How many fissures in the right lung

The criteria here used to classify the lung fissure incompleteness was the connected lobes by chunk of pulmonary tissue anywhere in the fissure, and those failed to reach the hilum of lung. Accessory fissure varied from notch to complete fissure; and exhibited in seven right lungs Table 1 among them one lung had both SAF Fig. Four right lungs had only IAF, because of which additional lobe Fig.

Interestingly, one right lung had a notch in the costal surface of middle lobe probably representing the demarcation between medial and lateral bronchopulmonary segment Fig. Nine left lungs Table 1 were with accessory fissure. In two specimens the lingula appeared to be separate lobe Fig.

The data in Craig and Walker's classification Table 3 shows Similarly, Grade III fissures were seen in Only The criteria here used to classify degree of completeness of fissures were the location of pulmonary artery at the base of oblique fissure and extent of varied parenchymal fusion along the floor of fissure. Gradation of fissures is important surgically for easy approach in surgical procedure and to prevent postoperative hemorrhage and complications.

When the embryo is approximately 4 weeks old, the respiratory diverticulum lung bud , an outgrowth from the ventral wall of the foregut, expands caudally into the surrounding mesenchyme and bifurcates into right and left bronchial buds. The right bronchial bud then divides into three secondary bronchi while the left bud into two secondary bronchi. Each lung then develops by a process of repeated dichotomous branching of the secondary bronchi. After several generations of branching, bronchopulmonary segments are formed [ 11 ].

In fetal period these bronchopulmonary segments are separated by spaces which later on gets obliterated except along the line of division of principal bronchi to give rise to major oblique and minor horizontal fissures in fully developed lung.

Along these fissures the visceral pleura is reflected and covers individual lobes on all sides [ 12 ]. Defective pulmonary development will give rise to variations as encountered in fissures and lobes [ 13 ]. Incomplete or absence of oblique and horizontal fissures could be due to a defect in the obliteration of these fissures either completely or incompletely [ 2 ].

The monopodial branching of stem bronchi accounts for accessory bronchi and lobes often found in adult lung [ 14 ]. Cadavers are still the best means to study all the domains of anatomy. It is observed that absent horizontal fissure is commonly occurring variation as reported by many researchers Table 4. Only the study of Mamatha et al. Incidence of missing horizontal fissure in present study Incomplete horizontal fissure was found highest in Jacob and Pillay's study [ 20 ] while least was in Lattupalli's study [ 22 ].

In our study it is found to be Prevalence of absence of oblique fissure in both right and left lung is comparatively less than absence of horizontal fissure in all above studies including present study. Oblique fissure of right lung was reported to be absent in data of other studies [ 9 , 15 , 18 , 19 , 20 , 24 ] while similar to our study remaining researchers [ 2 , 16 , 17 , 21 , 22 , 23 , 25 , 26 , 27 ] did not find missing oblique fissures. Incidence of missing oblique fissures of left lung was reported [ 15 , 18 , 19 , 22 , 24 , 27 ] but none of the cases of missing oblique fissures of left lung were reported in remaining studies including present study.

In present study incomplete oblique fissure was more in left lung Such findings were similar in most of above mentioned cases except these studies [ 18 , 19 , 20 , 21 , 22 , 23 ]. Beside variations in major and minor fissures of lung, clinicians and radiologists must be aware of possibilities of having accessory fissure.

Radiographically it appears as a thin white line, resembling the major and minor fissure, except for location. The line can be mistaken for an interlobar fissure, scar and wall of a bulla or for pleural line made visible by pneumothorax [ 4 ].

As shown in Table 5 , in present study LMF According to Nene et al. Study of Quadros et al. George et al. Studies of Prakash et al. The more common locations are between medial and lateral segments of the middle lobe and between anterior and lateral segments of the lower lobes. Sometimes fissures occur within a bronchopulmonary segment, usually separating subsegments, most commonly in the middle lobe or the posterior segment of the left lower lobe [ 4 ].

In present study a vertical notch was observed in middle lobe of one right lung, probably separating the medial and lateral bronchopulmonary segments of the lobe. Such finding was not shown in any literatures available to our best of knowledge.

The nature of fissure is of great importance in planning pulmonary surgeries. In order to provide a frame work for description of operative technique and to allow meaningful comparison between different surgical series, Craig and Walker [ 10 ] have proposed a fissural classification based on both the degree of completeness of the fissures and the location of the pulmonary artery at the base of the oblique fissure [ 2 ].

Gradation of fissures is important surgically for easy approach in surgical procedure and to prevent postoperative haemorrhage and complications. In cases of incomplete fissures where parenchymal fusion is present more dissections has to be performed to reach the bronchi and pulmonary arteries during surgical resections leading to more haemorrhage and postoperative complications.

