This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 胈 is uncertain. It combines ⺼ (flesh) with 犮, but the original meaning and component function are unclear.
With no clear meaning, focus on the shape: flesh ⺼ beside 犮. Imagine a piece of flesh being pulled away by a hand (犮 suggests pulling), but the exact idea is lost.
For ハツ, imagine a heart (ハツ as in 心臓) being pulled from the flesh: ハツ -> ハツ, though this is only a sound hook.