Printer Friendly

Segments of spinal cord harboring motor neuron somata of radial nerve of rabbit.

INTRODUCTION: Location of motor neuron somata supplying forelimb muscles have been studied by retrograde cell degeneration technique [5],[6],[7],[8],[9] and [10] by electrophysiological method [1] and by retrograde axonal transport of horse radish peroxidase (HRP) [11],[12],[13],[2] and [14] These studies have shown the locations of motor neuron somata of major forelimb nerves in cervical enlargement of spinal cord.

There are only few investigations on the locations of motor neuron somata of radial nerve or its branches,[15],[8],[9],[10],[1] [16],[12],[13] and [2] and there is some disagreement concerning their distribution. For example [2] in monkey the location of motor neuron somata of radial nerve extends from caudal end of fourth cervical segment (C-4) to second thoracic segment(T-2), whereas [1] in cat these neuron somata were located from sixth cervical segment (C-6) to first thoracic segment (T-l).

The aim of present study is to find out the cranio-caudal extent of spinal cord that harbors the motor neuron somata of radial nerve in rabbit.

MATERIAL AND METHODS: Six adult rabbits were used in this study. Initially several dissections were done in sacrificed animals to ascertain the formation and distribution of radial nerve on both sides and to decide upon the procedure for its surgical exposure. Under general anesthesia "using Thiopental sodium in the dose of 50 mg/kg body weight" the trunk of radial nerve was sectioned in axilla on right side.

The left side was used as control. Animals were allowed to survive for 8-28 days. After post lesional survival period of 8-28 days the animals were sacrificed with an overdose of chloroform and were immediately perfused through left ventricle of heart. Before starting the perfusion one of the superficial veins was cut in the neck. During perfusion first 500ml normal saline was injected followed by injection of 1500 ml of 10% of formal saline so that animal may be perfusion fixed. Twenty-four hours after perfusion spinal cord and hindbrain were exposed by dorsal approach i.e. by laminectomy and destruction of skull. Cervical and upper thoracic segments of spinal cord were removed along with hindbrain.

The 4th, 5th, 6th, 7th, & 8th cervical and 1st & 2nd thoracic spinal segments were, separated from each other and embedded in paraffin. Tissue blocks of each segment were prepared. From all blocks 40-micron thick serial transverse sections were dissected. Every 5th section was stained with thionine and studied light microscopically to identify neuronal somata with "typical chromatolysis" [3] or "cell body response" [4] and to compare the experimental (right) side with control (left) side.

OBSERVATIONS: Neuronal somata with "typical chromatolysis" or "cell body response" were found to be located in caudal part of fifth cervical segment, whole of the lengths of sixth seventh and eight cervical segments and cranial part of first thoracic segment. (Figs.1-2). Cell body response (including chromatolysis) was absent in fourth cervical and second thoracic segments. In left side (control) normal neuronal architecture was seen. Cell body response (including chromatolysis) was absent in control side.

DISCUSSION: Research of radial nerve is linked to fracture, nerve damage, humeral fractures, nerve paralysis, peripheral nerve injuries. The findings of present study are not in agreement with, [2] where in monkey the the motor neuron somata of many muscles supplied by radial nerve extend longitudinally from C-4 to T-1 (and often up to T-2) spinal cord segment. The findings of present study are also not in agreement with [1] where it was found in cat that the motor neuron somata of radial nerve were located from sixth cervical segment (C-6) to first thoracic segment (T-1).

In present study it was found that neuronal somata with "typical chromatolysis" or "cell body response" were located in caudal part of fifth cervical segment, whole of the lengths of sixth seventh and eight cervical segments and cranial part of first thoracic segment. This shows that segments of spinal cord that harbor motor neuron somata of radial nerve are 5th to 8th cervical segments and 1st thoracic segment.

This shows that if there is some injury to above mentioned segments of spinal cord or these segments are affected by certain lesions, radial nerve should be affected. But at times these these segments are affected, but radial nerve escapes. This is due to presence of motor neuron somata of radial nerve in different groups of ventral grey horn of spinal cord and not in whole of the width of segments.

This study can pave the way of further clinical researches related to radial nerve in humans.

CONCLUSION: Conclusion drawn from above study is that, the cranio-caudal extent of spinal cord harboring the motor neuron somata of radial nerve in rabbit extends from the caudal part of fifth cervical segment to cranial part of first thoracic segment.

DOI: 10.14260/jemds/2014/2868

REFERENCES:

[1.] Thomas RC, Wilson VJ. Recurrent interactions between motor neurons of known location in the cervical cord of cat. J. Neurophysiol 1967; 30: 661-674.

[2.] Jenny AB, Inukai J. Principles of motor organization of monkey cervical spinal cord. J. Neurosci 1983; 3: 567-575.

