Comparative thoracic anatomy
- right lung is larger
- has parietal and mediastinal surfaces
- 4 lobes- cranial, middle, caudal and accessory lobes (acessory lobe hangs over the caudal ena cava)
b) left lung –only 2 lobes
c)liver ,stomach are housed inside rib cage
d) heart is more or less in the midline but projects to left
a) right side of heart- right ventrical is more cranial
- gives off pulmonary vesels
- right ventricle-lies ventral because og its embryological origin.
b) left side of heart- has has a groove- interventricular septum which houses the interventricular artery
from coronary artery
c) left ventricle- larger muscle of the ventricles.
d) dorsal mediastinum-esophagus, azygous vein and aorta
a) considerably small
b) a lot of viscera projects forward
c) a triangular field
4)factors limiting thoracic volume
a)curvature of the neck(cervical spine and withers also take up space as the dorso-ventral limit
b)the ribs- the space between the first few ribs are small- it is a site where abolus of food can get
c)a growth in the neck can restrict the food from going down
d)mass of mucle in between the forelimb and trunk-cranial portion of the thorax is covered laterally by
the skeletal miscle of the shoulder and arm. Preventing clinical examination by auscultation and
percussion of the oragans within unless the forelimb is pulled forward.
e) thoracic spine and whither take up alot of space ad the dorso-ventral space in thorax.
R and L pleural cavities- lungs separated by –mediastinal pleura and heart
Equine pleural cavities-‘fenestrations’
6)right and left pleural cavitis
a)there are two pleural sacs line the throacic cavity that contact each other in the median plane to form
-b)the point where the pleura reflects on itself is known as the line of pleural reflection
-c)lungs are separated by mediastinum pleura
- mediastinal space – is small
- the mediastinum contains the heart and all ther thoracic organs except the lungs (
which are in the pleural sacs) - the caudal vena cava whoch indents the right pleural cavity supported by the caval
- heart also separates the right and left lungs.
d)in regions where the mediastinum contains no organs it is relatively thin and may be fenestrated as a
result of an underdeveloped or degenerated lamina propria that separates te two pleural layers .
fenestrations are seen mainly caudal to the heart. This part of the mediastinum is pushed far over to the
left because of the greater mass of the right lung.
e) Horses- due to the adhesion of the right and left lung . an infection of the lung on one side may pass
through easily to the other lung.
f) If one lung collapses due to a pneumothorax can cause the other lung to collapse as well.
Haemothorax- blood into the lung spaces from infection or secondary to pneumothorax can cause
bleeding into the thoracic cavity.
7) Dog lungs- highly lobated and smooth
- only connected by the lung roots.
8) Equine lungs
- not lobated(solid mass), smooth(visceral pleural is smooth and covers the lungs)
- but has functional lobations
- only the accessory lobe is divided by fissure(caudal vena cava) , it is still part of the right lung.
- For the right lung- no middle lobe
9)Ruminant, pig lungs-
a)obated- distinct lobation into cranial , middle and caudal lobes.
b)pig and ox- lobulated(smaller outlines)- looks like a bag of grapes)
-c)hard to diffrentiate between sheep and dog- as they are both lobated.
d)ruminant and pig
-Have tracheal bronchus- it is a branch of the trachea before the bifurcation of the trachea
- it supplies the cranial lobe of the right lung
- cardiac notch is still present-
10)Difference in lungs are lobations, lobulations and tracheal bronchus
-species variation on right side
- coronary groove/sulcus around the heart, lies between the atria and the ventricles and contains
the coronary vessel and fat.
- Is called the circle of blood, and is supplied by 2 coronary arteries a) right coronary artery b) left
coronary artery. And circumflex branch of the vessel
- a) left coronary artery
- 1) the circumflex branch of the left coronary artery: , which extends caudally in the left part of
the coronary sulcus and goes down the interventricular groove
B) right coronary artery has a very short course and is not as large as the L coronar