Illustrated Encyclopedia of Human Anatomic Variation: Opus IV: Organ Systems: Respiratory System
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
An accessory inferior lobe is frequently found on the undersurface, extending up onto the medial surface in front of the pulmonary ligament. This lobe may be indicated by a shallow fissures or be clearly defined. It may present a tongue-like projection inward or may comprise the entire medial portion of the base, but usually consists of one-fifth to one-third of the base. The lobe may occur on either side or on both; it is larger and more frequently well-defined on the right, but more often present, or at least indicated, on the left. It was found in 47% of 210 lungs.
Occasionally absence of a fissure marking off the middle lobe has been reported. An irregular fissure may subdivide the left lung into three lobes, and both lungs may further subdivided, especially the right. In one study, a single pair of lungs was divided into 11 clearly defined lobes with fully developed pleural fissures. However, one more frequently finds the commonly described five lobes not separated by fissures.
The most detailed study of the human lung has been performed by Boyden and associates.The brief summary that follows is from some of that work. The lung may show various degrees of developmental arrest: (a) agenesis, absence of one or both lungs; Congenital absence of a lung has an incidence of 0.007% (2/30,000) of autopsies (Ellis,1917) (b) aplasia, formation of rudimentary bronchi: and (c) hypoplasia, incomplete development of the lung. Short trachea has been reported (Wells et. al.) to occur in 36% of patients (31/87) with myelomengocele. It is also reported by Wells et. al. to be associated with a number of syndromes including: DiGeorge anomaly (77%), interrupted aortic arch (83%), hypoplastic left heart complex (63%), congenital cardiovascular disease (25%), clinical brevicollis, including Klippel-Feil and Jarcho-Levin syndromes (57%), skeletal dysplasias, including Ellis-Van Creveld syndrome, Jeune syndrome, osteogenesis imperfecta, achondrogenesis type 2, Kniest syndrome, hypophosphatasia (spur-limbed type), mesomelic dwarfism (Langer type), and short rib-polydactylia (59%), diaplacental rubella (40%), congenital hemidysplasia and ichthyosiform erythroderma with limb defects (CHILD) syndrome, Möbius sequence, Nager acrofacial dyostosis, partial chromosome 3 trisomy, and generalized GM1 gangliosidosis type 1.
Thomas and Boyden reported three cases of agenesis of the right lung with numerous variations of the left lung. In two cases, the left lung had three lobes and in a third it had no lobulation. In addition, there are cases of variations in bronchopulmonary segments, left eparterial bronchus, and vascular anomalies including coarctation of the aorta, persistent ductus arteriosus, and left post-tracheal or bronchial pulmonary artery.
Hypoplasia of only a single lobe or the entire lung has been described. In one case, the right lung appeared to have two lobes, but within the oblique fissure a small bronchus was found to supply a small piece of lung tissue; the bronchus originated at the expected site of the middle bronchus.
Rudimentary lung tissue may be found arising in ectopic positions such as (most commonly) the trachea. Examples of these so-called supernumerary lungs are described by Boyden; they arise from tracheal diverticula, and are not to be confused with displaced lobar bronchi. In one study, five specimens of this type were found in 6,000 autopsies (0.08%).
Another type of supernumerary lung is the Rokitansky lobes, isolated structures, located in the lower thorax. They occur most frequently on the left side, usually above the diaphragm. In one study, in 27 of 41 cases the lobes were located above the diaphragm and in 5 cases below the diaphragm. These isolated masses of lung tissue are usually separated from both the tracheobronchial tree and the pulmonary vascular system. It has been reported that these isolated masses are subject to the same diseases that affect lungs. Anomalous lung tissue has been reported as an outgrowth of the wall of the stomach.
Aeby (1880) first characterized the human lung as asymmetrical because of the presence of a right eparterial bronchus. Boyden noted that in very rare instances, a left eparterial may also occur (five cases, with only one case in 100 consecutive dissections). Although this variation has an incidence of "no more" than 1%, it is of surgical importance that it be recognized when present.
