Conflict of Interest: None.
Innervation of Rat and Human Dura Mater and Pericranial Tissues in the Parieto-Temporal Region by Meningeal Afferents
Article first published online: 6 MAY 2014
© 2014 American Headache Society
Headache: The Journal of Head and Face Pain
Volume 54, Issue 6, pages 996–1009, June 2014
How to Cite
Schueler, M., Neuhuber, W. L., De Col, R. and Messlinger, K. (2014), Innervation of Rat and Human Dura Mater and Pericranial Tissues in the Parieto-Temporal Region by Meningeal Afferents. Headache: The Journal of Head and Face Pain, 54: 996–1009. doi: 10.1111/head.12371
- Issue published online: 10 JUN 2014
- Article first published online: 6 MAY 2014
- Accepted manuscript online: 26 MAR 2014 07:22AM EST
- Manuscript Accepted: 19 MAR 2014
- EUROHEADPAIN. Grant Number: 602633
- neuronal in vitro tracing;
- fluorescence microscopy;
- trigeminal ganglion;
- spinosus nerve;
To reinvestigate the innervation pattern of the dura mater of rat and human middle cranial fossa, the morpho-functional substrate of headache generation, and adjacent extracranial tissues with neuronal in vitro tracing.
This study was initiated by recent structural and functional findings of meningeal afferent fibers which innervate the cranial dura mater and may project to extracranial tissues.
Anterograde and retrograde neuronal in vitro tracing was made in formaldehyde fixed hemisected rat and human skulls. The fluorescent tracer DiI was applied to proximally cut meningeal nerves in rat and to distal branches of the spinosus nerve in human calvaria lined by dura mater. After several weeks, the dura mater and deep extracranial tissues were examined with fluorescence microscopy.
In addition to a network of meningeal nerve fibers, several fiber bundles were observed, leaving the skull through emissary canals and fissures to innervate the pericranial temporal, parietal, and occipital periosteum. Traced fibers were seen spreading into deep layers of the temporal and upper neck muscles. Retrograde neuronal tracing revealed labeled cell bodies exclusively in the mandibular and maxillary division of the rat trigeminal ganglion, and centrally projecting fibers were identified in the spinal trigeminal tract. Electron microscopy of the cross-sected spinosus nerve showed myelinated and unmyelinated axons with similar numbers in human and rat.
We conclude that a proportion of meningeal afferents innervates extracranial tissues like periosteum and pericranial muscles via collaterals projecting through the skull. These afferents may be nociceptive, some may subserve proprioceptive functions. The finding of extracranial projections of meningeal afferents may be important for our understanding of extracranial impacts on headache generation and therapy.