Anatomy
Thorax
A 28 year old man is brought to ED with a penetrating chest wall injury in the area of the fourth costal cartilage. Which of the following pulmonary structures is present at this site:
Answer:
The horizontal fissure (separating the right superior and middle lobes) extends medially from the oblique fissure at the level of the 5th rib in the midaxillary line to the sternum, along the lower border of the fourth rib.Lung Surface Anatomy
Anatomy / Thorax / Pleura and Lungs
Last Updated: 25th April 2020
The lungs lie on either side of the mediastinum, each surrounded by a pleural cavity. The right lung is normally a little larger than the left lung because the middle mediastinum, containing the heart, bulges more to the left than to the right.
Lobes and Fissures
The right lung has three lobes and two fissures; the oblique fissure separates the inferior lobe from the superior and middle lobe whilst the horizontal fissure separates the superior lobe from the middle lobe.
The left lung has two lobes separated by the oblique fissure.
The oblique fissure may be an evolutionary development to permit greater transmission of diaphragmatic excursions to the superior lobe. In this way the upper lobe can expand to a relatively greater extent for a given increase in the superoinferior diameter of the pleural cavity.
Surface Markings
The inferior margin of the lung in quiet respiration is a line that runs between rib 6 in the midclavicular line, rib 8 in the midaxillary line and vertebra T10 posteriorly.
In quiet respiration, the approximate position of the right oblique fissure can be marked by a line on the thoracic wall that begins at the spinous process of vertebra T4, crosses the fifth intercostal space laterally and then follows the contour of rib 6 anteriorly. The horizontal fissure follows the fourth intercostal space from the sternum until it meets the oblique fissure as it crosses rib 5.
The oblique fissure in the left lung is slightly more oblique than the corresponding fissure in the right lung. In quiet respiration, the approximate position of the oblique fissure can be marked by a line on the thoracic wall that begins between the spinous processes of vertebrae T3 and T4, crosses the fifth intercostal space laterally and then follows the contour of rib 6 anteriorly.
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/Lung-pleura2.png)
Surface Markings of the Lungs. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Auscultation
Visualisation of the lungs from the surface is of utmost importance for auscultation:
- Anteriorly:
- The right side of chest mostly presents upper and middle lobes divided by the horizontal fissure at about the 5th rib in the midaxillary line to 4th rib in the sternum.
- The left side of chest mainly presents upper lobe, that is divided from the lower lobe by oblique fissure going from the 5th rib in the midaxillary line to the 6th rib at the midclavicular line.
- Posteriorly
- With the exception of apices, the posterior aspect of chest on each side mainly presents lower lobe stretching from spinous process C7 to T10.
- Right lateral
- The lung is located deep to the area going from axilla to the level of the 7th or 8th rib. The upper lobe is demarcated in the level of the 5th rib in the midaxillary line and 6th rib in the midclavicular line.
- Left lateral
- The lung is located deep to the area going from axilla to the 7th or 8th rib. The upper lobe is demarcated in the level of the 5th rib in the midaxillary line and 6th rib in the midclavicular line.
Key Points:
- The superior lobe of the right lung is perceptible above the 4th rib anteriorly.
- The middle lobe of the right lung is perceptible between the 4th and the 6th rib anteriorly.
- The superior lobe of the left lung is perceptible above the 6th rib anteriorly.
- The inferior lobes of the left and right lungs are best examined on the back, notably in the region of the triangle of auscultation formed by the lateral border of trapezius muscle, medial border of scapula, and upper border of latissimus dorsi (because this area is free of intervening muscle masses, respiratory sounds can be easily detected)
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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 |
