Post on 16-Dec-2015
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
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.
Path of CSF Circulation Pathway:
Flows from the lateral ventricles into the third ventricle Via Monro’s 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 Magendie’s 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
Clinical Considerations Rate of CSF Production
Disassociation between Production and Absorption Rate of the CSF
Medical Diagnostic Procedures Measurement of the pressure of the fluid
If abnormally high, may suspect: Intracranial tumor Intracranial hemorrhage Hydrocephalus Meningitis Encephalitis
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
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
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
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
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
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.