Rhombus of Michaelis

Rhombus of Michaelis (also known as Michaelis' rhombus, quadrilateral of Michaelis or sacral rhombus) is a kite-shaped area that includes the three lower lumbar vertebrae, the sacrum and that part of the ilium that is posterior to the acetabulum. It is named after the German gynecologist Gustav Adolf Michaelis who first described its importance in childbirth.

Anatomy

The Rhombus of Michaelis is a diamond-shaped area on the lower back of a woman. It is bordered by the lumbar vertebrae at the top, the iliac crests on the sides, and the sacrum at the bottom. The posterior superior iliac spines form the lateral points of the rhombus.

Role in Childbirth

During the second stage of labor, the Rhombus of Michaelis increases in size which allows the sacrum to move backwards to increase the diameter of the pelvic outlet. This is crucial for the baby's head to pass through. The movement of the sacrum is facilitated by the woman adopting an upright or forward-leaning position during labor.

Clinical Significance

Understanding the role of the Rhombus of Michaelis in childbirth can help healthcare professionals to support women during labor and delivery. It can also be used as a guide for manual therapy techniques in the treatment of lower back pain.

See Also

• Pelvis
• Childbirth
• Lumbar vertebrae
• Sacrum