Complex sentence: In the medulla, second-order fibers of the gracile and cuneate systems decussate and form the medial lemniscus, a tract of nerve fibers that leads the rest of the way up the brainstem to the thalamus.
Split into simpler sentences: In the medulla, second-order fibers of the gracile and cuneate systems decussate and form the medial lemniscus. The medial lemniscus is a tract of nerve fibers that leads the rest of the way up the brainstem to the thalamus.