Muscles and Walls of the Pelvic Cavity and Pelvic Floor

Question 1

The pelvic cavity has an antero-inferior wall, two lateral walls and a posterior wall.

The anterior-inferior wall is formed by the?

Answer 1

bodies and rami of the pubic bones and the pubic symphysis

Question 2

Answer 2

Question 3

which nerve network lies on the muscle forming the posterior wall of the pelvis?

Answer 3

sacral plecus lies anterior to the piriformis

Question 4

Answer 4

Question 5

what is the perineal body?

Answer 5

• The perineal body is a fibromuscular node lying in the midline of the perineum.
• In females it lies posterior to the vagina and anterior to the anal canal.
• It is pyramidal in shape and provides an anchor point for several of the muscles within the perineum.

Question 6

what is the anococcygeal body/ligament?

Answer 6

• The anococcygeal ligament runs in the midline between the inferior two segments of the coccyx and the posterior aspect of the rectum.
• It is a layered musculotendinous intersection of the two halves of the levator ani muscles.

Question 7

which 2 muscles make up the majority of the pelvic floor?

Answer 7

1: coccygeus
2: levator ani muscles (3 paired separate muscles)

Question 8

give three functions of the pelvic diaphragm/floor

Answer 8

1. support of the abdominopelvic viscera - through their tonic contraction.
2. resistance to increases in intra-pelvic/abdominal pressure - during activities such as coughing or lifting heavy objects.
3. urinary and faecal continence - the muscle fibres have a sphincter action of the rectum and urethra. They relax to allow urination and defecation.

Question 9

What is the innervation of the pelvic diaphragm/floor?

Answer 9

• coccygeus: branches of S4-5 nerves
• levator ani: nerve to levator ani (branches of S4), inferior anal (rectal) nerve, coccygeal plexus

Question 10

what is a cystocele?

Answer 10

A dropped or prolapsed bladder (cystocele) occurs when the bladder bulges into the vaginal space.

Question 11

what is a rectocele?

Answer 11

A rectocele is a form of pelvic organ prolapse, where weakened tissues in your pelvis cause your rectum to sag onto your vagina wall.

Question 12

Injury to the pelvic floor during childbirth is common and potentially damaging. Why?

Answer 12

• The pubococcygeus, the main intermediate part of the levator ani, is usually torn.
• This part of the muscle encircles and supports the urethra, vagina and anal canal.
• Weakening of this muscle may alter the position of the neck of the bladder and urethra which can cause urinary stress incontinence during coughing and lifting for instance.

Question 13

Why may an episiotomy minimise long-term damage to the pelvic floor?

Answer 13

Sometimes a doctor or midwife may need to make a cut in the area between the vagina and anus (perineum) during childbirth. This is called an episiotomy. An episiotomy makes the opening of the vagina a bit wider, allowing the baby to come through it more easily.

Question 14

Why is a mediolateral episiotomy preferable to a midline episiotomy?

Answer 14

A midline incision is easier to repair, but it’s more likely to extend into the anal area. A mediolateral incision is more difficult to repair, but it’s less likely to extend into the anal area.

Question 15

what structures can be palpated when performing a digital rectal examination on a (i) male and (ii) female?

Answer 15

(i) Prostate palpated anteriorly, seminal vesicles are close to anterior wall of rectum, bony structures such as sacrum and coccyx.
(ii) Cervix, rectouterine pouch of Douglas, walls of the rectum, bony structures.