Functional Anatomy Flashcards
Insertion
Is attached to the bone which moves more when the muscle contracts.
The insertion of a muscle is the point which is usually at the distal end
Motor neuron
Refers to neurons located in the central nervous system that project their axon outside the CNS and directly or indirectly control muscles
- responsible for carrying impulses away from the spinal cord and brain to the muscle or glands.
Motor unit
Refers to the single motor neuron and all the corresponding muscle fibres it innervates.
All or nothing principal
Determined whether the signal from the brain is above or below the threshold required for contraction. Muscle fibres in a motor unit will contract with 100% force or none at all. To increase the strength of contraction the brain simply sends more signals resulting in the recruitment of more motor units
Characteristics of type 2 A fast twitch muscle fibres
Fast contraction speed used for speed endurance activities Moderate force of contraction Fatigue resistance Large motor neuron Moderate oxidative density High glycoltic capacity Fuel source: CP and glycogen Intermediate capillary density
Characteristics of type 2 B fast twitch
Very fast contraction Very large motor neuron Low resistance to fatigue Very high force production Low capillary density Low oxidative destiny High glycoltic capacity Fuel source cp and glycogen
Characteristics of slow twitch
Slow contraction speed Small motor neuron High resistance to fatigue Low force production High capillary density High oxidative density Fuel source: trigylcerides and glycogen
Force velocity
Muscle can create an increase amount of force with decreased velocity with concentric action
Muscle can create a increase amount of force with increased force and a increased amount of velocity with eccentric contraction
Isotonic forces
Isotonic forces- is one which results in a change in the length of a muscle performed against a constant lead
Eccentric contraction
Concentric contraction
Concentric muscle contraction
Results in the shortening of the muscles length. It occurs when you apply a force against the direction of gravity
Eccentric muscle contraction
A muscle contraction that results in an increased length of the muscle. A muscle lengthens when resisting the force of gravity
Isokinetic force
Is one which results in a change in the length of a muscle, however is performed against a varying load. This requires expensive specialised equipment to ensure the speed of muscular contraction remains constant
Isometric contractions
If the muscle length does not change then a isometric contraction is being applied
Force length
The length of a muscle affects how well it creates tension
Max tension created in the muscle fibre occurs at slightly greater than resting length
Force time
Also referred to as electromechanical delay (EMD)
It’s is not possible for muscle to produce maximal forces instantaneously and there is a time lapse before maximum force can be produced
White fibres have lower EMD than red and can produce peak force faster than red fibres