Anterior Abdominal Wall Anatomy PDF

ANTERIOR ABDOMINAL WALL AND SURFACE ANATOMY Class Year 2, Semester 1 Lecturer DR. VIJAYALAKSHMI S B Department of Anatomy Email id: [email protected] Date 8th Sept’ 2024 Learning Outcomes Describe the anterior abdominal wall Describe the anato...

ANTERIOR ABDOMINAL WALL AND SURFACE ANATOMY Class Year 2, Semester 1 Lecturer DR. VIJAYALAKSHMI S B Department of Anatomy Email id: [email protected] Date 8th Sept’ 2024 Learning Outcomes Describe the anterior abdominal wall Describe the anatomy of the inguinal canal Demonstrate an understanding of how inguinal hernias develop & explain the anatomy and clinical findings Describe the layers and contents of the scrotum Explain the embryology of testicular descent, and why this is clinically relevant  The Abdomen – General structure and function Roughly a cylindrical chamber Inferior thoracic aperture forms superior opening – closed by the diaphragm Inferiorly – continuous with the pelvic wall at the pelvic inlet Function:  Houses and protects major viscera  Breathing  Changes in intraabdominal pressure  The Abdomen wall Skeletal elements:  5 lumbar vertebrae and the intervening IV discs  Pelvic bones  Costal margin, ribs 11 & 12 and xiphoid process Muscles:  Lateral to vertebral column - Quadratus lumborum, psoas major and iliacus  Lateral of the abdominal wall – transverse abdominis, internal oblique and external oblique  Anterior – Rectus abdominis Review – Important Bony landmarks  Review – Important Bony landmarks Iliac crest L3 Iliac tubercle L4 Anterior superior iliac spine Sacrum Anterior inferior iliac spine Ischial spine Pubic Pubic tubercle symphysis Surface Anatomy – Topographic divisions Used to describe the location of abdominal organs and pain associated with abdominal problems Two patterns most often used Four-quadrant pattern Nine-region pattern  Lumbar Vertebrae Transpyloric Plane – L1 Umbilicus – L3/4 intervertebral disc Transtubercular – L4-5  Transpyloric Plane – L1 Midway between jugular notch and pubic symphysis, (or Xiphoid and Umbilicus) at 9th costal cartilage – Pylorus of stomach – Body of Pancreas – Hila of Kidneys  Layers of the abdominal wall Skin Superficial fascia (or subcutaneous tissue) Muscles and associated fascia Parietal peritoneum  Superficial Fascia Consists of fatty connective tissue. The composition of this layer depends on its location: Two layers:  the fatty superficial layer (Camper’s fascia)  The membranous deep layer (Scarpa’s fascia) Superficial vessels and nerves run between these two layers of fascia  Muscles of the abdominal wall 5 muscles in the abdominal wall (on each side) Can be divided into two groups: 3 Flat muscles - situated laterally 1. External oblique 2. Internal oblique 3. Transverse abdominis 2 Vertical muscles – situated near the mid-line 1. Rectus abdominis 2. Pyramidalis  Muscles of the abdomen: The Flat muscles 3 flat muscles; 1. External oblique 2. Internal oblique 3. Transversus abdominis Located laterally, in the abdominal wall, stacked upon one another As they pass anteriorly, they continue as aponeurosis.​ Act to flex, laterally flex and rotate the trunk Fibres run in differing directions and cross each other – strengthening the abdominal wall and decreasing the risk of herniation  Muscles of the abdomen: The Flat muscles External Oblique – most superficial Origin Ribs 5-12 Insertion Iliac crest and linea alba Fibers in the inferomedial direction Innervation Thoracoabdominal T7-11 and subcostal nerve T12 Action Compresses abdomen contents, Both muscles flex trunk​ Each muscle bends trunk to same side, turning anterior part of the abdomen to opposite side​ The lower border folds on itself to form the inguinal ligament​ Associated ligaments Inguinal ligament - rolled-in free lower border of external oblique aponeurosis on each side  Passes between anterior superior iliac spine (ASIS) and pubic tubercle  Plays an important role in the formation of the inguinal canal Associated ligaments Lacunar ligament  Crescent-shaped extension of fibres at the medial end of the inguinal