Anatomy of Genitourinary and Renal Systems Flashcards
What is the inguinal canal?
Oblique passageway through muscles of anterior abdominal wall lying superior to medial half of inguinal ligament
Inguinal canal pathway
Starts at transversalis fascia (deep inguinal ring - an aperture in the transversalis fascia) deep and laterally
Finishes at external oblique aponeurosis (superficial inguinal ring - an aperture in the external oblique aponeurosis) superficially and medially
How long is the inguinal canal in adults?
Approx 5cm
Anterior border of inguinal canal
External oblique aponeurosis
Laterally only: internal oblique aponeurosis
Posterior border of inguinal canal
Transversalis fascia
Medially only: aponeurosis of internal oblique and transversus abdominis
Roof of inguinal canal
Transversalis fascia
Fibres of internal oblique and transversus abdominis
Floor of inguinal canal
Inguinal ligament
What is the inguinal ligament made up of?
Rolled up lower border of external oblique aponeurosis
Contents of inguinal canal in females
1) Round ligament of the uterus
2) Ilioinguinal nerve
3) Genital branch of genitofemoral nerve
In males, contents of inguinal canal are all contained within the …….. except from the …….. which runs in the canal but outside the ……
Spermatic cord
Ilioinguinal nerve
Spermatic cord
Contents of spermatic cord
2 nerves (genital branch of genitofemoral nerve and sympathetic nerve fibres)
3 arteries (testicular, cremasteric and artery to vas deferens)
3 fascial layers (external spermatic fascia, cremaster muscle and fascia, internal spermatic fascia)
4 other structures (pampiniform venous plexus, lymphatics, vas deferens, processus vaginalis)
Derivatives of the 3 fascial layers of the spermatic cord
External spermatic fascia derived from external oblique aponeurosis
Cremaster muscle and fascia derived from internal oblique muscle
Internal spermatic fascia derived from transversalis fascia
What is the processus vaginalis?
Evagination of peritoneum found in the spermatic cord
An inguinal hernia is…
Protrusion of abdominal contents through anterior abdominal wall into the inguinal canal
Indirect inguinal hernia
-Intra-abdominal contents forced through deep inguinal ring and into canal
-May even also be forced through superficial inguinal ring
-More common than direct
Direct inguinal hernia
-Intra-abdominal contents forced through posterior of inguinal canal directly through superficial inguinal ring
-Herniated content won’t pass through deep ring
-Less common but easier to reduce
Difference between other skin and scrotum skin
Scrotum skin is thin, wrinkled and more darkly pigmented
Between skin of scrotum is…
Thin layer of superficial fascia
Dartos (thin, involuntary muscle)
What separates the 2 testicles?
Extension of the superficial fascia forms a septum between the 2
What covers the testes?
The same 3 fascial layers covering the spermatic cord
External spermatic fascia, cremaster and internal spermatic fascia
Testes are partially covered by a sac derived from the peritoneum called…
The tunica vaginalis
The epididymis is a coiled tube laying on what border of each testis?
Posterior border
Where are spermatozoa formed and stored?
Formed in the testis
Stored in the epididymis
What carries sperm from epididymis?
Vas deferens
Testicular arteries are direct branches from…
The abdominal aorta
Venous blood from the testis and epididymis enter the… which forms the ….
pampiniform venous plexus
testicular veins
The right testicular vein enters the….
IVC
The left testicular vein enters the…
Left renal vein
3 cylinders of erectile tissue in the penis
2 corpora cavernosa found dorsally (along top of penis)
1 corpus spongiosum found ventrally (along bottom of penis)
The corpus spongiosum and corpora cavernosa are enclosed within the deep fascia of the penis called…
Buck’s fascia
End of penis is called …. which is an expansion of …
Glans
Corpus spongiosum
Penile urethra is found within the…
Corpus spongiosum
Urethra approaches the end of the penis and opens via…
The external urethral meatus
Arterial supply to penis via … which branch from …. which themselves branch from ….
Penile arteries branch from the internal pudendal arteries which themselves branch from the internal iliac arteries
Nerve supply to penis
S2-S4
Sensation and sympathetic via dorsal nerve of the penis which is a branch of the pudendal nerve
Parasympathetic from peri-prostatic nerve plexus (causes erection by dilating arteries of corpora)
What is primarily responsible for penis rigidity and increased size during an erection?
