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Anatomy - Abdomen, pelvis and perineum
Terms in this set (172)
Describe the foregut, midgut and hindgut and their arterial blood supply.
Foregut: extends to the entry of the bile duct into the duodenum (coeliac axis)
Midgut: extends to the distal third of the transverse colon (superior mesenteric)
Hindgut: extends to the ectodermal part of the anal canal (inferior mesenteric)
Describe the embryological development of the foregut. Describe the two types of atresia. Is it the left or the right vagus nerve that is anterior to the stomach? Which bit of the duodenum is retroperitoneal and why?
Starts to divide into the oesophagus and the laryngotracheal tube at week 4.
Pure oesophageal atresia: incomplete development (8%)
Atresia with tracheo-oesophageal fistula: fistula between the trachea and the oesophagus (80%)
The distal oesophagus dilated to form the stomach and rotates so that the right side of the stomach becomes the posterior wall. This make the right vagus nerve posterior to the stomach, and the left vagus nerve anterior.
The duodenum swings to the right and its mesentery fuses with the peritoneum of the posterior abdominal wall, leaving all but the first inch retroperitoneal.
What happens to the midgut during development?
It first grows fast early, having to herniate into the umbilical cord were its apex is continuous with the vitellointestinal duct into the yolk sac.
It then returns to the abdomen at week 10, bridging the ascending colon to the right side of the abdomen with the caecum progressively taking its place.
What is a Meckel's diverticulum?
A remnant of the proximal part of the yolk stalk (vitelline duct), which extends into the umbilical cord in the embryo and lies on the antimesenteric border of the ileum.
What is the Meckel's diverticulum "rule of 2's"?
2 inches longs, located within 2 feet of the ileocecal valve, 2 times as common in males than females, 2% of the population, 2% symptomatic, 2 types of ectopic tissue -- gastric & pancreatic
What embryoligal defect can lead to malrotation?
Malrotation occurs when there is inappropriate fixation of structures. For example, if the duodenojejunal flexure does not become fixed retroperitoneally and hangs freely from the foregut,it can lead to malrotation and volvulus.
What is the cloaca? What divides it in half?
An endoderm lined cavity at the end of the hindgut that is covered at the ventral boundary by ectoderm, the cloacal membrane.
The urectal septum divides it into the bladder anteriorly, and the rectum posteriorly.
What structures make the anal canal?
1. The end of the hindgut (endoderm)
2. Invagination of ectoderm
What are the differences between the upper part of the anal canal and the lower part? What seperates the two?
The pectinate (or dentate) line separates both parts.
What may cause an imperforate anus?
Failure of the hindgut to descend, or failure of the anal pit to ascend.
What are the pronephros, mesonephros and metanephros?
Pronephros: 3rd week, transient and never functions.
Mesonephros: 4th week, degenerates also, but duct persists and becomes the vas deferens and epididymis in the male.
Metanephros: 5th week, origin of the ureter, pelvis, calyces and collecting tubules. The metanephric duct or ureteric bud must invaginate the metanephros to allow the formation of these structures.
What are clinical consequences of development anomalies in the renal tract?
1. Failure of metanephric duct to invaginate and fuse with the metanephros causing congenital autosomal recessive polycystic kidneys.
2. Kidney that fails to migrate cranially and remains in the pelvis (ie. pelvic kidney).
3. Horseshoe kidney where two metanephric masses fuse in the mid-line.
4. Double ureter if the ureteric bud branches early. rarely, the second branch can be open ectopically, causing urinary incontinence via the vagina or directly into the urethra.
5. Congenital absence of a kidney if the metanephros fails to develop. (ie. agenesis)
What primitive structures are precursors of the bladder?
1. Cloaca (divides into: vesicourethral + pelvic = phalic portions)
2. Mesonephric ducts
What does the mesonephric duct participate in forming in the bladder?
It forms the trigone of the bladder (as well as the dorsal wall of the prostatic urethra).
Note: the urachus is at the apex if the bladder and joins with the umbilicus.
What makes the urethra in females? What about in males?
Females: the urethra is derived from the vesicourethral portion of the cloaca.
Males: the prostatic part of the urethra derives from the vesicourethral part of the cloaca and the caudal end is reived from the mesonephric duct. The shaft is formed by fusion of the genital (urethral) folds enclosing the phalic portion of the urogenital sinus (UG).
What are clinical complications of inappropriate development of the urethra?
Hypospadia: failure of fusion of the genital folds
Epispadia: where the dorsal wall of the urethra is partially or completely absent
What are the precursors to the testes? How far into intra-uterine development does it take for the testes to descend and reach the scrotum?
3rd month: lie in the pelvis
7th month: pass down the inguinal canal
8th month: reach the scrotum
What is the name given to the prolongation of peritoneum that the testes must carry with them when descending into the scrotum? What does this become at birth?
The testes slide down taking the processus vaginalis (layer of peritoneum) with them through the inguinal canal. At birth, this disstal covering layer becomes the tunica vaginalis.
What is the blood supply, lymphatic drainage and nerve supply of the testis associated to? What happens if the processus vaginalis fails to obliterate at birth?
The testis develops on the posterior abdominal wall and therefor it's supply is associated with this.
Hydrocele: caused by an accumulation of serous fluid within the tunica vaginalis. It may arise in response to neighboring infections or tumors, or it may be idiopathic. It is readily distinguished from collections of pus, lymph, and blood by allowing a beam of light to pass through (transluminescence).
What are the two layers that make the superficial fascia of the abdominal wall? Why are these clinically relevant?
1. Camper's fascia: superficial fatty layer
2. Scarpa's fascia: deep fibrous layer. In the midline, it is firmly attached to the linea alba and the symphysis pubis. It continues into the anterior part of the perineum where it is firmly attached to the ischiopubic rami and to the posterior margin of the perineal membrane. Here, it is referred to as the superficial perineal fascia (Colles' fascia).
These fascial planes are important in the spread of infection. Fluid from the perineal region (e.g., resulting from a ruptured urethra) can spread into the abdominal wall between Scarpa's fascia and the underlying investing (deep) fascia of the external abdominal oblique muscle and aponeurosis. Also, an ectopic testis in the groin cannot descend any lower than the thigh because of the attachement of Scarpa's fascia to the deep fascia of the thigh.
Name the 4 abdominal wall muscles. Name their origin, insertions and nerve supply.
1. Rectus abdominis:
Origin: 5th, 6th and 7th costal cartilages
Insertion: pubic crest + tendinous intersections to the xiphoid, umbilicus and halfway between the two
Nerve supply: T7 - T12
2. External oblique (downward and medially)
Origin: outer surface of the lower 8th rib
Insertion: linea alba, pubic crest, pubic tubercle, ant. half of the iliac crest
Nerve supply: T7 - T12
3. Internal oblique (upward and medially)
Origin: lumbar fascia, lat 2/3 of iliac creat and lateral 2/3 of inguinal ligament
Insertion: linea alba and pubic crest via the conjont tendon
Nerve supply: T7 - T12 + L1 (iliohypogastric and ilioinguinal nerves)
4. Transversus abdominis
Origin: deep surface of the lower 6th costal cartilage, lumbar fascia, ant. 2/3 of the iliac crest, lateral 1/3 of the inguinal ligament
Insertion: linea alba and pubic crest via the conjoint tendon
Nerve supply: T7 - T12 + L1 (iliohypogastric and ilioinguinal nerves)
What is the rectus sheath? What is the crescentic line or arcuate line of Douglas? Why is it relevant?
