Spinal cord organization — Flashcards

Flashcard 1: If only one tract (fasciculus) is present in the dorsal column, the spinal cord is _____ T6

Answer: below

Flashcard 2: Which spinal cord level contains mostly gray matter (relative to white matter)? _____

Answer: Sacral

Flashcard 3: The _____ horn of gray matter contains motor neurons

Answer: ventral

Flashcard 4: Which spinal cord level is characterized by large ventral horns and a high ratio of gray matter to white matter?

Answer: Lumbar

Flashcard 5: Both dorsal columns (fasciculus gracilis and fasciculus cuneatus) are present at and above which spinal level?

Answer: T6

Extra: The fasciculus gracilis is present at all spinal levels (carrying sensation from the lower limbs), while the fasciculus cuneatus begins only at the T6 level (carrying sensation from the upper limbs). Therefore, both dorsal columns are present only at and above the level of T6.

Flashcard 6: Which descending motor tract is responsible for voluntary movement of the limbs and decussates at the medullary pyramids?

Answer: Lateral corticospinal tract

Flashcard 7: What is an Argyll-Robertson pupil?

Answer: pupil that is unreactive to light but constricts with accomodation

Flashcard 8: Embryological origin of the neurohypophysis

Answer: Neuroectoderm (Diencephalon)

Extra: The neurohypophysis (posterior pituitary) develops from a downward extension of the neuroectoderm from the floor of the diencephalon (the infundibulum). In contrast, the adenohypophysis (anterior pituitary) develops from Rathke's pouch (oral ectoderm).

Flashcard 9: pineal gland

Answer: neuroectoderm

Flashcard 10: retina

Answer: neuroectoderm