PIE origins of 'sinus'.....

[Dennis Philps]

Does anyone happen to know the PIE root(s) of 'sinus' (a curvature,
flexure, bend; a cavity within a bone, esp. within the bones of the face,
connecting with the nasal cavities) and the obsolete 'sinuate' "to creep or
crawl in a winding course", which have come down to English via Latin
and/or French?

Given that the verb 'snake' (<*sneg-) is defined as "to follow a twisting
or winding course; creep, crawl", is the hypothesis of an etymological link
with PIE *sneg- "to creep, crawl" tenable, reflexes coming down in
zero-grade form (*sn-) via Germanic and in full-grade form (*sVn-) via
Latin/French?

Many thanks,
Dennis.