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HISTORY

The anatomic and surgical history of the abdominal wall is shown in Table 9-1.

Table 9-1. Anatomic and Surgical History of the Abdominal Wall and Hernias

Ebers Papyrus ca.

1552

B.C.

Earliest recorded reference to he rnias: "When you judge a swelling on the surface of a belly. . . what comes out. . . [is] caused by coughing"

Herophilus of

Chalcedon (ca.

300 B.C.)

"The founder of anatomy." Ligated vesse ls for hemostas is.

Erasistratus of

Keos (ca. 330-

250 B.C.)

"The father of physiology." Performed hernia operations in Alexandria, Egypt.

Celsus (?-50

A.D.)

Author of De Medicina.Wrote detailed descriptions of hernia ope rations, and believed in prese rving testicle during surgery. First to us e term

'hydrocele,' as "a fluid (humour) which collects either between the scrotal tunica (vaginal hydrocele) or between the membranes wh ich cover

the arteries and veins (hydrocele of the cord)."

Heliodorus (fl.98-117) Physician and surgeon during the Greco-Roman period. May have been the first to perform a celiotomy.

Galen (129-

199)

Most prominent physician of Greco-Roman period. Introduced concept of hernia caused by rupture of peritoneum and abdominal wall. Advise

ligature of sac and cord w ith orchiectomy. First to define processus vag inalis, "a duct descending to the testicle as a small offshoot o f the

great peritoneal sac in the lower abdomen." First to recommend use of a seton for hydrocele drainage.

Paul of Aegina

(625-690)

Provided meticulous and accurate description of hernia surgery. For the treatment of hydrocele, he advocated cutting through scrotal wall

with a knife, destroying tunica vaginalis by cautery, and partial suturing of edges.

Albucasis

(936-1013)

Great Moorish surgeon and writer whose On Surgery and Instrumentscontains original surgical procedures using instruments of his own

design. The purpose of this book was to "revive the art of surgery as taught by the 'Ancients.'" Used seton and cautery for hydrocele repair.

Avicenna (980-

1037)

Used cautery to drain hydrocele fluid

William of

Salicet (1210-

1277)

Innovator in surgery. First author after Celsus to propose redescent of testicle (rather than mutilation) during hernia operation: "And if you

were to be assured of this manner of opening, then permit the testicle to redescend to its place, and do not dream in any fashion of

extirpating it, as do some stupid and ignorant doctors who know nothing..."

Incised hydrocele with lancet and drained fluid through cannula.

Borgognoni ofLucca (d.

1252)

Proposed incising the hydrocele sac, plugging the cavity with "a lint," and treating the wound with arsenic powder

Guy de

Chauliac

1363 Provided a more complete classification of hernias

Marcel

Cumanus (d.

1423)

Recommended orchiectomy for treatment of hydrocele

Par (1510-

1590)

Advocated ligature of vesse ls and ligation of cord (often with a gold thread, as originated by Gualdus of Metz), and trusses for control of

hernias. Advised seton for hydrocele treatment.

Fallopius

(1523-1562)

Rejected surgical operation for repair of hydrocele. Suggested topical application of desiccating plaster for treatment.

Franco 1556 Described open method of surgery, which included cutting between strangulated hernia and external ring. In Trait des Hernies,Franco

advised against cutting spermatic cord or removing testicle.

Stromayr 1559 Practica Copiosadescribed first distinction betwe en direct and indirect hernias. Advised orchiectomy only in cases of indirect herniation.

Lusitanus 1571 Supported acupuncture method of hydrocele repair; sac punctured with many needles, permitting fluid to diffuse into scrotal tissues

Hildanus 1610 Sutured sac, ligated co rd and sac

Cheselden

(1688-1752)

Believed hydrocele to be a systemic disease originating in abdomen and extending to scrotum

Heister 1724 Successfully resected bowel of patient with strangulated hernia

Ruysch 1729 Stated that dila ted spermatic vessels were cause of hydroce le

Richter 1778-

1779

Described partial strangulation of intestinal wall within hernial sac

Morgagni 1761 Attributed hydrocele to rupture of hydatid cysts

Gimbernat 1793 Recommended division of lacunar ligament (which now bears his name) in cases of strangulated femoral hernia

Camper 1801 Described upper layer of superficial fascia of lower anterior abdominal wall and inguinal canal

Cooper 1804 Discovered bilaminar formation of transversalis fascia, transversus aponeurosis, and ligament that bears his name

Hesselbach 1806, Described trian le and li ament that now bear his name


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1814

Monteggia 1816 Accurately described types and causes of hydrocele

Scarpa (1752-

1832)

Accurately described sliding hernia and deep layer of superficial fascia of lower abdominal wall and inguinal ligament

Wood 1863 Introduced subcutaneous ligature o f sac fo r hernia repa ir

Demarquay 1863 Found microfilariae in hydrocele fluid

Bancroft 1876 Found live worms in hydrocele of spermatic cord

Annandale 1876 Often inaccurately attributed as being first to use Cooper's ligament in hernia repair. May have been first to introduce concept of

preperitoneal approach.

Marcy 1878 First to stress importance of high ligation of hernial sac and closure of dilated inguinal ring in repair of inguinal hernias. First to describe

transabdominal approach.Warren 1884 Proposed concept o f inje ction treatment

MacEwen 1886 Folded up peritoneal sac and fixed it around internal ring to act as a cork

Bassini 1887-

1890

Developed hernia repair ope ration which is basis o f modern herniorrhaphy. Bassini repair consists of high ligation and res ection of sac.

Internal oblique and transversus abdominis muscles and transversalis fascia are sutured to ligament of Poupart. According to Bassini, his

technique was designed to "restore those conditions in the area of the hernial orifice which exist under normal circumstances."

Halsted 1889,

1903

Performed herniorrhaphy by placing spe rmatic cord above external oblique aponeuros is (Halsted I). Placed cord deep under repair (Halsted

II). First to report relaxing incision ove r aponeurosis of rectus muscle.

Lucas-

Championniere

1892 First to perform hernia repair with cord in intermediate position and imbrication between layers of external oblique aponeurosis

Socin 1893 Revived sac ligation and excision procedure after Lister introduced antisepsis, making possible operation on hernias other than those

immediately threatening life

Andrews 1895 Incorporated cord into imbrication of external oblique aponeurosis

von Mikulicz 1896 Used extrapleural osteochondral flap approach during resection

Lotheissen 1898 Used Cooper's l igament for repair of inguinal hernia

Ferguson 1899 Sutured internal oblique muscle and aponeurosis over spermatic cord. In 1889, he wrote, "Leave the cord alone for it is the sacred highway

along which travel vital elements indispensable to the perpe tuity of our race."

Horwitz 1901 Treated hydrocele with excision and eversion of tunica vaginalis

Marwedel 1903 Resected stenosis through costal margin release procedure

Sauerbruch 1905 Advocated, but did not employ, two-incision approach (laparotomy and thoracotomy)

Wendel 1909 Employed two-incision technique (esophagostomy and gastrostomy)

Janeway and

Green

1910 First to sugges t one-incision approach. Only employed two-incision technique.

Cheatle 1920-

1921

Described operation using median abdominal section without ente ring peritoneal cavity (preperitoneal approach)

Huggins and

Entz, Rinker

and Allan

1931,

1951

By anatomic study, discovered cause o f hydrocele

He nry 1936 Revita liz ed pre peritone al proce dure

Brock 1942 Firs t success fu l e sophagogastro tomy in Europe

McVay 1942-

1949

Popularized us e of Cooper's ligament for hernia repair by repeatedly publishing articles about it

Shouldice,

Obney, Ryan

1950-

1953

Performed multiple layer repair of posterior inguinal wall under local ane sthes ia (Shouldice technique)

Solomon, Lord 1955,

1964

Developed radical cure of hydrocele by plication of tunica vaginalis without mobilization of hydrocele s ac

Nyhus 1959 Described iliopubic tract repair of direct and femoral hernia by preperitoneal approach. In 1989, Nyhus wrote: "I am convinced that all

recurrent groin hernias must be approached pos teriorly and the fascial repair buttressed by pros thetic material."

Fasana 1973,

1982

Modified radical cure for hydrocele irrespective of size of s ac and involvement of tunica vaginalis

Ger 1982 Described "intraabdominal approach" for repair of abdominal wall hernias. Believed to be first to perform laparoscopic inguinal herniorrhaphy

in a human.Stoppa 1984 Devised procedure for reinforcing peritoneum using large unslit prosthesis

Lichtenstein 1986 Introduced tension-free repair by reconstructing floor of inguinal canal using prosthetic material

Gilbert 1989 Devised technique for sutureless repair of inguinal hernia using prosthesis through internal inguinal ring or for repair of posterior inguinal

wall

Condon 1989 Studied iliopubic tract anatomically and used it for repair

Rutkow 1993 Modified mesh-plug repair

History table compiled by David A. McClusky III and John E. Skandalakis.

