Anatomy part 3

Question 1

The perineum lies inferior to the … … and is the area between your … and …

Answer 1

pelvic diaphragm (pelvic floor)

anus and external genitalia

Question 2

What external features are part of the

• male (4)
• female (4)

perineum

Answer 2

Male - penis, urethra, scrotum, anus

Females - vulva, urethra, vagina, anus

Question 3

The perineum anatomically is diamond shaped and can be split into 2 triangles, with the base of each triangle being a transverse line that joins

Answer 3

the 2 ischial tuberosities

Question 4

The perineum anatomically is diamond shaped and can be split into 2 triangles

Which triangle lies inferior to the pubic symphysis and which triangle is associated with the coccyx

Answer 4

Urogenital triangle

Posterior anal triangle

Question 5

The anal opening is located centrally in the posterior anal triangle with what on either side

Answer 5

ischioanal fossae

Question 6

The urogenital triangle contains many layers

One of the deeper layers is a layer of tough fascia that divides the triangle into a superficial and deep perineal pouch; it is perforated by the vagina + urethra in females and the uretraa and ducts of the bulbourethral glands in males

What is this layer called + what is its function

Answer 6

Perineal membrane - provide attachment for the muscles of the external genitalia

Question 7

List the muscles of the perineum (6)

Answer 7

External anal sphincter
External urethral sphincter
Bulbospongiosus
Ischiocavernosus
Superficial transverse perineal
Deep transverse perineal

Question 8

What is the perineal body

Answer 8

A fibromuscular mass formed by all the perineal muscles attaching centrally where the urogenital and anal triangle meet

• external anal sphincter
• bulbospongiosus
• superficial and deep transverse perineal muscle
• levator ani
• external urinary sphincter

Question 9

All the perineal muscles are innervated by

Answer 9

A branch of the pudendal nerve

Question 10

External anal sphincter

• innervation
• function

Answer 10

Branch of pudendal nerve

Constrict anal canal to maintain continence

Question 11

Bulbospongiosus

• innervation
• function (males/females)

Answer 11

Branch of pudendal nerve

Males - compresses bulb of penis to expel remaining urine from urethra after micturition

Females - constricts the vaginal opening

Question 12

Ischiocavernosus

• innervation
• function

Answer 12

Branch of pudendal nerve

Maintains erection of penis/clitoris

Question 13

Superficial + deep transverse perineal

• innervation
• function

Answer 13

Branch of pudendal nerve

Fix perineal body in the centre of the perineum to support the abdominopelvic organs

Question 14

External urethral sphincter

• innervation
• function

Answer 14

Branch of pudendal nerve

Maintain urinary continence by constricting urethra

Question 15

Clinical significance of the perineal body

Answer 15

Maintains the integrity of the pelvic floor, esp in females as its rupture during childbirth in females predisposes to prolapse of pelvic organs

Question 16

The perineal body can rupture during childbirth

What can be done to prevent excessive tearing of the perineum and its muscles

Answer 16

Episiotomy

Question 17

What are the layers of the urogenital triangle from deep to superficial

The external urethral sphincter is first found in which of these layers

Answer 17

Deep perineal pouch –> perineal membrane –> superficial perineal pouch –> perineal fascia

Deep perineal pouch then pierces the perineal membrane

Question 18

Internal urethral sphincter

• innervation
• function

Answer 18

Sympathetic fibres from T10-L2

Constrict proximal urethra to maintain urinary continence

Question 19

The ischioanal fosse mainly contain + function

Answer 19

fat + connective tissue

allow anal canal to expand during defaecation

Question 20

Why may abscesses form in the ischioanal fossa

Answer 20

Pus from perianal abscesses can traverse through the external anal sphincter into the ischioanal fossa

Question 21

A neurovascular bundle enters the ischioanal fossa on its lateral wall - what does this bundle consist of

Answer 21

Pudendal canal - pudendal nerve, internal pudendal a + v

Question 22

What are the component parts of the penis

Answer 22

Foreskin (prepuce)
Urethra
Glans
Corpus spongiosum
Corpora cavernosa

Question 23

Penis can be divided into 3 parts - root, body and glans

In the root, the erectile tissues are known as the left and right crura and the bulb of the penis

The crura continue into the body of the penis and become the … and the bulb becomes the …

Answer 23

Crura –> corpora cavernosa

Bulb –> corpus spongiosum

Question 24

The urethra runs through what erectile tissue of the penis

Answer 24

Corpus spongiosum

Question 25

Distally, the corpus spongiosum expands to form the

Answer 25

glans

Question 26

Penis

• innervation
• arterial supply

Answer 26

Motor + sensory - pudendal nerve

Parasympathetic - cavernous nerves

Branches of internal pudendal artery

Question 27

Lymphatic drainage of penis

Answer 27

Superficial inguinal nodes

Question 28

Components of the female external genitalia (6)

Answer 28

Vulva - collective term for:

• mons pubis
• labia minora
• labia majora
• clitoris
• vestibule (area enclosed by the labia minora containing the vaginal and urethral orifice)
• greater vestibular (bartholin’s) glands

Question 29

Where are the greater vestibular glands + function

Answer 29

On either side of the vaginal orifice

Secrete mucous to lubricate vagina

Question 30

What are the 2 elongated masses of erectile tissue on either side of the vaginal opening called

Answer 30

Bulbs of the vestibule - equivalent to bulb of penis