Anatomy: Thorax Flashcards
(144 cards)
1
Q
Abdominal breathing mechanism
A
Muscle fibres of diaphragm contract
Causes central tendon to move downwards (increases vertical diameter) - then movement arrested by the liver
This now acts as a fixed point - ebcomes the origing for muscle fibres to insert
Causing the elevation of the lower 6 ribs
2
Q
Order of lung root structures (anterior to posterior)
A
Upper of the two pulmonary veins
pulmonary artery
bronchus
3
Q
Where does the phrenic nerve travel in the middle mediastinum?
A
In between the fibrous pericardium and the mediastinal pleura
4
Q
Three surfaces of the heart
A
Anterior - RA, RV, narrow strip of LV, auricle of LA
Posterior (base) - LV, LA + 4 pulmonary veins
Inferior (diaphragmatic) - LV + RV + inferior part of RA where IVC enters
5
Q
Heart basics
Direction of apex and base
A
Free floting in pericardium - only attached to great vessels at base
Apex - downwards, forwards, left
Base - upwards, backwards, right
6
Q
How to avoid pulmonary vasculature in development
A
Ductus arteriosus: RA - RV - PA - DA - aortic arch; becomes ligamentum arteriosus
Foramen ovale: RA - LA - LV - aortic arch; becomes fossa ovalis
7
Q
Where is pleural pain referred to?
A
Parietal - eg. right lower lobe pneumonia via intercostal nerves to right lower abdomen mimicking appendicitis - goes to the corresponding thoraco-abdominal wall
Diaphragmatic pleura - via phrenic nerve to tip of the shoudler - C4 dermatome
8
Q
Relations of the manubrium
A
Anterior boundary of superior mediastinum
Upper part = L brachiocephalic vein + artery; L common carotid artery; L subclavian
Lower part = aortic arch
Laterally = lungs and pleura
9
Q
Nerve supply of pleura
A
Visceral - autonomic from vagus that supplies lung, sensitive only to stretching (no pain)
Parietal - somatic innervation from intercostal nerves (sensitive to pain)
Diaphragmatic pleura - phrenic nerve (sensitive to pain)
10
Q
Composition of Trachea
A
Fibroelastic tissue
U shaped rings; open posteriorly; ends connected by trachealis muscle
Rings can get calcified on xray
11
Q
What is the crista terminalis?
A
Muscular ridge separating the smooth walled posterior part of the RIGHT atrium (which is derived from the sinus venosus) from the rougher part derived from the true atrium (due to pectinate muscles)
12
Q
Branches of the right coronary artery
A
Marginal branch along the lower border of the heart
Posterior interventricular branch - runs forward into the inferior interventricular groove - then anastamoses with the corresponding branch of the left coronary artery (also known as the posterior descending artery)
13
Q
Location of AV node
A
Interatrial septum - above opening of coronary sinus
14
Q
L bronchopulmonary segments
A
Upper lobe - apico-posterior (1,2), anterior (3), superior lingular (4), inferior lingular (5)
Lower lobe - superior (6), anteromedial basal (8), lateral basal (9), posterior basal (10)
15
Q
How many pulmonary veins open into the LA?
