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Neuroanatomy II
Musculoskeletal Development and Adaptation
Question | Answer |
---|---|
A position in which the distal segment of the joint is directed laterally is? | Valgum |
A position in which the distal segment of the joint is directed medially is? | Varum |
A twist within the shaft of a long bone, along its longitudinal axis is? | Torsion |
This occurs when the femoral neck is angled anteriorly to the transcondylar axis of the femur. | Antetorsion |
A positional change in which either the acetabulum or the head an neck of the femur are directed anteriorly, relative to the frontal plane is called? | Anteversion |
Embryonic myoblasts arise from ______? | mesodermal cells |
Embryonic myoblasts differentiate into ________? | myotubes |
What are myotubes? | immature, multinucleate tubular structures |
What are the two distinct types of myotubes? | primary, secondary |
When can primary myotubes be seen? | 5 wks gestation |
Do primary myotubes develop and differentiate with or without neural influence? | without |
What type of muscle fibers do primary myotubes become? | mainly Type 1(slow twitch) |
When can secondary myotubes be seen? | several weeks after primary myotubes |
Are secondary myotubes dependent on neural input? | yes |
What happens if there is no neural input for secondary myotubes? | they will be smaller, fewer in number and malformed |
What type of fibers to secondary myotubes become? | type II muscle fibers(fast twitch) |
When do myotubes fuse and form muscle fibers? | By 20 weeks GA |
When are ACH receptors dispersed in the myotubular membrane? | By 8 weeks GA |
What is a motor unit? | Motoneuron and the muscle fiber it innervates |
What does the presence of motor activity indicate? | a viable connection of the motor unit |
Skeletal and Articular Structures Arise from which layer? | mesodermal layer |
What cells condense to form templates for the skeleton? | Mesenchymal |
What are the two distinct processes of bone formation? | endochondral and intramembranous ossification. |
What are the only bones that dont form via endochondral ossification? | skull, clavicle and mandible. |
What form of ossification is this....Collagenous & elastic fibers are deposited on mesenchymal models to form cartilaginous models. Bone minerals are deposited on these models, gradually replacing cartilage via ossification? | endochondral ossification |
What form of ossification is this....Occurs directly in the mesenchymal model, mesenchymal cells differentiate into osteoblasts then deposit a matrix called osteoid tissue, tissue organized into bone as calcium phosphate is deposited.? | intramembranous ossification |
When does ossification at the primary ossification centers occur? | at the end of embryonic period(8 wks ga) |
What are primary ossification centers? | diaphysis(body) of bone |
By birth, are diaphysis ossified? | almost |
What are the ends of bones called? | epiphysis |
The epiphysis remain _______. | cartilaginous |
When does ossification begin in the epiphyses of bone? | during early childhood |
Where does long bone grow in length? | at the epiphyseal plate |
Where does bone proliferation occur? | at the diaphyseal side of the bone |
When are most bones fully ossified? | by age 20 |
When are basic structures of the joint formed? | by 6-8 wks GA |
What influences the shape of joints? | forces of mvmt and compression |
Growth and shape of the skeleton are affected by? | genetic coding, nutrition, and mechanical forces over time. |
Can mechanical forces such as muscle pull and weight bearing cause skeletal adaptations? | yes |
Once the cartilaginous template is formed does the basic shape of the skeletal system change? | no |
What can cause natural and atypical angular changes, and what happens if these forces are too great or too small? | compression, tension and shear forces at epiphyseal plate\the rate of growth is diminished |
Growth is stimulated by areas of _______ and diminished in areas of _________. | tension,compression |
What leads to torsional twisting of bone? | shear forces |
At birth there how many degrees of medial torsion of the tibia? | 5 |
In adulthood there is how many degrees of lateral torsion of the tibia? | 18-47 |
At birth, an infants knees are _____? | bow legged(genu varum) |
What age is neutral knee alignment reached? | 1-2 years |
When does genu valgum reacjhits peak? | 2-4 years of age |
Females typically have slight ________(valgum or verum). | valgum |
Males typically have slight ________(valgum or verum). | verum |