Please enable JavaScript.

Coggle requires JavaScript to display documents.

Anatomy of the abdomen (Abdominal Viscera (Large Intestine (Cecum and…

- - - - Does not originate posteriorly from the thoracolumbar fascia (not like the other 2)
      - Posterior most fibers (from rib 12) run almost vertically to the iliac crest, more anterior fibers fan out , becoming increasingly medial in direction, and most anterior and superior fibers running almost horizontally
      - Become aponeuroses approx at MCL, and at the spino-umbilical line (from umbilicus to ASIS) inferiorly, forming a sheet of tendinous fibres that decussate at linea alba, most becoming continuous with that of the inferior oblique
        
        Together form a digastric muscle through its connection
      - Inferior margin of external oblique aponeurosis is thickened as an undercurving fibrous band with a free posterior edge that spans between ASIS and pubic tubercle as the inguinal ligament
        
        serves as a retinaculum (retaining band)
      - Origin: External surface of ribs 5-12
        Insertion: Linea Alba, pubic tubercle, anterior half of iliac crest
        Innervation: thoracoabdominal nerves (T7-T11) and subcostal nerves (T12)
        Compress and support abdominal viscera, flex and rotate trunk
    - - Thin muscle sheet that fans anteromedially, becomes aponeurotic at MCL and participates in formation of rectus sheath
      - Fibers run perpendicular to external obliques, except for the inferior most fibers, which arise from lateral half of the inguinal ligament
      - Origin: Thoracolumbar fascia, anterior 2/3 of iliac crest and CT deep to lateral third of inguinal ligament
        Insertion: Inferior borders of ribs 10-12, Linea alba, and pecten pubis via conjoint tendon (joins with transversis abodominis)
        Innervation: thoracoabdominal nerves (anterior rami of T6-T12) and first lumbar nerve
        Compress and support abdominal viscera, flaxes and rotates trunk
    - - Runs transversely except for inferior ones, which run parallel to those of internal oblique, also end in aponeuoses
      - Between internal oblique and transversus abdominis is a neurovascular plane (of the anterolateral abdominal wall)
        Nerves leave the plane in the anterior part and lie mostly in subcutaneous tissue
      - Origin: Internal sufaces of ribs 7-12 costal cartilages, thoracolumbar fascia, iliac crest and connective tissue deep to lateral third of inguinal ligament
        Insertion: linea alba with aponeurosis of internal oblique, pubic crest, and pecten pubis via conjoint tendon (with internal oblique)
        Innervation: Thoraco-abodminal nerves (anterior-rami of T6-T12 spinal nerves) and first lumbar nerve
        Compresses and supports abdominal viscera
    - - Principle vertical muscle of anterior wall
      - Anchored transversely by attachment to anterior layer of the rectus sheath at three or more tendinous intersections (grooves usually at xiphoid process, umbilicus and half way these structures)
      - Origin: Pubic Symphysis and Pubic crest
        Insertion: xiphoid process and 5th-7th costal cartilages
        Innervation: Thoracoabdominal nerves (anterior rami of T6-T12)
        Flex trunk, compress abdominal viscera, stabilizes and controls tilt of pelvis (antilordosis)
    - - Rectus sheath
        
        Strong, incomplete fibrous compartment
        
        Superior and inferior epigastric arteries and veins, lymphatic vessels and thoracoabdominal nerves
        
        External oblique aponeurosis contributes to anterior wall throughout the length (+ front layer of internal oblique aponeurosis)
        
        Internal oblique (back layer) and transversus abdominis contribute to superior 2/3 of posterior sheath
        
        At around 1/3 distance from umbilicus to pubic crest , aponeuroses of all three muscles pass anterior to the rectus abodminis to form the anterior layer, inferior to this, the posterior sheath is now only covered by transversalis fascia
        
        Cresentic arcuate line demarcates this transition, as well as the entry of the external iliac artery into the sheath
      - Linea alba is continuous down the medial line, with one defect: the umbilicus
    - - Form a strong expandable support for anterolateral wall
      - Support the abdominal viscera and protect them from most injuries
      - Compress the abdominal contents to maintain or increase introabdominal pressure, opoosing the diaphragm
      - Move the trunk and help to maintain posture
  - - - almost identical to map of peripheral nerve distribution
      - Because anterior rami of spinal nerves T7-12 do not participate in plexus formation
      - L1 is an exception, as it bifurcates into 2
      - T10: umbilicus
        L1: Inguinal fold
    - - Thoraco-abdominal nerves
        