References

Bendavid R. Prostheses and Abdominal Wall Hernias. Austin: RG Landes , 1994.

Fasana F. Hydrocele in the Temperate and Tropical Countries. Boca Raton: CRC Press, 1983.

Nyhus LM, Harkins HN (eds). Hernia. Philadelphia: JB Lippincott, 1964.


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Nyhus LM, Condon RE (eds). Hernia (3rd ed). Philadelphia: JB Lippincott, 1989.

Nyhus LM, Condon RE (eds). Hernia (4th ed). Philadelphia: JB Lippincott, 1995.

Robbins AW, Rutkow IM. The mesh-plug he rnioplasty. Surg Clin North Am 1993;73:501-512.

Warren R. Surgery. Philadelphia: WB Saunders, 1963.

EMBRYOGENESIS

Normal Development

During the 6th week of gest ation, mesoderm from the myotomes which lie on either side of the vertebral column invades the somatopleure (primitive wall of

the abdomen). This area is occupied by the body stalk and the open midgut. The mesoderm forms a sheetlike embryologic entity. After migrating laterally

and ventrally, it differentiates to form the right and left rectus muscles. Around the 12th week, they approximate in the midline, closing the body wall.

A majority of embryologists (among them Wolff2and Duhamel3) state that this closure proceeds simultaneously from cranial, caudal, and lateral directions.

However, Klippel4suggested that closure proceeds from the middle to the periphery.

Around the middle of the 7th week, the main body of the mesodermal sheet splits into 3 layers, forming the three flat muscles vent rally and the serratus

muscle group dorsally. Therefore, all abdominal wall muscles can be recognized around the 7th week.

The lower abdominal wall is formed by a mesodermal layer, the so-c alled "secondary mesoderm." It envelops and invades the c loaca, thereby separating

ectoderm from endoderm cranial to the cloaca.

The reader should remember that embryology is a speculative sc ience full of "perhaps," "maybe," and "most likely." The word "necessity" is used in this

chapter for a possible embryologic explanation. Two giants of the past used this word: Aristotle and John Hunter. Hunter wrote about the stimulus of

"necessity" in his writings about collateral circulation.

We present the following overview of the possible embryology of t he inguinofemoral area from Skandalakis et al.5:

The embryologic phenomenon of the formation of spaces above and below the inguinal ligament is the result of two necessary developments.Necessity One, the space above the inguinal ligament, is the well known inguinal canal which is the testicular pathway from the retroperitoneal space

to the scrotum. Necessity Two consists of the spaces below the inguinal ligament which permit the exodus of the muscles, nerves, and vessels which

are destined to provide for the lower extremity. The question is: What is the reason for the formation of the enigmatic femoral canal?...

The embryology of the inguinal canal is pec uliar. In a highly synergistic way, the skin, parietal peritoneum, and embryologic and anatomic ent ities

between them produce the future pathway for the testes. The skin will form the scrotum (scrotal folds) in the male and the labia (labial folds) in the

female. The parietal peritoneum will produce the processus vaginalis. Although present in bot h genders, t his peritoneal diverticulum is more important

to the male fetus because it will permit the descent of the testicles. The embryologic entities between the skin and peritoneum permit the processus

vaginalis to penetrate them and form the inguinal canal. The downward journey of the testicles to the scrotum is thus allowed. Descent of the ovary

outside of the peritoneal cavity, however, is forbidden. The processus vaginalis finally closes to obstruct ovarian exodus but leaves the formation of

the inguinal canal in situ.

Ogilvie6correctly stated that the descent of the testicles into the scrotum made a mess of the three-layered abdominal wall.

Lateral to the pubic tubercle are two openings: one is the fascia of Scarpa and is inferolateral to the pubic tubercle; the other (the superficial ring),

which is within the aponeurosis of the external oblique, is superolateral to the pubic tubercle. The two openings are about 4 cm apart in the adult...

The formation of the scrotum is a result of the fusion of the right and left labioscrotal folds. A scrotal septum separates the scrotum into two halves;

this separation is obvious externally by the raphe between the right and left scrotal halves. In the female the labioscrotal folds form the right and left

labia majora...

The formation of the femoral canal, mysterious and obscure, takes place after the formation of the three flat muscles of the anterior abdominal wall,

the formation of the transversalis fascia and its several thickenings, and the exodus of the several anatomic entities traveling downward from the

retroperitoneal space under the inguinal ligament to reach the lower extremities. Lyt le7is right in reporting that the flat muscles of the anterior

abdominal wall passing in front of the ligament of Cooper provide space for the spermatic cord and the great vessels of the lower extremity.

The embryologic and anatomic entities that produce the femoral canal and some that are merely good neighbors are:

Transversus abdominis aponeurosis

Transversalis fascia and its thickening

Ligament of Cooper (pectineal)

Ligament of Poupart (inguinal)

Ligament of Gimbernat (lacunar)

Femoral vein

Pectineus muscle and fascia

Lymphatics and lymph nodes

It is worth emphasizing Condon's8repeated statements that the inguinal ligament and the lacunar ligament just happen to be close to the femoral

canal they do not have any role in defining the orifice of the normal femoral canal.

Neither the medial end of the inguinal ligament, as it approaches its attachment to the pubic tubercle, nor the lacunar ligament of Gimbernat as it

attaches to the pectineal ligament and fuses with the pectineal fascia helps to close this most medial space under the inguinal ligament, the femoral


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cana . e manner o s orma on s pro uces a o o ques ons u perm s us o now a e en rance o e emora cana s oca e e ween

the posterior inguinal wall and the ligament of Cooper.

How strong embryologically and anatomically is this area of the posterior inguinal wall? Here the thickenings of the transversalis fascia and the

presence of transversus aponeurotic fibers start to play a great role. The femoral sheath is formed embryologically by the evagination of elements of

the abdominal wall by the outgrowth of the femoral vessels. The parietal fascial lining of the abdominal cavity which continues from the transversus

abdominis to the iliopsoas musculature is essentially drawn into the proximal thigh by the primitive vascular elements. It c an be seen that the iliopubic

tract arches over the vessels to insert upon the pectineal ligament, thereby forming the medial extremity of the beginning of the funnel-shaped

femoral sheath. The intermediate portion of the tract, wherewith it is arching over the artery and vein, is carried out upon the femoral vessels,

together with transversalis fascia. This covering blends without interruption with the fascia of the iliopsoas musculature which lies just deep to the

vessels. The innermost lining of the sheath is provided by preperitoneal connective tissue.

Another anatomic entity that should be mentioned is the iliopsoas fascia, which might be considered continuous below with the fascia lata of the

thigh. On its journey toward the thigh, it has interconnections with the transversalis fascia to form septa between the external iliac artery and vein,and between the external iliac vein and the femoral canal. As it continues into the thigh it provides a posterior wall for the femoral sheath. According

to Lytle,7at the medial part of the inguinal ligament the fascia lata's journey is interrupted and it turns backward from the posterior border of the

inguinal ligament to form the lacunar ligament.

The iliopubic tract and the femoral sheath are very closely related to the femoral canal. Embryologically, both belong to the transversalis fascia and

transversus abdominis aponeurosis. However, in fresh cadavers one can observe in the floor of the femoral canal that the pectineal fascia fuses with

the overlying femoral sheath. It is our opinion that both iliopubic tract and femoral sheath are specializations chiefly of the transversus and

transversalis fascia. The fixation of the femoral sheath to the iliopubic tract anteriorly and medially tells us that the sheath is an independent

embryologic and anatomic entity, or perhaps it is just part of the iliopubic tract traveling into the thigh.

There is a variably large opening in the fascia lata, the saphenous hiatus, which permits the great saphenous vein to enter the femoral sheath and,

simultaneously, to join and empty into the femoral vein. It is at t his opening in the fasc ia lata t hat some femoral hernias may protrude into the

superficial fascia of the thigh.

The femoral canal is the small opening between the insertion of the pectineal ligament and transversalis fascia onto the iliopubic tract and the

external iliac vein. This elliptical opening is typically occupied by lymphatic tissue, fat, and a small vessel or two - unless an aberrant obturator artery

or aberrant obturator vein also happens to cross the opening from its origin at the inferior epigastric artery and/or vein. With careful dissection, one

can open the femoral canal throughout its passage beneath the inguinal ligament and see the convergence and passage of fat-covered lymphatic

vessels through the wall of the canal and its delicate inner lining. What is the purpose of the femoral canal? It has two important roles: to permit the

passage of the efferent lymph vessels f rom the deep inguinal lymph nodes to the abdomen, and to permit expansion of the femoral vein when the

venous pressure of the lower extremity is elevated.9As we emphasize later this expansion does not prevent femoral herniation.

