Final answer:
The inside margin of each rib containing a neurovascular bundle is known as the costal groove. This groove runs along the inferior margin of each rib and houses an artery, vein, and nerve.
Step-by-step explanation:
The inside margin of each rib contains an artery, a vein, and a nerve and is called the costal groove. This shallow groove is located along the inferior margin of each rib and provides a passage for the neurovascular bundle (including blood vessels and a nerve) to run. The ribs are an integral part of the thoracic cage, with true ribs (1-7) attaching directly to the sternum via costal cartilage, false ribs (8-12) attaching to the sternum indirectly or not at all, and floating ribs (11-12) not attaching to the sternum or another rib.
Anteriorly, each rib ends in costal cartilage, which provides for either direct or indirect attachment to the sternum. Posteriorly, the head of the rib articulates with the costal facets located on the bodies of thoracic vertebrae, while the tubercle of the rib articulates with the facet located on the transverse process.