Cow lungs are the pair of main organs of the respiratory system. Here, I will describe the anatomy of cow lungs using hand-drawn diagrams and real images.
Quick answer: Cow lungs anatomy describes their surfaces, borders, base, and apex, along with the various lobes.
I got several questions about variations in the lobes between the right and left lungs during my classes over the last few years. Thus, I will help you understand the variations between the two lungs and their various impressions.
Where are the lungs located on a cow?
Figure 1 presents the hand-drawing schematic presentation of the location of the cow’s lungs. It shows the cow’s larger right and smaller left lungs occupy most of its thoracic cavity.
However, the topographic and surface anatomy of the cow’s lungs express their exact location within the thoracic cavity. Here, Figure 2 highlights the surface anatomy of the right and left lungs from the cow’s thoracic cavity.
- Location of the cow’s left lung: It is located in the thoracic cavity that extends from the second rib to the eleventh rib.
- Location of the cow’s right lung: It is separated from the left lung by the mediastinum and extends from the first rib to the tenth rib.
However, the lungs are related dorsally to the esophagus and cranio-medially to the heart. Again, both lungs are also related to the diaphragm caudally.
But why is the topographic or surface anatomy important for cows’ lungs? Well, the topographic anatomy of the lung provides knowledge on the relationship of the other thoracic organs with the lungs. However, surface anatomy helps you locate the cow’s lung by surface approaches for auscultation or other practices.
Here, Figure 3 highlights the triangular area to locate the cow’s lung by an external approach. However, I have modified it a little, as the right or left lung of the cow did not extend past the last rib.
Pleura and mediastinum
Figure 4 shows that the cow’s lungs are enclosed in a double-layered bag of the serous membrane. It is the pleura or pleural sac of the cow’s lung.
However, the interpleural space separates the right and left pleural sacs at the midline between the lungs. This is the mediastinum that extends from the cow’s thoracic inlet to the diaphragm along the midline of the thorax.
Cow lungs anatomy
Figure 5 highlights the anatomy of the cow’s lung. It shows these features that you should describe for the cow’s right and left lungs.
According to the figure, each lung is divided into lobes formed by deep fissures. They actually extend from the ventral border to almost the area of the lung’s root.
However, each lung of the cow is soft, lightweight, spongy, and elastic. They are pink in fresh condition, and may be pale gray or dark red in a dissected sample.
Sometimes, you may ask – what is the shape of the cow’s lung? Well, according to the above-mentioned figure, each of the lungs of a cow is conical in shape.
Thus, for an anatomical description of the cow’s lung, you might mention the features from the following –
- Lobes of the lungs: The cow’s right lung has 4 lobes, whereas the left one has three lobes.
- Surfaces of the lungs: Both lungs of the cow present 2 surfaces: the lateral and medial.
- Borders of the lungs: They present 2 distinct borders: dorsal and ventral.
- Base and apex of the lungs: Both the right and left lungs present the base and conical apex.
However, the ventral borders exhibit notches and fissures, which vary between the right and left lungs.
Lobes of the right lung of the cow
Figure 6 highlights the four lobes of the cow’s right lung, which are formed by the deep interlobar fissures. These lobes are not well-separated in the cow, but can be easily identified practically.
Thus, the cow’s right lung presents the following lobes –
- Apical or cranial lobe,
- Cardiac or middle lobe,
- Accessory or intermediate lobe, and
- Diaphragmatic or caudal lobe,
You may have the question: why do I start with the identification and description of the lobes of the cow’s lung? Well, proper knowledge of the lobes of the lungs helps you to describe their surfaces, borders, base, and apex perfectly.
Apical/cranial lobe of the right lung
The apical lobe is larger in the cow’s right lung. However, it extends to the left of the median plane, ventral to the trachea and great vessels, and cranial to the cow’s heart.
Here, the apical lobe divides into cranial and caudal parts in the cow’s right lung. However, this division is formed by the fissure that extends from the cardiac notch (Figure 5).
The medial surface of the apical lobe presents the greater part of the cardiac impression (Figure 6). Though you may also describe these features while describing the medial surface of the cow’s right lung.
Cardiac/middle lobe of the cow’s right lung
Figure 7 highlights the cardiac or middle lobe of the cow’s right lung. It is an elongated three-sided part of the right lung.
This cardiac lobe is separated from the cranial apical and caudal diaphragmatic lobes by the interlobar fissure.
However, this lobe is medially related to the heart. Thus, the medial surface of the lobe presents a part of the cardiac impression.
Accessory/intermediate lobe of the right lung
Figures 6 and 7 show the accessory or intermediate lobe of the cow’s right lung. It is pyramidal in shape and forms a part of the diaphragmatic surface or base of the right lung.
The accessory lobe also presents a groove for the passage of the caudal vena cava when it attaches to the diaphragmatic lobe. Actually, they attach to the medial aspect, and the accessory lobe is placed just behind the hilus (Figure 5).
Diaphragmatic/ caudal lobe of the cattle’s right lung
The diaphragmatic lobe is the largest lobe of the cow’s lungs and is caudal in position. A portion of the cardiac lobe attaches to the medial surface of the diaphragmatic lobe.
Lobes of the cow’s left lung
If you compare the cow’s right and left lungs, you will find a distinct variation in their lobes. So, how many lobes are there in the left lung of a cow? Are they 4 or 3 lobes?
Figure 8 presents the lobes from the cow’s left lung. It shows there are three lobes present in the cow’s left lung.
Thus, the lobes of the cow’s left lung are: apical/cranial, cardiac/middle, and diaphragmatic/caudal. Here, the accessory or intermediate lobe is absent from the medial surface of the cow’s left lung.
However, the apical lobe of the cow’s left lung is smaller than the right one. The cardiac lobe, along with the apical lobe, forms the extensive cardiac impression medially.
Again, the diaphragmatic lobe of the cow’s left lung is in close contact with the diaphragm.
Exception: The fissure/notch between the cardiac and apical lobes is not deep. Thus, sometimes they are considered as a single lobe of the cow’s left lung.
Surfaces of the cow lungs
Figure 9 shows a hand-drawn schematic of the two surfaces of the cow’s lung anatomy. It presents the convex lateral and concave medial surfaces of the cow’s right and left lung.
Lateral surface: It is also called the costal surface, which faces the inner aspect of the thoracic wall. Thus, its conformity is designed and adapted for the ribs, cartilages, and intercostal spaces of the thorax.
Sometimes, the lateral or costal surface of the cow’s right and left lungs presents the impressions of the ribs and cartilages.
Medial surface: The medial or mediastinal surface of the cow’s right and left lungs is vertical but irregular. However, this surface divides into the dorsal (vertebral) and the ventral (mediastinal) parts.
Here, the vertebral part of the medial surface relates to the bodies of the thoracic vertebrae. Whereas the mediastinal part relates to the structures or organs present in the mediastinal space.
What is the cardiac impression and hilus on the cow’s lung?
Cardiac impression: The overall medial surface of the cow’s right and left lungs presents a large, concave, and prominent area. These are the cardiac impressions of the cow’s lungs.
However, it is larger and more extensive in the right lung than the left one (Figure 10). While studying the apical and cardiac lobes, you already know that the cardiac impression appears between these two lobes on their medial aspect.
Hilus: The hilus is a rough triangular non-pleural area above and behind the cardiac impression. However, each hilus of the cow’s lungs contains the following structures –
- Primary bronchus,
- Pulmonary artery and vein,
- Bronchial artery, and
- Lymph vessels and nerves.
Besides the hilum and cardiac impression, the medial surface of the cow’s lungs presents a number of the following impressions/grooves –
- Horizontal impression for trachea: It extends cranially from the hilus of the cow’s right lung toward the apex. However, it is located along the dorsal aspect of the cardiac impression.
- Aortic groove: This groove is located just above and behind the hilus of the cow’s lungs. However, the aortic groove is deeper on the cow’s left lung.
- Esophageal groove: It is located just ventral to the aortic groove and is deeper in the cow’s right lung.
- Groove for the caudal vena cava: It is located on the medial surface of the cow’s right lung and runs between the intermediate and cardiac lobes.
Figure 11 highlights the various impressions and grooves from the medial surface of the cow’s lungs.
Borders of the cow’s right and left lungs
Figure 12 presents the dorsal and ventral borders of the cow’s right and left lungs. It also presents the cardiac notches and fissures of the ventral borders of the lungs.
