Anatomy CDM Part PDF

Abdomen OVERVIEW: WALLS, CAVJTIES, REGIONS, AND Surfac:a Anatomy of Antlrolamral Abdominal Wall I 432 PLANES/4(16 CUNICAL BOX: lnmmal Surface of.Anterulamral TABLE 5.1. Abdominal Regions, Reference P...

Abdomen OVERVIEW: WALLS, CAVJTIES, REGIONS, AND Surfac:a Anatomy of Antlrolamral Abdominal Wall I 432 PLANES/4(16 CUNICAL BOX: lnmmal Surface of.Anterulamral TABLE 5.1. Abdominal Regions, Reference Planes, Abdominal Wall and Inguinal Region. Spllrmatic: Cord, and Quadrants I 407 Sc:rotum, and Test../433 ANTEROLATERAL ABDOMINAL WALL /408 PERITONEUM AND PERITONEAL CAVITY I 439 Fascia of Antwolateral Abdominal Wall/408 Embi')'Oiogy of Peritoneal Cavity / 440 Muscles of.Anterolamral Abdominal Wall/ 409 Perito....W Fonnations/ 441 TABLE 5.2. Muscles of Anterolateral Abdominal Subdivisions of Peritoneal Cavity I 443 Wall/410 CLINICAL BOX: Peritoneum and Peritoneal Neurovasculature of Anmrolateral Abdominal Wall/41 5 Cavity /445 TABLE 5.3. Nerws ofAnterolateral Abdominal ABDOMINAL VISCERA /448 Wall/416 Ovem.w ofAbdominal Visan. and Dipsdw Tract /448 TABLE 5.4. Arteries of Anterolateral Abdominal Esophagus /451 Wall/418 Stomach I 452 CUNICAL BOX: Fuc:ia and Musdes of Anb!rulateral TABLE 5.7. Arterial Supply to Abdominal Foregut Abdominal Wall. Neunwuculature of Anmrolamnl Derivatives: Esophagus, Stomach, Uver, Gallbladder, Abdominal Wall/419 Pancreas, and Spleen /458 Internal Surface of Anll!rula1l!nl Abdominal Wall/ 423 Small Intestine I 461 Inguinal Region /424 TABLE 5.8. Distinguishing Characteristics ofJejunum TABLE 5.5. Boundaries of Inguinal Canal/426 and Ileum in Living Body /466 Spennatic Cord, Scrotum, and Testas /428 Large Intestine I 468 TABLE 5.6. Coi'T'eSponding Layers ofthe TABLE 5.9. Arterial Supply to Intestines/ 474 Anterior Abdominal Wall, Scrotum, and Spermatic CUNICAL BOX: Esophagus and Stomach. Small and Cord/430 Large Intestine /476 CLINICAL BOX KEY Anatomical Diagnostic ufe Cycle Surgical Trauma Pathology 404 Variations Procedures Procedures  Abdomen 405 Spleen/487 Dillphrw.gmatic: Aperturu I 535 Pancnt.ul488 TABLE 5.12. Neurovascular Structures of l..iver /491 Diaphragm I 535 TABLE 5.10. TenninologyfurSubdivision$ ofl.iver /497 Actions of Diaphragm I 536 Biliary Ducts and Gallbladder I 501 POSTERIOR ABDOMINAL WALL/ 537 CUNICAL BOX: Spleen and Panc:nas. L.iwr. Biliary Fascia of Posterior Abdominal Wall/ 537 Ducts. and Gallbladder I SOS Musc:lu ofPosmrior Abdominal Wall/ 539 Kidneys. Uretzrs. and Supl"lll'enal Glands I 51 S TABLE 5.13. Muscles of Posterior Abdominal CUNICAL BOX: Kidn.ys, Glands/ 523 u......,and SupraNIIal Wall/539 Nei"WS of Posterior Abdominal Wall/ 540 Summary of Innervation of Abdominal Visc:.ra I 527 Vessels of Posterior Abdominal Wall/ 541 TABLE 5.1 1. Autonomic Innervation ofAbdominal TABlE 5.1 4. Branches of Abdominal Aorta I 542 Viscera (Splanchnic Nel"'les) /529 CUNICAL BOX: Diaphragm. Poltllrior Abdominal DIAPHRAGM/ 533 W..l/544 Vessels and Nerws of Diaphragm I 534 SECTIONAL MEDICAL IMAGING OF ABDOMEN/ 549 The abdomen is the part of the trunk between the thorax and and their contents is provided by musculo-aponeurotic walls the pelvis (Fig. 5.1). It is a flexible, dynamic container, hous- anterolaterally, the diaphragm superiorly. and the muscles of ing most of the organs of the alimentary system and part of the pelvis inferiorly. The anterolateral musculo-aponeurotic the urogenital system. Containment of the abdominal organs walls are suspended between and supported by two bony :rings Apex of right l u n g - - - --=-- - ----:' , pal'i9talp!9Unl 1bolax Horizontal fillauru ThOnlciccage protecting upper abdominal viscera Outline of dua$num Tran8\18n19 colon Aacending coron-----;r colon Gree.ter pelviS 11-·"'f---Intersplnous plan& protac:ang IOWIIr ebclomlnal VIscera COlon 1. Demarcated by diapllrugm 2. Demarcated by plane of pelvic inlrit FIGURE 5.1. wm- of viKWa of t.n. thoru: &nd in situ. 406 ChapterS Abdomen (the inferior margin ofthe thoracic skeleton superiorly and the pelvic girdle inferiorly) linked by a semirigid lumbar vertebral column in the posterior abdominal wall. Interposed between Body cavlllea the more rigid thorax and pelvis, this arrangement enables the abdomen to enclose and protect its contents while providing the flexibility required by respiration. posture, and locomotion. Through voluntary or reflexive contraction, its muscular roof, anterolateral walls, and Boor can raise internal (intra- abdominal) pressure to aid expulsion ofair from the thoracic cavity (lungs and bronchi) or of fluid (e.g., urine or vomitus), flatus (gas), feces, or fetuses from the abdominopelvic cavity. OVERVIEW: WALLS, CAVITIES, REGIONS, AND PLANES Abdomino- The dynamic, multilayered, musculo-aponeurotic ahdomi· pelvlc cavtty nal walls not only contract to increase intra-abdominal pressure but also distend considerably, accommodating Plane of superior ( expansions caused by ingestion, pregnancy, fat deposition, pelvic aperture or pathology. (pelvic inlet) The anterolateral abdominal wall and several organs lying against the posterior wall are covered on their internal aspects with a serous membrane or peritoneum (serosa) that lledlal view reflects (turns sharply and continues) onto the abdominal FIGURE 5.2. Abdominopemc Clntity. The body has been sectioned in the viscera (L., soft parts, intemal organs), such as the stomach, median plane to show the abdominal and pelvic: c:avities as subdivisions of intestine, liver, and spleen. Thus, a bursal sac or lined poten- the continuous abdominopelvic c:avity. tial space (peritoneal cavity) is formed between the walls and the viscera that normally contains only enough extracellular is the location of most digestive organs, parts of the uro- (parietal) Huid to lubricate the membrane covering most genital system (kidneys and most of the ureters), and the of the surfaces of the structures forming or occupying the spleen. abdominal cavity. Visceral movement associated with diges- tion occurs freely, and the double-layered reHections of Nine regions of the abdominal cavity are used to describe peritoneum passing between the walls and the viscera pro- the location of abdominal organs, pains, or pathologies vide passage for the blood vessels, lymphatics, and nerves. (Table 5.1A, B). The regions are delineated by four planes: Variable amounts of fat may also occur between the walls and two sagittal (vertical) and two transverse (horizontal) planes. viscera and the peritoneum lining them. The two sagittal planes are usually the mklclavicular planes The abdominal cavity that pass from the midpoint of the clavicles (approximately 9 em from the midline) to the miclinguinal points, mid- fonns the superior and major part of the abdomino- points of the lines joining the anterior superlcr lltac sptne pelvic cavity (Fig. 5.2), the continuous cavity that (ASIS) and the pubic mbercle.s on each side. extends between the thoracic diaphragm and peloic Most commonly, the transverse planes are the suooostal diaphragm. plane, passing through the inferior border of the lOth costal has no floor of its own because it is continuous with the cartilage on each side, and the transtubercular plane, pass- pelvic cavity. The plane of the pelvic inlet (superior pel- ing through the iliac tubercles (approximately 5 em posterior vic aperture) arbitrarily, but not physically, separates the to the ASIS on each side) and the body of the L5 vertebra. abdominal and the pelvic cavities. Both of these planes have the advantage of intersecting pal- extends superiorly into the osseocartilaginous thoracic pable structures. cage to the 4th intercostal space (Fig. 5.1). Consequently, Some clinicians use the transpyloric and interspinous the more superiorly placed abdominal organs (spleen, planes to establish the nine regions. The transpylorlc liver, part of the kidneys, and stomach) are protected by plane, extrapolated midway between the superior borders the thoracic cage. The greater pelvis (expanded part of of the manubrium