Musculoskeletal and Nervous System Development

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Questions and Answers

What is the consequence of unregulated osteoclast activity in bone ossification?

Increased muscle capacity

Enhanced bone growth

Development of osteoporosis (correct)

Improved joint flexibility

What triggers the closure of epiphyseal growth plates?

Excessive physical activity

Injury to the growth plate

High levels of estrogen and testosterone (correct)

Reduction of calcium levels

Which of the following changes is NOT associated with the musculoskeletal development in early life?

Growth in muscle capacity

Increased force production capability (correct)

Nervous system organization

Changes in body dimensions

Which factor is responsible for the ability of myoblasts to regenerate muscle fibers after injury?

Unfused myoblasts Signup and view all the answers

What limits children's recruitment of Type II muscle fibers compared to adults?

Muscle maturation stages Signup and view all the answers

What primarily limits the muscular force production capacity in children?

Lower frequency of motor neuron firing Signup and view all the answers

What percentage of adult brain size does an infant's brain reach by the age of three?

80% Signup and view all the answers

What is essential for the maturation of the corticospinal tract in developing motor skills?

Elimination of terminations in the spinal cord Signup and view all the answers

During which period does the cerebellum undergo the most significant changes?

In the first year of life Signup and view all the answers

What developmental process is guided by basic movements and sensory feedback?

Synapse elimination Signup and view all the answers

Which reflex involves visual cues to aid in head righting?

Optical righting reflex Signup and view all the answers

What is the primary function of the labyrinthine righting reflex?

To maintain head position against gravity Signup and view all the answers

The neck righting reflex is primarily triggered by which condition?

Stretching of neck muscles Signup and view all the answers

At what age range is walking typically achieved in many children?

9-18 months Signup and view all the answers

Which of the following best describes the development of arm movements in infants?

Initial movements are primarily reflexive and random Signup and view all the answers

What pattern characterizes the development of postural control in children?

Control develops from head to trunk to legs Signup and view all the answers

Which reflex is stimulated by the foot touching a hard surface?

Stepping reflex Signup and view all the answers

What is a common misconception about human locomotor control development?

Humans can walk immediately after birth Signup and view all the answers

What role do unstructured limb movements play in development?

They provide opportunities to learn arm dynamics. Signup and view all the answers

Which reflex is primarily associated with placing the foot on a supporting surface?

Placing reaction Signup and view all the answers

Study Notes

Musculoskeletal System Development

Body size and proportion change significantly in the first few years of life, impacting movement capabilities.
Changes in body dimensions, bone growth, muscle capacity, and nervous system organization occur simultaneously during this period.
Bone ossification is a process where osteoclasts destroy bone tissue to create the bone marrow cavity; tightly controlled to prevent osteoporosis.
Epiphyseal growth plates enable bone growth after birth and can be damaged by large compressive loads.
Estrogen and testosterone contribute to growth plate closure.
Muscle fiber development involves myoblast fusion due to increased calcium flow between cells.
Some myoblasts remain unfused, crucial for muscle regeneration after injury.
Children have a lower capacity for force production due to a smaller proportion of Type IIX muscle fibers.

Nervous System Development

At birth, the brain is 25% of its adult size, but contains the same number of neurons.
The brain reaches about 80% of its adult size by age 3, due to increases in neuronal connections and myelination.
During the first year, the number of synapses in the cortex more than doubles, enhancing communication within and between brain areas.
Synapse elimination is crucial for brain maturation, particularly in the corticospinal tract and cerebellum.
The cerebellum triples in volume in the first year, while the cerebrum increases by one-third, due to growth of axons, dendrites, and synapse formation.

Midbrain and Cerebral Cortex Reflexes

Righting reflexes, like the labyrinthine and neck righting reflex, help maintain head level against gravity.
The optical righting reflex relies on visual cues to right the head.
The placing reaction involves visual and proprioceptive cues for foot placement on supporting surfaces.
The stepping reflex, triggered by contact with a hard surface, mimics a primitive walking pattern.

Development of Postural and Locomotor Control

Postural control develops from the head to the trunk to the legs, with milestones occurring within specific age ranges.
Humans are not born walking, with independent walking occurring between 9-18 months, as opposed to many animals.
Early arm movements are often random, providing opportunities to learn arm dynamics.
Voluntary movements gradually increase, with finger movements progressing from coordinated to independent, and thumb opposition developing later.

Information Processing and the Critical Period for Learning

Reaction times (RTs) are longest in young children and become more complex with age.
Older children are less sensitive to complexity than adults but still have longer RTs.
Learning complex movements can't happen until simpler tasks are learned.

Teenage Motor Control and Common Motor Changes in Older Adulthood

Rapid physical growth during adolescence temporarily disrupts internal models, leading to clumsiness.
Neuron density does not significantly decrease with age; some decreases occur in specific brain areas.
Increased reaction times (RTs) and movement times (MTs) in older adulthood reflect changes in sensory receptors and reduced motor units.
Changes in the vestibular system delay postural responses, increasing the risk of falls.

Effects of Exercise on Motor Changes in Older Adulthood

Resistance training can increase force development, improving balance and other motor functions.
Sensory training can induce neural plasticity in the vestibular and kinesthetic systems.
Aerobic exercise can reduce the risk of cardiovascular and other diseases.

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Description

Explore the intricate changes in the musculoskeletal and nervous systems during early development. This quiz covers important processes such as bone ossification, muscle fiber development, and brain growth dynamics. Test your understanding of how these systems evolve in early life and their impact on movement and physical capabilities.