Lecture 20: Pelvis And Pelvic Diaphragm

Question 0

Pelvic inlet has three diameters what are these?

Answer 0

• Conjugate (true, fixed) diameter
• Transverse diameter
• Oblique diameter

Question 1

Pelvic girdle is made of what?

Answer 1

coxal bones + sacrum, connects vertebral column to two femurs.

Question 2

The pelvic outlet (inferior pelvic aperture) is bounded by?

Answer 2

• Pubic arch anteriorly.
• Ischial tuberosities laterally.
• Inferior margin of the sacrotuberous ligament posterolaterally.
• Tip of the coccyx posteriorly.

Question 3

Pelvic diaphragm Consists of which muscles muscles?

Answer 3

• Coccygeus
• Iliococcygeus
• Pubococcygeus

• Puborectalis
( last three are levator ani)

Question 4

Piriformis muscle

Origin, insertion, action, Innervation

Answer 4

Origin: anterior surface of sacrum

Insertion: greater trochanter of the femur

Actions: laterally rotates the thigh at the hip joint. If thigh is first flexed approx. >60 degrees, piriformis becomes an abductor
and medial rotator of the thigh at the hip joint.

Innervation: nerve to piriformis

Question 5

Interosseous and posterior sacroiliac ligaments suspend?

Answer 5

sacrum between coxal bones (ilia).

Question 6

Interosseous SI ligaments are primary structures involved in transferring weight from what to where?

Answer 6

axial skeleton to ilia.

Question 7

Posterior SI ligaments fan superolaterally from?

Answer 7

sacrum to ilia.

Question 8

Weight bearing down on sacrum draws ilia ……. , locking

sacrum in place between them.

Answer 8

medially

Question 9

Study ligaments!!

Answer 9

Do it!

Question 10

What is the functional significance of this passage between piriformis and coccygeus muscles?

Answer 10

Sciatic nerve passage way

Question 11

What is the Innervation to the external anal and urethral sphincters?

Answer 11

Pudendal nerve