General Biomechanical Principles Flashcards
What is each skeletal muscle composed of?
fascicles
Define a fascicle.
a bundle of muscle fibers
What do muscle fibers contain?
myofibrils
What are myofibrils composed of?
myofilaments
List the breakdown of a muscle.
Muscle belly to epimysium to fascicles and perimysium to endomysium and myofiber to myofibril to sarcomere to actin and myosin
What does tendons attach?
muscle to bone, skin, or another muscle
Describe tendons.
usually have a thick cord-like structure
What is an aponeurosis?
thin flattened sheet of tendons
Give an example of a tendon.
Achilles tendon
Where would one find an aponeurosis?
Abdominal muscles
What do ligaments attach?
Bone to bone
Most skeletal muscles extend ________ and cross ______.
between bones, at least one movable joint
Upon contraction, one of the bones _____ while the other bone usually remains _____.
moves, fixed
Define origin.
less movable attachment of a muscle
Define insertion.
more movable attachment of muscle
Where does the origin usually lie?
proximal to the insertion
True or false the insertion is pulled toward the origin.
True
List the 4 organizational patterns in fascicles of muscle fibers.
Cicular, convergent, parallel, pennate
Describe a circular organizational pattern.
muscle is also called a sphincter because contraction of the muscle closes off the opening
Describe a convergent organizational pattern.
muscle has widespread muscle fibers that converge on a common attachment site and are often triangular in shape.
Describe a parallel organizational pattern.
fascicles run parallel to its long axis; have a central body called the belly or gaster
Describe a pennate organizational pattern.
have one or more tendons extending through their body and the fascicles are arranged at an oblique angle to the tendon
Give an example of a convergent muscle.
pectoralis major
Give an example of a circular muscle.
orbicularis oris
Give examples of parallel muscles.
stemocleidomastoid, biceps brachii
Give examples of pennate muscles.
deltoid (multi), flexor pollicis longus (uni), rectus femoris (bi)
Define effort.
load arm; work required (muscles do the work)
Define load.
resistance arm; what is being resisted or being moved (the body part)
Define fulcrum.
point of movement (the joint)
Define resistance arm.
distance between axis and point of resistance application
Define force arm.
distance between axis and point of force
List the 3 classes of levers in the body.
first, second, and third
Define a first class lever system and give and example.
has a fulcrum in the middle, between the force and the resistance
example: the head
Define a second class lever system and give and example.
resistance is between the fulcrum and the applied force
example: raising the body up, balancing on the balls of the feet
Define a third class lever system and give and example.
force is applied between the resistance and the fulcrum
example: doing dumbbell curls - biceps
What is the most common lever system in the body?
third class
How does bears’ biceps differ than humans? What does this produce?
In bears the bicep tendon inserts further down (distally) on the forearm, resulting in very strong, but relatively slower flexion.
What are the three primary types of actions of skeletal muscles?
agonists, antagonists, synergists
What is the action of an agonist?
contracts muscle to produce a particular movement
What is the action of an antagonist?
opposes those actions of the agonist
What is the action of a synergist?
- assist the prime mover in performing its action
- the contraction contrbutes to tension exerted close to the insertion of the muscle or stabilizes the point of origin
- may also assist an agonist by preventing movement at a joint and thereby stabilizing the origin of the agonist
- called fixators
