AESTHETIC FOCUS of the ageing

With an ever popular option for those seeking more youthful looks it is vital that practitioners have a proper understanding of anatomy. In the first of our two-part special focus on lipsDr Foutsizoglou provides a comprehensive guide to function and anatomy.

BY SOTIRIOS FOUTSIZOGLOU

he are pliable, mobile, muscular folds that encircle the opening of the oral cavity. They contain the orbicularis oris and superior and inferior labial vessels and . The lips are covered externally by skin and internally by . A sagittal cut through the lip can reveal the layers of soft tissue that form this relatively simple anatomical structure. That is, from Tsuperficial to deep: skin, superficial fat compartment, , deep fat compartment and mucosa. The lips are used for grasping food, sucking liquids, clearing food from the oral vestibule, forming speech, osculation, and controlling the size of the oral aperture.

Functions of the lips as part of the tactile senses. Lips are very sensitive to touch, warmth and cold. Food intake Lips serve to close the airtight shut, to hold food and drink inside. Because of their high number of endings, the lips are an erogenous zone. Mastication The lips therefore play a crucial role in Lips help to hold food between upper and osculation and other acts of intimacy. lower teeth during chewing.

Facial expressions Figure 1: Anatomical landmarks of the lip. Deglutition The lips form an integral part of facial Lips push food into the oral cavity proper expression e.g. smiling, frowning, etc. (Greek for love-charm), that extends from during the voluntary phase of the external , separating the where it is ingested and prepared for , to the vermillion border – the in the and small Lip anatomy sharp demarcation between the coloured intestine. The upper lip lies between the nose and edge of the lip and surrounding skin. The the orifice of the oral cavity. Laterally lower lip lies between the mouth and the Articulation the lips are separated from the labiomental groove, which separates the The lips serve for creating different sounds by the nasolabial grooves that extend lower lip form the [1]. The upper and – mainly labial, and labiodental consonant from the nose and pass approximately lower lips are continuous at the angles of sounds. 1 cm lateral to the angles of the mouth. the mouth or oral commissures (Table 1). These grooves or folds are easier to In adults the outer lip skin is thicker and Tactile observe when smiling. The upper lip has contains , sweat glands, and sebaceous glands. The edges of the lips are covered The lip has many nerve endings and reacts an infranasal depression, the

TABLE 1: LIP TOPOGRAPHY (ALSO SEE FIGURE 1)

• Vermillion: the red part of the lips. It is covered with a specialised stratified squamous , which is in continuity with the of the gingivolabial groove. Confusingly, the vermillion itself is also often referred to as the lips.

• Vermillion border: the demarcation line that separates the vermillion lip from the surrounding skin. It is also called the vermillion-cutaneous junction (V-C junction).

• Cupid’s bow: the upper central vermillion border at the base of the philtral columns. In a frontal view, this border resembles an archer’s bow, which curves medially and superiorly from the commissures to the paramedian peaks located at the bases of the pillars of the philtrum (crista philtrae) with an inferior convexity lying between those peaks [2].

• Oral commissure: The landmark where the lateral aspects of the vermillion of the upper and lower lips join [3].

• : A fibromuscular condensation where the extrinsic and intrinsic muscles of the mouth meet. The modiolus lies about 10-12mm superolateral to the corner of the mouth and is shaped in the form of a hub of a cart wheel. It is contributed to by the orbicularis oris, buccinator, , depressor anguli oris, zygomaticus major, , platysma, . The modiolus is very important for the stability and strength of the oral aperture and movement of the mouth.

