Osteology and Muscles of the Urogenital and Pelvic Diaphragms

Question 1

Outline of Lecture by Dr. B Wright:

Answer 1

> Primarily focus on muscles of the urogenital and pelvic diaphragm.
Visit general structural anatomy of the external genitalia.
Demonstrate relationships between the perineum and the pudendal vessels and nerve.

Question 2

Which two triangles makes up the perineum?

Answer 2

• Urogenital triangle

- Anal triangle

Question 3

What are the bony landmarks that make up the perineum?

Answer 3

Pubic symphysis - ischial tuberosity - coccyx - ischial tuberosity - pubic symphysis.

Question 4

What does the line at the center point of the perineum separate?

Answer 4

The urogenital triangle and anal triangle.

Question 5

What are the bony land marks of the urogenital triangle (anterior triangle of perineum)?

Answer 5

Pubic symphysis - ischial tuberosity - ischial tuberosity - pubic symphysis.

Question 6

What are the bony land marks of the anal triangle (posterior triangle of perineum)?

Answer 6

Coccyx - ischial tuberosity - ischial tuberosity - coccyx.

Question 7

What is the difference in the shape of the pelvic opening between male and female?

Answer 7

Male -> heart-shaped

Female -> oval shaped

Question 8

What is the difference in the shape of the obturator foramen between male and female?

Answer 8

Male -> round obturator foramen

Female -> oval obturator foramen

Question 9

What is the difference in the subpubic arch between male and female?

Answer 9

Male -> narrow subpubic arch (less than 70 degrees)

Female -> wide subpubic arch (more than 80 degrees)

Question 10

Does males or females have a thicker and heavier pelvis?

Answer 10

Male -> thicker and heavier pelvis

Female -> thinner and lighter pelvis

Question 11

Compare the differences in the acetabulum between males and females.

Answer 11

Male -> larger acetabulum in males.

Female -> smaller acetabulum in females.

Question 12

Compare the difference in the greater sciatic notch between males and females.

Answer 12

Male -> greater sciatic notch is a narrow, inverted V.

Female -> greater sciatic notch is almost 90 degrees.

Question 13

Is the android type shape of the pelvic opening more common in males or females?

Answer 13

Android is more common in males.

Question 14

What is the common type of shape in the pelvic opening in females?

Answer 14

Gynecoid pelvis is the “normal” female “type”.

Question 15

What are the 2 non-diaphragmatic pelvic muscles?

Answer 15

> obturator internus

> piriformis

Question 16

You know that the obturator internus is one of the two non-diaphragmatic pelvic muscles, but where are its two attachments?

Answer 16

Obturator internus:
> from the internal surface of the obturator membrane.
> to the greater trochanter on the femur.

Question 17

You know that the piriformis is one of the two non-diaphragmatic pelvic muscles, but where are its two attachments?

Answer 17

Piriformis:
> from the internal surface of the sacrum (surrounding the ventral rami)

> to the greater trochanter on the femur.

Question 18

What common attachment site does both of the non-diaphragmatic pelvic muscles share?

Answer 18

Greater trochanter on the femur.

Question 19

What is the perineum?

Answer 19

The surface area of the trunk between the thighs and the buttocks.

Question 20

What muscles make up the pelvic diaphragm?

Answer 20

Pelvic Diaphragm = coccygeus + levator ani

levator ani: pubococcygeus + puborectalis + iliococcygeus

Question 21

What muscles make up the levator ani?

Answer 21

• pubococcygeus
• puborectalis
• iliococcygeus

Question 22

What are the attachment sites for the coccygeus?

Answer 22

From ischial spine to inferior sacrum and coccyx.

Question 23

Does the coccygeus lie directly posterior or anterior to the sacrospinous ligament?

Answer 23

Lies directly anterior to the sacrospinous ligament.

Question 24

What are the attachments of the iliococcygeus?

Answer 24

Posterior tendinous arch to blend with anococcygeal ligament.

Question 25

What ligament does the iliococcygeus blend with?

Answer 25

Blends with anococcygeal ligament.

Question 26

What are the attachments of the pubococcygeus?

Answer 26

From the pubic ramus to coccyx and anococcygeal ligament.

Question 27

What does the puborectalis form a loop around?

Answer 27

The anus.

Question 28

What diaphragmatic muscle is the pubovaginalis (female) and the puboprostaticus (male) a subdivision of?

Answer 28

Pubococcygeus

Question 29

What makes up the pelvic diaphragm?

Answer 29

• puborectalis
• pubococcygeus
• iliococcygeus
• coccygeus
• anococcygeal raphe and ligament (body)

puborectalis, pubococcygeus, and iliococcgeus make up the levator ani

Question 30

True of False:

Some fibers of the puborectalis loop around (and help to support) the vagina or the prostate (pubovaginalis or puboprostaticus subdivisions).

Answer 30

True

Question 31

What is the tendinous arch of the levator ani muscles derived from?

Answer 31

The obturator internus fascia.

Question 32

In the anal triangle, what is the ischioanal fossa(e)?

Answer 32

Wedge-shaped area between skin and the inferior surface of the pelvic diaphragm.

usually filled with fat and loose connective tissue

Question 33

What is the ischioanal fossa(e) usually filled with?

Answer 33

fat and loose connective tissue

Question 34

What are the boundaries of the ischioanal fossa(e)?

Answer 34

> Lateral:

• ischium
• obturator internus with fascia

> Medial:
- external anal sphincter with levator ani muscle

> Posterior:

• sacrotuberous ligament
• edge of gluteus maximus

> Anterior:

• urogenital triangle
• anterior recesses of the ischioanal fossa

Question 35

Which boundary of the ischioanal fossa(e) is made up by the ischium and obturator internus with fascia?

Answer 35

lateral boundary

Question 36

Which boundary of the ischioanal fossa(e) is made up by the external anal sphincter with levator ani muscle?

Answer 36

medial boundary

Question 37

Which boundary of the ischioanal fossa(e) is made up by the sacrotuberous ligament and edge of gluteus maximus?

Answer 37

posterior boundary

Question 38

Which boundary of the ischioanal fossa(e) is made up by the urogenital trangle and anterior recesses of the ischioanal fossa?

Answer 38

anterior boundary

Question 39

In what muscle is the pudendal canal located?

Answer 39

Obturator internus with pudendal canal.

Question 40

What travels through the pudendal canal?

Answer 40

• internal pudendal artery
• internal pudendal vein
• pudendal nerve