Embryology Wk 4 Nervous System Development

The three main regions of the nervous system:

CNS, PNS, ANS

When does development of the nervous system begin?

In the third week.

The neural tube differentiates into what?

The CNS

The PNS and ANS are mostly formed from what cells?

Neural crest cells.

T/F Closure of the neuropores occurs BEFORE the establishment of vascular circulation for the neural tube

FALSE, the close of the neuropores COINCIDES with the establishment of a vascular circulation for the neural tube.

In neural tube formation, does the cranial or caudal end seal first?

The cranial end seals first.

What are the three zones that arise during development of the spinal cord?

Ventricular, marginal, and intermediate zone.

What (cells) does the ventricular zone give rise to?

All neurons and macroglia cells.

What does the marginal zone give rise to?

White matter of the spinal cord, axons grow into it from nerve cell bodies.

What does the intermediate zone give rise to?

The mantle layer, and it’s where neuroblasts become neurons.

What are glioblasts?

Supporting cells of the CNS that migrate from ventricular to intermediate and marginal zones.

What are microglia derived from?

The mesenchymal cells, and they originate in the bone marrow.

What do spinal ganglia develop from? Where do they go?

They develop from NCCs, they go to sensory endings in somatic or visceral structures.

What are meninges? What does the external layer form? The internal layer?

The meninges are membranes that cover the spinal lord. The external layer forms dura mater, the internal layer forms pia mater and arachnoid mater.

When does the CSF (cerebral spinal fluid) begin to form?

During the 5th week of life.

Which are myelinated first? Sensory roots, or motor roots?

Motor!

What is the name of the structure that indicates the region of closure of the caudal neuropore, when does it occur?

Sacral dimple, around the end of wk4

When does brain development begin around? What’s happening at that time?

Wk 3. The neural plate and tube are forming from the neuroectoderm.

What are the 3 primary brain vesicles?

Forebrain, midbrain, hindbrain.

What is the prosencephalon?

Forebrain

What is the mesencephalon?

Midbrain

What is the rhombencephalon?

Hindbrain

Which part of the brain do primordial retinae and optic nerves develop from?

Forebrain

TF? The midbrain does not divide into sub categories.

True

T/F The brain develops originally as a folded structure.

False, it is smooth brain, then wrinklyyy

The forebrain is divided into the?

Telencephalon and diencephalon

The telencephalon forms?

The primordia of the cerebral hemispheres, as well as the falx.

The falx is?

The line that splits the brain in half.

The Diencephalon forms what (3ish) things?

1) The thalamus, hypothalamus, and epithalamus. 2) The corpus callosum 3)The pituitary gland

What does the choroid plexus arise from? What does it do?

It arises from a sheet of pia mater that invaginates the 4th ventricle. It secretes ventricular fluid that becomes the CSF

What does the PNS mostly develop from?

The neural crest

From the basal plates of the developing spinal cord, ___ nerve fibers arise that form themselves into bundles to innervate ___

Motor, muscle groups

How many pairs of cranial nerves form?

12

What are the 3 groups of cranial nerves

1) Somatic efferent cranial nerves, 2)Nerves of pharyngeal arches, 3) Special sensory nerves

The parasympathetic (Craniosacral) nervous system activates…

Rest and digest

The sympathetic nervous system (Thoracolumbnar) activates

Flight or fight