Ankyloglossia

Ankyloglossia occurs as a result of the fusion of the lingual frenum to the floor of the mouth. However, complete fusion rarely occurs; a partial ankyloglossia or "tongue-tie" is a much more common condition. This leads to a myriad of speech problems such as lisping and stuttering. The treatment is to surgically sever the connection between the frenum and the floor of the mouth. 

Fissured Tongue

This condition is also referred to as scrotal tongue since the tongue often resembles the scrotum in this state. Here a transverse groove is present on the tongue from which numerous smaller grooves radiate all over the surface of the tongue. The condition is usually painless and the only problem is with the food debris gets stuck in the grooves. These have to be cleaned by gauze or a toothbrush.

Median Rhomboid Glossitis

This condition is a classic developmental disorder of the tongue. It is a failure of the developmental apparatus during the organogenesis of the fetus. A structure called "tuberculum impar" is supposed to withdraw when the two halves of the tongue come close to each other during development. When this does not happen, the structure gets trapped in between the two halves of the tongue, thereby creating an area, which looks like a bald patch on it. Median Rhomboid Glossitis has also been strongly linked with the fungal infection caused by Candida albicans, where the tongue has an ovoid patch just before the entry into the esophagus. Sometimes a flat-raised area can also be discerned. This condition is reportedly thrice as common in men as in women. The exact cause for this occurrence is not known, although hormonal links have been suggested.
There is no known treatment for MRG, though doctors have tried to administer anti-fungal agents with mixed results.