Lobar bronchi may be displaced to a point higher or lower than usual on the primary lung sacs. Cases are known in which the whole right upper lobe bronchus originates immediately above the middle lobe bronchus. The right upper and middle lobe bronchi may arise from a single stem located at the usual site of the middle lobe. The middle lobe bronchus may arise from a normally placed right upper lobe bronchus, either from the main stem or from the proximal part of the anterior segmental bronchus. The right upper lobe bronchus sometimes originates from the right lateral wall of the trachea.
Variations in the patterns of the bronchial trees are, for the most part, due to displacement of segmental and subsegmental bronchi. These variations are important considerations in resection of bronchopulmonary segments. One such variants, which supplies all or a part of the apical segment, arises on the right side of the trachea or from the lateral wall of the right primary bronchus before the origin of the lobar bronchus. Boyden has termed this the "pre-eparterial bronchus." In addition, one of the upper lobe bronchi may originate at a lower level.
The right anterior bronchus, so-called B2, may arise from the middle-lobe stem. Boyden has termed this the "postarterial bronchus." Usually the left medial basel (B7) and the left anterior basal (B8) bronchi arise from a common stem. In 7% of 100 specimens studied, Boyden found that B7arises independently, at a higher level on the tree. In the left lower lobe, the posterior ramus of the anterior segment (B2a) may be absent (35% of cases studied). When present, it occupies the site at which the absence of the left upper lobe most frequently occurs. Other examples and a detailed analysis of variations in the lung can be found in the numerous works of Boyden and co-workers.
The most common variation of the lungs is the presence of supernumerary fissures. These fissures do not always separate segments but may enter subsegmental or interbronchial planes. The most common site for a supernumerary fissure is the plane between the medial basal (B7) and anterior basal (B8) segments of the right lower lobe. This partially segregates a cardiac or infracardiac lobe. In one study, it was found in 35% of 180 human lungs, and in another study it was found in 38% of 50 injected right lungs. These variations would have been found in surgical exploration and, most of them, in radiologic examinations. A comparable fissure occurs, infrequently, in the left lung. Another common fissure segregates, more or less, the superior segment of the right or left lower lobe (so-called "dorsal lobe of Nelson"). In a study by Dévé it was found bilaterally in 12 cases, in the right lower lobe in 40, and in the left lower lobe in 14. In this study, the separated part was called the "posterior lobe."
Yet another common cleavage is the left horizontal fissure. This subdivides the left upper lobe into two almost equal parts, the lower part being called the "left middle lobe." Four types of left middle lobe have been described by Boyden: (a) a true middle lobe separating normal upper and lower division segments, (b) a compressed lingular, (c) an expanded lingular, and (d) an ectopic pulmonary type, which always separates the sector of an eparterial bronchus from the left upper lobe.
Another common form of lung variation includes the absence of fissures. In a study of 277 lungs, the horizontal fissure was absent in 21% and incomplete in 67%. Incomplete oblique fissures occur in about 30% of both right and left lungs.
Certain segments of the upper and middle lobes have a predilection for disease processes. In the right lung, subsegment B3a is the site of secondary Assmann's focus of pulmonary tuberculosis. Segment B3on the right side and subsegment B2a on both the right and left sides are common sites of lung abscesses. Segments B4and B5are common sites of bronchiectasis. In the lower lobes, the superior segment (B6), the subsuperior bronchus (B*), and accessory subsuperior bronchi from B9and B10are common sites of lung abscess.
A small process of the right lung just above the base, behind the termination of the inferior vena cava, rarely becomes isolated as the lobus cava. The vena azygos may be displaced outward, so that, instead of curving over the root of the lung, it makes a deep fissure in the upper part of the right lung, called the azygos lobe. This variation may be recognized radiographically and has the shape of an inverted "teardrop" or a comma. In one study its incidence was about 0.5% (7 of 1400 specimens examined); in another study its incidence was about 0.5% (7 of 1400 specimens examined); in another study of 50,000 roentgen examinations its incidence was about 0.26%. All sources combined (323,641 examinations) indicate the incidence to be 0.57%.
