Which neuropore is located at the tail end of the neural tube?
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Caudal neuropore.
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Which neuropore is located at the tail end of the neural tube?
Caudal neuropore.
What is Spina Bifida occulta?
A form of Neural Tube Defect characterized by incomplete fusion of vertebral arches.
What is seen in spina bifida with meningocele?
A bulge over the defect containing meninges and cerebrospinal fluid (CSF) in the subarachnoid space.
What is the significance of the tuft of hair in spina bifida occulta?
It may be present over the bony defect, indicating the condition.
What are the potential causes of neural tube defects during pregnancy?
Hypervitaminosus A and folic acid deficiency.
What is the 'Forebrain prominence' in the image?
The forebrain prominence is an early developmental structure that will give rise to the forebrain, including the cerebral hemispheres.
What shape does the lumen of the neural tube become as a result of the thickening of the mantle zone?
Rhomboidal.
What is spina bifida?
A condition due to the failure of fusion of the two vertebral arches, more common in the lumbosacral region.
What forms the central canal of the spinal cord?
The cavity of the neural tube.
What is the significance of the 'Midbrain' in the diagram?
The midbrain is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation.
Why is ingestion of preconception folic acid not easy?
Less than 50% of pregnancies are planned.
When is folic acid protective against neural tube defects (NTDs)?
When ingested in the periconception period.
On which day does the rostral neuropore close?
The 25th day.
On which day does the caudal neuropore close?
The 27th day.
What is the 'Heart prominence' in the image?
The heart prominence is an early developmental structure indicating the location of the developing heart.
Which zone in the wall of the neural tube is closest to the central canal?
Ventricular zone.
What is the primary defect in spina bifida occulta?
There is a defect in the vertebral arch.
Why do spinal nerves run more obliquely downwards and laterally?
Because of the differential growth between the vertebral column and the spinal cord.
What forms the white matter in the spinal cord?
The marginal zone.
Where is the intermediate zone (mantle layer) located?
Between the ventricular zone and the marginal zone.
What structure is formed by the fusion of neural folds?
The neural tube.
Why is it challenging to prevent NTDs with folic acid?
NTDs occur 26 days post-fertilization, often before many women know they are pregnant.
What is the significance of the somites in the image?
Somites are blocks of mesoderm that segment along the head-to-tail axis of the developing embryo and give rise to important structures such as vertebrae and skeletal muscle.
Which drugs are known to be folate antagonists and can contribute to neural tube defects?
Valproic acid (sodium valproate, e.g., Depakine) and carbamazepine.
What conditions can result from neural tube defects caused by hypervitaminosus A and folic acid deficiency?
Exencephaly or (mero)anencephaly with spina bifida.
What is the 'Amnion' in the image?
The amnion is a membrane that surrounds and protects the developing embryo, forming the amniotic sac.
What is the role of the back muscles in the context of spina bifida?
They are part of the structures affected by the defect in the vertebral arch.
What is anencephaly?
Anencephaly is one of the most common neural tube defects (NTDs) where no survival is possible.
What lines the neural tube during spinal cord development?
A thick layer of neuroepithelium.
What forms the ependymal lining of the central canal?
The ependymal zone.
Into what do cells in the intermediate zone differentiate?
Neuroblasts, which form neurons.
What are the two ends of the neural tube called?
Rostral neuropore and caudal neuropore.
What additional mal-development occurs in Neural Tube Defects (NTDs)?
Mal-development of mesoderm, which forms skeletal and muscular structures that cover neural structures.
What is the structure labeled as 'Neural groove' in the image?
The neural groove is a structure that forms during the early stages of neural tube development.
What does the subarachnoid space contain?
Cerebrospinal fluid (CSF).
What is seen over the defect in spina bifida with meningomyelocele?
A bulge containing meninges, cord, and nerves.
What is seen over the bony defect in spina bifida with myeloschisis?
An open spinal cord seen as a mass of neural tissue.
What is the subarachnoid space?
The space between the arachnoid mater and the pia mater, containing cerebrospinal fluid.
Where is the marginal zone located in relation to the ventricular zone?
Superficial to the ventricular zone.
What is the cauda equina?
A bundle of spinal nerve roots caudal to the lower end of the spinal cord (conus medullaris) that resembles a pony tail.
From which part of the neural tube does the spinal cord develop?
The narrow caudal part of the neural tube.
What is a sacral spinal sinus?
A skin dimple in the mid sacral region connected to the dura by a fibrous strand. It indicates the site of closure of the posterior (caudal) neuropore.
What structure indicates the line of regression of the spinal cord?
The filum terminale.
Which neuropore is located at the head end of the neural tube?
Rostral neuropore.
How do Neural Tube Defects (NTDs) vary in severity?
They range from simple Spina Bifida occulta to severe conditions like Anencephaly.
What are the three zones in the wall of the neural tube?
Marginal zone, Mantle zone, Ventricular zone.
What is the condition where the spinal cord is seen as a mass of neural tissue over the bony defect?
Spina bifida with myeloschisis.
What are the ventral structures formed in the neural tube called?
Basal plates.
What is the 'Cervical flexure'?
A bend in the neural tube that occurs between the hindbrain and the spinal cord.
What is the 'Dorsal root ganglion'?
A cluster of nerve cell bodies in the dorsal root of a spinal nerve.
What does the 'Hindbrain' develop into?
The hindbrain develops into structures such as the cerebellum, pons, and medulla oblongata.
