Pelvis

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Pelvis
Image:Illu pelvic girdle.jpg
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). 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.

1 Components
2 Sexual differences
3 Function
4 Additional images
5 See also
6 External links

[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
Pelvic outlet	relatively large	relatively small
Pubic arch	> 80 degrees	< 60 degrees
Obturator foramen	oval	round
Acetabulum	small	large
Wing of ilium	more flaired	less flaired
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.	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.