1. Blood supply of the nervous system

2. Objectives Describe the main 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. CEREBRAL ARTERIAL SUPPLY
It is composed of two arterial systems:
Carotid System
Vertebro Basilar System

4. Arteries of brain Two sources
Internal carotid artery: supplies anterior 2/3 of cerebral hemisphere and parts of diencephalon
Vertebral artery: supplies posterior 1/3 of cerebral hemisphere and parts of diencephalon, brain stem and cerebellum

5. Posterior cerebral artery
Vertebrobasilar System
Vertebral Artery
A branch of the first part of subclavian artery
Its course is divided into 4 parts
The 4th part enters the cranial cavity through the foramen magnum on the side the medulla
The two vertebral arteries approach each other and join together in the median plane at the lower border of the pons to form the basilar artery
Basilar artery
Formed by the union of the two vertebral arteries at the lower border of the pons
Ascends on the front of the pons lodged in the basilar groove
Ends at the upper border of the pons by dividing into 2 Posterior cerebral arteries (PCA)
Posterior cerebral artery
Basilar artery
Vertebral artery

6. Branches of the 4th part of vertebral artery
Anterior spinal artery
Posterior spinal artery
Medullary branches, to the antero-medial part of the medulla
Posterior inferior cerebellar artery, supplies the posterior part of the inferior surface of cerebellum.
It gives medullary branches to the postero-lateral part of the medulla, and a choroid branch
Posterior cerebral artery
Basilar artery
Superior cerebellar artery
Pontine branches
Labyrinthine artery
Vertebral artery
Anterior inferior
cerebellar artery
Anterior spinal artery
Posterior inferior
cerebellar artery
Posterior spinal artery

7. Basilar artery
Anterior inferior cerebellar arteries, supplies the anterior part of inferior surface of cerebellum
Labyrinthine artery, enters the internal acoustic meatus to supply the membranous labyrinth
Pontine branches, run transversely and supply the pons
Superior cerebellar arteries, supply the superior surface of cerebellum
2 Posterior cerebral arteries end divisions

8. Posterior cerebral artery Superior cerebellar artery
Choroid plexus of
lateral ventricle
Posterior cerebral artery
Superior cerebellar artery
Anterior choroid a
Pontine branches
Internal carotid a
Labyrinthine artery
Basilar artery
Anterior inferior
cerebellar artery
Posterior inferior
cerebellar artery
Anterior spinal artery
Posterior spinal artery
Vertebral artery

9. Posterior communicating a
Internal Carotid Artery
One of the two terminal branches of the common carotid artery
Reaches the cranial cavity by passing through the carotid canal
Terminates lateral to the optic chiasma by dividing into Anterior & Middle Cerebral Arteries
Terminal part of ICA
Anterior cerebral a
Optic chiasma
Middle cerebral a
Anterior choroid a
Posterior communicating a

10. Branches of internal carotid artery
Hypophyseal arteries, arise inside the cavernous sinus and supply the hypothalamus and neurohypophysis
Anterior choroidal artery, forms the choroid plexus of the lateral ventricle.
Posterior communicating artery, runs backwards to join the posterior cerebral artery
Ophthalmic artery, runs into the optic canal to the orbit
Terminal branches:
Anterior cerebral artery (ACA)
Middle cerebral artery (MCA)

11. Anterior communicating a Posterior communicating a
Anterior cerebral a
Anterior communicating a
Middle cerebral a
Anterior choroid a
Internal carotid a
Posterior communicating a
Posterior cerebral a
Choroid plexus
of lateral ventricle

12. Anterior communicating a
Circle of Willis
An arterial circle on the base of the brain
It joins the 2 arterial systems
It surrounds the optic chiasma in front of the cerebral peduncles
Anterior communicating a
Anterior cerebral a
Optic
chiasma
Internal
carotid a
Posterior
communicating a
Posterior
cerebral a
Basilar a

13. It is formed of:
2 Anterior cerebral arteries
2 Internal carotid arteries
2 Posterior cerebral arteries
2 Posterior communicating arteries
1 Anterior communicating artery

