Surgical Anatomy of the Abdominal Wall

Surgical Anatomy of the Ahdominal Wall ERNEST

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LAMPE, M.D., F.A.C.S. *

speaking, the part of the abdominal wall which interests most surgeons is bounded laterally by the right and left mid axillary lines; superiorly by the costoxiphoid margins; and inferiorly by the pubic crest, the inguinal ligaments and anterior halves of the iliac crests. This is understandable, since most abdominal incisions and hernias involve this area. Obviously, for these purposes, muscles, their nerve supply, aponeuroses, sheaths, fasciae and fascial planes are and have been stressed. In recent years, advances in the diagnosis and treatment of cancer and vascular disease have impressed surgeons with the importance of knowing not only the local lymph and blood supply but their relation to other parts of the body. This being the case, a more thorough knowledge of that part of the abdominal wall posterior to the midaxillary lines, especially its blood vessels, lymphatics and nerves, will be necessary. Therefore, in addition to reviewing the abdominal wall layer by layer as it relates to incisions and hernias, an attempt will be made to point out the relation of its important blood vessels and lymphatics to the remainder of the body. While it is taken for granted that the reader will note nothing new in"this article, it is, nevertheless, hoped that its approach and stress of the previously unstressed will make its reading worth while. GENERALLY

LAYER-LIKE STRUCTURE OF THE ABDOMINAL WALL

Broadly speaking, the abdominal wall can be divided into seven layers (Fig. 175), which may be easier to remember if considered in the following manner: Think of the fourth or middle layer as the muscle-bone layer, consisting on either side of the midline of nine muscles, their fasciae and aponeuroses, and posteriorly, the five lumbar vertebrae (Figs. 175, 183). Superficial to the fourth layer are the first, second and From the Department of Surgery, New York Hospital-Cornell Medical Center, New York.

* Assistant Professor of Surgery and of Clinical Anatomy, Cornell University Medical College; Assistant Attending Surgeon, New York Hospital; Attending Surgeon, ,Cornell Surgical Division, Bellevue Hospital.

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third layers (respectively, the skin, superficial fascia and deep fascia); deep to the fourth layer are fifth, sixth and seventh layers (respectively, the transversalis fascia, subserous or extraperitoneal fat and peritoneum). Because the fourth or muscle-bone layer is the most important, it

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Fig. 175. CROSS SECTION OF SEVEN LAYERS OF ABDOMINAL WALL 1. Skin-first layer. 2. Superficial fascia-second layer. 3. Deep fascia-third

layer. 4. External oblique, internal oblique, transversus abdominis muscles of the fourth or muscle-bone layer. Each muscle has fascial layer on superficial and deep aspect. 5. Transversalis fascia-fifth layer. 6. Extraperitoneal or subserous fat of sixth layer. 7. Peritoneum-seventh layer. 8. Fusion point of three layers of lumbodorsal fascia. 9. Middle layer of lumbodorsal fascia. 10. Posterior layer of lumbodorsal fascia. 11. Anterior layer of lumbodorsal fascia. 12. Right and left sympathetic trunks behind inferior vena cava and aorta respectively. 13. Peritoneum reflected off posterior abdominal wall as mesentery of intestine. 14. Transversalis fascia-also lines abdominal cavity but is not reflected on to viscera. 15. Aponeurosis of transversus abdominis fusing to posterior rectus sheath. 16. Aponeurosis of external oblique fusing to anterior rectus sheath. 17. Aponeurosis of internal oblique splitting to form anterior and posterior rectus sheath.

will be considered at once. Recall that on either side of the linea alba are the right and left rectus abdominis and pyramidalis muscles enveloped between the anterior and posterior rectus sheaths, formed by a splitting of the aponeuroses of the internal oblique muscles (Figs. 175, 176). Lateral to the rectus abdominis and pyramidalis are the third, fourth and fifth muscles: the external oblique, internal oblique and transversus abdominis muscles, their fasciae and aponeuroses (Figs. 175,

Surgical Anatomy of Abdominal Wall 176). These three muscles extend laterally and posteriorly from the lateral border of the rectus abdominis practically to the lateral border of the posteriorly situated quadratus lumborum muscle-the sixth muscle. Note that this sixth muscle is attached to medial half of the twelfth rib, to a part of the posterior third of the crest of the ilium, and medially to the transverse processes of the upper four lumbar vertebrae (Fig. 177). Next is the seventh of the nine muscles: the psoas major muscle, semilunar-shaped on cross-section and running downward along the anterolateral aspect of the lumbar vertebrae to insert into the lesser trochanter of femur (Fig. 177). The psoas minor being inconstant will not be described. The eighth muscle is the massive sacrospinalis or erector spinae, found on either side of the vertebral spines, and extending from the dorsum of the sacrum to the base of the skull. Only the lower portion of the important latissimus dorsi forms the ninth muscle (Figs. 175, 178). These, then, are the nine muscles which, with the lumbar vertebrae, form the middle layer of the seven layers of the abdominal wall. More details regarding them will be given later. Observe that external and internal to this fourth or muscle-bone layer are three layers (Fig. 175), and how they can be compared to one another: Externally, from without inward are layers one, two and three consisting respectively of the skin, subcutaneous fat or superficial fascia and the deep fascia; whereas, internally, from peritoneal cavity outward to the fourth layer are layers seven, six and five-consisting respectively of peritoneum, comparable to the skin; subperitoneal or subserous fat, comparable to the subcutaneous fat; and transversalis fascia, comparable to the deep fascia. This simple review of elementary abdominal wall anatomy merely emphasizes its layer-like structure. General academic details regarding the seven layers can be found in any standard textbook of anatomy; therefore, they will not be considered in this article. However, certain pertinent surgical anatomic features regarding each layer will be mentioned in the following paragraphs. I. SKIN

Whenever possible, some surgeons like to consider Langer's lines in making an abdominal incision. Generally speaking, however, they do not determine the position or direction of an incision. For obvious reasons, the Pfannenstiel inC£sion is used in selected cases of female pelvic surgery. II. SUBCUTANEOUS FASCIA

Standard textbooks of anatomy point out a change in character of this fatty layer in the lower abdominal wall and perineum. Fat, like other tissues or organs, has a stroma or framework of fibrous tissue to support the fat cells. How its amount and distribution in both the subcutaneous andextraperitoneal fat layers affects their characters will be described in subsequent paragraphs. It is well known that the character of the subcutaneous fascia or fatty

Ernest W. Lampe layer varies in different parts of the body. How different the tough, densely fibrous subcutaneous fat of the palm of the hand, sole of the foot, scalp and gluteal regions is from the soft, almost fluffy fat of the upper abdomen! Function and evolution doubtless account for this. Anatomy books describe a difference in character of the subcutaneous fascia or fat of the upper from that of the lower anterior abdominal wall. There appears to be sufficient concentration of fibrous stroma in the deep part of the subcutaneous fascia of the lower abdominal wall to form a fibrous fascial layer given the name of Scarpa's fascia. The soft and more superficial fat of the subcutaneous layer is called Camper's fascia, and it has much less of the fibrous element-much like that of the upper abdomen (Fig. 176). Scarpa's fascia extends a few centimeters below the inguinal ligament to fuse with the fascia lata (deep fascia) of the thigh. This probably explains why urine from a ruptured urethra frequently extravasates much more readily toward the costal margin than down the thigh. It probably also explains why a femoral hernia has a tendency to progress cephalad-over the inguinal ligament rather than toward the patella. Be it recalled that Scarpa's fascia extends on to the dorsum of the penis as the fundiform . ligament, and also extends down into the perineum where it is known as Calles' fascia. Here, on each side, it becomes firmly adherent to the inferior pubic rami, and posteriorly with the epimysium of the superficial transverse perineal muscles, thus forming the roof of the superficial perineal pouch. These attachments have a tendency to prevent urine from a ruptured urethra from extravasating down the medial aspect of the thighs or toward the anus; and, instead, directing it upward under Scarpa's fascia on the abdominal wall. In the scrotum, Scarpa's fascia is replaced by the dartos muscle; and, on the penis, Scarpa's fascia is referred to as the dartos of the penis. Extravasating urine gets under both layers. Some investigators question the presence of a Scarpa's fascia. I have noticed that it is much easier to demonstrate on fresh bodies than on those embalmed a long time. It can almost always be demonstrated in the performance of an inguinal hernioplasty. Like fasciae elsewhere, it may vary in its texture, extent and attachments. In some bodies, Scarpa's fascia is thin and even fenestrated; in other, it is quite substantial. It may havea solid or insular line of attachment below Poupart's ligament and thus account for wider urine extravasations than usually occur, or the descent of a femoral hernia much farther down the thigh than is to be expected. The significance of the blood vessels and lymphatics of the superficial fascia will be considered in the discussion of the blood and lymph supply of the abdominal wall. III. DEEP FASCIA

The deep fascia is not an important layer of the abdominal wall. It is much easier to demonstrate on the muscular part of the external oblique than on its aponeurosis where it is quite firmly adherent. As the testicle passes through the external inguinal ring en route to the scrotum, it drags the deep fascia with it; .

