Raftery Abdo and Perineum Flashcards
How many folds of peritoneum are there below the umbilicus and what are they?
Three
Median umbilical fold - obliterated urachus
Medial umbilical fold - obliterated umbilical artery
Lateral umbilical fold - inferior epigastric artery
What are the relations of the omental bursa (lesser sac)?
Front - lesser omentum, stomach
Above - superior recess whose anterior border is the caudate lobe of liver
Below - projects downwards to transverse mesocolon
Left - spleen, gastrosplenic and lienorenal ligaments
Right - opens into greater sac via epiploic foramen
What are the relations of the epiploic foramen (Foramen of Winslow)?
Front - free edge of lesser omentum
Back - IVC
Above - caudate process of liver
Below - 1st part of duodenum
What are the contents of the epiploic foramen?
Right - bile duct
Left - hepatic artery
Behind - portal vein
What separates the right and left subphrenic spaces?
Falciform ligament
What are the boundaries of the right subhepatic space (renal well of Rutherford Morrison)?
Above - liver with attached gallbladder
Below - duodenum
Behind - posterior abdominal wall, kidney
What is the left subhepatic space?
Lesser sac
What are the bones in the posterior abdominal wall?
Bodies of lumbar vertebrae
Sacrum
Wings of ilium
What are the muscles in the posterior abdominal wall?
Posterior part of diaphragm
Psoas major
Quadratus lumborum
Iliacus
What are important structures on the posterior abdominal wall?
Abdominal aorta IVC Kidneys Adrenal glands Lumbar sympathetic chain
What is the origin of psoas major?
Transverse processes of L1-5 and sides of bodies and intervening discs from T12-L5 vertebrae
Where does the psoas major insert?
Tip of lesser trochanter of femur
What is the nerve supply of psoas major?
L2-3
What are the actions of psoas major?
Flexion and medial rotation of extended thigh
What important structures lies on psoas major?
IVC
Ureters
Gonadal vessels
What lies in front of psoas major?
Retrocaecal or retrocolic appendix
Psoas/Cope’s sign = RLQ pain with flexion of right hip against resistance in appendicitis
What is the origin of quadratus lumborum?
Iliolumbar ligament and adjacent portion of iliac crest
Where does quadratus lumborum insert?
Medial half of lower border of 12th rib and by 4 small tendons into the transverse process of L1-4
What are some anterior relations of quadratus lumborum?
Colon
Kidney
Subcostal, ilioinguinal and iliohypogastric nerves
What is the origin of iliacus?
Greater part of iliac fossa extending into sacrum
What is the insertion of iliacus?
Lateral aspect of tendon of psoas major onto lesser trochanter of femur
What is the nerve supply of iliacus?
Branch of femoral nerve (L2-3)
What are the anterior relations of abdominal aorta (from up to down)?
Lesser omentum Stomach Coeliac plexus Pancreas Splenic vein Left renal vein 3rd part of duodenum Root of mesentery Coils of small intestine Aortic plexus Peritoneum
What are posterior relations of abdominal aorta?
Bodies of L1-4 vertebrae
Left lumbar veins
Cisterna chyli
What structures are found on the right side of the abdominal aorta?
IVC
Thoracic duct
Azygous vein
Right sympathetic trunk
What structures are found on the left side of the abdominal aorta?
Left sympathetic trunk
What are the branches of the abdominal aorta and their levels?
Anterior unpaired supplying abdominal viscera:
- Coeliac axis - T12
- SMA - L1
- IMA - L3
Lateral paired:
- Suprarenal - L1
- Renal - L1-2
- Gonadal (testicular/ovarian) - L2
Paired to parietes:
- Inferior phrenic - T12
- 4 lumbar arteries - L1-4
Terminal branches
- Common iliac - L4
- Median sacral - L4 (slightly above aortic bifurcation)
What are the branches of the coeliac axis?
Left gastric artery
Common hepatic artery
Splenic artery
What are the branches of the superior mesenteric artery?
Ileocolic
Middle colic
Right colic
What are the branches of the inferior mesenteric artery?
Left colic
Superior rectal
What are the anterior relations of common iliac artery?
Peritoneum
Small intestine
Ureters
Sympathetic nerves
Which artery runs along the brim of the pelvis on the medial side of psoas major?
External iliac artery
Inferior epigastric artery is a branch of?
External iliac artery
branch given off immediately before passing below inguinal ligament
Which structure passes backwards and downwards into the pelvis between the ureter (anteriorly) and internal iliac vein (posteriorly)?
