Trunk Muscles

Anterior Muscles

Name: Pectoralis Major Origin:

Sternum, clavicle, & 1st to 6th rib

Insertion: Proximal humerus

Primary action: Adducts and flexes

humerus

Anterior Muscles

Name: Intercostal muscles

Location: Found between the ribs

Primary action: Raise the ribcage for

breathing

Muscles of Abdominal Girdle

Name: Rectus abdominis

Origin: Pubis

Insertion: Sternum and 5th to 7th

rib Primary action:

Flexes vertebral column

Muscles of Abdominal Girdle

Name: External Oblique Origin:

Lower 8 ribs Insertion:

Iliac crest Primary action:

Flexes and rotates vertebral column

Muscles of Abdominal Girdle

Name: Internal Oblique Origin:

Iliac crest Insertion:

Last 3 ribs Primary action:

Paired muscles deep to external obliques

Flex and rotate vertebral column

Muscles of Abdominal Girdle

Name: Transverus abdominis

Origin: Lower ribs and iliac crest

Insertion: Pubis

Primary action: Compresses abdominal

contents

Posterior Muscles

Name: Trapezius Origin:

Occipital bone and all cervical / thoracic vertebrae

Insertion: Scapular spine and

clavicle Primary action:

Extends neck and adducts scapula

Posterior Muscles

Name: Latissimus Dorsi

Origin: Lower spine and iliac

crest Insertion:

Proximal humerus Primary action:

Extends and adducts humerous

Posterior Muscles

Name: Erector Spinae Origin:

Iliac crest, ribs 3-12, and vertebrae

Insertion: Ribs thoracic / cervical

vertebrae Primary action:

Extends back

Posterior Muscles

Name: Deltoid Origin:

Scapular spine and clavicle

Insertion: Humerus (deltoid

tuberosity) Primary action:

Abducts humerus