ANATOMY OF PERINEUM

Question 1

In general, what does the urogenital triangle and anal triangle contain?

Answer 1

Urogenital: male and female external genitalia
Anal: anal canal and anus and ischioanal fossa

Question 2

What separates the 2 triangles?

Answer 2

A line connecting the ischial tuberosities

Question 3

Perineal membrane:

• Stretches between?
• Extends anteriorly and posteriorly to?
• Separates the urogenital triangle into what 2 compartments?

Answer 3

• Stretches between the ischiopubic rami
• Extends anteriorly almost to pubic symphysis
• Extends posteriorly to ischial tuberosities
• Deep and superficial perineal spaces

Question 4

Where do the cavernous bodies of the external genitalia attach?

Answer 4

Deep perineal membrane

Question 5

What is the superficial perineal space/what are its boundaries?

Answer 5

Potential space bounded above by perineal membrane and below by the superficial perineal fascia

Question 6

What does the superficial perineal space contain in females?

What does it contain in males?

Answer 6

Clitoris, vestibular bulb, greater vestibular glands

- In males: root of the penis and proximal portion of spongy urethra

Question 7

What is the perineal body and it is formed by what muscles?

Answer 7

Irregular subcutaneous mass of fibromuscular tissue formed by converging fibers of the levator ani, deep transverse perineal and bulbospongiosus muscles and external anal sphincter

Question 8

Where does the perineal body lie in females and males?

Answer 8

Females: between the rectum and vagina
Males: between the rectum and bulb of penis ;) mmmm <3

Question 9

Function of the perineal body

Answer 9

Supports the pelvic diaphragm and pelvic viscera

Question 10

Innervation of perineum muscles

Answer 10

Pudendal nerve (S2 – S4)

Question 11

Blood supply to perineum

Answer 11

Perineal branches of the internal pudendal artery

Question 12

Venous drainage of the perineum

Answer 12

Drains to internal pudendal vein and internal iliac vein

Question 13

MALE UROGENITAL TRIANGLE: SCROTUM

What is it?

Answer 13

Extension of the anterior abdominal wall that encloses the testes and spermatic cord

Question 14

MALE UROGENITAL TRIANGLE: PENIS

What are the 3 parts of the penis? (just names)

Answer 14

Root, body, glans penis (aka glans)

Question 15

MALE UROGENITAL TRIANGLE: PENIS

Root: what is it attached to? Covered by? Composed of what 2 things?

Answer 15

Attached to perineal membrane, covered by muscles
Composed of:
1. Paired crura: attached to the ischiopubic rami and covered by the ischiocavernosus muscles
2. Bulb of penis: attached to the perineal membrane and covered by the bulbospongiosus muscles

Question 16

MALE UROGENITAL TRIANGLE: PENIS

What do the unattached parts of the paired crura of the penis continue as?

Answer 16

Corpora cavernosa

Question 17

MALE UROGENITAL TRIANGLE: PENIS

What does the unattached part of the bulb of penis continue as?

Answer 17

Corpus spongiosum

Question 18

MALE UROGENITAL TRIANGLE: PENIS

What is the body made up of? Is it covered by muscle?

Answer 18

Not covered by muscle

Made up of 3 cylindrical bodies of erectile tissue

Question 19

MALE UROGENITAL TRIANGLE: PENIS

What binds the 3 bodies together?

Answer 19

Deep penile fascia (Buck’s fascia)

Question 20

MALE UROGENITAL TRIANGLE: PENIS

What are the 3 erectile bodies?

Answer 20

2 corpora cavernosa (continuations of the crura); lie side by side on the dorsum of the penis
1 corpus spongiosum (continuation of the bulb of the penis); lies ventral to the 2 corpora cavernosa and is transversed by the penile urethra

Question 21

MALE UROGENITAL TRIANGLE: PENIS

Glans penis: what is it an extension of? Characterized by what 2 things?

Answer 21

Extension of the distal end of the corpus spongiosum
Characterized by:
Corona and external urethral orifice

Question 22

MALE UROGENITAL TRIANGLE: PENIS

Skin and subcutaneous tissue of the penis:
Blood supply and venous drainage

Answer 22

Blood supply: external pudendal artery

Venous drainage: superficial dorsal veins → external pudendal veins

Question 23

MALE UROGENITAL TRIANGLE: BULBOURETHRAL GLANDS

When are they active?

Answer 23

During sexual arousal

Question 24

MALE UROGENITAL TRIANGLE: BULBOURETHRAL GLANDS

What do they secrete and where do their ducts open?

