THE ABDOMINAL WALL OUTLINE Abdominal wall Divisions of

THE ABDOMINAL WALL

OUTLINE • Abdominal wall. • Divisions of anterior abdominal wall • Layers of anterior abdominal wall. • Fascia, muscles of anterior abdominal wall. • Posterior abdominal wall • Fascia of posterior abdominal wall 1/24/2022 2

Abdominal wall • Abdominal wall represents the boundaries of the abdominal cavity. Located between the diaphragm and pelvic inlet The abdominal wall is split into • Posterior (back), • Lateral (sides) and • Anterior (front) walls. • Because there is no clear cut demarcation between the anterior and lateral wall, it is sometimes therefore referred to 1/24/2022 as the anteriolateral wall 3

ANTERIOLATERAL/ ANTERIOR ABDOMINAL WALL Borders of the Abdomen • Superior: Costal cartilages 7 -12. • Xiphoid process: Level of 10 th cartilage • Inferior: Pubic bone and iliac crest: Level of L 4. • Anterolateral Borders: The muscles of abdominal wall. • Posteriorly: Lumbar Vertebrae and Quadratus Lumborum muscle. • Umbilicus: Level of IV disc L 3 -4 1/24/2022 4

DIVISIONS OF AAW • Abdominal Quardrants are formed by two intersecting lines: Intersect at umbilicus. • Quadrants: Right Upper. Left Upper. Right Lower. Left Lower. 1/24/2022 5

DIVISIONS OF AAW • Divided into 9 regions by two pairs of planes: Vertical Planes: • Left and right lateral planes = midclavicular planes Horizontal Planes: • Transpyloric plane: Midway between jugular notch and pubic symphysis (between xiphoid and umbilicus). • Intespinous plane: Through ASIS • NOTE: Subcoastal and intertubercular can be used too 1/24/2022 6

Abdominal Regions • Right and left hypochondriac: Contain liver • Epigastric: Contains: liver, stomach, pancreas • Right and left lateral (lumbar): Right contains ascending colon. Left contains descending colon. 1/24/2022 7

Abdominal Regons • Umbilical: Contains small intestine and transverse colon. • Right and left inguinal: Right contains ilieocecal junction and appendix. Left contains sigmoid colon. • Hypogastric: Contains small intestine, urinary bladder (full), pregnant uterus. 1/24/2022 8

Lines of the Anterior Abdominal Wall • Linea alba: Located along the midline = connective tissue raphe. • Linea semilunaris: Along each lateral border of rectus abdominis. • • Linea transversa: Tendinous bands of rectus abdominis 1/24/2022 9

The Umblicus • A scar tissue formed after the umbilical cord is severed at birth • Structures attached to the umbilicus in the internal/posterior surface of the AAW • Falciform ligament • Median umbilical fold • 2 Medial umbilical folds • 2 Lateral umbilical folds • Nerve supply: T 10 (10 th segmental spinal nerve) • Aterial supply: superficial epigastric atery • Venous drainage: superficial epigastric and paraumbilical veins 1/24/2022 10

Folds on Posterior Surface (of anterior wall) Median umbilical fold: • Midline peritoneal fold on inner abdominal wall above bladder. Contains median umbilical ligament: • Remnant of embryonic urachus. Medial umbilical fold: • Paired peritoneal folds on either side of median fold. Contain medial umbilical ligaments: • Remnants of umbilical arteries. 1/24/2022 11

Folds on Posterior Surface (of anterior wall) Lateral umbilical fold: • Paired peritoneal folds lateral to medial folds. Contain inferior epigastric vessels: • From deep inguinal ring to arcuate line. Falciform ligament: • Double layer of peritoneum. • Attaches liver to anterior abdominal wall and to inferior surface of diaphragm. • Contains ligamentum teres hepatis (round ligament of liver): • Remnant of left umbilical vein. 1/24/2022 12

