Class grades

1
Class grades

• 3 Quizzes
• 9/27 Ventricular System
• 11/20 Brainstem and Basal Ganglia
• 12/6 Cranial Nerves
• Clinical Notebooks Due
• 11/13----no late submissions accepted

• 2 Exams
• 11/1 Somatosensory System, Visual System,
  Central Auditory System, and Vestibular System
• 11/27 Motor System Cortical Level, Cerebellum,
  Brainstem, Basal Ganglia and Spinal Cord

2
The Meningesandthe Ventricular System
3
Learning Objectives

• 1. Describe the meninges, their locations, and
  their functions.
• 2. Identify parts of the ventricular cavities.
• 3. Discuss functions of cerebrospinal fluid.
• 4. Describe the mechanism of cerebrospinal fluid
  production.
• 5. Describe the circulation of cerebrospinal
  fluid.
• 6. Explain the diagnostic significance of the
  cerebrospinal fluid.

4
Protection of the CNS

• Function
• CNS is fairly soft and gelatinous in nature
• Basic protection

5
Meninges of the Brain
6
Meninges of the Brain

• Three Meninges

7
The Meninges

• Bhatnagar Andy, 1995, Figure 2.45A

8
Meningeal Layers Dura Mater

• Location
• Function

9
Meningeal Layers Dura Mater

• Structure
• Two spaces
• Two fibrous layers of the dura

10
The Meninges

• Bhatnagar Andy, 1995, Figure 2.45A

11
The Meninges

• Love Webb, 1996, Figure 3-3

12
Dural Extensions

• Falx Cerebri
• Location
• Cavity Formations

13
Dural Extensions on Midsagittal Section

• Bhatnagar Andy, 1995, Figure 2.43

14
Dural Extensions on Coronal View

• Bhatnagar Andy, 1995, Figure 2.44A

15
Dural Extensions

• Tentorium Cerebelli
• Location
• Tentorial Notch

16
Dural Extensions on Midsagittal Section

• Bhatnagar Andy, 1995, Figure 2.43

17
Dural Extensions on Coronal View

• Bhatnagar Andy, 1995, Figure 2.44A

18
Dural Extensions

• Falx Cerebelli
• Location

19
Dural Extensions on Midsagittal Section

• Bhatnagar Andy, 1995, Figure 2.43

20
Dural Extensions on Coronal View

• Bhatnagar Andy, 1995, Figure 2.44A

21
Meningeal Layers Arachnoid Membrane

• Structure
• Location

22
Meningeal Layers Arachnoid Membrane

• Spaces
• 1. Subarachnoid space
• 2. Subdural space

23
The Meninges

• Bhatnagar Andy, 1995, Figure 2.45A

24
Arachnoid Villi or Granulations

• Bhatnagar Andy, 1995, Figure 2.41

25
Meningeal Layers Pia Mater

• Location
• Structure

26
The Meninges and the Spinal Cord

• Similar Structures

27
The Spinal Cord and Its Meninges

• Bhatnagar Andy, 1995, Figure 2.46

28
The Ventricles
29
The Ventricular System

• Three Parts
• Function

30
Ventricular System in Relation to Brain Lateral
View

• Bhatnagar Andy, 1995, Figure 2.37

31
Ventricular System Lateral View

• Bhatnagar Andy, 1995, Figure 2.35A

32
Ventricular System Dorsal View

• Bhatnagar Andy, 1995, Figure 2.35B

33
The Lateral Ventricles

• Structure and Shape
• Location
• Connection
• Choroid Plexus

34
Ventricular System in Relation to Brain Lateral
View

• Bhatnagar Andy, 1995, Figure 2.37

35
The Third Ventricle

• Location and Shape
• Connection
• Choroid Plexus

36
Ventricular System in Relation to Brain Lateral
View

• Bhatnagar Andy, 1995, Figure 2.37

37
The Fourth Ventricle

• Location
• Shape
• Structure
• Function

38
Ventricular System in Relation to Brain Lateral
View

• Bhatnagar Andy, 1995, Figure 2.37

39
Subarachnoid Space

• Location
• Arachnoid Trabeculae

40
The Meninges

• Bhatnagar Andy, 1995, Figure 2.45A

41
Ventricles

• Inner Walls

42
Cerebrospinal Fluid

• Structure
• Circulation
• Function

43
Choroid Plexus

• Function
• Location

44
Path of CSF Circulation

• Pathway
• Flows from the lateral ventricles into the third
  ventricle
• Via Monros foramen
• Then flows from the third ventricle to the fourth
  ventricle through the cerebral aqueduct
