Muscles of facial expression - PDF document

Muscles of facial expression Lecture for Dental mechanics - First year Anatomy Shaista Afroz Associate professor Prosthodontics Z A Dental college, Aligarh Muslim University • The muscles of facial expression are located in the subcutaneous tissue (under the skin), • Origin: from bone or fascia, • Insertion: onto the skin. • Only group of muscles that insert into skin. â

€¢ By contracting, the muscles pull on the skin and exert their effects. • Can broadly be split into three groups: • Orbital • Nasal • Oral ORBITAL Orbicularis oris Mentalis Buccinator Masseter Aa Zygomatics major NASAL ORAL Orbital Group Muscles associated with the eye socket. • These muscles control the movements of the eyelids, • Protect the cornea from damage. 1. O

rbicularis Oculi • Surrounds the eye socket and extends into the eyelid. • Three distinct parts – palpebral, lacrimal and orbital. • Origin: the medial orbital margin, the medial palpebral ligament, and the lacrimal bone. • Insertion: the skin around the margin of the orbit, and the superior and inferior tarsal plates. • Actions: • Palpebral part – gently closes t

he eyelids. • Lacrimal part – involved in the drainage of tears. • Orbital part – tightly closes the eyelids. • Innervation – Facial nerve (CN VII, temporal and zygomatic branches) Orbicularis oris Corrugator supercilli B D Chaurasia’s HUMAN ANATOMY, head - neck brain Volume 3 2. Corrugator Supercilii • Smaller muscle, and is located posteriorly to the orbiculari

s oculi muscle. • Origin: the superciliary arch, running in a superolateral direction. • Insertion: into the skin of the eyebrow. • Actions – Acts to draw the eyebrows together, creating vertical wrinkles on the bridge of the nose. • Innervation – Facial nerve. Nasal Group Associated with movements of the nose, and the skin around it. 1. Nasalis • Largest of the nasal

muscles. • It is split into two parts; transverse and alar. • Origin: Both portions of the muscle originate from the maxilla. • Insertion: The transverse part attaches to an aponeurosis across the dorsum of the nose. • The alar portion of the muscle attaches to the alar cartilage of the nasal skeleton . • Actions: The two parts have opposing functions. • The transverse

part compresses the nares, • The alar part opens the nares. • Innervation: Facial nerve. 2. Procerus • The most superior of the nasal muscles. • It also lies superficially to the other muscles of facial expression. • Origin: from the nasal bone • Insertion: into the lower medial forehead. • Actions: Contraction of this muscle pulls the eyebrows downward to produce tran

sverse wrinkles over the nose. • Innervation: Facial nerve. 3. Depressor Septi Nasi • This muscle assists the alar part of the nasali in opening the nostrils. • Origin: It runs from the maxilla (above the medial incisor tooth) • Insertion: To the nasal septum. • Actions: It pulls the nose inferiorly, opening the nares. • Innervation: Facial nerve. B D Chaurasia’s HUMA

N ANATOMY, head - neck brain Volume 3 Procerus Nasalis Depressor Septi Nasi Oral Group • These are the most important group of the facial expression – responsible for movements of the mouth and lips as during singing and whistling, and add emphasis to vocal communication. The oral group of muscles consists of the orbicularis oris , buccinator, and various smaller muscles. Mu

scles around the lips: 1. Orbicularis Oris • The fibres of the orbicularis oris enclose the opening to the oral cavity. • Origin: Arises from the maxilla and from the other muscles of the cheek. • Insertion: It inserts into the skin and mucous membranes of the lips. • Action: Purses the lips. • Innervation: Facial nerve. 2. Buccinator • This muscle is located between t

he mandible and maxilla, deep to the other muscles of the face. • Origin: It originates from the maxilla and mandible. • Insertion: The fibres run in an inferomedial medial direction, blending with the orbicularis oris and the skin of the lips. • Actions : The buccinator pulls the cheek inwards against the teeth, preventing accumulation of food in that area. • Innervat

ion : Facial nerve. • There are other muscles that act of the lips and mouth. Anatomically, they can be divided into upper and lower groups: Lower group 3. Depressor anguli oris , • Origin: oblique line of mandible • Insertion: skin at the angle of the mouth and fuses with the orbicularis oris • Actions: Draws angle of mouth downward and laterally • Innervation : Facial

nerve. 4. Depressor labii inferioris • Origin: anterior part of oblique line of mandible • Insertion: lower lip at midline, fuses with the muscles from the opposite side • Actions: draws lower lip downward • Innervation : Facial nerve. 5. Mentalis. • Origin: mandible inferior to incisor teeth • Insertion: skin of chin • Actions: elevates and protrude lower lip • Inner

vation : Facial nerve. Upper group 6. Risorius, • Origin: Fascia on the masseter muscle • Insertion: skin • Actions: Retracts angle of mouth • Innervation : Facial nerve. 7. Zygomaticus major, • Origin: posterior aspect of lateral surface of zygomatic bone • Insertion: skin at the angle of the mouth • Actions: pulls the angle upward and laterally as in smiling • Inn

ervation : Facial nerve. 8. Zygomaticus minor, • Origin: anterior aspect of lateral surface of zygomatic bone • Insertion: upper lip medial to its angle • Actions: elevates the upper lip • Innervation : Facial nerve. 9. Levator labii superioris, • Origin: infraorbital margin of maxilla • Insertion: skin of upper lateral half of upper lip • Actions: elevates upper lips,

form nasolabial groove • Innervation : Facial nerve. 10. Levator labii superioris alaeque nasi • Origin: frontal process of maxilla • Insertion: upper lip and alar cartilage of nose • Actions: elevates upper lip and dilate nares • Innervation : Facial nerve. 11. Levator anguli oris . • Origin: maxilla just below infra orbital foramen • Insertion: skin of angle of m

outh • Actions: elevates angle of mouth and form nasolabial groove • Innervation : Facial nerve. B D Chaurasia’s HUMAN ANATOMY, head - neck brain Volume 3 Recommendation • B D Chaurasia’s HUMAN ANATOMY, head - neck brain Volume 3 • Ash, Major M. Wheeler's Dental Anatomy, Physiology, and Occlusion . Philadelphia: W.B. Saunders • https://www.youtube.com/watch?v=EUVD8cwK