You did not specify what "these parts" are; it depends on whether it's an English or Western saddle. Common to both are the pommel, the seat, the cantle, the stirrups, the fenders, the cinch. Western saddles are much bigger than English ones and are used for entirely different purposes. Western saddles have a horn, that's one difference, and you really need a picture to see what the differences are.
seat
Saddle joints are primarily found in the thumbs of humans, where they enable a greater range of motion for activities like grasping and manipulating objects. They are not as common in other parts of the body.
There are over 20 parts to a western saddle. Which 4 do you want to know?
carriage comprises of parts-saddle and apron.
i think there is no palm rest. bty r u doing howrse?
gunpartscorp
A saddle seat is a concave seat, occaisonally with a ridge in the front, similar to that of a horse's saddle, found on a Windsor chair.
a small saddle pad made from goat or fox skin found on an iberian saddle
No, the hip joint is a ball-and-socket joint, not a saddle joint. Saddle joints are found in your thumb and sternoclavicular joint.
when it fits your horse
The saddle cloth is found in your howrses box and is automatically placed on that horse. Each howrse must fine its own saddle cloth.
Part of the saddle, possibly pedals, grips. Parts of the shifters, brake levers.