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Questions and Answers
What is the main function of the pelvic diaphragm?
What is the main function of the pelvic diaphragm?
What type of joint is the symphysis pubis?
What type of joint is the symphysis pubis?
What is the shape of the pelvic inlet in females?
What is the shape of the pelvic inlet in females?
What forms the posterior boundary of the pelvic inlet?
What forms the posterior boundary of the pelvic inlet?
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What is the ligament that connects the two pubic bones along the upper border of the symphysis pubis?
What is the ligament that connects the two pubic bones along the upper border of the symphysis pubis?
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What is the region below the pelvic diaphragm?
What is the region below the pelvic diaphragm?
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What is the boundary of the pelvic outlet anteriorly?
What is the boundary of the pelvic outlet anteriorly?
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What is the function of the sacrotuberous ligament?
What is the function of the sacrotuberous ligament?
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What type of joint is the sacroiliac joint?
What type of joint is the sacroiliac joint?
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What is the function of the piriformis muscle?
What is the function of the piriformis muscle?
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Which of the following is NOT an origin point of the Levator Ani muscle?
Which of the following is NOT an origin point of the Levator Ani muscle?
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What is the function of the sacrotuberous ligament?
What is the function of the sacrotuberous ligament?
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What is the main function of the Puborectalis muscle?
What is the main function of the Puborectalis muscle?
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What is the location of the anterior pubic ligament?
What is the location of the anterior pubic ligament?
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What changes occur in the sacroiliac ligaments during late stages of pregnancy?
What changes occur in the sacroiliac ligaments during late stages of pregnancy?
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Which nerve branch supplies the Levator Ani muscle?
Which nerve branch supplies the Levator Ani muscle?
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What is the insertion point of the Pubococcygeus proper muscle?
What is the insertion point of the Pubococcygeus proper muscle?
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What type of joint is the sacrococcygeal joint?
What type of joint is the sacrococcygeal joint?
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What is the action of the obturator internus muscle?
What is the action of the obturator internus muscle?
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What is the action of the Coccygeus muscle?
What is the action of the Coccygeus muscle?
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What is the location of the sacrospinous ligament?
What is the location of the sacrospinous ligament?
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Which of the following is an action of the Levator Ani muscle?
Which of the following is an action of the Levator Ani muscle?
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What is the origin point of the Coccygeus muscle?
What is the origin point of the Coccygeus muscle?
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In females, the Levator Ani muscle also serves as a sphincter of which organ?
In females, the Levator Ani muscle also serves as a sphincter of which organ?
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Study Notes
Pelvic Bones
- The pelvis is formed by 2 hip bones anteriorly and laterally, and the sacrum and coccyx posteriorly
- The pelvic inlet (brim) is triangular or heart-shaped in males and transversely oval in females
- Boundaries of the pelvic inlet include the promontory and alae of the sacrum, arcuate lines, and pectineal lines
- The pelvic outlet is bounded by the symphysis pubis, tip of the coccyx, ischial tuberosities, ischiopubic rami, and sacrotuberous ligaments
Pelvic Cavity
- The pelvic cavity lies between the inlet and outlet
- It is divided into two parts by the pelvic diaphragm: the pelvis above the diaphragm and the perineum below
Joints and Ligaments of the Pelvis
- Symphysis pubis: a secondary cartilaginous joint between the two pubic bones
- Ligaments: superior pubic ligament, inferior pubic ligament, anterior pubic ligament, and posterior pubic ligament
- Sacroiliac joint: a strong weight-bearing plane synovial joint between the auricular surfaces of the sacrum and ilium
- Ligaments: anterior, posterior, and interosseous sacroiliac ligaments
- Accessory ligaments: sacrotuberous ligament and sacrospinous ligament
- Sacrococcygeal joint: a secondary cartilaginous joint between the last piece of sacrum and first piece of coccyx
Pelvic Muscles
- Muscles of the posterior wall: piriformis
- Nerve supply: branches from the sacral plexus
- Action: lateral rotator of the femur at the hip joint
- Muscles of the lateral walls: obturator internus
- Nerve supply: nerve to obturator internus from the sacral plexus
- Action: lateral rotator of the femur at the hip joint
- Muscles of the floor: levator ani and coccygeus
- Levator ani: divided into pubococcygeus and iliococcygeus
- Pubococcygeus: puborectalis, levator prostatae (in males) or sphincter vaginae (in females), and pubococcygeus proper
- Iliococcygeus: inserted into the side of the coccyx and the anococcygeal raphe
- Coccygeus: origin is the tip of the ischial spine
- Levator ani: divided into pubococcygeus and iliococcygeus
Nerve Supply and Action of Pelvic Muscles
- Levator ani:
- Nerve supply: perineal branch of S4 and perineal branch of the pudendal nerve
- Action: supports and maintains the pelvic viscera in position, increases intra-abdominal pressure during straining, and has a sphincter action on the ano-rectal junction; in females, it also serves as a sphincter of the vagina
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Description
This quiz covers the anatomy of the pelvis, including the bony pelvis, pelvic joints, ligaments, and muscles. It is designed for students of medicine and anatomy.
