Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Anatomy

The sacrum is a large triangular bone, formed by fusion of 5 sacral vertebrae. The sacral canal is the continuation of the spinal canal, its caudal opening is known as the sacral hiatus (SH). The sacrum has two lateral walls each presents 4 intervertebral foramina. The sacral hiatus is formed due to failure of fusion of laminae of the fifth (occasionally 4th) sacral vertebra. The hiatus contains the lower sacral and coccygeal nerve roots, filum terminale and fibrofatty tissue. The sacral hiatus is covered by skin, subcutaneous fatty layer and superficial dorsal sacrococcygeal ligament (also called sacrococcygeal membrane), which has to be pierced to reach the sacral canal. The lateral margins of the hiatus are formed by 2 sacral cornua. They are important clinical landmarks during caudal epidural block (CEB). Caudal epidural block has been widely used for the treatment of lumbar spinal disorders, for the management of chronic back pain and ensuring analgesia and anesthesia in operations including labor pain and genitourinary surgery. Technique of the CEB depends on accurate localization of sacral hiatus through which access to the sacral epidural space is gained. For a successful CEB intervention, clinicians are expected to know the anatomy of the sacral bone and the SH. Unfortunately, there are considerable anatomical variations in this area, and these result in discrepancies in the size and shape of SH which may make its identification difficult

Issued also as CD