the pharynx and have no external connections. The internal opening for
this fistula would most likely be within the bed of the palatine fossa (2nd
pharyngeal pouch) or further inferiorly within the pharynx if is from the
third or lower pharyngeal embryonic pouches. Persistent glossopharyn-
geal fistula (answer a)(opening of the embryonic glossopharyngeal duct)
more rarely makes a connection to the surface ectoderm and like a thy-
roglossal duct cyst (answer f )would be a midline structure. A hyperactive
sebaceous gland (answer d)would not secrete a clear fluid. Spina bifida
occulta(answer e)is associated with a tuft of hairy skin over a defect in the
posterior arch of the spinal cord.
296.The answer is c.(Waxman, pp 993–994.)The symptoms indicate that
the lesion is at the level of the midbrain. The spastic paralysis, hyperreflexia,
and positive Babinski reflect an upper motor neuron lesion. The corticobul-
bar and corticospinal tracts pass through the cerebral peduncles (basis
pedunculi). Those originating in the right cortex will pass through the right
peduncle and then cross to the contralateral side in the pyramidal decussa-
tion, resulting in left-side hemiplegia. It is of interest that the lower motor
neurons innervating muscles of facial expression located below the eye
receive upper motor neurons (corticobulbar tract) only from the contralat-
eral cortex, whereas lower motor neurons innervating facial muscles above
the eye (e.g., frontalis) receive input from both sides of the cortex. This
explains why only the lower portion of the left face was paralyzed. The
deficit in movement of the right eye indicates damage to the ipsilateral ocu-
lomotor nerve (CN III), which passes through the cerebral peduncle en
routeto the interpeduncular fossa. The “down and out” direction of the
right eye is explained by unopposed contraction of the lateral rectus (CN VI)
and superior oblique (CN IV) muscles. Because there were no sensory
deficits, neither the thalamus (answers d and e)nor sensory cortex
(answers a and b)were involved. The sensory tracts are arranged dorso-
laterally in the midbrain and do notpass through the affected area.
297.The answer is b.(Waxman, pp 169–170.)The middle cerebral artery
supplies a large portion of cerebral cortex, including portions of the frontal,
parietal, and temporal lobes. These regions include the Broca’s and Wernicke’s
areas and the precentral motor and postcentral sensory regions. Decreased
blood flow in these regions explains the observed motor and sensory deficits.
The anterior choroidal artery (answer a)is a branch of the internal carotid
444 Anatomy, Histology, and Cell Biology