GIT 2025 Anatomy Lecture (PDF)

GIT 2025 Anatomy Lecture(1): ANTERIOR ABDOMINAL WALL AND PERITONEUM Layers of the anterior abdominal wall 1- Skin 2- Superficial fascia: consist of; - Camper's fascia - fatty superficial layer - Scarpa's fascia - deep fibrous la...

GIT 2025 Anatomy Lecture(1): ANTERIOR ABDOMINAL WALL AND PERITONEUM Layers of the anterior abdominal wall 1- Skin 2- Superficial fascia: consist of; - Camper's fascia - fatty superficial layer - Scarpa's fascia - deep fibrous layer 3- Deep fascia: no deep fascia 4- Muscle - External oblique abdominal - Internal oblique abdominal - Rectus abdominis - Transverse abdominal muscle - Pyramidalis muscle 5- Fascia transversalis 6- Peritoneum External oblique muscle Origin: Lower 8 ribs. Direction of fibers: downward, foreword and medially. Insertion: - Fleshy fibers: into anterior ½ of the outer lip of iliac crest. - By an aponeurosis: into xiphoid process, linea alba, pubic crest, pubic tubercle and anterior superior iliac spine(ASIS) Ligaments derived from the external oblique - Inguinal ligament : runs from the ASIS to the pubic tubercle. It formed by the free edge of the external oblique. - Lacunar ligament: a crescent-shaped extension of the inguinal ligament, attached to the superior ramus of the pubic bone. - Pectineal ligament: extends from the lacunar ligament along the pelvic brim. 3 GIT 2025 Anatomy Internal oblique muscle Origin: 1- Ilioinguinal origin: from - Lateral ⅔ of upper surface of inguinal ligament. - Anterior ⅔ of intermediate line of iliac crest. 2- Lumbar origin: from thoracolumbar fascia. Direction of fibers: upwards & medially. Insertion: -Fleshy fibers: lower 3 or 4 ribs and their costal cartilages. - By an aponeurosis: attached to 7th, 8th and 9th costal cartilages. xiphoid process, linea alba, pubic crest and pubic tubercle. Transversus abdominis muscle Origin: 1- Costal: from the inner aspects of lower 6 costal cartilages. 2- Lumbar: from thoracolumbar fascia. 3- Ilioinguinal: from the anterior ⅔ of the inner lip of iliac crest and lateral ⅓ of inguinal ligament. # Direction of fibers: transversely Insertion: xiphoid process, linea alba, symphysis pubis NB: The lowermost aponeurotic fibers fuse with corresponding part of the aponeurosis of transversus abdominis, and attach to pubic crest forming the conjoint 4 GIT 2025 Anatomy tendon. Rectus abdominus muscle Origin: - From pubic crest (lateral head). - From symphysis pubis (medial head). Insertion: To the 5th, 6th and 7th costal cartilages and xiphoid process. NB: (The pyramidalis is a small muscle sometimes found overlying the inferior end of rectus abdominis, running from the lineal alba to the pubis.) Rectus sheath Definition: it's an apponeurotic sheath surrounding rectus abdominis and pyramidalis muscles and their associated nerves and vessels. Formed mainly by aponeurosis of three lateral abdominal muscles Contents of the rectus sheath - 2 muscles (rectus abdominins and pramidalis). - 4 vessels (superior epigastric artery and vein+ inferior epigastric artery and vein). - 6 nerves (terminal parts of the lower 5 intercostal nerves and subcostal nerve) For description it is considered at 3 levels: 1- Above the costal margin: - Anterior wall: ext. oblique apponeurosis. - Posterior wall: costal cartilages. 2- from costal margin to midway between umbilicus and pubis (arcuate line). - Anterior wall: ext. oblique apponeurosis+ anterior ½ of internal oblique ms. - Posterior wall: transversus apponeurosis + posterior ½ of internal oblique ms. 3- from previous line to pubis. - Anterior wall: apponeurosis of the 3 abdominal ms. - Posterior wall: deficient( formed by fascia tranversalis) 5 GIT 2025 Anatomy Nerves of the anterior wall - supply the skin, muscles and the parietal peritoneum. - They are derived from the anterior rami of lower 6 thoracic and the 1stlumbar nerves (iliohypogastric and ilioinguinal nerves) Vascular supply of anterior abdominal wall. Arterial supply Venous driange - Superior and Inferior epigastric - above level of umbilicus: artery drained into, - musculo-phrenic artery. 1- Superior epigastric vein. - 10th and 11th Posterior intercostal 2- Lateral thoracic vein. arteries - below level of umbilicus: - Subcostal and lumbar arteries drained into, - Superficial epigastric artery. 1- Inferior epigastric vein. - Deep and Superficial circumflex iliac 2- Superficial epigastric vein. artery. The Inguinal canal The path of descent of testis carries it obliquely through anterior abdominal wall, creating a passageway oriented in an inferomedial direction. Inguinal canal has 2 opening: - Superficial inguinal ring: defect in the aponeurosis of the external oblique muscle, lies immediately above and medial to the pubic tubercle. - Deep inguinal ring: oval opening in fascia transversalis, lies 1cm above the mid- inguinal point. NB: Cremaster muscle origin: From the lower arching fibers of internal oblique ms at middle of inguinal ligament. insertion: U shaped around the spermatic cord, inserted into pubic tubercle. nerve supply: by genitofemoral nerve 6