Posterior sternoclavicular ligament

At a glance

English

Posterior sternoclavicular ligament

Latin (TA2)

Ligamentum sternoclaviculare posterius

System

Ligament

Region

Upper limb

Side

Paired, left and right

About the posterior sternoclavicular ligament

The sternoclavicular joint, between the inner end of the clavicle and the upper corner of the manubrium, is held by four ligaments: anterior, posterior, interclavicular and costoclavicular. The posterior sternoclavicular ligament is the thickening on the back of the capsule and, though it receives less attention than its front partner, it is the stronger of the two and the most important restraint for this joint.

It is a band of fibres laid over the back of the joint. From the top and back of the clavicle's medial end it slopes downwards and medially to the posterior surface of the manubrium, near its upper border. In front, on its deep side, are the articular disc and the two synovial membranes of the joint. Behind it are the sternohyoid and sternothyroid muscles, and beyond them lie the brachiocephalic vein, the common carotid artery, the vagus nerve and, near the midline, the trachea. Its position thus separates the joint from vital structures at the root of the neck.

The ligament prevents the medial end of the clavicle from moving backwards, which tends to happen when the shoulder is driven forwards. Biomechanical studies have shown it to be the main barrier to both forward and backward translation of the clavicle at this joint, more so than the anterior ligament.

Posterior dislocation of the sternoclavicular joint is uncommon but potentially serious. The medial clavicle is pushed behind the manubrium and can press on the great veins and arteries, the trachea or the oesophagus, causing breathing or swallowing difficulty or loss of circulation to the arm. It usually follows a heavy blow to the front of the shoulder or chest, and reduction is carried out with a vascular surgeon available. In teenagers and young adults, the same injury often turns out to be a separation through the medial clavicular growth plate.

Attachments and function

Attaches from

The top and back of the clavicle's medial end.

Attaches to

The posterior surface of the manubrium of the sternum near its upper border.

Function

Reinforces the back of the sternoclavicular joint and is the main restraint against backward and forward translation of the medial clavicle.

Nerve supply

Branches of the medial supraclavicular nerve and the nerve to subclavius.

Blood supply

Branches of the internal thoracic and suprascapular arteries.