Abdominal, Renal and Reproductive Anatomy

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  • Created by: R_Hall
  • Created on: 26-05-15 15:31

AAW

  • External oblique- origin = lower 8 ribs -> iliac crest. Fibres run downwards and medially to form the inguinal ligament inferiorly. Form aponeuroses medially. Innervated by T7-11 and T12. 
  • Linea alba is formed from the aponeuroses of EO and IO
  • The inferior border of the EO has a free edge, and forms the inguinal ligament- ASIS => pubic tubercle
  • Internal oblique- originates from costal margin, thoracolumbar fascia, iliac crest, and the lateral 2/3 of the inguinal ligament. Fibres run downwards and backwards. Innervated by T6-11, T12 and L1. 
  • Transversus abdominis- originates from costal margin, thoracolumbar fascia, iliac crest, and the lateral 1/3 of the inguinal ligament. Fibres run transversely. Innervated by T6-11, T12 and L1. 
  • The 3 layers of apopneuroses form the rectus sheath. Rectus abdominis runs through the sheath from xiphi-sternum to pubic tubercle. Used in labour, bowel movements, heavy breathing and coughing. Inferior epigastrics run deep to it
  • There are 3 tendinous insertions where the muscle and aponeuroses blend
  • Linea semilunaris is a curved tendinous line on either side of the rectus abdominis, and the arcuate line marks the lower limit of the rectus sheath
  • Fascia
  • - superficial (Camper's)- thick layer on AAW, superficial to scarpa's
  • - deep (Scarpa's)- membranous layer on AAW
  • - Colles- continuous in the perineum with Scarpa's fascia, attachments form the deep perineal pouch
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Inguinal Canal

  • The pubic tubercle is just lateral to the pubic symphysis
  • Superficial inguinal ring- lateral to the tubercle, has an opening to allow the spermatic cord or round ligament of the uterus into the inguinal canal. 1/2 way along inguinal ligament
  • Boundaries- med= pubic symphysis, lat= pubic tubercle, post= conjoint tendon, ant= EO apo
  • The spermatic cord contains the vas deferens, testicular a and n. cremasteric a, deferential a, genital branch of genitofemoral, ilio-inguinal n, pampiniform plexus, lymphatics and the tunica vaginalis
  • Ilio-inguinal nerve joins the cord at the superficial inguinal ring
  • Boundaries of the inguinal canal- Floor= inguinal ligament, ant wall= EO apo (TA and IO), post wall= transversalis fascia roof= arching fibres of TA, IO and EO
  • IO originates from lateral 2/3rds of inguinal ligament, and TA from lateral 1/3rd
  • The deep ring is where the spermatic cord penetrates the transversalis fascia
  • The conjoint tendon is formed from IO and TA aponeuroses, behind the superficial inguinal ring. It reinforces the posterior wall of the inguinal canal
  • Tranversalis fascia runs deep to TA, and lines the abdominal (and pelvic) cavity
  • Indirect hernia- congenital, failure of inguinal ring to close, so gut protrudes through ring. 
  • Direct hernia- acquired, weak point in fascia of abdominal wall. More likely to be reducible
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The Peritoneum 1

  • NS of peritoneum- T7-12 and L1 (abdomen), and obturator (pelvis)
  • Greater omentum- double layer of peritoneum filled with fat. Remnant of the dorsal mesentery. Originates from the lesser curvature of the stomach. The transverse colon (with transverse mesocolon) attaches to the underside of GO
  • The mesocolic shelf is formed by the GO and transverse colon. Separates the abdomen into supra- and infracolic compartments
  • Supracolic compartment
  • Liver and gallbladder- the falciform ligament (ventral mesentery) is on the anterior surface with the ligamentum Teres (umbilical vein) in the free-edge. Separates the supracolic compartment into L and R
  • The subphrenic recess is on the superior surface, with the anterior coronary ligament from liver => diaphragm. The posterior coronary ligament is under the liver
  • The bare area is against the diaphragm, and has no peritoneal covering
  • The hepato-renal recess is the lowest and deepest space when in the supine position, so free fluids can collect. Continuous with R paracolic gutter
  • The gastro-splenic ligament connects the stomach and the spleen, and the lienorenal ligament connects the spleen and the kidney
  • Lesser sac- posterior to the stomach and the lesser omentum (to lesser curvature of stomach-ventral mesentery)-which has a free border containing the portal triad
  • The epiploic foramen is under the lesser omentum, and is a connection between the lesser and greater sacs. Boundaries- post= IVC, ant= portal triad, sup= liver, and inf= 1st part of duodenum
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The Peritoneum 2

