Fa: Neurology - Embryology

Front 1

What induces the ectoderm to differentiate into the neuroectoderm? What else does this form?

Back 1

- Notochord induces ectoderm → neuroectoderm
- And forms the neural plate

Front 2

What does the neural plate give rise to?

Back 2

- Neural tube
- Neural crest cells

Front 3

What does the notochord become?

Back 3

Nucleus pulposus of the intervertebral disc in adults

Front 4

What is the dorsal part of the neural plate? What is its function?

Back 4

Alar plate - sensory

Front 5

What is the ventral part of the neural plate? What is its function?

Back 5

Basal plate - motor

Front 6

What are the three primary vesicles that go onto become parts of the brain?

Back 6

- Forebrain: Prosencephalon
- Midbrain: Mesencephalon
- Hindbrain: Rhombencephalon

Front 7

What does the Prosencephalon become?

Back 7

- Telencephalon → Cerebral hemispheres & Lateral Ventricles
- Diencephalon → Thalamus & Third Ventricle

Front 8

What does the Mesencephalon become?

Back 8

Midbrain and Aqueduct

Front 9

What does the Rhombencephalon become?

Back 9

- Metencephalon → Pons, Cerebellum, and Upper part of Fourth Ventricle
- Myelencephalon → Medulla and Lower part of Fourth Ventricle

Front 10

What is the origin of the Telencephalon? What are the adult derivatives?

Back 10

- Originates from forebrain / prosencephalon
- Walls become cerebral hemispheres
- Cavity becomes lateral ventricles

Front 11

What is the origin of the Diencephalon? What are the adult derivatives?

Back 11

- Originates from forebrain / prosencephalon
- Walls become thalamus
- Cavity becomes the 3rd ventricle

Front 12

What is the origin of the Mesencephalon? What are the adult derivatives?

Back 12

- Originates from midbrain / mesencephalon
- Walls become the midbrain
- Cavity becomes the aqueduct

Front 13

What is the origin of the Metencephalon? What are the adult derivatives?

Back 13

- Originates from the hindbrain / rhombencephalon
- Walls become the pons and cerebellum
- Cavity becomes the upper part of the 4th ventricle

Front 14

What is the origin of the Myelencephalon? What are the adult derivatives?

Back 14

- Originates from the hindbrain / rhombencephalon
- Walls becomes the medulla
- Cavity becomes the lower part of the 4th ventricle

Front 15

What final neural structures originate from the neuroectoderm?

Back 15

- CNS neurons
- Ependymal cells (inner lining of ventricles, makes CSF)
- Oligodendroglia
- Astrocytes

Front 16

What final neural structures originate from the neural crest?

Back 16

- PNS neurons
- Schwann cells

Front 17

What final neural structures originate from the mesoderm?

Back 17

Microglia (like macrophages, originates from the mesoderm)

Front 18

What causes neural tube defects?

Back 18

- Neuropores fail to fuse (4th week)
- Leads to persistent connection between amniotic cavity and spinal canal
- Associated with low folic acid intake before conception and during pregnancy

Front 19

What are the signs of a neural tube defect?

Back 19

- Elevated α-Fetoprotein (AFP) in amniotic fluid and maternal serum
- ↑ Acetylcholinesterase (AChE) in amniotic fluid is a helpful confirmatory test

Front 20

How does Acetylcholinesterase relate to neural tube defects?

Back 20

- Fetal AChE in CSF transudates across the defect into the amniotic fluid
- ↑ AChE in amniotic fluid is a confirmatory test of a neural tube defect

Front 21

What are the types of neural tube defects?

Back 21

Mild:
- Spina Bifida Occulta
- Meningocele
- Meningomyelocele
Severe:

Front 22

What is the term for the failure of the bony spinal canal to close, but with no structural herniation?

Back 22

Spina Bifida Occulta

Front 23

What is wrong in Spina Bifida Occulta?

Back 23

- Failure of bony spinal canal to close, with no structural herniation
- Usually seen at lower vertebral level
- Dura is intact

Front 24

What type of neural tube defect is associated with a tuft of hair or skin dimple?