The embryologic question is: Are the posterior and lateral walls of the femoral sheath formed from the pectineal and psoas fasciae and from the iliacus

fasc ia (laterally)? Our observations lead us to believe so. We will not muddy the wat er more; let's all remember simply that the femoral sheath is a

prolongation of the transversalis fascia into the thigh, possibly originating mostly from the iliopubic tract and from the transversalis fascia, or it may

be an independent formation.

McVay10stated that the defect in a femoral hernia is a narrowing of the insertion of the transversus abdominis aponeurosis onto Cooper's ligament.

Mc Vay11also said, "A femoral hernia is never c ongenital in origin in that t here is never a preformed peritoneal sac, as with indirect inguinal hernia."

The chief argument against the congenital origin of femoral hernia has been its rarity in infants and children. We have been able to find only three

reports of femoral hernia in fetuses.12,13,14All three fetuses were between two and three months of age. We have not seen any similar reports in the

recent literature.

Monro15stated also that "a femoral hernia is never congenital" and hypothesized that "a congenital anomaly, consisting of a narrow insertion of the

iliopubic tract into the pectineal line of the pubis and causing a broad 'femoral dimple'" is an etiologic factor. Perhaps. Still embryologic, anatomic, and

etiologic factors overall are full of Delphian and Byzantine ambiguities. The question of whether femoral hernia can have a congenital origin is not easy

to answer. Several reports of femoral hernia in newborns have appeared in the literature, with their authors endorsing a congenital origin.

Weakness of struct ures around the femoral canal is not easily demonstrated in infants. Zimmerman and Anson16have observed that the relative

weakening of this region begins at the age of twenty.

Various explanations have been put forward for the developmental formation of a femoral hernial sac .

1. Adherence of the developing femoral artery to the peritoneum pulls the latter into the femoral canal forming a peritoneal sac.

2. Abnormal attachment of the testicular gubernaculum exerts a pull on the abdominal wall to form a peritoneal dimple, the precursor of a hernial sac.

3. Traction upon the peritoneum results from the adhesion of adipose tissue in the femoral canal with peritoneal fat in this region.

However attractive these theories, they remain possibilities without observational confirmation. Although empty femoral hernial sacs are known in

adults, Tasche17examined 64 newborns without finding one. While his sample was t oo small in view of the inc idence of femoral hernia, the fac t

remains that a congenital predisposing defect has yet to be demonstrated. However, Mitchell18reported a small peritoneal femoral diverticulum.

That there is no proof of a developmental defect must not make us overlook the fact that femoral hernias do occur in children and that they can

become strangulated. It should be noted that in at least one case 19the hernia was diagnosed as inguinal and the scrotum was entered before the

true condition was realized.

The femoral canal remains predominantly open (Last9called this the "dead space"), but it is partially filled with some fat and lymphatics and has in its

exit the Cloquet or Rosenmller lymph node. All the preceding structures together form the crural septum - which of course will not stop the formation

of femoral herniation.


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Wilson20stated that the conclusion of Hahn-Pedersen et al.21that femoral herniation is prevented by periodic venous dilatation of the femoral vein

and occlusion of the canal is not sound; we agree.

Congenital Anomalies

Anomalies of the anterior body wall are listed in Table 9-2.

Table 9-2. Anomalies of the Anterior Body Wall

Anomaly Prenatal Age at

Onset

First

Appearance

Sex Chiefly

Affected

Relative

Frequency

Remarks

Deformities of the thorax Late in fetal life At birth or in

infancy

Male Common Familial tendency

Unilateral thoracic wall aplasia Weeks 6-7 At birth Male Very rare

Sternal defects:

Simple defects Week 7 At any age Male Rare

Ectopia cordis Week 3 At birth Male Rare Few affected persons reach maturity; common in

nonviable monsters

Amastia Week 6 At birth Female Very rare Familial tendency

Polymastia Week 6 At any age Equal? Common Familial tendency

Umbilical hernia Week 10 At birth Equal Common Usually disappears spontaneously

Omphalocele Week 10 At birth Equal Uncommon Failure of normal intestinal return

Gastroschisis Weeks 6-7 At birth Male Uncommon Herniation through defect in abdominal wall

Incomple te clo sure of the pro ces sus va gina lis Around birth In infa ncy Ma le Common Results in inguina l he rnia o r hydro ce le

Epispadias Week 4 At birth Male Uncommon

Exstrophy of the bladder Week 6 At birth Male Uncommon Untreated patients die eventually from

pyelonephritis

Exstrophy of the cloaca Week 5 At birth Equal Very rare All should be reared as females

Absence of abdominal musculature with

urinary tract defects

Week 7 In infancy Male Rare

Aplasia of abdominal musculature without

urinary tract defects

Week 7 In infancy Male? Very rare

Source:Skandalakis JE, Gray SW (Eds). Embryology for Surgeons , 2nd Ed. Baltimore: Williams & Wilkins, 1994, p. 546; w ith permission.

Kluth and Lambrecht22present a summary of current theories of normal and abnormal embryologic development of the anterior abdominal wall. Nielsen et

al.23studied the effects of antenatal diagnosis of abdominal wall defects on the route of delivery and surgical outcome. While it is not within the scope of

this chapter to discuss these important issues, we advise the interested student to read these two presentations.

Congenital and acquired umbilical hernias are discussed later in this chapter under "Hernias of the Anterior Abdominal Wall."

SURGICAL ANATOMY

Anterior Abdominal Wall

The terminology "aponeurosis" and "fascia" can be confusing because both entities can present as sheets of connective tissue. An aponeurosis is dense,

regular, collagenous connective tissue that joins a muscle to its origin or insertion. Perhaps stated more clearly, an aponeurosis is a flattened tendon. This i

in contrast to the nature of the majority of tendons in the body, which are more cordlike in appearance.

Around each muscle the epimysium a connective tissue sheath or fascia that ranges from diffuse to dense continues over both surfaces of the

aponeurosis as the epitendineum. It may or may not be thick enough to be easily demonstrable on gross inspection. It does not have the strength of an

aponeurosis. A fascial sheet may become aponeurotic secondarily, providing for part of the origin or insertion of a muscle. In practice, the fascia covering a

particular muscle is usually named by the name of the muscle, such as psoas fascia.

The anterior abdominal wall can be considered to have two parts: anterolateral and middle (or midline). The anterolateral portion is composed of the externa

oblique, t he internal oblique, and the transversus abdominis muscles. T he middle portion is c omposed of the rectus abdominis and pyramidal muscles (Table

9-3).

Table 9-3. Muscles of the Abdominal Wall

Name Origin Insertion Action Nerve Observations

External

oblique

Inferior border of

lower 8 ribs

Aponeurosis to linea alba from xiphoid to

symphysis, iliac crest, a nterior superior iliac

spine

Compresses

abdomen

Lower 6 thoracic

spinal nerves

Flexes and

laterally rotate s

spine

Depresses ribs

Internal

oblique

Iliac fascia Lower border of ribs 9-12 Same as above Lower 6 thoracic

spinal nerves

Related to lateral of inguinal ligament

(approx.), but does not arise from

ligament


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nter or ac crest t aponeuros s to nea a a st um ar sp na

nerve

Lumbar

aponeurosis

Pecten pubis

Transversus

abdominis

Iliac crest Through aponeurosis to linea alba Compresses

abdomen

Same as above Related to lateral of inguinal ligament

but does not arise from ligament

Lumbodorsal fascia Pecten pubis Depresses ribs

Cartilages of lower

ribs

Rectus

abdominis

Crest of pubis and

pubic symphysis

Cartilages of ribs 5-7 Compresses

abdomen

Intercostals 6-12

Xiphoid process Lifts chestFlexes spine

Quadratus

lumborum

Iliolumbar ligament 12th rib Fixes last rib T12

Posterior iliac crest Tips of t ransverse processes of L1-4 Flexes spine at

the same side

L1-L3

Psoas

major

Transversus

processes of L1-5

Lesser trochanter of femur Flexes thigh and

rotates it laterally

L1-3

Sides of bodies and

fibrocartilages T12-

L5

Flexes spine and

bends spine

laterally

Iliacus Upper of iliac

fossa

Tendon of psoas major to lesser trochanter Flexes and laterally

rotates thigh

Femoral (L2-3)

Inner lip of iliac

crest

Anterior sacroiliacligament

Base of sacrum

Pyramidal Pubis and anterior

pubic ligament

Linea alba Tenses linea alba T12

Cremaster Internal oblique

muscle

Tubercle and crest of pubis Draws up testis Genital branch of

genitofemoral

nerve

Transversus

abdominis

aponeurosis

Modified from Pansky B, House EL. Review of Gross Anatomy: A Dynamic Approach. New York: Macmillan, 1964, p. 272; with permission.

Remember the dic tum of McVay and Anson:24,25There are no muscles that originate f rom or insert into the inguinal ligament. We agree. However, Gray's

Anatomy(38th ed.)26states that there is some disagreement as to whether the fibers of the transversus abdominis arise directly from the inguinal ligament(that is, from the lower edge of the aponeurosis of the external oblique) or from the adjacent iliac fascia.

