Appendicular Skeleton: Pelvic Girdle

Question 1

Pelvis

Answer 1

Includes both appendicular and axial bones (sacrum and coccyx)

“Hip bones” + sacrum + coccyx = pelvis

Attaches the lower limbs to spine (body weight passes through girdle to lower part of axial skeleton) and supports viscera

Strong attachment to axial skeleton at sacroiliac joint (very stable)

Less freedom of movement compared to pectoral girdle

Question 2

Os coxae

Answer 2

Os coxae is composed of 3 bones: ilium, ischium, and pubis. These fuse by adulthood

Acetabulum is lateral socket where the head of femur articulates. Composed of all 3 pelvic bones.

2 hip bones join to each other anteriorly at the pubic symphysis

Question 3

Pelvic Inlet and Pelvic Outlet

Answer 3

Pelvic Inlet defines the boundary between pelvic and abdominal cavities (or greater and lesser pelvis; or true and false pelvis)

Pelvic Brim: edge of pelvic inlet

Pelvic Outlet: inferior opening defined by ischial tuberosities (it’s the bony feature you sit on).

The size of this outlet and inlet is important for a successful birth

Question 4

Males vs Females

Answer 4

Males:

• -pelvis is narrower
• -pelvic inlet more heart shaped

Females:
–pelvis typically wider and shallower - this allows for birth

*Note the angle of sacrum and coccyx of female vs male