Nervous tissues are found in the brain, spinal cord, and peripheral nerves. Neurons are sensitive to certain types of changes in their surroundings. Because neurons communicate with each other and with various body parts, they coordinate, regulate, and integrate many body functions. Neurons are individaul nerve cells. Nerve - specifically, the spinal cord.
Nerves are collections of neurons and the largest nerve in the body is the spinal cord.
There are many hundreds of neurons in this picture.