A
4
Superior and inferior from each lung
16
Q
4th costal cartilage significance in the pericardium relations
A
below 4th CC - pericardium in contact with the sternum
above 4th CC - lungs and pleura are in front
17
Q
Venous drainage
A
Venae cordis minimae - tiny veins draining into the chambers
Anterior cardiac veins - small, open directly into the RA
Coronary sinus - main drainage, opens into the RA - below the AV node and left of the IVC opening, lies in the posterior AV groove; tributaries include - great cardiac vein, middle cardiac vein, small cardiac veins
18
Q
Articulations of the Body of the Sternum
Number of parts of the body of the sternum
A
Most of the second costal cartilage
Third - Seventh costal cartilage
4 parts = stenebrae
19
Q
Attachments and shape of the central tendon of the diaphragm
A
Shape - trefoil
Attachments - insertion of muscular fibres; above it fuses with the pericardium
20
Q
Tributaries and routes of the coronary sinus
A
Great cardiac vein - anterior interventricular groove - follows the LAD
Middle cardiac vein - next to the posterior interventricular artery (drains the posterior and inferior surfaces of the heart)
Small cardiac vein - follows marginal artery, drains into the terminus of the coronary sinus
21
Q
Distortion + widening of the carina
A
Lobar collapse
Pathology of the heart (LA enlargement)
enlargement of the tracheo-bronchial lymph nodes at the bifurcation due to carcinoma
22
Q
Most common congenital abnormality of the heart
A
VSD
Small ones = ok
Large ones (esp in membranous septum below AV valves) = may require repair
23
Q
Use of sternal puncture
A
Access bone marrow for the body of the sternum
Need to know the posterior relations of the sternum (brachiocephalic artery and vein / subclavian / common carotid / aortic arch)
24
Q
Features of 11/12 rib
A
Short
No tubercles
One articular facet on head
11th shallow subcostal goove, 12th no subcostal groove
25
**Tracheostomy**
Incision style
Vertical (from cricoid cartilage passing between the anterior jugular veins)
or
transverse (cosmetic - halfway between cricoid cartilage and suprasternal notch)
26
Development of the diaphragm
4 parts
1. Septum transversum (fibrous central tendon); (bare area of liver attaches here)
2. mesentery of the foregut (area adjacent to the vetebral column becomes the crura + median part)
3. Ingrowth from body wall
4. Pleuroperitoneal membrane (R+L) - these close of the communications between the pleural and peritoneal cavities
27
Rib Fractures complications
Damage **lung** (contusion) or pneumothorax
Rupture **spleen** (L 9,10,11)
Rupture **intercostal** **vessels** = haemothorax
28
First Rib important structures
inner upper border - scalene tubercle where scalene anterior attaches
anterior to scalene tubercle - subclavian vein
posterior to scale tubercle (in the subclavian groove) - subclaviant artery and lowest trunk of brachial plexus below that
neck of first rib crossed by - M to L - sympathetic trunk, supreme intercostal vein, superior intercostal artery, t1 to brachial plexus
first digitation of serratus anterior attaches to outside edge
suprapleural membrane (sibson's fascia) attached to inner border
29
Four borders of the heart
Right - RA + SVC + IVC
Left - LV + auricle of LA
Inferior - RV + apex of LV
Superior - RA + LA + great vessels
30
Use of no pleura at 4th 5th ICS
Needle goes staight into pericardium, useful for pericardiocentesis
31
What happen at angle of louis / sternal angle?
T4 plane
Sterno-manubrium
Bifurcation of trachea
Start and finish of aortic arch
Ligamentum arteriosum
Border of superior and inferior mediastinum
Azygos vein joins into the SVC
Thoracic duct runs from right to left
32
Rib
true
false
12 pairs
1-7 true - articulate with the sternum through costal cartilages
8-10 false articulate with costal cartilage, each with rib above
11-12 - no articulation, free anteriorly = floating
33
Muscles and directions of the intercostal muscles
External Intercostal muscles - downwards and forwards, replaced in the front by the anterior intercostal membrane
Internal intercostal muscles - downwards and backwards, replaced in the back by the posterior intercostal membrane
Innermost intercostal muscles - covers more than one intercostal space
34
Order of contraction for the AV bundle
Papillary muscle, then wall and septum from apex towards outflow tract
35
Damage to phrenic nerve complicaitons + clinical finidngs
Paralysis of diaphragm
Diaphragm elevated - dullness to percussion at base of lung + absent breath sounds
+ paradoxical movement on respiration
36
Route of the left coronary artery
Left posterior aortic sinus
Passses below then to the left of the pulmonary trunk
follows the left AV groove into the cover of the left auricle
then divides into two branches
37
Nerve supply of the heart
Sympathetic - cardio accelerator
Vagus - cardio inhibitor
38
L lung gross anatomy
Oblique fissue / 2 lobes - upper and lower
Cardiac notch on the anterior border
Middle lobe equivalent = lingula - lies between the cardiac notch and the oblique fissure
39
Structures seen when view the mediastinum from the right
Oesophagus
Trachea
Veins - SVC
Nerves - vagus, phrenic, sympathetic chain
40
What is the mediastinum?
What are the sections?
