Gross Anatomy and Embryology Flashcards
7 cards from real NBME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Gross Anatomy and Embryology flashcards as text
A newborn has a sacral mass covered by a membrane containing neural elements. This is best classified as which neural tube defect?
Answer: Myelomeningocele
Myelomeningocele involves herniation of both meninges and spinal cord/nerve roots through a bony defect and is covered by a thin membrane, representing the most severe form of spina bifida.
A patient has a disc herniation at L4-L5 compressing the traversing nerve root. Which nerve root is most likely affected?
Answer: L5
At the L4-L5 disc level, the L4 root exits above the disc through the L4-L5 foramen, while the L5 root traverses across the disc before exiting at L5-S1, making L5 the root compressed by posterolateral herniation.
Notochord induction of the overlying ectoderm to form the neural plate occurs during which embryological process?
Answer: Primary neurulation
Primary neurulation is the process by which the notochord induces the overlying ectoderm to thicken into the neural plate, which then folds and fuses to form the neural tube.
An epidural hematoma on CT shows a biconvex (lens-shaped) hyperdensity. Which vessel is most commonly ruptured?
Answer: Middle meningeal artery
The middle meningeal artery runs in a groove on the inner surface of the temporal bone, and temporal skull fractures commonly tear it, causing an epidural hematoma.
The primitive streak forms during gastrulation and establishes which embryonic axis?
Answer: Cranial-caudal and bilateral symmetry axes
The primitive streak forms at the caudal end of the epiblast and establishes the cranial-caudal axis; epiblast cells migrate through it to become mesoderm and endoderm, defining the body plan.
A patient sustains a fracture of the pterion and develops rapid loss of consciousness followed by a lucid interval. Bleeding from which vessel is responsible?
Answer: Middle meningeal artery
The pterion overlies the anterior branch of the middle meningeal artery; fracture here causes arterial epidural hemorrhage with the classic lucid interval.
Hypospadias results from failure of fusion of which embryonic structures?
Answer: Urogenital folds
The urethral (urogenital) folds fuse in the midline to enclose the urethral plate and form the penile urethra; failure of fusion results in hypospadias with the urethral meatus on the ventral surface.