Surgical Anatomy of Anterior Abdominal Wall - PDF

Surgical Anatomy of (Anterior Abdominal Wall, Retroperitoneal Region, Suprarenal Glands, and Inguinal Region) Prepared by Dr Ibrahim Mousa Maaroof Higher Diploma student M.B.Ch.B. Dr Sarmad Nadhem Ismael Higher Diploma student M.B.Ch.B. Supervised by Assist. Prof. Dr Baderkhan Saeed Ahmed Assist. Pr...

Surgical Anatomy of (Anterior Abdominal Wall, Retroperitoneal Region, Suprarenal Glands, and Inguinal Region) Prepared by Dr Ibrahim Mousa Maaroof Higher Diploma student M.B.Ch.B. Dr Sarmad Nadhem Ismael Higher Diploma student M.B.Ch.B. Supervised by Assist. Prof. Dr Baderkhan Saeed Ahmed Assist. Prof. Dr Azhy Muhammed Dewana 19 December 2023 1 THE ANTERIOR ABDOMINAL WALL ABDOMINAL WALL LAYERS • The anterolateral abdominal wall consists of four main layers (external to internal): skin, superficial fascia, muscles and associated fascia, and parietal peritoneum. THE ABDOMINAL WALL FUNCTIONS • Forms a firm, yet flexible boundary which keeps the abdominal viscera in the abdominal cavity and assists the viscera in maintaining their anatomical position against gravity. • Protects the abdominal viscera from injury. • Assists in forceful expiration by pushing the abdominal viscera upwards. • Is involved in any action (coughing, vomiting, defecation) that increases intra-abdominal pressure. SUPERFICIAL FASCIA The superficial fascia is connective tissue. The composition of this layer depends on its location: • Above the umbilicus – a single sheet of connective tissue. It is continuous with the superficial fascia in other regions of the body. • Below the umbilicus – divided into two layers; the fatty superficial layer (Camper’s fascia) and the membranous deep layer (Scarpa’s fascia). The superficial vessels and nerves run between these two layers of fascia. MUSCLES OF THE ABDOMINAL WALL The muscles of the anterolateral abdominal wall can be divided into two main groups: • Flat muscles – three flat muscles, situated laterally on either side of the abdomen. • Vertical muscles – two vertical muscles, situated near the mid-line of the body. A- FLAT MUSCLES There are three flat muscles located laterally in the abdominal wall, stacked upon one another. Their fibers run in differing directions and cross each other – strengthening the wall and decreasing the risk of abdominal contents herniating through the wall. In the anteromedial aspect of the abdominal wall, each flat muscle forms an aponeurosis, which covers the vertical rectus abdominis muscle. The aponeuroses of all the flat muscles become entwined in the midline, forming the Linea alba. FLAT MUSCLES External Oblique • The external oblique is the largest and most superficial flat muscle in the abdominal wall. Its fibers run inferomedially. • Attachments: Originates from ribs 5-12 and inserts onto the iliac crest and pubic tubercle Linea alba. • Actions: Contralateral rotation of the torso. • A triangular-shaped defect in the external oblique aponeurosis is known as the superficial inguinal ring • The spermatic cord (or round ligament of the uterus) passes through this opening and carries the external spermatic fascia • Between the anterior superior iliac spine and the pubic tubercle, the lower border of the aponeurosis is folded backward on itself, forming the inguinal ligament FLAT MUSCLES Internal Oblique • The internal oblique lies deep to the external oblique. It is smaller and thinner in structure, with its fibers running superomedially • Attachments: Originates from the inguinal ligament, iliac crest and lumbodorsal fascia. It inserts onto ribs 10-12. • Actions: Bilateral contraction compresses the abdomen, while unilateral contraction ipsilaterally rotates the torso. FLAT MUSCLES Transversus Abdominis • The transversus abdominis is the deepest of the flat muscles, with transversely running fibers. Deep to this muscle is a well-formed layer of fascia, known as the transversalis fascia. • Attachments: Originates from the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia. It inserts onto the xiphoid process, Linea alba and the pubic crest. • Actions: Compression of abdominal contents. FLAT MUSCLES VERTICAL MUSCLES • There are two vertical muscles located in the midline of the anterolateral abdominal wall, the rectus abdominis and pyramidalis. Rectus Abdominis • The rectus abdominis is long, paired muscle, found either side of the midline in the abdominal wall. 