Nutation, Counternutation and differences in pelves

Question 1

3 factors that impact joint stability?

Answer 1

• Shape of bones.
• Muscles that cross that joint.
• Ligaments that cross the joint.

Question 2

What is nutation?

Answer 2

• Refers to anterior movement of the sacrum with respoect to the pelvis.
• The upper body weight pushes down on the top and front of the sacrum.

Question 3

What is counternutation?

Answer 3

• Refers to the posterior movement of the sacrum with respect to the pelvis.
• The sacrum doesn’t move much because of the tight, strong ligament.

Question 4

What are the 2 sources of differences between male and female pelvises?

Answer 4

• Females have to transmit a baby at childbirth, therefore any structure that contributes to the pelvis inlet or outlet will be larger.
• Males are usually heavier and have larger muscles; therefore, any weight attached to muscles will be larger.

Question 5

What are 6 differences in male and female pelvises?

Answer 5

1. The female pubic angle is wider than males. It is more U-shaped; males are more acutely shaped.
2. Females’ pubic body and superior pubic ramus are wider. The acetabulum is larger in males.
3. Females have a wider sciatic notch.
4. Males’ pelvic inlet is more heart-shaped, while females is more rounded.
5. Males’ first sacral body is larger, while its alae are smaller.
6. The male auricular surface of the sacrum is larger than females.