The sternoclavicular joint is an important structure that is frequently overlooked. They contribute to the anterior border of the thoracic inlet. The sternoclavicular joint is a saddle type synovial joint between the medial surface of the clavicle and the clavicular fossa of the manubrium. The joint allows for movement in all planes, and is supported by numerous ligaments.
The sternoclavicular joint is a saddle type synovial joint formed between the manubrium of the sternum and the larger rounded medial articulating surface of the clavicle. The articulating surfaces of the two bones are covered in fibrocartilage, and may have a disc of fibrocartilage interposed between them. The disc also attaches to the joint capsule in front and behind, as well as the first costal cartilage below, and the clavicle above. This is unlike the articulating surfaces of the synovial joints that are covered in hyaline cartilage. In front of the joint is the sternocleidomastoid muscle. The sternothyroid and sternohyoid attach to the posterior surface of the manubrium. The brachiocephalic veins also lie just posteriorly to the joint.
The joint can move in all four planes, including elevation of the arm to 90 degrees and rotation of the sternoclavicular joint to 30 degrees. Due to the relative incongruence of the two articulating surfaces, the joint relies on surrounding ligaments to provide stability. These strong ligaments include the anterior and posterior sternoclavicular ligaments and the interclavicular ligament that joint the superomedial surfaces of the clavicles. The anterior sternoclavicular ligament limits superior dislocation of the joint, with the posterior sternoclavicular joint limiting anterior posterior instability. The costoclavicular ligament (also known as the rhomboid ligament) joins the first rib to the clavicle and supports the inferior aspect of the joint. It almost always merges with the joint capsule, and has a deep and superficial part separated by a bursa.
The joint is supplies by the internal thoracic branch of the subclavian artery and suprascapular arteries (branch of the thyrocervical trunk). It is innervated by the subclavius (a branch of the brachial plexus) and the supraclavicular nerves (branch of the cervical plexus).
Developmental precursor- Limb bud, somatic layer of lateral mesoderm
Blood supply- internal thoracic and suprascapular arteries
Nerve supply- supraclavicular nerve and nerve to subclavius
Bursae- Costoclavicular bursa