Final answer:
The organ palpable deep to the left costal margin during inspiration is the spleen edge. The spleen must be significantly enlarged to be palpable during a physical examination. In contrast, the liver edge can be palpated under the right costal margin.
Step-by-step explanation:
The organ palpable deep to the left costal margin during inspiration is the spleen edge. Typically, the spleen enlarges in a downward and medial direction, staying within the rib cage, which is why palpation beneath the left costal margin can detect splenic enlargement. During inspiration, the diaphragm descends and the abdomen contents are pushed downward, potentially making the spleen more palpable. Normally, the spleen is not palpable in most individuals; it must be significantly enlarged to be felt during physical examination. Palpation of the spleen should be done carefully to avoid causing discomfort or injury. In contrast, the liver edge might be palpable under the right costal margin.