Development of the Nervous System Flashcards
What embryonic tissue does the nervous system develop from?
Ectoderm
When is the development of the neural plate induced, and what is it induced by?
By the end of the 3rd week of development and it is induced by the notochord, which is of mesodermal origin and the anterior notochord thickens, which forms the neural plate.
What does the neural crest differentiate into?
Distinct neurons, such as:
- Cranial Nerve Sensory Ganglion Cells
- Dorsal Root Ganglion Cells
- Postganglionic Autonomic Ganglion Cells
- Chromaffin Cells of Adrenal Medulla
- Schwann Cells
- Melanocytes
What are the 3 main vesicles of the anterior neural tube in the early stage?
Prosencephalon - forebrain
Mesencephalon - midbrain
Rhomboenchephalon - hindbrain
What does the caudal aspect of the neural tube become?
Spinal Cord
What are the 5 main vesicles of the anterior neural tube in the later stage?
Telencephalon Optic Vesicle Diencephalon Pons (Metencephalon) Medulla (Myelencephalon)
What does the prosencephalon form?
Telencephalon
Diencephalon
What does the mesencephalon form?
Mesencephalon - remains
What does the rhomboencephalon form?
Metencephalon
Myelencephelon
What develops from the telencephalon?
Cerebral Cortex
Basal Ganglia
Amygdala
Hippocampus
Lateral Ventricles
What develops from the diencephalon?
Thalamus Hypothalamus Choroid Plexus Pituitary Gland (neurohypophysis) -> only half Pineal Gland
3rd Ventricle
What develops from the mesencephalon?
Midbrain
Cerebral Aqueduct
What develops from the metencephalon?
Pons
Cerebellum
4th Ventricle
What develops from the myelencephalon?
Medulla
Central Canal
What is the inner layer of the neural tube?
Ventricular
What is the intermediate layer of the neural tube?
Mantle
What is the outer layer of the neural tube?
Marginal
Describe the migration of cells in the neural tube?
They migrate from the ventricular to the marginal layer, with the mantle layer forming the gray matter and the ventricular layer forming the white matter.
What is the groove that appears at the midpoint of the neural tube during development called?
Sulcus Limitans
What forms the Alar Plate?
Cells migrating dorsal to the sulcus limitans
What forms the Basal Plate?
Cells migrating ventral to the sulcus limitans
What do the neurons in the Alar Plate contribute to?
Sensory
What do the neurons in the Basal Plate contribute to?
Motor
What nerve groups are located in the dorsal horn of the spinal cord?
GSA
GVA
Sensory
What nerve groups are located in the ventral horn of the spinal cord?
GVE
GSE
Motor
Describe the motor and sensory division in the medulla.
Motor divisions are medial and sensory divisions are lateral.
What are the foramen of the hindbrain ?
Foramen of Luschka - lateral (2 of them)
Foramen of Magendie - medial (only 1)
What are the 3 regions of the midbrain?
Tectal Region - dorsal
Tegmentum - intermedial
Peduncular - ventral
What is the sensory region of the midbrain?
Tectal Region
What is the motor region of the midbrain?
Tegmentum
What is the sensory modulating center of the brain?
Thalamus
What are the structures that cross the midline of the brain and connect the left and right hemispheres?
Anterior Commissure
Posterior Commissure
Corpus Callosum
What are some neural tube defects?
Spina Bifida Occulta - incomplete closure of the neural tube and it does not usually present problems
Spina Bifida Cystica - bulging of the neural tube out
Rachischisis - failure of the neural tube to form
Does the nervous system form before the skull?
Yes
What are the cranial defects?
Menigocele - only arachnoid
Meningoencephalocele - brain and arachnoid
Meningohydroencephalocele - brain, arachnoid and the ventricle
What does the rostral part of the neural tube become?
Brain
What does the caudal part of the neural tube become?
Spinal Cord
What does failure of the closure of the anterior neural tube cause?
Upper Neural Tube Defects
What does the failure of the closure of the posterior neural tube cause?
Lower Neural Tube Defects
What is neurocristopathy?
Any disease related to maldevelopment of neural crest cells
What is medullary carcinoma (MC) of thyroid?
It is is an endocrine neoplasm of the parafollicular cells of neural crest origin that secrete calcitonin.
What is Schwannoma?
A benign tumor of Schwann cells of neural crest origin.
What is neurofibromatosis type 1?
Mutation of the gene coding for neurofibromin. Neurofibromin down‐regulates p21 ras oncoprotein so that the NF1 gene belongs to the family of tumor‐ suppressor genes, so neural tumors form.
What is the caudal eminence?
It arises from the primitive streak and gives rise to the sacral and coccygeal segments of the spinal cord.
When does myelination of the spinal cord begin? What myelinated the CNS? The PNS?
At 4 months. Oligodendrocytes myelinate the CNS and Schwann cells myelinate the PNS.
What does the adenohypophysis develop from?
Rathke’s pouch
What does the neurohypophysis develop from?
Infundibulum
What is spina bifida?
Spina bifida occurs when the bony vertebral arches fail to form properly, thereby creating a vertebral defect usually in the lumbosacral region. It is due primarily to expectant mothers not taking enough folic acid during pregnancy.
What are the types of spin bifida?
Spina bifida occulta - is evidenced by multiple dimples present on the back of the infant and is the least severe
Spina bifida with meningocele - occurs when the meninges protrude through a vertebral defect and form a sac filled with CSF
Spina bifida with meningomyelocele - occurs when the meninges and spinal cord protrude through a vertebral defect and form a sac filled with CSF
Spina bifida with rachischisis - occurs when the posterior neuropore of the neural tube fails to close during week 4 of development and is the most severe
What are the variations of cranial bifida?
Menigocele - meninges protrude
Meningoencephalocele - meninges and brain protrude
Meningohydroencephalocele - meninges, brain and ventricle protrude
