Patients with cleft lip and palate have the most severe changes in the appearance of the lip and nose because the separation in the bones of the gums and palate creates a wide gap that separates the lip segments and drastically changes the shape of the nose. The figure below illustrates some important parts of the nose that are affected by clefts of the lip.
As you can see in the figure below, the degree to which the nose is deformed by the cleft of the lip relates to the severity of the cleft of the lip. For the nose, the involvement of the gums and palate have the most dramatic effect on the nasal shape. This is because the cartilage and skin of the nostril (ala) is shaped like an upside down U with the ends of the U sitting on the bone on each side of the cleft. The farther away the ends of the cartilages are from one another, the more severe the deformity of the nostril will be.
Similarly, the nasal tip and the columella (the skin between the two nostrils) are also affected by the severity of the cleft. The columella is typically shorter on the side of the cleft in unilateral cleft lip. The nasal tip is depressed on the side of the cleft causing significant asymmetry.