Sigmoid Sinus Within a Section of the Skull

Description

Cut away in lateral section, the male skull reveals the deeply concave sulcus for the sigmoid sinus curving within the mastoid portion of the temporal bone, then turning inferiorly toward the jugular foramen where it continues as the internal jugular vein. Superior and posterior to the petrous ridge, the sigmoid sinus receives flow from the transverse sinus and runs medial to the mastoid air cell system and posterior to the middle ear cavity. Adjacent cranial landmarks in this side view typically include the occipital bone, parietal bone, and the petrosquamous region, with the cerebral hemispheres exposed after removal of the calvaria and reflection of dura. For teaching dural venous drainage, the sigmoid sinus is the key corridor between intracranial venous sinuses and the extracranial venous system, and this view makes the relationship to the mastoid and jugular bulb easy to read. That anatomy matters in otogenic lateral sinus thrombosis and in mastoiditis, where infection can propagate to the sigmoid sinus with risk of septic thrombophlebitis and raised intracranial pressure. It also frames surgical risk during mastoidectomy and retrosigmoid approaches, where the sinus can be injured if its bony groove is dehiscent or if the jugular bulb is high riding. A tight operative neighborhood. Use this illustration in neuroanatomy and head and neck anatomy courses when you need students to connect dural reflections, venous sinuses, and the temporal bone in one continuous pathway, or in ENT and neurosurgical texts discussing mastoid surgery corridors and venous sinus complications of ear disease. It also supports radiology teaching when correlating CT of the temporal bone and MR venography with the expected bony groove and sinus contour. Anatomical accuracy verified by SciePro's Medical Advisory Board.