OBJECTIVEThe first attempt to cannulate the foramen ovale is oftentimes unsuccessful and requires subsequent reattempts, thereby increasing the risk of an adverse event and radiation exposure to the patient and surgeon. Failure in cannulation may be attributable to variation in soft-tissue–based landmarks used for needle guidance. Also, the incongruity between guiding marks on the face and bony landmarks visible on fluoroscopic images may also complicate cannulation. Therefore, the object of this study was to assess the location of the foramen ovale by way of bony landmarks, exclusive of soft-tissue guidance.METHODSA total of 817 foramina ovalia (411 left-sided, 406 right-sided) from cranial base images of 424 dry crania were included in the study. The centroid point of each foramen ovale was identified. A sagittal plane through the posterior-most molar (molar plane) and a coronal plane passing through the articular eminences of the temporal bones (inter-eminence plane) were superimposed on images. The distances of the planes from the centroids of the foramina were measured. Also, counts were taken to assess how often the planes and their intersections crossed the boundary of the foramen ovale.RESULTSThe average distance between the molar plane and the centroid of the foramen was 1.53 ± 1.24 mm (mean ± SD). The average distance between the inter-eminence plane and the centroid was 1.69 ± 1.49 mm. The molar and inter-eminence planes crossed through the foramen ovale boundary 83.7% (684/817) and 81.6% (667/817) of the time, respectively. The molar and inter-eminence planes passed through the boundary of the foramen together 73.5% (302/411) of the time. The molar and inter-eminence planes intersected within the boundary of the foramen half of the time (49.4%; 404/817).CONCLUSIONSThe results of this study provide a novel means of identifying the location of the foramen ovale. Unlike the soft-tissue landmarks used in the many variations of the route of Härtel, the bony landmarks identified in this study can be palpated, marked on the face, appreciated fluoroscopically, and do not require any measurement from soft-tissue structures. Utilizing the molar and inter-eminence planes as cannulation guides will improve the approach to the foramen ovale and decrease the amount of radiation exposure to both the patient and surgeon.

Cribra orbitalia is a phenomenon with interdisciplinary interest. However, the etiology of cribra orbitalia remains unclear. Recently, the appearance of cribra orbitalia was identified as vascular in nature. This study assessed the relationship between anatomical variation of vasculature, as determined by the presence of meningo‐orbital foramina, and the presence of cribra orbitalia in 178 orbits. Cribra orbitalia was identified in 27.5% (49:178) of orbits (22.7%, 35:154 adult orbits and 58.3%, 14:24 subadult orbits) and meningo‐orbital foramina were identified in 65.8% (100:152) of orbits. Among the 150 total intact adult orbits (i.e., orbital roof and posterior orbits both intact), cribra orbitalia was found in 35 (23.3%). Of these 35 occurrences of cribra orbitalia, 32 (91.4%) had the concurrent finding of a meningo‐orbital foramen. However, in the absence of the meningo‐orbital foramen, cribra orbitalia was only found in three sides out of the total sample of intact orbits (3:150; 2.0%). Fisher's exact test revealed that the presence of cribra orbitalia and the meningo‐orbital foramen were statistically dependent variables (p = .0002). Visual evidence corroborated statistical findings—vascular impressions joined cribra orbitalia to meningo‐orbital foramina. This study identifies that individuals who possess a meningo‐orbital foramen are anatomically predisposed to developing cribra orbitalia. Conversely, cribra orbitalia is unlikely to occur in an individual who does not possess a meningo‐orbital foramen. Thus, the antecedent of cribra orbitalia is both vascular and developmental in nature. This report represents an important advancement in the understanding of cribra orbitalia—there is an anatomical predisposition to the development of cribra orbitalia.

The brachial plexus is responsible for the innervation to the upper limb. The musculocutaneous and median nerves are terminal branches off the brachial plexus. The musculocutaneous nerve supplies motor innervation to anterior flexor muscles of the arm. The median nerve provides motor innervation to most flexor muscles of the forearm, pronator muscles of the forearm and passes through the carpal tunnel to innervate certain muscles of the hand. In the absence of the musculocutaneous nerve, the median nerve typically supplies the musculature of the anterior flexor compartment of the arm, including: biceps brachii muscle, brachialis muscle and at times the corocobrachialis muscle. In the case of a high median nerve injury, a variation of an absent musculocutaneous nerve may not only result in typical palsy of the forearm and hand, but also experience palsy in the arm. Therefore, understanding the prevalence and anatomical characteristics of the absence of the musculocutaneous nerve is clinically important. Among 44 brachial plexuses from 22 cadavers assessed, an absent musculocutaneous nerve was observed in 4 plexuses (9.1%) among 3 (13.6%) cadavers. A single female cadaver revealed a bilateral absence of the musculocutaneous nerves in comparison to one female cadaver showing a right unilateral absence of the musculocutaneous nerve and one male demonstrating a left unilateral absence of the musculocutaneous nerve. In all cases, the median nerve supplied both the biceps brachii and brachialis muscles. In summary, a systematic review of the absence of the musculocutaneous nerve demonstrated that females are under‐represented, relative to males and a unilateral absence of the musculocutaneous nerve in a female should be considered a particularly rare finding.Support or Funding InformationWV Research Challenge Fund [HEPC.dsr.17.06]This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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Trigeminal neuralgia, a debilitating pain disorder affecting the trigeminal nerve distribution, is often treated through percutaneous procedures using the route of Härtel. Miscannulation and excessive attempts at traversing the foramen ovale can negatively affect surgical outcomes. Complications attributed to miscannulation include blindness, brainstem hematoma, temporal lobe hematoma, and carotid artery hemorrhage. Currently, there is disagreement regarding the best skin entry point for the percutaneous approach. However, identifying an optimum entry point for cannulation can decrease the number of attempts necessary for a successful cannulation and also decrease the amount of fluoroscopic radiation exposure for both the patient and the surgeon. Therefore, this cadaveric study assessed a total of 56 cadavers to identify the optimum skin entry point. Calvariae, brains, and trigeminal nerves were removed, and the foramina ovalae were exposed. A lumbar needle was inserted through each porous trigeminus and foramen ovale at varied angles. The cannulation procedure was “reversed” by inserting the needle from the interior of the cranium through the porous trigeminus, foramen ovale, and skin. The exit location of the needle relative to facial structures was assessed. The exit points from the facial skin, which would otherwise represent the optimal entry points for the percutaneous procedure, were recorded. The results of this study represent an improvement in the percutaneous approach for the management of trigeminal neuralgia.