Dr. Nabil Khouri MD. Ph.D

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The abdomen is the region of the body that is located between the

diaphragm above and the pelvic inlet below.

Dermatoms

s

Abdominal regions. The abdomen can be divided to 9 regions by four imaginary lines.

The Rt. And Lt. vertical lines extending from the midclavicular point superiorly to midinguinal point inferiorly.

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Two transverse lines

1. The lower plain INTERTUBERCULAR plain extends between the Rt. And Lt. iliac tubercles

2. The upper subcostal plain extends between the lowest point of the costal edge.

Or TRANSPYLORIC plane that pass through L1 or the midway between the jugular notch and the pubic symphysis.

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And Deep fascia

Skin

Superficial fascia. 1. Superficial fatty layer (CAMPER’S FASCIA).

It’s continuous with superficial fat over the rest of the body.

In the scrotum is modified as a thin smooth muscular layer called DARTOS MUSCLE.

2. Deep membranous layer.(SCARPA’S FASCIA).

Its thin and fades out superiorly and laterally where it becomes continuous with the superficial fascia of the back and the thorax.

Inferiorly passes on to the front of the thigh and fuses with the deep fascia of the thigh about 2.5 cm bellow the inguinal ligament.

In the midline inferiorly. It form a tubular sheath for the penis (or clitoris) so it doesn’t attach to the pubis.

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Bellow the perineum

Inters the wall of the

scrotum. From here it

passes to be attached on

each side to the pubic arch

and there its referred as

COLLES FASCIA.

The Deep fascia.

Is a thin layer of

connective tissue covering

the muscles, it lies

immediately deep to the

membranous layer of

superficial fascia.

Muscles of the anterior abdominal wall.

It connects the thoracic cage to the hip bones as a

three large flat sheets and a wide vertical

muscle.

1. External oblique.

2. Internal oblique.

3. Transversus abdominal.

4. Rectus abdominis.

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External Oblique

The external oblique muscle is

a broad, thin, muscular sheet

that ARISES from the outer

surfaces of the lower eight ribs

and

fans out to be INSERTED into

1. The xiphoid process.

2. The linea alba.

3. The pubic crest.

4. The pubic tubercle.

5. The anterior half of the iliac

crest.

6. Forms the inguinal ligament

by its folding

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Internal Oblique lies deep to the external oblique; most of

its fibers run at right angles to those of

the external oblique.

It arises from

1. The lumbar fascia,

2. The anterior two thirds of the iliac

crest,

3. The lateral two thirds of the inguinal

ligament.

The muscle fibers radiate as they pass

upward and forward.

It inserts into

1. The lower borders of the lower three

ribs and their costal cartilages.

2. The xiphoid process.

3. The linea alba.

4. The symphysis pubis.

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The Transversus muscle is a thin sheet of muscle that

lies deep to the internal

oblique, and its fibers run

horizontally forward

It arises from the

1. Deep surface of the lower

six costal cartilages and

margins

2. The lumbar fascia (posterior

aponeurosis)

3. The anterior two thirds of

the iliac crest,

4. The lateral third of the

inguinal ligament.

Rectus Abdominis The rectus abdominis is a long strap muscle that extends along the

whole length of the anterior abdominal wall.

It is broader above and lies close to the midline, being separated

from its fellow by the linea alba.

It arises by two heads

1. from the front of the symphysis pubis.

2. from the pubic crest.

It inserts

1. into the fifth, sixth, and seventh costal cartilages and

2. the xiphoid process .

When it contracts, its lateral margin forms a curved ridge that can

be palpated and often seen and is termed the LINEA

SEMILUNARIS, this extends from the tip of the ninth costal

cartilage to the pubic tubercle.

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The rectus abdominis

muscle is divided

into distinct

segments by three

transverse tendinous

intersections: at the

level of the

1. xiphoid process.

2. umbilicus.

3. halfway between

these two.

These intersections are

strongly attached to

the anterior wall of

the rectus sheath.

Pyramidalis The pyramidalis muscle

is often absent.

It arises by its base from

the anterior surface of

the pubis.

it inserts into the linea

alba. It lies in front of the

lower part of the rectus

abdominis.

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NOT:

The posterior border of the external oblique muscle is free,

whereas the posterior borders of the internal oblique and

transversus muscles are attached to the lumbar vertebrae by

the lumbar fascia

1. Above the costal margin, the anterior wall is formed by the aponeurosis of the external oblique. The posterior

wall is formed by the thoracic wall—that is, the fifth, sixth, and seventh costal cartilages and the intercostal spaces.

2. Between the costal margin and the level of the anterior

superior iliac spine, the aponeurosis of the internal oblique splits to enclose the rectus muscle; the external oblique aponeurosis is directed in front of the muscle, and the transversus aponeurosis is directed behind the muscle.

3. Between the level of the anterosuperior iliac spine and the pubis, the aponeuroses of all three muscles form the

anterior wall. The posterior wall is absent, and the rectus muscle lies in contact with the fascia transversalis.

