Abdominal Wall

The abdominal wall is defined superiorly by the costal margins, inferiorly by the symphysis pubis and pelvic bones, and posteriorly by the vertebral column.

It serves to support and protect abdominal and retroperitoneal structures, and its complex muscular functions enable twisting and flexing motions of the trunk.

To gain surgical access to the abdominal cavity, an intimate knowledge of the arrangement of the muscles and aponeuroses of the abdominal wall is required

Layers of the abdominal wall

skin, subcutaneous tissue, superficial fascia, external oblique muscle, internal oblique muscle, transversus abdominis muscle, transversalis fascia, preperitoneal adipose and areolar tissue, peritoneum

Muscles of the Abdominal Wall - Listed Alphabetically

Muscle Origin Insertion Action Innervation

Artery Notes

external abdominal oblique

lower 8 ribs

linea alba, pubic crest & tubercle, anterior superior iliac spine & anterior half of iliac crest

flexes and laterally bends the trunk

intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves

musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a.

the inguinal ligament is a specialization of the external abdominal oblique aponeurosis; the external spermatic fascia is the external abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord

internal abdominal oblique

thoracolumbar fascia, anterior 2/3 of the iliac crest, lateral 2/3 of the inguinal ligament

lower 3 or 4 ribs, linea alba, pubic crest

flexes and laterally bends the trunk

intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves

musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a.

anterior fibers of internal abdominal oblique course up and medially, perpendicular to the fibers of external abdominal oblique; the cremaster muscle and fascia is the internal abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord

pyramidalis pubis, anterior to the rectus abdominis

linea alba draws the linea alba inferiorly

subcostal nerve

subcostal a., inferior epigastric a.

the pyramidalis m. is not always present

rectus abdominis

pubis and the pubic symphysis

xiphoid process of the sternum and costal cartilages 5-7

flexes the trunk

intercostal nerves 7-11 and subcostal nerve

superior epigastric a. intercostal aa., subcostal a., inferior epigastric a.

rectus sheath contains rectus abdominis and is formed by the aponeuroses of external and internal oblique and transversus abdominis mm.

transversus abdominis

lower 6 ribs, thoracolumbar fascia, anterior 3/4 of the iliac crest, lateral 1/3 of inguinal ligament

linea alba, pubic crest and pecten of the pubis

compresses the abdomen

intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves

musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a.

transversus abdominis muscle does not contribute to the coverings of the spermatic cord and testis; transversalis fascia, the deep fascia that covers the inner surface of the transversus abdominis, forms the internal spermatic fascia

Rectus Sheath

ANTERIOR ABDOMINAL WALL

Joints and Ligaments of the Abdomen - Listed AlphabeticallyJoint or ligament Description Notesinguinal ligament the ligament that connects

the anterior superior iliac spine with the pubic tubercle

the inguinal ligament is a specialization of the inferior border of the external abdominal oblique aponeurosis; it is the site of origin for a part of the internal abdominal oblique muscle and for a part of the transversus abdominis muscle; also known as: Poupart's ligament

lacunar ligament an extension of the medial end of the inguinal ligament which connects the pubic tubercle with the pecten of the pubis

the lacunar ligament is a flattened portion of the aponeurosis of the external abdominal oblique m. that projects posteriorly from the pubic tubercle; it forms the medial border of the femoral ring and the floor of the inguinal canal at the superficial inguinal ring

pectineal ligament a thickening of fascia on the pecten of the pubis

the pectineal ligament looks like an extension of the lacunar ligament along the surface of the pectineal line; also known as: Cooper's ligament (note: Cooper's ligaments are also found in the breast)

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Arteries – sup & inf epigastric, last 6 intercostal, 4 lumber, deep cicumpl. Iliac

Veins – above & below umbilicus to sup. & inf. Vena cava; paraumbilical vein

Nerves – 7th to 12th inercostals, ileohypogastric ileoinguinal

Lymphatics – Axillary & Superficial inguinal

Nerves of the Abdominal WallNerve Source Branches Motor Sensory Notes

intercostal n.

ventral primary rami of spinal nerves T1-T11

lateral & anterior cutaneous brs.