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Layers of anterior abdominal wall • The layers of the abdominal wall are (from superficial to deep): • Skin • Superficial Fascia – Camper's fascia - fatty superficial layer. – Scarpa's fascia - deep fibrous layer. • Deep fascia • muscle – – – External oblique abdominal muscle Internal oblique abdominal muscle Transverse abdominal muscle Rectus abdominis Pyramidalis muscle • Fascia transversalis • Extraperitoneal fascia • Peritoneum 1/24/2022 • The Skin: • the skin over the AAW is relatively thin. • Its crease runs along the cleavage lines • Incisions of the AAW must be done along the direction of the muscular fiber, otherwise a scar tissue may be formed during healing. • The skin can withstand stretch especially in pregnancy 14

Superficial Fascia Camper’s fascia: fatty layer • Fatty layer and areolar in texture, and contains in its meshes a varying quantity of adipose tissue. • In females, it is well developed where the fat functions to insulate the fetus • Continuous with superficial fascia over thorax superiorly and thigh inferiorly. Scarpa’s fascia: Membranous layer. • It continues into the anterior part of the perineum where it is firmly attached to the ischiopubic rami and to the posterior margin of the perineal membrane. • Here, it is referred to as the superficial 1/24/2022 perineal fascia (Colles' fascia) 15

Superficial Fascia (membranous layer) • Laterally, it enters the thigh and fuse with the fascia lata of the thigh. • In men, medially and below, it continues over the penis and fuse with the fascia penis of buck • Continues into the scrotum where it forms a specialized fascia (the dartos fascia). • From the scrotum, it is further reflected into the perineum where it is called the colles fascia. • In the female, it is continued into the labia majora and from there into the peritoneum to the fascia of Colles. Deep: fascia: Thin layer covering abdominal muscles. 1/24/2022 16

• 5 muscles • • Muscle Layers 3 horizontal flat muscles External oblique. Internal oblique. Transversus abdominus. • 2 vertical strap muscles • Rectus abdominus • Pyrimidalis 1/24/2022 17

External oblique • Most superficial of the three flat muscles • Immediately deep to the superficial fascia. • Large aponeurotic component covers the anterior part of the abdominal wall to the midline 1/24/2022 18

Extensions of external oblique • The lower border of the external oblique aponeurosis forms the inguinal • ligament on each side. • This thickened reinforced free edge of the external oblique aponeurosis passes between the anterior superior iliac spine laterally and the pubic tubercle • medially. • Lacunar ligament is a crescent-shaped extension of fibers at the medial end of the inguinal ligament that pass backward to attach to the pecten pubis on the superior ramus of the pubic bone. • Additional fibers extend from the lacunar ligament along the pecten pubis of the pelvic brim to form the pectineal (Cooper's) ligament. 1/24/2022 19

Internal oblique muscle • Deep to the external oblique muscle is the internal oblique muscle • This muscle is smaller and thinner than the external oblique, with most of its muscle fibers passing in a superomedial direction. • Its lateral muscular components end anteriorly as an aponeurosis that blends into the linea alba at the midline 1/24/2022 20

Transversus abdominis • Deep to the internal oblique muscle is the transversus abdominis muscle. • So-named because of the direction of most of its muscle fibers. • It ends in an anterior aponeurosis, which blends with the linea alba at the midline 1/24/2022 21

Rectus abdominis muscle Two parallel muscles • Separated by a midline band of connective tissue called the linea alba Attachment: Arise by two heads • Medial head: Pubic symphysis • Lateral: Pubic crest, • N/S: Anterior rami of lower seven thoracic spinal nerves (T 7 to T 12) • Functions: Compresses abdominal contents; • Flexes vertebral column & tense abdominal wall. 1/24/2022 22

Pyramidalis • Small triangular muscle Attachment • Front of pubis and pubic symphysis • Insertion: linea alba. • Anterior ramus of T 12 • Function: Tenses the linea alba • Nerve supply: subcoastal nerve 1/24/2022 23