  • Infracolic
  • L side of infracolic compartment communicates with the pelvis
  • Jejunum and Ileum- from upper L quadrant -> lower R quadrant. The origin of the root of the mesentery, which allows mobility and the intestine to increase in length in comparison to the body
  • Caecum- dilated sac where the appendix attaches. Forms an ileo-caecal junction with the ileum
  • Colon= ascending -> hepatic flexure -> transverse colon -> splenic flexure -> descending colon -> sigmoid colon -> rectum
  • The splenic flexure attaches to the diaphragm via the phrenico-colic ligament. This prevents the spleen enlarging downwards- enlarges anteriorly and diagonally instead.
  • The ascending and descending colon are secondarily retroperitoneal
  • Paracolic gutters- on either side of the colon (2 on each side- laterally and medially). The R lateral is continuous with the hepatorenal recess- so forms a pathway for free fluid from infracolic -> supracolic
  • Layers of mesentery- GO below transverse colon- 4 layers; between stomach and colon- 6 layers
  • Parasympathetic motor supply
  • - FG/MG- vagus (CN X)
  • - HG- pelvic splanchnic
  • - Bladder- S2-4
  • - Abdominal/pelvic viscera- sympathetic chain -> greater, lesser and least lumbar splanchnic
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The Stomach and Midgut

  • Gastrocolic ligament- part of the greater omentum, runs from greater curvature of stomach -> transverse colon
  • The posterior border of the lesser sac are formed by the pancreas, splenic artery and the L adrenal gland and kidney
  • Stomach- oesophagus -> cardia -> fundus -> body -> pyloric antrum -> pyloric sphincter
  • 3 unpaired arteries from the aorta supply the FG, MG and HG; the main one to the stomach is the coeliac trunk (T12)
  • There are fibrous coeliac plexuses on either side of the CT- form hub of autonomic ns to abdominal viscera
  • CT
  • -> L gastric
  • -> hepatic -> R gastric and R gastroduodenal -> R gastroepiploic
  • -> splenic -> L gastroepiploic
  • The lesser curvature is supplied by the R and L gastrics, and the greater curvature is supplied by the R gastro-epiploic and L gastro-epiploic
  • The external appearance of the colon- appendices epiploicae (fatty tags), taenia coli (3 x bands of longitudinal muscle) and haustra (pouches created by taenia coli)
  • Superior mesenteric artery (L1)
  • -> jejunal and ileal branches = form arcades and vasa recta
  • -> ileo-colic (to ileum and colon) -> appendicular 
  • -> R colic (to asc colon and hepatic flexure)
  • -> middle colic (branches to transverse colon, and forms marginal with R colic)
  • Appendicitis- pain in umbilical region- maximum tenderness at McBurney's point (lat 2/3 umbilicus -> ASIS)
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Hingut and Associated Arteries. Liver, Gallbladder

  • Inferior Mesenteric Artery (L3)
  • ->L colic (to splenic flexure, contributes to marginal)
  • -> sigmoidal (anastomoses with marginal)
  • -> superior rectal
  • The IMV receives branches from the rectum, sigmoid colon and splenic flexure. It drains into the splenic vein (under pancreas), which joins with the SMV to form the hepatic portal vein
  • Sigmoid colon is suspended by the sigmoid mesocolon, and the rectum is 1 retroperitoneal
  • Rectal arteries- superior (IMA), middle (int.iliac) and inferior (int.pudendal)
  • Liver
  • The portal triad= bile duct (from union of cystic and hepatic), hepatic artery and portal vein (always posterior)
  • The visceral surface includes the gallbladder, IVC, caudate lobe, quadrate lobe and the porta hepatis
  • The anterior and posterior pairs of coronary ligaments form the triangular ligaments, which stabilise the liver and suspend it from the diaphragm
  • The liver is divided into 8 functional segments- each one with its own branch of the portal triad
  • The cystic duct from the gallbladder and the hepatic duct (L and R) from the liver unite to form the bile duct, which empties into the pancreas and duodenum
  • Gallbladder supplied by the cystic artery (from R hepatic)
  • Veins of MG -> SMV + splenic vein (with IMV) -> portal vein
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Duodenum, Pancreas and Spleen

