Anatomy - Genitourinary and Renal systems Flashcards
What is the inguinal canal?
- oblique passageway through muscles of anterior abdominal wall
Where is the inguinal canal?
- superior to medial half of inguinal ligament
- passes through each layer of abdominal wall as it travels medially and inferiorly (starting at transversalis fascia deep and laterally and finishing with the external oblique aponeurosis superficially and medially)
How long it the inguinal canal?
~5cm in an adult
Where does the inguinal canal extend from?
- deep inguinal ring to superficial inguinal ring
What is the deep inguinal ring?
- an aperture in the transversalis fascia
What is the superficial inguinal ring?
- an aperture in the external oblique aponeurosis
Anterior border of inguinal canal
- external oblique aponeurosis
- laterally only (internal oblique aponeurosis)
Posterior border of inguinal canal
- transversalis fascia
- medially only (medial fibres of aponeuroses of the internal oblique and transversus abdominis)
What is the conjoint tendon?
fusion of aponeuroses of transversus abdominis and internal oblique
Roof of the inguinal canal
- transversalis fascia
- arching fibres of internal oblique and transversus abdominis
Floor of inguinal canal
- inguinal ligament (rolled-up lower border of external oblique aponeuroses)
What are the contents of the female inguinal canal?
- round ligament of the uterus
- ilioguinal nerve
- genital branch of genitofemoral nerve
What are the contents of the male inguinal canal?
- contents and including spermatic cord
- ilioinguinal nerve
Contents of the spermatic cord
- two nerves
- three arteries
- three fascial layers
- four other structures
What are the two nerves in the spermatic cord?
- genital branch of genitofemoral nerve
- sympathetic nerve fibres
What are the three arteries in the spermatic cord?
- testicular artery
- cremasteric artery
- artery to the vas deferens
What are the three fascial layers in the spermatic cord?
- external spermatic fascia
- cremester spermatic fascia
- internal spermatic fascia
What is the external spermatic fascia derived from?
- external oblique aponeuroses
What is the cremaster spermatic fascia derived from?
- internal oblique muscle
What is the internal spermatic fascia derived from?
- transversalis fascia
What are the four other structures in the spermatic cord?
- pampiniform venous plexus
- lymphatics
- vas deferens
- processus vaginalis
Where is the processes vaginalis derived from?
- the peritoneum
What is a hernia?
- an abnormal profusion of tissues or organs from one region into another through an opening or defect
When may a hernia of the abdominal wall occur?
- if the muscles are weak or have been incised during surgery
What is an inguinal hernia?
- a protrusion of abdominal contents (normally part of the greater omentum or loops of small intestine
True or false? Inguinal hernias are indirect or direct
true - can be either
Describe an indirect hernia
- intra-abdominal contents are forced through the deep inguinal ring and into the canal
- abdominal contents may even be forced along the canal and through the superficial ring
Where may an indirect hernia extend into?
- scrotum in males
- labia majora in females
Direct or indirect hernias are common?
indirect - they are also more likely to get stuck in the canal and become ‘irreducible’
Clinical relevance of indirect hernia
- herniated tissue can ‘strangulate’ and become ischaemic
- surgical emergency
Describe a direct hernia
- intra-abdominal contents are forced through the posterior wall of inguinal canal and directly through the superficial ring
- herniated contents do no pass through the deep inguinal ring in direct inguinal hernias
Which hernia is easier to reduce?
direct hernia
What is the scrotal skin?
- thin, wrinkled and more darkly pigmented than skin elsewhere
Dartos
- a thin involuntary muscle underneath the skin
What is found underneath the skin?
- a thin layer of superficial fascia and dartos
- the superficial fascia extends between the testicles to form a septum dividing the scrotum into right and left halves
What does each half of the scrotum contain?
- a testes
- epididymis
- a lower part of the spermatic cord
What are the testes?
- male reproductive organs
- produce sperms
- secrete sex hormone testosterone
Describe the testes
- ovoid structures
- covered by same three layers of spermatic fascia that cover the spermatic cord
- partially surrounded by a sac derived from the peritoneum: Tunica Vaginalis
What is the epididymis?
- a coiled tube lying along the posterior border of each testis
- has an expanded head superiorly, a body and a pointed tail lying at the lower pole of the testis
What is formed in the testis?
- spermatazoa
Where is spermatozoa stored and what does it travel with?
- in the epididymis
- travels with the testicular vessels in the spermatic cord
Where do the testicular arteries arise from?
- they are a direct branch of the abdominal aorta
Where does the venous blood from the testis and epididymas go?
- it enters the pampiniform venous plexus
What does the pampiniform venous plexus form?
- the testicular vein
What does the right testicualr vein join and enter?