Space between the two pleural cavities
Superior
Middle
Anterior
Posterior
41
Purpose of Ductus venosus
Bypasses the liver
42
Cusps of tricuspid valve
Septal, anterior, posterior
43
**Differences between R and L main bronchus**
Size
Length
Route
Branches
R is wider, shorter and more vertical
R is 2.5cm; L is 5cm
Both pass downwards and laterally: R behind ascending aorta and SVC; L below aortic arch and in front of oesophagus and descending aorta
R gives of upper lobe branch before entering hilum; left does not give off any branches
44
R lung gross anatomy
Larger than L
3 lobes - upper (horizontal) middle (oblique) lower
45
Inspiration muscles used
**Quiet**
**Forced**
Abdominal + thoracic muscle combination
SCM, scalenes, serratus anterior, pec major, pec minor
46
Great vessels
**6 pairs of arches**
1 + 2 disappears
3 carotid
4 subclavian R; aortic arch L (giving L subclavian)
5 disappears
6 R+L pulmonary arteries connecting to dorsal aorta - R disappears; L connects to aortic arch via ductus arteriosus
47
Nerves related to the diaphragm
Phrenic nerve (C3,4,5) - main motor innervation of the diaphragm
Greater and lesser splanchnic nerves pierce through the crura
48
Route of the L pulmonary artery - where it divides in front of the left main bronchus
Connected at its origin to the aortic arch via the ligamentum arteriosum
Runs in front of the left main bronchus and descending aorta
Left recurrent laryngeal nerve loops below the ortic arch in contact with the ligamentum arteriosum
49
Cardiac referred pain
Cardiac sensation - T1-4; referred pain of these dermatomes - arm (route: cardiac plexus - sympathetic chain - DRG - spinothalamic tract)
for jaw: vagal - nucleus of tractus solitarius in the medulla - upper cervical spinothalamic
50
How to work out the horizontal fissure?
Horizontally and medially from the 4th CC of the oblique fissure
51
R main bronchus
Downwards and laterally
Behind ascending aorta and SVC; azygous vein arches over it from behind to enter SVC
Gives off upper lobe bronchi before entering hilum
Divides into bronchi for middle and lower lobes within lung
Pulmonary artery lies below then anterior to it
52
Cusps of mitral valve:
Cusps of aortic valve:
anterior / posterior
right posterior (NCC) / anterior (RCC) / left posterior (LCC)
53
Relations of the body of the sternum
R - right pleura, thin anterior border of the right lung (intervenes between it and the pericardium)
L - upper two parts - left pleura, left lung
L - lower two parts - pericardium
54
Dextrocardia vs Situs inversus
Just heart vs all viscera
55
What's special about 10th rib?
Only one articular facet on head, rather than 2
56
Structures seen when viewing the mediastinum from the left
Heart
Arteries - left subclavian, left common carotid descending aorta
Nerves - phrenic, vagus, left recurrent laryngeal
57
Cervical Rib Complications
Artery: Post-stenotic dilation of subclavian artery - turbulene, thrombi, distal emboli, ischaemia, Raynaud's, subclavian aneurysm
Vein: thrombosis
Nerve: Brachial plexus - C8/T1 - wasting of small muscles of the hand; sensory loss in C8/T1 distribution
58
Fibrous pericardium expansion?
Gradual, but rapid stretching does not occur = causing tamponade
59
Thoracic Cage components
Vetebral coumn
Ribs and Intercostal spaces
Sternum and Costal Cartilages
60
Route of AV bundle
Through the fibrous skeleton of the heart
Then to the membranous part of interventricular septum
Then into left (larger) and right Bundle of His
Travels under the endocardium
61
Where does the NV bundle for ribs lie?
In the subcostal groove at the bottom of each rib
Between the innermost and internal intercostal muscles
62
Fusion between primum and secondum takes place when?
Failure to fuse causes?
Murmur?
3 months after birth
Atrial Septal defect; but normal in 10%
fixed split S2
63
Transverse sinus
Posterior to the Aorta + pulmonary ttrunk,
Anterior to the SVC,
Superior to the upper margin of left atrium
Useful in separating the great vessels during cardiothoracics to tie them off
64
Where does the right crus originate from?
