QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

Help viewing high resolution images Return to article

Fig. 5. Anatomy of the accessory flexor muscle and the motor neuronal innervation. (A) Camera lucida drawing of the motor innervation in the distal part of the metathoracic femur, viewed posteriorly. The accessory flexor muscle (red) is inserted diagonally (about 45°) onto the cushion, which is extended from the apodeme on which the main flexor muscle (orange) attaches. The accessory flexor nerve diverged from N5B2 gives rise to fine ramification with rich varicosities in the accessory flexor muscle. (B) Back-fill from the accessory flexor nerve with dextran, tetramethyl rhodamine, revealing that two inhibitor axons (whose somata are identified in the ganglion) pass through N5B2 distally to innervate the tibial muscles (indicated by broken boxes), thus are regarded as common inhibitors. The posterior branch of the accessory flexor nerve is slightly thicker than the anterior branch although both contain identical motor axons. (C) Motor neurones in the metathoracic ganglion, back-filled differentially from the distal flexor nerve and accessory flexor nerve with dextran, fluorescein (green) and dextran, tetramethyl rhodamine (red), respectively. There is no overlap of motor neurones supplying both motor nerves. Somata of four exciters sending axons to the distal flexor nerve (three are fast- and one is intermediate-type) are much larger than those sending axons to the accessory flexor nerve [one tentative intermediate (i) and three slow-type (s)]. Two somata of common inhibitors (CI2, CI3) are located closely to the midline (right edge of photo) and segregate from exciters that congregate in the antero-lateral part of the ganglion. Visible nerve roots are numbered. (D) Motor neurones supplying the accessory flexor nerve in the metathoracic ganglion, back-filled with NiCl₂ and silver-intensified. Note that neither sensory afferents nor dorsal unpaired median (DUM) neurones were stained and there is no correlation of soma location of exciters between C and D. Visible nerve roots are numbered and the vertical broken line indicates midline of the ganglion. (E,F) Composite photomicrographs reconstructed from 19 µm transverse sections at the levels indicated in D. Three slow exciters arbitrarily numbered (s1–3), corresponded to those in D. The tentative intermediate exciter (i) is characterized by the larger soma and the thicker axon (arrow in E) compared with slow-type exciters. The primary dendritic area of CIs was circled by thin broken line. Visible nerve roots are numbered and the vertical broken line indicates midline of the ganglion.

Return to article