Saliva constantly flows from the salivary glands in your mouth. Sometimes, the chemicals in saliva can crystalise to form a tiny stone. Salivary gland stones ('salivary calculi') can become lodged in the duct (tube) leading from the salivary gland, blocking the flow of saliva into the mouth. This can cause swelling and pain in the gland.
Hub assemblies and wheel bearings. Located between the brake drums/discs and the drive axle, the hub assembly is mounted to the holding bracket of the chassis on the axle side. On the drum/disc side, the wheel is connected to the hub assembly via bolts. The wheel bearing itself is inside the hub unit.
In general an axle is a centre shaft for a rotating wheel or gear. So In general axle shaft is on which the hub of the wheel is mounted. there should essentially be two rear axles in a vehicle, for each of the left and right wheel/s (hub) In a rear wheel drive, on side on the axle is attached to the differential assembly and the other side is attached to the hub.