Anterior Abdominal Wall

5/27/2018 Anterior Abdominal Wall

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nterior bdominal Wall Layer of anterior abdominal wall

A- Lateral:

1- Skin.2- Subcutaneous tissue.

3- External oblique muscle.

4- Internal oblique muscle.

5- Transversus abdominis muscle.

6- Fascia transversalis.

7- Peritoneum.


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1- Skin

A- Lateral


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2- Subcutaneous tissue

A- Lateral


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FasciaSuperficial:

Campers fascia

Continuous with fascia over thorax and thigh.

Fatty layer.


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FasciaDeep Superficial:

Scarpas fascia

Membranous layer.

Continues into perineum as:

Superficial perineal fascia = Colles fascia.

Deep:Thin layer covering abdominal muscles.


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3- External Oblique m.

A- Lateral


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4- Internal Oblique m.

A- Lateral


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5- Transversus abdominis m.

A- Lateral


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6- Fascia Transversalis m

A- Lateral


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7- Peritoneum

A- Lateral


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nterior bdominal Wall Layer of anterior abdominal wall

B- Medial:

1- Skin.

2- Superficial fascia.3- Anterior wall of rectus sheath.

4- Rectus muscle.

5- Posterior wall of rectus sheath.

6- Peritoneum.


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1- Skin

B- Medial


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2- Subcutaneous tissue

B- Medial


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3- Ant. Wall of Rectus

sheath

B- Medial


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4- Rectus Muscle

B- Medial


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B- Medial

5- Post. Wall of Rectussheath


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B- Medial

6- Peritoneum


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External Oblique Muscle

OriginFleshy digitations

from the lower 8 ribs


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The muscle is inserted by fleshy fibers as well asaponeurosis, as follows:

A- Fleshy fibers:

Outer lip of the iliac crest

B- Aponeurosis:

1. Medial part linea alba from xiphoid process to

symphysis pubis

2. Lateral part folded upwards & backwards upon itself

to form the inguinal ligament (ASIS pubic tubercle)

InsertionXiphoid

Process

Symphysis

Pubis


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Direction of fibersDownward

Forwards

Medially


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Nerve SupplyIntercostal nerves (T7 -T11) &

Subcostal nerve (T12)


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External Oblique MuscleA triangular shaped defect in the external oblique

aponeurosis lies immediately above and medial to thepubic tubercle, known as superficial inguinal ring

Between the anterosuperior iliac spine and the pubictubercle, the lower border of the aponeurosis is foldedbackward on itself, forming the inguinal ligament


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Internal Oblique Muscle

Origin

Insertion

1. Anterior 2/3 of the intermediate line of the iliac crest2. The lateral 2/3 of the inguinal ligament

3. Lumbar fascia

1. Lower 6 costal cartilages

2. Xiphoid process

3. Linea Alba

4. Pubic crest


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Internal Oblique Muscle

Direction of fibersUpwards

Forwards

Medially

Nerve SupplyT7-T12

Iliohypogastric n.

Ilioinguinal n.


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Transversus Abdominis Muscle

Origin

1- Lower 6 intercostal cartilages

2- Lumbar Fascia

3- Ant. 2/3 of inner lip of iliac crest

4- Lat. 1/3 of inguinal ligament


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Transversus Abdominis Muscle

Insertion

1- Xiphoid Process

2- Pubic Crest

3- Linea Alba


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Direction of fibersTransversus Abdominis Muscle

Horizontally


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Nerve SupplyTransversus Abdominis Muscle

T7-T12

Iliohypogastric n.

Ilioinguinal n.


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The part of the fascia which lines the innersurface of the transverse abdominus muscle

is called the fascia tranversalis.


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The main arteries of the abdominal wall andpelvis lie deep to the fascia tranversalis,while

the main nerves are superficial to it


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Rectus Abdominis

Muscle

Origin

From the pubic crest

Insertion

7th, 6th, 5th costal cartilages

Xiphoid process


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Rectus Abdominis

Muscle

Surgical Importance

The muscle is divided into segments

by tendinous intersections, Which

indicate that the muscle arises from anumber of myotomes, fused together

1- Segmental nerve supply.

