ZOOL 3214 1st Edition Lecture 19The Muscular SystemII. Axial Musculature (continued)C. Muscles of Respiration1. Diaphragm• Origin: xiphoid, ribs, CC 7-12, lumbar vertebra• Insertion: central tendon of diaphragm• Action: expansion of thoracic cavity (inhalation and contract) & relaxing it (exhalation)2. External & Internal Intercostals• Action: ribcage (elevation & depression or expansion & compression)III. Appendicular Muscles (Upper Limb)A. Chest & Shoulder1. Pectoralis Major Muscle• Origin: sternum, medial clavicle, CC 1-6• Insertion: intertubercular groove of humerus (lateral ridge of groove)• Action: adduction of arm (shoulder to elbow) & medial rotation2. Deltoid Muscle• Origin: lateral clavicle (ant.) & scapula (lateral acromion & spine post.)• Insertion: deltoid tuberosity of humerus• Action: arm abduction, directing the arm swing (dependent on ant. & post. Fibers being used)3. Rotator Cuff Muscles• SITS- Supraspinatus (above spine)- Infraspinatus (below spine)- Teres Minor (on lateral border)- Subscapularis (whole ant. side)• Functions: shoulder stabilization• Origin: fossae of scapula• Insertion: proximal humerus (greater & lesser tubercles)• Action: synerg. In abduction, adduction, and rotationB. Arm: Brachialis, Biceps brachii, Triceps brachii• Review Lecture #16 & HW to add O, I, & AC. Forearm & Hand• Many muscles assoc. w/actions in the wrist, hand, and finger regions• Anterior forearm (in AP): flexors• Posterior forearm (in AP: top of hand): extensors- These act via tendons that pass under the flexor and extensor retinaculum (bracelet of CT)- Problem: carpal tunnel syndrome (inflammation of the bracelet)1. Extensor Digitorum Muscle• Origin: lateral epicondyle of humerus• Insertion: posterior aspect of phalanges 2-5 via tendons• Action: extension of