Anterior Abdominal Wall

ANTERIOR ABDOMINAL WALL

• Divided into 9 regions with the help of 2 vertical & 2 horizontal planes.

Horizontal planes include:

1. Transpyloric plane (of Adison):

• Lies midway b/w the suprasternal notch & pubic symphysis.
• It passes anteriorly through tips of 9th costal cartilage & posteriorly through lower border of L1 vertebra.
• Organs present at this level are:

1. hilum of kidney
2. pylorus of stomach
3. beginning of duodenum
4. neck of pancreas
5. fundus of gall bladder & origin of SMA.

2. Transtubercular plane: connects the tubercles of iliac crests & pass through upper borddeer of L5 vertebra.

Vertical planes:

• The two vertical planes are right & left lateral planesthrough midinguinal point (also c/d as midingunal plane or midclavicular plane).
• The nine regions from above downwards are-

1. In middle: Epigastrium, umbilical, hypogastrium
2. On right side: Right hypochondrium, right lumbar, & right inguinal (iliac) regions.
3. Left side: Left hypochondrium, left lumbar & left inguinal (iliac) regions.

IMPORTANT LANDMARKS

• Xiphoid process lies at the level of T9 vertebra.

• Pubic symphysis lies at the level of coccyx.
• Line joining the xiphoid process & pubic symphysis isanterior median plane.
• Costal margins are formed by 7th, 8th, 9th & 10th costal cartilage.                               
• The transverse plane passing through lowest part of costal margin (10th costal cartilage in midmaxillary line) is called Subcostal plane, which pass through L3 vertebra.
• Highest point of iliac crest lies at L4 vertebra .
• The supracristal plane is indicated by a horizontal line through the highest points of iliac crests.
• Umbilicus lies b/w L3 and L4 vertebrae.
• The angle b/w the last rib & outer border of erector spinae is known as renal angle.

NERVE SUPPLY

• The skin of anterior abdominal wall is innervated by ventral rami of T7 to T12 spinal nerves (lower 5 intercostal & subcostal nerve) & ventral rami of L1 (iliohypogastric nerves).
• Lateral cutaneous branches of T7-T11 supply lateral part of skin of anterior abdominal wall.
• The dermatomal pattern is arranged in serial order:

1. T7 near xiphoid process (epigastric pit)
2. T10 at umbilicus level the iliohypogastric (L1) 2.5 cm above the superficial ring & others at proportionate distance b/w them.

SUPERFICIAL LYMPHATICS

• The umbilicus is a watershed, above the level of umbilicus lymph flows upwards to drain into axillary lymph nodes.
• Below the level of umblicus lymph flows downwards to drain into superficial inguinal lymph nodes.