1. The nervus olfactorius is well developed, owing to the olfactory lobe being situated close to the cerebrum. It supplies the olfactory rosette by three branches.
2. The nervus opticus enters its orbit through the recess between the pleuro sphenoids. At the decussation the left nerve lies above the right. The nervus oculomotorius and nervus trochlearis come out of the cranium through separate foramina in the pleurosphenoid. The nervus abducens pierces a ridge on the cranial surface of prootic and emerges into the orbit through a tunnel formed by the parasphenoid and prootics.
3. The trigemino-facial complex arises by two roots. The facialis branch of posterior root forms the trigemino-facial complex with the anterior root. The hyo mandibular branch of the posterior root receives ramus communicans from the trigemino-facial complex and forms the hyomandibular trunk. The trigemino-facial complex separates into the supraorbital and infraorbital trunks on emergence from the cranium.
4. The supraorbital trunk runs as the common trunk of the opthalmicus superficialis trigemini and opthalmicus superficialis facialis. The infraorbital trunk separates into the maxillo-buccalis and the mandibularis trigemini. The maxillo-buccalis divides into the maxillaris and buccalis rami beyond the orbit. The mandibularis internus and externus trigemini enter separate canals of the dentary.
5. The ramus mandibularis facialis fuses terminally with the ramus mandibularis internus trigemini. Two rami lateralis accessori arise from the trigemino-facial complex and run along the mid-dorsal and mid-ventral lines of the body.
6. The nervus glossopharyngeus and nervus vagus emerge from the cranium by separate foramina. The pretrematic branch of glossopharyngeus develops an anastomosis with the hyomandibular trunk. The nervus vagus separates into a trunk of the first and second branchialis, another trunk of the third and fourth branchialis and visceralis and the third trunk of the lateralis vagi.
View full abstract