A large, pulsating vessel was found passing through the crura of the stapes, consistent with a persistent stapedial artery (PSA) (figure 2).
Prevalence of facial canal dehiscence and of persistent stapedial artery in the human middle ear: A report of 1000 temporal bones.
Initially the network is supplied by the stapedial artery
and later by the external carotid artery.
The stapedial artery
lay nearly perpendicular to the course of the facial nerve (88-93 [degrees]C).
For example, a study validating the involvement of the stapedial artery
as the impetus that causes facial malformations characterized as hemifacial microsomia would have already been previously presented due to the number of reports published by Poswillo's group in the sixties and seventies that discussed the same theory.
The stapedial artery
originates as a dorsal branch of the second aortic arch and is part of the carotid arterial system (Fisher; Greig).
Later the stapedial artery
develops from the dorsal aspect of the second arch artery and passes through the condensed mesenchymal site of the future ring of stapes to anastamose with the ventral pharyngeal artery thereby annexing its terminal distribution.
Otoscopic findings were normal in all cases, which ruled out middle ear pathology such as a retrotympanic lesion (e.g., a glomus tumor or persistent stapedial artery
(1,3) It has been postulated that factors that contribute to facial nerve canal dehiscence include heredity, inhibition of proper canal wall formation, and a persistent stapedial artery
This most common area of dehiscence is probably secondary to the failure of ossification after the stapedial artery
(which passes through this area) resorbs prior to birth.
A jugular-bulb anomaly is sometimes associated with a persistent stapedial artery
and a diverticulum of the jugular bulb that protrudes into the hypotympanum.
This explanation is supported by the association of the lateralized carotid artery with a persistent stapedial artery
[5,6] and with a fibrous band at the site of the artery.