Sphenoidal artery, ramus orbitalis persistens and pterygospinosus muscle--a unique cooccurrence of first branchial arch anomalies in man.

In a 76-year-old Caucasian male, the right middle meningeal was replaced by a branch of the ipsilateral ophthalmic artery (O), i.e. the sphenoidal artery (S); the right foramen spinosum was found to be absent. In the orbit, the right O bifurcated into a medial (merely orbital) and a lateral division, i.e. a meningolacrimal trunk. From that trunk, the S branched off and entered the middle cranial fossa at the superolateral angle of the superior orbital fissure. In addition, an anastomotic channel was formed by a remnant of the ramus orbitalis, connecting the right infraorbital with the deep orbital artery. The right accessory meningeal (AM) regularly arose from the maxillary artery and entered the cranial cavity through the foramen ovale, separated from the mandibular nerve by a pterygospinosus muscle. This muscle was merely present in the right infratemporal fossa. Interestingly, the left AM originated from the posterior deep temporal artery. No other anatomical variations were found in this individual. Since the coexistence of an S with variations of other structures derived from the first branchial arch has not been previously reported in man, the embryology and comparative anatomy of this irregular vessel are discussed.