Embryology and Anatomy: Spine/Spinal Cord

Abstract

Development of the spine and spinal cord begins during the third week of gestation. Early development includes formation of primitive neural tissue, notochord develop- ment, and of the axes of the embryo. The axial skeleton eventually arises from the somites, while the central ner- vous system (CNS) arises from primordial mesoderm. Neurons within the CNS sprout axons form mixed spi- nal nerves that extend to the appropriate end organs cre- ating the peripheral nervous system (PNS). Mesodermal vertebrae eventually give way to a cartilaginous anlage, which is then progressively ossifi ed, forming the mature vertebrae. Secondary vertebral ossifi cation centers and the neurocentral synchondroses persist until the third decade of life and allow growth of the spinal canal during development. This chapter discusses these key elements of spine and spinal cord development and highlight critical moments during development that can lead to bony and neural malformation.