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Hakuba's triangle is a superior cavernous sinus triangle that allows for wide and relatively safe exposure of vascular and neoplastic lesions. This study provides cadaveric measurements of the borders of Hakuba's triangle and describes its neurovascular contents in order to enrich the available literature. The anatomical borders of the Hakuba's triangle (lateral, medial, and posterior borders) were defined based on Hakuba's description and identified. Then the triangle was dissected to reveal its morphology and relationship with adjacent neurovascular structures in Embalmed Caucasian cadaveric specimens. The oculomotor nerve occupied roughly one-third of the area of the triangle and the nerve was more or less parallel to its medial border. The mean lengths of the lateral border, posterior border, and medial border were 17 mm ± 0.5 mm, 12.2 mm ± 0.4 mm, and 10.6 mm ± 0.4 mm, respectively. The mean area of Hakuba's triangle was 63.9 mm 2  ± 4.4 mm 2 . In this study, we provided cadaveric measurements of the borders of Hakuba's triangle along with descriptions of its neurovascular contents., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The blood supply to the skull base is important to surgeons and those performing interventional and diagnostic procedures in this region. However, 1 vessel with a vast distribution in this area, the dorsal meningeal artery (DMA), has had few anatomic studies performed to investigate not only its normal anatomy but also its variations. Therefore the current study aimed to analyze the DMA via cadaveric dissection., Methods: In 10 adults, latex-injected, cadaveric heads (20 sides), the DMA was dissected using a surgical microscope. This artery and its branches were documented and measured., Results: A DMA was identified on all sides. In the majority (85%), it was a branch of the meningohypophysial trunk or common stem with either the inferior hypophysial or tentorial arteries and always had branches that traversed the basilar venous plexus. Multiple branches of the DMA were identified and categorized as bony, dural, neural, and vascular., Conclusions: Surgeons operating at the skull base or clinicians interpreting imaging of this area should have a good working knowledge of the DMA and its typical and variant anatomy., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: The anatomical characteristics of the anterior ethmoidal artery (AEA) exhibit a high degree of variability, especially regarding its topography. Methods: PubMed, Scopus, Embase, Web of Science, Cochrane Library, and Google Scholar were searched to identify all studies that included information regarding the morphometric and topographical characteristics of the AEA. Results: Ultimately, a compilation of 38 studies meeting the predetermined criteria, and possessing comprehensive and pertinent data, were incorporated into the current meta-analysis. In the overall analysis, reports of the AEA being embedded within the skull base or at the level of the skull base producing a bony protrusion were found in 56.91% of cases (95% CI: 43.55–69.80%). The mean diameters of the AEA in the intraorbital and intracranial areas were 0.94 mm and 0.76 mm, respectively. Moreover, the artery coursed most commonly between the second and third lamellae, with a prevalence of 65.82% (95% CI: 55.39–75.56%). Conclusions: The AEA may be at a high risk of iatrogenic injury during various sinus and skull base surgeries, especially if the surgeon performing these procedures is unfamiliar with the vast number of variations this vessel may exhibit. The spatial relationship between this vessel and the skull base is especially variable, and understanding this variability goes hand in hand with intraoperative safety. [ABSTRACT FROM AUTHOR]

Background: This meta-analysis aimed to present data on the sella turcica (ST) morphology and variations. Furthermore, a detailed morphometric analysis of the ST was conducted. Methods: Major online databases such as PubMed, Scopus, Embase, Web of Science, and the Cochrane Library were searched through. The overall search process was conducted in three stages. Results: This meta-analysis was based on the results of 18,364 patients and demonstrates the most up-to-date and relevant data regarding the morphology of the ST in the available literature. Four classification methods of the ST shape can be distinguished, in which the most commonly occurring variants are the normal ST (55.56%), the U-shaped ST (73.58%), the circular type of ST (42.29%), and non-bridging ST (55.64%). The overall midpoint height of the ST was 6.59 mm (SE = 0.13). The overall length of the ST was 9.06 mm (SE = 0.15). The overall volume of the ST was 845.80 mm3 (SE = 288.92). Four main classification methods of ST morphology can be distinguished in the available literature. Various morphometric characteristics of the ST may be applied in clinical practice to evaluate its shape, dimensions, and normal or pathological variants. [ABSTRACT FROM AUTHOR]

