. Human embryology and morphology. Embryology, Human; Morphology. 198 HUMAN EMBRYOLOGY AND MOEPHOLOGY. (2) The Pons Varolii. (3) The Cerebellum. The Fourth Ventricle.—The cavity or neural canal of the hind brain becomes the fourth ventricle. In its floor are developed, roof plate (inf. med. velum) inner zone middle zone outer zone. ependyma taenia alar lamina basal lamina Fig. 162.—Section across the Hind Brain of a Human Embryo in the 5th week. out of the ventral and dorsal parts or laminae (Fig. 162) of the medullary plates, the pons and medulla. In its roof are developed the cerebellum, sup
. Human embryology and morphology. Embryology, Human; Morphology. 198 HUMAN EMBRYOLOGY AND MOEPHOLOGY. (2) The Pons Varolii. (3) The Cerebellum. The Fourth Ventricle.—The cavity or neural canal of the hind brain becomes the fourth ventricle. In its floor are developed, roof plate (inf. med. velum) inner zone middle zone outer zone. ependyma taenia alar lamina basal lamina Fig. 162.—Section across the Hind Brain of a Human Embryo in the 5th week. out of the ventral and dorsal parts or laminae (Fig. 162) of the medullary plates, the pons and medulla. In its roof are developed the cerebellum, superior and inferior medullary vela. Inferior Medullary Velum.—When a section is made across the posterior half of the hind brain of a fifth week human embryo (Fig. 162), the same parts are seen as in a section of the cord. The only difference is that the roof plate, which in the cord is narrow, is here very wide and thin. It will also be noticed that each medullary plate, shows, as in the spinal cord, a dorsal or alar lamina and a ventral or basal one. The two laminae of each side meet at an angle. In the roof plate over the anterior half of the 4th ventricle is developed the cerebellum and superior medullary velum ; over the posterior half, the roof plate forms the inferior medullary velum. As shown in Fig. 163, the velum is continuous with the cerebellum above and the roof of the central canal of the cord below. In the posterior margin of the cerebellar rudiment are developed: (1) the nodule, (2) the flocculus, (3) the peduncle of the flocculus between 1 and 2 (Fig. 164). Hence the inferior medullary velum ends above in these structures. The obex and ligula, thickenings found on the margins of the lower angle of the 4th ventricle, mark the attachment of the roof. 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 origin
Size: 2010px × 1243px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
