The lateral atlantooccipital ligament

Abstract

The LAO is a constant anatomical structure of the craniocervical junction that might be of concern to the clinician. This ligament inhibits lateral flexion of the atlantooccipital joint and its disruption appears to add to instability at this articulation.

Ligaments of the craniocervical junction

“…51 The mean tensile strength of 37.5 N is relatively substantial and indicates that this ligament may play a role in maintaining stability at the CCJ. When the LAO ligament was transected in cadavers, Tubbs et al 75 observed an increase in lateral flexion of the contralateral side of 3°-5°. Additionally, 14 reported that axial rotation at the atlantooccipital joint of greater than 5° indicates hypermobility.…”

“…Biomechanics Although no studies have tested the biomechanical function of the LAO ligament, data from Tubbs et al 75 suggested that the ligament plays a role in limiting lateral flexion of the head. Lateral flexion of the head occurs almost exclusively in the subaxial spine, although Panjabi et al 56 reported that lateral flexion of the atlantooccipital joint may range from 8° to 40°.…”

“…It runs just lateral to the anterior atlantooccipital membrane, attaching to the anterolateral aspect of the transverse process of the atlas, and inserting onto the jugular process of the occipital bone. 59,75 This ligament runs immediately posterior to the rectus capitis lateralis muscle and has fibers that extend in the opposite direction to the muscle (that is, muscle runs lateral to medial and ligament runs medial to lateral). Additionally, the LAO ligament relates posteriorly to the VA and anteriorly to the jugular vein as it exits the jugular foramen.…”

“…Additionally, the LAO ligament relates posteriorly to the VA and anteriorly to the jugular vein as it exits the jugular foramen. 75 Tubbs et al 75 studied the LAO ligament in 20 human cadavers to elucidate the anatomy and function of the ligament and found the LAO ligament was present bilaterally in all bodies. The mean length, width, and thickness of this ligament were 22, 5, and 2 mm, respectively.…”

The atlanto-occipital joint: a concise review of its anatomy and injury

“…[9] LAO has a mean angle of 26° from the midline and a mean length and width of 2.2 and 0.5 cm, respectively. [9] This ligament limits lateral flexion of the neck and partially limits neck rotations bilaterally at the AOJ. [9] The alar ligaments (AL) (Figure 6) are dense structures that connect the odontoid process to the medial aspect of the OCs.…”