9 Development of the Brain - M Flashcards
What is the order of neurulation?
neural plate –> neural groove –> neural tube
What structure induces neurulation?
the notochord
The caudal 1/3 of the neural plate develops in what?
future spinal cord
What are the last two parts of the neural groove to close during neurulation?
Cranial & caudal neuropores
which neuropore, cranial or caudal, closes last?
caudal neuropore (Day 27)
Where does secondary neurulation occur?
the sacrum and coccyx
What occurs during secondary neurulation?
the caudal eminence fuses with the caudal portion of the neural tube
What cells are derived from neuroectoderm?
neurons of the CNS, glial cells, ependyma
What type of glial cell is not derived from neuroectoderm?
microglial cells (macrophages); derived from mesenchymal cells
NCCs give rise to which part of the nervous system?
the peripheral NS including all ganglia outside of the CNS
The 4th pair of somites demarks what?
Marks which part of the NT will form the brain and which will form the spinal cord
What are the 3 divisions of the NT that will develop into the brain?
Prosencephalon/forebrain, mesencephalon/midbrain, rhombencephalon/hindbrain
The prosencephalon/forebrain divides to give rise to what 2 brain regions?
Telencephalon (cerebrum) and diencephalon
The mesencephalon/midbrain gives rise to what brain region?
midbrain
The rhombencephalon/hindbrain gives rise divides into what brain structures?
metencephalon (pons) and myelencephalon (medulla)
When does the telencephalon begin to divide into two hemispheres?
by the 5th wk
What flexure is found between the midbrain & hindbrain?
cephalic flexure
What flexure is found between the hindbrain and the cervical region?
cervical flexure
During what timeframe are the basal ganglia developing?
6th-32nd wks
What structures are derived from the telencephalon? (6 major structures)
cerebral cortex, subcortical white matter, olfactory bulb/tract, basal ganglia, amygdala, hippocampus
What structures are derived from the diencephalon? (4)
thalamus, hypothalamus, epithalamus (pineal gland), and eyes (optic nerve)
Which 2 cranial nerves are derived from the midbrain?
oculomotor and trochlear
What structures are derived from the midbrain?
cerebral peduncles, tectum, tegmentum, substania nigra, and periaquedutal gray matter
What are the structures found in the tectum?
superior/inferior colliculi
What is holoprosencephaly (HPE)?
incomplete separation of the cerebral hemispheres (errors during 5th wk)
What other malformations are associated with HPE?
facial malformations (cleft lip/palate), orbital hypotelorism
What two structures give rise to the pituitary gland?
1st PA ectoderm (Rathke’s pouch) and neuroectoderm from forebrain (diencephalon)
the 1st PA ectoderm gives rise to which part of the pituitary gland?
anterior lobe (adenohypophysis)
Forebrain neuroectoderm gives rise to which part of the pituitary gland?
posterior lobe (neurohypophysis)
What separates the developing spinal cord into anterior and posterior plates?
the sulcus limitans
What are the 2 plates of the developing spinal cord?
alar plate (posterior), basal plate (anterior)
What hormone signs for the rostral development of the alar plate?
BMP (review from MSK)
Why does the alar plate derivatives ascend in the spinal cord?
because it gives rise to the sensory tracts
Why does the basal plate derivatives descend in the spinal tract?
because it gives rise to the motor tracts
What are the 3 zones of the developing spinal cord?
- ventricular zone
- intermediate zone
- marginal zone
What cells are found in the ventricular zone of the developing spinal cord?
germinal/ventricular cell –> ependymoblast –> epedymal/choroid plexus cells in the ventricular zone
What cells are found in the intermediate/mantle zone of the developing spinal cord?
cell bodies (gray matter) of neurons and glial cells
What cells are found in the marginal zone of the developing spinal cord?
axons of primary afferents/efferents and oligodendrocytes
Which nuclei in the myelencephalon (medulla) are derived from the basal plate?