2- Hematoma of rectus m. is localized


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Pyramidalis Muscle

It is a landmark of linea

alba intraoperative


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Rectus Sheath Is a long fibrous sheath

Encloses the rectus abdominis and pyramidalis

muscle (if present)

Contains the anterior rami of lower six thoracicnerves and the superior and inferior epigastric

vessels and lymph vessels

Formed mainly by aponeurosis of three lateralabdominal muscles


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Medially

Laterally

Rectus Sheath

Linea Alba

Linea Semilunaris

Arcuate Line


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Rectus Sheath

Falciform Ligament

External Oblique

Internal Oblique

Transversus Abdominis

Ant. Layer of Rectus Sheath

Post. Layer of Rectus Sheath

Rectus Abdominis

Above Arcuate Line

SKIN

PeritoneumTransverslais Fascia


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Rectus Sheath

External Oblique

Internal Oblique

Transversus Abdominis

Ant. Layer of Rectus Sheath

Rectus Abdominis

Below Arcuate Line

Urachus in Median Umbilical Fold

Medial Umbilical Ligament

Transverslais Fascia

SKIN

Peritoneum


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It is formed by the fusion of the aponeurosisof the abdominal muscles and it separates

the left and right rectus abdominus muscles.


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Applied anatomy In multiparae the upper part of the linea alba becomes

streched out and weak,so that fingers can beinsinuated between the two recti.the condition

known as Divarication of recti.


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It is a curved tendinous line placed one oneither side of the rectus abdominus,extends

from the 9thrib to the pubic tubercle.


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Actions of Anterior Abdominal Wall Muscles

They assist in raising the intra abdominal pressure (so,they help in vomiting, cough, delivery, etc.)

Keep the abdominal viscera in position. Rectus abdominis flexes the trunk, while the 2 oblique

muscles bend the trunk laterally.

Act as accessory expiratory muscles.


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Superior epigastric a.

Subcostal a.

Inferior epigastric a.

Deep circumflex iliac a.

- I -

Internal Mammary a.

- III -External Iliac a.

- II -

Descending Aorta

10th, 11thintercostal a.


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Lymphatic DrainageAbove the umbilicus:

Drain into the axillary and sternal nodes.

Below the umbilicus:

Drain into the superficial inguinal nodes.


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Venous Drainage Superficial veins are paired with arteries.

Above the umbilicus:

Drain into the azygos venous system. Below the umbilicus:

Drain into the femoral system (via greatsaphenous).


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Caput Medusae

The superficial veins around the umbilicus and theparaumbilical veins connecting them to the portal

vein may become grossly distended in case of

portal vein obstruction

The distended subcutaneous veins radiate outfrom the umbilicus, producing in severe cases the

clinical picture called Caput Medusae


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INGUINAL CANAL


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Inguinal canals

why have them?Allow contents of the scrotum to communicate with

intra-abdominal contents

Prevent mobile intra-abdominal contents (e.g.intestine) from entering the scrotum and possiblybecoming damaged, while at the same time permittingblood vessels, nerves, lymphatics, vas deferens etc. tosupply the scrotal contents

58Dr C Slater, Department of Human Biology, University of Cape Town


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A Box?

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Floor

Imagine the right side inguinal canal viewed from the front as a

box with anterior &posterior walls, a roof & floor. The arrow

indicates that structures can run through it from lateral to medial

e.g. in males it transmits the spermatic cord, and in females,

the round ligament of the uterus.

Medial

Lateral


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Inguinal canal

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Floor

Medial

Here are the posterior wall, which has the DEEP inguinal

ring situated laterally, and the floor. (Roof and anterior wall

removed).

Deep inguinal ring

Lateral


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Inguinal canal

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Floor

Medial

Here are the anterior wall (which has the SUPERFICIAL

inguinal ring situated medially), and the roof.

Superficial inguinal ring

Lateral


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Inguinal canal

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FloorSpermatic cord

exits through

the superficial

inguinal ring

Medial

Spermatic cord enters theinguinal canal through the

deep inguinal ringDeep inguinal ring


Lateral


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Inguinal canal

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Medial


The anterior wall is made up of the external

obliquemuscle throughout, and is reinforced

by the

internal oblique m. laterally.Thetransversus abdominus m.lies even

more laterally as part of the anterior abdominal

wall.

Lateral


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Inguinal canal

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Floor

Spermatic cord

Medial

Lateral

The transversus abdominis and

internal oblique mm. combine to

form the CONJOINT tendon that

arches over the contents of the

inguinal canal

The conjoint tendon attaches to

the pubic crest, reinforces theposterior canal wall medially

and also forms the ROOF of

the canal

Conjoint tendon


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Posterior wall of the inguinal canal

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Deep inguinal ring

Medial

The posterior wall is formed by transversalis fascia

(orange) throughout and the conjoint tendon (red)

medially. The wall is particularly weak over the deep

inguinal ring

Lateral

Conjoint tendon mediallyPosterior wall


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Floor of the inguinal canal

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Floor

Medial

The floor is formed by an incurving of the inguinal ligament,

which is part of the external oblique muscle, forming a gutter.