The rectus sheath is an aponeurotic sheath containing all the abdominal wall muscles. Depending on your positioning in the abdomen, it is different.
The crescentic line or the Arcuate line of Douglas marks the change in the disposition of the rectus sheath. It is located midway between the umbilicus and the pubic symphysis.
A: above the crescentic line
B: below the crescentic line
What is Spigelian hernia? Where is it located?
A hernia that occurs at the level of the arcute line of Douglas along the semilunar tendenous zone.
Name 5 abdominal incision. Where are they located?
What structures will you cut through with a midline abdominal incision?
2. subcutaneous fat.
3. superficial fascia (x2 layers in lower abdomen)
4. linea alba
5. extraperitonal fat
What structures will you cut through with a subcostal or Kocher's abdominal incision?Why is this clinically relevant?
2. subcutaneous fat
3. superficial fascia
4. anterior rectus sheath
5. rectus abdominis
6. posterior rectus sheath
7. extraperitoneal fat
Right side: cholecystectomy, kidneys
Left side: elective splenectomy, kidneys
What structures will you cut through with a Gridiron or McBurney abdominal incision? Why is this clinically relevant?
2. Camper's fascia
3. Scarpia's fascia at the lower end of the incision
4. external oblique aponeurosis
5. internal oblique aponeurosis
6. transversus msucle
7. extraperitoneal fat
Used in open appendicectomy.
What structures will you cut through with a paramedian abdominal incision?
Use is declining
2. superficial fascia
3. anterior rectus sheath amd tendinous intersections (segmental vessels enter here and bleeding will occur)
4. rectus muscle (which is retracted laterally)
5. posterior rectus sheath (bellow the arcuate line, this would only be transversalis fascia)
6. extraperitoneal fat
What structures will you cut through with a pararectus or Battle abdominal incision? Why is this clinically relevant?
Incision at the lateral border of the rectus below the umbilical level.
2. Camper's fascia
3. Scarpa's fascia
4. anterior rectus sheath
5. rectus muscle (retracted medially)
6. posterior rectus sheath
7. extraperitoneal fat
Occasionally used for appendicectomy but mostly for peritoneal dialysis catheters.
List all the abdominal incisions you know.
Visualize the following abdominal incisions.
What is the inguinal canal? What does it transmit in the male vs. the female?
Oblique passage in the lower abdominal wall. Passes from deep to superficial rings and is about 4cm long.
Male: spermatic cord + ilioinguinal nerve
Female: round ligament of the uterus + ilioninguinal nerve
What are the anatomical relations of the inguinal canal?
- Camper's fascia
- Scarpa's fascia
- external oblique aponeurosis
- internal oblique in lateral 1/3 of the canal
- medially: conjoit tendon
- laterally: transversalis fascia
- lower arching fibres of internal oblique and transversus
- lower recurved edge of external oblique = inguinal ligament
Describe the relations of the deep inguinal ring.
Defect in transversalis fascia.
Lies 1cm above the midpoint of the inguinal ligament, immediately lateral to the inferior epigastric vessels.
Describe the relations of the superficial inguinal ring.
V-shaped defect in the inguinal ligament.
Lies above and medial to the pubic tubercle.
What is the rule of three when recalling the contents of the spermatic cord?
''3 layers of fascia, 3 arteries, 3 nerves and 3 other structures''
Layers of fascia:
1. external spermatic fascia from the external oblique aponeurosis
2. cremasteric fascia and cremaster muscle from the internal oblique muscle
3. internal spermatic fascia from the transversalis fascia
1. testicular artery
2. cremasteric artery
3. the artery of vas
1. genital branch of the genitofemoral nerve to cremaster
2. sympathetic nerves
3. ilioinguinal nerve (actualy lie son the cord and not within it)
1. vas deferens
2. pampiniform plexus of veins
What is the femoral canal a prolongation of? What are the boundaries of the femoral ring? What are its contents?
The femoral canal is a prolongation of the transversalis fascia and teriorly and the iliacus fascia posteriorly prolonged over the femoral artery, vein and canal (but NOT THE NERVE)
The femoral ring is the upper opening of the femoral canal. Its bounderies are:
Anterior: inguinal ligament
Posterior: pectineal ligament
Lateral: femoral vein
Medial: lacunar ligament
Contents of the femoral canal:
3. lymph node (Cloquet's node)
The canal allows for a pathway for lymphatics of the lower limb to the external iliac nodes.
Note: the image shows the femoral sheath, do not confuse with the femoral canal.
What is the Hesselbach's triangle? What are its boundaries?
Area through which a direct hernia will push and create a passage.
Laterally: inferior epigastric artery
Inferiorly: inguinal ligament
Medially: lateral border of the rectus abdominis muscle
What is a direct inguinal hernia? How can you differentiate it from an indirect hernia?
A direct hernia bulges through the posterior wall of the inguinal canal (transversalis fascia) , medial to the inferior epigastric artery at the level of the Hesselbach's triangle.
The key way to differentiate the two during surgery is by determining if the defect is medial or lateral to the epigastric vessels.
Clinically, if you reduce the hernia, apply pressure over the deep inguinal ring, then ask a patient to cough and notice the bulge re-appear, then it is a direct hernia.
What is an indirect inguinal hernia? How can you differentiate it from a direct hernia?
An indirect hernia passes through the deep inguinal ring of the inguinal canal and into the scrotum. It is covered by the layers of the cord.
During surgery, if the bulge passes laterally to the inferior epigastric vessels and into the inguinal canal, then it is indirect.
Clinically, if you reduce the hernia, apply pressure over the deep inguinal ring, then ask a patient to cough and notice the bulge does not re-appear, then it is an indirect hernia that is controlled by your finger.
What is a femoral hernia? Who is this more commonly seen in?
Bowel that protrudes below the inguinal ligament that lies bellow and lateral to the pubic tubercle.
Because the femoral ring is more narrow than the inguinal canal and the lacunar ligament forms a 'sharp' medial border, irreducability and strangulation are more common in femoral hernias.
More common in females because they have a wider pelvis and therefor a larger canal.
How do you differentiate hernias in the groin?
What is the peritoneum? What epithelium is it made of? How many layers does it have? What about cavities?
It is the serous membrane of the abdominal cavity lines by simple squamous epithelium.