Answer 24

Secrete mucus; ducts open into the proximal part of the spongy urethra

Question 25

MALE UROGENITAL TRIANGLE: BULBOURETHRAL GLANDS Where are they located?

Answer 25

On either side of the urethra below the prostate surrounded by the urethral sphincter

Question 26

ERECTION Describe the changes seen in the arteries and muscles during erections?

Answer 26

1. Normally constricted helicine arteries relax under parasympathetic innervation → cavernous spaces dilate and become engorged 2. Pudendal nerve innervates contractions of the bulbocavernosus and ischiocavernosus muscles to impede venous outflow and maintain the erection

Question 27

ERECTION Describe the path of the urethra starting from the prostate

Answer 27

Traverses the prostate (prostatic urethra) and urogenital diaphragm (membranous urethra), pierces the dorsal surface (top) of the bulb of penis and courses within the corpus spongiosum (spongy urethra)

Question 28

FEMALE UROGENITAL TRIANGLE What is the mons pubis?

Answer 28

Fatty tissue that’s continuous with the superficial fatty layer of the abdominal wall; lies anterior to the pubic symphysis and is continuous with the labia majora

Question 29

FEMALE UROGENITAL TRIANGLE What is the labia majora?

Answer 29

Bilateral folds of fatty tissue; dark skin covered with hair; the inner surface is smooth and hairless

Question 30

FEMALE UROGENITAL TRIANGLE What is the labia minora?

Answer 30

Bilateral folds of hairless skin; flank the vestibule of the vagina → merge towards the anterior end of the clitoris

Question 31

FEMALE UROGENITAL TRIANGLE What is the vestibule of the vagina? What does it contain?

Answer 31

Space surrounded by 2 labia minora | Contains urethral and vaginal orifices and the openings of the ducts of the greater and lesser vestibular glands

Question 32

FEMALE UROGENITAL TRIANGLE What are vestibular bulbs?

Answer 32

Paired masses of erectile tissue that lie deep to the labia minora and are covered by the bulbospongiosus muscles - Homologous to the bulb of the penis - DO NOT form part of the clitoris

Question 33

FEMALE UROGENITAL TRIANGLE Function of the greater vestibular glands

Answer 33

Lubricate the vestibule during sexual arousal

Question 34

FEMALE UROGENITAL TRIANGLE What does it mean by cavernous tissue?

Answer 34

Highly vascularized; gets engorged during arousal

Question 35

FEMALE UROGENITAL TRIANGLE What 2 muscles cover erectile tissue?

Answer 35

Ischiocavernosus and bulbospongiosus

Question 36

FEMALE UROGENITAL TRIANGLE Where is the clitoris located? Made up of how many erectile bodies?

Answer 36

At the anterior junction of the labia minora | 2

Question 37

FEMALE UROGENITAL TRIANGLE What make up the erectile bodies?

Answer 37

Paired corpora cavernosa that make up the crura → join to form the body of the clitoris

Question 38

ANAL TRIANGLE What is the ischioanal fossa? What are its superior and inferior boundaries? Lateral and medial boundaries?

Answer 38

Fat-filled space that surrounds the anal canal - Superior: pelvic diaphragm - Inferior: anal region - Lateral: obturator internus - Medial: pelvic diaphragm and external anal sphincter

Question 39

ANAL TRIANGLE Where does it extend anteriorly?

Answer 39

Anteriorly into the urogenital triangle superior to the perineal membrane

Question 40

ANAL TRIANGLE How is the pudendal canal formed?

Answer 40

Splitting of the fascia of the obturator internus on the lateral wall of the ischioanal fossa

Question 41

ANAL TRIANGLE Pudendal bundle exits what foramen before entering the pudendal canal?

Answer 41

Lesser sciatic foramen

Question 42

ANAL TRIANGLE What bundle traverses the fossa?

Answer 42

Inferior rectal

Question 43

ANAL TRIANGLE Purpose/function of this fossa

Answer 43

Support the anal canal while also allowing it to enlarge during defecation

Question 44

ANAL TRIANGLE The inner surface of the anal canal is characterized by what 3 things?

Answer 44

Anal columns, anal valves, anal sinuses

Question 45

ANAL TRIANGLE How is the perineal flexure created? What is its function?

Answer 45

Puborectalis (part of levator ani) forms a sling around the anorectal junction, pulling it anteriorly and creating the flexure - When the muscle relaxes = defecation - Helps to maintain continence

Question 46

ANAL TRIANGLE What do the muscle fibers of the external anal sphincter merge with: anteriorly, superiorly, posteriorly?

Answer 46

Anteriorly: bulbospongiosus and perineal body Posteriorly: anococcygeal ligament Superiorly: levator ani