Thorax II Flashcards
1
Q
How many compartments is the thoracic cavity divided into?
A
3 compartments:
Left, right and centre
˙.˙ positioning of heart, left and right may not have same dimensions
2
Q
Why is the thoracic cavity larger than the actual lungs?
A
Allows expansion of the lungs up to a certain point eg. during exercise
= recess area
3
Q
What is the pleural membrane?
A
Thin serous membrane that lines the thoracic cavity and envelopes the lungs
4
Q
What are the types of pleural membrane?
A
Parietal - lines the inner wall of the thoracic cage and protects it
Allows expansion lungs
Visceral - lines the lungs
Continuous with mediastinal pleura at the root of the lung
5
Q
List the subdivisions of the parietal pleura
A
Cervical - covers apex of lung
Costal - covers the thoracic wall
Mediastinal - covers mediastinum
Diaphragmatic - covers diaphragm
6
Q
What is the pleural cavity?
A
Potential space between the parietal and visceral layers
Contains no structures
Kept moist by a small amount of pleural fluid
7
Q
What is pleural fluid?
A
Small amount of lubrication that allows the lungs to expand without friction
Only when there is chest pain, get symptoms
8
Q
Where is the pulmonary ligament and what does it do?
A
It is a fold of pleural membrane, that attaches the lungs, medially, to the mediastinum
It is inferior to the root of the lung
9
Q
Describe the filling of the pleural recesses
A
Deep inspiration - lungs fill the pleural cavity
Quiet respiration - lungs don’t occupy some parts of the cavity - leave the pleural recess
10
Q
Name the pleural recesses
A
Costo-diaphragmatic recess
Costo-mediatinal recess
11
Q
What is a pneumothorax?
A
Entry of air in the pleural cavity
12
Q
How does a pneumothorax occur?
A
Lungs and pleural sac may be injured through wounds to the neck
Causes air to enter the pleural space
Breaks the surface tension, usually keeps cavity (bet parietal and visceral pleura) open
Air pushes on the outside of the lung = lung collapse
.˙. pleural cavity (normally a potential space) becomes a real space
13
Q
How can you treat a pneumothorax?
A
By inserting a needle/chest tube between the ribs to remove excess air = needle aspiration
14
Q
What is a life threatening condition?
A
Tension pneumothorax
15
Q
How is the lung positioned in the pleural sac?
A
Pushed into pleural sac like fist pushed into slack balloon
Allows structures to pierce through in lung cavity
16
Q
What is the appearance of a healthy lung and an unhealthy lung?
A
Healthy = light pink
children and young people who live in a clean environment
Unhealthy = dark and mottled
People who live in urban or agricultural environments - esp. those who smoke
˙.˙ accumulation of dust and carbon, irritants inhaled in tobacco
BUT lungs are capable coping with considerable amounts of carbon w/o being adversely affected
17
Q
What are the surfaces of the lungs?
A
Costal, Diaphragmatic and cardiac, vertebral
18
Q
What are the borders of the lung?
A
Anterior, inferior (diaphragmatic side) and posterior borders
19
Q
How many fissures do the right and left lung have?
A
Right - 2 fissures
Horizontal and oblique
Left - 1 fissure
Oblique fissure
20
Q
Is the horizontal fissure always open?
A
No, it may be just a depression
21
Q
What are the surface markings of the oblique fissure?
A
Left and right lung
Surface markings - spinous process at T4
Crosses 5th intercostal space laterally
Follows the contour of the right 6th rib anteriorly
22
Q
What are the surface markings of the horizontal fissure?
A
Right lung only
Right 4th costal cartilage
meets oblique fissure approx. 5th intercostal space, mid-axillary line
23
Q
How many lobes do the right and left lung have?
A
R = 3
L = 2
Left superior lobe runs all way down to lower end of heart
T5 dermatome - nipple line, have axilla separation of the lobes
24
Q
What is the accessory lobe?
