Identify the joint that articulates between the sacrum and ilium.

Identify the joint that articulates between the sacrum and ilium.

• A. Sacroiliac joint
• B. L4-L5 joint
• C. Lumbar facet joint between L5 and S1
• D. Pubic symphysis

Answer: (A)

The connection between the sacrum and the ilium is the sacroiliac joint. This joint sits where the sacrum, the triangular bone at the base of the spine, meets the ilium, the upper part of each hip bone. It’s a strong, weight‑bearing articulation that transfers forces from the upper body to the pelvis and allows only a small amount of movement to accommodate walking and stability. It’s not between lumbar vertebrae, which are the L4–L5 and L5–S1 facet and intervertebral joints, and it’s not the pubic symphysis, which is the fibrocartilaginous joint at the front of the pelvis between the pubic bones.

The connection between the sacrum and the ilium is the sacroiliac joint. This joint sits where the sacrum, the triangular bone at the base of the spine, meets the ilium, the upper part of each hip bone. It’s a strong, weight‑bearing articulation that transfers forces from the upper body to the pelvis and allows only a small amount of movement to accommodate walking and stability. It’s not between lumbar vertebrae, which are the L4–L5 and L5–S1 facet and intervertebral joints, and it’s not the pubic symphysis, which is the fibrocartilaginous joint at the front of the pelvis between the pubic bones.