1. Biology 210 Chapter 13 The Central Nervous System
Edited by John McGill
Supplemental Notes by Beth Wyatt
Original PowerPoint By: Jack Bagwell
Last Updated: March 28, 2017

2. DIVISIONS OF THE NERVOUS SYSTEM
There Are Several Ways That the Nervous System Can Be Organized
BASED ON LOCATION OF ORGANS
CENTRAL NERVOUS SYSTEM (CNS)
PERIPHERAL NERVOUS SYSTEM (PNS)

3. DIVISIONS OF THE NERVOUS SYSTEM
Organs centrally located
CENTRAL NERVOUS SYSTEM (CNS)
BRAIN
SPINAL CORD

4. DIVISIONS: Peripheral Nervous System
Organs (Nerves) Peripherally Located
2 Kinds of Nerves
CRANIAL NERVES (Originate From Brain)
SPINAL NERVES (Originate From Spinal Cord)

5. Classification Based on Pathways
BASED ON DIRECTION IN WHICH PATHWAYS CARRY INFORMATION NEURONS CONDUCT NERVE IMPULSES)
AFFERENT (aa ferent) DIVISION: All Afferent Neurons
EFFERENT (ee ferent) DIVISION: All Efferent Neurons

6. Classification Based on Effectors
BASED ON EFFECTORS INNERVATED/REGULATED
SOMATIC NERVOUS SYSTEM (SNS)
AUTONOMIC NERVOUS SYSTEM (ANS)

7. Somatic: Voluntary Effectors
SOMATIC NERVOUS SYSTEM (SNS)
Effectors: Skeletal Muscles
Voluntary
Somatic Effectors

8. Autonomic: Involuntary Effectors
BASED AUTONOMIC NERVOUS SYSTEM (ANS)
Effectors: Cardiac and Smooth Muscle,Glands
Involuntary
Autonomic/Visceral Effectors)

9. Autonomic: 2 Divisions
SYMPATHETIC DIVISION-Response of Autonomic Effectors During Stress
PARASYMPATHETIC DIVISION-Response of Autonomic Effectors During Nonstress

10. COVERINGS OF THE BRAIN AND SPINAL CORD
Coverings Provide Protection
2 Kinds
OUTER COVERING - BONE
CRANIAL BONES: BRAIN
VERTEBRAE: SPINAL CORD
INNER COVERING – MEMBRANES (MENINGES)
LAYERS OF MENINGES
DURA MATER
ARACHNOID MEMBRANE
PIA MATER

11. BONE COVERS THE BRAIN AND SPINAL CORD
CRANIAL BONES: BRAIN
VERTEBRAE: SPINAL CORD

12. Vertebra & Spinal Cord

13. INNER COVERING MEMBRANES (MENINGES)
LAYERS OF MENINGES
DURA MATER
ARACHNOID MEMBRANE
PIA MATER

14. LAYERS OF MENINGES DURA MATER Outermost Layer of Meninges Tough, White
An Extension of Periosteum

15. Dura Mater of Inferior Sheep Brain
Pituitary
Optic Chiasma

16. LAYERS OF MENINGES ARACHNOID MEMBRANE Middle Layer of Meninges
Delicate

17. LAYERS OF MENINGES PIA MATER Innermost Layer of Meninges Thin
Transparent
Adheres to CNS
Contains Blood Vessels

18. Pia Mater of Superior Sheep Brain

19. SPACES BETWEEN MENINGES
EPIDURAL SPACE
SUBDURAL SPACE
SUBARACHNOID SPACE

20. EPIDURAL SPACE “Space Above Dura” (Between Bone & Dura Mater)
Contains Connective Tissue (Adipose)

21. Epidural Space

22. SUBDURAL SPACE “Space Below Dura” (Between Dura Mater & Arachnoid)
Contains a Serous Fluid That Provides Lubrication

23. SUBARACHNOID SPACE
SPACES “Space Below the Arachnoid” (Between Arachnoid & Pia Mater)
Contains Cerebrospinal Fluid

24. CEREBROSPINAL FLUID The Fluid That Circulates In and Around the CNS
FUNCTION
Protection (A Cushion of Fluid)
FLUID SPACES
The Spaces Where Cerebrospinal Fluid Circulates

