Pelvis

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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

The pelvis (pl. pelvises or pelves) or pelvic girdle is the irregular bony structure located at the base of the spine (properly known as the caudal end). In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or lower extremity. Until puberty, however, each hip bone consists of three separate bones yet to be fused — the ilium, ischium, and the pubis — and the pelvis is thus composed of up to five or seven bones.

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 hip bone. The two hip bones are joined anteriorly at the symphysis pubis and posteriorly to the sacrum. The pelvis incorporates the socket portion of the hip joint (the acetabulum) for each leg (in bipeds) or hind leg (in quadrupeds). It forms the lower limb (or hind-limb) girdle of the skeleton.

During childbirth child has to pass through pelvic opening in women.^[1]

[edit] Pelvic cavity

Pelvis parts named, showing hip joints.

Main article: Pelvic cavity

The pelvic cavity is a body cavity that is bounded by the bones of the pelvis and which primarily contains reproductive organs 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.

[edit] 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.^[2]

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

[edit] Race differences

African women tend to have smaller pelvic floor areas than European women^[3].

[edit] 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

[edit] See also

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

[edit] References

1. ^ [1]
2. ^ Saukko P, Knight B. (2004). Knight's Forensic Pathology (3rd ed.), Edward Arnold Ltd. ISBN 0-340-76044-3. 
3. ^ http://cat.inist.fr/?aModele=afficheN&cpsidt=13800687

[edit] External links

• Pelvis at eMedicine Dictionary
• Coccyx pain, tailbone pain, coccydynia (Peer-reviewed medical chapter, available free online at eMedicine)

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