Non-reproductive features of the Pelvis and Perineum

Question 1

What type of joint in the sacroiliac joint?

Answer 1

Synovial Joint

Question 2

What type of joint is the pubic symphysis?

Answer 2

Secondary cartilaginous joint

Question 3

What are the three main parts of the pelvis?

Answer 3

Ischium, pubic, ilium

Question 4

What is the name of the surface that articulates with the head of the femur?

Answer 4

Acetabular fossa

Question 5

What is considered the ‘true pelvis’?

Answer 5

Within the pelvic inlet.

Question 6

What constitutes the pelvic wall?

Answer 6

Sacrum, coccyx and pelvic bones

Question 7

What are the two main ligaments in the true pelvis?

Answer 7

Sacrospinous (sacrum to the ischial spine)

Sacrotuberous (sacrum to the ischial tuberosity)

Question 8

Describe the orientation of the pelvic cavity.

Answer 8

The axis of the pelvic cavity is at a 45 degree angle to the axis of the abdominal cavity

Question 9

Which muscle lines most of the pelvic bone facing the pelvic cavity?

Answer 9

Obturator internus

Question 10

Where does the obturator internus insert and what other muscle inserts here?

Answer 10

Medial surface of the greater trochanter of the femur - the piriformis also inserts here

Question 11

What muscle overlays the sacrospinous ligament?

Answer 11

Coccygeus muscle

Question 12

What are the three main muscles of the pelvic floor and what are they called collectively?

Answer 12

Iliococcygeus muscle
Pubococcygeus muscle
Puborectalis muscle
These muscles make up Levator Ani

Question 13

What forms the border between the obturator internus and the levator ani?

Answer 13

Tendinous arch of obturator internus fascia

Question 14

What other ligament is found in these group of muscles?

Answer 14

Anococcygeal ligament

Question 15

What is the nerve supply to the levator ani?

Answer 15

Pudendal nerve (S2-S4) and directly from S4

Question 16

What are the openings in the levator ani?

Answer 16

Urethra, vagina(Only in female)

and anus

Question 17

What is the structure that is formed by the levator ani and what does this structure do?

Answer 17

Pelvic diaphragm.

Supports the main pelvic viscera (bladder, rectum uterus, )
Below the diaphragm is the perineum, containing voluntary sphincters and external genitalia

Question 18

What is the name of the fat-filled space between the levator ani and the obturator internus in a male?

Answer 18

Ischio-anal fossa

Question 19

What are the two sphincters in the urethra of a male?

Answer 19

Internal urethral sphincter (smooth muscle)

External urethral sphincter(skeletal muscle)

Question 20

What are the four parts of the male urethra? How long is it?

Answer 20

Preprostatic, prostatic, membranous and spongy

20 cm

Question 21

Describe the arrangement of the uterus and the bladder in women.

Answer 21

The uterus sits on top of the bladder

Question 22

What is different about the urethral sphincters in women?

Answer 22

Women have a poorly organised internal sphincter.

External urethral sphincter is skeletal muscle surrounding the urethra in the deep perineal pouch.

Question 23

Where is the external urethral sphincter of women found?

Answer 23

In the deep perineal pouch

Question 24

What are two additional groups of muscle found in females?

Answer 24

Sphinter urethrovaginalis

Compressor urethrae

Question 25

Describe the shape of an empty bladder.

Answer 25

Tetrahedral

Question 26

What are the structures are each corner of the tetrahedron?

Answer 26

The posterior vertices have the ureters coming from them , 2 ureters. The anterior vertex has the median umbilical ligament. The posterior inferior vertex has the urethra coming from it.
Superior surface covered in peritoneum
Expands between transversalis fascia and lining peritoneum
Smooth muscle sphincter (vesicae) at neck
Skeletal muscle sphincter (urethrae) in perineum

Question 27

Describe the structure of the rectum.

Answer 27

It has a double S bend. There are three transverse rectal folds (superior, middle and inferior).probably functioning as an anti-gravity device keeping load off the sphincter

Question 28

What vessels supply the rectum?

Answer 28

Superior, middle and inferior rectal arteries

Question 29

Which nerves supply the rectum and which nerves supply the anal canal?

Answer 29

Rectum - autonomic nerves
Anal canal - somatic nerves
The rectum is supplied by the autonomic NS and is mainly sensitive to filling. The anal canal is supplied by somatic nerves and is extremely sensitive to injury.

Question 30

Which muscle is most important for faecal continence and what does it do?

Answer 30

Puborectalis muscle (wraps round the rectum) - it puts a sharp angle into the recto-anal junction.

Question 31

What could badly injure this muscle?

Answer 31

Episiotomy

Question 32

What main blood vessels supply all the pelvic organs?

Answer 32

Internal iliac artery

Internal iliac artery has anterior and posterior divisions

Question 33

What is the auricular surface? What type of joint forms between the two?

Answer 33

The surfaces of the ilium and sacrum that articulate with each other - a synovial joint forms between the two

Question 34

how long is the urethra in females and vagina?

Answer 34

4 cm

vagina- 8-12 cm

Question 35

What passes through the greater foramen?

What passes through the lesser foramen?

Answer 35

Sciatic Nerve
Pudendal Nerve (into pelvis)

Question 36

what does the sacral formaina allow?

Answer 36

Sacral foramina allow for passage of sacral nerves

Question 37

how to measure pelvic inlet size?

Answer 37

Sacral promontory -> to the superior margin of the pubic bone
around 10-12cm*
Distance between the ischial spines
Around 9.5-11.5cm*

Question 38

what are the layers of the bladder

Answer 38

Outer layer: serosa
Smooth muscle layer: detrusor muscle
Parasympathetic nerve supply
In males: second circularly-arranged smooth muscle layer in the urethral trigone, forming the internal urethral sphincter, to prevent retrograde ejaculation*
Inner layer: transitional epithelium