The venom is secreted by glands located behind the eyes. Each fang has a canal along the front edge. The fangs are located at the front of the mouth and are permanently in place. Cobras strike upwards with the snout curled back so the fangs protrude. When the fang penetrates, venom is squirted down the fang by muscles that squeeze the venom glands.
Some cobras have the ability to spread their hood.
The ribs in the neck region are movable and are swung out to stretch the loose skin of the neck, like the ribs of an umbrella stretching out fabric. The hood is spread when the animals are disturbed or excited. Cobras are used in performances of snake charmers. The snakes are not reacting to the music. Since snakes cannot hear, but rely on vibrations, they are not listening to the snake charmer's music.