The sacroiliac joint is the location in the body where the pelvis and the spine connect.
The term “sacroiliac” refers to the sacrum (the lower part of the spine) and the hip bone (commonly referred to as the ilium, which is technically the top part of the hip bone).

The joint is held together by ligaments and reinforced by muscle.
An injury to the SI joint typically involves an injury to the ligaments, which can cause the joint to move abnormally.

Muscles also play a key role in the function of the SI joint, so an important part of recovery for an SI joint injury involves strengthening these muscles to make sure they’re working optimally.
There a lot of factors that can affect how stable someone’s SI joints are, such as gender, age, and whether the person may be genetically hypermobile (common among people with SI joint issues).
Because of this, what works for one person versus another can be pretty individual. I have found that the SI joint is like a puzzle, and you must approach it intellectually in order to figure it out.
Here’s a video I made showing you the exact location of the SI joint:
And these posts provide some basic info on the SI joint:
- Main functions of the SI joint
- Ligaments of the SI joint
- SI Joint Concepts: Useful terminology
- Major structures of the pelvis
- The SI joint is like a puzzle
- How the SI Joint affects Movement Efficiency
- The SI Joint and Shock Absorption
I hope this info helps to get you started!
Photo Credits: Both of the illustrations above courtesy of Wikipedia.