14. Branches: Perforating arteries (Anterior& Posterior):
Numerous small vessels that penetrate the surface of the brain through the anterior and posterior perforating substances.
APA supplies:
Large part of Basal Ganglia,
Optic chiasma,
Internal capsule & Hypothalamus
PPA supplies:
Ventral portion of Midbrain, parts of Subthalamus and Hypothalamus

15. Anterior Cerebral Artery (ACA)
Course
One of the two terminal branches of ICA
Takes origin lateral to the optic chiasma
Runs medially above the optic nerve to reach the longitudinal fissure
Continues on the medial surface of the cerebral hemisphere above the corpus callosum
Its proximal part is connected to its fellow of the opposite side by the anterior communicating artery
Terminates by turning upward in front of the parieto-occipital sulcus
Anterior Cerebral Artery (ACA)
Corpus callosum
Parieto-occipital
sulcus
Anterior cerebral a
Terminal part of ICA
Anterior cerebral a
Posterior cerebral a
Terminal part of ICA

16. Anterior perforated substance Rostrum of corpus callosum
Branches of ACA:
Central branches
Pass through the anterior perforated substance
Supply anterior part of hypothalamus, rostrum of corpus callosum, septum pellucidum, head of caudate nucleus, anterior part of lentiform nucleus & anterior half of anterior limb of internal capsule.
Callosal Branches
They supply all parts of the corpus callosum except the splenium (supplied by posterior cerebral artery)
Thalamus
Septum pellucidum
Anterior perforated substance
Optic chiasma
Rostrum of corpus callosum
Posterior cerebral a
Posterior perforated
substance
hypothalamus
Optic chiasma

17. Anterior cerebral artery
Genu of
corpus callosum
Head of caudate
nucleus
Lentiform
nucleus
Internal
capsule
Thalamus

18. superolateral surface
Cortical branches
The cortical branches are distributed to the following areas:
Medial surface as far back as the parieto-occipital sulcus
Upper inch of supero-lateral surface, in front of the parieto-occipital sulcus
Medial part of the orbital surface
Parieto-occipital
sulcus
Upper inch of
superolateral surface
Medial part of
orbital surface

19. Middle Cerebral Artery (MCA)
Course
One of the two terminal branches of ICA
Takes origin lateral to the optic chiasma
Runs laterally in the depth of the lateral sulcus
Terminates on the surface of insula by breaking into terminal branches
Insula
Lateral cerebral a
Anterior cerebral a
Middle cerebral a

20. Body of corpus callosum
Branches of MCA:
Central branches
Pass through the anterior perforated substance
They are called striate arteries, as they supply the corpus striatum ( lentiform nucleus, caudate nucleus) and internal capsule
NB. Occlusion of (or hemorrhage from) striate arteries leads to contralateral hemiplegia
Striate arteries
Corpus striatum
Cortical branches
of middle cerebral a
Middle cerebral a
Anterior cerebral a
Lateral ventricle
Septum pellucidum
Body of corpus callosum

21. The cortical branches are distributed to the following areas:
All the Supero-lateral surface, EXCEPT:
Upper inch (supplied by anterior cerebral artery)
Lower inch (supplied by posterior cerebral artery)
Occipital lobe (supplied by posterior cerebral a)
Lateral part of orbital surface
Temporal pole & insula
Area supplied by
anterior cerebral a.
Area supplied by
posterior cerebral a.

22. Posterior Cerebral Artery (PCA)
Course
One of the two terminal branches of basilar artery at the upper border of the pons
Runs backwards around the side of the cerebral peduncle of the midbrain
Reaches the medial surface of the occipital lobe, below the splenium of corpus callosum, where it divides into 2 terminal branches which run in the:
Calcarine sulcus
Parieto-occipital sulcus
Cerebral peduncle
Posterior cerebral a

23. Central branches: Differentiated into medial & lateral groups
The medial group pierce the posterior perforated substance, while the lateral group pierce the side of the cerebral peduncle
They supply the thalamus, hypothalamus, cerebral peduncles & geniculate bodies
Posterior choroidal branches (Medial & lateral)
-The medial posterior choroidal supplies the tectum of midbrain and choroid plexus of 3rd ventricle
-The lateral posterior choroid supplies the choroid plexus of lateral ventricle
ICA
Thalamus
Anterior choroid a
Hypothalamus
Choroid plexus
of lateral ventricle
Medial posterior
chroid a
Posterior cerebral a
Lateral posterior
choroid a

