. A laboratory manual and text-book of embryology. Embryology. THE CEREBRAL NERVES 361 the facial nerve arise from the cells of the geniculate ganglion, which are in turn derived from the ganglion crest (Streeter). This ganglion is present at the third week (Fig. 341), located cranial to the acoustic ganglion. The centrally directed processes of the geniculate ganglion enter the alar plate and form part of the solitary tract. The peripheral fibers in part course with motor fibers in the chorda tympani, join the mandibular branch of the trigeminal nerve and end in the sense organs of the tongue
. A laboratory manual and text-book of embryology. Embryology. THE CEREBRAL NERVES 361 the facial nerve arise from the cells of the geniculate ganglion, which are in turn derived from the ganglion crest (Streeter). This ganglion is present at the third week (Fig. 341), located cranial to the acoustic ganglion. The centrally directed processes of the geniculate ganglion enter the alar plate and form part of the solitary tract. The peripheral fibers in part course with motor fibers in the chorda tympani, join the mandibular branch of the trigeminal nerve and end in the sense organs of the tongue. Other sensory fibers form later the great superficial petrosal nerve, which extends to the spheno-palatine ganglion. The motor fibers of the facialis at first course straight laterally passing Nucl. n. hypoglOSS N. aeceasorlua Funic posterior. Fig. 345.—Reconstruction of the nuclei of origin and termination of the cerebral nerves in an embryo of 10 mm. The somatic motor nuclei are colored red (Streeter). X 30. cranial to the nucleus of the abducens. The nuclei of the two nerves later gradually shift their positions, that of the facial nerve moving caudally and lateralwards, while the nucleus of the abducens shifts cranialwards. As a result, the motor root of the facial nerve in the adult bends around the nucleus of the abducens producing the genu or knee of the former. The two together produce the rounded eminence in the floor of the fourth ventricle known as the facial collic- ulus. 9. The Glossopharyngeal Nerve takes its superficial origin just caudal to the otic vesicle (Figs. 340, 344 and 346). Its few motor fibers arise from neuroblasts in the basal plate beneath the fifth neuromeric groove. These neuroblasts form. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Prentiss, Charles William, 1874-1915.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectembryology, bookyear1