Surgical Anatomy of Abdominal Wall and, subsequently, it is known as the external spermatic fascia of the spermatic cord and testicle. On the penis, it is commonly called Buck's fascia. The deep fascia and superficial fascia are approximated loosely to each other by loose areolar tissue. It is mentioned because, in doing hernioplasties, this is the delicate tissue many surgeons at one time actually rubbed off the external oblique aponeurosis to be sure it was "clean and shiny." It is known now that this delicate areolar tissue contains many so-called "wandering cells," which, according to Maximov, can perform two roles: a defensive role, along with the polymorphonuclear leukocyte, in case of infection, and a reparative role with the fibroblasts when repair commences. Obviously, fat particles should be removed, but it is better not to rub this delicate areolar tissue off the aponeurosis of the external oblique. IV. MUSCLE-BONE LAYER

As stated previously, the fourth or muscle-bone layer is the most important of the seven layers of the abdominal wall. This is to be expected because of the effect abdominal incisions and the various types of hernia may have upon it. MAJOR MuscLEs

Rectus Abdominis Muscle

Figure 176 shows the rectus abdominis extending from the pubic crest to the fifth rib. Note the three tendinous inscriptions between the costal margin and level of the umbilicus. Frequently, a fourth is present a short distance below the umbilicus. These fibrous septa make the rectus muscle less vulnerable to rupture. They are firmly attached to the anterior rectus sheath, thereby making it much easier to free the muscle from the unattached posterior sheath in making a paramedian, muscle-retracting incision. Transection of the rectus abdominis muscle in a transverse abdominal incision would result in too much retraction of the muscle ends, were it not for the tendinous inscriptions. In a closure, a series of Halsted mattress sutures applied to the edges of the transversely cut anterior sheath approximates the ends of the muscle just enough to result ultimately in the formation of new tendinous inscription. Below the level of the umbilicus, tendinous inscriptions are apt to be absent, thus causing greater retraction of the muscle ends-unless three or four muscle-sheath transfixing sutures were placed just above and below the transverse sheath incision before transecting the muscle. The nerve supply is from the lower six intercostal and first lumbar nerves. Observe the seventh intercostal nerve paralleling the costal margin as it terminates near the tip of the xiphoid (Fig. 176). Note the tenth intercostal Rerve at about the level of the umbilicus, and branches of the first lumbar nerve just above the pubic crest. It is generally accepted that in making a longitudinal, rectusmusclesplitting incision, one, and usually two, intercostal nerves can be cut with impunity; but cutting a third nerve is very apt to result in an atrophy of the denervated medial portion of the muscle. In a heavy laborer, herniation, or at least a weakening of the abdominal wall, may

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be the end result. This possibility suggests that, if a long longitudinal incision is necessary, a paramedian, muscle-retracting type is the better of the two. As every surgeon knows, it requires a longer time; but no motor nerves are injured, regardless of the length of the incision. Addi-

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Fig. 176. ANTERIOR ABDOMINAL WALL 1. Pectoralis major. 2. Serratus anterior. 3. Upper part of anterior rectus sheath. 4. Linea alba. 5. Skin. 6. Camper's fascia. 7. Scarpa's fascia. Note its fusion at 14-fascia lata of thigh. 8. Transversus abdominis. 9. Internal oblique reflected. 10. Right rectus abdominis (cut). 11. Semicircular line or fold of Douglas. 12. Arching fibers of transversus abdominis. 13. Poupart's ligament. 14. Fascia lata. 15. Pyramidalis muscle. 16. Left rectus abdominis muscle. 17 . Inconstant tendinous inscription. 18. Three constant tendinous inscriptions (including one above number and one below). 19. Transversus abdominis. 20. Nerves and blood vessels. 21. Fundiform ligament of penis. 22. Aponeurosis of transversus abdominis. 23. Conjoined tendon. 24. Cooper's ligament. 25. Reflex inguinal ligament. 26. Gimbernat's or lacunar ligament.

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tional comments on the transverse incision will be made when the internal oblique and transversus abdominis muscles are discussed. The importance of the blood vessels of the rectus abdominis will be discussed in subsequent paragraphs. External Oblique Muscle

The external oblique muscle is seen, in Figures 175 and 176, to originate from the anterolateral aspects of the lower six ribs. Its fibers run downward and inward. Note its most lateral portion inserting into the anterior half of the crest Qf the ilium, and its posterior border forming the anterior border of Petit's triangle (Fig. 178). Observe that 2 to 4 fingerbreadths below the costal margin it becomes aponeurotic. The usual subcostal cholecystectomy incision is 2 or 3 fingerbreadths below and parallel to the costal margin, transecting the muscular or adjacent aponeurotic portion of the external oblique muscle. The upper part of the muscle usually retracts above the costal margin under the superficial fascia, so that on closing the abdomen, it is frequently forgotten and left incompletely sutured. The inferior border of the aponeurosis forms Poupart's ligament, which is attached to the anterior, superior iliac spine and pubic tubercle. Just before attaching itself to the pubic tubercle, Poupart's ligament sends a lacunar-like cluster of fibers to the superior ramus of the pubic bone (Fig. 176). These fibers are known as lacunar or Gimbernat's ligamentnot to be confused with Cooper's ligament (Fig. 180), which is more posterior and attached to the pectineal crest. Medially, the aponeurosis fuses with the anterior rectus sheath, 1 to 2 cm. medial to the lateral border of the rectus abdominis muscle (Fig. 175). Occasionally, in making a longer-than-usual transverse abdominal incision, the internal oblique and transversus abdominis muscles can be split in the direction of their fibers more easily if the overlying and transversely incised external oblique aponeurosis is also incised a comfortable distance upward and downward about a half centimeter from its line of fusion with the anterior rectus sheath. This creates superior and inferior flaps of the external oblique aponeurosis which can be opened widely for easier splitting of the two underlying muscles. This type of transverse incision obviously causes little, if any, nerve injury. In the closure, the external oblique aponeurosis should be reattached to the anterior rectus sheath. Sometimes, in the repair of a large direct hernia, it is difficult to approximate substantial transverse abdominis aponeurosis and transversalis fascia to Poupart's ligament-or to Cooper's ligament, if a McVey hernioplasty is being done. A semilunar incision of the lower end of the anterior rectus sheath usually takes the tension off the suture line, but leaves the rectus muscle uncovered. Because the lower part of the external oblique aponeurosis frequently fuses with the anterior rectus sheath 2 cm. or more medial to the lateral border of the rectus abdominis muscle, the above semilunar releasing incision can often be made deep to the external oblique aponeurosis just lateral to where it fuses with the anterior rectus sheath. This prevents tension on the suture

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line and still leaves the lower medial part of the external oblique aponeurosis to cover the rectus muscle. Internal Oblique Muscle

The internal oblique muscle arises from about the lateral half of Poupart's ligament, anterior half of the iliac crest, and the lumbodorsal f~scia (Fig. 175). Generally speaking, its fibers run upward and inward-just the opposite direction of the external oblique. The most medial of the

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Fig. 177. SOME ANATOMICAL PITFALLS OF LUMBAR SYMPATHECTOMY * Quadratus lumborum muscle. ** Psoas major muscle. *** Iliacus muscle. 2. Femoral nerve along lateral border of psoas muscle. Genitofemoral nerve on anterior aspect of psoas muscle. Obturator nerve along medial border of psoas muscle. 3. Chain of prevertebrallymph nodes. 4. Tendinous fasciculae of psoas muscle. 5. Chain of lumbar sympathetic ganglia. 1. Transversus abdominis muscle.

fibers arising from the inguinal ligament arch upward and medially a variable distance. Then, as they go downward and medially, they become aponeurotic and insert into the pubic tubercle (Fig. 176). Sometimes the fibers form a very high arch, a condition said to predispose to direct hernias. Some of the underlying aponeurotic fibers of the transversus abdominis fuse with the aponeurotic fibers of the internal oblique to form the so-called conjoined tendon, which, as stated above, inserts into the pubic tubercle. The uppermost fibers of the internal oblique insert into the costal margin (lower six ribs). All the remainder of the muscle becomes a wide aponeurosis which splits to form the anterior and posterior rectus sheath, which then fuses medially with its fellow of the opposite side to form the linea alba, extending from xiphoid process to the pubic

