The nuchal ligament is a ligament at the back of the neck that is continuous with the supraspinous ligament.

The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous process of the seventh cervical vertebra in the lower part of the neck.

From the anterior border of the nuchal ligament, a fibrous lamina is given off. This 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.

The trapezius and splenius capitis muscle attach to the nuchal ligament.

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 and canids, the nuchal ligament serves to sustain the weight of the head.

In Chiari malformation treatment, decompression and duraplasty with a harvested nuchal ligament showed similar outcomes to pericranial and artificial grafts.

In sheep and cattle, it is known as the paxwax. It relieves the animal of the weight of its head.

The nuchal ligament is unusual in being a ligament containing more elastin as well as collagen, allowing for stretch and recovery to its original form. Other ligaments are made mostly of viscoelastic collagen fibers, a material two orders of magnitude stiffer, which cannot retain their original shape when extended past a certain point or for a prolonged period of time.