The sacral canal is a continuation of the vertebral canal and runs throughout the greater part of the sacral bone. Above the sacrum, it is triangular in form and below its posterior wall is incomplete, from the non-development of the laminae and spinous processes.

It lodges the sacral nerves, and its walls are perforated by the anterior and posterior sacral foramina through which these nerves pass out.

The sacral canal ends in an opening known as the sacral hiatus.

Injection of a transhiatal epidural contrast agent improves fluoroscopic imaging of the sacral canal and of the neural foramina. Hence, this technique could be applied to help the surgeon identify anatomical landmarks during sacroiliac screw fixation in geriatric patients ¹⁾.