Internal iliac artery
Where does the internal iliac artery divide into its anterior and posterior branches?
At the upper border of the greater sciatic notch
What do the branches of the internal iliac artery supply?
Pelvic organs
Perineum
Buttock
Anal canal
At which level does the common iliac veins join to form the inferior vena cava?
L5
At which level does the IVC pass through the diaphragm?
T8
What are the anterior relations of IVC?
Mesentery 3rd part of duodenum Pancreas 1st part of duodenum Portal vein Posterior surface of liver Diaphragm Arteries (from top to bottom): hepatic, right testicular, right colic, right common iliac
What are the posterior relations of IVC?
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 To the left: aorta
What are the tributaries of IVC?
Lumbar branches Right gonadal vein Right and left renal veins Right suprarenal vein Phrenic vein Hepatic vein
Where does the lumbar sympathetic chain start?
Deep to the medial arcuate ligament of the diaphragm as a continuation of the thoracic sympathetic chain
What are the positions of the lumbar vessels relative to the lumbar sympathetic chain?
Lumbar arteries - lie deep to chain
Lumbar veins - may cross superficial to it
What are the branches of the lumbar sympathetic chain?
Plexuses around abdominal aorta Hypogastric plexus (presacral nerves) to supply the pelvic viscera distributed along internal iliac artery and its branches
What causes failure of ejaculation after resection of AAA or extensive pelvic dissection?
Removal of aortic and hypogastric plexuses
What may lumbar sympathectomy be carried out for?
Plantar hyperhidrosis or vasospastic conditions
Usually the 2nd-4th ganglia are excised with the intermediate chain
Muscles of the pelvic floor
Levator ani
Coccygeus
Muscles of the pelvic wall
Piriformis (on front of sacrum) Obturator internus (on lateral wall of true pelvis)
Both act on femur, described with LL muscles
Origins of levator ani
Back of body of pubis
Ischial spine
Between these from the fascia covering obturator internus along a thickening between the above 2 points
Insertion of levator ani
Perineal body - forms a sling around prostate (levator prostatae) or vagina (sphincter vaginae)
Puborectalis (deep part of anal sphincter at anorectal ring) - sling around rectum and anus
Sides of coccyx and a median fibrous raphe stretching between the apex of the coccyx and anorectal junction
Nerve supply of levator ani
Pelvic surface - perineal branch of S4
Perineal surface - branch of inferior rectal and perineal division of pudendal nerve (S2-3)
Actions of levator ani
Principal support of pelvic floor
Support pelvic viscera
Resist downward pressure of abdominal muscles
Sphincter action on rectum and vagina
Increase intra-abdominal pressure during defecation, micturition, parturition
What is the coccygeus?
A small triangular muscle behind and in the same plane as levator ani
Origin of coccygeus
Ischial spine
Insertion of coccygeus
Side of coccyx and lowest part of sacrum
Same attachments as sacrospinous ligament
Nerve supply of coccygeus
Perineal branch of S4
Action of coccygeus
Hold coccyx in natural forwards position
Pelvic fascia
Parietal pelvic fascia - strong membrane covering muscles of pelvic wall and attached to bones at margins of muscles, over fixed or non-distensible structures (e.g. prostate)
Visceral pelvic fascia - loose and cellular over moveable structures (e.g. levator ani, bladder, rectum)
Triangles of the perineum
Urogenital triangle (anterior perineum) Anal triangle (posterior perineum)
What is the urogenital triangle?
Triangle formed by the ischiopubic inferior rami and line joining the ischial tuberosities passing just in front of anus
What is the perineal membrane?
Inferior fascia of the urogenital diaphragm - a strong fascial sheath attached to the sides of the urogenital triangle
Contents of deep perineal pouch
External urethral sphincter (striated muscle fibres surrounding membranous urethra) Bulbourethral glands (of Cowper) - ducts pierce perineal membrane to open into bulbous ducts
Relations of the external urethral sphincter
Below - perineal membrane
Above - indefinite layer of fascia i.e. superior fascia of urogenital diaphragm
Contents of superficial perineal pouch
Male:
- Bulb of penis attached to undersurface of perineal membrane (bulbospongiosus covers corpus spongiosum)
- Crura of penis attached at angle between insertion of perineal membrane and ischiopubic rami (each crus surrounded by ischiocarnous muscle)
- Superficial transverse perineal muscle running transversely from perineal body to ischial ramus
What is the perineal body?
