Vasculature of the Brain

Why Brain Blood Supply Matters

• The brain represents only 2% of body weight but consumes about 20% of the body's energy, primarily in the form of oxygen and glucose.
• Proper blood supply is critical to prevent neurological deficits, ischemia, or stroke

Overview of Presentation:

• - Major arteries (ICA and vertebrobasilar systems)
• - Circle of Willis
• - Clinical significance (stroke, TIAs, etc.)

Systemic Circuit: Branches of the Aorta

• L & R coronary arteries 

• Brachiocephalic trunk 

• left common carotid artery 

• left subclavian artery 

what comes off of Brachiocephalic trunk?

• right subclavian artery

  • to right arm 

• right common carotid artery

  • to right side of head and brain

Arteries of the head, neck, and brain

• aortic arch

• brachiocephalic artery (right side only)

• left common carotid

• subclavian 

what is apart of internal carotid (comes off L & R common carotid)?

• middle cerebral 

• circle of willis 

• anterior cerebral artery 

what comes of subclavian?

• vertebral 

  • basilar

  • posterior cerebral artries 

  • circle of willis 

what is Carotid System (Anterior Circulation) origin?

common carotid arteries

what is main branches Carotid System (Anterior Circulation)?

Internal Carotid Arteries (ICA)

what is the origin of Vertebrobasilar System (Posterior Circulation) ?

Vertebral arteries
• which merge to form the Basilar artery

what is supplies of Vertebrobasilar System (Posterior Circulation)?

Brainstem, cerebellum, occipital lobes

what is the course of the ICA?

Travels through the carotid canal in the skull, entering the brain to supply anterior circulation

what are key branches internal carotid artery system?

• Anterior Cerebral Artery (ACA): Medial surfaces of the frontal and parietal lobes.
• Middle Cerebral Artery (MCA): Largest branch, lateral surfaces of the brain

where is the anterior cerebral artery (ACA)?

Medial surfaces of the frontal and parietal lobes

where is Middle Cerebral Artery (MCA)?

Largest branch, lateral surfaces of the brain

what are other branches internal carotid artery system?

• anterior choroidal artery 

• posterior communicating artery

what are the arteries for the Vertebrobasilar System (Posterior Circulation)?

• vertebral arteries 

• basilar artery 

• branches 

  • posterior inferior cerebellar artery (PICA) 

  • anterior inferior cerebellar artery (AICA) 

  • superior cerebellar artery (SCA) 

  • posterior cerebral arteries (PCA) 

where does the vertebral arteries originate?

from the subclavian arteries

where does the vertebral arteries ascend?

ascend through the transverse foramina of the cervical vertebrae

what forms the basilar artery?

Formed by the union of the two vertebral arteries.

what does the basilar artery supply?

Supplies the brainstem and cerebellum.

what are the branches of the Vertebrobasilar System (Posterior Circulation)?

• posterior inferior cerebellar artery (PICA) P1-P5

• anterior Inferior Cerebellar artery (AICA)

• Superior cerebellar artery (SCA)

• Posterior Cerebral arteries (PCA)

the circle of willis definition

A circular network of arteries\ located at the base of the brain, linking the anterior and posterior circulations.

what is the importance of the circle of willis?

provides collateral circulation in case of arterial blockage

anterior components of the circle of willis

• The Anterior Cerebral Artery and Posterior Communicating arteries branch off the Internal Carotid Artery

• R&L Anterior Cerebral Arteries (ACA):

• Anterior Communicating Artery (AComm)

  • connects the two ACAs

what is the posterior components of the circle of willis ?

• R&L Posterior Cerebral Arteries (PCA): Arise from the basilar artery

• Posterior Communicating Arteries (PComm)

  • connect the ICA to the PCA

Mapping Cerebral Arteries to Brain Lobes:

• anterior cerebral artery (ACA) 

• Middle cerebral Artery (MCA) 

• posterior cerebral artery (PCA) 

where is anterior cerebral artery (ACA) located?

