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69 Cards in this Set
- Front
- Back
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what is an agonist muscle
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a muscle that is known to the principle mover of the lever
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what is an antagonist muscle
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a muscle that in contracting tends to produce movement opposite to that of an agonist
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where are prorioceptors located
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muscle, tendons, and joints
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what is an isometric contraction
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muscle contraction without muscle changing length
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what is an isotonic contraction
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muscle contraction that changes length while tension is held near constant
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what are the two type of muscle contraction
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concentric
eccentric |
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what is an concentric contraction
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when muscle develops sufficent tension to overcome resistance and shortens
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what is an eccentric contraction
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resistance is not overcome bu the muscle lengthens during the action
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why are muscles red
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due to an increased amount of myoglobin
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what are red muscles good at and what is an example of an red muscle
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efficient at performing long, sustained, slow pulls or contractions
postural muscles |
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what are white muscles good at and what is an example of white muscle
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good a performing fast contractions
gastroc |
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what are spurt muscles
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muscles with a large moving component (large insertion)
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what is the angle of muscle pull with spurt muscles
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greater than 45 degrees
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what are shunt muscles
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muscles having a larger stabilizing component than moving component (large origin)
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what is the angle of pull with shunt muscles
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less than 45 degrees
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what is the function of muscle at joints
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create stability by resisting rotational movements and maintaining compression
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besides stability what other functions do muscles play
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accelerators
resist motion(decelerator) |
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what is the accelerator function of the long extensors
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assist as ankle accelerators in ankle joint dorsiflexion at toe off
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what is the decelerator function of the long extensors
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decelerators of the foot at heel strike
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what are the effects of muscle resisting rotational forces
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causes compression at the joint and decreased tension and shearing forces on the bones of that joint
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at what points does the tension capacity of muscle slowly decrease
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when it is stretched to 120% or shortened to 50% of normal physiologic length
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what is normal physiologic length of muscle
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about 50% of actual length
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what happens to the lever arm in single joint muscles
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stays the same throughout
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what is the effects of the muscle on single muscle lever arms
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contraction of the muscle alters the proximity of the origin and insertion
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what are the effects of the muscle contraction in multiple joint muscles
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muscle length is maintained near resting length but lever arms change
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which lever arm has greates mechanincal efficiency
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class three lever becaus more movement is obtained with less muscle shortening
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what happens with a long resistance arm and short effort arm
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magnify speed
can move body parts rapidly if resistance is not great |
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what is important with the angle of application and efficiency
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the higher the angle of application the more efficient
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which is more efficient single joint or multiple joint muscles and why
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multiple joint muscles because each joint they pass over acts as a pully
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what powers movement in swing phase
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muscle contraction
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what is active contraction of muscles
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when muscle is contracting not in response to ground reactive forces
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what does the active contraction of musculature of the swing limb do during gait
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propels the body anteriorly propogating the controlled fall forward
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what is the fulcrum in stance phase
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MPJ
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what is the elastic response of muscles and ligaments
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the proprioceptors in muscles and ligaments are activated by stretch and when stretched they fire the muscles to return structure to normal
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what is an example of elastic response with the gastroc
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at the end of midstance the gastroc muscle is stretched eliciting elastic response of gastroc causing it to contract and lift heel
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when do we see elastic response in relationship to the tibio-fibular syndesmosis
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as the leg rotates the tibia moves in relationship to fibula and causes elastic response
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what happens if external rotation stimulates elastic response
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muscles that cause internal rotation are activated
