Nuchal ligament and interspinous ligaments

The nuchal ligament is a unique arrangement of tendons and fascia lying between the posterior neck muscles. It is located in the median sagittal plane. Because of its structure, the nuchal ligament is sometimes described as a triangular fibrous membrane rather than a ligament. Inferiorly, it continues as the supraspinous ligament.

This ligament has a triangular sheet-like appearance with a base directed upward and an apex facing downward. It extends between the external occipital protuberance superiorly and the tip of the spinous process of the seventh cervical vertebra (C7) inferiorly. One of its margins is free, while the other crosses over the posterior tubercle of the first cervical vertebra (C1) and spinous processes of the second cervical vertebra (C2) to the seventh cervical vertebra (C7).

The nuchal ligament participates in supporting the head. It limits flexion of the head and cervical spine, prevents hyperflexion and promotes returning the head to its anatomical position. Also, adjacent muscles such as the rhomboid minor, splenius capitis, and trapezius attach to its broad lateral surfaces and posterior free margin.

Interspinous ligaments

The interspinous ligaments (interspinal ligaments) are thin, weak, and membranous bands that stretch between the spinous processes of adjacent vertebrae. They attach along the apexes and bases of the spinous processes.

Anteriorly, the interspinous ligaments fuse with the yellow ligaments (Read more!). Posteriorly, they merge with the nuchal ligament in the cervical spine and with the supraspinous ligament below the C7 level.

The cervical interspinous ligaments are only slightly developed. Some authors even state that they are absent in the cervical spine. While some describe them as part of the nuchal ligament, others consider them distinct interspinous fascicles.

The interspinous ligaments limit flexion of the spine and resist the separation of the laminae during flexion.