embryology of nervous system - brain development

brain develop begins after

superior neuropore closes at about day 28-9 months

the build a brain

folding and bending of the neural tube into 3 sections, forebrain, midbrain and hindbrain

stage one of brain development

cephalic and cervical flexures bend into 3 regions

3 regions of created by flexures

prosencephalon, mesencephalon, rhombencephalon

cephalic flexure

separates prosencephalon and mesencephalon

cervical flexure

separates rhombencephalon and spinal cord

3 segments of initial brain formation

hollow to become ventricles and part of neural tube segmentation

stage two of brain development

3 segments further divide into 5 segments

prosencephalon (forebrain) turns into

telencephalon and diencephalon

mesencephalon (midbrain) turns into

midbrain

rhombencephalon (hindbrain) turns into

metencephalon and myelencephalon

stage 4 of brain development

rapid expansion of telencephalon to envelope (wrap around) the diencephalon

brain looks like adult structures at about

3 months of development

stage 5 of brain development, from 6-9 months,

cerebral cortex forms gyri, sulci and cerebrellar cortex forms folia

at birth, most neurons are

present

things in anatomy that are wrinkly, are to

increase surface area

telencephalon turns into

hemispheres, lobes of cortex and boundaries of lobes/sulcus (subcortical white and gray matter)

diencephalon turns into

thalamus, hypothalamus, epithalamus (and mamillary bodies)

mesencephalon turns into

midbrain structures

metecephalon

pons, cerebellum, 4th ventricle

myeleconcephalon turns into

medulla oblongata

frontal lobe

motor and personality

parietal lobe

sensory processing

occipital lobe

visual processing

temporal love

auditory processing

insular lobe (limbic lobe)

emotional processing

ventricular system develops from

hollow space in tube of tissue, fills with fluid at about week 12

2 lateral ventricles are within

telecephalon

2 lateral ventricles connect to the 3rd ventricle via

interventricular foramina

3rd ventricle is

between rigth and left diencephalons

3rd ventricle connects to 4th ventricle via

cerebral aqueduct (sits within mesencephalon)

4th ventricle is between

metencephlon and myelencephalon

4th ventricle is continuous with

central canal of spinal cord

CSF is produced in

all ventricles but primarily the lateral ventricles via choroid plecus

CSF flows down to

third ventricle from lateral ventricle, and then into fourth ventricle and either the central canal or drains into subarachnoid space (unidirectional flow)

CSF drains into subarachnoid space through either the

lateral apperture or median apperture and then into venous sinuses

from the subarachnoid space, CSF is drained into

venous sinuses to get rid of it (since we are constantly producing it we have to also get rid of it)

CSF functions

cushion, bouyancy, maintain content of environment around neurons

if the ventricular system is blocked, this will cause

an increase in intracranial pressure resulting in hydrocephalus

hydrocephalus if the brain is not fused (in infants) will cause

an increase in head size

about 80-90% of infants with spina bifida develop

hydrocephalus (meningocele or myelomeningocele)

if the brain is fused with hydrocephalus

growth of ventricles occurs and loss of brain tissue

hydrocephalus can shut down

neuron impulses, causing damage and blocking APs - represents with pain in head and changes in cognition

hydrocephalus treatment

shunt to drain CSF from ventricular system (not a cure - for symptoms)

arnold chiari malformation

deformity of the hindbrain that puts pressure on the brainstem which can lead to hydrocephalus and spina bifida by blocking CSF flow (type 2)