- the inferior vena cava
What does the left testicular vein join and enter?
- left renal vein
Name 5 examples of scrotal swellings
- hydrocoele
- varicocele
- epididymo-orchitis
- testicular torsion
- indirect inguinal hernia
Hydrocoele
- painless swelling caused by accumulation of peritoneal fluid between the layers of tunica vaginalis around the testis
- when a light is shone through a hydrocoele it can be seen from the other side
- this is called transillumination
Varicocoele
- abnormal dilation of the pampiniform venous plexus
- described as feeling like a ‘bag of worms’ on palpation (due to dilated veins)
- more common on the left side, due to the fact that the left testicular vein drains into the left renal vein before it drains into the inferior vena cava
- because of this, development of a left-sided varicocele often warrants intra-abdominal investigation to exclude a tumour that may be obstructing its venous drainage
Epididymo-orchitis
- painful inflammation of the epididymas and testis
- epididymo-orchitis in a younger patient is often caused by a sexually transmitted infection such as chlamydia or gonorrhoea whereas in an older patient it is more commonly caused by a urinary tract infection
Testicular torsion
- twisting of the testis on the spermatic cord
- this can lead to ischaemia of testis and is a surgical emergency
- if left untreated, it can lead to necrosis and loss of the affected testis
- torsion is very painful
Testicular cancer
- less common
- prognosis is excellent if detected and trated early, usually with surgery to remove testis and a length of cord (orchidectomy) with chemotherapy or radiotherapy if required
- testicular cancer metastasizes first to the para-aortic or retroperitoneal lymph nodes
Cryptochidism (undescended testis)
- during fetal development the testes form in the abdomen
- descend through the inguinal canal to reach the scrotum before birth
- if this fails to occur the infant is born with one or both testes absent from the scrotum, and the affected testis will be stuck somewhere along the path of descent
- spermatogenesis is optimal just below core body temperature, the testes will only function correctly if they are in the scrotum
- there is an increased risk of testicular cancer if the undescended testis is left inside the abdomen
- therefore, undescended testes are often brouht into the scrotum surgically
Vasectomy
- a means of male sterilisation
- relatively uncomplicated surgical procedure where the scrotum is incised and the vasa deferentia are located on each side and separated, before ligating, cauterising or clamping each end
- this prevents the passage os sperm from the testes
What is the Penis made up of?
3 cylinders of erectile tissue:
- 2 corpora cavernosa dorsally
- 1 corpus spongiosum ventrally
They are enclosed within the deep fascia of the penis
What is the name of the deep fascia of the penis in which the 3 cylinders are enclosed in?
Buck’s fascia
What is the end of the penis called?
- the glans (it is an expansion of the corpus spongiosum)
What does the penile urethra also carry?
- urine
- semen
Where does the penile urethra lie within?
- the corpus spongiosum
The urethra approaches the end of the penis and opens via…
the external urethral meatus
Describe the arterial supply to the penis
- penile arteries
- these are a branch of the internal pudendal artereis (which are a branch off the internal iliac arteries)
Innervation of the penis
- nerve supply: S2-S4
- general sensation and sympathetic innervation are carried by dorsal nerve of penis (branch of pudendal nerve)
- parasympathetic: arise from the peri-prostatic nerve plexus
What are the parasympathetic nerves in the penis reponsible for?
- causing erection by dilating the arteries of the corpora
What are primarily responsible for the increase in size and rigidity of the penis during erection?
- the corpora cavernosa
- during sexual arousal arterial blood flow into corpora increases so it becomes engorged with blood
- corpus spongiosum becomes engorged also but not to the same extent
What is the main role of the corpora spongiosum during erection?
- prevent the urethra from being compressed (which would prevent ejaculation)
Erectile dysfunction
- inability to acheive/maintain erection during sexual acitvity
- common and will affect most males at some point
- problem with blood flow, nerve pathays and relfexes and pschological arousal can cause this
- management: identify cause and treating that or using medications e.g. slidenafil which increase blood flow into the corpora of the penis
Where do the adrenal glands lie?
- close to the upper pole of each kidney
- right: behind the liver and IVC
- left: behind the stomach and pancreas
What are the three arteries that supply the adrenal glands?
- superior adrenal artery
- middle adrenal artery
- inferior adrenal artery
What is the superior adrenal artery a branch of?
- inferior phrenic artery
What is the middle adrenal artery a branch of?
- abdominal aorta
What is the inferior adrenal artery a branch of?
- renal artery
Venous drainage of the adrenal glands
- by a single vein on each side
- right adrenal vein directly drains into the IVC
- left first into left renal vein and then joins IVC
What are the two parts of the adrenal gland?
- outer cortex
- inner medulla
What does the outer cortex of the adrenal glands produce?
