Viipositional Changes Of The Spinal Cord

A. In the newborn, the conus medullaris ends at the third lumbar vertebra (L-3).

B. In the adult, the conus medullaris ends at L-1.

VIII. THE OPTIC NERVE AND CHIASMA are derived from the diencephalon. The optic nerve fibers occupy the choroid fissure. Failure of this fissure to close results in coloboma iridis.

IX. THE HYPOPHYSIS (pituitary gland) is derived from two embryologic substrata (Figures 4-5 and 4-6).

A. Adenohypophysis is derived from an ectodermal diverticulum of the primitive mouth cavity (stomodeum), which is also called Rathke's pouch. Remnants of Rathke's pouch may give rise to a congenital cystic tumor, a craniopharyngioma.

B. Neurohypophysis develops from a ventral evagination of the hypothalamus (neuroectoderm of the neural cube).

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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