MOD 10

Question 1

What is the process of myelination?

Answer 1

Formation of the myelin sheath around axons

Myelin is a fatty insulating layer that promotes rapid and efficient transmission of electrical signals in the nervous system.

Question 2

When does myelination begin and progress rapidly?

Answer 2

Begins in fetal development, progresses during the first two years of life

Myelination continues into adolescence and early adulthood, especially in higher order brain regions.

Question 3

What are the consequences of delayed or disruptive myelination?

Answer 3

• Challenges with coordination
• Timing issues
• Motor planning difficulties

Myelination is especially important in corticospinal tracts, cerebellar pathways, and peripheral nerves.

Question 4

What is neural tube formation?

Answer 4

One of the earliest and most critical steps in CNS development

Disruptions can lead to a wide range of motor impairments depending on severity and timing.

Question 5

When does neural tube formation begin?

Answer 5

Around 3 to 4 weeks of gestation

This forms the foundation of the central nervous system, including the brain and spinal cord.

Question 6

What can result from the failure of neural tube closure?

Answer 6

• Spina bifida
• Anencephaly

Spina bifida can range from mild (occulta) to severe (myelomeningocele), leading to various motor deficits.

Question 7

What are somites?

Answer 7

Segmented blocks of mesoderm that form along the head to tail axis of the developing embryo

They give rise to vertebrae, skeletal muscle, and dermis.

Question 8

What do sclerotomes, dermatomes, and myotomes form?

Answer 8

• Sclerotomes: Vertebra and ribs
• Dermatomes: Dermis of the skin
• Myotomes: Skeletal muscles

Proper segmentation is essential for symmetrical musculoskeletal development.

Question 9

When does limb bud formation begin?

Answer 9

Around 4 to 5 weeks of gestation

Limb buds emerge from the lateral plate mesoderm and are covered by ectoderm.

Question 10

What is Amelia?

Answer 10

Complete absence of a limb

Other limb formation issues include syndactyly (fused digits) and polydactyly (extra digits).

Question 11

What is the significance of fetal movement?

Answer 11

Promotes joint formation, muscle growth, and neurologic development

Movement is necessary for establishing reflex pathways and motor control.

Question 12

What can reduced fetal movement indicate?

Answer 12

• Neuromuscular disorders
• Central nervous system malformations
• Fetal growth restriction
• Placental insufficiency

It may lead to delayed motor milestones or hypotonia after birth.

Question 13

What is the role of the cerebral cortex in motor development?

Answer 13

Undergoes synaptic pruning, circuit refinement, and functional specialization

Matures into the third decade of life, especially the prefrontal cortex.

Question 14

What does the cerebellum contribute to?

Answer 14

Motor learning, balance, and coordination

Rapid growth occurs in the first year of life, critical for refining motor control.

Question 15

What are potential outcomes of cortical abnormalities?

Answer 15

• Motor planning disorders
• Developmental coordination disorders
• Dyspraxia

These can disrupt motor planning and coordination.

Question 16

How does genetics and embryology influence motor development?

Answer 16

Processes begin before birth and continue through infancy

Understanding these foundations helps physical therapists reason and prioritize treatment.