Timothy C. Hain, MD Page last modified: February 9, 2017
Schematic of circulation of inner ear, from Schuknecht's Pathology of the Ear. (Merchant and Nadol, 2010)
Most of the blood supplied to the inner ear begins with the labyrinthine artery, which is generally a branch of the anterior inferior cerebellar artery (AICA). The labyrinthine artery enters the internal auditory canal but divides into two branches shortly after entering into the canal, the common cochlear artery and the anterior vestibular artery. The common cochlear artery then again splits into the spiral modiolar artery, confusingly called the cochlear artery above, and the vestibulocochlear artery.
Contrary to this general design and somewhat neglected, the endolymphatic sac is supplied by the occipital artery, which is a branch of the external carotid artery.
Illustration of the blood supply to the cochlea by Konaschko (1927)
The spiral modiolar artery supplies about 80% of the cochlea. The vestibulocochlear artery supplies the other 20%.
The cochlea does not have a redundant vascular supply. Brief periods of blood loss in the labyrinthine artery result in deafness.
The implication of the vascular supply of the sac being from the occipital artery is unclear. One might reasonably hypothesize that one could have ischemia or a "stroke" of the endolymphatic sac, due to vascular disease in the external carotid or occipital artery. When there is vasodilation of the occipital artery, such as from migraine, it would seem possible that this might alter blood supply in the endolymphatic sac.