Front of the bodies of the first 3 lumbar vetebrae + intervetebral discs
65
Location of the auricle of the LA
Extends forwards and to the right; overlapping the commencement of the pulmonary trunk
Makes up the left border of the heart with the LV
Also makes up part of the anterior surface
66
Complications of PDA
Machine like murmur
Increased load on left ventricle and pHTN
67
**Lung**
Shape
Apex
Base
Parietal surface
Mediastinal surface
Anterior border
Hilum
Posterior border
Conical, conforms to shape of pleural cavities
Blunt, extending above sternal end of 1st rib
Concave, relating to diaphragm
Convex, relating to ribs
Concave, relating to pericardium
Thin, deficient on the left side over the cardiac notch
Bronchi and vessels passess to and from the root
Rounded, occupies the groove by the side of the vetebrae
68
Lining of the trachea
Ciliated columnar epithelium - goblet cells
69
Variations of the coronary arteries
Left dominance - where LAD/LCX is larger/longer and supplies the posterior interventricular artery (usually the RCA)
Co-dominance - supplied by RCA and LAD/LCX
3rd branch of LMS - inbetween LAD and LCX - supplies the lateral wall of the left ventricle
SA node - usually RCA, but 40% LCX, 3% dual
AV node - usually RCA, but 10% LCX
70
Cervical Rib
Incidence and Complete/Incomplete
Incidence 1:200; bilateral 1:500 (twice the sides, twice as uncommon)
Complete: articulates with transverse process of C7 and first rib; incomplete: free distally or just a fibrous band
71
Types of ASD
Secondum - too short secondum, so when fusion occurs between primum and secondum, ASD remains, aka "ostium secondum"
Primum - failure of primum to fuse with the endocardial cushions; aka "ostium primum"; usually on AV boundary so may be associated with a VSD
72
Where does medial arcuate ligament arise?
Condensation of fascia of **psoas major**
73
Bronchopulmonary segments
Number
Shape and location of the apex
What is each segment supplied by?
Can each segment communicate?
How are the boundaries marked?
Uses of the boundaries
Bronchopulmonary segments
10
Wedge shaped, apex at the hilum
segmental bronchus, artery, vein
No communication between segments
Intersegmental veins
Minimal bleeding/disruption if excised along boundaries
74
Composition of the pulmonary valve
3 semilunar cusps
75
**Anatomy of the Trachea**
Start to finish
Length of trachea
lower border of cricoid cartilage (sixth cervical vertebra)
into the two main bronchi (fifth thoracic vertebra)
11 cm
76
Oblique sinus
J shaped oblique sinus - blind ended
bounded by the pulmonary veins - behind inferior to the left atrium
forms a recess between the pericardium and left atrium
77
Parts of the LA
Principal cavity and eft auricle (which is located on the anterior surface and makes up part of the left border of the heart)
78
Expiration muscles used
**Quiet**
**Forced**
Elastic recoil of lung and chest wall
rectus abdominis, external / internal obliques, transversus abdominis, latissimus dorsi
79
Surface anatomy of lungs
Apex follows cervical pleura
Anterior border follows mediastinum (with distinct cardiac notch on left side at 5th and 6th CC)
Lower border is 2 below pleura - 6th MCL, 8th MAL, 10th MSL (lateral border of erector spinae)
80
Route of the right pulmonary artery - from dividing anterior to the left main bronchus
Anterior to the oesophagus, but behind the ascending aorta and the SVC
At the root of the lung it is anterior and in between the right main bronchus and its upper lobe branch
Then divides into 3 branches - 1 for each lobe
81
Differences in surface of valves
Atrial surface = smooth
Ventricular surface = rough - due to chordae tendinae that attach to the papillary muscles to prevent eversion of the valve
82
Where does the costal part and the sternal part of the diaphragm attach to?
Costal part - inner portion of the lower six ribs
Sternal portion - two small slips from the back of the xiphoid process
83
Fetal Circulation route
Placenta - Umbilical Vein - Ductus venosus - IVC
RA - FO - LA - LV - aortic arch
AND
RA - RV - PA - DA - aortic arch
Abdo aorta - common iliac
Internal iliac arteries - umblical arteries - placenta
84
Where does the trachea divide into the left and right main bronchus?
Sternal angle
85
Layers of pericardium
Fibrous
Serous - parietal and visceral
86
Blood supply of bronchopulmonary segments
Leaves RV
Anterior to ascending aorta
Passes upwards then backwards - to the left of ascending aorta
Reaches concavity of aortica arch
Then divides in front of the left main bronchus --\> into the left and right pulmonary arteries
87
**Fibrous pericardium**
Shape
Apex fuses with?
