Nuchal ligament

At a glance

English

Nuchal ligament

Latin (TA2)

Ligamentum nuchae

System

Ligament

Region

Neck

Side

Single, on the midline

About the nuchal ligament

The cervical spinous processes are short and lie deep in the neck, so the midline attachment for the back-of-neck muscles is supplied instead by a fibrous partition, the nuchal ligament (ligamentum nuchae). Below, it carries on as the supraspinous ligament that links the tips of the thoracic and lumbar spines, and the two can be thought of as one continuous midline band.

The ligament has two parts. Its thick superficial edge, the funicular part, runs as a cord from the external occipital protuberance of the skull down to the spine of C7, the vertebra prominens. From the deep side of that cord a thin, triangular lamina (the laminar part) passes forwards to attach to the median nuchal line (external occipital crest), the atlas's posterior tubercle and the cervical spines in between. The result is a midline septum dividing the muscles of the right side of the neck from those of the left.

Many muscles take attachment from it. Trapezius and splenius capitis arise from its superficial edge, and rhomboid minor and serratus posterior superior from its lower end, while the deeper extensors abut its lamina. In humans it is mainly fibrous, with modest elastic content, and acts chiefly as an anchoring sheet; it gives some passive support to the head when the neck is bent forwards.

A nuchal ligament arose separately in humans and in mammals built for running, probably to steady the head during gait. In grazing hoofed animals it is a massive elastic cable that holds up the heavy head and neck with little muscle effort. In sheep and cattle butchers call it the paxwax. Dogs and other canids have a comparable band from the first thoracic spine to the axis, which lets them carry the head low on a scent trail without tiring. Most other primates have only a thin fascia here. Clinically, surgeons have used strips of nuchal ligament as graft material to repair the dura in decompression operations for Chiari malformation, with results comparable to other grafts.

Attachments and function

Attaches from

The external occipital protuberance and median nuchal line (external occipital crest) of the occipital bone.

Attaches to

The spine of C7 (vertebra prominens); its deep lamina also reaches the atlas's posterior tubercle and each cervical spine.

Function

Forms a midline septum and attachment for the neck muscles and gives passive support to the head when the neck flexes.

Nerve supply

Twigs of the dorsal rami of the cervical spinal nerves.

Blood supply

Branches of the occipital artery and the deep cervical arteries.