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47. Dural venous sinuses

  1. The inferior sagittal sinus drains to the straight sinus (sinus rectus) ?
  2. The great cerebral vein (vena Galeni) drains to the straight sinus ?
  3. The cavernous sinus drains to the superior and inferior petrosal sinuses ?
  4. The transverse sinus drains to the sigmoid sinus ?
  5. The sigmoid sinus drains to the internal jugular vein ?
  6. The inferior petrosal sinus drains to the internal jugular vein ?

  1. T
  2. T
  3. T
  4. T
  5. T
  6. T

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2. Olfactory nerve

  1. Is the first cranial nerve (CN I). (T/F?)
  2. Is the second shortest of the cranial nerves. (T/F?)
  3. Emanates from the brainstem like all of the cranial nerves. (T/F?)
  4. Travels through cribriform plate of the ethmoid bone. (T/F?)
  5. Tumors of the frontal lobe of the brain can cause damage to the olfactory nerve. (T/F?)
  6. Lesions of the olfactory nerve  lead to a reduced ability to sense pain from the nasal epithelium. (T/F?)

  1. T
  2. F
  3. F
  4. T
  5. T
  6. F

    1. Olfactory nerve is the shortest of the cranial nerves.
    2. Olfactory nerve fibers arise from olfactory receptor cells located in the olfactory epithelium in the upper parts of the nasal cavity. They pass through the cribiform plate of the ethmoid bone to synapse in the olfactory bulb which lays in the anterior cranial fossa. The only other cranial nerve that does not join the brainstem is optic nerve.

By Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5], via Wikimedia Commons

  1. Pain from the nasal epithelium is carried to the central nervous system by the maxillary nerve.

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1. Trochlear nerve

  1. Is the smallest cranial nerve in terms of the number of axons it contains. (T/F?)
  2. Has the shortest  intracranial length. (T/F?)
  3. Is the one of two cranial nerves that exit from the dorsal (rear) aspect of the brainstem. (T/F?)
  4. Innervates superior oblique muscle, on the opposite side (contralateral) from its origin. (T/F?)
  5. Emerges from the dorsal aspect of the brainstem at the level of the caudal mesencephalon, just below the inferior colliculus, (T/F?)
  6. Enters the orbit through the superior orbital fissure. (T/F?)

  1. T
  2. F
  3. F
  4. T
  5. T
  6. T

  1. It is the smallest  in terms of the number of axons it contains.  The shortest is the olfactory nerve.
  2. Trochlear nerve has the longest intracranial length.
  3. Trochlear nerve is the only cranial nerve that exits from the dorsal aspect of the brainstem.

    Henry Vandyke Carter [Public domain], via Wikimedia Commons
  4. It is the only cranial nerve with contralateral innervation. It decussates within the mesencephalon before emerging on the opposite side of the brainstem. An injury to the trochlear nucleus in the brainstem will result in an contralateral superior oblique muscle palsy, whereas an injury to the trochlear nerve (after it has emerged from the brainstem) results in an ipsilateral superior oblique muscle palsy.