Chapter 11: The Muscular System
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
origin of a muscle
• One bone remains stationary or near its original position - the attachment of a tendon to the stationary bone
insertion of a muscle
• on the bone that moves - The attachment of the muscle’s other tendon to the movable bone
RMA
reverse muscle action =relatively stationary bone (origin) and movable bone (insertion) switch roles
a bone often functions as a ___ and its joint with another bone acts like a ____
• lever - fulcrum
when will the load be moves
when effort (E) is greater than load (L)
what is it based on for lever systems to show mechanical advantage or disadvantage?
It is based on the relative distances of the load and effort from the fulcrum
mechanical advantage
occurs when load is close to fulcrum and effort if farther away from fulcrum (first class lever) = allows large load to be moved a short distance with LITTLE effort
mechanical disadvantage
effort applied close to fulcrum and load located farther away from fulcrum (third class lever) = expend more effort to move small load but will be faster
what are the 5 possible fascicle arrangement?
1) parallel muscles 2) fusiform muscles 3) circular muscles 4) triangular muscles 5) pennate muscles
fascicles parallel to long axis of muscle; both ends terminate in flat tendons
parallel muscles
fascicles roughly parallel to long axis of muscle; muscle belly tapers at both ends, terminating in flat tendons
fusiform muscles
fascicles show a concentric circular pattern; seen in muscular sphincters
circular muscles
from thick central tendon, fascicles fan-out
triangular muscles
long tendons run most of muscle length; short fascicles emanate from tendon (feather-shaped)
pennate muscles
muscle power
the more muscle fiber per cm squared, the more forceful its contraction
muscle’s range of motion
the longer the fiber length, the greater the range of motion
how are pennate muscles compared to parallel muscles?
pennate muscles are more powerful than parallel muscles but pennate muscle has a smaller range of motion
“prime mover” = agonist
when the body part is moved by a group of muscles, usually one is the agonist (does most of the work)
other muscles of working group
synergists
when prime mover crosses intermediate joints before reaching joint of its primary action, what do the synergists do?
contraction of synergists stabilize intermediate joints
what is the prime mover/agonist often opposed by?
opposed by an antagonist located in the opposite compartment
what happens to antagonist, when agonist shortens?
Antagonist lengthens
biceps branchii contracts and triceps branchii lengthens
• flexion of forearm - vice versa for extension of forearm
biceps branchii and triceps branchii
antagonist pair which has equal force resulting isometric contraction