The muscular system (part a), the following will be discussed in this chapter: Skeletal muscles: functional groups, naming skeletal muscles, muscle mechanics: arrangement of fascicles, muscle mechanics: lever systems, classes of lever systems,. | 10 The Muscular System: Part A Skeletal Muscles: Functional Groups Prime movers Provide the major force for producing a specific movement Antagonists Oppose or reverse a particular movement Skeletal Muscles: Functional Groups Synergists Add force to a movement Reduce undesirable or unnecessary movement Fixators Synergists that immobilize a bone or muscle’s origin Naming Skeletal Muscles Location—bone or body region associated with the muscle Shape—., deltoid muscle (deltoid = triangle) Relative size—., maximus (largest), minimus (smallest), longus (long) Direction of fibers or fascicles—., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis) Naming Skeletal Muscles Number of origins—., biceps (2 origins) and triceps (3 origins) Location of attachments—named according to point of origin or insertion Action—., flexor or extensor, muscles that flex or extend, respectively Muscle Mechanics: Arrangement of Fascicles Circular Fascicles arranged in concentric rings (., orbicularis oris) Convergent Fascicles converge toward a single tendon insertion (., pectoralis major) Muscle Mechanics: Arrangement of Fascicles Parallel Fascicles parallel to the long axis of a straplike muscle (., sartorius) Fusiform Spindle-shaped muscles with parallel fibers (., biceps brachii) Muscle Mechanics: Arrangement of Fascicles Pennate Short fascicles attach obliquely to a central tendon running the length of the muscle (., rectus femoris) Figure (a) (b) (e) (d) (g) (f) (c) Circular (orbicularis oris) (b) Convergent (pectoralis major) (c) Parallel (sartorius) (d) Unipennate (extensor digitorum longus) (f) Fusiform (biceps brachii) (g) Multipennate (deltoid) (e) Bipennate (rectus femoris) Muscle Mechanics: Lever Systems Components of a lever system Lever—rigid bar (bone) that moves on a fixed point or fulcrum (joint) Effort—force (supplied by muscle contraction) applied to a lever to move a resistance . | 10 The Muscular System: Part A Skeletal Muscles: Functional Groups Prime movers Provide the major force for producing a specific movement Antagonists Oppose or reverse a particular movement Skeletal Muscles: Functional Groups Synergists Add force to a movement Reduce undesirable or unnecessary movement Fixators Synergists that immobilize a bone or muscle’s origin Naming Skeletal Muscles Location—bone or body region associated with the muscle Shape—., deltoid muscle (deltoid = triangle) Relative size—., maximus (largest), minimus (smallest), longus (long) Direction of fibers or fascicles—., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis) Naming Skeletal Muscles Number of origins—., biceps (2 origins) and triceps (3 origins) Location of attachments—named according to point of origin or insertion Action—., flexor or extensor, muscles that flex or extend, respectively Muscle Mechanics: Arrangement of Fascicles .
