Posterior sacro-iliac ligament

Looks like

Bands over the back of the sacroiliac joint, from the back of the iliac crest to the side of the sacrum; the long part can be felt under the skin dimple.

What it does

Resists the sacrum tipping forward and adds to joint stability.

Keeping it well

The long part is a frequent tender spot in pregnancy-related pelvic pain.

Related conditions

• Axial spondyloarthritis
• Bone metastases and spinal cord compression
• Brucellosis
• Developmental dysplasia of the hip
• Gout
• Haemophilia & bleeding disorders
• Lyme disease
• Marfan syndrome & connective tissue disorders
• Obstructed labour and obstetric fistula
• Osteoarthritis
• Psoriatic arthritis
• Reactive arthritis
• Rheumatic fever & rheumatic heart disease
• Rheumatoid arthritis
• Systemic lupus erythematosus
• Temporomandibular joint disorder