GU anatomy Flashcards
What is the inguinal canal?
Short, oblique passageway through muscles of anterior abdominal wall
5cm long
Walls collapsed around contents to avoid other structure entering and getting stuck
Where does the inguinal canal run?
Starts at the transversalis fascia (deep,lateral) at deep inguinal ring
Finishes at superficial inguinal ring in external oblique aponeurosis (superficial and medial)
What is in the inguinal canal in females?
Round ligament (from uterine horn to attach to labia majora)
Ilioinguinal nerve
Genital branch of genitofemoral nerve supplying skin of mons pubis and labia majora
What is in the inguinal canal in males?
All contents within spermatic cord except ilioinguinal nerve
Ilioinguinal nerve runs in canal but outside cord
What is in the spermatic cord?
Genital branch of genitofemoral nerve (supplies cremaster muscle and anterior scrotal skin)
Sympathetic nerve fibres
Testicular, cremasteric arteries and artery to vas deferens
External spermatic fascia, cremaster muscle and fascia, internal spermatic fascia
Pampiniform venous plexus
Lymphatics
Vas deferens
processus vaginalis
What is external spermatic fascia derived from?
External oblique aponeurosis
What is cremaster muscle and fascia derived from?
Internal oblique muscle
What is internal spermatic fascia derived from?
Transversalis fascia
What is an inguinal hernia?
Protrusion of abdominal contents through anterior abdominal wall into inguinal canal
What is an indirect inguinal hernia?
Intra-abdominal contents forced through deep inguinal ring into canal
More common
What is a direct inguinal hernia?
Intra-abdominal contents forced through the posterior wall of inguinal canal and directly through the superficial ring
Less common and easier to reduce
What is the dartos?
A thin sheet of smooth muscle directly under scrotal skin
Regulates the temp by wrinkling skin and reducing surface area
What does each half of the scrotum contain?
A testis, epididymis and lower part of spermatic cord
What do the testes do?
Produce sperm and secrete testosterone
What and where is the tunica vaginalis?
Closed sac of parietal peritoneal origin
Partially surrounds testes
What and where is the epididymis?
A coiled tube lying along the posterior border of each testis
Has a head (proximal), body and tail (distal, origin of vas deferens)
What is the function of vas deferens?
Carries sperm from epididymis to spermatic cord
What is the blood supply and drainage of testes?
Supplied by testicular arteries from AA
Venous blood enters pampiniform venous plexus which forms testicular vein
R testicular vein enters IVC, L joins renal vein
What are the three cylinders of erectile tissue in penis?
2 corpora cavernosa dorsally
Corpus spongiosum ventrally - contains penile urethra
Enclosed within Buck’s fascia
What is the end of the penis?
Glans, expansion of corpus spongiosum
Where does the male urethra open?
External urethral meatus
What is the blood supply to penis?
Penile arteries branch from internal pudendal arteries from internal iliac
What is the nervous innervation to penis?
S2-4
Sensation and symp from dorsal nerve of penis (branch of pudendal)
Parasymp arise from peri-prostatic nerve plexus
How does erection in males occur?
Arterial blood flow into corpora increases and corpora enlarge
Corpus spongiosum doesn’t enlarge as much and prevents urethra from being compressed
Where does the R adrenal gland lie and what shape is it?
Close to the top of kidney
Behind the liver and IVC
Pyramidal
Where does the L adrenal gland lie and what shape is it?
Close to top of kidney
Behind the stomach and pancreas
Semilunar
What are the 3 main arteries to the adrenal glands?
Superior adrenal- from inferior phrenic
Middle adrenal- from AA
Inferior adrenal- from renal
Where do the adrenal veins drain?
R adrenal drains directly into IVC
L adrenal drains into L renal then IVC
What does the adrenal cortex do?
Produces steroid hormones including cortisol, aldosterone and testosterone
What does the adrenal medulla produce?
Adrenaline
What are the dimensions of the kidneys?
11cm long
7cm wide
4cm thick
What level are the kidneys at?
T12-L3
What are the outer layers of the kidney?
Renal capsule (deepest)
Perinephric fat layer
Renal fascia
Paranephric fat
What enters through the renal hila?
Renal vessels
Nerves
Lymphatics
Ureters
What is the internal kidney composed into?
Cortex with nephrons (minus loop of henle + part of CD)
Medulla arranged into pyramids containing loop of Henle and rest of the collecting ducts
Renal papilla
Minor calyces
Major calyces
Renal pelvis which are continuous with ureter
What are the ureters and where do they run?
Narrow tubes with muscular walls
Transport urine via peristalsis
Anterior to psoas major on posterior abdo wall
Cross pelvic brim and enter bladder on its inferomedial aspect
What does the posterior abdo wall consist of?
L spine
Psoas and quadratus lumborum muscles
IVC, aorta, symp trunk, ureters and gonadal vessels all run along
What forms the lumbar plexus?
L1-L4 lumbar spinal nerves with contribution from T12
What does the lumbar plexus give rise to and what do they supply?
- Iliohypogastric and Ilioinguimal nerves supply anterior abdo wall muscles and skin of external genitalia
- Genitofemoral nerve supplies skin of external genitalia
- Lateral femoral cutaneous nerve supplies skin of lateral thigh
- Femoral nerve supplies muscles and skin of anterior thigh
- Obturator nerve supplies medial thigh
At what level does the AA bifurcate and terminate?
L4
What does the AA bifurcate into?
L and R common iliac arteries
What unpaired branches does the AA give rise to?
Coeliac trunk
SMA
IMA
What paired branches does the AA give rise to?
Renal
Adrenal
Gonadal
Lumbar arteries
What forms the IVC?
L and R common iliac veins unite at L5
What are the functions of the pelvis?
Transfer of weight
Provides attachment for locomotion
Contains and protects pelvic viscera
What bones make up the pelvis?
Sacrum
L and R hip (ilium, ischium and pubis fused together)
Which 3 bones fuse to form the hip?
Ilium
Ischium
Pubis
What are the 5 articulations of the bony pelvis?
Hip joint
Sacroiliac
Pubic symphysis
Lumbosacral
Sacrococcygeal
Where is the hip joint?
Between the head of femur and acetabulum of pelvis
What fuse at the acetabulum?
Ilium
Ischium
Pubis
Where is the sacroiliac joint?
Between the sacrum and ilium of hip bone
Very stable
Supported by ligaments
Where is the pubic symphysis?
Between the 2 pubic bones
Almost no movement permitted
Where is the lumbosacral joint?
Between 5th L vertebrae and sacrum
Intervertebral disc between the 2
Where is the sacrococcygeal joint?
Between the sacrum and coccyx
What does the intercristal line mark?
L4-5 disc space for lumbar puncture
Highest point of iliac crests
Where is the iliac tubercle?
Most lateral point of the ilium
What does the intertubercular line mark?
Lower 1/3 of abdomen from middle 1/3
What does the pubic tubercle mark?
Most medial part of the pubic bone
Where does the inguinal ligament run from?
ASIS to pubic tubercle
What is palpable at the mid-inguinal point?
Femoral artery
Where is the mid-inguinal point?
Mid-point of a line from ASIS to pubic symphsis
What is the female pelvis like?
Wider, circular pelvic inlet
Obtuse angle formed by inferior pubic rami
Wider and shorter sacrum
What is the male pelvis like?
Narrower pelvic inlet
Acute angle formed by pubic rami
Narrower, longer sacrum
What is the arterial supply to the pelvis?
L and R internal iliac
What are the key branches of the internal iliac and what do they supply?
Vesical arteries- supply the bladder in both sexes, and prostate and seminal vesicles in men
Uterine and vaginal (female)
Middle rectal - rectum
Internal pudendal- perineum
Sup and Inf gluteal- gluteal
Where does the pelvis drain?
Plexuses unite and drain into internal iliac vein
WWhat nerves arise from the sacral plexus?
Sciatic nerve
Pudendal nerve
Sup and Inf gluteal nerves
Pelvic splanchnic nerves
What forms the sacral plexus?
Sacral spinal nerves
What forms the pudendal nerve?
S2-4
What do the gluteal nerves do?
Innervate gluteal region
What do the pelvic splanchnic nerves do?
Carry parasympathetic fibres from S2-4 to pelvic viscera
Where are the sympathetic fibres that innervate the pelvis viscera derived from?
Lumbar splanchnic nerves
What are the 3 primary functions of the pelvic floor muscles?
Prevent herniation of pelvic organs inferiorly
Control continence of urine and faeces by providing a sphincter
Aid in increasing intra-abdominal pressure
Which two muscles make up the pelvic floor?
Levator ani
Coccygeus
What makes up leavtor ani?
All paired
Puborectalis
Pubococcygeus
Iliococcygeus
What does puborectalis do and attach to?
Attache to pubic bones anteriorly and forms sling around rectum
Pulls to form sharp angle between rectum and anal canal to prevent defecation
Relax for faeces to pass through
What does pubococcygeus attach to and do?
Provides stability and support to pelvic organs
Posterior and lateral to puborectalis
Attaches to pubic bone anteriorly
Attaches to coccyx and sacrum posteriorly
What does iliococcygeus attach to and do?
Lies lateral to pubococcygeus
Attaches to spines of ischium and the coccyx
Elevates pelvic floor and anorectal canal
What supplies levator ani?
Branch from S4
Some branches from pudendal (S2-4)
What is the perineum?
Superficial region between the pubic symphysis and coccyx
And betweene medial surfaces of the thighs
What can the perineum be split into?