(Medially it forms the lacunar ligament).

Lateral


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Roof and anterior wall of the

inguinal canal

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Medial

The anterior wall of the canal is formed by external oblique muscle

(orange) throughout and by internal oblique muscles

(red/black/white) laterally. This wall is weak medially because of

the hole in the external oblique muscle (= superficial inguinal ring).

Lateral


h l l


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Pressures on the inguinal canal

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Lateral

Medial

Deep inguinal ring intra abdominal

pressure

Spermatic cord


Conjoint tendon

= areas where reinforcement is present

Reinforcedanterior

wall by

internal

oblique m.

Reinforced

posterior wall

Pressure on

anterior wall


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Pressures in the inguinal canal

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Lateral

Deep inguinal ring intra abdominal

pressure


Conjoint tendon

Reinforced

anterior

wallReinforced

posterior wall

Weakness here

leads to direct

inguinal hernias

S.C.


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Deep Inguinal Ring inch above the ligament Midway between ASIS and the Symphysis

Lateralto the inferior epigastric vessels

Margins of ring give origin to the internal spermaticfascia


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Superficial Inguinal Ring Triangular defect in the aponeurosis of the externaloblique

Immediately above and medial to the pubictubercle

Margins give origin to the external spermatic fascia


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Mechanics of the inguinal CanalA potential weaknessA design to lessen weakness:

Oblique passageweakest areas lying some distanceapart

Anterior reinforcement by Int. oblique in front of deepring

Posterior reinforcement by Conjoint tendon behindsuperficial ring


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Mechanics of the inguinal Canal

Cont. On coughing/straining (defecation,parturition etc.) Int. oblique andtransversus abdominis muscles contract

f lattening the roof

canal isvirtually closed


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Inguinal hernias The posterior wall of the canal is particularly weaklaterally because of the deep inguinal ring

The anterior wall opposite the deep ring is reinforced

laterally by the internal oblique m.

A hernia (e.g. of small bowel) that comes through thedeep inguinal ring will have to travel along theinguinal canal as it cannot push into the reinforcedlayers of muscle in the anterior wall of the canaldirectly opposite the deep inguinal ring

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Inguinal hernias The anterior wall of the canal is weak medially wherethe superficial inguinal ring is situated

The posterior wall, opposite the superficial ring, is

reinforced medially by the conjoint tendon that isformed by fibres of the internal oblique andtransversus abdominis muscles

Abdominal contents cannot normally force themselvesthrough the superficial ring directly because of thereinforced posterior wall medially

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Indirect inguinal hernias Pass through the deep ring Travel along the canal

Exit the superficial ring above and medial to the pubictubercle .Since the incurved inguinal ligament formsthe floor of the canal, the contents of the canal couldnot emerge below or lateral to the public tubercle(useful in surgical diagnosis). An example is congenitalinguinal hernia.

Coverings of indirect hernias

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Coverings of indirect hernias Peritoneum Internal spermatic fascia

(from transversalis fascia)

Cremaster muscle & fascia(from transversus abdominis andinternal oblique mm.)

External spermatic fascia(from external oblique m.)

Superficial fascia

Skin

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Direct inguinal hernias If the posterior wall of the canal is weakened medially(e.g. by chronically increased intra-abdominalpressure), it can stretch and bulge out through the

superficial ring The contents of the hernia do not travel along the

length of the canal but push directly on the stretchedposterior inguinal canal wall and through the

superficial ring. Coverings of direct hernias

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Coverings of direct hernias Peritoneum Transversalis fascia

Conjoint tendon

External oblique aponeurosis

Superficial fascia

Skin

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Abdominal Quadrants Formed by two intersecting lines:Intersect at umbilicus.

Quadrants:

Upper left.

Upper right.

Lower left.

Lower right.


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Abdominal Regions

Divided into 9 regions by two pairs of planes:Vertical Planes:

Left and right lateral planes

= midclavicular planesHorizontal Planes:

Transpyloric plane:

Midway between jugular notch and

pubic symphysis (between xiphoid andumbilicus).

Intertubercular plane:

Through tubercles of iliac crests.


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Regions of the abdomen

R hypochondrial Epigastric L hypochondrial

R Lumbar Umbilical L Lumbar

R iliac Suprapubic/Hypogastric

L iliac


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Abdominal Regions Right and left hypochondriac:Contain liver

Epigastric:

Contains: liver, stomach, pancreas

Right and left lateral (lumbar):

Right contains ascending colon.

