ANATOMY AND HISTOLOGY OF THE MALE PELVIS AND ASSOCIATED STRUCTURES

Question 1

what is an allantois?

Answer 1

a temporary embryonic bladder

Question 2

what’s the cloaca?

Answer 2

the common canal where urogenital and anorectal canals meet

Question 3

when does separation of the cloaca happen?

Answer 3

by the 4th week

Question 4

what are mesonephros?

Answer 4

temporary kidneys during development

Question 5

what are the metanephros?

Answer 5

the structures which will become the adult permanent kidneys

Question 6

what are the mesonephric ducts?

Answer 6

they connect the mesonephros to the bladder

Question 7

where are the paramesonephric ducts?

Answer 7

parallel to the mesonephric duct

Question 8

what are the metamesonephric ducts?

Answer 8

ducts which connect the metanephros to the kidneys

Question 9

describe how, in males, we go from temporary to adult permenant kidneys?

Answer 9

we lose the paramesonephric duct and the mesonephros

the mesonephric ducts become the ductus deferens and are attached to the gonad via collecting tubules

Question 10

describe the ducts and glands on the bladder

Answer 10

2 ureters loop around and insert to the back of the bladder
2 ductus defers loop over the top of the ureters and swell to form ampullas
ampullas and seminal vesicles are connected to the ejaculatory duct which go through the prostate to reach the urethra

Question 11

describe the 3 regions of the urethra?

Answer 11

prostatic urethra travels through the centre of the prostate gland
membranous urethera passes through membrane
spongy urethra is from the membrane to the outside

Question 12

what epithelium is the prostatic urethra?

Answer 12

transitional epithelium (same as bladder)

Question 13

what is the histology of the membranous and spongy regions of the urethra?

Answer 13

from the prostate ending to the glans penis is psuedostratified columnar epithelium
the glans penis region is stratified squamous epithelium

Question 14

what is the glans penis?

Answer 14

the rounded head

Question 15

what is the perineum?

Answer 15

the region between the anus and the genitals

Question 16

how is the perineum split up?

Answer 16

the top triangle is the urogenital region and the bottom triangle is the anal diaphragm

Question 17

what is the pelvic diaphragm?

Answer 17

a muscular sheet that separates the pelvic cavity from the perineal region

Question 18

what can be found within the perineum?

Answer 18

anal canal
spongy urethra
external genitalia
arteries nerves and veins

Question 19

what are the 2 holes within the pelvic diaphragm?

Answer 19

the urogenital hiatus (urogenital structures pass through)
anal hiatus (anal canal passes through)

Question 20

what muscles make up the pelvic diaphragm

Answer 20

levator ani muscle (a group of small muscles

coccyges

Question 21

what makes up the levator ani muscle?

Answer 21

iliococcygeus muscle
pubococcygeus muscle
puborectalis muscle

Question 22

what is the perineal membrane?

Answer 22

a thin layer of dense tough fascia in the perineum which divides the urogenital triangle into the superficial and deep perineal pouches

Question 23

what is the ischia-anal fossae?

Answer 23

a space between the perineal membrane and the pelvic diaphragm

Question 24

what is in the superficial perineal pouch?

Answer 24

contains external genitalia
corpus spongiosum in the midline and shaft of the penis and on either side the corpus cavernosus
and muscles

Question 25

which muscles do we find in the superficial perineal pouch?

Answer 25

ischiocavernous muscle (covers corpus cavernosus)
bulbospongiosus muscle
superficial transverse (covers corpus spongiosus) perineal muscle

Question 26

what is the perineal body?

Answer 26

A fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle.

Question 27

outline the indifferent stage of the external genitalia?

Answer 27

in the midline, just in front of the anus we have the urogenital groove and either side are the urethral folds. surrounding these are the genital swellings. at the front there are genital tubercles

Question 28

describe the formation of male external genitalia?

Answer 28

the genital tubercles increase in size
urethral folds increase in size and zip up so the urthera is a tube with a small hole at the glans penis
genital swelling become scrotal swellings
shaft of the penis is formed as cells undergo hypertrophy

Question 29

describe the innervation of the perineum?

Answer 29

the pudendal nerve forms from S2, S3 and S4 and innervates the perineum. the inferior rectal nerve is a branch off this that innervates the anal region

parasympathetic fibres S2, S3, S4 from the hypogastric plexus. for vasodilation, simulating erections and bladder contractions

sympathetic fibres T10-L2. important for smooth muscle contraction, internal urethral sphincter and reproductive glands

Question 30

describe the arteries of the perineum?

Answer 30

the internal pudendal artery is a branch of the internal iliac artery. it supplies arterial blood to the perineum other than the gonads

Question 31

describe the arteries of the gonads?

Answer 31

branches of the abdominal aorta

Question 32

describe the veins of the perineum?

Answer 32

the internal pudendal vein

the deep dorsal veins which drain into the prostate plexus- on penis