allied face and neck

Muscle Fascicle Arrangement: Parallel

Fascicles run parallel to the long axis of the muscle. Example: Sartorius.

Muscle Fascicle Arrangement: Fusiform

Spindle-shaped muscles with parallel fibers and a thick belly that tapers at both ends. Example: Biceps brachii.

Muscle Fascicle Arrangement: Convergent

Broad origin where fascicles converge toward a single, narrow tendon of insertion. Example: Pectoralis major.

Muscle Fascicle Arrangement: Circular

Fascicles arranged in concentric rings, surrounding external body openings (sphincters). Example: Orbicularis oculi.

Muscle Fascicle Arrangement: Unipennate

Short fascicles that insert obliquely into only one side of a central tendon. Example: Extensor digitorum longus.

Muscle Fascicle Arrangement: Bipennate

Fascicles insert obliquely into opposite sides of a central tendon from both directions (looks like a feather). Example: Rectus femoris.

Muscle Fascicle Arrangement: Multipennate

Fascicles arrange obliquely and attach from many directions into a complex, branched central tendon. Example: Deltoid.

Epicranius (Occipitofrontalis)

Action: Bipartite muscle consisting of the frontal and occipital bellies connected by the epicranial aponeurosis. Alternate pulling actions raise eyebrows and pull scalp posteriorly. Origin: Occipital bone and mastoid process (Occipital belly); Epicranial aponeurosis (Frontal belly). Insertion: Epicranial aponeurosis (Occipital belly); Skin of eyebrows and root of nose (Frontal belly).

Frontalis (Frontal belly of Epicranius)

Action: Raises the eyebrows (as in surprise); wrinkles forehead skin horizontally. Origin: Epicranial aponeurosis. Insertion: Skin of eyebrows and root of nose.

Occipitalis (Occipital belly of Epicranius)

Action: Pulls the scalp posteriorly. Origin: Occipital bone and mastoid process of temporal bone. Insertion: Epicranial aponeurosis.

Corrugator Supercilii

Action: Draws eyebrows together and inferiorly; wrinkles skin of forehead vertically (as in frowning). Origin: Arch of frontal bone near nasal suture. Insertion: Skin of eyebrow.

Orbicularis Oculi

Action: Closes eye; protects eye from intense light and injury; blinking, squinting, and drawing eyebrows inferiorly. Origin: Frontal and maxillary bones and ligaments around orbit. Insertion: Tissue of eyelid.

Zygomaticus (Major and Minor)

Action: Raises lateral corners of mouth upward (smiling muscle). Origin: Zygomatic bone. Insertion: Skin and muscle at corner of mouth.

Risorius

Action: Draws corner of lip laterally; tenses lips; synergist of zygomaticus. Origin: Lateral fascia associated with masseter muscle. Insertion: Skin at angle of mouth.

Levator Labii Superioris

Action: Opens lips; raises and furrows the upper lip. Origin: Inferior margin of orbit and maxilla. Insertion: Skin and muscle of upper lip.

Depressor Labii Inferioris

Action: Draws lower lip inferiorly (as in pouting). Origin: Body of mandible lateral to midline. Insertion: Skin and muscle of lower lip.

Depressor Anguli Oris

Action: Draws corners of mouth downward and laterally (tragedy mask/grimace). Origin: Body of mandible below incisors. Insertion: Skin and muscle at angle of mouth below lower lip.

Orbicularis Oris

Action: Closes lips; purses and protrudes lips; kissing and whistling muscle. Origin: Arises indirectly from maxilla and mandible; fibers of other facial muscles embedded in lips. Insertion: Encircles mouth; inserts into muscle and skin at angles of mouth.

Mentalis

Action: Protrudes lower lip; wrinkles chin. Origin: Mandible below incisors. Insertion: Skin of chin.

Buccinator

Action: Compresses cheek (sucking and whistling); holds food between teeth during chewing; well-developed in infants. Origin: Molar region of maxilla and mandible. Insertion: Orbicularis oris.

Nasalis

Action: Flares nostrils; compresses nasal cartilages; depresses septum of the nose so nares can open. Origin: Maxilla and alar cartilage of nose. Insertion: Bridge of nose (aponeurosis on contralateral side).

Masseter

Action: Prime mover of jaw closure; elevates mandible. Origin: Zygomatic arch and zygomatic bone. Insertion: Angle and ramus of mandible.

Temporalis

Action: Closes jaw; elevates and retracts mandible; maintains position of the mandible at rest. Origin: Temporal fossa. Insertion: Coronoid process of mandible via a tendon that passes deep to zygomatic arch.

Medial Pterygoid

Action: Acts with lateral pterygoid to protract mandible and promote side-to-side grinding movements; synergist with masseter and temporalis to elevate mandible. Origin: Medial surface of lateral pterygoid plate of sphenoid bone, maxilla, and palatine bone. Insertion: Medial surface of mandible near its angle.

Lateral Pterygoid

Action: Protracts mandible and provides forward sliding position for grinding teeth; assists in side-to-side grinding of lower teeth. Origin: Greater wing and lateral pterygoid plate of sphenoid bone. Insertion: Condylar process of mandible and capsule of temporomandibular joint (TMJ).

Genioglossus

Action: Prime mover to protrude the tongue; depresses tongue in concert with hyoglossus. Origin: Internal surface of mandible near symphysis (mental spine). Insertion: Inferior aspect of the tongue and body of hyoid bone.

Hyoglossus

Action: Depresses tongue and draws its sides downward. Origin: Body and greater horn of hyoid bone. Insertion: Inferolateral tongue.

Styloglossus

Action: Retracts and elevates tongue. Origin: Styloid process of temporal bone. Insertion: Lateral inferior aspect of tongue.

Platysma

Action: Tenses skin of neck (as during shaving); helps depress mandible; pulls lower lip back and down, producing a downward sag of the mouth. Origin: Fascia of chest (over pectoral and deltoid muscles). Insertion: Lower margin of mandible, and skin and muscle at corner of mouth.

Splenius Capitis

Action: As a bilateral pair, it extends or hyperextends the head. When acting unilaterally, it rotates and laterally flexes the head to the same side. Origin: Ligamentum nuchae, spinous processes of vertebrae C7–T3. Insertion: Mastoid process of temporal bone and occipital bone.

Sternocleidomastoid

Action: Flexes and laterally rotates the head. Simultaneous contraction of both muscles causes neck flexion; acting alone, each muscle rotates head to the shoulder of the opposite side and laterally flexes head to its own side. Origin: Manubrium of sternum and medial portion of clavicle. Insertion: Mastoid process of temporal bone and superior nuchal line of occipital bone.