblongata
Motor fibers from motor cortex extend through the medulla and most cross from one side to the other.
Results in contralateral control
Right hemisphere controls muscles in the left side of the body
Left hemisphere controls muscles in the right side of the body

33. Cerebellum Two hemispheres with convoluted surfaces
Provides involuntary coordination of body movements
Helps maintain balance in standing, walking and sitting
Helps maintain muscle tone
Slide 7.43a
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34. Cerebellum Slide 7.43b Figure 7.15a
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35. Cranial Nerves 12 pairs of nerves that mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only
Slide 7.58
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36. Distribution of Cranial Nerves
Figure 7.21
Slide 7.59
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37. Cranial Nerves I Olfactory nerve – sensory for smell
II Optic nerve – sensory for vision
III Oculomotor nerve – motor fibers to eye muscles
IV Trochlear – motor fiber to eye muscles
Slide 7.60
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38. Cranial Nerves
V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles
VI Abducens nerve – motor fibers to eye muscles
VII Facial nerve – sensory for taste; motor fibers to the face
VIII Vestibulocochlear nerve – sensory for balance and hearing
Slide 7.61
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39. Cranial Nerves
IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx
X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera
XI Accessory nerve – motor fibers to neck and upper back
XII Hypoglossal nerve – motor fibers to tongue
Slide 7.62
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40. Cranial Nerves Mnemonic (a memory aid)
On Old Olympus Towering Top, A Finn And German Vaulted A Hedge
Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Acoustic (vestibulocochlear), Glossopharyngeal, Vagus, Accessory, Hypoglossal

41. Aging of the Nervous System
Brain decreases in size and weight
Speed of processing information slows
Movements slowed
Memory diminishes