Book - Handbook of Pathological Anatomy 2.11
|Embryology - 29 Nov 2020 Expand to Translate|
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- Ligaments: I. Trunk | II. Head | III. Extremities Muscles: I. Trunk | II. Head | III. Extremities Angiology: I. Heart | II. Body or Aorta Arteries | III. Body Veins| IV. Pulmonary Artery | V. Pulmonary Veins | VI. Lymphatic System | VII. A Comparison of Vascular System Nervous System: I. Central Nervous System
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Section IV. Pulmonary Artery
§ 1633. The pulmonary artery (A. pulmonalis, s. vena arteriosa) is generally a little smaller than the aorta, and arises from the summit or apex of the right ventricle, ascends to the left and backward, and presents a convexity upward and forward on the right, while it is concave downward and backward to the left. At its lower part it covers the commencement of the aorta in front, and in the rest of its course it proceeds on the left side of this artery, below its arch and on the left of its trunk. After passing through about two inches, it divides into a right and a left branch. From its bifurcation arises a round solid cord, a line thick and about four lines long, called the arterial ligament ( L . arteriosum). This is the remains of a duct, the arterial canal, or canal of Botal ( ductus arteriosus, s. Botallianus ), or the right root of the aorta, the changes of which we shall describe more minutely when giving the history of the fetus. This cord ascends a little obliquely to the left, toward the commencement of the ascending aorta, and is attached to its anterior part so firmly that it cannot be separated without tearing. A cylinder of bone, more or less apparent, generally forms within it, even in young people, shortly after the canal is completely effaced, in accordance with this general law, that ossification marks a diminution of the vital activity in the organs.
The two branches separate from the trunk at a right angle, to go each to its corresponding lung.
The right branch proceeds transversely to the right, directly behind the aorta and the descending vena-cava, before the right bronchia. It is not only larger than the left, which depends on the greater size of the right lung, but it is also longer than it by the whole breadth of the aorta. It also penetrates more deeply into the fissure of the lung, and divides from above downward, before coming to the substance of the organ, into two branches, an upper, which is smaller, and the inferior, which is much larger.
The upper branch goes upward, and at the moment it enters the lung, divides again into two ramuscules, of which the lower is also the larger, while the upper bifurcates in turn.
The lower branch descends behind the superior pulmonary vein, to arrive at the middle and inferior lobes of the lung. It divides, opposite the middle lobe, into two branches, an anterior and superior, which bifurcates also before it enters the most internal part of the middle lobe, the other is much larger and lower, and, covered at first before by the middle branch of the right bronchia, goes to the lower lobe, and divides into three branches before it penetrates into it.
The left branch of the pulmonary artery is shorter and narrower, ascends a little on the left, goes toward the left lung, passes before the origin of the descending aorta, goes outward in the fissure of this lung, between its upper and its lower lobe, and divides into upper and lower branches. Those of its branches which arise the first, the posterior, are generally smaller than the anterior, which arise afterward ; and those which ascend into the superior lobe are smaller but more numerous than those which descend into the lower. All generally bifurcate when they enter this organ.
The two branches of the pulmonary artery and all their ramifications are situated above and before the bronchia and their subdivisions.
§ 1634. The congenital anomalies of the pulmonary artery are,
1st. The total absence.
2d. Its obliteration.
3d. A great narrowness.
4th. Its insertion in the aorta : then it sometimes forms only one trunk, and sometimes its two principal branches arise from two separate places.
5th. Its insertion in the left ventricle.
6th. Its insertion in the two ventricles by the perforation of the base of the interventricular septum.
7th. The existence of two or four valves, instead of three.
Sth. The permanence of the arterial canal.
9th. The insertion of this canal in the subclavian vein.
10th. Finally, the insertion of this canal in the right ventricle.
Cite this page: Hill, M.A. (2020, November 29) Embryology Book - Handbook of Pathological Anatomy 2.11. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Handbook_of_Pathological_Anatomy_2.11
- © Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G