Anal and urogenital triangles
What does the anal triangle contain?
Opening of anus and external anal sphincter
What are the layers of the urogenital triangle?
Skin
Perineal fascia
Superficial perineal pouch
Perineal membrane
Deep perineal pouch
What is the perineal fascia?
A continuation of the fascia overlying the abdominal wall muscles
What is the superficial perineal pouch?
Space containing erectile tissues of penis or clitoris and 3 muscles: ischiocavernosus, bulbospongiosus and superficial transverse perineal
What 3 muscles are in the superficial perineal pouch?
ischiocavernosus
bulbospongiosus
superficial transverse perineal
What is the perineal membrane?
A strong fibrous membrane that provides support for the attachment of ischiocavernosus and bulbospongiosus
Has specific holes for urethra and vag
What is the deep perineal pouch?
A potential space between perineal membrane and pelvic floor muscles
Contains parts of vag, urethra and ext urethral sphincter
Where is the perineal body?
Between the anal and UG triangles
What is the perineal body?
A dense mass of fibrous tissue and muscle
Acts as an attachment for almost all the perineal and pelvic floor muscles
Which parts of the corpora cavernosa are attached to the ischial ramus?
Crura (crus singular)
What is the bulb of corpus spongiosum?
The part that sits on the perineal membrane
What does ischiocavernosus do?
Helps stabilise the erect penis/clitoris
What does bulbospongiosus do?
Assists in maintaining erection
In males: compresses veins that drain erectile tissues and contracts to squeeze fluid
In females: constricts around vaginal orifice to help fluid expression
What is the arterial supply to the perineum?
Internal pudendal from internal iliac
What is the main nerve of the perineum?
Pudendal S2-4
Innervates perineum and skin of external genitalia
What are the male reproductive organs?
Paired testes
Epididymides
Vasa deferentia
Seminal vesicles
Ejaculatory ducts
Bulbo-urethral glands
Prostate gland
Penis
What does the vas deferens do?
Carries sperm from epididymsi up the spermatic cord and through inguinal canal to pelvis
Terminates by joining the duct of the seminal vesicle to form ejaculatory duct
What forms the ejaculatory duct in men?
Vas deferens terminates and joins seminal vesicle duct
What is the seminal vesicle?
A lobulated sac lateral to ampulla of vas deferens
Secrete bulk of semen
Joins vas deferens to become ejaculatory duct
What does the prostate do?
Lies against neck of bladder
Pierced by urethra and ejaculatory ducts
Secretes enzymes into semen to break down clotting factors and keep fluid
What is the arterial supply to vas deferens, seminal vesicle and prostate?
Branches of internal iliac
What are the parts of the uterus?
Fundus
Body
Cervix
How is the uterus positioned?
Communicates laterally with uterine tubes and inferiorly with vagina
Lies on superior surface of bladder
Ante-flexed
Where does the blastocyst implant in the uterus?
Endometrium in the body of the uterus
What happens to the myometrium if pregnancy continues?
Becomes distended
What is the uterus covered by?
A fold of peritoneum which adheres to sides to form broad ligament
What is the space between the posterior uterus and anterior rectum called?
Rectouterine pouch (Pouch of douglas)
What is the rectouterine pouch?
Deepest point in peritoneal cavity so common site for accumulation of fluid/pus
Lined with peritoneum
Between uterus and rectum
What is the structure of the cervix?
Narrow lumen
Cervical canal communicates with uterine cavity via internal os and vag via external os
Lower part of cervix lies inside vag creating recess (vaginal fornices) around cervix
What stabiliises the cervix position?
Levator ani muscles and ligaments
What are the 4 parts of the fallopian tubes?
Isthmus
Ampulla
Infundibulum
Fimbrae draped over ovary
Where does fertilisation occur?
Ampulla of fallopian tubes
Where are the ovaries attached?
Posterior aspect of broad ligament by mesovarium
Position not fixed
Frequently in ovarian fossa between internal and external iliac arteries
What is the vagina?
Excretory duct of the uterus
Female organ of sexual intercourse
Where does the vagina run?
10cm long
Passes through the pelvic floor
Upper 2/3 lie in pelvic cavity
Lower 1/3 in perineum
Terminates at the introitus by opening into vestibule between labia minora
What in the female reproductive system does the internal iliac artery supply?
Vagina
Fallopian tubes
Cervix
Uterus
What does the ovarian artery supply and where does it come from?
Branch of AA
Supply ovaries and contributes to fallopian tubes
What is the vulva?
All parts of the female external genitalia
What is the blood supply to the vulva?
Mainly internal pudendal from internal iliac
What 4 nerves innervate the vulva?
Ilioinguina
Genital branch from genitofemoral
Pudendal
Posterior cutaneous
What is the mons pubis?
