Abdomen and Pelvis Anatomy: Boundaries and Inguinal Hernias

Abdomen: Boundaries and Protection

Silvia OldaniAbdomen: boundaries Diaphragm Inferior thoracic aperture Abdominal wall Iliac crest Pelvic inlet Lower limb Inguinal ligament

AAbdomen: protection of viscera Thoracic wall Abdominal cavity Axis of abdominal cavity Pelvic cavity Pelvic inlet Axis of pelvic cavity

Abdomen: Breathing and Pressure Changes

Abdomen: breathing Contraction of diaphragm Relaxation of abdominal muscles Diaphragm Relaxation of diaphragm Contraction of abdominal muscles Inspiration Expiration

Abdomen: changes in intraabdominal presssure Laryngeal cavity closed Air retained in thorax Fixed diaphragm Contraction of abdominal wall Increase in intraabdominal pressure Micturition Childbirth Defecation

Abdomen: Components and Surface Projection

Abdomen: components Quadratus lumborum External oblique Rib XII Costal margin Iliolumbar ligament Internal oblique Rectus abdominis Transversus abdominis Pelvic inlet Inguinal ligament Gap between inguinal ligament and pelvic bone Iliacus Psoas major A B

Abdomen: boundaries Pelvic bone Ala of sacrum Esophageal opening Costal margin Lateral arcuate ligament Median arcuate ligament Medial arcuate ligament LV Left crus SI Right crus Quadratus lumborum Psoas major Pelvic inlet Inguinal ligament

Abdomen:surface projection of the abdomen Thorax Diaphragm Costal margin Abdomen Iliac crest Anterior superior iliac spine Inguinal ligament Lower limb Pubic tubercle

Abdomen: Planes, Regions, and Quadrants

Abdomen: plain and regions Midclavicular planes Epigastric region -referred pain from foregut Right hypochondrium Left hypochondrium Subcostal plane Umbilical region -referred pain from midgut Right flank Left flank Intertubercular plane Right groin Left groin Anterior superior iliac spine Inguinal ligament Pubic region -referred pain from hindgut Pubic tubercle

Abdomen:quadrants Sagittal plane Liver Diaphragm Spleen Costal margin Stomach Gallbladder Transumbilical plane McBurney's point Descending colon Anterior superior iliac spine Appendix Sigmoid colon Inguinal ligament Pubic tubercle

Abdomen: Anterolateral Wall Anatomy

Anterolateral Wall Muscles

Abdomen: anterolateral wall Quadratus lumborum External oblique Rib XII Costal margin Iliolumbar ligament Internal oblique Rectus abdominis Transversus abdominis Pelvic inlet Inguinal ligament Gap between inguinal ligament and pelvic bone Iliacus Psoas major A B

Abdomen: anterolateral wall Linea Vertical anterior abdominal muscles alba Flat anterolateral abdominal muscles Anterior Anterolateral Left lateral (flank) of abdomen of back Axio-appendicular muscles* Vertical posterior muscles Posterior Lumbar vertebra Inferior view Boundary indefinite and overlapping

Anterolateral Wall Layers

Abdomen: anterolateral wall Skin External oblique muscle Superficial fascia- fatty layer (Camper's fascia) 1 Internal oblique muscle Superficial fascia- membranous layer (Scarpa's fascia) Transversus abdominis muscle Transversalis fascia Parietal peritoneum Extraperitoneal fascia

Superficial Fascia

Abdomen: superficial fascia Membranous layer of superficial fascia (Scarpa's fascia) External oblique muscle and aponeurosis Continuity with superficial penile fascia Attachment to fascia lata Attachment to ischiopubic rami Superficial perineal fascia (Colles' fascia) Continuity with dartos fascia

Fascia of Anterolateral Abdominal Wall

Abdomen: fascia of anterolateral abdomial wall Superficial Deep Skin (cut edge) Superficial fatty layer of subcutaneous tissue (Camper fascia) External oblique Internal oblique Transversus abdominis Deep membranous layer of subcutaneous tissue (Scarpa fascia) Extraperitoneal fat Endoabdominal (transversalis) fascia Investing (deep) fascia-superficial, intermediate, & deep -Parietal peritoneum

Transversalis Fascia

Abdomen: transversalis fascia „Transversus abdominis Deep Intermediate Superficial Internal oblique External oblique Parietal peritoneum Extraperitoneal fat Rectus abdominis Transversalis fascia Aponeurosis of D. Skin Fatty layer of subcutaneous tissue Rectus sheath Linea alba Membranous layer of subcutaneous tissue E. Transverse Sections

Abdomen: transversalis fascia Section below arcuate line Aponeurosis of external oblique muscle Anterior layer of rectus sheath External oblique muscle Rectus abdominis muscle Aponeurosis of internal oblique muscle Internal oblique muscle Skin Aponeurosis of transversus abdominis muscle Transversus abdominis muscle Transversalis fascia Medial umbilical ligament and fold Peritoneum Extraperitoneal fascia Urachus (in median umbilical fold) Umbilical prevesical fascia Subcutaneous tissue (fatty and membranous layers)Thoracolumbar fascia Psoas major muscle Transversus abdominis muscle Quadratus lumborum muscle Latissimus dorsi muscle Erector spinae muscles Thoracolumbar fascia Anterior layer Middle layer Posterior layer

Abdomen: Anterolateral Muscles

General Overview

Abdomen: anterolateral muscles Pectoralis major Serratus anterior Linea alba Tendinous intersection Transversus abdominis - Rectus abdominis Internal oblique External oblique Aponeurosis of the external oblique Inguinal ligament (formed by free interior border of the external oblique aponeurosis)

