From Encyclopedia Jr, free information reference for Kids
The pelvis (pl. pelvises or pelves) is the bony structure located at the base of the spine (properly known as the caudal end). The pelvis incorporates the socket portion of the hip joint for each leg (in bipeds) or hind leg (in quadrupeds). It forms the lower limb (or hind-limb) girdle of the skeleton.
[edit] Components
The pelvis is formed of three bones: the ilium, ischium and pubis. These three bones fuse together with age and are collectively known as the os coxae, or the innominate bone.
The pelvis is joined to the sacrum bone by ligaments (the sacroiliac joint), and the hip bones nest in specially shaped sockets (the acetabulum) on each side.
The upper edge of the ilium is known as the iliac crest.
The place at the front of the pelvis where both pubis bones join together is called the symphisis pubica. This is normally a very inflexible joint, but it softens and becomes more flexible during late pregnancy, allowing it to expand during labor for the baby's head to pass through.
[edit] Sexual differences
| Structure |
Female |
Male |
| picture |
 |
 |
| overall description |
narrow and thick |
wide and shallow |
| Pelvic inlet |
circular shaped |
heart-shaped |
| Pubic arch |
about 80 degrees |
about 60 degrees |
| Obturator foramen |
oval |
round |
| Acetabulum |
small |
large |
| comparison of the angle of the width of the frontal opening to one's hand |
If the angle is about the same as between the outstretched thumb and index finger, it is a female pelvis (arcus pubis). |
If it is closer to the angle between the spread index and middle fingers, it is a male pelvis (arcus subpubis). |
[edit] Function
The pelvis protects the digestive and reproductive organs in the lower part of the body, and many large nerves and blood vessels pass through it to supply the legs. It is also an important load-bearing part of the skeletal system.
[edit] Additional images
Median sagittal section of pelvis.
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Articulations of pelvis. Anterior view.
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Articulations of pelvis. Posterior view.
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Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.
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[edit] See also
- Bone terminology
- Terms for anatomical location
- Hip fracture
- Lesser pelvis
- Greater pelvis
- Pelvic cavity
- Pelvic fracture
- Pelvic Bone Width
[edit] External links
- Dictionary at eMedicine Pelvis
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Pelvis: sacrum, coccyx, hip bone |
| Ilium: Arcuate line - Wing - gluteal lines (Posterior, Anterior, Inferior) - Fossa - Tuberosity - Crest - iliac spines (Anterior superior - Anterior inferior - Posterior superior - Posterior inferior)
Ischium: Body (Ischial spine, Lesser sciatic notch) - Superior ramus (Tuberosity of the ischium) - Inferior ramus
Pubis: Superior ramus (Pubic tubercle, Pubic crest, Obturator crest) - Inferior ramus (Pectineal line)
Compound: Obturator foramen - Acetabulum - Acetabular notch - Greater sciatic notch - Iliopectineal eminence - Ischiopubic ramus - Pubic arch - Lesser pelvis (Pelvic inlet, Pelvic brim, Cavity of the lesser pelvis, Pelvic outlet) - Greater pelvis
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