The spinal column has 33 vertebrae: seven cervical, twelve thoracic, five lumbar, five sacral (fused), and four coccygeal. There are four curves in the spinal column: the cervical and lumbar curve convex anteriorly, whereas the thoracic and sacral curves convex posteriorly. The macro-, microanatomy, and sonoanatomy (static) of neuraxium, its content and relationships to other structures are discussed in this chapter. Special attention is given to the ligaments of the spine, and the ligamentum flavum in particular, paying special attention to the shapes that the spinal canal takes in certain regions, and the structure and consistency of the ligamentum flavum. Two further questions are specifically addressed in detail in this chapter. The first questions are why an epidural block is “segmental” and does not, like subarachnoid anesthesia, block the entire spinal cord distal to the site of injection. The second question answered in this chapter is why elderly people are less prone than their younger counterparts to developing postdural puncture headache following accidental dural puncture during attempted epidural block. Both of these questions are comprehensively addressed in this chapter on microanatomical grounds.
Keywords: Acute pain medicine, Arachnoid mater, Arachnoid villi, Arachnoid villus, Coccygeal, Dura mater, Dural puncture, Epidural anesthesia, Epidural block, Ligamentum flavum, Lumbar, Meninges, Neuraxium, Pia mater, Postdural puncture headache, Regional anesthesia, Sacral, Segmental, Spinal column, Spinal cord, Spinal ligaments, Spinal roots, Subarachnoid anesthesia, Thoracic, Vertebrae Cervical.