Part 1: Brain Blood Supply – The Anatomy Behind the Magic! 🧠

Today we’re exploring the vascular anatomy of the brain—because the brain may run the show, but without blood, it’s lights out! 💡 

Here’s some basics

Arterial Supply: The Brain's Lifeline 🚰

The brain relies on two key arterial systems:

🔹 Internal Carotid Arteries (ICA):

Branch into the anterior cerebral artery (ACA) and middle cerebral artery (MCA).

• ACA: Supplies the medial frontal and parietal lobes, anterior corpus callosum, and motor/sensory areas for the lower limbs.
• MCA: Supplies the lateral brain surface (face/arm motor areas) and language centres (Broca’s and Wernicke’s).

Clinical relevance: Understanding which areas the MCA supplies helps clinicians identify stroke symptoms—like aphasia or arm/face weakness—before imaging results are available.

🔹 Vertebral Arteries:

Join to form the basilar artery, which then branches into the posterior cerebral arteries (PCA).

PCA: Supplies the occipital lobe (vision), inferior temporal lobe (memory areas), and parts of the thalamus and midbrain.

Clinical relevance: PCA strokes often cause visual field deficits, which may be the only clue to posterior circulation involvement in an acute presentation.

🎯 The Circle of Willis: Built-In Backup System

This arterial ring at the base of the brain connects the ICA and vertebrobasilar systems, providing collateral flow if one path is compromised. Its key components:

• 🧠Anterior communicating artery: Links both ACAs.
• 🧠Posterior communicating arteries: Link the ICAs to the PCAs.

🌐 Real-World Relevance:

In patients with significant carotid artery disease, a complete Circle of Willis can maintain brain perfusion and reduce stroke risk. However, about 50% of people have incomplete or variant circles, affecting this protective mechanism.

💧 Venous Drainage: The Brain's Waste Removal Team

Superficial veins: Drain cortical blood into the superior sagittal sinus and other dural venous sinuses.

Deep veins: Drain subcortical areas via the great cerebral vein of Galen into the straight sinus.

Final path: Blood leaves through the internal jugular veins.

🧠 Clinical Relevance:

The brain relies on venous outflow to maintain intracranial pressure. Dural venous sinus thrombosis (DVST) can cause raised ICP, leading to headaches, vision changes, and seizures—particularly in young adults or pregnant patients

❓ Anatomical Quiz: Test Your Knowledge!

A patient has a stroke affecting the medial surface of the left frontal and parietal lobes, causing right leg weakness and sensory loss.

Which artery is most likely involved?

A) Middle cerebral artery

B) Anterior cerebral artery

C) Posterior cerebral artery

D) Basilar artery

💡 Drop your answers below!

Think about which arterial territory is responsible for lower limb motor and sensory function.

Remember this is just the basics, focus on your lab work and try and think three dimensionally in this intricate and vitally important system

Stay tuned for Part 2 tomorrow, where we connect these anatomical pathways to real-world clinical signs and stroke syndromes!  🔍