Fibromuscular nodule lying in the midline between anterior and posterior perineum
Attachments of perineal body
Anal sphincter
Levator ani
Bulbospongiosus
Transverse perineal muscle
What is the anal triangle?
Triangular area lying between ischial tuberosities on each side and coccyx
Contents of anal triangle
Anus and its sphincters
Levator ani
Ischiorectal fossa
What is the ischiorectal fossa?
Space between the anal canal and side wall of pelvis
Boundaries of ischiorectal fossa
Medial - fascia over levator ani, external anal sphincter
Lateral - fascia over obturator internus
Front - extends forwards as prolongation deep to urogenital diaphragm
Back - limited by sacrotuberous ligaments and origin of gluteus maximus from this ligament
What lies in the pudendal canal (of Alcock)?
Internal pudendal vessels and nerve
What is the pudendal canal (of Alcock)?
Tunnel of fascia continuous with fascia overlying the obturator internus
Parts of penis
Root
Body
Glans
Attachments of root of penis
Perineal membrane
Pubic rami by crura
Symphysis pubis by suspensory ligament
What does the body of the penis comprise?
Corpus cavernosum
Corpus spongiosum
How is corpus cavernosum attached to the pubic symphysis?
By a suspensory ligament
Parts of male urethra (20cm long)
Prostatic
Membranous
Spongy
Layers/coverings of the testis
Scrotal skin
Dartos fascia and muscle
External spermatic, cremaster muscle in cremasteric fascia, internal spermatic fascia
Parietal and visceral layers of tunica vaginalis
Tunica albuginea
Blood supply of testicles
Testicular artery arising from aorta at level of renal vessels
Origin of blood supply of vas deferens and epididymis
Artery to the vas from inferior vesical branch of internal iliac artery
Venous drainage of testis
Pampiniform plexus of veins which become the testicular vein at deep inguinal ring
Drainage of testicular veins
Right testicular vein into IVC, left into left renal vein
Lymphatic drainage of testis
Accompany testicular veins into para-aortic nodes
At which level does the testis arise from on the posterior abdominal wall?
L2/3
How may a rapidly developing varicocoele be a presenting sign of tumour of left kidney?
Tumour of left kidney may invade the left renal vein, blocking the drainage of left testicular vein into the renal vein
Where does the vas deferens join the seminal vesicle ducts to form the common ejaculatory duct?
At the most superior and posterior aspect of the prostate gland
What does the common ejaculatory duct become?
Traverses the prostate to open into the prostatic urethra at the verumontanum on either side of the utricle
Start and end points of oesophagus
From lower border of cricoid cartilage (C6) to cardiac orifice of stomach (T11)
Parts of oesophagus
Cervical
Thoracic
Abdominal
Relations of cervical oesophagus
Anterior - trachea, thyroid
Posterior - lower cervical vertebrae, prevertebral fascia
Left - left common carotid artery, inferior thyroid, subclavian artery, thoracic duct
Right - right common carotid artery, recurrent laryngeal nerves that lie on either side in the groove between trachea and oesophagus
Where are the vagus nerves in relation to the thoracic oesophagus?
2 vagus nerves form a plexus on the surface of the oesophagus in the posterior mediastinum
Left vagus - anterior
Right vagus - posterior
Relations of the thoracic oesophagus
Anterior - left common carotid artery, trachea, left main bronchus, pericardium (separating it from left atrium and diaphragm)
Posterior - thoracic vertebrae, thoracic duct, hemiazygous vein, descending aorta below
Left - left subclavian artery, aortic arch, left vagus nerve and recurrent laryngeal, thoracic duct, left pleura
Right - right pleura, azygous vein
Where does the abdominal oesophagus lie?