        Distal, abdominal parts of anterior rami of inferior 6 thoracic spinal nerves (T7-11), formal inferior intercostal nerves
        
        Pass infero-anteriorly from the intercostal spaces and run in the neurovascular plane between internal oblique and transversus abdominis to supply abdominal skin and muscle
        
        Branches enter sub-cu tissues as lateral cutaneous branch (in anterior axillary line) and anterior cutaneous branches of T7-11 (parasternal line)
      - Lateral (Thoracic) cutaneous branch
        
        of thoracic spinal nerves T7-9/10, enter sub-cu tissues at anterior axillary line and continues as anterior and posterior divisions
        
        Skin of R and L hypochondriac regions
      - Subcostal nerve
        
        Large anteriior ramus of T12
        
        Inferior border of 12th rib, pass into subumbilical abdominal wall (superior to iliac crest)
      - Iliohypogastric and ilio-inguinal nerves
        
        Terminal branches of anterior ramus of L1
        
        Iliohypogastric
        
        superior branch, most inferior abdominal wall (skin overlying iliac crest, upper inguinal and hypogastric regions; internal oblique and transversus abdominis muscles)
        
        Ilio-inguinal
        
        Inferior branch, transverse the inguinal canal
        
        Skin of lower inguinal region, anterior scrotum or labium majus and adjacent medial thigh, inferiormost internal oblique and transversus abdominis
      - Nerve supply
        
        T7-9: skin superior to umbilicus
        
        T10: around umbilicus
        
        T11 plus cutaneous branches of subcostal, L1: supply skin inferior to umbilicus
    - - Veins
        
        Cutaneous veins surrounding umbilicus anastomose with para-umbilical veins, small tributaries of hepatic portal vein that parallel the obliterated umbilical vein
        
        Thoraco-epigastric vein: develop between superficial epigastric vein (femoral vein tributary) and lateral thoracic vein
        
        Deeper veins of antero-lateral abdominal wall accompany the arteries (w same name)
        
        Deeper, medial venous anastomoses may develop between inferior epigastric vein and superior epigastric/internal thoracic vein
        
        anastomoses may afford collateral circulation during blockage of either Vena Cava
      - Vessels (arteries)
        
        Superior epigastric
        
        branches of musculo-phrenic vessels from the internal thoracic vessels
        
        Enters rectus sheath superiorly through its posterior layer, anastomose with inferior epigastric at approx umbilical region
        
        Inferior Epigastric
        
        plus deep circumflex iliac vessels form external iliac vessels (just superior to inguinal ligament)
        
        Runs superiorly in the transversalis fascia to enter rectus sheath below the arcuate line
        
        Superficial circumflex iliac and superficial epigastric
        
        Femoral artery and great saphenous veins respectively
        
        Posterior intercostal vessels
        
        of 11th IC space and anterior branches of subcostal vessels
      - Lymphatic drainage
        
        superficial follows sub-cu veins
        
        Superior to transumbilical plane drains to axiallary lymph nodes, a few to parasternal lymph nodes
        
        Inferior to the plane drains to superficial inguinal lymph nodes
        
        Deep lymphatic vessels
- - - - Inguinal Ligament and iliopobic tract extend from ASIS to pubic tubercle, constitute a bilaminar anterior (flexor) retinaculum of the ip joint
      - Retinacula: thick fibrous bands that occur in relationship to many joints that have a wide range of movement to retain structures against the skeleton during various positions of the joints
      - Inguinal ligament: dense band constituing the inferiormost part of the external oblique aponeurosis. most fibers of ligament's medial end insert into pubic tubercle, some follow other courses:
        
        Lacunar ligament: deeper fibers pass posteriorly to attach to superior pubbic ramus, lateral to tubercle
        