24. Cortical areas supplied by posterior cerebral a
Cortical branches
The cortical branches are distributed to the following areas:
Tentrorial surface (behind the temporal pole)
Lower inch of supero-lateral surface
All surfaces of the occipital lobe
Temporal
pole
Cortical areas supplied
by posterior cerebral a

25. Lateral surface Medial surface Cortical areas supplied by ACA
Cortical areas supplied by MCA
Cortical areas supplied by PCA

26. Summary of the arterial supply of the brain
Cortical Distribution of Cerebral Arteries
The Cerebral cortex is supplied by cortical branches of:
Anterior cerebral; all medial surface (except the occipital lobe), medial half of orbital surface and upper inch of lateral surface (in front of parieto-occipital sulcus)
Middle cerebral; all lateral surface (except the upper inch, lower inch and occipital lobe), lateral half of orbital surface, insula & temporal pole
Posterior cerebral; all surfaces of occipital lobe, tentorial surface (behind the temporal pole), lower inch of lateral surface

28. Internal capsule; supplied by central branches of:
MCA
ACA
Anterior choroidal artery (from Internal Carotid)
Corpus Striatum; supplied mainly by central (striate) branches of MCA
Thalamus; supplied mainly by central branches of PCA
Midbrain; supplied by:
PCA
Medial posterior choroidal (also from PCA)
Pons; mainly supplied by the Basilar artery and its pontine branches
Medulla Oblongata; supplied by medullary branches of:
Vertebral arteries
Posterior inferior cerebellar arteries.
Anterior & posterior spinal arteries
Cerebellum; supplied by the three pairs of cerebellar arteries:
Posterior Inferior Cerebellar, Anterior Inferior Cerebellar, Superior Cerebellar
Labyrinth; labyrinthine artery (from Basilar Artery)

29. Arterial Disorders Stroke: Aneurysm Angioma Sudden occlusion
Hemorrhage
Aneurysm
Angioma

30. Occlusion of ACA Manifestations:
1. Motor & sensory disturbances in the contralateral distal leg
2. Difficulty in the Prefrontal lobe functions:
Cognitive thinking, Judgment,
Motor initiation and Self monitoring

32. Occlusion of MCA Manifestations: 1. Contralateral weakness of:
Face, Arm & Hand (more than leg)
2.Contralateral sensory loss of:
3. Visual field cut (damage to optic radiation)
4. Aphasia (language disturbances )
Broca's: production
Wernicke's: comprehension

33. Occlusion of PCA Manifestations: 1. Visual disturbances
Contralateral homonymous hemianopia (visual field loss on the same side of both eyes)

34. Bilateral lesions: cortical blindness
Cortical blindness is the loss of vision due to damage to the visual portion of the occipital cortex in the brain.
(Anton Babinski`s syndrome)patients having cortical blindness but unaware they cannot see or insist that they can see
2. Memory impairment
If the temporal lobe is affected

35. Cerebral Venous Drainage
(A) Superficial (cortical) veins:
Found in the Subarchnoid space
Drain the cortical surfaces
(B) Deep veins:
Drain the deeper structures
These veins are thin walled and devoid of valves.
They ultimately drain into the Dural Venous Sinuses

36. Venous drainage of the cerebral hemisphere
Superior cerebral veins
Run on the lateral surface above the lateral fissure
Drain into the superior sagittal sinus and suprerficial middle cerebral vein
Inferior cerebral veins
Run on the lateral surface below the lateral fissure
Drain into the superficial middle cerebral vein and the transverse sinus
Superior sagittal sinus
Superior cerebral v
Superior anastomotic v
Superficial middle cerebral v
Inferiro anastomotic v
Inferior cerebral v

37. Superficial middle cerebral vein
Runs in the superficial part of the lateral sulcus
Its posterior end is connected to the superior sagittal sinus and transverse sinus by the superior and inferior anastomotic veins
Its anterior part curves medially to terminate in the cavernous sinus

