LAB 6
THE
INTERNAL THORAX
I. Histology
1. Lung Tissue Slide - Note the alveoli
2. Trachea - Note the hyaline cartilage and the epithelial lining. Also
note the presence of adipose tissue and elastic tissue.
II. Skeletal Material - None
III. Models
A. Heart, Mediastinum and Diaphragm
A. Diaphragm
B. Diaphragmatic pleura
C. Mediastinal adipose tissue
D. Parietal pericardium
E. Sternum and costal cartilage
F. Stomach
G. Spleen
H. Visceral and parietal peritoneum
I. Liver
J. Portal vein
K. Hepatic artery
L. Hepatic duct
M. Esophagus
N. Thoracic aorta
O. Azygos vein
P. Thoracic duct
Q. Intercostal artery and vein
R. Prevertebral adipose tissue
S. Eighth thoracic vertebra
T. Intervertebral disc
U. Hemiazygos vein
V. Posterior mediastinal lymph nodes
W. Esophageal artery
X. Right vagus nerve
Y. Left vagus nerve
Z. Phrenic nerve, artery and vein
1. aorta
2. brachiocephalic (innominate) artery
3. left common carotid artery
4. left subclavian artery
5. superficial cardiac plexus with entering cardiac nerves and ganglion
6. left vagus nerve
7. recurrent laryngeal nerve
8. ligamentum arteriosus
9. left pulmonary artery
10. left bronchus
11. left bronchial artery
12. pulmonary nerve plexus
13. intercostal arteries
14. thoracic duct
15. azygos vein
16. esophagus
17. right vagus nerve
18. right bronchial artery
19. trachea
20. right main bronchus
21. right pulmonary artery
22. tracheobronchial lymph nodes
23. right ventricle
24. left ventricle
25. left atrium
26. right atrium
27. right auricle
28. conus arteriosus
29. left auricle
30. apex
31. pulmonary artery
32. aorta
33. pericardium
34. superior vena cava
35. right coronary artery
36. anterior cardiac veins
37. left coronary artery
38. anterior interventricular artery
39. circumflex artery
40. great cardiac vein
41. marginal branch of left coronary artery
42. oblique vein of left atrium
43. coronary sinus
44. dorsal interventricular vein
45. left dorsal ventricular vein
46. inferior vena cava
47. azygos vein
48. left pulmonary veins
49. right pulmonary veins
50. marginal branch of right coronary artery
51. coronary sulcus
52. anterior interventricular sulcus
53. crista terminalis
54. sinoatrial node
55. atrioventricular node
56. opening of coronary sinus
57. limbus fossa ovalis
58. fossa ovalis
59. valvula venae cavae
60. musculi pectinati
61. tricuspid valve, anterior cusp
62. tricuspid valve, medial cusp
63. tricusid valve, posterior cusp
64. crista supraventricularis
65. tricuspid valve, anterior cusp
66. tricuspid valve, posterior cusp
67. tricuspid valve, medial cusp
68. anterior papillary muscle
69. posterior papillary muscle
70. septal papillary muscle
71. trabeculae carneae
72. right branch of bundle of His
73. moderator band
74. pulmonary conus
75. pulmonary semilumar valve, posterior cusp
76. pulmonary semilunar valve, right anterior cusp
77. pulmonary semilumar valve, left anterior cusp
78. fossa ovalis, left atrial side
79. opening of pulmonary vein
80. bicuspid valve, anterior cusp
81. bicuspid valve, posterior cusp
82. anterior papillary muscle
83. chordae tendineae
84. posterior papillary muscle
85. trabeculae carnae
86. aortic semilunar valve, right anterior cusp
87. aortic semilunar valve, left anterior cusp
88. aortic semilunar valve, posterior cusp
B. Heart (Greatly Enlarged)
1. right auricle
2. right ventricle
3. left ventricle
4. anterior ventricular artery (branch of right coronary artery)
5. coronary sinus
6. right coronary artery
7. left auricle
8. left atrium
9. apex of heart (left ventricle)
10. posterior descending branch, right coronary artery
11. anterior cardiac veins (marginal veins)
12. middle cardiac vein (in posterior interventricular groove)
13. small cardiac vein (variable)
14. interventricular branch of left coronary artery and great cardiac vein
15. innominate artery
16. left common carotid artery
17. left subclavian artery
18. superior vena cava
19. inferior vena cava
20. descending aorta
21. left recurrent laryngeal nerve and arch of aorta
22. right pulmonary artery (close division into main and eparterial part)
23. left pulmonary artery
24. left pulmonary veins
25. ligamentum arteriosum (this is the obliterated ductus arteriosus)
