Principles of abdominal anatomy


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Lecture given on 12 Oct 2010 by Dr Vooght and Dr Banigo to Surgical Scousers.

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  • II nerve enters canal from the side (pierces internal oblique), leaves through superficial ring, supplies skin over inguinal region, upper part of thigh, root of penis, anterior third of scrotum
  • Midline- linea alba, bloodless plane, good for rapid access. ?weak since less vascular Paramedian 1 inch from midline. Rectus sheath opened, rectus displaced laterally, posterios sheath and peritoneum incised. On closing, peritoneal sutures covered by rectus muscle, strengthens peritoneal scar.It can be extended upwards into 8 th /9 th incostal space (thoracoabdominal incision), thereby extensive access to upper abdomen & thorax Transrectus-same as paramedian but rectus not reflected, instead cut. Laterally-derived blood and nerve supply disrupted. Kochers- R side biliary surgery, L side spleen. 8 th intercostal nerve sacrificed, 9 th preserved Transverse muscle-split incision (starts 1inch above ASIS) preferred generally, in line with skin creases, adequate access with muscles split not cut Pfallenstiel- used for pelvic access
  • Mobility and Stability required for propelling large volumes of food, fluid, gas Alternate segments lost their mesentery and became secured for stability, thereby secondary retro peritoneal, therefore lying directly on top of primary retroperitoneal structures. Other sections are mobile to distend and alter their relative position (mobility).
  • Serous membrane- single layer flat cells, secrete fluid to minimise friction
  • Abdo cavity consists of abdo viscera (with peritoneum) and peritoneal cavity Both of utmost importance to surgeon, the cavity to plan safe planes of dissection. Entire GI tract develops on dorsal mesentery. Foregut also has a ventral mesentery, attaching it to anterior abdo wall
  • Abdo cavity consists of abdo viscera (with peritoneum) and peritoneal cavity Both of utmost importance to surgeon, the cavity to plan safe planes of dissection. Entire GI tract develops on dorsal mesentery. Foregut also has a ventral mesentery, attaching it to anterior abdo wall
  • Principles of abdominal anatomy

    1. 1. Anatomy of Abdomen- GI tract Adonye Banigo & Abigail Vooght, Oct 2010
    2. 2. Plan- Lecture 1 <ul><li>Abdo Wall </li></ul><ul><ul><li>Surface markings </li></ul></ul><ul><ul><li>Regions </li></ul></ul><ul><ul><li>Layers </li></ul></ul><ul><ul><li>Inguinal canal & hernias </li></ul></ul><ul><ul><li>Incisions </li></ul></ul><ul><li>Abdo cavity </li></ul><ul><ul><li>Whistlestop tour of GI tract </li></ul></ul><ul><ul><li>Viscera + peritoneum + embryology </li></ul></ul><ul><ul><li>Peritoneal cavity </li></ul></ul><ul><li>Surface markings </li></ul><ul><li>Abdominal wall </li></ul><ul><ul><li>surgical incisions </li></ul></ul><ul><li>Inguinal canal </li></ul><ul><ul><li>hernias </li></ul></ul><ul><li>Whistle stop tour of gut (mouth > anus) incl. landmarks </li></ul><ul><li>Embryology of gut </li></ul><ul><ul><li>Foregut/ midgut/ hindgut principles </li></ul></ul><ul><ul><li>Peritoneum and mesenteries </li></ul></ul><ul><ul><li>Referred pain </li></ul></ul>
    3. 3. Plan- Lecture 2 <ul><li>Key features of each organ </li></ul><ul><li>The GI adnexae- liver, gallbladder, pancreas, spleen </li></ul><ul><li>Not including the bony pelvis, genitourinary system, or histology of the gut </li></ul>
    4. 4. The Abdominal Wall
    5. 5. Role of Abdo Wall <ul><li>Moving the trunk </li></ul><ul><li>Depressing the ribs </li></ul><ul><li>Compressing the abdomen </li></ul><ul><li>Supporting and protecting organs </li></ul>
    6. 6. Surface Markings Linea Alba Linea semilunaris Tendinous intersections (3)
    7. 7. Landmarks Xiphisternum T9 Iliac crest Costal Margin Umbilicus L3/4
    8. 8. 9 regions Midclavicular line
    9. 9. 9 regions Midclavicular line Transpyloric plane (L1) Transtubercular plane (L4/5)
    10. 10. 9 regions Umbilical Suprapubic Epigastric
    11. 11. 9 regions Lumbar Iliac Fossae Hypochondrium
