BME 235 Quiz 8.3 with 100%
correct answers already graded
A+
Lever
any elongated, rigid object that rotates around a fixed fulcrum or 'pivot
point'
resistance arm
distance from fulcrum to point of applied resistance
effort arm
distance from fulcrum to point of applied effort
-rotation occurs when an effort applied overcomes resistance
first class lever system
- fulcrum (F) is between effort (E) and resistance (R)
ex: tilting head back, scissors
second class lever system
the resistance is between the fulcrum and the effort
ex: lifting the heel of the ground, wheel barrow
third class lever system
Effort applied between resistance and fulcrum
ex: bending elbow, tweezers
mechanical advantage (MA)
the ratio of the output force to the input force, calculated by the length of
effort arm divided by the length of resistance arm
MA < 1
, - lever produces more speed or distance, but less force than input
- biceps muscle during elbow flexion
MA > 1
- lever produces more force, but less speed and distance than force
exerted on it
-digastric muscle during jaw opening
shoulder joint
glenohumeral (humeroscapular) joint
- hemispherical head of humerus articulates with glenoid cavity of scapula
- most freely mobile joint in the body
- shallow glenoid cavity and loose shoulder joint capsule sacrifice stability
for freedom of movement
glenoid labrum
fibrocartilage ring that deepens glenoid cavity
shoulder joint is supported and acted on by several muscles
- deltoid, biceps brachii, pectoralis major anteriorly and laterally
-latissimus dorsi, teres major posteriorly
rotator cuff
- supraspinatus, infraspinatus, teres minor, and subscapularis
- tendons fuse to joint capsule and strengthen it superiorly and posteriorly
shoulder dislocation
painful, sometimes causes permanent damage
- downward dislocation is most common
--> especially kids
rotator cuff tear
correct answers already graded
A+
Lever
any elongated, rigid object that rotates around a fixed fulcrum or 'pivot
point'
resistance arm
distance from fulcrum to point of applied resistance
effort arm
distance from fulcrum to point of applied effort
-rotation occurs when an effort applied overcomes resistance
first class lever system
- fulcrum (F) is between effort (E) and resistance (R)
ex: tilting head back, scissors
second class lever system
the resistance is between the fulcrum and the effort
ex: lifting the heel of the ground, wheel barrow
third class lever system
Effort applied between resistance and fulcrum
ex: bending elbow, tweezers
mechanical advantage (MA)
the ratio of the output force to the input force, calculated by the length of
effort arm divided by the length of resistance arm
MA < 1
, - lever produces more speed or distance, but less force than input
- biceps muscle during elbow flexion
MA > 1
- lever produces more force, but less speed and distance than force
exerted on it
-digastric muscle during jaw opening
shoulder joint
glenohumeral (humeroscapular) joint
- hemispherical head of humerus articulates with glenoid cavity of scapula
- most freely mobile joint in the body
- shallow glenoid cavity and loose shoulder joint capsule sacrifice stability
for freedom of movement
glenoid labrum
fibrocartilage ring that deepens glenoid cavity
shoulder joint is supported and acted on by several muscles
- deltoid, biceps brachii, pectoralis major anteriorly and laterally
-latissimus dorsi, teres major posteriorly
rotator cuff
- supraspinatus, infraspinatus, teres minor, and subscapularis
- tendons fuse to joint capsule and strengthen it superiorly and posteriorly
shoulder dislocation
painful, sometimes causes permanent damage
- downward dislocation is most common
--> especially kids
rotator cuff tear