It has 2 layers:
1. Parietal layer: lines the abdominal and pelvic wall
2. Visceral layer: covers contained organs
It is divided into 2 cavities:
1. Main cavity (greater sac)
2. Smaller cavity (lesser sac) = omental bursa
What is the rectouterine pouch (of Douglas)?
Pouch of parietal peritoneum between the uterus and the rectum.
How does the peritoneum produce the broad ligament of the uterus ?
The peritoneum passes off lateral margins of the uterus to the pelvic wall, forming the broad ligaments with the Fallopian tubes in the upper border.
Describe the anatomical relations of the lesser sac (omental bursa) of the peritoneum.
Anteriorly: lesser omentum and stomach
Superiorly: caudate lobe of the liver
Inferiorly: projects downwards to the transverse mesocolon
To the left: spleen, gostrosplenic and lienorenal ligaments
To the right: opens into the greater sac via the epiploic foramen
Describe the anatomical relations of the epiploic foramen (or Formane of Winslow).
Anteriorly: free edge of the lesser omentum containing the bile duct to the right, the hepatic artery to the left and the portal vein behind
Posteriorly: inferior vena cava
Inferiorly: first part of the duodenum
Superiorly: caudate process of the liver
What is the Pringle's manoeuvre and how does it relate to the epiploic foramen (Foramen of Winslow)?
Manoeuvre where you compress the hepatic artery between your finger and thumb in the free edge of the lesser omentum.
Useful if the cystic artery is torn during cholecystectomy or if there is gross haemorrhage following liver trauma.
What is the coronary ligament in the abdomen?
Parts of the peritoneal reflections that hold the liver to the inferior surface of the diaphragm.
What are subphrenic spaces/ Why are they clinically relevant?
These are potential spaces below the liver in relation to the diaphragm, which may be site of collections or abscesses. (eg. after perforated ulcer, perf. appendicitis or diverticulitis). Most abscesses are drained percutaneously under US or CT control.
What 3 main muscles make the posterior abdominal wall?
1. Psoas major
2. Quadratus lumborum
What are the origins, insertion, nerve supply, action and important relations of the psoas major muscle?
The psoas muscle is a massive fusiform muscle extending from the lumbar region of the vertebral column across the pelvic brim and under the inguinal ligament off the thigh.
Origin: T12-L5 transverse processes
Insertion: lesser trochanter of the femur
Nerve supply: L2, L3
Action: flexion and medial rotation of extended thigh
- psoas sheath extends beneath the inguinal ligament
- lumbar nerves forming the lumbar plexus in the substance of the muscle
- the ureter, gonadal vessels and IVC lie on it
- there can be a retrocaecal or retrocolic appendix lying anteriorly
What are the origins, insertion, nerve supply, action and important relations of the quadratus lumborum muscle?
Origin: iliolumbar ligament and adjacent portion of the iliac crest
Insertion: medial half of lower border of the 12th rib and by four small tendons into the transverse processes of the upper four lumbar vertebrae
Anterior: colon, kidney, subcostal, iliohypogastric, ilioinguinal nerves
What are the origins, insertion, nerve supply, action and important relations of the iliacus muscle?
Origin: greater part of the iliac fossa extending into the sacrum
Insertion: lateral aspect of tendon of psoas major onto the lesser trochanter
Nerve supply: L2, L3
What structures make the posterior abdominal wall?
1. psoas muscles
2. quadratus lumborum
1. bodies of the lumbar vertebrae
3. wings of the ilium
1. abdominal aorta
4. suprarenal glands
5. lumbar sympathetic chain
What is the 'psoas test' or 'psoas sign'?
When an inflamed retrocaecal or retrocolic appendix lies in contact with psoas, the resulting spasm in the muscle leads to persistent flexion of the hip and pain on attempted extension.
Why is it clinically relevant that the tendon of the psoas muscle extends to the inguinal ligament?
Pus from a tuberculous infection of the lumbar vertebra may track down the sheath and present as a swelling bellow the inguinal ligament (psoas abscess).
Where does the abdominal aorta begin and end? What are its anatomical relations?
Enters the abdomen between the crura of diaphragm and lies on the vertebral bodies.
Extends from the 12th thoracic vertebra to the 4th lumbar vertebra where it divides into the common iliac arteries.
Anterior (from above down): lesser omentum, stomach, coeliac plexus, pancreas, splenic vein, left renal vein, 3rd part of the duaodenum, root of the mesentery, small intestine, aortic plexus, peritoneum
Posterior: bodies of the upper 4 lumbar vertebra, left lumbar veins, cisterna chyli
Right side: IVC, thoracic duct, azygos vein, right sympathetic trunk
Left side: sympathetic trunk
What are the branches of the abdominal aorta?
Where do the common iliac arteries begin and end? What are their anterior anatomical relations?
Arise at he bifurcation of the aorta at the level of the 4th lumbar vertebra.
They end at the level of the sacroiliac joint where they bifurcate into the internal and external iliac arteries.
Anterior relations: peritoneum, small intestine, ureters, sympathetic nerves
What are the differences between the right and left common iliac vessels?
Right common iliac artery is longer, the aorta being on the the left side of the spine.
The left common iliac vein crosses behind the right common iliac artery.
Left common iliac artery is crossed anteriorly by the inferior mesenteric artery.
Left common iliac vein is below and medial to the left common iliac artery.
Describe the anatomy and path of the external iliac artery. What important branch does it give off?
Runs along the brim of the pelvis on the medial side of psoas major.
It passes below the inguinal ligament to form the femoral artery.
Gives off inferior epigastric artery immediately before passing below the inguinal ligament.
Describe the anatomy and path of the internal iliac artery. What organs do its branches supply?
Passes backwards and downwards into the pelvis between the ureter and internal iliac vein.
At the level of the greater sciatic notch, it divides into anterior and posterior branches (trunks).
Branches supply the:
- pelvic organs
- anal canal
Describe the start and end of the inferior vena cava as well as is path in the abdomen.
Formed by the junction of the common iliac veins at the level of the 5th lumbar vertebra. It lies right of the aorta as it ascends. it is separated from the aorta by the right crus of the diaphragm when the aorta passes behind the diaphragm.
It passes through the diaphragm at T8 then transverses the pericardium and drains into the right atrium.
What are the anterior and posterior anatomical relations of the inferior vena cava?
- mesentery, 3rd part of duaodenum, pancreas, 1st part of duodenum, portal vein, posterior surface of the liver, diaphragm
- (from above downwards) arteries: hepatic, right testicular, right colic, right common iliac
- vertebral column, right crus of diaphragm and psoas major, right sympathetic trunk, right renal artery, right lumbar arteries, right suprarenal arteries, right inferior phrenic artery, right suprarenal gland
What are the tributary veins of the inferior vena cava?
- lumbar branches
- right gonadal vein
- right venal vein
- left renal vein
- right suprarenal vein
- phrenic vein
- hepatic vein
Where does the lumbar sympathetic chain start and end? Where does it travel? Why is this clinically relevant?