The lobe of the azygos has been known since 1777; it was described by Wrisberg in the cadaver of a 3 year boy. In this first case the lobe appeared bilaterally. At least 11 other cases of left-sided lobes have been reported. The bronchial supply of the azygos lobe has been identified as the apical segment B1a and B3a, the apical rami of the apical and posterior segments. Azygos radiographic image was first seen by Wessler and Jaches. Velde named it the azygos lobe of the lung.
Rarely a segmental bronchus arises from the trachea. An anomalous lobe of the lung may also arise from the esophagus.
The absence of a lung has been reported.
The right lung is usually heavier than the left by about 50 to 100gm. It is also usually shorter and wider.
The trachea usually divides at the level of the fifth or sixth thoracic vertebra and much less commonly at the seventh thoracic.
The shape of the trachea is variable.
In short trachea, the tracheal rings are reduced to 15 or less from a normal 17.01 +/- 1.28 according to Wells, et al.
Although vascular variations are catalogued in part 2, the Cardiovascular System, the inclusion of pulmonary vasculature would seem appropriate here as well.
Accessory bronchial arteries may arise from the left aorta (embryologic), subclavian arteries, highest intercostal artery, and the right internal thoracic artery.
Accessory pulmonary arteries may arise from the thoracic aorta below the hilum of the lung and atypically from the derivatives of the embryonic arches. In the 25 recorded cases, they arise from the ascending aorta and the arch of the aorta in 10, from the innominate artery in four, from the right subclavian in two, from the left subclavian in five, and from the decsending aorta below the hilum of each lung in four. The variations are usually associated with malformation of the heart and developmental anomalies of the aortic arch.
The pulmonary veins may also retain connections with the derivatives of the anterior cardinal veins or other embryonic vessels. In one study summarizing 106 cases, the drainage from the lungs passed entirely into the right atrium or its tributaries in 36% and partially in the remaining 64%. Of the 64%, the site of drainage was (in order of frequency) superior vena cava, right atrium, and left innominate vein. Pulmonary venous anomalies occur about twice as frequently on the right as on the left. Other unusual sites of drainage include the coronary sinus, inferior vena cava, azygos vein, left subclavian vein, portal vein, and left persistent superior vena cava.
Variations in the mode of entrance of pulmonary veins into the left atrium are of surgical importance. In one study, in 3% of 148 specimens, the right lung drained into a common right pulmonary vein before emptying into the left atrium. On the left side, the frequency may be as high as 25%. The right pulmonary vein may also be represented by three veins, which arise from the usual three lobes of the right lung and empty into the left atrium. In one reported case, however, the middle lobe of the three veins drained a portion of the right middle lobe and also a part of the lower lobe. One may not assume therefore that each of these three veins is entirely restricted to a particular lobe.
Reported Variations in Left and Right Main Bronchi
|54 mm. ave.||50 mm. ave.|
|27 mm. ave.||30 mm. ave.|
Sappey, Traité d’anat. descript. Tome IV, p. 421, Paris, 1859.
Cruveilheir, Traite d’anat. descript., 5th ed., tome II, p.271, Paris, 1874
Letulle, Bull. et Mem. d. l. Soc. Anat. d. Paris, 1885(2):132-133.
Variations in Peripheral Segmentation of Right Lung
Pulmonary Lobe of Azygos Vein
Adachi, B. (1940) Selteneres Vorkommen des sog. "Lobus venae azygos" bei den Japanern. Anat. Anz. 89:214-216.
Adams, R. and E.D. Churchill. (1937) Situs inversus, sinusitis, bronchiectasis. Report of five cases, including frequency statistics. J. Thoracic Surg. 7:206-217.
Aeby, D. (1882) Der Bronchialbaum des Menschen bei Situs inversus. Arch. Anat. Physiol. Wissen. Med. 1882:31-32.
Afzelius, B.A. (1976) A human syndrome caused by immotile cilia. Science 193:317-319.
Alezais, -. (1903) Anomalie de division du poumon droit. Soc. Biol. Comptes Rendus Hebdomadaires des Séances et Mémoires. 55:144-145.