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with reddish skin, called the vermillion, numerous hair follicles. As a ‘keratinised’ function. The contraction of this portion of and are abundantly provided with or waterproofed component of the skin, the muscle is responsible for accentuation sensitive nerve endings. The vermillion stratified squamous epithelium provides of vertical fine perioral wrinkles or is a transition layer between the outer, substantial protection against friction, ‘smoker’s lines’. hair-bearing tissue and the inner mucous microbial invasion and desiccation. As the Orbicularis oris is supplied mainly by membrane. The skin of the vermillion is epithelium approaches the so-called red the superior and inferior labial branches made up of three to five cellular layers area of the lip, the epithelium becomes of the facial , the mental and and is very thin compared to the skin non-keratinised stratified squamous infraorbital branches of the maxillary on the rest of the , which is typically epithelium. This type of epithelium is artery, and the transverse facial branch arranged in 16 cellular layers. The mucous designed for protection and lubrication of the superior temporal artery. Its membrane of the lip is full of capillaries during chewing and swallowing. nerve supply comes from the buccal and that are close to the translucent surface of mandibular branches of the . the vermillion, giving it its characteristic Orbicularis oris reddish colour. In newborn infants the Sensory innervation The orbicularis oris muscle, the lip inner surface is much thicker, with muscle, is a broad elliptical muscle sebaceous glands and minute projections around the mouth (Figure 2). When the Upper lip called papillae. These structural orbicularis oris is tonically contracted, the Superior labial nerve from the infraorbital adaptations seem to aid the process of mouth is closed, whereas active (phasic) nerve, one of the major cutaneous sucking [4]. contraction causes the mouth orifice branches of the (CNV2), The upper lip (labium superioris) is to become narrower as when kissing the intermediate division of the trigeminal superior in name only since it is actually or whistling. Its lateral fibres join the nerve. somewhat smaller than its partner, the modiolus, a chiasma of held lower lip (labium inferioris). In an ideal together by fibrous tissue, located lateral Lower lip world, the lower lip vermillion show and slightly superior to each angle of the from the inferior alveolar should be Phi times greater than the mouth. nerve, a major branch of the mandibular upper vermillion. However, that ratio can Orbicularis oris consists of two nerve (CNV3), which arises in the vary dramatically with ethnic background, distinct parts, the pars marginalis and mandibular canal and emerges from and even from individual to individual pars peripheralis, which differ in location the mental foramen normally located within the same ethnic group. and function [5]. Anatomical studies inferiorly to the second premolar The vermillion or ‘dry’ part of the lip have shown that pars peripheralis fibres in the . Those practitioners who is not hairy and does not have sweat or decussate at midline and insert into the use mental blocks for injections into the . Therefore, it does not have contralateral philtral ridge, whereas pars lower lip should be aware of the anatomical the usual protective layer of sweat and marginalis fibres form a continuous band changes associated with loss of mandibular body oils which keep the skin smooth, from modiolus to modiolus. teeth. Following complete loss or removal inhibit pathogens, and regulate warmth. of mandibular teeth, the alveoli begin to For these reasons, the lips dry out faster Pars marginalis and become chapped more easily. On the fill in with and the alveolar process It is developed to a unique extent in other , the epithelium of the mucosal begins to resorb. Gradually the mental human lips and is closely associated lip or ‘wet’ part of the lip is moistened by foramen lies near the superior border of with speech. In each quadrant, the labial and other glands associated with the body of the mandible. In extreme cases, pars marginalis consists of a single the oral cavity. the mental foramina disappear, exposing (occasionally) double band of narrow- The muco-cutaneous line or ‘wet-dry the mental nerves to injury. Pressure from diametre muscle fibres lodged within border’, formed where the upper and a dental , resting on an exposed the vermillion zone of the lip. At their lower lips meet, marks the transition nerve, may produce pain during eating. Loss medial end, the marginal fibres meet and between the vermillion lip and the of all the teeth also results in a decrease interlace with their contralateral fellows mucosal lip. The skin of the lips is in the vertical facial dimension and and then attach to the of the categorised as stratified squamous mandibular prognathism [1]. vermillion zone a few millimetres beyond epithelium, or flattened tissue cells. the median plane. At their lateral ends, The outer lip skin is keratinised Blood supply the fibres converge and attach to the stratified squamous epithelium with Superior and inferior labial arise deepest part of the modiolar base along from the . They are located a horizontal strip level with the buccal 1mm posterior to the mucocutaneous angle [6]. border or – the transition between the mucosa and skin of the Pars peripheralis lip. The labial arteries lie deep to the It is located in the cutaneous lip. It is the orbicularis oris muscle and anastomose thinner and more peripheral portion of with each other to form an arterial ring the muscle [7]. Pars peripheralis fibres [8]. The pulse of these arteries can be are reinforced directly by the buccinator, palpated by grasping the upper or lower levator anguli oris, and the superficial part lip lightly between the first two digits. of zygomaticus major in the upper lip, and from buccinators and depressor anguli oris in the lower lip. Its most peripheral Lymphatic drainage fibres are connected with the maxillary Upper and lower lateral lip drain primarily

