Anatomy
Abdomen
The lesser omentum extends between which of the following structures:
Answer:
The lesser omentum is considerably smaller and extends from the lesser curvature of the stomach and the first part of the duodenum to the inferior surface of the liver.Greater and Lesser Omentum
Anatomy / Abdomen / Topography of Abdominal Cavity
Last Updated: 11th April 2019
The omenta are double layers of peritoneum that extends from the stomach and proximal part of the duodenum to other organs.
Table: Anatomical Overview of the Abdominal Cavity
| Structure | Key anatomy |
|---|---|
| Peritoneal cavity | Divided into greater and lesser sacs |
| Greater sac | Divided into supracolic and infracolic compartments by transverse mesocolon, compartments connected by paracolic gutters |
| Supracolic compartment | Contains stomach, liver and spleen, lies under cover of costal limits of thoracic cage |
| Infracolic compartment | Divided into left and right parts by oblique attachment of mesentery, contains small intestine and ascending/descending colon, continuous with pelvic cavity |
| Lesser sac (omental bursa | Lies posterior to stomach and liver and anterior to pancreas, continuous with greater sac through epiploic foramen |
| Greater omentum | Descends from greater curvature of stomach and first part of duodenum, drapes inferiorly over transverse colon, jejunum and ileum, folds back up and ascends to adhere to transverse colon/mesocolon before arriving at posterior abdominal wall |
| Lesser omentum | Extends from lesser curvature of stomach and first part of duodenum to inferior surface of liver |
| Mesentery | Connects jejunum and ileus to posterior abdominal wall, attaches superiorly to duodenojejunal junction and passes oblique downwards and to the right to end at ileocecal junction |
| Transverse mesocolon | Connects transverse colon to posterior abdominal wall, leaves posterior abdominal wall across anterior surface of head and body of pancreas and passes outwards to surround transverse colon |
| Sigmoid mesocolon | Connects sigmoid colon to abdominal wall, V-shaped fold with apex near division of left common iliac artery, left limb descending along medial border of left psoas major muscle and right limb descending into pelvis to end at vertebral level S3 |
Greater Omentum
The greater omentum descends from the greater curvature of the stomach and first part of the duodenum, drapes inferiorly over the transverse colon and the coils of the jejunum and ileum, then folds back up posteriorly and ascends to become adherent to the peritoneum on the superior surface of the transverse colon and the anterior layer of the transverse mesocolon before arriving at the posterior abdominal wall.
The greater omentum is often referred to as the 'policeman of the abdomen' because of its apparent ability to migrate to any inflamed area and wrap itself around the organ to wall off inflammation. The greater omentum is also an important site for metastatic tumour spread; direct omental spread by a transcoelomic route is common for carcinoma of the ovary.
Lesser Omentum
The lesser omentum is considerably smaller and extends from the lesser curvature of the stomach and the first part of the duodenum to the inferior surface of the liver.
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/02/Peritoneum-1.png)
Peritoneal Cavity. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
