Cleft Lip Anatomy
Cleft lip causes an abnormal appearance of both the lip and the nose. A better understanding of the normal anatomy of the lip and nose will help in understanding where clefts in the lip are found and how they affect a child’s appearance and function.
A baby’s upper lip, nose and roof of the mouth (palate) have completed formation by only 10 weeks into the pregnancy. The philtrum is the normal feature found in the middle portion of the upper lip seen below. The lip forms from three parts merging during pregnancy– the center part and the left and right side parts. The center and side parts of the upper lip meet at the philtral columns.
Normally the side portions of the lip meet and fuse with the center portion of the lip. The places where the center and side portions of the lip merge become the philtral columns (in blue above). These are the raised ridges extending the vertical length of the lip from the mouth up to the nose. The Cupid’s bow is the normal shape of the lip where the red and white portions of the upper lip meet (in red above). The philtral columns meet the red portion of the lip at the peaks of Cupid’s bow, as illustrated in the figure above.
The image above shows a baby a left unilateral cleft lip and palate on the right side of the figure. The philtral column and the peak of the Cupid’s bow are absent on the baby’s left side (the side of the cleft) because the cleft occurs through these structures. Note that in cleft lip and palate the cleft involves the floor of the nostril and gums. If both the left and right side fail to meet the center part of the lip a bilateral cleft lip forms as seen below.
In complete cleft lip the cleft extends up through the entire height of the lip and through the floor (bottom) of the nostril. The example case show complete unilateral and bilateral cleft lip and palate. In cleft lip and palate the cleft continues back through the bone in the upper jaw including the gums and the entire length of the palate. While the features of isolated cleft lip alone are striking, the involvement of the underlying facial bones in cleft lip and palate creates significant changes in the facial skeleton that further affect the appearance of the face.
In both unilateral and bilateral cleft lip, the majority of patients will have some involvement of the gums and palate. 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 cleft nasal anatomy page will further explain the changes in the nose.