38. Deep Cerebral Veins
Drain the internal structures (basal ganglia, internal capsule, thalamus)
They merge to form two Internal Cerebral Veins.
The two veins unite in the midline to form the Great Cerebral vein.
This short vessel is continuous with the Straight Sinus

39. Superficial middle cerebral v
Deep middle cerebral vein
Runs in the depth of the lateral sulcus
Terminates at the anterior perforated substance where it shares in the formation of the BASAL vein
Anterior cerebral vein
Runs on the medial surface with the anterior cerebral artery
Striate veins
Drain the corpus striatum
Emerges through the anterior perforated substance and joins the anterior cerebral vein and deep middle cerebral vein to form the BASAL vein
Anterior cerebral v
Deep middle cerebral v
Superficial middle cerebral v
Basal vein
Great cerebral v

40. Superficial middle cerebral v
Basal vein
Formed at the anterior perforated substance by the union of:
Anterior cerebral vein
Deep middle cerebral vein
Striate veins
Runs around the side of the midbrain to terminate in the GREAT CEREBRAL VEIN
Anterior cerebral v
Deep middle cerebral v
Superficial middle cerebral v
Basal vein
Great cerebral v

41. Internal cerebral vein
Thalamostriate vein
Runs in the groove between thalamus and caudate nucleus
Drains the thalamus, corpus striatum, internal capsule and septum pellucidum
Unites with the choroid veins (behind the interventricular foramen) to form the internal cerebral vein
Choroid veins
Drain the choroid plexuses of lateral and third ventricles
Unite with the thalamostriate veins to form the internal cerebral vein
Internal cerebral vein
Thalamostriate vein
Caudate nucleus
Choroid vein
Choroid plexus
of lateral ventricle
Basal vein
Great cerebral vein
Straight sinus

42. Internal cerebral vein Inferior sagittal sinus
Formed behind the interventricular foramen by the union of:
Thalamostriate vein
Choroid veins
Runs backwards and unites with its fellow of the opposite side to form the Great Cerebral Vein
Great cerebral vein
Formed by the union of the two Internal Cerebral Veins
It also receives the basal veins
Runs backwards and unites with the Inferior Sagittal Sinus to form the Straight Sinus
Internal cerebral vein
Great cerebral v
Inferior sagittal sinus
Internal cerebral v
Thalamostriate vein
Choroid vein
Choroid plexus
of lateral ventricle
Basal vein
Great cerebral vein
Basal v
Straight sinus
Straight sinus

43. Dural venous sinuses
The venous blood from the deep areas of the brain is collected into channels called the venous sinuses.
The dural venous sinuses of the brain are formed by layers of dura matter lined by endothelium. The main venous sinuses are :
1 superior sagittal sinus
1 inferior sagittal sinus
1 straight sinus
2 transverse sinus or lateral sinuses
2 sigmoid sinuses
The sigmoid sinuses situated close to the mastoid air sinuses continue as internal jugular veins

46. Dural sinus
Location
Receives
Superior sagittal
Superior border of falx cerebri
Superior cerebral, diploic, and emissary veins and CSF
Inferior sagittal
Inferior margin of falx cerebri
A few cerebral veins and veins from the falx cerebri
Straight
Junction of falx cerebri and tentorium cerebelli
Inferior sagittal sinus, great cerebral vein, posterior cerebral veins, superior cerebellar veins, and veins from the falx cerebri
Occipital
In falx cerebelli against occipital bone
Communicates inferiorly with vertebral plexus of veins
Confluence of sinuses
Dilated space at the internal occipital protuberance
Superior sagittal, straight, and occipital sinuses

47. Transverse (right and left)
Horizontal extensions from the confluence of sinuses along the posterior and lateral attachments of the tentorium cerebelli
Drainage from confluence of sinuses (right-transverse and usually superior sagittal sinuses; left-transverse and usually straight sinuses); also superior petrosal sinus, and inferior cerebral, cerebellar, diploic, and emissary veins
Sigmoid (right and left)
Continuation of transverse sinuses to internal jugular vein; groove parietal, temporal, and occipital bones
Transverse sinuses, and cerebral, cerebellar, diploic, and emissary veins
Cavernous (paired)
Lateral aspect of body of sphenoid
Cerebral and ophthalmic veins, and emissary veins from pterygoid plexus of veins and sphenoparietal sinuses

