Perineum

Question 1

Define the following boundaries of the perineum:
anterior boundary:
lateral boundary:
posterior boundary:
roof:

Answer 1

anterior boundary: pubic arch (pubic symphosis)

lateral boundary: pubic and ischial rami, ischial tuberosity, sacrotuberous ligament

posterior boundary: sacrum and coccyx

roof: pelvic diaphragm

Question 2

Where is the anal triangle?

Answer 2

posterior to a line connecting the ischial tuberosities

Question 3

Describe the anal canal.

arterial supply:
venous drainage:
innervation:

Answer 3

continuation of rectum beyond puborectalism

arterial supply: superior rectal A. above pectinate line, inferior rectal A below pectinate line

venous drainage: superior rectal V. above pectinate line, inferior rectal V. below pectinate line

innervation: autonomic = inferior hypogastric plexus somatic =inferior rectal n.

Question 4

Describe the internal anal sphincter.

Answer 4

thickened lower end of the inner circular muscle of the rectum

weak sphincter which is not competent acting alone
smooth muscle= inferior hypogastric plexus innervation

Question 5

Describe the external anal sphincter (3 parts).

Answer 5

subcutaneous- complete circle just deep to skin

superficial- attached posteriorly to coccyx, anteriorly to the perineal body

deep- encircles anal canal and is fused with puborectalis m.

skeletal muscle- innervated by inferior rectal branch of
pudendal nerve

Question 6

Describe the ischiorectoral fossa.

Answer 6

fat filled space lateral to the anal triangle which is used as dead space for the anus to expand

Question 7

Describe the lateral, medial, posterior, and anterior walls of the ischiorectoral fossa.

Answer 7

Lateral wall: fascia of obturator internus muscle, sacrotuberous ligament and ischial tuberosity

medial wall: anal canal and levator ani m.

posterior: gluteus maximus and sacrotuberous lig.
anterior: transverse perinei m.

Question 8

Describe the pudendal canal. (Also known as Alcock’s canal)

Answer 8

formed by fascia of obturator internus below levator ani which splits to enclose the pudendal neurovascular bundle and connects the lesser sciatic foramen to the posterior perineal membrane. (arcus tendineus is above levator ani)

The pudendal canal travels from the lesser sciatic foramen to the deep transverse perineus muscle. The ischial spine marks the posterior limit of the pudendal canal

Question 9

Describe the Perineal Body.

Answer 9

lies at the front of the anal canal, it is composed of interdigitating fibers of puboprostaticus (pubovaginalis); superficial external anal sphincter, and transversus perinei m.

Question 10

Describe the nerves of the anal triangle.

Answer 10

pudendal nerve gives off inferior rectal nerve and perineal nerve (perineal is more in UG area though)

pudendal divides at anterior end of anal (triangle to dorsal nerve of penis/clitoris and perineal n)

Question 11

Describe the vessels of the anal triangle.

Answer 11

Internal pudendal artery and vein

branches include inferior rectal artery and vein

internal pudendeal artery (gives inf. rectal which gives) perineal branch to superficial pouch and continues into deep pouch

Question 12

Describe the urogenital triangle.

Answer 12

Has perineal membrane which forms the base for penile (clitoral) musculature and penis (clitoris)

space deep to perineal membrane is the deep pouch, the space superficial to the perineal membrane is the superficial pouch

Question 13

What are the contents of the superficial perineal pouch of the urogenital triangle?

Where is it?

Answer 13

located the area between inferior fascia of UG diaphragm and Colles fascia

CRURA AND BULB:
root of penis/clitoris, erectile tissue
bulb: posterior part of corpus spongiosum (male)
crura: posterior part of corpora cavernosa (one crus, 2 crura. crus of penis/clitoris turns into corpora cavnernosa)
(in female the greater vestibular glands are in s. pouch)

blood supply: deep penile a to crura and artery to the bulb
internal pudendal, perineal

Question 14

What are the muscles of the superficial perineal pouch?

Answer 14

ischiocavernosus muscle -attaches to ischiopubic rami and surrounds the crura. It contracts to compress venous outflow of penis/maintain erection

Bulbospongiosus m. - surrounds the bulb, acts to expel any remaining urine or semen in the urethra

superficial transverse perineal m

Question 15

What is different about the female UG triangle?

Answer 15

the bulb and bulbospongiosus m. are split by the vagina

also clitoris has no corpus spongiosum. urethra has nothing to do with clitoris

in male the corpus spongiosum contains urethra running through

Question 16

What innervates the UG triangle?

Answer 16

perineal n (branch of pudendal nerve.. which also gives off inferior rectal n)
muscular branches
scrotal and labial branches

Question 17

Describe the arterial supply of the UG triangle.

Answer 17

perineal a. (branch of internal pudendal a.)
muscular branches
scrotal and labial branches

Question 18

Describe the deep perineal pouch and its contents.