        Pectineal ligament: most lateral of lacunar ligament that run along pecten pubis
        
        Reflected inguinal ligament: more superior ligaments that fan upward, bypass tubercle and cross linea alba to blend the aponeurosis
      - Iliopubic tract
        
        thickened inferior margin of transversalis fascia
        
        Fibrous band running parallel and posterior to inguinal ligament
        
        reinforce posterior wall and floor of inguinal canal, briding structures transversing the subinguinal space
      - Inguinal ligament and iliopubic tract span and provide central strength to area of innate weakness in body wall in inguinal region called myopectineal orifice
        
        site of direct and indirect hernias and femoral hernias
    - - formed in relation to relocation of testis during fetal development
      - Oblique passage, approx 4cm long, directed inferomedially through inferior part of anterolateral abdominal wall
      - Main occupant: spermatic cord in makes and round ligament of uterus in females
      - also contain blood and lymphatic vessels, the ilio-inguinal nerve and genital branch of genitofermoral nerve (to cremaster) in both sexes
      - Has an opening on each end:
        
        Deep(internal) inguinal ring
        
        entrance to inguinal canal
        
        Superior to middle of inguinal ligament, lateral to inferior epigastric artery
        
        beginning of evagination in transversalis fascia, forming innermost covering of structures
        
        Through this, extraperitoneal ductus deferens and testiculas vessels in males and genital branch of genitofermoral nerves pass to enter canal
        
        superficial (external) inguinal ring
        
        exit of canal
        
        Split that occurs indiagonal(otherwise parallel) fibers of external oblique aponeurosis just superolateral to pubic tubercle
        
        parts of aponeurosis that lie medial or lateral form margins of the superficial ring, are called crura
        
        lateral crus attach to pubic tubercle
        
        Medial crus to pubic crest
        
        Intercrural fibers keep crura from spreading apart
      - Borders
        
        Anterior wall: external oblique aponeurosis, lateral part reinforced by muscles of internal obliqie
        
        Posterior wall: transversalis fascia, medial part reinforced by pubic attachments of internal oblique and transversus abdominus aponeurosis that merge to form conjoint tendon
        
        Roof: laterally by transversalis fascia, centrally by musculo-aponeurotic arches of internal oblique and transversus abdominis, medially by crus of external oblique aponeurosis
        
        Floor: laterally by iliopublic tract, centrally by gutter formed by infolded inguinal ligament, medially by lacunar ligament
      - Development of inguinal canal
        
        Testes develop in extraperitoneal CT in superior lumbar region of posterior abdominal wall
        
        Gubernaculum is a fibrous tract connecting primordial testis to anterolateral abdominal wall at site of future deep ring inguinal canal
        
        a peritoneal diverticulum (processus vaginalis) transverse the developing inguinal canal, carrying muscular and fascial layers of anterolateral abdominal wall before it as it enters primordial scrotum.
        
        By 12th week, testis is in pelvis, 28th week, close to the developing deep inguinal ring, beings to pass through the canal then and takes approx 3 days to transverse it.
        4 weeks later, in the scrotum
        
        as testis, ducts and vessels and nerves relocate, ensheathed by the musculofascial extensions
        
        internal and external spermatic fasciae and cremaster muscle
        
        Stalk of processus vaginalis normally degenerates (6th month), but distal saccular part forms tunica vaginalis, a serous sheath of testis and epididymis
        
        In females, gubernaculum connects the ovary and primordial uterus to the developing labium majus, represented postnatally by the ovarian ligament between ovary and uterus and round ligament of the uterus
        
        Round ligament connects to the anterior labium majus from the uterus
        
        Inguinal canal in females narrower, shorter in infants and much less oblique
        
        superficial ring of infants lie almost directly anterior to deep rings
      - Inguinal canal and increased intra-abdominal pressure
        
        deep and surperficial dont overlap because of the oblique path
        
        Increases in intra-abdominal pressure act on the inguinal canal, force posterior wall of canal against anterior wall and strengthen the wall, decreasing likelihood of hernia until pressure overcome resistance
        
