Muscular System

Chapter 11 – Lecture Notes to accompany

Anatomy and Physiology: From Science to Life

textbook by Gail Jenkins, Christopher Kemnitz, Gerard Tortora 1

Chapter Overview 11.1 Physiology of Movement 11.2 Naming Skeletal Muscles 11.3 Muscles of Head 11.4 Muscles of Neck 11.5 Muscles of Torso 11.6 Muscles of Pelvic Floor 11.7 Muscles of Thorax, Pectoral Girdle and Movement of Upper Limb 11.8 Muscles of Vertebral Column 11.9 Muscle of Pelvic Girdle and Movement of Lower Limb 2

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Essential Terms muscular system

voluntarily controlled skeletal tissues of body

bilateral

 occurring on both sides of body

lever

 rigid structure that moves around a fixed point called a fulcrum

effort

 force that causes movement

load

 resistance to movement 3

Introduction  Almost 700 individual skeletal muscles  primary function is to produce movements of body parts  also function to stabilize bones 4

Concept 11.1

Physiology of Movement

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   Physiology of Movement skeletal muscles that produce movements do so by exerting force on tendons of articulating bones during muscle contraction one bone is pulled toward another  origin end of muscle at stationary bone   insertion end of muscle at movable bone   body fleshy part of bone between tendons 6

  Lever Systems and Leverage bones act as levers  joints are the fulcrums   levers can operate  at a mechanical advantage when a smaller effort can move a heavier load   at a mechanical disadvantage when a larger effort moves lighter load position of effort, load, and fulcrum on lever determine mechanical advantage or disadvantage 7

 Effects of Fascicle Arrangement fibers within a fascicle are parallel      fascicles are arranged in one of five patterns parallel fusiform (like a cigar) circular triangular   pennate (like a feather) fascicular arrangement affects muscle’s power and range of motion 8

 Fascicular Arrangement    range of motion  measure in degrees of a circle through which bones of a joint can be moved longer and more parallel the fibers greater range of motion    power depends on total cross-sectional area thicker muscles have more power fascicular arrangement is a compromise of range of motion and power 9

Figure 11.1

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Coordination within Muscle Groups      prime mover or agonist muscle that causes a desired action  antagonist muscle that opposes the desired action, stretching and yielding to movement of prime mover   fixator stabilizes the prime mover increasing efficiency several for some movements muscles can generally switch roles depending on movement 11

Figure 11.13ab

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Figure 11.13cd

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Concept 11.2

Naming Skeletal Muscles

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Naming Skeletal Muscles  1.

Most skeletal muscle names contain combinations of word roots for their features pattern of muscle’s fascicles 2.

3.

4.

5.

size shape action number of origins 6.

7.

location of muscle sites of origin and insertion 15

Table 11.2 pt 1 16

Table 11.2 pt 2 17

Figure 11.2a

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Figure 11.2b

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Concept 11.3

Muscles of the Head

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    Muscles of the Facial Expression muscles lie within layers of superficial fascia originate on fascia or on bones of skull insert into skin or other muscles rather than bones move skin rather than a joint in contraction 21

Figure 11.3ab

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Figure 11.3c

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Table 11.3 pt 1 24

Table 11.3 pt 2 25

Muscles of the Eyeball Movement     extrinsic originate outside the eyeball in the orbit insert on outer surface of eyeball in various directions    intrinsic   originate and insert entirely within eyeball move structures inside the eyeball iris lens 26

Figure 11.4a

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Figure 11.4b

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Table 11.4

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Muscles that Move the Mandible     also called muscles of mastication involved in chewing assist in speech also protract the mandible 30

Figure 11.5

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Table 11.5

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Muscles That Move the Tongue    extrinsic originate outside the tongue and insert into it move entire tongue in various directions    intrinsic originate and insert within the tongue alter shape of tongue 33

Figure 11.6

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Table 11.6

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Concept 11.4

Muscles of the Neck

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Muscles of the Anterior Neck   suprahyoid muscles superior to hyoid bone   infrahyoid muscles inferior to hyoid bone 37

Figure 11.7ab

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Figure 11.7cd

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Table 11.7

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Muscles That Move the Head 41

Figure 11.8

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Table 11.8

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Concept 11.5

Muscles of the Torso

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Muscles that Act on Abdominal Wall Functions    contain and protect the abdominal viscera flex, laterally flex, and rotate vertebral column at intervertebral joinings compress abdomen during forced exhalation   produce force of defecation   urination childbirth 45

Figure 11.9ab

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Figure 11.9c

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Table 11.9

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   Muscles Used in Breathing diaphragm external intercostal internal intercostal 49

Figure 11.10ab

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Figure 11.10c

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Figure 11.10d

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Table 11.10

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Concept 11.6

Muscles of the Pelvic Floor

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 Muscles of the Pelvic Floor pelvic diaphragm group  levator ani group 55

Figure 11.11

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Table 11.11

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Muscles of the Perineum  two layers    deep assist in urination in males and females ejaculation in males    superficial help maintain erection of penis in males and clitoris in females facilitate ejaculation in males 58

Figure 11.12

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