1. Based on patterns of fascicle organization, name the four classifications of skeletal
muscle tissue.
a. Based on the patterns of fascicle organization, skeletal muscles can be classified
as parallel muscles, convergent muscles, pennate muscles, or circular muscles.
2. Why does a pennate muscle generate more tension than does a parallel muscle of the
same size?
a. Contraction of a pennate muscle generates more tension than would contraction of
a parallel muscle of the same size because a pennate muscle contains more muscle
fibers, and thus more myofibrils and sarcomeres, than does a parallel muscle of
the same size.
3. Which type of fascicle arrangement would you expect in a muscle guarding the opening
between the stomach and the small intestine?
a. The opening between the stomach and the small intestine would be guarded by a
circular muscle, or sphincter. The concentric circles of muscle fibers found in
sphincters are ideally suited for opening and closing passageways and for acting
as valves in the body.
4. Define a lever, and describe the three classes of levers.
a. A lever is a rigid structure—such as a board, a pry bar, or a bone—that moves on
a fixed joint called the fulcrum. There are three classes of levers: In a first-class
lever, the fulcrum lies between the applied force and load; in a second-class lever,
the load lies between the applied force and fulcrum; and in a third-class lever, the
applied force or pull exerted is between the fulcrum and the load. Third-class
levers are the most common type in the body.
5. The joint between the occipital bone of the skull and the first cervical vertebra (atlas) is
an example of which class of lever?
a. The joint between the occipital bone and the first cervical vertebra is part of a
first-class lever system. The joint between the two bones (the fulcrum) lies
between the skull (which provides the load) and the neck muscles (which provide
the applied force).
6. The gracilis muscle is attached to the anterior surface of the tibia at one end, and to the
pubis and ischium of the pelvis at the other.
7. When the muscle contracts, flexion occurs at the hip. Which attachment point is
considered the muscle's origin?
a. The origin of a muscle is the end that remains stationary during an action.
Because the gracilis muscle moves the tibia, the origin of this muscle must be on
the pelvis (pubis and ischium).
8. Muscle A abducts the humerus, and muscle B adducts the humerus. What is the
relationship between these two muscles?
a. Muscles A and B are antagonists to each other, because they perform opposite
actions.
, 9. Define the term synergist as it relates to muscle action.
a. A synergist is a muscle that helps a larger prime mover (or agonist—a muscle that
is responsible for a specific movement) perform its actions more efficiently.
10.Identify the kinds of descriptive information used to name skeletal muscles.
a. Names of skeletal muscles are based on several factors, including location in the
body, origin and insertion, fascicle organization, relative position, structural
characteristics, and action. Names may also reflect the muscle shape, number of
origins, and size.
11.What does the name flexor carpi radialis longus tell you about this muscle?
a. The name flexor carpi radialis longus tells you that this muscle is a long muscle
(longus) that lies next to the radius (radialis) and flexes (flexor) the wrist (carpi).
12.Describe the location of axial muscles.
a. Axial muscles arise on the axial skeleton. They position the head, neck, and
vertebral column, move the rib cage, and form the perineum.
13.If you were contracting and relaxing your masseter muscle, what would you probably be
doing?
a. Contraction of the masseter muscle elevates the mandible, and relaxation of this
muscle depresses the mandible. You would probably be chewing something.
14.Which facial muscle would you expect to be well developed in a trumpet player?
a. You would expect the buccinator muscle, which positions the mouth for blowing,
to be well developed in a trumpet player.
15.Why can swallowing help alleviate the pressure sensations at the eardrum when you are
in an airplane that is changing altitude?
a. Swallowing involves contractions of the palatal muscles, which elevate the soft
palate as well as portions of the superior pharyngeal wall. Elevation of the
superior portion of the pharynx enlarges the opening to the auditory tube,
permitting airflow to the middle ear and the inside of the eardrum. Making this
opening larger by swallowing facilitates airflow into or out of the middle ear
cavity.
16.Damage to the external intercostal muscles would interfere with what important process?
a. Breathing.
17.If someone hit you in your rectus abdominis muscle, how would your body position
change?
a. A hit in the rectus abdominis muscle would cause that muscle to contract
forcefully, resulting in flexion of the vertebral column. In other words, you would
"double over."
18.After spending an afternoon carrying heavy boxes from his basement to his attic, Joe
complains that the muscles in his back hurt. Which muscles are most likely sore?
a. The sore muscles are most likely the erector spinae muscles, especially the
longissimus and the iliocostalis muscles of the lumbar region. These muscles
muscle tissue.
a. Based on the patterns of fascicle organization, skeletal muscles can be classified
as parallel muscles, convergent muscles, pennate muscles, or circular muscles.
