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Muscular SystemChapter 11 – Lecture Notes

to accompany

Anatomy and Physiology: From Science to Life

textbook by

Gail Jenkins, Christopher Kemnitz, Gerard Tortora

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Chapter Overview11.1 Physiology of Movement11.2 Naming Skeletal Muscles11.3 Muscles of Head11.4 Muscles of Neck11.5 Muscles of Torso11.6 Muscles of Pelvic Floor11.7 Muscles of Thorax, Pectoral Girdle and

Movement of Upper Limb11.8 Muscles of Vertebral Column11.9 Muscle of Pelvic Girdle and Movement of

Lower Limb

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Essential Termsmuscular 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

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Introduction Almost 700 individual skeletal muscles primary function is to produce

movements of body parts also function to stabilize bones

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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

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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

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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

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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

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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

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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 Most skeletal muscle names contain

combinations of word roots for their features1. pattern of muscle’s fascicles

2. size

3. shape

4. action

5. number of origins

6. location of muscle

7. sites of origin and insertion

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Table 11.2 pt 1

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Table 11.2 pt 2

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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

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Figure 11.3ab

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Figure 11.3c

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Table 11.3 pt 1

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Table 11.3 pt 2

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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

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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

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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

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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

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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

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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 WallFunctions 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

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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

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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

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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

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Figure 11.12