Commences deep to the medial arcuate ligament of the diaphragm, lies against the bodies of the lumbar vertebra, passes deep to the iliac vessels to continue as the sacral trunk and has both its ends converge as the ganglion impar in front of the coccyx.
Resection of a AAA and extensive pelvic dissection can cause trauma to the sympathetic chain and therefor cause compromise to ejaculation in men. On the other hand, sympathectomy can be undertaken for plantar hyperhidrosis or vasospastic conditions.
What are the 4 muscles of the pelvic floor and wall?
1. levator ani
3. piriformis (on the front of sacrum)
4. obturator internus (on the lateral wall of true pelvis)
Describe the origin, insertion, nerve supply and actions of the levator ani muscle.
Muscle that acts as the principal support of the pelvic floor.
Origin: back of the body of the pubis to the spn eof the ischium.
Insertion: forms a sling around the prostate or vaginainserting into the perineal body. Also forms a sling around the rectum and the anus inserting into and reinforcing the deep part of the anal sphincter at the anorectal ring (puborectalis).
Nerve supply: perineal branch of S4 (pelvic surface) + pudendal nerve (perienal surface)
- resists downwards pressure from abdominal muscles
- sphincter action on the rectum and vagina
- helps increase abdominal pressure during defecation and mictruation
Describe the origin, insertion, nerve supply and actions of the coccygeus muscle.
Small triangular muscle in the same plane as levator ani.
Origin: spine of the ischium.
Insertion: side of the coccyx and lowest part of the sacrum
Nerve supply: perineal branch of S4
- holds the coccyx in natural forward position
- holds pelvic fascia
What are the two sections of the perineum?
1. the anteror urogenital perineum
2. the posterior anal perineum
What are the borders of the urogenital triangle? What is it made of? What pierces through this structure in men vs. women?
The urogenital triangle is bordered the ischiopubic inferior rami and a line joining the ischial tuberosities (which passes right in front of the anus). It is made of a perineal membrane that is pierced by the urethra in men, and by the urethra and vagina in women.
In men, the deep perineal pouch contains the bulbourethral glands (of Cowper) whose ducts pierce the perineal membrane to open into the bulbous urethra.
Describe the contents of the superficial perineal pouch in the male.
This pouch contains
- the bulbospongious muscle that covers the corpus spongiosum
- the crura of the penis (each crus is surrounded by an ischiocavernous muscle)
- superficial transverse perineal muscle running transversely from the perineal body to the ischial ramus
What does the deep perineal pouch contain in men?
- membranous urethra
- sphincter urethra
- bulbourethral glands
- deep transverse perineal muscles
- internal pudendal vessels
- dorsal nerves of the penis
What is the perineal body? What attaches to it? Why is this clinically relevant?
It is a fibromuscular nodule lying in the middle bewteen the anterior and posterior perineum.
The following muscles attach to it:
1. anal sphincter
2. levator ani
4. transverse perineal muscles
Clinical: if this is torn during childbirth, it will cause considerable weakness in the pelvic floor.
What is the posterior anal perineum? What structures does it contain?
Triangular area lying between the ischial tuberosities on each side of the coccyx.
1. anus and its sphincters
2. levator ani
3. ischiorectal fossa
What are the ischiorectal fossae? What are their boundaries? Why is this clinically relevant?
Triangular shaped spaces made of fat that are crossed by the inferior rectal vessels and nerves from lateral to medial.
Medial: fascia over the levator ani and the external anal sphincter
Lateral: fascia over the obturator internus
Anterior: extends forwards into the urogenital diaphragm
Posterior: limited by the sacrotuberous ligaments and the origin of the gluteus maximus
- the internal pudendal vessel and pudendal nerve lie on the lateral wall of the fossa in the pudendal canal (of Alcock) - this can be compressed during Forceps delivery causing regional anaesthesia
- both ischirectal fossae communicate behind the anus, allowing infection to pass from one to the other (secondary to boils or abscesses on the perianal skin)
What are the 3 main parts of the penis?
1. root: attaches to the perineal membrane, the pubic rami (by 2 strong processes) and the pubic symphysis (by the suspensory ligament)
Describe the anatomy of the glans of the penis. What is the frenulum? What is the corona? What is the prepuce?
The glans is the extremity of the penis. it contains the external urethral meatus.
Frenulum: fold of mucous membrane continuous with the prepuce (or foreskin).
Corona: projecting edge of the glans, behind which is a constriction.
What two structures make the body of the penis?
1. Corpora cavernosa:
- separated posteriorly to form the two crura that attach to the medial margins of the ischial and pubic rami
- attached to the pubic symphysis by the suspensory ligament
- groove on upper surface for the dorsal vein + groove on lower surface for the corpus spongiosum
2. Corpus spongiosum
- commences at the perineal membrane with the bulb (that is surrounded by the bulbospongiosus muscle)
- runs on the under-surface of the corpora cavernosa
- the urethra pierces the bulb on its upper surface and runs in the middle of the corpus spongiosum
What are the 3 divisions of the male urethra?
1. prostatic urethra = 3 cm
2. membranous urehtra = 2 cm
3. spongy urethra = 15 cm long, traverses the corpus spongiosum
Describe the anatomy of the prostatic part of the urethra. What structures join to make the ejaculatory ducts?
This part of the urethra passes through the prostate.
There is, in the middle, a prostatic utricle. (contracts during sex to open the ejaculatroy ducts)
It has a prostatic sinus, into which 15 to 20 prostatic ducts empty.
Ejaculatory ducts (on either side of the prostatic utricle) = union of the duct of the seminal vesicle + terminal part of the vas deferens
What is a straddle injury to the penis?
When there is trauma to the penis causing rupture of the urethra by an object that crushes the urethra against the edges of the pubic symphysis bone.
Describe the anatomy of the female urethra.
- 4cm long
- lies immediately infront of the vagina
Describe the structures that make the female genitalia (or vulva).
1. Mon pubis
2. Labia majora
3. Labia minora
4. Vestibule (contains the urethral and vaginal orifices)
5. Vaginal orifice (guarded in the virgin by a thin mucosal fold called the hymen)
7. Greater vestibular or Bartholin's glands
Describe the anatomy of the clitoris.
Contains 2 corpora cavernosa attached at the pubic rami.
the free extremity of the glans is formed by the corpus spongiosum.
What the vestibular or Bartholin glands secrete? Where are they positioned?
Bartholin glands are pea sized mucus secreting glands lying deep to the posterior part of the labia majora.. The ducts open on the labia minora external to the hymen.
If blocked, this can cause a Bartholin's cyst.
Describe the anatomy of the scrotum. Why does the scrotum often bruise following hernia repair?
Scrotum contains the testicles suspended by the spermatic cord. There is a median raphe.
Clinical: the subcutaneous tissue is continuous with the fascia of the abdominal wall which is why urine or blood may gravitate into the scrotum as bruising following hernia repair.
Also, the scrotum will become oedematous in cardiac or renal failure.