In the groove on the posterior surface of the left lobe of liver with left crus of diaphragm behind
Blood supply of oesophagus
Cervical - inferior thyroid arteries
Thoracic - branches of aorta
Abdominal - left gastric and inferior phrenic arteries
Venous drainage of oesophagus
Cervical - inferior thyroid veins
Thoracic - azygous veins
Abdominal - azygous veins (systemic), partly to left gastric veins (portal)
Nerve supply of oesophagus
Upper 1/3 - parasympathetics via recurrent laryngeal nerve, sympathetics from middle cervical ganglion via inferior thyroid artery
Lower 2/3 (below root of lung) - vagus and sympathetics nerves contribute to oesophageal plexus
Layers of oesophagus
Mucous membrane lined by non-keratinised stratified squamous epithelium
Submucosa
Muscular layers - inner circular and outer longitudinal muscles
Muscularis externa upper 1/3 - striated muscle
Lower 2/3 - smooth muscle causing peristalsis
Adventitia
Outer layer of loose connective tissue
Lymphatic drainage of oesophagus
Cervical - deep cervical nodes
Thoracic - mediastinal nodes
Abdominal - gastric nodes
Surfaces of the stomach
Anterior
Posterior
Curvatures of the stomach
Greater
Lesser
Orifices of the stomach
Cardia
Pylorus
What is the name of the notch that marks the junction of the body with pyloric antrum along the lesser curve?
Incisura angularis
What is attached to the lesser and greater curves of the stomach?
Lesser and greater omentum respectively
What marks the junction of the pylorus with the duodenum?
Constant prepyloric vein of Mayo, which crosses it vertically
Relations of the stomach
Anterior (left to right) - diaphragm, abdominal wall, left lobe of liver
Posterior - separated from diaphragm, aorta, pancreas, spleen, left kidney and suprarenal gland, transverse mesocolon and colon by lesser sac of peritoneum
Arterial supply of stomach
Left gastric artery (from coeliac axis) - runs along lesser curve and anastomoses with right gastric branch of common hepatic artery
Right gastroepiploic artery (from gastroduodenal branch of hepatic artery) - anastomoses along greater curve with left gastroepiploic artery (from splenic artery)
Short gastric arteries (from splenic artery)
Venous drainage of stomach
Follows arteries, into the portal vein
Lymphatic drainage of stomach
Cardiac area - drains along left gastric artery to coeliac nodes
Area supplied by splenic artery - drains via nodes accompanying that artery to LN at hilum of spleen then to those along upper border of pancreas, eventually to coeliac nodes
Rest of stomach:
- Via branches of hepatic artery through nodes along lesser curve to coeliac nodes
- Through nodes along right gastroepiploic vessels to subpyloric nodes, then to coeliac nodes
Nerve supply of stomach
Anterior vagus nerve close to oesophageal wall - gives off hepatic branch and pyloric branch to pyloric sphincter
Posterior vagus nerve further from oesophageal wall - gives off coeliac branch passing to coeliac axis before sending a gastric branch to posterior surface of stomach
Gastric divisions of both vagi (nerves of Latarjet) reach the stomach at the cardia and descend along the lesse curve between the anterior and posterior peritoneal attachments of the lesser omentum
What is the surface of gastric mucosa covered by?
Columnar epithelial cells which secrete mucus and alkaline fluid to protect the epithelium from mechanical injury and gastric acid
What are the 3 areas of gastric mucosa?
Cardiac gland via area gastro-oesophageal junction - contains mucus-secreting cells
Acid-secreting region (oxyntic gland area) - contains parietal (oxyntic) cells and chief (zymogen) cells
Pyloric end area (distal 30% of stomach) - contains ‘G’ cells producing gastrin with mucus-secreting cells
In a retrograde spread of gastric carcinoma, what can happen with regards to the lymphatic drainage?
Spread may occur into the hepatic LNs at porta hepatis - enlargement of these nodes may cause external compression of bile ducts resulting in obstructive jaundice
Contents of femoral triangle
(Medial to lateral) Femoral vein Femoral artery Femoral nerve Deep and superficial inguinal LNs Lateral cutaneous nerve Great saphenous vein Femoral branch of genitofemoral nerve
In the lesser pelvis, where does the obturator nerve lie?
Lateral to the internal iliac vessels and ureter
Joined by the obturator vessels lateral to the ovary and ductus deferens
What does the obturator nerve supply?
Medial compartment of thigh
Muscles: external obturator, adductor longus/brevis/magnus (lower part by sciatic nerve), gracilis
What does the cutaneous branch of the obturator nerve supply?
Note: cutaneous branch is often absent.
When present, it passes between gracilis and adductor longus near middle part of thigh.
Supplies skin and fascia of distal 2/3 of medial aspect.
What is the obturator canal and its contents?
Connects the pelvis and thigh.
Contains: obturator artery and vein, nerve which divides into anterior and posterior branches.
What is the spermatic cord formed by?
