Topographic Anatomy and Step-Wised Harvest of Intermuscular Occipital Artery in Far Lateral Approach.

Background: The occipital artery (OA) is an important donor artery for intracranial and extracranial bypass surgery, but its path is tortuous, making it difficult to harvest. Part of the traditional intermuscular OA is not covered by muscle and is easily damaged during surgery. Currently, there are few reports on how to protect this segment of the OA.

Objectives: To clarify the course of the intermuscular OA and its positional relationship with different muscles through anatomical measurements, and to explore how to quickly and safely harvest the occipital artery in the far lateral approach.

Methods: Thirty-three sides of seventeen formalin-fixed adult cadaveric heads (n=33) were used for anatomical measurements to clarify the positional relationship between the OA and the splenius capitis muscle and the superior nuchal line (SNL). A "reverse C-shaped" surgical incision through the far lateral approach was used to find the attachment of the uppermost muscle fiber of the splenius capitis muscle to the SNL, the site where the OA passed through the splenius capitis muscle, and the site where the OA crossed the SNL. The distances between these three points were measured, and the proximal and distal diameters of the OA were also measured. We proposed how to safely and quickly harvest the OA using the splenius capitis muscle as a landmark in the far lateral approach.

Results: In all specimens, part of the intermuscular OA ran below the tendons and connective tissues in the superficial layer of the muscle. This area was located on the medial side of the uppermost muscle fibers of the splenius capitis muscle, below the SNL, and on the surface of the sternocleidomastoid muscle or trapezius muscle tendons. There were no dense muscle fibers on the surface of the OA in this area, which we referred to as the posterior segment of OA of the splenius capitis muscle, with the length of 29.3 ± 12.1mm.

Conclusion: Through the far lateral approach, the splenius capitis muscle is a useful landmark to expose the OA. We can safely, quickly and accurately find the OA by dissecting within 13.6 ± 5.2mm below the uppermost muscle fiber of the splenius capitis muscle.