of the sternum and the pubic symphy- the pelvis superior to the pelvic inlet) supports and partly sis (typically the Ll vertebral level), commonly transects protects the lower abdominal viscera (part of the ileum, the pylonss (the distal, more tubular part of the stomach) cecum, appendix:, and sigmoid colon). when the patient is recumbent (supine or prone) (Fig. 5.1). (continued onp. 408)  Overview: Walls, Cavities, Regions, and Planes 407 TABLE 5.1. ABDOMINAL REGIONS (A), REFERENCE PLANES (B), AND QUADRANTS (C) Abdomlnalarau Abdominal Reglona: RH Right hypochondrium RL Right ftank (lateral region) RI Right Inguinal (groin) E Epigastric U Umbilical P Pubic LH Lett hypochondriac LL Left flank Oateral region) U Left inguinal (groin) Abdominal Quadrants: RUQ Right upper quadrant LUQ Left upper quadrant RLQ Right lower quadrant LLQ Lett lower quadrant \ (A} Abdominal reglona (C) Abdominal quadrants Right upper quadrant (RUQ) Left upper quadrant (LUQ) Uver: right lobe Liver: left lobe Gallbladder Spleen Stomach: pylorus Stomach Duodenum: parts1-3 Jejunum and proximal Ileum Pancreas: head Pancreas: body and 1all Right suprarenal gland Lett kidney Right kidney Left suprarenal gland Right colic (hepatic) flexure Left colic (splenic) flexure Ascending colon: Transverse colon: left half superior part Descending colon: Transverae colon: right half superior part Right lower quadrant (RLQ) Left lower quadrant (LLQ) Cecum Sigmoid colon Appendix Descending colon: Inferior part Most of ileum Left ovary Ascending colon: inferior part Lett uterine tube Right ovary Left ureter: abdominal part Right uterine tube Left spermallc cord: Right ureter: abdominal part abdominal part Right spermatic cord: Uterus (if enlarged) abdominal part Urtnary bladder (If very full) Uterus (If enlarged) Urinary bladder (if very full) (B) Abdominal reference planea 408 ChapterS Abdomen Because the viscera sag with the pull of gravity, the pylorus is musculo-aponeurotic, except for the posterior wall, which usually lies at a lower level when the individual is standing includes the lumbar region of the vertebral column. The erect. The transpyloric plane is a useful landmark because it boundary between the anterior and lateral walls is indefinite; also transects many other important structures: the fundus therefore, the term anterolateral abdominal waD. is often of the gallbladder, neck of the pancreas, origins of the supe- used. Some structures, such as muscles and cutaneous nerves, rior mesenteric artery (SMA) and hepatic portal vein, root of are in both the anterior and lateral walls. The anterolateral the transverse mesocolon, duodenojejunal junction. and hila abdominal wall extends from the thoracic cage to the pelvis. of the kidneys. The interspinous plane passes through the The anterolateral abdominal wall is boWlded superiorly easily palpated ASIS on each side (Table S.IB). by the cartilages of the 7th-10th ribs and the xiphoid pro- For more general clinical descriptions, four quadrants of cess of the sternum and inferiorly by the inguinal ligament the abdominal cavity (right and left upper and lower quad- and the superior margins of the anterolateral aspects of the rants) are defined by two readily defined planes: (1) the trans- pelvic girdle (iliac crests, pubic crests, and pubic symphysis) verse transumbilical plane, passing through the umbilicus or (Fig. 5.4A). navel (and typically the intervertebral [IV] disc between the L3 The anterolateral abdominal wall consists of skin and and lA vertebrae), dividing itinto upper and lower halves, and subcutaneous tissue (superficial fascia) composed mainly (2) the vertical 1J'UUhan plane, passing longitudinally through of fat, muscles and their aponeuroses and deep fascia, the body, dividing it into right and left halves (Table 5.1C). extraperitoneal fat, and parietal peritoneum (Fig. 5.4B). The It is important to know what organs are located in each skin attaches loosely to the subcutaneous tissue, except at abdominal region or quadrant so that one knows where the umbilicus, where it adheres fu:mly. Most of the antero- to auscultate, percuss, and palpate them (Table 5.1) lateral wall includes three musculotendinous layers; the fiber and to record the locations of findings during a physical bundles of each layer nm in different directions. This three- examination. ply structure is similar to that of the intercostal spaces in the thorax. ANTEROLATERAL ABDOMINAL WALL Fascia of Anterolateral Although the abdominal wall is continuous, it is subdivided Abdominal Wall into the anteriorwall, right and left lateral wall8, and posterior The subcutaneous tissue over most of the wall includes a wall for descriptive purposes (Fig. 5.3). The abdominal wall variable amount of fat. It is a major site of fat storage. Males are especially susceptible to subcutaneous accumulation of fat in the lower anterior abdominal wall. In morbid obesity, VerUcal anterior abdominal musctes the fat is many inches thick, often forming one or more sag- ging folds (L. panniculi; singular =panniculus, apron). Superior to the umbilicus, the subcutaneous tissue is consistent 'With that found in most regions. Inferior to the umbilicus, the deepest part of the subcutaneous tissue is reinforced by many elastic and collagen fibers, so it has two layers: the superficial fatty layer (Camper fascia) and the deep membranous layer (Sca:rpa fascia.) ofsubcutaneous tissue. The membranous layer continues inferiorly into the perineal region as the membranous layer of subcutaneous tissue of the perinewn (superficial perineal or Colles fascia), but not into the thighs (see Fig. 5.9B). Superficial, intermediate, and deep U..yers of intlesting fascia cover the external aspects of the three muscle layers of the anterolateral abdominal wall and their aponeuroses (Oat expanded tendons) and cannot be easily separated from them. The investing fascias here are extremely thin, being represented mostly by the epimysium (outer fibrous con- nective tissue layer surrounding all muscles-see Chapter lnfwlor 'VIew * Boundary indefinite and overlapping I, Overview and Basic Concepts) superficial to or between muscles. The internal aspect of the abdominal wall is lined FIGURE 5.1 Subdillisiont of «he.WominaJ wall. A transverse section 'With membranous and areolar sheets of varying thickness of the abdomen demonstrates various aspects ofthe wall and its components. (*The superficial latissimus dorsi and deeper psoas constituting endoabdominal fascia. Although continu- major muscles are axio-appendicular muscles that attach distally in the ous, different parts of this fascia are named according to the upper and lower limbs, respectively.) muscle or aponeurosis it is lining. The portion lining the deep  Ante.,IIW!I"aa Abdominal Wall 409 Muscles of Anterolateral Abdominal Wall There are 6.ve (bilaterally paired) muscles in the anterolateral abdominal wall (Fig. 5.3): three flat muscles and two vertical muscles. Their attachments are demonstrated in Figure 5.5 and listed, along with their nerve supply and main actions, in Table 5.2. The three flat muscles are the external oblique, internal oblique, and tran8fJ6f'SU8 ahdcmmis. The muscle 6.bers ofthese three concentric muscle layers have varying orientations, with the 6.bers of the outer two layers running diagonally and per- pendicular to each other for the main part, and the 6.bers of the deep layer running transversely. All three flat muscles are continued anteriorly and medially as strong, sheet-like neuroses (Fig. 5.6A). Between the midclavicular line (MCL) and the midline, the aponeuroses form the tough, aponeu- rotic, tendinous rectus sheath enclosing the rectus abdominis muscle (Fig. 5.6B). The aponeuroses then interweave with their fellows ofthe opposite side, forming a midline raphe (G. rhaphe, suture, seam), the linea alba (L. white line), which extends from the xiphoid process to the pubic symphysis. The decussation and interweaving ofthe aponeurotic 6.bers here is not only