Supraspinous ligament

At a glance

English

Supraspinous ligament

Latin (TA2)

Ligamentum supraspinale

System

Ligament

Region

Thorax

Side

Single, on the midline

About the supraspinous ligament

Of all the ligaments of the vertebral column, the supraspinous ligament is the most superficial and the easiest to feel. It is a continuous fibrous cord laid along the spine tips, the bony points that can be felt down the middle of the back. At its upper end, at the seventh cervical spine, it merges with the nuchal ligament, which carries the same midline line on to the skull. Below, it usually fades out over the lower lumbar spines and the median sacral crest.

Along its course it is joined on its deep side by the interspinous ligaments, the thin sheets that fill the gaps between neighbouring spines. It is wider and thicker in the lumbar region than in the thorax, and at all levels it is closely blended with the surrounding thoracolumbar fascia and the tendons of muscles such as trapezius and latissimus dorsi. Its fibres are layered: the most superficial span three or four vertebrae, a middle layer spans two or three, and the deepest fibres simply join one spine to the next.

Working with the interspinous ligaments, the ligamenta flava and the posterior longitudinal ligament, it limits how far the spine can bend forwards. Being furthest from the axis of movement, it is stretched most in full flexion and is the first of these to be strained when the back is forced into deep bending.

Damage to it may leave a tender, palpable thickening in the midline, and ultrasound can show the lesion. In a midline lumbar puncture or epidural, the needle passes through skin and fat and then meets the supraspinous ligament as the first firm layer, followed by the interspinous ligament and the ligamentum flavum; its resistance is part of the feel the operator learns to recognise. In older people it may be calcified, making a midline approach harder.

Attachments and function

Attaches from

The tip of the C7 spine, continuous above with the nuchal ligament.

Attaches to

The tips of the lumbar spinous processes and the median sacral crest.

Function

Limits flexion of the vertebral column and binds the spinous processes together along the back.

Nerve supply

Medial branches of the dorsal rami of the spinal nerves.

Blood supply

Dorsal branches of the posterior intercostal and lumbar arteries.