Anterolateral Portion

The external and internal oblique muscles (Fig. 9-1) and the t ransversus abdominis muscle are arranged so t hat their fibers are roughly parallel as they

approach their insertion on the rectus sheath. A muscle-splitting incision here will not encounter widely-differing directions of muscle fibers. More laterally,

toward the flank, the fibers of the different muscles are more divergent. The choice between muscle splitting and some muscle transection is often

encountered during urological exposure through flank incisions.

Fig. 9-1.


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Transversus abdominis muscle and aponeurosis; external and internal oblique muscles and their aponeuroses have been removed. (Modified from Skandalakis JE,

Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Originally, it was thought that the aponeuroses of the three flat muscles of the anterior abdominal wall were composed of one lamina only, and that each of

the laminae unilaterally proceeded to contribute to the anterior and posterior laminae of the rectus sheath. However, our knowledge of the aponeurotic

structural wall is more complete because of the work of Askar27and Rizk28(Fig. 9-2). In several publications, both authors reported independent findings

that radically changed the traditional view of the formation of the anterior and posterior laminae of the rectus sheath and that of the linea

alba.27,28,29,30,31

Fig. 9-2.

Aand B.Transverse sections through anterior abdominal wall, traditional view: A,immediately above umbilicus. B,below arcuate line. C-E,Schematic transverse


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sect ons t roug ventra a omna wa , s owng amnar aponeuroses, exte rna o que , nte rna o que , transve rsus a omns , an s te s o nea r e cussat on

that compacted from linea alba. (Modified from Williams PL (ed). Gray's Anatomy (37th ed). New York: Churchill Livingstone, 1989; with pe rmission.)

EXTERNAL OBLIQUE MUSCLE

The external oblique muscle arises from the lower eight ribs, with the lowest attachment to the tip of the 12th rib. There, the fibers from the 11th and 12th

ribs pass nearly vertically to insert upon the anterior half of the outer margin of the iliac crest, thereby forming the free posterior border of the muscle.

Above, t he slips of origin from the upper ribs interdigitate with fibers originating in the pec toralis major and the serratus anterior muscles. The external

oblique musculature is oriented so that the majority of its fibers pass inferiorly and medially, like "hands in the f ront pockets." The muscle bec omes

aponeurotic a long a line that passes vertically downward f rom the 9th costal c artilage, forming the linea semilunaris. Below the anterior superior iliac spine,

the external oblique muscle is wholly aponeurotic.

External Oblique Fascia (Innominate Fascia of Gallaudet)

The external oblique fasc ia is a thin, tissuelike membrane covering the external oblique muscle and aponeurosis. At the superficial ring, it forms the

intercrural fibers between the crura. On its way down to the scrotum, following the spermatic cord, the innominate fascia of Gallaudet forms the external

spermatic fascia. Remember: the external oblique aponeurosis does not usually extend down toward the scrotum as a covering of the spermatic cord.

External Oblique Aponeurosis

According to Rizk,28the aponeurosis of the external oblique (Fig. 9-3) is formed by two layers: superficial and deep. These, together with the bilaminar

aponeuroses of the internal oblique and transversus abdominis, form (by linear decussation) both the rec tus sheath and, finally, the linea alba. If Rizk is

correct, the following is true: The anterior lamina of the rectus sheath at the lower abdominal wall could be formed, theoretically, by six aponeurotic layers

(two from each flat muscle) fused together. The posterior lamina does not exist as a substantial structure, usually consisting of nearly transparent

aponeurotic bands and transversalis fascia.

Fig. 9-3.

External oblique muscle and apone urosis (skin and layers of superficial fascia removed). (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical

Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

The "touchdown" (insertion, fusion) point of the bilaminar external oblique aponeurosis to the anterior lamina of the rectus sheath (Fig. 9-4) is never at the

linea alba or the lateral border of the rectus sheath. Instead, it is always somewhere between the linea alba and the lateral border. The aponeurosis of the

external oblique muscle tends to remain separate from those of the internal oblique and transversus abdominis. It thus contributes little to the actual

structure of the anterior lamina of the rectus sheath, acting only to cover it superficially.32

Fig. 9-4.

"Touchdown point" (triangle)of external oblique aponeurosis is always between linea alba and semilunar line, as shown here in diagram of relaxing incision. X,

Point o f relaxing incision a t ante rior lamina of rectus shea th. (Modified from Skandalakis JE, Colborn GL, Gray SW, Skandalakis LJ, Pemberton LB. The surgical

anatom of the in uinal area Part 1. Contem Sur 1991 38:20-34 with ermission.


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The inferior edge of the external oblique aponeurosis is convex. This is due to the following factors:

The attachment of the aponeurosis inferior to the iliacus fascia

The internal pressure of viscera pressing outward upon the aponeurosis and creating the convexity

The convexity is most apparent laterally. This convexity is less apparent medially where the aponeurosis arches over the exiting femoral artery and vein to

reach t he pubic tubercle. This aponeurosis also forms the lacunar ligament (of Gimbernat) and t he reflected inguinal ligament.

The lower border of the external oblique aponeurosis, suspended between the anterior superior iliac spine and the pubic tubercle, is termed the inguinal

ligament. The c lassic point of view holds that the inguinal ligament is, therefore, s imply the inferior edge of the external oblique aponeurosis.

The superficial inguinal "ring" is the t riangular opening of the external oblique aponeurosis 1 to 1.5 cm above and lateral to the pubic tubercle. This opening

formed by the splitting of the external oblique aponeurosis. The opening allows passage of the spermatic cord or round ligament and makes the crura of the

subcutaneous ring.

The inferior crus (lateral crus) inserts into the tubercle and pubic pecten. The superior crus (medial crus) inserts into the anterior surface of the tubercle,

pubic bone, and symphysis. The insertion of the inferior crus is, in part, by way of the lacunar ligament. Fibers from the superior crus cross the midline to

insert on the opposite tubercle.

There are t hree important facts to remember regarding the external oblique aponeurosis.

In the inguinal area, there are three regional modifications of the externa l oblique aponeurosis: the inguinal ligament, the lacunar ligament, and the reflected

inguinal ligament.

Only fascial attachments (no muscles) enter o r originate in the inguinal ligament.

Cooper's ligament is poss ibly, and only possibly, a lateral continuation of the lacunar ligament of Gimbernat. If this state ment is correct, then the ligament of

Cooper belongs to the anterior lamina of the abdominal wall. To be more specific, the ligament of Cooper, along with the ligament of Gimbernat, is the product o f thaponeurosis of the external oblique muscle. We realize that this assumption would destroy the well accepted classification of anterior and posterior laminae. What i

Cooper's ligament? In all honesty, we do not know. Both ligaments Cooper's and Gimbernat's are good neighbors. It may be that the point of their union is

indeed the meeting point of the anterior and posterior laminae. On the other hand, Cooper's ligament may represent the tendinous origin of the pectineal ligament

which, secondarily, provides a significant site of insertion for the abdominal wall musculature inferomedially.

The inguinal ligament, lacunar ligament (Gimbernat's), and ligament of Cooper are considered later in this chapter under "Inguinofemoral Area."

INTERNAL OBLIQUE MUSCLE

The internal oblique muscle (Fig. 9-5) arises in part from the thoracolumbar fascia and the iliac crest. These fibers insert upon the inferior borders of the

lower three or four ribs. The uppermost bundle of these muscle bundles is essentially continuous with the internal intercostal muscle layer. Fibers arising fro

the anterior two-thirds of the iliac crest pass upward and medially (like "hands in the back pockets"). The lower fibers of origin, arising from iliopsoas fascia,

pass nearly horizontally, or curve medially and downward. The lowest fibers arch over the spermatic cord or round ligament, forming its cremasteric layer.

Fig. 9-5.

Internal oblique muscle and its arch (external ob lique apone urosis removed, spe rmatic cord not retracted). (Modified from Skandalakis JE, Gray SW, Rowe JS Jr.

-


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http://web.uni-plovdiv.bg/stu1104541018/docs/res/skandalakis'%20surgical%20anatomy%20-%202004/Chapter%2009_%20Abdominal%20Wall%20and%20H 10/

na omca omp ca ons n enera urge ry. e w o r : c raw - , ; w pe rmsson.

There is c ontinuing disagreement over the relationship of the internal oblique muscle to other entities in the inguinal region. McVay11regarded the origin of

the muscle to be the iliopsoas muscle fascia. We have observed this condition in fresh, slender cadavers. This arrangement can be seen when the internal

oblique muscle is easily separated from the inguinal ligament with a knife handle. According to McVay,24,25as mentioned earlier, there are no muscles that

start from or insert into the inguinal ligament; there are only fascial attachments.

The medial termination of the internal oblique muscle is also subject to debate. Many surgeons and anatomists concur regarding its participation in the

anterior rectus lamina. However, there is disagreement within both groups about the formation of the conjoined tendon. This topic will be covered later.

