Perineum

Question 1

What can the perineum be divided into?

Answer 1

2 triangles:

• Urogenital triangle
• Anal triangle

Question 2

What are the 3 components of the anal triange?

Answer 2

1. Anal aperture
2. External anal sphincter
3. Ischioanal fossa x2

Question 3

Where are the ischioanal fossa’s located?

Answer 3

Spaces located laterally to anus (between ischial spine and anus)

Extend from skin of anal region (inferiorly) to pelvic diaphragm (superiorly)

Question 4

What is the medial boundary of the ischioanal fossa?

Answer 4

Levator ani and external anal sphincter

Question 5

What is the lateral boundary of the ischioanal fossa?

Answer 5

Obturator internus

Question 6

What is the inferior boundary of the ischioanal fossa?

Answer 6

Subcutaneous tissue

Question 7

What is the anal aperture?

Answer 7

Opening of anus

Question 8

Where is the anal aperture located?

Answer 8

The anal aperture is located centrally in the triangle with the ischioanal fossae either side.

Question 9

What do the ischioanal fossae contain?

Answer 9

Fat and connective tissue to allow expansion of anal canal during defecation

Question 10

What else passes through the ischioanal fossa?

Answer 10

Pudendal neurovascular bundle (artery, nerve, vein)

Question 11

What branch does the pudendal nerve/artery give off in the ischioanal fossa?

Answer 11

Inferior rectal nerve and inferior rectal artery

Question 12

What does the inferior rectal nerve supply?

Answer 12

External anal sphincter, external urethral sphincter, levator ani

Helps with continence

Question 13

Where does the pudendal nerve come from?

Answer 13

S2, S3, S4

Question 14

What does the internal anal sphincter consist of?

Answer 14

Circular smooth muscle

Question 15

What is the internal anal sphincter innervated by?

Answer 15

Autonomic fibres (as smooth muscle)

Question 16

What is the external anal sphincter innervated by?

Answer 16

Pudendal nerve –> somatic control

Question 17

What are the different parts of the external anal sphincter?

Answer 17

1. Deep part
2. Superficial part
3. Subcutaneous part

Question 18

Describe the deep part of the external anal sphincter

Answer 18

Fuses with fibres of levator ani including puborectalis

Maintains anorectal angle

Question 19

What is the superficial part of the external anal sphincter attached to?

Answer 19

Anteriorly to the perineal body

Question 20

What is the urogenital triangle covered by?

Answer 20

An additional layer of strong deep fascia; the perineal membrane, as well as the muscular urogenital diaphragm

Question 21

What does the urogenital triangle merge with posteriorly?

Answer 21

The perineal body in the midline

Question 22

What is found above and below perineal membrane?

Answer 22

Pouches on superior and inferior surfaces

Above - deep perineal pouch
Below - superficial perineal pouch

Question 23

What are the boundaries of the urogenital triangle?

Answer 23

It is bounded by the pubic symphysis, ischiopubic rami, and a theorectical line between the two ischial tuberosities

Question 24

What are the layers of the urogenital triangle (deep to superficial)?

Answer 24

1. Deep perineal pouch
2. Urogenital diaphragm
3. Superficial perineal pouch
4. Perineal fascia
5. Skin

Question 25

What is found superior to the UG diaphragm?

Answer 25

Deep perineal pouch

Question 26

What is the UG diaphragm made up of?

Answer 26

1. Superior layer of connective tissue 2. Layer of striated muscle 3. Inferior thick layer of fascia: perineal membrane

Question 27

What does the layer of striated muscle of the UG diaphragm form?

Answer 27

External urethral sphincter, sphincter of vagina

Question 28

What is found inferiorly/superficially to UG diaphragm?

Answer 28

Superficial perineal pouch

Question 29

What is found within the superficial perineal pouch?

Answer 29

- Erectile tissue that forms the penis and clitoris (corpus cavernosum): found in men and women - Corpus spongiosum/bulb of vestibule Have 2 identical ones, one on either side of corpus spongiosum/vestibular bulbs

Question 30

What is the corpus spongiosum?

Answer 30

A mass of erectile tissue alongside the corpora cavernosa of the penis

Question 31

What is function of corpus spongiosum/the two cavernosa?

Answer 31

Expandable and sponge like, involved in process of penile erection Corpora cavernosum fills with blood

Question 32

What does the corpus spongiosum correspond to in females?

Answer 32

Female vestibular bulbs

Question 33

What does the corpus spongiosum contain?

Answer 33

The urethra

Question 34

Where does the corpus spongiosum terminate?

Answer 34

Dilates to form glans penis

Question 35

What does the root/bulb of penis attach to?

Answer 35

Perineal membrane

Question 36

How do the female vestibular bulbs differ from male corpus cavernosum?

Answer 36

Female bulbs don't fuse but sit either side of vaginal opening

Question 37

How do the female vestibular bulbs terminate?

Answer 37

Clitoris

Question 38

What muscle is found around the vestibular bulb and bulb of penis?

Answer 38

Bulbospongiosus muscle

Question 39

What muscle covers the corpora cavernosa?

Answer 39

Ischiocavernosus muscle

Question 40

Where do external genitalia hang from?

Answer 40

Perineal membrane (superficial pouch)

Question 41

What supplies the external genitalia?

Answer 41

Branches of pudendal artery and nerve

Question 42

How do the pudendal artery/nerve enter the perineum?

Answer 42

Leave pelvis via greater sciatic foramen inferior to piriformis, curves around ischial spine to enter perineum via lesser sciatic foramen