Final answer:
Sterno+costal pertains to the sternum and the ribs. The sternum is the centrally located bone to which the first seven pairs of ribs (true ribs) attach directly; the next three pairs (false ribs) attach indirectly, and the last two pairs (floating ribs) do not attach to the sternum at all.
Step-by-step explanation:
The term sterno+costal pertains to the sternum and the ribs. The sternum, also known as the breastbone, is a long flat bone in the anterior chest, composed of the manubrium, body, and xiphoid process. The ribs are 12 pairs of long, curved bones that form the ribcage by attaching to the thoracic vertebrae and curving towards the front of the body. Costal cartilages connect the anterior ends of ribs to the sternum, helping to provide structure and flexibility to the thoracic cage - the area that encloses and protects the heart and lungs.
The first seven pairs of ribs, known as the 'true ribs', are directly connected to the sternum via their costal cartilage. The false ribs (8-12), have a different type of attachment, with ribs 8-10 being connected indirectly to the sternum by attaching to the cartilage of the rib above, and the last two pairs (11 and 12) being the 'floating ribs', which do not connect to the sternum at all.