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symphysis (Figs. 175, 176). The posterior rectus sheath extends only to the fold of Douglas (Fig. 180), about half way between umbilicus and pubic crest. The anterior rectus sheath extends as high as the fifth costal cartilage (Fig. 176). In performing a radical mastectomy, the surgeon usually excises the sheath from this level down to a point just beyond the costal margin. Inferiorly, the anterior rectus sheath is attached to the pubic crest. The posterior rectus sheath extends from the costal margin to the semicircular fold of Douglas, usually described as being midway between the umbilicus and pubic crest, but it may be 1 or 2 fingerbreadths above or below this level (Fig. 180). In the supraumbilical portion of the linea alba are usually found small elliptical openings to permit the passage of nerves and blood vessels. Occasionally, one of the openings may be so large as to permit not only extrusion of extraperitoneal fat but peritoneum to form an epigastric hernia. There sometimes occurs a weakness in the linea semilunaris where the inferior epigastric vessels meet the lateral border of the rectus abdominis muscle, thus making possible the formation of a spigelian or lateral ventral hernia. They are not common. Transversus Abdominis Muscle

The transversus abdominis (Fig. 175) arises inferiorly from about the lateral third of Poupart's ligament and subjacent iliopsoas fascia, and about the anterior three-fourths of the crest of the ilium. Its midportion arises from the lumbodorsal fascia (Fig. 175); its upper portion from the lower six ribs where its digitations interdigitate with those of the diaphragm. There is a delicate fascia on its superficial and deep surface. These fasciae fuse with the aponeurosis of the muscle. The underlying transversalis fascia is also in intimate contact with the aponeurosis, especially as it forms the posterior wall of the inguinal canal (Fig. 180). Its upper and mid portions have an aponeurotic insertion mostly into the posterior rectus sheath. Its lowermost part helps form the anterior rectus sheath. Usually, the muscle becomes aponeurotic near the lateral border of the rectus muscle; but frequently, in its upper portion, transverse muscle fibers are transected in making an upper abdominaL vertical paramedian incision-meaning that sometimes the muscle may not become aponeurotic until near the linea alba. At the fold of Douglas (about midway between the umbilicus and pubic crest), it passes anterior to the rectus abdominis muscle to fuse with the aponeurosis of the internal oblique and external oblique to form the anterior rectus sheath. The lowermost fibers arch (arching fibers) over the spermatic cord at the internal inguinal ring in the same manner as do those of the internal oblique (Figs. 176, 180). According to most textbooks, these arching fibers become aponeurotic and fuse with the superjacent aponeurosis of the internal oblique to form the so-called conjoined tendon which inserts into the pubic tubercle. Anson and McVey found that, while some of the aponeurotic fibers of

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the transversus abdominis do fuse with those of the internal oblique to form a conjoined tendon, most of the transverse aponeurosis and its fasciae continue downward to gain attachment to Cooper's ligament (Fig. 180). (A word of explanation must be offered as to the use of the word

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6--...., Fig. 178. BACK MUSCLES AND AUSCULTATORY TRIANGLE (Note fingers in auscultatory triangle. Finger extending upward is in bloodless fascial plane deep to trapezius and rhomboid muscles. Finger extending downward is in bloodless fascial plane deep to latissimus dorsi and serratus anterio'r muscles.) 1. Dorsal scapular nerve-motor nerve to second layer of back muscles (levator scapulae, rhomboid minor and rhomboid major muscles, illustrated in dotted lines). 2 and 3. Descending branches of transverse cervical artery and vein. 4. Portion of sacrospinalis muscle. (Costal attachments must be freed in resecting posterior segments of ribs.) 5. Auscultatory triangle, bounded by trapezius, latissimus dorsi and medial border of scapula. 6. Petit's triangle, bounded by latissimus dorsi, external oblique and crest of ilium. 7. Trapezius muscle. 8. Latissimus dorsi muscle. 9. External oblique muscle.

fasciae in the preceding sentence. Note, in Figure 175, that the external and internal oblique and transversus abdominis muscles have a layer of fascia superficially and deeply. These fasciae fuse with the aponeuroses of their respective muscles j hence, one speaks of the aponeurosis of the transversus abdominis and its fasciae. To this, one must add the fact that the transversalis fascia is usually attached to the posterior aspect of the transversus abdominis aponeurosis and its fasciae, especially where it forms most of the posterior wall of the inguinal canal.)

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Most textbooks mention the fact that within the inguinal canal the spermatic cord has a covering known as the cremaster muscle and its fascia, derived from internal oblique and its fascia; and, deep to this, the infundibuliform or internal spermatic fascia, derived from the transversalis fascia. So many times, in demonstrating the spermatic cord layers at the operating table, I have found one or two delicate fascial layers between the cremaster muscle and transversalis fascia. The only logical way they could be accounted for was to assume that fasciae of the transversus abdominis (superficial and deep aspects) (Fig. 175) were carried down as the testicle made its descent to the scrotum. Sometimes, these extra fascial layers are "filmy-thin" and difficult to isolate; at other times they are demonstrably substantial. While one frequently sees a surprisingly thick layer of cremaster muscle and fascia, it is not at all uncommon to see only a few scattered cremaster muscle fibers and fascia. During the repair of a small indirect hernia, one quite often notices that the arching fibers of the internal oblique and its conjoined tendon are only a few millimeters above Poupart's ligament; in fact, the conjoined tendon may actually be adherent to Poupart's ligament. Obviously, this is the type of posterior 'inguinal canal wall which prevents the formation of a direct hernia; in contrast to arching muscles and tendinous fibers, 2, 3 cc. or even more above Poupart's ligament, which help form a weak posterior inguinal canal wall, thereby creating an ideal "set-up" for the formation of a direct hernia. According to McVey, even though the arching fibers of the internal oblique and its conjoined tendon are, say 1 to 3 cm. above Poupart's ligament, a normally substantial transversus abdominis aponeurosis and its fasciae (transversalis fascia included and adherent posteriorly) will prevent the formation of a direct hernia. Again, according to McVey, "a thinning-out" of this transversus abdominis and its fasciae makes possible a direct hernia. If the direct hernial bulge is not too great and the posterior inguinal canal wall not too thin, a series of plicating sutures may be sufficient to obliterate the bulge. However, when the posterior wall is very thin, as in a large direct hernia, then the "thinned-out" part, according to McVey, should be excised; and the strong upper border of this created hiatus then sutured to Cooper's ligament. Many surgeons feel that the repair is just as good if the upper border is sutured to Poupart's ligament instead of Cooper's ligament. If Poupart's ligament is too relaxed, and there is danger of subsequent formation of a femoral hernia, then the upper border of the transversus abdominis and fasciae (transversalis fascia included) should be sutured to Cooper's ligament, as per McVey. Nerve and Blood Supply

Before the rectus abdominis, external oblique, internal oblique and transversus abdominis are dismissed, mention should be made of their nerve and blood supply; and,. also, the relation of muscles, blood vessels and nerves to abdominal incisions. Figure 176 shows how the nerves and blood vessels lie between the internal oblique and transversus abdominis muscles. The lower six intercostal and first lumbar nerves supply these muscles and the skin overlying them. The first lumbar artery and vein,

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from aorta and inferior vena cava respectively, anastomose with the last intercostal artery and vein above and second lumber artery and vein below. The fourth lumbar artery and vein anastomose above with the third lumbars and below with the iliolumbar artery and vein coming from the internal iliac vessels in the pelvis (Fig. 179). The posterior intercostal

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COLLATERAL CIRCULATION OF LOWER TRUNK AND UPPER THIGH

1. Posterior intercostal veins. 2. Anterior intercostal veins. 3. Internal mammary veins. 4. Anastomosis between fourth lumbar and iliolumbar veins. 5. Anastomosis between iliolumbar and deep circumflex iliac veins. 6. Anastomosis between deep and superficial circumflex iliac veins. 7 and 8. Schematic communication between superior and inferior gluteal vessels of internal iliac with circumflex femoral branches of profunda femoris artery. 9. Internal pudendal vein. 10. Anastomosis of superficial and deep external pudendal branches from femoral vessels with internal pudendal branches from the internal iliac vessels. 11. Anastomosis of obturator vein from internal iliac with medial femoral circumflex branch of profunda femoris veins.

