Fatty acid desaturase that catalyzes the introduction of the third double bond at the Delta(10) position in d18:3Delta4,8,10 triunsaturated sphingolipid long fatty acid chains. The cytochrome b5 domain probably acts as the direct electron donor to the active site of the desaturase. a (4E,8E)-4-sphinga-4,8-dienine ceramide + 2 Fe(II)-[cytochrome b5] + 2 H(+) + O2 = 2 Fe(III)-[cytochrome b5] + 2 H2O + N-acyl-(4E,8E,10E)-sphingatrienine Lipid metabolism; sphingolipid metabolism. The histidine box domains may contain the active site and/or be involved in metal ion binding. Belongs to the fatty acid desaturase type 1 family.