Left contains descending colon.


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Abdominal Regions Umbilical:Contains small intestine and transverse colon.

Right and left inguinal:

Right contains ileocecal junction and appendix.

Left contains sigmoid colon.

Hypogastric:

Contains small intestine, urinary bladder (full),pregnant uterus.


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Protuberance of the abdomen. The five common

causes (5F) Fat, Faeces, Fetus, Flatus And Fluid

Abdominal Hernias

Anteriolateral abdominal wall may be the site of

hernias Inguinal, umbilical and epigastric regions


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Common Sites

Inguinal HerniaUmbilical Hernia

Femoral Hernia Incisional Hernia

Less common Hernia Epigastric Hernia Recurrent Hernia


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Umbilical Hernia

Fascial defect at the umbilicus withperitoneal sac covered by skin

Paediatric umbilical hernias

Adult umbilical hernias


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Pediatric Umbilical Hernia Present in 10-30% of babies

80% close spontaneously by age 2

Indications for primary suture repair

Hernia present after ages 2-4

Large (5 cm) defect at age 1


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Adult Umbilical Hernia Increased intra-abdominal pressure Pregnancy

Obesity

Ascites

Differential diagnosis (rare)

Embryologic remnants

Metastatic cancer


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Adult Umbilical Hernia Symptoms relate to cosmesis, traction on the sac,

or trapped contents

Omentum

Small or transverse colon

Acute incarceration: reduction en masseproblematic


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Adult Umbilical Hernia Repair

Assess contents and manageappropriately based on viability

Open hernia repair

< 1 cm defect: primary suture repair > 1 cm defect: mesh repair lowers recurrence

Laparoscopic hernia repair: size of accessports often > hernia incision

Epigastric Hernia


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Epigastric Hernia

Fascial defect in supraumbilical linea alba Most < 1 cm

20% with multiple defects

Beware diastasis recti

Men: Women 2:1

Epigastric Hernia


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Epigastric Hernia

Contents Incarcerated preperitoneal fat or falciform ligament Peritoneal sac

Repair Open repair similar as for umbilical hernia Must palpate or visualize entire supraumbilical linea alba

Laparoscopic approach is suboptimal


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Spigelian Hernia

Defect through transversus abdominus andinternal oblique muscles

Occurs at junction of arcuate line and linea semilunaris Fascial defect 1-2 cm

Covered by external oblique aponeurosis

Spigelian Hernia


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Spigelian HerniaPresentation Lower abdominal swelling lateral to rectus

Focal discomfort/pain

May require imaging studies for diagnosis Ultrasound or CT

Repair: open or laparoscopic, on-lay mesh

I i i l H i


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Incisional Hernia

Bulge in region of scar from surgery orpenetrating trauma

Chronic wound failure Up to 20% of abdominal incisions

Subcutaneous sac may be more complex

Multi-loculated Contents adhesed within sac


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Incisional Hernia: Risk FactorsPrevious incisional hernia repair

Obesity

Smoking

Chronic lung disease

Diabetes

MalnutritionWound infection


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Incisional Hernia Repair

Fix conditions that promotedhernia occurrence

Open repair

Primary suture: < 52% recurrence Mesh: < 24% recurrence


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Common Clinical FeaturesThe features of all hernias are:

They occur at weak spotThey reduce on lying down or with direct

pressure

They have an expansile cough impulse


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ComplicationsUntreated hernia may develop following

complications:

a) intestinal obstructionb) strangulationc) incarceration


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ABDOMINAL WALL DEFECTS


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OmphaloceleMembrane sac arising from the umbilical cord

covers intestines

Outer membrane layer consists of amnion and

inner lining of peritoneum Size ranging from small->giant defects containing

liver, small and large bowel, stomach, spleen,ovaries, and testes

Associated with foreshortened bowel andmalrotation

Small abdominal cavity and pulmonary hypoplasia


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Gastroschisis No membrane coveringAbdominal wall defect typically 2-4cm diameter

Lateral to the right side of the umbilical cord Usually contains midgut and stomach

Thickened, atretic, and possibly ischemic bowel

Associated with malrotation


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ABDOMINAL WALL DEFECTSomphalocele gastroschisis

Membrane covered

1-15 cm defect size

Centre of the membrane Bowel-normal

Associated abnormalities-60%

Open defect

2-5 cm

Left of the defect Bowel-edematous,serositis

10%


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Anterior Abdominal Wall

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