MORS 113: Muscle Facts (Little Blue Book)

Question 1

Refers to the study of the muscular system.

Answer 1

Myology

Question 2

• Make up about 45% of body weight.
• Responsible for imparting movement to body parts.
  
  • Do this through the ability to contract (shorten in length).

Answer 2

Muscles

Question 3

The ability to contract and cause movement.

Answer 3

Contractility

Question 4

Have the ability to convert chemical energy derived from digested food products into mechanical energy, which in turn creates the contractions and movement associated with muscles.

Answer 4

Muscle Cells

Question 5

May only be 1/2 to 1/3 it’s normal length when at rest.

Answer 5

A Fully Contracted Muscle

Question 6

Specialized nerve cells (neurons) that transmit stimuli to muscle cells.

• Muscles do not contract on their own, they need these.

Answer 6

Motor Neurons

Question 7

The combination of a motor neuron and the group of muscle cells which it stimulates.

Answer 7

Motor Unit

Question 8

Generally, muscles do not act individually to create movement of a body part, but function:

Answer 8

In Coordination With Other Muscles

Question 9

There is often one muscle which is largely responsible for a desired action, and it is referred to as this.

Answer 9

Prime Mover (Agonist)

Question 10

Has the opposite effect of the prime mover.

Answer 10

Antagonist

Question 11

In addition to creating movement, muscles also enable to body to:

Answer 11

Maintain Its Posture

Question 12

Partial muscular contraction that does not create movement, but simply allows for a relatively constant amount of tension in a muscle so that it can hold a body part in its proper position.

Answer 12

Tonic Contraction

Question 13

Besides creating movement and maintaing posture, muscles are also responsible for:

Answer 13

Heat Production in The Body

Question 14

1. Skeletal
2. Smooth
3. Cardiac

Answer 14

Three Basic Categories of Muscle Tissue

Question 15

Makes up the greatest share of the muscular tissue in the human body.

• Attaches to the bones of the skeleton and creates movement by pulling these bones.

Answer 15

Skeletal Muscle (Voluntary, Striated)

Question 16

Skeletal muscle is also known as this because it can be made to contract by conscious control.

Answer 16

Voluntary

Question 17

Skeletal muscle is also called this because under a microscope, this type of muscle is seen to contain dark colored stripes.

Answer 17

Striated

Question 18

Found in various organs and functions “automatically.”

• Microscopically, does not have stripes (striations)
• Found in most of the viscera - such as the stomach and intestines.

Answer 18

Smooth Muscle (Involuntary, Visceral, Non-Striated)

Question 19

The kind of muscle found in the heart.

• Has some of the characteristics found in the other two kinds of muscles.
  
  • Is striated and involuntary
• Forms branches, is functionally arranged differently so that it can keep the heart beating in a rythmic fashion.

Answer 19

Cardiac Muscle

Question 20

Small, dense cords of connective tissue that are responsible for attaching muscle to bone (or muscles to muscles in some cases).

• Often cross over an articulation in order to pull on the bones forming the joint, thus bringing them toward each other.

Answer 20

Tendons

Question 21

Have three main parts:

• Origin
• Insertion
• Body

Answer 21

Voluntary (Skeletal) Muscle

Question 22

The end of the muscle which is attached to the less moveable, or “fixed” bone.

Answer 22

Origin

Question 23

The end of the muscle which is attached to the more movable bone.

Answer 23

Insertion

Question 24

The fleshy portion of the muscle.

Answer 24

Body (Belly)

Question 25

The origin of the muscle is normally the ____ end.

Answer 25

Proximal

Question 26

The insertion of a muscle is usually the ______ end.

Answer 26

Distal

Question 27

Long, cylindrical cells that are made up of tiny, thread-like structures, which in turn consist of ven finer filaments made up on specialized proteins.

Answer 27

Muscle Fibers

Question 28

The tiny, thread-like stuctures within a muscle fiber.

Answer 28

Myofibrils

Question 29

• Tonic
• Twitch
• Tetanic
• Isotonic
• Isometric

Answer 29

Forms of Muscle Contraction

Question 30

Rapid, jerky contractions in response to a stimulus, which play no major role in normal bodily activities.

Answer 30

Twitch Contractions

Question 31

More sustained contractions, where muscle fibers are unable to relax between stimuli occurring at a more rapid rate.

Answer 31

Tetanic Muscle Contractions

Question 32

Resulting from tetanic contractions, the state of contraction. May vary in intensity and is not necessarily an efficient, maximized contraction of all the fibers in a particular muscle.

Answer 32

Tetanus

Question 33

Those contractions in which we normally think of when muscles undergo their normal movement, where a more constant, equal contraction is involved.

• The muscle shortens and pulls on another body part, such as bone, in order to create movement.

Answer 33

Isotonic Contraction

Question 34

Involve a constant tension put upon a muscle, but little or no movement occurs. Although tension increases within the muscle, the muscle does not shorten and result in movement of a body part.

Answer 34

Isometric Contraction

Question 35

Usually reflect something important about the muscle, such as:

• Location
• Action
• Shape
• Direction of the muscle fibers
• Size
• Number of divisions
• Points of attachment
• Superficial or deep

Answer 35

Names of Skeletal Muscles

Question 36

Moving a body part, such as a limb, away from the median plane of the body.

• Example: moving your arm out to the side

Answer 36

Abduction

Question 37

Moving a body part toward the median plane.

• Example: Moving your arm from away from the body back down to your side.

Answer 37

Adduction

Question 38

Bending a body part, or decreasing the angle between two bones.

Answer 38

Flexion

Question 39

Straightening out a body part, or increasing the angle betwen bones.

Answer 39

Extension

Question 40

Movement of the palm of the hand from a forward or upward facing position to a backward or downward facing position.

• The distal end of the radius crosses over the ulna

Answer 40

Pronation

Question 41

Movement of the palm of the hand from a backward or downward facing position to a forward or upward position.

• The radius and ulna are parallel

Answer 41

Supination

Question 42

Lifting up of a body part.

Answer 42

Elevation

Question 43

Downward movement, or lowering, of a body part.

Answer 43

Depression

Question 44

Movement of a bone around its longitudinal axis.

Answer 44

Rotation

Question 45

Turning, or swinging, a body part, such as a limb, in a circular fashion. This movement is actually a combination of other actions.

Answer 45

Circumduction

Question 46

The squeezing closed of a body orifice.

Answer 46

Constriction

Question 47

Refers to a widening or opening of an orifice.

Answer 47

Dilation

Question 48

Refers to a forward movement of a body part.

Answer 48

Protraction

Question 49

Refers to a backward movement of a part.

Answer 49

Retraction

Question 50

Used to describe an outward turning of the sole of the foot.

Answer 50

Eversion

Question 51

Means an inward turning of the sole of the foot.

Answer 51

Inversion