The intraneural distribution of myelinated fibres in the equine recurrent laryngeal nerve.
Abstract: The intraneural course of nerve fibres in the equine recurrent laryngeal nerve was investigated by partially ligating the nerve at a proximal site, and 3-8 weeks later, tracing the course and spatial relationships of intact and degenerating fibres along the distal stump. This nerve was chosen because of its great length, the fact that it is a nonbranching motor nerve and because of debate about the course of abductor and adductor nerve fibres in the recurrent laryngeal nerve. Six ponies were used and in each the recurrent nerve was partially ligatured about 20 cm from the larynx, using a fine silk suture. In all there was a clear separation of intact and degenerating fibres just distal to the suture, but they became mixed close to the point of innervation of the laryngeal muscles. The numbers of intact myelinated fibres remained similar along the partially denervated nerve segment. These results suggest that myelinated fibres mix within the recurrent laryngeal nerve and that focal lesions of this nerve should not result in denervation of individual laryngeal muscles.
Publication Date: 1987-12-01 PubMed ID: 3427399DOI: 10.1093/brain/110.6.1531Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study observed the journey of nerve fibers in the recurrent laryngeal nerve of horses, to understand its structure and relations. The research highlighted the intermingling of different types of myelinated fibers within the nerve, suggesting that focal damage to the nerve may not lead to the denervation of individual laryngeal muscles.
Introduction of Investigation
- This research was undertaken to study the inner pathway of nerve fibers in the equine recurrent laryngeal nerve. The Equine recurrent laryngeal nerve was chosen for its length, its identity as a nonbranching motor nerve and ongoing debate about the course of both abductor and adductor nerve fibers in the recurrent laryngeal nerve.
- The main method of investigation involved partially ligating the recurrent laryngeal nerve and monitoring the course and spatial relationships of intact and degenerating fibers along the distal stump over a period of 3-8 weeks.
Procedure of the Study
- The experiment was performed on six ponies. In each, the recurrent nerve was partially tied off using a fine silk suture about 20 cm from the larynx.
- Post-surgical observations were made to trace the course of the nerve fibers and their spatial relationships.
Results and Findings
- The finds pinpointed a clear separation of intact and degenerating fibers just below the ligation. However, these fibers were found to mix closer to the point of innervation of the laryngeal muscles.
- The investigation also revealed that the count of intact myelinated fibers remained more or less constant along the partly denervated nerve segment.
Interpretation and Conclusion
- The results suggest that different types of myelinated fibers are intertwined within the recurrent laryngeal nerve.
- The study also puts forth the possibility that isolated damage in the nerve might not result in denervation of specific laryngeal muscles. This is due to the fact that the fibers are not strictly separate or specific to certain muscle groups, but rather mix along their course.
Cite This Article
APA
Dyer KR, Duncan ID.
(1987).
The intraneural distribution of myelinated fibres in the equine recurrent laryngeal nerve.
Brain, 110 ( Pt 6), 1531-1543.
https://doi.org/10.1093/brain/110.6.1531 Publication
Researcher Affiliations
- School of Veterinary Medicine, University of Wisconsin, Madison 53706.
MeSH Terms
- Animals
- Horses / anatomy & histology
- Laryngeal Nerves / anatomy & histology
- Laryngeal Nerves / pathology
- Ligation
- Nerve Degeneration
- Nerve Fibers, Myelinated / anatomy & histology
- Nervous System / anatomy & histology
Citations
This article has been cited 4 times.- Draper ACE, Piercy RJ. Pathological classification of equine recurrent laryngeal neuropathy. J Vet Intern Med 2018 Jul;32(4):1397-1409.
- Hayashi M, Isozaki E, Oda M, Tanabe H, Kimura J. Loss of large myelinated nerve fibres of the recurrent laryngeal nerve in patients with multiple system atrophy and vocal cord palsy. J Neurol Neurosurg Psychiatry 1997 Mar;62(3):234-8.
- Llewelyn JG, Thomas PK, Gilbey SG, Watkins PJ, Muddle JR. Pattern of myelinated fibre loss in the sural nerve in neuropathy related to type 1 (insulin-dependent) diabetes. Diabetologia 1988 Mar;31(3):162-7.
- Harrison GD, Duncan ID, Clayton MK. Determination of the early age of onset of equine recurrent laryngeal neuropathy. 1. Muscle pathology. Acta Neuropathol 1992;84(3):307-15.
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