between right and left sides but also between superfi- Rectus cial and intermediate and intermediate and deep layers. lnguinalligament------ r The two vertical mmdes of the anterolateral abdominal wall, contained within the rectus sheath, are the large rectus Pubic crest and ahdominis and the small pyramidalis. (A) Anterior view Supernclal 40 years of age) majority of which 819 males FNqu.nqo Less common (one third to one quarter of Inguinal hernias) More common (two thirds to three quarters) of Inguinal hernias EXIt from abdominal cavity Peritoneum plus transversalis faacia (lies outside inner one Peritoneum of persistent processus vaginal is plus (Fig. B5.3A, B) or two faacial coverings of cord) all three fascial coverings of COI'dlround ligament Course (Fig. B5.3C) Passes through or around Inguinal canal, usually traversing Trawl'868 Inguinal canal (entire canal If It 18 of only medial third of canal, external and PaJ9IIelto vestige of sufllclent size) within proc:essus vaglnalls processus vaglnalls EXIt from lllllllrtor Via superficial ring, lataraiiO oon:l: r8191y anlars scrotum Via superficial ring inside oon:l, commonly passing abdominal wall into scrotum/labium majua Hematocele of Testis a hematocele or hematoma from a hydrocele. A hematocele of the testis may be associated with a scrotal hematocele, A hematocele of the testis is a collection of blood resulting from effusion of blood into the scrotal tissues. in the tunica vagiwilis that results, for example, from rupture of branches of the testicular artery by trauma to the testis (Fig. B5.4C). Trauma may produce a Torsion of Spermatic Cord scrotal and/or testicular hematoma (accumulation of blood, Torsion of the spermatic cord is a surgical emer- usually clotted, in any extravascular location). Blood does not gency because necrosis (pathologic death) of the transilluminate; therefore, transillumination can differentiate testis may occur. The torsion (twisting) obstructs 436 Chapter 5 Abdomen Lateral margin of rectus lndlr.ct abdomlnls muscle Anterior superior Inferior Anterior iliac spine artery lilac spine Inguinal ligament Deep Inguinal Inguinal ring ring Inguinal canal Superficial inguinal ring (A) (B) (C) A-C. Anterior views Inferior eplgasb1c artery and vein Rac:tus abdominis Transversus Rectus abdomlnls \ abdomlnls Transversalis fascia Deep Inguinal ring (cut edge) lllopublc tract Deep Inguinal ring Testicular artery and vein -..r.,;.,;--,.. External lilac artery and vein eo-Iliopsoas External lilac deferens artery and vein (D) (E) D, E. Pos18rlor vlewll of right anterior abdominal wall FIGURE BS.3. the venous drainage, with resultant edema and hemorrhage, Anesthetizing Scrotum and subsequent arterial obstruction. The twisting usually occurs just above the upper pole of the testis (Fig. B5.4D). Since the anterolateral surface ofthe scrotum is sup- One clue on physical exam is that the testis seems to lie lumbar plexus Ll via the transversely. Ultrasound can be used to confirm. To pre- ilio-mguinal nerve) and the aspect is vent recurrence or occurrence on the contralateral side, supplied bythe sacral plexus (primarily S3 fibers via the puden- which is likely, both testes are surgically fixed to the scrotal dal nerve), a spinal anesthetic agent must be injected more septum. superiorly to anesthetize the anterolateral surface of the scro- tum than is necessary to anesthetize its surface. Hemorrhage into the tunica vaginalis due to............ ) cord ,.,____, Upper c of testis Testis / ( ' (A) Hydrocele (H) of testle (B) Hydrocele (H) of cord (C) Hematocele (H) of leetl8 (D) Torelon of apermatlc cord FIGURE 85.4.  Anterolateral Abdominal Wall 437 Spermatocele and Epididymal Cyst A spermatocele is a retention cyst (collection of fluid) in the epididymis (Fig. B5.5A), usually near --Spennatic coR! its head. Spermatoceles contain a milky fluid and are generally asymptomatic. An epididtprud cyst is a collec- tion offluid anywhere in the epididymis (Fig. B5.5B). Vestigial Remnants of Embryonic Genital Ducts When the tunica vaginalis is opened, rudimen- ta:ry structures may be observed at the superior aspects of the testes and epididymis {Fig. B5.6). These structures are small remnants of genital ducts in the embryo. They are rarely observed unless pathological changes occur. The appendix of the testis is a vesicular rem- nant of the cranial end of the paramesonephric (miilkrian) "-Parietal layer Of reftec:ted tuniCa duct, the embryonic genital duct that in the female forms vaglnalls half of the uterus. It is attached to the upper pole of the {cut edge) testis. The appendices ofthe epididymis are remnants ofthe *Sinu8 cranial end of the mesonephric (wolffian) duct, the embry- Of epididymi$ onic genital duct that in the male forms part of the ductus Anterior viM' deferens. The appendices are attached to the head of the FIGURE 15.8. epididymis. Varicocele favorable to How than the nearly 90° angle at which the left testicular vein enters the left renal vein, making it more sus- The vine-like pamptnifonn plexus of veins may ceptible to obstruction or reversal of How. become dilated (varicose) and tortuous, produc- ing a ooricocele, which is usually visible only when the man is standing or straining. The enlargement usually Cancer of Testis and Scrotum disappears when the person lies down, particularly if the Lymphogenous metastasis is common to all testicu- scrotum is elevated while supine, allowing gravity to empty lar tumors, so a lmowledge oflymphatic drainage is the veins. Palpating a varicocele can be likened to feeling a helpful in treatment (Kumaret al., 2015). Because bag of worms. Varicoceles may result from defective valves the testes relocate from the posterior abdominal wall to the in the testicular vein, but kidney or renal vein problems can scrotum during fetal development, their lymphatic drainage also result in distension ofthe pampiniform veins. Varicocele differs from that of the scrotum, which is an outpouching of occurs predominantly on the left side, probably because the anterolateral abdominal skin (see Fig. 5.15). Consequently: acute angle at which the right vein enters the IVC is more Cancer ofthe testis: metastasizes initially to the retroperi- toneallumbar lymph nodes, which lie just inferior to the renal veins. Subsequent spread may be to mediastinal and Eplcllclymal cyst supraclavicular nodes. Cancer of the scrotum: metastasizes to the super:ficl.al inguinal lymph notks, which lie in the subcutaneous tis- sue inferior to the inguinal ligament and along the termi- nal part of the great saphenous vein. Testicular tumors are approached through an inguinal incision so that vessels and lymphatics can be controlled early. A classic pitfall is going in through a scrotal incision, (A) (B) \ Tes11s cowrvct thinking a mass is "just" a hydrocele. Careful physical exam and ultrasound help avoid this mistake by visceral layer Metastasis of testicular cancer may also occur by hema- of tunica vaginalis togenous spread of cancer cells (via the blood) to the bmgs, FIGURE 85.5. A. Spennatocele. B. Epididymal cyst. liver, brain, and bone. 438 ChapterS Abdomen The Bottomline INTERNAL ABDOMINAL WALL AND INGUINAL REGION lntllrnalabdominal wall: The primary features of the neurovascular structures of the testis (or processus vaginal is internal surface of the anterolateral abdominal wall are and lower ovarian gubernaculum of the female) become peritoneal folds overlying structures radiating from the engulfed by fascial extensions derived from most (three umbilical ring and the peritoneal fossae fonned in relation offour) of the laY'!rs traversed. This results in a trilaminar to the folds. Of the umbilical peritoneal folds, the central covering. The transversalis fascia, internal oblique, and three (median and medial umbilical folds) cover remnants external oblique laY'!rs contribute the internal spennatic: ofembryological structures, whereas the lateral umbilical fascia, cremasteric: muscle and fascia, and external