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 the cranial and caudal axes of the embryo as well as formation of primitive neural tissue and notochord development. The axial skeleton eventually arises from the somites forming mesodermal vertebrae. Congenital abnormalities that alter the development somites also alter development of the vertebrae, creating vertebral anomalies that may create congenital scoliosis or congenital kyphosis as well as associated anomalies in the cardiopulmonary and urogenital systems. The mesodermal vertebrae eventually give way to a cartilaginous anlage, which then ossifies and forms the mature vertebral column. The central nervous system (CNS) arises from primordial mesoderm. Neurons within the CNS sprout axons that form mixed spinal nerves. The mixed spinal nerves then extend to the end organs forming the peripheral nervous system (PNS). Neurocentral joints allow growth of the spinal canal into maturity, and secondary vertebral ossification centers persist until the third decade of life. This chapter will discuss these key elements of spine and spinal cord development and highlight critical moments during development that can lead to bony and neural malformation.