- steroid hormones e.g. cortisol, aldosterone and testosterone
What does the inner medulla of the adrenal glands produce?
- adrenaline
Phaeochromocytoma
- rare hormone-producing tumour of adrenal medulla
- secretes excess adrenaline and can cause signs related to hyperactivity of the sympathetic nervous system e.g. hypertenison, tachycardia and excessive sweating
Dimensions of a regular kidney
- 11cm long
- 7 cm wide
- 4cm thick
True or false? the kidneys are both extra-peritoneal and retroperitoneal
true
Describe the positions of the kidneys
- one on either side of the upper lumbar vertebrae
What are the kidneys embedded and then covered in?
- perinephric fat
- this is covered by renal fascia
- there is a further layer of perinphric fat outside the renal fascia
Where is the renal hilum and what does it contain?
- medial border of the kidneys
- renal vessels, nerves, lymphatics and ureter enter/leave the kidney
What are the left/right renal arteries branches of?
abdominal aorta
Where do the left/right renal veins directly drain into?
IVC
Internal compsure of the kidneys
- cortex, medulla and calyces
True or false? The medulla is arranged into pyramids
true
What are the functional units of the kidneys (nephrons) responsible for?
- filtering the blood
- reabsorbing water and solutes
- secreting and excreting waste products as urine
What parts of the nephron are in the cortex?
- glomeruli
- bowman’s capsule
- PCT
- DCT
- part of the collecting duct
What parts of the nephron is in the pyramids?
- loop of henle
- rest of the collecting duct
Where does urine travel down from the collecting ducts to?
- renal papilla (apex of the pyramid) where it enters a minor calyx
- minor calyces merge to form the renal pelvis which is continuous with the ureter
Purpose of the ureter (narrow tubes with muscular walls)
carry urine to the bladder via peristalsis
Where does the ureter run?
- anterior to psoas major on posterior abdominal wall
- cross the pelvic brim to enter the pelvis
- enter the bladder on its inferomedial aspect
What are Kidney (ureteric) stones made from and what are the risk factors for developing them?
- calcium oxalate
- risk factors: high urine calcium levels, dehydration, obesity and certain medications
Typical presentation of an obstructing kidney stone
- excruciating, pulsatile pain felt from loin to groin
- due to the pain fibres supplying ureter originate from T12-L2
- pain is referred and felt in the T12-L2 dermatomes
What occurs if flow of urine from kidneys is obstructed?
- kidney will fill with urine and swell (hydronephrosis)
- this can injure the kidney and may also lead to infection
The ureter narrows in three regions where it is likely for stones to get stuck. These regions are…
- pelvic-ureteric junction (PUJ) - between the renal pelvis and ureter
- pelvic brim - where ureter runs over pelvic brim (anterior to iliac artery)
- vesicle-ureteric junction (VUJ) - where ureter joins the bladder
Urinary Tract Infection (UTIs)
- almost always caused by bacteria entering the urinary bladder via urethra
- more common in females is urethra is shorter
- infection of urinary bladder is called cystitis
- symptoms: burning pain on passing urine and sensation of having to pass urine more frequently
- pyelonephritis is a more serious infection
Pyelonephritis
- requires intravenous antibiotics
- symptoms: fever, flank pain and nausea and vomiting plus other UTI symptoms
What are the three types of renal cancer and what are they based on?
- renal cell carcinomas (RCC)
- transitional cell carcinomas (TCC)
- Wilms’ tumours
these are based on their histological origin
RCC histological origin
originate from the lining of the nephron
TCC histological origin
arise from epithelial lining inside the kidney
Where do wilms’ tumours originate from?
renal stem cells
Renal cancer presentation
Triad of symptoms:
1. pain in the flank
2. palpable mass in abdomen
3. haematuria
Why do we investigate for kidney cancer if there is left-sided varicocele?
- since left testicular vein drains into left renal vein which may be compressed by a renal tumour
Where does the posterior abdominal wall extend from?
- from attachments of diaphragm above to the pelvic brim below
What does the posterior abdominal wall consist of?
- lumbar spine
- psoas
- quadratas lumborum muscles
What do the gonadal vessels supply and what do they run down over?
- supply the gonads
- run down over ureters
Which lumbar spinal nerves form the lumbar plexus on the posterior abdominal wall?
L1-L4 (with a contribution of T12)
What does the lumbar plexus give rise to?
- several branches that innervate the skin and muscles of the abdominal wall and thigh
- e.g. iliohypogastric and ilioinguinal nerves
- genitofemoral nerve
- lateral femoral cutaneous nerve
- femoral nerve
- obturator nerve
What do the iliohypogastric and ilioinguinal nerves supply?
- anterior abdominal wall muscles and the skin of the external genitalia
What does the genitofemoral nerve supply?