    12. 13. Layers of Abdo Wall- Laterally <ul><li>Skin </li></ul><ul><li>Superficial fascia </li></ul><ul><ul><li>Camper’s (soft & spongy fat!) </li></ul></ul><ul><ul><li>Scarpa’s (membranous) </li></ul></ul><ul><li>External Oblique (Aponeurosis) </li></ul><ul><li>Internal Oblique </li></ul><ul><li>Transversus Abdominis </li></ul><ul><li>Transversalis Fascia </li></ul><ul><li>Extraperitoneal fat </li></ul><ul><li>Peritoneum </li></ul>
    13. 14. Layers of Abdo Wall- Medially <ul><li>Skin </li></ul><ul><li>Superficial fascia </li></ul><ul><ul><li>Camper’s (soft & spongy fat!) </li></ul></ul><ul><ul><li>Scarpa’s (membranous) </li></ul></ul><ul><li>Rectus Abdominis and Rectus Sheath </li></ul><ul><li>Transversalis Fascia </li></ul><ul><li>Extraperitoneal fat </li></ul><ul><li>Peritoneum </li></ul>
    14. 15. Abdo wall- Layers Medially Costal Margin Arcuate line (of Douglas)
    15. 16. Inguinal canal <ul><li>Passage for spermatic cord ♀ // round ligament ♂ </li></ul><ul><li>4cm long </li></ul><ul><li>Deep (internal) ring to superficial (external) ring </li></ul><ul><li>Boundaries: </li></ul><ul><ul><li>Anteriorly- E-O aponeurosis + I-O lateral 1/3 </li></ul></ul><ul><ul><li>Posteriorly- transversalis fascia + conjoint tendon medially </li></ul></ul><ul><ul><li>Above- arching fibres of internal oblique + transversalis </li></ul></ul><ul><ul><li>Below- inguinal ligament (infolded gutter of E-O) </li></ul></ul>
    16. 17. 1) External oblique aponeurosis, 2) Internal oblique muscle, 3) Transversus abdominis muscle, 4) Endo abdominal fascia, 5) Internal inguinal ring, 6) Iliopubic tract, 7) Inguinal ligament, 8) Pubic symphisis, 9) Spermatic cord, 10) Interparietal connective tissue (cremasteric fascia), 11) cremasteric muscle, 12) Aponeurotic layer of posterior inguinal wall, 13) Fascial layer of posterior inguinal wall
    17. 18. Inguinal Canal- conceptual- from above Extenal Oblique Aponeurosis Transversalis fascia ASIS Pubic Tubercle Posterior Anterior Conjoint Tendon Internal Oblique
    18. 19. Deep and Superficial Rings <ul><li>Deep Ring: </li></ul><ul><ul><li>Transversalis fascia evagination into canal as internal spermatic fascia </li></ul></ul><ul><ul><li>½ inch above midpoint of inguinal ligament </li></ul></ul><ul><ul><li>Transmits spermatic cord or round ligament </li></ul></ul><ul><li>Superficial Ring: </li></ul><ul><ul><li>V-shaped defect in E-O aponeurosis </li></ul></ul><ul><ul><li>Transmits spermatic cord + ilioinguinal nerve </li></ul></ul>
    19. 20. Spermatic Cord: 3 coverings,6 constituents <ul><li>Coverings </li></ul><ul><ul><li>External spermatic Fascia (from E-O apo) </li></ul></ul><ul><ul><li>Cremastic muscle + fascia (?I-O, TA) </li></ul></ul><ul><ul><li>Internal spermatic Fascia (transversalis fascia) </li></ul></ul><ul><li>Constituents </li></ul><ul><ul><li>Ductus Deferens </li></ul></ul><ul><ul><li>Arteries: Testicular artery, artery to ductus </li></ul></ul><ul><ul><li>Veins: Pampiniform plexus </li></ul></ul><ul><ul><li>Lymphatics </li></ul></ul><ul><ul><li>Nerves: Genital br of genitofemoral n + sympathetic twigs </li></ul></ul><ul><ul><li>Processus Vaginalis </li></ul></ul>
    20. 21. Indirect Inguinal Hernia <ul><li>Generally congenital </li></ul><ul><li>Lax deep ring </li></ul><ul><li>Repair by excising hernia sac and mesh to reinforce ring </li></ul>
    21. 22. Direct Inguinal Hernia <ul><li>Generally weakness in EO aponeurosis </li></ul><ul><li>Repair by reinforcing external ring, suturing mesh to conjoint tendon </li></ul>
    22. 23. PRINCIPLES OF INCISIONS <ul><li>Adequate exposure of the organ </li></ul><ul><li>Follow cleavage lines in skin (Langer’s lines) </li></ul><ul><li>Avoid neurovascular structures </li></ul><ul><li>Consider direction of muscles fibres and location of aponeuroses </li></ul>
    23. 24. Abdo wall nerve supply 7 8 9 10 11 12-s/c L1-i/h L1-i/i
    24. 25. Abdo Wall Arterial Supply
    25. 26. Principles of Abdominal Incisions <ul><li>Adequate exposure of the organ </li></ul><ul><li>Follow cleavage lines in skin (Langer’s lines) </li></ul><ul><li>Avoid neurovascular structures </li></ul><ul><li>Consider direction of muscle fibres and location of aponeurosis </li></ul>