- hypoglossal nucleus
- dorsal motor vagal nucleus
- nucleus ambiguus
Which nuclei of the myelencephalon are derived from the alar plate?
- vestibular nuclei
- cochlear nuclei
- soliatary nuclei
- inferior olive
- spinal trigeminal nuclei and tracts
What nuclei of the metencephalon (pons) are derived from the basal plate?
- motor nuclei for CN 5, 6 and 7
- superior salivary nucules (CN 7)
What nuclei of the metencephalon (pons) are derived from the alar plate?
- cerebellar anlage
- cochlear nuclei
- vestibular nuclei
- solitary nucleus
- pontine nuclei
- *
What nuclei of the mesencephalon are derived from the basal plate?
- red nuclei
- oculomotor nuclei
- edinger-westphal nuclei
What nuclei of the mesencephalon are derived from the alar plate?
superior and inferior colliculi
What is syringomyelia?
A cyst that occurs in the central canal and results in the accumulation of CSF in the cervical region
syringomyelia is high associated with what type of congenital malformation?
Chiari type 1 malformations
What type of gait patterns are associated with spasitc cerebral palsy
toe walking and scissor gait
Described the types of movements associated with athetoid cerebral palsy?
slow writhing movements of extremities and/or trunk (serpent type movements)
What type of movements are associated with ataxic cerebral palsy?
uncoordinated, weakness, and shaking during voluntary movements; damage to cerebellum
Arnold-Chiari malformations are due to errors in the development of what part of the brain?
hindbrain
Chiari type 1 malformations are the result of what developmental error?
herniation of cerebellar tonsil through the foramen magnum
Chiari type 1 malformations are highly associated with what other pathology?
syringomyelia
What are some signs of Chiari type 1 malformations?
- head/neck pain
- lower cranial nerve problems (CN 5-12)
What pathology doe this patient have?
Chiari type 1 malformation; may also have syringomyelia
How are arnold-Chiari type 2 malformations described?
Herniation of medulla and cerebellum through the foramen magnum
What pathology highly associated with Arnold-Chiari type 2 malformations?
spina bifida (3 types so look them up if you don’t remember)
When are Arnold-Chiari malformations typically diagnosed?
during fetal development by MRI (look at brainstem & lumbar region)
What pathology is a result of a large cyst in the posterior fossa that is continuous with the 4th ventricle
Dandy-Walker malformation/cyst
What foramina can be affected by a Dandy-Walker cyst?
Foramina of Luschka and Magendie
What brain structure can be affected by a Dandy-Walker cyst?
Cerebellum
What is the purpose of brain gyri and sulci?
Increases the amount of brain matter that can develop in the cranial vault; also decreases the length of axons & allows for faster processing speeds
What is lissencephaly or agyria?
SMOOTH BRAIN d/t incomplete or failure of neuronal migration during 12-24th wks
What cells are derived from the NCC regarding the PNS
- dorsal root ganglia
- sensory ganglia of cranial nerves
- otic, pterygopalatine, ciliary, mandibular
- Schwann cells
- sympathetic ganglia
When during development does myelination occur?
late fetal period through first postnatal year
What are the 4 types of spina bifida?
- Spina Bifida occulta
- meningocele
- meningomyelocele
- myelocele/myeloschisis
What is anencephaly?
Neural tube failure that results in the absence of parts of the brain, skull, and scalp
What is encephalocele
- incomplete closure that results in sac-like protrusions from the head
- may or may not contain herniated of brain tissue
What spinal cord defect does this patient have? what other malformation may this patient have?
Patient has spina bifidia occulta, may also have Chiari type 1 malformation
What is this? What else might the patient have?
myelomeningocele; Chiari type 1 malformation
What part of the neural plate do the NCCs develop from?
Neural crest
The crainal 2/3rds of the neural plate develops into what?
the 4th pair of somites = future brain
