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Guilherme Mazui

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What is the Difference Between Sacrum and Coccyx?

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The sacrum and coccyx are two distinct bony structures located at the base of the spine. They are both composed of multiple fused vertebrae but serve different functions and have different characteristics:

Sacrum:

  • A triangular bone located just below the lumbar vertebrae.
  • Forms the posterior pelvic wall and strengthens and stabilizes the pelvis.
  • Composed of five segments (S1 to S5) and is connected to the last lumbar vertebra (L5) to form a sacral vertebra.
  • Part of the pelvic girdle along with the coccyx and two sacroiliac joints.
  • Can be subject to external trauma, injury, overextension, poor posture, or pregnancy.

Coccyx:

  • Also known as the "tail bone" or "tailbone".
  • Composed of two to four tiny, partially fused vertebrae.
  • Provides slight support for the pelvic organs but is considered a bone of little use.
  • Attached to several tendons and ligaments anteriorly and posteriorly, and also supports the vertebral column.
  • Can be fractured or affected by tumors, requiring surgical removal in some cases.

In summary, the sacrum is a larger, triangular bone that plays a crucial role in supporting and stabilizing the pelvis, while the coccyx is a smaller, triangular bone composed of fewer fused vertebrae that provides some support for the pelvic organs.

On this page
  • What is the Difference Between Sacrum and Coccyx?
  • Comparative Table: Sacrum vs Coccyx

    • Comparative Table: Sacrum vs Coccyx

    Here is a table summarizing the differences between the sacrum and coccyx:

    Feature Sacrum Coccyx
    Description A triangular bone, concave anteriorly and convex posteriorly, located just below the lumbar vertebrae. Also known as the tailbone, it is a vestigial bone that forms the final component of the vertebral column and comprises three to five rudimentary vertebrae.
    Formation Composed of five segments (S1 to S5) and is a triangular bone present just below the lumbar vertebrae. Derived from the fusion of three to five small coccygeal vertebrae.
    Function Connects the spine to the lower half of the body and fits between the two halves of the pelvis. The two dimples at the lower back are the point where the sacrum joins the hip bones forming a composite structure known as the pelvic girdle. Supports the vertebral column, attached to several tendons and ligaments anteriorly and posteriorly.
    Weight-bearing Yes, the sacrum is weight-bearing. No, the coccyx is not weight-bearing in the standing position, but may receive some body weight when sitting.

    Both the sacrum and coccyx are integral to functions such as walking, standing, and sitting.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.