spennatic: folds cover the inferior epigastric vessels. The peritoneal fascia, respectively, to the spennatic: cord. In their passage fossae fonned in relation to the umbilical folds indude the through the inguinal canal, the processus vaginalis, testis, transitional supravesical fossae, the height of which changes ductus deferens, and neurovascular structupatent as the with bladder filling, and the medial and lateral inguinal fossa, tunica vaginalis testis. The contents of the spennatic: cord overtying potential weak areas in the anterior abdominal wall are the ductus deferens and neurovascular structures, which where direct and indirect inguinal hernias, respectively, may trailed the testis as it relocated from the posterior abdominal occur. The supra-umbilical falc:ifonn ligament encloses wall during development. the remnant of the embryonic: umbilical vein and the Sci"Dttllm: The scrotum is the integumentary sac: fonned accompanying para-umbilical veins (tributaries of the hepatic from the labioscrotal swellings of the male to house the portal vein) in its free edge. testes after their relocation. The fatty layer ofsubcutaneous Inpinal reslon: The inguinal region extends from the ASIS tissue of the abdominal wall is replaced in the scrotum by to the pubic tubercle; its superficial inguinal fold deman:ates the the smooth dartos muscle, whereas the membranous laY'!r abdomen from the lower limb. It lies within the L1 dennatome. is continued as the dartos fascia and scrotal septum. The Most structures and fonnations in the inguinal region relate scrotum receives anterior scrotal arteries from the thigh to a double (bilaminar) retinaculum fonned by the inguinal (via the external pudendal artery), posterior scrotal arteries ligament and iliopubic tract as they extend between the two from the perineum (internal pudendal artery), and internally bony points. These two bands are thickenings ofthe inferior cremasteric: arteries from the abdomen (inferior epigastric: margins of the external oblique aponeurosis and transversalis artery). Anterior scrotal nerves are derived from the lumbar fascia of the abdominal wall, respec:tiwly. plexus (via the genitofemoral and ilio-inguinal neM!S), To allow the testis to descend prenatally to a subcutaneous and posterior scrotal nerves from the sacral plexus (via the location that will be cooler poslrlatally (a requirement for pudendal nerve). the development of spenns ), the inguinal canal traverses the Tatea1 The testes are the male gonads, shaped and abdominal wall superior and parallel to the medial half of the sized like large olives that produce sperms and male inguinal ligament. In females, only the inferior portion of hormones. Each testis is engulfed, except posteriorly the gubernaculum trawrses the canal, becoming the round and superiorly, by a double-layered serous sac, the tunica ligament of the uterus. The inguinal canal itself consists vaginalis, derived from the peritoneum. The outer of a deep ring internally, a superficial ring externally, and surface of the testis is covered with the fibrous tunica two musculo-aponeurotic arches in between. The oblique albuginea, which is thickened internally and posteriorly as passageway through the offset rings and arches collapses the mediastinum of the testis from which septa radiate. when intra-abdominal pressure increases. Collapse of the Between the septa are loops of fine seminiferous tubules in canal, combined with the prenatal occlusion of the peritoneal which the sperms develop. The tubules converge and empty evagination (processus vaginalis) and the contraction of the into the rete testis in the mediastinum, which is connected arches, nonnally resists the tendency for abdominal contents in turn to the epididymis by the efferent ductules. The to herniate (protrude through) the canal. Failure of the innervation, blood vasculature, and lymphatic drainage all processus vaginalis to occlude, or defectiw anatomy, or reflect the posterior abdominal origin of the testes and are, degeneration of tissues, may result in the development of for the main part, independent of the surrounding scrotal inguinal hernias. sac. The epididymis is formed by the highly convoluted and compacted duct of the epididymis leading from the efFerent ductules to the ductus deferens. It is the site of SPERMATIC COBD, SCBOTUM, AND TESTES sperm storage and maturation. The epididymis clings to Spennadc conla In their passage through the inguinal the more protected superior and posterior aspects of the canal, the processus vaginalis, testis, ductus deferens, and testis.  Peritoneum and Peritoneal Cavity 439 PERITONEUM AND PERITONEAL region, that from midgut derivatives in the umbilical region, and that from hindgut derivatives in the pubic region. CAVITY The peritoneum and viscera are inthe abdominopelvic cavity. The relationship ofthe viscera to the peritoneum is as follmvs: The peritoneum is a continuous, glistening, and slippery transparent serous membrane. It lines the abdominopelvic Intraperitoneal organs are almost completely covered cavity and invests the viscera (Fig. 5.23). The peritoneum with visceral peritoneum (e.g., the stomach and spleen). consists of two continuous layers: the parietal peritoneum, Intraperitoneal in this case does not mean inside the peri- which lines the internal surface of the abdominopelvic wall, toneal cavity (although the term is used clinically for sub- and the visceral peritoneum, which invests viscera such as the stances injected into this cavity). Intraperitoneal organs stomach and intestines. Both layers of peritoneum consist have conceptually, if not literally, invaginated into the of mesothelium, a layer of simple squamous epithelial cells. closed sac, like pressing your fist into an inflated balloon The parietal peritoneum is senred by the same blood (see the discussion of potential spaces in the Chapter 1, and lymphatic vasculature and the same somatic nenre sup- Overview and Basic Concepts). ply, as is the region of the wall it lines. Like the overlying E:rtraperitoneal, retroperitoneal, and rmbperitoneal skin, the peritoneum lining the interior of the body wall is organs are also outside the peritoneal cavity-exter- sensitive to pressure, pain, heat and cold, and laceration. nal to the parietal peritoneum-and are only partially Pain from the parietal peritoneum is generally well localized, covered with peritoneum (usually on just one surface). except for that on the inferior surface of the central part of Retroperitoneal organs such as the kidneys are between the diaphragm, where innervation is provided by the phrenic the parietal peritoneum and the posterior abdominal wall nerves (discussed later in this chapter); irritation here is often and have parietal peritoneum only on their anterior sur- referred to the C3-C5 dennatomes over the shoulder. faces (often with a variable amount of intervening fat). The visceral peritoneum and the organs it covers are Similarly, the subperi.toneal urinary bladder has parietal served by the same blood and lymphatic vasculature and vis- peritoneum only on its superior surface. ceral nenre supply. The visceral peritoneum is insensitive to The peritoneal cavity is within the abdominal cavity and touch, heat and cold, and laceration; it is stimulated primarily continues inferiorly into the pelvic cavity. The peritoneal cavity by stretching and chemical irritation. The pain produced is is a potential space of capillary thinness between the parietal poorly localized, being referred to the dermatomes of the spi- and visceral layers of peritoneum. It contains no organs but nal ganglia providing the sensory :fibers, particularly to mid- contains a thin film of peritoneal Buid, which is composed of line portions of these dermatomes. Consequently, pain from water, electrolytes, and other substances derived from inter- foregut derivatives is usually experienced in the epigastric stitial :O.uid in adjacent tissues. Peritoneal fluid lubricates the An18rlor Lesser omenlllm Hepatogastrlc I !Portal triad in artery ligament hepatoduodenal Bile duct Stomach ligament Hepatic portal VIsceral peritoneum (covering spleen) Parietal peritoneum Parietal peritoneum l:.L"llll Greater sac Inferior view Posterior - Omental bursa (lesser sac) FIGURE 5.23. Tran- Hc:tian ofabdomen at IIMII of 111M11tal bui'IIIL. The orientation figure (inaat:) indicates the level ofthe section superficially. The d.Jrlc mJW passes fioo m die greater sac ofdie peritoneal cavity (P) through dl e omental (epiploic) foramen and across the full extent ofthe omental bursa (lesser sac). 