Final answer:
Fibrous joints are characterized by a lack of synovial cavity and almost no movement, tightly held together by collagen fibers. Sutures, syndesmoses, and gomphoses are the three main types, providing stability and protection within different parts of the body.
Step-by-step explanation:
The type of structural joint that consists of dense fibrous connective tissue with collagen fibers that hold the joints firmly together without a synovial cavity is known as a fibrous joint. Fibrous joints are nearly immovable, with bones that are directly connected to each other. The three main types of fibrous joints include sutures, found only in the skull, syndesmoses, a type of joint connected by ligaments or interosseous membranes found between long bones of the forearm and leg, and gomphoses, the connection between a tooth and its socket in the jawbone.