A
Azygous lobe - right lung
approx 1% people have it
In these cases azygous vein may arch over the apex of the right lung (and not over right hilum)
= isolation medial part apex as azygous lobe
25
What structures make impressions on the right and left lobe?
Right - azygous vein, subclavian artery, SVC
Left - arch aorta, left common carotid, subclavian arteries
26
What is the hilum of the lung?
Place where structures enter and leave the lung
Triangular depression - where connection between parietal pleura and visceral marks meeting point between mediastinum and pleural cavities
Separation of pericardium and pleura
27
What is the root of the lung?
```
Collection of structures that connect the lung to the mediastinum
Include:
Pulmonary arteries and veins
Primary bronchus
Bronchial arteries
Pulmonary nerve plexus
Lymphatics
```
28
What level does the trachea bifurcate and into what?
At level T4
Into 2 main bronchi - L+R
1 for entering into each hila of the lungs
29
List the branching of the trachea
Trachea -> L+R primary bronchus -> lobar/ secondary bronchi -> segmental/tertiary bronchi
30
Is the branching at T4 symmetrical?
No, because of the positioning of the heart
| Right bronchus more vertical than the left.
31
What is the clinical significance of the right bronchus being more vertical?
Important in paeds
| Whatever children inhale, more likely to end up in right lung because it's more vertical
32
Where may lymph nodes be found?
Bronchial lymph nodes may be found at the root.
Often black ˙.˙ pollution - deposition carbon-based particles in airway
Eventually results in endobronchial and parenchymal fibrosis
Non-smokers get anthrocosis
33
What is the positioning of the structures in the root?
Bronchus at back
| Artery above vein
34
What is the cardiophrenic angle?
| What is the costophrenic angle?
```
Cardiophrenic = Angle between the heart and the diaphragm
Costophrenic = angle between diaphragm (-phrenic) and the ribs (costo-)
```
35
How many anterior ribs should you be able to count on an X-ray?
5-7 anterior ribs
36
What colour is air on an X-ray?
Black
37
What is the cardiothoracic ratio?
Comparison between cardiac diameter and the thoracic diameter
Cardiac diameter = apex of heart to right atrium
Thoracic diameter = one costal end to the other
Heart should be no larger than 50% of the thoracic diameter normally
38
What is a super-black region on an X-ray indicative of?
Air in the wrong area
Important when looking at lung parenchyma - to see if deep breath filling space
Pneumothorax X-rays can see an extra black region
39
What is the trachea composed of?
15-20 C-shaped cartilages/ tracheal rings
Have a septum at the back
Lined w/ ciliated columnar epithelium - helps beat mucus
40
What happens in lobar pneumonia?
Lobar areas affected, segmental bronchi collapse in areas and cause problems
41
Describe the course of the phrenic nerve over the lungs
| L+R
Left - descends along left side subclavian artery, crosses the vagus nerve superficially as approaches aortic arch
crosses anterior to root left lung, descends across the pericardium to diaphragm
Right - lies lateral to right brachiocephalic vein and SVC
Runs ant to lung of the root, across pericardium to diaphragm
42
Describe the course of the vagus nerve
Runs posterior to the hilum of the lungs and gives branches to the oesophagus
43
What imprints on the right lung?
Azygous vein - drainage of post. intercostal and lower abdominal area
Can engorge when have issues with portal system
44
Where is the apex of the lung?
Sits slightly above the clavicle
45
What is significant about the inferior lobe of the lung?
Common area for fluid collection and pus can accumulate in pneumonia
eg. lower resp tract infection/upper resp tract infection
common cold
46
Outline the formation of the lungs
4-7 wk lungs begin to bud and heart begins to form
7-17 wk (pseudoglandular) - lobes begin to come together
17-26 wk (canilicular) - surfactant synthesis
primitive alveoli - type I & II cells
27-36 wk - sacular
36 wk (alveolar) - birth alveolar are mature by this stage
after 2 yrs will grow - as develop into adult
47
What is the mediastinum divided into?
