A better understanding of the associated anatomy, embryology, and pathology of these cysts will assist the clinician who treats such patients.

Knowledge of the inferior petrosal sinus is of great importance for open surgical approaches to the skull base and endovascular access to the cavernous sinus and sellar region.

T he SPS is a small, narrow venous channel located at the junction between the middle and posterior cranial fossae. It is adjacent to many important intracranial structures, and its vicinity to these structures makes it an important landmark for surgical approaches to the skull base. It originates in the CS and passes dorsolaterally to drain into the transverse-sigmoid junction. The sinus runs in the superior petrosal sulcus and begins from the posterolateral base of the petrous ridge and travels at an anteromedial angle toward its apex, and is usually larger posteriorly and becomes smaller near its apex. 23 This sinus travels in the attached margin of the tentorium cerebelli 26 and receives drainage from the cerebellum, the inferior cerebral veins, and the veins of the tympanic cavity. 26,31 Since knowledge of such regional anatomy is important to the neurosurgeon, and the relationship of the SPS to the Meckel cave has not been stressed in the literature, the current study was undertaken.The relationship between the superior petrosal sinus and the porus trigeminus: an anatomical study Object. During intracranial approaches to the skull base, vascular relationships are important. One relationship that has received scant attention in the literature is that between the superior petrosal sinus (SPS) and the opening of the Meckel cave (that is, the porus trigeminus).Methods. Cadaver dissections were performed in 25 latex-injected adult cadaveric heads (50 sides). Specifically, the relationship between the SPS and the opening of the Meckel cave was observed. The goal was to enhance knowledge of the relationship between the SPS and the opening of the Meckel cave.Results. Of the 50 sides, 68%, 18%, and 16% of SPSs traveled superior to, inferior to, and around the opening to the Meckel cave, respectively. In the latter cases, a venous ring was formed around the proximal trigeminal nerve. No sinus entered the Meckel cave. In general, the porus trigeminus was narrowed on sides found to have an SPS that encircled this region. Sinuses that traveled only inferior to the porus were in general smaller than sinuses that traveled superior or encircled this opening. No statistically significant differences were noted between the various sinus relationships and sex, age, or side of the head.Conclusions. Knowledge of the relationship between the SPS and the opening of the Meckel cave may be useful to the skull base surgeon. Based on this study, some individuals may retain the early embryonic position of their SPS in relation to the trigeminal nerve.

The superior petrosal sinus is located between the middle and posterior cranial fossae and is important during many neurosurgical approaches to the skull base. Using standard search engines, the anatomical and clinical importance of the superior petrosal sinus was investigated. The superior petrosal sinus is important in many neurosurgical approaches and pathological entities. Therefore, it is important for those who operate at the skull base or interpret imaging here to have a good working knowledge of its anatomy, development, and pathological involvement.

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