| Pelvic cavity | |
|---|---|
| Latin | cavitas pelvis |
| Lymph | primarily internal iliac lymph nodes |
The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor.
The pelvic cavity primarily contains reproductive organs, the urinary bladder, the pelvic colon, and the rectum. The rectum is placed at the back of the pelvis, in the curve of the sacrum and coccyx; the bladder is in front, behind the pubic symphysis. In the female, the uterus and vagina occupy the interval between these viscera. The pelvic cavity also contains major arteries, veins, muscles, and nerves. These structures have to work together in a little crowded space. They can be affected by many different diseases and by many drugs in many different ways. One part may impact upon another, for example constipation may overload the rectum and compress the urinary bladder, or childbirth might damage the pudendal nerves and later lead to anal weakness.
Contents |
The boundaries are as follows:
| roof: pelvic brim[1] | ||
| posterior: sacrum, coccyx | lateral: obturator internus | anterior: pubic symphysis |
| floor: pelvic floor |
The lesser pelvis (or "true" pelvis) only includes structures inferior to the pelvic brim.
For example, the pelvic splanchnic nerves arising at S2-S4 is in the true pelvis, but the femoral nerve from L2-L4 is only in the "false pelvis", or greater pelvis.
| Ligament | From | To |
| broad ligament of the uterus | ||
| * mesovarium | ovary | |
| * mesosalpinx | Fallopian tube | |
| * mesometrium | ||
| cardinal ligament | ||
| ovarian ligament | ovary | uterus |
| round ligament of the uterus | ||
| suspensory ligament of the ovary |
The pelvis can be classified into four main types by measuring the pelvic diameters and conjugates at the pelvic inlet and outlet and as oblique diameters.
| Measurement | From | To | Length |
|---|---|---|---|
| Transverse diameter (of inlet) |
Between extreme lateral points of pelvic inlet | 13.5-14 cm | |
| Oblique diameter I | Right sacroiliac joint | Left iliopubic eminence | 12-12.5 cm |
| Oblique diameter II | Left sacroiliac joint | Right iliopubic eminence | 11.5-12 cm |
| Anatomical conjugate | Pubic symphysis | Promontory | ~12 cm |
| True conjugate (obsteric conjugate) |
Retropubic eminence (posterior surface of symphysis) |
Promontory | 11.5 cm |
| Diagonal conjugate* | Inferior pubic ligament | Promontory | 13 cm |
| Straight conjugate | Lower border of symphysis | Tip of coccyx | 9.5-10 cm |
| Median conjugate | Lower border of symphysis | Lower border of sacrum | 11.5 cm |
| Transverse diameter (of outlet) |
Between ischial tuberosities | 10-11 cm | |
| Interspinous distance | Between anterior superior iliac spines | 26 cm (female) |
|
| Intercristal distance | Between furthest lateral points of iliac crest | 29 cm (female) |
|
| External conjugate | Spinous process of fifth lumbar vertebra | Upper edge of symphysis | ~20 cm |
| Intertrochanteric distance | Between femurs | 31 cm | |
| *Because the true conjugate can not be measured directly it is derived from the diagonal conjugate which is measured through the vagina. | |||
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