Session 26 - Bony Pelvis, Pelvic Floor and Perineum

Question 1

Where do the femoral, obturator and sciatic nerves pass from the abdomen into the
thigh?

Answer 1

• Femoral nerve: under the inguinal ligament half way between the pubic tubercle
and anterior superior iliac spine.

• Obturator: through the obturator canal.

• Sciatic: posteriorly through the greater sciatic foramen into the buttock and
then the thigh.

Question 2

Which muscle maintains the angle between the anal canal and rectum?

Answer 2

Levator ani

Question 3

Describe the location and contents/role of the “superficial perineal pouch” and
“perineal membrane”.

Answer 3

• Superficial perineal pouch - a potential space immediately superficial to the
perineal membrane that contains the erectile tissues of the penis or clitoris and
also 3 muscles: ischiocavernosus, bulbospongiosus and the superficial transverse
perineal muscles.

• Perineal membrane - a strong fibrous membrane located between the perineal
pouches that provides support for the attachment of ischiocavernosus and
bulbospongiosus and through which the urethra and vagina pass.

Question 4

Which nerve carries the majority of pain sensation during childbirth? Which landmark
used to identify this nerve when targeting it for a nerve block with local anaesthetic?

Answer 4

Pudendal nerve

Ischial spine

Question 5

The femoral artery and vein are targets for blood sampling in time-critical clinical
situations where getting a blood sample from peripheral veins is not possible or proving
very difficult. Describe the bony landmarks that clinicians can use to identify the
approximate location of the femoral vessels.

Answer 5

Mid-inguinal point

The mid-inguinal point: palpate the anterior superior iliac spine and the pubic
symphysis. Approximately halfway between these points is the location of the
femoral artery.

The femoral vein is situated immediately medial to the artery at this location.

Question 6

Identify the structures labelled A, B, C, D and E in the diagram.

Answer 6

A. Anterior superior iliac spine
B. Pubic symphysis
C. Acetabulum
D. Ischial tuberosity
E. Sacrotuberous ligament