# Cleft lip

Cleft lip

The abnormalities in cleft lip are the direct consequence of disruption of  the muscles of  the upper lip and nasolabial region. The muscle continuity is disrupted, leading to the cleft lip and also abnormal insertions of  the muscle at the cleft edge. - The e ff ect of  this can be seen on the nasal septum and the nose itself. - Unilateral cleft lip In the unilateral cleft lip, the muscle rings are disrupted on - one side, resulting in an asymmetric upper lip and/or nose. This involves the external nasal cartilages, nasal septum and anterior maxilla (premaxilla). This influences the mucocuta - neous tissues, causing a displacement of  nasal skin onto the lip and a retraction of  labial skin, as well as changes to the vermil - ion and lip mucosa. All these changes need to be considered in planning the surgical repair of  the unilateral cleft lip. (a) Bilateral cleft lip In the bilateral cleft lip the disruption is greater but often symmetrical. Muscular continuity is disrupted bilaterally , producing a flaring of the nose (caused by a lack of nasolabial muscle continuity), a protrusive premaxilla and an area of skin in front of  the premaxilla devoid of  muscle, known as the prolabium. As in the unilateral cleft lip, the muscular, carti laginous and skeletal deformities influence the mucocutaneous tissues, which must be respected in planning the repair of  the bilateral cleft lip. 

A
B
C
(b)
Figure 50.4
(a)
Schematic representation of disruption of the nasola
bial and bilabial muscle chains in unilateral (right) cleft lip. A, nasola
bial; B, bilabial; C, labiomental.
(b)
Unilateral cleft lip before muscular
reconstruction (courtesy of William P Smith).