Sphenoidal artery: review of the literature and analysis of a dissected arterially injected fetal orbit

Abstract

Purpose The sphenoidal artery is considered a component of the complex and dangerous arterial anastomoses of the human orbitocranial region, particularly with the advent of interventional neuroimaging. The objective of this publication was to analyze the various descriptions of the sphenoidal artery in the literature as related to relevant photographs of a dissected arterially injected fetal middle cranial fossa and orbit. Methods Publications dealing with middle meningeal-ophthalmic arterial anastomoses, focusing on the sphenoidal artery, were reviewed. A relevant dissection of a fetal specimen was analyzed. Results The literature dealing with the sphenoidal artery is at times not in agreement. The nomenclature and anatomy of its passage through the superior orbital fissure or Hyrtl canal have variable descriptions. Photographs of the skull base of a dissected arterially injected fetal specimen show bilateral prominent orbital branches of the middle meningeal arteries. These branches entered both orbits in a course similar to the diagrammatic representations of the sphenoidal artery, and give rise to several major intraorbital arteries. This study provides the only photographic image in the literature of this variation in a human fetal anatomic dissection. Conclusions Review of the literature dealing with the sphenoidal artery shows inconsistent nomenclature and conflicting descriptions of its anastomotic connections, and varying evolutionary and embryologic theories. Analysis of the dissected fetal skull base indicates that the sphenoidal artery is not a distinct artery but just a middle meningeal orbital arterial branch, an important component of the complex and dangerous arterial anastomoses of the human orbitocranial region.

Internal carotid supply to the parietal meninges: a comparative study based on cranio-orbital vascular traces in modern humans and Indonesian <i>Homo erectus</i>

“…In modern humans, the SOF and/or COF provide pathways for the ophthalmic or lacrimal meningeal branches or the orbital branches of the MMA (Diamond, 1991a). To avoid terminological confusion (Lasjaunias et al, 1975;Diamond, 1991a;Erdogmus and Govsa, 2005;Kier et al, 2021), in this study, the terms 'sphenoidal artery' and 'meningolacrimal artery' are used to refer to the orbital branch of the MMA via the SOF and the COF, respectively (Diamond, 1991a). The term RMA is used here to refer to the ophthalmic branch that enters the middle cranial fossa from the orbit via the SOF or the COF (Hayreh, 1962;Erdogmus and Govsa, 2005; for the different usage of this term, see Toma, 2016;Bonasia et al, 2020a).…”

“…The orbital branch of the MMA anastomoses with the RMA (Hayreh and Dass, 1962;Lasjaunias et al, 1975;Diamond, 1991a;Shimada et al, 1995;Bonasia et al, 2020aBonasia et al, , 2020bBonasia et al, , 2021, or instead of the ophthalmic arterial branches, it supplies blood to the orbital contents such as the lacrimal gland, extraocular muscles, and periorbital connective tissues and occasionally travels further to the anterior cranial fossa (Diamond, 1991a;Shimada et al, 1995;Bonasia et al, 2020a;Kier et al, 2021). Some cadaver dissection studies suggest that the orbital branch of the MMA often anastomoses with the RMA when it passes through the SOF, while it does less frequently when it passes through the COF in modern humans (Diamond, 1991a;Shimada et al, 1995;Perrini et al, 2007).…”

“…In this hypothesis, the persistent anastomosis between the MMA and the ophthalmic artery is explained by secondary connection, while the bregmatic branch of the MMA is considered the extraorbital part of the RMA annexed by the MMA; if this were true, the bregmatic branch would always arise near the orbit. However, the bregmatic branch often occurs at a point closer to the stem of the MMA and then runs anteriorly on the middle cranial fossa, even in fetal specimens (see also the 18-week fetus of Kier et al (2021)). Such a branching pattern would be more compatible with the generally accepted hypothesis that persistent anastomosis is the remnant of the stapedial's supraorbital ramus (Padget, 1948;Georgiou and Cassell, 1992), although identification of the twiggy artery that Müller (1977) described as the stapedial's vestige is also needed.…”