1. Brain & Cranial Nerves
Dr. Michael P. Gillespie

2. Major Parts of the Brain
Brain stem
Cerebellum
Diencephalon
Cerebrum
Dr. Michael P. Gillespie

3. Brain Stem Continuous with the spinal cord. Subdivisions
Medulla Oblongata
Pons
Midbrain
Dr. Michael P. Gillespie

4. Cerebellum Posterior to the brain stem. Cerebellum = little brain.
Dr. Michael P. Gillespie

5. Diencephalon Superior to the brain stem. Subdivisions
Thalamus
Hypothalamus
Epithalamus
Subthalamus
Di = through; encephalon = brain
Dr. Michael P. Gillespie

6. Cerebrum Supported on the diencephalon and brain stem.
Largest part of the brain.
Cerebrum = brain.
Dr. Michael P. Gillespie

7. Dr. Michael P. Gillespie

8. Brain Blood Supply Arteries Veins Internal carotid arteries
Vertebral arteries
Veins
Internal jugular veins
Dr. Michael P. Gillespie

9. Brain Blood Flow
The brain consumes about 20% of the oxygen and glucose used at rest.
A brief slowing of blood flow may cause unconsciousness.
When activity of neurons and neuroglia in a certain portion of the brain increases, blood flow to that region increases.
Dr. Michael P. Gillespie

10. Brain Blood Flow
An interruption of blood flow for 1 to 2 minutes impairs neural function.
Total deprivation of oxygen for 4 minutes causes permanent injury.
If the blood entering the brain has a low level of glucose, mental confusion, dizziness, convulsions, and loss of consciousness may occur.
Dr. Michael P. Gillespie

11. Blood Brain Barrier
The blood-brain barrier (BBB) protects the brain from harmful substances and pathogens.
It prevents the passage of many substances from the blood to the brain tissue.
Tight junctions seal together endothelial cells of brain capillaries.
Astrocytes selectively allow some substances through and not others.
Dr. Michael P. Gillespie

12. Permeability of the BBB
Water-soluble substances.
Glucose crosses the BBB by active transport.
Creatinine, urea, and most ions cross the BBB very slowly.
Proteins and most antibiotic drugs do not cross the BBB.
Lipid-soluble substances.
Oxygen, carbon dioxide, alcohol, most anesthetic agents cross easily.
Dr. Michael P. Gillespie

13. Breaching the BBB
The BBB prevents the passage of harmful substances into the brain, but it also prevents the passage of useful drugs.
Drugs are injected in a concentrated sugar solution to facilitate passage.
The high osmotic pressure causes cells lining the barrier to shrink and makes the membrane “leaky”.
Dr. Michael P. Gillespie

14. Protective Coverings Cranium Meninges.
Dura mater (Outer layer).
Two dural layers around the brain and one around the spinal cord.
Arachnoid mater (Middle layer).
Pia mater (Inner layer).
No epidural space around the brain.
Dr. Michael P. Gillespie

15. Protective Coverings
Extensions of dura mater separate parts of the brain.
Falx cerebri – separates the two hemispheres of the cerebrum.
Falx cerebelli – separates the two hemispheres of the cerebellum.
Tentorium cerebelli – separates the cerebrum from the cerebellum.
Dr. Michael P. Gillespie

16. Dr. Michael P. Gillespie

17. Cerebrospinal Fluid (CSF)
Clear colorless liquid.
Protects the brain and spinal cord from chemical and physical injuries.
Carries oxygen, glucose, and other needed chemicals from the blood to the neurons and neuroglia.
Circulates in the subarachnoid space (between the arachnoid mater and pia mater).
Dr. Michael P. Gillespie

18. Formation of CSF in the Ventricles
CSF is formed in the ventricles.
Formed by ependymal cells that cover the choroid plexuses of the ventricles.
Dr. Michael P. Gillespie

19. Formation of CSF in the Ventricles
There are 4 ventricles.
Functions of CSF.
Mechanical protection.
Shock absorption.
Buoys the brain.
Chemical protection – optimal chemical environment.
Circulation – medium of exchange for wastes and nutrients.
Dr. Michael P. Gillespie

20. Dr. Michael P. Gillespie

21. Dr. Michael P. Gillespie

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23. Dr. Michael P. Gillespie

24. Hydrocephalus
Abnormalities of the brain can interfere with drainage of CSF from the ventricles and subarachnoid space.
CSF pressure increases causing hydrocephalus.
In infants this causes the fontanels to bulge.
Dr. Michael P. Gillespie

25. Hydrocephalus
Tumors, inflammation, developmental malformations can all cause hydrocephalus.
Pressure buildup can damage the delicate nervous tissue.
A surgeon can implant a drain line called a shunt to divert CSF.
In adults, hydrocephalus may occur after head injury, meningitis, or subarachnoid hemorrhage.
Dr. Michael P. Gillespie