[3.] Nissl F. Uber die Veranderungen der ganglionzellen am Facialiskern des Kaninchens nach Aisreossimg derNerven, All. Z. Psychiat Ihre Grenzg. 1882; 48: 197-198.

[4.] Grafstein B. The nerve cell body response to axotomy. Experimental Neurology 1975; 48, 32-51.

[5.] Marinesco G. Recherchen experimentales surles Localization's motrices spinales. Revue Neurol 1901; 9: 410-424.

[6.] dee Neef, H.C. Studies on the motor cells of spinal cord. I Distribution in normal human cord. Am. J. Anat, 1942 70, 95-117.

[7.] Romanes, G.J. The development and significance of cell columns in theventral horn of the cervical and upper thoracic spinal cord of rabbit. J. Anat, 1941, 76, 112-130.

[8.] Georing, J. H. An experimental analysis of motor cell columns in the cervical enlargement of spinal cord in albino rat. J comp. Neurol. 1928, 46, 125-151.

[9.] Reed, A.F. The nuclear masses in the cervical spinal cord of Macaca Mulatta. J. Comp. Neurol, 1940 72, 187-206.

[10.] Sterling, P. and Kuypers, H.G.J.M. Anatomical organization of brachial spinal cord of cat. II. The motor neuron plexus. Brain. Res. 1967 4, 16-32.

[11.] Iwamotto, G.A., Haber, L.H., Dixon, T.A. and Gonyea, W.J. Anatomical distribution of flexor carpi radialis and flexor carpi ulnaris motor nuclei in cat spinal cord. Neurosc. Lett. 1980 20, 25-30.

[12.] Frietz, N. Illert, M. and Reeh, P. Location of ulnar and median motor nuclei in cat. Neurosc. Lett. 1982 30, 103-108.

[13.] Frietz, N. Illert, M. and Reeh, P. Location motor neurons projecting to the cat distal forelimb. II. Median and ulnar motor nuclei. J comp. Neurol. 1986 244, 302-312.

[14.] Mutai, M. Shibata, H. and Suzuki, T. Somatotropic organization of motor neurons innervating the pronators, carpal and digital flexors and forepad muscles in dog. Brain Res. 1986 375, 90-95.

[15.] Marinesco, G. Recherchen surles Localization's motrices spinales. La Semaine. Med. 1904, 24, 225-231.

[16.] Rao, G.S., Sahuy, S.and Saigal, H.P. The somatotropic arrangement of motor neurons on the spinal cord of buffalo. A Brachial plexus Acta Anat, 1971 80, 250-254.

Fig. 1: Photomicrograph of a part of transverse section of spinal cord of rabbit passing through the caudal part of fifth cervical segment (C-5) showing a chromatolysed (ch) neuron. (Rabbit No. 4: Thionine stain; A- X I30, B- X 260).

[FIGURE 1A OMITTED]

[FIGURE 1B OMITTED]

Fig. 2: Photomicrograph of a part of transverse section of spinal cord of rabbit passing through the cranial part of first thoracic segment (T1) showing a chromatolysed (ch) neuron. (Rabbit No. 6: Thionine stain; A- X I30, B- X 260).

[FIGURE 2A OMITTED]

[FIGURE 2B OMITTED]

Farhan Kirmani (1), Nema Usman (2), Shagufta Moini (3)

AUTHORS:

(1.) Farhan Kirmani

(2.) Nema Usman

(3.) Shagufta Moini

PARTICULARS OF CONTRIBUTORS:

(1.) Assistant Professor, Department of Anatomy, JNMC AMU.

(2.) Assistant Professor, Department of Anatomy, JNMC AMU.

(3.) Associate Professor, Department of Biochemistry, JNMC AMU.

NAME ADDRESS EMAIL ID OF THE CORRESPONDING AUTHOR:

Dr. Farhan Kirmani, Department of Anatomy, JNMC AMU.

Email: fkirmani@rediffmail.com

Date of Submission: 09/06/2014.

Date of Peer Review: 10/06/2014.

Date of Acceptance: 20/06/2014.

Date of Publishing: 25/06/2014.
COPYRIGHT 2014 Akshantala Enterprises Private Limited
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2014 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:ORIGINAL ARTICLE
Author:Kirmani, Farhan; Usman, Nema; Moini, Shagufta
Publication:Journal of Evolution of Medical and Dental Sciences
Date:Jun 30, 2014
Words:1370
Previous Article:Development of adverse drug reaction reporting culture in second professional medical undergraduates at tertiary care teaching hospital: a health...
Next Article:A comparative study of post operative astigmatism in superior versus temporal approach of manual small incision cataract surgery.
Topics:

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters |