Anatomy Abdomen in General PDF

4.01 11/03/2015 ABDOMEN IN GENERAL Dr. E. Acosta I.Anterior Abdominal Wall  Peritoneum A. Surface Landmarks...

4.01 11/03/2015 ABDOMEN IN GENERAL Dr. E. Acosta I.Anterior Abdominal Wall  Peritoneum A. Surface Landmarks o Describe the peritoneum and its disposition B. Four Quadrants and Nine Regions o Define the peritoneal cavity and spaces/fossae 1. Common Pathologies in Each Region o Name the peritoneal derivatives 2. Abdominal Incisions  Posterior Abdominal Wall C. Boundaries of the Anterior Abdominal Wall o Name the musculature of the posterior abdominal 1. Upper boundary wall 2. Lower boundary D. Anterior Abdominal Muscles I. ANTERIOR ABDOMINAL W ALL 1. Functions  Anterior Abdominal Wall 2. Flat muscles o crosses the lateral abdominal wall, hence it is also 3. Medial/Vertical muscles known as the anterolateral abdominal wall 4. Actions of each Muscle Group o Midinguinal points - midpoints of the lines E. Layers of the Abdomen joining the anterior superior iliac spine (ASIS) and F. Rectus Sheath, Linea Alba, and Umbilicus the pubic tubercles G. Blood Supply, Venous Drainage, and  Abdomen Lymphatic Drainage o Part of the trunk between the thorax and the H. Innervation pelvis II. Inguinal Region o A flexible, dynamic container, housing most of the A.Layers of Musculature and Other Pertinent organs of the alimentary system and part of the Structures urogenital system B. Inguinal Canal o Has musculotendinous walls, except posteriorly 1. Extent and Boundaries of the Inguinal Canal where the wall includes lumbar vertebrae and IV 2. Fetal Development of Inguinal Canal discs (Moore) C. Hernias o Walls III.Peritoneum  Anterolateral: Musculoaponeurotic walls A. Peritoneal formations  Superior: Diaphragm B. Subdivisions of Peritoneal Cavity  Inferior: Pelvis C. Anterior Abdominal Wall  Abdominal Cavity D. Pathologies o forms the superior and major part of the IV. Posterior Abdominal Wall abdominopelvic cavity A. Musculature of Posterior Abdominal Wall  Abdominopelvic cavity - the continuous cavity B. Blood Supply that extends between the thoracic diaphragm C. Venous Drainage and pelvic diaphragm D. Nerve Supply o has no floor of its own because it is continuous E. Lymphatic Drainage with the pelvic cavity o extends superiorly into the diaphragm and superoanteriorly intothe (inserted by Dr. LEARNING OBJECTIVES Acosta)osseocartilaginous thoracic cage to the 4th  Anterior Abdominal Wall intercostal space o Identify anatomical landmarks  Thoracic cage - protects the more superiorly o Describe quadrants and regions of the abdomen placed abdominal organs (spleen, liver, part of and the clinical applications the kidneys, and stomach) o Define extent of layers and musculature from  Greater pelvis - supports and partly protects superficial (outside) to deep (inside) the lower abdominal viscera (part of the o Describe formation and contents of rectus sheath ileum, cecum, appendix, and sigmoid colon). o Describe the vasculature, lymphatic drainage and o is the location of innervation.  most digestive organs(stomach, small  Inguinal Region intestines, most bowel)(inserted by Dr. o Name the layers of musculature and other Acosta) pertinent structures  urogenital system (kidneys, ureters) spleen o Describe the extent and boundaries of the inguinal canal o Define the superficial and deep inguinal rings o Differentiate the types of inguinal hernia o Describe other forms of hernia in the abdomen 1 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General I-A. SURFACE LANDMARKS  Inguinal Ligament(green line) o Ligament composed of the aponeurotic fibers of the External Oblique muscle, which lies deep to a skin crease that marks the division between the lower abdominal wall and thigh of the lower limb o Located between the ASIS to the pubic tubercle (inserted) o Defines the inguinal areaand is the lateral border of the Inguinal or Hesselbach’s triangle (inserted)  Iliac crest(orange line) o The rim of the ilium o Lies at about the level of the L4 vertebra  Superficial Epigastric veins(white line) o Found in pubic area o Arises from the Femoral Artery and courses toward the pubis *Pyramidalis - the second midline paired muscle that may be found inferior to the rectus abdominis(inserted) – can also be present which can increase number of visible “abs” to more than 6 in more muscular people Figure 1. Surface landmarks of the abdomen (Netter, 5 th edition - 2011) I-B. FOUR QUADRANTS AN D NINE REGIONS  Used in physical examination in order to locate Hard Tissues Soft Tissues abdominal organs, for pain assessment and abdominal Xiphoid Process pathologies. Linea Semilunaris Costal Margin Lateral to Rectus Iliac Crest FOUR QUADRANTS Abdominis muscle Anterior Superior Iliac Tendinous inscriptions on the Spine (ASIS) Anterior Rectus Sheath Pubic Tubercle Linea alba (midline) Inguinal Ligament Umbilicus Pubic Crest Table 1. Summary of the tissues of the anterolateral abdominal wall (from 2017 A transcription)  Linea Alba(red line) o Relatively avascular; subcutaneous band of fibrous tissue o Found midline, distinct in those with highly defined abdomen, formed by crisscrosses of the aponeuroses from the flat muscles. Figure 2. The 4 Quadrants of the Anterior Abdominal Wall o Midline raphe which extends from the xiphoid process to the pubic symphysis  Quadrants – divided into 4 through the umbilicus via: o All flat lateral abdominal muscle aponeuroses o Transverse Transumbilical plane (yellow line) (added) muscles except the rectus abdominiswill  divides the abdomen into upper and lower insert into the linea alba (2017A trans) hemi-abdomen (Horizontal Cut)  Tendinous Intersections(yellow line)  At level L3 and L4 vertebrae o Transverse skin grooves that demarcate o Vertical Median Plane or Midsagittal Line (blue transverse fibrous attachment points of the Rectus line) Sheath to the underlying Rectus Abdominis  divides the abdomen into left and right hemi- muscle abdomen from the xiphoid process to the o Defines the “abs” or “packs” symphysis pubis (Vertical Cut)  Linea Semilunaris/semilunar line(blue line) o These planes divide the abdomen into the Right o Curved line parallel to Linea Alba, defines the Upper and Lower Quadrant, and Left Upper and