PS

*muḫḫ- - brain, marrow (SED I No. 187; Kogan 2011: 220)

‘Brain’ is the only meaning to develop into ‘top of the head’, ‘head, skulľ, on the one hand, and ‘marrow’, on the other.

Akkadian
muḫḫu - top of the head; brain, marrow (CAD M₂ 172, AHw. 667)
Ugaritic
mḫ - top of the head, brain (WUS 181)
Hebrew
mōaḥ - bone-marrow (HALOT 567)
Jewish Palestinian Aramaic
mwḥ - skull, brain (DJPA 294)
Jewish Babylonian Aramaic
mōăḥ (mōḥā) - marrow, brain, head (Jastrow 740 )
Syriac
muḥḥā - skull; marrow, brain (LSyr. 379, SL 723)
Mandaic
muha - brain, head (MD 260 )
Arabic
muḫḫ- - brain (BK 2 1071)