1. Brain Sinuses Venous channels found between layers of dura mater
They carry oxygen-depleted blood
They are not real veins – possess no muscular coat but lined with endothelium

2. Venous Blood Flow
Veins of brain  Sinuses  Internal Jugular Vein  Brachiocephalic Vein  Superior Vena Cava  Right Atrium
See Figure 21.24

3. Not real veins – tunnels through membranes
Dural venous sinuses. Sagittal section of the skull, showing the sinuses of the dura. The dural venous sinuses (also called dural sinuses, cerebral sinuses, or cranial sinuses) are venous channels found between layers of dura mater in the brain.
 in human anatomy, any of the channels of a branching complex sinus network that lies between layers of the dura mater, the outermost covering of the brain, and functions to collect oxygen-depleted blood. Unlike veins, these sinuses possess no muscular coat. Their lining is endothelium, a layer of cells like that which forms the surface of the innermost coat of the veins. The sinuses receive blood from the veins of the brain and connect directly or ultimately with the internal jugular vein. Blood from the sinuses, after it leaves the internal jugular vein, flows through the brachiocephalic vein and the superior vena cava to the upper right chamber (atrium) of the heart.

4. Blood-Brain Barrier Metabolically active Ischemia Diabetes Protection
2% weight
20% O2 & Glucose
Ischemia
Diabetes
Protection
Cilia – CSF
Semi-permeable

5. Blood-Brain Barrier Can Pass Cannot Pass
Glucose (via transport proteins)
Lipid-soluble substances
 O2, CO2, alcohol, anesthetics
Large molecules ex. Proteins
Most antibiotic drugs
Trauma, inflammation and certain toxins can break down the BBB

6. Cerebrospinal Fluid Produced from arterial blood 80-150 mL
Circulates in subarachnoid space, ventricles, sulci and spinal cord

8. Fig 14.3
Brain Ventricles

9. Functions of CSF The brain “floats” in the cranial cavity.
Mechanical protection – cushion / shock absorbing medium
Homeostatic function –pulmonary ventilation and cerebral blood flow affected by pH of CSF.
Circulation – minor exchange of nutrients & waste
Blood-CSF barrier

10. Formation of CSF Ventricles Choroid Plexuses Ependymal cells
Figure 14.3

11. Choroid (Arachnoid) Villi
Fig 14.4

12. Choroid (Arachnoid) Villi

13. Circulation of CSF Refer to Figure 14.4

14. Anatomy of the brain: The Cerebrospinal Fluid CSF
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AWFUL commentary but good visual. Talk over the video

15. Brainstem

16. Medulla Oblongata Most inf  foramen magnum  pons Medial Leminscal
Spinothalamic tracts
Corticospinal tracts
Pyramids
Decussation of pyramids
Nuclei

17. Sensory Pathways

18. Medulla Oblongata

19. Medulla Oblongata Nucleus  collection of neuronal cell bodies in CNS
Nuclei of origin for cranial nerves VIII, IX, X, XI, XII

20. Reticular Formation (RAS)
Network of nerves  monitors ingoing / outgoing sensory/motor impulses.
Level of consciousness
Reticular Formation (RAS)
Most influential part
RAS = reticular activating system

21. Pons
Nuclei of origin for cranial nerves V, VI, VII and VIII

22. Pons
Apneustic – promotes inspiration by stimulating nerves in M.O. Controls intensity.
Pneumotaxic – Antagonistic. Inhibits inhalation. Regulates rate of respiration.