University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2024
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275

Pages:

57
Author:

hivalye6w

9 & 10 Abdominal wall & ing Learning Objectives At the end of the lecture, students should be able to: • • • • Define the abdominal wall and inguinal region. Enlist the layers. Identify the blood and nerve supply. Applied anatomy The two topographical division patterns of the abdomen are: ■ Four-quadrant pattern ■ Nine-region pattern. A horizontal transumbilical plane passing through the umbilicus (intervertebral disc between vertebrae L3 and L4) and intersecting with the vertical median plane divides the abdomen into four quadrants. The two topographical division patterns of the abdomen are: ■ Four-quadrant pattern ■ Nine-region pattern. It is based on two horizontal and two vertical planes: ■ Subcostal plane: inferior to the costal margins, at level of vertebra L3. (transpyloric plane, halfway between the jugular notch and the symphysis pubis, at level of vertebra L1, is used instead.) ■ Intertubercular plane: connects the tubercles of the iliac crests, vertebra L5. ■ Midclavicular planes pass inferiorly from the midpoint of the clavicles. Alternatives: groin (inguinal region); the flank (lateral region). Some clinicians use the transpyloric and interspinous planes to establish the nine regions. Transpyloric plane Interspinous plane Midclavicular planes Layers of the anterior abdominal wall: 1- Skin. 2- Superficial fascia: 2 layers a). Superficial fatty layer (Camper’s fascia). b). Deep membranous layer (Scarpa’s fascia). 3- Deep Fascia (thin layer) 4- Muscular layers: a. External oblique m. b. Internal oblique m. c. Transversus abdominis m. 5- Transversalis fascia. 6- Extraperitoneal fatty tissue 7- Parietal peritoneum Superficial Fascia The fatty layer: - Continuous with the superficial fat over the rest of the body. - In the scrotum, is represented as a thin layer of smooth muscle (dartos muscle). The membranous layer: - Thin and fades out laterally and above. - Fuses with the deep fascia of thigh one fingerbreadth below the inguinal ligament. In women, it continues into the labia majora and the anterior part of the perineum. Clinical Note: Arrows indicate paths taken by urine in cases of ruptured urethra (B). Rupture of the penile urethra may be followed by extravasation of urine into the scrotum, perineum, and penis and then up into the lower part of the anterior abdominal wall deep to the membranous layer of fascia. The urine is excluded from the thigh because of the attachment of the fascia to the fascia lata (A). Three layers of muscles of anterolateral abdominal wall External Oblique Muscle Origin: External surfaces of 5th–12th ribs. Direction of fibers: Downward, forward, and medially. Continues toward midline as aponeurosis. Insertion: Anterior ½ of outer lip of iliac crest. Pubic tubercle Linea alba. Innervation: Inferior six thoracic nerves and subcostal nerve (T7-T12). Function: Compresses and supports abdominal viscera; flexes and rotates trunk. Associated ligaments The lower border of the external oblique aponeurosis forms the inguinal ligament on each side. Inguinal ligament passes between the anterior superior iliac spine laterally and the pubic tubercle medially. Lacunar ligament Pectineal ligament v Superficial Inguinal Ring: A triangular-shaped defect in the external oblique aponeurosis lies immediately above and lateral to the pubic tubercle. It has 2 crura, (lateral and medial). The lateral crus attaches to pubic tubercle & the medial crus attaches to pubic crest. Its base is formed by the lateral part of pubic crest. .R Dr e A fa t bo eh a zl h G Superficial Inguinal Ring: Internal Oblique Muscle Origin: • Lumbar fascia. • Iliac crest, • Lateral 2/3 of inguinal ligament, Direction of fibers: Upward forward and medially (at right angle with the fibers of external oblique). Insertion: • Lower 3 ribs and their costal cartilages, • Aponeurosis ending in linea alba, • Pubic crest • Pectineal line. Innervation: (T7-T12) + L1 Transversus Abdominis m Origin: • • • • Lumber fascia Inner lip of iliac crest Lateral 1/3 of inguinal ligament Lower 6 costal cartilages. Direction of fibers: Horizontally. Insertion: • Xiphoid Process • Linea alba • Pubic crest • Pectineal line Innervation: (T7-T12) + L1 Function: compress abdominal contents. The conjoint tendon A tendon formed by joining of both lowest tendinous fibers of the internal oblique and transversus muscles. • It is fixed to the pubic crest and the pectineal line, and medially to the linea alba. • It has a lateral free border. Rectus Abdominis Muscle Origin: It has 2 heads, originate from: Pubic crest, Pubic tubercle Front of symphysis pubis. Insertion: Into 5th, 6th, & 7th costal cartilages and xiphoid process. It is a strap muscle that extend along the whole length of the anterior abdominal wall. - It shows transverse tendinous intersections. - The muscle lies within the Rectus Sheath !!! The rectus abdominis muscle is divided into distinct segments by three transverse tendinous intersections: § One at the level of the xiphoid process § One at the level of the umbilicus § One halfway between these two. These intersections are strongly attached to the anterior wall of the rectus sheath. Rectus Sheath An aponeurotic tendinous