Where is the conus medullaris located in an adult?
At the level of L1.
What is the end of the dural sac in an adult?
At the level of S1.
What is a characteristic feature of spina bifida occulta?
No bulge over the bony defect; a tuft of hairs may be present.
What is the 'Yolk stalk' in the image?
The yolk stalk is a structure that connects the yolk sac to the midgut of the developing embryo.
What is the dura mater?
The outermost layer of the meninges surrounding the brain and spinal cord.
What structure is labeled as the 'Forebrain' in the diagram?
The anterior part of the brain, located at the front.
What is the 'Midbrain flexure'?
A bend in the neural tube that occurs in the midbrain region during development.
What is the significance of the differential growth between the vertebral column and the spinal cord?
It causes the spinal nerves to course obliquely downward to reach their corresponding intervertebral foramina.
What is depicted in the cross section of the trilaminar embryonic disc?
The formation of the neural tube from the neural plate, including structures like the neural groove, neural fold, neural crest, and notochord.
What are some teratogens that can contribute to neural tube defects?
Hyperthermia, sulfas, antihistaminics, and nutritional deficiencies.
How many days post-fertilization do neural tube defects (NTDs) occur?
26 days post-fertilization.
What structure is unfused in spina bifida?
The vertebral arch.
What is the 'Neural tube' in the image?
The neural tube is the precursor to the central nervous system, which includes the brain and spinal cord.
What parts of the brain are affected in anencephaly?
The cerebrum is exposed, open, and undeveloped, while the brain stem and its functions are preserved.
Are there any neurological deficiencies in spina bifida occulta?
No, there are no neurological deficiencies.
What is the structure at the top of the neural tube called?
Roof plate.
What forms the ventral and lateral grey horns and what is their function?
The basal lamina forms the ventral and lateral grey horns, which are motor.
Where is the conus medullaris located at birth?
At the level of L3.
What is the primary defect in Neural Tube Defects (NTDs)?
Failure of neuropore to close or neural folds to fuse in midline and form neural tube (Neuroectoderm).
What are the two types of spina bifida shown in the image?
With meningomyelocele and with myeloschisis.
Which zone in the wall of the neural tube is also known as the presumptive gray matter?
Mantle zone.
Which zone in the wall of the neural tube is also known as the presumptive white matter?
Marginal zone.
What physical sign may be present in spina bifida occulta?
A tuft of hair may be present.
What zone does the neuroepithelium form in the neural tube?
The ventricular zone.
What is the filum terminale?
A long fibrous strand of pia mater extending between the conus medullaris and the coccyx, indicating the line of regression of the spinal cord.
How do the spinal nerves course during the 8th week of development?
They course horizontally laterally through their corresponding intervertebral foramina.
What happens to the vertebral column compared to the spinal cord during development?
The vertebral column elongates faster than the spinal cord, resulting in differential growth.
What is the filum terminale?
A fibrous extension of the pia mater that anchors the spinal cord to the coccyx.
What structure gives rise to the brain and spinal cord?
The neural tube.
What is Anencephaly?
A severe form of Neural Tube Defect where there are wide openings in cranial and vertebrae bones and absence of brain, nerves, and meninges.
What is the 'Connecting stalk' in the image?
The connecting stalk is a structure that connects the developing embryo to the placenta.
What are the key physical characteristics of anencephaly?
Absence of calvarium, posterior bone elements, and deficiency in procencephalus.
How many regions does the mantle zone thicken in the wall of the neural tube?
Four regions.
What is spina bifida occulta?
A form of spina bifida that is not visible externally. A skin dimple or a tuft of hair may be seen over it, and it has no neurological symptoms.
At what level do the dural and arachnoid sheaths end?
At the S2 level.
What is the structure at the bottom of the neural tube called?
Floor plate.
What forms the dorsal grey horn and what is its function?
The alar lamina forms the dorsal grey horn, which is sensory.
Where is the 'Optic vesicle' located in the diagram?
Near the forebrain, it is an early structure that will develop into the eyes.
What is the dura mater?
A tough membrane that surrounds the spinal cord.
What structures are contained in the bulge seen in spina bifida with meningomyelocele?
Meninges, cord, and nerves.
What is the role of the spinal ganglion?
It contains the cell bodies of sensory neurons.
What is the membranous sac in spina bifida with meningomyelocele?
A sac that contains the displaced spinal cord, meninges, and nerves.
Is survival possible for individuals with anencephaly?
No, survival is not possible for individuals with anencephaly.
What forms the grey matter in the spinal cord?
The mantle zone.
What structures are found in the lateral walls of the neural tube?
Sulcus limitans.
What are the key structures involved in neural tube formation?
Neural groove, neural fold, neural crest, neural tube, surface ectoderm, paraxial mesoderm, notochord, yolk sac.
What are the dorsal structures formed in the neural tube called?
Alar plates.
What happens to primitive neuroepithelial cells in the ventricular zone?
They multiply and newly formed cells move out to form the intermediate zone (mantle layer).
At what level are the lower end of the spinal cord and the vertebral column during the 8th week of development?
They are at the same level.
What induces the ectodermal layer to form the neural plate?
The underlying notochord and paraxial mesoderm.
From which structure is the neural tube formed?
The neural plate.
What is the significance of the neural crest in neural tube formation?
The neural crest cells migrate to form various structures in the body.
What is the role of the notochord in neural tube formation?
It induces the ectodermal layer to form the neural plate.
