Gross Anatomy of the Anterior Abdominal Wall Part 1 PDF

Module 08: Gastrointestinal System and Nutrition 1 Gross Anatomy of the Anterior Abdominal Wall Part 1 Michele Rivera Nuez, MD FPCS FPAPRAS | January 15, 2024 | Asynchronous TABLE OF CONTENTS Learning Objectives 1 V. Anterolateral Abdominal 6 I. S...

Module 08: Gastrointestinal System and Nutrition 1 Gross Anatomy of the Anterior Abdominal Wall Part 1 Michele Rivera Nuez, MD FPCS FPAPRAS | January 15, 2024 | Asynchronous TABLE OF CONTENTS Learning Objectives 1 V. Anterolateral Abdominal 6 I. Surface Anatomy 1 Wall Layers A. Boundaries 1 A. Multiple Layers 7 B. Surface Landmarks 1 B. Skin 7 II. Abdominal Planes and 1 C. Subcutaneous Tissue 7 Anatomical Correlates VI. Summary & Key Points 9 A. Horizontal Planes 2 Review Questions 9 B. Vertical Planes 3 Rationale 9 III. Abdominal Regions and 4 References 9 Quadrants A. Quadrants 4 B. Regions 5 C. Practical Applications 5 Figure 1. Male Trunk, Anterior View IV. Anterolateral Abdominal 5 Wall Boundaries B. SURFACE LANDMARKS A. Subdivisions 5 Few anatomic landmarks B. Boundaries 6 The flat plane is broken up by: C. Bones 6 – Costal margins LEARNING OBJECTIVES – Anterior superior iliac spines 1. Describe the bony and cartilaginous landmarks visible or – Umbilicus palpable on abdominal examination and explain their clinical significance 2. Describe the different abdominal planes and its anatomical correlates 3. Describe the descriptive regions and quadrants of the abdomen 4. Describe the surface projections of the abdominal organs onto the four quadrants and nine descriptive regions of the abdomen 5. Describe the surface projections of the liver, gallbladder, pancreas, spleen, kidneys, stomach, duodenum, jejunum, ileum, caecum, appendix, ascending, transverse, descending, and Figure 2. Male and Female Thorax (09.01a, 2026) sigmoid parts of the colon Surface landmarks that may be used when doing physical 6. Understand the layers of the anterior abdominal wall examination: 7. Describe the anatomy, innervation, and functions of the muscles – Xiphisternal joint of the anterior abdominal wall – Apex of the infrasternal angle 8. Describe the different aponeuroses of the anterior abdominal – Xiphoid process wall – Iliac crest 9. Identify blood supply and lymphatic of anterior abdominal wall – Anterior superior iliac spine (ASIS) 10. Identify the umbilical folds/ligaments and their relative structures – Linea alba I. SURFACE ANATOMY ▪ At the midline Surface Anatomy ▪ Other names: Median line or Median furrow – Study of anatomical landmarks on the exterior of the human – Semilunar line or linea semilunaris body ▪ At the side of the linea alba – Descriptive science dealing with anatomical features that can ▪ Lateral border of the rectus muscle be studied by sight and palpating the human body without ▪ Can be appreciated on lean and muscular individuals, dissecting it especially when abdominal wall is contracted Abdomen – Umbilicus – Part of the trunk between the thorax (upper) and pelvis (lower) ▪ Anywhere between L3-L5 – Flexible, dynamic container housing most of the organs of the − Usually at the level of L3 vertebra alimentary system and part of the urogenital system Inguinal ligament and groove – Can be palpated at the groin area A. BOUNDARIES II. ABDOMINAL PLANES AND ANATOMICAL CORRELATES Anterolateral: Musculoaponeurotic wall The abdomen has been mapped out by arbitrary lines or planes Superior: Diaphragm for clinical and descriptive purposes Inferior: Pelvis – Similar to how the thorax is also mapped out – Includes both vertical and horizontal planes Horizontal planes: – Subcostal plane – Transpyloric plane – Transumbilical plane – Transtubercular plane TG6 | Advincula, Aurellano, Chiew, Dait, Esguerra, Gonzalvo, Lopez, Lurzano, Mesa, Migraso, Reyes YL5 08.01a 1 of 9 CG15 | Angala, Castillo, Estiva, Gelera, Go, Licup, Macababbad, Melo, Pornillos, Reyes  – Interspinous plane – Duodeno-jejunal flexure Vertical planes: – Root of the transverse mesocolon – Midclavicular plane – Hepatic