26. Hydrocephalus
Dr. Michael P. Gillespie

27. Brain Stem Between the brain and spinal cord. 3 regions.
Medulla oblongata.
Pons.
Midbrain.
Dr. Michael P. Gillespie

28. Medulla Oblongata A continuation of the spinal cord.
Sensory (ascending) tracts and motor (descending) tracts travel through the white matter of the medulla.
Many nerves decussate (cross over) in the medulla.
Dr. Michael P. Gillespie

29. Medulla Oblongata
Cardiovascular center regulates the heartbeat and the diameter of the blood vessels.
Dr. Michael P. Gillespie

30. Medulla Oblongata
The medullary rhythmicity area adjusts the rhythm of the breathing and controls reflexes for vomiting, coughing, and sneezing.
Dr. Michael P. Gillespie

31. Medulla Oblongata
The nuclei for the following cranial nerves reside in the medulla:
VIII (vestibulocochlear).
IX (glossopharyngeal).
X (vagus).
XI (accessory).
XII (hypoglossal).
Dr. Michael P. Gillespie

32. Dr. Michael P. Gillespie

33. Dr. Michael P. Gillespie

34. Pons Pneumotaxic area and apneustic area regulate breathing.
Nuclei for cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII (vestibulocochlear).
Dr. Michael P. Gillespie

35. Midbrain
The midbrain or mesencephalon contains the superior colliculi (visual actvities) and inferior colliculi (auditory pathways).
The midbrain contains the substantia nigra which release dopamine to help control subconscious muscle activities. Loss of these neurons results in Parkinson disease.
Cranial nerves III (oculomotor) and IV (trochlear) originate here.
Dr. Michael P. Gillespie

36. Dr. Michael P. Gillespie

37. Cerebellum The second largest part of the brain.
A main function of the cerebellum is to evaluate how well movements are being carried out and correct for discrepancies. This helps to “smooth out” movements.
Dr. Michael P. Gillespie

38. Dr. Michael P. Gillespie

39. Diencephelon Epithalamus. Thalamus.
Contains the pineal gland which secretes melatonin.
Thalamus.
Relays sensory information to the cortex.
Provides crude perception of touch, pressure, pain, and temperature.
Dr. Michael P. Gillespie

40. Dr. Michael P. Gillespie

41. Diencephelon Subthalamus. Hypothalamus. Controls body movements.
Controls and integrates activities of the ANS.
Regulates emotional and behavioral patterns.
Regulates cicadian rhythms.
Regulates eating and drinking behavior.
Produces hormones oxytocin and ADH.
Dr. Michael P. Gillespie

42. Dr. Michael P. Gillespie

43. Cerebrum Sensory areas interpret sensory impulses.
Motor areas control muscular movement.
Association areas function in emotional and intellectual processes.
Basal areas regulate gross muscle movements and regulate muscle tone.
Limbic system functions in survival behaviors.
Dr. Michael P. Gillespie

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46. Dr. Michael P. Gillespie

47. Brain Injuries
Concussion – an abrupt, temporary loss of consciousness following a blow to the head.
Most common brain injury.
Signs – headache, drowsiness, lack of concentration, confusion, amnesia.
Dr. Michael P. Gillespie

48. Brain Injuries
Contusion – bruising of the brain due to trauma and includes leakage of blood.
Signs - immediate loss of consciousness, transient cessation of respiration, decreased blood pressure.
Dr. Michael P. Gillespie

49. Brain Injuries
Laceration – tear of the brain usually from a skull fracture or gunshot wound.
Rupture of large blood vessels.
Consequences – cerebral hematoma (localized pool of blood, usually clotted), edema, and increased intracranial pressure.
Dr. Michael P. Gillespie

50. Cerebral Cortex Areas and Functions
Sensory areas – receive and interpret sensory information.
Dr. Michael P. Gillespie

51. Cerebral Cortex Areas and Functions
Motor areas – initiate movements.
Association areas – deal with integrative functions:
Memory.
Emotions.
Reasoning.
Will.
Judgement.
Personality.
Intelligence.
Dr. Michael P. Gillespie

52. Sensory Areas
Primary somatosensory area – receives sensations for touch, proprioception, pain, itching, tickle, and thermal sensations.
Located in the postcentral gyrus of the parietal lobes.
Primary visual area.
Primary auditory area.
Primary gustatory area – taste.
Primary olfactory area.
Dr. Michael P. Gillespie

53. Motor Areas
Primary motor area – located in the precentral gyrus of the frontal lobe.
Broca’s speech area – coordinates the contractions of speech and breathing muscles.
Dr. Michael P. Gillespie

54. Association Areas
Somatosensory association area – integrates and interprets sensations.
Visual association area – evaluates what is seen.
Auditory association area – evaluates sounds.
Dr. Michael P. Gillespie

55. Association Areas
Wernicke’s (posterior language) area – interprets the meaning of speech.
Common integrative area.
Premotor area – controls learned skilled movements.
Frontal eye field area – controls voluntary scanning movements of the eyes.
Dr. Michael P. Gillespie

