Tessier cleft Abnormality of mouth shape Transverse facial cleft 2011-06-06T05:03:42Z Lateral facial cleft HP:0100731 A horizontal cleft of the face, varying from slight widening of the mouth, to a cleft extending to the ear. UMLS:C4020954 Usually, these clefts are unilateral and do not extend beyond the anterior border of the masseter. Transverse clefts are thought to develop either due to failure of the maxillary and mandibular processes to fuse or a disruption in the processes after fusing.