Chapter 10

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Chapter 10
2012-10-06 23:35:21
Muscular System

Anatomy of the Muscular System
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  1. Endomysium
    delicate connective tissue membrane that covers skeletal muscle fibers (each fiber)
  2. Perimysium
    tough connective tissue binding together fascicles
  3. Epimysium
    coarse sheath covering the muscle as a whole
  4. Fascia
    is the fibrous connective tissue that surrounds the muscle and is outside the epimysium & tendon
  5. Origin
    point of attachment that does not move when muscle contracts (usually proximal point)
  6. Insertion
    point of attachment that moves when muscle contracts (usually distal point)
  7. Belly
    is the central body portion of the muscle
  8. Prime movers (agonists)
    muscles or groups of muscles that directly perform a specific movement
  9. Antagonists
    muscles that, when contracting, directly oppose prime movers; relax while prime movers (agonists) are contracting to produce movement; provide precision and control during contraction of prime movers
  10. Synergists
    muscles that contract at the same time as the prime movers; they facilitate prime movers’ actions to produce a more efficient movement
  11. Fixator muscles
    joint stabilizers (page 298, 7th ed,)
  12. Lever system
    • composed of four component parts (Figure 10-4):
    • •Rigid bar (bone)
    • •Fulcrum (F) around which the rod moves (joint)
    • •Load (L) that is moved
    • •Pull (P) that produces movement (muscle contraction)
  13. First-class levers
    • •Fulcrum lies between the pull and the load
    • •Not abundant in human body; serve as levers of stability
  14. Second-class levers
    • •Load lies between the fulcrum and the pull
    • •Controversy exists regarding presence of these levers in the human body
  15. Third-class levers
    • •Pull is exerted between the fulcrum and the load
    • •Permit rapid and extensive movement
    • •Most common type of lever found in the body
  16. Muscles of facial expression
    unique in that at least one point of attachment is to the deep layers of the skin over the face or neck. Buccinator muscle is responsible for facilitating smiling. (Figures 10-7 and 10-8; Table 10-6)
  17. Muscles of mastication
    responsible for chewing movements. Masseter muscle assists with mastication. (Figure 10-9; Table 10-6)
  18. Muscles that move the head
    paired muscles on either side of the neck are responsible for head movements (Figure 10-10; Table 10-7)
  19. Muscles of the thorax
    critical importance in respiration. External intercostals elevates the ribs (inspiration) while internal intercostals & innermost intercostals lower the ribs (expiration). (Figure 10-9; Table 10-8)
  20. Muscles of the abdominal wall
    arranged in three layers, with fibers in each layer running in different directions to increase strength (Figure 10-12; Table 10-9)
  21. Muscles of the back
    bend or stabilize the back (Figure 10-13; Table 10-10)
  22. Muscles of the pelvic floor
    support the structures in the pelvic cavity. The Levator ani muscle makes most of the pelvic floor. (Figure 10-14; Table 10-11)
  23. Muscles that move the upper arm
    originate on the clavicle and scapula.
  24. Rotator cuff muscles (move the shoulder)
    supraspinatus, infraspinatus, subscapularis, and teres minor