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?
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What is the joint where the os coxae articulates with the sacrum?
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What is the deep, curved depression on the lateral surface of the os coxae where the femur articulates?
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What is the term used to describe the complete pelvis?
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At what age do the three bones (ilium, ischium, and pubis) fuse to form the single os coxae?
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What is the name of the curved surface of the acetabulum that articulates with the femoral head?
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Compare and contrast the glenoid cavity of the scapula with the acetabulum of the os coxae.
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What is the name of the depression on the medial surface of the ilium?
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What are the attachment sites for the gluteal muscles of the buttock?
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What is the name of the large, roughened area on the posteromedial side of the ilium?
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What are the names of the spines located inferiorly to the ala of the ilium?
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What is the name of the prominent triangular spine that projects medially posterior to the acetabulum?
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What are the names of the rami that fuse anteriorly to form the ischiopubic ramus?
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What is the name of the space in the os coxae that is encircled by both pubic and ischial rami?
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What three bones fuse to form the os coxae?
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What is the name of the bony ridge that subdivides the pelvis into a true pelvis and a false pelvis?
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What is the name of the space enclosed by the pelvic brim?
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What is the function of the ischial tuberosities?
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What is the name of the inferiorly placed opening bounded by the coccyx, ischial tuberosities, and the inferior border of the symphysial surface?
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Why is the width and size of the pelvic outlet important for pregnancy?
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What is the most reliable indicator of sex in the human body?
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How does the shape and orientation of the female-like ilium differ from that of a male-like ilium?
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What is the name of the depression or groove found between the greater sciatic notch and the sacroiliac articulation in females?
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How does the acetabulum project in females compared to males?
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What is the name of the body region formed by the pelvic outlet?
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How does the subpubic angle differ between females and males?
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What is the significance of the shape of the bony pelvis in relation to childbirth?
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How does the auricular surface of the ilium change with age?
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What is the significance of the symphysial surface of the pubis in estimating age at death?
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What is the difference in the shape of the pubis between females and males?
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How does the greater sciatic notch differ between females and males?
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What is the difference in the shape of the sacrum between females and males?
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How does the ischial spine differ between females and males?
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What is the significance of the ossa coxae in estimating age at death?
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What is the difference in the overall shape of the pelvis between females and males?
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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.