Vertebra S2

The second sacral vertebra (S2) is part of the sacrum, which is formed by the fusion of five sacral vertebrae. The S2 vertebra has several key anatomical features:

1. Vertebral Body: The mean height, anteroposterior diameter, and width of the S2 vertebral body are approximately 25.0 mm, 13.5 mm, and 29.4 mm, respectively.[1]

2. Spinal Canal: The S2 spinal canal has a mid-sagittal diameter of about 10.3 mm, a maximum transverse diameter of 23.1 mm, and an area of 162.4 mm².[1]

3. Lateral Mass: The lateral mass of S2 is significant for screw fixation. The mean transpedicular screw length is 25.2 mm with an optimal medial angle of 30 degrees, while the mean lateral mass screw length is 32.8 mm with an optimal lateral angle of 22 degrees.[1]

4. Sacral Foramina: The S2 vertebra contains both anterior and posterior sacral foramina. The posterior sacral foramen (PSF) at S2 measures approximately 8 mm × 8 mm.[2]

5. Sacral Canal Termination: The thecal sac typically ends at the S2 level, which is an important consideration for surgical procedures involving the sacrum.[2]