sheath formed by a unique layering of the aponeuroses of the: o External oblique m o Internal oblique m o Transversus abdominis muscles. The rectus sheath: • Encloses anterior and posterior surfaces of upper three-quarters of the rectus abdominis. • It covers the just anterior surface of the lower one-quarter of the muscle, and no sheath covers the posterior surface. • The point of transition between upper 3 and lower quarter is an arch of fibers known as arcuate line. • The muscle at and below arcuate line is in direct contact with the transversalis fascia. Dr. Refat AboGhazleh Umbilicus Arcuate line ASIS Arcuate line: located at a midway between umbilicus and the pubic symphysis. Or located at the same level of anterior superior iliac spine. Contents of Rectus Sheath 2 Muscles: § Rectus Abdominis § Pyramidalis 2 Vessels: Superior & inferior epigastric arteries and veins. Nerves: Anterior rami of spinal nerves T7-T12. Lymphatic vessels Pyramidalis Muscle Origin: Pubic symphysis Pubic crest Insertion: Linea alba Linea Alba and Semilunaris § Linea Alba: A vertical midline fibrous band that extends from xiphoid process to the symphysis pubis. Formed by the fusion of the aponeurosis of the abdominal wall. § Linea Semilunaris A curved ridge formed by lateral margin of rectus abdominis muscle. Extends from the tip of the ninth costal cartilage to the pubic tubercle. Inguinal Region § The groin (inguinal region) is the area of junction between the anterior abdominal wall and the thigh. § It extends between the ASIS and pubic tubercle. § Surgically and anatomically, it is an important area where structures enter and exit the abdominal cavity. § It is a potential site for herniation. § In fact, the majority of all abdominal hernias, occur in this region in particular the inguinal hernia. Inguinal Canal Inguinal canal • It is an intramuscular passage in the lower medial part of anterior abdominal wall. • It runs just above and parallel to the medial half of the inguinal ligament. • It is about 4 cm length in adult. • It connects between the superficial and deep inguinal rings. ## The contents of the canal are: o Genital branch of genitofemoral nerve. o Spermatic cord in male, or round ligament of the uterus in female. o Ilioinguinal nerve pass through part of it in both sexes . v Superficial Inguinal Ring: Repeated Slide A triangular-shaped defect in the external oblique aponeurosis lies immediately above and lateral to the pubic tubercle. It has 2 crura, (lateral and medial). The lateral crus attaches to pubic tubercle & the medial crus attaches to pubic crest. Its base is formed by the lateral part of pubic crest. Superficial Inguinal Ring: Repeated Slide Deep Inguinal Ring § It is an opening in the fascia transversalis 1 cm above the middle of the inguinal ligament (midpoint of inguinal ligament). § It lies lateral to the inferior epigastric vessels. Borders of Inguinal Canal Anterior Wall: § Aponeurosis of External oblique muscle along its entire length. § Internal oblique muscle along lateral half. Posterior Wall: • Fascia Transversalis along its entire length. • Conjoint tendon along the medial part. • Reflected ligament along the medial part. Borders of Inguinal Canal Borders of Inguinal Canal Floor: medial half of Inguinal ligament supported medially by the lacunar ligament. Roof: Arching fibers of internal oblique and transversus abdominis muscles. Spermatic Cord The spermatic cord is a collection of structures that pass from each testis through the inguinal canal to the abdominal cavity. Coverings 1- External spermatic fascia 2- Cremasteric fascia 3- Internal spermatic fascia Structures of the spermatic cord • Vas deferens / Ductus deferens • Artery of the vas deferens • Testicular artery • Testicular veins (pampiniform plexus) • Testicular lymph vessels • Remnant of processus vaginalis • Autonomic nerves • Genital branch of genitofemoral nerve, which supplies the cremaster muscle & dartos muscle. Mechanics of the Inguinal Canal Although inguinal canal is a potential weak point in the anterior abdominal wall, but it is supported in different ways: • It is directed obliquely. • Anterior wall of the canal is reinforced laterally by the internal oblique muscle in front of the deep ring. • Posterior wall of the canal reinforced medially by the conjoint tendon behind the superficial ring. • On coughing and straining (micturition and defecation) the arching lower fibers of the internal oblique and transversus abdominis contract and flatten the roof of the canal, compressing the contents of the canal against the floor so that the canal is virtually closed. • In great straining (defecation and parturition), the person naturally assumes squatting position, in which the anterior abdominal wall is protected by the thighs. Abdominal Hernias Definition A protrusion of part of the abdominal contents beyond the normal confines of the abdominal wall. Parts: 1. Hernial Sac • • It is a pouch of peritoneum (diverticulum) It has neck and body. 2. Hernial Coverings • Formed by the layers of abdominal wall. 3. Hernial Content • Any structure found within the abdominal cavity (usually loop of intestine or part of greater omentum). Abdominal Herniae • • • • Inguinal (direct or indirect). Femoral. Umbilical (congenital or acquired). Epigastric. • Separation of the