        Simultaneously, contraction of external oblique approximates anterior wall to posterior wall, increasing tension on medial and lateral crura, resisting enlargement of superficial ring
  - - - Internal spermatic fascia: transversalis fascia
      - Cremasteric Fascia: internal oblique muscle
        
        contain loops of cremaster muscle, formed by lowermost fascicles of internal oblique muscle arising from inguinal ligament
        
        reflexively draws testis superiorly, in response to cold, and in warm environment, relaxes and testis descends into scrotum
        
        acts with the dartos muscle, that inserts into the skin of scrotum and contracts to the same stimuli
      - External spermatic Fascia: external oblique aponeurosis
      - Cremaster muscle innervated by genital branch of genitofemoral nerve (L1, L2)
    - - Ductus deferens
      - testicular artery (arising from aorta, to the testis and epididymis)
      - Artery of ductus deferens (from inferior vesical artery)
      - cremasteric artery: from inferior epigastric artery
      - Pampiniform venous plexus: network of 12 veins that converge superiorly as right or left testicular veins
      - Sympathetic nerve fibers on arteries and ductus deferens
      - Lymphatic vessels
      - Vestige of processus vaginalis: fibrous thread in anterior part of spermatic cord, extending between abdominal peritoneum and tunica vaginalis, may not be detectable
  - - - Medial to inferior epigastric vessels: direct herniation
        
        Due to weakness in apex of hesselbach's triangle, exits through superficial ring, does not enter scrotum
        
        Hesselbach's triangle
        
        inferior: inguinal ligament
        
        Lateral: inferior epigastric artery
        
        Medial: rectus abdominus
        
        Wont come in contact with deep inguinal ring
      - Lateral to inferior epigastric vessels: indirect hernia
        
        Follows path of descend of testes, into the internal ring, into scrotum
        
        Covered by all 3 layers of spermatic fascia
    - - Hydrocele
        
        excess fluid (transilluminates)
        
        In a persistent processus vaginalis
        
        May be associated with indirect hernia
        
        Of testis: confined to scrotum and distends tunica vaginalis
        
        Of spermatic cord: confined to spermatic cord and distends persistent part of the stalk of processus vaginalis
      - Hematocele
        
        Collection of blood in tunica vaginalis that results from rupture of (e.g.) testicular artery by trauma to testis
        
        Trauma may produce hematoma (accumulation of blood, usually clotted in any extravascular location)
        
        Does not transilluminate
        
        Testicular hematocele could be associated with scrotal hematocele
      - Varicocele
        
        vine like pampiniform plexus of veins become dilated and tortuous, visible when standing or straining
        
        Usually disappears when person lies down
        
        like feeling a bag of worms
        
        May result from defective valves in tesituclar veins, but kidney or renal vein problems could be the reason too
        
        Left side most affected due to the acute angle at which the right vein enters the IVC, more favorable than the 90 degree angle at which the left testicular vein enters the left renal vein, making it more susceptible to obstruction or reversal of flow
- - - - served by same blood and llymphatic vasculature and same somatic nerve supply as the wall it lines
      - Sensitive to pressure, pain, heat and cold and laceration
      - pain is usually well localized except on the inferior surface of the central part of diaphragm, where innervated by phrenic nerves -> referred pain over shoulder (C3-C5 dermatome)
    - - same blood, lymphatic vasculature and visceral nerve supply
      - Insensitive to touch, heat and cold and laceration, stimulated primarily by stretching and chemical irritation
      - Pain poorly localized, referred to dermatomes
  - - - Herniation out with its blood supply and innervation to allow for more increase in length while abdominal cavity expands
      - During herniated phase, guts rotate 90 degrees anticlockwise looking ventral-dorsal) first, followed by another 180 when it is going back in
  - - - Double layer of peritoneum that occurs as a result of invagination of peritoneum by an organ, constitutes a continuity of visceral and parietal peritoneum (embryo: dorsal mesentery)
      - provide means of neurovascular communications between organs and the body wall
      - connects intraperitoneal organ to the body wall, usually posterior
      - Mesentery normally refers to that of small intestines, while others are named with meso in front, e.g. Transverse mesocolon: mesentery for transverse colon
      - an omentum is a double layered extension or fold of peritoneum that passes from the stomach and proximal part of the duodenum to adjacent organs
        
        Embryological source: ventral mesentery
        
        greater omentum
        
        four layered, hang down like apron, from greater curvature of stomach to transverse colon
        
        Lesser omentum
        
        much smaller, double layered, connect lesser curvature of stomach and proximal duodenum to the liver, also contains portal triad
      - Peritoneal ligament
        
        liver is connected to
        
        anterior abdominal wall by falciform ligament
        
        stomach by hepatogastric ligament (membranous portion of lesser omentum)
        
        Duodenum by hepatoduodenal ligament, thickened free edge of lesser omentum which conducts portal triad
        
