Cranial Nerves of the Common Catfish, Clarias batrachus (LINN.)

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The nervus olfactorius is thin and small, since the olfactory bulb lies just behind the olfactory rosette. It supplies the olfactory rosette by a pair of branches, which arise independently. The nervus opticus enters the orbit through the optic foramen bounded by the parasphenoid and pleurosphenoid. During the decussation of optic nerves, the left nerve lies dorsal in most of the cases. The eye muscle nerves emerge from the cranium through the foramen for the trigeminofacial complex, which arises by two roots and emerges out of the cranium through the space between the parasphenoid, pleurosphenoid and prootic. It separates first the hyomandibular trunk intracranially, and splits into supraorbital and infraorbital trunks extracranially. The supraorbital trunk splits into the rami ophathalmicus superficialis facialis and ophthalmicus superficialis trigeminus beyond the eye ball. The infraorbital trunk distinguishes into the ramus buccalis and maxillo-mandibularis trunk. The ramus maxillaris supplies the maxillary barbel and the upper jaw. The ramus buccalis supplies the infraorbital canal of lateral-line system and sense organs of maxillary barbel. The ramus mandibularies trigeminus separates into the external and internal branches before the gap of the mouth and supply the mandibular and mental barbels and lower jaw. Anastomosis exists between ramus maxillaris and ramus buccalis. The ramus lateralis accessorius extends back from the trigeminofacial. complex collecting the dorsal rami of spinal nerves. Both anterior and posterior palatinus branches are present. The nerves glossopharyngeus arises through a single root and emerges through separate foramen. The vagal mass divides into the trunk of branchiales, another trunk of visceralis and the third trunk of ramus lateralis. vagi. The trunk of branchiales again shows division into an anterior, which givesrise to first two branchiales and posterior, which produces the remaining branchiales.. The pharyngeal branches arise from the second and third branchiales and from between the third and fourth branchiales. The respiratory trees on the second and: fourth gill archs are supplied by the branches of the pretrematic of second and the posttrematic of fourth branchiales respectively.