Corpora cavernosa filling with blood due to increased arterial blood flow (spongiosum also fills with blood but not to same extent)
Main role of corpus spongiosum during erection
Prevent urethral compression (would prevent ejaculation)
Each adrenal gland is supplied by 3 arteries
Superior adrenal artery - branch of inferior phrenic artery
Middle adrenal artery - branch of abdominal aorta
Inferior adrenal artery - branch of renal artery
Drainage of right and left adrenal glands
Right adrenal vein drains directly into the IVC
Left adrenal vein drains into left renal vein which then joins the IVC
2 sections of the adrenal glands and what they produce
Cortex - steroid hormones including cortisol, aldosterone, testosterone
Medulla - adrenaline
Kidneys are either side of what vertebrae?
Upper lumbar
Each kidney is embedded by
Perinephric which is covered by a renal fascia
Paranephric fat is found outside renal fascia
What is found at the renal hilum of each kidney?
Renal vessels, nerves, lymphatics, ureter
Left and right renal arteries are branches of…
The abdominal aorta
Left and right renal veins drain directly into…
IVC
Collecting ducts travel down the renal pyramid to the…
Renal papilla where it enters the minor calyx and flows into a major calyx into the renal pelvis and into the ureter
Ureters carry urine from… to ….
Kidneys to urinary bladder
Path of the ureters
Run anterior to psoas major on the posterior abdominal wall and cross the pelvic brim to enter the pelvis
Ureters enter the bladder from…
The inferomedial aspect
Ureters are narrow tubes with muscular walls which transport urine by…
Peristalsis
Which spinal nerves form the lumbar plexus?
L1-L4 (with contribution from T12)
Ilioinguinal and iliohypogastric (branches of lumbar plexus) supply…
Anterior abdominal walls muscles and skin of external genitalia
Genitofemoral nerve (branch of lumbar plexus) supplies…
Skin of external genitalia
Lateral femoral cutaneous nerve (branch of lumbar plexus) supplies…
Skin over lateral thigh
Femoral nerve (branch of lumbar plexus) supplies…
Muscles and skin of anterior thigh
Oburator nerve (branch of lumbar plexus) supplies…
Muscles and skin of medial thigh
Thoracic aorta pierces diaphragm at …. descending through the diaphragm as abdominal aorta
Level of T12
Abdominal aorta terminates by birfurcating into ….. and ….. at level of ….
Left and right common iliac arteries at approx level of L4
Abdominal aorta and IVC relative positions
Abdominal aorta just left of midline
IVC just right of midline
Paired branches of abdominal aorta (4)
Renal
Adrenal
Gonadal
Lumbar arteries
Unpaired branches of abdominal aorta (3)
Coeliac trunk
Superior mesenteric artery
Inferior mesenteric artery
Bony pelvis functions
Supporting spine, torso, upper body
Locomotion
Housing/protecting abdominal viscera
3 bones of the bony pelvis
Sacrum
Left and right hip bones
3 smaller, fused bones comprising each hip bone
Ilium, ischium and pubis
Hip joint of pelvis is between…
Head of femur and acetabulum (socket of pelvis)
Sacroiliac joint of pelvis
Between sacrum and the ilium of hip bone
Pubic symphysis of pelvis
Between 2 pubic bones
Lumbosacral joint
Between 5th lumbar vertebrae and sacrum
Sacrococcygeal joint
Between sacrum and coccyx
Palpating iliac crest
The posterior iliac crest is the highest point which can be palpated between level of L4-L5
Palpating the anterior superior iliac spine
Most anterior point of the ilium in most people
Palpating the iliac tubercles
Most lateral point of the ilium
Intertubercular line delineates the hypogastric from the umbilical region (lower from middle 1/3 of abdomen)
Palpating pubic tubercle
Most medial part of pubic bone
Where does the inguinal ligament run?
What does it border the floor of?
From the ASIS to pubic tubercle
Bordering floor of inguinal canal
Mid-inguinal point
Halfway point between ASIS and pubic tubercle
What does McBurney’s point mark?
Approximate location of base of appendix
3 differences between male and female pelvis
Wider circular pelvic inlet in females (for childbirth), narrower heart-shaped in males
Wider and shorter sacrum in females
Obtuse (>90) angle formed by inferior pubic rami in females, acute (<90) angle in males
5 key branches of the internal iliac arteries
Vesical arteries
Uterine and vaginal arteries
Middle rectal artery
Internal pudendal artery
Superior and inferior gluteal arteries
Organs housed by the pelvis
Rectum
Bladder
Uterus (F)
Ovaries (F)
Vagina (F)
Prostate (M)
Seminal Vesicles (M)
Arterial supply to pelvis
Left and right internal iliac arteries (give rise to several branches that supply pelvic viscera)
What do the vesical arteries (branch of internal iliac) supply?