intercostal muscles; abdominal wall muscles (via T7-T11); muscles of the forearm and hand (via T1)

skin of the chest and abdomen anterolaterally; skin of the medial side of the upper limb (via T1-T2)

intercostal n.travels below the posterior intercostal a. in the costal groove

iliohypogastric n.

lumbar plexus (ventral primary ramus of spinal nerve L1)

lateral and anterior cutaneous brs.

muscles of the lower abdominal wall

skin of the lower abdominal wall, upper hip and upper thigh

iliohypogastric n. receives a contribution from T12 in approximately 50% of cases

ilioinguinal n. lumbar plexus (ventral primary ramus of spinal nerve L1)

anterior cutaneous br. (also known as: anterior labial/scrotal n.)

muscles of the lower abdominal wall

skin of the lower abdominal wall and anterior scrotum/labium majus

ilioinguinal n. courses through the inguinal canal and superficial inguinal ring

subcostal n. ventral primary ramus of T12

lateral cutaneous br., anterior cutaneous br.

muscles of the abdominal wall

skin of the anterolateral abdominal wall

the subcostal n. is equivalent to a posterior intercostal n. found at higher thoracic levels

Topographical Anatomy of the Abdominal Wall

Structure/Space Description/Boundaries

Significance

arcuate line anatomical feature on the inner surface of the abdominal wall; a fascial line in the transverse plane approximately 1/2 of the distance from the umbilicus to the pubic symphysis

arcuate line is the point at which the posterior lamina of the rectus sheath ends and transversalis fascia lines the inner surface of the rectus abdominis m. intercristal line an imaginary line

drawn in the horizontal plane at the upper margin of the iliac crests

intercristal line locates the level of the L4 vertebra; a useful landmark in spinal tap procedure

intertubercular line an imaginary line drawn in the horizontal plane at the upper margin of the iliac tubercles

intertubercular line locates the level of the L5 vertebra; used with midinguinal and transpyloric lines to divide the abdominal wall into 9 regions

Muscles of the Posterior Abdominal Wall

Muscle Origin Insertion Action Innervation Artery Notes

iliacus iliac fossa and iliac crest; ala of sacrum

lesser trochanter of the femur

flexes the thigh; if the thigh is fixed it flexes the pelvis on the thigh

femoral nerve

iliolumbar a.

inserts in company with the psoas major m. via the iliopsoas tendon

iliopsoas iliac fossa; bodies and transverse processes of lumbar vertebrae

lesser trochanter of the femur

flexes the thigh; flexes and laterally bends the lumbar vertebral column

branches of the ventral primary rami of spinal nerves L2-L4; branches of the femoral nerve

iliolumbar a.

a combination of the iliacus and psoas major mm.

psoas major

bodies and transverse processes of lumbar vertebrae

lesser trochanter of femur (with iliacus) via iliopsoas tendon

flexes the thigh; flexes & laterally bends the lumbar vertebral column

branches of the ventral primary rami of spinal nerves L2-L4

subcostal a., lumbar aa.

the genitofemoral nerve pierces the anterior surface of the psoas major m.

psoas minor bodies of the T12 & L1 vertebrae

iliopubic eminence at the line of junction of the ilium and the superior pubic ramus

flexes & laterally bends the lumbar vertebral column

branches of the ventral primary rams of spinal nerves L1-L2

lumbar aa. absent in 40% of cases

quadratus lumborum

posterior part of the iliac crest and the iliolumbar ligament

transverse processes of lumbar vertebrae 1-4 and the 12th rib

laterally bends the trunk, fixes the 12th rib

subcostal nerve and ventral primary rami of spinal nerves L1-L4

subcostal a., lumbar aa.

the lateral arcuate ligament of the diaphragm crosses the anterior surface of the quadratus lumborum m.

diaphragm xiphoid process, costal margin, fascia over the quadratus lumborum and psoas major mm.(lateral & medial arcuate ligaments), vertebral bodies L1-L3

central tendon of the diaphragm

pushes the abdominal viscera inferiorly, increasing the volume of the thoracic cavity (inspiration)

phrenic nerve (C3-C5)

musculophrenic a., superior phrenic a., inferior phrenic a.

left crus attaches to the L1-L2 vertebral bodies, the right crus attaches to the L1-L3 vertebral bodies