An incomplete fissure may alter the spread of disease within the lung and is also a cause for postoperative air leakage [ 10 ]. Similarly, accessory fissures in patients with endobronchial lesion, might alter the usual pattern of lung collapse and pose difficulty in diagnosing a lesion and its extent.

Often these accessory fissures act as a barrier to spread of infection, creating a sharply marginated pneumonia, which can wrongly be interpreted as atelectasis or consolidation [ 4 ]. An anomalous fissure can be mistaken for a lung lesion or an atypical appearance of pleural effusion.

As the fissures form the boundaries for the lobes of the lungs, knowledge of their position is necessary for the appreciation of lobar anatomy and thus for locating the bronchopulmonary segments which is significant both anatomically and clinically. The lobes of lungs show partial fusion as a result of incomplete pulmonary fissures.

The results and their comparison with the previous works show that there is a wide range of difference in occurrence of oblique, horizontal and accessory fissures. In present study, common finding is complete oblique and horizontal fissures in right lung and incomplete oblique fissure in left lung. Accessory fissure varied from notch to prominent fissure often separating an accessory lobe.

LMF of left lung, which separates the lingula from upper lobe is frequently appearing accessory fissure. The wide range of variation in occurrence of oblique, horizontal and accessory fissures might be due to genetic and environmental factors during its development. The authors are highly thankful to National Medical College, Birgunj, Nepal for providing the necessary support.

Professor S. C Gupta is duly acknowledged for his extreme support and encouragement to carry out this study. Authors also acknowledge the immense help received from the scholars whose articles are and books cited and included in discussion and references of this manuscript. National Center for Biotechnology Information , U.

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This article has been cited by other articles in PMC. Abstract The fissures of lungs are embryologically separating the bronchopulmonary segments, which later on persist in interlobar planes of fully developed lung.

Certain radiological findings can mislead the diagnosis as in the cases of extra lobes, as it may misinterpret as lung lesions. In the presence of extra lobes, the CT scan shows a significant increase in the size of mediastinum around the trachea [ 5 ]. The accessory fissure might alter usual pattern of lung collapse in patients with endobronchial lesion, and pose difficulty in diagnosing the extent of lesion.

Normally pneumonia will be restricted to the lobes affected by it, but in patients with incomplete fissures, it may spread to adjacent lobes through the parenchymal continuation [ 6 , 7 ]. In the current study, we focused on the morphological variations of the lungs in the south Indian cadaveric samples. One hundred thirty-eight isolated, adult formalin fixed cadaveric lungs preserved in the dissection hall were observed for the study.

The lungs belonged to the adult age group between years. No gender difference of the lungs was made in this study. Only those lungs which were covered all over by pleura except at the hilum were used in the study. If any part of the lung was cut off during its removal, such lung was excluded from the study. Out of lungs, 65 were right lungs, and 73 were left lungs. Following parameters were noted in the current study: number of fissures and lobes, shape of lungs and their lobes, and variations in the hilar structures.

Among the 65 right lungs, 2 lungs 3. Three right lungs 4. Two 3. Forty-one lungs Sixty-four of them Two of the lungs 3.

Among the 73 left lungs, 11 Two of them 2. Four of them 5. Fifty-nine Sixteen of them Five lungs 6. Photographs of the specimens with some of the major variations can be seen in Figs. Percentage statistics have been given in Table 1. Cadavers are the best means to study the variant anatomy of any organ. Various researchers have noted and reported the anomalous anatomy of the lungs in human cadavers [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ].

During development of the lungs numerous bronchopulmonary buds are formed and later they fuse completely except at the sites of fissure formation. This results in the formation of lobes and fissures.

Incomplete fissure formation could be due to partial obliteration of these fissures [ 8 ]. Accessory fissure could be the result of non-fusion of spaces between the bronchopulmonary buds which normally are obliterated.

If there is any factor affecting the fusion in the developmental stage, there will be variations in the formation of lobes and fissures of the lung [ 4 ].

In our literature survery, we could find a few reports on variations of the fissures of the lungs [ 15 , 16 , 17 , 18 ]. Knowledge of development of minor lung segments and pulmonary veins is also useful clinically [ 19 ].

When compared to the previous studies, we found a higher incidence of incomplete horizontal fissures and two arteries in the hilum of right lung [ 9 , 10 , 11 ]. Accessary lobes and fissures can be misinterpreted on X-rays and CT scans. They can also be confused with certain clinical conditions such as linear atelectasis, pleural scars or walls of bullae [ 3 , 11 , 14 ]. In our study 3 such cases of right lungs with extra horizontal fissures were present, with which the lungs were divided into 4 lobes instead of 3 lobes.