        Stomach connected to
        
        inferior surface of diaphragm by gastrophrenic ligament
        
        Spleen by gastrosplenic ligament
        
        transverse colon by gastrocolic ligament
      - every organ has an area not covered by peritoneum to allow entry and exit of neurovascular structures
        
        BARE AREAS
  - - - Superior recess: limited superiorly by diaphragm and posterior layers of coronary ligament of liver
      - Inferior recess: between superior parts of greater omentum
      - Communicates with greater sac through omental foramen (foramen of winslow)
        
        Located by running finger along gall bladder to the free edge of lesser omentum, usually admits two fingers
        
        Anterior: hepatoduodenal ligament, containing portal triad
        
        Posterior: IVC
        
        Superior: liver
        
        Inferior: duodenum
    - - loop of small intestine may pass through foramen into omental bursa and be strangulated by edges of faramen
      - None of the boundaries can be incised as each contains blood vessels, swollen intestine must be decompressed by a needle so that it can return to the greater sac
- - - - at pharyngo-esophageal junction, 15cm from incisor teeth
    - - first cross arch of aorta, 22.5cm from incisor teeth
      - Then where it is cross by left main bronchus, 27.5cm from incisor teeth
    - - through esophageal hiatus, approx 40cm from incisor teeth
  - - - wider part: antrum, leads into pyloric canal
      - PylorusL gatekeeper, distal, sphincteric region of pyloric part
    - - gastric folds: rugae
    - - Arteries
        
        Lesser curvature: Left gastric arteries and right gastric arteries (from common hepatic artery)
        
        Greater curvature: right and left gastroomental (gastroepiploic) arteries (from GDA and splenic artery respectively)
        
        Fundus and upper body: short and posterior gastric arteries (from splenic arteries)
        
        gastroduodenal artery supplies to proximal duodenum too
      - Veins
        
        Right and left gastric veins (left to splenic vein first) to portal vein
        
        Short gastric veins and left gastro-omental veins drain to splenic vein, join SMV to form hepatic portal vien
        
        Right gastro-omental vein to SMV
      - Nerves
        
        parasympathetic: posterior and anterior vagus trunks and branches, which enter abdomen through esophageal hiatus
        
        Sympathetic: from T6 through T9 of spinal cord, pass celiac plexus through greater splanchnic nerve
  - - - First and shortest part (25cm)
      - Widest and fixed part
      - C-shaped course, from the pylorus to the duodenojejunal flexure
        
        occurs at L2 level, 2-3 cm left of midline, usually takes the form of an acute angle (duodenojejunal angle)
      - most fixed by peritoneum structures to posterior abdominal wall, partially retroperitoneal
      - Divided into 4 parts
        
        short, (approx 5cm) and lies anterolateral to body of L1 vertebra
        
        descending, longer (7-10cm) and descends along right sides of L1-L3 vertebrae
        
        Inferior, short (5cm), cross L3 vertebea
        
        Ascending, short (5cm) begins at left of L3, rise superiorly as far as superior border of L2
      - First 2 cm of superior duodenum, immediately distal to pylorus, has a mesentery and is mobile (called the ampulla (duodenal cap))
        
        Distal 3cm and other parts of duodenum have no mesentery and are immobile as they are retroperitoneal
      - Superior part is overlapped by liver and gallbladder, and proximal part has a hepatoduodenal ligament
      - Descending duodenum has the ampulla of vater
      - Inferior runs transversely to left, passing over IVC, aorta and L3, crossed by SMA and V and the root of mesentery of jejunum and ileum
      - Ascending part: curves anteriorly to join the jejunum at the duodenojejunal flexure, supported by ligament of treitz
        
        ligament of treitz is a muscle composed of a slip of skeletal muscle from diaphragm and a fibromuscular band of smooth muscle from the 3rd and 4th parts of duodenum, contraction widens the angle, facilitating movement of intestinal contents
      - Suspensory muscle passes posterior to pancreas and splenic vein, anterior to left renal vein
      - arteries
        
        GDA and its branch, the superior pancreaticoduodenal artery supplies proximal to entry of bile duct into descending part of duodenum
        
