1 / 23

Thinking questions

Ventricular System, Meninges, and CSF Study suggestion: Read the selected pages from Chapter 2 first, then read Chapter 8. Thinking questions. How to pack something very fragile that has to be shipped cross-country

bailey
Télécharger la présentation

Thinking questions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ventricular System, Meninges, and CSFStudy suggestion: Read the selected pages from Chapter 2 first, then read Chapter 8

  2. Thinking questions • How to pack something very fragile that has to be shipped cross-country • How to make a person who is heavy into a person who can be lifted with one hand

  3. Overview of this lecture, so you see the big picture • CNS is very fragile and vulnerable, and it is constantly being transported around • Cushion from ___________ and ___________ • Encase the whole thing in _______________ • CNS would collapse under its own weight if placed on a table. Brain’s weight is reduced from 1500g (3.3 lbs)  75 g (1/10 of a lb.) because it is ___________ in __________

  4. Introduction to CSF • Cerebrospinal Fluid (CSF) • Colorless • Continuously produced deep within internal brain spaces called ___________, and cushions around whole CNS ______________ • Functions • Mechanical cushion around CNS • Removal of harmful substances & waste

  5. CSF CIRCULATION: Where does it start? Produced in ventricles*, and flows caudally through ventricular system • Two lateral ventricles • Interventricularforamen • One third ventricle • Cerebral aqueduct • One fourth ventricle • Two foramina of Luschka • One foramen of Magendie * CSF produced by choroid plexus in the ventricular cavities

  6. Can you find the structures mentioned in the previous slide on these figures?

  7. So, CSF exits the ventricular system • Exits from 4th ventricle through • Two foramina on lateral sides of fourth ventricle = __________________ • One foramen in posterior part of fourth ventricle = foramen of ___________________ • Enters into a space called _____________ that encircles/covers whole CNS!

  8. More about subarachnoid space • Net-line structure within the SAS is called arachnoid trabeculae • Large pockets/enlargements of SAS are called _______________________ • Do you see the arachnoid trabeculae? Do you see any cisterns? • Lumbar puncture (spinal tap) from lumbar cistern

  9. Subarachnoid space is sandwiched between two of the three covering layers over the CNS • These three layers are called the MENINGES. • ??? How is this related to meningitis?

  10. Outer covering of brain:Where are the meninges? • (Scalp) • (Muscles and surface arteries) • (Bone: Skull) • Meninges • Cover brain and spinal cord • 3 layers • Between two of the layers is a cushioning layer of fluid called cerebrospinal fluid

  11. Meninges • Three-layer covering of CNS, from outermost to innermost • Dura mater (outermost, tough, DURable) • has 2 fused, closely united sub-layers • One next to bone • One next to arachnoid mater • 2 layers separate in spots to form venous sinuses • Arachnoid mater + subarachnoid space (below it): • Pia mater (innermost, “tender” fragile) • Three layers continuous: brain & spinal cord

  12. Meninges cover all of the CNS, including spinal cord

  13. Dura mater: More details • In certain places, the two layers separate to form dural venous sinuses (system of cavities and channels to drain venous blood) • Rigid sheets of dura mater extend into cranial vault (Fig. 3-11 in W&A) • Falxcerebri • flat, crescent-shaped • separates two cerebral hemispheres • Tentoriumcerebelli • dome-shaped • separates cerebral hemispheres from cerebellum • Diagphragmasella (not pictured) • Roof of structure that encloses pituitary gland

  14. Do you see where the dural venous sinuses are?

  15. Coronal section: More details on dura mater • Look at falxcerebri and tentoriumcerebelli • Folds of dura mater • Brace brain from displacement • Receive blood from brain’s cerebral veins • Receive cerebrospinal fluid from subarachnoid space

  16. Subarachnoid space (SAS): More details • Sub-arachnoid space filled with cerebrospinal fluid (CSF) • Extends into sulci (p. 63 of W) • Larger portions of this space called cisterns (Figure 3-9) • Arachnoid protrudes into dural venous sinuses • Protrusions = arachnoidvilli • CSF absorbed into blood + removed from SAS

  17. Pia mater: More details • Adheres tightly to surface of brain • Outer surface has many blood vessels • Many blood vessels cross the space between the pia and the arachnoid maters

  18. Circulation of CSF: Lateral view

  19. Clinical applications related to CSF • Blockage of CSF movement or failure of resorbtion mechanism  accumulation of fluid in ventricles or around brain tissue  hydrocephalus • Treated by shunting CSF from ventricle to body peritoneal or pleural cavities • Medical diagnostics on CSF • CSF pressure (high pressure associated with tumor, hemorrhage, hydrocephalus, meningitis or encephalitis) • CSF chemical and cell studies

  20. Clinical application related to meninges Extracerebral hemorrhages • Hemorrhages from the blood vessels in the meninges or on the surface of the brain, from: • Weakness of vessel wall • Traumatic injury • (rarely)-extreme fluctuations in blood pressure • Types, based on where blood accumulates • Subarachnoid: b/w arachnoid and pia (most common, from • aneurysm • arteriovenous malformation (AVM) • Subdural: under dura (esp. from TBI) • Epidural: b/w dura and skull (esp. from TBI) • After bleeding stops, left with hematoma

  21. Clinical application: Extracerebralhemorrhages (cont.) • Types, based on where blood accumulates • Subarachnoid: b/w arachnoid and pia (most common, from • aneurysm • arteriovenous malformation (AVM) • Subdural: under dura (esp. from TBI) • Epidural: b/w dura and skull (esp. from TBI) • After bleeding stops, left with hematoma

More Related