25. CEREBROSPINAL FLUID: FLUID SPACES
WITHIN BRAIN
VENTRICLES
4 Fluid Spaces Within the Brain
LATERAL (FIRST AND SECOND) VENTRICLES
THIRD VENTRICLE
FOURTH VENTRICLE
CEREBRAL AQUEDUCT
WITHIN SPINAL CORD
CENTRAL CANAL

26. CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain
LATERAL (FIRST AND SECOND) VENTRICLES
2, Located in Each Cerebral Hemisphere
The Largest of the Ventricles

27. CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain
THIRD VENTRICLE
Lies Inferior and Medial to the Lateral Ventricles

28. CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain
FOURTH VENTRICLE
Diamond Shaped Space, Located Between the Brainstem and the Cerebellum

29. CEREBROSPINAL FLUID within the BRAIN
CEREBRAL AQUEDUCT
Canal That Connects the Third and Fourth Ventricles

30. CEREBROSPINAL FLUID within the SPINAL CORD
CENTRAL CANAL
Passageway Within the Spinal Cord
Continuous With the Fourth Ventricle

31. CEREBROSPINAL FLUID Circulation
AROUND BRAIN AND SPINAL CORD
SUBARACHNOID SPACE

32. CEREBROSPINAL FLUID Formation
FORMATION FROM BLOOD
Choroid Plexuses: Capillary Networks Located in Each of the Ventricles
As Blood Flows Through Choroid Plexuses,
Some of the Fluid from Blood Filters Through the Plexuses and into the,
Ventricles, The Fluid is Now Known as CSF

33. Choroid Plexuses

34. CEREBROSPINAL FLUID Circulation
FROM LATERAL VENTRICLES 
THIRD VENTRICLE
CEREBRAL AQUEDUCT 
FOURTH VENTRICLE* 
CENTRAL CANAL 
SUBARACHNOID SPACE 
BACK TO BLOOD (ARACHNOID VILLI)

35. CEREBROSPINAL FLUID Circulation 2nd Pathway
*NOTE: ADDITIONAL PATHWAY:
ONCE IN FOURTH VENTRICLE 
SUBARACHNOID SPACE 
BACK TO BLOOD (ARACHNOID VILLI)
Arachnoid Villi: Fingerlike Extensions of Arachnoid That Project into Blood Vessels

36. SPINAL CORD STRUCTURE LOCATION, EXTENT, SHAPE Spinal Cavity
Extends from Foramen Magnum to Lower Border of the First Lumbar Vertebra (approx. 18 inches)
Oval Cylinder

37. SPINAL CORD STRUCTURE: Grooves
ANTERIOR MEDIAN FISSURE
Deep Groove in the Anterior Midline
POSTERIOR MEDIAN SULCUS
Groove in the Posterior Midline

38. Anterior Median Fissure
Olive
Pyramids
Cerebellum

39. Posterior Median Sulcus: 400X+

40. Posterior Median Sulcus & Others

41. SPINAL CORD: NERVE ROOTS
NERVE ROOTS/SPINAL NERVES
Spinal Nerves Attached to Spinal Cord by Nerve Roots (example nerves)
DORSAL NERVE ROOT: NF OF AFFERENT NEURONS
VENTRAL NERVE ROOT: NF OF EFFERENT NEURONS

42. DORSAL NERVE ROOT: NF OF AFFERENT NEURONS
Unipolar
Receptors/Dendrites in Sense Organs
Axons (Peripheral Portion) in Spinal Nerve
Cell Bodies in Dorsal Root Ganglion Axons (Central Portion) in Dorsal Nerve Root

43. VENTRAL NERVE ROOT: NF OF EFFERENT NEURONS
Efferent Neurons: Multipolar
Dendrites/Cell Bodies in Gray Matter of Spinal Cord
Axons in Ventral Nerve Root and S. Nerve

44. Spinal Cord Cross Section

45. Spinal Cord: Afferent (unipolar) & Efferent (multipolar) Neurons

46. Spinal Cord: Gray and White Matter
The spinal cord consists of
Gray Matter:
Consists of cell bodies of interneurons and motor neurons
White Matter
Consists of axons of neurons originating in the spinal cord and brain.