Vas deferens
Layers of spermatic cord and their origins
External spermatic fascia - external oblique aponeurosis
Cremasteric fascia - internal oblique aponeurosis
Internal spermatic fascia - transversalis fascia
Contents of the spermatic cord
3 arteries - testicular (from AA), cremasteric (from inferior epigastric), artery to vas deferens (from inferior vesical, anterior division of internal iliac artery)
3 nerves - genital branch of genitofemoral nerve (to cremaster), sympathetic nerves (lies on arteries), ilioinguinal nerve (lies on cord, not within)
3 others - pampiniform plexus veins (drain to R/L testicular vein), vas deferens, lymphatics (to lumbar and para-aortic nodes)
Arterial supply of scrotum
Anterior and posterior scrotal arteries
Lymphatic drainage of scrotum
Inguinal lymph nodes
Innermost layer of scrotum
Parietal layer of tunica vaginalis
Lymphatic drainage of testes
Para-aortic nodes
Where does the iliacus muscle lie?
Posterior to the femoral nerve in femoral triangle
Where does the femoral sheath lie?
Anterior to the iliacus and pectineus muscles
Femoral nerve root values
L2-4
What does the femoral nerve innervate?
Pectineus
Sartorius
Quadriceps and rectus femoris
Vastus lateralis/medialis/intermedius
Branches of femoral nerve
Medial and intermediate cutaneous nerves of thigh
Saphenous nerve
Which muscle does the femoral nerve penetrate?
Psoas major
How does the femoral nerve exit the pelvis?
By passing under the inguinal ligament to enter the femoral triangle
What is the location of femoral nerve relative to the femoral artery and vein?
Lateral to femoral artery and vein
Posterior relations of ascending colon
Iliacus
Quadratus lumborum
Perirenal fascia over lateral aspect of kidney
How is the transverse colon attached to the anterior border of pancreas?
By the transverse mesocolon
Relations of transverse colon
Anterior - greater omentum
Posterior - kidneys, 2nd part of duodenum, pancreas, small intestine
Superior - liver, gallbladder, greater curvature of stomach, spleen
Inferior - small intestine
What lies between the splenic flexure and diaphragm?
Phrenicocolic ligament, a fold of peritoneum
Relations of descending colon
Anterior - small intestine
Posterior - Left kidney, quadratus lumborum, iliacus
Which structures does the root of sigmoid colon cross over?
External iliac vessels
Left ureter
What are taenia coli?
3 flattened bands of longitudinal muscle passing from caecum to rectosigmoid and converging at base of appendix
What are appendices epiploicae?
Fat-filled tags scattered over the surface of the colon, most numerous in sigmoid colon (absent in appendix, caecum, rectum)
Commonest positions of appendix
Retrocaecal - 75%
Pelvic - 20%
Preileal or postileal - 5%
Arterial supply of appendix
Appendicular artery (from ileocolic artery)
Start and end points of rectum
~12cm long, starts anterior to 3rd segment of sacrum and ends ~2.5cm in front of coccyx
What is the transition between sigmoid and rectum marked by?
Disappearance of taenia coli
Extraperitoneal parts of rectum
Upper 1/3 - posterior
Middle 1/3 - posterior and lateral
Lower third - whole thing, lie below pelvic peritoneum
What is the extraperitoneal rectum surrounded by?
Mesorectal fat containing lymph nodes
Note: this layer is removed during rectal cancer surgery (total mesorectal excision)
Fascial layers surrounding rectum
Denonviliers fascia - anterior (prostate)
Waldeyers fascia - posterior (sacrum)
Lateral inflexions of rectum
Left, right then left
Each inflexion is capped by valve of Houston
Relations of rectum
Anterior (M) - rectovesical pouch, bladder, prostate, seminal vesicles
Anterior (F) - rectouterine pouch (Douglas), cervix, vaginal wall
Posterior - sacrum, coccyx, middle sacral artery, lower sacral nerves
Lateral - levator ani, coccygeus
Arterial supply of rectum
Superior rectal artery (from IMA) - whole rectum and upper half of anal canal
Middle rectal artery (from internal iliac) - small, only muscle coats of rectum
Inferior rectal artery (from internal pudendal) - lower half of anal canal
Venous drainage of rectum above vs below dentate line
Above - superior rectal vein (portal venous system)
Below - inferior rectal vein (systemic)
Note: site of portosystemic anastomosis
Lymphatic drainage of rectum above vs below dentate line
Above dentate line - mesorectal nodes along superior rectal vessels draining into internal iliac nodes
Below dentate line - superficial inguinal nodes
Epithelium above vs below dentate line
Above - columnar (adenocarcinoma
Below - non-keratinised stratified squamous (SCC) (until Hilton’s white line where anal verge becomes continuous with perianal skin containing keratinised epithelium)
Embryological origin above vs below dentate line
Above - endoderm
Below - ectoderm
Arterial/venous supply above vs below dentate line
Above - superior rectal
Below - middle and inferior rectal (venous only inferior)
Nerve supply above vs below dentate line
Above - inferior hypogastric plexus (autonomic), not sensitive to pinprick
Below - inferior rectal nerves (somatic), sensitive to pinprick (relevant when injecting haemorrhoids)
At which vertebral level does the left colon become the sigmoid?
