9.2 Osteology, Arthrology, and Musculature of the Pelvis Flashcards
By what age do the three bones of the os coxi fuse?
7-9
By what age does the acetabulum completely fuse?
20-25
What is the name of the foramen between the superior and inferior pubic rami?
Obturator foramen
What are some differences between the female and male pelvis?
In women:
- Larger inlet and outlet
- Wider pubic angle (~90°)
- Wider ilium wings
- Shallower sacrum concavity
What kind of joint is the sacroiliac joint? Describe some characteristics of it
- Synovial joint: fibrous capsule, synovial membrane, synovial fluid etc.
- Many ligaments to stabilize the joint
Describe 4 openings of the pelvis
- Greater sciatic foramen (by notch)
- Lesser sciatic foramen (by notch)
- Obturator canal (hole in membrane in obturator foramen
- Deep to inguinal ligament
Which two muscle groups combine to form the pelvic diaphragm?
- Levator ani
- Coccygeus
Describe the origin, insertion, and function of the coccygeus muscle, including where the “base” and “apex” are.
Origin: Ischial spine (apex)
Insertion: lateral coccyx and sacrum (base)
Function: forms part of the pelvic floor, supports pelvic organs.
What are the three fibre groups within the levator ani?
- Iliococcygeus
- Pubococcygeus
- Puborectalis
Which ligament anchors the external anal sphincter to the coccyx?
Anococcygeal ligament
Origin and insertion of iliacus and psoas
Iliacus: originates in iliac fossa, inserts in lesser trochanter
Psoas: originates T12-L5, inserts lesser trochanter
Action (both): hip flexion
Origin, insertion, and action of the piriformis
Origin: anterior sacrum
Insertion: Greater trochanter
Action: External rotation
Obturator internus origin, insertion, and action
Origin: Internal surface of obturator foramen
Insertion: Greater trochanter
Action: External rotation
