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6
CHAPTER SUMMARY
The muscular system presents challenges similar to those in the skeletal system in that this system
requires both the conceptualization of complex mechanisms and the memorization of numerous terms.
Providing students with a list of criteria used in the naming of muscles helps them overcome their
anxieties and helps them view the task as manageable.
This chapter begins with an overview of muscle types. Skeletal, smooth, and cardiac muscle
are discussed, and their differences as well as similarities in microscopic appearance and level of
conscious control are emphasized. The applied anatomy of a muscle is presented, from the
endomysium that covers a single muscle fiber to the epimysium that covers an entire muscle. The
functions of muscle are explored, including movement, maintenance of posture, joint stabilization, and
heat generation.
The next section of the chapter discusses the microscopic anatomy of skeletal muscle,
followed by an overview of the mechanism of muscle contraction. The sliding filament mechanism is
often confusing to students, but the explanation of muscle responses to various levels of stimulation,
muscle fatigue and its relationship to available oxygen, and the types of muscle contractions help to
clarify this concept.
In the final sections of the chapter, the “5 Golden Rules” of skeletal muscle activity
are presented to help students comprehend muscle movements and their related interactions. First, the
types of body movements generated by muscles are explained. Then a basic list of criteria for naming
muscles is provided to ensure that students understand the logic involved in the naming of most
muscles. Finally, the most important of the more than 600 muscles of the human body are presented,
along with their points of origin and insertion as well as function.
SUGGESTED LECTURE OUTLINE
I.
OVERVIEW OF MUSCLE TISSUES (pp. 178–182)
A.
Muscle Types (pp. 178–181)
1.
Skeletal Muscle—voluntary control of movement
a.
Connective Tissue Covering
i.
Endomysium
ii.
Perimysium
iii.
Epimysium
b.
Striated
i.
Actin
ii.
Myosin
c.
Tendons
d.
Aponeuroses
2.
Smooth Muscle—involuntary control of visceral organs
a.
Nonstriated
3.
Cardiac Muscle—involuntary control within heart walls
a.
Striated
b.
Intercalated disks
B.
Muscle Functions (pp. 181–182)
1.
Producing Movement
2.
Maintaining Posture
3.
Stabilizing Joints
4.
II.
Generating Heat
MICROSCOPIC ANATOMY OF SKELETAL MUSCLE (pp. 182–184)
1.
Sarcolemma
2.
Myofibrils
3.
Light (I) bands
4.
Dark (A) bands
5.
Myofilaments
6.
Cross bridges
7.
Sarcoplasmic reticulum (SR)
III.
SKELETAL MUSCLE ACTIVITY (pp. 184–192)
A.
Stimulation and Contraction of Single Skeletal Muscle Cells
(pp. 184–187)
1.
The Nerve Stimulus and the Action Potential
a.
Motor unit
b.
Axon
c.
Axon terminals
d.
Neuromuscular junction
e.
Synaptic cleft
f.
Neurotransmitter—acetylcholine in skeletal muscle
2.
Mechanism of Muscle Contraction: The Sliding Filament Theory
a.
Calcium ions
B.
Contraction of a Skeletal Muscle as a Whole (pp. 187–192)
1.
Graded Responses
a.
Muscle Response to Increasingly Rapid Stimulation
i.
Muscle twitches
ii.
Complete tetanus—fused
iii.
Incomplete tetanus—unfused
b.
Muscle Response to Stronger Stimuli
1.
Providing Energy for Muscle Contraction
a.
Direct phosphorylation of ADP by creatine phosphate
b.
Aerobic respiration
c.
Anaerobic glycolysis and lactic acid formation
2.
Muscle Fatigue and Oxygen Debt
3.
Types of Muscle Contractions
a.
Isotonic
b.
Isometric
4.
Muscle Tone
5.
Effect of Exercise on Muscles
a.
Aerobic exercise
i.
Mitochondria
b.
Anaerobic exercise
IV.
MUSCLE MOVEMENTS, TYPES, AND NAMES (pp. 192–200)
A.
Five Golden Rules of Muscle Activity (p. 192)
1.
Cross at least one joint—with a few exceptions
2.
Bulk of muscle lies proximal to joint crossed
3.
At least two attachments
a.
Origin
b.
Insertion
4.
Can only pull—never push
5.
Insertion moves toward origin during contraction
B.
B.
C.
D.
II.
Types of Body Movements (pp. 192–196)
1.
Flexion
2.
Extension
3.
Rotation
4.
Abduction
5.
Adduction
6.
Circumduction
7.
Dorsiflexion and Plantar Flexion
8.
Inversion and Eversion
9.
Supination and Pronation
10.
Opposition
Interactions of Skeletal Muscles in the Body (p. 196)
1.
Prime mover
2.
Antagonists
3.
Synergists
4.
Fixators
Naming Skeletal Muscles (pp. 196 and 198)
1.
Directions of muscle fibers
2.
Relative size of muscle
3.
Location of the muscle
4.
Number of origins
5.
Location of the muscle’s origin and insertion
6.
Shape of the muscle
7.
Action of the muscle
Arrangement of Fascicles (pp. 199–200)
1.
Circular
2.
Convergent
3.
Parallel
4.
Fusiform
5.
Pennate
GROSS ANATOMY OF SKELETAL MUSCLES (pp. 200–208; Figures 6.21–6.22; Tables 6.3–
6.4)
A.
Head and Neck Muscles (pp. 200–201)
1.
Facial Muscles
a.
Frontalis
b.
Orbicularis Oculi
c.
Orbicularis Oris
d.
Buccinator
e.
Zygomaticus
2.
Chewing Muscles
a.
Masseter
b.
Temporalis
3.
Neck Muscles
a.
Platysma
b.
Sternocleidomastoid
B.
Trunk Muscles (pp. 201–203)
1.
Anterior Muscles
a.
Pectoralis Major
b.
Intercostal Muscles
c.
Muscles of the Abdominal Girdle
i.
Rectus Abdominis
ii.
External Oblique
C.
D.
III.
iii.
Internal Oblique
iv.
Transversus Abdominis
2.
Posterior Muscles
a.
Trapezius
b.
Latissimus Dorsi
c.
Erector Spinae
d.
Deltoid
Muscles of the Upper Limb (pp. 203–204)
1.
Muscles of the Humerus That Act on the Forearm
a.
Biceps Brachii
b.
Brachialis
c.
Brachioradialis
d.
Triceps Brachii
Muscles of the Lower Limb (pp. 204–208)
1.
Muscles Causing Movement at the Hip Joint
a.
Gluteus Maximus
b.
Gluteus Medius
c.
Iliopsoas
d.
Adductor Muscles
2.
Muscles Causing Movement at the Knee Joint
a.
Hamstring Group
i.
Biceps Femoris
ii.
Semimembranosus
iii.
Semitendinosus
b.
Sartorius
c.
Quadriceps Group
i.
Rectus Femoris
ii.
Vastus Muscles
3.
Muscles Causing Movement at the Ankle and Foot
a.
Tibialis Anterior
b.
Extensor Digitorum Longus
c.
Fibularis Muscles
d.
Gastrocnemius
e.
Soleus
DEVELOPMENTAL ASPECTS OF THE MUSCULAR SYSTEM (p. 214)
1.
Embryonic development
a.
Maturation of muscle control
i.
Cephalic to caudal direction
ii.
Proximal to distal direction
b.
Aging effects
i.
Hypertrophy
ii.
Atrophy
2.
Homeostatic Imbalances
a.
Muscular Dystrophy
b.
Myasthenia gravis