Regions of the Anterolateral Abdominal Wall PDF

Regions of the Anterolateral Abdominal Wall symptoms and signs of abdominal diseases are located and recorded with reference to regions mapped out on anterolateral abdominal wall abdominal quadrants: anterolateral abdominal wall is divided in...

Regions of the Anterolateral Abdominal Wall symptoms and signs of abdominal diseases are located and recorded with reference to regions mapped out on anterolateral abdominal wall abdominal quadrants: anterolateral abdominal wall is divided into 4 quadrants (upper right, upper left, lower right and lower left quadrants) by a vertical plane and a horizontal plane that intersect at umbilicus vertical and horizontal planes: subcostal plane à horizontal plane that connects lowest points of right and left costal margins (10th costal cartilages) lies at the level of body of L3, near its upper border transtubercular plane- horizontal plane connecting tubercles of right and left iliac crests (lies at the level of body of L5, near its upper border midclavicular plane- vertical plane that passes through midpoint of clavicle and intersects halfway a line connecting anterior superior iliac spine (ASIS) to pubic tubercle 2 midclavicular planes and 2 horizontal planes (subcostal and transtubercular) are used to divide anterolateral abdominal wall into 9 regions: upper part (above subcostal plane): consists of epigastric region or epigastrium (center) and right and left hypochondriac regions middle part (between subcostal and transtubercular planes): consists of umbilical region (center) and right and left lateral regions (lumbar regions or flanks) lower part (below transtubercular plane): consists of pubic, hypogastric region or hypogastrium (center) and right and left inguinal (iliac) regions https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 3 of 38 https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 4 of 38  Layers of the Anterolateral Abdominal Wall (Superficial to Deep) skin superficial fascia muscles with their deep (investing) fasciae transversalis fascia extraperitoneal fascia parietal peritoneum Superficial Fascia divided into 2 layers in lower part of anterior abdominal wall: superficial, fatty layer (Camper’s fascia): continuous with superficial fat over rest of body and may be extremely thick deep, membranous layer (Scarpa’s fascia): on each side, it fuses with fascia lata (deep fascia of thigh) about a fingerbreadth below inguinal ligament and in the midline, it is continuous with superficial fascia of penis (or clitoris), dartos tunic/fascia (scrotum) and superficial perineal fascia (Colles’ fascia) https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 5 of 38  Abdominal Muscles Transversalis Fascia superficial and deep surfaces of flat abdominal muscles are covered by deep (investing) fascia. These fascial layers are unremarkable, except for fascia that covers deep surface of transversus abdominis (transversalis fascia), which is better developed transversalis fascia is part of continuous layer of fascia (endoabdominal fascia) that lines inner surface of abdominal walls à name of fascia changes depending on region or muscle it covers (diaphragmatic fascia, transversalis fascia, iliacus fascia, etc.) Extraperitoneal Fascia layer of loose connective tissue, with a variable amount of fat, located between transversalis fascia and parietal peritoneum Parietal Peritoneum serous membrane that lines inner surface of anterolateral abdominal wall https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 7 of 38  Muscles of the Anterolateral Abdominal Wall 3 broad and thin (flat) muscles on each side: external oblique, internal oblique and transversus abdominis on each side of anterior midline there is a long, vertical muscle (rectus abdominis) there is usually a small muscle anterior to lower part of rectus abdominis called pyramidalis (absent in about 20% of people) 3 flat abdominal muscles are muscular (fleshy) posterolaterally and aponeurotic (fibrous) anteromedially aponeuroses of 3 flat muscles pass medially and enclose rectus abdominis (and pyramidalis, if present) to form rectus sheath in midline of anterior abdominal wall, aponeuroses of 3 right flat muscles join aponeuroses of 3 left flat muscles à form fibrous band (linea alba) that extends from xiphoid process to pubic symphysis External Oblique Origin: outer surface of lower 8 ribs Insertion: on an anterior view, fibers run inferiorly and medially (similar to external intercostals). The lower fibers insert into iliac crest any remaining fibers become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone inguinal (Poupart’s) ligament: lower border of external oblique aponeurosis that extends from ASIS to pubic tubercle and it is folded backward on itself forming the inguinal ligament (forms boundary between abdomen and thigh) superficial inguinal ring- opening in external oblique aponeurosis located immediately superior to pubic tubercle. It is the anterior (superficial) opening of inguinal canal https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 8 of 38  Insertion: on an anterior view, upper fibers run superiorly and medially (similar to internal and innermost intercostals) while lower fibers are more horizontal, upper fibers insert into inferior border of lower 3 or 4 ribs and their costal cartilages à remaining fibers become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone has a lower free border that arches over contents of inguinal canal Transversus Abdominis lies deep to internal oblique Origin: deep surface of lower 6 costal cartilages, thoracolumbar fascia, iliac crest and lateral ⅓ of inguinal ligament Insertion: fibers run horizontally forward à become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone has a lower free border that arches over contents of inguinal canal Rectus Abdominis long strap muscle that extends along whole length of anterior abdominal wall à narrower and thicker below, broader and thinner above à it is separated from its fellow by linea alba