BMB 1 - Neuroembryology

Question 1

Name the general steps of neurodevelopment.

Answer 1

Neural plate* –> Neural groove –> Neural tube**

(*induced by notochord)

(**neural crest cells are collections of neuroectoderm found lateral to the tube)

Question 2

The alar plates of the developing neuroepithelium are responsible for ___________ (afferent/efferent) nerve fibers.

Answer 2

The alar plates of the developing neuroepithelium are responsible for afferent nerve fibers.

Question 3

The basal plates of the developing neuroepithelium are responsible for ___________ (afferent/efferent) nerve fibers.

Answer 3

The basal plates of the developing neuroepithelium are responsible for efferent (afferent/efferent) nerve fibers.

Question 4

Give the alternate names for each of the following as the three major portions of the developing brain:

Forebrain

Midbrain

Hindbrain

Answer 4

Prosencephalon

Mesencephalon

Rhombencephalon

Question 5

Name the secondary vesicle(s) which form(s) from the prosencephalon (developing forebrain).

Answer 5

Telencephalon

Diencephalon

Question 6

Name the secondary vesicle(s) which form(s) from the mesencephalon (developing midbrain).

Answer 6

Mesencephalon

Question 7

Name the secondary vesicle(s) which form(s) from the rhombencephalon (developing hindbrain).

Answer 7

Metencephalon

Myencephalon

Question 8

Name the mature structures forming from each of the following secondary vesicles:

Telencephalon

Diencephalon

Answer 8

Name the mature structures forming from each of the following secondary vesicles:

Telencephalon - Cerebrum; lateral ventricles

Diencephalon - Thalamus; third ventricle

Question 9

Name the mature structures forming from the following secondary vesicle:

Mesencephalon

Answer 9

Name the mature structures forming from each of the following secondary vesicles:

Mesencephalon - Midbrain

Question 10

Name the mature structures forming from each of the following secondary vesicles:

Metencephalon

Myencephalon

Answer 10

Name the mature structures forming from each of the following secondary vesicles:

Metencephalon - pons; cerebellum

Myencephalon - Medulla oblongata

Question 11

Where are the three major flexures of the brain/spinal cord?

Answer 11

Midbrain flexure

+

Pontine flexure

+

Cervical flexure

Question 12

What is the name for the depression between the developing alar and basal plates (which separates motor from sensory neurons)?

Answer 12

The sulcus limitans

Question 13

Which cranial nerves do not originate in the brainstem?

Answer 13

I, II, XI

Question 14

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.

Answer 14

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.

Question 15

Why is the open medulla flared out?

Answer 15

To make up part of the fourth ventricle

Question 16

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).

Answer 16

Question 17

Name some of the cranial nuclei associated with the medulla (and thus, which may be affected in medullary lesions).

Answer 17

V, VIII, IX, X, XII

Question 18

Name some of the cranial nuclei associated with the pons (and thus, which may be affected in pontine lesions).

Answer 18

V, VI, VII, VIII

Question 19

Name some of the cranial nuclei associated with the midbrain (and thus, which may be affected in midbrain lesions).

Answer 19

II, III, IV, V

Question 20

True/False.

The cerebellum grows dorsally from alar swellings in the medulla.

Answer 20

False.

The cerebellum grows dorsally from alar swellings in the pons.

Question 21

In the midbrain, the colliculi are formed from _____ (number) dorsal swellings, and the ______ ________ forms ventrally.

Answer 21

In the midbrain, the colliculi are formed from 4 dorsal swellings (2 superior and 2 inferior), and the crus cerebri forms ventrally.

Question 22

The sensory ganglia (known as _______ _______ ganglia) ______ (are / are not) synaptic ganglia.

Answer 22

The sensory ganglia (known as dorsal root ganglia) are not synaptic ganglia.

Question 23

Which cranial nerves carry parasympathetic fibers?

Answer 23

III, VII, IX, X

Question 24

Cranial nerve III carries parasympathetic fibers from the _____________ nucleus to the _____________ ganglion.

