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Abdomen, Pelvis and Lecture 1 Perineum 1 10/10/2022 Surgical Societyor Anatomy Series Olivia WingyStructure of Layers of the abdominal cavity 3 mins the session Divisions of the wall 3 mins Anterior abdominal wall muscles 12 mins Any questions you have Posterior abdominal wall muscles 12 mins through out please put in the chat and I’ll either leave them Vessels, nerves & lymph of the abdominal wallins until the relevant section or answer at the end. Inguinal canal 9 mins Practice Questions 6 mins Surgical SocietyJunior Anatomy SeriesDivisions of the wall L3 L5 Surgical Societynior Anatomy SeriesLayers of the wall • What is the order of the sheet muscles from out to in? 1. External oblique 2. Internal oblique 3. Transversus abdominis. • They assist in the flexion of the trunk and guarding the viscera contained without the abdomen and pelvis. • When identifying the different muscles, and their respective functions, it is useful to look at the directions the fibers are travelling in. Surgical Societyunior Anatomy SeriesLayers of the wall The Scarpa’s fascia blends with the linea alba Camper’s fascia Scarpa’s fascia Superficial fatty layer Deeper membranous layer Contains variable amounts Thin and little or no fat of fat Continuous over inguinal Continues into the thigh but ligament then fuses with the fascia lata (of the thigh) just below the inguinal ligament Surgical Society Junior Anatomy SeriesExternal oblique • The external oblique fibers travels inferiorly and medially. • Becomes an aponeurosis medially (which makes up part of the linea alba). • The lower border of the external oblique aponeurosis forms the inguinal ligament on each side. Originates: ribs 5-12 Insert: iliac crest and pubic tubercle Function : contralateral rotation of the torso Innervation: thoracoabdominal nerves (T7-T11) and subcostal KEY POINT An aponeurosis is a flat sheet nerve (T12) or ribbon of tendon-like material that anchors a muscle or connects it with the part that the muscle moves. Surgical Society Junior Anatomy SeriesInternal oblique • The internal oblique fibers travels superiorly and medially (perpendicular to the fibers of external oblique). • This muscle is smaller and thinner than the external oblique. • Also becomes an aponeurosis medially (which makes up part of the linea alba). Originates: inguinal ligament, iliac crest and lumbodorsal fascia Insert: ribs 10-12 Function: bilateral contraction compresses the abdomen, unilateral contraction ipsilaterally rotates the torso Innervation: thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus Surgical Society Junior Anatomy SeriesTransversus abdominis • The transversus oblique fibers travels transversely. • Also becomes an aponeurosis medially (which makes up part of the linea alba). • Beneath the muscle is the transversalis fascia which is well-formed and worth noting. Originate: inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia Insert: conjoint tendon, xiphoid process, linea alba and the pubic crest Function: compression of abdominal contents (most important muscle in raising intra-abdominal pressure!) Innervatio: thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus Surgical SocietyJunior Anatomy SeriesRectus abdominis • It is split into two by the linea alba. The lateral borders of the muscles create a surface marking known as the linea semilunaris. • At several places, the muscle is intersected by fibrous strips, known as tendinous intersections. The tendinous intersections and the linea alba give rise to the ‘six pack’ seen in individuals with a well -developed rectus abdominis. Originates: crest of the pubis Insert: xiphoid process of the sternum and the costal cartilage of ribs 5-7 Function: assisting the flat muscles in compressing the abdominal viscera, the rectus abdominis, it also stabilizes the pelvis during walking, and depresses the ribs Innervation: thoracoabdominal nerves (T7-T11) Surgical Society Junior Anatomy SeriesRectus sheath