Human Brain Anatomy Overview

Notes

ANATOMY OF THE HUMAN BRAIN OBIEKEZIE M.C. The brain, a bilaterally symmetric, soft, gelatinous structure surrounded by its meninges and enclosed in its bony cranium, is continuous with the spinal cord at the foramen magnum at the base of the skull. At birth the brain weighs less than 400 g, but by the beginning of the second year of life it has more than doubled in weight to 900 g. The adult brain weighs between 1,250 and 1,450 g, and demonstrates a gen der differential, since brains of males generally weigh more than those of females. • During embryonic development of all vertebrates, the CNS first makes its appearance as a simple tubelike structure, the neural tube, that extends down the dorsal median plane. • By the fourth week, the human brain begins to form as an expansion of the anterior or rostral end of the neural tube (the end toward the head). • Shortly thereafter, constrictions appear, dividing the developing brain into three major regions— • forebrain, • midbrain, and • hindbrain During embryo genesis the brain is subdivided into five continuous regions, From rostral to caudal Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon CONTENT General topograp...