leg, shin
臑 centers on the lower leg, specifically the shin area. It refers to the front part of the leg between the knee and ankle.
臑 combines the flesh radical ⺼ (meat/body part) with 需, which likely provides the sound. The character specifically denotes the shin or lower leg.
The flesh radical ⺼ on the left indicates a body part. The right side 需 looks like rain 雨 over a structure 而, but here imagine it as the shape of a shin bone under the skin. Together, 臑 is the shin.
For ジ, picture a shin that starts to itch, and you say 'Gee, my shin itches!' The 'Gee' sound cues ジ, and the scene ties back to the shin meaning.