The fibers of the internal oblique muscle do not add substantially to the lower portion of the posterior inguinal wall, because they do not have a broad

insertion into Cooper's ligament.33The internal oblique aponeurosis is formed by two layers, anterior and posterior. These layers are fused and, together

with the two other bilaminar aponeuroses, contribute primarily to the anterior rectus sheath lamina. They decussate at the linea alba, there becomingcontinuous with the contralateral aponeuroses.

TRANSVERSUS ABDOMINIS MUSCLE

The transversus abdominis muscle, the deepest of the three flat anterior abdominal muscles, arises from four locations:

Inner surface of the lowe r six costal cartilages

Thoracolumbar fascia

Iliac crest

Fascia of the iliopsoas

The uppermost fibers of the t ransversus abdominis muscle interdigitate with t hose of the respiratory diaphragm. From various sites of origin, the transversus

fibers pass medially. The uppermost fibers become aponeurotic rather near the midline and, thus, posterior to the rectus abdominis. At the level of theumbilicus, the aponeurotic fibers begin somewhat lateral to the rectus. The lower fibers remain muscular almost to the lateral border of the superficial

inguinal ring.

In most cases, the arching lower border of the transversus musculature occurs at a level slightly above the deep inguinal ring and, therefore, does not

contribute to the muscular covering of the spermatic cord. In some cases, however, the transversus may contribute substantially to the cremasteric muscle

covering of the cord.

By their aponeurotic nature, the lower fibers of origin of the transversus abdominis contribute to the formation of the iliopubic tract. This

musculoaponeurotic band is given additional substance by the transversalis fascia. As seen laparoscopically, the iliopubic tract also appears to receive a

significant contribution from extraperitoneal connective tissue. This connective tissue seemingly enhances the bright reflectivity of the tract under

laparoscopic illumination.

The iliopubic tract usually becomes distinct several centimeters medial to the anterior superior iliac spine. Near its beginning, the fibers of the tract appear

to diverge f rom one another. This c learly muscular band of fibers arches medially, pass ing above the deep inguinal ring. Other fibers, aponeurotic in nature,

arise from the iliopsoas fascia and, as the iliopubic tract, pass deep to the deep inguinal ring. They insert upon the pectineal ligament of Cooper, forming the

medial border of the femoral ring.

It should be noted that a relatively thin part of the aponeurotic band may pass above the deep inguinal ring. In such cases, the margins of the deep inguina

ring are formed both above and below by the iliopubic tract.

The inguinal ligament cannot be seen from within the abdominal cavity, because it is concealed by muscular and aponeurotic fibers of the more deeply

situated elements of the anterior abdominal wall. This is true, also, in the area of the femoral canal, which is the region of "touchdown," or insertion, of

aponeurotic and fascial elements upon the pectineal ligament medial to the external iliac vein and artery. Just distal to this point, these vessels, now

renamed the femoral vein and artery, pass into the lower limb within a tube of connective tissue called the femoral sheath.

The femoral canal is an ellipsoidal, funnel-shaped dec livity just medial to the external iliac (f emoral) vein, through which lymphatic vessels f rom the lower

part of the body enter the abdominal cavity. The medial border of the femoral ring, the entrance to the femoral canal, is clearly formed by aponeurotic fibers

of the iliopubic tract and transversalis fascia. Furthermore, this boundary is reinforced more deeply by the insertion of muscular fibers of the transversus

muscular arch, subsequent to its passage above the deep inguinal ring.

As the iliopubic tract passes beneath the deep inguinal ring and in front of the external iliac vessels, it contributes substantially to the anterior layer of the

femoral sheath. Posteriorly, this sheath is formed by the iliopsoas fascia, with deeper contributions from fascia of the pectineal muscle.

Debate regarding the origin of the internal oblique muscle in the inguinal area also applies to the t ransversus abdominis muscle. We again agree with

McVay11that this muscle arises in the inguinal area from the iliopsoas fasc ia, and not from the inguinal ligament.

The t ransversus abdominis arch is useful for the repair of inguinal hernias. This anatomic entity is formed by t he free aponeurotic and muscular lower margin

of the muscle. Medially, however, the arch is principally aponeurotic. Toward the internal ring, it is both muscular and aponeurotic. In the environment of th

internal ring, the internal oblique is muscular, and the transversus abdominis is aponeurotic. The transversus abdominis muscle inserts on Cooper's ligament.

In addition, medially in the inguinal area, all the aponeurotic layers of the three f lat muscles pass anterior to the rec tus muscle and form the anterior lamina

of the sheath.

The integrity of the transversus abdominis muscle prevents the formation of a hernia. We agree with Mc Vay 11that, in this sense, the transversus

abdominis is the most important layer of the abdominal wall. If we believe Askar27and Rizk28that the aponeurosis of this muscle is bilaminar, then both

laminae (anterior and posterior) fuse, or there is some attenuation of the posterior layer, as reported by Rizk. Rizk28also described each abdominal

aponeurosis as bilaminar and each wall of the rect us sheath as t rilaminar (like plywood).


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For a further discussion of the conjoined area (tendon) (Fig. 9-6), see "Conjoined Area (Tendon)" later in this chapter under "Surgical Anatomy of the

Inguinofemoral Area."

Fig. 9-6.

"Conjoined area." (Modified from Skandalakis JE, Colborn GL, Androulakis JA, Skandalakis LJ, Pemberton LB. Embryologic and ana tomic basis of inguinal

herniorrhaphy. Surg Clin North Am 1993;73:799-836; with permission.)

Middle PortionRECTUS ABDOMINIS AND PYRAMIDAL MUSCLES

The rectus muscle is the master muscle of the abdominal wall.Dr. Omar Askar(personal communication to JE Skandalakis, 1990)

The rectus abdominis muscle attaches to the 5th, 6th, and 7th costal cartilages and the xiphoid process above. Below, it attaches to the pubic crest, to

the ligamentous t issue at the symphysis pubis, and the superior ramus of the pubis. It is broader but thinner superiorly.

Each rectus muscle is traversed by three tendinous lines (the tendinous intersections or inscriptions) at the level of the xiphoid process, at the umbilicus,

and halfway between these points. One or two additional fibrous intersections may occur below the level of the navel. These irregular, curved, or zigzagging

tendinous bands are usually tightly affixed to the anterior lamina of the rectus sheath. They are occasionally attached to the posterior lamina as well,

although the tendinous fibers do not ordinarily pass more than halfway through the muscle. Studies by Milloy et al.34demonstrate that three inscriptions are

the most common pattern (58%), and four inscriptions the next most common (35%).

Some have conjectured that the tendinous intersections represent the original embryonic segmentation of the muscle or myosepta delineating the myotome

that form the muscle. Definitive proof of the nature of the bands remains elusive. It may be that the fibrous intersections serve a distinct function, rather

than being embryonic "leftovers." These fibrous bands attach the rectus muscles firmly to the anterior lamina of the rectus sheath and to the superior


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attachment to the semirigid thoracic wall. Thus, as the supraumbilical portion of the rectus contracts, that portion of the rectus sheath becomes taut,

perhaps assisting in respiratory (or other) physiologic mechanisms.

The rectus muscle (Fig. 9-7) is enclosed within a stout sheath formed by the bilaminar aponeuroses of the three flat muscles that divide and pass anteriorly

and posteriorly around the muscle. As noted above, the space between the muscle and the sheath permits the muscle to contract freely with essentially

little restraint, save for the supraumbilica l portion. From the rib margin to a point midway between the umbilicus and the pubis (linea semicircularis of

Douglas), the posterior sheath is made up of the posterior leaf of the internal oblique aponeurosis, the aponeurosis of the transversus abdominis muscle, and

the transversalis fascia. Below this level, the posterior wall is formed by transversalis fascia alone, with variable contributions of aponeurotic bands from the

transversus abdominis. The deep epigastric arteries and veins course along the posterior surface of the rectus muscle, so below the linea semicircularis they

are separated from the peritoneum by only transversalis fascia.

Fig. 9-7.

Rectus abdominis muscle and rectus shea th. (Modified from Schwartz SI (ed). Principles of Surgery (6th e d). New York: McGraw-Hill, 1990; w ith permission.)

The two recti are separated by the linea alba, a tendinous line wherein the three flat muscles both fuse with one another and decussate across the midline.

By means of the decussation of aponeurotic fibers, the contralateral flat muscles may be continuous with one another. For instance, the aponeurotic fibers

of the external oblique muscle of one side are continuous with the internal oblique of the opposite side. 27,28This arrangement is of obvious importance in

the contractile properties of the abdominal wall. The linea alba is considerably wider above the umbilicus than below it. Thus, a midline incision inferior to th

umbilicus will tend to pass through the laminae of the rectus sheath.

