Chapter 5 : Neurohistology (4)

Question 1

1. Peripheral nerve fibers regenerate at the rate of
(A) 0.1 mm/day
(B) 3 mm/day
(C) 100 mm/day
(D) 200 mm/day
(E) 400 mm/day

Answer 1

1–B. Peripheral nerve fibers regenerate at 3 mm/day.

Question 2

2. Fast pain has a conduction velocity of
(A) 1 m/sec
(B) 5 m/sec
(C) 15 m/sec
(D) 30 m/sec
(E) 100 m/sec

Answer 2

2–C. Fast pain has a nerve fiber (A delta) conduction velocity of 12 to 30 m/sec. Slow pain has a nerve fiber (C) conduction velocity of 0.5 to 2 m/sec.

Question 3

3. A 10-year-old boy has severed his radial nerve. Which of the following cells plays a major role in axonal regrowth?
(A) Fibrous astrocytes
(B) Fibroblasts
(C) Oligodendrocytes
(D) Protoplasmic astrocytes
(E) Schwann cells

Answer 3

3–E. Schwann cells play a major role in axon regeneration (axon regrowth) in the PNS.

Question 4

4. The MSR is initiated by which of the following receptors?
(A) End bulbs of Krause
(B) Merkel disks
(C) Muscle spindles
(D) Ruffini end bulbs
(E) Vater-Pacini corpuscles

Answer 4

4–C. The muscle stretch reflex is initiated by muscle spindles.

Question 5

5. Wallerian degeneration involves
(A) the proximal end of the axon
(B) only the CNS
(C) chromatolysis
(D) swelling of the cell body
(E) successive fragmentation of the axon

Answer 5

5–E. Wallerian, or anterograde, degeneration occurs toward the distal end of the axon in both the CNS and PNS and is characterized by successive fragmentation and disappearance of axons and myelin sheaths and by secondary proliferation of Schwann cells. Retrograde degeneration occurs toward the proximal end of the axon and in the cell body. It takes place in both the CNS and PNS and is characterized by chromatolysis, cell body swelling, and flattening and displacement of the
nucleus to the periphery.

Question 6

6. A 46-year-old female nurse complains of right-sided hearing loss and vertigo (dizziness). A small tumor was demonstrated within the internal auditory canal. Which structure listed below accounts for the hearing loss and vertigo?
(A) arachnoid cyst
(B) ependymoma
(C) epidermoid cyst
(D) meningioma
(E) Schwannoma

Answer 6

6–E. A schwannoma is a benign tumor derived from Schwann cells of the vestibular division of
CN VIII (acoustic neuroma of CN VIII). Schwannomas occur twice as frequently in females as in males. Symptoms arise from pressure on the vestibular division, resulting in vertigo, and pressure on the cochlear division, resulting in nerve deafness (sensorineural). Acoustic neurinomas represent 8% of intracranial neoplasms. When bilateral they are diagnostic of type 2 neurofibromatosis.The internal auditory canal contains the facial and vestibulocochlear nerves and the labyrinthine artery, a branch of the anterior inferior cerebellar artery. An arachnoid cyst is a congenital disorder; it is a CSF sac that forms in the cranium or spinal cord. An ependymoma is a
slow-growing, benign circumscribed neoplasm typically found within the ventricles. An epidermoid
cyst is a benign cyst derived from ectodermal tissue. A meningioma is a slow-growing
intracranial tumor of mesenchymal origin.

Question 7

7. A 9-year-old boy has a stumbling gait,dizziness, diplopia, headache, vomiting, and coarse nystagmus toward the side of the lesion. He scans his speech. Tests for dysdiadochokinesia, papilledema, elevated CSF protein, and intention tremor are positive. Match this symptom complex with the best-fitting choice.
(A) meningioma
(B) oligodendroglia
(C) medulloblastoma
(D) craniopharyngioma
(E) von Hippel-Lindau disease

Answer 7

7–C. The medulloblastomas are malignant neoplasms comprising one-third of the tumors in the posterior fossa of children. They are radiosensitive. Metastatic spread within the neuraxis is frequent. Meningiomas are benign tumors originating from arachnoid cells; they contain psammoma bodies that are calcified and visible on computed tomography. Oligodendroglia are the myelin-producing cells of the CNS. Craniopharyngiomas, congenital epidermoid tumors, are the most common supratentorial tumors found in children. Von Hippel-Lindau disease is a rare genetic disorder that results in tumor growth in blood-rich areas of the body.

Question 8

The response options for items 8 to 12 are the same. Select one answer for each item in the set.
(A) Astrocytes
(B) Oligodendrocytes
(C) Microglial cells
(D) Schwann cells
(E) Tanycytes
Match each of the following descriptions with the corresponding type of nerve cell.

8. Are a variety of ependymal cell found in the wall of the third ventricle

Answer 8

8–E. Tanycytes are a variety of ependymal cell found in the wall of the third ventricle. The
processes of these cells extend from the lumen of the third ventricle to the capillaries of the
hypophyseal portal system and also to the neurosecretory neurons of the arcuate nucleus.

Question 9

The response options for items 8 to 12 are the same. Select one answer for each item in the set.
(A) Astrocytes
(B) Oligodendrocytes
(C) Microglial cells
(D) Schwann cells
(E) Tanycytes
Match each of the following descriptions with the corresponding type of nerve cell.

9. Arise from monocytes

Answer 9

9–C. Microglial cells, the scavenger cells of the CNS, arise from monocytes and enter the CNS via
abnormal blood vessels.

Question 10

The response options for items 8 to 12 are the same. Select one answer for each item in the set.
(A) Astrocytes
(B) Oligodendrocytes
(C) Microglial cells
(D) Schwann cells
(E) Tanycytes
Match each of the following descriptions with the corresponding type of nerve cell.

10. Are neural crest derivatives

Answer 10

10–D. Schwann cells are derived from the neural crest; they myelinate the axons of the PNS.

Question 11

The response options for items 8 to 12 are the same. Select one answer for each item in the set.
(A) Astrocytes
(B) Oligodendrocytes
(C) Microglial cells
(D) Schwann cells
(E) Tanycytes
Match each of the following descriptions with the corresponding type of nerve cell.

11. Contain glial filaments and glycogen granules

Answer 11

11–A. Astrocytes are characterized by the presence of glial filaments and glycogen; glial filaments contain GFAP, a marker for astrocytes.

Question 12

The response options for items 8 to 12 are the same. Select one answer for each item in the set.
(A) Astrocytes
(B) Oligodendrocytes
(C) Microglial cells
(D) Schwann cells
(E) Tanycytes
Match each of the following descriptions with the corresponding type of nerve cell.

12. Are perineuronal satellite cells in the CNS

Answer 12

12–B. Oligodendrocytes are perineuronal satellite cells; they myelinate the axons of the central
nervous system (CNS).