The Transverse Occipital Ligament

BACKGROUND: Knowledge of the anatomy of ligaments that bind the craniocervical junction is important for treating patients with lesions of this region. Although the anatomy and function of these ligaments have been well described, those of the transverse occipital ligament (TOL) have remained enigmatic. OBJECTIVE: To describe the anatomy and functions of the transverse occipital ligament. METHODS: Via a posterior approach, 9 cadaveric specimens underwent dissection of the craniocervical junction with special attention to the presence and anatomy of the TOL. RESULTS: The TOL was identified in 77.8% of the specimens. The ligament was found to be rectangular with fibers running horizontally between the lateral aspects of the foramen magnum. The attachment of each ligament near the occipital condyle was consistent, and each ligament was found superior to the transverse portion of the cruciform ligament and inserted just posterior to the lateral attachment sites of the alar ligaments. The average width, length, and thickness of the TOL was 0.34, 1.94, and 0.13 cm, respectively. The TOL in some specimens also had connections to the alar and transverse ligaments. CONCLUSION: The TOL was found in the majority of our specimens. The possible functions of this ligament when attached to the alar ligaments include providing additional support to these structures in stabilizing lateral bending, flexion, and axial rotation of the head. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal from pathology via imaging modalities.