Cerebro-vascular Anatomy and Collateral Pathways

Comprehensive vocabulary flashcards covering the anatomy of the aortic arch, carotid and vertebral arteries, intracranial circulation, and major collateral pathways.

Aortic Arch

Originates from the left ventricle of the heart, ascends in the thorax, and forms a curve in the superior mediastinum above the left main bronchus before descending.

Brachiocephalic trunk

Also known as the innominate artery, it is the first branch of the arch of aorta and divides into the right common carotid artery and right subclavian artery.

Left common carotid artery

The second branch of the aortic arch, originating slightly to the left of the innominate artery; it is usually longer than the right common carotid artery.

Left subclavian artery

The third and last branch of the aortic arch, which gives rise to the left vertebral artery as its first branch.

Anatomic Variants of the Arch

Variations occurring in approximately 30% of cases, with the most common being the left common carotid artery arising from the innominate artery (approximately 10%).

Common Carotid Artery (CCA)

Arteries that ascend anterolaterally in the neck, measuring between $6\,mm$ – $8\,mm$ in diameter, and bifurcate at the superior border of the thyroid cartilage ($C4$).

Carotid Bulb

A dilation at the origin of the ICA and ECA that includes the distal CCA, proximal ICA, and proximal ECA.

External Carotid Artery (ECA)

The smaller branch of the CCA located antero-medial to the ICA, supplying high-resistance vascular areas such as the face, neck, and scalp.

Superior thyroid Artery

The first branch of the ECA, most commonly visualized during carotid duplex imaging and used as a landmark to identify the ECA.

Superficial Temporal Artery

A branch of the ECA used to differentiate it from the ICA via the temporal tapping maneuver during duplex imaging.

Internal Carotid Artery (ICA)

The larger branch of the CCA, measuring $5\,mm$ – $6\,mm$ in diameter, which lays postero-lateral to the ECA and provides no branches in the neck.

Carotid Canal

The opening in the petrous part of the temporal bone through which the ICA enters the cranium.

Vertebral Arteries (VA)

The first branches of the subclavian arteries that ascend through the transverse foramina of cervical vertebrae and enter the skull via the foramen magnum.

Basilar Artery

An artery formed by the union of the right and left vertebral arteries that provides blood supply to the posterior part of the brain.

Carotid Siphon

The S-shaped curve the ICA makes at the base of the brain after entering the cranium.

Ophthalmic Artery

The first branch of the intracranial ICA, arising at the carotid siphon and supplying the peri-orbital circulation.

Circle of Willis

A polygon-shaped vascular ring at the base of the brain described by Thomas Willis in 1664; the complete classic version is present in only 20% to 25% of cases.

Middle Cerebral Artery (MCA)

The larger terminal branch of the ICA that extends laterally and horizontally to supply the middle part of the brain.

Anterior Cerebral Artery (ACA)

The smaller terminal branch of the ICA that courses antero-medial to supply the anterior part of the brain.

Anterior Communicating Artery (ACoA)

A short branch connecting the anterior cerebral arteries that provides collateral circulation between the right and left hemispheres.

Posterior Communicating Artery (PCoA)

Bilateral arteries that course posterior and medial to join the posterior cerebral artery, providing collateral between the anterior and posterior circulation.

Extracranial-Intracranial Collateral Pathway

A collateral system between the ophthalmic artery branches and ECA branches via the orbit.