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vessels coming from the subclavian and aorta not only anastomose with each other but anastomose with the anterior intercostals from the internal mammary vessels. The lumbar vessels, posteriorly, are in series with the posterior intercostal vessels; anteriorly, they anastomose with the superior and inferior epigastric vessels in the rectus abdominis muscle (Fig. 179). More will be said about these vessels when the remainder of the blood supply of the abdominal wall will be discussed. Abdominal Incisions It is fitting to associate a few widely used incisions with the names of the great in surgical history. There are, however, now so many incisions with proper names attached to them that it has become quite a chore to remember their exact location and the name to be associated with each one of them. So frequently surgeon A's incision may be a scant centimeter or two above or below or medial or lateral to surgeon B's incision; and along comes surgeon C who decides that an incision just between that of A and B will take him most directly to his immediate problem. Therefore, the author feels it much more logical that each surgeon make his own incision, based, of course, on certain sound surgical and anatomicophysiologic principles. All surgeons agree that an incision should be planned to give as direct approach as possible to the source of trouble; but it should injure no motor nerves, or at the most, one motor nerve; and, with the exception of the rectus abdominis, should not transect the fibers of a muscle. In closing a transverse incision, the stout anterior and posterior rectus sheaths can be approximated so as to oppose nicely the ends of the transected rectus abdominis, the end result being a firm scar resembling one of the nearby tendinous inscriptions. Furthermore, no motor nerves were injured when the incision was made. In making a subcostal incision for a cholecystectomy, the right rectus· and lower most fleshy part of the external oblique must be transected .. So little of the fleshy part of the external oblique is transected that its atrophy is inconsequential. In the closure, the surgeon must -remember to approximate its transected ends, because the upper flap is easily overlooked owing to its contraction out of sight and above the costal margin. In the subcostal incision, the internal oblique and transversus abdominis can be split in the direction of their fibers, injuring, at most, only one motor nerve. This is not enough to cause muscle atrophy because of the overlapping supply from nerves above and below the one that was cut or stretched. In this type of incision, the peritoneum can be closed more easily and securely, because the transversus abdominis not only tends to approximate its edges but it can be included in the peritoneal suture. In making a transverse abdominal incision, the rectus abdominis and the aponeurosis and few fleshy fibers of the external oblique are transected. The internal oblique and transversus abdominis muscles are split in the direction of their fibers, so that, at most, only one motor nerve may have been injured. A suitable layer closure of this type of incision should produce a firmly healed wound. Furthermore, a transverse incision permits a much easier excision of a part of the transversus abdominis

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or transversus abdominis and internal oblique when an ascending or descending colon carcinoma is fixed and gross metastasis is not evident. Postoperative pulmonary complications are not so apt to occur because of less pain on attempting the very important deep-breathing exercises during the first twenty-four postoperative hours. Because a transverse incision requires more time, many surgeons prefer some type of vertical InCISlOn. Of the vertical incisions, the paramedian muscle-retracting incision is the soundest, because, regardless of its length, no motor nerves or muscle fibers are injured. Because it, too, requires more time, some surgeons prefer a vertical muscle-splitting incision; others an incision through the linea alba. The former, if made too far from the midline and too long, obviously results in an atrophy of the medial part of the muscle; the latter is thought by many to be more vulnerable to postoperative herniation because of its relatively meager blood supply. At times, a pararectus incision offers the most direct approach; its drawback being that, if lengthening it traumatizes more than two motor nerves, a partial atrophy and weakness of the involved rectus may follow. To summarize: A surgeon Can make any type of abdominal incision he sees fit, provided he will not injure more than one motor nerve, not transect muscle fibers unnecessarily, and, above all, "put the structures back" in the approximate position they were before the incision was made-in other words, a careful layer closure. OTHER MUSCLES OF THE FOURTH LAYER

The next four muscles, the quadratus lumborum, psoas major, sacrospinalis and latissimus dorsi, along with the lumbar vertebrae, bound the abdominal wall posteriorly (Fig. 175). They are not nearly so important to the general surgeon as the rectus abdominis, external oblique, internal oblique and transversus abdominis muscles.

Quadratus Lumborum, Psoas Major and Iliacus Muscles The quadratus lumborum extends from the posterior third of the crest of the ilium to the medial half of the twelfth rib (Fig. 177). The psoas major arises from the five lumbar vertebrae (Fig. 176) and extends downward to have its tendon fuse with that of the iliacus and insert into the lesser trochanter of the femur. The iliacus muscle)rises from the iliac fossa. Of these three muscles, the psoas major is the most important because of related structures. The upper three lumbar nerves furnish most of the nerve supply. The surgeon doing an extraperitoneal lumbar sympathectomy makes use of the psoas major as an excellent landmark muscle. There are several pitfalls. The lumbar sympathetic chain usually can be found on the anterolateral aspect of the lumbar vertebrae, along the medial border of the psoas major muscle (Figs. 175, 177). Occasionally, the surgeon may lose his way and think he is at the medial border of the psoas muscle, when actually he is at the medial border of the laterally adjacent quadratus lumborum muscle; and before realizing it, he may not only macerate portions of the psoas muscle but truamatize a part of the lumbar plexus. The upper part of the genitofemoral nerve, as it lies on the anterior aspect of the psoas muscle, may be mistaken for the sympathetic chain; but failure to see ganglionic enlargements or rami communicantes warns

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the surgeon of his error (Fig. 177). Sometimes, when it is difficult to locate the chain, the surgeon may be seeking it in the neighborhood of the third lumbar ganglion, and if the psoas muscle does not happen to receive many fibers from the fifth lumbar vertebra, and he is dissecting more posteriorly than he realizes, the obturator nerve may be mistaken for the chain. Again, failure to see ganglionic enlargements and rami communicantes warns the surgeon. If in doubt, stimulation of the nerve causes adductor movement of the thigh. Below the level of the iliac crest, the easily palpated bulge of the psoas muscle should remind him of three nerves: the genitofemoral nerve on its anterior aspect, the large femoral nerve on its lateral border (iliopsoas groove), and the obturator nerve near its posteromedial border (Fig. 177). A slender musculotendinous fasciculus along the medial border of the psoas may deceive momentarily the surgeon seeking the ganglionic chain (Fig. 177). Even a chain of small prevertebral lymph glands has been sent to the pathology laboratory as a chain of sympathetic ganglia (Fig. 177). In searching for the right lumbar sympathetic chain, the overlying inferior vena cava frequently must be retracted medially (Fig. 175); just as the abdominal aorta must be retracted medially when in quest of the left lumbar chain (Fig. 175). And on either side, the lumbar branches of these vessels should be handled very gently if the surgeon wishes a dry operative field. To avoid injury to the ureter, the surgeon endeavors to remain outside not only the peritoneum but the transversalis fascia.

Sacrospinalis or Erector Spinae Muscle A large sacrospinalis or erector spinae muscle is found on either side of the vertebral spines and by means of its sacrolumbar, lumbocostal and costocervical sections extends from the dorsum of the sacrum to the base of the skull (Fig. 175). The posteJ;'ior divisions of the sacral, lumbar, intercostal and cervical nerves furnish the nerve supply. Acting in unison, the two muscles hold the spine erect; individually, they flex the spine lateralward. They oppose the psoas major, rectus abdominis and external and internal oblique muscles which flex the spine. Since lateral fasciculae of the costal part of the muscle extend as far as the angles of the ribs (Fig. 178), some of these must be cut or elevated with a periosteal elevator to permit exposure and removal of the posterior part of a rib or ribs. Near either side of the roots of the vertebral spines are found blood vessels which extend longitudinally from the base of the skull to the sacrum (Fig. 183). While more will be mentioned about them in the paragraphs dealing with the vascular distribution of the abdominal wall, it is important now to point out that it is because of these vessels tha(the orthopedist or neurosurgeon cleaves closely to the vertebral spines or laminae in freeing, with minimal bleeding, the sacrospinalis, so that it can be retracted lateralward for adequate exposure.

Latissimus Dorsi Muscle The latissimus dorsi, last of the posterior group of muscles, arises from the posterior half of the crest of the ilium, where it forms the postlJrior boundary of Petit's triangle (the external oblique and crest of the ilium forming the other two boundaries), and that part of the lumbodorsal fascia attached to the dorsum of the sacrum, lumbar spines and lower six thoracic spines (Fig. 178). Its uppermost fibers arise from the inferior angle of the scapula, where they form the lower boundary of the auscultatory triangle (the scapula and trapezius forming the other two boundaries (Fig. 178).

