Musculoskeletal Development and Adaptation Flashcards
What are somites
Precursor cells that differentiate into dermis (dermatome), skeletal muscle (myotome), and vertebrae (sclerotome)
- Sclerotome differentiates first because vertebre develops very early on in development
- Dermomyotome then forms primary and secondary myotubes (GMs directly correlate to when they get innervated)
- Primary –5-7 weeks GA, Type I fibers (corresponds to spontaneous movements)
- Secondary –30 weeks gestation, Type II fibers later on
(do not need to know Gestational age)
Describe early muscle cells and what should we keep in mind?
Early on there is a lot of interstitial fluid in muscle cells (60% to 20% by 36 weeks)
you have to think about what happens when a baby is born prematurely - what is going on with their muscle fibers, does it relate to strength
Explain what happens to muscles from birth to childhood
1st year after birth muscle fibers divide from existing cells
through childhood muscles increase in length and girth with addition of sarcomeres
What are mononucleated satellite cells and what happens if there is a problem with them?
They are helper muscle cells that hang out next to muscle cells. If muscle cell gets damaged they respon and regenerate damaged cells.
If there is a problem with these cells then this would lead to significant weakness
How are type 1 and type2 muscle fibers distributed
random in a mosaic pattern
how would steroid use, malnourishment and spasticity affect muscle fibers
Steroid use –atrophy of type II
–Malnourishment –conversion of type II to I
–Spasticity leads to structural changes
Muscle Growth is Influenced By?
- Tension of bony growth for length stretches muscle and sarcomeres added so growth is at similar rate to bone
- Active stress of exercise –provides thickness (when working with kids you want to add bulk. also look at the symmetry)
• Strength through use!
-this influences muscles and boney development
Why would you want to cast someone in a lengthen position?
lengthen position will increase sarcomeres while a shortened on will decrease them
After 4 weeks this will revert unless you continue to use the length. This kids will need neuro re-education to keep the length
What are the hip stabilizers and what do they do
Loading stance leg with hip external rotators strengthening, as glut max and TFL couple with IT Band to decelerate lateral weight shift and maintain pelvic alignment
Stance leg goes into relative IR and External rotators help from collapsing. Babies who do not really walk you will see it band anterior and extensors will be lateral. This will also help with the development of greater trochanter and torsion of our bones
- lateral muscle shift laterally and torsion of the bone happens bc of ER force from the muscle
What are growing pains
pains caused by the muscle trying to keep up with the bone growth, bc bone grows first
Consideration with hypertonicity and children
If you have a hypertonic muscle and the kid has a growth spurt then that muscle get even tighter. this will directly affect ROM.
You need to stay ahead of growth spurts
Muscle concerns with CP
- muscle growth is even slower than normal
- sarcomere stretch but there is dec. force production
- inc. risk of injure
- muscle is replaced by collagen
- inc. stiffness at every level (muscle and connective tissue)
while these kids are growing you have to maintain length and strength
What are the 2 processes of bone formation
–Endochondral (intracartilaginous) ossification
–Intramembranous ossification (clavicle, mandible, skull)
Intramembranous ossification
Ossification occurs directly on mesenchymal model
Endochondral (intracartilaginous) ossification
Think long bones
• Mesenchymal models—-collagenous and elastic fibers deposited—–cartilaginous models—-bone minerals deposited–replace cartilage via ossification
When and where does primary ossification start?
Primary ossification in center of diaphysis starts at 8th week of gestation
When are most bones ossified by (age)
20 years
When are children prone to injury?
There is a growth and ossification hasn’t caught up yet
Why would a full term baby bone be stronger than a premature baby bone?
Because ossification happens throughout gestation. So preemies will come out a bit osteopenic
What type of forces lead to bone growth
Loading forces - growth and thickness
intermittent forces lead to bone growth and sustained forces lead to limited growth
Tension - (muscle) provides raised surfaces to the bones (ie: tubercles)
Shearing forces - twisting of bones
Most change to skeletal modeling can be made in the first _____ years
2
Joint formation
- Begins with cartilaginous models (similar to long bones) with differentiation for joints
- Basic structures formed during 6-8th week gestation, development continues throughout early childhood
Hip joint development
during gestation acetabulum covers femoral head
at birth half of the femoral head covered
coverage inc. until age 10
How do we regain coverage of hip joint?
What happens to children who are NWB
ABduction forces and WBing. Pushes trochanter into acetabulum
children who are not weight bearing will end up with shallow hip joints putting them at risk for dislocation