flexure of the colon – Median plane ▪ Found underneath the liver – Paramedian line – Splenic flexure of the colon – Mid-poupart line ▪ Found underneath the spleen A. HORIZONTAL PLANES – Fundus of the gallbladder Subcostal Plane Figure 6. Anatomical Correlates of Transpyloric Plane More Anatomical Correlates: Figure 3. Subcostal Plane – L1 vertebral body Imaginary horizontal line at the lowest subcostal arch – Hila of the kidneys – Formed by the 10th costal cartilage on both sides – Hilum of the spleen Extends through the upper part of the 3rd lumbar vertebra ▪ Spleen not seen in Figure 5 An inch or more above the umbilicus – 9th costal cartilage Anatomical Correlates: – Origin of Superior Mesenteric Artery (SMA) – Origin/root of Inferior Mesenteric Artery – Splenic vein joins Superior Mesenteric Vein (SMV) to form – At the level of the transverse colon portal vein – Upper limit of the transverse (3rd) part of the duodenum – Cisterna chyli – Lower ends of the kidney Transumbilical Plane – Lower limit of the liver Transpyloric Plane Figure 4. Transpyloric Plane Figure 7. Transumbilical Plane Imaginary horizontal line midway between superior border of A transverse plane passing through the umbilicus manubrium (suprasternal notch) and pubic symphysis Located at the level of L3/L4 vertebral junction or IV disc – Also known as Addison’s Plane – Posterior projection Transtubercular Line Extends the area of the tubercle of the iliac crest at 2.5 cm from the anterior superior iliac spine Figure 5. Anatomical Correlates of Transpyloric Plane Anatomical Correlates: – Pylorus of the stomach – D1 part of the duodenum Figure 8. Ileocecal Valve within the plane of the Transtubercular Line YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 2 of 9  Figure 9. Transtubercular Line spanning the level of L5 Figure 12. Midclavicular Line Clinical Correlations: Midclavicular Line → Useful for evaluating an enlarged liver and for locating the gallbladder → Which is at the cross point of the midclavicular line and the transpyloric plane Figure 10. Base of Appendix in the Transtubercular Line Anatomical Correlates – Corresponds to the body of L5 vertebrae – Passing through or just above the Ileocecal valve – Marks the confluence of the common iliac veins at the right side of L5 – Marks the formation of inferior vena cava – Base of appendix ▪ Indicated on the surface of the abdomen by a point 2 cm below the intersection between the transtubercular plane and the right midclavicular line (right lateral plane) Interspinous Plane Line between the anterior superior iliac spine of the iliac bone Figure 13. Liver and Gallbladder in the Midclavicular Line passing through L5 Median Plane Also known as the Midsagittal plane Bisects the body vertically through the midline marked by the navel – Dividing the body exactly in left and right side Figure 11. Interspinous Plane B. VERTICAL PLANES Midclavicular Line Sagittal line Imaginary vertical line parallel to the long axis of the body Figure 14. Median Plane Passes through the midpoint of the clavicle on the ventral Paramedian Line surface of the body – Between the tip of the acromion and suprasternal notch Imaginary line that defines the lateral border of the 2 rectus abdominis muscle Mid-Poupart Line – Right and Left vertical line – Imaginary vertical line drawn from the point midway between the anterior superior iliac spine and the pubic symphysis on each side YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 3 of 9  III. ABDOMINAL REGIONS AND QUADRANTS There are nine (9) regions and four (4) quadrants Figure 15. Paramedian Plane Clinical Correlations: Mid-Poupart Line → Right Mid-Poupart Line Figure 18. Regions and Quadrants of the Abdomen A. QUADRANTS Defined by the horizontal transumbilical plane and vertical median plane Four (4) quadrants: – Right Upper Quadrant (RUQ) – Right Lower Quadrant (RLQ) – Left Upper Quadrant (LUQ) – Left Lower Quadrant (LLQ) Figure 16. Right Mid-Poupart Line Table 1. Major Organs found in the Quadrants a. Ileocecal valve Upper