Surgical Societyr Anatomy SeriesSurface anatomy Pyramidalis muscle The pyramidalis muscle is a small triangular muscle, found superficially to the rectus abdominis. It acts to tense the linea alba. Surgical SocietyJunior Anatomy SeriesPsoas major (and minor) • The psoas major is located lateral to the lumbar vertebrae and runs deep to the inguinal ligament • The psoas minor is only present in 60% of the population • The psoas minor also aids in flexion of the vertebral column • It attaches to a ridge on the pectineal line (superior ramus of the pubic bone) Originates: transverse processes and vertebral bodies of T12 – L5 Insert: lesser trochanter of the femur Function: flexion of the thigh at the hip and lateral flexion of the vertebral column Innervatio: anterior rami of L1 – L3 nerves Surgical SocietyJunior Anatomy SeriesPsoas major (and minor) • The psoas major is located lateral to the lumbar vertebrae and runs deep to the inguinal ligament • The psoas minor is only present in 60% of the population • The psoas minor also aids in flexion of the vertebral column • It attaches to a ridge on the pectineal line (superior ramus of the pubic bone) Originates: transverse processes and vertebral bodies of T12 – L5 Insert: lesser trochanter of the femur Function: flexion of the thigh at the hip and lateral flexion of the vertebral column Innervatio: anterior rami of L1 – L3 nerves (L1 only for psoas minor) Surgical SocietyJunior Anatomy SeriesIliacus • The iliacus muscle is fan shaped • This muscle fuses with the psoas major muscle to form the iliopsoas Originates: surface of the iliac fossa and anterior inferior iliac spine Insert: lesser trochanter of the femur (as it merges with the psoas major muscle) Function : flexion and lateral rotation of the thigh at the hip joint Innervation: femoral nerve (L2 – L4). Surgical Society Junior Anatomy SeriesQuadratus lumborum • This muscle is irregularly quadrilateral in shape Originate: iliac crest and iliolumbar ligament Insert: transverse processes of L1 – L4 and the inferior border of the 12th rib Function: extension and lateral flexion of the vertebral column (it also fixes the 12th rib during inspiration so that energy in contracting the diaphragm is not wasted) Innervatio: femoral nerve (L2 – L4). Surgical SocietyJunior Anatomy SeriesPosterior wall Surgical Societyor Anatomy SeriesArteries of the wall • Segmental arteries: • Intercostals 7 -11 • Subcostal artery • Lumbar arteries • Longitudinal arteries: • Superior epigastric -> from internal thoracic • Inferior epigastric -> from external iliac • (these anastomosis in the region of the umbilicus) Surgical SocietyJunior Anatomy SeriesVeins of the wall • Segmental veins: st nd • The subcostal vein joins with the 1 and 2 lumbar veins to form the ascending lumbar vein that drains into the azygous system • The 3rdand 4 lumbar veins directly into the IVC • Longitudinal veins: • Superior epigastric -> drains into internal thoracic • Inferior epigastric -> drains into external iliac Surgical Society Junior Anatomy SeriesLymph of the wall • Above the umbilicus lymph drains into the axillary nodes. • Below the umbilicus lymph drains to the superficial inguinal nodes. • The posterior wall lymph drains to the lumbar lymph nodes. Surgical Societynior Anatomy SeriesNerves of the wall • The neurovascular branches supplying the abdominal wall travel between the internal oblique and the transversus abdominis muscles. Surgical Societynior Anatomy SeriesNerves of the wall Surgical SocietyAnatomy SeriesNerves of the wall Surgical SocietyAnatomy SeriesInguinal canal • The contents of the canal: • Genitofemoral nerve in women • Spermatic cord in men • Round ligament of the uterus in women • And the Ilio -inguinal nerve passes through part of the canal. Surgical Societyunior Anatomy SeriesWalls of the Inguinal canal • Anterior wall: external oblique aponeurosis • Floor: inguinal ligament • (becoming the conjoint tendonnal oblique medially) • Posterior wall: transversalis fascia