The Perineum

Question 1

What are the two triangles of the perineum called?

Answer 1

Urogenital triangle and anal triangle

Question 2

Which structures form the borders of the perineum?

Answer 2

Anterior border = inferior border of pubic symphysis
Lateral border = ischial tuberosity
Posterior = tip of coccyx

Question 3

Which triangle in the perineum consists of many layers of tissue?

Answer 3

Urogenital

Question 4

What does the deep perineal pouch contain in females?

Answer 4

Proximal part of urethra, mass of smooth muscle, dorsal neurovasculature of clitoris

Question 5

What does the superficial pouch in females contain?

Answer 5

Clitoris, ischiocavernosus muscle, bulbs of vestibule (bulbospongiosus), greater vestibular glands (Bartholin’s gland), superficial transverse perineal muscle

Question 6

Outline the order of layers in the urogenital triangle

Answer 6

Skin –> superficial perineal fascia (1. superficial fatty tissue Campers, 2. Colles’ fascia which is membranous layer) –> deep perineal fascia and muscle (including superficial then deep pouches)

Question 7

What are the anatomical borders of the anal triangle?

Answer 7

Coccyx, sacrotuberous ligament (laterally) and an imaginary line between the ischial tuberosities (to separate from urogenital triangle)

Question 8

What are the anatomical borders of the urogenital triangle?

Answer 8

Pubic symphysis anteriorly, ischiopubic rami and sacrotubuerous ligaments laterally and imaginary line posteriorly between the ischial tuberosities.

Question 9

Describe the blood supply to the perineum

Answer 9

Common carotid artery –> internal iliac artery then descends giving rise to the superior and then inferior gluteal arteries. The final branch of the interior iliac artery is the internal pudendal artery which then branches further to form the arteries of the perineum: inferior rectal, perineal and dorsal clitoral/penis

Question 10

Describe the nervous supply to the perineum

Answer 10

Mainly from the pudendal nerve (S2,4 and 4 keeps the shit off the floor)

Question 11

What structures does the anal triangle contain?

Answer 11

Contains the ischioanal fossa, which is lateral to the anal canal. On the lateral wall of this fossa is the obturator internus muscle which contains the pudendal canal (contains internal pudendal vessels and nerve).

Question 12

Describe the contents of the superficial pouch in males

Answer 12

Root of penis, crura, ischiocavernous, bulbospongiosus, proximal part of spongy urethra and superficial transverse perineal muscles

Question 13

Describe the contents of the deep pouch in males

Answer 13

external urethral sphincter, deep transverse perineal muscle, membranous portion of urethra, bulbourethral gland

Question 14

In males, what causes the moistening of the external urethral orifice?

Answer 14

Stimulation of the Cowper’s glands

Question 15

Describe how nervous stimulation leads to the development of an erection

Answer 15

Parasympathetic outflow (S2-S4) goes to hypogastric plexus and causes the release of NO which leads to vasodilatation and engorgement. The pressure created is further accentuated by the ischiocavernosus and bulbospongiosus muscle action.

Question 16

What is another name for the bulbourethral gland?

Answer 16

Cowper’s gland

Question 17

Which organs, in males, secrete fluids into the ejaculatory duct?

Answer 17

Seminal vesicles, prostate gland and bulbourethral glands

Question 18

Describe how nervous stimulation leads to ejaculation

Answer 18

There is stimulation of sympathetic fibres to the smooth muscle of the ducts of the epididymis, vas deferens, seminal vesicles and prostate alongside rhythmic contractions of bulbospongiosus muscles (and bladder sphincter contracts involuntarily)

Question 19

Describe the attachments of the crura in male anatomy

Answer 19

These are attached to the pubic arch and lie along the dorsum of the penis (form part of corpus cavernosum)

Question 20

What is the prepuce?

Answer 20

Foreskin

Question 21

Describe the attachments of the prepuce in male anatomy

Answer 21

The prepuce/foreskin covers the glans penis (head) and is connected to the glans by the frenulum

Question 22

Describe the attachments of the bulb of the penis

Answer 22

Bulb of penis is attached to urogenital diaphragm (pelvic floor) and is transversed by urethra

Question 23

Describe the attachments of the erectile tissue in males

Answer 23

There are 2 dorsal corpus cavernosa and 1 ventral corpus spongiosum (expands up to form glans penis)

Question 24

What type of urethra is present in the penis shaft?

Answer 24

Spongy urethra

Question 25

What are the 4 different names for parts of the urethra?

Answer 25

Pre-prostatic, prostatic, membranous and spongy

Question 26

Describe the location of the pre-prostatic urethra

Answer 26

Vertical through the neck of the bladder

Question 27

Describe the location of the prostatic urethra

Answer 27

Descends through anterior prostate

Question 28

Describe the location of the membranous urethra

Answer 28

Descends through the deep perineal pouch

Question 29

Describe the location of the spongy urethra

Answer 29

Courses through the corpus spongiosum

Question 30

What is the role of the ischiocavernosus muscle?

Answer 30

It covers and compresses the crura in order to assist erection in women and men (penis or clitoris)

Question 31

What is the function of the bulbospongiosus muscle?

Answer 31

Females: ejects clitoris and reduces size of vaginal orifice
Males: compresses urethra and dorsal vein, involved in ejaculation

Question 32

What is the role of Bartholin’s gland?

Answer 32

Secretes lubricating mucus at vaginal orifice through small ducts that pen in the posterior vestibule

Question 33

What is the perineal body?

Answer 33

This is the point of attachment of muscles that assist the perineal body to support the vaginal wall e.g. levator ani, external anal sphincter, bulbospongiosus and superficial transverse perineal