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Carotid Canal

canalis caroticus

The carotid canal is a bony channel in the petrous part of the temporal bone that transmits the internal carotid artery and the carotid sympathetic plexus from the base of the skull at the external opening (on the inferior petrous surface) through an S-shaped course that first ascends then turns anteromedially to open into the foramen lacerum and the cavernous sinus. The canal is approximately 10 mm wide and is lined by a venous plexus and sympathetic fibres.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The carotid canal is the site of internal carotid artery dissection when longitudinal temporal bone fractures extend into this canal, producing traumatic carotid-cavernous fistula, arterial pseudoaneurysm, and thromboembolism causing stroke. The perisinus sympathetic plexus in the carotid canal is disrupted by ICA dissection, producing a postganglionic Horner syndrome without anhidrosis. Aberrant carotid arteries, where the ICA courses medially into the middle ear through an incomplete carotid canal, can be mistaken for a middle ear mass.

Pathology

Common Injuries & Conditions

Traumatic Carotid-Cavernous Fistula from Petrous Fracture

Longitudinal temporal bone fracture through the carotid canal lacerates the ICA, creating an arteriovenous fistula between the carotid and the adjacent cavernous sinus, producing pulsating proptosis, chemosis, and an orbital bruit treated by endovascular coiling or covered stent placement.

Aberrant Internal Carotid Artery

A developmental anomaly where the ICA courses through an incomplete carotid canal and enters the middle ear appears as a pulsatile reddish retrotympanic mass on otoscopy, mimicking a glomus tumour; recognition before any biopsy attempt prevents catastrophic haemorrhage.