Pelvic cavity

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.

Pelvic cavity
The various cavities of the human body as seen in a frontal projection, with the pelvic cavity labeled 4.
The various cavities of the human body as seen in a lateral projection, with the pelvic cavity labeled 4.
Details
LymphPrimarily internal iliac lymph nodes
Identifiers
LatinCavitas pelvis
TA98A01.1.00.052
A10.1.00.002
A02.5.02.002
TA2130
FMA9738
Anatomical terminology
Male pelvis.
Female pelvis.

The pelvic cavity primarily contains the reproductive organs, urinary bladder, distal ureters, proximal urethra, terminal sigmoid colon, rectum, and anal canal. In the female, the uterus, Fallopian tubes, ovaries and upper vagina occupy the area between the other viscera.[1][2] 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. The pelvic cavity also contains major arteries, veins, muscles, and nerves. These structures coexist in a crowded space, and disorders of one pelvic component 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.

Structure
Pelvis

The pelvis has an anteroinferior, a posterior, and two lateral pelvic walls; and an inferior pelvic wall, also called the pelvic floor.[3][4] The parietal peritoneum is attached here and to the abdominal wall.[5]

Lesser pelvis

The lesser pelvis (or "true pelvis") is the space enclosed by the pelvic girdle and below the pelvic brim: between the pelvic inlet and the pelvic floor. This cavity is a short, curved canal, deeper on its posterior than on its anterior wall.[1] Some consider this region to be the entirety of the pelvic cavity. Others define the pelvic cavity as the larger space including the greater pelvis, just above the pelvic inlet.

The lesser pelvis is bounded in front and below by the superior rami of the symphysis pubis; above and behind, by the sacrum and coccyx; and laterally, by a broad, smooth, quadrangular area of bone, corresponding to the inner surfaces of the body and superior ramus of the ischium, and the part of the ilium below the arcuate line.[1]

roof: pelvic brim[6]    
  posterior: sacrum, coccyx    lateral: obturator internus    anterior: pubic symphysis  
floor: pelvic floor        

The lesser pelvis contains the pelvic colon, rectum, bladder, and some of the sex organs. The rectum is at the back, 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.[1]

The pelvic splanchnic nerves arising at S2-S4 are in the lesser pelvis.

Greater pelvis

The greater pelvis (or "false pelvis") is the space enclosed by the pelvic girdle above and in front of the pelvic brim. It is bounded on either side by the ilium; in front it is incomplete, presenting a wide interval between the anterior borders of the ilia, which is filled by the muscles and fascia of the anterior abdominal wall; behind is a deep notch on either side between the ilium and the base of the sacrum that is filled by the thoracolumbar fascia and associated muscles.[1]

It is generally considered part of the abdominal cavity (this is why it is sometimes called the false pelvis).[7] Some consider this region part of the pelvic cavity, while others reframe the classification question by calling the combination the abdominopelvic cavity.

The greater pelvis supports the intestines (specifically, the ileum and sigmoid colon), and transmits part of their weight to the anterior wall of the abdomen.[1]

The femoral nerve from L2-L4 is in the greater pelvis, but not in the lesser pelvis.

Ligaments
LigamentFromTo
broad ligament of the uterusuterusside of pelvis
* mesovariumovary
* mesosalpinxFallopian tubebroad ligament of the uterus
* mesometrium
cardinal ligamentcervix & vaginapelvic wall
ovarian ligamentovaryuterus
round ligament of the uterusovarytravels through inguinal canal, ends at mons pubis
suspensory ligament of the ovaryovarypelvic wall

Arteries

Nerves

Measurements

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.

Female pelvic cavity
Pelvic measurements[8]
MeasurementFromToLength
Transverse diameter
(of inlet)		Between extreme lateral points of pelvic inlet13.5–14 cm
Oblique diameter IRight sacroiliac jointLeft iliopubic eminence12-12.5 cm
Oblique diameter IILeft sacroiliac jointRight iliopubic eminence11.5–12 cm
Anatomical conjugate
(true conjugate)		Pubic symphysisPromontory~12 cm
Obstetric conjugateRetropubic eminence
(posterior surface
of symphysis)		Promontory>10 cm
Diagonal conjugate*Inferior pubic ligamentPromontory11.5–12 cm
Straight conjugateLower border of symphysisTip of coccyx9.5–10 cm
Median conjugateLower border of symphysisLower border of sacrum11.5 cm
Transverse diameter
(of outlet)		Between ischial tuberosities10–11 cm
Interspinous distanceBetween anterior superior iliac spines26 cm
(female)
Intercristal distanceBetween furthest lateral points of iliac crest29 cm
(female)
External conjugateSpinous process of fifth lumbar vertebraUpper edge of symphysis~20 cm
Intertrochanteric distanceBetween femurs31 cm
*Because the true conjugate can not be measured directly it is derived from the diagonal conjugate which is measured through the vagina.

Additional images
  • Joints of the pelvis. Anterior view.
  • The arteries of the pelvis.
  • Dissection of side wall of pelvis showing sacral and pudendal plexuses.
  • Sacral plexus of the right side.
  • Male pelvic cavity
  • Female pelvic cavity
  • Lateral projection of the human body cavities, with the line separating the abdominal and pelvic cavities shown.

References
  1. This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
  2. Drake R, Vogl AW, Mitchell AW. Gray's Basic Anatomy E-Book. Elsevier; 2018. ISBN 9780323508506. 5 Pelvis and Perineum. p. 220-227.
  3. Moore, Keith L. et al. (2010) Clinically Oriented Anatomy 6th Ed, ch.3 Pelvis and perineum, p.339
  4. Richard S. Snell Clinical Anatomy By Regions, Pelvic cavity p.242
  5. Tank, P. (2013) Grants Dissector 15th ed., ch.4 The abdomen, p.99
  6. "Anatomy of the Female Pelvis - D. El-Mowafi". Retrieved 2007-12-03.
  7. Drake et al. (2009) Grays Anatomy for Students, 2nd Edition, ch.5 Pelvis and perineum - general description, p.406
  8. Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. p. 190. ISBN 3-13-533305-1.
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