Download Thibodeau: Anatomy and Physiology, 5/e Chapter 10: Anatomy of

Thibodeau: Anatomy and Physiology, 5/e
Chapter 10: Anatomy of the Muscular System
Virtually every deliberate action we perform is accomplished by the contraction of skeletal
muscle. Purposeful body movement is in turn determined by the manner in which muscles are shaped and
grouped, the muscles' relationship to joints, and how the muscles attach to the skeleton.
Muscle fibers are covered with a delicate connective tissue membrane called the endomysium.
Groups of skeletal muscle fibers (fascicles) are bound together by a tougher connective tissue called the
perimysium, and finally, the muscle as a whole is covered by a coarse sheath called the epimysium. These
three structures are continuous with the fibrous structures (e.g., tendons) that attach muscles to bones or
other structures. Most of our muscles span at least one joint and attach to both articulating bones. When
contraction occurs, one bone usually remains fixed and the other moves. The origin is the point of
attachment that does not move when the muscle contracts, whereas the insertion is the point of attachment
that does move when the muscle contracts. Many muscles have multiple points of origin or insertion.
Skeletal muscles usually act in groups rather than singly, with some muscles playing the role of
prime movers, antagonists, synergists, or fixators. Lever systems can help us understand muscle action as
either first-class, second-class, or third-class levers. Muscles are named and categorized quite logically
according to location, function, shape, direction of fibers, number of heads or divisions, or points of
attachment.
Muscles of facial expression are unique in that at least one point of attachment is to the deep layers
of the skin over the face or neck; muscles of mastication are responsible for chewing, and paired muscles
on either side of the neck are responsible for head movements. Other important skeletal muscles include the
trunk muscles, upper limb muscles, and lower limb muscles. Maintaining posture is one of the major roles
of the muscles; this involves maintaining a body alignment that most favors function, requires the least
muscular work, and keeps the body's center of gravity over its base. Muscle cells change in number, size,
and the ability to shorten at different periods of the life cycle or as the result of certain pathological
conditions.
Objectives
After students have completed this chapter, they should be able to:
1.
List the major connective tissue elements related to skeletal muscle.
2.
Discuss the attachment of muscles.
3.
Explain the functional classification of muscles based on movement pattern.
4.
Identify six features that may be used to name a muscle.
5.
Identify major muscles, their points of attachment, and their function in the following areas:
a.
Muscles of facial expression
b.
Muscles of mastication
c.
Muscles that move the head
d.
Muscles that move the abdominal and chest wall
e.
Muscles of the pelvic floor
f.
Muscles acting on the shoulder girdle
g.
Muscles that move the upper and lower arm
h.
Muscles that move the wrist, hand, and fingers
i.
Muscles that move the thigh and lower leg
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Chapter 10: Anatomy of the Muscular System
j.
6.
Muscles that move the ankle and foot
Define posture and discuss its importance to the body as a whole.
Lecture Outline
I.
Introduction (Figs. 10-1, 10-2)
II.
Skeletal Muscle Structure (p. 281)
A.
B.
C.
D.
Connective tissue components (Fig. 10-3)
1.
Endomysium
2.
Perimysium
3.
Epimysium
4.
Tendon
5.
Aponeurosis
6.
Tendon sheath
Size, shape, and fiber arrangement (p. 282)
1.
Parallel (Fig. 10-4, A)
2.
Convergent (Fig. 10-4, B)
3.
Pennate (Fig. 10-4, C)
4.
Bipennate (Fig. 10-4, D)
5.
Sphincter (Fig. 10-4,E)
Attachment of muscles (Fig. 10-5)
1.
Origin
2.
Insertion
Muscle actions (p. 283)
1.
2.
E.
III.
Functional classification of muscle groups
a.
Prime mover (agonist)
b.
Antagonist
c.
Synergist
d.
Fixator
Specific muscle actions (see Types and Range of Movement at
Synovial Joints, p.
268)
Lever systems (Fig. 10-6)
1.
First-class levers
2.
Second-class levers
3.
Third-class levers
How Muscles Are Named (Figs. 10-1, 10-2)
A.
Features used in naming muscles
1.
Location
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Chapter 10: Anatomy of the Muscular System
B.
IV.
V.
VI.
VII.
Shape
4.
Direction of fibers
5.
Number of heads or divisions
6.
Points of attachment
7.
Size of muscle
Hints on how to deduce muscle actions (p. 286)
1.
Be familiar with name, shape, and location (Table 10-1)
2.
From shape and location, deduce name of origin and insertion bone
3.
Determine which bone moves when muscle contracts
4.
Deduce action—insertion moves toward origin
5.
Deduce which muscle gives a specific action
Muscles of facial expression (Fig. 10-7; Table 10-3)
B.
Muscles of mastication (Fig. 10-7; Table 10-3)
C.
Muscles that move the head (Fig. 10-8; Table 10-4)
Trunk Muscles (p. 289)
A.
Muscles of the thorax (Fig. 10-9; Table 10-5)
B.
Muscles of the abdominal wall (Fig. 10-10; Table 10-6)
C.
Muscles of the back (Fig. 10-11; Table 10-7)
D.
Muscles of the pelvic floor (Fig. 10-12; Table 10-8)
Upper Limb Muscles (p. 293)
A.
Muscles acting on the shoulder girdle (Fig. 10-13; Table 10-9)
B.
Muscles that move the upper arm (Figs. 10-14, 10-15; Table 10-10)
C.
Muscles that move the forearm (Figs. 10-16, 10-17; Table 10-11)
D.
Muscles that move the wrist, hand, and fingers (Figs. 10-18, 10-19, 10-20; Table 10-12)
Lower Limb Muscles (p. 300)
Muscles that move the thigh and lower leg (Figs. 10-1, 10-2, 10-22 to 10-27; Tables 10Muscles that move the ankle and foot (Figs. 10-28, 10-29; Table 10-15)
Posture (p. 306)
A.
How posture is maintained
Cycle of Life: Muscular System (p. 308)
A.
sequences
B.
X.
3.
A.
B.
IX.
Function
Important Skeletal Muscles (p. 286)
A.
13, 10-14)
VIII.
2.
During infancy and childhood, muscle coordination and control allows developmental
to occur
Degeneration of muscles with age includes replacement with connective tissue
The Big Picture: Skeletal Muscles and the Whole Body (p. 308)
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