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Ernest W. Lampe

The fleshy part of the muscle sweeps upward and outward along the axillary border of the scapula (forming most of the posterior axillary fold) to reach the bicipital sulcus of the humerus, where, as a flattened tendon, it inserts (Fig. 178). The reader recalls that the pectoralis major and teres major muscles insert, respectively, lateral and medial to the latissimus dorsi; and that these three powerful adductor muscles of the humerus are attached just distal to the surgical neck of the humerus, thus accounting for the medial malposition of the distal humeral fragment in surgical neck fractures. While the muscle assists the pectoralis major and teres major muscles in adducting and internally rotating the humerus, it is also to be remembered as an important muscle used in chopping and climbing movements. A suggestion to aid in remembering the location of the nerve and vascular supply of this important muscle: With the thumb and index finger of the left hand, grasp the right posterior axillary fold (right latissimus dorsi) at the upper end of the axillary border of the scapula; at this point, the ball of the thumb will press upon the vertically running thoracodorsal nerve, artery, vein and accompanying lymphatics (Fig. 178). These structures supply this muscle, and it is in this area that they must be considered in doing a radical mastectomy. In performing a thoracoplasty or resecting the sixth, seventh or eighth ribs in an esophageal or high gastric resection, the upper part of the latissimus dorsi and lower part of the underlying serratus anterior muscles will be transected; and if the surgeon forgets that they overlie each other, and retract in different directions because of the direction of their fibers, a flap of one of the muscles is easily overlooked on closure. The surgeon likes to remember that the ascultatory triangle is at the medial border of the scapula about two fingerbreadths cephalad to its inferior angle, (Fig. 178). The fibrous tissue covering the triangle is avascular; easy to cut through to develop an avascular plane deep to the latissimus dorsi and serratus anterior if cutting inferiorly and anteriorly (sixth, seventh or eighth rib resection); or an avascular plane deep to the trapezius and underlying rhomboid major and minor muscles, if one has to go cephalad for the resection of a higher rib or ribs (Fig. 178). In the latter case, the surgeon does not get close to the medial border of the scapula because of annoying bleeding from the descending branches of the transverse cervical artery and vein, and the desire to avoid injury to the dorsal scapular nerve which supplies the second layer of back muscles (levatorangulae scapulae, rhomboid major and minor muscles, Fig. 178). Occasionally there is reason for a six rib thoracoplasty, an operation which is apt to permit painful impingement of the inferior angle of the scapula on the seventh rib. In doing a subtotal scapulectomy for relief, the uppermost fibers of the latissimus dorsi must be freed from the inferior angle of the scapula (Fig. 178).

Lumbodorsal Fascia Before leaving the posterior muscles, a few words should be said about the lumbodorsal fascia. Figure 175 shows how the external layer is attached to the tips of the lumbar spines; the middle layer to the tips of the transverse processes; the internal layer to the roots of the transverse processes; and how the three layers fuse to form a single substantial layer which serves as part of the origin of the internal oblique and transversus abdominis muscles. An incision parallel to and about two fingerbreadths below the lateral half of the twelfth rib and extending a variable distance towards the anterior superior iliac spine will pass through the fusion point of the three layers of lumbodorsal fascia and make it easier to split the posterior parts of the internal oblique

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and transversus abdominis muscles in the direction of their fibers. In cutting through the fusion area of the lumbodorsal fascia, 'the first lumbar nerve is usually encountered. With slight modifications, this incision can serve as an approach to the kidney, upper ureter, lumbar sympathetic chain, and the inferior vena cava on the right side and abdominal aorta on the left side. It is also low enough to prevent injury to the pleura, which frequently extends as far as a fingerbreadth below the medial half of the twelfth rib-a point to be remembered, if one is attempting to do an extraperitoneal drainage of a posterior subphrenic abscess (Oschner approach). V. FIFTH LAYER OR TRANSVERSALIS FASCIA

While the transversalis fascia or fifth layer of the abdominal wall lines the abdominal cavity somewhat like the peritoneum, it differs in this important respect: It is not reflected onto and over the abdominal viscera (Fig. 175), except for a partial reflection (visceral layer) onto the viscera of the pelvic cavity (Fig. 181). Because the transversalis fascia is so intimately adherent to the posterior rectus sheath, the three layers -peritoneum, transversalis fascia and posterior rectus sheath-are sutured together in the so-called "peritoneal closure." Lateral to the posterior rectus sheaths, however, the transversalis fascia is so loosely attached to the transversus abdominis, quadratus lumborum and psoas major muscles that it can be freed from them without difficulty-a procedure which raises the kidney and upper ureter out of harm's way in doing the so-called extraperitoneal lumbar sympathectomy. While the pelvic cavity is not being discussed in the present review, it might be mentioned that, on either side of it, at the arcus tendineus or white line (a thickened part of the transversalis fascia extending from the back of the pubic bone to the ischial spine) the transversalis fascia splits to form the superior and inferior layers of pelm'c diaphragmatic fascia (Fig. 181). The greater part of each levator ani muscle originates from the arcus tendineus and proceeds downward and medially to form most of the pelvic floor. The above-mentioned superior and inferior layers of pelvic diaphragmatic fascia, derived by a splitting of the transversalis fascia at the arcus tendineus, cover respectively the superior and inferior surfaces of the levator ani or "hammock muscle of the pelvis" (Fig. 181). The so-called visceral layer of pelvic diaphragmatic fascia is derived from the superior layer and covers the pelvic viscera for a variable distance. The transversalis fascia also stretches across a small part of the pubic arch or angle as the superior layer or "roof"of the deep perineal pouch, within which lies the membranous part of the urethra, Cowper's glands and the voluntary urethral sphincter or so-called "cut-off" muscle. In the lower half of the anterior abdominal wall, the transversalis fascia is noticeably thicker-especially, below the level of the semicircular fold of Douglas (midway between umbilicus and pubic crest). A subumbilical, paramedian, muscle-retracting incision usually reveals the fold of Douglas, the posterior rectus sheath above it, and a noticeably substantial transversalis fascia below it.

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Ernest W. Lampe

If, in the making of a McBurney incision, the surgeon separates gently the fibers of the external oblique, internal oblique and transversus abdominis muscles, and gently elevates the separated edges of the transversus abdominis, he reveals a substantial transversalis fascia. If this procedure is done roughly, the points of the scissors or clamp or the fingers actually tear through the transversalis fascia, creating a rent whose edges retract under the transversus abdominis muscle, and are very apt not to be included in the suture which closes the peritoneum. Whenever a surgeon notices, in closing the peritoneum in a McBurney incision, that the peritoneum seems "very thin" and not much stronger than wet tissue paper, chances are that he has tom a sufficiently large rent in the transversalis fascia to have its edges retract out of sight under the edges of the transversus abdominis muscle, and thus not be included in the so-called peritoneal suture. Obviously, this weakens the abdominal closure; may weaken the abdominal wall; and even lay the groundwork for a future hernia. If it is important to close the transversalis fascia in a hernia repair in the nearby inguinal region, why is it not logical to close the transversalis fascia in the "peritoneal closure" of a McBurney incision? To continue with the description of the transversalis fascia: In the inguinal region, it is also quite substantial, and, along with the aponeuro- . sis and fasciae of the transversus abdominis muscle (with which it is usually fused), forms most of the posterior wall of the inguinal canal (Fig. 180). Immediately medial to the internal inguinal ring, for slightly more than a centimeter, the transversalis fascia alone may form the posterior wall of the inguinal canal. Frequently, in a small, narrow-neck, indirect inguinal hernia, high amputation and closure of the peritoneal sac, plus a mattress suture to the small hiatus in the transversalis fascia, is all that is required for the repair. Whenever a surgeon sees the naked, so to speak, inferior epigastric vessels, he knows he has cut through and is deep to the transversalis fascia. A direct hernia implies a weakness in the posterior wall of the inguinal canal, which, as previously stated, is composed mostly of the transversus abdominis aponeurosis and its fascia, and the underlying intimately adherent transversalis fascia (Fig. 180). If the direct hernia is small and the above structures substantial, some surgeons feel that a series of interrupted plicating sutures may be adequate. If, however, the direct hernia is large and the above structures weak and "thinned-out," they are excised, the excess extraperitoneal fat (really the loose fat of the space or cave of Retzius) removed and the herniating peritoneum excised and the peritoneum closed with a continuous suture. The actual repair of the defect in the posterior wall of the inguinal canal may necessitate making a semilunar, releasing incision in the lower part to the anterior rectus sheath to permit easy approximation of the transversus abdominis aponeurosis and fascia and the transversalis fascia to Poupart's ligament-or to Cooper's ligament if the surgeon is qoing a McVey type of direct hernia repair. The McVey procedure is also used in the repair of a femoral hernia. As the fetal limb bud develops, the femoral artery and vein pull down

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a funnel-like prolongation of transversalis fascia, which is subsequently referred to as the femoral sheath (Figs. 176, 181). In the adult, the femoral sheath extends distad to the inguinal ligament about 4 or 5 em., finally fusing with the adventitia of these vessels. This funnel-like sheath is