- the skin of the external genitalia
What does the Lateral femoral cutaneous nerve supply?
- also known as lateral cutaneous nerve of the thigh
- supplies the skin over the lateral thigh
What does the Femoral nerve supply?
- large nerve that supplies the muscles and skin of the anterior thigh
- often a target for nerve blocks to provide pain relief for lower limb fractures or surgery
- relatively easy to locate in inguinal region using ultrasound
What does the obturator nerve supply?
- muscles and skin of medial thigh
At what level does the abdominal aorta termiante and bifurcate
L4
What are the paired branches that originate from the abdominal aorta?
- renal
- adrenal
- gonadal
- lumbar arteries
What forms the IVC
- union of the left and right common iliac veins at ~L5
- ascends posterior abdominal wall just right of midline
Functions of the bony pelvis
- supporting spine, torso, upper body
- locomotion
- housing and protecting the pelvic viscera
What three bones make up the bony pelvis?
- sacrum
- left hip (innominate)
- right hip (innominate)
What is the hip bone composed of?
- 3 smaller bones that fuse together (ilium, ischium and pubis)
What are the 5 articulations of the bony pelvis?
- hip joint
- sacroiliac joint
- pubic symphysis
- lumbosacral joint
- sacrococcygeal joint
Describe the hip joint
- between the head of the femur and the acetabulum (socket) of the pelvis
- the ilium, ischium and pubis of the hip bone fuse at the acetabulum
Describe the sacroiliac joint
- between the sacrum and the ilium of the hip bone
- this joint is very stable and strong and is supported by many ligaments
Describe the pubic symphysis
- between the two pubic bones
- almost no movement is permitted at the pubic symphysis
Describe the lumbosacral joint
- between the 5th lumbar vertebrae and the sacrum (an intervertebral disc lies between the two)
Describe the sacrococcygeal joint
- between the sacrum and coccyx
Iliac crest
- line drawn from the top of them is level L4/L5 disc space
- this is useful as this is a position where a lumbar punture can be performed or an epidural injection is given
Anterior superior iliac spine
- this is the most anterior point of the ilium and is palpable in most people
Iliac tubercle
- this is the most lateral point of the ilium
What does the intertubercular line mark the division of?
- the lower third of the abdomen from the middle third
- delineates the suprapubic region from the umbilical, and the iliac fossae from the flanks
Pubic tubercle
- palpable in most people
- this is most medial point of the pubic bone
Inguinal ligament
- runs from the anterior superior iliac spine to the pubic tubercle
Mid-inguinal point
- the mid-point of a line drawn from the anterior superior iliac spine to the pubic symphysis (not the pubic tubercle)
- the femoral artery is palpable here
McBurney’s point
- marks the approximate location of the base of the appendix
What are the differences between male and female pelves?
- wider, circular pelvic inlet in females (for childbirth)
- narrower, heart-shaped pelvic inlet in males
- obtuse angle formed by inferior pubic rami in females, acute angle in males
- wider and shorter sacrum in females, narrower and longer sacrum in males
Describe the arterial blood supply to the pelvis
- via left/right internal iliac arteries
- these give rise to many branches in pelvis to supply pelvic viscera
- some branches exit the pelvis to supply the perineum and gluteal region
What are the 5 key branches of the internal iliac arteries?
- vesical arteries
- uterine and vaginal arteries (in females)
- middle rectal artery
- internal pudendal artery
- superior/inferior gluteal arteries
What do the vesical arteries supply?
- the bladder (in both sexes)
- prostrate and seminal vesicles in males too
What does the middle rectal artery supply?
- the rectum
What does the internal pudendal artery supply?
- it exits the pelvis to supply the perineum
What do the superior and inferior gluteal arteries supply?
- these exit the pelvis to supply the gluteal (buttock) region
Describe the venous drainage of the pelvis
- pelvis contains several venous plexuses which drain the pelvic organs
- these plexuses unite and mostly drain into the internal iliac vein
Innervation - pelvis
- structures in pelvis are supplied by somatic, parasympathetic and sympathetic
- in pelvis, sacral spinal nerves come together to form the sacral plexus
What are the 4 key nerves arising from the sacral plexus?
- sciatic nerve
- pudendal nerve
- superior/inferior gluteal nerve
- pelvic splanchnic nerves
What are the sympathetic fibres innervating the plevic viscera derived from?
- lumbar splanchnic nerves
What are the 3 functions of the pelvic floor?
- prevent herniation of pelvic organs inferiorly, out of the pelvis
- control continence of urine and faces by providing a sphincter action on the urethra and rectum
- aid in increasing intra-abdominal pressure
What two muscles make up the pelvic floor?
