Anterior Abdominal Wall – Structure And Anatomy

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ANTERIOR ABDOMINAL WALL

The anterior wall is firm but elastic and consists of 8 layers from

before backwards.

1.Skin

2.Superficial fascia

3.External oblique muscle and its aponeurosis

4.Internal oblique muscle and its aponeurosis

5.Transversus abdominis muscle and its aponeurosis

6. Fascia transversalis

7.Extra-peritoneal tissue and

8.Parietal peritoneum.

Opposite the linea alba, the layers are reduced to six in number.

Embryologically, the 7th layer of the extra-peritoneal tissue is important

because all abdominal visceras virtually lie in this layer; this fact is proved

by the coverings received by the testis during its descent.

DESCRIPTION OF DIFFERENT LAYERS

SKIN

It is thinner and more sensitive than the skin of the posterior

abdominal wall. The skin presents a number of cleavage lines (Langer’s

lines). The skin presents two parts, an outer epidermis which is non- vascular

and an inner dermis or corium which is highly vascular and presents rich

nerve supply.

The skin of the anterior abdominal wall consists of longitudinal

groove overlying the linea alba, and a curved groove on each side with the

convexity directed laterally which corresponds with the lateral border of the

rectus abdominis muscle. A surface depression, the umbilicus, affects the

median groove; It is composed of cicatritial tissue and represents remnant of

the foetal end of the umbilical cord.

SUPERIFICIAL FASCIA

Above a line joining the two anterior superior iliac spines it consists of

a single layer. Below that line it splits into superficial fatty layer (Camper’s

fascia) and deep membranous layer (Scarpa’s fascia).

SUPERFICIAL INGUINAL SPACE

It is a potential space in the anterior abdominal wall between the fascia

of Scarpa and the aponeurosis of external oblique.

EXTERNAL OBLIQUE MUSCLE

(OBLIQUUS EXTERNUS ABDOMINIS)

Origin

It arises by eight fleshy slips from the outer surfaces and lower borders

of the lower eight ribs.

Insertion

The most posterior fibres pass almost vertically downwards and are

inserted by fleshy fibres to the anterior half of the outer lip of the ventral

segment of the iliac crest. Its posterior margin is free and forms the anterior

boundary of the lumbar triangle.

The remaining fibres pass downwards, forwards and medially, and end

in a broad aponeurosis.

INGUINAL LIGAMENT (POUPART’S LIGAMENT)

It is the thickened lower border of the aponeurosis of the external

oblique which is folded backwards presenting a grooved upper surface. It

measures about 12 cm. to 14cm. in length in the adult.

INTERNAL OBLIQUE MUSCLE

(OBLIQUUS INTERNUS ABDOMINIS)

Origin

1. From the lateral two – third of the upper surface of the inguinal

ligament.

2. Anterior 2/3 of intermediate lip of the iliac crest.

3. Posterior layer of thoraco lumbar fascia.

Insertion

1.By forming conjoint tendon it is inserted into pubic crest and

pectineal line.

2.Forms rectus sheath and insert into the linea alba.

3. Lower 3 or 4 ribs.

Rectus abdominis

It is a long strap muscle, wider above than below.

Actions of the rectus muscles

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