When dealing with fractures of the middle fossa, allusion was made to the implication of the seventh and eighth pair of nerves as the result of a fracture traversing the posterior fossa of the skull towards the outer angle of the jugular foramen and cutting across the petrous bone (see [p. 104]).
The ninth, tenth, and eleventh cranial nerves may be injured in the same variety of fracture. These three nerves are, however, so protected by their dural sheaths that they generally escape injury.[21]
In the following cases the nerves were involved:—
The patient was admitted suffering from a fracture resulting from a blow on the posterior parietal region. During the next four days no special symptoms developed. On the fifth day, during a sudden attack of dyspnœa and dysphagia, death occurred. A fissured fracture was found which extended into the jugular foramen, a region occupied by blood-clot.
A man committed suicide by means of a pistol-bullet fired through the mouth. The bullet lodged against the under surface of the petrous bone, tearing the jugular vein and lacerating the nerves passing through that foramen.
In another case the patient was admitted with a fractured base. He progressed favourably until the tenth day when, on sitting up suddenly in bed, he was seized with rigors, dyspnœa, and dysphagia, dying shortly afterwards. A basic fracture was found, practically dividing the skull into two parts and involving the jugular foramen. Displacement had occurred with consequent compression of the ninth, tenth, and eleventh nerves.
The twelfth nerve.
The anterior condyloid foramen is most favourably situated with respect to the course pursued by posterior fossa fractures. No instance of its involvement has come under my own observation.
Stierlein records a case in which the tenth and twelfth nerves were injured, with inability to speak or swallow, paralysis of the right half of the tongue, soft palate, vocal cords and pharyngeal constrictions. Death resulted in seven weeks.
The late Professor von Bergmann[22] mentions a case of hypoglossal paralysis together with paralysis of the sterno-mastoid and trapezius muscles (eleventh nerve).