Muscles of Facial Expression PDF

Happiness - characterized by a smile, raised cheeks, and crow's feet around the eyes Sadness - features a frown, downturned lips, and drooping eyelids Anger- marked by furrowed brows, tightly pressed lips, and flared nostrils Surprise: Involves raised eyebrows, wide-open eyes, and...

Happiness - characterized by a smile, raised cheeks, and crow's feet around the eyes Sadness - features a frown, downturned lips, and drooping eyelids Anger- marked by furrowed brows, tightly pressed lips, and flared nostrils Surprise: Involves raised eyebrows, wide-open eyes, and a dropped jaw Fear- similar to surprise but more pronounced, with wide eyes and a tense, often raised, forehead Disgust - characterized by a wrinkled nose, raised upper lip, and squinted eyes Arrogance /superiority - shown with one side of the mouth raised (half-smile or smirk) and often a combination of other expressions Scalp muscle - Occipitofrontalis Long and wide muscle of the scalp Spanning from the eyebrows to the superior nuchal lines of occipital bone Together with temporoparietalis, it comprises the epicranial group of the muscle of expression Consists of occipital bellies and occipital bellies, each containing a pair of quadrangular muscle heads Connected by a thick fibrous sheath called epicranial aponeurosis (galea aponeurotica) ○ A connective tissue layer that forms the third and middle layers of the scalp. It’s a structure that connects the frontal and occipital parts of the occipitofrontalis muscle Function - elevate the eyebrows and wrinkle the forehead skin with its frontal part, and to retract the scalp with its occipital part Origin: ○ Frontal belly (frontalis): skin of eyebrow, muscles of forehead ○ Occipital belly (occipitalis): lateral ⅔ rd of superior nuchal line Insertion: Epicranial aponeurosis  Action: ○ Frontal belly: elevates eyebrows, wrinkles skin of forehead ○ Occipital belly: retracts scalp Innervation: ○ Frontal belly: temporal branches of facial nerve (CN VII) ○ Occipital belly: posterior auricular nerve (branch of facial nerve CN VII) Blood supply: superficial temporal, ophthalmic, posterior auricular and occipital arteries Orbit & eyebrow muscles Orbicularis oculi ○ Orbital ○ Palpebral ○ Origin: medial wall of the orbit ○ Insertion: circular path around orbit ○ Action: Closes eye Also assists in tear transport and drainage Controls spontaneous and reflex blinking (palpebral portion) Forced closure: orbital and palpebral portion ○ Innervation: CN VII (facial nerve) ○ Corrugator supercilia ○ Origin: medial end of superciliary arch of the frontal bone ○ Insertion: skin deep to medial eyebrow ○ Action:  Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning ○ Innervation: CN VII (facial nerve) ○ ○ Droops eyelid if Botox is injected too far in this area ○ Brings brow area in and down when contracted this muscle Part of the problem: glabellar lines Levator palpebrae superioris ○ Origin: roof of orbit at the lesser wing of sphenoid bone ○ Insertion: skin of upper eyelid ○ Action: elevates upper eyelid ○ Innervation: CN III (oculomotor nerve) ○ Nose muscles Nasalis ○ (Transverse nasalis muscle) Located on the bridge of the nose Connected from one side of the nasal cartilage to the other, blends with the procerus superiorly Origin – maxilla, near the nasal bone and cartilage Inserts into the skin over the bridge of the nose, particularly at the midline Innervated by cranial nerve VII Function – Compress the nostrils  ○ ○ Alar nasalis muscle Arises from the maxilla and extends up to the wing of the nostril (the alar cartilage), allowing it to draw the nostrils outward Originates from the maxilla, just above the canine fossa (where the canine tooth is located) Inserts into the alar cartilage of the nostril and the skin of the nostril Innervated by cranial nerve VII Function - flaring the nostrils Procerus ○ Origin: Fascia over nasal bone ○ Insertion: Skin between eyebrows ○ Actions Draws down medial eyebrows Also wrinkles the skin of the nose Gives look of frowning and also helps shield eyes from bright light ○ Innervation: CN VII (Facial nerve) ○ Depressor septi nasi ○ Originates from the maxilla, above the incisor teeth ○ Inserts into the nasal septum and the lower part of the cartilage of the nose ○ Function: pull the nasal septum downward to widen the nostrils ○ Aids in respiratory functions by allowing for increased airflow through the nasal passages ○ Innervated by cranial nerve VII  ○ Mouth muscles Orbicularis oris ○ Origin: Surrounds the mouth ○ Insertion: Skin at corner of mouth ○ Action: Closes mouth Protrudes the lips (like kissing) Compresses lips against teeth Shapes lips during speech ○ Innervation: CN VII (Facial nerve) ○ Zygomaticus major ○ Origin: Zygomatic bone ○ Insertion: Skin at angle of mouth and orbicularis oris (snarling is zygomaticus major + minor) ○ Action: Draws angle of mouth superiorly and laterally (as in smiling) ○ Innervation: CN VII (Facial nerve) ○ Zygomaticus minor ○ Origin: Zygomatic bone ○ Insertion: Upper Lip  ○ Action Elevation of Upper Lip Exposing maxillary teeth (Blends with levator labii superioris) ○ Innervation: CN VII (Facial nerve) ○ Levator labii superioris ○ Origin: Superior to Infraorbital foramen of the maxilla ○ Insertion: Orbicularis oris (upper lip) ○ Action Elevation of Upper Lip (Contraction alone will elevate upper lip as in showing someone our upper teeth) Main elevators of upper lip are levator labii superioris and zygomaticus minor ○ Innervation: CN VII (Facial nerve) ○ Depressor labii inferioris ○ Origin: Mandible ○ Insertion: Skin of lower Lip ○ Action: Depression of Lower Lip Also assists in drawing the lower lip laterally and everting it Contribute to facial expressions of sorrow, doubt, and irony ○ Innervation: CN VII (Facial nerve) ○ Depressor anguli oris ○ Origin is at the mandible - It is situated at the corners of mouth, extending from the mandible (jawbone) to the angle of the mouth (insertion)  ○ Function Pull the corners of the mouth downward, which contributes to facial expressions like frowning or sadness. Assists the Risorius in drawing the angle of the mouth laterally ○ Innervated by the facial nerve (cranial nerve VII) ○ Levator anguli oris ○ Origin: Maxilla, just inferior to the infraorbital foramen ○ Insertion: skin of upper lip and orbicularis oris (angle of mouth) ○ Action Elevation of Angle of Mouth Also known as the caninus (because contraction can result in teeth especially canine tooth becoming visible) ○ Innervation: CN VII (Facial nerve) ○ Buccinator ○ Located in the fleshy part of the cheek ○ Forms a significant part of the lateral wall of the oral cavity ○ Originates from the outer surfaces of the maxilla and mandible near the molars ○ Also, in part originates as well as from the pterygomandibular raphe (fibrous band that connects the maxilla to the mandible) ○ Inserts into the orbicularis oris, the circular muscle surrounding the mouth, and it helps to form the cheek structure ○ Function Pressing the cheeks against the teeth during chewing, which helps keep food between the teeth and prevents it from accumulating in the cheeks Aiding in the control of airflow during speech Smiling and blowing ○ Innervated by the facial nerve (cranial nerve VII)  ○ Risorius ○ Situated in the lateral part of the face ○ Extends from the side of the mouth toward the masseter muscle (chewing muscle) ○ Originates from the fascia covering the masseter muscle and the superficial structures of the face ○ Inserts into the skin at the corner of the mouth, blending with the fibers of other facial muscles, including the zygomatic major and minor ○ Function – draw the corners of the mouth laterally, allowing for expressions that resemble smiling or grinning ○ Innervation: facial nerve (cranial nerve VII) ○ Mentalis ○ Origin - Mandible ○ Insertion - Skin of the Chin ○ Action Elevation and protrudes lower Lip Pulls skin of chin up (as in pounting) Wrinkles the skin of the chin Contributes to facial expressions of doubt, pouting, or dislike ○ Innervation: CN VII (Facial nerve) ○ Platysma- Neck muscle Found in the anterior and lateral parts of the neck Extends from the upper chest and shoulder area up to the lower jaw Originates from the fascia over the pectoralis major and deltoid muscles in the upper chest and shoulder región Inserts into the lower mandible (jawbone) and the skin of the lower face, as well as the muscles around the mouth Function ○ Tensing the skin of the neck ○ Depressing the mandible ○ Helps in movements of the skin over the neck during expressions Innervated by the cervical branch of cranial nerve VII Muscles of mastication: Also assist in speech 4 pairs ○ Masseter Located at the side of the jaw Origin is at zygomatic arch (cheekbone) Inserts at ramus of mandible (vertical extension of the mandible) Elevates and closes the jaw, playing a significant role in biting and chewing Innervation by mandibular division of trigeminal nerve (CN V) ○ Temporalis Situated on the side of the head Originates at the temporal fossa of the skull Insertion at the coronoid process of the mandible Elevates and retracts the jaw Helps close the jaw with vertical and horizontal forces Innervated by the mandibular division of trigeminal nerve (CN V)  ○ Medial pterygoid Located on the internal (medial) side of the mandible Originates at the medial surface of the lateral pterygoid plate of the sphenoid bone and the maxilla Inserts at the medial surface of the angle of the mandible Function: Elevates the jaw and assists in grinding movements side to side Innervation: Mandibular division of trigeminal nerve (CN V) ○ Lateral pterygoid Located at lateral to the medial pterygoid Originates at the greater wing and lateral surface of lateral portion of pterygoid process of sphenoid bone Insertion: Condyle of mandible and articular disc of the temporomandibular joint (TMJ) Helps to protrude the jaw and assists in moving the jaw side to side. Innervation: Mandibular division of trigeminal nerve (CN V)