2. Why does a pennate muscle generate more tension than does a parallel muscle of the
same size?
a. Contraction of a pennate muscle generates more tension than would contraction of
a parallel muscle of the same size because a pennate muscle contains more muscle
fibers, and thus more myofibrils and sarcomeres, than does a parallel muscle of
the same size.
3. Which type of fascicle arrangement would you expect in a muscle guarding the opening
between the stomach and the small intestine?
a. The opening between the stomach and the small intestine would be guarded by a
circular muscle, or sphincter. The concentric circles of muscle fibers found in
sphincters are ideally suited for opening and closing passageways and for acting
as valves in the body.
4. Define a lever, and describe the three classes of levers.
a. A lever is a rigid structure—such as a board, a pry bar, or a bone—that moves on
a fixed joint called the fulcrum. There are three classes of levers: In a first-class
lever, the fulcrum lies between the applied force and load; in a second-class lever,
the load lies between the applied force and fulcrum; and in a third-class lever, the
applied force or pull exerted is between the fulcrum and the load. Third-class
levers are the most common type in the body.
5. The joint between the occipital bone of the skull and the first cervical vertebra (atlas) is
an example of which class of lever?
a. The joint between the occipital bone and the first cervical vertebra is part of a
first-class lever system. The joint between the two bones (the fulcrum) lies
between the skull (which provides the load) and the neck muscles (which provide
the applied force).
6. The gracilis muscle is attached to the anterior surface of the tibia at one end, and to the
pubis and ischium of the pelvis at the other.
7. When the muscle contracts, flexion occurs at the hip. Which attachment point is
considered the muscle's origin?
a. The origin of a muscle is the end that remains stationary during an action.
Because the gracilis muscle moves the tibia, the origin of this muscle must be on
the pelvis (pubis and ischium).
8. Muscle A abducts the humerus, and muscle B adducts the humerus. What is the
relationship between these two muscles?
a. Muscles A and B are antagonists to each other, because they perform opposite
actions.
, 9. Define the term synergist as it relates to muscle action.
a. A synergist is a muscle that helps a larger prime mover (or agonist—a muscle that
is responsible for a specific movement) perform its actions more efficiently.
10.Identify the kinds of descriptive information used to name skeletal muscles.
a. Names of skeletal muscles are based on several factors, including location in the
body, origin and insertion, fascicle organization, relative position, structural
characteristics, and action. Names may also reflect the muscle shape, number of
origins, and size.
11.What does the name flexor carpi radialis longus tell you about this muscle?
a. The name flexor carpi radialis longus tells you that this muscle is a long muscle
(longus) that lies next to the radius (radialis) and flexes (flexor) the wrist (carpi).
12.Describe the location of axial muscles.
a. Axial muscles arise on the axial skeleton. They position the head, neck, and
vertebral column, move the rib cage, and form the perineum.
13.If you were contracting and relaxing your masseter muscle, what would you probably be
doing?
a. Contraction of the masseter muscle elevates the mandible, and relaxation of this
muscle depresses the mandible. You would probably be chewing something.
14.Which facial muscle would you expect to be well developed in a trumpet player?
a. You would expect the buccinator muscle, which positions the mouth for blowing,
to be well developed in a trumpet player.
15.Why can swallowing help alleviate the pressure sensations at the eardrum when you are
in an airplane that is changing altitude?
a. Swallowing involves contractions of the palatal muscles, which elevate the soft
palate as well as portions of the superior pharyngeal wall. Elevation of the
superior portion of the pharynx enlarges the opening to the auditory tube,
permitting airflow to the middle ear and the inside of the eardrum. Making this
opening larger by swallowing facilitates airflow into or out of the middle ear
cavity.
16.Damage to the external intercostal muscles would interfere with what important process?
a. Breathing.
17.If someone hit you in your rectus abdominis muscle, how would your body position
change?
a. A hit in the rectus abdominis muscle would cause that muscle to contract
forcefully, resulting in flexion of the vertebral column. In other words, you would
"double over."
18.After spending an afternoon carrying heavy boxes from his basement to his attic, Joe
complains that the muscles in his back hurt. Which muscles are most likely sore?
a. The sore muscles are most likely the erector spinae muscles, especially the
longissimus and the iliocostalis muscles of the lumbar region. These muscles
