Biomechanics, Ch. 2
Biomechanics, Ch. 2 HSS 387, biomechanics
U of L
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This 8 page Class Notes was uploaded by Caroline Pirtle on Monday April 18, 2016. The Class Notes belongs to HSS 387, biomechanics at University of Louisville taught by Werner in Spring 2016. Since its upload, it has received 12 views. For similar materials see Exercise Physiology in Exercise Biology at University of Louisville.
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Date Created: 04/18/16
Chapter 2 - Neuromuscular fundamentals Wednesday, September 2, 2015 7:58 AM I. Skeletal muscles a. Responsible for movement of body and all of its joints b. Muscle contraction produces force that causes joint movement c. Muscles also provide i. Protection ii. Posture and support iii. Produce a major portion of total body heat b Aggregate muscle action - muscles work together in groups/pairs II Muscle nomenclature a Muscles are usually named due to i. Visual appearance (what do they look like) ii. Anatomical location (where) iii. Function (what it does) b Skeletal muscle naming II Shape and fiber arrangement a Effects of muscle shape and fiber arrangement no slide 5,6,7 i. Muscles ability to exert force onto the bones to which they are attached ii. Range through which it can effectively exert force onto the bones b Cross section diameter i. Factor in muscle's ability to exert force ii. Greater cross section diameter = greater force exertion b Muscle's ability to shorten i. Larger muscles can shorten through a greater range b Parallel and pennate i. Parallel 1. Fibers arranges parallel to length of muscle ii Pennate 1. Run oblique, at an angle; when they shorten will typically pull at whatever tendon it is inserted. The more pennate it is means it has more muscles 2. Uni, bi, multi- b Shape i Flat ii Fusiform iii Strap - sartorius iv Radiate v Sphincter or circular II Muscle tissue properties a Ability to produce force and movement about joints: i Irritability or excitability - responsiveness to chemical, electrical, or mechanical stimuli; responds by creating tension ii Contractility - ability of the muscle to contract and develop tension when stimulated iii Extensibility - ability to be passively stretched beyond its normal resting length iv Elasticity - ability to return to its normal resting length after being stretch 1. Static stretching II Muscle terminology a Intrinsic muscle - pertaining usually to muscles within or belonging solely to body part upon which they act b Extrinsic - outside the muscle it moves c Action - specific movement of a joint resulting from the concentric contraction of a muscle which that crosses joint d Innervation - segment of nervous system defined as being responsible for providing a stimulus to muscle fibers within a specific muscle e Tendon - muscle to bone f Aponeurosis - there's a sheath around some muscles that keep them in place; there's not a bone between each muscle so it has to be stabilized in some way; rectus abdominus g Fascia - the most superficial portion of a muscle; connective tissue around muscle i Retinaculum - space that’s been carved out so tendons can run through it b Origin - proximal attachment; the least moveable part of a muscle i Like an anchor b Insertion - distal attachment; most moveable part II Passive joint movement a Movement may occur at any given joint without any muscle contraction whatsoever = passive joint movement i Solely due to external forces such as those by another person, object, gravity II Muscle contraction a Stabilization of bone b Contraction - when a muscle turns on because you told it to i All contractions are either 1. Isometric - contracting and same length; without motion a. A plank b. posture 2 Isotonic - contracting and changing length; with motion a. Concentric - muscle shortening occurs; causing joint motion b. Eccentric - muscle lengthening occurs; control joint motion; whatever you are holding in your hand is usually winning in this contraction; gravity wins although you're not going down without a fight 2 Isokinetics - a type of dynamic exercise using concentric and/or eccentric muscle contractions a. Speed b. Muscle contraction II Roles of muscles a Agonist i Cause joint motion through a specified plane of motion when contracting concentrically ii A muscle that causes an action at a joint b Antagonist i Opposite joint motion of agonist ii Cannot have both contracting at the same time = isometric contraction b Stabilizers = neutralizer i Not a prime mover but keeps fixated area stable while distal portion moves ii Firm base b Synergist i Assist in the action of agonists but are not necessarily prime movers for the action..guiding muscles ii Helping synergist iii True synergist b Force couples i More than one muscle pulling in a different direction causing the same movement 1 Steering wheel is a good example 2 Scapula - rotation II Tying roles of muscles together slide 36 a Kicking a ball i Agonists = hip flexion and knee flexion ii Antagonist = hamstrings relax to allow the kick to occur iii Preciseness of the kick depends on the involvement of many other muscles II Determination of muscle action III Lines of pull - a description of the direction of force exerted by a muscle IV Neural control of voluntary movement--know red information a Cerebral cortex i Highest level of control ii Interprets sensory stimuli iii Conveys to lower structures to fine tune actions iv Where actions are determined and then do it v Contraction always originates here b Basal ganglia i Balance ii A lot to do with stabilizers b Cerebellum i All of the fine tuning ii Feedback relative to motion b Brain stem i Executes what the cerebellum tells it ii Excitation and inhibition b Spinal cord i Common pathway between CNS and PNS ii Last stop II Division of PNS no 46-53 a Sensory = afferent i Arrive CNS b Motor = efferent i Exit CNS ii Voluntary (somatic) iii Involuntary (visceral) II 3 types of neurons a Motor b Sensory c Interneurons II Proprioception and kinesthesis a Proprioception i Knowing where your body is in space unconsciously ii Proprioceptors - what allows you to be aware iii Types: 1 Muscle spindles -- know definition a. Sensitive to stretch and rate of stretch 2 Golgi tendon organ a. Respond to tension - make sure you don't tear a muscle under load b. Job is to make you fail; know when your tendon is about to rip from bone c. In a tendon d. You can increase the set point or sensitivity b Kinesthesis i Conscious awareness of where your body is in space II Muscle length a A shorter length of a muscle can't produce as much force b Greatest amount of tension can be developed when a muscle is stretched between 100-130% I Active and Passive insufficiency a Example of squatting on the desk a Active insufficiency - muscle becomes shortened b Passive insufficiency - opposing muscle becomes stretched II Force - velocity relationship a Concentric - the contraction force is greater than the resistance load b Isometric - contraction force usually isn't larger than force because there is no motion c Eccentric - the resistance is greater than the contraction force II Reciprocal inhibition a The idea that when my quad fires my hamstring instantaneously turns off b When agonist is on antagonist is off normal stretched shortened ☹ Mills train* * 1111 e*
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