Humphreys said after leaving the field during Bath's 30-9 win over Saracens that he was confident of playing at Murrayfield, but would leave the decision up to the medical experts.
'I've just wrenched a shoulder,' the 33-year-old said. 'I have to have a check on it, but I've got fairly good movement.' he said after the game.
But latest reports suggest the injury is subsiding, and Humphreys is hopeful to make the squad that travels to Scotland.
However, If Humphreys does not pass fitness tests, Hansen with few places to go at hooker. Pontypridd's Mefin Davies is the logical choice but he was unceremoniously dumped after the loss to Italy, while Bridgend youngster Gareth Williams also comes into contention.
If Humphreys doesn't make the trip to Edinburgh, the captaincy will revert back to Colin Charvis, who is expected to get the nod at No 8 ahead of Bath's Gavin Thomas.
Goal-kicker Stephen Jones is expected to step straight back into the starting lineup on his return from injury.
The Llanelli fly-half was ruled out of Wales' opening two Six Nations matches with a broken thumb, but the cast has come off and he should step past Ceri Sweeney and Iestyn Harris to play in the crucial Edinburgh clash.
Jones is 11 points away from taking over from Arwel Thomas as Wales' third-highest Test points-scorer, and has bagged 33 in two matches against the Scots.
'Stephen's been training with us and the thumb has stood up well,' national coach Steve Hansen said.
'Fitness won't be an issue because even with the injury, he's been able to train with us.'
The move is tough on Pontypridd youngster Sweeney, who played courageously against England last weekend, and it spells the end of league convert Harris' involvement in the playing 22.