lateral wall of Rectus Abdominis muscle Lower Quadrant 2 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General - Also transects the following structures:  Pylorus  Gallbladder fundus  Pancreatic Neck  Origin of Superior mesenteric artery  Origin of Portal Vein  Root of Transverse Mesocolon  Duodenojejunal junction  Hila of kidney - Also separates the upper and middle thirds horizontally *Transpyloric plane is slightly higher than Subcostal plane, used interchangeably depending on the clinician  Transtubercular/Intertubercular - Passing through the iliac tubercles (approximately 5 cm posterior to the ASIS on each side) and the body of theL5 vertebra - Second horizontal line Table 2. Contents of the 4 Quadrants of the Anterior - Separates the middle and lower thirds Abdominal Wall horizontally  Interspinous plane  Regions – delineated by 4 planes: - Passes through palpated ASIS on each o 2 Sagittal: side  Left and Right(inserted)Midclavicular plane to Midinguinal plane - Passes midpoints of the lines joining the anterior superior iliac spine (ASIS) and the superior edge of the pubic symphysis on each side. (Moore) - Separates the right, middle and left thirds of the abdomen (inserted) vertically o 2 Transverse/Horizontal: subcostalor transpyloric plane, and interspinous or transtubercular plane(inserted)  Subcostal plane - Passes through the inferior border of the 10th costal cartilage and transtubercular (iliac tubercles usually body of L5)planes - Separates upper and middle thirdsof the abdomen(inserted) horizontally Figure 3. The 9 Regions of the Anterior Abdominal Wall - Between the hypochondriac and lumbar NINE REGIONS regions(inserted)  Hypochondriac – Upper right and left regions - More commonly used as the first horizontal  Epigastric – Upper middle region plane(inserted)  Lumbar/Flank – Middle right and left regions  Transpyloric plane  Umbilical – Center region / Middle region - Extrapolated midway between the  Iliac – Lower right and left regions superior borders of the manubrium of the  Hypogastric – Lower middle region sternum and the symphysis pubis, commonly transects the pylorus when the patient is recumbent (supine or prone) - A plane thatRight on top (transects)(deleted)will cross or transect the(inserted)pylorus of the stomach and found around the level of L1 - More superior than the subcostal planeFirst horizontal line 3 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General I-B-1. COMMON PATHOLOGIES IN THE NINE  Transverse Right Lower Quadrant Incision (blue) REGIONS o Rockey-Davisincision o Used in patients with appendicitis o Since the area of the appendix is localized in the right iliac region or RLQ, the physician will use McBurney’s point.  McBurney’s Point – Between the middle and(inserted) Distal third of an imaginary line(inserted) from the umbilicus to the ASIS o Preferred incision since a complete midline incision will induce more pain post-operatively which is why you limit your incision  Subcostal Incision (red) o Used in removal of liver or gallbladder (Right Subcostal Incision)  Mercedez-Sign Incision (pink) Figure 4. Common pathologies in the 9 regions o Used in pancreatectomy or removal of the  Examples: pancreas o Gallstones – RUQ pain or right hypochondriac o Used instead of subcostal incision when trying to region pain visualize more of the upper(inserted) abdominal o Appendicitis – RLQ pain or usually right iliac organs. region pain o An extension of the subcostal incision I-B-2. ABDOMINAL INCISIO NS  Pfannenstiel Incision (yellow) o Bikini Incision o Used in Caesarean Section o Also called “bikini cut” because the incision will not be seen when mothers choose to wear bikinis  Infraumbilical Incision(purple) o Also used in Caesarean Section o Incision is done midline below the umbilicus towards the pubic symphysis  Supraumbilical Incision (brown) o A horizontal (inserted)incision done a third of the way up from the umbilicus. o Mostly used in pediatric patients for optimal access of abdominal cavity since their abdomen has a bigger width than length (midline incision would be shorter than a transverse/horizontal incision) (inserted) is squarer than rectangular Figure 5. Common types of incisions.(A) Clockwise from the upper right quadrant are subcostal (Kocher), thoracoabdominal, left lower quadrant (extraperitoneal), vertical midline, and Rockey Davis (transverse)/McBurney (oblique). (B) From superior to inferior are bilateral subcostal with vertical T extension, supraumbilical transverse, infraumbilical transverse, left paramedian, and Pfannenstiel incision.  Midline Incision (green) o One straight line from tip of xiphoid (subxiphoid) to pubic symphysis (avoiding the umbilical area by going around it for better and more aesthetic healing and also because it is already a deep area) o May be used to determine extent of damage if patient presents with stab wound without removing the penetrating material (e.g. knife) or determine extent of involvement of the abdominal organs since the organs move on its own. 4 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General I-C. BOUNDARIES OF THE ABDOMEN  Lower Boundary of the Abdomen  Limits the contents of the abdomen superiorly and inferiorly *There is no actual structural cut-off between the abdomen and the pelvis (lower part of the abdomen) Figure 8. Lower Boundary of the Abdomen o Pelvis  Most inferior boundary  Includes the Inguinal Ligament and anterolateral aspect of Pelvic Girdle  Pelvic Girdle – also known as Greater pelvis - Consist of Iliac Crest, Pubic Crest and Pubic Symphysis - Bony protection for lower abdominal viscera I-D. ANTERIOR ABDOMINAL MUSCLES Figure 6. Boundaries of the Abdomen  Upper Boundary of the Abdomen Figure 7. Upper Boundary of the Abdomen o Diaphragm  Most superior boundary, found at the 7th- 10th costal cartilage and xiphoid process  Parachute-shaped to accommodate abdominal contents (as compared to lower boundary, Figure 9. Anterior Abdominal Muscles which is the pelvis that is a bony structure and only moves rarely such as in giving birth)  5 paired muscles in the anterolateral abdominal wall: o 3 lateral (inserted)flat muscles(external oblique, o Thoracic Cage internal oblique and transversus  Used in protecting