Quadrants ○ Situated where the mid-poupart line crosses the intertubercular line Left Right b. McBurney’s Point Liver Liver ○ Located 1 inch below the intersection of the Stomach Left Adrenal Gland mid-poupart line and intertubercular line Stomach Gallbladder ○ Vermiform appendix Duodenum Left Kidney → Left Mid-Poupart Line Right Kidney Pancreas Pancreas Spleen Transverse Colon Transverse Colon Right Adrenal Gland Small Intestine Small Intestine Lower Quadrants Left Right Small Intestine Small Intestine Large Intestine Large Intestine Cecum Sigmoid colon Appendix Left ureter Right ureter Left reproductive organs Right reproductive organs Fallopian Tube (females) Figure 17. Left Mid-Poupart Line Ovary (females) Ovary (females) Fallopian tube (females) a. Corresponds to the inner edge of the descending colon Spermatic Cord (males) Spermatic Cord (males) ACTIVE RECALL BOX 1. Which is not a boundary of the abdomen? a. Diaphragm b. Pelvis c. Inguinal ligament d. Musculoaponeurotic wall 2. What is the lateral border of the rectus muscle? a. Linea semilunaris b. Umbilicus c. Anterior superior iliac spine d. Linea alba 3. T/F: The Transpyloric Plane, also known as Addison’s Plane, is located around where the pylorus of the stomach is. Answers: 1C, 2A, 3T Figure 19. Organs of the Four Quadrants of the Abdomen YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 4 of 9  B. REGIONS Figure 20. Numbered Regions and Planes of the Abdomen Defined by: – 2 Vertical Planes Figure 22. Organs of the Nine Regions of the Abdomen ▪ 2 Midclavicular Plane C. PRACTICAL APPLICATIONS – 2 Horizontal Planes Visualization of the position of the abdominal viscera is ▪ Subcostal Plane fundamental in physical examinations − Boundary that divides 1-3 and 4-6 Important to know which organs are located in each abdominal ▪ Transtubercular Plane/Intertubercular Plane region and quadrant − Boundary that divides 4-6 and 7-9 – To know where to auscultate, percuss, and palpate them Some of these viscera or their parts can be felt by palpating through the abdominal wall Surface features can be used to establish the positions of deep structures IV. ANTEROLATERAL ABDOMINAL WALL BOUNDARIES A. SUBDIVISIONS Figure 21. Regions of the Abdomen 9 Regions of the Abdomen: – Hypochondriac ▪ Hypo - below; Chondriac - cartilage – Lumbar ▪ Area of the lumbar vertebra – Iliac ▪ Area of the iliac crest of the pelvic girdle – Epigastric ▪ Area above the stomach – Umbilical ▪ Belly button – Hypogastric Figure 23. Abdominal Wall Subdivisions ▪ Area below the stomach The abdominal wall can be subdivided into: – Anterior wall Mnemonics Time! – Lateral walls (right and left) 9 Regions of the Abdomen. – Posterior wall Hector Loves Isabel Every Unceasing Hour The anterior and lateral walls are continuous – Hypochondriac – The boundary between the anterior and lateral walls is – Lumbar symmetric – Iliac – They are collectively called the anterolateral wall of the – Epigastric abdomen – Umbilical – Hypogastric YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 5 of 9  B. BOUNDARIES I. MAIN HEADING FORMAT V. ANTEROLATERAL ABDOMINAL WALL LAYERS Figure 24. Abdominal Wall Muscles Abdominal organ – Has minimal bones except for the posterior wall – Wall is instead made up of muscles and aponeurosis called a musculoaponeurotic wall Figure 26. Anterolateral Abdominal Wall Boundaries of the abdominal wall: The Anterolateral Abdominal Wall – Anterolaterally: musculoaponeurotic wall – Extends from the Thoracic Cage to the Pelvis – Superiorly: diaphragm – Boundaries: ▪ 7th to 10th ribs and xiphoid process ▪ Superior: 7-10th Ribs and Xiphoid Process – Inferiorly: muscles of the pelvis ▪ Inferior: Inguinal Ligament and superior margin of Pelvic C. BONES Girdle − Pelvic Girdle is composed of: o Iliac Crest o Pubic Crest o Pubic Symphysis A. MULTIPLE LAYERS THAT COMPOSE THE ABDOMINAL WALL Figure 27. Layers of the Anterior Abdominal Wall From Superficial to Deep: – Skin – Subcutaneous Tissue/Superficial Fascia ▪ Two kinds of superficial fascia which are normally below