©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
USMLE STEP 1 Neurology Exam Practice
Questions and Answers (100% Pass)
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]
2. Midbrain [Mesencephalon]
3. Hindbrain [Rhombencphaln]
1
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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:
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
2
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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
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
3
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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
Chiari Type II Malformation - Answer✔️✔️-Posterior fossa malformation
Significant HERNIATION of the CEREBELLAR TONSILS and VERMIS
through FORAMEN MAGNUM with AQUEDUCTAL STENOSIS and
HYDROCEPHALUS
Patients often present w/:
1. Lumbosacral meningomyelocele
2. Paralysis below the defect
Dandy-Walker Malformation - Answer✔️✔️-AGENESIS of CEREBELLAR
VERMIS with CYSTIC ENLARGEMENT of the 4th ventricle
Fills enlarged posterior fossa
Associated w/:
4
USMLE STEP 1 Neurology Exam Practice
Questions and Answers (100% Pass)
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]
2. Midbrain [Mesencephalon]
3. Hindbrain [Rhombencphaln]
1
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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:
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
2
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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
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
3
, ©SOPHIABENNET@2024/2025 Tuesday, August 20, 2024 10:21 AM
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
Chiari Type II Malformation - Answer✔️✔️-Posterior fossa malformation
Significant HERNIATION of the CEREBELLAR TONSILS and VERMIS
through FORAMEN MAGNUM with AQUEDUCTAL STENOSIS and
HYDROCEPHALUS
Patients often present w/:
1. Lumbosacral meningomyelocele
2. Paralysis below the defect
Dandy-Walker Malformation - Answer✔️✔️-AGENESIS of CEREBELLAR
VERMIS with CYSTIC ENLARGEMENT of the 4th ventricle
Fills enlarged posterior fossa
Associated w/:
4