        SMA supplies here through inferior pancreaticoduodenal artery, supplies duodenum distal to entry of bile duct
      - veins follow arteries and drain into portal vein
    - - Iileum ends at ileocecal junction
      - Jejunum constitute approx 2/5 of the intraperitoneal section of small intesting, remaining will be the ileum
      - Most of jejunum lies in Left upper quadrant (LUQ), most of ileum in RLQ
      - Terminal ileum usually in pelvis from which it ascends, ending in medial aspect of cecum (is around 30cm)
      - Mesentery is a fan-shaped fold of peritoneum, that attaches to the jejunum and ileum, runs from the duodenojejunal junction to the ileocecal juntion
      - Origin or root of mesentery (approx 15cm long) directed obliquely, inferiorly to the right
      - between the two layers of mesentery of the root are superior mesenteric vessels, lymph nodes, a variable amount of fat and autonomic nerves
      - SMA supplies via jejunal and ileal arteries, and usually arises from abdominal aorta at L1, approx 1cm inferior of celiac axis
      - sends out 15-18 branches of arteries to the jejunum and ileum, which then unite to form loops or arches, called arterial arcades, and then give rise to straight arteries, called vasa recta
      - SMV drains jejunum and ileum, lies anterior and to the right of SMA, ends posterior to neck of pancreas where it unites with splenic vein to join the hepatic portal vein
      - jejunum has greater vascularity, longer vasa recta and few large loops of arcades
      - ileum has less vascularity, short vasa recta and many short loops of arcades
      - SMA and its branches surrounded by periarterial nerve plexus, which are connected to parts of the intestine supplied by this artery
        
        Sympathetic fibers originate from T8-T10 and reach the superior mesenteric nerve plexus
        
        sympathetic stimulation reduce peristaltic and secretory activity of intestine and cause vasoconstriction, reducing or stopping gastrointestinal activity
        
        Parasympathetic from posterior vagal trunks, stimulation increases peristalsis and secretion and cessation of sympathetic stimulation allows vasodilation, restoring blood flow to active bowel
  - - - Omental appendices: small, fatty like, omentum-like projections
      - Teniae coli: three distinct longitudinal bands of muscles
        
        Mesocolic tenia (transverse and sigmoid mesocolons attach)
        
        Omental tenia (omental appendices attach)
        
        Free tenia (not attached to anything)
      - Haustra, sacculations of wall of colon between teniae (as teniae are shorter than the actual large bowel
      - much greater caliber
    - - Cecum is first part of large intestine
      - a blind pouch, around 7.5 cm inboth length and breadth, lies in iliac foosa of RLQ, inferior to ileocecal junction
      - if cecum distended with feces or gas, could be palpable
      - lies with 2.5 cm of inguinal ligament, almost entirely enveloped by peritoneum, can be lifted freely, but has no mesentery, but held by cecal folds of peritoneum
      - Appendix is a blind diverticulum that contains masses of lymphoid tissue, arise from posteromedial aspect of cecum inferior to ileocecal junction
      - has a short triangular mesentery, meso-appendix, derived from posterior side of terminal ileum, attach to cecum and proximal part of appendix
      - Supplied by appendicular artery, a branch of ileocolic artery, and drained by a tributary of SMV, the ileocolic vein
      - Supplied by ileocolic artery, the terminal branch of SMA
    - - Ascending colon
        
        from cecum to hepatic flexure (at right lobe of liver), lies deep to 9th and 10th rib, overlapped by inferior part of liver
        
        narrower than cecum, secondarily retroperitoneal along right side of posterior abdominal wall, usually covered by peritoneum anteriorly on both side, but 25% have short mesentery
        
        Separated from anterolateral abdominal wall by greater omentum, with a deep vertical groove (right paracolic gutter) lined with parietal peritoneum at the lateral aspect
        
        arterial supply: ileocolic and right colic arteries from SMA, which anastamose with each other and with the right branch of middle colic artery, first in a series of anastomotic arcades from the left colic to the sigmoid arteries to form a continuous arterial channel (marginal artery)
        
        nerve: superior mesenteric nerve plexus
      - Transverse colon
        
        third, longest and most mobile, cross from right to left (splenic) flexure, where it turns inferiorly to form descending colon
        
        splenic flexure usually more superior and more acute, less mobile than hepatic flexure
        