upper abdominal viscera abdominis)(inserted) or upper abdominal organs such as the o 2 medial muscles (inserted): Rectus Abdominis stomach, small bowel, and colon and o Pyramidalis (inserted) 5 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General I-D-1. FUNCTIONS OF ABDO MINAL MUSCLES midclavicular line medially and at the spino- umbilical line (line running from the umbilicus to  Support for anterolateral abdominal wall the ASIS) inferiorly  Support for the abdominal viscera and protection from  With the contralateral Internal Oblique muscles, possible injuries these muscles will (inserted) work together to flex  Compression of the contents to maintain or increase and rotate the ipsilateral shoulder to the intraabdominal pressure contralateral hip (Torsional movement of  Movement of the trunk and maintenance of posture trunk)  Becomes the Dartos muscle to the scrotum (works together with the cremaster muscle) o Causes the scrotal skin to “wrinkle” when exposed to cold temperature B. Internal Oblique Muscles  Middle (intermediate) abdominal muscle  Fibers run superomedially (as if placing your hand on your chest)  Majority of the fibers run perpendicular to those of the External Oblique muscles o Except for its lowermost fibers, which arise from the lateral half of the inguinal ligament  Its fibers become aponeurotic at the midclavicular line and participate in the formation of the Rectus Sheath  Becomes the Cremaster muscle in the Spermatic Figure 10. Lateral view of Abdominal Muscles Cord o Elevates the testes when exposed to cold (sperm can only develop in a certain I-D-2. FLAT MUSCLES temperature)  3 ply (layers) structure consisting of *The external oblique and internal oblique work together to musculotendinous layers running in different flex and rotate the ipsilateral shoulder to the contralateral directions hip (torsional movement of the trunk; right shoulder to left  Interweaving between the right and left aponeurotic hip or left shoulder to right hip) fibers and between the superficial, intermediate and  To pull the body from the cephalic to caudal deep layers portion, both the external and internal oblique o Extends to the middle to meet via its aponeuroses muscles take action or tendons  Note: LEO RIO – RIGHT o The interweaving of the aponeuroses forms the o Left external oblique and right internal Rectus Sheath, which covers the Rectus Abdominis oblique are active when rotating the trunk muscle. and flexing the hip to the RIGHT A. External Oblique Muscles *The external and internal oblique are perpendicular to  Outermost, largest and most superficial abdominal each other except where it attaches to the iliac crest. Here, it muscle is almost parallel  Fibers run inferomedially, as if placing your hand ***Tip to remember the Direction of external vs. internal in your front pocket (However, the posteriormost oblique muscles: fibers are nearly vertical as they attach to the "Hands in your pockets":When you put your hands in your anterior half of the iliac crest) pockets, fingers now lie on top of external obliques and  In contrast to the two deeper layers, does not fingers point their direction of fibers: down and towards originate posteriorly from the thoracolumbar midline. fascia; its posteriormost fibers (thickest part of C. Transversus Abdominis the muscle) have a free edge where they span  Innermost abdominal muscle between its costal origin and iliac crest (Moore,  Transverse to the abdomen Dalley, & Agur, 2014) o Except for the inferior fibers, which run  Provides the aponeurosis to form the fibrous band parallel to those of the internal oblique between the ASIS and the pubic tubercle to form (Moore, Dalley, & Agur, 2014) the Inguinal Ligament (Poupart Ligament)  Decreases the diameter of the abdominal cavity  Fleshy part contributes to lateral part of the  Fibers run transverse, circumferential orientation abdominal wall to compress the abdominal contents causing an  Its aponeurosis contributes to the anterior wall; become aponeurotic approximately at the 6 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General increase in intraabdominal pressure (e.g. during Table 3. Actions of abdominal muscle groups defecation) Muscle group Action  Aponeurosis contributes to the formation of the Oblique muscles Laterally flex and rotate trunk Rectus Sheath Rectus Abdominis Flexes trunk and stabilizes pelvis *Between the internal oblique and transversus abdominal Pyramidalis Keeps Linea Alba taut muscles is a Neurovascular Plane containing the nerves *All muscles EXCEPT Pyramidalis muscle are for and arteries of the anterolateral abdominal wall compression  Oblique and transverse muscles, acting together I-D-3. MEDIAL/ VERTICAL MUSCLES bilaterally, form a muscular girdle that exerts firm A. Rectus Abdominis pressure on the abdominal viscera  Principal vertical muscle o Intra-abdominal pressure is needed for expelling  “Strap-like” band air during respiration (e.g., coughing, sneezing,  Paired rectus muscles separated by Linea Alba burping), vomiting and defecation  Three times as wide superiorly as inferiorly: It is broad and thin superiorly and narrow and thick *SEE APPENDIX FOR SUMMARY OF ANTERIOR inferiorly ABDOMINAL MUSCLES  Run vertically from xiphoid to the pubic I-E. LAYERS OF THE ABDOMEN symphysis  Anchored transversely by attachment to the anterior layer of the Rectus Sheath at three or more tendinous intersections  Tendinous intersections on the xiphoid level, umbilicus and in between B. Pyramidalis*  Most inferior midline abdominal muscles  Small, triangular muscle that is absent in approximately 20% of people  Lies anterior to the inferior part of the Rectus Abdominis muscle and attaches to the anterior surface of the Pubis and the anterior Pubic Ligament  Tenses the Linea Alba; when present, its attachment to the Linea Alba is used as a landmark for median abdominal incision  May or may not be present in cadavers* I-D-4. ACTIONS OF EACH MUSCLE GROUP Figure 12. (A) Anterior view and (B) Longitudinal section of the layers of the abdomen *Mnemonics: SaucyChristy’sSexualExploitsIncludeTransvestites,Transexua ls,Eunuchs, Puffs 1. Skin  Attaches loosely to the subcutaneous tissue (except at the umbilicus, where it adheres firmly) 2. Superficial Fascia or Subcutaneous Tissue  Contains a variable amount of fat; a major site of fat storage Figure 11. Actions of the abdominal muscle groups  Superior to umbilicus: the subcutaneous tissue is consistent with that found in most regions. 