Origin: pubic symphysis and pubic crest Insertion: 5th, 6th and 7th costal cartilages and xiphoid process divided into segments by 3 transverse fibrous bands (tendinous intersections or inscriptions) à superior tendinous intersection is just inferior to xiphoid process, inferior one is at the level of umbilicus, middle one is half-way between the other two Pyramidalis small triangular muscle located anterior to lower part of rectus abdominis, within rectus sheath may be absent on one or both sides Origin: anterior surface of body of pubis Insertion: linea alba Action: tensor of linea alba Actions of the Anterolateral Abdominal Muscles their tone plays an important role is supporting and protecting abdominal organs oblique muscles are involved in flexion, lateral flexion and rotation of trunk https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 10 of 38  rectus abdominis flexes trunk transversus abdominis contributes little to trunk movements by contracting simultaneously with diaphragm, with glottis of larynx closed, anterolateral abdominal muscles increase intra-abdominal pressure à help with evacuation of contents of abdominal and pelvic hollow organs (micturition, defecation, vomiting, childbirth) assist in forced expiration (coughing and sneezing) by pulling down ribs and sternum Rectus Sheath (Netter’s Plate 253) formed by aponeurosis of 3 flat abdominal muscles contents: rectus abdominis pyramidalis (if present) terminal parts of lower 5 (7th to 11th) intercostal nerves and subcostal nerve superior and inferior epigastric vessels upper ¾ of anterior abdominal wall- aponeurosis of internal oblique splits into 2 laminae. The anterior lamina joins aponeurosis of external oblique to form anterior wall of rectus sheath and the posterior lamina joins aponeurosis of transversus abdominis to form posterior wall of rectus sheath lower ¼ of anterior abdominal wall-3 aponeuroses pass anterior to rectus abdominis muscle to form anterior wall of sheath. There is no posterior aponeurotic wall. At this level, rectus abdominis muscle is directly related posteriorly to transversalis fascia arcuate line is a curved line that marks lower end of posterior aponeurotic wall of rectus sheath. It is located half-way between umbilicus and pubic symphysis. Inferior to arcuate line, posterior aponeurotic wall of rectus sheath is lacking (aponeurosis of 3 flat abdominal muscles pass anterior to rectus muscle) posterior wall of sheath is not attached to rectus abdominis muscle, but the anterior wall of sheath is firmly attached to tendinous intersections of rectus abdominis muscle https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 11 of 38  Nerves of the Anterolateral Abdominal Wall ventral rami of T7 to T11 spinal nerves (7th to 11th intercostal nerves) ventral ramus of T12 spinal nerve (subcostal nerve) ventral ramus of L1 spinal nerve (iliohypogastric and ilioinguinal nerves) for a large part of their course, these nerves run forward between internal oblique and transversus abdominis 7th to 11th intercostal nerves and subcostal nerve enter rectus sheath and supply rectus abdominis; iliohypogastric and ilioinguinal nerves do not enter rectus sheath nerves of anterolateral abdominal wall provide sensory innervation to skin and parietal peritoneum that line the outer and inner surfaces, respectively, of anterolateral abdominal wall and provide motor innervation to muscles of anterolateral abdominal wall Dermatomes of the Anterolateral Abdominal Wall T7 - just inferior to tip of xiphoid process T10 -level of umbilicus L1 -pubic symphysis and area immediately superior to it https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 12 of 38  arteries of the anterior abdominal wall Arteries of the Anterolateral Abdominal Wall superior epigastric artery- terminal branch of internal thoracic artery (descends posterior to rectus abdominis within rectus sheath and supplies upper central part of anterior abdominal wall. It anastomoses with inferior epigastric artery) inferior epigastric artery- originates from distal part of external iliac artery (just above inguinal ligament) (runs superiorly and medially and enters rectus sheath and ascends posterior to rectus abdominis. It supplies lower central part of anterior abdominal wall. It anastomoses with superior epigastric artery deep circumflex iliac artery -originates from distal part of external iliac artery (just above inguinal ligament) and runs superiorly and laterally toward ASIS. It supplies lower lateral part of anterior abdominal wall 10th and 11th posterior intercostal arteries, subcostal artery and lumbar arteries (they supply lateral part of anterior abdominal wall) superficial epigastric and superficial circumflex iliac arteries (branches of femoral artery) - supply superficial structures of lower part of anterior abdominal wall https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 15 of 38  Veins of the Anterolateral Abdominal Wall (netter’s plate 259) superficial veins: form a network that radiates out from umbilicus --- network drains superiorly into axillary vein and inferiorly into femoral vein and may provide collateral circulation during blockage of either vena cava deep veins (accompany corresponding arteries): superior epigastric vein- drains into internal thoracic vein inferior epigastric and deep circumflex iliac veins- drain into external iliac vein lower posterior intercostal and subcostal veins- drain into azygos (right) or hemiazygos (left) veins lumbar veins- drain into inferior vena cava Lymphatic Drainage of the Anterior Abdominal Wall superficial lymph vessels: above level of umbilicus lymph drains upward toward anterior axillary lymph nodes below level of umbilicus lymph drains downward toward superficial inguinal lymph nodes deep lymph vessels: follow arteries and deep veins and drain into internal thoracic (parasternal), external iliac, posterior mediastinal and lumbar (para-aortic) lymph nodes https://sites.google.com/view/grossanatomyii/week-5-lecture-notes 6/21/24, 1:34 PM Page 16 of 38