  • Transverse mesocolon leaves the PAW at the level of the pancreas
  • Pancreas = body -> neck -> head -> uncinate process
  • Splenic artery runs superiorly to pancreas, and splenic vein inferiorly
  • The tail of the pancreas is embedded in the hilum of the spleen, the neck is anterior to the HPV and SMA, and the uncinate is underneath the SMA + V
  • Spleen- smooth supro-lateral surface, anterior border with indentations, long axis in line with rib X. 3 regions- gastric, renal and colic
  • Suspended by gastro-splenic and lienorenal ligaments, which are remnants of the dorsal mesentery
  • Parts of duodenum= superior -> descending -> horizontal -> ascending
  • BS from gastroduodenal artery (common hepatic) and pancreaticoduodenal (common hepatic)
  • The bile duct originates from the gallbladder, and unites with the main pancreatic duct to form the hepato-pancreatic ampulla
  • The HPA is surrounded by the sphincter of Oddi, which control its drainage into the duodenum via the mjr duodenal papilla. 
  • Papilla marks boundary between FG and MG
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Kidneys

  • Aortic hiatus through diaphragm = T12, and bifurcates into common iliacs at L4. IVC through diaphragm at T8
  • Kidney- from T12 - L3. Has a smooth, curved lateral surface, sup and inf poles and an indented medial surface (hilum)
  • The renal veins branch off the IVC, and the L travels over the aorta. The L renal v receives branches off the L gonadal vein, whereas the R gonadal vein drains directly into the IVC
  • The renal artery comes off the aorta at L1/2, and travels posterior to the renal vein (anterior to the ureter)
  • In a longitudinal section through the kidney, there is a pale outer cortex and a darker inner medulla. Bands of cortex called renal columns pass into the medulla, and are separated by renal pyramids. Minor calyces are found at the apices
  • 2/3 minor calyces -> major calyces -> renal pelvis -> ureter
  • BS to ureters- upper= renal, mid= aorta, gonadals and common iliacs, pelvic= internal iliac branches
  • 3 narrowest points of ureter- uretopelvis junction, pelvic brim and entry point into bladder
  • Adrenal/ suprarenal glands- produces corticosteroids and adrenaline. They are highly vascularised- with an adrenal vein (into renal) and a series of adrenal arteries off the aorta (sup, mid and inf)
  • Perinephric fat- directly around kidney. Paranephric fat- separated from peri by a layer of fascia
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PAW

  • The kidney sits on muscles in the PAW:
  • Psoas major- on the lateral surface of the lumbar vertebra
  • Illiacus- lateral to psoas mjr, in the iliac fossa
  • Quadratus lumborum- lateral to psoas mjr, T12 -> iliac crest
  • Illiacus + psoas mjr => iliopsoas muscle- forms a joint tendon to femur
  • The kidney sits on 3 nerves- subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1)- which provide somatic innervation to body wall
  • The ureter passes along psoas major, and crosses the common iliac bifurcation (L4)
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Bladder and Pelvic Organs- Female

  • Bladder- post to pubic symphysis. Apex -> fundus -> base. Bs= sup and inf vesicles
  • Ns- sympathetic= hypogastric plexus/nerve, parasympathetic- pelvic splanchnic and inf hypogastric
  • There are rugae on the internal surface to allow expansion, apart from a triangular smooth area called the trigone. This area is formed by the two ureters and the urethral orifice, and allows urine to escape (as no contracting muscle fibres)
  • In the female, the peritoneum drapes over the superior surfaces of pelvic organs:
  • -rectouterine pouch/ pouch of Douglas= lowest point in pelvic cavity
  • - vesicouterine pouch. Both collect free fluid and pus
  • The vagina is posterior to the bladder
  • Uterus = cervix -> body -> fundus.
  • The cervix has an external os opening into the vagina, and 3 fornixes (lat, ant and post) surrounding the surface. The posterior fornix lies next to the rectouterine pouch
  • 2 uterine tubes run into the uterus. The broad ligament runs laterally from the uterus, with uterine tubes in the superior margin
  • The uterine tube curves back on itself to give fimbriae. Fimbriae -> infundibulum -> ampulla -> isthmus
  • 3 ligaments within the broad ligament- which forms a sheet connecting uterus to pelvic floor and walls
  • - ovarian- between uterus and ovary
  • - round ligament of uterus- lateral surface of bladder -> AAW
  • - suspensory- ovary -> lateral pelvic wall. Contains ovarian artery and vein
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Bladder and Pelvic Organs- Male

  • The urethra opens through the prostate gland
  • Posterior to the prostate is the vas deferens or ductus deferens. It carries sperm from the testes (tail of epididymis) to the base of the penis, and enters the prostatic urethra, where it is joined by the seminal vesicle
  • Vas deferens enters the pelvis through the deep inguinal ring
  • Vas deferens + seminal vesicle -> ejaculatory duct
  • Rectum- S3 -> ano-rectal junction on pelvic floor
  • The perineum drapes over the rectum and bladder to form a rectovesicle pouch
  • The rectum has rectal folds/ valves (2L, 1R), an anorectal junction and an anus
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Internal Iliac and Pelvic Floor