What does the processus vaginalis become after development?
It becomes the tunica vaginalis.
Failure of closure of the processus vaginalis can increase the risk of developing a hydrocele, haematocele, inguinal hernia and testicualr torsion.
What structures do you encounter when undertaking a surgical approach of the testis?
1. scrotal skin
2. dartos muscle
3. external spermatic fascia
4. cremaster muscle in cremasteric fascia
5. internal spermatic fascia
6. parietal layer of tunica vaginalis
7. visceral layer of the tunica vaginalis
8. tunica albuginea
Where is the sperm produced in the testicle? Once produced, where is it transported to?From there, how does it reach the ejaculatory ducts?
Sperm is produced in the seminiferous tubules. It is then transported to the epididymis. From there, it goes through the vasa (ductus deferens) and joins with the seminal vesicles prior to forming the common ejaculatory ducts.
What is a hydatid of morgagni (or appendix testis)? Why is this clinically relevant?
A small stalked body located either at the upper extermity of the testis of epididymis.
The appendix of testis can, occasionally, undergo torsion (i.e. become twisted), causing acute one-sided testicular pain and may require surgical excision to achieve relief. One third of patients present with a palpable "blue dot" discoloration on the scrotum. This is nearly diagnostic of this condition. If clinical suspicion is high for the serious differential diagnosis of testicular torsion, a surgical exploration of the scrotum is warranted. Torsion of the appendix of testis occurs at ages 0-15 years, with a mean at 10 years, which is similar to that of testicular torsion
What is the blood supply and lymphatic drainage of the testicle? Why is this clinically relevant?
Testicular artery arising from the aorta. It anastomoses with the artery of the vas.
Artery of the vas is a branch from the internal iliac artery that supplies the vas deferens and epididymis.
Venous drainage is by the pampiniform plexus that becomes the testicular vein.
Clinical; the right testicular vein drains straight into the IVC, however, the left testicular vein drains into the left renal vein. A left-sided varicocele could be a sign of left-sided renal malignancy obstructing the left testicular vein.
Lymphatic drainage is to the para-aortic nodes!
Where does the oesophagus begin and end? What are it's 3 parts?
Begins at the cricoid cartilage and ends at the cardiac orifice of the stomach.
2. thoracic (oesophageal hiatus at T10)
What are the anterior, posterior, left and right anatomical relations of the cervical oesophagus?What is the blood supply?
Anterior: trachea, thyroid gland
Posterior: lower cervical vertebrae, prevertebral fascia
Left: left common artery, left inferior thyroid artery, left subclavian artery, thoracic duct, recurrent laryngeal nerve
Right: right common carotid artery, recurrent laryngeal nerves
The recurrent laryngeal nerves lie on either side in the groove between the trachea and the oesophagus.
Arterial supply: inferior thyroid arteries.
Venous drainage: inferior thyroid veins.
What are the anterior, posterior, left and right anatomical relations of the thoracic oesophagus? What is the blood supply?
Anterior: left common carotid artery, trachea, left main bronchus
Posterior: thoracic vertebrae, thoracic duct, hemiazygos vein, descending aorta below
Left: left subclaivian artery, aortic arch, left vagus nerve and its recurrent laryngeal branch, thoracic duct, left pleura
Right: right pleura, azygos vein
Arterial supply: branches of the aorta
Venous drainage: azygos vein
At what vertebral level does the oesophagus enter the stomach?
What is the nerve supply to the upper 1/3 of the oesophagus? What about below the root of the lung?
- parasympathetic: recurrent laryngeal nerve
- sympathetic: middle cervical ganglion via the inferior thyroid artery
Below the root of the lung:
- parasympathetic: vagus nerves
- sympathetic: oesophageal plexus
Describe the epithelium and muscles of the oesophagus.
Epithelium: stratified squamous epithelium
- inner circular muscle
- outer longitudinal muscle
- upper 1/3: striated (for swallowing)
- lower 2/3: smooth (for peristalsis)
What are the 3 areas where foreign bodies are more likely to get stuck in the oesophagus? Where are oesophageal varices more likely to occur?
1. commencement of the oesophagus
2. where the oesophagus is crossed by the left main bronchus
Oesophageal varices are more common in the lower 1/3, where there is a porto-systemic anastomosis of the azygos vein (systemic) and the gastric vein (portal).
describe the various compartments of the stomach. What is the incisura angularis? What is the prepyloric vein of Mayo?
- J shaped organ
- Has a lesser and greater curvature, to which the lesser and greater omentum are attached.
- Has a cardia, fundus, body and pyloric part
- The incisura angularis = notch formed by the junction of the body with the pyloric antrum
- A thickened pyloric sphincter surrounds the puloric canal.
- The Prepyloric vein of Mayo is a vein that marks the crossing from the pylorus to the duodenum.
What are the anterior and posterior relations of the stomach? Why is this clinically relevant?
Anterior: (from L>R) diaphragm, abdominal wall, left lobe of the liver
Posterior: aorta, pancreas, spleen, left kidney and suprarenal gland, transverse mesocolon and colon (by lesser sac of peritoneum)
A posterior gastric ulcer or carcinoma may erode into the pancreas giving rise to pain in the back.
What is the arterial blood supply to the stomach? Why is this clinically relevant?
1. Left gastric artery (from CA) that anastomoses with the 2. Right gastric artery of the Hepatic artery
3. Right gastro-omental artery (from the gastroduodenal branch of the Hepatic artery) that anastomoses with the 4. Left gastro- omental artery.
5. Short gastric arteries (from the Splenic artery)
Ulcer in the lesser curve can erode the right or left gastric artery causing haematemesis and malaena.
What is the lymphatic drainage of the stomach? Why is this clinically relevant?
Gastric, gastroomental, and pyloric lymph nodes that all drain into the coaeliac axis.
Retrograde spread of carcinoma may occur in the hepatic lymph nodes at the Poarta Hepatis causing external compression of the bile ducts with obstructive jaundice.
What is the nerve supply to the stomach?
Parasympathetic: vagus nerve (CN X)
Anterior vagus nerve = pyloric branch
Posterior vagus nerve = coeliac branch to the posterior surface of the stomach
Sympathetic: coeliac plexus (T5-T12)
What are the layers and structures of the gastric mucosa? What cells are present in the cardia area? What about the body? What about in the pyloric area?
Gastric mucosa = columnar epithelial cells that secrete mucus
- Cardia: mucus secreting cells
- Fundus and body: Parietal (oxyntic cells) + Chief (zygomen) cells
- Antrum and Pylorus: ''G cells'' (Gastrin) + mucus secreting cells.
Describe the 4 parts of the duodenum. Why part marks the transition from the foregut to the midgut?
