MORS 113: Muscle Facts (Little Blue Book) Flashcards
Refers to the study of the muscular system.
Myology
- Make up about 45% of body weight.
- Responsible for imparting movement to body parts.
- Do this through the ability to contract (shorten in length).
Muscles
The ability to contract and cause movement.
Contractility
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.
Muscle Cells
May only be 1/2 to 1/3 it’s normal length when at rest.
A Fully Contracted Muscle
Specialized nerve cells (neurons) that transmit stimuli to muscle cells.
- Muscles do not contract on their own, they need these.
Motor Neurons
The combination of a motor neuron and the group of muscle cells which it stimulates.
Motor Unit
Generally, muscles do not act individually to create movement of a body part, but function:
In Coordination With Other Muscles
There is often one muscle which is largely responsible for a desired action, and it is referred to as this.
Prime Mover (Agonist)
Has the opposite effect of the prime mover.
Antagonist
In addition to creating movement, muscles also enable to body to:
Maintain Its Posture
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.
Tonic Contraction
Besides creating movement and maintaing posture, muscles are also responsible for:
Heat Production in The Body
- Skeletal
- Smooth
- Cardiac
Three Basic Categories of Muscle Tissue
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.
Skeletal Muscle (Voluntary, Striated)
Skeletal muscle is also known as this because it can be made to contract by conscious control.
Voluntary
Skeletal muscle is also called this because under a microscope, this type of muscle is seen to contain dark colored stripes.
Striated
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.
Smooth Muscle (Involuntary, Visceral, Non-Striated)
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.
Cardiac Muscle
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.
Tendons
Have three main parts:
- Origin
- Insertion
- Body
Voluntary (Skeletal) Muscle
The end of the muscle which is attached to the less moveable, or “fixed” bone.
Origin
The end of the muscle which is attached to the more movable bone.
Insertion
The fleshy portion of the muscle.
Body (Belly)
The origin of the muscle is normally the ____ end.
Proximal
The insertion of a muscle is usually the ______ end.
Distal
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.
Muscle Fibers
The tiny, thread-like stuctures within a muscle fiber.
Myofibrils
- Tonic
- Twitch
- Tetanic
- Isotonic
- Isometric
Forms of Muscle Contraction
Rapid, jerky contractions in response to a stimulus, which play no major role in normal bodily activities.
Twitch Contractions
More sustained contractions, where muscle fibers are unable to relax between stimuli occurring at a more rapid rate.
Tetanic Muscle Contractions
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.
Tetanus
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.
Isotonic Contraction
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.
Isometric Contraction
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
Names of Skeletal Muscles
Moving a body part, such as a limb, away from the median plane of the body.
- Example: moving your arm out to the side
Abduction
Moving a body part toward the median plane.
- Example: Moving your arm from away from the body back down to your side.
Adduction
Bending a body part, or decreasing the angle between two bones.
Flexion
Straightening out a body part, or increasing the angle betwen bones.
Extension
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
Pronation
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
Supination
Lifting up of a body part.
Elevation
Downward movement, or lowering, of a body part.
Depression
Movement of a bone around its longitudinal axis.
Rotation
Turning, or swinging, a body part, such as a limb, in a circular fashion. This movement is actually a combination of other actions.
Circumduction
The squeezing closed of a body orifice.
Constriction
Refers to a widening or opening of an orifice.
Dilation
Refers to a forward movement of a body part.
Protraction
Refers to a backward movement of a part.
Retraction
Used to describe an outward turning of the sole of the foot.
Eversion
Means an inward turning of the sole of the foot.
Inversion