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At the site where the aponeuroses forming the

posterior wall pass in front of the rectus at the

level of the anterior superior iliac spine, the

posterior wall has a free, curved lower border

called the arcuate line

At this site, the inferior epigastric vessels enter

the rectus sheath and pass upward to

anastomose with the superior epigastric

vessels.

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The rectus abdominis is enclosed between the aponeuroses of the

external oblique, internal oblique, and transversus muscles

which form the rectus sheath

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Rectus Sheath The rectus sheath is a long fibrous sheath that encloses the rectus

abdominis muscle and pyramidalis muscle (if present)

and contains

1. rectus abdominis muscle and pyramidalis muscle (if present)

2. the anterior rami of the lower six thoracic nerves and

3. the superior and inferior epigastric vessels

4. and lymph vessels.

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Between the anterior superior iliac spine and the pubic

tubercle, the lower border of the external oblique muscle

aponeurosis is folded backward on itself, forming the

inguinal legament Inguinal ligament.

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It extend from the ASIP to the symphesis pubis to from the medial end

of the ligament, the lacunar ligament that extends backward and

upward into the pectineal line on the superior ramus of the pubis

The inferior rounded border of the inguinal ligament is attached the

deep fascia of the thigh, the FASCIA LATA

The lateral part of the posterior edge of the INGUINAL

LIGAMENT gives origin to:

1. Part of the internal oblique

2. The transversus abdominis muscles.

Its sharp, free crescentic edge forms the medial margin of the

FEMORAL RING

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The internal oblique has a

lower free border that arches

over the spermatic cord (or

round ligament of the uterus)

and then descends behind it

to be attached to the pubic

crest and the pectineal line.

Near their insertion, the

lowest tendinous fibers are

joined by similar fibers from

the transversus abdominis to

form the conjoint tendon.

The conjoint tendon is

attached medially to the

linea alba.

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Conjoint tendon

Superficial inguinal ring is a triangular-shaped defect in the

external oblique aponeurosis lies immediately above and medial to

the pubic tubercle.

Its margins are referred as crura. At and beyond the apex of the

triangle 2 crura are united by intercrural fibers

The spermatic cord (or round ligament of the uterus) passes

through this opening and carries the external spermatic fascia (or

the external covering of the round ligament of the uterus) from the

margins of the ring

As the spermatic cord (or round ligament of the uterus) passes

under the lower border of the internal oblique, it carries with it

some of the muscle fibers that are called the

Cremaster muscle (fibers).

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Floor

Lateral Medial

Here are the anterior wall (which has the SUPERFICIAL inguinal ring situated medially), and the roof.

Superficial inguinal ring

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Deep inguinal

ring

An oval opening in

the fascia

transversalis

situated 1.2 cm

above the

midinguinal point,

and immediately

lateral to the stem

of the inferior

epigastric artery

Deep inguinal ring

Floor

Medial

Inguinal Canal

Location

Inferior part of the

anterolateral abdominal wall

It is about 4cm(1.5 inches)

long, and is directed

downwards, forwards and

medially

The inguinal canal extends

from the deep inguinal ring to

the superficial inguinal ring

Floor

Lateral

The posterior wall is formed by transversalis fascia (orange)

throughout and the conjoint tendon mdially. The wall is particularly

weak over the deep inguinal ring

1.In its whole extent

a. The fascia transversalis

b. The extra peritoneal tissue

c. The parietal peritoneum.

2.In its medial two-thirds a. The conjoint tendon b. At its medial end by the

reflected part of the inguinal ligament.

THE ANTERIOR WALL

1.In its whole extent

a. Skin

b. Superficial fascia

c. External oblique aponeurosis

2.In its lateral one-third

The fleshy fibres of the internal oblique muscle.

The ROOF : It is formed by the arched fibres of the internal oblique and

transverse abdominis muscles.

Deep inguinal ring

Medial

Lateral

Conjoint tendon medially Posterior wall

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Content

Nerve Supply of Anterior Abdominal Wall Muscles

The oblique and transversus abdominis muscles are supplied by the

lower six thoracic nerves and the iliohypogastric and ilioinguinal nerves

(L1).

The rectus muscle is supplied by the lower six thoracic nerves.

The pyramidalis is supplied by the 12th thoracic nerve.

The nerves of the anterior abdominal wall are the anterior rami of the

lower six thoracic and the first lumbar nerves.

The thoracic nerves are the lower five intercostal nerves and the

subcostal nerves and the first lumbar nerve is represented by the

iliohypogastric and ilioinguinal nerves, branches of the lumbar plexus.

They supply the skin of the anterior abdominal wall, the muscles, and

the parietal peritoneum.

The lower six thoracic nerves pierce the posterior wall of the rectus

sheath to supply the rectus muscle and the pyramidalis (T12 only).

They terminate by piercing the anterior wall of the sheath and

supplying the skin.

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The first lumbar nerve has a similar course,

but it does not enter the rectus sheath.

It is represented by the iliohypogastric nerve,

which pierces the external oblique aponeurosis

above the superficial inguinal ring,

and by the ilioinguinal nerve, which emerges

through the ring.

They end by supplying the skin just above the

inguinal ligament and symphysis pubis.

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