Development of Central Nervous System

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Questions and Answers

What is the outermost layer of the embryonic disc from which the nervous system is derived?

Epiblast

Endoderm

Mesoderm

Ectoderm (correct)

At what stage of development does the primitive streak appear?

End of week four

End of week three

End of week two (correct)

End of week one

What is the structure that forms from the fusion of the neural folds?

Neural plate

Neural crest

Neural tube (correct)

Notochord

What is the function of the notochord?

To secrete growth factors that stimulate the differentiation of the overlying ectoderm Signup and view all the answers

What is the name of the process by which the neural tube is formed?

Neurulation Signup and view all the answers

What is the name of the process during which the neural folds meet in the midline and fuse?

Neurulation Signup and view all the answers

Which of the following cells does not differentiate from neuroderm cells?

Melanocytes Signup and view all the answers

What is the name of the structure that develops from the caudal end of the neural tube?

Spinal cord Signup and view all the answers

What is the name of the cell population that forms from the migration of cells within the neural folds?

Neural crest Signup and view all the answers

At what stage of development does the nervous system begin to form?

End of week three Signup and view all the answers

How many secondary vesicles develop from the primary vesicles in the brain?

5 Signup and view all the answers

What is the name of the structure that develops from the metencephalon?

Pons and cerebellum Signup and view all the answers

What is the term for the three layers that form from the initial two layers of the bilaminar disk?

Trilaminar embryonic disk Signup and view all the answers

What is the function of axons and dendrites in neurons?

To receive and transmit signals Signup and view all the answers

Which of the following is not a derivative of the rhombencephalon?

Thalamus Signup and view all the answers

What is the name of the process by which neurons migrate to their final destination in the brain?

Neuronal migration Signup and view all the answers

What is the main function of myelin in the nervous system?

To insulate nerve cells and allow for rapid communication Signup and view all the answers

Which part of the brain is responsible for controlling voluntary actions?

Cerebrum Signup and view all the answers

What is the term for the convolutions of the cerebral cortex?

Gyri Signup and view all the answers

Which lobe is responsible for speech output and organizational skills?

Frontal lobe Signup and view all the answers

What is the term for the mass of fibers that links the two hemispheres of the cerebrum?

Corpus callosum Signup and view all the answers

Which hemisphere controls voluntary limb movements on the right side of the body?

Left hemisphere Signup and view all the answers

What is the location of the primary motor cortex?

Frontal lobe, anterior to the central sulcus Signup and view all the answers

How many lobes are there in each hemisphere of the cerebrum?

4 Signup and view all the answers

Which part of the brain is responsible for processing memory and auditory information?

Temporal lobe Signup and view all the answers

What is the primary function of the Corpus Callosum?

To connect the two hemispheres together Signup and view all the answers

Which area of the brain is responsible for processing information about numbers and spatial awareness?

Somato-sensory cortex Signup and view all the answers

What is the primary function of the primary visual cortex?

To process raw sensory information from the retina Signup and view all the answers

Which areas of the brain are closely linked in the comprehension and production of speech?

Wernike's area and Broca's area Signup and view all the answers

What is the outermost layer of the brain?

Gray matter Signup and view all the answers

What is the function of the neurons in the gray matter?

To store and process information Signup and view all the answers

What is the primary function of the somato-sensory cortex?

To receive general sensory information and initial reception of tactile and proprioceptive information Signup and view all the answers

What is the term for the pathway that connects the motor cortex to the spinal cord?

Corticospinal tract Signup and view all the answers

What is the function of the thalamus in sensory processing?

To filter and relay sensory information to the cortex Signup and view all the answers

Which type of fiber carries impulses away from the cortex to other areas of the brain?

Efferent fibers Signup and view all the answers

What is the term for the protective covering that surrounds axons outside the gray matter?

Myelin Signup and view all the answers

Which lobe of the brain is responsible for processing visual information?

Occipital lobe Signup and view all the answers

What is the term for a group of nerve cell bodies in the gray matter?

Nucleus Signup and view all the answers

What is the function of the motor cortex?

To generate motor responses Signup and view all the answers

Which of the following tracts connects the cortex to the brainstem?

Corticopontine tract Signup and view all the answers

Study Notes

Development of the Central Nervous System

The nervous system begins to form in the 3rd week of development and continues after birth and for many years into the future.
The nervous system is divided into two parts: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
CNS consists of the brain and spinal cord, while PNS consists of cranial and spinal nerves, ganglia, plexuses, and sensory receptors.

Early Stages

At the end of week two, a structure called the primitive streak appears as a groove in the epiblast layer of the bilaminar disk.
Cells within the epiblast migrate downward through the primitive streak, giving rise to three layers: Endoderm (innermost layer), Mesoderm (middle layer), and Ectoderm (outermost layer).
The nervous system is derived from the Ectoderm.

Neurulation

In the third week of development, the notochord appears in the Mesoderm and secretes growth factors that stimulate the differentiation of the overlying Ectoderm into neuroectoderm.
The neuroectoderm forms a thickened structure known as the neural plate, which then rises to form neural folds.
The neural folds move towards each other and meet in the midline, fusing to form the neural tube (precursor to the brain and spinal cord).
During fusion of the neural folds, some cells within the folds migrate to form a distinct cell population known as the neural crest.
The neural crest gives rise to a diverse cell lineage, including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons, and glia.

Later Development

Brain and Cerebellum

In the fifth week of development, swellings appear at the cranial end of the neural tube, forming three primitive vesicles.
The primitive vesicles develop into five secondary vesicles, which give rise to all structures of the brain.
Neuroderm cells begin to differentiate into neurons and glial cells, migrating throughout the brain and developing axons and dendrites to form synapses.

Spinal Cord

The caudal end of the neural tube develops to form the spinal cord.
A fatty material called myelin coats nerve cells to insulate them and allow for quick communication.

The Cerebrum

The cerebrum is the largest part of the brain and controls voluntary actions, speech, senses, thought, and memory.
The surface of the cerebral cortex has grooves or infoldings (called sulci), which separate lobes.
The cerebrum is divided into two halves, known as the right and left hemispheres, which are linked by the corpus callosum.
Each hemisphere is divided into four lobes: frontal, parietal, temporal, and occipital, which are interconnected and process different types of information.

Lobes of the Brain

Frontal lobes: responsible for voluntary movement, speech output, organizational skills, and certain aspects of behavior, mood, and memory.
Parietal lobes: process sensory information such as temperature, pain, taste, and touch, and are involved in processing information about numbers and spatial relationships.
Temporal lobes: process memory and auditory information, and are responsible for higher-order visual information, complex aspects of memory, language, and comprehension of language.
Occipital lobe: main visual processing area of the cortex, processing information on color, objects, and facial recognition.

Corpus Callosum

The corpus callosum is the largest fiber bundle in the brain and connects the two hemispheres together, allowing for the transmission of information between them.

Thalamus

The thalamus is the main part of the Diencephalon and is located between the midbrain and cerebellum.
All sensory pathways pass through the thalamus, which filters incoming information and decides what to pass on or not to pass on to the cortex, preventing the overload of sensory information.

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Description

Learn about the formation and development of the central nervous system from the 3rd week of fertilization to many years after birth. Understand the structural divisions of the nervous system into central and peripheral parts.