Superior mediastinum – extends upwards, terminating at the superior thoracic aperture.
Inferior mediastinum – extends downwards, terminating at the diaphragm.
It is further subdivided into the anterior mediastinum, middle mediastinum and posterior mediastinum.
48
What are the boundaries of the superior mediastinum?
```
Superior = manubrium, 1st thoracic vertebrae, 1st rib
Inferior = transverse thoracic plane between T4/5 intervertebral disc and sternal angle
Anterior = Manubrium of sternum
Posterior = Bodies of thoracic vertebrae 1-4
Lateral = lungs and mediastinal pleura
```
49
What does the superior mediastinum contain?
```
Superior thoracic outlet
Arch of aorta (3 major branches)
SVC and branches - brachicephalic vein, left superior intercostal vein, superior intercostal vein, azygous vein
L+R Vagus nerve pass through
Phrenic nerve passes through
Cardiac nerves and sympathetic trunk
Thymus
Sternohyoid, sternothyroid
Trachea - bifurcates at level of sternal angle
Thoracic duct
Oesophagus
```
50
What are the borders of the inferior mediastinum?
Superiorly: transverse thoracic plane T4/5
Inferiorly: diaphragm and inferior thoracic aperture.
Laterally: mediastinal pleura and lungs.
Anteriorly: Manubrium of sternum.
Posteriorly: bodies of lower eight thoracic vertebrae, their transverse processes and associated ribs.
51
Structures in inferior mediastinum
Inferior thoracic outlet
| Part of the arch of aorta and pulmonary trunk
52
How much of the mediastinum does the heart occupy?
2/3 inferior mediastinum
53
Divisions of the middle mediastinum?
Anterior: Anterior margin of the pericardium.
Posterior: Posterior border of the pericardium.
Laterally: Mediastinal pleura of the lungs.
Superiorly: Imaginary line extending between the sternal angle (the angle formed by the junction of the sternal body and manubrium) and the T4 vertebrae.
Inferiorly: Superior surface of the diaphragm.
54
What structures are in the middle mediastinum?
Heart and pericardium
Vessels = Ascending aorta, Pulmonary trunk, SVC
Nerves = cardiac plexus, phrenic nerves
Lymph = tracheobronchial lymph nodes
55
Borders of posterior mediastinum?
Lateral: Mediastinal pleura (part of the parietal pleural membrane).
Anterior: Pericardium.
Posterior: T5-T12 vertebrae.
Roof: Imaginary line extending between the sternal angle (the angle formed by the junction of the sternal body and manubrium) and the T4 vertebrae.
Floor: Diaphragm.
56
What are the contents of the middle mediastinum?
Vessels = thoracic aorta, posterior intercostal arteries,
bronchial arteries, oesophageal arteries, superior phrenic arteries
Azygous vein, hemiazygous and accessory hemiazygous vein
Nerves = oesophageal plexus (branches from left and right vagus nerves), thoracic sympathetic trunk
Oesophagus
57
Borders of anterior mediastinum?
Lateral borders: Mediastinal pleura (part of the parietal pleural membrane).
Anterior border: Body of the sternum and the transversus thoracis muscles.
Posterior border: Pericardium.
Roof: Continuous with the superior mediastinum at the level of the sternal angle.
Floor: Diaphragm.
58
Contents of ant. mediatinum
Thymus
59
Describe the position of the structures in the mediastinum when lying down
Arch aorta lies superior to transverse thoracic plane
Bifurcation trachea transected by plane
Central tendon diaphragm (diaphragmatic surface) lies at T9 (level of xiphisternal junction)
60
Describe the position of structures in the mediastinum when standing
Arch aorta transected by thoracic plane
Tracheal bifurcation lies inferior to plane
Central tendon diaphragm may fall to level of middle of xiphoid process and T9/10 intervertebral disc
61
Where does the pericardium sit?
On the diaphragm
62
What is the transverse pericardial sinus?
Pericardial cavity behind the aorta and pulmonary trunk
63
What are the practical implications of the pericardial sinus?
