ANATOMY OF THE ABDOMEN

DEFINITION OF ABDOMEN

• A region of the body bounded by

the following regions:-

– Superiorly – thorax

– Inferiorly – pelvis/perineum

– Posteroinferiorly – back

– Inferolaterally – lower limbs

BONY LANDMARKS OF THE ABDOMEN

• Xiphoid process

• Costal margin – 7th – 11th costal

cartilages

• Pelvic bones

• L1 – L5 Lumbar vertebrae

• occupied by organs of the digestive, urogenital, endocrine &

vascular structures.

CONTENTS OF THE ABDOMINAL CAVITY

REGIONS OF THE ABDOMEN

4 planes divide the abdominal

cavity into 9 regions

2 vertical (midclavicular),

midclavicular to midinguinal

2 transverse – ( subcostal &

transtubercular)

Subcostal – pass through

10th costal cartilage

Transtubercular – pass

through iliac tubercle

ANTEROLATERAL ABDOMINAL WALL

• Anterior & lateral walls

extending from the thorax to

pelvis

• Consists of the

– (1) Skin

– (2) Fascia -

Subcutaneous & deep

– (3) Muscles

– (4) Transversalis fascia

– (5) Extraperitoenal fat

– (6) Peritoneum

MUSCLES OF THE ANTEROLATERAL ABDOMINAL WALL

• 5 pairs of muscles bilaterally – 3

flat, 2 vertical

• (1) External oblique

• (2) Internal oblique

• (3) Transversus abdominis

• (4) Rectus abdominis

• (5) Pyramidalis

EXTERNAL OBLIQUE MUSCLE

• O: external surfaces of 5th – 12th ribs

• I: linea alba, pubic tubercle, ant ½ of iliac crest

• N: thoracoabdominal nerves (T7-T11 spinal nerves), subcostal nerve.

• A: compresses the abdomen to provide support for abdominal organs.

INTERNAL OBLIQUE MUSCLE

• O: thoracolumbar fascia, ant 2/3 of iliac crest, lat 1/3 of inguinal ligament.

• I: inferior borders of 10th – 12th ribs, linea alba, pecten pubis, conjoint tendon.

• N: thoracoabdominal nerves (T6-T12 spinal nerves), L1 nerve

• A: compresses and supports abdominal viscera

TRANSVERSUS ABDOMINIS MUSCLE

• O: thoracolumbar fascia, internal surfaces of 7th-12th costal cartilages, iliac crest,

lat 1/3 of inguinal ligament.

• I: linea alba, pubic crest, pecten pubis, conjoint tendon.

• N: thoracoabdominal nerves (T6-T12 anterior rami of spinal nerves), L1 nerve

• A: compresses and supports abdominal viscera

RECTUS SHEATH

• A strong incomplete fibrous

compartment

• Formed by decussation and

interweaving of the flat

abdominal muscles.

• Internal oblique

aponeurosis splits into two

layers: anterior & posterior and invest the rectus

abdominis muscle.

RECTUS SHEATH

• Anterior wall – external oblique,

anterior layer of internal oblique

• Posterior wall – transversus

abdominis and posterior layer of

internal oblique.

• All aponeuroses fuse in the

midline – linea alba.

• In the midline, it contains the

umbilical ring. A defect where

fetal umbilical vessels pass to

the placenta.

• Splitting of internal oblique,

lateral to rectus abdominis –

semilunar line.

NERVES OF THE ANTEROLATERAL ABDOMINAL WALL

• (1) thoracoabdominal

nerves (T7 – T11)

• (2) Subcostal nerve

(anterior ramus of T12)

• (3) Iliohypogastric

• (4) Ilioinguinal

VESSELS OF THE ANTEROLATERAL ABDOMINAL WALL

• (1) superior epigastric artery

• (2) musculophrenic artery

• (3) 10th & 11th post intercostal

arteries

• (4) subcostal artery

• (5) inferior epigastric

• (6) deep circumflex iliac

• (7) superficial circumflex iliac

• (8) superficial epigastric

VEINS & LYMPHATICS OF THE ANTEROLATERAL ABDOMINAL WALL

• (1) Subcutaneous venous plexus

• (2) Paraumbilical veins

• (3) Lateral thoracic vein

• (4) Superficial epigastric veins

• (5) superficial circumflex iliac

• (6) superior & inferior epigastric

• (7) deep circumflex iliac

• (8) posterior interocstal (11th) &

subcostal veins

•Thank you