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Fig. 180. INTRA-ABDOMINAL VIEW OF INGUINAL REGION 1. Rectus sheath at the linea alba. 2. Transversalis fascia. 3. Semicircular fold of Douglas. 4. Cut through transversalis fascia to demonstrate rectus abdominis muscle and arching fibers of the aponeurosis of the transversus abdominis muscle. 5. Rectus abdominis muscle. 6. Inferior epigastric vessels. 7. Anomalous obturator vessel (so-called corona mortis). Very vulnerable in repair of femoral hernia. 8. Arching fibers of transversus abdominis. 9. Entrance to femoral canal-site of femoral hernia. 10. Cooper's ligament-utilized in the McVey hernioplasty. 11. Cut through transversalis fascia. 12. Obturator foramen. 13. Arcus tendineusthickened lowermost part of transversalis fascia, where it divides to form the superior and inferior pelvic diaphragmatic fascia, between which is found the levator ani muscle. The visceral component of pelvic fascia is derived from the superior pelvic diaphragmatic fascia, and extends upward a variable distance on the pelvic viscera. 14. Three abdominal muscles and their aponeuroses. 15. Transversalis fascia. 16. External iliac vessels. 17. Iliac muscles. 18. Levator ani muscle between the superior and inferior pelvic diaphragmatic fascia layers-derived by a splitting of the lower part of the transversalis fascia. t Abdominal inguinal ring with cord.

divided into three compartments: the most lateral compartment contains the femoral artery, the middle one the femoral vein, and the most medial one forms the femoral canal (Fig. 181). This canal is normally about a centimeter in width at its proximal end; about a centimeter and a half in length; and contains the lymph node of Cloquet. The femoral hernia descends into and enlarges the femoral canal.

564

Ernest W. Lampe VI. THE SIXTH OR SUBSEROUS FAT LAYER

The extraperitoneal or subserous layer (sixth layer of the abdominal wall, Fig. 175), varies in amount and character in different parts of the abdominal cavity.~Basically, it can be considered a layer of rather loose areolar fibrous tissue which contains fat and separates the transversalis fascia (fifth layer) from the peritoneum (seventh layer). This is best seen in very thin individuals. While one of its functions is that)f a potential

I

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Fig. 181. DISPOSITION OF TRANSVERSALIS F AseIA 1. Peritoneum. 2. Transversalis fascia. 3. The three compartments of the

femoral sheath. Lateral compartment contains femoral artery; middle compartment the femoral vein; and the medial compartment forms the femoral canal, containing the gland of Cloquet. Femoral hernia extends into the canal. 4. Femoral sheath formed by femoral prolongation of transversalis fascia. 5. Peritoneum and transversalis fascia overlying bladder. 6. Arcus tendineus where transversalis fascia splits to form superior (7) and inferior (8) pelvic diaphragmatic fascia. Note visceral fascia arising from superior pelvic diaphragmatic fascia.

fat depot, in certain places it contains much less fat than in others: Subdiaphragmatic ally and posterior to the upper half of the posterior rectus sheaths there is the least (falciform ligament excepted). Then lateral ward to about the mid axillary line there is also much less than elsewhere. This makes possible the inclusion of posterior rectus sheath, transversalis fascia, the extraperitoneallayer and peritoneum in one suture line when doing a peritoneal closure in this region. It is also why, in the peritoneal closure in the McBurney area, one can usually include the peritoneum, extraperitoneal tissue and transversalis fascia in one suture line. Recall the difference in amount and character of the subserous fat in the perirenal region and space of Retzius area. The latter is that triangu-

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lar area whose apex is the umbilicus and whose lateral boundaries are the obliterated hypogastric arteries of the fetus. It usually contains much loose fat to permit easy expansion of a full bladder. The stroma or fibrous framework of fat varies in amount and distribution. As just mentioned, the fat in the space of Retzius is very loose, hence contains very little fibrous stroma for its framework. On the other hand, recall the difference around the kidney: There is not only a variable amount of fairly loose, soft fat, but there is a sufficient concentration of fibrous stroma to form a fibrous capsule (the false capsule of the kidney). This is different from the true capsule which hugs the kidney very closely, and is sheathlike in character. Another good example of concentration of the fibrous stroma of the extraperitoneal layer is that which occurs in the pelvis to form supporting ligaments for the cervix uteri -the sacrouterine ligaments or ligaments of M ackenrodt. Thus, it can be seen that the extraperitoneal or subserous layer can act as a tissue-holding peritoneum against transversalis fascia, or it can act in a fat depot (space of Retzius and perirenal fat) , or it can concentrate its fibrous stroma for a supportive or protective role: sacrouterine ligaments and false capsule of kidney. VII. SEVENTH LAYER-PERITONEUM

The peritoneum or seventh abdominal wall layer is that smooth, moist and glistening mesothelial layer which bounds the peritoneal cavity (Fig. 175). The manner in which it is reflected onto the various viscera to form ligaments, mesenteries and folds will not be described in the present review. Because the falciform ligament is frequently encountered in making upper right rectus abdominis incisions, it should be recalled that it is a fold of peritoneum which has in its free border the ligamentum teres, derived from the obliterated umbilical vein of the fetus. It also contains a variable amount of fat, and paraumbilical blood vessels which sometimes bleed annoyingly when cut. These same vessels connect with the left branch of the portal vein, and increase markedly in size in cirrhosis of the liver and help form the well-known caput medusa. At the umbilicus, they anastomose with the superior and inferior epigastric and lumbar vessels. VASCULAR REVIEW

The increased interest in vascular and cancer surgery makes it worthwhile to review the more important blood vessels and lymphatics of the abdominal wall. Even though this review will be quite general, it is hoped it will serve as a sound framework to which the reader can easily add details by referring to any standard textbook of anatomy. And how often apparently unimportant details have a way of surprising us with a very real importance! In this vascular review, reference will be made frequently to Figures 179, 182 and 183. Note that they deal almost entirely with the venous system. Because of lack of space, separate drawings of corresponding arteries were not made. The reader will recall, however, that the poste-

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Ernest W. Lampe

rior segmental vessels, i.e. intercostal and lumbar arteries and veins, lie adjacent to each other, so that, if mention in the text is made of the arteries, one can easily visualize them lying adjacent to the veins. The first and second posterior intercostal arteries are branches of the superior intercostal arteries, which, in turn, arise from the costocervical trunks of the subclavian arteries. All the remaining posterior intercostal arteries and lumbar arteries arise from the descending aorta-a fact not difficult to remember. The anterior intercostal arteries are branches of the internal mammary arteries which come from the right and left subclavian arteries. Because the segmental arterial distribution is not difficult to visualize or remember, most of the available space for drawings was allotted to the veins. They are connected with the azygos-hemiazygos system, and the anterior and posterior vertical venous circulations, which, the reader will note, are somewhat more complicated. As the reader recalls, the trunk of the body (thorax and abdomen) has a certain pattern to its vascular equipment, which, expressed simply, consists of two groups: (1) a series of blood vessels and lymphatics which run roughly in a transverse direction (segmental supply), illustrated by the intercostal and lumbar vessels (Figs. 182, 183); (2) a group of vessels which extend roughly in a vertical direction, illustrated by the several branches of the axillary artery and vein, which stream downward onto the chest wall to not only anastomose with the intercostal vessels but to anastomose with the superficial epigastric vessels, ascending from their origin from the femoral vessels just below Poupart's ligament (Fig. 183). Observe how this particular anastomosis establishes a communication betweenyessels destined for the upper and lower extremities (Fig. 183). Veins and lymph vessels originate from the same mesenchymal tissue, . and are very apt frequently to run a parallel course, so that, if the venous drainage of an area is known, one can usually figure out the lymphatic drainage. In incising through the subcutaneous fascia (Camper's and Scarpa's layers) in an ordinary inguinal hernia incision, one encounters vessels consistently in about the middle and medial ends of the incision; and, if the incision extends laterally farther than usual, a third vessel may be seen. The most lateral is the superficial circumflex iliac vein; the middle one, the superficial epigastric vein; the medial one, the superficial external pudendal vein (Fig. 179). These three veins empty into the great saphenous vein just before it opens into the femoral vein. As is well known, these three veins should be clamped, cut and ligated in doing a high saphenous ligation as part of the procedure for eliminating varicosities of the lower extremity. The companion arteries to these three veins have the same names; are usually quite small; and arise from the femoral artery about 2 cm. below Poupart's ligament. Of these three veins, the middle or superficial epigastric is by far the most important, because it forms the lower part of the well-known thoraco-epigastric anastomosis -the upper half being the lateral thoracic vein, located at the lateral border of the breast and emptying into the axillary vein (Figs. 182, 183). Note how this anastomosis connects the blood supply of the upper and lower extremities, so that it is an important collateral route, if the axil-