Medial frontal and parietal lobes.

where is the middle cerebral artery (MCA)

Lateral frontal, temporal, parietal, and parts of the occipital lobes.

where is the posterior cerebral artery (PCA) located?

Occipital lobes, posterior temporal lobes, brainstem

what is course and anatomy of anterior cerebral artery (ACA)?

Travels along the longitudinal fissure, supplying the medial surfaces of the frontal and parietal lobes

what are the areas supplied by superficial cortical branches?

• frontal lobe 

• medial motor cortex (contralateral lower limbs) 

• medial somatosensory cortex (contralateral lower limb sensation) 

what is part of frontal lobe?

• prefrontal cortex (decision-making, personality) 

• olfactory cortex (smell) 

Areas Supplied by Deep Branches:

• basal ganglia 

• hypothalamus 

Middle Cerebral Artery (MCA) course and anatomy

• Largest Cerebral Artery:

• Extends laterally, running through the Sylvian fissure

• Example of Deep Branch = Lenticostriate

Areas Supplied by Superficial Cortical Branches in the middle cerebral artery (MCA)

• Lateral surfaces of the frontal, temporal, parietal, occipital lobes and Insula

  • primary motor and sensory areas for the face, arm, and trunk

  • Expressive (Broca’s) and Receptive (Wernicke’s) Aphasia

what is the clinical note for MCA?

MCA is the artery most often involved in ischemic strokes.

Posterior Cerebral Artery (PCA) course and anatomy

• Arises from the basilar artery
• supplies posterior regions of the brain

what areas does the PCA supply?

• occipital lobes 

• hippocampus 

• midbrain 

• thalamus 

what is the occipital lobe?

• Visual deficits, e.g. Hemianopia

•  Calcarine Artery supplies Primary Visual Area

• Parieto-occipital Artery supplies Sup. Occip. and Post. Parietal lobes

  • Visual Attention

what is hippocmapus?

• in posterior & inferior temporal lobes 

  • memory loss

where is the midbrain?

cerebral peduncles (CST & CBT)

what is the thalamus?

contralateral sensory loss

what is the clinical note for PCA?

Occlusion of the PCA can result in visual deficits (e.g., hemianopia).

Small branches off the ICA supplyblood locally to

some deep brain areas and cranial nerves

what are the Small branches off the ICA supplyblood locally to some deep brain areas and cranial nerves:

• Internal Capsule

• CNs II, III, IV, V1 and V2
  • Motor Eye
  • Sensory face + vision

Supply areas of the cerebral arteries. A: axial slice; B: coronal slice. (1) Anterior cerebral artery, (2) middle cerebral artery, (3) posterior cerebral artery, (4) anterior choroidal artery, (5) lenticulostriate arteries.

what Branches off the ICA?

• anterior choroidal artery 

• posterior communicating artery 

what does the anterior choroidal artery supply?

• internal capsule

• basal ganglia

• optic tract

what does the internal capsule control?

sensory and motor deficits

what is the basal ganglia also supplied by?

Also supplied by deep branches of the ACA and MCA

what does the PCA supply?

• hypothalamus

• optic chiasm 

what is the Branches off the Basilar Artery?

• posterior inferior cerebellar 

• pontine 

• superior cerebellar 

• posterior communicating artery 

what are the Branches off the Vertebral/Basilar Artery

• posterior inferior cerebellar (P1)

• anterior inferior cerebellar (AICA)

• pontine 

• superior cerebellar 

• posterior spinal arteries

• anterior spinal artery

• spinal arteries

• also connected to the systemic circulation

what is the posterior inferior cerebellar (P1) ?

• Off the vertebral artery

• Supplies lower cerebellum

• Lateral Caudal Medulla

  • Motor & Cardiovascular problems

• Dizzy, Headache, Vomiting, Balance

• Wallenberg Syndrome

• Horner’s Syndrome

what are symptoms of posterior inferior cerebellar (P1)?

dizzy, headache, vomiting, balance

what syndromes are associated with posterior inferior cerebellar (P1)?

