Nervous system development Flashcards
What is the diff b/w ganglion and nucleus?
Ganglion is a collection of cell bodies located outside of CNS (in PNS), while nucleus is located w/in the CNS
What does the brainstem consist of?
Medulla, pons, midbrain
The cerebellum has been largely viewed as a component of the __ sytem, but it has a wide range of functions including __ and __.
The cerebellum has been largely viewed as a component of the motor system, but it has a wide range of functions including learning and memory.
What does the diencephalon consist of?
What about the telencephalon?
Thalamus, Hypothalamus, and epithalamus;
striatum and cerebral cortex
What are the major lobes of the cerebral cortex/neo cortex?
occipital, parietal, temporal, frontal,
also post-central, orbito-frontal, cingulate
The neocortex is a 6-layered structure. In the sensory cortex, inputs from the thalamus largely target cells in what layer?
layer 4
The cerebral hemispheres are interconnected through what 3 major pathways?
Corpus callosum, anterior commissure, and posterior commissure.
In the 3rd wk, inductive factors from where cause the transformation of the surface ectoderm into the neural plate?
Notochord and paraxial mesenchyme.
What is primary neurulation and when does it happen?
Neural folds and a midline neural groove forms in the neural plate in the region of the 4th thru 6th somites. This happens in 4th wk days 22-23
Closure of the neural tube proceeds bidirectionally. When and where is the first closure?
Day 22 in the region of the 5th somite.
NOTE: neural tube closure occurs at up to 5 diff places and abnormal closure of different sites results in neural tube defects.
How is the caudal most portion of the neural tube formed?
When is this completed?
By secondary neurulation of the caudal eminence NOT the neural plate.
Secondary neurulation is completed by wk 8.
Failure of fusion of the neural rube and vertebral arches are defects collectively known as…
Spina bifida
Defects in the closure of the rostral neuropore results in what?
Defects in the closure of the caudal neuropore results in what?
Incomplete development of the brain, calvaria, and/or face;
Different types of spina bifida
What is microencephaly?
A severe form of rostral neural tube defect in which portions of the cranium fail to form w/ resulting defects in brain development.
Typically forebrain, midbrain, and portions of hindbrain fail to form.
Describe the different severities of spina bifida.
- Spina bifida occulta: failure of fusion of vertebral arches (L5 or S1). Indicated by a small dimple w/ a patch of hair
- Spina bifida cystica meningocele: spinal cord in normal position but a meningal sac protrudes thru the defect
- Spina bifida cystica meningomyelocele: spinal cord and nerve roots also protrude thru the vertebral defect
- Spina bifida myeloschisis: most severe form, the neural tube failed to fuse resulting in a flattened neural mass directly exposed to amniotic fluid.
Which neural crest cells migrate just deep to the ectoderm w/in the loose mesoderm?
Cephalic neural crest cells
What is neurofibromatosis?
What is neuroblastoma?
Peripheral nerve tumors;
Tumor of the adrenal medulla, autonomic ganglia
The ___ of the neural plate forms the spinal cord.
Caudal 1/3
What is the ventricular zone?
The neuroepithelial layer adjacent to the central canal (the lumen of the neural tube) and contains precursor cells that give rise to all of the neurons and macroglia of the spinal cord.
The primordial neurons migrate from ___ to ___.
the ventricular zone to the intermediate zone.
What is the sulcus limitans?
Where does it extend through?
It is a shallow longitudinal groove in the lateral walls of the neural tube that separate the developing gray matter into a dorsal alar plate and ventral basal plate.
The sulcus limitans extends the length of the spinal cord through the mesencephalon (midbrain).
Neuronal cell bodies in the alar plate form:
nuclei that constitute the dorsal gray matter that receive and relay input from afferent (sensory, somatic, and visceral) neurons
Neuronal cell bodies in the basal plate form:
The ventral gray matter or efferent neurons. Axons of these neurons project motor fibers to skeletal m. and form the ventral roots of the spinal n.’s
Describe how ventral and dorsal roots of the spinal nerves come about.
The ventral roots are motor fibers that extend from the basal plate. The dorsal roots arise from the developing spinal ganglia and join w/ the ventral roots.
The spinal n.’s branch to form the dorsal and ventral primary rami.