2. Skeletal Muscle Structure

6. Origin and insertion Figure 10-3

7. (An example) Triceps origins are  long head - margin of glenoid cavity  lateral head - posterior humerus;  medial head - distal radial groove on posterior humerus Triceps insertion  olecranon process of ulna

8.  Flexion - closes a joint (ex: bicep flexes arm)  Extension - opens a joint (ex: tricep extends arm) Types of muscle action flexing knee extending knee

9. Flexor Extender

10.  Adduction - draw towards body (ex: Latissimus dorsi “Lats” adducts humerus)  Abduction - moves from body (ex: Gluteus minimus abducts femur - origin at illium) Types of muscle action

12. Oxidative - resistant to fatigue, high rate of O 2 transfer from blood (SO) Myoglobin, more mitochondria Glycolytic - more prone to fatigue b/c less ATP produced (FG), ATP made quickly Endurance vs. Bursts of power Fast and slow twitch muscle cells

13. People are born with certain ratio of slow vs. fast twitch fibers usually an even mix in most skeletal muscles Fast and slow twitch muscle cells

14.  Turkey vs. Duck  Pike vs. Mackerel Duck breast muscle chicken breast pike mackerel

15. Which causes furthest movement of bone? Which is strongest? Muscle architecture

16. Muscle architecture: length The distance a muscle contracts is determined by muscle length (# of sarcomeres) Muscles of different lengths contract within the same amount of time

17. Pennate fiber orientation can increase the number of fibers/area to increase force Muscle architecture: cross-section area

18. Axial vs. appendicular muscle  Epaxials, hypaxials Muscle development

19. Axials – Contraction causes bending, not shortening A single myomere exerts influence over a large area of spine p.355 Fish axial musculature and swimming

20. Zig-zag shape more pronounced at tail – affect size of undulations Fish axial musculature and swimming

21. Drag increases with velocity

22. Normal arrangement of red fibers allows contractions with less bending – less drag Drag increases with velocity

23. 

24.  Tuna, mako and white sharks have red fibers deep in musculature Fish endothermy

25. Constant oxidation at deep red fibers allows these fish to be endothermic Fish endothermy

26. Axial muscles in tetrapods

27. Rectus abdominis, Obliques, Transversus  Amniotes – intercostals  Mammals - diaphragm Hypaxials in tetrapods

28. In tetrapods, epaxial muscles function in posture and respiration Epaxials in tetrapods

29. Found in Chondrichthyes and Osteichthyes Stacked modified muscle cells, often axial muscle Electric organs

30. 

31. Cells do not contract, yet produce electrical signals via ion channels Strong net current is produced when many cells in a row are stimulated simultaneously Electric organs