440 ChapterS Abdomen peritoneal surfaces, enabling the viscera to move over each sac, acquiring a peritoneal covering, the visceml peritoneum. other without friction, and allowing the movements of diges- A viscus (organ) such as the kidney protrudes only partially tion. In addition to lubricating the surfaces of the viscera, the into the peritoneal cavity; hence, it is primarily retroperitn- peritoneal :8.uid contains leukocytes and antibodies that resist neal, always remaining external to the peritoneal cavity and infection. Lymphatic vessels, particularly on the inferior sur- posterior to the peritoneum lining the abdominal cavity. Other face of the constantly active diaphragm, absorb the perito- viscera, such as the stomach and spleen, protrude completely neal :8.uid. The peritoneal cavity is completely closed in males. into the peritoneal sac and are almost completely invested by However, there is a communication pathway in females to the visceral peritoneum-that is, they are intraperitoneal. exterior of the body through the uterine tubes, uterine cavity, These viscera are connected to the abdominal wall by a f118S- and vagina. This communication constitutes a potential path- ent6flj of variable length, which is composed of two layers of way ofinfection from the exterior. peritoneum with a thin layer ofloose connective tissue between them. Generally, viscera that vary relatively little in size and shape, such as the kidneys, are retroperitoneal, whereas viscera Embryology of Peritoneal Cavity that undergo marked changes in shape owing to fl11ing, emp- When it is initial1y formed, the gut (embryonic digestive tying, and peristalsis, such as the stomach, are invested with tube) is the same length as the developing body. It undergoes visceral peritoneum. Intraperitoneal viscera with a mesentery, exuberant growth, however, to provide the large absorptive such as most of the small intestine, are mobile, the degree of surface required by nutrition. By the end of the lOth week of which varies with the length of the mesentery. Although the development, the gut is much longer than the body that con- liver and spleen do not change shape as a result ofintrinsic activ- tains it. For this increase in length to occur, the gut must gain ity (although they may slowly change in size when engorged freedom of movement relative to the body wall at an early with blood). their need for a covering ofvisceral peritoneum is stage, while still maintaining the connection with it necessary dictated by the need to accommodate passive changes in posi- for innervation and blood supply. This growth (and later, the tion imposed by the adjacent, highly active diaphragm. activity of the gut) is accommodated by the development of As orgaiJS protrude :iDto the peritoneal sac, their vessels, a serous cavity within the trunk that houses the increasingly nerves, and lymphatics remain connected to their extraperi- lengthy and convoluted gut in a relatively compact space. toneal (usually retroperitoneal) sources or destinations so that The rate of growth of the gut initially outpaces the develop- these connecting structures lie between the layers ofthe peri- ment of adequate space within the trunk (body), and for a toneum forming their mesenteries. Initially, the entire pri- time, the rapidly lengthening gut extends outside the devel- mordial gut is suspended in the center of the peritoneal cavity oping anterior body wall (see the Clinical Box "Brief Review by a posterior mesentery attached to the midline ofthe poste- of Embryological Rotation of the Midgut," p. 481). rior body wall As the organs grow, they gradually reduce the Early in its development, the embryonic body cavity (lntra- size of the peritoneal cavity until it is only a potential space emhryonk coelom) is lined with f118ScxUrm, the primordium of between the parietal and visceral layers of peritoneum. As the peritoneum. At a slightlylater stage, the primordial abdom- a consequence, several parts of the gut come to lie against inal cavity is lined with parietal peritoneum derived from the posterior abdominal wall, and their posterior mesenteries mesoderm, which forms a closed sac. The lumen of the peri- become gradually reduced because of pressure from overly- toneal sac is the peritoneal caoity. As the organs develop, they ing organs (Fig. 5.24). For example, during development, the invaginate (protrude) to varying degrees into the peritoneal growing coiled mass of small intestine pushes the part of the Descending colon (now secondarily Descending colon retroperi!Dneal) Superior Ylewa FIGURE 5.24. Mipv.tian and fu&ian of die dacanding rnaocalan. Starting !Tom the primordial position, suspended from the midline ofthe posterior abdominal wall (A), the mesocolon shifts to the left: (B) and gradually fuses with the left posterior pariml peritoneum (C). D. The descending colon has become secondarily retroperitoneal. The arrcw indicates the left: paracolic gutter, the site where an incision is made during mobilization ofthe colon during surgery. Sometimes, the descending colon reti.ins a short mesentery, similar to the stage shown in (C), especially where the colon is in the iliac fossa.  Peritone11m and Peritoneal Cavit, 441 gut that will become the descending colon to the left side and (Fig. 5.25A, E). A mesentery connects an intraperitoneal presses its mesentery against the posterior abdominal wall. organ to the body wall-usually the posterior abdominal wall The mesentery is held there until the layer ofperitoneum that (e.g., mesentery of the small intestine). formed the left side of the mesentery and the part of the vis- The small intestine mesentery is usually referred to ceral peritoneum ofthe colon lying against the body wall fuse simply as "the mesentery"; however, mesenteries related with the parietal peritoneum ofthe body wall. As a result,. the to other specific parts of the alimentary tract are named colon becomes fixed to the posterior abdominal wall on the accordingly-for example, the transverse and sigmoid left side with peritoneum covering only its anterior aspect mesocolons (Fig. 5.25B), mesoesophafps, mesogamium, and The descending colon (as well as the ascending colon on the meso-appendi-x. Mesenteries have a core of connective tis- right side) has thus become secoodarily rmopentoneal, hav- sue containing blood and lymphatic vessels, nerves, lymph ing once been intraperitoneal (Moore et al., 2016). nodes, and fat (see Fig. 5.48A). The layers of peritoneum are now fused by means of a An omentum is a double-layered extension or fold of fusion fascia (of Toldt; see Culligan 2012), a connective peritoneum that passes from the stomach and pronmal part tissue plane between the retroperitoneum and the former of the duodenum to adjacent organs in the abdominal cavity descending mesocolon in which the nerves, vessels, and (Fig. 5.25). lymph nodes of the descending colon continue to lie. Thus, The greater omentum is a prominent, four-layered the descending colon of the adult can be freed from the pos- peritoneal fold that hangs down like an apron from the terior body wall (surgically mobilized) by incising the perito- greater curvature of the stomach and the proximal part neum along the lateral border of the descending colon and of the duodenum (Fig. 5.25A, C, & E). After descending, then bluntly dissecting along the plane of the fusion fascia, it