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The clavicula also known as the collar bone, is a sigmoid-shaped long bone that makes up the front part of the shoulder. It sits between the shoulder blade and the sternum. There are 2 clavicles in a person, one on the right and the other one on the left side. It is the only long bone in the body that lies horizontally.
Due to the clavicle’s structure, there are only two planar diarthrosis articulations that can be found. This type of articulation is also known as a ‘double plane joint’ – where two joint cavities are separated by a layer of articular cartilage.
A total of five muscles are attached to the clavicle, found distributed at either the lateral third or medial two thirds of the bone.
Two muscles are attached to the lateral third of the clavicle:
- The trapezius muscle, which is attached along the posterior surface of the bone.
- The deltoid muscle, where the anterior portion of the muscle is attached to the periosteum at the anterior surface of the bone.
Three muscles are attached to the medial third of the clavicle:
- The sternocleidomastoid muscle, where the muscular clavicular head of the muscle is attached to the superior surface of the bone.
- The pectoralis major muscle, which is attached to the anterior surface of the bone.
- The subclavius muscle, which is attached to a groove found in the middle of the bone’s inferior surface. From there, the muscle extends into both lateral and medial areas of the clavicle.
- Anatomy, Shoulder and Upper Limb, Clavicle Scott Hyland; Matthew Varacallo. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.