When the supine subject begins to raise the head, the rectus abdominis muscle begins to act before the trunk begins to move. Thus, the rectus abdominis

muscle fixes the thorax, so that the sternocleidomastoid muscles can be effective in flexing the neck. Although the rectus is very important in flexing the

trunk, it plays little or no role in rotating the trunk. The oblique muscles figure significant ly in trunk flexion. The internal oblique is also quite ac tive in

maintaining the posture of the upright torso, whereas the external oblique and rectus muscles are quiet.35

The internal oblique and transversus abdominis muscles extend superiorly only to the costal margin, whereas the rectus muscle passes ventral to the costal

margin in its superior insertion. In this region, therefore, the sternum and costal cartilages provide the posterior wall for the rectus sheath. No aponeurotic

lamina is present.

In the lower one-fourth of the abdominal wall, the aponeuroses pass anterior to the rectus muscle as the anterior rectus sheath lamina. The posterior lamina

here is formed essentially by transversalis fascia alone together with a highly variable quantity of aponeurotic transversus bundles. This allows passage of

the inferior epigastric vascular supply into the sheath.

The semicircular line of Douglas (linea semicircularis) marks the lower level of the aponeurotic posterior lamina. This concav ity of the arcuate line is usually

directed downward or downward and laterally. If the change from aponeurosis to transversalis fascia is gradual, the line is poorly defined. If the change is


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a rup , e ne s we mar e .

The pyramidal muscle attaches to the pubic crest and symphyseal ligamentous tissues and inserts into the linea alba. The pyramidal muscle is absent on one

or both sides in 10 to 20 percent of subjects.36When present, its insertion into the linea alba is a landmark for an accurate midline incision.

The superior and inferior epigastric arteries are responsible for the blood supply of the rectus muscle. The superior epigastric vessels are terminal branches

of the internal thoracic artery. The larger, inferior epigastric vessels arise from the external iliacs. The arteries snake behind the muscle within its sheath.

The superior and inferior epigastric vessels anastomose at approximately t he middle one-third of the muscle.

The most characteristic phenomenon of the superior and inferior epigastric arteries occurs when the muscle contracts: the epigastric vessels glide within

their fascial coverings. This avoids injury, bleeding, and the formation of hematoma within the rectus sheath.

Two veins, the superior and inferior epigastric venae comitantes, accompany each epigastric artery.

LINEA ALBA

Rizk28believes that the linea alba should be considered not so much an insertion for the abdominal muscles, but rather the common area of decussation of

their intermediate aponeuroses. According to Rizk, the incision most destructive to the abdominal wall is the vertical midline. The least destructive incision is

the subcostal.

Askar's research27shows that the linea alba is formed by decussating aponeurotic fibers of the rectus sheath. According to Askar, there is a single

decussation of fibers of both the anterior and posterior rectus sheath laminae in 30% of cases. A single decussation of anterior rectus sheath laminae and a

triple decussation of posterior rectus sheath laminae is found in 10% of cases. A triple decussation of aponeurotic fibers of both anterior and posterior

rectus laminae occurs in 60% of cases. Subjects in the group with single fibrous crossings of both the anterior and posterior rectus sheath laminae may be

more susceptible to linea alba herniation.

The linea alba (Figs. 9-2, 9-3, 9-4) is well formed from the xiphoid process of the st ernum to the umbilicus. However, below the umbilicus the formation is

very vague and in most cases indiscernible. Inferiorly, superficial fibers from the linea alba pass in front of the rectus muscle to find attachment to the

symphysis pubis. Deep fibers radiate laterally behind the rectus to attach to the posterior surface of the pubic crest, forming the so-called adminiculum

lineae albae.

The linea alba is one of the most common routes of approach in abdominal surgery and also t he most common site of incisional hernias. Rath et a l.37

undertook a study of its morphology and other factors. They found that morphologic results allowed definition of diastasis of the rectus muscles in terms of

subject age. In subjects less than 45 years of age, diastasis was considered as a separation in excess of 10 mm between the two rectus muscles above th

umbilicus, 27 mm at the umbilical ring, and 9 mm below the umbilicus. In subjects more than 45 years of age, the corresponding values were 15 mm, 27 mm,

and 14 mm respectively. To quote from their findings, "In the biomechanical study the subumbilical region exhibited a coefficient of elasticity greater than

that of the supra-umbilical portion, but no significant difference in resistance was found between the different parts studied."

UMBILICAL AREA

Most anatomy books describe the umbilicus in one or two sentences. We owe our knowledge of anatomy of the umbilicus to Orda and Nathan, 38who

described in detail the entities involved and their variations.

Embryologically, the umbilicus (Figs. 9-8, 9-9) is a midline fusion of the medial aponeurotic borders of both rect us abdominis aponeuroses around the

umbilical cord. This fusion may take place around the 10th week, after the herniated midgut returns to the peritoneal cavity. During the period of fetal

circulation, t he following embryologic entities are found at the umbilicus:

Left umbilical vein

Vitellointestinal duct

Vitelline a rtery and ve in

Urachus

Two umbilical arteries

Fig. 9-8.


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Structures in umbilical cord. V-I, vitellointestinal. (Modified from Basmajian JV, Slonecker CE. Grant's Method of Anatomy (11th ed). Baltimore: Williams & Wilkins,

1989; with permission.)

Fig. 9-9.


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A,Pos terior surface of ante rior abdominal wall of newborn infant, seen from inside abdomen; umbilical cord still attached. B,Diagrammatic sagittal se ction through

normal umbilicus show ing relation o f umbilical ring to linea alba, round ligament, median umbilical ligament (urachus), and umbilical and transversalis fas ciae. Noteabsence of subcutane ous fat o ver umbilical ring. C,Diagrammatic sagittal section th rough small umbilical hernia; hernial sac covered by skin only. (Modified from

Skandalakis LJ, Gadacz TR, Mansberger AR Jr, Mitchell WE Jr, Colborn GL, Skandalakis JE. Modern Hernia Repair: The Embryological and Anatomical Basis of Surgery.

New York: Parthenon, 1996; w ith permission.)

The embryologic entities associated with the umbilical cord and umbilicus are shown in Table 9-4.

Table 9-4. Structures Associated with the Umbilical Cord and Umbilicus

In the Primitive Body Stalk At the Umbilicus at Term In the Neonatal Abdomen Pathology

Yolk stalk (vitelline duct) Absent or vestigial Absent Meckel's diverticulum or umbilical sinus or fistula

Extraembryonic coelom Absent None

Herniated intestine Returned to abdomen Returned to abdomen Failure of return: omphalocele

Vitelline arteries Absent Celiac, superior, and inferior mesenteric arteries

Vitelline veins Absent Part of portal veinAllantois Absent or vestigial Urachus (median umbilical ligament) Patent urachus; undescended bladder

Umbilical arteries Both present Medial umbilical ligaments Single umbilical artery (1%)

Umbilical veins Only left vein present Round ligament in falciform ligament

Undifferentiated mesenchyme Embryonic connective tissue at cord None

Source:Skandalakis LJ, Gadacz TR, Mansbe rger AR Jr, Mitchell WE Jr, Colborn GL, Skandalakis JE. Modern Hernia Repair: The Embryological and Anatomical Basis of

Surgery. New York: Parthenon, 1996, p. 6; with permission.

Remember the following four anatomic entities, which pass through the umbilical ring in the newly born child:

Left umbilical vein (round ligament of the liver)

Urachus (median umbilical ligament)

Two umbilical arteries (medial umbilical ligaments)


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The umbilicus is located at the center of the umbilical region. For all practical purposes, the umbilicus is a scar. It is not the same in all individuals. Its

boundaries are the epigastric area above, the hypogastric area below, and the right and left lumbar areas laterally.

The umbilicus is essentially at the vertical midpoint of the linea alba. It marks the junction of the lower end of the well-formed upper linea alba and the

beginning of the poorly-defined lower linea alba.

Umbilical Ring

The medial umbilica l ligaments (obliterated umbilical arteries) and the urachus (obliterated allantoic duc t) part icipate in the formation of the fibrous umbilical

ring. The round ligament (obliterated umbilical vein) arises from the inferior margin of the ring and passes superiorly in the falciform ligament. Acc ording to

Orda and Nathan,38the umbilical ring (Fig. 9-10) and its four essentially solid tubes (two obliterated umbilical arteries, the urachus, and the round ligament)

are related as follows:

Umbilical ligaments

In 74% of cases , the ligamentum teres of the liver crosses the umbilical ring, and attaches to its lower margin.

In 24%, the ligamentum teres splits and attaches to the upper margin of the ring, forming a triangle. The urachus a lso splits to form another triangle related to

the lower margin of the ring. It is possible that the structure and manner of formation of these triangles are involved in the genesis of sup raumbilical or

infraumbilical hernias.

Umbilical fascia

In 36%, a localized th ickening of the transversalis fascia in this a rea, named the umbilical fascia, covers the umbilical ring in toto. This fascial "buffer" can protect

against the gene sis of an umbilical hernia.