Allen, W. (1882) A variety of pulmonary lobation and its relations to the thoracic parietes, as illustrated by comparative anatomy and abnormalities in the humansubject. J. Anat. Physiol. 16:605-614.
Anson, B.J. and H.V. Smith. (1936) The accessory pulmonary lobe of the azygos vein. Am. J. Roentgenology 35:630-634.
Anson, B.J., Siekert, R.G., Richmond, T.E. and W.E. Bishop. (1950) The accessory pulmonary lobe of the azygos vein. An anatomical report, with a record of incidence. Q. Bull. Northwestern University Medical School. 24:285-290.
Appleton, A.B. (1944) Segments and blood vessels of the lungs. Lancet 2:592-594.
Atkin, E.E. (1934) A specimen of the accesory lobe of the azygos vein. Lancet 2:1221-1222.
Beau, -., Cayotte, -., Lux, -. and -. Streiff. (1951) La parabronche externe du lobe superieur du poumon humain. Assoc. Anatomistes Comptes Rendus 38:128-133.
Beau, -., Cayotte, -., Prévot, -. and -. Delestre. (1951) Systématisation du lobe moyen du poumon humain. Assoc. Anatomistes Comptes Rendus 38:134-139.
Beau, -., Cayotte, -., Gille, -. and Brulé. (1951) Systématisation du lobe inférieur du poumon humain. Assoc. Anatomistes Comptes Rendus 38:140-146.
Benedick, A.J. and H. Wessler (1928) The azygos lobe of the lung.
Bérard, M., Sournia, J. and L. Grézard. (1950) Difficultés inhérentes à l'existence d'un lobe azygos lors des interventions pulmonaires endothoraciques. Lyon Chir. 45:98-102.
Berg, R.M., Boyden, E.A. and F.R. Smith. (1949) An analysis of variations of segmental bronchi of the left lower lobe of fifty dissected, and ten injected lungs. J. Thoracic. Surg. 18:216-236.
Boyden, E.A. (1949) A synthesis of the prevailing patterns of the bronchopulmonary segments in the light of their variations. Dis. Chest. 15:657-668.
Boyden, E.A. (1952) The distribution of bronchi in gross anomalies of the right upper lobe, particularly lobes subdivided by the azygos vein and those containing pre-eparterial bronchi. Radiology 58:797-807.
Boyden, E.A. (1953) A critique of the international nomenclature on bronchopulmonary segments. Dis. Chest 23:266-269.
Boyden, E.A. (1955) Developmental anomalies of the lungs. Am. J. Surg. 89:79-89.
Boyden, E.A. (1961) The nomenclature of the bronchopulmonary segments and their blood supply. Dis. Chest 39:1-6.
Boyden, E.A. nad C.J. Hamre. (1951) An analysis of variations in the bronchovascular patterns of the middle lobe in fifty dissected and twenty injected lungs. J. Thoracic Surg. 21:172-188.
Boyden, E.A. and J.F. Hartmann. (1946) An analysis of variations in the bronchopulmonary segments of the left upper lobes of fifty lungs. Am. J. Anat. 79:321-360.
Boyden, E.A. and J.G. Scannell (1948) An analysis of variations in the bronchovascular patterns of the right upper lobe of fifty lungs. Am. J. Anat. 82:27-74.
Bray, E. (1933-34) Grandezze ponderali di alcuni visceri umani in rapporto alle dimensioni esterne dei corrispondenti segmenti coporel. Elaborazione statistica del materiale ruccolta a firenze da Castaldi e Vannuncci. Nota III: Cuore, Pulmoni. Arch. Ital Anat. Embriol. 32:257-274.
Broca, -. (1852) Un poumon divsé en deux lobes complétement séparés. Bulletins et Mem. de la Société Anatomique de Paris XXVII(1):29.
Brown, S. and M. Braverman. (1931) Azygos lobe of the right lung. Radiology 17:575-576.
Cairney, J. (1924) The lobe of the azygos vein. Note on two additional cases. J. Anat. 58:54-58.