26. left phrenic nerve
27. thoracic aortic sympathetic plexus
28. right coronary artery
29. posterior left ventricular artery (in this model from coronary artery)
30. projection of bifurcation of trachea
31. posterior interventricular artery (from right coronary artery)
32. right pulmonary veins
33. projection of esophageal vagal plexus in relation to heart
34. right and left vagus nerve
35. superficial cardiac plexus of autonomic nervous system
36. pulmonary trunk
37. ascending aorta
38. arch of aorta
39. bifurcation of pulmonary trunk
40. posterior left ventricular artery and vein
41. valve of inferior vena cava
42. musculi pectinati
43. fossa ovalis
44. valve of coronary sinus
45. cristaterminalis (position of sinutrial mode of cardiac conducting system)
46. atrioventricular node (cardiac conducting system)
47. atrioventricular bundle (right septal division)
48. infundibulum of right ventricle
49. tricuspid valve and chordae tendineae
50. mitral (bicuspid) valve chordae tendinese
51. papillary muscle (inferior)
52. papillary muscle (anterior) and moderator band
53. trabeculae carneae
54. pulmonary valve
55. interventricular septum
56. cavity of left atrium
57. aortic valve
58. papillary muscle (inferior)
59. trabculae carneae
60. left septal division of atrioventricular bundle
61. pectinate muscles
62. papillary muscle (superior)
63. membraneous part of interventricular septum and aortic vestibule
C. Lung with Alveoli (model 1)
A diagrammatic representation of a pulmonary lobule with cartilaginous bronchi and non-cartilaginous bronchioles. The vertical distances of the bronchial tree
are greatly shortened. Some of the alveoli show the capillary network, others show the
reticulum of elastic fibers. The network of smooth muscle is also shown. Mucous
membrane -yellow-red; gland - green; cartilage - light blue; muscle - brown; elastic fibers - black; pulmonary vein - carmine; pulmonary artery - violet; bronchial artery - vermilion;
bronchial vein - blue; lymph vessels - orange; nerves - yellow. The back of the model
shows the circulation within the pulmonary lobule and in the pleural cover.
On account of anatomical differences the bronchial system is divided into the
following sections: (the rings of cartilage on the major bronchi are not shown.)
1. The intra-pulmonary bronchi have only cartilaginous plates.
2. Non-cartilaginous bronchioles divide into:
3. respiratory bronchioles of 1st, 2nd and 3rd order. The respiratory bronchiole has lateral hemispherical protrusions, the
4. alveoli - the actual respiratory elements of the lung. The respiratory
bronchioles of 1st, 2nd and 3rd order are distinguished by their varying densities of
alveoli. Beyond the respiratory bronchioles begin the lung tissues that serve the
external breathing apparatus. The lining of the bronchi is composed of
5. mucous membrane, which lies in longitudinal folds when the lung is
relaxed. A strong network of longitudinal
6. elastic fibers (black) runs through the sub-epithelial connective tissue.
The latter also contains
7. smooth muscle (brown) running at first in circular, then in spiral direction.
Its contraction, together with the filling of the
8. pulmonary plexus of the bronchial vein leads to a narrowing of the air
passage. The
9. mucous glands of the bronchi can penetrate deep into the outer
10. fibro-cartilaginous layer through gaps in the cartilaginous framework.
Precise information on the number of alveoli is not available. Estimates vary between
150 and 1,800 million. Physiologists estimate the respiratory surface area attained by
the presence of alveoli to be between 50 and 90 square meters. The diameter of the
alveoli varies between .15 and .6 mm. The width increases with age. The
11. pulmonary pleura shows the
12. limiting membrances with translucent alveoli, the layer of
13. dense capillaries, the layer of
14. collaginous fibers, the layer of
15. elastic fibers, and the
16. epithelium
The dense arrangement of elastic fibers (black) makes the lung the most elastic
of all the organs of the body. The elastic begin in the pleura and end in the finest branches in the wall of the alveoli.