1st part: (superior) Intra-peritoneal
Anterior: liver and gallbladder
Posterior: portal vein, CBD, gastroduodenal artery, IVC
2nd part: (descending) Retroperitoneal
- Curves around the head of the pancreas
- Bile ducts + main pancreatic duct merge and form the Ampulla of Vater
3rd part: (horizontal) Retroperitoneal
Crosses the IVC, the aorta and 3rd vertebra
4th part: (ascending) Retroperitoneal
You can identify the duodenojejunal flexure at the end of the duodenum with the suspensory ligament of Treitz (a peritoneal fold descending from the right crus of the diaphragm to the termination of the duodenum)
Describe in more detail the anatomy of the second part of the duodenum.
1. Common Hepatic Duct
2. Cystic duct
3. Superior part of the duodenum
4. Hepatic ducts
5. Cystic duct
6. Common bile duct
7. Main pancreatic duct
8. Hepatopancreatic Ampulla (of Vater)
Which parts of the duodenum are retroperitoneal?
Only the 1st part is intra-peritoneal.
The 2nd, 3rd and 4th parts are retroperitoneal.
What structures are retroperitoneal? What mneumonic is there to remember these?
S: suprarenal (adrenal) gland
D: duodenum (second, third and fourth parts)
P: pancreas (except tail)
C: colon (ascending and descending)
What is the arterial blood supply to the duodenum? Why is this clinically relevant?
- Superior pancreaticoduodenal artery (from the gastroduodenal artery)
- Inferior pancreaticoduodenal artery (from the superior mesenteric artery)
These both supply the duodenum and the head of the pancreas.
Erosion of the posterior duodenal ulcers into the gastroduodenal artery will cause haematemesis and melaena.
How long is the small intestine? What are the two parts of the small intestine? How do you differentiate them in surgery?
- upper half
- thicker wall with larger and more numerous circular folds of mucosa (valvulae coniventes or plicae circulares)
- greater diameter
- lower half
- smaller and fewer valvulae coniventes
Hoe does the blood supply to the jejunum differ from the ileum?
- The arteries form one or two arcades some distance from the free edge of the mesentery, and long straight branches from these arcades run to supply the jejunum.
- The arterial supply forms several rows of arcades in the mesentery and the final straight arteries to the ileum are shorter and more numerous than in the jejunum.
What does the small bowel attach to? What does this structure contain?
Small bowel attaches to mesentery which contains:
- superior mesenteric vessels (enter the mesentery anterior to the 3rd part of the duaodenum)
- lymph nodes
- autonomic nerves fibres
How long is the large intestine? What are the large parts of the large intestine?
- caecum with vermiform appendix
- ascending colon
- hepatic flexure
- transverse colon
- splenic flexure
- descending colon
- sigmoid colon
- anal canal
Describe the anatomy of the caecum. What organ can you find here?
- dilated blind-ended pouch in the RIF
- completely covered by peritoneum
- ileocaecal valve is present between the caecum and ascending colon
Appendix = arises from the posteromedial aspect of the caecum (2.5cm below the ileocaecal valve)
Is the ascending colon covered by peritoneum? What are the anatomical relations of the ascending colon?
Yes. It is covered on anterior and lateral aspects by peritoneum.
- quadratus lumborum
- perineal fascia over lateral aspect of kidney
What are the anatomical relations of the transverse colon?
Superior: liver, gallbladder, greater curve of the stomach, spleen
Inferior: coils of small intestine
Anterior: anterior layers of the greater omentum
Posterior: right kidney, second part of the duodenum, pancreas, small intestine and left kidney
What are the anatomical relations of the descending colon?
Posterior: left kidney, quadratus lumborum and iliacus
Anterior: coils of small intestine
Where is the sigmoid colon? What does the sigmoid colon rest on in the man vs. in the female?
Men: rests on the bladder
Women: related to the uterus and posterior fornix of the vagina
What is the difference between taenia coli and appendices epiploicae?
- 3 flattened bands of longitudinal muscle that pass from the caecum to the rectosigmoid
- converge at the base of the appendix
- fat-filled tags
- most common in the sigmoid
- absent on the appendix, caecum and rectum
What is the blood supply to the appendix? Why is this clinically relevant?
Arterial supply: bears a mesentery containing the appendicular artery which is a branch of the ileocolic artery
Clinical: the appendicular artery is an end-artery and in acute appendicitis, may thrombose and rapidly cause gangrene with perforation of the appendix.
What are the different positions the appendix can lie? Why is this clinically relevant?
75% lies behind the caecum or colon (ie. retrocaecal or retrocolic)
5% preileal or retroileal
Clinical: a long pelvic appendix may hang down and irritate the bladder, causing frequency and simulating cycstitis.
Is the rectum entirely covered in peritoneum?
Posterior aspect: extraperitoneal
Upper 1/3: covered by peritoneum on front and sides
Middle 1/3: covered by peritoneum only on the anterior aspect
Lower 1/3: completely extraperitoneal
What are the anatomical relations of the rectum women?
rectouterine pouch (of Douglas) and posterior wall of the vagina
sacrum, coccyx, lower sacral nerves, middle sacral artery
bellow the peritoneal reflexion lies the levator ani and coccygeus.
What are the anatomical relations of the rectum in men?
rectovesical pouch , base of bladder, seminal vesicles and prostate + a layer of fascia (of Denonviliers) lies in front separating the rectum from the prostate
sacrum, coccyx, lower sacral nerves, middle sacral artery
bellow the peritoneal reflexion lies the levator ani and coccygeus.
Describe the blood supply to the large intestine. What are the branches of the superior and inferior mesenteric arteries and what do they supply? What is the name of the artery where an anastamosis between these two arteries occurs?
Superior mesenteric artery:
1. ileocolic artery: caecum and begining of ascending colon
2. right colic artery: ascending colon
3. middle colic artery: transverse colon
Inferior mesenteric artery:
1. left colic artery: descending colon
2. sigmoid branches: sigmoid colon
3. superior rectal artery: rectum + upper half of the anal canal
Marginal artery = continuous chain of anastomosis along the length of the colon (also know as the marginal artery of Drummond)
Is the marginal artery an at risk artery for ischaemic colitis?
Yes! It is a weak artery and sometimes deficient where the superior and inferior mesenteric arteriy distributions meet just proximal to the splenic flexure.
Describe the blood supply to the anal canal. Why is this clinicaly relevant?
Superior rectal artery: supplies the whole of the rectum + upper half of the anal canal
3 branches from the superior rectal artery descend and anastomose with branches from the inferior rectal artery.
Inferior rectal artery: supplies the lower half of the anal canal
Middle rectal artery: only supplies the muscles that coat the rectum
Clinical: where the 3 branches anatomose, tributary veins accompany the arteries and drain into the partal system. This explain why internal haemorrhoids occur at 3, 7 and 11 o'clock when the anal canal is viewed with the patient in the lithotomy position (speculum exam position)
Describe the lymphatic drainage of the large bowel.
The field of lymphatic drainage corresponds to its arterial blood supply. Tissues drain to local lymph nodes, who drain into nodes near the origins of the superior and inferior mesenteric arteries.