Campbell, A.H. and A.G. Liddelow. (1967) Signifcant variations in the shape of the traches and large bronchi. Med. J. Anat. 1:1017-1020.
Campbell, J.M. (1937-38) Bilateral anomaly of the laryngeal saccule. J. Anat. 72:465-466.
Campbell, R.T. (1953-54) Intestinal obstruction with congenital absence of the left diaphragm. Brit. J. Surg. 41:56-60.
Chiene, J. (1870) Note on a supernumerary lobe to the right lung. J. Anat. Physiol. 4:89-90.
Chilaiditzi, D. (1910) Zur Diagnostik angeborener Lungenmissbuildungen. Fortschr. Röntgenstrahlen 15:108-114.
Cleland, J. (1870) Case of the supernumerary lobe of the right lung. J. Anat. Physiol. 4:200.
Coulouma, -. et -. Devos. (1937) Les scissures pulmonaires et leurs variations chez l'homme et les mammifères Assoc. Anatomistes Comptes Rendus 32:112-139.
Crawford, J.H. (1944) Tomographic appearance of the azygos lobe with a description of two cases and a report of seven cases. Brit. J. Radiol. 17:319-322.
Crivellari, C.A.L., de., Newton, E.F. and C.A. Crivellari. (1943) Lóbulo de la azigos normal y patológico. Prensa Méd. Argent. 30:2210-2214.
Dalla Rosa, L. (1889) Beitrag zur Cauistik und Morphologie der Varietaten des menschlichen Bronhialbaumes. Wien. Klin. Wochenschr. 2:437-438, 461-463,483-487.
DeBakey, M., Arey, J.B. and R. Brunazzi. (1950) Successful removal of lower accessory lung. J. Thorac. Surg. 19:304-311.
Debeyre, A., Coulouma, -. et -. Devos. (1938) Les scissures et les cloisons interzonaires du poumon. Assoc. Anatomistes Comptes Rendus. 33:156-164.
D'Hour, H. and J. Crinquette (1951) Orifices bronchoscopiques et anatomic bronchique du lobe moyen. Assoc. Anatomistes Comptes Rendus 38:425-429.
Dovay, E. (1926) Lobe pulmonaire accessoire par anomalie de l'azygos (lobule de Wrisberg). Le sillon creusé dan le poumon a-t-il une conséquence pathologique? Bull. Mem. Soc. Anat. 89:26-31.
Dubey, P.N., Robert, S.L. and K.P. Hardas. (1962) Costomediastinal border of the left pleura. J. Anat. Soc. India 11:87-88.
Duget, -. (1881) Transposition complète des viscères thoraciques et abdominaux. Soc. Biol. Comptes Rendus des Séances et Mémoires. 33:55-58.
Dyson, J.E. (1934) Congenital absence of lung. J. Iowa Med. Soc. 24:442-445.
Ellis, A.G. (1917) Congential absence of lung. Am. J. Med. Sci. 154:33-39.
Elward, J.F. (1936) Roentgen aspects of congenital aplasia of lung. Radiol. 27:667-671.
Epstein, I. 91951) Bronchial adenoma in a supernumerary tracheal lobe: Report of an unusual case. J. Thoracic Surg. 21:362-369.
Etter, L.E. (1947) Variations in the position of the azygos septum and incidence in fifty thousand roentgen examinations. Am. J. Roentgenol. 58:726-729.
Ettig, F. (1924) über die Differentialdignose zwischen einer Pleuritis mediantinalis posterior und der Infiltration eines abnormen Lungenlappens (lobus infracardiacus). Monatsschrift f. Kinderheilkunde 28:207-214.
Falor, W.H. and A.K. Kyriakides. (1949) Ectopia bronchi. J. Thoracic Surg. 252-260.
Favaro, G. (1913) Les cavités pleurales rétrocardiaques de l'homme dans la transposition des viscères. Arch. Ital. Biol. 60:307.
Fergusson, C.F. and E.B. D. Neuhauser. (1944) Congenital absence of the lung (Agenesis) and other abnormalities of the tracheobronchial tree. Am. J. Roentgenology 52:459-471.
