Essentials of Anatomy and Physiology

155

Table 7–4 MUSCLES OF THE TRUNK

Muscle Function Origin Insertion

Trapezius

External intercostals

Internal intercostals

Diaphragm

Rectus abdominis

External oblique

Sacrospinalis group

(deep muscles)

Raises, lowers, and adducts

shoulders

Pull ribs up and out (inhalation)

Pull ribs down and in (forced

exhalation)

Flattens (down) to enlarge

chest cavity for inhalation

Flexes vertebral column, com-

presses abdomen

Rotates and flexes vertebral col-

umn, compresses abdomen

Extends vertebral column

• occipital bone and all
  thoracic vertebrae


• superior rib


• inferior rib


• last 6 costal cartilages
  and lumbar vertebrae


• pubic bones


• lower 8 ribs


• ilium, lumbar, and
  some thoracic vertebrae
  
  
  • spine of scapula and
    clavicle
  
  
  • inferior rib
  
  
  • superior rib
  
  
  • central tendon
  
  
  • 5th–7th costal cartilages
    and xiphoid process
  
  
  • iliac crest and linea alba
  
  
  • ribs, cervical, and
    thoracic vertebrae
  
  
  
  

External oblique

Internal oblique

Transversus

abdominis

Rectus abdominis

Sternocleidomastoid

Trapezius

Pectoralis major

Serratus anterior

Trapezius

Splenius capitis

Deltoid

Teres major

Infraspinatus

Rhomboideus

major

Gluteus maximus

Latissimus

dorsi

External

oblique

A

B

Figure 7–10. Muscles of the trunk. (A) Anterior view. (B) Posterior view.

QUESTION:Which muscles of the trunk move the arm? Why are they on the trunk?