Base fuses with?
Conical
Adventitia of great vessels - about 5cm from the heart
Central tendon of the diaphragm
88
Route of the right coronary artery
Starts from the sinus of the anterior cusp of the aortic valve
Goes to the right of the pulonary trunk between it and the auricle of the right atrium
Follows down the AV groove
where it anastomoses into the left coronary artery at the posterior interventricular groove
89
Meeting of parietal and visceral pleura
As a sleeve at the hilum
Hangs down interiorly at the pulmonary ligament
Capacity to expand if needed - if pulmonary veins have increased blood flow
90
Articulations of the Manubrium
Clavicle
First costal cartilage
Upper part of second costal cartilage
Body of sternum (manubriosternal joint / angle of louis)
91
What is the moderator band?
What is its function?
muscle bundle crossing from the interventricular spetum to the anterior wall of the heart (the RV)
Function - prevents overdistension of the ventricle; conducts right branch of AV bundle to the anterior wall of ventricle
92
Causes of bleeding during tracheostomy
Adults - anastamosis of anterior jugular veins, inferior thyroid veins, thyroidea ima artery
Children - braciocephalic artery, L braciocephalic vein, thymus may be seen in the lower part
93
Dvision of the sternum provides access to?
Heart
Retrosternal goitre
Thymus
Ectopic parathyroid tissue
94
Eisenmenger's pathophyshiology
ASD / VSD / PDA - increased pulmonary flow / pHTN - left to right shunt
eventually pulmonary pressure is so great the shunt is reversed
causing CYANOSIS
95
Where does the left crus originate from?
first 2 lumbar vetebrae and intervetebral discs
96
Surface anatomy of the heart
Superior - 2nd CC L to 3rd CC R (both 1.2cm away from sternal edge)
Inferior - 5th ICS MCL (9cm away from midline) L to 6th CC R 1.2cm away from sternal edge
Left border - curved line joining 2nd CC to 5th ICS
Right boder - curved line joing 3rd CC to 6th CC
97
Typical rib anatomy
Head - 2 facets to articulate with corresponding vetebra and one above
Neck - gives attachment to the costo-transverse ligament
Tubercle - with a smooth facet to articulate with transverse process of corresponding vetebra
Shaft - flattened side to side, possessed an angle to mark to the lateral limit of attachment for erector spinae
Shaft also has a groove = subcostal groove - located inferiorly - contrains neurovascular bundle
98
Branches of the left coronary artery
From the left main stem:
Anterior interventricular (anterior descending) - goes down to the apex in the anterior interventricular groove; then anastomises with the posterior interventricular (posterior descending) --\> supplies the wall of the ventricles
Circumflex - round the left side of the heart in the AV groove - anastomises with the terminal branches of the right coronary artery - also gives off the marginal branch
99
What is the pulmonary ligament?
Where?
Purpose?
Loose fold of pleura
Root of the lung
Allows pulmonary vein to expand
100
What is the infundibulum of the right ventricle?
