Final answer:
The diaphragm does not attach to the upper 3 ribs. It attaches to the xiphoid process of the sternum, the inferior six ribs and their cartilages laterally, as well as the lumbar vertebrae and 12th ribs.
Step-by-step explanation:
The diaphragm does not attach to the upper 3 ribs (a). The diaphragm is a large, dome-shaped muscle that plays a critical role in respiration by contracting and relaxing to change the volume of the thoracic cavity. The attachments of the diaphragm include:
- The xiphoid process of the sternum anteriorly.
- The inferior six ribs and their cartilages laterally.
- The lumbar vertebrae (specifically L1-L3) and 12th ribs posteriorly.
The upper three ribs do not serve as attachment points for the diaphragm, thus the correct answer to the question is option (a). In the human ribcage, the ribs are classified as true ribs (1-7), which attach directly to the sternum via their costal cartilage, and false ribs (8-12), which attach indirectly or not at all to the sternum.
The floating ribs (11-12) are included in the latter category as they do not connect to the sternum or to the costal cartilage of another rib. The diaphragm's musculature is primarily involved in the mechanics of breathing and is not connected to the upper three ribs.