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pelvis
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Labeled anatomical illustration of the human pelvic girdle, showing the sacrum, coccyx, hip bones, and key features such as the iliac crest, pubic symphysis, ischial tuberosity, and obturator foramen. An anatomical illustration of the human hip joint showing bones and ligaments, including the ilium, ischium, pubis, femur, head of femur, and labeled ligaments such as the iliofemoral, pubofemoral, and pubocapsular ligaments. Diagram showing front and side views of the pelvis in a chimpanzee, Australopithecus, and modern human, highlighting differences in iliac blade shape, hip joint orientation, and leg stance. The Human Body Two labeled illustrations compare dinosaur pelvic structures: the saurischian pelvis on the left with forward-pointing pubis, and the ornithischian pelvis on the right with backward-pointing pubis, both showing ilium, ischium, and pubis bones. Illustration comparing the hip bones of two dinosaurs: a saurischian pelvis highlighted within an Allosaurus and an ornithischian pelvis highlighted within a Stegosaurus, with detailed drawings of each pelvis type shown beside the respective dinosaur. internal structure of fishes Diagram of the female renal system showing kidneys, adrenal glands, and urinary tract organs in their anatomical positions, with labels for major structures including blood vessels, bladder, and uterus.
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Characteristics of the Human Body
Quick Facts
Also called:
bony pelvis or pelvic girdle
Related Topics:
birth canal
pubis
ilium
acetabulum
ischium
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Labeled anatomical illustration of the human pelvic girdle, showing the sacrum, coccyx, hip bones, and key features such as the iliac crest, pubic symphysis, ischial tuberosity, and obturator foramen.
Pelvic girdle Bones of the pelvic girdle.

pelvis

anatomy
Also known as: bony pelvis, hip girdle, pelvic bone
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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Last updated
•History
Top Questions

What is the pelvis and its function?

What are the components of the pelvis?

How does the human pelvis differ from that of apes?

How does the female pelvis differ from the male pelvis?

What conditions can affect the pelvis?

An anatomical illustration of the human hip joint showing bones and ligaments, including the ilium, ischium, pubis, femur, head of femur, and labeled ligaments such as the iliofemoral, pubofemoral, and pubocapsular ligaments.
The human hip and pelvisAnterior view of the hip and pelvis, showing attachment of ligaments to the femur, ilium, ischium, and pubis.

pelvis, in human anatomy, basin-shaped complex of bones that connects the trunk and the legs, supports and balances the trunk, and contains and supports the intestines, the urinary bladder, and the internal sex organs.

The pelvis consists of paired hipbones, connected in front at the pubic symphysis and behind by the sacrum. Each hipbone is made up of three bones—the blade-shaped ilium, above and to either side, which accounts for the width of the hips; the ischium, behind and below, on which the weight falls in sitting; and the pubis, in front. All three unite in early adulthood at a triangular suture in the acetabulum, the cup-shaped socket that forms the hip joint with the head of the femur (thighbone). The ring made by the pelvis functions as the birth canal in females.

The pelvis serves a critical role in providing attachment for muscles that balance and support the trunk and move the legs, the hips, and the trunk. In the human infant the pelvis is narrow and nonsupportive. As the child begins walking, the pelvis broadens and tilts, the sacrum descends deeper into its articulation with the ilia, and the lumbar curve of the lower back develops.

Muscles of facial expression, human anatomy, (Netter replacement project - SSC). Human face, human head.
Britannica Quiz
Characteristics of the Human Body
Diagram showing front and side views of the pelvis in a chimpanzee, Australopithecus, and modern human, highlighting differences in iliac blade shape, hip joint orientation, and leg stance.
The pelvis and leg bones of three great apesComparison of the pelvis and lower limbs of a chimpanzee, an australopith, and a modern human.

In the semierect apes, the center of gravity falls near the shoulder, and the abdominal organs are suspended from the vertebral column. The ilium is elongated and somewhat spoon-shaped, and the pelvis is oriented horizontally. When a human is standing erect, the center of gravity falls over the center of the body, and the weight is transmitted via the pelvis from the vertebral column to the thighbone, the knee, and the foot.

There are several key differences in morphology of the pelvis between humans and other apes. Among the latter, the ilium is broadened backward in a fan shape, developing a deep sciatic notch posteriorly, and a strut of bone, the arcuate eminence, is present on the ilium, located diagonally from the hip joint, where it playes a role in supporting lateral balance when the animal is in an upright posture. In addition, in other apes, the anterior superior iliac spine, on the upper front edge of the iliac blade, is closer to the hip joint, and the ischium is shorter. The pelvis of Australopithecus africanus—which lived more than two million years ago—is clearly hominin (of human lineage). Homo erectus and all later fossil hominins, including Neanderthals, had fully modern pelvises.

Sex differences in the pelvis are marked and reflect the necessity in the female of providing an adequate birth canal for a large-headed fetus. In comparison with the male pelvis, the female basin is broader and shallower, with the birth canal rounded and capacious. The sciatic notch is wide and U-shaped, and the pubic symphysis is short, with the pubic bones forming a broad angle with each other. In addition, in the female, the sacrum is short, broad, and only moderately curved, the coccyx is movable, and the acetabula are farther apart. These differences reach their adult proportions only at puberty. In males and females, wear patterns on the pubic symphyses may be used to estimate age at death.

The pelvis is vulnerable to fracture, particularly from falling, which is most likely to occur among older adults or individuals with weak bones. Older individuals may also experience osteoarthritis, rheumatoid arthritis, or other degenerative joint diseases of the pelvis. The pelvis also can be affected by limb-girdle muscular dystrophy, in which voluntary muscles around the pelvic and shoulder areas weaken progressively over time. Osteitis pubis results from inflammation of the pubic symphysis, often from overuse in athletes. During pregnancy, increasing instability in the pelvic joints can produce a condition known as pelvic girdle pain (PGP). PGP typically resolves on its own in the weeks or months following childbirth, though full recovery may take years.

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The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Kara Rogers.