folds back and attaches to the anterior surface of the elevating the neurovascular structures from the posterior transverse colon and its mesentery. body wall until the midline is reached. The ascending colon The lesser omentum is a much smaller, double-layered can be similarly mobilized on the right side. peritoneal fold that connects the lesser curvature of the Several parts of the gastrointestinal tract and associated stomach and the proximal part of the duodenum to the organs become secondarily retroperitoneal (e.g., most of the liver (Fig. 5.25B, D). It also connects the stomach to a duodenum and pancreas as well as the ascending and descend- triad of structures that run between the duodenum and ing parts of the colon). They are covered with glistening peri- liver in the free edge of the lesser omentum (Fig. 5.23). toneum only on their anterior surface. Other parts of the viscera {e.g., the sigmoid colon and spleen) retain a relatively A peritoneal ligament consists of a double layer of peri- short mesentery: However, the roots of the short mesenteries toneum that connects an organ with another organ or to the do not arise from the midline but shift to the left or right by abdominal wall. a fusion process like that described for the descending colon. The liver is connected to the anterior abdominal wall bythefalciformUgament (Fig. 5.26). Peritoneal Formations stomach by the hepatogastric ligament, the membra- nous portion ofthe lesser omentum. The peritoneal cavity has a complex shape. Some ofthe facts duodenum by the hepat.oduodenalligament, the thick- relating to this include the following: ened free edge of the lesser omentum, which conducts The peritoneal cavity houses a great length of gut, most of the portal triad: portal vein, hepatic artery, and bile duct which is covered with peritoneum. (Figs. 5.23 and 5.26). Extensive continuities are required between the parietal The hepatogastric and hepatoduodenalligaments are con- and visceral peritoneum to convey the necessary neuro- tinuous parts of the lesser omentum and are separated only vascular structures from the body wall to the viscera. for descriptive convenience. Although the volume of the abdominal cavity is a fraction The stomach is connected to the: ofthe body's volume, the parietal and visceral peritoneum lining the peritoneal cavity within it have a much greater inferior surface of the diaphragm by the gastrophrenic surface area than the body's outer surface (skin); there- ligament. fore, the peritoneum is highly convoluted. spleen by the gastrosplenic ligament, which reflects to the hilum of the spleen. Various terms are used to describe the parts of the peri- transverse colon by the gastrocolic ligament, the apron- toneum that connect organs with other organs, or to the like part of the greater omentum, which descends from abdominal wall, and the compartments and recesses that are the greater curvature, tums under, and then ascends to formed as a consequence. the transverse colon. A mesentery is a double layer of peritoneum that occurs as a result of the invagination of the peritoneum by All these structures have a continuous attachment an organ and constitutes a continuity of the visceral and along the greater curvature of the stomach and are all part parietal peritoneum. It provides a means for neurovascu- of the greater omentum, separated only for descriptive lar communications between the organ and the body wall purposes.  ChapterS Abdomen (A) Anterior view (C) (D) (E) Anterior view FIGURE 5.25. PriMi,_J of the peritoneum. A. In this opened peritoneal cavity, pam of the greater omentum, transverse colon, and the small intestine and its mesentery have been cut away to reveal deep structures and the layers of the mesenteric: structures. The mesentery ofthe jejunum and ileum (small intestine) and sigmoid mesocolon have been cut close to their parietal attachments. B. This median section of the abdominopelvic cavity of a male shows me relationships of the peritoneal attachments. C. The greater omentum is shown in its "normal" position, covering most ofthe abdominal viscen. D. The lesser omentum, attaching the liver to the lesser curvature ofthe stomach, is shown by reSecting the liver and gallbladder superiorly. The greater omentum has been removed !Tom the greater curvature ofthe stomach and tnl.nsverse colon to reveal the intestines. E. The greater omentum has been reRec:ted superiorly, and the small intestine has been retracted to the right side to reveal the mesentery of the small intestine and the transverse mesocolon. Although intraperitoneal organs may be almost entirely ducts, and ligaments formed by obliterated fetal vessels covered with visceral peritoneum, every organ must have (e.g., the umbtlkal fold$ on the internal surface of the an area that is not covered to allow the entrance or exit of anterolateral abdominal wall, Fig. 5.13). Some peritoneal neurovascular structures. Such areas are called bare areas, folds contain blood vessels and bleed if cut, such as the formed in relation to the attachments of the peritoneal for- lateral umbilical folds, which contain the inferior epigastric mations to the organs, including mesenteries, omenta, and arteries. ligaments that convey the neurovascular structures. A peritoneal recess, or peritoneal fossa, is a pouch of A peritoneal fold is a reflection of peritoneum that peritoneum that is formed by a peritoneal fold (e.g., the infe- is raised from the body wall by underlying blood vessels, rior recess of the omental bursa between the layers of the  Peritone11m and Peritoneal Cavit, greater omentum, and the supravesical and umbilical fossae compartments through the paracolic gntters, the grooves between the umbilical folds; see Fig. 5.13). between the lateral aspect of the ascending or descending colon and the posterolateral abdominal wall. Flow is freest on the right side. Subdivisions of Peritoneal Cavity The omental bursa is an extensive sac-like cavity that After the rotation and development of the greater curva- lies posterior to the stomach, lesser omentum, and adjacent ture of the stomach during development (see the Clinical structures (Figs. 5.23, 5.27A, and5.28). The omental bursa Box "Brief Review of Embryological Rotation of Midgut." has a superior recess, limited superiorly by the diaphragm p. 481), the peritoneal cavity is divided into the greater and and the posterior layers of the coronary ligament of the liver, lesser peritoneal sacs (Fig. 5.27A). The greater soc is the and an inferior recess between the superior parts of the layers main and larger part of the peritoneal cavity. A swgical inci- of the greater omentum (Figs. 5.26 and 5.28A). sion through the anterolateral abdominal wall enters the The omental bursa permits free movement of the stom- greater sac. The omental bursa (ksser soc) lies posterior to ach on the structures posterior and inferior to it because the stomach and lesser omentum. the anterior and posterior walls of the omental bursa slide The transverse mesocolon (mesentery of the trans- smoothly over each other. Most of the inferior recess of the verse colon) divides the abdominal cavity into a supracolic bursa becomes sealed off from the main part posterior to the compartment, containing the stomach, liver, and spleen, stomach after adhesion of the anterior and posterior layers of and an infracolic compartment, containing the small the greater omentum (Fig. 5.28B). intestine and ascending and descending colon. The infra- The omental bursa communicates with the greater sac colic compartment lies posterior to the greater omentum through the omental foramen (epiploic foramen), an opening and is divided into right and left in&acolic spaces by the situated posterior to the free edge of the lesser omentum (hep- mesentery ofthe smalllntestine (Fig. 5.27B ). Free commu- atoduodenalligament). The omental foramen can be looated nication occurs between the supracolic and the infracolic by running a finger along the gallbladder to the free edge of 444 ChapterS Abdomen Superior recess of Lung Transverse omental bursa colon I Infracollc compartment (B) Antlrlor view (A) Right lattral view FIGURE 5.27. Subdivisions of the peritoneal cavity. A. This median section ofthe abdominopelvic cavity shows the subdivisions of the peritoneal cavity. B. The supracolic and in&acolic: compartments of the greater sac are shown after removal of the greater omentum. The in&acolic: spaces and paracolic gutters detennine the flow of ascitic ftuid (4mws) when inclined or upright. the lesser omentum (Fig. 5.29). The omental foramen usually Posteriorly: the IVC and a muscular band, the right crus admits two fingers. The boundaries ofthe omentalforomen are of the diaphragm, covered anteriorly with parietal perito- as follows: neum. (They are retroperitoneal.) Anteriorly: the hepatoduodenal ligament (free edge Superiorly: the liver, covered with visceral peritoneum of lesser omentum), containing the hepatic portal vein, (Figs. 5.28 and 5.29). hepatic artezy, and bile duct (Figs. 5.23 and 5.26). Inferiorly: the superior or first part of the duodenum. ,_,...