- levator ani
- coccygeus
What are the three smaller paired muscles that make up the levator ani?
- puborectalis
- pubococcygeus
- iliococcygeus
Puborectalis
- U-shaped muscle attaches to pubic bones anteriorly and forms a sling around the rectum
- pulls on rectum so sharp angle is formed between rectum and anal canal, preventing defecation
- when it relaxes the path from the rectum to the anal canal straightens and faces can pass through
- contributes to control of micturition similarly
- this muscle is the most anterior in levator ani
Pubococcygeus
- lies posterior and lateral to puborectalis
- attaches to the pubic bone anteriorly
- attaches to coccyx and sacrum posteriorly
iliococcygeus
- this muscle lies lateral to pubococcygeus
- its name is slightly misleading as it attaches to the spine of the ischium (not the ilium) and the coccyx
What is the levator ani innervated by?
- by a branch of the S4 nerve
- and by some branches of the pudendal nerve (from S2-S4)
Pelvic floor weakness
- due to stretch, damage or weakened by childbirth, ageing, straining or obesity
- can lead to incontinence of urine or faeces
- can also lead to pelvic organ prolapse as they are no longer supported
Where is the perineum?
- immediatley superficial and inferior to the pelvic floor
- superficial region between pubis symphysis and coccyx
- between medial surfaces of the thighs
What can the perineum roughly be divided into?
- two triangles:
1. anal triangle
2. urogenital triangle
Anal triangle
- contains opening of anus and the external anal sphincter
Urogenital triangle
(has several layers)
1. skin (urethra and vagina opening out through the skin)
2. perineal fascia (continuation of fascia overlying abdominal wall muscles)
3. superficial perineal pouch (potential space containing erectile tissues of penis or clitoris + 3 muscles)
4. perineal membrane (strong fibrous membrane that provides support for attachment of ischiocavernosus and bulbospongiosus, it also has specific holes for urethra and vagina)
5. deep perineal pouch (space between perineal memrbane and pelvic floor muscles and contains parts of vagina, urethra and external urethral sphincter)
What are the 3 muscles in the superficial perinal pouch in the urogenital triangle?
- ischiocavernosus
- bulbospongiosus
- superficial transverse perineal muscles
What sits between the two triangles of the perineum?
- the perineal body
What is the perineal body?
- dense mass of fibrous tissue
- muscle sits in the centre of the perineum
- acts as an attachment for almost all the perineal and pelvic floor muscles including levator ani, external anal sphincter, external urethral sphincter, superficial and deep transverse perineal muscles and bulbospongiosum
What does the superficial perineal pouch contain?
- most of the erectile tissue that unites to form the clitoris or penis
- and the muscles underlying them
The corpora cavernosa in the superficial perineal pouch
- they are symmetrical and run along the ischial rami bilaterally to converge in the midline
- they form a strogn foundation for the clitoris/penis
- the parts that are attached to the ischial ramus are known as ‘crura
Where does the corpora spongiosum sit?
- in the midline
The ‘bulb’ of the penis
- expanded proximal part of the corpora spongiosum which rests on the perineal membrane
Corpus spongiosum in the female
- splits into two parts that flank the vaginal opening
- they also rest on the perineal membrane on either side of the vaginal opening
- these parts of the corpus spongiosum in females are the bulb of the vestibule (or bulb of the clitoris)
What covers the corpora cavernosa?
- ischiocavernosus muscles
Purpose of the ischiocavernosus muscles?
- helps stabilise and erect the penis and clitoris
What covers the corpus spongiosum?
- bulbospongiosus muscle
Purpose of the bulbospongiosus muscle in males?
- assists in maintaining erection by compressing the veins that drain erectile tissues
- it also contracts to squeeze any remaining urine or semen from the urethra
Purpose of the bulbosponigosum muscle in females?
- helps maintain clitoral erection
- constricts around the vaginal orifice which can help expression of fluid from the greater vestibular glands
Arterial supply to perineum
- via internal pudendal artery
(this is a branch of the internal ilias artery)
Innervation of perineum
- pudendal nerve S2-S4
- it innervates muscles in the perineum and skin of the external genitalia
- perineal structures are also innervated by autonomic nerves
True or false? Internal pudendal artery and pudendal nerve arise in the pelvis but do not enter the perineum by piercing the pelvic floor
- true
- instead they travel through the greater and lesser sciatic foramina of the pelvis
Episiotomy
- pre-emptive incision made lateral to perineal body to avoid injury to perineal body or an uncontrolled tear through the anal sphincter
List the male organs of reproduction
- paired testes
- epididymides
- vas deferentia
- seminal vesicels
- ejaculatory ducts
- bulbo-urethral glands
- prostate gland and penis
What is the vas deferens?