Describe the main differences between the upper anal canal and the lower anal canal regarding epithelium, blood supply, innervation and lymphatic drainage. Why is this clinically relevant?
Upper half of the anal canal:
- derived from endoderm
- lined with columnar epithelium
- hosts adenocarcinoma
- supplied by autonomic nervous system (not sensitive to pinprick)
- veins drain into the portal system (important site of portosystemic anastomosis in portal HTN)
- lymph drains to abdominal nodes
Lower half of the anal canal:
- derived from ectoderm
- lined with stratified squamous epithelium
- hosts squamous cell carcinoma
- supplied by somatic innervation via the inferior rectal nerve (sensitive to pinprick - important in haemorrhoid injection)
- veins drain in the systemic venous system
- lymph drains to the inguinal nodes (cancer may metastasize to inguinal lymph nodes)
Describe the anatomy of the anal sphincters. What are the differences between the internal and external anal sphincters?
Internal anal sphincter:
- smooth muscle continuous above with the circular muscle of the rectum
- supplied by sympathetic nerves
External anal sphincter:
- composed of striated muscle, which surrounds the internal anal sphincter
- divided in 3 parts:
2: superficial: attached to the coccyxbehind and the perineal body in front
3: deep: which is continuous with the puborectalis part of levator ani
- Nerve supply: inferior rectal branch and the pudendal nerve (S2,3) and the perineal branch of S4
What is called the anorectal ring?
The deep part of the external sphincter where it blends with levator ani together with the internal anal sphincter.
What 3 of the 9 abdominal regions does the liver lie in?
It is the largest organ in the body.
1: right hypochondrium
3: left hypo-chondrium
What is the falciform ligament?
The large ligament, a remnant of the umbilical vein that separates the left and right liver lobes.
It FUNCTIONALLY separates the caudate lobe from the left lobe of the liver.
Describe the superior, postero-inferior and posterior surface anatomical relations of the liver.
Superior surface relations:
dome-shaped; related to the diaphragm which separates it from the pleura, lungs, pericardium and heart.
Posterio-inferior surface relations:
- covered with peritoneum except where the gallbladder is attached and at the porta hepatis and the fissure for the ligamentum venosum.
- related to the abdominal oesophagus, stomach, duodenum, hepatic flexure of the colon, right kidney and right suprarenal gland.
connected to the diaphragm over the right lobe of the liver by the coronary ligament between the two layers of which is a non-peritonealised area, i.e. the bare area.
What are the four lobes of the liver?
right, left, caudate, quadrate
What is the porta hepatis? What are the structures in it? Why is this clinicaly relevant?
It is the gateway to and from the liver.
1. common hepatic duct anteriorly
2. hepatic artery in the middle
3. portal vein posteriorly
Contains lymph nodes which when enlarged by malignancy may compress the bile ducts and cause obstructive jaundice
Describe the difference between the falciform ligament, the ligamentum teres, the coronary ligament, the triangular ligaments and the ligamentum venosum.
Falciform ligament: fold of peritoneum that divides the liver in two unequal lobes
Ligamentum teres: ligament that runs in the Falciform ligament's free border
Coronary ligament: peritoneal fold that holds the liver to the inferior surface of the diaphragm.
- Left: connects the posterior part of the upper surface of the left lobe of the liver to the diaphragm
- Right: situated at the right extremity of the bare area, and is a small fold which passes to the diaphragm
Ligamentum venosum: fibrous remnant of the ductus venosus of the fetal circulation. Invested by the peritoneal folds of the lesser omentum within a fissure on the visceral/posterior surface of the liver between the caudate and main parts of the left lobe
Are the anatomical and functional divisions of the liver the same?
No. The functional division is through a plane which passes through the gall bladder fossa and fossa for the IVC.
Each of these two functional lobes has its own arterial and portal venous blood supply and its own biliary drainage. Each lobe being divided into four segments
Total = 8 segments
What are the 3 main hepatic veins? How do these divide the liver functionaly?
These divide the liver into four sectors, each of which receives a portal pedicle,with an alternation between hepatic veins and portal pedicles
A schematic representation of the functional anatomy of the liver. The three main hepatic veins divide the liver into four sectors, each of which receives a portal pedicle.
What segments would a right hemihepatectomy involve? What about a left hemihepatectomy?
Right hemihepatectomy: V, VI, VII and VIII.
Left hemihepatectomy: II,III and IV.
Describe the anatomy of the extrahepatic biliary system.
- Common hepatic duct is joined by cystic duct to form bile duct (common bile duct).
- Bile duct runs in a groove on the posterior aspect of the head of the pancreas before opening into the medial aspect of the second part of the duodenum.
- The main pancreatic duct joins the common bile duct to form a common dilated channel, i.e. the ampulla of Vater guarded by the sphincter of Oddi (periampullary sphincter).
- There may be an additional duct, which receives ducts from the lower part of the head of the pancreas, known as the accessory pancreatic duct.
Describe the anatomy of the gallbladder. What is it's purpose?
Acts as a reservoir for bile, which it alsoconcentrates. (holds about 50 mL of bile when physiologically distended)
The gall bladder consists of:
- neck: the neck opens into the cystic duct which conveys bile to and from the common bile duct.
The lumen of the cystic duct contains a spiral mucosal valve (of Heister).
What is the Hartmann's pouch? Why is this clinically relevant?
A small pouch may be present on the ventral aspect of the gallbladder just proximal to the neck.
This is an area where gallstones are likely to form.
What is the blood supply to the gallbladder?
Cystic artery + arteries in the bed of the liver
Cystic artery passes behind the common hepatic duct and cystic duct to gain the upper surface of the neck of the gall bladder.
Venous drainage: is via small veins draining directlyinto the bed of the liver.
What s the Calot's Triangle? Why is ths clinically relevant during surgery?
Triangle made up of the liver, the cystic duct and the common hepatic duct.
- cystc artery
- right hepatic artery
- lymph node of Lund (Mascagni's lymph node) = swells during cholecystitis or chlangitis
During cholecystectomy, dissection in the triangle of Calot is ill-advised until the lateral-most structures have been cleared and identification of the cystic duct is definitive
What is Pringle's manoeuvre?
Compressing the hepatic artery and portal vein in the free edge of the lesser omentum to control haemrrhage during cholecystectomy or from liver trauma.
What epithelium lines the inside of the gallbladder? is there any muscle in the gallbladder, cystic duct or bile duct? Why is this clinically relevant?
Gallbladder: smooth muscle is present
Cystic duct: smooth muscle is present
Common bile duct: smooth muscle absent
- This means that a stone, if blocked in the gallbladder or cystic duct, will cause pain due to smooth muscle spasm. However, a stone in the common bile duct will be painless!
- If the gallbladder is obstructed, bile is absorbed and the goblet cells produce mucus = mucocele of gallbladder
(On US scan: Minimal wall thickening and dilated gallbladder suggest mucocele)
What organs does the portal venous system drain blood from? What vessels make the portal vein?