Dorsal border of the cow’s lung: It is thick, rounded, and related to the proximal extremity of the ribs and sympathetic trunk. However, it forms the dorsal boundary between the lateral surface and the vertebral part of the medial surface.
Ventral border of the cow’s lung: This border is irregular, thin, and shorter than the dorsal border.
The ventral border of both the right and left lungs of the cow presents the cardiac notch.
What is the cardiac notch in a cow’s lung?
The ventral border of the cow’s lungs presents a V-shaped/triangular/concave incision. It is indented at the level of the heart at the third or fourth rib (Figure 12).
However, through this notch, the pericardium, along with the apical part of the cow’s heart, is exposed to the thoracic wall.
The cardiac notch is variable in size in the two lungs of the cow. In the cow’s left lung, the ventral border is a L-shaped gap. However, the angle of the L forms a larger cardiac notch on the left than on the right.
Location of the cardiac notch: It lies opposite to the ventral third of the third intercostal space, fourth rib, and the fourth intercostal space.
Why is the cardiac notch of the cow’s lung important? Well, the cardiac notch of the cow’s left lung is a much extensive area than on the right side (Figure 12). Thus, the area of the left cardiac notch is the preferred site for examination of the cow’s heart.
Base and apex of the cow lungs
Figure 13 highlights the base and apex of the cow’s right and left lungs. Here, the base of the lungs is oval, concave, and smooth, whereas the apex is conical in shape or pointed.
Base of the cow’s lungs: It is also known as the basal surface or the diaphragmatic surface. However, it is related and moulded on the thoracic surface of the cow’s diaphragm.
The base of the right lung is more concave due to the placement of the cow’s liver at the other side of the diaphragm.
Apex of the cow’s lungs: The apex occupies the space within the cupula of the pleural sac and is primarily formed by the apical lobe. Here, the apex of the cow’s right lung is much larger than that of the left lung.
It also extends to the left side of the cow’s thoracic cavity, passing ventral to the trachea, great vessels, and heart.
The apex of the cow’s left lung is more or less pointed. However, the apical lobe of the right lung is ventilated by a special apical bronchus that comes from the trachea.
The difference between the cow’s right and left lungs
Table 1 shows the differentiating anatomical features between the cow’s right and left lungs –
| Features | Cow’s right lung | Cow’s left lung |
| Size | Larger | Samller |
| Lobes | 4 lobes | 3 lobes |
| Apical lobe | Larger | Smaller |
| Intermediate lobe | Present | Absent |
| Cardiac impression | Deep | Shallow |
| Cardiac notch | Small | Deep/L-shaped gap |
| Base | More concave | Less concave |
| Apex | Conical shape | Pointed (more/less) |
| Apical bronchus | Present | Absent |
FAQ’s on the cow’s right and left lungs
The cow’s right lung is bigger due to an additional lobe called the intermediate lobe and a larger apical lobe (Figures 5 and 6). However, the cardiac notch on the cow’s right lung is smaller than that of the left one.
Here, the cow’s left lung presents an extensive cardiac notch compared to the right. This is because most of the heart is located on the left. This reduces the total volume of the cow’s left lung compared to the right lung.
The lungs of the goat and sheep are comparatively longer than the cow’s lungs. Here, the cardiac notch lies opposite to the ventral part of the fifth rib and the fifth intercostal space in goats and sheep.
The lobes of the goat and sheep’s right and left lungs are almost similar to the cow. However, there is no clear demarcation between the apical and cardiac lobes of the goat and sheep’s right lung (Figure 14).
Again, the division of the apical lobe in the lungs of the goat and sheep is not clearly visible. Whereas the cow’s lung clearly shows the cranial and caudal divisions of the apical lobe.
The pulmonary artery from the right ventricle of the cow’s heart provides functional supply to the lungs. It gives a primary branch to each lung and a secondary branch to each lung lobe.
However, the cow’s lung is innervated by the pulmonary nerves. Here, the pulmonary nerves are the branches of the cow’s autonomic nervous system.
Conclusion
So, the anatomy of cow lungs includes their location and the features of their surfaces, borders, base, and apex. Here, the lobes, impressions, and grooves are also identifying features for the cow’s right and left lungs.
A larger apical lobe and an additional intermediate lobe make the cow’s right lung larger than the left one. However, the larger cardiac notch, which is unique on the ventral border of the cow’s left lung, is due to the presence of the heart.
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