Ferry, R.M., Jr. and E.A. Boyden. (1951) Variations in the bronchovascular patterns of the right lower lobe of fifty lungs. J. Thorac. Surg. 22:188-201.
Foster-Carter, A.F. (1946) Broncho-pulmonary abnormalities. Brit. J. Tuberculosis 40:111-124.
Gans, S.L. and W.J. Potts. (1951) Anomalous lobe of lung arising from the esophagus. J. Thoracic Surg. 21:313-318.
Geddes, A.C. (1910) Apparent triplication of the apex of the right lung. J. Anat. Physiol. 45:11-15.
Gennadiew, A.N. (1930) Zur Frage der Morphologie des Lungenläppchens der Vena azygos. Z. Anat. Entwicklungsgesch. 92:178-212.
Gillaspie, C., Miller, L.I. and M. Baskin. (1916) Anomalies in lobation of lungs with review of literature. Anat. Rec. 11:65-75.
Golay, -. (1876) Pneumonie caséeuse double. Anomalie du poumon droit. Bulletins et Mem. de la Société Anatomique de Paris LI(3):282-284.
Gruber, W. (1880) Vierlappige rechte Lunge eines Erwachsenen, in Folge Auftretens eines Spitzenlappens durch einen supernumerären verticalen Einschnitt-Verlauf des Bogens der Vena azygos in diesem Einschnitte. Arch. Pathol. Anat. Physiol. Klin. Med. 81:475-477.
Gruber, W. (1886) Vierlappige rechte Lunge eines Erwachsenen in Folge Auftretens eines Spitzenlappens durch einen supernumeraren-tiefen Einschnitt-Verlauf des Bogens der Vena azygos am Boden dieses Einschnittes. Arch. Pathol. Anat. Physiol. Klin. Med. 103:484-487.
Gruenfeld, G.E. and S.H. Gray. (1944) Malformations of the lung. Arch. Path. 31:392-407.
Hasse, C. (1908) Ein seltener Fall von Lungenschnürung. Anat. Anz. 32:385-388.
Hepburn, D. (1925) Note on a right lung which resembled a left lung in presenting only apical and basal lobes. Journal of Anatomy 59:326-327.
Hjelm, R. and O. Hultén. (1928) Röntgenologische Studien über den Lobus der Vena azygos. Acta Radiol. 9:126-135.
Humphry, L. (1885) Accessory lobe to the left lung. J. Anat. Physiol. 19:345-346.
Jackson, C.L. and J.F. Huber. (1943) Correlated applied anatomy of the bronchial tree and lungs with a system of nomenclature. Dis. Chest 9:319-326.
Jiminez-Martinez, M., Pérez-Alverez, J.J., Pérez-Trevino, C., Rubio-Alverez, V. and J. de Rubens. (1965) Agenesis of the lung with patent ductus arteriosus treated surgically: Report of a case. J. Thoracic Surg. 50:59-62.
Jit, I (1958) Broncho-vascular anatomy of the azygos lobe of the lung. J. Anat. Soc. India 7:19-29.
Jordon, H. (1939) Anomalies of human respiratory system: A proposed classification. Am. Rev. Tuberc. 40:517-521.
Kartagener, M. and A. Horlacher. (1935) Bronchiektasien bei Situs viscerum inversus. Schweiz. Med. Wochenschr. 16:782-784.
Krivinka, R. (1939) Uber einen Fall von linksseitigem Vorkommen des Lobus Wrisbergi. Röntgenpraxis 11:234-237.
Lachman, E. (1942) A comparison of the posterior boundaries of lungs and pleura as demonstrated on the cadaver and on the roentgenogram of the living. Anat. Rec. 83:521-542.
Letulle, M. (1885) Remarques à propos de l’anatomie normale des bronches primitives. Bull. et Mem. de la Société Anatomique de Paris. 1885(2):132-133.
Leudet, E. (1856) Trois bronches naissant de la trachée. Soc. Biol. Comptes Rendus des Séances et Mémoires. 8:54.
Levy, C.S. (1920) Congenital absence of one lung. Am. J. Med. Sci. 159:237-246.
