Axial Muscles

Buccinator

Origin: Mandible and maxilla Insertion: Orbicularis oris at corner of mouth Action: Draws corner of mouth posteriorly; compresses cheek to hold food between teeth

Corrugator supercilii

Origin: Nasal bridge and orbicularis oculi Insertion: Skin of eyebrow Action: Depresses medial portion of eyebrow; draws eyebrows together, as in frowning

Depressor labii inferioris

Origin: Lower border of mandible Insertion: Skin of lower lip and orbicularis oris Action: Depresses lower lip

Levator labii superioris

Origin: Maxilla Insertion: Skin and orbicularis oris of upper lip Action: raises upper lip; "sneer"

Mentalis

Origin: mandible Insertion: skin of chin Action: elevates and wrinkles skin over chin; protrudes lower lip; "pout"

Nasalis

Origin: maxilla Insertion: bridge and side of nose Action: dilates nostril

Occipitofrontalis (cranius)

Origin: occipital bone Insertion: skin of eyebrow and nose Action: moves scalp; raises eyebrows; wrinkles forehead; "surprise"

Orbicularis oculi

Origin: maxilla and frontal bones Insertion: circles orbit and inserts near origin Action: closes eyes; blinking; winking; squinting

Orbicularis oris

Origin: nasal septum, maxilla, and mandible Insertion: faschia and other muscles of lips Action: closes and purses lips; "kissing"

Platysma

Origin: fascia of deltoid and pectoralis major Insertion: skin over inferior border of mandible Action: depresses lower lip; wrinkles skin of neck and upper chest; to express fear

Risorius

Origin: platysma and masseter fascia Insertion: orbicularis oris and skin at corner of mouth Action: draws corner of mouth laterally; risor - laughter

Zygomaticus

Origin: zygomatic bone Insertion: angle of mouth (major); orbicularis oris of upper lip (minor) Action: elevates and abducts upper lip and corner of mouth; "smile"

Temporalis

Origin: Temporal fossa Insertion: Anterior portion of mandibular ramus and coronoid process Action: Elevates and retracts (moves posteriorly) mandible; involved in excursion

Masseter

Origin: Zygomatic arch Insertion: Lateral side of mandibular ramus Action: Elevates and protracts (move anteriorly) mandible; involved in excursion

Lateral pterygoid

Origin: Lateral side of lateral pterygoid plate and greater wing of sphenoid Insertion: Condylar process of mandible and articular disk Action: Depresses and protracts mandible; involved in excursion; side-to-side movements

Medial pterygoid

Origin: Medial side of lateral pterygoid plate and tuberosity of maxilla Insertion: Medial surface of mandible Action: Elevates and protracts mandible; involved in excursion; side-to-side movements

Genioglossus

Origin: Mental protuberance of mandible Insertion: Tongue Action: Depresses and protrudes tongue

Hyoglossus

Origin: Hyoid Insertion: Side of tongue Action: Retracts and depresses side of tongue

Styloglossus

Origin: Styloid process of temporal bone Insertion: Tongue (lateral and inferior) Action: Retracts tongue

Splenius capitis

Origin: C4 to T6 Insertion: Superior nuchal line and mastoid process Action: Extends, rotates, and laterally flexes neck

Trapezius

Origin: Occipital protuberance, nuchal ligament, spinous processes of C7 to T12 Insertion: Clavicle, acromion process, and scapular spine Action: Extends and laterally flexes neck

Sternocleidomastoid

Origin: Manubrium and medial clavicle Insertion: Mastoid process and superior nuchal line Action: One contracting alone: laterally flexes head and neck to same side and rotates head and neck to opposite side Both contracting together: flex neck

Scalene muscles

Origin: C2 to C6 Insertion: First and second ribs Action: Flex, laterally flex, and rotate neck

Iliocostalis cervicis (erector spinae)

Origin: Superior six ribs Insertion: Transverse processes of middle cervical vertebrae Action: Extends, laterally flexes, and rotates vertebral column

Iliocostalis thoracis (erector spinae)

Origin: Inferior six ribs Insertion: Superior six ribs Action: Extends, laterally flexes, and rotates vertebral column

Iliocostalis lumborum (erector spinae)

Origin: Sacrum, ilium, and lumbar vertebrae Insertion: Inferior six ribs Action: Extends, laterally flexes, and rotates vertebral column

Longissimus capitis

Origin: Upper thoracic and lower cervical vertebrae Insertion: Mastoid process Action: Extends head

Longissimus cervicis

Origin: Upper thoracic vertebrae Insertion: Transverse processes of upper cervical vertebrae Action: Extends neck

Longissimus thoracis

Origin: Ribs and lower thoracic vertebrae Insertion: Transverse processes of upper lumbar vertebrae and ribs Action: Extends vertebral column

Spinalis cervicis

Origin: C6-C7 Insertion: Spinous processes of C2-C3 Action: Extends neck

Spinalis thoracis

Origin: T11 - L2 Insertion: Spinous processes of middle and upper thoracic vertebrae Action: Extends vertebral column

Diaphragm

Origin: Interior of ribs, sternum, and lumbar vertebrae Insertion: Central tendon of diaphragm Action: Inspiration depresses floor of thorax

External intercostal

Origin: Inferior margin of each rib Insertion: Superior border of next rib below Action: Quiet inspiration elevates ribs

Internal intercostal

Origin: Superior margin of each rib Insertion: Inferior border of next rib above Action: Forced expiration depresses ribs

Anterior Scalene

Origin: Transverse processes of C3-C6 Insertion: First rib Action: Elevates first rib

Medial scalene

Origin: Transverse processes of C2-C6 Insertion: First rib Action: Elevates first rib

Posterior scalene

Origin: Transverse processes of C4-C6 Insertion: Second rib Action: Elevates second rib

Rectus abdominis

Origin: Pubic crest and symphysis pubis Insertion: Xiphoid process and inferior ribs Action: Flexes vertebral column; compresses abdominal wall

External abdominal oblique

Origin: Fifth to twelfth ribs Insertion: Iliac crest, inguinal ligament, and rectus sheath Action: Flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

Internal abdominal oblique

Origin: Iliac crest, inguinal ligament, and lumbar fascia Insertion: Tenth to twelfth ribs and rectus sheath Action: Flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

Transversus abdominis

Origin: Seventh to twelfth costal cartilages, lumbar fascia, iliac crest, and inguinal ligament Insertion: Xiphoid process, linea alba, and pubic tubercle Action: Compresses abdominal wall

Quadratus lumborum

Origin: Iliac crest and lower lumbar vertebrae Insertion: Twelfth rib and upper lumbar vertebrae Action: Laterally flexes vertebral column and depresses twelfth rib