©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
USMLE STEP 1 Neurology Exam Practice
Questions and Answers
The notochord induces what to differentiate into what? - ANSWER✔✔-Induces overlying ECTODERM to
differentiate into NEUROECTODERM and form NUERAL PLATE
Neural plate then gives rise to? - ANSWER✔✔-Neural tube and neural crest cells
Notochord becomes what? - ANSWER✔✔-Nucleus pulposus of the intervertebral disks in adults
Alar Plate - ANSWER✔✔-Dorsal [Sensory]
Same orientation as spinal cord
Basal Plate - ANSWER✔✔-Ventral [Motor]
Same orientation as the spinal cord
How does FGF affect chordin and noggin? - ANSWER✔✔-FGF regulates chordin and noggin to down
regulate BMP which leads to neural plate induction
Three Primary Vesicles - ANSWER✔✔-1. Forebrain [Prosencephalon]
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, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
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2. Midbrain [Mesencephalon]
3. Hindbrain [Rhombencphaln]
The Forebrain gives rise to: - ANSWER✔✔-1. Telencephalon [Cerebral hemispheres, lateral ventricles]
2. Diencephalon [Thalamus, Third Ventricle]
The Midbrain gives rise to: - ANSWER✔✔-1. Mesencephalon [Midbrain, aqueduct]
The Hindbrain gives rise to: - ANSWER✔✔-1. Metencephalon [Pons, cerebellum, upper part of the fourth
ventricle]
2. Myelencephalon [Medulla, Lower part of the fourth ventricle]
CNS/PNS Origins - ANSWER✔✔-Neuroectoderm = CNS neurons, ependymal cell [Inner lining of
ventricles, makes CSF], oligodendrocytes, astrocytes
Neural crest cells = PNS, schwann cells
Mesoderm = Microglia [Like Macrophages, originate from Mesoderm]
Neural tube defects - ANSWER✔✔-NEUROPORES fail to fuse [4th week] → Persistent connection
between amniotic cavity and spinal canal
Associated with:
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1. Low folate levels before conception and during pregnancy
2. ↑ a-fetoprotein levels [AFP] in amniotic and maternal serum
3. ↑ AChE in amniotic fluid [Helpful confirmatory test]
-- Fetal AChe in CSF transudates across defect into amniotic fluid
Spina bifida occulta - ANSWER✔✔-Failure of bony spinal canal to close, NO STRUCTURAL HERNIATION
Usually seen at lower vertebral levels
DURA INTACT
Associated w/ tuft of hair or skin dimple at level of bony defect
NORMAL AFP
Meningocele - ANSWER✔✔-Meninges [BUT NO NEURAL TISSUES] herniates through bony defect
Meningomyelocele - ANSWER✔✔-Meninges and neural tissue herniate through bony defect
Associated w/ Arnold-Chiari Type II Malformation
Anencephaly - ANSWER✔✔-Malformation of the ANTERIOR NEURAL TUBE →
1. No forebrain
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, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
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2. Open calvarium
Clinical Findings:
1. ↑ a-fetoprotein levels [AFP]
2. Polyhydramnios [No swallowing center in brain]
3. Associated w/ MATERNAL TYPE I DIABETES
4. Maternal folate supplementation ↓ risk
Holoprosencephaly - ANSWER✔✔-Failure of LEFT AND RIGHT HEMISPHERES TO SEPARATE
Usually occurs during the 5th and 6th week
May be related to mutations in the SONIC HEDGEHOG signaling pathway
Moderate form = Cleft lip/palate
Severe form = Cyclopia
Seen in:
1. PATAU SYNDROME
2. FETAL ALCOHOL SYNDROME
Page 4/143
FIRST PUBLISH OCTOBER 2024
USMLE STEP 1 Neurology Exam Practice
Questions and Answers
The notochord induces what to differentiate into what? - ANSWER✔✔-Induces overlying ECTODERM to
differentiate into NEUROECTODERM and form NUERAL PLATE
Neural plate then gives rise to? - ANSWER✔✔-Neural tube and neural crest cells
Notochord becomes what? - ANSWER✔✔-Nucleus pulposus of the intervertebral disks in adults
Alar Plate - ANSWER✔✔-Dorsal [Sensory]
Same orientation as spinal cord
Basal Plate - ANSWER✔✔-Ventral [Motor]
Same orientation as the spinal cord
How does FGF affect chordin and noggin? - ANSWER✔✔-FGF regulates chordin and noggin to down
regulate BMP which leads to neural plate induction
Three Primary Vesicles - ANSWER✔✔-1. Forebrain [Prosencephalon]
Page 1/143
, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
2. Midbrain [Mesencephalon]
3. Hindbrain [Rhombencphaln]
The Forebrain gives rise to: - ANSWER✔✔-1. Telencephalon [Cerebral hemispheres, lateral ventricles]
2. Diencephalon [Thalamus, Third Ventricle]
The Midbrain gives rise to: - ANSWER✔✔-1. Mesencephalon [Midbrain, aqueduct]
The Hindbrain gives rise to: - ANSWER✔✔-1. Metencephalon [Pons, cerebellum, upper part of the fourth
ventricle]
2. Myelencephalon [Medulla, Lower part of the fourth ventricle]
CNS/PNS Origins - ANSWER✔✔-Neuroectoderm = CNS neurons, ependymal cell [Inner lining of
ventricles, makes CSF], oligodendrocytes, astrocytes
Neural crest cells = PNS, schwann cells
Mesoderm = Microglia [Like Macrophages, originate from Mesoderm]
Neural tube defects - ANSWER✔✔-NEUROPORES fail to fuse [4th week] → Persistent connection
between amniotic cavity and spinal canal
Associated with:
Page 2/143
, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
1. Low folate levels before conception and during pregnancy
2. ↑ a-fetoprotein levels [AFP] in amniotic and maternal serum
3. ↑ AChE in amniotic fluid [Helpful confirmatory test]
-- Fetal AChe in CSF transudates across defect into amniotic fluid
Spina bifida occulta - ANSWER✔✔-Failure of bony spinal canal to close, NO STRUCTURAL HERNIATION
Usually seen at lower vertebral levels
DURA INTACT
Associated w/ tuft of hair or skin dimple at level of bony defect
NORMAL AFP
Meningocele - ANSWER✔✔-Meninges [BUT NO NEURAL TISSUES] herniates through bony defect
Meningomyelocele - ANSWER✔✔-Meninges and neural tissue herniate through bony defect
Associated w/ Arnold-Chiari Type II Malformation
Anencephaly - ANSWER✔✔-Malformation of the ANTERIOR NEURAL TUBE →
1. No forebrain
Page 3/143
, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
2. Open calvarium
Clinical Findings:
1. ↑ a-fetoprotein levels [AFP]
2. Polyhydramnios [No swallowing center in brain]
3. Associated w/ MATERNAL TYPE I DIABETES
4. Maternal folate supplementation ↓ risk
Holoprosencephaly - ANSWER✔✔-Failure of LEFT AND RIGHT HEMISPHERES TO SEPARATE
Usually occurs during the 5th and 6th week
May be related to mutations in the SONIC HEDGEHOG signaling pathway
Moderate form = Cleft lip/palate
Severe form = Cyclopia
Seen in:
1. PATAU SYNDROME
2. FETAL ALCOHOL SYNDROME
Page 4/143