Two of the left lungs also showed an accessary fissure, which divided them into 3 lobes instead of 2 lobes. Some of the previous studies also report the presence of accessory lobes of lungs [ 20 , 21 , 22 ]. It is very rare to find an artery in the fissure of a lung. Awareness of this might be useful for surgeons to avoid excessive bleeding during pulmonary lobectomy. The shape anomaly such as cylindrical or leaf like appearance may be of congenital cause and when exists, might cause confusions in radiological diagnosis.

In conclusion, knowledge of the fissures and lobes of the lungs are important to plan various surgical procedures to avoid post-operative complications like air leakage. It can also help to explain various radiological appearances of lobar anatomy of the lungs and the position of the interlobar fluid. The results of the present study and their comparison with the previous studies shows that a variety of variations can occur at the hilar structures as well as the shape, fissures and lobes of the lungs in humans.

Variations in the number and pattern of hilar structures in both human lungs have not been studied in detail by earlier researchers, thus this study add a database for the same. The lobes are further divided into segments and then into lobules, hexagonal divisions of the lungs that are the smallest subdivision visible to the naked eye. The lobes of the lungs : The right lung has three lobes and the left lung has two. The right lung is five centimeters shorter than the left lung to accommodate the diaphragm, which rises higher on the right side over the liver; it is also broader.

The volume, the total capacity, and the weight of the right lung is greater than that of the left. The right lung is divided into three lobes.

The upper lobe is the largest lobe of the right lung. It extends from the apex of the lung down to the horizontal and oblique fissures. It bears apical, anterior, and posterior bronchopulmonary segments. The middle lobe is the smallest lobe of the right lung, located between the horizontal and oblique fissures. It bears medial and lateral bronchopulmonary segments. The lower lobe is the bottom lobe of the right lung. It lies beneath the oblique fissure. It bears medial, lateral, superior, anterior, and posterior bronchopulmonary segments.

The Left Lung : This has a concave depression that accommodates the shape of the heart, called the cardiac notch. The human left lung is smaller and narrower that the right lung, and is divided into two lobes, an upper and a lower, by the oblique fissure. The left lung has only two formal lobes because of the space taken up in the left side of the chest cavity by the heart, though it does have the lingula, which is similar to a lobe.

The left lung has a depression on the medial side of its surface called the cardiac notch, a concave impression molded to accommodate the shape of the heart. The upper lobe of the left lung contains anterior and apicoposterior bronchopulmonary segments. It is above the oblique fissure. The lower lobe of the left lung contains superior, anterior, posterior, medial, and lateral bronchopulmonary segments.

The lingula is not formally considered to be a lobe. It is a small, tongue-like projection of the left lung that is analogous to the middle lobe of the right lung.

It contains superior and inferior bronchopulmonary segments. Above and behind the cardiac impression is a triangular depression named the hilum. The hilum is the root of the lung where that contains structures that supply the lungs with blood, lymph fluid, and innervation, such as the pulmonary vein, pulmonary artery, pulmonary nerves, and lymphatic vessels.

These structures are enclosed by pleura. There is a hilium for each of the lungs found in the mediastinum backside of the lungs. The hilium is thinner in the left lung compared to the right lung because it lies between the cardiac notch and the groove for the aorta. The hilium is important because it is the primary way in which the respiratory system links with the cardiovascular and nervous systems.

Pulmonary circulation transports oxygen-depleted blood away from the heart to the lungs and returns oxygenated blood back to the heart. Bronchial circulation by the bronchial arteries supplies blood to the tissues of the bronchi and the pleura, and is considered part of systemic circulation. The right side of the heart deals with pulmonary circulation. At the end of systemic circulation, the veins take blood back to the heart through the vena cava.

The vena cava fills the right atrium with blood, which then ejects blood into the right ventricle by passing through the tricuspid valve. After blood fills in the right ventricle, it contracts and pumps the blood through the pulmonary valve, and into the pulmonary arteries.

There are two pulmonary arteries one for each lung that bring the deoxygenated blood to the lungs through the hilium. The arteries branch into the capillaries of the alveoli. Capillaries are the thinnest and smallest type of blood vessel, and they supply oxygen to individual tissues everywhere in the human body.

Gas exchange occurs by passive diffusion in the alveoli, so that dissolved oxygen enters the capillaries, while carbon dioxide leaves pulmonary circulation.

The oxygenated blood then leaves the lungs through pulmonary veins also contained in the hilium , which return the blood to the left side of the heart, completing the cycle of pulmonary circulation. This blood then enters and fills inside the left atrium, which pumps it through the mitral valve also called bicuspid into the left ventricle.

The blood fills inside the left ventricle and is then pumped through the aortic valve into the aorta, which marks the beginning of systemic circulation.

Systemic circulation and pulmonary circulation form the overall cycle of the circulatory system: transporting oxygen throughout the body.