Liang, L.S. and C.A.R. Snell. (1955) The bronchial tree in Indonesians of East-Java (the right upper lobe bronchus). Assoc. Anatomistes, Comptes Rendus 42:924-932.
Lucien, M. and A. Beau. (1951) La systématisation pulmonaire. Ses bases morphologiques et ses modalitiés. Assoc Anatomistes, Comptes Rendus 38:3-92.
MacKenzie, C.F., McAslan, T.C., Shin, B., Schellinger, D. and M. Helrich. (1978) The shape of the human adult trachea. Anesthesiology 49:48-50.
Makhni, S.S. (1957) Some variations of the human lingular bronchi. J. Anat. Soc. India 6:40-43.
Marek, J.J. (1940) Congenital deformity of trachea. Ohio State Med. J. 36:1308.
Mather, J.H. and R. Coope. (1928) Accessory lobe of the azygos vein. Brit. J. Radiol. 1:481-485.
Mitchell, H.E. (1946) Agenesis of the right lung with death following aspiration of froeign bodies into the left lung. Ann. Otol., Rhin. and Laryngol. 55:609-616.
Motti, G. (1893) Anomalie degli organi interni nei malati di mente. Rara anomalia polmonale. Giornale Internazionale delle Scienze Mediche 15:881-892.
Neil, J.H. (1950) Azygos lobes of the lung, and terminology of the bronchopulmonary segments of the bronchial tree. Ann. Otol. Rhinol. Laryngol. 59:409-413.
Nelson, H.P. and G. Simon. (1931) The accessory lobe of the azygos vein. Brit. Med. J. 1:9-11.
Paul, F. 91928) Fehlbildungen im Bereiche der Atmungsorgane. Virchow's Arch. f. Pathol. Anat. u. Physiol. u. f. Klin. Med. 267:295-317.
Piergrossi, A.R. (1948) Sul lobo medio del polmone sinistro. Radiol. Med. 32:154-165. Cited in Exerpta Medica, Sec. 1, Vol. 2, abstract 529, p. 251, 1948.
Pitel, M. and E.A. Boyden. (1953) Variations in the bronchovascular patterns of the left lower lobe of fifty lungs. J. Thoracic Surg. 26:633-653.
Ponfick, -. (1870) Ein Fall von angeborener primärer Atrophie der rechten Lunge. Arch. Pathol. Anat. Physiol. Klin. Med. 50:633-637.
Pozzi, S. 91872) D'une anomalie réversive du poumon droit de l'homme (existence d'un lobus impar). Bull. de la Soc. d'Anthrop. de Paris. 7:161-165.
Raman, T.K. (1944) Azygos lobe of lung. J. Indian Med. Assoc. 21:98-99.
Rao, D.S. (1951) The azygos lobe of the lung. J. Indian Med. Assoc. 21:69.
Rigler, L.G. and L.G. Ericksen. (1933) The inferior accessory lobe of the lung. Am. J. Roentgenol. 29:384-392.
Robbins, R.H. (1935-36) Abnormal azygos pleural fold. J. Anat. 70:579.
Scannell, J.G. (1947) A study of variations of the bronchopulmonary segments in the upper lobe. J. Thoracic Surg. 16:530-537.
Scannell, J.G. and E.A. Boyden. (1948) A study of the variations of bronchopulmonary segments of the right upper lobe. J. Thoracic Surg. 17:232-237.
Schaffner, G. (1898) über den lobus inferior accessorius der Menschlichen Lunge. Arch. Pathol. Anat. Physiol. Klin. Med. 152:1-25.
Schmitt, H. (1938) Mittellappen der linken lunge und seltene Form des Lobus venae azygos. Röntgenpraxis 10:568-571.
Schmitz-Cliever, E. (1950) über das Vorkommen des Lobus venae azygos der linken Lungenseite. Fortschr. Röntgenstr. 72:728-731.
Schugt, H.P. (1940) The piriform sinus. Anatomie and clinical observations with a review of the literature. Arch. Otolaryngol. 31:626-644.