the umbilicus: − Camper’s Fascia (Fattier) Figure 25. Boundaries of the Abdominal Wall − Scarpa’s Fascia (more membranous) Musculoaponeurotic wall – External Oblique Muscle – Located anterolaterally – Internal Oblique Muscle – Suspended between and supported by two bony rings – Transversus Abdominis Muscle ▪ Superior: inferior margin of the thoracic skeleton – Transversalis Fascia ▪ Inferior: pelvic girdle – Extraperitoneal Fascia (fat) ▪ Bony rings are linked by a semi-rigid lumbar vertebral – Peritoneum column at the back Bony support functions as: Nice! – Protective structure that encloses and protects its contents Anterolateral Abdominal Wall Layers: – Provides flexibility for respiration, posture, and locomotion Sleepy Chrysty’s Study Encouragement Includes Textbooks, Voluntary or reflexive contraction of the abdominal muscle, Trans Notes, E books & Professor Phobia muscular roof, and floor could increase intra-abdominal pressure – Skin – This concerted effort aid in the following: – Camper’s Fascia ▪ Expulsion of air from the thoracic cavity – Scarpa’s Fascia – External Oblique Muscle ▪ Expulsion of fluid in urination – Internal Oblique Muscle ▪ Vomiting – Transversus Abdominis Muscle ▪ Passing out of gas – Transversalis Fascia ▪ Giving birth – Extraperitoneal Fascia YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 6 of 9  – Peritoneum C. SUBCUTANEOUS TISSUE B. SKIN DISSECTION OF THE ABDOMINAL SKIN Figure 31. Subcutaneous Tissue Layer Covers most of the abdominal wall Major site of fat storage – Fat may become very thickened in cases of morbid obesity Also called the superficial fascia of the abdominal wall Figure 28. Dissection of the Abdominal Skin – Layer after the skin Superior to the umbilicus Steps in chronological order: – The subcutaneous tissue is consistent with that found in most – Make a vertical midline incision through the skin from the regions Xiphoid Process to the Pubic Symphysis Inferior to the umbilicus ▪ Be careful not to cut through the superficial fascia – Forms two layers – Make a transverse incision from the superior end of the – Camper’s fascia: a superficial fatty layer (outer) vertical incision to the midaxillary line bilaterally (upper red – Scarpa’s fascia: deeper membranous layer (inner) arrow in the Figure 28) – More visible in the lower aspect of the abdominal wall below – From the inferior end of the vertical incision, cut along both the level of the umbilicus pubic crests. Extend the incisions below the inguinal ligament along the Iliac Crest to the ASIS (Iower red arrow in Figure 28) – Reflect the Skin laterally (as seen in Figure 29) Figure 32. Camper’s Fascia and Scarpa’s Fascia DISSECTION OF THE SUBCUTANEOUS TISSUE Figure 29. Dissection of the Abdominal Wall (Reflection of Skin) – Once you have reflected the skin, but before removing the superficial fascia of the anterior abdominal wall, you may be able to identify some superficial epigastric vessels (pointed in Figure 30) ▪ These vessels may become engorged in individuals whose venous blood cannot freely run to the heart − E.g: Obstruction of the Hepatic Portal Vein, portal hypertension ▪ The patient will be said to have caput medusae Figure 33. Subcutaneous Tissue Dissection Within the superficial fascia, there may be different amounts of fat in different cadavers – Some of this fat may be removed via liposuction Steps in chronological order: – Make incisions through the superficial fascia at similar locations to those in the skin. Figure 30. Dissection of the Abdominal Wall (Removed Skin) YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 7 of 9  – Reflect this fascia laterally. – CAMPER’S FASCIA Figure 36. Camper’s Fascia and Scarpa’s Fascia Figure 34. Camper’s Fascia Clinical Correlations: Scarpa’s Fascia As you go down the umbilicus, the superficial fascia is defined by 2 layers → Serves as a firm unit for suturing the superficial fascia during – Camper’s fascia closure of the anterior abdomen/perineum after abdominal or pelvic surgery – Scarpa’s fascia → Sufficiently