---lesser----...! omentum FIGURE 5.28. Walls and recesses of dMI omenta.! bursa. A. This section shows that the omental bursa is an isolated part ofthe peritoneal cavity, lying dorsal to the stomach and extending superiorfy to the liver and diaphragm (superior recess) and inferiorly between the layers of the greater omentum (inferior recess). B. This section shows the abdomen after fusion ofthe layers ofthe greater omentum. The inferior recess now extends inferiorfy only as far as the transverse colon. The rod #ffl/WS pass (A) lnflnt (B)AduH from the greater sac through the omental ScherMIIc saglttaiMCtlonrt, r.teral vt.w foramen into the omental bursa.  Peritone11m and Peritoneal Cavit, 445 Falclfonn Porta hepatis Lesser omentum Finger Is Inserted - *'"""7Hi!5:::::=-- :=i:liii5i through omental foramen into omental bursa Gallbladcler Costodlaphragmatlc (pleural) recess 10th r i b - - - - - - ;M; Anastomosis between 11th c o a t a l - - - --¥'-;:1\.'\\ rtght and left cartilage arteries TranaverstJs abdomlnls colon appearing In an unusual gap In the greater Anterior view omentum FIGURE 5.29. Ometttal (epiploic) foramen and omental burn. The index finger is passing !Tom the greater sac through the oment.al foramen into the omental bursa (lesser sac). The hepatoduodenalligament is being pinched between thumb and index finger, which would compress the structures ofthe portal triad (portal vein, hepatic anery, and bile duct). CLINICAL BOX PERITONEUM AND PERITONEAL the peritoneum (laparotomy) than they do with smalllapa- roscopk incisions or vaginal operations. CAVITY It is the covering of visceral peritoneum (often referred Patency and Blockage of Uterine Tubes to clinically as the serosa) that makes watertight end-to-end anastomoses of intraperitoneal organs, such as the small While theoretically it is possible for organisms to intestine, relatively easy to achieve. Surgeons refer to this as enter the female peritoneal cavity directly via the reperitonealization. It is more difficult to achieve watertight uterine tubes, such primary peritonitis is rare, anastomoses of extraperitoneal structures that have an outer bearing testimony to the effectiveness of the protective adventitial layer, such as the thoracic esophagus. mechanisms of the female reproductive tract. A primary Because of the high incidence of complications such as mechanism in preventing such infection is a mucous plug peritonitis and adhesions (see the Clinical Box "Peritoneal that effectively blocks the external os (opening) of the uterus Adhesions and Adhesiotomy,.. p. 446) after operations in to most pathogens, but not to sperm cells. The patency uf which the peritoneal cavity is opened. efforts are made to th8 uterine tube.s can be tested clinically by means of a tech- remain outside the peritoneal cavity whenever possible (e.g., nique in which air or radiopaque dye is injected into the uter- translumbar or extraperitoneal anterior approach to the kid- ine cavity, from which it normally flows through the uterine neys). When opening the peritoneal cavity is necessary, great tubes into the peritoneal cavity (hysterosalpingography; see effort is made to avoid contamination of the cavity. Chapter 6, Pelvis and Perineum, for more details). Peritonitis and Ascites The Peritoneum and Surgical When bacterial contamination occurs during lapa- Procedures rotomy. or when the gut is traumatically penetrated Because the peritoneum is well innervated, or ruptured as the result ofinfection and in.Oamma- patients undergoing abdominal surgel}' experience tion (e.g. appendicitis). allowing gas, fecal matter, and bac- more pain with large, invasive, open incisions of teria to enter the peritoneal cavity. the result is infection and 446 ChapterS Abdomen inflammation of the peritoneum---peritonitis. Exudation of Abdominal Paracentesis serum, fibrin, cells, and pus into the peritoneal cavity occurs, accompanied by pain in the overlying skin and an increase in Most cases of peritonitis are seoondary, having a the tone of the anterolateral abdominal muscles. Given the surgical cause. Ascites can result from cirrhosis of extent of the peritoneal surfaces and the rapid absorption of the liver or in association with malignancy. In rare material, including bacterial toxins, from the peritoneal cav- cases, individuals with chronic ascites from a condition such ity, when a peritonitis becomes gen6f'alized {widespread in as cirrhosis vv:ill develop primary peritonitis in which the asci- the peritoneal cavity), the condition is dangerous and perhaps tes beoomes infected without a surgical cause. lethal. In addition to the severe abdominal pain, tenderness, Treatment of generalized peritonitis includes removal of nausea and/or vomiting. fever, and constipation are present. the ascitic fluid, forreliefwhenlarge amounts are present, and General perltonitt.s also occurs when an ulcer perforates diagnosis (e.g., culture). In the presence of infection, large the wall of the stomach or duodenum, spilling its acidic con- doses of antibiotics are administered. Occasionally, more tents into the peritoneal cavity. Excess fluid in the perito- localized accumulations of fluid may have to be removed for neal cavity is called ascitic fluid. The clinical condition in analysis. Surgical puncture of the peritoneal cavity for the which one has ascitic fluid is referred to as ascites. Ascites aspiration or drainage of fluid is called paracentesis. After may also occur as a result of mechanical injwy (which may injection of a local anesthetic agent, a needle or trocar and a also produce internal bleeding) or other pathological condi- cannula are inserted through the anterolateral abdominal wall tions, such as portal hypertension (venous congestion), wide- into the peritoneal cavity through the linea alba, for example. spread metastasis of cancer cells to the abdominal viscera, The needle is inserted superior to the empty urinary bladder, and starvation (when plasma proteins fail to be produced, in a location that avoids the inferior epigastric artery. altering concentration gradients and producing a paradoxi- cally protuberant abdomen). hl all these cases, the peritoneal Peritoneal Dialysis cavity may be distended with several liters of abnormal fluid, interfering with movements of the viscera. The peritoneum is a semipermeable membrane Rhythmic movements of the anterolateral abdominal wall with an extensive surface area, much of which normally acoompany respirations. If the abdomen is drawn in (subdiaphragmatic portions in particular) overlies as the chest expands (pamduxical aJxlomirwthorocic ihythm) blood and lymphatic capillary beds. Therefore, fluid injected and muscle rigidity is present, either peritonitis or pneumonitis into the peritoneal cavity is absorbed rapidly. (inflammation ofthe ltmgs) may be present. Because the intense In nmal faaure, waste