1. The Muscular System

2. Muscles of Trunk, Shoulder, Arm
Anterior muscles
Pectoralis major —adducts and flexes the humerus

3. Anterior Muscles of Trunk, Shoulder, Arm
Intercostal muscles
External intercostals —raise rib cage during inhalation
Internal intercostals —depress the rib cage to move air out of the lungs when you exhale forcibly

4. Muscles of Trunk, Shoulder, Arm
Muscles of the abdominal girdle
Rectus abdominis —flexes vertebral column and compresses abdominal contents (defecation, childbirth, forced breathing)

5. Anterior Muscles of Trunk, Shoulder, Arm
Muscles of the abdominal girdle
External and internal obliques —flex vertebral column; rotate trunk and bend it laterally
Transversus abdominis —compresses abdominal contents
Figure 6.16b

6. Muscles of Trunk, Shoulder, Arm
Posterior muscles
Trapezius —elevates, depresses, adducts, and stabilizes the scapula
Latissimus dorsi —extends and adducts the humerus

7. Muscles of Posterior Neck, Trunk, Arm
Posterior muscles
Erector spinae —back extension
Quadratus lumborum —flexes the spine laterally
Deltoid —arm abduction

8. Muscles of Posterior Neck, Trunk, Arm
Figure 6.17b

9. Muscles of the Upper Limb
Biceps brachii —supinates forearm, flexes elbow
Brachialis —elbow flexion
Brachioradialis —weak muscle
Triceps brachii —elbow extension (antagonist to biceps brachii)

10. Muscles of Posterior Neck, Trunk, Arm
Figure 6.17a