Cf. a variant root laṯˁat- ‘the bottom of the lips on the inside, the part of the lips that touches the roots of the teeth’ [BK 2 965].
The suffix -ān in labān-.
Note the translation ‘vésicule de musc’ (”musk vesicle”) in [Belot Arb.-Fr. 718] as well as labīḫ- ‘bladder, container for musk’ in [WKAS II 108].