7 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General  Inferior to umbilicus: the deepest part of the subcutaneous tissue is reinforced by many elastic and collagen fibers.  Superficial Fatty Layer (Camper’s fascia)  Deep Membranous Layer (Scarpa’s fascia) *Continues inferiorly into the perineal region as the superficial perineal fascia (Colles fascia), but not into the thighs 3. Investing (deep) Fascia  Covers the external aspects of the muscles of anterolateral abdominal wall and their aponeuroses (flat expanded tendons).  Consisting of Superficial, Intermediate, and Deep layers  External aspects of the three muscles are represented mostly by the epimysium (outer fibrous connective tissue layer surrounding all muscles) 4. Muscles and their aponeuroses  Lateral: 3 flat muscles (External Oblique, Internal Oblique, Transversus Abdominis) Figure 13. Layers of the Anterior Abdominal Wall  Medial: 2 vertical muscles (Rectus Abdominis and Pyramidalis)  Midline: Linea Alba 5. Endoabdominal (Transversalis) Fascia  The internal aspect of the abdominal wall lined with membranous and areolar sheets of varying thickness  Note: it is called the Transversalis Fascia at the portion lining the deep surface of the Transversus Abdominis 6. Extraperitoneal fat  A variable amount of fat separating the Transversalis fascia and Parietal Peritoneum  Presence depending on the physique of an individual 7. Parietal Peritoneum  Single layer of epithelial cells and supporting connective tissue. *Neurovascular plane – between the Internal Oblique muscle and Transversus Abdominis muscle, and continuous between their aponeuroses at the region of the Rectus Sheath; contains the nerves and arteries of the anterolateral abdominal wall; nerves and vessels leave the neurovascular plane and lie mostly in the subcutaneous tissue Figure 14. Formation of Rectus Sheath and neurovascular structures of the anterolateral abdominal wall 8 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General  Arcuate Line - crescenteric line that demarcates the transition between the aponeurotic posterior wall of the sheath covering the superior ¾ of the Rectus Sheath (posterior lamina of the Inferior Oblique aponeurosis and the Transversus Abdominis) and the Transversalis fascia covering the inferoposterior ¼ of the Rectus Sheaththe presence and absence of the posterior rectus sheath found at the level of the ASIS or between the upper and middle 1/3 of the area between the umbilicus and the pubic symphysis/tubercle(inserted) - Inferior limit of the posterior rectus sheath - Indicates that there is no more contribution from all of the three flat muscles to the posterior rectus sheath(inserted) from this line downwards - Posteriorly, above this line, the posterior rectus sheath is present(inserted)there are still contributions(deleted) from the internal oblique and transversus abdominis. However, below this line, theposterior rectus sheath is Figure 15. Anterior Abdominal wall dissection absent.(inserted) re are no more contributions from these layers(see Figure 16) I-F. RECTUS SHEATH, LINEA ALBA, AND - Intersection between the arcuate line and UMBILICUS Linea Semilunaris (Lateral border of  Rectus Sheath Rectus Abdominis) is a weak point and a o The strong, incomplete fibrous compartment of possible site of hernia (2018B trans) the Rectus Abdominis and Pyramidalis muscles o Formed by the decussation and interweaving of the aponeuroses of the flat abdominal muscles o The External Oblique aponeurosis contributes to the anterior wall of the sheath throughout its length o The superior two-thirds of the Internal Oblique aponeurosis splits into two layers (laminae) at the lateral border of the Rectus Abdominis. (Moore)  Anterior Lamina: joins the External Oblique aponeurosis to form the anterior layer of the Rectus Sheath  Posterior Lamina: joins the Transversus Abdominis aponeurosis to form the posterior layer of the Rectus Sheath o One third of the distance from the Umbilicus to the Pubic CrestOR at the level of the ASIS (inserted), the aponeurosis of ALL (inserted) three flat muscles pass anterior to the Rectus Abdominis to form the anterior layer of the Rectus Sheath and Figure 16. Transverse section of the wall superior and there will no longer be a posterior rectus sheath inferior to the umbilicus showing the makeup of the Rectus below(inserted) Sheath  Thin Transversalis fasciaand parietal peritoneum (inserted)are left to cover the Rectus Abdominis posteriorly 9 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General o ANTERIOR LAYER of the Rectus Sheath o Superficial Epigastric – Found on the distal,  ABOVE the arcuate line (upper portion of bottom portion of the abdominal cavity abdomen): Aponeuroses of the external  Supplies the superficial abdominal wall of the oblique and anterior lamina of the internal PUBIC and INFERIOR umbilical regions oblique *The positions/locations of the vessels indicate the areas  BELOW the arcuate line (lower 2/3 of area they supply from umbilicus to pubic symphysis): ** The origin of the artery hints at what it supplies Aponeuroses of the external oblique, internal oblique, and transversus abdominis o POSTERIOR LAYER of the Rectus Sheath  ABOVE the arcuate line: Aponeuroses of the posterior lamina of the internal oblique and transversus abdominis  BELOW the arcuate line: absent(inserted) o Transversalis fascia, extraperitoneal fat, peritoneumwill be left posterior to the rectus abdominis(inserted)  Linea Alba o Interlaced fibers of the anterior and posterior layers of the Rectus Sheath in the anterior median line o Running vertically the length of the anterior abdominal wall and separating the bilateral Rectus Sheaths o Umbilical Ring: a defect in the Linea Alba through which the fetal umbilical vessels passed to and from the umbilical cord and placenta during pregnancy (Moore) Figure 17. Blood supply of the abdomen  Umbilicus o All layers of the abdominal wall fuse at the  Veins umbilicus o