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Bone: Pelvis
Female type pelvis from Gray's Anatomy
Male type pelvis from Gray's Anatomy
Gray's	subject #57 236
Dorlands / Elsevier	p_10/12623123

The (pelvis pl. pelvises or pelves) is the bony structure located at the base of the spine (properly known as the caudal end). It is part of the appendicular skeleton. Each os coxae (hipbone) consists of three bones: the ilium, ischium, and the pubis. The ilium is the largest and upper most part, the ischium is the posterior-inferior (back-lower) part, and the pubis is the anterior (front) part of the hipbone. The two hipbones are joined anteriorly at the symphysis pubis and posteriorly to the sacrum. 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.

Pelvic cavity

Pelvis parts named, showing hip joints.

The pelvic cavity is a body cavity that is bounded by the bones of the pelvis and which primarily contains reproductive organs, the urinary bladder, and the rectum. The lesser pelvis (or "true pelvis") only includes structures inferior to the pelvic brim. The greater pelvis (or "false pelvis") is the expanded portion of the cavity situated above and in front of the pelvic brim. The sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones.

Sex differences

Main article: Sex differences in humans

• Infrapubic angle is greater than 90˚ in females and less than 90˚ in males.
• Pelvic inlet in males is more heart-shaped, while in females it is more round or oval.
• Greater sciatic notch narrower in males.
• Acetabulum in males faces more laterally, while it faces more anteriorly in females.
• Sacrum more triangular and shorter in females.^[1]

There are four main types of pelvis

• Gynaecoid: Normal female pelvis, round with enlarged transverse diameter
• Android: Normal male pelvis, Heart shaped
• Anthropoid: Long anterior to posterior diameter
• Platypelloid: Long transverse diameter

Biiliac width

In humans, Biiliac Width is an anatomical term referring to the widest measure of the pelvis between the outer edges of the upper iliac bones.

Biiliac Width has the following common synonyms: pelvic bone width, biiliac breadth, intercristal breadth/width, bi-iliac breadth/width and biiliocristal breadth/width.

In the average adult female, it measures 28 cm (11 in).^[2] It is best measured by anthropometric calipers (an anthropometer designed for such measurement is called a pelvimeter). Attempting to measure biiliac width with a tape measure along a curved surface is inaccurate.

The biiliac width measure is helpful in obstetrics because a pelvis that is significantly too small or too large can have obstetrical complications. For example, a large baby and/or a small pelvis often lead to a caesarean section. ^[3]

It is also used by anthropologists to estimate body mass.^[4]

Additional images

Median sagittal section of pelvis.	Median sagittal section of male pelvis.	Median sagittal section of female pelvis.	Articulations of pelvis. Anterior view.
Articulations of pelvis. Posterior view.	Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.	Radiograph of a healthy human hip joint

See also

• Bone terminology
• Coccyx (tailbone)
• Greater pelvis
• Hip fracture
• Lesser pelvis
• Pelvic cavity
• Pelvic fracture
• Sacroiliac joint
• Pelvimetry
• Symphysis pubis
• Terms for anatomical location

References

1. ^ Saukko P, Knight B. Knight's Forensic Pathology, 3rd Ed. Edward Arnold Ltd. 2004. ISBN 0-340-76044-3.
2. ^ http://www.healthyeatingclub.org/APJCN/Volume14/vol14.1/fullArticles/Heinz.pdf
3. ^ Cesarean Section: Encyclopedia of Medicine
4. ^ Ruff C, Niskanenb M, Junnob J, Jamisonc P (2005). "Body mass prediction from stature and bi-iliac breadth in two high latitude populations, with application to earlier higher latitude humans". Journal of Human Evolution 48: 381–392. doi:10.1016/j.jhevol.2004.11.009. Retrieved on 2006-07-26. 

External links

• Pelvis at eMedicine Dictionary
• Coccyx pain, tailbone pain, coccydynia (Peer-reviewed medical chapter, available free online at eMedicine)
• view various anthropometers
• Self Estimation of Biiliac Width

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