ability, talent, elbow, arm
肱 centers on the arm, especially the upper arm or elbow, as a physical part. The meanings of ability and talent are natural extensions of the arm as a symbol of strength and capability.
肱 combines 月 (flesh/body part) with 厷, which likely contributes the sound and may have originally depicted an arm or a bent shape. The character specifically refers to the upper arm or elbow.
The left side 月 (flesh) and the right side 厷 (which looks like a bent arm with a hand) together picture the upper arm or elbow. Think of flexing your arm to show ability and talent.
For コウ, imagine a strong arm bending into a 'ko' shape, like the curve of an elbow. The sound 'ko' cues コウ, and the bent arm shows the kanji's meaning.