true pelvis

Examples of true pelvis in the following topics:

• False and True Pelves

  • The false (greater) pelvis is larger and superior to the true (lesser) pelvis where the pelvic inlet is located.
  • Depending on what is included in the description these groupings are often termed true (lesser) or false (greater) pelves.
  • The true (or lesser) pelvis is bounded in front and below by the pubic symphysis and the superior rami of the 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.
  • The true pelvis contains the pelvic colon, rectum, bladder, and some of the reproductive organs.
  • The greater pelvis (yellow) is larger and superior to the lesser pelvis (red) where the pelvic inlet is located.

• Comparison of Female and Male Pelves

  • The female pelvis has evolved to its maximum width for childbirth and the male pelvis has been optimized for bipedal locomotion.
  • A wide pelvis is beneficial for child birth, however a narrow pelvis is beneficial for locomotion when walking upright.
  • The female pelvis has evolved to its maximum width for childbirth—a wider pelvis would make women unable to walk.
  • The female pelvis is larger and broader than the male pelvis, which is taller (owing to a higher iliac crest), narrower, and more compact.
  • This causes the sides of the male pelvis to converge from the inlet to the outlet, whereas the sides of the female pelvis are wider apart.

• Pelvic Structure and Childbearing

  • The human pelvis is narrower and smaller than that of our closest living relatives, the apes.
  • These changes in the pelvis enable bipedal locomotion, or upright walking.
  • This narrowing of the pelvis has also affected the way humans give birth, as a narrow pelvis makes it more difficult for an infant to move through the birth canal.
  • Since the pelvis is vital for both efficient locomotion and childbirth, natural selection has been forced to strike a compromise between a wide pelvis to facilitate birthing large-brained infants and having a narrow pelvis to increase locomotive efficiency.
  • The female pelvis is wider than that of the male, as can be seen by the greater than 90 degree angle of the pubic arch.

• Veins of the Abdomen and Pelvis

  • The major veins of the abdomen and pelvis return deoxygenated blood from the abdomen and pelvis to the heart.
  • A number of veins remove deoxygenated blood from the abdomen and pelvis.
  • The external iliac vein, the upward continuation of the femoral vein, passes upward along the pelvis and ends to form the common iliac vein.The tributaries of the external iliac vein are the inferior epigastric, deep iliac circumflex, and pubic veins.
  • The internal iliac vein begins near the upper part of the greater sciatic foramen, the large opening at the rear of the pelvis, passes upward behind and slightly medial to the internal iliac artery and, at the brim of the pelvis, joins with the external iliac vein to form the common iliac vein.
  • They drain blood from the pelvis and lower limbs.

• Pelvimetry

  • Though less common now, pelvimetry was once common as the assessment of the female pelvis for the successful delivery of a baby.
  • Pelvimetry is the assessment of metrics of the female pelvis as it pertains to the delivery of a baby.
  • Clinical pelvimetry attempts to assess the pelvis by clinical examination.
  • This may be due to a small pelvis, a nongynecoid pelvic formation, a large fetus, or a combination of these factors.
  • Explain the reasons why pelvimetry, the measurement of the pelvis, is used less frequently in obstetrics

• Arteries of the Pelvis and Lower Limbs

  • The pelvic cavity is largely supplied by the paired internal iliac arteries, formed when the common iliac artery divides the internal iliac artery at the vertebral level L5 descends inferiorly into the lesser pelvis.
  • At the most superior border of the greater sciatic foramen, the large opening to the rear of the pelvis, the internal iliac artery divides into anterior and posterior trunks.
  • The anterior trunk gives rise to numerous arteries that supply the organs of the pelvis and the gluteal and adductor muscles of the leg.
  • Outline blood flow in the arteries of the pelvis and lower limbs

• Ilium

  • The ilium is the uppermost and largest bone of the pelvis.
  • The ilium is the uppermost and largest bone of the pelvis.
  • The internal surface of the body forms part of the wall of the lesser pelvis and gives origin to some fibers of the obturator internus muscle.
  • In humans, bi-iliac width is an anatomical term referring to the widest measure of the pelvis between the outer edges of the upper iliac bones.
  • The ilium is the uppermost bone of the pelvis and extends laterally.

• Ischium

  • The ischium forms the lower and posterior portion of the hip bones of the pelvis.
  • Dorsally, the ramus contributes to the obturator foramen, a large opening in the pelvis through which key nervous and vascular vessels pass.
  • Left hip joint, opened by removing the floor of the acetabulum from within the pelvis.

• Pubis

  • The pubis is the lowest and most anterior portion of the hip bones of the pelvis.
  • The pubic bone forms the anterior region of the pelvis and contributes to the acetabulum, which articulates with the femoral head to form the hip joint.
  • The internal surface forms the wall of the lesser pelvis and is the point of origin for a portion of the obturator internus muscle.
  • Its internal surface enters into the formation of the wall of the lesser pelvis and gives origin to a portion of the obturator internus muscle.

• Muscles that Cause Movement at the Hip Joint

  • Attachments - Originates from the posterior of the pelvis and attaches to the femur.
  • Actions - Abducts and medially rotates the thigh and fixes the pelvis during walking.
  • Attachments - Originates from the pelvis and attaches to the femur.
  • Obturator Internus - The obturator internus lines the internal wall of the pelvis.
  • Attachments: Originates from the pelvis and femur and attaches to the fibula.