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Transversalis fascia • Each of the three flat muscles is covered on its anterior and posterior surfaces by a layer of investing abdominal fascia. • These layers are unremarkable except for the layer deep to the transversus abdominis muscle (the transversalis fascia), which is better developed 1/24/2022 25

Extraperitoneal fascia and Peritoneum • Deep to the transversalis fascia is a layer of connective tissue, the extraperitoneal fascia, which separates the transversalis fascia from the peritoneum Peritoneum • Deep to the extraperitoneal fascia is the peritoneum. • This thin serous membrane lines the walls of the abdominal cavity and, at various points, reflects onto the abdominal viscera, providing either a complete or a partial covering 1/24/2022 26

Nerve Supply • Cutaneous Nerves • The skin and muscles of the anterolateral abdominal wall are supplied by T 7 to T 12 and L 1 spinal nerves. • Ventral rami of T 7 through T 11: = thoracoabdominal nerves. • T 7 to dermatome over xiphoid process. • T 10 at level of umbilicus. • Subcostal nerve – pyramidalis • Ventral ramus of L 1: Gives rise to: iliohypogastric nerve. ilioinguinal nerve 1/24/2022 27

Nerve supply of the AAW 1/24/2022 28

Arterial supply • Superior part of the wall: Musculophrenic artery and Superior epigastric artery, a terminal branch of the internal thoracic artery. • Lateral part of the wall • 10 th and 11 th intercostal arteries • Subcostal artery • • Inferior part of the wall Inferior epigastric artery Superficial and deep circumflex iliac artery, both branches of the femoral artery 1/24/2022 29

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Venous Drainage 1/24/2022 31

Lymphatic Drainage Superficial lymphatics: • Above the umbilicus: Drain into the axillary and sternal nodes. • Below the umbilicus: Drain into the superficial inguinal nodes. Deep lymphatic drainage • Follows the deep arteries back to parasternal nodes along the internal thoracic artery, • lumbar nodes along the abdominal aorta • external iliac nodes along the external iliac artery. 1/24/2022 32

Applied Anatomy 1) Liposuction is a surgical method for removing unwanted subcutaneous fat using a percutaneously placed suction tube and high vacuum pressure. • The tubes are inserted subdermally through small skin incisions. • When closing abdominal skin incisions inferior to the umbilicus, surgeons include the membranous layer of subcutaneous tissue when suturing because of its strength. 2) Protuberance of Abdomen: A prominent abdomen is normal in infants and young children because their gastrointestinal tracts contain considerable amounts of air. • An infant’s and young child’s relatively large liver also accounts for some bulging. In adults, protruding abdomen can be as a result of any or more of the following; food, fluid, fat, feces, flatus, and fetus. • Eversion of the umbilicus may be a sign of increased intra-abdominal pressure, usually resulting from ascites (abnormal accumulation of serous fluid in the peritoneal cavity), or a large mass (e. g. , a tumor, a fetus, or an enlarged organ such as the liver). 1/24/2022 33

Applied Anatomy • Excess fat accumulation owing to overnourishment most commonly involves the subcutaneous fatty layer; however, there may also be excessive depositions of extraperitoneal fat in some types of obesity. • Tumors and organomegaly (organ enlargement such as splenomegaly—enlargement of the spleen) also produce abdominal enlargement. When the anterior abdominal muscles are underdeveloped or become atrophic, as a result of old age or insufficient exercise, they provide insufficient tonus to resist the increased weight of a protuberant abdomen on the anterior pelvis. • The pelvis tilts anteriorly at the hip joints when standing (the pubis descends and the sacrum ascends) producing excessive lordosis(sway back) of the lumbar region. 1/24/2022 34