  • Aorta -> common iliac (L IV) -> external and internal iliacs
  • External iliac- pelvic brim -> AAW
  • -> inferior epigastric, which travels up AAW in the lateral umbilical fold (layer of peritoneum)
  • Internal iliac- variable branches
  • -> umbilical artery: travels up AAW in medial umbilical ligament. Gives rise to superior vesicle artery and becomes obliterated as median umbilical ligament
  • -> obturator artery (with v and n through obturator canal -> leg)
  • -> inferior vesicle / vaginal artery
  • -> superior gluteal (above piriformis) artery
  • -> inferior gluteal artery
  • -> internal pudendal artery (through greater sciatic foramen) -> inferior rectal
  • Piriformis- moves out of pelvis and into gluteal region via the greater sciatic foramen. Associated with inf and sup gluteal arteries.
  • The sacral roots S1-5 run on top of it and form the sciatic nerve. S2-4 also form the pudendal nerve
  • Muscles of pelvic floor
  • - piriformis 
  • - coccygeus (base= coccyx/sacrum, apex= ischial spine)
  • - levator ani (attached to pubic bone, tendinous arch and ischial spine)- incl puborectalis
  • - obturator internus (lines obturator foramen)
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Perineum and External Genitalia- Female

  • Ischioanal fossa- fat filled spaces on either side of the anus. Med= levator ani and EAS, lat= obturator internus, floor= fat and perianal skin
  • IAS supplied by pelvic splanchnic (S4), and IAS supplied by S4 and pudendal
  • The perineum is split into urogenital and anal triangles, by a horizontal line drawn between the ischial tuberosities
  • Sacro-tuberous ligament- sacrum -> ischial tuberosity. Forms the lesser sciatic foramen (where pudendals pass through) The sacro-spinous ligament is deep to it
  • Internal pudendal artery. Out of pelvis via greater sciatic foramen -> round ischial spine and sacrospinous ligament -> pass into pelvis via lesser sciatic foramen -> run in ischioanal fossa
  • Urogenital triangle- has a perineal membrane which separates deep and superficial perineal pouches
  • Female
  • Bulb of vestibule (like bulb of penis)- separated into L and R, with vaginal opening in the middle. Covered by a thin film of bulbus spongiosus muscle
  • Corpus cavernosus- erectile tissue found laterally to bulb of vestibule. Converges in the midline -> ********. Covered by a thin film of ischio cavernosus muscle
  • Lymph drains to internal iliac and inguinal nodes
  • EUS supplied by perineal branches of pudendal nerve (S2-4)
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Perineum and External Genitalia- Male

  • Male
  • The corpus spongiosum (bulb of penis) is found on the ventral penile surface, and is covered by the bulbo spongiosus muscle- supplied by pudendal nerve, and used for emission of semen/removal of residual urine
  • Corpora cavernosa is found laterally on the dorsal penile surface. Attaches to the ischiopubic ramus and hangs off the perineal membrane. Covered by ischiocavernosus muscle- supplied by pudendal nerve, and used to erect penis
  • Urethra- pre-prostatic -> prostatic -> membranous -> spongy/penile
  • Corpus spongiosum dilates into the glans of the penis
  • The tunica vaginalis forms a protective coat on the testes- with an epididymis -> vas deferens
  • Superficial perineal pouch contains the testis, vas and root of penis. Between perineal membrane and Colles' fascia
  • Bs of penis- artery of bulb of penis (int pudendal), urethral artery (int pudendal), and deep/dorsal artery of penis (int pudendal)
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Living Anatomy of the Abdomen

  • Superior margin of abdo wall- from xiphoid process, along costal margin to rib 12
  • Inferior margin- from pubic tubercle/crest, along inguinal ligament to ASIS
  • Linea alba and linea semilunaris mark boundaries of rectus abdominis. Linea alba is a common surgical approach- as doesn't contain any primary nerves of bv
  • Abdomen can be divided into 9 regions- vertical lines= L and R mid-clavicular, horizontal lines= subcostal (L3) and transtubecular (L 4/5)
  • Transpyloric plane- through L1, and kidneys, pancreas and duodenum
  • Guarding= tensing of abdominal wall to protect inflamed organs from palpitation
  • Kidneys are palplated using a bimanual technique- balloting aka rolling the inferior pole of the kidney
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