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lary vein were ligated near the first rib; or, vice versa, a ligation of the external iliac, common iliac or inferior vena cava. It was stated previously that lymph vessels have a ~endency to follow

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Fig. 182. SCHEMATIC VIEW OF SEGMENTAL COLLATERAL CIRCULATION 1. Right axillary vein and its branches. 2. Superficial circumflex iliac vein anastomosing with the deep circumflex iliac vein. 3. Schematic illustration of anastomosis between intercostal vessels. 4. Three lower intercostals. 5. Four lumbar vessels: first lumbar vessel anastomoses with last lower intercostal vessel; the fourth lumbar (from aorta) anastomoses with iliolumbar from internal iliac. 6. Schematic alignment of the vessels which connect the segmental lumbar vessels (from aorta) with the circumflex femoral vessels from the profunda femoris in the thigh. These connecting vessels from above downward are: iliolumbar and circumflex iliac vessels found along iliac crest, the superior and inferior gluteals (from internal iliac) located respectively in the superior and inferior gluteal areas.

veins. Many of the superficial lymph vessels of the breast drain toward the areola, and usually leave the areolar area by two or three lymph vessels, which drain into lymph glands associated with the above-mentioned lateral thoracic vein, located at the lateral border of the breast (Fig. 183). The lymphatics associated with the above-me~tioned tho-

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Ernest W. Lampe

raco-epigastric anastomosis are no doubt responsible in the occasional cases of metastasis of breast carcinoma to the inguinal lymph nodes. The superficial external pudendal vessels (Fig. 179), which cause the bleeding at the medial end of the inguinal hernia incision, supply· the subcutaneous tissue of the pubic region; and, at the root of the penis and scrotum, anastomose with penile and scrotal branches from the internal pudendal vessels coming from the internal iliac artery and vein within the pelvic cavity. The inferior hemorrhoidal vessels, branches of the internal pudendals, not only supply the anal canal but perianal tissues, where they anastomose indirectly with the external pudendals. This helps explain why, in extensive pelvic resections-bladder, rectum, etc., with ligation of the internal iliacs-there may not be any sloughing of scrotal, penile and labia majora skin. And since lymphatics follow veins, it also explains why malignant lower anal or perianal, penile, scrotal and labia majora lesions may metastasize to some of the inguinal lymph nodes. The superficial circumflex iliac vessels (Figs. 179, 182), the ones which occasionally bleed at the lateral end of a long inguinal incision, extend up to and along the crest of the ilium. Superiorly, they anastomose with fine superficial branches of the fourth lumbar vessels coming from the aorta and inferior vena cava; inferiorly, in the upper gluteal area, they anastomose with small branches of the superior gluteal vessels which come through the greater sciatic notch from the internal iliac artery and vein in the pelvic cavity. Posteriorly, they anastomose with the fine, superficial branches of the iliolumbar vessels, which also come from the internal iliac artery and vein. The deep circumflex iliac vessels, coming from the external iliac vessels just above Poupart's ligament, are mentioned now, because they, too, anastomose with the above-mentioned iliolumbar branches of the internal iliac artery and vein. The name, "iliolumbar," tells one that the vessels are between the lumbar and iliac or gluteal regions; and, also reminds us that they are the anastomotic link between the lowest branches of the abdominal aorta and inferior vena cava (fourth lumbar arteries and veins) and the superior gluteal and inferior gluteal branches arising from the internal iliac arteries and veins within the pelvic cavity (Figs. 179, 182). And more: The descending branches of the inferior gluteals anastomose with the ascending branches of the anterior and posterior circumflex femoral vessels, arising from the profunda femoris artery and vein about 5 cm. below Poupart's ligament (Figs. 179, 182). A series of perforating branches of the profunda femoris continue the anastomotic linkage down to and with the superior branches of the popliteal vessels in the popliteal region. The following review may help one to understand why the lower extremities have a reasonably good blood supply, despite a coarctation of the aorta at the junction of its arch and descending part. It was pointed out in the preceding paragraph how the fourth pair of lumbar arteries (last pair of segmental branches of the aorta) anastomosed inferiorly with the iliolumbar, superior and inferior gluteal branches of the internal iliac to form a collateral route for blood to the lower extremity (Figs. 179, 182). It is also recalled that the fourth lumbar arteries anastomose

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superiorly with the third pair; the third pair with the second pair, the second pair with the first pair, and the first pair of lumbar arteries anastomose with the lowest pair of intercostal arteries (Figs. 179, 182). Then one recalls that the descending part of the thoracic aorta (the part just distal to the coarctation) gives off the lower ten posterior intercostal arteries, which not only anastomose superiorly and inferiorly with each other, but anteriorly with the anterior intercostal vessels coming from the internal mammary arteries, which, in turn, arise from their respective subclavian arteries. It is important to remember that the first and second posterior intercostal arteries do not arise from the aorta; they are branches of the superior intercostal arteries which arise from their respective subclavian arteries. Since the left subc"tavian artery arises directly from the aortic arch, and the right subclavian usually from the innominate artery, the first branch of the aortic arch, it becomes understandable why there is such a marked increase in caliber of the superior intercostal artery and its first and second posterior intercostal branches, which form a surprisingly large anastomosis with the third, fourth, and other pairs of lower posterior intercostal arteries arising from that part of the descending thoracic aorta which is distal to the coarctation. This "hook-up" forms the arterial anastomosis on the posterior thoracic and abdominal walls, which permits more blood to reach the lower extremity. In the above-mentioned coarctation, the internal mammary arteries, arising from their respective subclavian arteries, are also increased in size. As they descend about a centimeter lateral to the sternal margins, they give off the anterior intercostal arteries, which anastomose with each other, the above-mentioned posterior intercostal vessels, and the anterior chest wall branches of the axillary artery (Figs. 182, 183). At the level of the sixth ribs, the right and left internal mammary arteries bifurcate into their respective superior epigastric and musculophrenic arteries. The latter follows the costal margin, giving off anterior intercostal branches and small branches to the edge of the diaphragm. The superior epigastric branch of the internal mammary is easily remembered because of the frequency with which it is encountered in upper rectus abdominis incisions (Fig. 183). The inferior epigastric artery and vein, (Fig. 183), which arise from the external iliac artery and vein just above Poupart's ligament and medial to the internal inguinal ring, form a very important anastomosis with the superior epigastric artery and vein. As mentioned above, the superior epigastric arteries arise from their respective internal mammary arteries, which, in turn, arise from the right and left subclavian arteries, thereby making this arterial anastomosis very helpful in supplying blood to the lower extremity in coarctation of the aorta. It is well to remember that the anastomosis between the superior and inferior epigastric veins is also important (Fig. 183). The superior epigastric veins empty into the right and left internal mammary veins, and they, in turn, empty into their respective innominate veins, which unite to form the superior vena cava, going to the right atrium of the heart (Fig. 183). The inferior epigastric veins go to their respective

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Ernest W. Lampe


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19 20 21 22 23 24 8 9 10

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Fig. 183.

SCHEMATIC VIEW OF COLLATERAL VENOUS CIRCULATION IN OBSTRUCTION OF SUPERIOR VENA CAVA

1. Superior sagittal sinus. 2. Inferior sagittal sinus. 3. Straight sinus. 4. Right transverse sinus-eventually forms right internal jugular vein. 5. Vertebral vein. 6. Lateral thoracic vein. 7. Thoracodorsal vein. 8. Posterior intraspinal veins. 9. Anterior intraspinal veins. Note that the intraspinal veins extend the length of the spinal canal; and communicate with extraspinal vessels in the cervical region, intercostal vessels in thoracic region, lumbar vessels in lumbar region and lateral sacral branches of internal iliacs in the pelvis. 10. Right ascending