• Then flows from the fourth ventricle into the
  subarachnoid space through three apertures
• Two lateral Foramina of Luschka
• One mediodorsal Magendies foramen
• Then travels to reach the inferior surface of the
  cerebrum and moves superiorly over the lateral
  aspect of each hemisphere
• Some of it moves into the subarachnoid space
  around the spinal cord

45
The Ventricular System Midsagittal View

• Bhatnagar Andy, 1995, Figure 18.2

46
Circulation of the CSF

• Love Webb,
  1996,
  Figure 3-6

47
Clinical Considerations

• Drainage of the CSF
• Inadequate Drainage of the CSF

48
Clinical Considerations

• Rate of CSF Production
• Disassociation between Production and Absorption
  Rate of the CSF

49
Clinical Considerations

• Hydrocephalus
• Increased Pressure in the Brain
• Sustained Pressure

50
MRI of Enlarged Lateral Ventricles Secondary to
Hydrocephalus

• Bhatnagar Andy, 1995, Figure 18.3

51
Medical Diagnostic Procedures

• Measurement of the pressure of the fluid
• If abnormally high, may suspect
• Intracranial tumor
• Intracranial hemorrhage
• Hydrocephalus
• Meningitis
• Encephalitis

52
Treatment

• Hydrocephalus
• No longer a fatal condition
• If diagnosed early
• Can be surgically treated
• Treatment
• Involves diverting the blocked ventricular CSF
• To another cavity for absorption
• Procedure
• Tube is surgically inserted in the ventricular
  cavity
• And use to divert CSF flow to the peritoneal
  cavity in the abdomen

53
Medical Diagnostic Procedures

• Lumbar Puncture or Spinal Tap
• Needle inserted into the lumbar subarachnoid
  space
• Between the fourth and fifth lumbar vertebrae
• Because spinal penetration at this point does not
  cause any injury to nerve fibers
• Attach needle hub to a manometer or other
  pressure sensitive device
• A pressure level higher than normal suggests that
  a pathologic process exists

54
Medical Diagnostic Procedures

• Catheter Insertion into the Lateral Ventricles
• Measure Ventricular pressure
• Increased intracranial pressure occurs in
  response to
• 1. Increased amounts of CSF
• 2. Brain swelling
• 3. And brain tumors

55
Medical Diagnostic Procedures

• Additional Procedures Associated with Spinal
  Puncture
• Procedure also used to draw out CSF for chemical
  or cell studies
• Diseases of the CNS change the constituent
  composition of the CSF
• An alteration serves as a diagnostic tool for
  identifying pathologic changes that occur in the
  brain and spinal cord
• May suggest acute bacterial meningitis
• Route used to inject drugs to combat infection or
  to induce anesthesia
• Anesthesia prevents nerve impulses from being
  conducted through the spinal nerves
• From the lower body up to the level of the spinal
  injection

56
Define the Following Technical Terms

• Arachnoid granulations
• Arachnoid trabecula
• Cerebrospinal fluid
• Choroid plexus
• Ependymal cells
• Intracranial pressure
• Lumbar Puncture

• Meninges
• Meningitis
• Septum
• Subarachnoid space
• Subdural space
• Ventricles

57
Review Questions

• 1. Discuss the function of the meningeal
  membranes of the brain and spinal cord.
• 2. Describe the location of epidural, subdural,
  and arachnoid spaces.
• 3. Name the dural extensions of the brain and
  describe their relationship to the brain.
• 4. With a labeled diagram, identify major parts
  of the ventricular system.
• 5. Discuss the functions of the cerebrospinal
  fluid.
• 6. Discuss the production, circulation, and
  absorption of the cerebrospinal fluid.
• 7. Describe the mechanism, clinical
  implications, and treatment of hydrocephalus.

58
The Meningesandthe Ventricular System

• Graphics

59
THINGS TO DO BEFORE LECTURE