Kin 411 Lecture 23: Vascular Supply

Label A-I

Two main sources of blood supply to brain?

1. Internal Carotid (anterior brain)

2. Vertebral-basilar (posterior brain)

What does the common carotid artery divided into?

External carotid artery

Internal Carotid

What does the external carotid artery supply?

Outside of the head (face, scalp)

What does internal carotid artery supply?

Brain (anterior circulation)

Two main branches of the internal carotid artery?

Anterior Cerebral Artery (ACA)

Middle Cerebral Artery (MCA)

ACA vs MCA: What general area do they supply?

ACA: Medial surface of the brain

MCA: Lateral surface of the brain

Difference in left and right common carotid artery

Left: Common carotid comes right off the aorta

Right: Common carotid comes off a small branch of the aorta called Brachiocephalic artery

Through what structures do vertebral arteries travel?

Foramina transversaria of cervical vertebrae

What is Basilar artery? what arises from it?

Bilateral vertebral arteries join to form Basilar artery.
Basilar artery gives rise to Posterior Cerebral Artery (PCA)

Which arteries are part of anterior circulation vs posterior circulation?

Anterior circulation: ACA and MCA

Posterior circulation: PCA and Basilar system

Summary of cerebral blood supply

Internal carotids supply anterior brain (ACA, MCA), while vertebral arteries join to form basilar supply, which give rise to PCA that supplies the posterior brain

Vertebral artery path summary path

Subclavian artery → bilateral vertebral artery thru foramina transversaria → join + enter skull via foramen magnum → basilar artery → PCA

Carotid system path summary

Aorta splits → Common carotid → enters skull via carotid foramen → internal carotid = brain, external carotid= face

Label

Circle of Willis

Reflects connections between different cerebral arteries and the communicating arteries

Where are the cerebral arteries traveling?

Once ACA, MCA and PCA branch off, they enter into the sub-arachnoid space (CSF filled space under arachnoid mater and above pia mater)
There they run into smaller arteries and feed all the cortical areas of the brain

ACA blood supply

ACA supplies superior and medial cortex:

• from frontal lobes to anterior parietal lobes

MCA path

Comes off the internal carotid artery → Goes out laterally into the sylvian fissure

Posterior Cerebral Artery blood supply

PCA supplies:

Inferior and medial temporal lobe and occipital lobe

Basilar artery gives rise to PCA → Goes into interhemispheric fissure → running along the midline, but goes to the posterior parts of the brain

Label A-C

A- Anterior Cerebral Artery (ACA): goes up interhemispheric fissure

B- Internal Carotid Artery

C- Basilar Artery: Goes up interhemispheric fissure along the midline to PCA → posterior brain

Label

Blue: ACA

Pink: PCA

MCA: Yellow

ACA:

Medial surface of cortex as well as strip of superior cortex

From frontal lobe → anterior parietal lobe

PCA:

Inferior + medial temporal lobe, posterior parietal lobe, occipital lobe

MCA divisions

3 divisions:

1. MCA Superior division:

Emerge from Sylvian fissure → wraps UP → cover lateral frontal lobe to anterior parietal lobe

2. MCA Inferior Division:

Emerge from Sylvian fissure → wraps DOWN → anterolateral (superior) surface of temporal lobe and posterior parietal cortex

3. MCA Deep Branch:

To deep nuclei within center of brain (body of caudate + lentiform nucleus)

Describe MCA supply in the lateral view

Superior MCA: Lateral surface of cortex anterior frontal lobe to anterior parietal lobe

Inferior MCA: Anterolateral (Superior surface) of temporal lobe

What does MCA superior division supply?

• Lateral frontal lobe

• Anterior parietal lobe

What does MCA inferior division supply?

• Superior (anterolateral) temporal lobe

• Posterior parietal cortex

Through what fissure does MCA travel?

Sylvia fissure

Memory trick for MCA blood supply?

MCA = Most of the lateral cortex

What structures do MCA deep division supply?

• body of caudate

• Lentiform nucleus (GPi + putamen)

What do deep branches of the PCA supply?

Thalamus

What do the major sinuses do? Describe the path

Allow the venous blood to drain out of head and back into circulatory system

Superior saggital sinus runs along the superior part of interhemispheric fissure. Enters into interhemispheric fissure into the falx cerebri.

Superior drains into transverse sinus (made by tentorium cerebelli)

From Transverse sinus it drains out internal jugular vein and into the circulatory system

Vascular injury types

Blockages/occlusion of arteries: blood not flowing becuase blocked

Hemorrhage: artery is burst or torn open

Vascular injury: Hemorrhage

• Associated with ruptured aneurism (weakening of arterial wall)

• Arterial blood spills out into subarachnoid space for subarachnoid hematoma

Vascular injury: Blockage/occlusion

2 different mechanisms:

1. Thrombus: blood clot forms within arteries around artherosclerotic clot. Narrows/prevent flow of blood thru artery

2. Embolism: blockage by lodged material (embolus) within the vessel. Embolus is blood clot that has formed somewhere else in the circulatory system and becomes a plug in that artery

What dictates symptoms of vascular injury?

Depends on where the block or bleed occurs

e.g. block ACA → superior + medial frontal lobe and anterior parietal cortex = UMN for feet and legs probs