A root canal is a narrow passage in a root through which the nerves and blood vessels enter the tooth. They travel from the end of the root through the root canal on their way to the pulp chamber at the centre of the tooth.
The pulp chamber is the space in the crown of a tooth, which houses the nerves and blood vessels (the pulp). They have entered the tooth through the root canals. The pulp chamber is like a nerve and blood vessel terminus, where their inward journey ends and the return journey back to the end of the root begins. The nerves send pain signals to the brain in response to the presence of decay or injury. The blood vessels supply the nutritional needs of the tooth.