    26. 27. Abdominal Incisions- access vs healing Midline Paramedian Pfannenstiel Subcostal (Kochers) Gridiron Muscle split
    27. 28. The Abdominal Cavity Viscera + peritoneum Peritoneal Cavity
    28. 29. Viscera <ul><li>Urinary- kidneys, ureters </li></ul><ul><li>Endocrine- adrenal glands </li></ul><ul><li>Develop on post. Abdo wall (1 ° retroperitoneal) </li></ul><ul><li>Arterial supply from corresponding side of aorta </li></ul><ul><li>Nerve supply bilateral , true to level of origin </li></ul><ul><li>Referred pain to corresponding side </li></ul><ul><li>Digestive- GI tract, liver & biliary tract, pancreas </li></ul><ul><li>Haemopoietic- Spleen </li></ul><ul><li>Develop on a mesentery (which some lose to become 2 ° retroperitoneal) </li></ul><ul><li>Arterial supply from front of aorta </li></ul><ul><li>Nerve supply bilateral </li></ul><ul><li>Referred pain to midline </li></ul>Paired Unpaired
    29. 30. Intro: the Peritoneum <ul><li>Serous membrane (latin =thin skin) </li></ul><ul><li>2 layers- visceral + parietal </li></ul><ul><li>Parietal </li></ul><ul><ul><li>Lines interior of body wall </li></ul></ul><ul><ul><li>Nerve & vascular supply from body wall (somatic) </li></ul></ul><ul><li>Visceral </li></ul><ul><ul><li>Covers viscera (!) </li></ul></ul><ul><ul><li>Visceral supply </li></ul></ul>
    30. 31. Mesenteries <ul><li>Double layer of serous membrane (peritoneum), suspends all intraperitoneal viscera </li></ul><ul><li>Intermediary structure between parietal and visceral peritoneum </li></ul><ul><li>Function </li></ul><ul><ul><li>Provide mobile attachment for viscus </li></ul></ul><ul><ul><li>Contains supply lines (sandwiched between 3 layers) </li></ul></ul><ul><li>All unpaired viscera develop on a mesentery </li></ul>
    31. 32. Whistlestop tour of gut
    32. 33. Stomach
    33. 34. Duodenum
    34. 35. Jejenum
    35. 36. Ileum
    36. 37. Caecum
    37. 38. Large Bowel
    38. 39. Rectum & Anus
    39. 40. Embryology of gut- 6/40 Midgut Foregut Hindgut Posterior abdo wall Mesentery (ventral) Mesentery (dorsal)
    40. 41. Foregut <ul><li>Oropharynx to D2 (precisely opening of bile duct) </li></ul><ul><li>Includes </li></ul><ul><ul><li>Outgrowths: biliary tract </li></ul></ul><ul><ul><li>Glands: liver & pancreas </li></ul></ul><ul><ul><li>Spleen </li></ul></ul><ul><li>Artery: Coeliac </li></ul><ul><li>Nerve supply: T6- T9 spinal segments </li></ul><ul><li>Rotation (on vertical axis of gut)- 90 º left </li></ul><ul><ul><li>Spleen from posterior (dorsal mesogastrium) to left </li></ul></ul><ul><ul><li>Liver from anterior (ventral mesogastrium) to right </li></ul></ul><ul><li>Retroperitoneal: 2 nd part duodenum, spleen, most of pancreas </li></ul>
    41. 42. Rotation of foregut Midgut Foregut Hindgut Mesentery (ventral) Mesentery (dorsal) liver Spleen
    42. 43. Foregut rotation 2 Greater sac Lesser sac
    43. 44. Midgut <ul><li>D2 to mid-transverse colon </li></ul><ul><li>Artery: SMA </li></ul><ul><li>Nerve supply: spinal segments T9, T10 </li></ul><ul><li>Rotation: </li></ul><ul><ul><li>On axis of SMA 270 ° anticlockwise </li></ul></ul><ul><ul><li>6- 10/40 gestation </li></ul></ul><ul><ul><li>Via physiological hernia </li></ul></ul><ul><li>Retroperitoneal: duodenum, ascending colon </li></ul>
    44. 45. Midgut rotation 6-10/40 Rotation occurs around the axis of the SMA on a single mesentery, “the mesentery”
    45. 46. Hindgut <ul><li>Mid-transverse colon- upper anal canal </li></ul><ul><li>Artery: IMA </li></ul><ul><li>Nerve supply: T11 -S4 </li></ul><ul><li>Mesenteries: </li></ul><ul><ul><li>transverse mesocolon (shared with midgut) </li></ul></ul><ul><ul><li>sigmoid mesocolon </li></ul></ul><ul><li>Rotation: swings to left vertical axis of dorsal mesentery </li></ul><ul><li>Retroperitoneal: L colon (line of Toldt), rectum </li></ul>
    46. 47. Peritoneal Attachments Bare area of liver Lesser sac Epiploic foramen Greater sac
    47. 48. Abdominal Viscera <ul><li>Next time! </li></ul>
    48. 49. Any Questions? ?