ZOOL 3214 1st Edition Lecture 18Muscular System IVI. Axial MusculatureA. Back Muscles1. Latissimus dorsi muscle: large superficial muscle of lower back• Origin: T6-T12 (spinous processes)- Via thoracolumbar fascia: origin- lumbar &sacral vertebra• Origin: lower 4 ribs• Origin: iliac crest• Insertion: intertubercular groove of humerus• Actions: extension of upper limb (ex. Back swing in bowling)- Adduction and medial rotation of the limb (ex. Rowing, swimming, or bowling)B. Abdominal Muscles1. Connective Tissue: geography• Runs from xiphoid process down to pubic symphysis w/ umbilicus (belly button) being in the middle• Rectus Sheath: anterior and posterior CT sleeves• Linea Alba: medial line that bisects the rectus sheath• Tendinous Intersections: horizontal/transverse lines of CT that form the (6 pack)• Aponeuroses of external abdominal oblique muscle- Inguinal Canal: tube formed from the inferior part of aponeuroses of exterior abdominal oblique*Inferior margin = Inguinal ligamentThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.*Passageway in and out of pelvic cavity(in males leads to the scrotum)*In development the testes descend through this canal*Clinical Issues:1. Undescended Testicle: cryptorchidism2. Inguinal Hernia: small loop of SI may bulge through2. Rectus Abdominis muscle: 6 pack Abs• Origin: pubic symphysis and superior margin of pubis• Insertion: xiphoid process of sternum and costal cartilage 5-73. External Abdominal Oblique muscle• Origin: ribs and CC 5-12• Insertion: linea alba via rectus sheath, iliac crest & pubic symphysis via aponeuroses of exterior abdominal oblique 4. Internal Abdominal Oblique muscle• Origin: inguinal ligament, iliac crest, thoracolumbar fascia• Insertion: linea alba via rectus sheath, ribs 10-12, CC 7-12, and pubis5. Transverse Abdominal muscle• Origin: thoracolumbar fascia, inguinal ligament, and CC 7-12• Insertion: linea alba via rectus sheath, pubis, and