Trunk Muscles

Pectoralis major Origin - sternum, clavicle, & ribs 1 - 6 Insertion - proximal humerus Action - adducts & flexes humerus; medially rotates arm

Rectus abdominus Origin - Pubis Insertion - sternum & costal cartilage of ribs 5 - 7 Action - flexes vertebral column; increases abdominal pressure

External oblique Origin - lower 8 ribs Insertion - iliac crest of ilium Action - flexes vertebral column; increases abdominal pressure; aids back muscles with rotation & lateral flexion of the trunk

Trapezius Origin - occipital bone and all cervical and thoracic vertebrae Insertion - scapula & clavicle Action - extends neck; adducts and stabilizes scapula

Latissimus dorsi Origin - lower spine and iliac crest of ilium Insertion - proximal humerus Action - prime mover of arm extension; adducts & medially rotates the arm; brings arm down in power stroke as in striking a blow

Deltoid Origin - scapula & clavicle Insertion - humerus Action - prime mover of arm abduction; aids in flexion, extension, & rotation of the humerus

Muscles found only in cats Pectoantebrachialis Pectoralis minor Xiphihumeralis Deltoid = 3 cat muscles: clavobrachialis, acromiodeltoid, & spinodeltoid Trapezius = 3 cat muscles: clavotrapezius, acromiotrapezius, & spinotrapezius

Trunk Muscles

Deep Trunk and Arm Muscles

Superficial Muscles: Anterior

Superficial Muscles: Posterior