Lab 7 OIA Flashcards

Frontal Belly

• Origin: Epicranial aponeurosis

• Insertion: Skin of eyebrows & forehead

• Action: Raises eyebrows, wrinkles forehead

Occipital Belly

• Origin: Occipital bone & mastoid process

• Insertion: Epicranial aponeurosis

• Action: Pulls scalp posteriorly

Orbicularis Oculi

• Origin: Frontal bone & maxilla

• Insertion: Skin around eyelids

• Action: Closes eyes

Orbicularis Oris

• Origin: Maxilla & mandible

• Insertion: Lips

• Action: Closes & protrudes lips

Zygomaticus

• Origin: Zygomatic bone

• Insertion: Corner of mouth

• Action: Smiling (elevates mouth corners)

Buccinator

• Origin: Maxilla & mandible

• Insertion: Orbicularis oris

• Action: Compresses cheek

Mentalis

• Origin: Mandible

• Insertion: Skin of chin

• Action: Elevates lower lip

Masseter

• Origin: Zygomatic arch

• Insertion: Mandible

• Action: Elevates mandible (closes jaw)

Temporalis

• Origin: Temporal bone

• Insertion: Coronoid process of mandible

• Action: Elevates & retracts mandible

Digastric

• Origin: Mandible (anterior), mastoid process (posterior)

• Insertion: Hyoid bone

• Action: Opens mouth, elevates hyoidA:

Mylohyoid

• Origin: Mandible

• Insertion: Hyoid bone

• Action: Elevates floor of mouth

Sternohyoid

• Origin: Sternum & clavicle

• Insertion: Hyoid bone

• Action: Depresses hyoid

Sternocleidomastoid

• Origin: Sternum & clavicle

• Insertion: Mastoid process

• Action: Flexes neck, rotates head

Deltoid

• Origin: Clavicle & scapula (acromion, spine)

• Insertion: Deltoid tuberosity of humerus

• Action: Abducts arm (also flexes & extends depending on fibers)

Pectoralis Major

• Origin: Clavicle, sternum, ribs

• Insertion: Humerus (intertubercular groove)

• Action: Adducts & medially rotates arm

Pectoralis Minor

• Origin: Ribs 3–5

• Insertion: Coracoid process of scapula

• Action: Stabilizes & protracts scapula

Serratus Anterior

• Origin: Ribs 1–8

• Insertion: Medial border of scapula

• Action: Protracts scapula, holds it against rib cage

External intercostal (posterior/lateral)

• Origin: Inferior border of rib above

• Insertion: Superior border of rib below

• Action: Elevate ribs (inhalation)

Internal intercostal (anterior/medial)

• Origin: Superior border of rib below

• Insertion: Inferior border of rib above

• Action: Depress ribs (forced exhalation)

Diaphragm

• Origin: Sternum, ribs, lumbar vertebrae

• Insertion: Central tendon

• Action: Contracts to flatten → inhalation

External oblique

• Origin: Ribs 5–12

• Insertion: Iliac crest & linea alba

• Action: Trunk rotation & compression (fibers toward groin)

Internal oblique

• Origin: Iliac crest & inguinal ligament

• Insertion: Ribs & linea alba

• Action: Trunk rotation & compression (fibers toward outer hip)

Rectus abdominus

• Origin: Pubis

• Insertion: Xiphoid process & ribs 5–7

• Action: Flexes trunk (“8-pack”)

Linea alba

• Structure: Connective tissue midline seam

• Location: Runs down center of abdomen

• Function: Joins left & right abdominal muscles

Trapezius

• Origin: Occipital bone, ligamentum nuchae, C7–T12 vertebrae

• Insertion: Clavicle & scapula (acromion, spine)

• Action: Elevates, retracts, depresses scapula; extends neck

Latissimus dorsi

• Origin: T7–L5 vertebrae, iliac crest

• Insertion: Humerus (intertubercular groove)

• Action: Extends, adducts, medially rotates arm

Rhomboid major

• Origin: T2–T5 vertebrae

• Insertion: Medial border of scapula

• Action: Retracts (adducts) scapula, downward rotation

Rhomboid minor

• Origin: C7–T1 vertebrae

• Insertion: Medial border of scapula (above major)

• Action: Retracts scapula

Levator scapulae

• Origin: C1–C4 transverse processes

• Insertion: Superior medial border of scapula

• Action: Elevates scapula (shrug shoulders)

Teres major

• Origin: Inferior angle of scapula

• Insertion: Humerus

• Action: Extends, adducts, medially rotates arm

Erector spinae

• Origin: Iliac crest, sacrum, vertebrae

• Insertion: Ribs & vertebrae

• Action: Extends & maintains posture of spine

Supraspinatus (SITS)

• Origin: Scapula

• Insertion: Humerus

• Action: Initiates arm abduction

Infraspinatus (SITS)

• Origin: Scapula

• Insertion: Humerus

• Action: Lateral rotation of arm

Teres Minor (SITS)

• Origin: Lateral border of scapula

• Insertion: Humerus (greater tubercle)

• Action: Lateral rotation of arm

Subscapularis

• Origin: Subscapular fossa (under scapula)

• Insertion: Humerus (lesser tubercle)

• Action: Medial rotation of arm

Transversus Abdominis

• Origin: Iliac crest, ribs, thoracolumbar fascia

• Insertion: Linea alba

• Action: Compresses abdomen (fibers horizontal)