recti abdominis muscles. • Hernia of linea semilunaris (Spigelian hernia). • Internal hernia. Indirect (Oblique) Inguinal Hernia o Most common form of hernia. o Mainly congenital in origin. o 20 times more common in men than in women. o 30 % bilateral. o More common on the right side, WHY? o More common in children and young adults. § The hernial sac enters the inguinal canal through the deep inguinal ring lateral to the inferior epigastric vessels. § Located inside the remains of processus vaginalis. § Its extension depends on the state of obliteration of the processus vaginalis. § Hernial sac may extend above and medial to the pubic tubercle. § May extend down to the scrotum or (labium majus). Direct Inguinal Hernia • 15 % of inguinal herniae • Common in old men with weak abdominal wall, rare in women. • Hernial sac bulges medial to the inferior epigastric vessels in the inguinal triangle (Hesselbach’s triangle). • The neck of the hernial sac is wide. Right inguinal triangle. Internal view. • Because both inguinal hernia types exit the superficial ring, palpation of an impulse at this site does not discriminate type. • Detection of an impulse at the superficial ring and a mass at the site of the deep ring suggests an indirect hernia. • Palpation of a direct inguinal hernia is performed by placing the palmar surface of the index and/or middle finger over the inguinal triangle and asking the person to cough or bear down (strain). If a hernia is present, a forceful impulse is felt against the pad of the finger. The finger can also be placed in the superficial inguinal ring; if a direct hernia is present, a sudden impulse is felt medial to the finger when the person coughs or bears down. Femoral Hernia • The hernial sac descends through the femoral canal within femoral sheath. • More common in women !! • The neck of the sac lies below and lateral to the pubic tubercle. • The neck of the sac is narrow and lies at the femoral ring. • Because of the narrow neck, it is often irreducible and may become strangulated. Umbilical Herniae A. Congenital Umbilical Hernia Caused by failure of part of the midgut loop (physiological hernia) to return to the abdominal cavity during fetal development. B. Acquired Infantile Umbilical Hernia § Small hernia caused by a weakness of the umbilical scar at the linea alba. § Occurs in children and often disappears without treatment. C. Acquired Umbilical Hernia of Adults • known as A paraumbilical hernia. • Caused by a weakness of linea alba in the region of the umbilicus. • More common in women especially with repeated pregnancy. Epigastric Hernia • Occurs through the linea alba anywhere between the xiphoid process and the umbilicus. • Usually a small hernia. • Common in middle-aged manual workers men. Separation of the Recti Abdominis • The hernial sac lies between the medial margins of the 2 recti. • Common in elderly multiparous women. • Caused by a weakness of the recti muscles. Incisional Hernia • A postoperative incisional hernia • Large hernial sac Causes: - Damage to segmental nerve supplying the muscles of the anterior abdominal wall. - Postoperative infection with necrosis of the muscles. Hernia of Linea Semilunaris • Known as Spigelian hernia • Rare type • Occurs through the aponeurosis of transversus abdominis lateral to the rectus sheath. • Usually below the level of the umbilicus. Iliopubic Tract • It is the thickened inferior margin in the fascia transversalis. • It appears as a fibrous band running deep (posterior) to the inguinal ligament. • During laparoscopy it is seen as it bridges the structures traversing the subinguinal space, through which the flexors of the hip joint and the neurovascular bundle pass to the lower limb. The inguinal ligament and Iliopubic tract span an area of weakness in the groin called the myopectineal orifice. Iliopubic tract • Demarcates between, the inferior margin of the deep inguinal ring, and the superomedial margin of the femoral ring. • It is a useful landmark during laparoscopic repair of the inguinal hernia. Internal Surface of the Anterolateral Abdominal Wall The posterior surface of the anterolateral abdominal wall is covered by fascia transversalis. Five umbilical peritoneal folds are seen. o Median umbilical fold: Extends from apex of urinary bladder to umbilicus, (obliterated urachus). o Two medial umbilical folds: Obliterated distal part of the umbilical artery. o Two lateral umbilical folds: The peritoneum covers the Inferior Epigastric vessels, so it bleeds if it is injured. Fossae in-between the Umbilical Folds (A) Supravesical Fossae: between the median and the medial umbilical folds. It is rarely to see supravesical hernias. C B (B) Medial Inguinal Fossae: Between medial & Lateral umbilical folds. It is also called inguinal or Hesselbach triangle (Potential site for direct inguinal hernia). (C) Lateral Inguinal Fossae: Lateral to lateral umbilical folds (including deep inguinal ring – Potential site for indirect or oblique inguinal hernias). A Anterolateral Abdominal Wall Arteries o Internal Thoracic Artery • Superior Epigastric Artery o External Iliac Artery • Inferior Epigastric Artery • Deep Circumflex Iliac Artery o Femoral Artery • Superficial Epigastric Artery • Superficial Circumflex Iliac Artery

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