External Oblique Muscle

Abdomen: external oblique Latissimus dorsi muscle Abdominal part of pectoralis major muscle Linea alba External oblique muscle Aponeurosis of external oblique Anterior superior iliac spine Inguinal ligament Origin Muscular slips from the outer surfaces of the lower eight ribs (ribs V to XII) Insertion Lateral lip of iliac crest; aponeurosis ending in midline raphe (linea alba) Innervation Anterior rami of lower six thoracic spinal nerves (T7 to T12) Function Compress abdominal contents; both muscles flex trunk; each muscle bends trunk to same side, turning anterior part of abdomen to opposite

Associated Ligaments

Abdomen: associated ligaments External oblique Anterior superior iliac spine Aponeurosis of external oblique OC Inguinal ligament Lacunar ligament Femoral artery and vein Pubic tubercle

Abdomen: associated ligaments Anterior superior iliac spine Pectineal ligament Inguinal ligament Pectineal line Pubic tubercle Pubic symphysis Lacunar ligament

Internal Oblique Muscle

Abdomen: internal oblique External oblique muscle External oblique muscle Rib X Linea alba Internal oblique muscle and aponeurosis - Aponeurosis of external oblique Anterior superior iliac spine Origin Thoracolumbar fascia; iliac crest between origins of external and transversus; lateral two-thirds of inguinal ligament Insertion Inferior border of the lower three or four ribs; aponeurosis ending in linea alba; pubic crest and pectineal line Innervation Anterior rami of lower six thoracic spinal nerves (T7 to T12) and L1 Function Compress abdominal contents; both muscles flex trunk; each muscle bends trunk and turns anterior part of abdomen to same sideFibers of left external oblique aponeurosis, which run deep on the right side and running superficially on the left side Umbilical ring Deep fibers of right external oblique aponeurosis Deep fibers of left external oblique aponeurosis Intramuscular exchange of superficial and deep fibers within aponeuroses of contralateral external oblique muscles. (A) Anterior views Fibers passing from superficial to deep (and vice versa) at linea alba Right external oblique muscle Fibers of left internal oblique aponeurosis Fibers of right extemal oblique aponeurosis Left internal oblique muscle Intermuscular exchange of fibers between aponeuroses of contralateral external and internal oblique muscles. Rectus sheath Aponeurosis of transversus abdominis muscle Rectus abdominis Parietal peritoneum Transversalis fascia Transversus abdominis muscle Internal oblique External oblique Subcutaneous tissue Aponeurosis of external oblique Laminae of aponeurosis of internal oblique Skin Linea alba (note fibers passing from superficial to deep, and vice versa, as in right side of figure A) Linea alba Parietal peritoneum Extraperitoneal fat -Transversalis fascia Membranous layer ) Fatty layer Subcutaneous tissue Superior views of transverse sections (B) Anterior view Linea alba Rectus sheath

Transversus Abdominis Muscle

Abdomen: transversus abdominis External oblique muscle External oblique muscle Rib X - - Aponeurosis of external oblique Transversus abdominis muscle and aponeurosis Aponeurosis of internal oblique Anterior superior iliac spine Linea alba Origin Thoracolumbar fascia; medial lip of iliac crest; lateral one-third of inguinal ligament; costal cartilages lower six ribs (ribs VII to XII) Insertion Aponeurosis ending in linea alba; pubic crest and pectineal line Innervation Anterior rami of lower six thoracic spinal nerves (T7 to T12) and L1 Function Compress abdominal contents

Rectus Abdominis Muscle

Abdomen: rectus abdomis Origin Pubic crest, pubic tubercle, and pubic symphysis Insertion Costal cartilages of ribs V to VII; xiphoid process External oblique muscle Rectus abdominis muscle Posterior wall of rectus sheath Innervation Internal oblique muscle Tendinous intersection 0 Arcuate line Transversalis fascia -Linea alba Pyramidalis muscle Anterior rami of lower seven thoracic spinal nerves (T7 to T12) Function Compress abdominal contents; flex vertebral column; tense abdominal wall

Pyramidalis Muscle

Abdomen: pyramidalis Origin Front of pubis and pubic symphysis Insertion Into linea alba External oblique muscle Rectus abdominis muscle Posterior wall of rectus sheath Internal oblique muscle Tendinous intersection 0 Arcuate line Transversalis fascia -Linea alba Pyramidalis muscle Innervation Anterior ramus of T12 Function Tenses the linea alba

Rectus Sheath

Abdomen: rectus sheath Linea alba Rectus abdominis External oblique Transversalis fascia Internal oblique Parietal peritoneum A Transversus abdominis Linea alba Rectus abdominis External oblique Transversalis fascia Internal oblique Parietal peritoneum Transversus abdominis BCostal margin Xiphoid process Linea alba (midline) Linea alba (midline) Variations of anterior and posterior rectus sheath at different levels (right side) EO RA Level above costal margin Right rectus muscle Costal cartilage 5.6.7 Superior epigastric vessels External oblique muscle EO RA Level above arcuate line Arcuate line (behind rectus muscle) * Lateral and medial branch of type Il deep epigastric vessels (DIEA and DIEV) EO RA 1 10 Level below arcuate line TA TF Inferior epigastric vessels EO 10. TA Level above pubic symphysis Pyramidalis muscle TF RA Pubic symphysis · Common branching patterns: - Type I DIEA continues as a single vessel (29%). - Type II DIEA divides into two vessels (57%). - Type III DIEA is a trifurcation (14%). RA = Rectus abdominis EO = External oblique IO = Internal oblique TA = Transversus abdominis TF = Transversalis fascia 10 TA TF