Smile muscles

 Muscles works in smile

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Ads by Eonads Muscles of Facial Expression are unique in that they migrate to their destinations about the scalp, neck, and mostly about the face from second pharyngeal arch mesenchyme and thus receive their motor innervation via the facial nerve (CN VII), the nerve of the second arch. Although most of these muscles originate on bone, most do not insert on bone; rather, they insert into the dermis of the skin and freely intermingle with muscles in their vicinity. Upon contraction, this arrangement and groupings of muscles about the orifices of the face convey movements about these orifices that we interpret as emotions.

The muscles of the face (and scalp) are derived from the second pharyngeal arch (hyoid arch) mesenchyme that migrates to its final destination.

Considering the origin of these muscles, it is not surprising that they receive motor innervation from branches of the facial nerve (CN VII).

Rather than inserting into bone, these muscles insert into the dermis of the skin, thus their orchestrated contractions convey various shapes to the face that we interpret as emotions. It is important to understand that fascicles of these muscles intermingle with each other, and they tend to act in groups to control the orifices around which they are grouped, such as the orbit, nose, and mouth. It is according to this grouping that they are described.

Ads by Eonads Muscles of the Face and Scalp
Muscle	Location	Origin
Scalp
Frontalis	Forehead	Procerus, corrugator, orbicularis oculi
Occipitalis	Back of the head Ads by Eonads	Ads by Eonads Mastoid process and superior nuchal line
Temporoparietalis	Temple	Temporal fascia
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Auricularis anterior	Anterior to ear	Temporal fascia
Auricularis superior	Above ear	Temporal fascia
Auricularis posterior	Behind ear	Mastoid process
Nose
Procerus
Nasalis
Depressor septi
Eye
Orbicularis oculi	Around the orbit	Nasal process of frontal bone, frontal process of maxilla, medial palpebral ligament, and lacrimal bone
Corrugator	Deep to the orbicularis oculi	Medial aspect of superciliary arch
Mouth
Levator labii superioris	Upper lip	Zygoma and maxilla just above infraorbital foramen
Levator labii superioris alaque nasi	Upper lip and side of nose	Maxilla, frontal process
Levator anguli oris	Ads by Eonads Corner of mouth	Canine fossa of maxilla
Zygomaticus major	Cheek and corner of mouth	Temporal process of zygoma
Zygomaticus minor	Cheek and corner of mouth	Maxillary process of zygoma
Risorius	Cheek	Masseteric fascia
Depressor labii inferioris	Lower lip	Oblique line of mandible
Depressor anguli oris	Corner of mouth	Oblique line of mandible
Mentalis	Chin	Incisive fossa of mandible
Orbicularis oris	Circumscribes the mouth	Muscles in the vicinity, maxilla, nasal septum, mandible
Buccinator	Cheek	Pterygomandibular raphe, alveola arches of mandible and maxilla
Neck
Platysma	Neck and chin	Pectoral and deltoid fascia

Muscles of the Ear and Nose

The three external muscles of the ear are the auricularis anterior, superior, and posterior. Similarly, the three muscles of the nose are the procerus, nasalis, and depressor septi. These two groups of muscles are fairly inconsequential.

Muscles Surrounding the Orbit

Orbicularis Oculi

The orbicularis oculi muscle is composed of two parts, the palpebral portion and the orbital portion. The former originates from the medial palpebral ligament (attached to the medial aspect of the orbit) and inserts into the lateral palpebral raphe (attached to the lateral aspect of the orbit). The orbital portion of the muscle describes an oval around the orbit.

The orbicularis oculi is innervated by the temporal and zygomatic branches of the facial nerve and acts to close the eyelid completely. Forceful closure is mediated by the orbital portion, whereas the palpebral portion is responsible for light closure, as in blinking.

Corrugator

The corrugator (supercilii) muscle is located deep to the superomedial aspect of the orbicularis oculi, at the medial aspect of the eyebrow. It originates at the medial extent of the superciliary arch and inserts into the skin of the eyebrow.

It is innervated by the temporal and zygomatic branches of the facial nerve; the combined actions of the paired muscles approximate the eyebrows, producing frowns.

Muscles Surrounding the Mouth

Orbicularis Oris

The orbicularis oris completely encircles the mouth. Its fibers are positioned at various depths and angles in the two lips. Fascicles of this muscle, some of which are derived from those of neighboring muscles—especially the buccinator—freely intermingle with fascicles of other muscles acting on the lips, permitting extensive movability. Many of the fibers of the buccinator cross over each other at the angle of the mouth so the upper fibers proceed to the lower lip and the lower fibers to the upper lip. Hence, the origin of the orbicularis oris is complex and is usually considered to be from the fibers of the surrounding muscles as well as from the alveolar portion of the maxilla, the septum of the nose, and the area lateral to the incisive fossa of the mandible. Insertion is into the skin and into itself, forming an ellipse around the mouth.

Buccal branches of the facial nerve innervate this complex muscle, which closes the lips and, during stronger contraction, purses them, as in osculation and whistling.

Risorius