Outflow tract of RV - directed upwards and to the right into the pulmonary trunk
101
Bronchial arteries
Source
Function
Bronchial arteries
Branches of the descending aorta
Supplies the air passages
102
Composition of the root of the lung
principle bronchus
pulmonary artery and 2 veins
bronchial arteries and veins
pulmonary plexuses of nerves
lymph vessels
bronchopulmonary lymph nodes
103
Boundaries of the superior mediastinum
Anterior: Manubrium of sternum
Posterior: T1-4 vertebrae
Above: root of neck
Below: level of sternal angle - where it becomes inferior mediatinus (anterior / middle / posterior)
104
Contents of the superior mediastinum
Longus coli
OEsophagus
Trachea (lower end)
Vagus Phrenic Lt recurrent laryngeal nerve
SVC + (RBV+LBV+TD+LSIC) AoA + (LSA+LCCA+LBT)
Thymus
Sternothryoid, sternohyoid
+ lymph nodes, cardiac nerves, innominate artery + veins
105
Structure and Function of the Xiphoid Process
Small and cartilaginous
Prominent in adults if they lose significant weight - presents as a lump previously covered in fat
106
Features of the aortic valve cusps
Each have:
a central nodule on its free edge
a **sinus** / dilatation in the aortic wall alongside each cusp
107
Types of congenital diaphragmatic hernias
1. **Posterolateral** hernia - through foramen of bochdalek (pleuroperitoneal membrane) - more common on left side; presents later, worse prognosis
2. Hernia through a deficiency of the whole **central** tendon
3. Hernia through the foramen of Morgagni **anteriorly** - xiphoid and costal cartilagel presents earlier
4. Hernia through a congenitally large oesophageal hiatus
108
Relations of the trachea in the neck
Anterior - isthmus of the thyroid (2nd-4th tracheal rings); sternohyoid; sternothyroid
Laterally - lobes of the thyroid gland; carotid sheath
Posteriorly - oesophagus, recurrently laryngeal nerves in the groove between trachea and oesophagus
109
Order of NV bundle in ribs
**Rib**
Vein (lies in the groove)
Artery
Nerve
**Rib**
110
Layers of incision
Skin
Superficial fascia
Platysma (lateral part of transverse incision only)
Pre-tracheal fascia (split longitudinally) - this is where bleeding may be encountered - anastamosis of the anterior jugular veins, inferior thyroid veins, thyroidea ima artery
Strap muscles - leading to isthmus - either retracted upwards or divided upwards and clamped
Exposes the cartilaginous rings of the trachea
Incision to admit the tracheostomy tube
111
Surface anatomy of pleura
Behind the 1/3-2/3 if the clavicle
Extends 2.5cm above clavicle
Comes behind the sternoclavicular joint
Meets in the midline at sternal angle
R - lateral border of sternum then 8th at MCL, 10th at MAL, 12th at MSL (or lateral border of erector spinae)
L - arches at 4th CC laterally, then follows R pleura (4th/5th ICS not covered by pleura)
Pleura descends below the 12th rib at its medial extremity
112
Where does visceral meet parietal?
Hilum of lung
113
Second rib vs the first
Twice as long
Less curved
114
Order of lung root structures (cranial to caudal)
R - upper lobe bronchus, pulmonary artery, right principle bronchus, lower pulmonary vein
L - pulmonary artery, bronchus, lower pulmonary vein
115
Recurrent Laryngral Nerve position
Hooks around the 4th on the R as 5+6 disappears
Hooks around the 6th on the L (which is ductus arteriosus / ligamentum arteriosum in adults)
116
Components of the muscular part of the diaphragm
Arcuate ligaments
Crura
Ribs
Sternum
117
Process at birth
Baby breathes - LA pressure increases - pushing septum primum into secondum closing foramen ovale
Increased blood flow throguh PA; becomes poorly oxygenated - due to systemic venous blood
Vascular resistance (and presssure) lowered abruptly as lungs inflate - DA obliterated over next few days
Ligation of cord - thrombosis of umbilical artery, vein and DV
118
Relations of the fibrous pericardium
Anterior - sternum - 3-6 costal cartilage, thymus, anterior edges of lungs and pleura
Posterior - oesophagus, descending aorta, T-5-8 vetebrae
Lateral - roots of the lung, phrenic nerve, mediastinal pleura
119
Co-arctation pathophysiology
Failure of obliteration of ductus arteriosus = obstruction
Collateral flow through intercostal vessels supplied by superior intercostal artery of the costocervical trunk of the subclavian
Causes dilation and more tortuous vessels = rib notching
120
Where does the lateral arcuate ligament arise?
Condensation of fascia ascia over **quadratus lumborum**
121
Development of the heart
Two endothelial tubes fuse = primitive heart tube (in pericardial cavity)
5 sections - SV A V BC TA; SV into A, BC into V
Becomes U then S shaped
Boundary tissue between single atrial cavity and single ventricle grows as dorsal / ventral EC cushions
EC meet in the midline dividing common AV orifice into right (tricuspid) and left (mitral) orifices
Interventricular septum - apex to EC
Septum primum - atrium to EC, leaves small gap for FO
Septum secondum - right of primum; acts as valve for right to left shunt
At birth - decreased PP = primum pushed to close FO, primum and secondum fuse and obliterate FO leaving fossa ovalis
SV - joins atria + forms 2 vena cava on right and 4 pulmonary veins on left
122
**Costal Cartilage**
Composition
Function
Hyaline Cartilage
Increase resilience, reduce fractures
123
Boundaries of the anterior, middle and posterior mediastinum
**Anterior** Anterior sternum; posterior pericardium
**Middle** Anterior a. mediastinum; posterior p. mediastinum
**Posterior** anterior pericardium, root of lungs, diaphragm; posterior T4-T12
124
Irritation of intercostal nerves eg during needle decompression
Part of the anterior rami of the thoracic nerves
Causes referred pain to the anterior chest or abdominal wall (where the nerve terminates)
125
How are pericardial sinuses formed?
