Anatomical Landmarks for Transverse-Sigmoid Sinus Junction: A Cadaveric Study

Area of Science:

• Neurosurgery
• Anatomy
• Surgical Navigation

Background:

• Accurate identification of posterior cranial fossa structures is vital for minimizing surgical complications.
• Superficial landmarks are crucial for guiding surgical approaches to deep cranial anatomy.
• The transverse sinus (TS) and transverse-sigmoid sinus junction (TSSJ) are critical structures in the posterior cranial fossa.

Purpose of the Study:

• To establish the top of the mastoid notch (TMN) as a reliable external landmark for locating the TSSJ.
• To predict the anatomical course of the transverse sinus (TS) using superficial cranial landmarks.
• To provide anatomical data that can assist surgeons in planning posterior fossa procedures.

Main Methods:

• Anatomical dissections were performed on 10 adult cadaveric skulls (20 sides).
• A coordinate system was established using the Frankfurt line and a vertical line through the TMN.
• Intracranial drilling from the internal cranial surface was used to identify and map the TS and TSSJ.

Main Results:

• The inferomedial point of the TSSJ was located dorsally and cranially from the TMN.
• Distances of the TS edges from the Frankfurt horizontal plane were measured at specific points.
• The right transverse sinus diameter was significantly larger than the left, and the confluens sinuum was consistently located to the right of the inion.

Conclusions:

• The TMN serves as a reliable landmark for locating the TSSJ.
• The study provides a method for delineating the TS trajectory using external landmarks.
• These findings can aid surgeons in identifying intracranial structures in the posterior fossa, particularly when advanced navigation is unavailable.