Answer 24

Cranial nerve III carries parasympathetic fibers from the Edinger-Westphal nucleus to the ciliary ganglion.

Question 25

Cranial nerve VII carries parasympathetic fibers from the __________ nucleus to the __________ and __________ ganglia.

Answer 25

Cranial nerve VII carries parasympathetic fibers from the superior salivatory nucleus to the pterygopalatine and submandibular ganglia.

Question 26

Cranial nerve IX carries parasympathetic fibers from the _____________ nucleus to the _____________ ganglion.

Answer 26

Cranial nerve IX carries parasympathetic fibers from the inferior salivatory nucleus to the otic ganglion.

Question 27

What term refers to congenital defects/absence in the skull and brain?

What term refers to a congenital defect of the skull?

Answer 27

Anencephaly;

meroencephaly

Question 28

A neonate is missing the portion of their brain that connects the two hemispheres.

What is this congenital defect termed?

Answer 28

Corpus callosum agenesis

Question 29

_____________ refers to a failure of the forebrain to divide completely into right and left cerebral hemispheres.

Answer 29

Holoprosencephaly refers to a failure of the forebrain to divide completely into right and left cerebral hemispheres.

Question 30

__________ 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).

Answer 30

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).

Question 31

_________ refers to a congenital failure of growth of the brain and neurocranium.

Answer 31

Microcephaly refers to a congenital failure of growth of the brain and neurocranium.

Question 32

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?

Answer 32

Abnormal histogenesis of the cerebral cortex

Question 33

What term refers to an intracranial build-up of CSF?

Answer 33

Hydrocephalus

Question 34

What term refers to cranium bifidum (defect of the cranium) leading to herniation of intracranial contents?

Answer 34

Encephalocele

Question 35

What form of encephalocele (cranial defect leading to herniation of intracranial contents) only involves herniation of the meninges?

Answer 35

Meningocele

Question 36

What form of encephalocele (cranial defect leading to herniation of intracranial contents) involves herniation of the meninges and some neural tissues?

Answer 36

Meningoencephaloceles

Question 37

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?

Answer 37

Meningohydroencephaloceles

Question 38

Issues in CSF resorption in the subarachnoid granulations leads to what form of hydrocephalus?

Answer 38

Communicating;

non-obstructive

(I.e. the ventricles are all patently exchanging CSF.)

Question 39

Issues in CSF exchange between the ventricles (e.g. due to cerebral aquaduct constriction) leads to what form of hydrocephalus?

Answer 39

Non-communicating;

obstructive

(I.e. the ventricles are not patently exchanging CSF.)

Question 40

Anencephaly refers to a failure of the rostral _____________ to close.

Answer 40

Anencephaly refers to a failure of the rostral neuropore to close.

Question 41

Anencephaly refers to an open ________ and an absent ________.

Answer 41

Anencephaly refers to an open calvarium and an absent forebrain.

Question 42

Spina bifida refers to a failure of the caudal _____________ to close.

Answer 42

Spina bifida refers to a failure of the caudal neuropore to close.

Question 43

Name the three main forms of spina bifida.

Answer 43

Occulta (most common)

Meningocele

Meningomyelocele

Question 44

Holoprosencephaly is often related to defects in weeks 5 - 6 of development due to some failure in signalling in what gene?

Answer 44

The SHH gene

Question 45

Name two syndromes associated with holoprosencephaly.

Answer 45

Fetal alcohol syndrome;

Patau’s syndrome

Question 46

What will MRI reveal in a neonate with holoprosencephaly?

Answer 46

Monoventricle

+

basal ganglia fusion

Question 47

What is a Chiari I malformation?

Answer 47

Ectopia (congenital displacement) of cerebellar tonsils

+

spinal cavitations (e.g. syringomyelia)

Question 48

What is a Chiari II malformation?

Answer 48

Herniation of cerebellar vermis and tonsils (plus resultant hydrocephalus due to aquaductal stenosis)

+

an association with lumbosacral meningomyelocele

Question 49

When/how do Chiari I malformations typically present?

Answer 49

Adulthood;

as headaches and cerebellar symptoms