L3-4
What is the name of the artery that forms as a result of anastomoses between branches of SMA and IMA along length of colon?
Marginal artery (of Drummond) - from right colon
Weakest near splenic flexure. Can cause ischaemic colitis.
Contribution from the marginal artery becomes significant when IMA is surgically divided (e.g. during AAA repair).
Position of rectal veins
1 on left, 2 on right
This explains the 3, 7 and 11 o’clock positions of haemorrhoids when anal canal is viewed with patient in lithotomy position.
Where do the efferent vessels from nodes near origins of SMA and IMA drain into?
Cisterna chyli
What can be found at the midpoint of the anal canal?
Vertical columns in the mucosa (columns of Morgagni)
What can be found at the distal end of the vertical columns in the anal canal?
Valve-like folds (anal valves of Ball)
Muscles of anal sphincters
Internal anal sphincter - smooth muscle continuous above with circular muscle of rectum, surrounds upper 2/3 of rectum, supplied by sympathetic nerves
External - striated muscle that surrounds the internal anal sphincter but extends further distally
Parts of external anal sphincter
3 parts:
- subcutaneous
- superficial, attached to coccyx behind and perineal body in front
- deep, continuous with puborectalis of levator ani
What is the anorectal ring?
The deep part of external anal sphincter where it blends with levator ani together with internal sphincter
Note: anorectal ring is palpable with finger in anal canal where it forms a ring, immediately above which the finger enters the ampulla of the rectum
What is the subcutaneous part of the external anal sphincter traversed by?
Fan-shaped expansion of longitudinal muscle fibres of anal canal
Nerve supply of external anal sphincter
Inferior rectal branch of pudendal nerve (S2-3)
Perineal branch of S4
Relations of 1st part of duodenum
Anterior - liver, gallbladder
Posterior - portal vein, CBD, gastroduodenal artery (IVC behind all these)
Relations of 2nd part of duodenum
Anterior - transverse colon
Posterior - right kidney and ureter
Relations of 3rd part of duodenum (longest part, ~10cm)
Anterior - root of mesentery, superior mesenteric vessels
Posterior - IVC, aorta, L3 vertebra
How may the DJ flexure be identified during surgery?
At DJ flexure, small intestine leaves posterior abdo wall and acquires a mesentery
By presence of suspensory ligament of Treitz - a peritoneal fold descending from the right crus of diaphragm to termination of duodenum
Arterial supply of duodenum
Superior pancreaticoduodenal artery (from gastroduodenal)
Inferior pancreaticoduodenal (from SMA)
These 2 arteries lie in the curve between duodenum and head of pancreas, supplying both structures
Average length of small intestine
6 metres
Length of mesentery of small intestine
About 15cm, attached across posterior abdominal wall
Start and end points of small intestine
Starts at DJ flexure to the left of L2 vertebra, passes obliquely downwards to right sacroiliac joint
Relations of root of mesentery of small intestine
(Left to right) 3rd part of duodenum Aorta IVC Right psoas major Right ureter Right gonadal vessels Right iliacus
Contents of mesentery of small intestine
Superior mesenteric vessels (enter mesentery anterior to 3rd part of duodenum)
LNs draining small intestine
Autonomic nerve fibres
How do you distinguish between jejunum and ileum at surgery?
Jejunum has a thicker wall due to valvulae conniventes or plicae circularis (i.e. circular folds of mucosa) - larger and more numerous than in ileum
Jejunum has greater diameter
Final straight arteries to ileum shorter and more numerous than in jejunum
Mesentery becomes thicker and more fat-laden from above downwards
Jejunum most likely to be found at/above level of umbilicus while ileum tends to lie below umbilicus in the hypogastrium and pelvis
