Blood Supply Fall 2012 General Concepts Internal Carotid Artery Vertebral Artery Circle of Willis Fall 2012

Cerebral Blood Flow Central nervous system 2% of body by weight 15% of all cardiac output 20% of all O2 consumed Total brain blood volume every 5-7/min Loss of consciousness after 10 sec Necrosis after 4-5 min of hypoxia

Cerebral Blood Flow Arterial supply to brain and much of spinal cord derived from 2 sets of arteries Internal carotid arteries Anterior circulation - 80% of blood supply Vertebral arteries Posterior circulation - 20% of blood supply Linear extent of capillaries/Unit volume Gray matter > White matter Sensory, interneurons > Motor

Internal Carotid Artery Common Carotid Artery Off Brachiocephalic Trunk – Right Off Arch of Aorta - Left Subclavian Artery

Normally at superior border of thyroid cartilage = C4 vertebra Carotid Bifurcation <1% 4% 12% 30% 35% 12% 5% 1% Normally at superior border of thyroid cartilage = C4 vertebra

Ophthalmic Artery Optic Nerve Ophthalmic Artery ICA

ICA Branches Anterior Cerebral A. Middle Cerebral A. ICA Post. Comm. Artery Anterior Choroidal Artery

ICA Branches Anterior Cerebral Artery Ophthalmic Artery ICA Middle Cerebral Artery Anterior Choroidal Artery Posterior Communicating Artery

Anterior Choroidal Artery AChA = yellow

Anterior Cerebral Artery Communicating Artery ACA

(Recurrent A. of Heubner) Anterior Cerebral Artery Anterior Communicating Artery Medial Striate Artery (Recurrent A. of Heubner) ACA

Anterior Cerebral Artery ACA

Anterior Cerebral Artery Frontopolar branches Internal frontal branches Paracentral branches Internal parietal branches

Anterior Cerebral Artery ACA = pink

Middle Cerebral Artery ACA Middle Cerebral A. M1 segment

Middle Cerebral Artery Subdivisions

Middle Cerebral Artery Medial Striate Artery Lateral Striate As. M1 ACA

Middle Cerebral Artery Post. Parietal A. Ant. Parietal A. Central A. Precentral A. Frontal A. Orbital A. MCA, sup. trunk Angular A. MCA Temporal As. MCA, inf. trunk

Middle Cerebral Artery MCA = green

Vertebral Artery Variants Left off arch of aorta 4% Left dominant 60% Right hypoplastic 10% Left hypoplastic 5% Left atretic, no communication with basilar 3% Right atretic, no communication with basilar 2% Subclavian Artery

Vertebral Artery C1 C2 C3 1% 2% 5% 90% C4 C5 C6 C7 T1

Vertebral Artery

Vertebral Artery Basilar Artery Vertebral Artery PICA Anterior Spinal Artery PICA

Vertebral Artery Basilar Artery Vertebral Artery Posterior Spinal Artery (25%) Anterior Spinal Artery

Vertebral Artery Basilar Artery PICA Vertebral Artery Posterior Spinal Artery (75%) Anterior Spinal Artery

Spinal Arteries

Spinal Arteries

Spinal Arteries Artery of Adamkiewicz

PICA Basilar Artery PICA

Basilar Artery - Branches Pontine Arteries Basilar Artery AICA Labyrinthine Artery

Basilar Artery - Branches Posterior Communicating Artery Posterior Cerebral Artery CN III Superior Cerebellar Artery

Basilar Artery - Branches Posterior Communicating Artery Posterior Cerebral Artery CN III Superior Cerebellar Artery

Basilar Artery - Branches Posterior Cerebral Artery CN III Basilar Artery Superior Cerebellar Artery CN VI

Cerebellar Arteries

Posterior Cerebral Artery

Posterior Cerebral Artery Parieto-occipital Artery Calcarine Artery PCA

Posterior Cerebral Artery PCA = blue

Circle of Willis Anterior Communicating Artery Anterior Cerebral Artery Internal Carotid Artery Posterior Communicating Artery Posterior Cerebral Artery Basilar Artery

Circle of Willis Anterior Communicating Artery Anterior Cerebral Artery Internal Carotid Artery Posterior Communicating Artery Posterior Cerebral Artery Basilar Artery

Circle of Willis Anterior Communicating Artery Superior Hypophyseal Artery Anterior Cerebral Artery Internal Carotid Artery Posterior Communicating Artery Inferior Hypophyseal Artery Posterior Cerebral Artery

Circle of Willis Variations 10% 10% 10% 60% complete 10% 10% 10%

Watershed Zones

Venous Dural Sinuses Inferior Sagittal Superior Sagittal Sphenoparietal Straight Inferior Petrosal Confluens Occipital Transverse Sigmoid

Venous Dural Sinuses Superior Sagittal Sinus Inferior Sagittal Sinus Occipital Sinus Straight Sinus

Venous Dural Sinuses Superior Ophthalmic Vein Sphenoparietal Cavernous Superior Petrosal Inferior Petrosal Sigmoid Straight Superior Sagittal Transverse

Medulla Blood Supplies

Caudal Medulla PSA / PICA ASA / VA ASA

Rostral Medulla PICA PSA / PICA ASA / VA

Pons Blood Supplies

Caudal Pons BA / AICA BA

Rostral Pons SCA BA / SCA BA

Midbrain Blood Supplies

Caudal Midbrain SCA / PCA BA / SCA

Rostral Midbrain PCA PCA PCA PCoA Ant Ch A