Bladder in both sexes
Prostate and seminal gland in males
What does the middle rectal artery (branch of internal iliac) supply?
Rectum
What does the internal pudendal artery (branch of internal iliac) supply?
Exits pelvis to supply perineum
What do the superior and inferior gluteal arteries (branch of internal iliac) supply?
Exits pelvis to supply gluteal region
Drainage of the pelvis
By several venous plexuses which unite and mostly drain into the internal iliac vein
4 key nerves arising from the sacral plexus
Sciatic nerve
Pudendal nerve
Superior and inferior gluteal nerves
Pelvic splanchnic nerves
Sciatic nerve formed by…
L4-S3 exiting pelvis to supply lower limb
Pudendal nerve formed by…
S2-S4 (somatic) exiting pelvis and is major nerve of perineum
Superior and inferior gluteal nerves innervate…
Gluteal region
Pelvic splanchnic nerves formed by…
S2-S4 (parasympathetic) supplying pelvic viscera
3 functions of the pelvic floor (collective name for several muscles)
1) Prevent herniation of pelvic organs inferiorly
2) Control continence by providing a sphincter on urethra and rectum respectively
3) Aid increased intra-abdominal pressure
2 main muscles of the pelvic floor
Levator ani
Coccygeus
Levator ani comprised of 3 smaller paired muscles
1) Puborectalis
2) Pubococcygeus
3) Iliococcygeus
Puborectalis role
U-shaped muscle attaching to pubic bones anteriorly forming a sling around the rectum
Creates a sharp angle between rectum and anal canal preventing defecation
When it relaxes, the path straightens
Contributes to micturition in a similar way
Pubococcygeus position and attachments
Lies posterior and lateral to puborectalis attaching to pubic bone anteriorly and coccyx and sacrum posteriorly
Iliococcygeus attachment and position
Lateral to pubococcygeus attaching to the spines of the ischium and the coccyx
Innervation of levator ani
Branch of S4 nerve and some branches of pudendal nerve (S2-S4)
Where is the perineum found?
Immediately superficial and inferior to pelvic floor
It’s the superficial region between pubic symphysis and coccyx, and between the medial surfaces of the thighs
Viewed from below, the perineum is roughly diamond shaped and can be divided into 2 triangles…
Anal triangle (posteriorly) - contains opening of anus and anal sphincter
Urogenital triangle (anteriorly) - 5 layers
5 layers of urogenital triangle
Skin - Urethra and vagina open through skin
Perineal fascia - Continuation of fascia overlying abdominal wall muscles
Superficial perineal pouch - Potential space containing erectile tissue of penis/clitoris and 3 muscles
Perineal membrane - Fibrous membrane providing attachment to ischiocavernosus and bulbospongiosus. Has holes in it for urethra and vagina
Deep perineal pouch - Space between perineal membrane and pelvic floor muscles. Contains parts of vagina, urethra and external urethral sphincter
3 muscles found in the superficial perineal pouch (potential space)
Ischiocavernosus, bulbospongiosus, superficial transverse perineal muscles
What sits between the 2 triangles of the perineum?
The perineal body - Dense mass of fibrous tissue and muscles sitting in middle of perineum acting as an attachment for most perineal and pelvic floor muscles
What is contained within the superficial perineal pouch?
Part of urogenital triangle containing most of erectile tissue that unites to form the clitoris/penis and the muscles overlying them
Path of corpora cavernosa to converge on the midline
They’re symmetrical and run along the ischial rami bilaterally to converge in the midline
Parts of the corpora cavernosa attached to the ischial ramus are called…
crura
Males have an expanded proximal corpus spongiosum called…
The bulb of the penis which rests on the perineal membrane
Make up of the corpus spongiosum in females
Splits in 2 parts that flank the vaginal opening
Also rest on perineal membrane either side of vaginal opening
These parts of the corpus spongiosum are the bulb of vestibule (bulb of clitoris)
Which muscle covers the corpora cavernosa?
Ischiocavernosus muscles
Which muscle covers the corpus spongiosum?
Bulbospongiosus muscle
Role of ischiocavernosus muscle
Stabilise elect penis/clitoris
Role of bulbospongiosus muscle in males
Assists in maintaining erection by compressing veins draining erectile tissues and contracts to squeeze any remaining urine/semen from urethra
Role of bulbospongiosus in females
Maintain clitoral erection and constricts around vaginal orifice which can help expression of fluid from greater vestibular glands
Arterial supply to perineum is via…
The internal pudendal artery (branch of internal iliac artery)
The main nerve in the perineum is the pudendal nerve (S2-S4). What does it innervate?