        Anterior to the inferior part of left kidney, attach to diaphragm through phrenicocolic ligament
        
        root of transverse mesocolon lies along inferior border of pancreas and is continuous with parietal peritoneum posteriorly
        
        freely movable, is in variable position, usually hanging to level of umbilicus (L3) or in tall and thin people, at the pelvis
        
        Arterial supply mainly from middle colic artery, a branch of SMA (right colic artery, first 2/3 of transverse colon) and a branch of IMA(left colic artery)
        
        anastamose to form marginal artery
        
        nerve: superior mesenteric nerve plexus
      - Descending colon
        
        secondarily retroperitoneal
        
        Between left colic flexure and left iliac fossa, and continues into sigmoid colon
        
        33% have short mesentery, usually not long enough to cause volvulus (twisting) of colon
        
        descends, colon pass anterior to lateral border of left kidney
        
        also have paracolic gutter in its lateral aspect
    - - S shaped loop to rectum, extends from iliac fossa to S3 vertebra where it joins the rectum, usually have a long mesentery (sigmoid mesocolon) and has free movement
      - Root of sigmoid mesocolon has inverted v shaped attachment, with left ureter and division of left common iliac artery
        lie retroperitoneally, posterior to apex of root
      - Omental appendices are long, disappear when sigmoid mesentery terminates
      - arterial supply: left colic and sigmoid arteries, branches of IMA
      - nerve
        
        sympathetic: lumbar splanchnic nerves, superior mesenteric plexus
        
        Para: pelvic splanchnic nerves, inferior hypogastric plexus and nerves
    - - rectum is fixed
  - - - Protrusion of part of the stomach into the mediastinum through esophageal hiatus in the diaphragm
      - Possibly due to weakening of muscular part of diaphragm and widening of the esophageal hiatus
      - 2 mains types
        
        Paraesophageal
        
        Less common
        
        Cardia remains in normal position, pouch of peritoneum, often containing part of the fundus, extends through the hiatus anterior to the esophagus
        
        Usually no regurgitation as cardial orifice is in normal position
        
        Sliding hiatal hernia
        
        common
        
        Abdominal part of esophagus, cardia and parts of the fundus of stomach slide superiorly through esophageal hiatus into thorax, especially when a person lies down or bends over
        
        some regurgitation possible because clamping of right crus of diaphragm in inferior end of esophagus is weak
    - - marked thickening of smooth muscle of pylorus, causing narrow pyloric canal, resist gastric emptying
      - Proximally, stomach become dilated
      - Treated with pyloromyotomy, to allow free passage
    - - H. Pylori erodes protective mucous lining of stomach, inflaming the mucosa and making it vulnerable to effects of gastric acid and digestive enzymes (pepsin) produced by the stomach -> ulcer
      - Ulcer erodes into gastric arteries, can cause life threatening bleeding
      - secretion of gastric acid by parietal cells of stomach largely controlled by vagus nerves, vagotomy can reduce secretion of acid.
        
        try to preserve as much as you can, taking out only parts that have parietal cells
      - posterior gastric ulcer may erode through stomach wall into pancreas, to the splenic artery, potentially causing a lot of pain and hemorrhage into the peritoneal cavity
      - can also cause duodenal ulcers
    - - remnant of proximal part of embryonic yolk stalk, appear as a finger like pouch (failure of vitelline duct to regress or involute)
      - always at site of attachment of omphalo-enteric duct
      - could have cell types of other parts of the gut (acid producing gastric tissue, pancreatic tissue, jejunal or colonic mucosa)
    - - base is at Mcburney's point
    - - oomphalocoele: herniation of infant's intestine/other organs outside the body covered with a thin layer of tissue (amnion, not enough mesodermal tissue to close off wall)
      - Gastrochisis
        
        same as oomphalocoele, except no peritoneal covering
      - abnormal rotation: duodenum infront of colon
- - - - expanded part of gland embraced by c-shape curve of duodenum to the right of SM vessels, just inferior to transpyloric plane
        