Applied Anatomy 3) Abdominal Hernias: Most hernias occur in the inguinal, umbilical, and epigastric regions. • Umbilical hernias are common in newborns because the anterior abdominal wall is relatively weak in the umbilical ring, especially in low-birth-weight infants. • Umbilical hernias are usually small and result from increased intraabdominal pressure in the presence of weakness and incomplete closure of the anterior abdominal wall after ligation of the umbilical cord at birth. 4) Superficial Abdominal Reflexes: With the person supine and the muscles relaxed, the superficial abdominal reflex is elicited by quickly stroking horizontally, lateral to medial, toward the umbilicus. Usually, contraction of the abdominal muscles is felt; this reflex may not be observed in obese people 1/24/2022 35

Applied Anatomy • 5)Abdominal Surgical Incisions 1/24/2022 36

POSTERIOR ABDOMINAL WALL 1/24/2022 37

POSTERIOR ABDOMINAL WALL (contents) The posterior abdominal wall is musculoskeletal and mainly composed of • The five lumbar vertebrae and their associated intervertebra disc • Posterior abdominal muscles and diaphragm • Posterior abdominal wall fascia • Nerves, vessels and lymph nodes 1/24/2022 38

Muscles of PAW • Muscles forming the medial, lateral, infereior and superior boundaries of the posterior abdominal region fill the bony framework of the PAW • Medially are the psoas major and minor • Laterally is the quardratus lumborum • Inferiorly is the iliacs muscle • Superiorly is the diaphragm 1/24/2022 39

Muscles of PAW PSOAS MAJOR: ORIGIN • (a). Bodies of lumber vertebrae. (b). Lumber intervertebral discs. • (c). Fibrous arches spanning the concavities of sides of upper vertebral bodies. (d). Medial ends of all the lumber transverse processes. • INSERTION • Tendon is attached to the lesser trochanter of femur. • Nerve Supply: First three lumber nerves (mainly L 2). • ACTIONS • Power flexor of hip joint. • Lateral flexor of vertebral column. • With iliacus and their fellows of opposite side it assist in the flexion of the trunk produced by anterior abdominal wall muscles. 1/24/2022 40

Muscles of PAW Psoas Minor • Slender and lie on surface of the psoas major • Present in two third of the population Origin: T 12 and L 1 vertebrae and intervening disc Insertion: its long tendon blend with the psoas major and inserts onto the pectinial line of pelvic brim and iliopubic eminence Nerve Sypply: L 1 spinal nerve Action: weak flexor of the lumber spine 1/24/2022 41

Muscles of PAW QUARDRATUS LUMBORUM • Flat sheet. Lying in the deep paravertebral gutter. • Edge to edge with psoas medially and transverse abdominis laterally. • ORIGIN: Transverse process of L 5 vertebrae through the Iliolumbar ligament. Internal lip of iliac crests. • • Insertion: transverse process of L 1 to L 4 vertebrae Medial half of Inferior border of 12 th rib • • ACTION: Prevent diaphragm from elevating 12 th rib during inspiration. Depress 12 th rib it aids descent of contracting diaphragm. Lateral flexor of lumbar spine. • • • NERVE SUPPLY Subcostal nerve. Upper three or four lumbar nerves. • • 1/24/2022 42

Muscles of PAW • ILIACUS: triangular shaped • ORIGIN • Upper 2/3 rd of iliac fossa up to the inner lip of iliac crest and from anterior sacroiliac ligament • Insertion: passes under the inguinal ligament and • inserts into the psoas tendon and • adjacent part of femur below the lesser trochanter • Nerve Supply: Femoral nerve L 2, L 3. • Action: flexion of the thigh at the hip joint 1/24/2022 43

