Lec 2

Question 1

Prenatal Muscular Development

Answer 1

• during the second half of gestation, rapid increase in number and size of muscle fibers
• all skeletal muscles are developed at birth (all muscles are mixed with slow and fast fibers)
• type 1 (21 weeks)
• type 2 (30 weeks)
• changes in the direction of muscle fibers (trap becomes multiple fiber directions)
• splitting in myotomes (biceps splits into 2 heads)
• degeneration (aponeurosis forms, i.e. linea alba in rectus abdominis)

Question 2

Myotomes

Answer 2

Area of muscles that a nerve goes to and innervates

Question 3

Infant and Childhood Muscular

Answer 3

• number and size of fibers continue to increase, differentiation in fiber type
• at birth muscle mass is only 25% of total body mass
• increased muscular strength as muscles grow and mature
• Males: 14-fold increase in fiber number, fiber size and strength increases until adolescence, 5-17 years; MM increases to 41-53% of total body mass
• Females; 10 fold increase in fiber number, more rapid increase in fiber size (3-10 years peak size), 5-17 years; MM increases to 41-42% total body mass

Question 4

Adolescence Muscular

Answer 4

• type 1 and type2 fiber ratio reaches adult level
• growth spurt; increase in skeletal bones and consequently muscle length
• length-tension relationship is modified through muscle lengthening (addition of sarcomeres and fibers) as bones grow
• increased strength caused by increased MM
• overall peak strength seen in young adulthood (early 20s-30s)
• males; rapid increase in strength and endurance throughout the entirety of adolescence
• females; peak strength at onset of puberty

Question 5

length tension relationship

Answer 5

• the amount of tension or force a muscle can produce depends on how stretched or shortened it is
• during growth spurts, muscles can experience rapid changes in length as the body grows quickly. This can temporarily disrupt the optimal length for force production, which might affect strength and coordination

Question 6

Adulthood Muscular

Answer 6

• muscle strength declines at age 30 (each decade 5% of MM lost)
• coordination declines in 30s, increased muscle strains (physically active adults may not decline as much)
• 50 years: steady decline in strength/impaired fxn
• 50-70 years; 30% decline in strength
• 70 years old; rapid decline in strength

Question 7

Older adults Muscular

Answer 7

• sarcopenia
• senile muscular atrophy
• decreased strength and speed of muscular contraction
• decreased mobility
• greater decline in trunk and lower extremities compared to upper
• pattern of muscle weakness is proximal; most prominent in back, abdominals and quadriceps = impaired balance and equilibrium reactions
• increased rate of loss of type 2 fast-twitch fibers compared to type 1 = dec. speed of contraction = loss of muscular power and mobility, slower reaction times and impaired balance

Question 8

Osteoblasts vs Osteoclasts

Answer 8

• blasts build bone
• clasts absorb bone

Question 9

parts of a bone; diaphysis, epiphysis, epiphyseal plate, epiphyseal lines

Answer 9

diaphysis - shaft of long bone

epiphysis - end of long bone

*epiphyseal plate - area where bone grows

*epiphyseal lines - area where plates have fused together and growth is no longer possible

Question 10

Prenatal Skeletal

Answer 10

• all bones and cartilage develop from the mesenchyme
• 3-8th week; bones and cartilage are differentiated and bone develops
• 5th week; mesenchymal cells condense and differentiate (first in Upper extremity then lower)
• 6th week; chondrocytes form the cartilage of long bones

Question 11

Endochondral ossification?

Answer 11

• growth of cartilage model - 6th week
• development of primary ossifcation center 7-11th week
• development of secondary ossification center after birth
• formation of articular cartilage and epiphyseal plate - after birth

Question 12

Birth Skeletal

Answer 12

• diaphysis well ossified
• is formed by the primary ossification center
• epiphysis still cartilaginous, formed by the secondary ossification center, most bone fractures occur here
• primary curves/kyphotic (thoracic and sacral) curves formed

Question 13

When are secondary curves of the spine formed?

Answer 13

• lordotic cervical and lumbar regions are formed through weight bearing and during walking

Question 14

Infancy and Childhood Skeletal

Answer 14

• skeletal maturity (plates close)
• SMI (hand x-ray, growth plate closure, bone density)
• if scoliosis present, x-ray of iliac crests (risser sign)
• newborn head and trunk are larger
• bone grows rapidly
• bone REMODELING; weight-bearing and moment drive these skeletal changes (pelvis and LE change in length, rotation, angle and torsion)
• fontanelles; soft areas where bone on head hasn’t fused yet
• posterior; 2-3 months
• anterior 12-18 months
  -cranial bones have complete fusion at 18 months
• craniosynostosis; premature closure of sutures
• cranial orthoses (helmet to help shape infant head)
  *important to get those procedures done before fusion of sutures happens

Question 15

When do fontanelles fuse

Answer 15

posterior; 2-3 months

anterior; 12-18 months

Question 16

Adolescence Skeletal

Answer 16

• bone remodeling and growth continues (influenced by hormones, PA, nutrition)
• growth spurts influence skeletal changes; girls 12-14, boys 12-15
• trunk grows before legs
• skeletal growth occurs quicker than muscular growth = improper length-tension relationship = decreased flexibility

Question 17

When do epiphyseal growth plates close and what precautions exist?

Answer 17

all close at 25 or before

• a fracture across a growth plate can lead to asymmetrical growth of that joint
• the use of ultrasound is contraindicated over epiphyseal areas in children or where there remains open growth plates

Question 18

Adulthood Skeletal

Answer 18

• bone growth complete
• bone remodeling and density can increase with weightbearing, muscular contraction, adequate nutrition and calcium intake
• bone mass peaks during late 20s-early 30s and remains stable at 30-50
• bone resorption exceeds bone formation after age 50

Question 19

Older Adults Skeletal

Answer 19

• loss of bone mass, associated with decrease in estrogen - - - females approx 1% year before menopause, 4% during first 4-5 years after menopause then 1% a year
  -males; approx 0.5% per year
• osteopenia; bone mineral density is low but not low enough for osteoporosis
• deficient mineralization of bone matrix (vit D, calcium, phosphate)
• osteomalacia; softening of bones
• structural changes in cartilage
• functional impairments - posture, strength, flexibility

Question 20

Prenatal Functional implications

Answer 20

• concerns; malleable skeletal system in confined envirnment change the fetus position, deformities sue to intrauterine molding
• club foot (planta and inversion)
• congenital hip dysplasia (hip not in socket)
• congenital limb deficiency (portion of upper or lower limp does not form completely)

Question 21

Infancy and Childhood Fxn implications

Answer 21

• concerns; vulnerability of growth plate and cartilage to trauma (injuries can prevent blood/nutrients from getting there and cuase permanent damage)
• increased risk of ligament tears or growth plate fracture due to traumatic mechanisms of injury
• epiphyseal infection and injury
• growth plate fracture
• apophyseal avulsion (piece of bone gets pulled away bc strong muscular contraction)
• nursemaid elbow (toddlers and preschool)

Question 22

Adolescence fxn implications

Answer 22

• increase occurance of stress fractures and apophyseal avulsion fractures
• stress fractures and apophyseal avulsion fractures
• slipped captial-femoral epiphysis (slippage of femoral head due to damage to the growth plate
• scoliosis (common in females)

Question 23

Adulthood and Older adults Fxn Impairments

Answer 23

concerns; decreased strength and endurance bc age-related bone changes, increased risk of fractures

• back pain
• osteoporosis (bone reabsorption > formation)
• osteoarthritis (weight-bearing joints, accumulated microtrauma and inflammation)