Muscles/Ligaments/Tendons tutorial Wk 6 Flashcards
What factors many contribute to high “muscle tone” or higher muscle stiffness in an affected musculotendinous unit of a child with CP?
Increase on collagen content and sarcomere length –> increase passive tension
Describe spasticity and contracture using language that is appropriate for a patient of a child with CP
- Spasticity is just when your muscle continue to contract without any control from the person this is due to an upper motor neuron lesion. This is due to a decreased inhibition of stretch reflexes
- Contractures is when your muscles continuously contract without control and this causes your muscles, tendons and ligaments to become hardened and causes deformity and rigidity of your joints
- Spasticity- neural
- Contractures- non-neural
- With CP = loss of function, greater contraction affects bones
What is the order of events that can lead to spasticity and contractures of the musculotendinous unit?
Muscles sense stimulus (fake) –> sends signal to troponin for tropomyosin to open the myosin heads –> actin attaches –> actin and myosin cross bridging
Which structures transmit forces passively?
- Actin and myosin cross bridging generate force
- Titin (anchors myosin to z line) and connective tissue (endomysium; perimysium; epimysium transmits force passively
Where do most injuries occur within the musculotendinous unit?
musculotendinous junction
Why is the musculotendinous junction the most prone location to injury?
- Going from a elastic material to a more stiff material
- A lot of force being transmitted
What is the pre-cursor of somites?
Mesoderm
What does the notocord do?
sends out stimulus to differentiate- neural tube
What structures develop from mesoderm?
dermatomes; myotomes; scleratomes –> skeletal muscles, skin, bone and connective tissue In series and bilateral paired- symmetry
Describe some of the changes that are likely with active loading (e.g. increased exercise) to: Tendon stiffness
- increases tendon stiffness
- isometric (esp. eccentric) contraction is beneficial
- not endurance, stretching (short term)
- 3-5% strain
Describe some of the changes that are likely with active loading (e.g. increased exercise) to: Muscle fibres
- Endurance training- changes from type II to I (due to exercise)
- Have changes due to genetics (predisposed)
- Type II- easily fatiguable
- Type I (slow twitch)- smaller force generated but able to be sustained
- Muscle changes occur faster (wraps up)
- Tendon changes occur faster (after detraining)
What is sacropenia?
Loss of mean body mass
What are 7 changes in the musculotendinous unit that are likely with ageing?
- Muscle fibres decrease in number and size; greater change to type II
- Muscle fibre type transformation (fast –> slow)
- Myofilaments
- reduce in single fibre max. force reduce in myosin protein content and function
- Reduce in elasticity
- Mitochondria
- Reduce in no of type II
- Loss in enzyme content = decreased ability to create ATP from oxygen = type I fibres more affected (type I and IIa more oxydated)
- Excitation-contraction coupling
- Disruption or uncoupling
- Deficits in Ca2+ release
- Satellite cells reduce in number- less response to injury
- Adipose tissue infiltration
- Where the muscle was –> increase pennation angle –> increase ability to transfer forces (can help a bit)
- Fascicle length increase