Back 24

Spina Bifida Occulta - located at level of bony defect

Front 25

What is wrong in Meningocele?

Back 25

Meninges (but not spinal cord) herniate through the spinal canal defect
- Normal AFP (α-Fetoprotein)

Front 26

What is wrong in Meningomyelocele?

Back 26

Meninges and spinal cord herniate through the spinal canal defect

Front 27

What are the types of forebrain congenital anomalies?

Back 27

- Anencephaly
- Holoprosencephaly

Front 28

What can cause an open calvarium with a frog-like appearance and no forebrain? Cause?

Back 28

Anencephaly - malformation of anterior neural tube

Front 29

What are the clinical findings of Anencephaly?

Back 29

- ↑ AFP
- Polyhydramnios (no swallowing center in brain)
- No forebrain and open calvarium

Front 30

What is Anencephaly associated with? What can help prevent it?

Back 30

- Associated with maternal diabetes (type I)
- Maternal folate supplementation ↓ risk

Front 31

What goes wrong in Holoprosencephaly?

Back 31

Failure of L & R hemispheres to separate
- Moderate from has a cleft lip / palate
- Severe form results in cyclopia

Front 32

What causes Holoprosencephaly (failure of L&R hemispheres to separate)?

Back 32

May be related to mutations in sonic hedgehog signaling pathway

Front 33

What are the types of posterior fossa malformations?

Back 33

- Chiari II Malformation (Arnold Chiari Malformation)
- Dandy-Walker

Front 34

What can cause herniation of the cerebellar tonsils and vermis through the foramen magnum with aqueductal stenosis and hydrocephalus, often with lumbosacral myelomeningocele and paralysis below the defect?

Back 34

Chiari II Malformation (Arnold-Chiari Malformation)
- Type of posterior fossa malformation

Front 35

What are the problems in Chiari II (Arnold-Chiari Malformation)?

Back 35

- Significant herniation of cerebellar tonsils and vermis through foramen magnum
- Aqueductal stenosis → hydrocephalus
- Lumbosacral myelomeningocele → paralysis below defect

Front 36

What can cause agenesis of the cerebellar vermis with cystic enlargement of the 4th ventricle?

Back 36

Dandy-Walker
- Type of posterior fossa malformation

Front 37

What are the problems in Dandy-Walker? What is it associated with?

Back 37

- Agenesis of cerebellar vermis
- Cystic enlargement of 4th ventricle (fills enlarged posterior fossa)
- Associated with hydrocephalus and spina bifidia

Front 38

What is the cause of Syringomyelia?

Back 38

- A cyst or cavity forms within the spinal cord
- This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord

Front 39

What gets damaged by the cystic cavity within the spinal cord in patients with Syringomyelia?

Back 39

Crossing anterior spinal commissural fibers are typically damaged first → "cape-like" bilateral loss of pain and temperature sensation in upper extremities (fine touch is preserved)

Front 40

Where is Syringomyelia most often occurring?

Back 40

C8-T1 (leading to "cape-like" distribution of defects)

Front 41

What is Syringomyelia associated with?

Back 41

Chiari I malformation (>3-5 mm cerebellar tonsilar ectopia; congenital, usually asymptomatic in childhood, manifests with headaches and cerebellar symptoms)

Front 42

What forms the anterior 2/3 of the tongue? Functions?

Back 42

- 1st and 2nd branchial arches
- Responsible for sensation via CN V3 and taste via CN VII

Front 43

What forms the posterior 1/3 of the tongue? Functions?

Back 43

- 3rd and 4th branchial arches
- Sensation and taste mainly via CN IX
- Extreme posterior of tongue via CN X

Front 44

What provides motor function to the tongue?

Back 44

CN XII

Front 45

What are the muscles of the tongue derived from?

Back 45

Occipital myotomes

Front 46

What nerves are responsible for sensation/pain in the tongue?

Back 46

- Anterior 2/3: CN V3
- Posterior 1/3: CN IX and extreme posterior CN X

Front 47

What nerves are responsible for taste in the tongue?

Back 47

- Anterior 2/3: CN VII
- Posterior 1/3: CN IX and extreme posterior CN X (solitary nucleus)