Lip reconstruction may be required after trauma or surgical excision. The lips are considered the beginning of the oral cavity and are the most common site of oral cancer. Any reconstruction of the lips must include both functional and cosmetic considerations. The lips are necessary for speech, facial expression, and eating. Because of their prominent location on the face, even small abnormalities can be apparent.
Relevant anatomy
Superficial
The upper and lower lips include the vermilion border. This is the juncture between the lighter skin and the redder tissue (vermilion) that we commonly call the lip. This tissue is red because the skin is thin and underlain by large numbers of capillaries. The vermilion is different both from the oral mucosa and from regular skin, as it includes a cornified stratum corneum and lacks salivary glands, unlike the oral mucosa, but is thinner and more vascularised than regular skin, and lacks both hair follicles and sweat glands.
The pattern of the vermilion border defines the areas of the lip: Philtrum-two vertical lines extending from the base of the nose to the central vermilion border, forming the bow of the central upper lip; Commissures-where the upper and lower lips meet laterally; Lateral upper lip-between philtrum and commissure.
Deep
The primary underlying muscle of the lips is the orbicularis oris. This circumferential muscle underlies the upper and lower lip. The muscle contracts the lips to allow for expression, speech, chewing and swallowing. It also maintains tone to prevent objects from falling out of the mouth (referred to as oral competence). Disruption of the circular nature of this muscle can have a significant effect on oral function.
In addition, there are other muscles both above and below the lips that attach either to the orbicularis oris or to the fibrous bands extending from the commissures.
Nerve supply
The muscles are supplied by two cranial nerves, the facial nerve and the trigeminal nerve.
The upper lip receives its sensibility from the infraorbital nerve, which is a branch of the maxillary division of the trigeminal nerve. The infraorbital nerve provides sensation to the upper lip, cheek, ala, and nasal sidewall. The sensory innervation of the lower lip is provided by the mental nerve. The mental nerve is the terminal branch of the inferior alveolar nerve, which in turn is a branch of the mandibular division of the trigeminal nerve.
Blood supply
The muscles and overlying skin are supplied by branches of the external carotid artery (the facial artery and Superior labial artery.
Lymph drainage
Submandibular/submental-Under the chin
Principles of Reconstruction
Preserve sensation of the lips
Maintain oral competence
Continuity of vermilion border
Sufficient oral access (not too small, microstoma) Adequate lip appearance
Types of defects
Lip defects are classified by their depth and their size. Superficial defects involve the skin and vermilion, and leave the underlying muscles, nerves and arteries undisturbed. Deep/full thickness defects include the underlying muscles, primarily the orbicularis oris. The nerve and blood supply may also be affected if the defect is large. Regardless of the depth or size, a successful lip reconstruction considers the five principles and the effect that the reconstruction has on the surrounding tissue.
Superficial upper lip reconstruction
Successful reconstruction of the upper lip attempts to maintain the anatomic relationship of the philtrum (central portion of upper lip) and the base of the nose. Not distorting the commissure is also desirable for upper lip reconstruction.
Central lip
Straight line closure-may cause a pulling up of the vermilion border as it heals
Advancement flaps-these pull in skin from the sides and heal best when the defect is the full height of the upper lip, can come in from one or both sides (single or double advancement)
Lateral lip
Straight line closure
A-T closure-extends the defect up to the philtrum or down to the vermilion border to make the scar less noticeable. Single Advancement-incision along vermilion border to pull tissue in from the lateral aspect Rotation flaps-rotate in tissue from the cheek
Superficial lower lip reconstruction
The anatomic requirements are not as limiting for the lower lip because the surrounding anatomy is less complex. The considerations include maintaining a non-distorted vermillion border, hiding incisions in the horizontal crease of the chin, and not distorting the commissure.