Pulmonary and pleural circulation
The right side of the heart sucks the dark venous blood of the body through the
vena cavae, and that of the heart wall through the coronary sinus and pumps it through
the pulmonary trunk and pulmonary arteries to the lungs for oxygen enrichment. Simultaneously, the left side of the heart sucks the pale red oxygenated blood from the pulmonary veins and pumps it through the aorta into the systemic circulation; thus the
two circulatory systems function side by side. The right side of the heart containing
venous blood supplies the pulmonary circulation.
The lung contains two vascular systems. The vessels of the pulmonary circulation
bring the blood directly from the heart into the capillary circulation of the alveoli, and
from there back to the heart. These are the pulmonary arteries and veins. Their
circulation directly serves the metabolism of the entire organism. The systemic supply,
which nourishes the lung tissues, is carried by the bronchial arteries which are the
branches of the aorta. The bronchial veins opens mainly into the azygos and hemiazygos veins.
The pulmonary arteries are of the elastic type (like the aorta) and run together
with the bronchi into the larger lung segments. They enter the lobules as arterioles,
together with the terminal bronchioles. The arterioles reach the capillary network of the alveoli together with the alveolar duct.
The pulmonary veins take another route. They collect at the tips of the alveoli
and run in the interlobular septa to the larger bronchi. From here, bronchus, artery
and vein run together to the hilum of the lung. The veins are firmly embedded in the pulmonary connective tissue. Between the pulmonary circulation and the systemic
blood supply are arterial anastomoses. Numerous arterio-venous anastomoses are also present in the visceral pleura, in which the terminal branches of the bronchial arteries communicate with interlobular branches of the pulmonary artery.
17. bronchial vein plexus
18. pulmonary vein
19. pulmonary artery
20. bronchial artery
21. anastomosis between bronchial artery and pulmonary vein
22. alveolar capillary network
23. anastomosis of an obstructed artery with pulmonary vein
24. dense capillary network
25. anastomosis between pulmonary artery and vein
Network of lymph vessels
The visceral pleura contains a network of lymph vessels. The larger vessels
follow the borders of the lobules. There are numerous small subpleural lymph nodes.
The endothelia of these lymph vessels absorb dust particles, and this can be seen as a darkening of the surface of the lung. From there interlobular lymph vessels follow the
venules to bronchial lymph nodes. Lymph nodes lie at the bifurcation of the bronchi -
even in the smallest branches. The lymph vessels, which carry the lymph from the
bronchial wall also open into the bronchial lymph nodes. There are no lymph vessels
in the alveolar wall.
Nerve supply
Groups of autonomic ganglion cells occur in many places in the bronchi as in the trachea. Together with their sympathetic and parasympathetic fibers they form the
pulmonary plexus which regulates the dilation of the blood vessels and also the
function of the smooth muscle of the bronchioli and the alveolar ducts.
C.
Model II
The model shows section of alveoli (diameter: 0.1 - 0.5mm). On the front are alveoli with the alveolar epithelium, the "anucleate discs" and the translucent layer beneath.
On the back are shown (1) capillaries with the lattice fiber network and the connective
tissue stroma and the epithelial cells - here seen in niches (3) in the capillary mesh. The
blood capillaries in the alveolar wall consist of an endothelial tube, and a basal membrane with reticulated circular fibrils (2). The tortousity of the capillaries is eliminated during inspiration. The connective tissue framework of the alveolar wall (4) is part of the fibrous system extending throughout the organ that consists of delicate collagenous fibers as
well as reticulated fibrils. The alveolar wall is surrounded by a basket-like framework of elastic fibers (5). This permits a reversible stretching of the alveoli up to three times their diameter. At the openings of the alveoli the thick elastic fibers form characteristic
peripheral rings. Together with smooth muscle fibers these form the alveolar arches (6).
This musclature regulates the width of the orifices and the tension of the elastic fibrous framework.
The front of the model shows alveoli with the alveolar epithelium (7) and the
"anucleate discs." The alveolar epithelium is the continuation of the epithelium of the respiratory bronchiles and lines the alveolar ducts and alveolar sacs: it is single-layered,
flat and lies in direct contact with the inspired air. Four tissue layers separate the
capillary blood from the alveolar air: the capillary endothelium, two basal membranes
and the alveolar epithelium. The connective tissue can be included as a fifth layer.
Oxygen and carbon dioxide must pass through these layers during the gaseous exchange.
