Which area on the horse's body is referred to as the withers?

The withers is specifically identified as the area on a horse's body where the neck meets the back. It is a prominent ridge formed by the spinous processes of the thoracic vertebrae, and it serves as a critical anatomical landmark. This area is significant for many reasons, particularly in fitting saddles. The shape and height of the withers can greatly influence how a saddle fits, impacting both the comfort of the horse and the rider's effectiveness.

Understanding the withers is essential for horse care, riding, and training as it not only plays a role in saddle fitting but also in assessing a horse's overall conformation and movement. The other choices do not accurately define the withers; for example, the base of the tail is a separate area entirely, and the joint at the knee pertains to a different part of the horse's anatomy.