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external iliac veins. Note how helpful this anastomosis is in returning blood to the heart in a case of obstruction or ligation of the inferior vena cava. To review: Note that the anterior thoraco-abdominal wall has two important vertical anastomoses, which connect blood vessels going to or coming from the lower extremity with those going to or coming from the upper extremity and head and neck (Fig. 183). The superficial anastomosis or thoraco-abdominal anastomosis (located in the superficial fascia), is between the superficial epigastric branches of the femoral vessels and the lateral thoracic branches of the axillary vessels (Fig. 183). The other, the deep anastomosis, is deep to the ribs and muscles, and directly or indirectly connects the subclavian vessels with the external iliac vessels (Fig. 183). The external iliac vessels pass under Poupart's ligament to become the feI~oral vessels. The subclavian arteries give off not only the previously described internal mammary branches, but the vertebral arteries which ascend the neck to pass through the foramen magnum to form the basilar artery, whose branches unite with the internal carotids to form the circle of WilUs, supplying the brain. The well-known thyrocervical artery and the costocervical arteries are the other branches of the subclavian artery. In an upper or lower rectus incision, rough handling of the posterior aspect of the rectus abdominis muscle frequently causes annoying bleeding from the superior or inferior epigastric vessels (Figs. 175, 183). Besides causing the surgeon to mutter into his mask, it should remind lumliar vein connects the right four lumbar veins and passes through the diaphragm to become the azygos vein. On the opposite side is the left ascending lumbar vein which passes through the diaphragm as the hemiazygos vein. 11. Lumbar veins. Note how blood in them can go either directly to the inferior vena cava or via the azygos vein to the superior vena cava. 12. Anterior extraspinal veins. 13. Inferior vena cava. 14. Vein from basilar plexus at base of brain stem. 15. Venous plexus about foramen magnum. Note occipital sinus draining into it. 16. Anterior intraspinal veins (dotted)-help to drain basilar plexus and plexus about foramen magnum. 17. Posterior intraspinal veins-help to drain occipital sinus and plexus about foramen magnum. * Left superior intercostal vein drains left first and second intercostals into the left innominate vein. All remaining left and right posterior intercostal veins eventually drain into the azygos vein which goes to the superior vena cava. 18. Azygos vein. Note all right posterior intercostals draining directly into azygos vein; and all but two left posterior intercostals draining into azygos vein via hemiazygos and accessory hemiazygos veins. In this figure, arrows show reversal of flow due to obstruction of superior vena cava. Note schematic connection of azygos with the intraspinal veins draining brain when superior vena cava is blocked. ** Accessory hemiazygos vein. 19. Hemiazygos vein. Note lower left posterior intercostals and accessory hemiazygos draining into it. 20. Superior epigastric vessels. Observe anastomosis with inferior epigastrics (26).21. Skin. 22. Superficial fascia. 23. Deep fascia. 24. External and internal oblique and transversus abdominis muscles. Transversalis fascia, extraperitoneal fat and peritoneum are deep to these muscles. 25. Schematic. view of the superficial anterior vertical anastomosis (thoraco-epigastric anastomosis). Lateral thoracic branch of axillary vein communicates with superficial epigastric branch of femoral vein. 26. Deep anterior vertical anastomosis. Superior epigastric from internal mammary and innominate communicates with inferior epigastric from external iliac. tttLateral sacral veins connecting lower end of intraspinal veins to internal iliac vein.

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Ernest W. Lampe

him that the vessels are parts of the very important deep vertical anastomosis. The surgeon's superficial regard for the superficial epigastric vessels in the middle of an inguinal hernia incision should remind him of the superficial vertical anastomosis; just as, on repairing the sac, his deep respect for the deep or inferior epigastrics can remind him of the deep vertical anastomosis. Because they are a part of the collateral circulation between the abdominal (really pelvic) wall and lower extremity, the obturator vessels should be mentioned. They arise from the internal iliac artery and vein, and pass forward through the obturator foramen to reach the upper anteromedial aspect of the thigh, where they anastomose with the medial circumflex branch of the profunda femoris artery. One should remember that an anomalous obturator artery arises from the external iliac, and passes medially and downward so close to the femoral canal that it is easily injured in dealing with a femoral hernia (Fig. 179). In an earlier paragraph, it was mentioned that one of the reasons for considering the posterior abdominal wall in this article was the relation of some of its blood vessels to vessels elsewhere in the trunk, head and neck. Figure 183 shows how each pair of lumbar veins communicates with the intra- and extraspinal veins. Recall that, superiorly, the anterior and posterior intraspinal veins, at the foramen magnum, connect respectively with the basilar venous plexus and occipital sinus, which, in turn, communicate with other large intracranial sinuses receiving venous blood from the cerebral hemispheres, brain stem and cerebellum (Fig. 183). As these same intraspinal veins extend the length of the spinal canal, they communicate not only with the anterior and posterior extraspinal veins (Fig. 183), but in the cervical region with the deep cervical and vertebral veins emptying into the subclavian and innominate veins. In the thoracic region, they communicate with the posterior intercostal veins draining into the azygos-hemiazygos system (Figs. 179, 183). In the lumbar region (posterior abdominal wall), the intraspinal veins connect with the lumbar veins, which drain into both the inferior vena cava and the azygos-hemiazygos system (Figs. 179, 183). Observe that the azygos-hemiazygos veins actually connect the inferior vena cava with the superior vena cava, (Fig. 183). Finally, in the sacral region, the intraspinal veins communicate with the lateral sacral veins, going to the internal iIiacs, and the middle sacral vein, going to the left common iliac or inferior vena cava, Figure 183. Despite the fact that most of the azygos-hemiazygos system is in the thoracic cavity, its origin, in the posterior part of the abdominal cavity, makes it worthy of review (Figs. 179, 183). Usually, the four right lumbar veins are connected with each other by the ascending lumbar vein, which then passefl as the azygos vein through the aortic orifice of the diaphragm with the aorta and thoracic duct. Somewhat to the right of the midline, the azygos vein extends upwards on the anterior aspects of the lower eight thoracic vertebra, finally, to arch over the right primary bronchus and empty into the superior vena cava (Fig. 183). The left ascending lumbar vein (Figs. 179, 183), connecting the four left lumbar veins, passes through the left crus of the diaphragm as the

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hemiazygos vein. The lower four or five left posterior intercostal veins

empty into the hemiazygos vein as it runs along the left anterolateral aspects of the lower four thoracic vertebrae, finally crossing in front of the eighth thoracic vertebra to empty into the azygos vein (Figs. 179,183). Continuing upward on the left posterior chest wall, note (Fig. 183), that the next four or five left posterior intercostal veins pour their blood into the accessory hemiazygos vein, which descends to the eighth thoracic vertebra, where it may empty into the hemiazygos vein or directly into the azygos vein. The left first and second posterior intercostal veins unite to form the left superior intercostal vein, which flows into the left innominate vein. To summarize the azygos-hemiazygos system: The four right and left lumbar veins on the posterior abdominal wall not only empty into the inferior vena cava, but the four on the right side are connected with each other by the right ascending lumbar vein, which passes through the diaphragm as the azygos vein, draining the right posterior chest wall into the superior vena cava (Fig. 183). The four lumbar veins on the left side are connected by the left ascending lumbar vein, which becomes the hemizazygos vein. This, with the accessory hemiazygos, drains most of the blood of left posterior chest wall into the azygos vein. The left first and second posterior intercostals empty into the left innominate vein. The azygos vein then drains practically all of both posterior chest walls; assists in draining the posterior abdominal wall; and forms a very important venous anastomosis between the inferior and superior vE;)nae cavae. In addition, the azygos vein receives branches from the lower end of the esophagus, wherein lies the esophageal venous plexes, which, via its branches to the coronary vein, also communicates with the portal circulation. Figures 182 and 183 show schematically how the axillary vein not only receives the venous blood of the upper extremity, but forms a very competent anastomosis with the intercostal vessels via its supreme intercostal, thoraco-acromial, lateral thoracic and thoracodorsal branches. The lateral thoracic vein has already been described as also forming the upper part of the thoraco-abdominal or superficial anastomosis between the axillary and femoral veins. Note the value of this collate~al circulation in obstruction of the superior vena cava. Those who have ever seen a case of severely obstructed super£or vena, whatever the cause, can never forget the tremendous, edematous swelling of the face, neck, upper extremities and chest wall. When one considers that almost all the venous drainage from these parts normally drains ultimately into the superior vena cava, it is not at all surprising to find the above-mentioned condition in the presence of severe obstruction. In fact, were it not for the various collateral venous routes described in previous paragraphs, patients would not survive as long as they do. Now one can see how the anterior and posterior £ntraspinal veins form a very important venous outlet for the brain when there is obstruction of the superior vena cava.

Ernest W. Lampe

574 SUMMARY

The reader will note that I have attempted to review the surgical anatomy of the abdominal wall from two points of view: First, a resume of the seven layers of the abdominal wall as the surgeon thinks of them in making his incisions; second, a review of the transverse and vertical vascular patterns as they apply to the local circulation and to that of the head, neck and upper extremity, and the lower extremity. Obviously, more illustrations would have been helpful, but, despite this and the brevity of the review, I hope that enough basic groundwork has been covered to serve as a framework to which details can be added by referring to any standard textbook of anatomy. Dr. Ismail Djavid, assistant resident surgeon on the Cornell Surgical Division of Bellevue Hospital, drew the illustrations for the text. The writer regrets that lack of space prevents the use of more of his fine drawings.