Congenital defect of the abdominal wall

In omphalocele, viscera protrude through an open umbilical ring and are covered by a sac derived from the amnion

In gastroschisis, the viscera protrude through a defect lateral to the umbilicus and no sac is present

Persistence of a vitelline duct Persistence of urachal remnants Infantile umbilical hernia

Other Lesions of the Abdominal Wall

Hematoma of the Rectus Sheath - may also occur secondary to disorders of coagulation, blood dyscrasia, or degenerative vascular diseases. Pregnancy

Sudden onset of pain, worse on contraction Tenderness, guarding, tender mass,

echymosis Diagnosis confirmed by USG or CT 90% respond to conservative treatment –

correction of coagulopathy, blood transfusion Angiographic embolisation surgical evacuation & heamostasis

Abdominal Wall Tumors – fibromas, lipomas

Heamangioma, neurofibroma, Desmoid tumor (Musculoaponeurotic

fibromatoses) Abdominal wall sarcoma Metastatic

Desmoid Tumour Occurs sporadically or as part of an inherited

syndrome (FAP), Scar of abdominal trauma,

operation,pregnancy. 80% in women The superficial disease, also known as

Dupuytren's fibromatosis, is slow growing, is small in size, and rarely involves deeper structures.

Deep fibromatosis has a relatively rapid growth rate, often attains a large size, has a high rate of local recurrence, and involves the musculature of the trunk and extremities

Wide excission (2.5cm), high recurrence rate Adjuvant radiotherapy, NSAID, antiestrogens

Abdominal Wall Sarcoma

Account for 10% of sarcomas Nonreducible lesions arising from below

the superficial fascia Size greater than 5 cm Recent increase in size Fixation to the abdominal wall Fixation to organs in the abdomen MRI & Biopsy Resection with reconstruction

Diastasis Recti

A diffuse widening and thinning of the linea alba without a fascial defect, fascia transversalis is intact.

On examination, this condition appears as a fusiform, linear bulge between the two rectus abdominis muscles without a discrete fascial defect.

Although this condition may be unsightly, repair should be avoided since there is no risk of incarceration, the fascial layer is weak, and the recurrence rate is high.

A CT scan will differentiate rectus diastasis from a true ventral hernia

Abdominal Wall Infection

Superficial cellulitis – abdominal wound

Deep Cellulitis Progressive post op synergistic

gangrene microaerophilic non-heamolytic streptococci and a staph

Amoebic Cutis

Pain in the Abdominal Wall Abdominal pain may be categorized as

Visceral- inflammation, distention, or ischemia. Somatoparietal- inflammation of the parietal

peritoneum Referred - felt in anatomic regions remote from

the diseased organ Pain from a diaphragmatic, supradiaphragmatic,

or spinal cord lesion may be referred to the abdomen.

Herpes zoster (shingles) may present as abdominal pain, in which case it will follow a dermatomal distribution.

Scars may be sensitive or painful Entrapment of a nerve

Abdominal incisions

Abdominal incisions are based on anatomical principles

They must allow adequate assess to the abdomen They should be capable of being extended if

required Ideally muscle fibres should be split rather than cut Nerves should not be divided The rectus muscle has a segmental nerve supply It can be cut transversely without weakening a

denervated segment Above the umbilicus tendinous intersections

prevent retraction of the muscle

Abdominal wall incissions

Accessibility

Flexibility

Security

Allow sufficient access Extendable if

necessary Easy to open Minimise damage to

tissues Avoid cutting nerves Split rather than

transect muscles Limit damage to fascia

Easy to close Allow sufficiently

strong closure

Types of Incission

Vertical –midline or paramedian, supra or infra umbilical. extendable

Transverse or oblique – Kocher’s, MacBurney’s Pfannenstiel infraumbilical incision,

Abdominothoracic -peritoneal cavity, pleural space, and mediastinum into a single operative field

Extraperitonial or Retroperitonial – Kidney, adrenal, aorta

Laparoscopic Ports

Choice of Incission

Organs of interest and proceedure planned Build of patient Urgency or Speed - Midline Previous operative scar – re-entry through

previous incission, never parallel or acute angle

Choice or experience of surgeon Consideration for future proccedure Placement of stoma if necessary Cosmesis