47. SPINAL CORD: Gray Matter
In Spinal Cord, Gray Matter Primarily Consists of Cell Bodies of Interneurons and Motor Neurons

48. SPINAL CORD: Gray Matter
LOCATION: Central Portion of Spinal Cord, Resembles Letter “H”
DIVISIONS: GRAY HORNS (COLUMNS), ANTERIOR, POSTERIOR, & LATERAL

49. SPINAL CORD: White Matter
Consists of axons of neurons originating in the spinal cord and brain.

50. SPINAL CORD: White Matter
LOCATION: Peripheral to Gray Matter
DIVISIONS
WHITE COLUMNS: ANTERIOR, POSTERIOR, LATERAL
TRACTS
White Columns Further Subdivided into Tracts
Names of Tracts Often Indicate 2 Things About Tract:
Where Tract Begins/Ends
White Column in Which Tract Located

51. SPINAL CORD: White Matter
WHITE COLUMNS
ANTERIOR
POSTERIOR
LATERAL

52. Gray and White Matter

53. SPINAL CORD: White Matter
FUNCTIONS
PROVIDES CONDUCTION ROUTES (2 WAY) FOR NERVE IMPULSES TRAVELING TO AND FROM THE BRAIN (WHITE MATTER)
White Matter of the Spinal Cord (Tracts) Conducts Impulses Toward and Away from the Brain
Ascending tracts conduct impulses up the SC toward the brain
Descending tracts conduct impulses down the SC away from the brain

54. SPINAL CORD: ASCENDING TRACTS
Conduct Impulses Up the SC Toward the Brain
FUNCTION
Ascending Tracts Have a Sensory Function (Carry Impulses Related To General Sensations: Hot, Cold, Pain, Pressure, Touch & Kinesthesia)
IMPORTANT ASCENDING TRACTS
SPINOTHALAMIC TRACTS
FASCICULI GRACILIS AND CUNEATUS
SPINOCEREBELLAR TRACTS

55. SPINAL CORD: DESCENDING TRACTS
DESCENDING TRACTS Elaboration
Conduct Impulses Down the SC Away from the Brain
FUNCTION
Descending Tracts Have a Motor Function
(Carry Impulses that Will Result in Voluntary Movement of Skeletal Muscles)
IMPORTANT DESCENDING TRACTS
CORTICOSPINAL TRACTS
RETICULOSPINAL TRACTS
RUBROSPINAL TRACTS

56. Spinal Cord Tracts

57. Ascending Tracts Spinocerebellar tracts Spinothalamic tracts
Impulses from stretch receptors are carried to the spinal cord.
These tracts originate in the spinal cord and transmit signals to the cerebellum
Involved in regulation of muscle tone without reaching consciousness.
Spinothalamic tracts
Fibers concerned with pain, thermal sense, and light touch
Originate in the spinal cord.
Convey sensory impulses to the thalamus.
Dorsal column: Fasciculi Gracilis and Cuneatus Tracts
Arise from spinal ganglion cells
The fasciculi terminate upon large nuclear masses (the nuclei gracilis and cuneatus) in the medulla.
Conveys signals associated with tactile, pressure, and kinesthetic (or positional) sense to sensory areas of the cerebral cortex.

58. Descending Tracts Corticospinal tract Rubrospinal tract
Concerned with skilled voluntary activity, the corticospinal tract originates from premotor, primary motor, and primary sensory cortex.
Synapse with interneurons and motor neurons.
Rubrospinal tract
Arises from cells in the midbrain.
Fibers of this tract descend the spinal cord and terminate on interneurons.
Cells of the midbrain receive input from the motor cortex and from the cerebellum (via the superior cerebellar peduncle).
The rubrospinal tract brings flexor muscle tone under the control of these two regions of the brain.
Reticulospinal tract
Arises from the reticular formation of the pons and medulla
Fibers of this tract influence voluntary movements, muscle tone, and a variety of spinal reflexes.
Fibers terminate at all spinal levels.
Receive input from regions of the motor cortex.