ligament  Attaches to the pecten pubis Pectineal (Cooper’s) Ligament  Extended fibres along the pecten pubis of the pelvic brim v  Inguinal ligament The midpoint of the inguinal ligament: Anterior superior iliac spine  Halfway along the inguinal ligament  Surface marking of the deep inguinal ring and femoral nerve The mid-inguinal point:  Halfway between the ASIS and the superior border of the pubic symphysis. Femoral  Surface marking for the femoral artery nerve Pubic symphysis Femoral artery Pubic tubercle Inguinal ligament Acknowledgement: Dr Sara Sulaiman  Muscles of the abdomen: The Flat muscles Internal Oblique – deep to the external oblique Origin Lateral 2/3 inguinal ligament, iliac crest and thoracolumbar fascia Insertion Linea alba, pectineal line, pubic crest, inferior border of ribs 9-12 Fibers passing in a superomedial direction Innervation Thoracoabdominal T7-11 and subcostal nerve T12, iliohypogastric (L1) and ilioinguinal (L1) Action Compresses abdomen contents, Both muscles flex the trunk​ Each muscle bends the trunk and turns anterior part of the abdomen to same side​  Muscles of the abdomen: The Flat muscles Transversus Abdominis - Deep to the internal oblique Origin Iliac crest, lateral 1/3 inguinal ligament, thoracolumbar fascia and ribs 7-12 Insertion Linea alba, pubic crest and pectineal line Fibers pass transversely​ Innervation Thoracoabdominal T7-11 and subcostal nerve T12, iliohypogastric (L1) and ilioinguinal (L1) Action Compresses abdomen contents  Muscles of the abdomen: Vertical muscles Rectus Abdominis Origin Pubic crest, tubercle & symphysis Insertion Costal cartilage of ribs 5-7, xiphoid process Innervation Thoracoabdominal T7-11, subcostal T12 Action Compresses abdomen contents, flex vertebral column, tense abdominal wall Pyramidalis Origin Pubic symphysis and pubic bone Insertion Linea alba Innervation Subcostal nerve (T12) Action Tenses the linea alba  Gym anatomy Which muscles are activated when you do curl-ups/sit- ups? Which muscles are activated when you do sit-ups with a rotation?  The rectus abdominis muscles are engaged during flexion of the torso with an assist from the abdominal obliques.  If you are doing full sit-ups, then the hip flexors (The rectus femoris and iliopsoas muscles ) are also engaged.  The abdominal oblique muscles are more active when a rotation to one side is added to the flexion. For example, When twisting to the right, the left external abdominal oblique and right internal abdominal oblique will be activated. The opposite combination occurs when twisting to the left. Images from: https://www.wikihow.com Acknowledgement: Dr Sara Sulaiman  Rectus Sheath Formed by aponeuroses of the 3 flat muscles Anterior wall by aponeuroses of external oblique and half of internal oblique Posterior wall by aponeuroses of half internal oblique and of the transversus abdominus Upper Abdomen – Above the arcuate line midway between the umbilicus and pubic symphysis, all the aponeuroses move to the anterior wall of the rectus sheath – Arcuate line (marking this point of transition) Lower Abdomen - Below the arcuate line  Nerve Supply Motor and sensory Nerves course between the internal oblique and transversus abdominis muscles​ They innervate the muscles and terminate by supplying the skin​  Dermatomes Skin on xiphoid process (T7) Skin around the umbilicus (T10) Skin on the inguinal ligament (L1) *Clinical application - Umbilicus T10 Referred pain from appendix, testis Acknowledgement: Dr Sara Sulaiman  Blood supply Deep supply – Superior epigastric vessel (from internal thoracic artery) – Inferior epigastric vessels and deep circumflex (from external iliac) Musculophrenic a. – 10th and 11th intercostal arteries and subcostal artery (from the Superior epigastric a. abdominal aorta) Superficial supply Superficial epigastric a. – Musculophrenic artery (from internal thoracic artery) – Superficial epigastric and superficial circumflex (from femoral artery) Inferior epigastric a. Superficial circumflex a. Acknowledgement: Dr Sara Sulaiman  Inguinal canal Deep inguinal ring Defect