ABSTRACT
Background: Cochlear nerve serves as one of the nodal point for enabling the passage of sound in both directions.The knowledge of age related morphological changes in human cochlear nerve is important to understand itsrole in the manifestation of sensori-neural presbycusis.Materials and Methods: The study was conducted in 21 human cochlear nerve samples, collected in 3 differentage groups (0-30 years, 31-50 years, 51 years and above). Resin embedding of cochlear nerves was done. Semithin (1 µm) cross sections of the nerves were cut by glass knife on Reichert Ultra-microtome. Under light microscope,toluidine blue stained nerve sections were studied for shape, organization of connective tissue and number offascicles.Results: Cochlear nerve was comma-shaped across all the age groups studied. Majority of the nerve sections hada blunt round head and sharp tail. Few sections had blunt tail also. Nerve fascicles were well defined in all the21 samples studied. The approximate number of fascicles across the various age groups varied from 60 to 85 pernerve. Numerous Schwann cells and numerous small sized blood vessels were found in the endoneurium of olderage group compared to younger and middle aged groups.Conclusion: However, we didn’t observe major qualitative changes across different age groups, but the presentstudy provides novel baseline morphological data on the human cochlear nerve.
ABSTRACT
The present study reports an anomalous branching pattern of the thoracic sympathetic chain. At the level of T3 ganglion, an anomalous branch i.e accessory sympathetic chain (ASC) descended anteromedial to the main sympathetic chain (MSC). The MSC and the ASC communicated with each other at the level of T9, T10 and T11 ganglion, indicating the absence of classical pattern of greater, lesser and least splanchnic nerves on the right side. However, on the left side, the sympathetic chain displayed normal branching pattern. We opine that the ASC may be representing a higher origin of greater splanchnic nerve at the level of T3 ganglion and the branches from MSC at T9, T10 and T11 ganglion may be the lesser and least splanchnic nerves, which further joined the ASC (i.e presumably the greater splanchnic nerve) to form a common trunk. This common trunk pierced the right crus of diaphragm to reach the right suprarenal plexus after giving few branches to the celiac plexus. Awareness and knowledge of such anatomical variants of thoracic sympathetic chain may be helpful to surgeons in avoiding any incomplete denervation or preventing any inadvertent injury during thoracic sympathectomy.
El presente estudio relata un patrón de ramos anómalos de la cadena simpática torácica. A nivel del ganglio de T3, un ramo anómalo denominado cadena simpática accesoria (CSA), descendió anteroedialmente a la cadena simpática principal (CSP). La CSP y la CSA comunicadas cada una con la otra a nivel de los ganglios de T9, T10 y T11, indicaban la ausencia de patrones clásicos de nervios esplácnicos mayor, menor y mínimo del lado derecho. Sin embargo, en el lado izquierdo, la cadena simpática estaba dispuesta en un de patrón normal. Nuestra opinión es que la CSA estaría representando un origen alto del nervio esplácnico mayor a nivel del ganglio de T3 y que los ramos de CSP de los ganglios T9, T10 y T11 podrían ser los nervios esplácnicos menor y mínimo, los cuales se unían lejos a la CSA (presumiblemente el nervio esplácnico mayor) para formar un tronco común. Este tronco común perforaba la cruz derecha del diafragma para alcanzar el plexo suprarrenal derecho, dando después pequeños ramos para el plexo celiaco. El conocimiento de tales variaciones de la cadena simpática torácica pueden ser de ayuda para los cirujanos, pudiendo ser evitada alguna denervación incompleta o prevenir algún daño involuntario durante la simpactectomía torácica.