Bony Tunnel Formation Associated with the Distal Segment of the Frontal Branch of the Middle Meningeal Artery

Abstract

The knowledge of certain anatomical variations is fundamental and any surgeon who operates without that knowledge may encounter difficulty during surgery. In this context, there is the middle meningeal artery (MMA) which also engenders considerable clinical interest due to its location. The MMA is predominantly periosteal, irrigating the bone and dura mater. It enters the floor of the middle cranial fossa through the foramen spinosum, travels laterally through a middle fossa bony ridge, and curves anteriorly over the upper-greater wing of the sphenoid where it divides into parietal and frontal branches at a variable point. Occasionally, the distal segment of the frontal branch may pass through a bony tunnel of variable size. To the best of our knowledge, there is no evidence in the current literature on the incidence of this rare bony tunnel. Therefore, we decided to investigate the incidence of this bony tunnel in 85 dry skulls of adults (both genders) belonging to the didactic collection of the Human Anatomy Laboratory of the Universidade de Santa Cruz do Sul, Brazil. All the skulls were examined bilaterally for the presence or absence of the bony tunnel associated with the distal segment of the frontal branch of the MMA. Of the 85 skulls analyzed, the bony tunnel was present on the right side in 1.18% and on the left side in 5.88% (p = 0.045). Thus, in the studied sample, there was a significant tendency for this bony tunnel to be formed on the left side.

The Middle Meningeal Artery: Branches, Dangerous Anastomoses, and Implications in Neurosurgery and Neuroendovascular Surgery

“…The anterior division of the MMA can become intraosseous by entering a bony canal (of ∼1-30 mm in length) near the sphenoid angle of the parietal bone sometimes accompanied by the sphenoparietal sinus. 2,27 This intraosseous segment of the anterior division of the MMA can be injured with fractures or craniotomies, which could precipitate the formation of pseudoaneurysms or dural arteriovenous fistulas (AVFs). 27 The anterior division of the MMA then divides into a (1) lateral branch that courses along the convexity and terminates as (A) falcine branches that anastomose with the anterior falcine branches of the OphA at the level of the superior sagittal sinus and (B) contralateral branches that cross the midline and anastomose with the contralateral MMA (Figure 6), and (2) medial branch (anterior division of MMA) that courses near the sphenoid ridge of the lesser sphenoid wing and SOF to anastomose with the meningolacrimal (recurrent meningeal branch the lacrimal artery) and sphenoidal branches of the OphA 2,10 (Figure 7).…”

“…2,27 This intraosseous segment of the anterior division of the MMA can be injured with fractures or craniotomies, which could precipitate the formation of pseudoaneurysms or dural arteriovenous fistulas (AVFs). 27 The anterior division of the MMA then divides into a (1) lateral branch that courses along the convexity and terminates as (A) falcine branches that anastomose with the anterior falcine branches of the OphA at the level of the superior sagittal sinus and (B) contralateral branches that cross the midline and anastomose with the contralateral MMA (Figure 6), and (2) medial branch (anterior division of MMA) that courses near the sphenoid ridge of the lesser sphenoid wing and SOF to anastomose with the meningolacrimal (recurrent meningeal branch the lacrimal artery) and sphenoidal branches of the OphA 2,10 (Figure 7). The posterior division of the MMA divides into (1) petrosquamosal and (2) parieto-occipital branches, which supply the dura over the posterolateral floor of the middle fossa, lateral tentorium, petrous ridge, dura over the confluence of the superior petrosal, transverse and sigmoid sinuses, parieto-temporo-occipital convexity, and walls of the superior sagittal sinus and falx.…”

“…Illustration of the MMA highlighting its main branches and anastomoses. The external carotid artery(27) branches into the superficial temporal artery(31) and maxillary artery(30), which in turn gives the MMA (1). After entering the skull base through the foramen spinosum, the main trunk of the MMA (1) gives the following branches: the cavernous artery (4) that anastomoses with the inferolarteral trunk (7) of the cavernous ICA(26), which connects with the recurrent branch of the ophthalmic artery(24); the petrosal artery (5) that anastomoses with the APhA (8) and tentorial arteries (25) of the meningohypophyseal trunk; and the superior tympanic branch (6) that anastomoses into the middle ear with the inferior tympanic artery (9) of the APhA (8), the caroticotympanic (10) artery from the ICA, and with the posterior tympanic artery(11) from the posterior auricular artery(29).…”