Muscles in perineum and skin of external genitalia
How does the internal pudendal artery enter the pelvis?
Through the lesser sciatic foramen
How does the pudendal nerve enter the pelvis?
Through the greater sciatic foramen
What is the only part of the internal pelvis not supplied by the internal iliac artery?
Gonads supplied by the gonadal arteries which come directly from the aorta
What divides the 2 triangles of the perineum?
The ischial tuberositys
Urachus
Remnant of a channel between the bladder and the umbilicus
Male reproductive organs (8)
Testes
Epididymides
Vasa deferentia
Seminal vesicles
Ejaculatory ducts
Bulbo-urethral glands
Prostate glands
Penis
Vas deferens path
Carries sperm from epididymis up spermatic cord through inguinal canal into pelvis. From deep inguinal ring, passes across side wall of pelvis, medially onto back of bladder.
Here it has a dilated portion (ampulla) which lies medial to seminal vesicle
Terminates by joining the duct of the seminal vesicle to form the ejaculatory duct
Seminal vesicles
Each 4cm long lying lateral to ampulla of vas deferens
Secrete thick alkaline fluid forming bulk of semen
Duct of seminal vesicle joins vas deferens becoming ejaculatory duct which pierces back of prostate to enter prostatic urethra
Prostate
Walnut sized
Lies against neck of bladder
Pierced by urethra and ejaculatory ducts
Secretions of prostate added to seminal fluid during ejaculation
Prostate, seminal vesicle and vas deferens all supplied by…
Internal iliac artery
Female pelvis contains
Uterus, cervix, vagina, uterine tubes and ovaries
Uterus length
About 8cm
Uterus has 3 parts…
Fundus (above uterine tubes)
Body
Cervix
Body of uterus typically angled…
And lies on…
Anteriorly
Superior surface of bladder
Rectouterine pouch (Pouch of Douglas)
Behind uterus, anterior to rectum (lined with peritoneum)
Deepest point in peritoneal cavity (makes it common accumulation site of intraperitoneal fluid/pus)
If conception occurs, developing blastocyst implants into…
The uterine lining (endometrium) in the body of the uterus
Which layer of the uterus becomes distended if pregnancy continues?
The middle, muscular layer (myometrium)
Uterus covered in fold of peritoneum which adheres to itself at sides of uterus to form…
The broad ligament (attaches uterus to lateral pelvic sidewalls)
Cervix interacts with the uterine cavity via the…
And with the vagina via the…
Internal os
External os
Lower cervix lies inside the vagina creating a recess around the cervix called..
The vaginal fornices
Cervix stabilised by…
Tone of levator ani muscle
Role of fallopian (uterine) tubes
Site of fertilisation
Carry ova from ovary to uterine cavity
Uterine tubes found running in the upper border of…
The broad ligament
Free edge of infundibulum (of fallopian tube) is broken up into…
Finger-like projections called fimbriae which are draped over the ovary
Ovary dimensions
4cm x 2cm
Ovary dimensions
4cm x 2cm
How are the ovaries attached to the broad ligament?
Attached to posterior aspect of broad ligament by a short mesentery (mesovarium)
Vagina length
About 10cm
Introitus
External opening of vaginal canal
Opens into vestibule (between the 2 labia minora)
Upper 2/3 of vagina lie in…
Lower 1/3 lies in…
Pelvic cavity
Perineum
Female urethra often embedded in…
Lower 1/3 of vagina
Female pelvic organ blood supply
Internal iliac artery supplies: Uterus, cervix, fallopian tubes, vagina
Ovarian arteries supply: Ovary and contributes to fallopian tube blood supply
What is the ovarian artery a branch of?
Direct branch of abdominal aorta
What is the vulva?
Collective name for all parts of external female genitalia
Blood supply to vulva
Internal pudendal arteries
Internal pudendal arteries are branches of…
Internal iliac arteries
Innervation to vulva via 4 nerves…
Ilioinguinal nerve
Genital branch of genitofemoral nerve
Pudendal nerve
Posterior cutaneous nerve of the thigh
Mons pubis (female)
Mound of fatty tissue located in front of pubic symphysis causing elevation of hair-bearing skin (labia majora)
Labia majora (female)
Prominent hair-bearing folds of skin
Labia minora (female)
Smaller, hairless folds of skin located medial to labia majora
Form boundaries of vestibule
Anterior fusion of labia minors forms…
Hood of the clitoris
Clitoris
Comprises corpora cavernosa and corpus spongiosum
Becomes engorged during sexual arousal
Vestibule of vagina
Space bordered by labia minora containing vaginal opening, urinary meatus and vestibular glands
Hymen
Thin membrane partially covering vaginal opening
Often ruptures during first episode of sexual intercourse / use of tampon
What is the urinary meatus?
