Human Anatomy/Osteology/Upper Extremities
The Fixed Upper Limb
The fixed upper limb is the region that joins the free upper limb to the trunk. It is made up of the pectoral, axillary and shoulder regions. Its primary role is to act as a link between the free upper limb and the axial skeleton.
The Bones of the Fixed Upper Limb
The main bones of the fixed upper limb are the clavicle and the scapula. The sternum, ribs, vertebrae and humerus, though all considered part of other regions, need to be considered when studying this region as many of the muscles and ligaments of the fixed upper limb arise from or insert into one of these bones.
The clavicle (sometimes referred to as the collarbone) is one of the two bones considered part of the fixed upper limb. It is the anterior bone of the fixed upper limb, with its medial third sitting just anterior to the first rib of the thorax. It marks the superior border of the anterior segment of the fixed upper limb.
The clavicle has both a medial and lateral articulation. Medially (also referred to as its sternal end), the clavicle's sternal articular facet articulates with the sternum at the sternoclavicular joint. Laterally (also referred to as the acromial end), the clavicle's acromial articular facet articulates with the acromion of the scapula at the acromioclavicular joint. Both facets are covered by fibrocartilage. The body (shaft) of the clavicle is palpable for most of its length as it runs between the sternum and the acromion.
In cross-section, the clavicle is more-or-less rounded throughout its body. The bone is expanded at its sternal end and flattened towards its aromial end. The medial two thirds are convexed anteriorly and the lateral one third is concave anteriorly.