To provide further information on the identification of the occipital artery (OA) and suggest an improved approach to its anterograde dissection technique for harvesting.
Six cadaveric specimens were prepared for surgical simulation, and the anterograde approach was used to harvest the OA; a hockey stick incision was made from the C2 spinous process through the nuchal ligament to the mastoid tip. By retracting the scalp flap from the posterior arch of C2 to the transverse process, the suboccipital triangle was reflected by a single myocutaneous flap from the inferior nuchal line. In addition, 70 head computed tomography angiography scans were assessed bilaterally (n = 140) to study the running pattern of the OA.
The mean total length of the mobilized OA was 11.8 ± 0.7 cm, with a diameter of 1.5 ± 0.1-2.1 ± 0.2 mm at the suboccipital segment and 1.3 ± 0.1 mm at the upper edge of the surgical incision. The average distance of OA at the inferior nuchal line to the midline was 2.9 ± 0.3 cm, the average distance of OA at the superior nuchal line to midline was 4.1 ± 0.2 cm, the average distance of OA at incision edge to midline was 5.2 ± 0.3 cm.
Orientational anterograde technique for OA harvesting is a fast and easy approach. This approach avoids critical neurovascular structures. The most important step is to identify the OA near the lateral edge of the superior oblique muscle. Subsequently, in conjunction with preoperative computed tomography angiography, an imaginary line that crosses the inferior and superior nuchal lines may be established to assist in the separation of the OA.

UNASSIGNED: The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases.
UNASSIGNED: Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT.
UNASSIGNED: Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT.
UNASSIGNED: Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

OBJECTIVE: The far-lateral approach (FLA) remains a challenge for neurosurgeons due to the complex anatomy of this region, especially in patients with anatomical variations. There is therefore an urgent need for better quantitative knowledge of the microsurgical anatomy of the FLA.
METHODS: The study was performed using the dried skulls and atlas vertebrae of 50 Chinese adults, in which significant clinical parameters were measured. We further used 12 cadaveric heads to simulate the FLA to explore the step-by-step anatomy entailed by this procedure, enabling us to obtain key images and related information.
RESULTS: Limited to hypoglossal canal, the occipital condyle posterior was abraded by roughly 10 mm, which provided good exposure to the ventral front of the foramen magnum. When occipital artery exits the occipital groove, the mean diameter was 2.20 mm. The average occipital artery suboccipital segment length was 65.26 mm. The posterior spinal artery (PSA) and posterior inferior cerebellar artery (PICA) generally originated from the fourth vertebral artery segment intradurally, and the mean distances from the PSA and PICA to the dural entry point of the vertebral artery were 2.62 mm and 8.71 mm, respectively. The incidence of PSA and PICA arising from the third vertebral artery segment was 16.67% and 4.17%, respectively.
CONCLUSIONS: Understanding the important anatomic structures of the CVJ region and developing improved knowledge of the microsurgical anatomy of the FLA offer an opportunity to ensure safe exposure and treatment of lesions in the ventral and ventrolateral regions of the CVJ.

Several far lateral approaches have been proposed to deal with cranio-vertebral junction (CVJ) tumors including the basic, transcondylar, and supracondylar far lateral approaches (B-FLA, T-FLA, and S-FLA). However, the indications on when to use one versus the other are not well systematized yet. Our purpose is to evaluate in an experimental cadaveric setting which approach is best suited to remove tumors of different sizes.
We implanted at the CVJ, using a transoral approach, tumor models of different sizes (five 1-cm3 and five 3-cm3 tumors) in ten embalmed cadaveric heads. The artificial tumors were exposed via the three approaches using endoscopic-assisted microneurosurgical technique and neuronavigation. The skull base area exposed and the maneuverability linked to each approach were evaluated using neuronavigation.
In 1-cm3 tumors, the T-FLA and the S-FLA exposed a significantly larger skull base area than the B-FLA both using the microscope and the endoscope (P < 0.05); the T-FLA executed with the microscope provided wider vertical and horizontal maneuverability than the B-FLA (P = 0.030 and 0.017, respectively); the S-FLA executed with the endoscope provided wider vertical maneuverability than the T-FLA (P = 0.031). The S-FLA executed using the microscope and the endoscope provided wider vertical maneuverability than the B-FLA both in 1 and 3-cm3 tumors (P < 0.05).
In 1-cm3 tumors, the S-FLA and the T-FLA expose a wider skull base area than the B-FLA. In larger tumors, the exposure is similar for all three approaches. Use of the endoscope in an assistive mode may further increase the surgical exposure and maneuverability.