Thoracic Cavity Contents Flashcards
1
Q
What are the contents of the thoracic cavity?
A
two pleural sacs (right contains right lung and left contains left lung)
mediastinum - midline
2
Q
Describe esophagus location in mediastinum
A
- has cervical, thoracic, short abdominal parts
- thoracic part: runs in dorsal mediastinum from thoracic inlet to esophageal hiatus
- cranial mediastinum: dorsolateral trachea on left side
- caudal mediastinum: ventral to ascending aorta and dorsal to caudal vena cava
3
Q
What is structure 1 and 2?
A
esophagus
4
Q
compare the muscle of esophagus in different species
A
- tunic muscularis skeletal m. throughout in ruminants and dog, but horse, pig, and cat it change to smooth m. caudal to heart
5
Q
describe thoracic trachea
A
- starts as most dorsal visceral structure entering cavity (directly ventral to longus colli)
- in mediastinum inclines ventrally and attains position ventral to esophagus at aortic arch
- terminates near heart base and divides into two principal bronchi
6
Q
What is tracheal bifurcation?
A
- trachea terminates near heart base, it divides into two principal bronchi (primary), occurs at T5
7
Q
What is the order of respiratory passageways from largest to smallest?
A
- trachea –> principal bronchi (right and left) –> lobar bronchi (1/lobe) –> segmental bronchi (each serves one whole bronchopulmonary segment) –> subsegmental bronchi –> true and terminal bronchioles (lack cartilage) –> alveolar ductules –> alveoli
8
Q
describe bronchopulmonary segments
A
- each lobar bronchus divides into many segmental bronchi
- each segmental bronchus and tissue it supplies with air a bronchopulmonary segment (self-contained unit)
- cone shaped with base toward pleura
- can remove a unit
9
Q
What is the tracheal bronchus?
A
- in ruminants and pig
- starts cranial to bifurcation
- serves right cranial lobe
10
Q
what is lung orientation?
A
- horizontal in thorax
11
Q
what are the basic features of lungs?
A
- apex (directed cranial toward thoracic inlet)
- base (diaphragmatic surface)
- lobes (based on division of lobar bronchi within lung parenchyma
- interlobar fissures (separate between lobes)
12
Q
name the lobes of the right lung
A
- right cranial lobe
- middle lobe
- right caudal lobe
- accessory lobe (medial to caudal lobe and surrounds caudal vena cava and phrenic n. see #3)
13
Q
name the lobes of the left lung
A
- left cranial lobe (cranial part and caudal part)
- left caudal lobe
14
Q
what is the hilus?
A
- area on medial surface where structures enter or exit lung
15
Q
what structures enter/exit through hilus?
A
- enter: primary bronchus, bronchial artery, pulmonary artery, autonomic nerves
- exit: pulmonary veins, bronchial veins (satellites of bronchoesophageal artery), sensory nerves, lymphatics
16
Q
what is the root of the lung?
A
- all the collected structures enter/exit hilus wrapped in pleura (double fold)
17
Q
what lobe is most prone to lung lobe torsion and why?
A
- right middle lobe due to its freedom of movement and deep fissures that separate it from other lobes
- occurs in deep chested dogs
- lobectomy (dogs and cats) can survive up to 50% lung loss
18
Q
what is lung lobe torsion?
A
- rotation of lobe along its axis - twists bronchus and pulmonary vessels leading to necrosis
19
Q
discuss differences in ox lung lobes
A
- 2 left lung lobes are the same
- right cranial lobe is supplied by tracheal bronchus which comes off cranial to bifurcation
- right cranial lobe divided into cranial and caudal parts
- same with pigs and camels
20
Q
discuss horse lung lobes
A
- 2 left lung lobes but cranial lobe is not divided into parts
- 3 right lung lobes - no middle lobe
21
Q
what is the cardiac notch?
A
- region where the heart is not overlaid by lung tissue
- triangular space between cranial and middle lobes of rt. lung where borders diverge from each other leaving portion of pericardial wall uncovered by lung tissue
- apex of notch at distal quarter of 4th rib between sternum and CCJ
- a window for needle puncture of pericardium, heart and auscultation or ultrasound exams
- also cardiac notch on left side
- present in all species
22
Q
Where does heavier particles such as fluid travel in lung?
A
- tends to land right cranial and middle lobes due to them being more ventral and gravity
23
Q
where do lighter air-borne particles tend to travel in lung lobes?
A
- inhaled into accessory lobe due to straight trajectory
24
Q
where is the auscultation triangle?
A
- cranial: caudal border of triceps brachii
- dorsal: epaxial muscles
- caudoventral: curved line from olecranon to intercostal space between ribs #16 and #17
25
what are the rules for pleurocentesis or thoracocentesis?
- puncture in middle of ICS
- dorsal to CCJ
- ox and horse at 7th ICS above the CCJ
- horse avoid superficial thoracic spur vein
26
which side of azygous vein is present in carnivores and horse?