48. Superior petrosal (paired)
Superior margin of petrous part of temporal bone
Cavernous sinus, and cerebral and cerebellar veins
Inferior petrosal (paired)
Groove between petrous part of temporal bone and occipital bone ending in internal jugular vein
Cavernous sinus, cerebellar veins, and veins from the internal ear and brainstem
Basilar
Clivus, just posterior to sella turcica of sphenoid
Connect bilateral inferior petrosal sinuses and communicate with vertebral plexus of veins

49. Important structures related to cavernous sinus
The internal carotid artery and the sixth cranial nerve, which travel through it
In the lateral wall, the third and fourth cranial nerves, and the ophthalmic and maxillary divisions of the fifth cranial nerve.
The pituitary gland, which lies medially in the sella turcica
The veins of the face, which are connected with the cavernous sinus via the facial vein and inferior ophthalmic vein, and are an important route for the spread of infection from the face
The superior and inferior petrosal sinuses, which run along the upper and lower borders of the petrous part of the temporal bone

50. Dangerous area of the face
It is the area between the root of the nose and 2 angles of the mouth. - The veins in this region are connected to cavernous sinus through the facial vein so any infection in this area may lead to cavernous sinus thrombosis.

51. Venous Disorders Infarcation. Sinus thrombosis:
(SSS thrombosis) can complicate ear infection .
Cavernous S thrombosis (as a complication of infection in the dangerous area of the face)
Obstruction of venous drainage of the brain leads to Cerebral swelling (edema) and raised ICP

52. Arterial Supply of the Spinal Cord
The spinal cord is supplied by the anterior and posterior spinal arteries, in addition to the radicular arteries
Anterior spinal arteries
They arise from the 4th part of vertebral artery on each side
Arteries of both sides unite together forming a single anterior spinal artery
The anterior spinal artery descends in front of the anterior median fissure of the spinal cord
Posterior spinal arteries
They also arise from the 4th part of the vertebral artery on each side
Each artery divides into 2 branches
The 2 branches descend on each side of the dorsal roots of spinal nerves

54. Radicular arteries
Their origin varies according to the region through which the spinal cord descends
From above downwards, they arise from the following arteries:
Vertebral
Ascending cervical
Superior intercostal
Posterior intercostal
Subcostal
Upper lumbar
They pass through the intervertebral foramina and divide into ventral and dorsal branches

56. AICA = lateral inferior pontine
Anterior Cerebral Artery
-Loss of sensation and motor to lower limb
- Medial motor & somatosensory motor
Middle Cerebral Artery
-Loss of sensation and motor to upper limb and face
- Lateral motor & somatosens
Posterior Cerebral Artery =
Webers or Benedikts (red nucleus)
Lose CST: contra weakness
Lose CN 3: (Oculomotor-eyes down and out-ipsi
BENEDIKTS: Webers + Ataxia
Superior Cerebellar Artery = lateral superior pontine
-Sup Cerebellar Ped=output from cerebellum = Ataxia
Basilar Artery = locked in
Median Pontine Syndrome
*Only move eyes up & down
-CST & Facial Nucleus
-Abducens N & Pontine gaze enter
PICA =lateral medullary:Wallenberg
-Inf Cerebellar peduncle=Ataxia
-Trigeminal-Spinal tract & Nucl V=
pain/temp from face-ipsi
-STT=pain & temp from body-contra
-CN 10=Nucl Solitarius-no taste
-Desc symp fibers: Horner’s
AICA = lateral inferior pontine
-Middle Cerebellar Ped= ATAXIA, posture probl.
-CN 8-Vestibular Nuclei=vertigo
-Trigeminal-CN V Spinal Tract= lose pain & temp from face- ipsi
-STT= pain & temp from body contr
-Desc symp fibers: Horner’s
Vertebral Artery = lateral medullary
-same as PICA
Anterior Spinal Artery = medial medullary
-CST & ML/DL= contra
-CN 12-Hypoglossal=ipsi tongue deviation