Pelvic Anatomy

Question 1

Describe the differences between the pelvic inlet and outlet

Answer 1

Question 2

What is the clinical importance of the ischial spine?

Answer 2

Landmark for pudendal nerve and can be used to assess progress of labour

Question 3

How can the progress of labour be assessed using the ischial spine?

Answer 3

Question 4

What is the clinical importance of the sacral promontory?

Answer 4

Question 5

What is the clinical importance of the iliopectineal ligament?

Answer 5

Question 6

Main differences between male and female pelvic anatomy

Answer 6

Question 7

What are the main joints of the pelvis

Answer 7

Sacroiliac and pubic symphysis

Question 8

How is the sacroiliac joint stabilised

Answer 8

NO MUSCLES, only ligaments holding it together - anterior ileo-sacral ligaments and the posterior Ileo-sacral ligaments

Question 9

What are the key features of the pubic symphysis

Answer 9

• Fibrocartilagenous disc - shock absorber (it can compress)
• There is a hormone called relaxin that allows more water to enter the ligaments and allows it to relax. The joints of the child do not detach but they slide over each other.

Question 10

What are the main ligaments in the female reproductive tract?

Answer 10

Broad, Ovarian and Uterine

Question 11

What is the broad ligament?

Answer 11

• a flat sheet of peritoneum, associated with the uterus, fallopian tubes and ovaries
• Extends from the lateral pelvic walls on both sides and folds over the internal female genitalia, covering their surface anteriorly and posteriorly

Question 12

What are the subdivisions of the broad ligament

Answer 12

Mesometrium (uterus), Mesovarium (ovaries) and Mesosalpinx (fallopan tube)

Question 13

What are the other ligaments located in the broad ligament?

Answer 13

Ovarian ligament

Round ligament of uterus

Suspensory ligament of ovary (aka infundibulopelvic ligament)

Question 14

Which ligaments are associated with the superior aspect of the uterus?

Answer 14

The broad ligament and round ligaments

Question 15

Which ligaments are associated with the middle aspect of the uterus?

Answer 15

cardinal, pubocervical and uterosacral ligaments

Question 16

Which structures support the uterus inferiorly?

Answer 16

levator ani, perineal membrane, perineal body

Question 17

Where are the Cardinal ligaments found?

Answer 17

Situated along the inferior border of the broad ligament, housing the uterine
artery and uterine veins

Question 18

What is the function of the pubocervical ligaments?

Answer 18

Bilateral structures attaching the cervix to the posterior surface of the pubic symphysis

Question 19

What is the function of the uterosacral ligaments?

Answer 19

Bilateral fibrous bands attaching the cervix to the sacrum posteriorly

Question 20

What is the innervation of the walls of organs in the pelvis?

Answer 20

PARASYMPATHETIC - smooth muscle walls

Question 21

Why is any pain in the walls of pelvic organs poorly localised?

Answer 21

Referred pain occurs because the sensory nerves transmit signals up the same tracts of the dermatomes - wherever it enters at a particular level, the pain comes from that equivalent dermatome.

Question 22

Where is most pain felt and why?

Answer 22

Most pain is felt in the MIDLINE – because the autonomic ganglia (SPLANCHIC NERVE GANGLiA) are near the vessels of the midline.

Question 23

What are the main muscles of the pelvic diaphragm?

Answer 23

levator ani (puborectalis, pubococcygeus, iliococcygeus) and coccygeus

Question 24

Damage to which muscle during delivery is a major cause of faecal incontinence?

Answer 24

Pubo-rectalis as normally, it puts a kink in the rectum which prevents faeces from exiting the rectum - this makes it more important than sphincters for faecal incontinence

Question 25

What is used to quantify and describe the degree of uterine prolapse?

Answer 25

Pelvic Organ Prolapse Questionnaire - POP-Q

Question 26

What are the nerve roots of the pudendal nerve?

Answer 26

S2-S4

Question 27

What does the pudendal nerve provide?

Answer 27

Motor to perineal muscles Somatosensory to perineum and external genitalia

Question 28

Why can a pudendal nerve block be useful prior to instrumental delivery?

Answer 28

Sensation in areas innervated by pudendal is usually specific and well localised so blocking it provides pain relief

Question 29

What are the anatomical borders of the perineum?

Answer 29

Anterior: pubic symphysis Posterior: tip of the coccyx Laterally: inferior pubic rami and inferior ischial rami, and the sacrotuberous ligament Roof: pelvic floor Base: skin and fascia

Question 30

What is the perineal body and where is it found?

Answer 30

An irregular fibromuscular mass located at the junction of the urogenital and anal triangles – the central point of the perineum.

Question 31

What is the function of the perineal body?

Answer 31

Acts as an attachment point for muscles from the pelvic floor and the perineum In women, it acts as a tear resistant body between the vagina and the external anal sphincter, supporting the posterior part of the vaginal wall against prolapse In the male, it lies between the bulb of penis and the anus.