Due to refellections of the parietal and visceral pericardium
126
Irritation of the diaphragm - where is the referred pain?
Cutaneous supply of phrenic nerve - C4 dermatome - shoulder tip
127
Why is a sinus significant for the aortic valve cusps?
The anterior sinus opens into the right coronary artery
The left posterior sinus opens into the left coronary artery
128
Where is the fossa ovalis located?
Interatrial septum
129
L main bronchus
Downwards and laterally below arch of aorta in front of oesophagus and descending aorta
Gives off no branches until it enters hilum of lung - then gives of upper and lower lobe bronchi
Pulmonary artery lies anterior then above the bronchus
130
Relations of the trachea in the thorax
Anteriorly - brachiocephalic artery, L brachiocephalic vein, L common carotid, thymus
Posteriorly - oesophagus, recurrent laryngeal nerves
Right - vagus nerve, azygos vein, pleura
Left - aortic arch, L common carotid, L subclavian vein, L recurrent laryngeal nerve, pleura
131
Importance of pleura descending below the 12th rib in the medial extremity
Can be cut open in a loin approach to the kidney or adrenal
132
Diaphragm
Shape
Composition
Dome
Peripheral muscular part; central tendon
133
TOF components
Pulmonary stenosis
RVH
VSD
Overriding aorta
Cyanosis in the first few months + bootshaped heart
134
R bronchopulmonary segments
Upper lobe - apical (1), posterior (2), anterior (3)
Middle lobe - lateral (4), medial (5)
Lower lobe - superior (6), medial basal (7), anterior basal (8), lateral basal (9), posterior basal (10)
135
Serous pericardium
Parietal layer - in contact with fibrous layer
Visceral layer - synonymous with epicardium
Parietal is reflected onto visceral near the great vessels - the aorta and pulmonary trunk and the SVC / IVC and pulmonary veins
136
Parts of the sternum
Manubrium
Body
Xiphoid
137
What is the fibrous skeleton of the heart?
AV orifice - figure-of-8 conjoined fibrous ring
Purpose - acts as a skeleton for the attachment of muscles and valves
Maintains shape and position of the heart
138
Contents of the inferior mediastinum
Posterior
Middle
Anterior
**Posterior T**horacic duct
O**E**sophagus
**D**esecending aorta
(**SAHAV)** Splanchnic nerves (G,L,L) Azygos vein, Hemiazygos vein, accessory hemiazygos vein, vagus
**Middle** Great vessels (aorta / pulm trunk / SVC (lower) / 4 pulm veins); phrenic nerve, cardiac plexus
**Anterior** Sternopericardial ligaments
Thymus (in children)
Lymph nodes
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How to work out the oblique fissure?
Abduct arm fully - corresponds to the medial border of the scapula
OR
2.5cm lateral to T5 vertebrae to the 6th CC
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Where does the right atrium receive blood from?
SVC
IVC
Coronary sinus
Anterior cardiac vein
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How is the **median** arcuate ligament formed**?**
From the medial borders of the medial arcuate ligament
joins anteriorly over the aorta
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Location of SA node
Upper end of crista terminalis - right atrial wall
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Coarctation of aorta pathophysiology
abnormality of the obliterative process which normally occludes ductus arteriosus
results in hypertension in upper limbs; weak delayed femoral pulses
rib notching on CXR - intercostal arteries located on inferior border of ribs
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Pump handle vs bucket handle mechanism of respiration
**Pump handle** - anterior portion of the ribs + sternum is raised (usually below the posterior portion) - increasing **AP** diameter
**Bucket handle** - lateral portion of ribs 4-7 is raised (usually below the anterior and posterior portion) - increasing **transverse** diameter
