Lecture 5- Overview Of Musculoskeletal System Flashcards
Principal functions of MS system
Support the body and provide a means of locomotion
Elongation of limbs
Adaptation for longer strides and therefore improve speed
Disproportional, proximal distribution of muscle mass
Adaptation to increase frequency of oscillation
Disproportional growth of distal bones
Results in longer limbs and improves stride distance and therefore speed
Results in change in stance- from plantigrade to digitigrade to unguligrade
Loss of digits
Loss of manipulative skills
Flexibility of spine
Increasing flexibility of spine inreases stride length
Origin of muscle
Most proximal attachment; usually no tendon; least movable
Insertion
Most distal part; most movable
Muscle shapes
Parallel, fan-shaped, fusiform, pennate (parallel fibers attached to tendon at an angle)
Range of contraction
Depends on pennation of muscles
Unipennate> bipennate> multipennate
Force produced:
Multipennate> bipennate> unipennate
Hypertrophy
Occurs by increasing the diameter of a muscle fiber through synthesis of new myofibrils; increases force-generating capacity
Hyperplasia
Occurs by formation of more muscle cells; increases force generating capacity
Define agonist, antagonist, isometric, isotonic, concentric, eccentric
Agonist muscles- muscles that work together to perform same action
Antagonist- muscles that produce opposite movements
Isometric contraction- force generated at a constant length
Isotonic contraction- when internal force exceeds external force and muscle contracts
Concentric contraction- isotonic contraction in shortening direction
Eccentric contraction- lengthening of a contracting muscle; generates more force than concentric
Moment arm
Perpendicular line from an axis to the line of application of force
Torque
Force x moment arm
Shorter moment arm
Low torque, high range of motion
