The nuchal ligament

The nuchal "ligament" (ligamentum nuchae) composed of two parts: the dorsal raphe and the midline fascial septum. In humans, neither component is a true ligament, leading some to question the terminology. The image shows a patient with a disrupted dorsal raphe following trauma.

The dorsal raphe, also known as the funicular (funiculus: Latin for rope) portion of the nuchal ligament, extends from the external occipital protuberance to the spinous process C7. The dorsal raphe is not a true ligament. It is formed by interlacing tendons of the trapezius muscle throughout the course of the dorsal raphe and by the fibers of the splenius capitis and rhomboid minor muscles caudad to the C4 spinous process.

The second part of the nuchal "ligament" is the midline fascial septum (also known as the lamellar portion) is attached to the ventral aspect of the dorsal raphe and extends to the tips of the spinous processes. Rostrally, it attaches to the external occipital protuberance and the external occipital crest.

It has been suggested by some that preserving the dorsal raphe at C6 and C7 during laminoplasty can prevent undesirable radiologic changes such as kyphotic deformity and destabilization.

Calcifications can be seen along the nuchal "ligament" and are thought to represent sesamoid bones.

Trivia

The nuchal ligament in quadrupeds is a true ligament that supports the dependent head. It is known as the paxwax (bastardization of faxwax which is Old English for hair and to grow). Paxwax itself has been bastardized as paddywhack or paddywack, and can be found in the nursery rhyme, "This old man." Today, paxwax is commonly sold in pet stores as a doggie treat.

References

• Kadri PA, Al-Mefty O. Anatomy of the nuchal ligament and its surgical applications. Neurosurgery. 2007 Nov;61(5 Suppl 2):301-4;
• Mercer SR, Bogduk N. Clinical anatomy of ligamentum nuchae. Clin Anat. 2003 Nov;16(6):484-93.
• Sakaura H, Hosono N, Mukai Y, Oshima K, Iwasaki M, Yoshikawa H. Preservation of the nuchal ligament plays an important role in preventing unfavorable radiologic changes after laminoplasty. J Spinal Disord Tech. 2008 Jul;21(5):338-43.
• Scapinelli R. Sesamoid bones in the ligemntum nuchae of man. J Anat. 1963 Jul;97:417-22.