- abdominal part of GI tract (except the lower part of the anus)
- gall bladder
Portal vein = splenic vein + superior mesenteric vein
What structure does the portal vein traverse to enter the liver? Are there any valves in the portal system?
The epiploic foramen or Foramen of Winslow.
No valves - this is to limit the impact of any obstruction of the system (ie. cirrhosis)
What are the 5 areas of anastomosis where the portal system drains into the systemic venous system? Why is this clinically relevant?
1. oesophageal branch of the left gastric vein (portal) and the oesophageal tributaries of the azygos vein (systemic) = oesophageal varices
2. superior rectal branch of the inferior mesenteric vein (portal) and the inferior rectal veins (systemic) = haemorrhoids
3. portal tributaries in the mesentery (portal) and retroperitoneal veins (systemic) = retroperitoneal varices
4. portal veins in the liver (portal) and veins in the abdominal wall (systemic) = caput medusae
5. portal branches in the liver (portal) and veins of the diaphragm (systemic)
These are all are of anastomosis that may bleed if there is portal hypertension.
What are the parts of the pancreas? Is it retroperitoneal?
Yes it is retroperitoneal.
- uncinate process
What are the anatomical relations of the pancreas?
- The head of the pancreas lies in the C-shape of the duodenum
Anterior: transverse mesocolon
Posterior: aorta, left crus of the diaphragm, suprarenal gland, and left kidney/ splenic vein
Superior: splenic artery
Inferior: small intestine
What are the names of the pancreatic ducts?
Main pancreatic duct = Duct of Wirsung
Accessory pancreatic duct = Duct of Santorini (2cm proximal to the ampula of Vater)
Describe the blood supply to the pancreas. What about the lymphatic drainage?
1. the splenic artery via the great pancreatic artery
2. superior pancreaticoduodenal artery (branch from the gastroduodenal artery) + inferior pancreaticoduodenal artery (branch of the superior mesenteric artery) = supply the uncinate process
Tissues drain in nodes along the upper border of the pancreas, the duodenum and the root of the mesentery.
What cells make the pancreatic lobules? What other important cells are scattered around the pancreas and have endocrine function?
Pancreatic lobules (exocrine) = acini of serous cells, secrete pancreatic enzymes
Islets of Langerhans = shperoidal clusters of pale-staining cells that secrete insulin and glucagon (endocrine)
What ligaments connect to the spleen?
1. Gastrosplenic ligament: connects the spleen to the greater curvature of the stomach (carries the short gastric and left gastroepiploic vessels)
2. Lienorenal ligament: connects the spleen to the abdominal wall (caries the tail of the pancreas and the splenic vessels)
What are the anatomical relations of the spleen? Why is this clinically relevant?
Posterior: left part of diaphragm, left lung, 9th, 10th , 11th ribs
Inferior: splenic flexure
Medially: left kidney
If a patient fractures their left lower ribs, check for damage or rupture of the spleen.
What is the blood supply to the spleen?
Arterial: splenic artery (branch from coeliac axis)
Venous: splenic vein (joined by the superior mesenteric vein to make the portal vein)
Note: the splenic artery, vein and lymph nodes are enclosed in the lienorenal ligament.
Are kidneys retroperitoneal? Which kidney lies a bit lower than the other?
The right kidney lies a bit lower than the left owing to the downward placement of the liver.
What are the anatomical relations of the kidneys? What are the 3 capsules of the kidneys? What is the blood supply? Lymph?
Medial to both kidneys: hilum, renal vain, renal artery and pelvis of the ureter, aorta and IVC
Lateral: transversalis fascia
Above: renal fascia blends with the fascia of the diaphragm
Capsules: (superficial to deep)
1. fascial (renal fascia)
2. perinephric fat
3. true fibrous capsule
Arterial: renal artery
Venous: renal vein. The left renal vein is longer and receives 2 tributaries (gonadal and adrenal)
Lymph drain into the para-aortic lymph nodes.
What happens when there is a traumatic injury to the kidney causing it to rupture?
Rupture or pus in the perinephric abscess will distend the renal fascia and then take the line of least resistance, tracking down within the fascia compartment to the pelvis.
What structures do you encounter when reaching the kidney surgically from the loin approach?
Make an oblique incision halfway between the 12th rib and iliac crest (extending forward from the lateral border of erector spinae to the lateral border of rectus abdominus)
1. latissiumus dorsi and serratus posterior are divided
2. external oblique is split along the lines of it fibres
3. internal oblique and transversus abdominis are divided
5. renal fascia capsule
6. subcostal nerve and vessels
Describe the inner anatomy of the kidney and it's connection to the ureter.
The upper end of the ureter is expanded at the pelvis, which is divided into 2 parts called major calyces. These are the subdivided into about 12 minor calyces.
The apices of the renal pyramids form papillae that project into the calyces.
What are the anatomical relations of the ureter in the abdomen vs in the pelvis?
Anterior: peritoneum, colic vessels, gonadal vessels, ileum, mesentery, sigmoid colon, sigmoid mesocolon
Posterior: psoas major, psoas minor tendon, genitofemoral nerve, bifurcation of the common iliac artery
Male: enter by crossing the bifurcation of the common iliac artery, runs down to the ischial spine, crosses the obturator nerve and the anterior branches of the internal iliac artery, turns medially to reach the bladder and passes bellow the vas deferens before entering the bladder.
Women: course similar, but it crosses close to the lateral fornix of the vagina below the uterine artery and posterior part of the bladder
What are the 3 narrowest parts of the ureter?
1. pelviureteric junction (PUJ)
2. at the brim of the pelvis
3. vesicoureteric junction (VUJ)
What is the blood supply to the ureters?
- renal arteries
- gonadal arteries
- internal iliac artery
- inferior vesical arteries
How can you recognise a ureter intra-operatively?
- its strips up with the peritoneum
- if you stimulate the ureter with the tip of a forceps, you can see worm-like movements occur in its wall
Describe the anatomy of the right vs. left suprarenal (or adrenal) glands as well as their anatomical relations.
- cresenteric shape, embraces the medial border of the left kidney above the hilum
- Anterior: stomach, across the lesser sac
- Posterior: diaphragm
- Inferior: upper pole of the kidney
- pyramidal shape, embraces the upper pole of the right kidney
- Anterior: liver, IVC
- Posterior: diaphragm
- Inferior: upper pole of the kidney
Describe the blood supply to the suprarenal glands.
1. branch from the aorta
2. branch form the inferior phrenic artery
3. branch from the renal artery
Right: straight into the IVC
Left: longer vein into the left renal vein
Describe the structure of an adrenal gland and the hormones it produces.
- derived from the neural crest (ectoderm)
- receives sympathetic fibres from the greater splanchnic nerve
- secretes adrenaline and noradrenaline
1. Zona glomerulosa = mineralocoritcoids
2. Zona fasciculata = glucocorticoids
3. Zona reticularis = sex hormones
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