How does the nerve cord of chordates differ from chord other animals?

In most animals with nerve cords, such as flatworms, roundworms, and annelids, the nerve cord is typically a ventral structure located close to the digestive tract. However, in chordates, the nerve cord is a dorsal structure that runs along the dorsal midline of the body and is derived from the notochord, a unique defining feature of chordates. This positioning is a synapomorphic trait and a key factor distinguishing chordates from other animals.