Bone
Sacrum
The spinal component of the posterior pelvic ring
High-yield
Four pairs of anterior and posterior foramina transmit sacral nerve branches. The sacral hiatus is the inferior posterior opening of the sacral canal.
Overview
The adult sacrum usually contains five fused vertebral segments. It lies between the hip bones and connects the lumbar spine to the pelvic ring, allowing body weight to pass toward the lower limbs through the sacroiliac joints.
Reference facts
- Bone type
- An irregular bone produced by fusion of the sacral vertebrae.
- Key landmarks
- Recognizable features include the promontory, alae, sacral foramina, median crest, hiatus and paired auricular surfaces.
- Articulations
- Joins L5 superiorly, the two hip bones laterally and the coccyx inferiorly.
Clinical correlation
Fragile sacral bone can fracture under ordinary loading, particularly with osteoporosis. Such insufficiency fractures may present as lower-back or buttock pain without a major traumatic event.
Frequently asked questions
What type of bone is the sacrum?
An irregular bone produced by fusion of the sacral vertebrae.
What does the sacrum articulate with?
The sacrum articulates with the joins L5 superiorly, the two hip bones laterally and the coccyx inferiorly.
What are the key landmarks of the sacrum?
Key landmarks of the sacrum include the recognizable features include the promontory, alae, sacral foramina, median crest, hiatus and paired auricular surfaces.