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The growing nervous system
The nervous system continues to change after birth. Early movement patterns provide one visible window into this process because coordinated sitting, standing, crawling, and walking depend on communication between the brain, spinal cord, sensory systems, and muscles.
Development is not measured by one isolated skill. Children reach abilities across broad ranges, and the order and quality of movement are more informative than treating a table as a prediction for an individual child.
Stages of nervous system development
Nervous system development can be described through four connected processes:
- Cell specification: developing cells take on neural or glial identities.
- Migration and axon growth: neurons move into position and extend processes that carry signals.
- Synapse formation: neurons establish communication points with other neurons, muscles, or glands.
- Connection refinement: useful pathways are strengthened while less-used branches are reduced.
Glial cells support this network. Oligodendrocytes help insulate central nervous system axons, astrocytes support the chemical and structural environment, and microglia contribute to immune surveillance and tissue maintenance.
Postnatal milestones
Developmental research often records structural and sensory changes by postnatal day in animal models. These findings help researchers study timing and mechanisms, but they should not be read as a direct timetable for human children.
| Developmental process | Why it matters |
|---|---|
| Growth of corticospinal pathways | Supports communication between motor areas of the brain and spinal circuits. |
| Synaptogenesis | Creates communication points that allow neural networks to process information. |
| Myelination | Insulates selected axons and can improve the speed and reliability of signalling. |
| Sensory pathway maturation | Helps visual, auditory, smell, touch, and balance systems process input. |
Myelination begins in different regions at different times. Broadly, pathways supporting essential early functions mature before many higher-order networks, while development and refinement continue through childhood and adolescence.
Brain development
The brain develops from the embryonic neural tube. Its early regions become interconnected structures with specialised roles, while later growth and refinement shape how those structures work together.
The prosencephalon
The prosencephalon, or forebrain, gives rise to the cerebrum and diencephalon. The cerebrum includes the cerebral cortex, underlying white matter, basal nuclei, hippocampus, amygdala, and related structures. Its networks contribute to learning, memory, movement, language, and emotional processing.
The diencephalon includes the thalamus and hypothalamus. The thalamus relays much sensory information, while the hypothalamus helps regulate internal balance and autonomic functions.
The mesencephalon
The mesencephalon, or midbrain, forms part of the brainstem. It participates in orienting responses, eye movement, motor control, and the processing of visual and auditory information.
The rhombencephalon
The rhombencephalon, or hindbrain, contributes to the pons, cerebellum, and medulla. These structures help coordinate movement and balance and support vital functions such as breathing, heart regulation, sleep, and reflexes.
Development of the spinal cord
The spinal cord contains sensory pathways that carry information toward the brain and motor pathways that carry commands outward. Its organisation is often described through cervical, thoracic, lumbar, sacral, and coccygeal regions.
Spinal nerves leave the cord in paired groups and connect the central nervous system with tissues throughout the body. As pathways mature, myelination and synaptic refinement support increasingly efficient movement and sensory processing.
Postnatal nervous system development is therefore both rapid and ongoing. Early growth establishes essential circuits, while later experience, practice, sleep, and learning continue to modify how networks operate.
References
- Chen, V. S. et al. (2017). Histology Atlas of the Developing Prenatal and Postnatal Mouse Central Nervous System. Toxicologic Pathology, 45(6), 705–744.
- Hill, M. A. (2019). Development of the Nervous System and Neural System – Postnatal. Embryology reference materials.
- Staveley, B. E. (n.d.). Development of the nervous system. Molecular and developmental biology teaching resource.