Mound of fatty tissue loacted in front of pubic symphysis causing an elevation of hair bearing skin
What is the labia majora?
Prominent hair bearing folds of skin that meet anteriorly at mons pubis
What is the labia minora?
Smaller, hairless folds of skin medial to labia majora
Fuse together to form clitoris hood
Form boundaries of vestibule
What is the clitoris?
Highly sensitive tissue made of erectile corpora cavernosa and spongiosum
Engorged during sexual arousal
Where is the vestibule?
Area between labia minora
Contains vaginal opening, urinary meatus, vestibular glands
What is the hymen?
Thin membrane partially covering vaginal opening
What is the urinary meatus?
Opening of the urethra
Posterior to clitoris
Anterior to vaginal opening
What are the greater vestibular glnads?
Bartholins glands
Posterior to vaginal opening
Secrete lubricant into vagina during sexual arousal
What are the lesser vestibular glands?
Skenes glands
Near urethral opening
Secrete fluid
Where is the urinary bladder?
Infra-peritoneal below periotneum in pelvis
Posterior to pubic symphysis
Anterior to vag and rectum
What supplies the urinary bladder?
Vesical arteries from internal iliac
Drain into internal iliac
What is the role of the bladder?
Stores urine
Squeeze urine out during micturition
How much urine can the bladder accommodate?
400-600ml in adults
What is the smooth wall in the triangular area of the bladder called?
Trigone
Where ureters enter
What forms at the angle where ureters enter the trigone?
Rudimentary valve which prevents reflux of urine into ureters when bladder full
What type of muscle does the bladder contain?
Smooth
Where is the internal urethral sphincter and what is it composed of?
Base of bladder
Opens into urethra
Composed of smooth muscle under involuntary control
Where is the external urethral sphincter and what is it composed of?
Just after prostate in males
In deep perineal pouch in females
Skeletal muscle
Under voluntary control
What is the somatic innervation to the bladder?
Pudendal (S2-4)
Allows conscious control of the external urethral sphincter
What is the sympathetic innervation to the bladder?
Hypogastric nerve (T12-L2 symp chain)
Causes relaxation f detrusor and contraction of the internal urethral sphincter
Urine storage
What is the parasympathetic innervation to the bladder?
Pelvic splanchnic nerves (S2-4)
Causes contraction of the detrusor and relaxation of internal urethral sphincter
Allows initiation of micturition
Where does the urethra run?
Carries urine from the internal urethral orifice of the bladder to the external urethral orifice
How long is the female urethra?
3-4cm
What are the divisions of the male urethra?
Preprostatic
Prostatic
Membranous
Penile
Describe the bladder stretch reflex
Bladder fills with urine
Walls stretch
Sensory nerves detect
Sacral spinal cord
PS fibres in pelvic splanchnic
Bladder contracts and empties
When is the bladder stretch reflex overridden?
Potty training, put under conscious control
What pathways are interrupted if a an injury is above spinal cord sacral level in bladder dysfunction?
Ascending pathways conveying sensation (patient no longer aware of bladder filling)
Descending pathways that exert voluntary control over external urethral sphincter (permanently relaxed)
Reflex arc still in tact, incontinence
What happens if a patient suffers injury to spinal cord at cauda equina or below (bladder dysfunction)?
Internal urethral sphincter permanently contracted
Bladder fills, pressure exceeds strength of internal urethral sphincter: urination
This is overflow incontinence
If pressure doesn’t exceed, urinary retention, needs catheter to avoid backflow of blood
What is the rectum?
Terminal part of large intestine
Approx 12cm in adult
Stores faeces prior to defecation
What are the 2 flexures on the rectum?
Sacral: anterior
Anorectal: posterior
Where is the anal canal?
Distal rectus to anus
In anal triangle
What is the muscle and control of internal anal sphincter?
Smooth muscle
Involuntary
What is the muscle and control of external anal sphincter?
Skeletal
Voluntary
What does the pectinate divide?
Superior part of anal canal from inferior
Above pectinate line, endoderm derived
Inferior part from ectoderm
Therefore different supplies
What supplies the superior part of anal canal?
Part of hindgut
Supplied by inferior mesenteric artery via superior rectal artery
Portal venous drainage
What epithelia lines the superior part of anal canal?
Columnar epithelium lines lumen
Intestinal mucosa
What innervates the internal anal sphincter?
Sympathetic fibres from sympathetic trunk
PS fibres (pelvic splanchnic)
What supplies the part of the anal canal below pectinate line?
Middle and inferior rectal arteries from internal iliac
No portal drainage
What epithelia lines lumen of inferior anal canal?
Stratified squamous
What innervates the external anal sphincter?
Pudendal nerve
What are haemorrhoids?
Cushions of veins lining walls of anal canal which aid faecal continence