complete to compartmentalize extravasated Camper’s fascia usually becomes continuous over the inguinal fluids like blood or urine ligament → E.g. Ureteral Rupture – In men, the superficial layer continuous over the penis and ○ Urine from the bladder can leak out but because of the scrotum the peculiar arrangement of the Scarpa’s fascia, it will ▪ Loses its fatty layer and becomes the dartos fascia prevent the extraversion of urine intra-abdominally – In women, some fat is retained to be a component of the labia majora SCARPA’S FASCIA Figure 37. Scarpia’s Fascia ACTIVE RECALL BOX Figure 35. Scarpa’s Fascia 1. Camper’s Fascia is considered the ____ layer between the two Deeper membranous layer of the superficial fascia subcutaneous tissue layers Thin and contains little to no fat a. More membranous When relaxed/tightened, it usually appears as a white line b. More fatty Structural support and it varies in strength and weakness c. More muscular throughout the body 2. T/F: The 4 quadrants of the abdominal wall are the hypochondriac, epigastric, iliac, and hypogastric – Stitched together first in closing abdominal wounds 3. The anterolateral abdominal wall extends from the thoracic Extends up and fades out to the thoracic wall and mid-axillary cage to the _____. line Answers: 1B, 2F, 3 Pelvis Fuses with: VI. SUMMARY & KEY POINTS – Fascia lata over the flexure of the skin crease of the hip – Linea alba and pubic symphysis The abdomen is part of the trunk between the thorax (upper) and – Continues over the penis and scrotum pelvis (lower). It is bounded anterolaterally by the ▪ Perineal area: superficial perineal fascia of Colles musculoaponeurotic wall, superiorly by the diaphragm, and Continues to anterior part of the perineum inferiorly by the pelvis. Attached to ischiopubic rami Voluntary or reflexive contraction of the abdominal muscle, muscular roof, and floor could increase intra-abdominal pressure. There are multiple layers that compose the abdominal wall, namely (from superficial to deep): Skin, Camper’s Fascia (fattier), Scarpa’s Fascia (more membranous), External Oblique Muscle, Internal Oblique Muscle, Transversus Abdominis Muscle, Transversalis Fascia, Extraperitoneal Fascia, Peritoneum. YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 8 of 9  REVIEW QUESTIONS #1: T/F: When the airway is open, the flat abdominal muscles contract simultaneously, leading to a decrease in intra-abdominal pressure and the diaphragm being pushed down. True or False? #2: T/F: The Subcostal Plane lies higher than the Transpyloric Plane True or False? #3: T/F: The xiphoid process can be found between the L3-L5 vertebra True or False? #4: Which of the following is involved in the closure of the anterior abdomen after a surgery? A. Anterior Rectus Sheath B. Posterior Rectus Sheath C. Scarpa’s Fascia D. Camper’s Fascia #5: Which is NOT one of the nine regions of the abdomen? A. Right Hypochondriac Region B. Middle Hypochondriac Region C. Hypogastric Region D. Left Lumbar Region Answer Key 1F, 2F, 3F, 4C, 5B RATIONALE TO ANSWERS OF REVIEW QUESTIONS 1. [F] — False. The open airway and the contraction of the abdominal muscles lead to an increase in Intra-abdominal pressure, which pushes the diaphragm up, allowing air to leave Figure 192832. Meme for Freedom Wall Space the lungs. 2. [F] — The transpyloric plane passes through L1, thus it lies higher than the subcostal plane which passes through the upper part of L3. 3. [F] — The Umbilicus is found between L3-L5. 4. [C] — The Scarpa’s Fascia serves as a firm unit for suturing the superficial fascia during closure after surgery in the area. 5. [B] —Middle Hypochondriac Region does not exist, there is only a Left and Right Hypochondriac Region. REFERENCES REQUIRED RESOURCES Nuez, M.P. (2024, January 15). Anterior Abdominal Wall [Lecture Slides]. Evaluate us! ✔ Feedback Form: bit.ly/2028EvalsYearRoundForm ✔ Errata Tracker: https://tinyurl.com/__ErrataTracker28 Figure 192833. Weh FREEDOM SPACE YL5 08.01 Gross Anatomy of the Anterior Abdominal Wall Part 1 9 of 9