Muscles Unit (OIAs only)

Epicranius (occipitofrontalis) origin

Epicranial aponeurotica; occipital and temporal bones

Epicranius (occipitofrontalis) insertion

Skin of eyebrows; epicranial aponeurotica

Epicranius (occipitofrontalis) action

Raises eyebrows and pulls scalp posteriorly

Orbicularis oculi origin

Frontal and maxillary bones

Orbicularis oculi insertion

Eyelid

Orbicularis oculi action

Closes eyes

Orbicularis oris origin

Maxilla and mandible

Orbicularis oris insertion

Corners of mouth

Orbicularis oris action

Closes lips

Zygomaticus major origin

Zygomatic bone

Zygomaticus major insertion

Corners of mouth

Zygomaticus major action

Raises corners of mouth upward

Zygomaticus minor origin

Zygomatic bone

Zygomaticus minor insertion

Corners of mouth

Zygomaticus minor action

Raises corners of mouth upward

Risorius origin

Fascia of masseter

Risorius insertion

Corners of mouth

Risorius action

Draws corners of mouth laterally

Buccinator origin

Maxilla and mandible

Buccinator insertion

Orbicularis oris

Buccinator action

Compresses cheek

Masseter origin

Zygomatic arch and maxilla

Masseter insertion

Angle and ramus of mandible

Masseter action

Closes jaw

Temporalis origin

Temporal fossa

Temporalis insertion

Mandible

Temporalis action

Closes jaw

Platysma origin

Fascia of chest

Platysma insertion

Lower margin of mandible and skin of jawline

Platysma action

Tenses skin of neck

Sternocleidomastoid origin

Sternum and clavicle

Sternocleidomastoid insertion

Mastoid process

Sternocleidomastoid action

Flexes neck and rotates head toward opposite shoulder

Sternohyoid origin

Posterior manubrium

Sternohyoid insertion

Hyoid bone

Sternohyoid action

Assists in swallowing and speaking

Digastric origin

Lower margin of mandible; mastoid process of temporal bone

Digastric insertion

Connective tissue sling of hyoid bone

Digastric action

Assists in swallowing and speaking

Omohyoid origin

Superior surface of scapula

Omohyoid insertion

Inferior border of hyoid bone

Omohyoid action

Assists in swallowing and speaking

Trapezius origin

Occipital bone and thoracic vertebrae

Trapezius insertion

Scapula

Trapezius action

Raises, rotates, retracts, and stabilizes scapula

Levator scapulae origin

Transverse processes C1-C4

Levator scapulae insertion

Superior angle and medial border of scapula

Levator scapulae action

Elevates and retracts scapula

Rhomboids origin

Thoracic vertebrae

Rhomboids insertion

Scapula

Rhomboids action

Stabilizes scapula

Latissimus dorsi origin

Thoracic and lumbar vertebrae and iliac crest

Latissimus dorsi insertion

Intertubercular sulcus of humerus

Latissimus dorsi action

Extends and adducts arm at shoulder

Splenius origin

Spinous processes

Splenius insertion

Mastoid process, temporal bone, and occipital bone

Splenius action

Extends head at neck

Semispinalis origin

Transverse processes of C7-T12

Semispinalis insertion

Occipital bone and spinous processes C1-T4

Semispinalis action

Extends head at neck and trunk and rotates trunk to opposite side

Spinalis origin

Transverse processes of thoracic and lumbar vertebrae

Spinalis insertion

Spinous processes

Spinalis action

Extends trunk at vertebral column and laterally flexes trunk at vertebral column

Longissimus origin

Iliac crest and transverse processes of lumbar and thoracic vertebrae

Longissimus insertion

Mastoid process of temporal bone and transverse processes of cervical, thoracic, and lumbar vertebrae

Longissimus action

Extends trunk at vertebral column and laterally flexes trunk at vertebral column

Iliocostalis origin

Iliac crest and transverse processes of lumbar and thoracic vertebrae

Iliocostalis insertion

Ribs

Iliocostalis action

Extends trunk at vertebral column and laterally flexes trunk at vertebral column

Quadratus lumborum origin

Iliac crest and lumbar fascia

Quadratus lumborum insertion

Inferior border of last rib and transverse processes of lumbar vertebrae

Quadratus lumborum action

Laterally flexes trunk and extends trunk

Pectoralis major origin

Clavicle and sternum

Pectoralis major insertion

Intertubercular sulcus of humerus

Pectoralis major action

Flexes, adducts, and medially rotates arm at shoulder

Deltoid origin

Lateral 1/3 of clavicle, acromion, and spine of scapula

Deltoid insertion

Deltoid tuberosity of humerus

Deltoid action

Abducts humerus at shoulder

Pectoralis minor origin

Ribs 3-5

Pectoralis minor insertion

Coracoid process of scapula

Pectoralis minor action

Protracts and depresses scapula

Serratus anterior origin

Lateral aspect of true ribs

Serratus anterior insertion

Medial border of scapula

Serratus anterior action

Protracts scapula and rotates scapula

External intercostals origin

Inferior border of rib above

External intercostals insertion

Superior border of rib below

External intercostals action

Elevates rib cage during inspiration

Internal intercostals origin

Superior border of rib below

Internal intercostals insertion

Inferior border of rib above

Internal intercostals action

Depresses rib cage during expiration

Diaphragm origin

Inferior border of rib cage and lumbar vertebrae

Diaphragm insertion

Central tendon

Diaphragm action

Contracts for respiration

Rectus abdominis origin

Pubic crest and symphysis

Rectus abdominis insertion

Xiphoid process

Rectus abdominis action

Flexes vertebral column and rotates trunk

External oblique origin

Anterior surface of lower 8 ribs

External oblique insertion

Linea alba, pubic crest, and pubic tubercle

External oblique action

Flexes and rotates trunk at vertebral column

Internal oblique origin

Lumbar fascia and iliac crest