|Year : 2016 | Volume
| Issue : 3 | Page : 284-287
Morphological variation of human lung fissures and lobes: An anatomical cadaveric study in North Karnataka, India
Paras Thapa, Suresh P Desai
Department of Anatomy, KLE's Jawaharlal Nehru Medical College, Belagavi, Karnataka, India
|Date of Web Publication||21-Dec-2016|
Dr. Suresh P Desai
Department of Anatomy, KLE's Jawaharlal Nehru Medical College, Belagavi - 590 010, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: The lungs are a pair of vital organs of respiration which are divided into lobes by fissures. The fissures facilitate the movements of lobes and help in uniform expansion of the whole lungs. The fissure may be complete, incomplete, or absent. The knowledge of position and completeness of fissures and lobes is necessary for an appreciation of lobar anatomy and thus locating bronchopulmonary segments.
Objectives: The objective of this study was to analyze the morphology of fissures and lobes of lungs.
Materials and Methods: Twenty pairs of lungs were taken for the study, obtained from twenty formalin-fixed cadavers. The specimens were thoroughly observed for the pattern of lobes, fissure variations were noted, and the specimens were photographed.
Results: Of the twenty right-sided lungs, incomplete oblique fissure was seen in six (30%) lungs. None of the lungs showed the absence of oblique fissure. Incomplete horizontal fissure was seen in ten (50%) lungs, and horizontal fissure was found absent in four (20%) lungs. Among the twenty lungs, four (20%) lungs showed two lobes due to the absence of horizontal fissure and the remaining 16 (80%) lungs showed normal lobar pattern of lungs. On the left side, incomplete oblique fissure was observed in two (25%) lungs, and two (25%) lungs showed the absence of oblique fissure. Due to the absence of oblique fissure, three (15%) specimens showed only one lobe while 17 (85%) lungs showed normal lobar pattern. There was no incidence of the presence of an accessory fissure in either side of the lungs.
Conclusion: The present study when compared with a previous work showed a wide range of difference in the lobes and fissures between and among different populations. Knowledge of such variation may be important for performing lobectomies, surgical resections, and correct interpretation of radiological images.
Keywords: Cadaver, horizontal fissure, lung, oblique fissure
|How to cite this article:|
Thapa P, Desai SP. Morphological variation of human lung fissures and lobes: An anatomical cadaveric study in North Karnataka, India. Indian J Health Sci Biomed Res 2016;9:284-7
|How to cite this URL:|
Thapa P, Desai SP. Morphological variation of human lung fissures and lobes: An anatomical cadaveric study in North Karnataka, India. Indian J Health Sci Biomed Res [serial online] 2016 [cited 2019 Dec 6];9:284-7. Available from: http://www.ijournalhs.org/text.asp?2016/9/3/284/196326
| Introduction|| |
The lungs are a pair of vital organs of respiration located within the thoracic cage, on either side of the heart and other mediastinal contents. Each lung is conical in shape which is divided into lobes by double layers of infolded reflection of visceral pleura called fissures. Anatomically, the right lung is divided into upper, middle, and lower lobes by oblique and horizontal fissures whereas the left lung is divided into upper and lower lobes by an oblique fissure. On the right side, middle and inferior lobes are separated by oblique fissure and upper and middle lobes are separated by the horizontal fissure.
In each lung, oblique fissure begins on medial surface at the posterosuperior part of hilum and crosses the posterior border of the lung 6 cm below the apex. At the posterior border, the fissure lies opposite at a surface point 2.5 cm lateral to the junction of T3 and T4 spines. Then, it descends forward across the costal surface to reach the inferior border of lung at 5th intercostal space and follows the 6th costochondral junction about 7.5 cm lateral to the middle line. It finally ascends on the medial surface and ends at the lower end of hilum. The left oblique fissure is more vertical than the right. The short horizontal fissure separates the superior and middle lobes. The horizontal fissure begins at the oblique fissure near the midaxillary line, course horizontally along the costal surface, cuts anterior border at the level of 4th costal cartilage, and then passes backward on the mediastinal surface to the end at the hilum.
