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Muscular System Chapter 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 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
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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
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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 features pattern of muscle’s fascicles size shape action number of origins location of muscle 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 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
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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
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