External opening of urethra
The vestibular glands of the vulva
Greater vestibular glands (Bartholin’s glands) - just posterior to vaginal opening secreting lubricant into vagina during sexual arousal
Lesser vestibular glands (Skene’s glands) - lie near urethral opening. Fluid secretion
urinary bladder located in pelvis below the peritoneum making it…
An infra-peritoneal organ
Relative position of urinary bladder
Posterior to pubic symphysis
Anterior to vagina and rectum
Blood supply of urinary bladder
Vesicle arteries (which are branches of internal iliac artery)
Drainage of urinary bladder
vesicle veins which drain into internal iliac veins
In an adult, urinary bladder can accommodate up to…
400-600ml urine
Where do ureters drain into bladder?
Posterior aspect
What prevents backflow of urine into ureters when bladder is flow
Rudimentary valve (formed because ureters enter the trigone of the bladder at an angle)
Bladder trigone
Triangular shaped region at base of bladder
The detrusor
Smooth muscle in bladder wall which contracts to forcibly expel urine
Composition of internal bladder wall
Corrugated with folds of mucosa called RUGGAE allowing bladder to stretch when it fills
2 sphincters controlled urine release
Internal urethral sphincter
External urethral sphincter
Internal urethral sphincter
Located at base of bladder where it opens into urethra
Smooth muscle, involuntary control
External urethral sphincter
Located just after prostate in males and in deep perineal pouch in females
Skeletal muscle, voluntary control
Somatic innervation of urinary bladder and urethral sphincters
Branches of pudendal nerve (S2-S4)
Allows conscious control of external urethral sphincter
Sympathetic innervation of urinary bladder and urethral sphincters
Branches of hypogastric nerve (T12-L2)
Relaxation of detrusor and contraction of internal urethral sphincter (urine storage)
Parasympathetic innervation of urinary bladder and urethral sphincters
Pelvic splanchnic nerves (S2-S4)
Contraction of detrusor, relaxation of internal urethral sphincter (micturition)
2 ends of the urethra named…
Internal and external urethral orifices
4 parts of male urethra
Preprostatic
Prostatic
Membranous
Penile
Length of female urethra
3-4cm
Sacral micturition centre found in the…
sacral spinal cord
Bladder stretch reflex
Bladder fills -> stretch detected sent to sacral spinal cord via visceral afferent fibres.
Here, they synapse directly onto motor neurons
The motor neurons (via parasympathetic fibres in the pelvic splanchnic nerves) stimulate bladder contraction
How is the bladder stretch reflex inhibited in adults and older children?
Inputs from cerebral cortex
They can detect bladder filling and consciously control when to urinate (achieved through ‘potty-training’)
2 flexures of the rectum
Anterior curve (sacral flexure)
Posterior curve (anorectal flexure)
Rectum length in adults
About 12cm
Anal canal length
About 4cm
Anal canal position
Found in the anal triangle of the perineum
2 anal sphincters controlling defecation
Internal anal sphincter - smooth muscle, involuntary
External anal sphincter - skeletal muscle, voluntary
Pectinate line divides…
Superior part of anal canal (derived from endoderm) from inferior part (derived from ectoderm)
Blood supply to superior part of anal canal
Part of hindgut so is supplied by the IMA (via the superior rectal artery)
Blood supply to inferior part of anal canal
Middle and inferior rectal arteries which originate from internal iliac
Drainage of superior part of anal canal
Via portal system towards liver
Internal anal sphincter innervated by…
Sympathetic fibres (originating from sympathetic trunk)
Parasympathetic fibres (via pelvic splanchnic nerves)
Drainage of inferior anal canal
Enters systemic system (doesn’t enter portal system)
External anal sphincter innervated by…
Pudendal nerve
Internal anal sphincter encircles…
External anal sphincter encircles…
Superior anal canal
Inferior anal canal
Haemorrhoids
Abundance of veins that form cushions lining the walls of the anal canal
Juxtaglomerular Apparatus
Modified muscular layer of afferent arteriole at hilum of glomerulus
Contains juxtaglomerular cells and macula densa
Cells contain less actin/myosin but many granules containing renin (cells act as baroreceptors to change in BP)
Low BP -> less distended walls -> renin release