in transversalis fascia Transversalis fascia Located at a point midway between the About 4 cm long ASIS and the pubic symphysis Above the inguinal ligament Lateral to the inferior epigastric vessels Begins: deep inguinal ring Ends: superficial inguinal ring Transversus abdominis Superficial inguinal ring Internal oblique Triangular opening in the aponeurosis of the external External oblique oblique. Found superior to the pubic tubercle. Contents: Male: genital branch of the genitofemoral nerve, the spermatic cord Females: genital branch of the genitofemoral nerve, round ligament of the uterus. Ilio–inguinal nerve passes through part of the canal (both sexes). Acknowledgement: Dr Sara Sulaiman  Inguinal canal Transversalis fascia Deep inguinal ring Floor  Inguinal ligament  Medially lacunar ligament Transversus abdominis Anterior wall: Internal oblique  Aponeurosis of external oblique External oblique  Laterally by internal oblique Roof:  Arching fibers of transversus abdominis and internal oblique Posterior wall:  Transversalis fascia  Medially by conjoint tendon superficial inguinal ring Acknowledgement: Dr Sara Sulaiman  Spermatic cord 3 Layers Internal spermatic fascia (transversalis fascia) Cremasteric layer (internal oblique) External spermatic fascia (external oblique) 3 Arteries Testicular – from Aorta at L2 Cremasteric – from Inferior Epigastric Artery of Vas – from Superior Vesical 3 Nerves Nerve to cremaster – from Genitofemoral Sympathetic – deep pain sensation (Ilioinguinal – separate) 3 other things Vas deferens Pampiniform plexus of veins – asymmetric, varicosities Lymphatics to para-aortic nodes at L2  Hernia -Definition Abnormal protrusion of an organ, tissue or structure in part or in whole through a defect in the cavity that normally contains it Groin Hernias  Common: 75% of hernias  25% of males and 2% of females have inguinal hernias in their lifetime Inguinal hernia  Neck is above & medial to the pubic tubercle Femoral hernia  Neck is below and lateral to the pubic tubercle  Femoral hernia Indirect inguinal hernia Acknowledgement: Dr Sara Sulaiman Inguinal Hernia - Indirect  Inguinal canal  Congenital  Through the deep ring, along the inguinal canal, superficial ring to the scrotum  If reduced, can be controlled at deep ring  The abdominal content passes through the deep ring thus, the bulge occurs lateral to the epigastric vessels​  Inguinal hernia - Direct  Through weakness in transversalis fascia & superficial ring  the bulge occurs medial to the epigastric vessels (Hesselbach’s triangle).  Acquired  Heavy lifting  Constipation  Sports e.g. Rugby https://x.com/ChaseSurgical Descent of Testes  Scrotum anatomy Processus vaginalis is an extension/outpouching that projects into the labioscrotal swelling. It usually disappears except the distal part. As the testis moves into the scrotum, it acquires layers from the abdominal wall. Corresponding layers of the Layers of the abdominal wall testis and spermatic cord 1. Skin 1. Skin 2. Superficial fascia 2. Colle’s fascia and dartos muscle (camper and Scarpa) 3. External spermatic fascia 3. External oblique 4. Cremasteric fascia and muscle 4. Internal oblique 5. Does not contribute 5. Transversus abdominis 6. Internal spermatic fascia 6. Transversalis fascia 7. Extraperitoneal fat 7. Extraperitoneal fat 8. Tunica vaginalis 8. Parietal peritoneum Acknowledgement: Dr Sara Sulaiman  Lymphatic drainage Abdominal wall superficial lymphatics: Superficial  Above the umbilicus: drain to the axillary nodes lymphatics  Below the umbilicus: drain to the superficial inguinal of the nodes. abdomen Drain to Abdominal wall deep lymphatics follow the deep axillary nodes arteries:  To parasternal nodes along the internal thoracic artery, Above the umbilicus Below the umbilicus  To lumbar nodes along the abdominal aorta  To external iliac nodes along the external iliac artery Drain to superficial inguinal nodes Testis drain to para-aortic nodes at L1 Skin of the Scrotum drains into inguinal nodes. Acknowledgement: Dr Sara Sulaiman Thank you for your attention Questions?