        rests on the IVC, reight renal artery and vein and left renal vein
        
        Bile duct lies in a groove on the posterosuperior surface of the head or is embedded in
    - - short and overlies SM vessels, which form a groove in its posterior aspect
      - anterior surface is adjacent to pylorus of stomach, SMV joins splenic vein posterior to neck to form portal vein
    - - left of SM vessels, pass over aorta and L2 vertebra, continuing just above transpyloric plane posterior to omental bursa
      - Posterior in contact with aorta, SMA, left supraadrenal gland, left kidney and renal vessels
    - - anterior to left kidney
      - mobile, pass between layers of splenorenal ligament with splenic vessels
- - - - Superior (R to L): VII, VIII, IVA, II
      - Inferior (R to L): VI, V, IVB, III
      - I is inside the liver, near IVC, covering both R and L sides
    - - Upon removal, liver will look bigger due to regeneration from stellate cells
      - Can be operated on based on the different segments if tumors are small, but if it is close to the vein, may have to remove entire lobe
        
        e.g. if 5 removed, segments 5,6,7 and 8 removed
      - based on splitting from portal triads, or due to the cantlie line on the visceral surface that runs from the IVC superiorly to the notch for the fundus of the gallbladder
      - Subdivided vertically into medial and lateral divisions (left and right hepatic veins) with each of the four divsions receiving a secondary branch of the portal triad
      - Transverse hepatic plane subdivides 3 of the 4 divsions, each receiving tertiary branches of the triad
      - Caudate lobe (segment I) supplied by branches of both divisions, drained by its own minor hepatic veins
  - - - 75-80% of blood to the liver
      - about 40% more oxygen than blood returning to the heart from the systemic circuit, sustaining liver parenchyma
      - Carries almost all of the nutrients absorbed by alimentary tract to sinusoids of the liver (except for liver, which go through lacteals to lymphatic vessels, bypassing liver)
      - Formed by superior mesenteric and splenicc veins posterior to neck of pancreas, ascends anterior to IVC as part of portal triad
    - - Branch of celiac trunk, divided into common hepatic artery, and at the bifurcation split into hepatic artery proper and GDA
      - At or close to porta hepatis, hepatic artery and portal vein terminates by dividing to right and left branches
    - - drains parts of adjacent segments
      - Formed by union of collecting veins, drain to central veins, and then to the IVC just inferior to diaphragm
      - Attachment to these veins to IVC helps hold the liver in position
- - - - Cystic artery, supplying proximal part of the duct
      - Right hepatic artery: middle part of duct
      - GDA and posterior superior pancreaticoduodenal artery: retroduodenal part
    - - proximal part of bile duct and hepatic ducts enter liver directly
      - Posterior superior pancreaticoduodenal vein drain distal part of bile duct and empties into portal veins
    - - cystic lymph nodes near neck of gallbladder -> lymph node of omental foramen -> hepatic lymph nodes
  - - - Fundus
      - Body
      - Neck
    - - Cystic artery, commonly arise from right hepatic artery in the triangle between common hepatic duct, cystic duct and visceral surface of the liver (triangle of calot)
      - Variations occur in origin and course of cystic artery
    - - Via cystic veins
        
        enter veins directly or drain through hepatic portal vein to liver after joining veins draining hepatic ducts and proximal bile duct
      - Veins from fundus and body drains directly into visceral surface of the liver into the sinusoids
    - - Pass along cystic artery from celiac nerve plexuss and vagus nerve
      - Right phrenic nerve (somatic afferent) may carry pain due to inflammation
      - Parasympathetic stimulation cause contractions of gallbladder and relaxation of sphincters at hepatopancreatic ampulla, though are generally stimulated by CCK through the blood stream
  - - - Blood from splenic vein rich in products of RBC breakdown pass mostly to the left liver
      - Blood from SMV, rich in absorbed nutrients move mostly to the right liver
    - - Formed in
        
        Submucosa of inferior esophagus
        
        Submucosa of anal canal
        
        Peri-umbilical region
        
        Posterior aspects of secondarily peritoneal viscera
      - During obstruction of portal circulation in the liver, blood from GIT can still reach the heart through this colatleral routes
      - If excessive -> portal hypertension
- - - - Noninvasive method of imaging using MRI for diagnosis of both pancreatic and biliary disease
      - Produc detailed images of hepatobiliary and pancreatic systems
    - - for pancreatic and biliary disease diagnosis
      - Used when interventions (biopsy, stone removal, or stenting) are required
      - First, Fiberoptic endoscope passed through the mouth, esophagus and stomach
      - Then, duodenum is entered and a cannula is inserted into the major duodenal papilla and advanced under fluoroscopic control into duct of choice for injection of radiographic contrast medium