Lab 4 BIOL 319 AOIs

Dr. Lee Summer 2025

Obliques (external and internal): Action

Compression of abdomen, flexion and rotation of trunk

Obliques (external and internal): Origin

ribs (external), iliac crest (internal)

Obliques (external and internal): Insertion

iliac crest (external), ribs (internal)

Transverse abdominis: Action

Compression of abdomen

Transverse abdominis: Origin

Ribs and iliac crest

Transverse abdominis: Insertion

Linea alba

Rectus abdominis: Action

Flexion of trunk; compression of abdominal wall

Rectus abdominis: Origin

Pubic crest

Rectus abdominis: Insertion

xiphoid process and ribs 5-7

Intercostals (external and internal): Action

elevation and depression of ribs

Intercostals (external and internal): Origin

Superior border of ribs (external); inferior border of ribs (internal)

Intercostals (external and internal): Insertion

inferior border of ribs (external); superior border of ribs (internal)

Diaphragm: Action

opens thoracic cavity for lungs during inspiration

Diaphragm: Origin

Ribs (5-10) and lumbar vertebrae

Diaphragm: Insertion

central tendon

Frontalis: Action

Raises eyebrows

Frontalis: Origin

Epicranial aponeurosis

Frontalis: Insertion

Skin of eyebrows and root of nose

Occipitalis: Action

pulls scalp posteriorly

Occipitalis: Origin

Occipital bone

Occipitalis: Insertion

Epicranial aponeurosis

Temporalis: Action

Closes jaw; retracts mandible

Temporalis: Origin

Temporal fossa

Temporalis: Insertion

Coronoid process (mandible)

Masseter: Action

Closes jaw

Masseter: Origin

Zygomatic arch

Masseter: Insertion

angle and ramus of mandible

Zygomaticus: Action

Elevates corners of mouth

Zygomaticus: Origin

Zygomatic bone

Zygomaticus: Insertion

Corner of mouth

Buccinator: Action

Compression of cheek

Buccinator: Origin

Molar region (maxilla and mandible)

Buccinator: Insertion

Orbicularis oris

Platysma: Action

Tenses skin of neck; depression of lower lip

Platysma: Origin

Fascia of chest

Platysma: Insertion

Mandible and corner of mouth

Orbicularis oculi: Action

Closes eyes

Orbicularis oculi: Origin

Frontal bone and maxilla

Orbicularis oculi: Insertion

Eyelids

Orbicularis oris: Action

Closes and protrudes lip

Orbicularis oris: Origin

Maxilla and mandible

Orbicularis oris: Insertion

Angles of mouth

Levator labii superioris: Action

Elevation of upper lip

Levator labii superioris: Origin

zygomatic bone and infraorbital margin (maxilla)

Levator labii superioris: Insertion

Upper lip

Depressor labii inferioris: Action

Depression of lower lip

Depressor labii inferioris: Origin

Body of mandible

Depressor labii inferioris: Insertion

Lower lip

Sternocleidomastoid: Action

Flexion and rotation of neck

Sternocleidomastoid: Origin

Manubrium and clavicle

Sternocleidomastoid: Insertion

Mastoid process (temporal bone)

Scalenes: Action

Elevation of ribs 1 and 2; rotation of neck

Scalenes: Origin

Transverse processes of cervical vertebrae (C3-C7)

Scalenes: Insertion

Ribs 1-2

Serratus anterior: Action

Abduction and rotation of scapula

Serratus anterior: Origin

True ribs

Serratus anterior: Insertion

Medial border (scapula)

Rhomboids: Action

Adduction and elevation of scapula

Rhomboids: Origin

Spinous processes of vertebrae (C7-T5)

Rhomboids: Insertion

Medial border (scapula)

Splenius: Action

Rotation of head; extension of neck

Splenius: Origin

Spinous processes of vertebrae (C7-T6)

Splenius: Insertion

Temporal and occipital bone

Digastric: Action

Elevation of hyoid; opens mouth

Digastric: Origin

Lower margin (mandible); mastoid process (temporal bone)

Digastric: Insertion

Hyoid bone

Mylohyoid: Action

Elevation of hyoid and floor of mouth

Mylohyoid: Origin

Medial surface (mandible)

Mylohyoid: Insertion

Hyoid bone

Geniohyoid: Action

Elevation and protraction of hyoid bone

Geniohyoid: Origin

Mental tubercle

Geniohyoid: Insertion

Hyoid bone

Sternohyoid: Action

Depression of hyoid and larynx

Sternohyoid: Origin

Manubrium (sternum)

Sternohyoid: Insertion

Hyoid bone

Sternothyroid: Action

Depression of hyoid and larynx

Sternothyroid: Origin

Manubrium (sternum)

Sternothyroid: Insertion

Thyroid cartilage

Thyrohyoid: Action

Depression of hyoid; elevation of larynx

Thyrohyoid: Origin

Thyroid cartilage

Thyrohyoid: Insertion

Hyoid bone