Answer 18

space between perineal membrane and the deep fascia of the levator ani m. (deep pouch is between inferior fascia of UG diaphragm and superior fascia of UG diaphragm)

Contents: membranous urethra
bulbourethral glands (male) (Cowper's) ...lubricate urethra before ejaculation

sphincter urethra m.
deep transverse perineus m.

Question 19

What innervates the deep perineal pouch?

Answer 19

all muscles receive innervation from the muscular branch of the perineal nerve from superficial pouch (S234)

Question 20

Describe the arterial supply of the deep perineal pouch.

Answer 20

internal pudendal Artery

• muscular branch
• artery to the bulb: pierces the perineal membrane to enter the bulb of penis or clitorus
• deep A. pierces the perineal membrane to reach corposa cavernosa (major erectile body)
• dorsal A. pierces perineal membrane to reach dorsum of penis or clitoris

Question 21

Describe the veins of the deep perineal pouch.

Answer 21

correspond to the arteries except that the dorsal vein is divided into a deep and superficial dorsal vein

• superficial dorsal vein drains into the superficial external pudendal veins (a branch of femoral v)
• deep dorsal penile vein enters the pelvic cavity by passing above the anterior border of the UG diaphragm and drains into the prostatic plexus of veins

Question 22

Arrange the fascial planes in order from superficial to deep.

deep fascia (bucks; bulbospongiousus fascia)
skin
deep fascia of UG diaphragm
perineal membrane
deep fascia of pelvic diaphragm
membranous layer of superficial fascia (Scarpa’s, Dartos)

Answer 22

skin
membranous layer of superficial fascia (Scarpa’s Dartos)
deep fascia (bucks; bulbospongiosus fascia)
perineal membrane
deep fascia of UG diaphragm
deep fascia of pelvic diaphragm

Question 23

What two muscles occupy the deep space?

Answer 23

sphincter urethrae

deep transverse perineus

Question 24

Where is the ureter relative to the uterine artery?

Answer 24

Water under the bridge!
Ureter travels UNDER the uterine artery.

artery is superficial to ureter

Question 25

Describe the normal and abnormal orientation of the uterus and lower part of cervix/beginning of vagina.

Answer 25

normal:
uterus- anteflexion
lower part of cervix/beginning of vagina- anteversion

abnormal (could be because of tumor..):
uterus: retroflexed
lower part of cervix/beginning of vagina: (in?)verted

Question 26

Where are glands located in the male/female UG triangles?

Answer 26

female: greater vestibular gland in superficial pouch
male: bulbourethral gland within deep pouch

Question 27

What nerve may be blocked for childbirth or surgery?

Answer 27

pudendal

find it by palpating ischial spine (pudendal nerve block site)

Question 28

Describe the blood supply of the female perineum.

Answer 28

internal pudendal gives: inferior rectal a, dorsal artery of clitoris, perineal artery

dorsal artery of clitoris gives deep artery of clitoris

perineal artery gives posterior labial artery, artery to bulb, muscular branches

Question 29

Describe the nerve supply of the female perineum.

Answer 29

pudendal nerve gives inferior rectal, dorsal nerve of clitoris, perineal

perineal nerve gives posterior labial and muscular

Question 30

What is in the deep perineal pouch of the female?

Answer 30

(between perineal membrane below and superior fascia of UG diaphragm above)

vagina, urethra, sphincter urethra, deep transverse perinei
dorsal nerve of clitoris, dorsal/deep clitoral arteries

Question 31

What is in the superficial perineal pouch of female?

Answer 31

(everything below perineal membrane)

2 crura and ischiocavernosus
bulb and bulbospongiousus
superficial transverse perinei
perineal body
perineal artery/nerve/branches
vestibular glands

Question 32

What is in the male deep perineal pouch?

Answer 32

(between perineal membrane below and superior fascia of UG diaphragm above)

membranous urethra
deep transverse perinei
spinchter urethrae (external spincter)
bulbourethral glands (Cowper's) which drain into urethra below the perineal membrane
internal pudendal vessels
dorsal nerve of penis

Question 33

Describe how blood investing in the superficial perineal space will be stopped at borders with a straddle injury.

Answer 33

superior border: arcuate line in abdominal wall
lateral borders: inguinal ligaments
deep border: perineal membrane

in male, spread of urine in case of urethral injury would be toward scrotum, penis and anterior abdomen
(blood collects between Colle’s fascia and rectus sheath?)

Question 34

Arcus tendineus is between what 2 muscles?

Answer 34

Obturator internus
levator ani

(it is above the levator ani)

Question 35

Describe the path of the pudendal artery/nerve.

Answer 35

leaves greater sciatic foramen, loops around ischial spine and comes back in lesser sciatic foramen to reach perineum

Question 36

What are the roots of the sciatic nerve?

What are the roots of the femoral nerve?

Answer 36

sciatic- L4,5 and S1,2,3

femoral-L2,3,4

Question 37

What does Scarpa’s fascia turn into in the perineum?

Answer 37

Colle’s fascia