Simpson, G.C.E. (1908) A case of accessory lobe of the right lung. J. Anat. Physiol. 42:221-225.
Smart, J. (1946) Complete congenital agenesis of a lung. Q. J. Med. 15:125-140. Cited in Exerpta Medica, Sec. 1, Vol. 2, abstract 1182, p. 426, 1948.
Smith, F.R. and E.A. Boyden. (1949) An analysis of variations of the segmental bronchi of the right lower lobe of fifty injected lungs. J. Thoracic Surg. 18:195-215.
Stibbe, E.P. (1919) The accessory pulmonary lobe of the vena azygos. J. Anat. 53:305-314.
Stibbe, E.P. (1929) True congenital diverticulum of the trachea in a subject showing also right aortic arch. Journal Anat. 64:62-66.
Suess, E. (1928) Rontgenologie des Lobus venae azygos. Med. Klin. 24:1790-1792.
Teggihalli, M.M. (1955) The azygos lobe. J. Anat. Soc. India 4:49.
Thomas, L.B. and E.A. Boyden. (1952) Agenesis of the right lung. Surgery 31:429-435.
Turner, R.S. (1962) A note on the geometry of the tracheal bifurcation. Anat. Rec. 143:189-194.
Underwood, F.A. and N. Tattersall (1933) The accessory lobe of the azygos vein: A record of fourteen cases, with special reference to heredity as an aetiological factor, and to pathological features of the condition. Tubercle 15:1-12.
Valle, A.R. (1955) Agenesis of the lung. American J. Surg. 89:90-100.
Valle, A.R. and M.L. White, Jr. (1947) Subdiaphragmatic aberrant pulmonary tissue. Dis. Chest 13:63-68.
VanLoon, E.L. and S. Diamond. (1941) Congenital absence of right lung: its occurrence in healthy child. Am. J. Dis. Child. 62:584-589.
Velde, G. (1927) Ein eigentümlicher Schattenstreifen in der rechten Lungenspitze. Fortschr. Röntgensthr. 36:315-318.
Wang, K.P. and H.P. Tai (1965) An analysis of variations of the segmental vessels of the right lower lobe in 50 Chinese lungs. Acta Anat. Sin. 8:408-423.
Wells, T.R., Jacobs, R.A, Senac, M.O. and B.H. Landing. 1990 Incidence of short trachea in patients with myelomeningocele. Pediatric Neurology 6(2):109-111.
Welsch, K. (1928) Ein Fall von Mangel der rechten Lunge. Frankfurter Zeitschr. f. Pathol. 36:192-206.
Wessler, H. and L. Jaches. (1923) Clinical Roentgenology of
the Chest. The Southworth Co., Troy, N.Y.
Woodburne, R.T. (1947) The costomediastinal border of the left pleura in the precordial area. Anat. Rec. 97:197-210.
Wrisberg, H.A. (1777) Observationes anatomicae de vena azyga duplici, aliisque hujus venae varietaibus. Novis Commentariis Societatis Reg. Sci. Gottingen 8:14.
Zawadowski, W. (1930) Le lobule de la veine azygos (lobule de Wrisberg) sa visibilité sur les radiographies pulmonaires. J. Radiol. Electrol. 14:273-282.
Ziegelman, E.F. (1935) Tracheal diverticulum: observatins on a cadaver and results of histiological study. Arch. Otolaryngol. 21:414-425.
Section Top | Title Page
Please send us comments by filling out our Comment Form.
All contents copyright © 1995-2017 the Author(s) and Michael P. D'Alessandro, M.D. All rights reserved.
"Anatomy Atlases", the Anatomy Atlases logo, and "A digital library of anatomy information" are all Trademarks of Michael P. D'Alessandro, M.D.
Anatomy Atlases is funded in whole by Michael P. D'Alessandro, M.D. Advertising is not accepted.
Your personal information remains confidential and is not sold, leased, or given to any third party be they reliable or not.
The information contained in Anatomy Atlases is not a substitute for the medical care and advice of your physician. There may be variations in treatment that your physician may recommend based on individual facts and circumstances.