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. • Attachments: Originates from the crest of the pubis bone. It inserts onto the xiphoid process of the sternum and the costal cartilage of ribs 5-7. • Actions: As well as assisting the flat muscles in compressing the abdominal viscera, the rectus abdominis also stabilizes the pelvis during walking, and depresses the ribs 19 December 2023 16 VERTICAL MUSCLES Pyramidalis • This is a small triangular muscle, found superficially to the rectus abdominis. It is located inferiorly, with its base on the pubis bone, and the apex of the triangle attached to the Linea alba. • Attachments: Originates from the pubic crest and pubic symphysis before inserting into the Linea alba. • Actions: Tenses the Linea alba. Surface Anatomy • Many of the organs in the abdominal cavity can be palpated through the abdominal wall, or their position can be visualized by surface markings • The abdomen is a large area, and so it split into nine regions – these are useful clinically for describing the location of pain, location of viscera and describing surgical procedures. The nine regions are formed by two horizontal and two vertical planes: Horizontal planes: o Transpyloric plane – halfway between the jugular notch and the pubic symphysis, approximately the level of the L1 vertebrae. o Intertubercular plane – horizontal line that runs between the superior aspect of the right and left iliac crests. Vertical planes – run from the middle of the clavicle to the mid-inguinal point (halfway between the anterior superior iliac spine of the pelvis and the pubic symphysis). These planes are the mid-clavicular lines. 19 December 2023 20 SURGICAL INCISIONS IN ABDOMINAL WALL • Midline An incision that is made through the Linea alba. It can be extended the whole length of the abdomen by curving around the umbilicus. The linea alba is poorly vascularized, so blood loss is minimal, and major nerves are avoided. It can be used in any procedure that requires access to the abdominal cavity. • Paramedian Similar to the median incision, but is performed laterally to the Linea alba, providing access to more lateral structures (kidney, spleen and adrenals). This method ligates the blood and nerve supply to muscles medial to the incision, resulting in their atrophy. Kocher • A Kocher incision begins inferior to the xiphoid process and extends inferolaterally in parallel to the right costal margin. It is mainly used to gain access for gall bladder and/or biliary tree pathology. • Two modifications and extensions of the Kocher incision are possible: Chevron / rooftop incision or modification the extension of the incision to the other side of the abdomen. This may be used for esophagectomy, gastrectomy, bilateral adrenalectomy, hepatic resections, or liver transplantation Mercedes Benz incision or modification the Chevron incision with a vertical incision and break through the xiphisternum. This may be used for the same indications as the Chevron incision, however classically seen in liver transplantation. McBurney • A McBurney is a called a ‘grid iron’ incision, because it consists of two perpendicular lines, splitting the fibers of the muscles without cutting them – this allows for excellent healing. • McBurney incision is performed at McBurney’s point (1/3 of the distance between the ASIS and the umbilicus) and is used in an open appendicectomy. RETROPERITONEAL SPACE • The retroperitoneal space lies on the posterior abdominal wall behind the parietal peritoneum. • It extends from the 12th thoracic vertebra and the 12th rib to the sacrum and the iliac crests below. • The floor or posterior wall of the space is formed from medial to lateral by the psoas and quadratus lumborum muscles and the origin of the transversus abdominis muscle. • Each of these muscles is covered on the anterior surface by a definite layer of fascia. • In front of the fascial layers is a variable amount of fatty connective tissue that forms a bed for the suprarenal glands, the kidneys, the ascending and descending parts of the colon, and the duodenum. • The retroperitoneal space also contains the ureters and the renal and gonadal blood vessels SUPRARENAL GLANDS 19 December 2023 29 SUPRARENAL GLANDS • Asymmetrical & the weight is ≈ 4 g. • Right is pyramidal and embraces the upper pole of the right kidney. • Left is crescentic and embraces the medial border of the left kidney above the hilum. • They are situated in the retroperitoneum,, within Gerota’s capsule. 19 December 2023 30 ANATOMICAL RELATIONS • Anteriorly: right side—liver, IVC; left side—stomach across the lesser sac. • Posteriorly: the diaphragm. • Inferiorly: the upper pole of the kidney. 