4. Nine Regions of abdomen :
To describe location of viscera, abdomen is divided into 9
regions by 4 imaginary planes:
1. Transpyloric plane: tips of the ninth costal cartilages;
and the lower part of the body of the first lumbar
vertebra.
2. Transtubercular/Intertubercular plane: tubercles
of iliac crests (body of L5 vertebra).
3. Left and right midclavicular plane
11. Internal Oblique Muscle
• Origin: thoracolumbar fascia,
anterior two-thirds of iliac crest,
and lateral half of inguinal
ligament .
• Insertion: inferior borders of
last three ribs,as aponeurosis
to 7th,8th,9th costal cartilage
xiphoid process, linea alba,
pectineal line and the pubic
crest via the conjoint tendon.
• Nerve supply: lower 6 thoracic
nerves, 1stlumbar nerve.
• Direction : UFM
12. Transversus Abdominis
Origin: Internal surfaces of 7th
to 12thcostal cartilages,
thoracolumbar fascia, iliac crest,
and lateral third of inguinal
ligament. ( horizontally forward)
Insertion: as a broad aponeurosis
to Linea alba (with aponeurosis of
internal oblique), pubic crest, and
pecten pubis (via conjoint tendon).
Nerve supply: lower 6 thoracic
nerves, 1stlumbar nerve.
15. Comparison of upper and lower three-fourths of
anterior abdominal wall
Upper Midline Lower Midline
Linea alba well developed Linea alba poorly developed
Right and left recti well separated Right and left recti close together
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 well developed
25. INGUINAL REGION
An area of weakness in
anterior abdominal wall
because of prenatal
penetration of the wall by
testis and spermatic cord
26. • Suprolateral: inferior
epigastric vessels
• Medial:lateral margin of
the rectus muscle
• Inferior: inguinal
ligament/Poupart's
ligament
• Clinical significance
– Direct inguinal
hernias leave the
abdomen through this
triangle.
Inguinal (Hesselbach's) triangle
27. Inguinal canal
Deep Inguinal Ring: Oval
transversalis fascia.
Superficial Inguinal Ring:
Triangular, aponeurosis of
EOM.
Boundaries
28.
29. CONTENTS
Spermatic cord , round ligament
Ilioinguinal nerve.
Contents of spermatic cord:
1. Vas deferens.
2. Testicular artery, cremasteric
artery, artery of ductus
deferens.
3. Pampiniform plexus of vein.
4. Genital branch of
genitofemoral nerve,
plexus of sympathetic
nerves around artery of
ductus deferens.
5. Testicular lymph vessel.
6. Remains of processus
vaginalis.
30. CLINICAL IMPORTANCE
Indirect inguinal hernia: loop of intestine passes through deep
ring, inguinal canal, superficial inguinal ring, into scrotum.
Intestine is lateral to inferior epigastric artery.
Direct inguinal hernia: loop of intestine passes through
hassalbachs triangle.
Descent of testis: before birth, testis descends from abdomen to
scrotum via inguinal canal.
31. Mechanism of inguinal canal
This weakness is compensated by the following factors:
1. Obliquity of the inguinal canal: 2 inguinal rings do not lie opposite
, intra-abdominal pressure rises,walls approximated, thus
obliterating the passage. Flap valve mechanism.
2. Superficial inguinal ring is guarded from behind by conjoint
tendon and reflected part of inguinal ligament.
3. Deep inguinal ring is guarded from front by fleshy fibres of
internal oblique.
4. Shutter mechanism of internal oblique
