There is a groove in the middle of the tongue, mostly known as cracked tongue or grooved tongue, which is mainly caused by congenital developmental abnormalities, vitamin and trace element deficiencies in the body, and poor hygiene, etc., as follows: 1, congenital developmental abnormalities: some people have congenital developmental defects on the tongue surface, which can lead to a relatively deep groove in the middle of the tongue body. 2, vitamin and trace element deficiencies in the body: common in people who have been picky and paranoid for a long time. The first thing you need to do is to take a look at the tongue. At this point, brush your teeth and rinse your mouth carefully, and while brushing your teeth, gently brush the surface of your tongue with the bristles to remove the food residue and bacteria from the surface of your tongue.