Figure 2.

Left: Muscle complex involved in the function of the upper lip: seven pairs of facial and lip muscles connected to the circular orbicularis oris muscle (red: superficial fibers, blue; deep fibers); buccinator (1), levator labii superioris (2), levator labii superioris alaeque nasi (3), levator anguli oris (4), zygomaticus minor (5), zygomaticus major (6), and the risorius muscle (7). Middle: unilateral cleft lip with abnormal orientation and insertion of the orbicularis oris muscle, superficial muscle fibers (red) and deep muscle fibers (blue) are deficient. Right: bilateral cleft lip with abnormal orientation and insertion of the orbicularis oris muscle [Color figure can be viewed at wileyonlinelibrary.com]