Important to cardiac surgeons, after pericardial sac is opened anteriorly, can pass things through transverse pericardial sinus, posterior to aorta and pulmonary trunk
During coronary artery bypass grafting
ie. surgical clamp/place ligature around vessels, inserting tube of bypass machine and then tightening ligature
surgeons can stop/divert circulation of blood from these arteries while performing cardiac surgery
64
What do pericardial reflections do?
Link parietal and visceral pericardium
NB - continuity of parietal and visceral serous pericardium around roots of great vessels
Ascending aorta and pulmonary trunk are contained within fibrous pericardial sac and covered by serous pericardium
65
What is constrictive pericarditis?
Thickening pericardial sac implies compression heart and subsequent heart failure
66
What is the oblique pericardial sinus?
Blind-ending pericardial cul-de-sac behind the heart which opens into the pericardial space proper inferiorly
67
What are the practical implications of the pericardium?
Pericarditis = inflammation of pericardium causes chest pain
Some inflammatory diseases may cause pericardial effusion - escape of fluid from pericardial capillaries into pericardial cavity
Cardiac tamponade = compression of the heart
Large volume of pericardial effusion accumulates, prevents heart from expanding fully, limiting inflow blood to ventricles
Eg. blood leaking from stab wound may limit expansion ventricles
Potentially lethal as fibrous pericardium tough, elastic and can't expand - reduces cardiac output and blood circulation
68
How is cardiac tamponade treated?
Pericardiocentesis - needle and catheter used to remove fluid
69
What are the great vessels of the heart?
Ascending aorta, pulmonary trunk, brachiocephalic veins, SVC, IVC, R+L Pulmonary veins
70
What is the pericardium?
Thin fibro-serous sac surrounds the heart and root of great vessels.
71
What are the components of the pericardium?
Fibrous pericardium - Thick connective tissue surrounds heart and root of great vessels
Serous pericardium -
- parietal layer - lines inner surface of fibrous pericardium
- visceral layer - adheres to the heart and constitutes to the outer covering
72
What allows frictionless beating of the heart?
Small amount of fluid between parietal and visceral layers
73
Where does the pericardium sit?
On the diaphragm - wraps around structures and vessels that pierce through it, to incorporate them
ie. goes over part of the arch of aorta
74
Describe the outer appearance of the heart
Shaped like sideways pyramid
| Lies in middle of chest - has vase posteriorly and apex in 5th intercostal space
75
Why may the heart be larger than normal?
Enlargement = cardiomegaly/ patient exercises
76
Which side of the heart do the great vessels lie?
Vena cava - RHS (returns deoxygenated blood back to heart)
| Arch aorta - LHS
77
What is the auricle of the heart and what emerges from them?
Small flap on the atria - coronary arteries emerge from underneath
L+R coronary arteries major arteries that supply the hear
78
Which ventricle is more anterior and lateral?
Right ventricle takes up more space anterolaterally
| Left more posterior
79
Why is the left ventricle thicker?
Left is thicker because need pump blood to body at higher pressure
Oxygenated blood comes in left side via pulmonary veins pulmonary trunk w/ blood from RHS passes blood to pulmonary system
80
What are the surfaces of the heart?
4 surfaces -
Left and right pulmonary surfaces - where lungs are
Sternocostal surface - front
Diaphragmatic surface - inferiorly (sits on diaphragm)
81
What is the apex of the heart?
Made up of left ventricle - moves laterally and downward from midline
82
What is opposite the apex of the heart?
Base - mainly formed by left atrium and small portion right atrium
83
What are the borders of the heart?
4 borders -
Superior - where major blood vessels emerge eg. arch aorta, pulmonary trunk
Left - made by left ventricle
Right - formed by right atrium
Inferior - formed by right ventricle at bottom
84
Which vessel is most inferior?
Pulmonary vein is most inferior
then pulmonary trunk, arch of aorta goes over pulmonary trunk
This is important to distinguish where lungs are
85
What is the coronary sinus?
