Anatomy of the Pelvis
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Questions and Answers

What is the function of the pelvis in the human body?

The pelvis protects and supports the viscera in the inferior part of the ventral body cavity.

What is the pelvic girdle composed of?

The left and right ossa coxae.

At what angle is the pelvis when a person is standing upright?

Anteriorly.

What are the three bones that fuse to form each os coxae?

<p>Ilium, ischium, and pubis.</p> Signup and view all the answers

What is the joint where the os coxae articulates with the sacrum?

<p>Sacroiliac joint.</p> Signup and view all the answers

What is the deep, curved depression on the lateral surface of the os coxae where the femur articulates?

<p>Acetabulum.</p> Signup and view all the answers

What is the term used to describe the complete pelvis?

<p>Pelvis.</p> Signup and view all the answers

At what age do the three bones (ilium, ischium, and pubis) fuse to form the single os coxae?

<p>Between 13 and 15 years of age.</p> Signup and view all the answers

What is the name of the curved surface of the acetabulum that articulates with the femoral head?

<p>Lunate surface</p> Signup and view all the answers

Compare and contrast the glenoid cavity of the scapula with the acetabulum of the os coxae.

<p>The glenoid cavity is shallower and more vulnerable to dislocation, while the acetabulum is deeper and more stable.</p> Signup and view all the answers

What is the name of the depression on the medial surface of the ilium?

<p>Iliac fossa</p> Signup and view all the answers

What are the attachment sites for the gluteal muscles of the buttock?

<p>Anterior, posterior, and inferior gluteal lines</p> Signup and view all the answers

What is the name of the large, roughened area on the posteromedial side of the ilium?

<p>Auricular surface</p> Signup and view all the answers

What are the names of the spines located inferiorly to the ala of the ilium?

<p>Anterior inferior iliac spine and posterior inferior iliac spine</p> Signup and view all the answers

What is the name of the prominent triangular spine that projects medially posterior to the acetabulum?

<p>Ischial spine</p> Signup and view all the answers

What are the names of the rami that fuse anteriorly to form the ischiopubic ramus?

<p>Ramus of ischium and inferior pubic ramus</p> Signup and view all the answers

What is the name of the space in the os coxae that is encircled by both pubic and ischial rami?

<p>Obturator foramen</p> Signup and view all the answers

What three bones fuse to form the os coxae?

<p>Ilium, ischium, and pubis</p> Signup and view all the answers

What is the name of the bony ridge that subdivides the pelvis into a true pelvis and a false pelvis?

<p>The pelvic brim</p> Signup and view all the answers

What is the name of the space enclosed by the pelvic brim?

<p>The pelvic inlet or superior pelvic aperture</p> Signup and view all the answers

What is the function of the ischial tuberosities?

<p>They form part of the pelvic outlet and provide a site for muscle attachment</p> Signup and view all the answers

What is the name of the inferiorly placed opening bounded by the coccyx, ischial tuberosities, and the inferior border of the symphysial surface?

<p>The pelvic outlet or inferior pelvic aperture</p> Signup and view all the answers

Why is the width and size of the pelvic outlet important for pregnancy?

<p>To accommodate the fetal head during childbirth</p> Signup and view all the answers

What is the most reliable indicator of sex in the human body?

<p>The pelvis, primarily the ossa coxae</p> Signup and view all the answers

How does the shape and orientation of the female-like ilium differ from that of a male-like ilium?

<p>A female-like ilium flares more laterally, whereas a male-like ilium projects more superiorly</p> Signup and view all the answers

What is the name of the depression or groove found between the greater sciatic notch and the sacroiliac articulation in females?

<p>The preauricular sulcus</p> Signup and view all the answers

How does the acetabulum project in females compared to males?

<p>In females, the acetabulum projects more laterally, whereas in males, it projects more anteriorly</p> Signup and view all the answers

What is the name of the body region formed by the pelvic outlet?

<p>The perineum</p> Signup and view all the answers

How does the subpubic angle differ between females and males?

<p>In females, the subpubic angle is wider and more convex, usually greater than 100 degrees, whereas in males, it is narrower and typically less than 90 degrees.</p> Signup and view all the answers

What is the significance of the shape of the bony pelvis in relation to childbirth?

<p>The shape of the bony pelvis is strongly correlated with whether an expectant mother will have a difficult labor and delivery.</p> Signup and view all the answers

How does the auricular surface of the ilium change with age?

<p>The auricular surface changes from a billowing texture with a fine-grained surface in young adults to a flattened surface with a coarse and granular texture in older individuals, and may develop bony lipping in much older individuals.</p> Signup and view all the answers

What is the significance of the symphysial surface of the pubis in estimating age at death?

