An Experimental Study On The Functional Orientation And Micro-structure Of The C7 Nerve Root And Its Branches

Objective: (1) To investigate the motor fiber counts of the human cervical 7th nerveroot and their orientation in C7 and its branches, and to analyze how to match donorand recipient nerves based on the motor fiber count in the C7 branches transfer. (2) Tostudy the functional outcomes of the main muscles in the upper extremity oncondition that C7 worked as the only dominated nerve.(3) To assess the final functionof the C7 dominated muscles after episolateral C7 transfer procedures was excised inthe rat partial brachial plexus injury model. (4) To evaluate the value of theintra-operative electrophysiological examination in the judgment of the originationof the dorsal thoracic nerve from the trunks of the brachial plexus in episolateral C7transfer procedures.Methods: (1) In the study of the C7's power in the upper extremity, the rat model ofC7 function as the only dominating nerve in upper extremity was established.Evaluation method include: motor fiber counts in the main nerves of the upperextremity, section area of the main muscles, EMG study, and maximum forcecontraction of the main muscle, and so on. (2) In the C7 dominated muscles' functionstudy, C7 nerve root was excised whereas the inferior or superior trunk was totallyinjuried in order to assess the feasibility of the episolateral C7 transfer procedure.(3)All of the fascicles in the divisions of C7 in human brachial plexus specimens weredivided under microscope (x10), and the motor fiber counts in the fascicles wereanalyzed. The principle of the match of the donor-recipient nerve fiber were discussed.Moreover, the dorsal thoracic nerve which is usually effected in the episolateral C7transfer was studied in its sources, and the value of the intra-operative EMG wasdiscussedResults: (1) There were 4-6 fascicles in both anterior and posterior divisions of C7which contain 3010 and 5883 motor fibers in human respectively, and the destinationof the fascicles can be discerned clearly. 1-2 nerve fascicles added to theMusculocutaneous nerve from the lateral cord, the rest of the anterior division 6复旦大学博士学位论文added to the median nerve(3-4 fascicles), the motor fiber count were 589 and 1931respectively; For the posterior division, 1-2 to the axillary nerve from the post cord,1-2 fascicles to the dorsal thoracic nerve from the post-lateral cord; and the rest to theradial nerve, and the motor fiber count were 611, 994, 4036 respectively. In theanatomical study of the origin of the dorsal thoracic nerve in trunks of brachial plexus,Eighty five percent of dorsal thoracic nerves were consisted from the inferior ,posterior and superior trunk. However, there were 5% from inferior and 10% fromsuperior trunk. (2) The function of C7's 5 terminal nerves and their dominated muscles in theupper extremity were evaluated. 2 weeks post operation, motor fiber counts reducedin all of the main terminal nerves on different levels, which were lower than the countin normal C7- fascicles and recovered to or exceeded to normal in 2 months. For otheritems, the recovery ratio of the CMAP, MAX-F, muscle force contractility,section cut area of muscle cell showed a drop in different degree, whereas in 2months, all of the items of the triceps muscle and latissimus muscle recovered tonormal, and the other 3 muscles improved. These items in group B which were totallydenervated showed a continuous deficiency and atrophy. (3)The safety assessment of episolateral C7 transfer procedure, C7 nerve root wasexcised totally while superior and inferior trunk of brachial plexus remained intact. 2weeks post operation, the motor fiver counts were reduced to about 30% in radialnerve and dorsal thoracic nerve in group Aand B, and to about 70% in group C and D.Two month after operation, motor fiber counts were increased 5%-7% higher thanthose of two weeks in group A and B, and meanwhile 4%-12% in group C and D. Th...