products such as urea accumulate pain worsens with movement, people with peritxmitis commonly in the blood and tissues and ultimately reach fatal levels. lie with their knees flexed to relax their anterolateral abdominal Peritoneal d4alysis may be performed in which soluble sub- muscles. They also breathe shallowly (and hence more rapidly), stances and excess water are removed from the system by reducing the intra-abdominal pressure and pain. The suction transfer across the peritoneum, using a dilute sterile solu- effect of the diaphragm during resp:iralion draws fluid (e.g., tion that is introduced into the peritoneal cavity on one side from a perforated viscus) into the subphrenic spaces. Hence, and then drained from the other side. Diffusible solutes and subphrenic abscess is a frequent oomplication ofperitonitis. water are transferred between the blood and the peritoneal cavity as a result of concentration gradients between the two Peritoneal Adhesions fluid compartments. Peritoneal dialysis is usually employed only temporarily, however. For the long term, it is preferable and Adhesiotomy to use direct blood flow through a renal dialysis machine. If the peritoneum is damaged, by a stab wound, for example, or infected, the peritoneal surfaces become inflamed, making them sticky with fibrin. Functions of Greater Omentum As healing occurs, the fibrin may be replaced with fibrous The greater omentum, large and fat-laden, pre- tissue, forming abnormal attachments between the visceral vents the visceral peritoneum from adhering to the peritoneum of adjacent viscera, or between the visceral.. parietal peritoneum. It has considerable mobil- peritoneum of an organ and the parietal peritoneum of the ity and moves around the peritoneal cavity with peristaltic adjacent abdominal wall. Adhesions (scar tissue) may also movements of the viscera. It is called the "policeman of the form after an abdominal operation (e.g., owing to a ruptured abdomen" because it goes to the site of trouble. It often appendix) and limit the normal movements of the viscera. forms adhesions adjacent to an inflamed organ, such as the This tethering may cause chronic pain or emergency com- appendix, sometimes walling it off and thereby protecting plications such as intestinal obstruction when the intestine other viscera from it. Thus, it is common when entering the becomes twisted around an adhesion (ooloolus). abdominal cavity, in either dissection or surgery, to find the Alllu1sioly$1$ refers to the surgical separation ofadhesions. omentum markedly displaced from the "normal" position in Adhesions are often found during dissection ofcadavers (see, which it is almost always depicted in anatomical illustrations. e.g., the adhesion binding the spleen to the diaphragm in The greater omentum also cushions the abdominal organs Fig. 5.39B). against injury and forms insulation against loss of body heat.  Peritoneum and Peritoneal Cavity 447 Abscess Formation Fluid in Omental Bursa Perforation of a duodenal ulcer, rupture of the gall- Perforation of the posterior wall of the stomach bladdm; or perforation of the appendix may lead to results in the passage of its fluid contents into the the formation of an abscess (circumscribed oollection omental bursa. An inflamed or injured pancreas of purulent exudate, i.e., pus) in the subphrenic recess. 1'he can also result in the passage of pancreatic fluid into the abscess may be waDed inferiorly by adhesions of the greater bursa, forming a pancreatic pseudocyst. omentum (see the Clinical Box"Subphrenic Abscesses," p. 507). Internal Hernia Through Omental Spread of Pathological Fluids Foramen (t) Peritoneal recesses are ofclinical importance in con- nection with the spread of pathological fluids such as pus, a product of inflammation. The recesses deter- mine the extent and direction of the spread of fluids that may Although uncommon, a loop of small intestine may pass through the omental foramen inti> the omental bursa and be strangulated by the edges of the fora- men. As none of the boundaries of the foramen can be incised enter the peritoneal cavitywhen an organ is diseased or injured. because each contains blood vessels, the swoDen intestine must be decompressed using a needle so it can be returned to the Flow of Ascitic Fluid and Pus greater sac ofthe peritoneal cavitythrough the omental foramen. The paracolic gutters are of clinical importance (-, because they provide pathways for the How of Temporary Control of Hemorrhage \J ascitic fluid and the spread ofintraperitoneal infec- from Cystic Artery tions (Fig. 5.27B). Pumlent material (consisting of or con- taining pus) in the abdomen can be transported along the The cystic artery must be ligated or clamped and paracolic gutters into the pelvis, especially when the person then severed during cholecystectomy, removal ofthe is upright. Thus, to facilitate the flow ofexudate into the pel- gallbladder. Sometimes, however, the artery is acci- vic cavity where absorption of toxins is it is relatively easy to dentally severed before it has been adequately ligated. The sur- drain, patients with peritonitis are often placed in the sit- geon can control the hemorrhage by compressing the hepatic ting position (at least a 45° angle). Converse)y, infections in artery as it traverses the hepatoduodenalligament 11le index the pelvis may extend superiorly to a subphrenic recess situ- finger is placed in the omental foramen and the thumb on its ated under the diapluagm (see the Clinical Box "Subphrenic anterior wall (Fig. 5.29). Alternate compression and release of Abscesses," p. 507), especially when the person is supine. pressure on the hepatic artery allows the surgeon to identify Similarly, the paracolic gutters provide pathways for the the bleeding arteJy and clamp it. This is also done sometimes spread of cancer cells that have sloughed from the ulcerated to provide temporary control during cases of severe trauma tn surface of a tumor and entered the peritoneal cavity. the liver or associated structures ("Pringle maneuver"). e ottomline PERITONEUM, PERITONEAL CAVI'IT, AND PERfl'ONEAL FORMATIONS Perkaneum and peritoneal cavity: The peritoneum is a abclominopelvic cavity. Parts of the peritoneum aJso occur continuous, servus membrane dlat lines d1e abdominopelvic as double folds (mesenteries and omenta. and subdivisions cavity (the parietal peritoneum) and the contained viscera called ligaments) that convey neurovascular-structures and the (the visceral peritoneum). The collapsed peritoneal ducts ofa.:cessory organs to and from the viscera. Peritoneal cavity betWeen the parietal and visceral peritoneum ligaments are named for the particular struCUJres connected by normally contains only enough peritoneal fluid (about 50 them. As a result ofthe rotation and exuberant growth ofthe ml) to lubricate the inner surface of the peritoneum. This intestine during development, the disposition ofthe peritoneal arrangement allows d1e gut the fTeedom of movement cavity becomes complex. The main part ofche peritoneal I"'!C!uired for alimentation (digestion). Adhesions formed as cavity (greater sac) is divided by the transverse mesocolon into a result of infection or injury interfere with these movements. supracolic and infracolic compartments. A smaller part of the The parietal peritoneum is a sensitive, semipermeable peritoneal cavity, the omental bursa (lesser sac:) lies posterior membrane, with blood and lymphatic capillary beds especially to the stomach, separating it from retroperitoneal viscera on abundant deep to its subdiaphragmatic surface. the posterior wall. It communicates with the greater sac via the fannatioN ancl IUbdlviiiOIII ofperilloneal omental foramen. The complex disposition ofthe peritoneal CIIYity: Continuities and connections between the visceral and cavity determines the flow and pooling ofexcess (ascitic) fluid parietal peritoneum the gut enten and exits the occupying the perimneaJ cavity during pad!ological conditions.