Muscles connecting the arm to the spine seen from behind (nuchal ligament labeled in red at center)
|From||External occipital protuberance|
|To||Spinous process of C7|
From its anterior border a fibrous lamina is given off, which is attached to the posterior tubercle of the atlas, and to the spinous processes of the cervical vertebrae, and forms a septum between the muscles on either side of the neck.
All dogs (and all living Canidae - wolves, foxes, and wild dogs) possess a similar ligament connecting the spinous process of their first thoracic (or chest) vertebrae to the back of the axis bone (second cervical or neck bone), which supports the weight of the head without active muscle exertion, thus saving energy. This ligament is analogous in function (but different in exact structural detail) to the nuchal ligament found in ungulates. This ligament allows dogs to carry their heads while running long distances, such as while following scent trails with their nose to the ground, without expending much energy.
In humans it is a tendon-like structure that has developed independently in humans and other animals well adapted for running. In some four legged animals, particularly ungulates, the nuchal ligament serves to sustain the weight of the head.
- Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students (Pbk. ed.). Philadelphia: Elsevier/Churchill Livingstone. p. 45. ISBN 978-0-443-06612-2.
- Swindler, D. R., and C. D. Wood. 1973 An Atlas of Primate Gross Anatomy. Seattle: University of Washington Press[page needed]
- Bramble, Dennis M.; Lieberman, Daniel E. (2004). "Endurance running and the evolution of Homo". Nature. 432 (7015): 345–52. Bibcode:2004Natur.432..345B. doi:10.1038/nature03052. PMID 15549097.
- Wang, Xiaoming and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. pp.97-8