Unformatted text preview: Facial Muscles frontalis temporalis levator labii superioris masseter levator anguli oris depressor anguli oris depressor labi inferioris zygomaticus minor zygomaticus major orbicularis oris mentalis Muscles of the lips ‐ Subset of muscles of the face ‐ Include both intrinsic and extrinsic components Can be categorized according to orientation relative to OO: • Angular muscles – Oblique to the corners of the mouth • Vertical muscles – From above or below the lips • Transverse/parallel muscles – Course horizontally from origin Orbicularis Oris: • Ring of muscle within lips that forms a sphincter – intrinsic fibers • deep layer of concentric rings around lips • contraction closes, protrudes and rounds lips – extrinsic fibers • superficial layer into which other facial muscles converge 1. Transverse Muscles: • Buccinator – principal (and deepest) muscle of cheek – from pterygomandibular raphe/ligament (runs from hamulus to posterior mylohyoid line of mandible) and alveolar process of maxilla to corners of upper and lower lips – function – pulls corner of moth back and/or compresses lips and cheeks against the lips • Risorius – from superficial covering (fascia) of masseter to skin and mucosa of corner of mouth function ‐ moves corner of mouth laterally (smiling) 2. Angular muscles: • Levator labii superior (AKA quadratus labii superior) – from lower margin of orbit, zygomatic bone and maxilla to upper lip – function ‐ elevates upper lip • Zygomatic – Major • from zygomatic bone to corner of mouth • function ‐ draws corner of mouth up and laterally – Minor • from zygomatic bone to upper lip • function – elevation of upper lip • Levator labii superior alaeque nasi – from frontal process and infraorbital margin of maxilla to lateral cartilage of nose (nasal segment) and OO (lip segment) – function ‐ dilates nostrils and/or elevates upper lip • Depressor labii inferior (AKA quadratus labii inferior) – from front of mandible (upward and medially) to lower lip (just lateral to midline) – function ‐ draws lower lip down and laterally 3. Vertical Muscles: • Mentalis from front of mandible (lateral to midline) to OO and skin of chin function ‐ raises lower lip and wrinkles chin; helps in protruding and everting the lip for drinking; pouting • Depressor anguli oris (aka triangularis) – from oblique line (outer surface) of mandible to OO (at side of mouth) and upper lip – function ‐ may depress corner of lip or draw upper lip downward against lower lip • Levator anguli oris (AKA caninus) – from canine fossa of maxilla to angle of mouth (upper and lower) – function ‐ draws corner of mouth up; draws lower lip upward; can force lips together 4. Parallel Muscles: • Incisivus labii superioris – beneath levator labii superior – from canine fossa/eminence of maxilla to OO (upper) – function – pulls corner of mouth up and medially • Incisivus labii inferioris – beneath depressor labii superior – from mandible (near lateral incisor) to OO (lower) – function – pulls corner of mouth down and medially 5. Other Facial Muscles: • Platysma – Broad muscle covering most of front and side of neck and side of face – from connective tissue above clavicle to lower edge of mandible; also blends with fibers of lower lip and corner of mouth – function – draws skin of neck toward mandible or pulls lower lip down against alveolar process of mandible – – ...
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- Spring '10
- Muscles of the head and neck, upper lip, Levator anguli oris