Lecture 4 (B) - Pelvis

Question 1

What axis is the pelvis on?

Answer 1

Anterior-inferiorly inclined.

Question 2

What part makes up the majority of the pelvic girdle?

Answer 2

Iliac fossae - form shallow basins containing the lower abdominal viscera.

Question 3

What artery supplies most of the pelvic organs?

Answer 3

Internal iliac artery - does not supply the ovaries/testis, the pelvic walls or much of the gluteal region.

Question 4

Where can a synovial joint be found in the pelvic girdle?

Answer 4

At the sacro-iliac joint - marks the border between the sacral spinal cord and the pelvis.

Question 5

What is the pelvic wall composed of?

Answer 5

• Sacrum and coccyx
• Pelvic bones
• Sacrospinous and sacrotuberous ligaments

Question 6

Which two muscles are attached to the greater trochanter of the femur (highest point of femur)?

Answer 6

• Piriformis muscle

- Obturator internus muscle

Question 7

What muscle makes up the majority of the pelvic diaphragm?

Answer 7

Levator ani

Question 8

What does the pelvic diaphragm do?

Answer 8

Supports the pelvic organs (bladder, cervix, uterus and rectum/prostate in males) as well as forming the divide between the pelvic cavity and the perineum.

Question 9

What is found in the perineum?

Answer 9

Voluntary sphincters and external genitalia.

Question 10

Where are the openings in the elevator ani?

Answer 10

• Urethra
• Vagina
• Anal canal

Question 11

What is found between the vagina and the anus?

Answer 11

Perineal body (a fibromuscular mass)

Question 12

What is found inferior to the levator ani?

Answer 12

Perineal membrane (forms the inferior layer of fascia of the urogenital part of the pelvic diaphragm)

Question 13

What nerves innervate the pelvic diaphragm?

Answer 13

Via the pudendal nerves (S2-4) and directly by S4.

Question 14

How is the external urethral sphincter controlled?

Answer 14

Under voluntary control (skeletal muscle).

Question 15

How is the internal urethral sphincter controlled?

Answer 15

Under non-voluntary control (smooth muscle)

Question 16

What is the difference between the urethral sphincters in men and women?

Answer 16

• Internal urethral sphincter is not well organised in females
• There are two additional groups of muscles found in females (sphincter urethrovaginalis and compressor urethrae)

Question 17

Describe the structure of the bladder.

Answer 17

• Tetrahedral in shape (when empty)
• Attached to a structure at each corner of the tetrahedron
• Ureters enter at the supero-posterior angles
• Urethra leaves through the inferior angle
• Median umbilical ligament is attached supero-anteriorly

Question 18

Where is the internal sphincter found?

Answer 18

At the neck of the urethra, just below where it exits the bladder.

Question 19

Where does the bladder begin and end?

Answer 19

Expands between the transversals fascia and the lining of the peritoneum (superior surfaced is covered in peritoneum).

Question 20

What is the shape of the rectum and what is the significance of this?

Answer 20

Has a double S bend, which is thought to be a functional structures as an anti-gravity device, keeping the load off the sphincter.

Question 21

How are the rectum and anal canal innervated?

Answer 21

Rectum - autonomic nerves

Anal canal - somatic nerves

Question 22

What structure is important in faecal continence?

Answer 22

The puborectalis part of the levator ani, which puts a sharp angle into the recto-anal junction. The skeletal muscle sphincter surrounding the anal canal is actually much less important.

Question 23

How can the puborectalis be damaged?

Answer 23

Can bee damaged in a poorly performing episiotomy.

Question 24

What is an episiotomy?

Answer 24

A surgical cut made at the opening of the vagina during childbirth to aid difficult delivery and prevent rupture of tissues - it is sutured back up agin after delivery.