**Lips of the groove become firmly opposed and shorten
**Lips of the groove become firmly opposed and shorten
−
**Lips become inverted and twisted around the axis of the right lip of the groove, drawing the reticular mucosa over the right lip
+
**Lips become inverted and twisted around the axis of the right lip of the groove, drawing the reticular mucosa over the right [[Lips - Anatomy & Physiology|lip]]