Vertical versus Transverse Incisions Build of the patient- Obesity,

Subcostal arch Transverse direction of fascial fibres Postoperative pain, pulmonary

complications, and frequencies of incisional hernia and burst abdomen

Transverse or Oblique

Subcostal Chevron or Rooftop MacBurney grid iron or Rockey-Davis

muscel splitting Pfannenstiel Incision Thoracoabdominal Retropritonial

Vertical Incissions

Midline Medial Paramedian Lateral paramedian Vertical muscel splitting

Midline incissions

It is almost bloodless, No muscel fibres are devided No nerves are injured It affords goods access It is very quick to make as well as to

close It can be easily extended

Midline incision Midline incisions are the commonest approach to the

abdomen The following structures are divided:

Skin Linea alba Transversalis fascia Extraperitoneal fat Peritoneum

The incision can be extended by cutting through or around the umbilicus

Above the umbilicus the Falciform ligament should be avoided

The bladder can be accessed via an extraperitoneal approach through the space of Retzius

The wound can be closed using a mass closure technique The most popular sutures are either non-absorbable or

absorbable monofilaments At least 1 cm bits should be taken 1 cm apart Requires the use of one or more sutures four times the wound

length

Paramedian incision A paramedian incision is made parallel to and

approximately 3 cm from the midline The incision transverse:

Skin Anterior rectus sheath Rectus - retracted laterally Posterior rectus sheath - above the arcuate line Transversalis fascia Extraperitoneal fat Peritoneum

The potential advantages of this incision are: The rectus muscle is not divided The incisions in the anterior and posterior rectus sheath are separated by

muscle

The incision is closed in layers Takes longer to make and close Had a lower incidence of incisional hernia (when sutures

were not so good) Tends to weaken the vacularity & Nerve supply of recti Incission is laborious Poor access to contralateral structures

Closure of Abdominal Incissions Peritonium Muscels Fascia Mass closure Subcutaneous tissue Skin Tension sutures Drains

Burst Abdomen

Close with non-absorbable, monofilament Inturrupted sutures, 2 layers better, matress Avoid tight suturing (4-5 times incission

length) Avoid drainage directly through wound Transverse better then vertical Deep wound infection, pancreatic &

intestinal leak Coughing, vomiting & distention General condition

Clinical features

Serosanguinous (pink) discharge Sense of something giving away Coils of intestines and omentum

lying below the skin Ocasionally pain & shock Features of intestinal obstruction

Treatment - Emergency operation

Reassure, cover with sterile drapes I V fluid, N G Tube, Analgesics,

Sedatives Protruding intestines, omentum and

wound washed with sterile saline Deep infection or leaks looked for Single layer monofilament mattress

with soft rubber or plastic tube Abdominal support Recurrence is rare but hernia may

follow

Umbilicus

Infection of the umbilical chord – prophylaxis

OmphalitisAbscessExtensive ulcerationSepticaemiaJaundicePortal vien thrombosisPeritonitisUmbilical hernia

Discharge from Umbilicus

Umbilical granuloma – silver nitrate Dermatitis – bacterial , fungal Pilonidal sinus Umbilical calculus (Umbolith) Abscess (Urachal remnant) Umbilical fistulae

Intraperitonial pathology Patent vitellointestinal duct Patent Urachus

Persistence of the Omphalomesenteric Duct

Abnormalities Resulting From Persistence of the Allantois

The intra-abdominal portion is termed the urachus

The extra-abdominal allantois is contained within the umbilical cordThe urachus is converted into a fibrous cord that courses between the extraperitoneal urinary bladder and the umbilicus as the median umbilical ligamentPersistence of a part or all of the urachus may result in the formation of a vesicocutaneous fistula

An extraperitoneal urachal cyst presenting as a lower abdominal mass, or an urachal sinus with the drainage of a small amount of mucusTreatment is excision of the urachal remnant with closure of the bladder, if necessary

Umbilical Neoplasms

Benign – adenoma or rasberry tumour, commonly seen in infants

Endometrioma – women between 20 – 45

Malignant – Secondary carcinoma – Sister Joseph’s Nodule. It is a late manifestation of primaries in stomach, colon, ovary, breast, liver