B

Figure 1 (A) Cheek relaxing incisions to allow opposing advancement flap repair of the lower lip by Celsus in the first century A.D. (B) Repair of upper lip with distant flap from arm by Tagliacozzi. Source: From Refs. 4a, 4b.

a mucosal surface specially adapted to external exposure. The mucocutaneous or anterior vermilion line is normally very well defined, though may become a little faded with solar exposure and aging. The philtrum is a structure special to the central region of the upper lip that is created by the fusion of the frontonasal and bilateral maxillary processes during embryologic development and can be difficult to duplicate in reconstruction.

The orbicularis oris is the muscle that makes up the body of both lips. It functions as a sphincter that regulates mouth opening and retention of oral materials. This muscle courses horizontally through both the upper and lower lips and connects in a crisscross or decussated fashion immediately lateral to the oral commissure on both sides. The muscles of facial expression that affect the lip lie deep in the cheeks and chin and exert their respective influence.

The upper and lower labial arteries are the principle source of blood supply to the lips. For purposes of reconstruction, it is important to understand that they derive from the facial artery on each side and course horizontally in the submuco-sal plane, just beyond the posterior vermilion line (the last part of the vermilion that is seen when the lips are held open). The labial arteries can actually be detected by palpation of the posterior surface of the lip in most patients. An

Figure 2 (A) Patient with normal upper and lower lips. Note strong outline for lip complex with melolabial and mental creases. Note the fine rhytids that course in a "radiant" pattern about the mouth opening. (B) Note progressive decrease in height of more lateral portions of upper lip. The melolabial crease passes much close to the free margin of the lip near the oral commissure.

Figure 2 (A) Patient with normal upper and lower lips. Note strong outline for lip complex with melolabial and mental creases. Note the fine rhytids that course in a "radiant" pattern about the mouth opening. (B) Note progressive decrease in height of more lateral portions of upper lip. The melolabial crease passes much close to the free margin of the lip near the oral commissure.

anatomic study of the arterial structures of the lower face by Park reveals a variable pattern of anastamosing vessels across the lower lip and chin with a horizontally oriented mental branch in many as well as one or more vertically oriented labiomental branches (5).

Motor innervation to the upper lip is primarily via the buccal branch of the facial nerve and to the lower lip primarily by the marginal mandibular nerve branch. Sensory innervation of the upper lip is via the infraorbital nerve and to the lower lip via the mental nerve.

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