<p>The symphysial surface undergoes uniform, age-related changes, making it a reliable indicator for estimating age at death.</p> Signup and view all the answers

What is the difference in the shape of the pubis between females and males?

<p>In females, the pubis is longer and more rectangular, whereas in males, it is shorter and triangular.</p> Signup and view all the answers

How does the greater sciatic notch differ between females and males?

<p>In females, the greater sciatic notch is wide and shallow, whereas in males, it is narrow and U-shaped.</p> Signup and view all the answers

What is the difference in the shape of the sacrum between females and males?

<p>In females, the sacrum is shorter and wider with a flatter sacral curvature, whereas in males, it is narrower and longer with a more curved sacral curvature.</p> Signup and view all the answers

How does the ischial spine differ between females and males?

<p>In females, the ischial spine rarely projects into the pelvic outlet, whereas in males, it frequently projects into the pelvic outlet.</p> Signup and view all the answers

What is the significance of the ossa coxae in estimating age at death?

<p>The ossa coxae are an excellent indicator of age at death, with age-related changes occurring in the auricular surface of the ilium and the symphysial surface of the pubis.</p> Signup and view all the answers

What is the difference in the overall shape of the pelvis between females and males?

<p>In females, the pelvis is wider and more oval, whereas in males, it is narrower and more heart-shaped.</p> Signup and view all the answers

Study Notes

The Pelvic Girdle and Its Functions

  • The adult pelvis consists of four bones: the sacrum, coccyx, and the right and left ossa coxae (hip bones).
  • The pelvic girdle refers to both the left and right ossa coxae only.
  • The pelvis protects and supports the viscera in the inferior part of the ventral body cavity.

Os Coxae

  • The os coxae is formed from three separate bones: the ilium, ischium, and pubis, which fuse between 13 and 15 years of age.
  • Each os coxae articulates posteriorly with the sacrum at the sacroiliac joint.
  • The femur articulates with the acetabulum, a deep, curved depression on the lateral surface of the os coxae.

Features of Os Coxae

  • The ilium:
    • Forms the superior region of the os coxae and part of the acetabular surface
    • Has a fan-shaped portion called the ala, which terminates inferiorly at the arcuate line
    • Has an iliac fossa on the medial side
    • Has gluteal lines on the lateral surface for attachment of gluteal muscles
    • Has an auricular surface for articulation with the sacrum
  • The ischium:
    • Fuses with the ilium near the superior and posterior margins of the acetabulum
    • Has an ischial spine that projects medially
    • Has a body and a lesser sciatic notch
    • Has an ischial tuberosity that supports the weight of the body when seated
  • The pubis:
    • Fuses with the ilium and ischium at the acetabulum
    • Has a ramus that fuses with the inferior pubic ramus to form the ischiopubic ramus
    • Has a body and a superior pubic ramus
    • Has an obturator foramen that is covered with a connective tissue membrane

True and False Pelves

  • The pelvic brim is a continuous, oval ridge that extends from the pubic crest, pectineal line, and arcuate line to the rounded inferior edges of the sacral ala and promontory.
  • The true pelvis lies inferior to the pelvic brim and encloses the pelvic cavity.
  • The false pelvis lies superior to the pelvic brim and forms the inferior region of the abdominal cavity.
  • The pelvic inlet is the space enclosed by the pelvic brim, whereas the pelvic outlet is the inferior opening in the true pelvis.

Sexually Dimorphic Features of the Pelvis

  • The ossa coxae are the most sexually dimorphic bones of the body due to the demands of pregnancy and childbirth.
  • Female pelvis:
    • Shallower and wider than the male pelvis
    • Has a wider and more convex subpubic angle
    • Has a longer body of the pubis
    • Has a preauricular sulcus
    • Has a shorter and wider sacrum
  • Male pelvis:
    • Narrower and more massive than the female pelvis
    • Has a narrower and U-shaped greater sciatic notch
    • Has a larger and oval obturator foramen
    • Has a shorter and more triangular body of the pubis
    • Has a narrower and V-shaped subpubic angle

Age Differences in the Ossa Coxae

  • The ossa coxae are an excellent indicator of both sex and age.
  • Age-related changes to the auricular surface of the ilium:
    • In young adults, the surface has a billowing texture
    • In older adults, the surface becomes more coarse and granular, with bony lipping and osteoarthritic changes
  • Age-related changes to the symphysial surface of the pubis:
    • In young adults, the surface is billowed, and no well-formed rim is found
    • In older adults, the surface becomes more flattened, and a bony rim forms around the circumference
    • In older adults, the surface becomes depressed and concave, with pitting and bony lipping.

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Description

This quiz covers the bones and structures that make up the pelvis, including the pelvic girdle and os coxae. It also explores the articulations and joints involved in the pelvis.

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