Pleural Membranes, Reflections & Recesses & Mediastinum Flashcards
how is the mediastinum divided
subdivided into cranial, middle and caudal
which mediastinum contains the heart
middle mediastinum
what are the structures
what is the plica vena cava
the caudal vena cava runs outside the mediastinum –> burrows between the caudal lobe of the right lung and the accessory lobe –> it has its own reflection of the pleura called the plica vena cavae (covering and supporting the caudal vena cava)
what is the pericardium
serous sac surrounding the heart
what are the structures associated with the cranial mediastinum
esophagus, thoracic duct, branches of aorta, thymus, trachea, cranial vena cava
where is the thymus found
ventral part of the cranial mediastinum
what are the structures in the cranial mediastinum
what structures are associated with the middle mediastinum
thoracic duct, aorta, esophagus, azygos vein, pulmonary trunk, principle bronchi, heart, pericardium
what are the structures
what comprises the largest part of the middle mediastinum
heart within the pericardium
what are the structures associated with the caudal mediastinum
the liver projects cranially up under the diaphragm
what occurs to the plica vena cava in the caudal mediastinum
plica vena cava-parietal pleura of right sac is reflected over the caudal vena cava –> forms the mediastinal recess, the accessory lobe of the right lung sits in this recess
what are the structures of the caudal mediastinum
what does the visceral pleura form
the pulmonary ligament
how does the pulmonary ligament form
reflection of the visceral pleura at the medial surface of each lung as it continues onto the mediastinum
forms the pulmonary ligament which attaches caudal lobe of each lung to the diaphragm
what is the pleural reflection
line or curvature that occurs when a fold is made so that the pleura can change direction
what and where is the costomediastinal recess
where the costal and mediastinal (parietal) pleura meet ventrally
ventral border of the lung moves into this during inspiration
what is this structure
what is the blue shaded area
costal/diaphragmatic pleura
what is the costodiaphragmatic reccess
parietal pleura
basal border of lung moves in and out of this recess
costodiaphragmatic line of pleura reflection is the most caudal extent of this recess
what is the pleural cupula
parietal pleura recess
reflection of costal pleura and mediastinal pleura
projects beyond first rib –> apex of each lung moves into this space during inspiration
vulnerable to trauma
what are the parietal pleura regions
costomediastinal recess
costodiaphragmatic recess
pleural cupula
what are these structures
what are these structures
what is the clinical importance of the costodiaphragmatic line (CDL) of pleural reflection
in horses and dogs the CDL follows the curve of the costal arch but is about a hands breadth more cranial and dorsal
in the bovine the line is placed more cranial and dorsal to the costal arch than in other species
what are these structures
extent of the peritoneal cavity that is in direct contact with the thoracic wall
implications for surgery
what are anatomical obstacles to percussion and ausuculation of the lungs
- cranial boundary: caudal edge of the triceps brachii muscle
- dorsal boundary: runs parallel to the vertebral column but is restricted by epaxial muscles –> horse and bovine: line from the tuber coxae to the caudal angle of the scapula
- caudoventral boundary: corresponds to basal border of the lung at the end of expiration. Line from the 5th costochondral junction to the dorsal end of the 2nd last rib. Cranially ends near the olecranon process in the standing animal
what is the minimum area for ausculation and percussion of the lungs
area of contact between the lung and thoracic wall at the end of expiration
what occurs to the minimum area in the diseased state
decreases if the lung partially collapsed (pneumothorax or pleural effusion)
increases if the lung becomes enlarged (alveolar emphysema)
what influences the min area for asuculation and percussion
variations in rib # and conformation of the thorax
large in horse, small in bovine, intermediate in dog and pig
