BMB 1 - Neuroembryology Flashcards
Name the general steps of neurodevelopment.
Neural plate* –> Neural groove –> Neural tube**
(*induced by notochord)
(**neural crest cells are collections of neuroectoderm found lateral to the tube)
The alar plates of the developing neuroepithelium are responsible for ___________ (afferent/efferent) nerve fibers.
The alar plates of the developing neuroepithelium are responsible for afferent nerve fibers.
The basal plates of the developing neuroepithelium are responsible for ___________ (afferent/efferent) nerve fibers.
The basal plates of the developing neuroepithelium are responsible for efferent (afferent/efferent) nerve fibers.
Give the alternate names for each of the following as the three major portions of the developing brain:
Forebrain
Midbrain
Hindbrain
Prosencephalon
Mesencephalon
Rhombencephalon
Name the secondary vesicle(s) which form(s) from the prosencephalon (developing forebrain).
Telencephalon
Diencephalon
Name the secondary vesicle(s) which form(s) from the mesencephalon (developing midbrain).
Mesencephalon
Name the secondary vesicle(s) which form(s) from the rhombencephalon (developing hindbrain).
Metencephalon
Myencephalon
Name the mature structures forming from each of the following secondary vesicles:
Telencephalon
Diencephalon
Name the mature structures forming from each of the following secondary vesicles:
Telencephalon - Cerebrum; lateral ventricles
Diencephalon - Thalamus; third ventricle
Name the mature structures forming from the following secondary vesicle:
Mesencephalon
Name the mature structures forming from each of the following secondary vesicles:
Mesencephalon - Midbrain
Name the mature structures forming from each of the following secondary vesicles:
Metencephalon
Myencephalon
Name the mature structures forming from each of the following secondary vesicles:
Metencephalon - pons; cerebellum
Myencephalon - Medulla oblongata
Where are the three major flexures of the brain/spinal cord?
Midbrain flexure
+
Pontine flexure
+
Cervical flexure
What is the name for the depression between the developing alar and basal plates (which separates motor from sensory neurons)?
The sulcus limitans
Which cranial nerves do not originate in the brainstem?
I, II, XI
The ________ medulla is the portion which makes up part of the fourth ventricle.
The ________ medulla is the portion which more closely resembles the spinal cord.
The open medulla is the portion which makes up part of the fourth ventricle.
The closed medulla is the portion which more closely resembles the spinal cord.
Why is the open medulla flared out?
To make up part of the fourth ventricle
Moving from caudal (inferior) to rostral (superior), describe the mechanism by which the medulla flares out from closed to open (and how the alar and basal plates shift).
Name some of the cranial nuclei associated with the medulla (and thus, which may be affected in medullary lesions).
V, VIII, IX, X, XII
Name some of the cranial nuclei associated with the pons (and thus, which may be affected in pontine lesions).
V, VI, VII, VIII
Name some of the cranial nuclei associated with the midbrain (and thus, which may be affected in midbrain lesions).
II, III, IV, V
True/False.
The cerebellum grows dorsally from alar swellings in the medulla.
False.
The cerebellum grows dorsally from alar swellings in the pons.
In the midbrain, the colliculi are formed from _____ (number) dorsal swellings, and the ______ ________ forms ventrally.
In the midbrain, the colliculi are formed from 4 dorsal swellings (2 superior and 2 inferior), and the crus cerebri forms ventrally.
The sensory ganglia (known as _______ _______ ganglia) ______ (are / are not) synaptic ganglia.
The sensory ganglia (known as dorsal root ganglia) are not synaptic ganglia.
Which cranial nerves carry parasympathetic fibers?
III, VII, IX, X
Cranial nerve III carries parasympathetic fibers from the _____________ nucleus to the _____________ ganglion.
Cranial nerve III carries parasympathetic fibers from the Edinger-Westphal nucleus to the ciliary ganglion.
Cranial nerve VII carries parasympathetic fibers from the __________ nucleus to the __________ and __________ ganglia.
Cranial nerve VII carries parasympathetic fibers from the superior salivatory nucleus to the pterygopalatine and submandibular ganglia.
Cranial nerve IX carries parasympathetic fibers from the _____________ nucleus to the _____________ ganglion.
Cranial nerve IX carries parasympathetic fibers from the inferior salivatory nucleus to the otic ganglion.
What term refers to congenital defects/absence in the skull and brain?
What term refers to a congenital defect of the skull?
Anencephaly;
meroencephaly
A neonate is missing the portion of their brain that connects the two hemispheres.
What is this congenital defect termed?
Corpus callosum agenesis
_____________ refers to a failure of the forebrain to divide completely into right and left cerebral hemispheres.
Holoprosencephaly refers to a failure of the forebrain to divide completely into right and left cerebral hemispheres.
__________ refers to a congenital defect in which brainstem tissue extended into the spinal canal via the foramen magnum (i.e. following the CN XI path).
Chiari malformation refers to a congenital defect in which brainstem tissue extended into the spinal canal via the foramen magnum (i.e. following the CN XI path).
_________ refers to a congenital failure of growth of the brain and neurocranium.
Microcephaly refers to a congenital failure of growth of the brain and neurocranium.
What term refers to a congenital defect in which neurons do not migrate, but still develop into gray matter in either atypical places or in an atypical organizational pattern?
Abnormal histogenesis of the cerebral cortex
What term refers to an intracranial build-up of CSF?
Hydrocephalus
What term refers to cranium bifidum (defect of the cranium) leading to herniation of intracranial contents?
Encephalocele
What form of encephalocele (cranial defect leading to herniation of intracranial contents) only involves herniation of the meninges?
Meningocele
What form of encephalocele (cranial defect leading to herniation of intracranial contents) involves herniation of the meninges and some neural tissues?
Meningoencephaloceles
What form of encephalocele (cranial defect leading to herniation of intracranial contents) involves herniation of the meninges, neural tissues, and part of the ventricular system?
Meningohydroencephaloceles
Issues in CSF resorption in the subarachnoid granulations leads to what form of hydrocephalus?
Communicating;
non-obstructive
(I.e. the ventricles are all patently exchanging CSF.)
Issues in CSF exchange between the ventricles (e.g. due to cerebral aquaduct constriction) leads to what form of hydrocephalus?
Non-communicating;
obstructive
(I.e. the ventricles are not patently exchanging CSF.)
Anencephaly refers to a failure of the rostral _____________ to close.
Anencephaly refers to a failure of the rostral neuropore to close.
Anencephaly refers to an open ________ and an absent ________.
Anencephaly refers to an open calvarium and an absent forebrain.
Spina bifida refers to a failure of the caudal _____________ to close.
Spina bifida refers to a failure of the caudal neuropore to close.
Name the three main forms of spina bifida.
Occulta (most common)
Meningocele
Meningomyelocele
Holoprosencephaly is often related to defects in weeks 5 - 6 of development due to some failure in signalling in what gene?
The SHH gene
Name two syndromes associated with holoprosencephaly.
Fetal alcohol syndrome;
Patau’s syndrome
What will MRI reveal in a neonate with holoprosencephaly?
Monoventricle
+
basal ganglia fusion
What is a Chiari I malformation?
Ectopia (congenital displacement) of cerebellar tonsils
+
spinal cavitations (e.g. syringomyelia)
What is a Chiari II malformation?
Herniation of cerebellar vermis and tonsils (plus resultant hydrocephalus due to aquaductal stenosis)
+
an association with lumbosacral meningomyelocele
When/how do Chiari I malformations typically present?
Adulthood;
as headaches and cerebellar symptoms
