Coccyx vs. Sacrum — What's the Difference?
By Tayyaba Rehman — Updated on October 9, 2023
The coccyx, also known as the tailbone, is the small, triangular bone at the base of the spine. The sacrum is the larger, triangular bone above the coccyx, connecting the spine to the pelvis. Both are parts of the vertebral column.
Difference Between Coccyx and Sacrum
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Key Differences
The coccyx and sacrum are integral components of the human vertebral column. The coccyx, often termed the "tailbone," is the final segment of the vertebral column, comprising three to five fused vertebrae. In contrast, the sacrum is situated just above the coccyx and consists of five fused vertebrae.
Both the coccyx and sacrum play significant roles in supporting the body. The coccyx serves as an attachment site for certain muscles, ligaments, and tendons, providing stability. On the other hand, the sacrum forms the back portion of the pelvis, interfacing with the hip bones to create the sacroiliac joints.
Regarding pain or injury, the coccyx can be particularly sensitive. Falls or prolonged sitting might cause coccydynia, which is pain associated with the coccyx. The sacrum, while robust, can also be subject to fractures or pain, especially in conditions like sacroiliitis, which affects the sacroiliac joint.
Both the coccyx and sacrum have evolutionary significance. The coccyx is a vestigial structure, a remnant of tail vertebrae from evolutionary ancestors. The sacrum, however, has evolved to be broader and more curved in humans, providing support for our bipedal posture.
Comparison Chart
Position
Base of the vertebral column
Just above the coccyx
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Number of Vertebrae
3-5 fused vertebrae
5 fused vertebrae
Evolutionary Significance
Vestigial remnant of tail vertebrae
Adapted for bipedal human posture
Associated Pain
Coccydynia
Sacroiliitis
Function
Attachment for muscles, tendons, ligaments
Forms back part of the pelvis, sacroiliac joint formation
Compare with Definitions
Coccyx
The coccyx is the small triangular bone at the base of the spine.
He bruised his coccyx during a fall.
Sacrum
Sacrum forms the posterior wall of the pelvis.
The sacrum and iliac bones together form the sacroiliac joint.
Coccyx
Coccyx is often referred to as the tailbone.
He felt pain in his coccyx, or tailbone, after sitting for hours.
Sacrum
The sacrum is a broad, triangular bone at the base of the spine above the coccyx.
She fractured her sacrum during a skiing accident.
Coccyx
Coccyx comprises of three to five fused vertebrae.
Doctors confirmed there are four fused vertebrae in her coccyx.
Sacrum
Sacrum consists of five fused vertebrae.
The five vertebrae of the sacrum fuse during early life.
Coccyx
Coccyx serves as the terminal segment of the vertebral column.
She learned that the coccyx was the end part of the vertebral column.
Sacrum
Sacrum is integral to bipedal human posture.
The curvature of the sacrum helps support our upright stance.
Coccyx
Coccyx provides an attachment site for several anatomical structures.
Certain ligaments attach to the coccyx, giving stability.
Sacrum
The sacrum (plural: sacra or sacrums), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1–S5) between ages 18 and 30.The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones.
Coccyx
The coccyx (plural: coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g.
Sacrum
A triangular bone in the lower back formed from fused vertebrae and situated between the two hip bones of the pelvis.
Coccyx
A small triangular bone at the base of the spinal column in humans and some apes, formed of fused vestigial vertebrae.
Sacrum
A triangular bone made up of five fused vertebrae and forming the posterior section of the pelvis.
Coccyx
A small triangular bone at the base of the spinal column in humans and other apes, consisting of several fused rudimentary vertebrae. Also called tailbone.
Sacrum
(anatomy) A large triangular bone at the base of the spine, located between the two ilia (wings of the pelvis) and formed from vertebrae that fuse in adulthood.
Coccyx
The final (bottom-most) fused vertebrae at the base of the spine, the tailbone.
Sacrum
That part of the vertebral column which is directly connected with, or forms a part of, the pelvis.
Coccyx
The end of the vertebral column beyond the sacrum in man and tailless monkeys. It is composed of several vertebræ more or less consolidated.
Sacrum
Wedge-shaped bone consisting of five fused vertebrae forming the posterior part of the pelvis; its base connects with the lowest lumbar vertebra and its tip with the coccyx
Coccyx
The end of the vertebral column in humans and tailless apes
Sacrum
Sacrum plays a role in connecting the spine to the pelvis.
Without the sacrum, the spine wouldn't be connected to the pelvis.
Common Curiosities
Where is the sacrum located?
The sacrum is positioned above the coccyx, forming the back portion of the pelvis.
Why is the coccyx called the tailbone?
It's a vestigial remnant of tail vertebrae from evolutionary ancestors.
What is coccydynia?
Coccydynia refers to pain arising from the coccyx or tailbone area.
Is sacroiliitis related to the sacrum?
Yes, sacroiliitis is an inflammation of the sacroiliac joint formed by the sacrum.
What's the coccyx?
The coccyx, or tailbone, is the small, triangular bone at the base of the spine.
Can you break your coccyx?
Yes, falls or impacts can lead to coccyx fractures or bruising.
How can the coccyx be injured?
Commonly through falls, prolonged sitting, or direct trauma.
What structures attach to the sacrum?
Ligaments, tendons, and muscles, especially those of the pelvis and lower back.
How many vertebrae make up the coccyx?
The coccyx comprises 3 to 5 fused vertebrae.
What's the main function of the sacrum?
It provides support for bipedal posture and forms the posterior wall of the pelvis.
Are the coccyx and sacrum movable?
They're mostly fixed due to fused vertebrae, but slight movement is possible at their joints.
How is the sacrum connected to the pelvis?
The sacrum forms the sacroiliac joints by interfacing with the hip bones.
Why is the sacrum broader in humans?
It has evolved to support our upright, bipedal posture.
Are the coccyx and sacrum unique to humans?
No, other vertebrates have them, but their shapes and functions might differ.
What connects the sacrum and coccyx?
The sacrococcygeal joint connects these two structures.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
