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Rectus Capitis Lateralis: An Important Landmark in Posterolateral Approaches to the Craniocervical Junction
Introduction: The rectus capitis lateralis (RCL) is a small posterior cervical muscle that connects the transverse process of C1 (C1TP) with the jugular process of the occipital bone. The RCL is located anterolateral to the suboccipital triangle and is normally not seen during a far lateral approach. The RCL can serve as an excellent surgical landmark for localizing several neurovascular structures in variations of the lateral approach including transcondylar, transtubular, and/or high cervical extensions.
Methods: A horseshoe shaped incision was made and the muscles of the suboccipital triangle were dissected on two cadaveric specimens. The incision was extended into the neck and a high cervical dissection of the carotid sheath was performed. The RCL was exposed as it rans medial to the posterior belly of the digastric muscle.
Results: The RCL was identified directly posterior to the internal jugular vein (IJV), separated only by the carotid sheath. The anterior portion of the RCL forms the posterior aspect of the jugular foramen as it inserts on the jugular process. After the VA exits from the C1 foramen transversarium, it courses posteromedially and becomes perpendicular to the RCL. After exiting the stylomastoid foramen, the facial nerve lies 1 to 2 mm anterolateral to the RCL as it inserts on the jugular process. The occipital condyle lies medial to the RCL and extends anteriorly. The hypoglossal nerve courses anterolaterally through the occipital condyle before exiting the hypoglossal canal anterior to the RCL. The jugular bulb lies anterior to RCL’s attachment at the jugular process.
Conclusion: Use of the RCL as a surgical landmark can enhance surgical efficiency and safety during extended lateral variations of the far lateral approach. Extended lateral exposure is sometimes required. Tumors of the sigmoid sinus and jugular canal often invade the sinus and ligating the IJV in the high cervical region is often necessary. The RCL forms a natural landmark that can help identify the IJV within the carotid sheath. High cervical exposure as an adjunct to the far lateral approach can be facilitated by an understanding of the anatomy of the RCL. While exposure of the extracranial facial nerve is rarely required during neurosurgical procedures, avoidance of the facial nerve as it exits the stylomastoid foramen is facilitated by a detailed understanding of its anatomic relationship with the RCL.