Head and Neck Arterial Supply
Overview
The head and neck receive their arterial supply primarily from two bilateral systems: the carotid arteries (anterior circulation) and the vertebral arteries (posterior circulation). These systems anastomose intracranially to form the Circle of Willis, providing crucial collateral perfusion.
The Carotid System
Common and Internal Carotid Arteries
The Common Carotid Artery (CCA) bifurcates at the level of the upper border of the thyroid cartilage (C3-C4). On the right, it arises from the brachiocephalic trunk; on the left, directly from the aortic arch.
- Internal Carotid Artery (ICA): Has NO branches in the neck. Enters the skull via the carotid canal. Supplies the anterior two-thirds of the cerebral hemispheres, eyes, and forehead.
- External Carotid Artery (ECA): Supplies the face, scalp, and meninges. Eight principal branches (mnemonic: S.A.L.F.O.P.M.S): Superior thyroid, Ascending pharyngeal, Lingual, Facial, Occipital, Posterior auricular, Maxillary, Superficial temporal.
The Vertebrobasilar System
The vertebral arteries arise from the first part of the subclavian arteries and ascend through the transverse foramina of C6-C1. They unite at the lower border of the pons to form the Basilar Artery, which terminates by splitting into the posterior cerebral arteries.
WarningCarotid Stenosis: High Yield Etiology
Atherosclerosis preferentially affects the carotid bifurcation. Emboli from this site are a leading cause of hemispheric TIAs and MCA territory infarcts. NASCET criteria: >70% stenosis in symptomatic patients warrants carotid endarterectomy.
High Yield Facts
LightbulbFRCR / MD Prep Pearl
The ICA lies posterolateral to the ECA at the bifurcation. The ophthalmic artery is the first major intracranial branch of the ICA. Dominant hemisphere stroke from a PCA territory lesion implies vertebrobasilar, not carotid, disease.