• wallenberg syndrome 

• horner’s syndrome 

what is anterior inferior cerebellar (AICA)?

• Posterior & Lateral Pons
• Lateral Pontine Syndrome:
• Vestibular Nuclei – dizziness
• Cochlear Nucleus – deafness
• Trigeminal Nucleus – sensory face & motor mastication

what is lateral pontine syndrome?

• Vestibular Nuclei – dizziness

• Cochlear Nucleus – deafness

• Trigeminal Nucleus – sensory face & motor mastication

what is pontine?

anterior pons 

what does superior cerebellar supply?

• supplies upper cerebellum 

  • ataxia, balance, dizziness 

what are the posterior spinal arteries?

• posterior medulla

  • cun. + grac. Nuclei 

• dorsal SPC 

  • dorsal columns 

what are the anterior spinal artery?

• anterior medulla 

  • pyramidal decussation

• anterior SPC

  • motor deficits

what is part of venous drainage?

• superficial venous drainage

• deep venous drainage

• all eventually exits through internal jugular vein 

what is superfiical venous drainage ?

• The superficial veins of the brain drain the cortex and empty into dural venous sinuses, particularly the superior sagittal sinus.
• Other major sinuses include the transverse sinus and sigmoid sinus

what is deep venous drainage?

Drain structures within the brain, such as the basal ganglia and the thalamus

what are major structures of the deep venous drainage?

• great cerebral vein (of Galen)
• straight sinus
• inferior sagittal sinus

what is blood brain barrier?

• Highly selective permeability barrier that separates circulating blood from the brain's extracellular fluid
• It protects the brain from harmful substances but also complicates drug delivery to the CNS

what are components of the blood brain barrier?

• Tight junctions between endothelial cells restrict passage of substances.

• Astrocyte foot processes surround the capillaries, contributing to the barrier’s strength.

• Only small, lipid-soluble molecules, and certain transportable substances can pass through

what is circumventricular organs (CVOs) for the blood brain barrier ?

• Eight brain structures that lack a blood-brain barrier and are located near the midline, associated with the ventricular system

• These organs detect blood-borne compounds or secrete neurosecretory products into the blood to regulate the internal environment

what is an example of CVOs?

Area postrema triggers vomiting in response to blood-borne chemicals

what is Cerebrospinal fluid (CSF)?

fills the ventricles and subarachnoid space, bathing the brain's external surface

what is CSF production?

• Produced by choroid plexus

• Removed through Arachnoid Villi

  • Protrusions into the dural sinuses

• Approximately 500 mL per day; excess fluid is eliminated through venous drainage in dural sinuses

what does the choroid plexus produce?

CSF production

what removes CSF production?

arachnoid villi

what is functions of Ventricular System & CSF?

• buoyancy

• excretion

• chemical communication

what is buoyancy?

Cushions the brain, reducing pressure on delicate tissues and protecting against physical shocks

what is excretion?

• Removes waste and regulates the CNS chemical environment since the brain lacks a lymphatic system.

  • CSF aids in waste and excess neurotransmitter removal via the blood–CSF barrier in the choroid plexus

what is chemical communication?

CSF allows neurochemicals released by neurons to spread and influence adjacent neural tissue

what are the 2 types of stroke?

1. ischemic stroke 

2. hemorrhagic stroke

what causes ischemic stroke?

Caused by a blockage (e.g., thrombus or embolism)
• MCA, ACA, PCA & Basilar

what causes Hemorrhagic stroke?

Caused by bleeding (e.g., aneurysm rupture or trauma)
• Circle of Willis and Deep Arteries

Importance of Understanding Arteries:

• Each artery supplies specific brain areas
• Symptoms vary based on the affected artery

Basal Ganglia Stroke

ACA Stroke

MCA Stroke

PCA Stroke

• Different strokes affect distinct brain areas depending on the artery involved.
• Early recognition of symptoms is crucial for timely intervention.
• Understanding the arteries helps predict outcomes and guide treatment.

Conclusion