Opening into right atrium
It is a opening on the posterior wall - collection of deoxygenated blood coming back into RA from the heart
(drains the heart)
86
What is the crista terminalis?
Direct connection between orifice of IVC and SVC
| Smooth surfaced, thick portion heart inc crescent - at opening right atrial appendage
87
What are the musculi pectinati?
Muscular ridges on inner wall of auricular appendage
88
What is the fossa ovalis?
Remnant of foramen ovale -> aperture between R+L atrium for blood to cross the aorta and bypass pulmonary circulation during foetal development
Closed in an adult - can see as a depression
89
What are the features of the right ventricle?
* Trabeculae - rounded or irregular muscular columns which project from the inner surface of the right and left ventricle of the heart.
* Infundibulum (w/smooth walls) - conical pouch formed from the upper and left angle of the right ventricle, from which the pulmonary trunk arises.
* Interventricular septum
* Atrioventricular orifice – right atrioventricular valve
* Ant, post (inf), septal cusps of atrioventricular valve
90
How many cusps does the tricuspid valve have?
```
3 cusps:
Anterior
Septal
Posterior
Look at picture
```
91
What do the chordae tendinae attach to?
To papillary muscles (attachment area)
92
What do the trabeculae carnae do?
Forms network
| Contraction pulls on chordae tendinae - preventing insertion of mitral and tricuspid valve toward atrial chambers
93
What is the journey of blood on the right side of the heart?
Comes down toward apex from atria to right side of ventricle
| Then pushes up and out through pulmonary valve
94
What are the features of the left atrium?
* Smooth internal features
* Septal wall w/ fossa ovalis depresson
* Auricle w/ rudimentary musculi pectinati
* Pulmonary vein orifices
* Left atrioventricular orifice and mitral valve
95
What is the mitral valve?
Bicuspid - has 2 cusps
Anterior and posterior
Passway from left atrium to left ventricle
Toward apex
96
What are the features of the left ventricle?
• Ventricular cavity – cone shaped in normal heart
Narrows aortic vestibule
• Trabeculae carnae
• Left atrioventricular orifice (mitral valve)
• Chordinae tendinae and associated papillary muscles
• Aortic valves w/ semilunar cusps
• Atrioventricular groove
• Interventricular groove
97
Why are the pathologies of the left ventricle different?
Has thicker walls
| Blood passing into aorta from it
98
What is the atrio-ventricular groove (coronary sulcus)?
Line where right atrium and ventricle meet
| Contains branch of right coronary artery
99
What is the interventricular groove?
Between right and left ventricles - front and back surfaces of heart
Contains branch of left coronary artery
100
Describe the coronary artery and its passage
1st 2 branches of arch of aorta
| Passes behind pulmonary trunk and emerges by auricles of heart
101
Which artery passes down the anterior interventricular groove?
Left ant. descending/ anterior interventricular branch
| Most common to get blocked- passes round down to apex
102
What branches come off the left anterior descending artery?
Diagonal and marginal branches
103
Which artery supplies the left atrium?
Left circumflex - passes round left auricle
104
What do the ventricular marginal branches supply?
Ventricles
105
What does the right coronary artery supply?
Supplies anterior and posterior aspect of heart
| Gives branch to supply SAN
106
What is the clinical significance of the right coronary artery?
Required for ECG - helps to know what position heart is in and what looking at
107
List the major coronary arteries on the RHS
Right coronary artery - goes down right sulcus
Posterior interventricular artery
Marginal artery
108
List major coronary arteries on LHS
Left coronary artery
Anterior interventricular arteries
Circumflex artery
109
What is the corona?
Coronary blood vessels form a ring around the heart, known as corona
110
What are some variations?
Variations in branching of coronary arteries:
Left coronary artery dominant in 15% people - posterior interventricular branch of circumflex artery
OR
Single coronary artery - circumflex branch arises from right aortic sinus
OR
Accessory coronary artery
Usually (70-80%) right CA dominant - post interventricular artery = branch of right CA
R+L CA share approx. equal blood supply to heart
111
Are there collateral routes of blood supply to the heart?
