Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Includes all skeletal muscle tissue that can be controlled voluntarily Muscular system

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Organization of skeletal muscle fibers Parallel muscle- Fascicles (s.: fasciculus; small bundle; collection of muscle fibers) are parallel to the long axis of the muscle. Convergent muscle- Muscle fibers are spread over a broad area, but all fascicles converge at one common attachment site. Circular muscle (sphincter)- Fibers are concentrically arranged around an opening or recess. When muscle contracts, the diameter of the opening decreases.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings - Pennate muscle- Fascicles form a common angle with the tendon. Do not move tendon as far as parallel muscles. Unipennate - All muscle fibers are in same side as tendon. Ex.: extensor digitorum muscle (forearm muscle that extends the finger joints). Bipennate - Fibers on both sides of tendon. Ex.: rectus femorus muscle (muscle that extends knee). Multipennate - Tendon branches within a pennate muscle. Ex.: deltoid muscle of shoulder. Organization of skeletal muscle fibers, continue

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.1 Figure 11.1 Different Arrangements of Skeletal Muscle Fibers

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rigid structure that moves on a fixed point, the fulcrum Changes direction and strength of applied force Changes distance and speed of movement Three classes First class: Sea-saw lever (ex.: one involved in extension of neck). Fulcrum (Ful) lies between the applied force (AF) and the resistance (R). Second class- R is located between AF and Ful (ex.: when performing an ankle extension (plantar flexion), calf muscles use second-class lever). Third class- Force is applied between R and Ful (ex.: barbell curl motion). Most common in the body Levers

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.2 The Three Classes of Levers Figure 11.2a

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.2 The Three Classes of Levers Figure 11.2b

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.2 The Three Classes of Levers Figure 11.2c

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscles can be identified by origin, insertion and action Origin = stationary end Insertion = movable end Origins and Insertions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscles can be classified by action Agonist (prime mover)- Muscle whose contraction is mainly responsible for producing a particular movement. Ex.: biceps brachii muscle is an agonist that produces flexion at the elbow. Antagonist- Muscle whose action opposes that of a particular agonist. Ex.: triceps brachii is an agonist that extends elbow, thus is an antagonist of biceps brachii. Synergist- When a synergist contracts, it helps a larger agonist work efficiently. May provide additional pull near the insertion or may stabilize the point of origin. Fixator- A synergist that may also assist an agonist by preventing movement at another joint and thereby stabilize the origin of the agonist. Actions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Names give clues to muscle characteristics Location Fascicle organization Relative position Structure Size Shape Origin and insertion Action Names of skeletal muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Axial musculature arises on axial skeleton Positions head and spinal column and moves the rib cage Appendicular musculature moves and stabilizes components of the appendicular skeleton Axial and Appendicular Muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.3 Figure 11.3 An Overview of the Major Skeletal Muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.3 Figure 11.3 An Overview of the Major Skeletal Muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Logical groupings based on location and/or function Head and neck Vertebral column Oblique and rectus muscles Pelvic floor Axial muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Facial expression muscles Orbicularis oris Buccinator Occipitofrontalis muscles Platysma Muscles of the head and neck

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.4 Muscles of Facial Expression Figure 11.4a

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11.4 Muscles of Facial Expression Figure 11.4b