Sigmoid Sinus in the Male Skull

Description

Cut through the lateral calvaria, the cranial cavity opens to the dural venous sinuses with the superior sagittal sinus coursing in the midline along the inner table before draining posteriorly into the confluence and then into the transverse sinus. Along the posterolateral cranial fossa, the transverse sinus curves inferiorly and anteriorly as the sigmoid sinus, riding in its bony groove on the mastoid part of the temporal bone and approaching the jugular foramen as the superior bulb of the internal jugular vein. Anteroinferiorly, the cutaway preserves key external landmarks of the viscerocranium while the mandible is absent, leaving the glenoid fossae (mandibular fossae) exposed just anterior to the external acoustic meatus. Spatially, the sigmoid sinus sits posteroinferior to the temporal lobe region and lateral to the posterior cranial fossa contents. Surgeons care about this relationship. Mastoidectomy and posterior tympanotomy place drills and curettes within millimeters of the sigmoid sinus, and dehiscence or a high-riding jugular bulb can turn routine otologic work into brisk venous bleeding. Thrombosis of the transverse-sigmoid system, often linked to mastoiditis or hypercoagulable states, produces headache, papilledema, and venous infarction patterns that hinge on exactly where this S-shaped channel narrows and turns. Small structure, large consequences. Use this cutaway for teaching dural sinus drainage in head and neck anatomy, for neurosurgical and otolaryngology atlases illustrating the temporal bone corridor, or for radiology education correlating CT venography and MR venography with the sigmoid groove and jugular foramen. It also supports patient-facing explanations of lateral sinus thrombosis and peri-mastoid surgical risk. Anatomical accuracy verified by SciePro's Medical Advisory Board.