Drain into Axillary v. and Superficial Epigastric v. o As fat accumulates postnatally in the o Venous drainage is generally parallel to arterial subcutaneous tissue around the umbilical ring, the supply umbilicus becomes depressed (Moore) o Thoraco-epigastric vein - between Superficial Epigastric and Lateral Thoracic veins I-G. BLOOD SUPPLY, VEN OUS DRAINAGE, AND LYMPHATIC DRAINAGE O F THE ANTEROLATERAL ABDOMINAL WALL *SEE APPENDIX FOR THE SUMMARY OF THE ARTERIES OF THE ABDOMEN  Arteries o Musculophrenic + Superior Epigastric – Supplies the upper 1/3 of the abdominal cavity o 10th and 11th Posterior Intercostal Arteries + Subcostal Artery – Supplies the sides of the abdominal wall o Inferior Epigastric + Deep Circumflex Iliac – Supplies the deeper portions of the inferior abdominal wall (pubic and inguinal regions) o Superficial Circumflex Iliac + Superficial Epigastric – Supplies the superficial portion of the inferior abdominal wall *The superior epigastric artery anastomoses with the inferior epigastric artery approximately in the umbilical region (Moore, Dalley, & Agur, 2014) o The inferior epigastric vessels enter the rectus Figure 18. Lymphatics and superficial veins of the sheath and pass upward to anastomose with the abdomen superior epigastric vessels at the linea alba (2018B trans) 10 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General  Lymphatics and Superficial veins o Superficial lymphatic vessels  Accompany the Subcutaneous veins  Reference point - Transumbilical plane: - Superior: drain mainly to the Axillary lymph nodes, however few drain to the Parasternal lymph nodes. - Inferior: drain to the Superficial Inguinal lymph nodes o Deep lymphatic vessels  Accompany the deep veins and drain into the following: 1. External Iliac lymph nodes 2. Common Iliac lymph nodes 3. Right and left (Caval and Aortic) lymph node o Superficial Veins  References point –Umbilicus Figure 19. Caput Medusae - Above: Lateral Thoracic vein to Axillary vein I-H. INNERVATION OF AN TEROLATERAL - Below: Superficial Epigastric vein into ABDOMINAL WALL Femoral vein and Great Saphenous vein  Thoraco-epigastric vein - network of veins around the umbilicus; may exist or develop (as a result of altered venous flow) between the superficial epigastric vein (a femoral vein tributary) and the lateral thoracic vein (an axillary vein tributary) [Moore, Dalley, & Agur, 2014]  Paraumbilical vein – connect with Portal vein along Ligamentum Teres  Forms the Portal-Systemic venous anastomosis  Caput Medusae: in severe cases of portal obstruction, the veins of the anterior abdominal wall (normally caval tributaries) that anastomose with the paraumbilical veins (normally portal tributaries) may become varicose and look somewhat like small snakes radiating under the skin around the umbilicus; named as such because of its Figure 20. Dermatomes and nerves of anterolateral resemblance to the serpents on the head of abdominal wall Medusa, a character in Greek mythology. (Moore, 6th edition, page 288)  Thoracoabdominal nerves o T7 to T9 – supply skin superior to umbilicus o T10 – supplies skin around the umbilicus o T11 (with T12 and L1) – supplies skin inferior to umbilicus  Lateral Cutaneous Branches o T7 to T9 or T10  Subcostal nerve o T12  Iliohypogastric nerve (L1) o Pierces transversus abdominis muscle, branches pierce external oblique aponeurosis  Ilioinguinal nerve (L1) o Traverses inguinal canal 11 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General * The two L1 can elicit sharp burning pains when cut during  Components: surgery (i.e.for inguinal hernia) o Male: spermatic cord **Note: distribution and origin of motor innervation is o Female: round ligament of uterus similar to dermatomal coverage Spermatic Cord contents *Mnemonics:"Piles Don't Contribute To A Very Good Sex ***SEE APPENDIX FOR SUMMARY OF THE NERVE SUPPLY Life": OF THE ABDOMEN  Pampiniform venous plexus:a network formed by up to 12 veins that converge superiorly as right or left II. INGUINAL REGION testicular veins  Extends between the anterior superior iliac spine  Ductus deferens (vas deferens): a muscular tube (ASIS) and pubic tubercle (Moore, 2010) that conveys sperms from the epididymis to the  An anatomically important area because it is where ejaculatory duct. structures exit and enter the abdominal cavity (Moore,  Cremasteric artery: arising from the inferior 2010) epigastric artery  A clinically important area because the pathways of  Testicular artery: arising from the aorta and exit and entrance are potential sites of herniation supplying the testis and epididymis (Moore, 2010)  Artery of ductus deferens: arising from the inferior II-A. LAYERS OF MUSCULATUR E AND OTHER vesical artery PERTINENT STRUCTURES  Vestige of processus vaginalis:may be seen as a fibrous thread in the anterior part of the spermatic cord extending between the abdominal peritoneum and the tunica vaginalis; may not be detectable  Genital branch of the genitofemoral nerve:supplying the cremaster muscle.  Sympathetic nerve fiberson arteries and sympathetic and parasympathetic nerve fibers on the ductus deferens.  Lymphatic vessels:draining the testis and closely associated structures and passing to the lumbar lymph nodes Medial Inguinal Triangle  Hesselbach’s triangle o For the determination of whether a hernia is direct or indirect Figure 21. The inguinal region. Its dissection is described Iliopubic tract below (Netter, 2014)  Thickened inferior margin of the transversalis fascia,  Cut through the aponeurosis of the external oblique and which appears as a fibrous band running parallel and open it like a window. Cut through the internal oblique posterior (deep) to the inguinal ligament and open it like a door. You will see the transversus abdominis inside.  