- tube
- carries sperm from epididymis up spermatic cord and through inguinal canal into the pelvis
- it passes from the deep inguinal ring across the side wall of the pelvis. then turns medially onto the back of the bladder where it has a dilated portion (ampulla)
- it terminates by joining duct of seminal vesicle to form ejaculation duct
Where does the ampulla of the vas deferens lie?
- medial to the seminal vesicle
Describe the seminal vesicle
- a lobulated sac
- ~4cm long
- lies lateral to ampulla of vas deferens
- duct of seminal vesicle joins vas deferens to become the ejaculatory duct which pierces the back of the prostate gland to enter the prostatic urethra
What is the role of the seminal vesicle
- secretes a thick alkaline fluid (forms the bulk of seminal fluid also known as semen)
Describe the prostate
- roughly spherical fibromuscular gland
- ~ size of a walnut
- lies against neck of the bladder and is pierced by the urethra and ejaculatory ducts
- secretions of prostate are added to seminal fluid during ejaculation
What are the prostate, seminal vesicle and vas deferens all supplied by?
- by branches of the internal iliac artery
Benign prostatic hyperplasia (BPH)
- prostate gland completely encircles urethra
- with progressive age, benign enlargement of prostate is common
- may lead to compression of urethra and inability to pass any urine
- requires catheter insertion to drain urine
What is the phrase to describe the inability to pass any urine?
- urinary retention
Prostate cancer
- common
- venous blood from prostate passes into plexus of veins which lies anterior to sacrum and communicate with veins which run up to the azygos vein in the chest
- these veins communicate with veins in vertebral bodies
- this explains why prostate cancer commonly metastasizes to the vertebrae
How can the prostate be examined?
DRE (digital rectal exam)
Describe DRE
- also known as PR (per rectum exam)
- pushing a finger into rectum via anus and flexing it anteriorly to palpate prostate which sits just anterior to anal canal and rectum
- can feel size, contour and firmness
- hard craggy prostate: concerning for malginancy
What does the female pelvis contain?
- uterus
- cervix
- vagina
- uterine tubes
- ovaries
Describe the uterus
- pear-shaped
- hollow
- ~8cm long
- communicates laterally with uterine tubes and inferiorly with vagina
- has a fundus, a body and a cervix
- body of uterus is typically angled anteriorly (ante-flexed) and lies on superior surface of bladder
- the junction between body and cervix may be tilted anteriorly (anteverted) or posteriorly (retro-verted)
What happens during conception?
- developing blastocyst implants into the uterine lining (endometrium) in the body of the uterus
- middle muscular layer of uterus (myometrium) becomes distended as pregnancy continues
- uterus is covered in a fold of peritoneum which adheres to itself at the sides of the uterus to form the broad ligament
- space behind uterus but anterior to rectum is called rectouterine pouch and is lined with peritoneum
What is the rectouterine pouch also known as?
What is it a common site for accumulation of?
- pouch of douglas
- it is the deepest point in the peritoneal cavity so it is a common site for the accumulation of intraperitoneal fluid or pus
Describe the cervix
- narrow lumen (cervical canal) which communicates with uterine cavity via internal orifice (os) and vagina via external orifice (os)
- lower part lies inside vagina creating a recess (vaginal fornices) around the cervix
How is the position of the cervix stabilised?
- by the tone of the levator ani muscle and ligaments which run from the lateral wall of cervix to lateral pelvic wall at base of broad ligament
Describe the uterine tubes (fallopian tubes)
- paired tubes carry ova from ovary towards uterine cavity
- fertilisation occurs in uterine tubes
- ~10cm long
- found running in upper border of broad ligament
- near uterus, the tubes has a narrow isthmus
- laterally the tubes have a dilated ampulla leading into a finger-like projection FIMBRIAE which are draped over the ovary
- can be clipped as a means of sterilisation
Describe the ovary
- almond shaped
- ~4cm long and 2cm wide
- attached to posterior aspect of broad ligament by a short mesentery - the mesovarium
- position is not fixed but frequently overlies in ovarian fossa formed by angle between the internal and external iliac arteries
- ureter and obturator nerve and vessels are close relations of ovarian fossa
Describe the vagina
- female organ of sexual intercourse
- excretory duct of uterus
- ~10cm long
- blind-ended region in the region of the cervix and terminates below at the introitus by opening into the vestibule (space) between labia minora
- passes through the pelvic floor
- upper 2/3 lie in pelvic cavity
- lower 1/3 lie in perineum
- closely related to bladder anteriorly and urethra is often embedded in anterior wall of lower third of vagina
Blood supply of the vagina, ovaries, cervix, uterine tubes and uterus
- branches of internal iliac artery
- except ovary (supplied by ovarian artery)
Where does the ovarian artery come from?
