1. Blood Supply of the CNS

2. Lecture Objectives Describe the four arteries supplying the CNS.
Follow up each artery to its destination.
Describe the circle of Willis and its branches.
Discuss the principle of end artery type of circulation.
Describe venous drainage of the brain.

3. Vertebral Artery Branch of the 1st part of the subclavian a.
Ascends the neck through the upper sex transverse vertebrae
Inters the skull through foramen magnum
Both sides unit to form the basilar a.

4. Vertebral Artery Branches Meningeal aa. Anterior spinal a.
Posterior spinal aa.
Posterior inferior cerebellar a. (PICA)
Medullary aa.

5. Basilar Artery Ascend in front of pons
Participate in forming circle of Willis
Branches
Anterior inferior cerebellar aa. (AICA)
Pontine aa.
Superior cerebellar aa.
Posterior cerebral aa. (end branches)
Inferior & posterior parts of cerebrum

6. Blood Supply to Cortex Circle of Willis

7. Blood Supply to Cortex Vascular Territories

8. Blood Supply to Cortex Vascular Territories

9. Blood Supply to Cortex Vascular Territories

10. Blood Supply to Deep Structures

11. Internal Carotid Artery
Ophthalmic a.
Posterior communicating a.
Anterior choroidal a.
Anterior cerebral a.
Middle cerebral a.

12. Middle Cerebral Artery
Language areas (left MCA in most people)
Motor & somatosensory cortex (except- lower limb & perineum)
Auditory cortex
Lenticulostriate arteries- basal gangila & internal capsule (genu)

13. Middle Cerebral Artery

14. Middle Cerebral Artery

15. Anterior Choroidal Artery
Hippocampus, uncus & amygdala
Choroid plexus (temporal horn of lateral ventricle
Globus pallidus, putamen, part of thalamus
Internal capsule (posterior limb)

16. Anterior Choroidal Artery

17. Anterior Cerebral Artery
Motor & somatosensory cortex (lower limb & perineum)
Corpus callosum (except- splenium)
Olfactory bulb & tract
Recurrent artery of Heubner
Head of caudate (ventral part) and adjacent putamen
Internal capsule (anterior limb)

18. Anterior Cerebral Artery

19. Posterior Cerebral Artery
Hippocampus
Parahippocampal gyrus
Calcarine branch- all primary & some association cortex for vision
Posterior choroidal artery
Choroid plexus (lateral & 3rd ventricles)
Thalamus (posterior part)
Fornix
Tectum

20. Posterior Cerebral Artery

21. Blood Supply to SC One anterior spinal a.
Vertebral aa.
Two posterior spinal aa.
Vertebral aa. 25%
PICA 75%
Anterior & posterior radicular aa.
Arise at every spinal level
Serve their respective roots & ganglia

22. Blood Supply to SC Anterior & posterior spinal medullary aa.
Arise at intermittent levels
Serve to augment the BS to SC
Artery of Adamkierwicz
Unusually large spinal medullary a.
Usually on the left
In low thoracic or upper lumber levels

23. Blood Supply to SC Spinal cord Ischemia Anterior spinal a.
Small & tenuous
Occlusion produces bilateral damage (below lesion)
Affects
Corticospinal tracts
Paraplegia below lesion
Spinothalamic tracts
Thermoanesthesia and analgesia
Descending autonomic tracts
Loss of bladder & bowel control
Anterior gray horn
Near enlargement – weakness of limb muscles

24. Veins of the Brain Superior cerebral veins → SSS
Superficial middle cerebral veins → cavernous sinus Deep middle cerebral vein
Anterior cerebral basal vein Striate veins
Thalamostriate vein Choroid vein
Internal cerebral vein
Great cerebral vein
↓ straight sinus
External cerebral veins
Internal cerebral veins

25. Veins of the Brain

26. Veins of the Brain

27. Dural Venous Sinuses Location Drains ….. Fate
Superior sagittal sinus
Venous lacunae
Inferior sagittal sinus
Straight sinus
Occipital sinus
Transverse sinus
Sigmoid sinus
Cavernous sinuses
Superior and inferior petrosal sinuses

28. Dural Venous Sinuses

29. Blood Brain Barrier protects cells from some toxins and pathogens
proteins & antibiotics can not pass but alcohol & anesthetics do
Structure
tight junctions seal together epithelial cells
continuous basement membrane
astrocyte processes covering capillaries

30. Blood Brain Barrier Areas without BBB Structure
Area postrema in the floor of the fourth ventricle
Areas in the hypothalamus
Structure
Endothelial fenestrations

31. Blood Cerebrospinal Fluid Barrier
Structure
Endothelial cells
BM of endothelial cells
Pale cells
BM of choroidal epithelial cells
Tight junctions seal the choroidal epithelial cells