Anterior Abdominal Wall and Inguinal Canal Lecture 1 PDF

Anterior Abdominal Wall, Inguinal Canal & Hernias Dr. Bip Choudhury  Intended Learning Outcomes By the end of the lecture, students should be able to describe the:  nature of the divisions of the anterior abdominal wall into 9 anatomical regions  list...

Anterior Abdominal Wall, Inguinal Canal & Hernias Dr. Bip Choudhury  Intended Learning Outcomes By the end of the lecture, students should be able to describe the:  nature of the divisions of the anterior abdominal wall into 9 anatomical regions  list the constituents of the anterior abdominal wall and its neurovascular supply and lymph drainage  explain the importance of knowing the anatomical arrangement of the rectus sheath  apply knowledge of the structure of the inguinal canal to describe hernia formation  Importance of anterior abdominal wall Function is for protection, aids flexibility and allows forced expiration. Think about the following clinical applications of anatomical knowledge: - laparotomy - paracentesis - appendectomy -liposuction  Surface Landmarks xiphoid process costal margin anterior superior iliac spine inguinal ligament pubic tubercle  Abdominal Regions midclavicular lines subcostal line intertubercular line  Abdominal Regions 1 = right hypochondrium 2 = epigastrium 3 = left hypochondrium 4 = right lumbar/flank/loin 1 2 3 5 = umbilicus 6 = left flank/lumbar/loin 4 5 6 7 = right iliac fossa 8= 7 8 9 suprapubic/hypogastium 9 = left iliac fossa  Layers of the anterior abdominal wall deep muscl es fat fat ski parietal n peritoneum transversalis fascia Sagittal section through anterior abdominal wall  Muscles of anterior abdominal wall Rectus abdominis Pyramidalis Trilaminar Muscles External Transvers Oblique Internal us (shown) Oblique Abdomini s External Oblique xiphoid process lower 8 ribs anterio r half pubic iliac crest & crest tubercle  Internal Oblique xiphoid process ribs 10- 12 Line a lateral 2/3 alba inguinal ligament anterior 2/3 iliac crest Transversus Abdominis xiphoid process lower 6 costal cartilage s Line a alba lateral 2/3 inguinal ligament anterior 2/3 pubic iliac crest symphy sis Muscle Origin Insertion Nerve Supply Action External lower 8 ribs xiphoid T6-T12, Flexion & oblique process, pubic iliohypogastri rotation of crest, pubic c& trunk, tubercle, ilioinguinal increases anterior half nerves intra iliac crest abdominal pressure Internal anterior ribs 10-12, T6-T12, Flexion & oblique 2/3rds iliac xiphoid iliohypogastri rotation of crest, lateral process, linea c& trunk, 2/3rds alba and ilioinguinal increases inguinal pubic intra ligament symphasis abdominal pressure Transversus lower 6 costal xiphoid T6-T12, Increases abdominis cartilages, process, linea iliohypogastri intra anterior alba, pubic c& abdominal 2/3rds iliac symphasis ilioinguinal pressure crest, lateral 2/3rds inguinal ligament  Internal Oblique External Transversus Oblique Abdominis Girdle formation EO aponeuroses IO aponeuroses TA aponeuroses  Inguinal Ligament externa l oblique Inguinal ligament (between ASIS & pubic tubercle)  Rectus Abdominis xiphoid Rectus Abdominis process muscle has tendinous intersections.(the 5th-7th costal muscle is bound cartilages down, attached to structures beneath it, usually the fascia) Linea alba Pubic symphasis & crest  Particulars Muscle Origin Insertion Nerve Action Supply Rectus Pubic 5th-7th costal T6-T12 Compresses Abdominis symphasis & cartilages & abdominal pubic crest xiphoid contents, flexes process vertebral column, accessory muscle of respiration Pyramidalis Front of Linea alba T12 Tenses linea pubis and alba pubic symphasis  The Rectus Sheath M S L D skin E E O O IO IO RA RA TA TA transversalis fascia Above ASIS skin E E O O IO IO RA RA TA TA transversalis Below ASIS fascia EO external oblique IO internal oblique TA transversus abdominis RA rectus abdominis  Rectus Sheath superior epigastric IO artery E TA O ski transversalis n fascia abdominis Rectus arcuate line inferior epigastric Sagittal section through anterior abdominal artery wall  Vascular Supply Superior epigastric artery Lateral thoracic vein Intercostal arteries Lumbar veins Lumbar arteries Deep circumflex iliac arteries Superficial epigastric vein Inferior epigastric artery  Nerve supply & lymph drainage T7 Anterior axillary T8 lymph nodes T9 Lower 6 thoracic and 1st lumbar nerve Superficial inguinal lymph nodes Superficial Inguinal Ring Located above and medial to pubic tubercle externa l oblique = superficial inguinal ring (SIR)  Deep Inguinal Ring transversalis fascia = deep inguinal ring (DIR) Sagittal section through anterior abdominal wall  Inguinal Canal transversalis RA fascia TA IO DI R dee EO p Ing uin a l ca na l SI R Anterior view of anterior abdominal wall  Inguinal Canal a natural opening is parallel to/ superior to the inguinal ligament extends from the DIR to the SIR (3-5cm long) Contents Males : spermatic cord and ilioinguinal nerve Females : round ligament of the uterus and ilioinguinal nerve  Inguinal Canal DIR roo an t f =f erio orm r ed wa by l= l f fibr orm es ed o f IO by and E late O ap r a ll one TA yb u y IO rosis fibr rein es for ced SIR Anterior view of inguinal canal  Inguinal Canal Conjoint tendon DIR pos formed from lower t floowal erior fibres of IO and TA r =l f =t orm ran liga e co s me d bynjoin versa nt s ing t te l u i n nd i s f a s al a o n cia nd a nd l ac una r Lacunar ligament SIR formed from fibres of inguinal ligament and fascia lata Anterior view of inguinal canal  Hernias Definition The protrusion of part of the abdominal contents beyond the normal confines of the abdominal wall (Snell). sac content coverin s gs  Hernias Reducible Strangulat Epigastric ed hernia Umbilical hernia Femoral Inguinal hernia hernia  REVIE Paracentesis W Through which layers of the abdominal wall must the needle pass in order to reach the peritoneal cavity?  REVIE Incisions W What structures are cut in a midline incision, to gain access to the abdominal cavity? This is a McBurney’s incision. How might you access intraabdominal structures without damaging the trilaminar muscles?  Extra Reading Chapter 5, The Abdomen Moore’s Clinically Orientated Anatomy Page 408 onwards Or the equivalent in your favourite anatomy textbook Le Saint-Grant, A, Taylor, A, Varsou, O, Grant, C, Cezayirli, E & Bowness, J (2021) Arterial anatomy of the anterior abdominal wall: Ultrasound evaluation as a real-time guide to percutaneous instrumentation. Clinical Anatomy 34:5-10