Anteriolateral wall Flashcards
Discuss the boundaries or the regions of the abdomen
- 9 regions
- divided by two sagittal planes running through the two midclavicular lines
- two sagittal lines one through the subcostal plane passing through the inferior border of the 10th costal cartilage on each side and the transtubercular plane passing through the iliac tubercles and the body of the L5 vertebrae.
Discuss the fascia of the anterolateral abdominal wall
- Major site of fat storage
- Sub cut tissues has two layers a superficial fatty layer and a deep membranous layer. The membranous layer continues inferiorly into the perineal region as the superifical perineal fascia
- superifical intermediate and deep layers of investing fasica cover the external aspects of the three muscle layers of the anterolateral abdominal wall and their aponeuroses
- The internal aspect of the abdominal wall is lined with a membranous sheet of varying thickness called the endoabdominal fascia. Although continuous different parts of this fascia are named according to the muscle or aponeurosis it is lining
- The portion lining the transverse abdominal muscle and its epnoeurosis the transversalis fascia is relatively firm.
Describe the muscles of the anterolateral abdominal wall
There are five muscles in the anterolateral abdominal wall; three flat msucles and two vertical muscles.
The flat muscles are the internal and external obliques and the transverse abdominal. The msucles fibers of these concentric layers crisscross each other with the fibers of the outer two layers running diagnollay and perpendicular to each other and the fibers of the deep layer running transversely
- All three transverse muscles are continued anteriorly and medially as strong sheet like aponeuroses. Between the midclavicular line and the midlein the aponeuroses form the tough tendinous rectus sheath enclosing the rectus abdominus muscle. The aponeruoses then interweave with their fellows of the opposite side forming a midline raphe the linea alba which extends from the xiphoid to the pubic symphysis.
- The two vertical msucles of the anterolateral abdominal wall are the rectus abdominis and pyramidalis
Describe the Rectus Abdominis
Origin: pubic symphysis and pubic crest
Insertion: xiphoid process and 5th -7th costal cartialges
Innervation: thoracoabdomianl nerves (anterior rami of inferior 6 thoracic nerves)
Action: flexes trunk and compresses abdominal viscera, stabilizes and controls tilt of pelvis
Describe the Transverse abdominus (deepest flat)
Origin: internal surfaces of 7th to 12th costal cartilages, thoracolumbar fascia, iliac crest and lateral third of inguinal ligament
Insertion: Linea alba with aponeurosis of internal oblique, pubic crest and pecten pubis via conjoint tendon
Innervation: thoracoabdomianl nerves (anterior rami of inferior 6 thoracic nerves and first lumbar)\
Action: compresses and support abdominal viscera
Describe the internal oblique (intermediate)
Origin: thoracolumbar fasica, anterior two thirds of iliac crest, and lateral half of inguinal ligament
Insertion: inferior border of 10-12th ribs, linea alba and pectin pubis via conjoit tendon
Innervation: thoracoabdomianl nerves (anterior rami of inferior 6 thoracic nerves and first lumbar)
Action: compresses and support abdominal viscera, flex and rotate trunk
Describe the external oblique(most superficial and largest)
Origin external surfaces of ribs 5-12
Insertion: linea and alba, pubic tubercle and anterior half of iliac crest
Innervation: thoracoabdomianl nerves (t7-11)
Discuss the Rectus Sheath and linea alba
The rectus sheath is the strong incomplete fibrous compartment of the rectus abdominis and pyramidalis. Also found in the rectus sheath are the superior and inferior epigastric arteries and veins, lymphatic vessels and distal portions of the thoracoabdominal nerves (abdominal portion of the anterior rami of spinal nerve t7-12)
- The sheath is formed by the decussation and interweaving of the aponeuroses of the flat abdominal muscles.
- The external oblique contributes to the anterior wall throughout its length.
- The superior two thirds of the internal oblique slits into two layers or laminae at the lateral border of the rectus abdominisa; one laminae passing anterior to the muscle and one posterior
- The realtively thin transverse abdominus fasica covers the inferior quarter of the posterior wall
- The lineas alba running vertically the entire length of the anterior abdominal wall and separating the bilateral rectus sheath, narrows inferior to the umbilicus to the width of the pubic sympth and widens superioly to the width of the xiphoid
Describe the nerves of the anterolateral abdominal wall
- Thoracoabdominal nerves; the distal abdominal parts of the anterior rami of the inferior six thoracic spinal nerves. These are the former inferior intercostal nerves distal to the costal margin. Run between the second and third layers of abdominal muscles
- lateral cutaneous branches of the thoracic spinal nerves t7-9 or 10
- subcostal nerve the alrge anterior ramus of spinal nerve t12
- iliohypogastric and ilioinguinal nerves terminal branches of the anterior ramus of spinal nerve L1
Describe the vascular supply of the anterolateral abdominal wall
The primary blood vessels of the anterolateral abdominal wall are the
- superior epigastric vessels and branches of the msuclophrenic vessels from the internal thoracic vessels
- inferior episgastric and deep circumflex iliac vessels from the external iliac vessels
- superficial circumflex iliac and superficial epigastric vessels from the femoral artery and greater saphenous vein
- posterior intercostal vessels of the 11th intercostal space and anterior branches of the subcostal vessels.
The skin and subcut tissues of the abdominal wall is served by an intricate subcutaneous venous plexus draining superiorly to the internal thoracic vein medially and the lateral thoracic vein laterally and inferiorly to the superior and inferior epigastric veins tributaries of the femoral and external iliac veins respectively.
-Cutaneous veins surrounding the umbilicus anastomose with parumbilcal veins small tributaries of the portal vein that parallel the obliterated umbilical vein
Describe briefly the lymphatic drainage of the anterolateral wall
- Superficial lymphatic superior to the transumbilical plane drain mainly to the axillary lymph nodes though some drain to the parasternal lymph nodes
- Superifical lymphatic vessels inferior to the trans umbilical plane drain to the superficial inguinal lymph nodes.
- Deep lymphatic follow deep vessels and drain into the the external iliac, common iliac and right and left lumbar lymph nodes
Describe the internal surface of the anterolateral abdominal wall
The internal surface of the anterolateral abdominal wall is covered with transversalis fascia a variable amount of extraperitoneal fat and parietal peritoneum. There are five umbilical peritoneal folds two on each side and one in the median plane
- The median umbilical fold forms the apex of the urinary bladder to the umbilicus and covers the median umbilical ligament
- Two medial umbilcal folds lateral to the median umbilical fold cover the medial umbilcal ligaments
- two lateral umbilical folds lateral to the medial umbilical folds cover the inferior epigastric vessels and therefore bleed if cut
Discuss the peritoneal fossae
Depressions lateral to the umbilical folds and are a site of potential herniation
- Supravesical fossa between the median and the medial umbilical folds, formed as the peritoneum reflexts from the anterior wall onto the bladder
- Medial inguinal fossae between the medial and lateral umbilical folds areas aslo commonly called inguinal triangles (hesselbach traingles) which are potential sites for the less common direct inguinal hernias
- lateral inguinal fossae lateral to the lateral umbilical folds include the deep inguinal rings and are potential istes ofr the most common type of hernia in the lower abdominal wall the indirect hernia.
Discuss the falciform ligament
The supraumbilical part of the internal surface of the anterior abodomainl wall has a sagittally oriented peritoneal refelction, the falciform ligmanet, that extends between the superior anterior abodmuinla wall and the liver. It encloses the round ligament of the liver and paraumbilical veins in its inferior free edge . The round ligament is a fibrous remnant of the umbilical vein which extened from the umbilicus to the liver prenatally
