Muscles of the Cranium
The muscles of the cranium assist with actions of facial expression. These muscles receive nerve supply from the facial nerve (cranial nerve (CN) VII).
|Occipitofrontalis||Frontal belly (frontalis): galea aponeurotica (epicranial aponeurosis)||Skin of the eyebrow||Temporal branch of the facial nerve||Lifts eyebrows, wrinkling the forehead|
|Occipital belly (occipitalis): superior nuchal line||Galea aponeurotica||Occipital belly: posterior auricular nerve from facial nerve||Moves the scalp posteriorly|
|Temporoparietalis||Aponeurosis above auriculares muscles||Galea aponeurosis||Temporal branch of the facial nerve||Pulls the ears cranially and dorsally|
Muscles of the Mouth
The muscles of the mouth assist with facial expression, chewing, and communication. These muscles are supplied by the facial nerve (CN VII).
Orbicularis oris and buccinator
|Orbicularis oris||Deep surface of the perioral skin, angle of the mouth (modiolus)||Mucous membrane of the lips||Buccal branch of the facial nerve||Closes mouth, purses lips|
|Buccinator||Alveolar processes of the maxilla and mandible (at the 1st–2nd molars)||Angle of the mouth radiating into the orbicularis oris||Buccal branch of the facial nerve||
|Risorius||Masseteric fascia||Skin of angle of the mouth||Buccal branch of the facial nerve||Pulls angle of the mouth laterally|
|Zygomaticus major||Lateral surface of the anterior aspect of the zygomatic bone||Skin of angle of the mouth, blending with levator anguli/orbicularis oris||Zygomatic and buccal branches of the facial nerve||
|Zygomaticus minor||Front of the zygomatic arch||Skin of lateral part of upper lip, extends to nasolabial sulcus||Buccal branch of the facial nerve||
|Levator labii superioris||Infraorbital margin of the maxilla||Skin of the upper lip||Buccal branch of the facial nerve||
|Levator labii superioris alaeque nasi||Frontal process of the maxilla||Skin of lateral part of the nostril and skin of upper lip||Zygomatic branches of the facial nerve||
|Levator anguli oris||Canine fossa (maxillary fossa) on anterior surface of the maxilla||Skin of angle of the mouth||Buccal branch of the facial nerve||Raises the angle of the mouth while smiling|
|Depressor anguli oris||Oblique line of the base of the mandible||Skin of angle of the mouth||Marginal mandibular branch of the facial nerve||Pulls angle of the mouth downward|
|Depressor labii inferioris||Oblique line of the base of the mandible||Skin of lower lip||Retracts (depresses) and everts lower lip (pouting)|
|Mentalis||Incisive fossa on alveolar process of the mandible||Skin of the chin||
Muscles of the Eyes
The muscles of the extraorbital eye assist with actions of blinking and facial expression. These muscles are primarily supplied by branches of the facial nerve.
|Orbicularis oculi||Orbital part:
||Temporal and zygomatic branches of the facial nerve||
|Depressor supercilii||Medial orbital rim||Skin below the eyebrow and intercanthal region||Temporal branch of the facial nerve||Depresses the eyebrow|
|Corrugator supercilii||Medial part of superciliary arch||Skin over middle of the eyebrow (penetrates frontalis and orbicularis oculi)||Temporal branch of the facial nerve||Pulls skin of eyebrow downward and medially|
Muscles of the Nose
The muscles of the nose assist in respiration and facial expression. These muscles are supplied by branches of the facial nerve.
|Nasalis||Transverse nasalis (compressor naris): maxilla, lateral to incisive fossa||Aponeurosis of bridge of the nose||Buccal branch of the facial nerve||Compresses nostril|
|Alar nasalis (dilator naris): outer surface of maxilla, above lateral incisor tooth||Skin of ala, superior to lateral crus of major alar cartilage||Dilates nostril|
|Procerus||Midline of nasal bone and lateral nasal cartilage||Skin of lower part of forehead between eyebrows||Draws the medial border of the eyebrows downward to produce transverse wrinkles over the bridge of the nose|
|Depressor septi nasi||Incisive fossa of the maxilla||Nasal septum and posterior aspect of alar nasalis||Depresses nasal septum and pulls wings of the nose downward|
Muscles of the Ear
The muscles of the ear are more simple than the other muscle groups of the face. These muscles assist with moving the ear and are innervated by fibers of the facial nerve (CN VII).
|Anterior auricular||Lateral edge of the galea aponeurotica||Projection on the front of the helix||Temporal branch of the facial nerve||Pulls ear upward and forward|
|Posterior auricular||Mastoid portion of temporal bone||Lower part of the cranial surface of the concha||Posterior auricular nerve of facial nerve||Retracts and elevates the ear|
|Superior auricular||Galea aponeurotica||Cranial surface of the auricula||Pulls ear upward|
Muscles of Mastication
The muscles of mastication assist in the action of chewing via movement of the mandible. They are supplied by the mandibular branches (V3) of the trigeminal nerve (CN V).
|Temporalis||Temporal fossa||Coronoid process of the mandible||Branches of mandibular division of trigeminal nerve||Elevates and retracts the mandible|
|Masseter||Zygomatic arch||Masseteric tuberosity of the mandible||Elevates the mandible|
|Lateral pterygoid||Infratemporal surface of the greater wing of sphenoid and lateral plate of pterygoid process||Pterygoid fossa of the mandible||
|Medial pterygoid||Pterygoid fossa of sphenoid bone||Pterygoid tuberosity of the mandible||
- Temporomandibular joint (TMJ) dysfunction: syndrome of pain and dysfunction of the TMJ and the muscles of mastication. The most significant feature of this disorder is pain, followed by restricted mandibular movement, and possibly “cracking” or “popping” noises from the TMJ. The etiology is multifactorial, being attributed to musculoskeletal, psychological, and/or neuromuscular factors. Symptomatology may be chronic and difficult to manage. Management includes analgesics, physical therapy, and CBT.
- Trismus: also called lockjaw. Trismus is limited range of motion of the jaw. The disorder may be caused by a spasm of the muscles of mastication or by an inferior alveolar nerve block injection leading to hemorrhage within the medial pterygoid muscle. Trismus can significantly affect an individual’s quality of life by interfering with eating, speaking, and maintaining proper oral hygiene. Trismus can present with an altered facial appearance. The condition may be distressing and painful, but it is temporary in most cases.
- Myasthenia gravis: autoimmune neuromuscular junction disorder characterized by varying degrees of muscle weakness. The condition commonly presents with weakness of the arms and legs, but individuals with myasthenia gravis will also have ptosis, resulting from weakness of the muscles around the eyes. Myasthenia gravis is managed medically with acetylcholinesterase inhibitors or immunosuppressants and surgically by thymectomy.
- Cosmetics: the muscles of the face are common targets for botulinum toxin injection, with the intent of temporary paralyzing the targeted muscles. Relaxation of the muscles leads to fewer wrinkles and a younger-appearing face. Common muscles for botulinum toxin injection include the frontalis, procerus, and corrugator supercilii.
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