Innervation of the posterior fossa dura of the cat

This study was designed to identify the location of neurons giving rise to fibers innervating the posterior fossa dura in the cat using horseradish peroxidase (HRP, Sigma, Type VI). Investigations since the 19th century have implicated innervation by cranial nerves V, VII, IX, X and XII and the upper cervical nerves, C1–3. The meninges of the posterior fossa of 14 cats was exposed using one of three surgical approaches: (1) a suboccipital craniectomy and C1 laminectomy, (2) a parieto-occipital craniectomy with removal of the occipital lobe and bony tentorium exposing the meninges over the cerebellum, or (3) an anterior approach through the upper neck, exposing the dura of the ventral surface of the caudal brainstem. A unilateral, curvilinear incision was made in the dura and HRP was applied to the exposed dural edges. Following 48 hours the animals were sacrificed and fixed by perfusion. Cranial nerve ganglia of V, VII, IX, X, dorsal root ganglia (DRG) of C1–3, and superior cervical ganglia (SCG) were removed bilaterally, sectioned and processed with tetramethylbenzidine (TMB). HRP labeled cells were located bilaterally, always more ipsilaterally, in DRG of C1, C2, C3, and SCG with application of HRP to all three regions of the dura. Labeled cells were also located in trigeminal ganglia and superior ganglia of CN X, occasionally bilaterally, depending on the site of application. No HRP was ever identified in neurons of the geniculate ganglion, inferior ganglion of CN X or superior or inferior ganglia of CN IX. This information is valuable to an understanding of the innervation of intracranial structures and the problems of head pain.