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what happens if internal rotation stimulates elastic response
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muscles that cause external rotation are activated
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what is the elastic response of the spring ligament
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when the spring ligament is stretched during pronation or decrease of medial arch then muscles that supinate the foot are activated
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what is the elastic response in relationship to upper and lower trunk
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when elastic response is stimulated it rotates two portions in opposite directions
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when does anterior tibialis begin to contract in propulsion
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just before toe off with peak activity just after toe off
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what is the function of the tibialis anterior in propulsion
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functions to assit in dorsiflexion of the foot to help the toes clear the ground
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when does the tibialis anterior have its peak activity
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during contact period
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what are the functions of the anterior tibialis in contact period
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decelerates ankle joint plantarflexion
supinates the forefoot around the LMTJ to compensate for calcaneal eversion as it relaxes it promotes lateral to medial loading |
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as the tibialis anterior slows ankle joint plantarflexion it also reduces this
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posterior shear
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when is the anterior tibialis peak activity in swing phase
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just after toe off
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what are the functions of the tibialis anterior in swing phase
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accelerates the foot at the ankle joint
supinates forefoot at LMTJ and dorsiflexes first ray to help in clearing the ground in midswing weak supinator of entire foot to prevent excessive pronation during swing |
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what will we see in contact if anterior tibialis is not functioning
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foot slap
extensor substitution |
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what will we see in swing if anterior tibialis is weak or not functioning
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foot drag
pronated STJ during swing |
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what effects does the anterior tibialis have on the following joints ankle, STJ, first ray, LMTJ, OMTJ
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ankle=good lever arm
STJ=short lever arm First ray=long lever arm LMTJ=short lever arm OMTJ=little effect here |
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how does anterior tibialis have effects on the LMTJ even though it has a short lever arm at this joint axis
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by dorsiflexing the first ray it raises other rays and supinates the LMTJ
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when is the anterior tibialis active in gait
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last part of propulsion through midswing then the end of swing through the first half of contact
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what is the function of the EHL in contact period
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deceleration of the foot at heel strike
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what muscle is the EHL dependent on in contact period
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anterior tibialis
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how do the EHL and Anterior Tibialis work together in contact period
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because the anterior tibialis is dorsiflexing the first ray the EHL can only dorsiflex 20-25 degrees this allows the EHL to adi in deceleration at ankle joint
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what is the function of the EHL in propulsive period
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turns hallus into rigid beam for propulsion
stabilizes at first MPJ along EHB stabilizes IPJ compresses phalanges of hallux posteriorly |
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when do we see peak function of the EHL
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at the beginning and end of swing phase
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what is the function of the EHL in swing phase
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most important for rapid ankle joint dorsiflexion at ankle joint for foot clearance
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why is the EHL a neutral dorsiflexor
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because it has little to no effect on the STJ while doing its function
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what does the EHL need for extended dorsiflexion
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anterior tibialis
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what pathology will we see with EHL failure
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partial foot drop at contact
difficulty in foot clearance during midswing |
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what are the lever arms of the EHL in relation to the Ankle, STJ, 1st MPJ
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ankle=long lever arm
STJ=runs almost parallel no lever arm here 1st MPJ=long lever arm to transverse axis |
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when is the EHL active in gait
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last part of propulsion thru mid swing than again in late swing thru early contact
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what are the functions of the EDL in propulsion
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creates rigid beam of digits
assists the lumbricales in developing extensor rigidity at IPJ assists in stabilizing the phalanges of the lesser digits posteriorly against each other and the corresponding met heads |
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what are the functions of the EDL in swing phase
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assists in dorsiflexing of the foot for toe clearance
prevents excessive supination of the foot during the swing phase by exerting a pronatory force pronates STJ as well as the midtarsal joint axis |
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what are the pathologies we will see if the EDL is inactive or weak
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excessively supinated STJ and MTJ during swing phase
foot drop during midswing due to loss of dorsiflexion |
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what are the lever arms of the EDL in relation to the ankle, STJ, LMTJ, OMTJ
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ankle=long lever arm
STJ=relatively long arm LMTJ=relatively long arm OMTJ=relatively long arm |
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When is the EDL active in gait
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midpropulsion thru midswing and then late swing thru the very beginning of contact
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what are the motions of the EDL at the following joints
ankle, STJ, OMTJ |
ankle=dorsiflexion
STJ=pronation OMTJ=pronation |
