Chapter 5 (Muscular System) Flashcards
What are muscle names based off of?
- Location
- Shape
- Action
- # of heads or divisions
- Attachments= origin/insertion
- Direction of fibers
- Size
When a muscle contracts it knows no direction: it simply ____?
shortens
What is the more movable bone?
Insertion (most distal) which moves toward the origin
What is the more stable bone?
Origin (most proximal)
What is the reversal of a muscle action ?
When the origin moves towards the insertion
Long and thin, fibers run the entire length of the muscle
Strap muscle (parallel)
Spindle shape- wide mouth tapered ends (muscle)
Fusiform muscle (parallel)
Four sided, flat (muscle)
Rhomboidal muscle (parallel)
Flat, fan shaped, fibers radiating from a narrow attachment
Triangular muscle (parallel)
looks like one side of a feather (muscle)
Unipennate (oblique)
pattern common feather (muscle)
Bipennate (oblique)
Many tendons (muscle)
Multipennate (oblique)
What is normal resting length?
- when the length is unstimulated
2. When there are no forces or stresses on it
What are the four functional characteristics of muscle ?
- Irritability
- Contractility
- Extensibility
- Elasticity
Ability to respond to a stimulus
- Contracts when stimulated, motor nerve or electric current
Irritability
Ability to shorten or contract
- Produces tension between ends
- The muscle shortens, stays the same, or lengthens
Contractile
Ability of a muscle to stretch or lengthen when force is applied
Extensibility
Ability to recoil or return to normal resting length when stretching or shortening force is removed
Elasticity
What is tension?
Force built up within the muscle
What does it mean to shorten?
muscle shortens 1/2 its normal resting length
What is excursion?
Distance from max elongation to max shortening
(From the shortened to lengthened; 3”-9” = excursion)
Shortened = 3”
Normal = 6”
Stretched = 9”
When a muscle reaches a point where it cannot shorten any farther
- Occurs to the agonist
Active insufficiency
When a muscle cannot be elongated any farther without damage to the fibers
- Occurs to the antagonist, opposite the agonist
Passive insufficiency
Example of Active insufficiency…
Hamstrings which are a two joint muscle (extend the hip and flexes the knee). Can preform either motion but not simultaneously. If you flex the knee while hip is extended it cannot complete full range because muscle is at maximum contraction.
Example of Passive insufficiency…
hamstrings -muscle can be stretched of two joints but not simultaneously. sitting with knee extended then try to flex hip. hamstring is to tight it has already been stretched to maximum capacity.
Agonist usually becomes actively insufficient (cannot contract any farther) before the antagonist becomes passively insufficient (cannot be stretched farther)
Stretching
What are the 3 types of muscle contractions?
- Isometric
- Isotonic
- Isokinetic
When a muscle contracts, producing force without changing the length of the muscle
(joint angle does not change)
isometric
Ex. plank position
Muscle contracts, changing the muscle length and the joint angle. Can be concentric or eccentric
Isotonic
Muscles shorten and the muscle attachments move towards each other. Usually occurs against gravity direction (raising motion)
Concentric
Ex. - biceps muscle bringing up the barbell.
Describe eccentric
Muscles lengthen and the muscle attachments move away from each other
Usually occurs with gravity (lowering motion)
Ex. biceps muscles as a barbell is lowered.
What are roles of muscle ?
- agonist
- Antagonist
- Cocontraction
- Stabilizer
Muscle or muscle groups that cause the motion
Agonist
Ex. During elbow flexion bicep is the agonist and pronator teres is the assisting mover
Muscle that performs opposite motion of agonist
Antagonist
Ex. During elbow flexion bicep is agonist and tricep is the antagonist.
When agonist and antagonist contract at same time. Occurs when there is a need for accuracy.
Cocontraction
Group which stabilizes the part to allow the agonist to perform more effectively; sometimes referred to as a fixator
Stabilizer
Ex. When doing a push up abdominal muscle are the stabilizes
Muscles only have one direction of pull. It is usually a diagonal line of pull.
Angle of pull
What are 3 types of angle of pull?
- Vertical
- Horizontal
- Diagonal
Elevating or depressing the scapula is an example of what angle of pull?
Vertical pull
Retract or protract the scapula is an example of what angle of pull?
Horizontal pull
What type of pull causes motion in both planes?
Diagonal pull
Position in which the muscle shortens without having to work against the effects of gravity.
Done in horizontal plane.
Gravity-eliminated exercise
Describe a closed-kinetic chain
Distal segment is fixed (closed) and the proximal segment moves.
Ex. Rising from a chair; (your knees extend causing your hip and ankles to move as well)
Describe an open-kinetic chain
Distal segment is free to move and the proximal end remains stationary.
Ex. being seated and extending knee; (your knee, hip, and ankle would not move)
