Nervous and mental diseases . of theseventh, and are eventually distributed to the orbicular muscle of themouth, correlating the labial and lingual movements necessary inphonation, mastication, and other buccal processes. The decussation of the seventh explains the phenomena of crossed oralternate paralysis of the face and limbs. A lesion in the pons abovethe decussation involves at once the seventh nerve and the pyramidaltract for the opposite side of the body, but below the facial crossing andabove the pyramidal decussation a lesion involves the face on the sameside and the limbs on the oppo
Nervous and mental diseases . of theseventh, and are eventually distributed to the orbicular muscle of themouth, correlating the labial and lingual movements necessary inphonation, mastication, and other buccal processes. The decussation of the seventh explains the phenomena of crossed oralternate paralysis of the face and limbs. A lesion in the pons abovethe decussation involves at once the seventh nerve and the pyramidaltract for the opposite side of the body, but below the facial crossing andabove the pyramidal decussation a lesion involves the face on the sameside and the limbs on the opposite side. Such a lesion must involvethe lower third of the pons, approximately the portion below the super-ficial origin of the fifth pair. After entering the internal auditory meatus the seventh nerve bendssomewhat sharply, and presents a gangliform swelling, which receives thelarge superficial petrosal from the Vidian nerve, probably containing thetaste-fibers from the second branch of the fifth nerve by way of the spheno-. Fig. 44.—Diagram showing the courseof facial and pyramidal fibers and the re-lations of cranial nerve-trunks. A, Le-sion causing one-sided symptoms; B, lesioncausing crossed paralysis of the face on oneside and the limbs on the other. 120 DISEASES OF THE CRANIAL NERVES. palatine ganglion. The taste-fibers leave the facial nerve in the form of thechorda tympani after it has almost completely traversed the Fallopian canal,and, passing up through the tympanum, finally reach the anterior portionof the tongue with the lingual branch of the fifth. Within the Fallopiancanal the facial gives off from within outward, first, near the ganglion ofthe knee, above mentioned, a motor branch to the tympanic plexus; sec-ond, a motor branch to the stapedius muscle; and, third, the chorda accom-panied by a secretory branchto the salivary glands. Thefacial nerve, therefore, withinthe aqueduct contains (1) motorfilaments for the facial muscles,(2) filaments of the specialse
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