19 December 2023 31 STRUCTURE Comprises a cortex and a medulla. Medulla derived from neural crest (ectoderm). Cortex derived from mesoderm. Medulla receives preganglionic sympathetic fibres from the greater splanchnic nerve and secretes adrenaline and noradrenaline. The cortex secretes mineralocorticoids (from zona glomerulosa), glucocorticoids (from zona fasciculata) and sex hormones (from the zona reticularis). 19 December 2023 32 BLOOD SUPPLY • Arterial supply: I. A branch from the aorta. II. A branch from the inferior phrenic artery. III. A branch from the renal artery. • Venous drainage: 1. On the right is via a short vein directly into the IVC. 2. On the left is by a longer vein into the left renal vein. 19 December 2023 33 INGUINAL CANAL 19 December 2023 34 INGUINAL CANAL • Oblique passage intermuscular passage (directs downwards, forwards and medially) in lower abdominal wall. • Passes from deep to superficial inguinal rings. • About 4 cm long. And situated just above the medial half of inguinal ligament. • The inguinal canal transmits the spermatic cord (round ligament in the ) and the ilioinguinal nerve. • It is larger in 19 December 2023 35 INGUINAL LIGAMENT • Formed by the lower border of the external oblique aponeurosis between ASIS and pubic tubercle being folded backwards upon itself. • Its convex outer surface is attached to fascia lata (deep fascia of the thigh) 19 December 2023 36 MID-INGUINAL POINT AND MIDPOINT OF THE INGUINAL LIGAMENT • Mid-inguinal point – halfway between the pubic symphysis and the ASIS (anterior superior iliac spine). The femoral pulse can be palpated here. • Midpoint of the inguinal ligament – halfway between the pubic tubercle and ASIS (the two attachments of the inguinal ligament). The opening to the inguinal canal is located just above this point. 19 December 2023 37 BOUNDARIES OF THE INGUINAL CANAL • Anteriorly— aponeurosis of external oblique (internal oblique laterally). • Posteriorly— transversalis fascia. • Superiorly (roof )— transversalis fascia, internal oblique, and transversus abdominis. • Inferiorly (floor)— inguinal ligament (lacunar ligament medially). 19 December 2023 38 CONTENTS OF THE SPERMATIC CORD THREE VESSELS  Testicular artery  Cremasteric artery  Artery to the vas deferens THREE NERVES  Genital branch of genitofemoral  Autonomic supply tothe testicle  Ilioinguinal nerve - actually lies on the cord and not within it 19 December 2023 39 THREE STRUCTURES  Vas deferens  Pampiniform venous plexus  Testicular lymphatics THREE COVERINGS  External spermatic fascia from the external oblique aponeurosis  Cremasteric fascia from the internal oblique aponeurosis  Internal spermatic fascia from the transversalis fascia 19 December 2023 40 The deep (internal) inguinal ring Is formed by transversalis fascia (TVF), which invaginates to form a covering of the contents of the inguinal canal. Lies 1– 2cm above the inguinal ligament, midway between the symphysis pubis and the anterior superior iliac spine. Immediately lateral to inferior epigastric vessels. The superficial (external) inguinal ring is a V- shaped defect in the aponeurosis of the external oblique, above, and medial to the pubic tubercle. 19 December 2023 41 HESSELBACH’S TRIANGLE (INGUINAL TRIANGLE) an area bounded by: • Inferiorly: the inguinal ligament • Laterally: the inferior epigastric artery • Medially: the lateral border of the rectus muscle. 19 December 2023 42 FEMORAL CANAL • Lies medial to the femoral vein within femoral sheath. • Contains loose areolar tissue and a lymph node known as the lymph node of Cloquet. • The femoral ring is the abdominal opening of the femoral canal. 19 December 2023 43 • Increase in size in the elderly. • The ↑ diameter of the true pelvis in widens the femoral canal. proportionally • In the pelvis, the canal is larger in diameter, thus increasing the risk of femoral herniation. • Similarly, the defect can the defect can increase in size in the elderly. 19 December 2023 44 BOUNDARIES • Anteriorly— inguinal ligament (of Poupart). • Medially— lacunar ligament. • Posteriorly— pectineal ligament. • Laterally— femoral vein. 19 December 2023 45 REFERENCES • O'Connell, P.R., McCaskie, A.W., & Sayers, R.D. (Eds.). (2023). Bailey & Love's Short Practice of Surgery - 28th Edition • Brunicardi F, & Andersen D.K., & Billiar T.R., & Dunn D.L., & Kao L.S., & Hunter J.G., & Matthews J.B., & Pollock R.E.(Eds.), (2019). Schwartz's Principles of Surgery, 11e. 19 December 2023 46 Thank You 19 December 2023 47