9 Regions of Abdomen

       

-Key contents

1. Introduction to abdomen
2. Layers of the abdomen wall

• Skin
• Superficial fascia 
• Muscles
• Actions of muscles

1. Nerve supply of abdomen
2. Abdominal cavity
3. Nine regions of the abdomen 

 Introduction to the abdomen-

• The abdomen lies below the diaphragm and is the lowest part of the trunk.
• The abdomen is surrounded by various muscles, which can easily adjust themselves according to changes in the capacity of the abdominal cavity. Forex- They can thin out to contain bulge of the abdomen imposed by gas, fat, fetus, and fluid.
• The abdomen contains various parts of the digestive and urogenital systems.
• It contains the suprarenal glands and numerous lymph nerves. 
• Layers of the abdominal wall-

1. Skin
2. Superficial fascia 
3. Muscles 
4. Actions of muscles 
   

 

 Layers of the abdomen-    

• Skin – The skin of the anterior abdominal wall is efficient for immense stretching. Forex- during pregnancy, obesity, ascites (accumulation of fluid), intra-abdominal tumors.

 

NOTE- Excessive stretching may result in the formation of frosted bands on the lower part of the anterior abdominal wall; these are known as lineae Albicans.

• Superficial Fascia- 

1. Beneath the umbilicus level (a scar in the anterior abdominal wall formed by a shred of the root of the umbilical cord), the superficial fascia of the anterior abdominal wall is divided into two layers-

• Superficial fatty layer (fascia of Camper)
• Deep membranous layer (fascia of Scarpa)

 

      2.The fascia contains-fat, cutaneous nerves, cutaneous vessels, superficial lymphatics.

 

• Muscles of the abdomen –

1. External oblique muscles
   
2. Internal oblique muscles 
   
3. Transversus abdominis muscles
   
    
4.  Rectus abdominis muscles 
   
5. Pyramidalis 

 

• Actions of muscles-

 

1. Support for abdominal viscera- abdominal muscles provide elastic support for abdominal viscera against gravity.
2. Explosive acts- oblique muscle can compress the abdominal viscera and lead to micturition, defaecation, parturition, vomiting, etc.
3. Forceful expiratory acts-the external oblique can compress and depress the lower part of the thorax and lead to forceful expiration i.e coughing, sneezing, blowing, shouting, etc.
4. Movements of the trunk- flexion, lateral flexion, rotation.

Nerve supply-

1. Lower six thoracic nerves (T7-T12)-External Oblique Muscles 
   
2. Lower six thoracic nerves and the first lumbar nerve (T7-L1)-Internal Oblique muscles 
3. Lower six thoracic nerves and the first lumbar nerve (T7-L1)-Transversus Abdominis Muscle
4. Lower six or seven thoracic nerves (T7-T12)-Rectus Abdominis Muscles
   
5. Subcostal nerve(T12)-Pyramidalis

Abdominal cavity- 

1. It is the largest cavity.
2. The abdomen cavity contains very lengthy organs.
3. It encloses the peritoneal cavity between its parietal and visceral layers.
4. The peritoneum is a protective layer that supports the abdominal viscera and stores fat.

 

 

Nine regions of the abdomen-

1. Right hypochondrium 
2. Left hypochondrium
3. Epigastric region
4. Right lumbar region
5. Left lumbar region
6. Umbilical region
7. Right iliac fossa 
8. Left iliac fossa 
9. Hypogastric region
   

Main contents of these nine regions-

1. Right hypochondrium- liver, gallbladder.
2. Left hypochondrium- stomach, spleen, left colic flexure.
3. Epigastric region- stomach, duodenum, pancreas.
4. Right lumbar- right kidney and ureter, ascending colon.
5. Left lumbar- left kidney and ureter, descending colon.
6. Umbilical region- aorta, inferior vena cava, coils of the small intestine, stomach.
7. Right iliac fossa- caecum, vermiform appendix.
8. Left iliac fossa- sigmoid colon.
9. Hypogastric region- urinary bladder, coils of the small intestine, enlarged uterus.

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