Neural Tube Development - Spinal Cord

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Neural tube closure defect at caudal end?

Spina bifida

Neural tube closure defect at rostral end?

Anencephaly

What structure separates motor and sensory regions in the spinal cord?

Sulcus limitans

Neural crest derivatives in the spinal cord?

Sensory neurons, Schwann cells, satellite cells.

Basal plate gives rise to?

Motor neurons located in the anterior horn.

Alar plate gives rise to?

Sensory neurons located in the posterior horn.

What forms the central canal of the spinal cord?

Neural tube lumen.

What structure anchors the spinal cord to the coccyx?

Filum terminale.

Spinal cord ends at what level in adults?

L1.

Spinal nerve roots below L1 form what structure?

Cauda equina.

Why is the cauda equina a site for lumbar puncture?

Ends at S2, avoiding spinal cord injury.

Three primary vesicles of the brain?

Forebrain, Midbrain, Hindbrain.

Five secondary vesicles?

Telencephalon, Diencephalon, Mesencephalon, Metencephalon, Myelencephalon.

What forms from the telencephalon?

Cerebral hemispheres and lateral ventricles.

What forms from the diencephalon?

Thalamus, hypothalamus, and third ventricle.

What structure connects the lateral and third ventricles?

Interventricular foramina.

Which CN nuclei are in the medulla?

Cranial nerves IX, X, XI, XII.

Which CN nuclei are in the pons?

Cranial nerves V, VI, VII, VIII.

Which CN nuclei are in the midbrain?

Cranial nerves III and IV.

Superior colliculus function?

Responsible for visual reflexes.

Inferior colliculus function?

Responsible for auditory reflexes.

What structure allows CSF to enter the subarachnoid space?

Foramina of Luschka & Magendie.

Most common neural tube defect?

Spina bifida.

What supplement prevents neural tube defects?

Folic acid (400 mcg/day).

Failure of aqueductal drainage leads to?

Hydrocephalus.

Chiari malformation is associated with what condition?

Myelomeningocele.

Neural tube dilates at the cephalic end to form?

Forebrain, midbrain, hindbrain.

What forms the spinal cord?

Caudal neural tube elongation.

What type of epithelium lines the neural tube?

Pseudostratified columnar epithelium (matrix cells).

What is the function of the ventricular zone?

Site of neural progenitor cell division.

What forms gray matter?

Neuroblasts migrating to the intermediate zone.

What forms white matter?

Myelinated nerve fibers from neuroblasts in the marginal zone.

Astrocytes and oligodendrocytes arise from?

Matrix cells.

Microglia arise from?

Mesenchyme and migrate with blood vessels.

What cells line the central canal?

Ependymal cells.

What does the basal plate develop into?

Motor neurons located in the anterior horn.

What does the alar plate develop into?

Sensory neurons located in the posterior horn.

What structure separates motor and sensory regions?

Sulcus limitans.

Basal plate expansion forms what structure?

Anterior median fissure.

Alar plate expansion leads to?

Compression of the posterior neural tube lumen.

What structure forms from posterior tube wall fusion?

Posterior median septum.

What does the neural tube lumen become?

Central canal.

Medial motor neuron group innervates?

Skeletal muscles (somatic motor neurons).

Lateral motor neuron group gives rise to?

Autonomic preganglionic fibers.

Sympathetic preganglionic neurons originate from what levels?

T1–L2/L3.

Sensory neuron cell bodies originate from?

Neural crest cells.

What forms the posterior root of the spinal nerve?

Central process of sensory neurons.

What structure surrounds unipolar neurons in the posterior root ganglion?

Capsular (satellite) cells.

Sensory neuroblast processes ascend or descend in what spinal cord region?

Marginal zone (white matter).

Some sensory processes cross via what structure?

Floor plate.

Meninges develop from which embryonic structure?

Mesenchyme (sclerotome).

What forms within the mesenchyme and fills with CSF?

Subarachnoid space.

What spinal structure forms from mesenchymal condensations?

Ligamentum denticulatum.

At birth, the spinal cord ends at what vertebral level?

L3.

In adults, the spinal cord ends at what vertebral level?

L1 (lower border).

What forms from descending spinal nerve roots below L1?

Cauda equina.

What anchors the spinal cord to the coccyx?

Filum terminale (thin pia mater strand).

What structure extends to S2 and is a site for lumbar puncture?

Cauda equina.

Spinal cord enlargements occur due to?

Limb bud development (4th month).

Which spinal regions show enlargement?

Cervical and lumbar regions.

What are the three primary vesicles of the brain?

Forebrain, Midbrain, Hindbrain.

Forebrain vesicle develops into what?

Prosencephalon.

Midbrain vesicle develops into what?

Mesencephalon.

Hindbrain vesicle develops into what?

Rhombencephalon.

What does the telencephalon form?

Cerebral hemispheres.

What does the diencephalon form?

Optic vesicles & third ventricle.

What does the metencephalon form?

Pons & cerebellum.

What does the myelencephalon form?

Medulla oblongata.

Lateral ventricles are found in what brain region?

Telencephalon (Cerebral hemispheres).

The third ventricle is located in which brain division?

Diencephalon.

What connects the third and fourth ventricles?

Cerebral aqueduct (Aqueduct of Sylvius).

Where is CSF initially produced?

Choroid plexus.

What allows CSF to enter the subarachnoid space?

Foramina of Luschka & Magendie.

How is the early neural tube shaped?

Straight.

What causes the neural tube to curve?

Head & tail folds.

Motor nuclei of CN IX, X, XI, XII arise from?

Basal plate of the medulla.

What sensory structures develop from the alar plate of the medulla?

Sensory nuclei of CN V, VIII, IX, X + gracile & cuneate nuclei.

What is the function of the olivary nuclei?

Relays motor information to the cerebellum.

What structure forms from the roof plate and produces CSF?

Choroid plexus.

Descending axons from the motor cortex form what structure?

Pyramids.

Motor nuclei of CN V, VI, VII originate from?

Basal plate of the pons.

What sensory nuclei form in the pons?

CN V, CN VII, Vestibular & Cochlear nuclei of CN VIII.

What structure forms from transverse axons of the pontine nuclei?

Middle cerebellar peduncle.

The cerebellum forms from which embryonic structure?

Posterior part of the alar plates of the metencephalon.

What embryonic structure gives rise to the cerebellum?

Rhombic lips.

When do the vermis and cerebellar hemispheres appear?

12th week.

When do cerebellar fissures form?

4th month.

What deep cerebellar nucleus is formed by neuroblasts?

Dentate nucleus.

Which cerebellar peduncle connects the cerebellum to the midbrain & forebrain?

Superior cerebellar peduncle.

Which cerebellar peduncle carries sensory input from the spinal cord?

Inferior cerebellar peduncle.

The midbrain develops from which vesicle?

Midbrain vesicle.

The narrowing of the midbrain cavity forms what structure?

Cerebral aqueduct.

Motor neurons of CN III & CN IV arise from?

Basal plate of the midbrain.

What structure in the midbrain controls movement?

Substantia nigra & red nucleus.

What forms the basis pedunculi?

Marginal zone expansion (contains corticospinal, corticobulbar, corticopontine tracts).

What midbrain structure is responsible for visual reflexes?

Superior colliculi.

What midbrain structure is responsible for auditory reflexes?

Inferior colliculi.

Which cranial nerve is the only one that exits posteriorly and decussates?

CN IV (Trochlear nerve).

Where do CN III fibers emerge?

Anteriorly between the cerebral peduncles.

What forms from the forebrain vesicle?

Telencephalon & Diencephalon.