Underneath these layers will be the inguinal region  The space exposed upon dissection is the inguinal canal  REMEMBER! These three layers are important. They provide covering for the inguinal canal Inguinal/Poupart Ligament  Dense band constituting the inferiormost part of the external oblique aponeurosis Lacunar Ligament  Forms the medial boundary of the subinguinal space Pectineal Ligament of Cooper  most lateral of the Lacunar fibers that continue to run along the pecten pubis Inguinal Canal  Lies parallel and superior to the medial half of the inguinal ligament 12 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General Figure 22. Posterior (internal) view of the inguinal region showing the Hesselbach’s triangle bounded: (1)anteriorly Figure 23. Layers of the inguinal region, which the by the inguinal (Poupart) ligament, (2) iliopubic tract spermatic cord traverses posteriorly (3) the lateral portion of the rectus abdominis muscle medially, and (4) the inferior epigastric vessels superiorly. *NOTE: The iliopubic tract is the posterior portion; it is behind the inguinal ligament. They are two different things. **Below the inguinal ligament or the iliopubic tract will be the femoral ring, another site for hernias.  This triangle is important for you to identify if any protruding structure (herniation) is found inside or outside the triangle. This determines whether the hernia is direct or indirect  The inferior epigastric vessels originate from the external iliac vessels, and are surgically avoided since they are difficult to control Figure 24. Layers of the inguinal region, which the Layers that the spermatic cordtraverses before spermatic cord traverses reaching the scrotum:  Peritoneum  Extraperitoneal fat  Transversalis fascia  Transversus abdominis muscle  Internal oblique muscle  External oblique  Inguinal ligament *The transversus abdominis muscle and the internal oblique muscle will join to form the inguinal falx. REMEMBER! Beneath the external oblique will be the internal oblique. When cutting through the latter, one must be careful because underneath it and above the transversus abdominis will be the neurovascular plane. The iliohypogastric and ilioinguinal nerves are found in this area. Figure 25.Sagittal section of the anterior abdominal wall and inguinal canal at the vertical plane (gray line) shown in figure C and D. 13 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General A. Retroinguinal Space (of Bogros)  Roof: Transversalis fascia (laterally),  An extraperitoneal space found underneath the musculoaponeurotic arches of the internal oblique and transversalis fascia transversus abdominis (centrally), and medial crus of  Tissue or mesh repair can be done during inguinal the external oblique aponeurosis (medially) [Moore] surgery and placed in this area  Floor: Iliopubic tract (laterally), inguinal ligament  Area where you may findInguinal aspect of (centrally), and the lacunar ligament (medially) the(inserted)extraperitoneal fatlayer(inserted) [Moore] II-B. INGUINAL CANAL ** Tip to remember:  An oblique passage directed inferomedially through the inferior part of the anterolateral abdominal wall  Lies parallel and superior to the medial half of the inguinal ligament  The inguinal canal will run through the inguinal ligament  Main occupants: o Spermatic cord in males o Round ligament of the uterus in females  Also contains blood and lymphatic vessels and the ilioinguinal nerve  The spermatic cord to include(inserted) the vas (ductus) deferens and testicular vessels will run through the inguinal canal  Has an opening at each end: *SEE APPENDIX FOR SUMMARY OF THE BOUNDARIES OF o Deep (internal) inguinal ring THE INGUINAL CANAL  Entrance to the inguinal canal  Located superior to the middle of the inguinal II-B-2. FETAL DEVELOPMENT OF THE INGUINAL ligament and lateral to the inferior epigastric CANAL artery  An invagination in the transversalis fascia  Comes from the deeper portion of the abdomen  Will provide the opening going to the inguinal canal, which contains the spermatic cord in males  Traversing structures: vas deferens, pampiniform plexus, testicular vessels, and the genital branch of the genitofemoral nerve o Superficial (external) inguinal ring  Exit by which the spermatic cord, or the round ligament, emerges from the inguinal canal  A split that occurs in the diagonal, otherwise parallel fibers of the external oblique aponeurosis just superolateral to the pubic tubercle II-B-1. EXTENT AND BOUNDARIE S OF INGUINAL CANAL  Anterior wall: External oblique aponeurosis throughout the length of the canal; its lateral part is reinforced by muscle fibers of the internal oblique (Moore)  Posterior wall: Transversalis fascia; with the middle part reinforced by pubic attachments of the internal oblique and the transversus abdominis aponeurosis (they merge into a common tendon called the inguinal falx); and the reflected inguinal ligament (Moore) 14 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General II-C. LAYERS OF THE ANTERIOR ABDOMINAL WALL, SCROTUM, AND T HE SPERMATIC CORD *The scrotum of a male elevates(the muscle causes the testis to move against the body) during cold showers through the action of the cremaster muscle, a derivative of the internal oblique muscle. This is to keep the testes in a warm environment for the sperm. Figure 26. Formation of inguinal canals and relocation of testes. Left: Sagittal cut; Right: Coronal cut (A) In a 7-week embryo, the testis is attached to Figure 27. Corresponding layers of the anterior abdominal the posterior abdominal wall. wall to the scrotum and coverings of spermatic cord  By the 12th week, the testis is in the pelvis. (Moore) II-D. HERNIAS  The male gubernaculum is a fibrous  An inguinal hernia is a protrusion of parietal tract connecting the primordial testis to peritoneum and viscera, such as the small intestine, the anterolateral abdominal wall, where through a normal or abnormal opening from the cavity the future deep ring of the inguinal canal in which they belong. (Moore) is (Moore) o Indirect inguinal hernia: There’s some weakness  The female gubernaculum connects the in the abdominal wall. The hernia directly travels ovaries and the primordial uterus to the through the inguinal canal. It is outside the labia majus (Moore) Hesselbach’s triangle. (B) A fetus at 28 weeks (seventh month) shows  Supposedly due to the persistence of the the processus vaginalis and testis passing processus vaginalis through the inguinal canal. The testis passes  More commonly found in pediatric patients or posterior to the processus vaginalis, not adolescents through it. (Moore) o Direct inguinal hernia: A hernia outside of the (C) In a