Anatomy
Abdomen
A 29 year old rugby player presents to ED complaining of left flank pain. Imaging shows a fracture of the angle of the twelfth rib on the left side. Which of the following organs, based on surface anatomy, is most at risk for injury:
Answer:
The kidneys lies retroperitoneally on the posterior abdominal wall, one on each side of the vertebral column at the level of the T12 - L3 vertebrae, the left kidney reaching as high as the eleventh rib posteriorly. The spleen superior to the kidneys and adjacent to ribs 9 to 11. The liver is located primarily on the right side of the body and lies around the level of the fifth to tenth ribs. The pancreas is predominantly located in the midline, more medial the kidneys, at the level of the eleventh to twelfth ribs.Kidney
Anatomy / Abdomen / Urinary Tract
Last Updated: 11th April 2019
The kidneys are retroperitoneal organs. They lie in the extraperitoneal connective tissue immediately lateral to the vertebral column in the upper left and right abdominal quadrants.
Table: Anatomical Overview of the Kidneys
| Viscera | Kidney |
|---|---|
| Surface marking | Extend between vertebrae T12 – L3, left kidney slightly higher than right, renal hila at vertebral level L1 |
| Anterior relations | RIGHT: right adrenal gland, liver, second part of duodenum, right colic flexure, segment of small intestine. LEFT: left adrenal gland, spleen, pancreas, stomach, left colic flexure and descending colon, duodenojejunal flexure and coils of small intestine |
| Posterior relations | Diaphragm, psoas major, quadratus lumborum and transversus abdominis muscles |
| Structure | Each kidney covered by fibrous capsule and surrounded by renal fascia, kidney itself made up of outer renal cortex and inner renal medulla, renal pelvis continuous with ureters |
| Blood supply | Renal artery (branch of abdominal aorta arising at vertebral level L1/L2 posterior to the pancreas), divides into segmental arteries to supply renal parenchyma |
| Lymphatics | Lumbar (para-aortic) lymph nodes |
| Innervation | Via renal plexus, parasympathetic fibres from vagus nerve and sympathetic fibres from thoracic splanchnic nerves |
Surface Markings
The position of the kidneys varies with respiration and the position of the body. In the supine position, the kidneys extend from approximately vertebra T12 superiorly to vertebra L3 inferiorly. The left kidney is a little higher than the right, reaching as high as rib 11, compared to rib 12 for the right kidney (because of its relationship with the liver). The hila of the kidneys and the beginning of the ureters are at the level of the L1 vertebra.
Surface Markings of the Kidneys (Anterior View). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/02/Surface-kidney.png)
Surface Markings of the Kidneys (Posterior View). (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Relations
The anterior surface of the right kidney is related to the (superiorly to inferiorly):
- right adrenal gland medially
- liver
- second part of the duodenum medially,
- right colic flexure laterally
- a segment of small intestine medially.
The anterior surface of the left kidney is related to the (superiorly to inferiorly):
- left adrenal gland medially
- spleen laterally
- pancreas
- stomach (the kidney forms part of the stomach bed)
- left colic flexure and descending colon laterally
- duodenojejunal flexure and coils of small intestine
Posteriorly both kidneys are related superiorly to the diaphragm and ribs and inferiorly (moving from medial to lateral) the psoas major, quadratus lumborum and transversus abdominis muscles. The pleural sacs and the costodiaphragmatic recesses also extend posterior to the kidneys.
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/02/Kidneys2.jpg)
Relations of the Kidneys. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Functional Anatomy
Each kidney consists of an outer renal cortex and an inner renal medulla.
Extensions of the renal cortex (the renal columns) project into the inner aspect of the kidney, dividing the renal medulla into the renal pyramids. The base of the renal pyramids are directed outwards towards the renal cortex, while the apex of each renal pyramid projects inwards towards the renal sinus, a cavity which is occupied by the renal calyces, blood vessels, nerves and fat.
The apical projection of the renal pyramid is surrounded by a minor calyx into which the collecting ducts drain. Several minor calyces unite to form a major calyx, and two or three major calyces unite to form the renal pelvis, which is continuous with the ureter.
Functional Anatomy of the Kidney. (Image by OpenStax College [CC BY 3.0 , via Wikimedia Commons)
Renal Fascia
Each kidney is covered by a firm fibrous capsule and surrounded by the renal fascia. The attachments of the renal fascia determine the path of extension of a perinephric abscess. Fascia at the renal hilum attaches the renal vessels and ureter, usually preventing the spread of pus to the contralateral side. However pus from an abscess may force its way into the pelvis between the loosely attached anterior and posterior layers of the renal fascia.
Blood Supply
The renal artery arises from the abdominal aorta just inferior to the origin of the superior mesenteric artery just between vertebrae L1 and L2 and posterior to the pancreas. Each renal artery enters the kidney via the renal hilum, dividing into segmental branches. These branches undergo further divisions to supply the renal parenchyma.
Lymphatic Drainage
The lymphatic drainage is to the lumbar (para-aortic) lymph nodes located at the origin of the renal arteries.
Innervation
The kidneys receive autonomic nerve fibres via the renal plexus which contains parasympathetic fibres from the vagus nerve and sympathetic fibres from the thoracic splanchnic nerves.
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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 |