Surgical SocietyJunior Anatomy SeriesInguinal canal rings • The deep inguinal ring is halfway between the anterior superior iliac spine and the pubic symphysis. • It is a deficiency in the transversalis fascia. • The superficial inguinal ring is superior to the pubic tubercle. Surgical Societyunior Anatomy Series SBA Questions PRACTICE QUESTION PRACTICE QUESTION PRACTICE QUESTION 1. What muscle is the most 3. What statement below is true 5. Between what 2 muscles do the important for raising intra- about Scarpa’s fascia? neurovascular branches supplying abdominal pressure? • Continuous over inguinal the abdominal wall travel? • External and internal oblique • Rectus abdominis ligament • External oblique • Contains lots of fat • Rectus abdominis and internal • Internal oblique • Superficial oblique • Transversus abdominis • Makes up the conjoint tendon • Internal oblique and transversus abdominis • Psoas major • Deep membranous layer • Rectus abdominis and transversus abdominis 2. What is the posterior wall of the 4. What does the superior inguinal canal? epigastric artery arise from? 6. Below the arcuate line which • Internal oblique structure is posterior to the rectus • External iliac artery abdominis muscle? • Inguinal ligament • Internal iliac artery • Conjoint tendon • External thoracic artery • ½ the internal oblique aponeurosis • External oblique • Transversalifascia • Internal thoracic artery • Transversalis fascia • Subcostal artery • Transversus abdominis aponeurosis Surgical Society | Junior Anatomy Series SBA Questions PRACTICE QUESTION PRACTICE QUESTION PRACTICE QUESTION 1. What muscle is the most 3. What statement below is true 5. Between what 2 muscles do the important for raising intra- about Scarpa’s fascia? neurovascular branches supplying abdominal pressure? • Continuous over inguinal the abdominal wall travel? • External and internal oblique • Rectus abdominis ligament • External oblique • Contains lots of fat • Rectus abdominis and internal • Internal oblique • Superficial oblique • Transversus abdominis • Makes up the conjoint tendon • Internal oblique and transversus abdominis • Psoas major •Deep membranous layer • Rectus abdominis and transversus abdominis 2. What is the posterior wall of the 4. What does the superior inguinal canal? epigastric artery arise from? 6. Below the arcuate line which • Internal oblique structure is posterior to the rectus • External iliac artery abdominis muscle? • Inguinal ligament • Internal iliac artery • Conjoint tendon • External thoracic artery • ½ the internal oblique aponeurosis • External oblique • Transversalis fascia • Internal thoracic artery • Transversalis fascia • Subcostal artery • Transversus abdominis aponeurosis Surgical Society | Junior Anatomy Series Extra Spotter Questions Cut edge of anterior layer of rectus sheath Superior epigastric artery Rectus abdominis muscle Tendinous intersection External abdominal oblique muscle Transversus abdominis muscle Posterior layer of rectus sheath Inferior epigastric artery Inguinal ligament and il-o inguinal nerve Surgical Society| Junior Anatomy Series Extra Spotter Questions Cut edge of anterior layer of rectus sheath Superior epigastric artery Rectus abdominis muscle Tendinous intersection External abdominal oblique muscle Transversus abdominis muscle Posterior layer of rectus sheath Inferior epigastric artery Inguinal ligament and il-o inguinal nerve Surgical Society| Junior Anatomy SeriesSurgical Society | Junior Anatomy Series OLIVIA WING JAS LEADS Contact olivia.wing19@imperial.ac.ukPhase 1a: Sree Kanakala (sk1821) Phase 1b: Ananya Jain (aj620) CPA Lead: Mohamad Abou-Eid (ma2219) Please fill out the following feedback form in Feedback order to receive a copy of the slides on Medall along with bonus SBAs to aid your revision! Form We hope you enjoyed this lecture! See you on TuesdayOctober 2022 for our next lecture on Abdomen, Pelvis and Perineum 2. dback/anonymous?organisation=im/fee perial-college-surgical- f0533ba017yword=8812a7e57900c8