No
Anastomoses exist between branches coronary arteries, sub-epicardial/myocardial and extra cardiac vessels. don't provide adequate collateral route for continuation of heart function after MI/ clotted blood.
112
List the coronary veins
Coronary sinus
Great cardiac vein
Middle cardiac vein
Small cardiac vein
113
What is significant about the valves of the heart?
Only allow blood flow in one direction
2 atrioventricular (cuspid) valves - guarantee blood doesn't return from ventricle to aorta
eg. mitral and tricuspid
2 arterial (semi-lunar) valves - avoid reflux blood from 2 arteries that leave heart
eg. pulmonary and aortic
114
What is an aortic sinus?
Anatomic dilatations of the ascending aorta, which occurs just above the aortic valve, between the wall of the aorta and each of the three cusps of the aortic valve
˙.˙ pushing blood out into arch aorta
115
What is a murmer?
Abnormal heart sound - problem w/ leaflet
116
What is insufficiency and stenosis in the heart?
Insufficiency = poor functioning valve
Stenosis = Narrowing orifice ˙.˙ inability of valve to fully open
Both cases when affecting aortic valve and inducing reflux blood (regurgitation) signals severe heart failure
117
What is the azygous vein?
Major vein of trunk
118
Describe the entry of veins in the heart
R+L brachicephalic veins form SVC that flows into heart from above
Inf vena cava flows into heart from below - has all major tributaries from lower limbs and posterior abdominal structures
119
What is the SAN?
Instigator for contraction of R+L atrium
In top right hand corner atrium
Sympathetic increases flight and fight
120
What is the AVN?
Controls conduction jumps - goes down purkinje fibres to help contract down toward apex
Parasympathetic - slows down - rest and digest
121
What are the plexi of the heart?
Deep and superficial cardiac plexus - help heart despite it being myogenic
122
What type of system is the heart?
Dual suction/pressure pump that keeps blood circulating
123
How can the heart contract spontaneously?
Musculature of atria and ventricles able to contract spontaneously
Nodes and networks specialised cardiac muscle cells (cardiac conduction system) coordinate contraction
124
What does the ANS control?
Rate contraction and speed of conductivity
Increased by sympathetic and inhibited by parasympathetic
Linked to vagus nerve
125
Which vagus nerve is longer?
Left as it loops under arch of aorta
126
What do the branches of the vagus nerve contribute to?
Branches help supply superficial cardiac plexus
| above arch aorta = sensory mechanism
127
What do the deep cardiac branches supply?
Supplies region just over carina
Deeper branches from vagus
Important because need to expand airway to get more O2 during insp/exp in flight or fight
128
Describe the course of the left vagus nerve
Left vagus runs posterior to hilum of lung
129
Describe the relation with the sympathetic trunk
Cardiac plexi link directly with rami to sympathetic trunk - gives connection to spinal cord .˙. helps w/ control heartbeat
Nerves connect w/ ganglion from spinal cord linking systems w/in symp. trunk (ANS)
helps liase w/ and have effect on cardiac plexus to increase/decrease HR
.˙. have receptors over arch aorta and over trachea - help w/ control
Links in w/ part brbachial plexus .˙. get tingling sensation lower brachial plexus -> may complain pain down in arm
shares neuropathway
130
Describe the course of the venous return via cardiac veins
Great cardiac vein goes down interventricular septum w/ LAD (any aspect)
Small cardiac vein on right side - helps supply
Middle cardiac vein
Contribute to coronary sinus that in turn empties into right atrium
Small veins anterior to right atruim drain directly into right atrium
131
What are the implications of leaky valves?
Murmers - occur if valves don't seal adequately
Leaky valves cause heart to enlarge - most time require surgery
Refer to notes for auscultation positions
Heart lies behind sternum