- direct branch of abdominal aorta
- contributes to blood supply of uterine tubes as well
What is the vulva
- collective term for all parts of the female external genitalia
- blood supply mainly by internal pudendal arteries (branches of internal iliac arteries)
- innervation via four nerves
- erectile tissues are innervated by parasympathetic nerves
What are the four nerves that innervate the vulva?
- ilioinguinal nerve
- genital branch of genitalfemoral nerve
- pudendal nerve
- posterior cutaneous nerve of the thigh
Parts of the vulva
- mons pubis
- labia majora
- labia minora
- clitoris
- vestibule
- vaginal opening
- hymen
- urinary meatus
- vestibular glands
Mons pubis
- mound of fatty tissue located in front of the pubic symphysis causing an elevation of hair-bearing skin
Labia majora
- prominent hair-bearing folds of skin that meet at the mons pubis anteriorly
Labia minora
- smaller hairless folds of skin located medial to labia majora
- fuse together anteriorly to form the hood of the clitoris
- form the boundaries of the vestibule
clitoris
- pea-sized highly sensitive tissue comprised of erectile corpora cavernosa and corpora spongiosum
- becomes engorged during sexual intercourse
Vestibule
- area between labia minora
- contains vaginal opening, urinary meatus and vestibular glands
Vaginal opening
- entrance to vagina
- also known as vaginal introitus
Hymen
- thin membrane that partially covers vaginal opening
- often ruptures during first episode of sexual intercourse and hsitorically its presence was taken as proof of virginity
- however it can rupture spontaneously, during exercise, by using tampons or menstrual cups
- may be absent altogether
Urinary meatus
- opening of urethra
- lies posterior to clitoris but anterior to vaginal opening
Vestibular glands
greater vestibule glands (bartholin’s glands)
- lie posterior to vaginal opening
- secrete a lubricant into the vagina during sexual arousal
lesser vestibule glands (skene’s glands)
- lie near urethral opening
- function of fluid they secrete is debated but may lubricate the vaginal opening or urethra or have an antimicrobial effect
Ectopic pregnancy
- blastocyte implants outside the uterus
- uterine tube is most common place for occurence
- fertilisation usually occurs in uterine tubes and zygote it swept down the uterine tubes towards the uterus by ciliated cells
- if zygote does not reach the uterus it may implant on the wall of the uterine tube
- uterine tube cannot stretch to accommodate a growing embryo and so may rupture
- cause significant pain and internal bleeding (can be life threatening)
- surgery required to remove pregnancy
Endometriosis
- endometrial tissue (which lines inside of uterus) is found outside uterus
- affects: ovaries, uterine tubes, uterine ligaments and rectouterine pouch
- rarely found outside the pelvis
- chronic pelvic pain, cyclical pain related to menstruation and pain during intercourse
- formally diagnosed using biopsy samples obtained during surgical exploration (diagnostic laparoscopy)
Gynaecological cancers
- can affect any part of female reproductory system
- pelvic pain, abnormal vaginal discharge, abnormal vaginal bleeding, urinary disturbance, abdominal swelling, fatigue and weight loss
- check for HPV in females
Describe the urinary bladder (female)
- hollow muscular organ located in pelvis below the peritoneum
- infra-peritoneal organ
- posterior to pubic symphysis and anterior to vagina and rectum
Arterial supply of the urinary bladder
- vescial branches off the internal iliac artery
Venous drainage of the urinary bladder
- vescial veins drain into the internal iliac vein
Function of urinary bladder
- stores urine and helps to squeeze urine out during micturition
- when empty it may squash down completely
- when full its superior aspect may extend above the pubic symphysis
- can accommodate ~400-600ml of urine in an adult
Where do the ureters drain into the bladder from?
the posterior aspect of the bladder near the base
What is the trigone?
- the triangular area where the ureter enters the bladder
- has a smooth wall
- ureters enter trigone at an angle forming a rudimentary valve which prevents reflux of urine into the ureters when it is full
Describe the rest of the bladder wall besides the trigone
- rest of inside wall is corrugated with folds of mucosa called rugae
- these allow the bladder to stretch without tearing when it fills
- bladder wall contains smooth muscle DETRUSOR which contracts to forcibly expel urine
What is the release of urine controlled by?
two sphincters:
1. internal
2. external urethral sphincters
Where is the internal urethral sphincter and what is it made of?
- located at base of bladder where it opens into the urethra
- composed of smooth muscle
- it is under involuntary control
Where is the external urethral sphincter and what is it made of?