60. Spinal Cord Tracts

61. SPINAL CORD : Reflexes
REFLEX CENTER FOR ALL SPINAL REFLEXES (GRAY MATTER)
Gray Matter of the Spinal Cord Functions as Reflex Centers for Spinal Reflexes
Reflex Center: Center of a Reflex Arc
Spinal Reflexes: Reflexes Whose Arcs Pass Through the SC

62. SPINAL CORD : Reflexes

63. SPINAL CORD : Reflexes

64. THE BRAIN DIVISIONS SIZE BRAINSTEM CEREBELLUM DIENCEPHALON CEREBRUM
MEDULLA OBLONGATA
PONS
MIDBRAIN
CEREBELLUM
DIENCEPHALON
CEREBRUM
SIZE
In Adults, Weighs Approx. 3 Pounds

66. THE BRAIN: Brainstem BRAINSTEM STRUCTURE
Extension of SC into the Cranial Cavity
STRUCTURE
MEDULLA OBLONGATA
Lowermost Division
PONS
Middle, Swollen Division
MIDBRAIN
Uppermost Division

67. THE BRAIN: Brainstem
MIDBRAIN: Uppermost Division; Has 2 Important External Landmarks
CEREBRAL PEDUNCLES: Form Floor of Midbrain
CORPORA QUADRIGEMINIA

68. Cerebral Peduncles

69. Midbrain: Copora Quadrigemina
CORPORA QUADRIGEMINIA
Forms Roof of Midbrain
CQ Consists of 4 Rounded Structures
SUPERIOR COLLICULI (2): Visual Centers
INFERIOR COLLICULI (2): Auditory Centers

70. CORPORA QUADRIGEMINIA

71. THE BRAIN: Reticular Formation
LOCATIONS OF GRAY AND WHITE MATTER IN BRAINSTEM
WHITE MATTER –outside
RETICULAR FORMATION – inside
Reticular Formation = Mixture of Gray and White Matter Located in the Core of the Brainstem

72. Reticular Formation http://www. medinfo. ufl

73. Reticular Formation http://www. medinfo. ufl

74. THE BRAIN: Brainstem Tracts (white matter)
FUNCTIONS
The Functions of the Brainstem are Similar to the Functions of the SC
PROVIDES CONDUCTION ROUTES (2 WAY) FOR NERVE IMPULSES TRAVELING BETWEEN SPINAL CORD AND BRAIN (WHITE MATTER)
The White Matter of the Brainstem is Organized into Tracts (Ascending & Descending Which are an Extension of The Tracts of the Spinal Cord

75. THE BRAIN: Reticular Formation
REFLEX CENTER FOR BRAIN REFLEXES (GRAY MATTER)
Portions of Gray Matter Located Within the Reticular Formation Functions as Reflex Centers for Brain Reflexes
(Brain Reflexes: Reflexes Whose Arcs Pass Through the Brainstem)

76. THE BRAIN: Brain Reflexes
2 Kinds of Reflex Centers in Brainstem
VITAL REFLEX CENTERS (MEDULLA)
Reflex Centers for Vital Reflexes
Vital Reflexes: Reflexes that are Essential for Survival;
Examples: Breathing, Heart rate, BP
Names of Vital Reflex Centers:
Respiratory Centers, Cardiac Control Centers, Vasomotor Center
All of the Vital Reflex Centers are Located in the Medulla (Medulla Associated with Basic Survival)

77. THE BRAIN: Brain Reflexes
NONVITAL REFLEX CENTERS (MEDULLA, PONS, MIDBRAIN)
Reflex Centers for Nonvital Reflexes (Not Essential for Basic Survival:
Vomiting, Coughing, Hiccuping, Swallowing, Sneezing, etc.); Centers Have Same Names as Reflexes
Nonvital Reflex Centers Located in All Parts of the Brainstem

78. Brain Illusions and Information