newborn infant, obliteration of the stalk inguinal canal. Thus, there is a direct weakness of of the processus vaginalis has occurred. The the abdominal wall. It is in the Hesselbach’s remains of the processus vaginalis have triangle. formed the tunica vaginalis of the testis. The  Can be observed in patients with chronic remnant of the gubernaculums has obstructive pulmonary disease (COPD), which is disappeared. (Moore) usually a disease of smokers  The anterior abdominal muscles are pushed to  At 7 weeks of gestation, the testis (found in the thinness/weakness extraperitoneal region) will travel from the upper part o Pantaloon hernia: Both direct and indirect of the abdomen downwards inguinal hernia (tip: pants have two legs, so it’s both)  On the 7th month, the testis will travel down with the o Epigastric hernia: epigastric area testicular vessels going to the scrotum. This is guided o Umbilical hernia: umbilicus by the gubernaculum (a pathway) o Incisional hernia: post-operative problem usually  The pathway formed by the gubernaculum is the weak due to the opening of investing fascia during link that sometimes causes the indirect inguinal hernia surgery  By the time the baby is delivered, the testis is already in the scrotum, and the spermatic cord is already ** SEE APPENDIX FOR THE SUMMARY OF THE present CHARACTERISTICS OF DIRECT AND INDIRECT INGUINAL  The inguinal canal is formed due to the pathway that HERNIAS the testis follows during development Undescended testes may cause malignancy (Medical diagnosis: cryptorchidism) 15 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General  Techniques in determining types of hernia III. PERITONEUM o Usually required during physical exam  Serous membrane consisting of mesothelium that o 5th digit (pinky finger) for kids covers the internal aspect and most of abdominal o Pointing finger for adults cavity o METHOD:  2 continuous layers made of mesothelium (simple 1. Insert finger squamous epithelial cells) 2. Get the loose skin of testes o Parietal Peritoneum – Glistening layer of 3. Push finger up through the inguinal canal abdominal wall formed by a single layer of 4. Let the patient cough (to incease epithelial cells and supporting connective tissue; intraabdominal pressure) sensitive to pressure, pain, heat, cold and *Indirect inguinal hernia: felt mass at the tip of laceration (Moore) your finger; or down the scrotum o Visceral Peritoneum – Layer investing on the *Direct inguinal hernia: felt mass at the side of viscera that is sensitive to stretching and chemical your finger (inside the triangle) irritation; insensitive to touch, heat, cold and laceration (Moore)  Peritoneal Cavity – Bursal sac or lined potential space between the walls and viscera containing peritoneal fluid for lubrication for movements of digestion o Air in the peritoneal cavity is called pneumoperitoneum o In males, the cavity is completely closed, but in females, there is a communication pathway in females through the uterine tubes, cavity, and vagina, which is a pathway for infection  Divides the viscera into intraperitoneal and extraperitoneal organs (Moore) o Intraperitoneal organs are invaginated into the closed sac, and are nearly completely covered with visceral peritoneum (e.g., stomach, spleen) – organs that need to move o Extraperitoneal, retroperitoneal and Figure 28. Different types of hernia and their subperitoneal organs are only partially covered corresponding regions with peritoneum, usually on just one surface (e.g., kidney, urinary bladder) – organs that need to be anchored to the body III-A. PERITONEAL FORMATIONS  Mesentery – Double layer of peritoneum that occurs as invagination of peritoneum by an organ (Moore) o Continuity of visceral and parietal peritoneum o Provides a means for neurovascular communication between the organ and the body wall (usually the posterior abdominal wall) o “Mesentery” usually refers to the mesentery of the small intestine, with other specific parts named accordingly  Mesoesophagus – For esophagus  Mesogastrium – For stomach  Mesocolon – For the colon  Transverse and sigmoid mesocolons Figure 29. Hernias are surgically treated using a mesh repair or a Lichtenstein repair, where a mesh is placed on top of the strongest layer, the posterior wall of the inguinal canal, the transversalis fascia. Its strength is not based on the mesh but the fibrosis that results from the body’s reaction to the mesh. 16 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General  Omentum – Double Layered extension or fold of o Infracolic compartment is divided into left and peritoneum that passes from the stomach and right infracolic spaces by mesentery of small proximal part of the duodenum to adjacent organs in intestine the abdominal cavity (Moore) o Free communication occurs between the supra- o Greater Omentum (yellow arrow) – Four-layered and infracolic compartments through the peritoneal fold hanging down like an apron from paracolic gutters the greater curvature of the stomach and proximal  Omental bursa (lesser sac) is a sac-like cavity that part of duodenum, and after descending, folds lies posterior to the stomach and lesser omentum. back and attaches to anterior surface of the (Moore) Superiorly bounded by the diaphragm and transverse colon and its mesentery posteriorly by the coronary ligament of the liver. o Lesser Omentum (blue arrow) – Smaller, two- Inferiorly bounded by the layers of the greater layered peritoneal fold that connects the lesser omentum. curvature of the stomach and proximal part of o Permits free movement of stomach on structures duodenum to the liver posterior and inferior to it o Communicates with the greater sac (the abdominal cavity) through the omental foramen III-B. ANTERIOR ABDOMINAL WALL  Median umbilical ligament o obliterated urachus – connection between the umbilicus and the bladder  Medial umbilical folds (left and right) o lateral to the median umbilical ligament  Lateral umbilical folds (left and right) o covers the inferior epigastric vessels III-C. PATHOLOGIES  Pneumoperitoneum – Presence of air inside the peritoneal cavity (Moore) o Symptoms include drawing in of abdomen as chest Figure 30. Greater and Lesser Omentum (Moore, edited by expands (also known as paradoxical previous batch) abdominothoracic rhythm), and muscle rigidity o Can be due to perforation of viscera o Counterpart in the thorax is pneumothorax o Different from gastric bubble, which is normal and can be seen in the fundus of the stomach  Ascites – Presence of excess fluid (ascetic fluid) in the peritoneal cavity (Moore) o May occur as a result of mechanical injury o Causes distention of peritoneal cavity, interfering with movements of viscera o Counterpart in thorax is pleural effusion IV. POSTERIOR ABDOMINAL WALL IV-A. CONTENTS  Central: 5 Lumbar Vertebrae and IV discs  Superior boundary: Diaphragm  Lateral boundary: Abdominal wall muscles Figure 31. Principal formations of the peritoneum. (Moore) o Psoas major and minor Focus on the compartments o Quadratus lumborum o Iliacus III-B. SUBDIVISIONS OF THE PERITONEAL o Transversus abdominis CAVITY o External and internal obliques  Transverse mesocolon divides abdominal cavity into  Thoracolumbar fascia supracolic compartment (stomach, liver, and spleen)  Lumbar plexus (anterior rami of lumbar plexus) and infracolic compartment (small intestine,  Fat, nerves, vessels and lymph nodes (unspecified) ascending and descending colon) [Moore] *SEE APPENDIX FOR THE SUMMARY OF MUSCLES OF THE POSTERIOR ABDOMINAL WALL 17 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General IV-B. BLOOD SUPPLY, VENOUS DRAINAGE, AND  Oblique and transverse muscles, acting together LYMPHATIC DRAINAGE , AND INNERVATION OF bilaterally, form a muscular girdle that exerts firm THE POSTERIOR ABDOMINAL WALL pressure on the abdominal viscera  Blood Supply  Intra-abdominal pressure is needed for expelling air o Descending aorta becomes the abdominal aorta during respiration (e.g., coughing, sneezing, burping), vomiting and defecation  Inguinal region: it is where structures exit and enter the abdominal cavity; pathways of exit and entrance are potential sites of herniation  Inguinal Canal boundaries: Remember MALT REVIEW QUESTIONS 1. The Inguinal ligament is composed of the aponeurotic fibers of which abdominal muscle? a. External Oblique b. Internal Oblique c. Transversus Abdominis Figure 32. Branches of the abdominal aorta d. Rectus Abdominis 2. It is a surgical incision used in Cesarean Section, also known as the “Bikini cut”  Venous Drainage a. Infraumbilical Incision o Main venous drainage is the Inferior Vena Cava b. Mercedez-Sign Incision o Portal circulation involves the hepatic portal vein c. Pfannenstiel Incision which drains blood from the GIT then brings it to d. McBurney’s point the liver before it drains to the hepatic vein then 3. All of the following muscles are responsible for the to the IVC compression of the abdomen EXCEPT:  Nerve Supply a. Rectus Abdominis o From the anterior rami of T7-L1 spinal nerves as b. Oblique muscles thoracoabdominal, subcostal, iliohypogastric c. Pyramidalis (T12-L1), and iliolingual (L1) nerves 4. Which layer of subcutaneous tissue or superficial fascia is considered the “deep membranous layer”? IV-E. LYMPHATIC DRAINAGE a. Camper’s fascia  Specifically for each organ b. Scarpa’s fascia  Superficial vessels: supraumbilical region drains into c. Colles fascia pectoral axillary nodes; infraumbillical region drains 5. The Neurovascular Plane can be found between which into superficial inguinal nodes of the following muscles?  Deep vessels: follow arteries and drain into internal a. External Oblique and Internal Oblique thoracic,external iliac, posterior mediastinal, and para- and Transversus Abdominis aortic nodes b. Transversus Abdominis and Rectus Abdominis SUMMARY c. Rectus Abdominus and Pyramidalis  Surface Landmarks: linea alba, tendinous 6. Which of the following is NOT a content of the intersections, linea semilunaris/semilunar line, spermatic cord? inguinal ligament, iliac crest, superficial epigastric a. Vas deferens veins b. Pampiniform plexus  Four quadrants: RUQ, LUQ, RLQ, LLQ (more commonly c. Femoral branch of the genitofemoral used) nerve  Nine Regions: hypochondriac (upper left and right), d. Testicular vessels epigastric (upper middle), lumbar/Flank (middle left 7. Which among the following layers is the deepest? and right), umbilical (center region), iliac (lower left a. Transversalis fascia and right), hypogastric(lower middle) b. External oblique muscle  Upper boundary of anterior abdominal wall: c. Internal oblique muscle diaphragm and thoracic cage d. Transversus abdominis muscle  Lower boundary of anterior abdominal wall: pelvis  All muscles EXCEPT Pyramidalis muscle are for compression 18 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General 8. The transversalis fascia make up the posterior wall of REFERENCES which third of the inguinal canal?  Acosta, E. (2015). Lecture on abdomen in general. a. Lateral third  Moore, K., Dalley, A., Agur, A. (2014). Clinically b. Middle third Oriented Anatomy(7thed.). Lippincott Williams & c. Medial third Wilkins: Philadelphia. d. Both A and B  Netter’s Clinical Anatomy (6th ed.). (2014). Saunders: e. Both B and C Philadelphia 9. What fetal structure connects the primordial testis to  2018 A and B transes the anterolateral abdominal wall?  2017 A trans a. Vas deferens b. Gubernaculum c. Processusvaginalis MOTIVATIONAL MESSAGE d. Ductusprimordium 10. The cremaster muscle is a derivative of which muscle? a. External oblique “The way to get started is to QUIT TALKING b. Internal oblique and BEGIN DOING” – Walt Disney c. Transversus abdominis d. Rectus abdominis “There is no elevator to success. You have Answers: ACCBBCADBB to take the stairs!” “You were given this life because you’re strong enough to live it” 19 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General APPENDICES Appendix 1. Summary of Anterior Abdominal Muscles (Moore) Appendix 2. Summary of the arteries of the abdomen Appendix 3. Summary of the nerve supply of the abdomen 20 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]  4.01 Abdomen in General Appendix 4. Summary of the boundaries of the inguinal canal Appendix 5. Summary of the characteristics of direct and indirect inguinal hernias Appendix 6. Summary of the muscles of the posterior abdominal wall 21 of 21 Abdomen in General [Abella, Abesamis, Aburayyan, Ada, Aison]