Description
The external border (outer border) of first rib is its convex, outer edge. It is one of the two borders of the body of the first rib, the other being the internal border. Unlike the other eleven ribs, which have superior and inferior borders, the unique orientation of the first rib gives it external and internal borders.
The external border of first rib provides origin sites for the external, internal and innermost intercostal muscles.
Related parts of the anatomy