- located just after the prostate in males and and is in deep perineal pouch in females
- composed of skeletal muscle
- it is under voluntary control
Innervation of urinary bladder and urethral sphincters
- somatic
- sympathetic
- parasympathetic
Somatic innervation of urinary bladder and urethral sphincters
- via branches of pudendal nerve S2-S4
- allows conscious control of external urethral sphincter
Sympathetic innervation of urinary bladder and urethral sphincters
- via branches of hypogastric nerve (sympathetic chain T12-L2)
- causes relaxation of detrusor and contraction of the internal urethral sphincter, allowing storage of urine
Parasympathetic innervation of urinary baldder and urethral sphincters
- via the pelvic splanchnic nerves S2-S4
- causes contraction of detrusor and relaxation of internal urethral sphincter, allowing initiation of micturition
Where does the urethra carry urine to and from?
- from the internal urethral orifice to the external urethral orifice (located at tip of penis in males and in vestibule in females)
Females urethra is relatively short…
~3-4cm
What are the four parts the male urethra is divided into (for description purposes)?
- preprostatic
- prostatic
- membranous
- penile parts
Urination is controlled by which parts of the brain?
- cerebral cortex
- brainstem
(+ sacral spinal cord which contains the sacral micturition centre)
Describe the bladder stretch reflex
- as bladder fils, stretch in wall is detected and relayed to sacral spinal cord via visceral afferent fibres
- synapse directly onto motor neurons
- motor neurons (Via parasympathetic fibres in pelvic splanchnic nerves) stimulate baldder contraction
The bladder stretch reflex is known as an example of a..
relfex arc
In adults and older children the reflex arc for bladder stretch is inhibited by inputs from the…
cerebral cortex
(older children and adults can detect bladder filling and conciously control when and where they urinate which is achieved by ‘potty-training’ where they develop descending pathways that inhibit the reflex when it is not convenient to urinate)
Injury to spinal cord ABOVE sacral level
2 pathways are inhibited:
1. ascending pathways conveying sensation of bladder filling to the brain (no longer aware of bladder filling)
2. descending pathways that exert voluntary, inhibitory control over the external urethral sphincter (so external sphincter is permanently relaxed)
- relfex arc still functioning but no control over it
- patient does not realise they need to pass urine and bladder automatically empties as it fills
Injury to spinal cord/cauda equina AT/BELOW level of spinal micturition centre
- reflex arc is disrupted and bladder fills without emptying
- internal urethral sphincter is permanently contracted
- as bladder continues to fill, the pressure in the bladder eventually exceeds the strength of the internal urethral sphincter and urination will occur
- this type of incontinence is ‘overflow incontinence’
- if pressure inside the bladder does not overcome the sphincter the patient develops urinary retention
- eventually urine may back up to the ureters and kidneys if a urinary catheter is not placed
Overview of the rectum
- terminal part of the large intestine
- two curves/flextures: anterior curve (sacral flexure) and posterior curve (anorectal flexure)
- ~12cm long in adult and its primary purpose is storage of faeces prior to defecation
Overview of anal canal
- most distal part of GI tract
- 4cm long in an adult
- extends from distal rectum to anus and lies in anal triangle of perineum
- two anal sphincters control defecation: internal and external anal sphinter
Internal anal sphincter
- smooth muscle
- involuntarily controlled
External anal sphincter
- skeletal muscle
- voluntarily controlled
What is the pectinate line also known as?
the dentate line
What does the pectinate line divide?
- superior part of anal canal from inferior part
- superior part is derived from endoderm
- inferior derived from ectoderm
- they are supplied by different vessels and nerves
Superior part of anal canal
- part of hindgut
- supplied by inferior mesenteric artery (superior rectal artery)
- venous drainage is via portal venous system towards the liver
- encircled by internal anal sphincter and lumen is lined by columnar epithelium (intestinal mucosa)
- internal anal sphincter is innervated by sympathetic fibres (from sympathetic trunk) and parasympathetic fibres (via pelvic splanchnic nerves)
Inferior part of anal canal
- supplied by middle and inferior rectal arteries (which originate from internal iliac arteries)
- venous blood enters systemic venous system and does not pass through the portal system
- inferior anal canal is encircled by external (voluntary) anal sphincter which is innervated by the pudendal nerve (a somatic nerve)
- stratified squamous epithelium lines the lumen
Haemorrhoids
- walls of anal canal are lined with an abundance of veins that form ‘cushions’ which aid faecal continence
- these are known ar haemorrhoids or piles
- can become excessively swollen and inflamed
- above pectinate line: painless
- below pectinate line: painful
- can be normal and present in healthy individuals or pathological
Pathological haemorrhoids
- bleed when passing stool
- if painless then presence of blood wiping after defecation may be first sign
- increased intra-abdominal pressure in excessive straining, constipation, squatting or pregnancy increases pressure in pelvic veins and can lead to haemorrhoids becoming swollen and problematic
