There can be a number of reasons for this, probably the biggest being bad oral hygiene. Try improving that and leave the corners of your mouth alone; don't start rubbing it with all kinds of lotions. An exception might be a hydrating lotion, but make sure it does that and nothing else.
If the splits don't improve seek the advice of a professional medical practitioner.
The Elite's jaw splits open because they are so angry that they couldn't be in control.
Delta.
It usually means you have something on the corner of your mouth.
When it meets with the mouth witch splits the river up.
a split gland is a gland that splits when you scream to loud.
Angular cheilitis (also called perlèche, cheilosis or angular stomatitis) is an inflammatory lesion at the labial commissure, or corner of the mouth, and often occurs bilaterally. The condition manifests as deep cracks or splits. In severe cases, the splits can bleed when the mouth is opened and shallow ulcers or a crust may form.
If you have a cut on the corner of your mouth that won't heal, you should see a doctor. They can determine the cause of the lack of healing.
a kufuzelanter
cheilosis: crack like sores at the corner of the mouth. (lip disease)
zygomaticus
Actually the joint is found at the corner of your jaws.
Lesions at the corners of the mouth are an indication of riboflavin deficiency (vitamin B2).