Fascia of PAW • Each of the muscle of posterior abdominal wall is covered by fascia which blends at margins of muscles. PSOAS FASCIA • Invests the surface of muscles. • Attached to the vertebral bodies, fibrous arches and transverse process and iliopubic eminence. • It is not part of lumbar fascia. • Its lateral edges blends with anterior layers of lumber fascia (over quadratus lumborum muscle). • Psoas fascia thicken from body of L 1 (or L 2) to transverse process of L 1 to form medial arcuate ligament. • Retains the pus of a psoas abscess • Spinal tuberculosis may present as Cold abscess in the groin 1/24/2022 44

Fascia of PAW Iliacus fascia • Iliacus muscles is covered by iliac fascia. • Attached to the bone at the margins of muscle and to inguinal ligament. • Fascia is continuous with psoas fascia. 1/24/2022 45

Fascia of PAW LUMBER FASCIA: lumber part of thoracolumber fascia • Three layers of fascia (ant, middle and post. ) enclose two muscular compartments • Anterior and middle layer occupy lumbar region. • Posterior layer extends above to the neck and below to the dorsal surface of sacrum. • Quadratus lumborum occupy the anterior compartment. • Erector spinae fills the posterior compartment. 1/24/2022 46

Fascia of PAW ANTERIOR LAYER • Extends from front of iliolumbar ligament and adjoining iliac crest to the lower border of 12 th rib. • Medially attached to the front of transverse process and adjoining attachments to the psoas fascia. • Laterally it blends with middle layer along the lateral border of Quadratus lumborum. 1/24/2022 47

Fascia of PAW • MIDDLE LAYER: from back of iliolumber ligament and adjoining iliac crest up to 12 th rib • Medially attached to the tip of the lumber transverse processes. • Laterally, it blends with the ant. and post. Layers. • Line of fusion is along the lateral border of erector supinae 1/24/2022 48

Fascia of PAW • POSTERIOR LAYER: Lies over the whole erector spinae mass of muscle. • Attached medially to the spinous processes and supraspinous ligament of all sacral lumber and thoracic vertebrae. • Its lateral margins extends upwards along the transverse tubercles from where it slopes out wards to the 12 th rib. 1/24/2022 49

Blood Supply of the PAW 1/24/2022 50

Nerve Supply of the PAW • Lumber and its Branches: Iliohypogastric nerve, Ilioinguinal nerve, Genitofemoral nerve, Lateral cutaneous nerve of thigh, Femoral nerve, Obturator nerve, Lumbosacral trunk • Autonomic nerves • Sympathetic and • Parasympathetic nerves 1/24/2022 51

Nerve Supply of the PAW 1/24/2022 52

Lymph Nodes and Lymph Trunks of PAW • Preaortic nodes • Para-aortic nodes • Cisterna chyli 1/24/2022 53

APPLIED ANATTOMY • 1) PSOAS ABSCESS: an infection eg tuberculosis can be spread to the vertebrae through the blood (hematogenous spread). • An abscess from TB in the lumber region tend to spread from the lumber vertebrae into the psoas sheath where it may for psoas abscess. • Pus from this psoas abscess passes inferiorly within the fascia tube over the pelvic brim and deep to the inguinal ligament and usually surface on the upper part of the thigh • Pus can also reach the psaos sheath by passing from the posterior mediastinum when the thoracic vertebrae are diseased 1/24/2022 54

APPLIED ANATTOMY 2) Posterior abdominal pain: when any of the structures related to the PAW like (kidney, pancreas, ureters, cecum, appendix etc) is diseased, movement of the iliopsaos usually cause pain. • And when the intra abdominal inflammation is suspected in abdominal pain, iliopsoas test is performed • The person is asked to lie on the unaffected side and extend the thigh of the affected side against the resistance of the examiner’s hand • Elicitation of pain with this maneuver is a 1/24/2022 positive psoas sign 55

APPLIED ANATTOMY • An acutely inflamed appendix will produce a positive right psoas sign • Adenocarcinoma of the pancreas in advanced stage invade the muscles and nerves of the PAW producing excrutiating pain because of the close relationship of the pancreas to the PAW 1/24/2022 56