Sacrum

Sacrum presentation

1. Sacrum By- Sanju Sah St. Xavier’s college, Maitighar , Kathmandu Department of Microbiology

2. The word sacrum comes from Latin word sacer , meaning sacred or strong. It is a single bone formed by incomplete fusion of five vertebrae to form triangular or wedged-shaped bone with a concave anterior surface. Location: It is situated at the upper, back part of pelvic cavity, between two wings of pelvis.

3. Anatomy The sacrum is a kyphotic bone, that is, it is concave in shape, facing outwards and forwards. There lies an inter-vertebral disc between the base of the last lumbar vertebra and the sacrum, which is known as the lumbosacral disc.

4. The canal for the passage of the spinal cord extends into the sacrum . The sacral nerves exit through the bony foramina, which are present along the outer borders of the sacrum . If these nerves get pressed due to dislocation or any other injury, then it can lead to intense pain in that area, among other symptoms.

5. Articulations The sacrum articulates with four bones: the last lumbar vertebra above the coccyx (tailbone) below the  illium  portion of the hip bone on either side.

6. Function Several key muscles of the hip joint, including the gluteus maximus , iliacus , and piriformis , have their origins on the surface of the sacrum and pull on the sacrum to move the leg . The sacrum also surrounds and protects the spinal nerves of the lower back.

7. Finally, the sacrum helps to form the pelvic cavity that supports and protects the delicate organs of the abdominopelvic cavity and provides space for a fetus to pass through during childbirth.

8. References Gray H: Anatomy of the Human Body. Philadelphia: Lea & Febiger , 1918; Bartleby.com, 2000 www.bartleby.com/107/ [July 18, 2003] 9. Rose and wilson , Anatomy and Physiology, 11 th edition, Reprinted in 2011 , Pp: 393.