rib
肋 centers on the rib, the curved bone in the chest. It is a specific anatomical term without broad abstract extensions.
肋 combines the flesh radical ⺼ (meat, body part) with 力, which likely contributes the sound. The character specifically denotes the rib.
The flesh radical ⺼ on the left indicates a body part, and the right side 力 suggests strength. Picture the strong, curved ribs protecting the chest like a cage.
For ロク, imagine a rib cage as a locked box of bones: lock -> ロク, and the ribs are the locked bars around your chest.
rib
rib; rib cage
boneless rib (esp. of pork or beef); boned rib
intercostal
midrib; rachis
subcostal artery
costal fovea
wall bars
lumber (for the ribs of a ship)
pleura
pleurisy
costal cartilage
costochondritis
intercostal artery
intercostal nerve
intercostal neuralgia
intercostal muscle
levatores costarum
iliocostalis muscle