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.
Wheel - Construction. 1  The rim is the outer edge of a wheel, holding the tire. [21] 2  In the 1st millennium BCE an iron rim was introduced around the wooden wheels of chariots. 3  The hub is the center of the wheel, and typically houses a bearing, and is where the spokes meet.