Musculoskeletal Development

Question 1

Does the number of axons innervating a muscle fiber increase or decrease?

Answer 1

• skeletal muscle fiber innervated by many axons but the number decreases to 1 axon

Question 2

1st year of life, why do the the amount of muscle fibers continue to increase ?

Answer 2

due to division of existing fibers or development of new fibers

Question 3

What happens to muscle fibers during the years of growth? Why?

Answer 3

yrs of growth, muscle fibers increase in length and cross sectional area by the addition of sarcomeres

muscle fibers increase in size as
a result of blood supply, innervation, nutrition, genetics and exercise (exposure)

Question 4

Which factors impact fiber types?

Answer 4

Fiber types are dependent upon neuronal input,

genetics, exposure and disease processes

Question 5

Ossification of the diaphyses of the bone
(body of bone) commences by the end
of the _____ week of gestation and is near complete by birth

Answer 5

8th week of gestation

Question 6

By _______, the diaphysis (body of the bone) are almost ossified

Answer 6

Birth

Question 7

The thickness of the diaphysis continues

to grow slowly by adding new bone to the A)________, with spurts of growth @ B)__-__ and C)_______

Answer 7

A) outside surface

B) 4-6 years old

C) puberty

Question 8

Ossification of the epiphyses of the bone

varies with each bone, but most are ossified by ______.

Answer 8

20 years

Question 9

The basic structures that will form joints are present by ___-___ weeks of gestation and continues to develop over a long period of time

Answer 9

6-8 weeks

Question 10

By _______ of gestation acetabulum is deep and

femoral head is well covered

Answer 10

12 weeks

Question 11

What are some factors that deepen the acetabulum?

Answer 11

Postnatal growth, compression, movement and exposure all increase the depth of the acetabulum

Question 12

What is a positive adaptation of muscle fibers?

Answer 12

• Our muscles respond to the challenges placed on them

* Increasing environmental exposure, specifically early in development, will influence muscle development

Question 13

What is negative adaptation of muscle fibers?

Answer 13

Selective atrophy

Question 14

When might one see selective atrophy of type II muscle fibers?

Answer 14

• children with muscular diseases
• adults with steroid induced atrophy
• spastic muscles of children with CP
• muscles that have been denervated (both atrophy, but more type II)
• malnourished children

Question 15

When might one see selective atrophy of type I muscle fibers?

Answer 15

• children with hypotonia

* children with congenital myotonic dystrophy

Question 16

Which is more common, selective atrophy of type I or type II muscle fibers?

Answer 16

Type II

Question 17

What force length adaptations will occur in muscle secondary to immobilization?

Answer 17

Leads to a shorter muscle, which changes the length
tension curve. The child may now be physiologically strongest in a place in ROM that is inappropriate, or simply not effective

Question 18

What force length adaptations will occur in muscle secondary to disuse atrophy?

Answer 18

Decreased strength will obviously impact on abilities

Longer tendon & shorter muscle belly

Question 19

What force length adaptations will occur in muscle secondary to Decreased muscle length?

Answer 19

Arguments for decreased muscle length and increased tendon length in spastic muscles with increased tone

Question 20

Muscular length changes will have profound

effects on function including:

Answer 20

• posture in sitting, standing
• available ROM and subsequent functional abilities
• gait
• cardiopulmonary

Question 21

Skeletal adaptations are dependent upon…

Answer 21

Dependent upon genetics, nutrition and mechanical

forces (exposure)

Question 22

Normal intermittent forces __________ bone growth.

Excessive forces will actually _______ this growth.

Answer 22

Stimulate

Diminish

Question 23

What do the knees of an infant look like in the frontal plane?

Answer 23

Genu varum

Question 24

What do the knees of a 20 month old look like in the frontal plane?

Answer 24

Straight

Question 25

What do the knees of a 2.5 yo look like in the frontal plane?

Answer 25

Genu valgum

Question 26

What do the knees of a 4-6 year old look like in the frontal plane?

Answer 26

Normal valgum/ straight

Question 27

The abnormal stresses of spasticity may lead to _______

Answer 27

Degenerative joint disease

Question 28

Define Dysplasia.

Answer 28

Abnormal development or

growth of tissues, organs, or cells

Question 29

When would you expect to see hip dysplasia?

Answer 29

CP, MD, downs syndrome or other processes which alter the muscle forces around the hip will predispose a
child to hip dysplasia

Question 30

According to Buckley et al, which pathologic pediatric population had the most shallow acetabulum?

Answer 30

CP

Question 31

Femoral anteversion results in a toe___ gait

Answer 31

Toe in

Question 32

Spasticity will impact
A) antagonist
B) agonist
C) synergist strength

Answer 32

Antagonist