56. Dr. Michael P. Gillespie

57. Aphasia An inability to use or comprehend words.
Dr. Michael P. Gillespie

58. Aphasia Damage to Broca’s area results in nonfluent aphasia.
Inability to properly articulate to form words.
These people know what they wish to say, but cannot speak.
Dr. Michael P. Gillespie

59. Aphasia
Damage to the auditory association area results in fluent aphasia.
Faulty understanding of spoken words.
Word deafness – inability to understand spoken words.
Word blindness – inability to understand written words.
Dr. Michael P. Gillespie

60. Cranial Nerve I - Olfactory
Type: sensory.
Function: smell.
Anosmia – loss of sense of smell.
Dr. Michael P. Gillespie

61. Cranial Nerve II – Optic Nerve
Type: sensory.
Function: vision.
Anopia – blindness in one or both eyes.
Dr. Michael P. Gillespie

62. Cranial Nerve III - Oculomotor
Type: mixed (mainly motor).
Function: movement of the upper eyelid and eyeball. Accomodation of the lens for nearn vision and constriction of the pupil.
Strabismus – deviation of the eye in which both eyes don’t focus on the same object.
Ptosis – drooping of the upper eyelid.
Diploia – double vision.
Dr. Michael P. Gillespie

63. Cranial Nerve IV – Trochlear Nerve
Type: mixed (mainly motor).
Function: movement of the eyeball.
Diplopia and strabismus occur with trochlear nerve damage.
Dr. Michael P. Gillespie

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65. Cranial Nerve V – Trigeminal Nerve
Type: mixed.
Function: conveys impulses for touch, pain, temperature and proprioception. Chewing.
Trigeminal neuralgia (tic douloureux) – pain to branches of the trigeminal nerve.
Dentists apply anesthetic to branches of this nerve.
Dr. Michael P. Gillespie

66. Dr. Michael P. Gillespie

67. Cranial Nerve VI - Abducens
Type: mixed (mainly motor).
Function: movement of the eyeball.
With damage to this nerve the eye cannot move laterally beyond the midpoint and usually points medially.
Dr. Michael P. Gillespie

68. Dr. Michael P. Gillespie

69. Cranial Nerve VII – Facial Nerve
Type: mixed.
Function: Propriception and taste. Facial expression. Secretion of saliva and tears.
Injury produces bell’s palsy (paralysis of facial muscles).
Dr. Michael P. Gillespie

70. Dr. Michael P. Gillespie

71. Cranial Nerve VIII – Vestibulocochlear Nerve
Type: mixed (mainly sensory).
Function: conveys impulses for equilibrium and hearing.
Injury can cause vertigo, ataxia (muscular incoordination), nystagmus (rapid movement of the eyeball), and tinnitus.
Dr. Michael P. Gillespie

72. Cranial Nerve IX – Glossopharyngeal Nerve
Type: mixed.
Function: taste and somatic sensations from the posterior 1/3 of the tongue. Elevates the pharynx during swallowing and speech. Stimulates the secretion of saliva.
Injury causes decreased salivary secretion, loss of taste, and difficulty swallowing.
Dr. Michael P. Gillespie

73. Dr. Michael P. Gillespie

74. Cranial Nerve X – Vagus Nerve
Type: mixed.
Function: taste and somatic sensations. Swallowing, coughing, and voice production. Regulates GI tract and heart rate.
Injury interferes with swallowing, paralyzes vocal cords, and causes the heart rate to increase.
Dr. Michael P. Gillespie

75. Dr. Michael P. Gillespie

76. Cranial Nerve XI – Accessory Nerve
Type: mixed (mainly motor).
Function: Proprioception. Swallowing, movement of head and shoulders.
If the nerves are damaged the SCM and Trapezius become paralyzed.
Dr. Michael P. Gillespie

77. Dr. Michael P. Gillespie

78. Cranial Nerve XII – Hypoglossal Nerve
Type: mixed (mainly motor).
Function: Proprioception. Movement of the tongue during speech and swallowing.
Injury results in difficulty in chewing, speaking, and swallowing. When protruded, the tongue curls towards the affected side and atrophies on the affected side.
Dr. Michael P. Gillespie

79. Dr. Michael P. Gillespie

80. Cranial Nerves I – Olfactory II – Optic III – Oculomotor
IV – Trochlear
V – Trigeminal
VI – Abducens
VII – Facial
VIII – Auditory (Vestibulocochlear)
IX – Glossopharyngeal
X – Vagus
XI – Spinal accessory
XII - Hypoglossal
Dr. Michael P. Gillespie

81. Cranial Nerves
On Old Olympus’ Towering Tops A Fin And German Viewed Some Hops.
This mnemonic device helps you memorize the names of the cranial nerves.
The first letter from each word corresponds to the first letter of each cranial nerve.
Dr. Michael P. Gillespie

82. Cranial Nerves
Some Say Marry Money, But My Brother Says Big Brains Matter Most.
This mnemonic device helps you memorize the sensory / motor distribution of the cranial nerves.
S = sensory
M = Motor
B = Both
Dr. Michael P. Gillespie