When does the neural plate develop?
week 3
What does the elevation of the neural plate create?
Neural Folds
When do the neural folds close?
Cranial neuropose closes day 25
Caudal neuropose closes day 27
What are the three primary vesicles of the brain?
1) Prosencephalon (Forebrain)
2) Mesencephalon (Midbrain)
3) Rhombencephalon (Hindbrain)
What does the Prosencephalon divide into?
What does the Rhombencephalon divide into?
What does the neural crest give rise to?
1) Sensory Ganglia of Spinal Nerves (Dorsal root Ganglion)
2) Postganglionic Neurons of the ANS
3) Schwann Cells
4) Melanocytes
What does the neural tube form?
Brain and Spinal Cord
What is the mantle?
Forms grey matter in spinal cord
What are the parts of the mantle?
1) Basal Plate - Ventral; Motor
2) Alar Plate - Dorsal Sensory
3) Sulcus Limitans separates basal and alar plates
4) Roof plate and floor plate - Inducers of mesenchyme (No Neurons)
What becomes the white layer?
Marginal Layer
Nerve fibers rom developing neurons of mantle
Fibers from the neurons of basal plate form what?
Ventral Root - Week 4
Fibers from the dorsal root ganglia grow to form what?
Dorsal Root
Fibers from dorsal root ganglia grow distally and join ventral nerve roots to form what?
Spinal Nerve
The dorsal root ganglia comes from what origin?
Neural crest
What forms the Cauda Equina?
Results from differential growth of spinal cord and vertebral column.
What is spinal bifida cystica?
Neural tissue or meninges are exposed
What are the three flexures?
1) Mesencephalic - Cranial Flexure "Mid Brain"
2) Cervical - Brain stem and cord
3) Pontine - Will fold on itself
What happens to the alar plates in the Myelencephalon of the Rhombencephalon?
The alar plates move to lateral position
What do the alar and basal plates develop into in the Myelencephalon?
Sensory and motor areas subdivivded into columns (GSA, SVA, GVA, etc...)
Alar - afferent
Basal - Efferent
What structures do the alar and basal neurons supply in the Myelencephalon?
Supply the structures of the head and neck. Some are associated with CN X (Vagus) that innervates visceral.
What is the roof plate of the Myelencephalon made of?
Ependymal cells covered by vascular mesenchyme
What are Ependymal cells?
They work with the vascular to produce CSF
What happens in the basal plate of the Metencephalon?
Marginal layer forms bridge between cerebral cortex, cerebellar cortex, and the cord called the PONS.
It is the tracks that connects them all together.
What does the alar plates of the Metencephalon become?
Cerebellum - Coordinating center for movement
What do the basal plates of the mesencephalon become?
motor nuclei innervating structures of the eye
What do the alar plates of the mesencephalon become?
Relays for visual and auditory reflexes (Anterior and Posterior Colliculi)
What are the two parts of the Prosencephalon?
1) Diencephalon
2) Telencephalon
What does the roof plate of the Diencephalon become?
Choroid plexus of 3rd ventricle and pineal gland
What does the alar plate of the Diencephalon become?
Thalamus, hypothalamus, Epithalamus, and posterior lobe of pituitary gland.
What happens in the telencephalon?
Cerebral hemispheres appear as evagination of lateral wall of Prosencephalon in week 5.
What appears as the telencephalon continues to develop?
Gyri (Folds) and sulci (grooves)
What is the Lamina terminalis?
Site of closure of anterior neuropore.
It is a site of commiccures (connections between right and left sides)
What are the different commissures of the Lamina terminalis?
1) Olfactory (Anterior) Commissure - Connects left and right Olfactory senses
2) Hippocampal
3) Corpus Callosum - Connects left and right cerebral cortex
4) Optic Chiasm
What is anencephaly?
failure of closure of cephalic portion of neural tube results in degeneration of neural tissue
What is hydrocephalus?
Abnormal accumulation of cerebrospinal fluid due to obstruction of drainage into subarachnoid space
What is arnold-chiari malformation?
Herniation of cerebellar tissue through foramen magnum
Frequently associated with spina bifida cycstica
Name all 12 of the cranial nerves.
Where are the preganglionic sympathetic neurons derived from embryonically?
Lateral Plate Basal plates
Where are the postganglionic sympathetic neurons derived from embryonically?
Neural Crest Cells
Where does the Adrenal Medulla from embryonically?
Neural Crest Cells to form modified sympathetic ganglion
Where does the Adrenal Cortex from embryonically?
Mesoderm
What are the somatic efferent cranial nerves, where do they arrise and what do they innervate?
CN III, IV, VI, and XII
Arrise from brain stem
Innervate muscles derived from preotic and occipital myotomes
What are the nerves of the pharyngeal archeswhere do they arrise and what do they innervate?
CN, V, VII, IX, and X
Arise from nuclei of brain stem
Contain sensory and motor components
What are the special sensory nerves, where do they arrise and what do they innervate?
CN I, II, and VII