In 38% of individuals, the umbilical fascia covers only the upper part o f the umbilical ring.

In 6% of individuals, the umbilical fascia covers on ly the lower part o f the umbilical ring.

In 4% of individuals, the umbilical fascia is located above the ring.

In 16% o f individuals, the umbilical fascia is absent.

Fig. 9-10.


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Variations in umbilical ring and umbilical fascia seen from poste rior (peritonea l) surface of body wa ll. A-C,Variations in disposition o f umbilical ligaments. Arrows

indicate: A,Usual relations (74 percent) of umbilical ring (UR), round ligament (RL), urachus (U), and medial umbilical ligaments (MUL). Round ligament crosses

umbilical ring to insert on its inferior margin. B,Less-common configuration (24 percent). Round ligament splits and attaches to superior margin of umbilical ring. C,

Rare configuration (less than 1 percent). Round ligament branches before reaching umbilical ring. Each branch continues with the medial umbilical ligament w ithout

attaching to umbilical ring. D-G,Variations in pres ence and form of insertion o f umbilical fascia. D,Thickened transversalis fascia forms umbilical fascia covering

umbilical ring (36 percent). Arrows indicate: E,Umbilical fascia covers only superior portion of umbilical ring (38 percent). F,Umbilical fascia covers only inferior

portion of umbilical ring (6 percent). G,Though present, umbilical fascia doe s no t unde rlie umbilical ring (4 percent). (No figure: Fascia is entirely absent in 16

percent.) (Modified from Orda R, Nathan H. Surgical anatomy of umbilical structures. Int Surg 1973;58:454-464; with permission.)

TRANSVERSALIS FASCIA

The name transversalis fascia, formerly applied to the deep fascia covering the internal surface of the transversus abdominis muscle, can be applied in a

general way to the entire connective tissue sheet lining the parietal musculature of the abdominal cavity. It covers muscles, aponeuroses, bones, and

ligaments. The transversalis fascia may be closely adherent, such as the portion covering the transversus abdominis aponeurosis. In other areas it may be

thick or thin and discrete.

Some anatomists consider the transversalis fascia to be a laminated layer of tissue located between the peritoneum and the posterior wall of the

transversus abdominis muscle anteriorly. Its upward continuation blends with the inferior diaphragmatic fascia. Downward it is continuous with the iliac and

pelvic fasciae and several other thickenings related to the inguinofemoral area, where it is said to split into anterior and posterior laminae. Its posterior

pathway toward the posterior lumbar wall fuses with the anterior lamina of the thoracolumbar fascia.

A deficient posterior wall, found in the inguinal canal of 23% to 25% of patients, lacks the support of the aponeurosis of the transversus abdominis

muscle.39The transversalis fascia, therefore, is the only anatomic entity contributing to the continuity of the floor. 39Structural weakness may occur when

the arch is in a high position or when there is poor arch participation in the posterior walls and floor (Fig. 9-11). In a few patients, the transversalis fascia

crura may be difficult to locate, owing to their underdevelopment. Without statistical data, we can only propose that this is a congenital defect or variation

Fig. 9-11.


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Cross section of a weak poste rior canal wall. (Modified from Lampe EW. The transversalis fascia. In Nyhus LM, Condon RE (eds ). Hernia (4th ed). Philadelphia: JB

Lippincott, 1995, pp. 53-57; w ith permission.)

PERITONEUM

The peritoneum is the innermost layer of the abdominal wall anteriorly, laterally, and posteriorly. It is loosely connected with the transversalis fascia in most

areas, except at the internal ring, where the connection is stronger. It can also be fused rather tightly to the posterior lamina of the rectus sheath,

rendering their separation difficult. The processus vaginalis, a peritoneal diverticulum, is embryologically related to the deep inguinal ring (see the c hapter o

the peritoneum for details).

Some comparisons between the structures of the upper three-fourths of the abdominal wall and those of the lower one-fourth are shown in Table 9-5.

Table 9-5

Upper Midline Lower Midline

Linea alba well developed Linea alba poorly developed

Right and le ft re ct i well separa ted Right and le ft re cti close toge ther

Anterior and posterior layers of sheath present Only anterior layer of sheath present

Aponeurosis of external oblique weak or absent Aponeurosis of external oblique strong and w ell developed

Source:Skandalakis LJ, Gadacz TR, Mansbe rger AR Jr, Mitchell WE Jr, Colborn GL, Skandalakis JE. Modern Hernia Repair: The Embryological and Anatomical Basis of

Surgery. New York: Parthenon, 1996, p. 4; with permission.

Blood Supply of the Anterior Abdominal Wall

Where there have been no previous incisions, the blood supply to the abdominal wall creates no problem. Where scars are present, the surgeon should be

familiar with details of the blood supply to avoid necrosis from ischemia to specific areas. If possible, the surgeon should proceed through an existing scar.

With multiple operations the abdominal wall may develop weakness resulting in acute herniation and dehiscence or in the formation of vent ral hernia; theseare secondary to bad technique or compromising the blood supply of the wall.

ARTERIES

The superficial tissues of the lower anterolateral abdominal wall are supplied by three branches of the femoral artery. These branches, from lateral to media

are the superficial circumflex iliac artery (Fig. 9-12), the superficial epigastric artery, and the superficial external pudendal artery. Branches of these arteries

travel toward the umbilicus in the subcutaneous connective tissues.

Fig. 9-12.


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Superficial arteries of inguinal region. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill,

1983; with permission.)

The superficial epigastric artery anastomoses with the contralateral artery. All three arteries have anastomoses with the deep arteries. Following its origin

from the femoral artery, the superficial epigastric artery ascends across the inguinal region, halfway between the pubic tubercle and the anterior superior

iliac spine. It then passes toward the umbilicus.40

The deep arteries lie between the transversus abdominis and the internal oblique muscles. They are the posterior intercostal arteries 10 and 11, the anterior

branch of the subcostal artery, the anterior branches of the four lumbar arteries, and the deep circumflex iliac artery.

The deep circumflex iliac artery arises from the external iliac, several centimeters above the inguinal ligament. The vessel passes laterally in the iliac fossa,

supplying the ilium and the iliacus muscle. A large ascending branch of the deep circumflex iliac passes deep to the iliopubic tract. Then, adjacent to the

anterior superior iliac spine, it ascends vertically within the abdominal wall between t he transversus abdominis and the internal oblique. This branch is,

apparently, the primary arterial source for the internal oblique muscle. Its existence allows this muscle to be used as a free flap or pedicle flap or, together

with a portion of the iliac crest, a combined muscular and osseous flap.41

The rectus sheath is supplied by two arteries. The superior epigastric artery arises from the internal thoracic artery. The inferior epigastric artery arises from

the external iliac artery, just above the inguinal ligament. The inferior epigastric artery is distinctly larger than the superior epigastric artery. The average

diameter of the former is 3.4 mm, while the diameter of the latter is 1.6 mm.

Generally, the inferior epigastric artery divides into two large branches below the level of the umbilicus. These vessels communicate with the superior

epigastric artery above the level of the umbilicus.42These epigastric arteries anastomose with one another in about 40 percent of subjects, 34although the

anastomosing branches are generally less than 0.5 mm in diameter.42

The superior epigastric artery enters the upper end of the rectus sheath, deep to the rectus muscle. Musculocutaneous branches pierce the anterior rectus

sheath to supply the overlying skin.43The perforating arteries (Fig. 9-13) are closer to the lateral border of the rectus than to the linea alba. The number

and size of perforating branches of the inferior epigastric vessels, in particular, become greatest at the level of the umbilicus and just inferolateral to it. Few

perforators are present in the lower fifth of the rectus region (Fig. 9-14). 42

Fig. 9-13.

Vessels supplying ante rior abdominal wa ll. EOP, External oblique perforators; SCI, Superficial circumflex iliac artery; SE, Superior epigast ric artery; DCI, Deep

circumflex iliac artery; IE, Deep inferior epigastric artery; SIEA, Superficial inferior epigastric artery. (Modified from Hester TR Jr, Nahai F, Beegle PE, Bostwick J III.

Blood supply of the abdomen revisited, with emphasis on the superficial inferior epigastric artery. Plast Reconstruct Surg 1984;74:657-666; with pe rmission.)

Fig. 9-14.


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Primary territories of vess els supplying anterior abdominal wa ll.Above, left:Skin territory of superficial inferior epigastric artery (SIEA).Above, right:Skin territory of

external oblique perforators (EOP). Center:Skin territory of deep epigastric system. Below, left:Skin territory of superficial circumflex iliac system (SCI). Below, right:Skin territory of deep circumflex iliac system (DCI). (Modified from Hester TR Jr, Nahai F, Beegle PE, Bostwick J III. Blood supply of the abdomen revisited, with

emphasis on the superficial inferior epigastric artery. Plast Reconstruct Surg 1984;74:657-666; with permission.)