- right v. azygos
27
which side of the azygous vein is present in ruminants and discuss its location
- they have both
- runs left dorsal surface of aorta and must make a u-turn to get to R ventricle
- drains into coronary sinus
28
discuss R. azygous vein
- unpaired (carnivores and horse)
- runs along right dorsal surface of aorta
- drains into cranial vena cava
- both veins develop in embryo but left atrophies
29
how many lymphocenters are present in thorax and name them?
- 4
- dorsal thoracic
- ventral thoracic
- mediastinal
- bronchial
30
what lymph nodes are present in dorsal thoracic lymph center?
- intercostal lnn
31
what lymph nodes are in ventral thoracic LC?
- sternal lnn
32
what lymph nodes are present in mediastinal LC?
- represented by cranial mediastinal lnn in all species
- caudal mediastinal lnn (absent in carnivores, huge in ruminants)
33
what lymph nodes are in bronchial LC?
- rt. lt. and middle tracheobronchial lnn
34
what special lymph node do ruminants have and what is clinical significance?
- caudal mediastinal lymph node
- a single large elongated lnn between aorta and esophagus
- if enlarged it will press on esophagus and dorsal vagal trunk which causes vagal indigestion and no eructation (gas cannot exit)
- #20 is vagus nerve
35
what are different in city dogs and how?
- tracheobronchial lnn. and pulmonary are darker
36
what is significant about sternal lymph node?
- lymph from peritoneal cavity drains into sternal ln. via afferent lymphatic duct which perforates diaphragm near costodiaphragmatic recess and runs along internal thoracic vessels covered by transversus thoracic m.
- may drain cranial mammary glands, so may take up tumor cells
37
what is unique about T6 as a landmark?
- longus colli m. arises from T6
- thoracic duct deviates from right to left at T6
- on lat rad carina shows up as circular dark spot at T6
- tracheobronchial lymph nodes located in relation to carina, can be ID if abnormal rad
38
describe thoracic duct and clinical significance
- transports fat absorbed from digestive tract to venous circulation, material within called chyle
- can be visible on left lat side of esophagus cranial to aortic arch - avoid in sx
39
What is at 1
- thoracic duct
- arises cisterna chyli between 2 crura and runs cranially along rt dorsal surface of aorta, at T6 crosses cranioventrally to left in groove between esophagus and left longus colli
- then opens in area where left sub and external jug veins join
40
what is chylothorax?
- when lymph accumulates in thorax cavity
- if lymph vessels cut they remain open due to lack of clotting factors in lymph
- will not resolved unless sx intervention taken to ligate duct
41
where is the heart in a dog?
- middle mediastinum and partially left to median
- ribs 3 to 6
- 45 degree axis
42
where is heart in the cat?
- middle mediastinum
- partially left to median
- ribs 4-7 (more caudal then dogs)
- 25-30 degree axis
43
where is heart in horse?
- ICS 2-6
- more perpendicular than carnivores
44
where is the heart in ox?
- ICS 2-5
45
what is the pericardium?
- triple fibroserous sac enclosing the heart and the beginnings of large blood vessels connected to it
- serous pericardium and fibrous pericardium
46
what is the fibrous pericardium?
- condensation of endothoracic fascia and it is tightly adhered to parietal serous pericardium
- mediastinal pleura is superficial to it
47
what is cardiac tamponade?
- pericardial sac fills with fluid
- fibrous nature of parietal pericardium prevents expansion and heart is compressed (especially thin R ventricle)
48
what is pericardiocentesis?
- insert needle or catheter from right side @ 4th or 5th ICS between sternum and CCJ
- dx or relieve inc pressure in cavity
49
what are the main structures of the heart
- base (2 atria)
- apex (left ventricle)
- 4 chambers: right and left atria, right and left ventricles
50
what part of heart is cranial?
right
51
what part of heart is caudal?
left
52
what are the grooves of the heart?
- coronary groove
- two interventricular grooves
- intermediate groove (ruminants)
53
what is the coronary groove?
- separation of atria and ventricle
54
what are the interventricular grooves?
- two of them indicate interventricular septum inside
- paraconal on left
- subsinuosal on right
55
what is the left side of heart called?
- auricular surface
- see auricles with pulmonary trunk in between
56
what is the right side of heart called?
- atrial surface
- see cranial and caudal venae cavae entering right atrium
57
what are the septa in heart?
- divide left and right sides
- interatrial septum
- interventricular septum
58
what are the valves of the heart?
- semilunar valves
- atrioventricular valves (AV)
59
what are the semilunar valves?
- between ventricles and great arteries
- aortic and pulmonary
60
what are the AV valves?
- between atria and ventricles
- tricuspid (right blue side) and mitral (left aka oxygenated side)
61
what is/are branch of aortic arch in horse?
brachiocephalic trunk
62
what is/are branches of the aortic arch in carnivores?
- brachiocephalic trunk
- left subclavian artery
63
what is the best places to auscultate heart in dog?
- PAM aka 345 on left side
- pulmonic valve in 3rd ICS at CCJ
- aortic valve in 4th ICS at point of shoulder
- mitral valve in 5th ICS low along sternal border
- tricuspid on right side in 4th ICS at CCJ
