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VALENCIA BSC 2093C - Lecture Notes

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Effects of Fascicle ArrangementCHAPTER 11LECTURE OUTLINEINTRODUCTION1. Distinguish the tissues that constitute the skeletal system. HOW SKELETAL MUSCLES PRODUCE MOVEMENTMuscle Attachment Sites: Origin and Insertion2. Define the terms origin and insertion.3. Show the relationship between the usual location of the belly of a muscle and the more mobile bones of its insertion.4. Describe tenosynovitis and its possible causes.Lever System and Leverage5. Define lever, fulcrum and mechanical advantage. Compare the three classes oflevers on the basis of placement of the fulcrum, effort, and resistance, with respect to examples of muscle systems on the body.Effects of Fascicle Arrangement6. Identify the various arrangements of muscle fibers in a skeletal muscle and relate the arrangements to the strength of contraction and range of motion. 7. Compare the advantages and disadvantages of intramuscular injection to subcutaneous injection and oral medications.Coordination Within Muscle Groups8. Discuss most body movements as activities of groups of muscles by explaining the roles of the prime mover, antagonist, synergist, and fixator.9. Examine the effects of stretching for range of motion and mobility of soft tissues.HOW SKELETAL MUSCLES ARE NAMED10. Define the criteria employed in naming skeletal muscles.PRINCIPAL SKELETAL MUSCLES11. Identify the principal skeletal muscles in different regions of the body by name, origin, insertion, and action.12. Identify and discuss the various clinical problems associated with the differentmuscle groups.DISORDERS: HOMEOSTATIC IMBALANCES13. Describe the prevalence and cause of common injuries related to running.14. Describe compartment syndrome, its causes and untreated outcome.Suggested Lecture OutlineI. INTRODUCTIONA. The muscular system specifically concerns skeletal muscles and associated connective tissue that make individual muscle organs.B. This chapter discusses how skeletal muscles produce movement and describesthe principal skeletal muscles.II. HOW SKELETAL MUSCLES PRODUCE MOVEMENTA. Muscle Attachment Sites: Origin and Insertion1. Skeletal muscles produce movements by exerting force on tendons, which in turn pull on bones or other structures, such as skin.2. Most muscles cross at least one joint and are attached to the articulating bones that form the joint (Figure 11.1a).3. When such a muscle contracts, it draws one articulating bone toward the other.a. The attachment to the stationary bone is the origin.b. The attachment to the movable bone is the insertion.4. Tenosynovitis is an inflammation of the tendons, tendon sheaths, and synovial membranes surrounding certain joints (Clinical Connection).B. Lever Systems and Leverage1. Bones serve as levers and joints serve as fulcrums.2. The lever is acted on by two different forces: resistance (load) and effort (Figure 11.1b).3. Levers are categorized into three types, according to the position of thefulcrum, effort, and loada. first-class (EFL) (Figure 11.2a)-the fulcrum is between the effort and the load. An example is pair of scissors.b. second-class (FLE) (Figure 11.2b)- the load is between the fulcrum and effort. An example is a wheelbarrow.c. third-class (FEL) (Figure 11.2c).-the effort is between the fulcrum and the load. An example is a pair of forceps.4. Leverage, the mechanical advantage gained by a lever, is largely responsible for a muscle’s strength and range of motion (ROM), i.e., the maximum ability to move the bones of a joint through an arc.C. Effects of Fascicle Arrangement1. Skeletal muscle fibers (cells) are arranged within the muscle in bundles called fasciculi.2. The muscle fibers are arranged in a parallel fashion within each bundle, but the arrangement of the fasciculi with respect to the tendonsmay take one of four characteristic patterns: parallel, fusiform, pennate, and circular (Table 11.1).3. Fascicular arrangement is correlated with the power of a muscle and the range of motion.4. Intramuscular injections have advantages, and disadvantages, over oral or subcutaneous delivery of medications (Clinical Connection)D. Coordination Within Muscle Groups1. Most movements are coordinated by several skeletal muscles acting in groups rather than individually, and most skeletal muscles are arrangedin opposing (antagonistic) pairs at joints.2. A muscle that causes a desired action is referred to as the prime mover (agonist); the antagonist produces an opposite action.3. Most movements also involve muscles called synergists, which serve to steady a movement, thus preventing unwanted movements and helping the prime mover function more efficiently.4. Some synergist muscles in a group also act as fixators, which stabilize the origin of the prime mover so that it can act more efficiently.5. Under different conditions and depending on the movement and whichpoint is fixed, many muscles act, at various times, as prime movers, antagonists, synergists, or fixators.6. Some of the benefits of stretching (Clinical Connection) include: improved physical performance, decreased risk of injury, reduced muscle soreness, improved posture, increased synovial fluid, and increased neuromuscular co-ordination.III. HOW SKELETAL MUSCLES ARE NAMEDA. Muscle naming involves many categories such as:1. Location2. Size3. Number or origins4. Appearance5. Direction of fibers6. Origin and insertion7. Muscle action8. CombinationsB. Origins and insertions1. Muscles exert force by pulling on tendons and moving bonesa. Insertion: moves toward the originb. Origin: stationary2. Show examples of insertions on cadaver and illustration of the biceps brachii.C. Musculoskeletal Levers1. First class lever2. Second class lever3. Third class leverD. Coordination among muscles1. Prime mover (agonist)a. Primarily responsible for causing the desired movement2. Antagonista. Stretches and yields to the effects of the prime mover3.a. Prevent unwanted movements of intermediate jointsb. aid movement of the primer mover4. Fixatora. Steady proximal joints of prime moverIV. PRINCIPAL SKELETAL MUSCLESA. Exhibits 11.A through 11.T list the principle skeletal muscles in various regions of the body.B. Discuss the origin, insertion and action of the major skeletal muscles listed in the PowerPoint1. Muscles of facial expressiona. Orbicularis oris(1) action: closes and protrudes lips(2) origin: surrounding opening of mouth(3) insertion: corner of mouthb. Extraoccular(1) Action: precise and rapid eye


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