The fissures facilitate the movement of lobes in relation to one other which accommodate the greater distention and movements of lower lobes during respiration. The fissure may be complete, incomplete, or absent altogether. Accessory fissures are sometimes present which divide the lungs into smaller subdivision. In the presence of these major variations, the left lung may have three lobes and the right lung may have four or only two lobes. The identification of the completeness of the fissure is important before lobectomy, individuals with incomplete fissure are more prone to develop postoperative air leaks.
The position of lobes and fissures is useful in locating the bronchopulmonary segments which is significant both anatomically and clinically. Prior awareness and anatomical knowledge of the variations in the lobes and fissures of lung is important for proper radiological interpretation and is of great significant to cardiothoracic surgeons for planning segmental resection. Considering anatomical and clinical importance, an attempt has been made to study the morphology of lung fissures and lobes from specimens obtained from cadavers in North Karnataka, India.
| Materials and Methods|| |
Twenty pairs of lungs, of which 12 pairs belong to male and eight pairs belong to female cadavers used during routine dissection for the medical undergraduate classes in the Department of Anatomy, J. N. Medical College, were taken for the study after proper embalming with 10% formalin. The thoracic wall of the cadavers was dissected, and then the lungs were exposed to study the morphological features such as the number of fissures and lobes.
Anatomical classification proposed by Craig and Walker's was followed to determine the presence of completeness of fissures.
- Grade I - Complete fissure with entirely separated lobes
- Grade II - Complete visceral cleft but parenchymal fusion at the base of fissure
- Grade III - Visceral cleft evident for a part of fissure
- Grade IV - Complete fusion of lobes with no evident fissural line.
| Results|| |
The study on twenty lungs of each side revealed the following fissural pattern which is depicted in [Table 1].
Incidence of oblique and horizontal fissure according to Craig and Walker's criteria is depicted in [Table 2].
|Table 2: The incidence of oblique and horizontal fissure according to Craig and Walker's criteria|
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| Discussion|| |
The lungs develop from respiratory diverticulum of cranial foregut which subsequently differentiates into various components of respiratory tree and parenchyma. With progressive development, all the spaces between individual bronchopulmonary segments get obliterated except along the lines of division of principal bronchi, where deep complete fissure remains patent dividing the right lung into three lobes and left lung into two lobes. The fissures are oblique and horizontal in position in the right lung and only one fissure is placed obliquely in the left lung. Absence or incompleteness of fissures could be due to obliteration of these fissures either completely or partially. With defect in pulmonary development, there can be variation in the lobes and fissures of lungs.
Several authors have reported varying percentage of incidence of absence of oblique fissure in the right lung, but in the present study, there was no incidence of absence of oblique fissure. In the present study, the left lung showed absent as well as incomplete oblique fissure which is in conformity with previous studies. There was higher percentage of incidence of incomplete oblique fissure in the right lung as compared to the left lung. When compared with other studies, the incidence of the percentage of incomplete oblique fissure of the right lung is more than the previous studies [Table 3]. The incidence of the percentage of incomplete horizontal fissure was less than the previous studies except the values obtained by Divya et al. which show a similar value. The percentage of incidence of absence of horizontal fissure obtained by Divya et al. was found to be nearly similar to the present study while the percentage of incidence obtained by Nisha et al. drastically varies. The incidence of percentage of incomplete left oblique fissure of the present study was nearly similar with that of a study done by Abhilasha and Charulata, while the incidence of percentage of absence of oblique fissure in the left lung is more than that of earlier studies. Accessory fissures are sometimes present which appear differently on X-rays and computed tomography scans and can mistakenly be confused with the areas of atelectasis or consolidation, pleural sacs or walls of bullae.
|Table 3: Comparative incidence of variations of oblique and horizontal fissures|
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The previous and present studies emphasize the clinical importance of the knowledge of variations of fissures in the lungs to clinicians, radiologists, and thoracic surgeons.
| Conclusion|| |
The incidence of fissural pattern of fissures was significantly higher in the present study in comparison to previous ones. By comparative study, it is deduced that absence and incomplete fissures are the common variants of lung morphology. Thus, it is concluded that knowing the frequency of occurrence of variant fissure in particular population might help the radiologists and clinicians to make a correct diagnosis. Similarly, it might help the surgeons to plan, execute, and modify a surgical procedure depending on the merit of case. This will ultimately help reduce the morbidity and mortality associated with lung surgeries.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]