Original Articles: PDF OnlyAnatomy of the Orbicularis Oris Muscle in Incomplete Unilateral Cleft Lip Based on Histological ExaminationDado, Diane V. M.D.*,†; Kernahan, Desmond A. M.D.†Author Information *From the Division of Plastic Surgery, Loyola University Medical Center, Maywood †From the Division of Plastic Surgery, The Children's Memorial Hospital, Chicago, IL. Annals of Plastic Surgery: August 1985 - Volume 15 - Issue 2 - p 90-98 Buy Abstract Histological sections of tissue removed from three incomplete cleft lips at the time of repair, a nature's scar line, and a noncleft lip were examined serially in the horizontal and saggital planes. The findings confirm previous data from electrical stimulation studies of clefts and a three-dimensional histological model of the orbicularis oris in a complete cleft lip. There is a disorganized mass of muscle fibers with numerous dermal insertions and no evidence of well-defined muscle bundles running parallel to the cleft margins. The fibers are somewhat hypoplastic and less abundant than those present in noncleft lips. © Williams & Wilkins 1985. All Rights Reserved.