The alveolar wall is interrupted by (8) alveolar pores that connnect alveoli to each other. The fibrinous threads occuring in pneumonia can jut into neighboring alveoli
through these tiny openings.
(9) afferent and
(10) efferent capillary vessels
D.
Model of lung with trachea
attached (Note the following)
LEFT LUNG
Frontal Section
(a) Oblique fissure
(b)(c) Left Principalis Bronchus.
(d)(e) Branches of Pulmonary Artery
(f)(g) Branches of Pulmonary veins
20. Base of Lung
21. Apex
22. Groove for Left Subclavian Artery
23. Groove for Aorta
24. Costal Surface
25. Mediastinal Surface (inner surface)
26. Diaphramatic Surface
27. Inferior Border
28. Hilum
29. Superior or Upper Lobe
30. Inferior or Lower Lobe
31. Oblique Fissure
32. Left Pulmonary Artery
33. Left Pulmonary Veins
RIGHT LUNG
34. Base of Lung
35. Apex
44. Superior lobe
45. Middle lobe
46. Inferior lobe
47. Oblique fissure
51. Right Pulmonary Artery
52. Right Pulmonary Veins
IV. Dissection
A. General Internal Thorax
66. Internal Thoracic A.
67. Internal Thoracic V.
68. Transversus Thoracis
69. Cut edge of Diaphragm
70. Diaphragm
71. Left Lung
72. Right Lung
73. Left phrenic N.
74. Pericardium
75. Aorta
76. Pulmonary Trunk
77. Superior Vena Cava
78. Left Innominate V.
79. Right Innominate V.
80. Right Auricle
81. Left Vagus N.
82. Left Subclavian V.
83. Left Jugular Vein
84. Left Common Carotid
85. Left Subclavian A.
86. Brachiocephalic A.
87. Right Common Carotid
88. Right Subclavian A.
89. Left Ventricle
90. Right Axillary V.
91. Right Axillary A.
92. Median N.
93. Ulnar N.
94. Axillary N.
95. Musculocutaneous N.
96. Radial N.
B.
Separate
Hearts
HEART #1
97. Right Atrium
98. Superior Vena Cava
99. Musculi Pectinati
100. Left Auricle
101. Tricuspid Valve Cusp
102. Chordae Tendinae
103. Papillary Muscle
104. Moderator Band
105. Right Ventricle - note trabeculae carni
106. Pulmonary Semilunar Valve
107. Pulmonary Trunk
108. Aorta
109. Brachiocephalic A.
110. Left Common Carotid
111. Left Subclavian A.
HEART #2
112. Mitral Valve Cusp
113. Chordae Tendinae
114. Papillary Muscle
115. Left Ventricle
116. Aortic Semilunar Valve
117. Aorta (opened up)
118. Opening to Right Coronary A.
119. Left Coronary A.
120. Circumflex A.
121. Ant. Interventricular Coronary A.
122. Left Auricle
HEART #3
123. Crista Terminalis
124. Opening of Coronary Sinus
125. Superior Vena Cava
126. Inferior Vena Cava
127. Fossa Ovalis - note thinness of interatrial septum
128. Left Atrium
129. Right Atrium
130. Aorta
131. Right Pulmonary A.
132. Left Pulmonary A.
133. Right Ventricle - note thickness of myocardium
134. Left Ventricle - note thickness of myocardium
135. Interventricular Septum
136. Coronary Sinus
C. Thorax - POSTERIOR WALL
137. Diaphragm
138. Left Lung
139. Left Phrenic N.
140. Aorta
141. Right Vagus N.
142. Trachea
143. Right Bronchus
144. Left Bronchus
145. Esophagus
146. Azygos V.
147. Hemiazygos V.
148. Inferior Vena Cava
LEFT
LUNG HILUS
149. Left Bronchus
150. Left Pulmonary A.
151. Left Pulmonary V.
152. Lingula
RIGHT LUNG
153. Superior Lobe
154. Median Lobe
155. Inferior Lobe
EXCISED HEART
156. Ligamentum arteriosum
157. Aortic Arch
158. Right Subclavian A.
159. Right Common Carotid
160. Left Common Carotid
161. Left Subclavian
162. Pulmonary Trunk
V. Audio - Visual Material
A.. The following charts may help you with the circulation in the thorax.