Figure 2: Anatomy of normal orbicularis oris muscle: pars bone and nasal septum above and with into the submandibular nodes, whereas marginalis (blue) and pars peripheralis (red). the mandible below. It has a dilatory lymph from the medial part of the lower

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Figure 3: Smile arc and teeth symmetry should be examined. Figure 4: Lips showing soft tissue changes.

lip passes initially to the submental lymph affecting the smile arc. References nodes. • Tooth loss causes 1. Moore KL, Dalley AF. Clinically Oriented Anatomy. 4th Edition. Lippincott Williams & Wilkins; 1999. resorption and cortical bone loss 2. Hennekam RC, Cormier-Daire V, Hall J, et al. Elements Lip assessment / evaluation leading to decreased anterior lip of morphology: standard terminology for the nose projection (lips look thinner and and philtrum. Am J Med Genet A 2009;149A:61-76. 3. Carey JC, Cohen MM Jr, Curry C, et al. Elements Lip-teeth relationships inverted). of morphology: standard terminology for the • Dentures affect the position of soft lips, mouth, and oral region. Am J Med Genet A • The maxillary incisal edge curvature tissues and lips. 2009;149A:77-92. should be parallel to the curvature of 4. www.britannica.com the lower lip in an ideal smile arc. 5. Azib N, et al. Anatomy and Lip Enhancement. Paris, Soft tissue changes France; E2e Medical Publishing / Master Collection 4; 2011. • Epidermal thinning with flattening of • At rest, there should be 2-4mm 6. Standring S. Gray’s Anatomy: The Anatomical Basis of vertical exposure of the maxillary the dermal-epidermal junction. Clinical Practice. 41st Edition. Elsevier; 2016. incisors in relation to the upper lip. • Loss of and elasting leading 7. Trevidic P, Sykes J, Criollo-Lamilla G. Anatomy of the lower face and botulinum toxin injections. Plastic to reduced elasticity of skin. Reconstruct Surg 2015;136:55. Tooth proportions and symmetry, • Reduction in glycosaminoglycans 8. Brown DL, Borschel GH. Michigan Manual of Plastic gingival aesthetics, the smile arc, width leading to water loss and dry skin. Surgery. Lippincott Williams & Wilkins; 2004. of the smile, buccal corridors, incisal • Reduction in soft tissue volume, and gingival display, dental integrity, and elasticity and repeated perioral occlusal relationship should be all be muscle activity leading to perioral Don’t miss the next issue of examined as part of the lip assessment. rhytids. PMFA News which will feature an • Perioral fat compartments become overview of the clinical aspects Chronological lip changes lipodystrophic and ptotic. of lip augmentation by Dr Nestor Demosthenous. Structural lip changes • Maxillary retrusion in both dentate • Upper lip loses its volume, lengthens and edentulous individuals. and inverts. • Maxilla rotates clockwise. • Lower lip becomes thinner and rolls • Decrease in the maxillary angle inward. and height leading to posterior • The intercommissural width positioning of the lip and deepening becomes smaller. of the nasolabial folds (NL). • Commissures drop. • Decreased display of the maxillary Mandible anterior teeth. • Exposure of mandibular anterior • Height of ramus and mandibular teeth increases. body length decrease with age. • Philtrum columns flatten and • Loss of mandibular volume ‘splay’ as they approach the upper contributes towards laxity of vermillion border. platysma. • Vermillion border becomes thinner. • Mandibular angle increases. This Dr Sotirios Foutsizoglou, • Partial loss of Cupid’s bow. may result in blunting of jawline Cosmetic Surgeon and Founder of SFMedica, • Perioral rhytids, NL folds and London. definition. labiomental (LM) folds become more E: [email protected] The dentition noticeable. Declaration of competing interests: • Curves of the lips are lost. None declared. • Chronological results • Lips become more dry. in flattening of the incisal edges

pmfa news | DECEMBER/JANUARY 2017 | VOL 4 NO 2 | www.pmfanews.com