Creating an incision too far laterally will result in bleeding from the several perforating arteries, and muscle paralysis from cutting the musculocutaneous

nerves. To avoid injury to major vessels in abdominal operative laparoscopic procedures, laterally situated trocars should be placed at least 8 cm from the

midline, and at least 5 cm above the pubic bone.44Should vascular injury occur, thought should be given to enlarging the incision and directly securing the

injured vessel. The vessel should be occluded with electrocautery, ligature, or vascular clip to avoid the formation of a large hematoma or serious

postoperative bleeding. Injury can occur following movements of the trunk by the unconscious or conscious patient, which can lead to traction on and

reopening of the injured vessel.45

The inferior epigastric artery arises in the preperitoneal connective tissue. It enters the sheath at or below the level of the semicircular line of Douglas,

passing between the rectus muscle and the posterior layer of the sheath.

VEINS

The veins follow the arteries.

Further information about anterior abdominal circulation may be found later in t his chapter under "Blood Supply of the Inguinal Area."

Lymphatics of the Anterior Abdominal Wall

The lymphatic drainage of the skin of the anterior abdominal wall is presented in Figure 9-15. The lymphatics can be divided into supraumbilica l and

infraumbilical networks with further groupings for superficial and deep struct ures.

Fig. 9-15.


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Probable lymphatic drainage o f anterior abdominal wall. Deep drainage shown on left. Superficial drainage shown on right. Arrows indicate course o f drainage.

The superficial supraumbilica l network drains to axillary, pec toral, and infraclavicular lymph nodes. The deep supraumbilical network drains to axillary and

internal mammary nodes, with some lymphatics to the lymph nodes at t he area of the porta hepat is. The superficial infraumbilica l network drains to

superficial inguinal lymph nodes. The deep infraumbilical network drains to aortic lymph nodes and deep femoral lymph nodes.

Read an Editorial Comment

Nerve Supply to the Anterior Abdominal Wall

Both the anterolateral portion of the abdominal wall and the rectus abdominis muscle are supplied by anterior rami of the 7th to 12th thoracic nerves and

the 1st lumbar nerve. A branch (the lateral cutaneous ramus) arises from each anterior ramus and pierces the outer two flat muscles. It innervates the

external oblique muscle and forms the lateral cutaneous nerve.

The anterior rami of the last six thoracic nerves enter the posterior layer of the rectus sheath, innervating the rectus muscle. They send perforating

branches through the anterior layer of the sheath to form the anterior cutaneous nerves. The first lumbar nerve forms an anterior cutaneous nerve without

passing through the rec tus sheath. These relationships are shown diagrammatically in Figure 9-16.

Fig. 9-16.
http://windowreference%28%27editorialcomment%27%2C%27editorialcomment.aspx/?aID=90024&comment_aID=90147%27);http://windowreference%28%27editorialcomment%27%2C%27editorialcomment.aspx/?aID=90024&comment_aID=90147%27);


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Course of anterior ramus of segmental nerves in anterior body wall. A,Seventh to tw elfth thoracic nerves. B,First lumbar nerve. (Modified from Skandalakis JE, Gray

SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

According to Monkhouse et al.,32variation in the arrangement of the segmental nerves to the anterior abdominal wall is considerably greater than that

suggested in most textbooks. For instance, one cannot predict with confidence that the umbilical region is supplied by the 10th thoracic spinal nerve.

Rectus muscle paralysis, with weakening of the abdominal wall, will result from section of more than one of these nerves. There is little if any cross-

communication between the segmental nerves to the rectus abdominis muscle. The anterior ramus must not be mistaken for the branch of the subcutaneou

nerve that runs in the same direction as, but is superficial to, the external oblique muscle. Injury of the motor supply to a segment of the rectus muscle will

result in fibrosis of that segment.

Lee and Dellon46stated that groin pain of neural origin can be treated with positive outcomes by realizing that symptoms can be referred to regions other

than the groin. They related referred pain in the knee to the lateral femoral cutaneous nerve, in the pelvic viscera to the iliohypogastric nerve, and in the

testicle to the genitofemoral nerve. The fourth source of referred pain is the ilioinguinal nerve. Referred pain may be related to more than one of the nerves

The lateral femoral cutaneous nerve was decompressed and the other nerves were resected.

Surgical Considerations of the Anterior Abdominal Wall

(NOTE:Further surgical considerations are included later in this chapter under "Incisions of t he Anterior Abdominal Wall" and "Hernias of the Abdominal Wall."

Rectus sheath hematoma (arterial or venous) takes place without trauma or disease in most cases (see Fig. 9-7). A palpable mass may or may not be present at

the right or left rectus area. When the pa tient tense s the rectus muscle, the tender mass may be palpable. This is Fothergill's sign.47Occasionally, the hematoma

may be mistaken for a spigelian hernia or acute abdominal process. Use of ultrasonography, CT, or MRI for diagnosis a voids unnecessary surgical intervention. If

symptoms persist, incision and evacuat ion is the procedure o f choice.

Desmoid tumors are ben ign tumors of aponeurotic origin. The home of desmoid tumors is the anterolateral abdominal wall formed by the three flat muscles. The

etiology of such tumors is unknown. The treatment of choice is wide excision.

Editorial CommentThere is debate as to whether desmoid tumors should be classified as benign (aggressive fibromatosis) or as low grade fibrosarcomas (Grade

I). Desmoids virtually never metas tasize, but the y present and behave in a fashion identical to low grade so ft tissue sa rcomas. Desmoids of the abdominal wall can

usually be cured by wide excision; inadequate excision will lead to local recurrence. Deaths due to abdominal wall desmoids are infrequent, but desmoid tumors in

certain critical areas such a s the abdomen, pelvis, or the neck may be initially unresectable or may lead to death from unresectable local recurrence. (Roger S.

Foster, Jr., MD)

The superficial fascia of the ante rior abdominal wa ll includes the a dipose layer of Camper and the membranous layer of Scarpa. Scarpa's fascia of the lower ante ri

abdominal wall possesses regional peculiarities. It is attached to the crest of the ilium and to the symphysis pubis, but not to the superior border of the pubic crest.

More laterally, Scarpa's fascia is attached to the fascia lata of the thigh.

Extravasating fluid from the perineal region can pass superiorly deep to this fascial layer, but it cannot pass into the limb. By the same token, therefore, any

collect ion of fluid within the sc rotum may be drained with ease by a small suprapubic incision and finger dissec tion.

Nicodemo48reported access to the pelvic extraperitonea l space by a suprapubic pathwa y. This was performed by puncture in a midline position 1 cm above the

pubis between the linea alba and the vesicoumbilical fascia.

Rectus abdominis muscle and omental flaps can be used to reconstruct huge chest wall defects, either as free flaps or based upon a vascular pedicle.

If the pe riumbilical fasciae do not fuse at the base of the umbilical cord, formation of an umbilical hernia will result (at the cente r of the umbilicus). In most cas es,

the hernia will close spontaneously within a few years.


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Emergency surgery is advised for viscus incarceration.

Whe n supraumbilical or infraumbilical hernias a re diagnosed, surgery is advised.

Inguinofemoral Area

Inguinal Canal

ANATOMY OF THE INGUINAL CANAL IN INFANTS AND CHILDREN

There are readily apparent differences between the inguinal canals of infants and adults.49In infants, the canal is short (1 to 1.5 cm), and the internal and

external rings are nearly superimposed upon one another. Scarpa's fascia is so well developed that the surgeon may mistake it for the aponeurosis of the

external oblique muscle, resulting in treating a superficial ectopic testicle as an inguinal cryptorchidism. There also may be a layer of fat between the fascia

and the aponeurosis. We remind surgeons of the statement of White 50that the external oblique fascia has not been reached as long as fat is encountered.

In a newborn with an indirect inguinal hernia, there is nothing wrong with the posterior wall of the inguinal canal. Removal of the sac, therefore, is the only

justifiable procedure. However, it is extremely difficult to est imate the weakness of the newborn's posterior inguinal wall by palpation. If a defect is

suspected, a few interrupted permanent sutures might be used to perform the repair.51

ADULT ANATOMY OF THE INGUINAL CANAL

The inguinal canal in the adult is an oblique rift in the lower part of the anterior abdominal wall. It measures approximately 4 cm in length. It is located 2 to

cm above the inguinal ligament, between the opening of the external (superficial) and internal (deep) inguinal rings.

The boundaries of the inguinal canal (Fig. 9-17) are as follows:

Anterior:The anterior boundary is the aponeurosis of the external oblique muscle and, more laterally, the internal oblique muscle. Remember, there are no exte rna

oblique muscle fibers in the inguinal area, only aponeurotic fibers.

Posterior:In about o f subjects, the pos terior wall (floor) is formed laterally by the aponeuros is of the transve rsus abdominis muscle and the transversalis fascia

in the remainder, the posterior wall is transversalis fascia only. Medially the pos terior wall is rein

chapter 9 abdominal wall and hernias

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