The present study aims to provide detailed observations on the cavernous segment of the abducens nerve (AN), emphasizing anatomical variations and the relationships between the nerve and the internal carotid plexus. A total of 60 sides underwent gross-anatomical study. Five specimens of the AN were stained using Sihler's method. An additional five specimens were subjected to histological examination. Four types of AN course were observed: a single nerve along its entire course, duplication of the nerve, division into separate rootlets at the point of contact with the cavernous part of the internal carotid artery (ICA), and early-branching before entering the orbit. Due to the relationships between the ICA and internal carotid plexus, the cavernous segment of the AN can be subdivided into a carotid portion located at the point of contact with the posterior vertical segment of the cavernous ICA and a prefissural portion. The carotid portion of the cavernous AN segment is a place of angulation, where the nerve always directly adheres to the ICA. The prefissural portion of the AN, in turn, is the primary site of fiber exchange between the internal carotid plexus and either the AN or the lateral wall of the cavernous sinus. [ABSTRACT FROM AUTHOR]

The inferomedial triangle is one of the two surgical triangles in the paraclival subregion of the skull base. It is delineated by the posterior clinoid process, the dural entrance of the trochlear nerve and the dural entrance of the abducens nerve. The aim of the present article is to describe the anatomical variations within the inferomedial triangle. Measurements of the triangle's borders and area were supplemented by detailed observations of the topographical anatomy and various arrangements of its contents. Nine adult cadaveric heads (18 sides) and 28 sagittal head sections were studied. The mean area of the inferomedial triangle was estimated to be 60.7 mm2. The mean lengths of its medial, lateral and superior borders were 16.1 mm, 11.9 mm and 10.4 mm, respectively. The dorsal meningeal artery was identified within the inferomedial triangle in 37 out of 46 sides (80.4%). A well-developed petrosphenoidal ligament of Grüber was identified within the triangle on 36 sides (78.3%). Although some structures were variable, the constant contents of the inferomedial triangle were the posterior petroclinoid dural fold, the upper end of the petroclival suture, the gulfar segment of the abducens nerve and the posterior genu of the intracavernous internal carotid artery. [ABSTRACT FROM AUTHOR]

Reports of a duplicated or fenestrated inferior petrosal sinus (IPS) are scarce or not found in the literature, respectively. To our knowledge, there are no cadaveric reports of the latter. This study used 20 adult cadaveric heads (40 sides). After removal of the brain, the IPS was dissected using a surgical microscope. Specimens with duplication or fenestration of the IPS anywhere along its course were photographed and measured. On 2 (5%) left sides, a fenestration was identified in the IPS. One of these was found to have 2 fenestrations. The mean length and width of the 3 fenestrations were 2.3 mm and 0.95 mm, respectively. The 3 fenestrations were located at the middle to terminal parts of the IPS. On 2 (5%) left sides and 1 (2.5%) right side, the IPS was duplicated over a part of its course. The mean length and width of the duplicated parts of the IPS were 25.9 mm and 3.1 mm, respectively. No statistical significance was found for fenestrations or duplications comparing males versus females, but fenestrations were statistically significant (P < 0.05) for occurring on left sides. Unfamiliarity with a duplicated or fenestrated IPS could increase risk of iatrogenic injury and misinterpretation of imaging. Further radiological imaging studies are required to substantiate more accurately the mechanisms by which a duplicated or fenestrated IPS affects clinical outcomes. Nonetheless, anatomical awareness of such lesser known variations of the IPS is crucial for promoting safe and effective interventional approaches at the skull base. [ABSTRACT FROM AUTHOR]

The intermediate condylar canal, which lies lateral to the occipital condyles and medial to the jugular foramen, is rarely mentioned in textbooks, even those devoted to the skull base. Therefore the present anatomic study was performed to better elucidate these structures. We studied 100 adult skulls (200 sides) to better understand the prevalence and anatomy of the intermediate condylar canal. An intermediate canal was found on 6 of 200 sides (3%). On average, these canals traveled 7.1 mm lateral to the occipital condyle and had a mean of 2.2 mm posteromedial to the jugular foramen. Anteriorly, these canals opened into the external surface of the hypoglossal canal and, when present, were just medial to a paracondylar process for which there was a strong positive correlation. The length of the canals ranged from 5 to 7.8 mm. In all, there were 3 partial canals and 3 complete canals. One left canal communicated anteriorly at the confluence of the inferior opening of a septated (bifurcated) hypoglossal canal and an unnamed foramen medial to the jugular foramen. These canals were distinct from posterior condylar canals when the latter was present. Knowledge of the anatomic variants at the base of the skull may help minimize complications during surgical procedures that employ a paracondylar or transcondylar approach or approaches to the jugular foramen. [ABSTRACT FROM AUTHOR]