anatomy and imaging Flashcards
contraction of external intercostals do what
pulls rib below up and out - expanding the rib cage (muscles of inspiration)
placement of the external intercostal muscles
extend for the whole of the space from posterior to anterior - just before sternum, replaced by membrane - external intercostal membrane
what are the 2 traditional sites for central vein catheterization
internal jugular vein subclavien
checklist for R and L phrenic nerve (4)
- descends on scalenes anterior 2. passes between subclavein artery and vein at the top of the thorax 3. passes ANTERIOR to the lung root 4. pierce the diaphragm and supply it posteriorly
when does the cardiothoracic ratio not apply when deciding whether the heart is enlarged or not?
- in adults with hyperinflation of lungs - in children
what things should you look for when analysing an x-ray? (10)
- patient age, sex and ethnicity - PA, erect, centred, inspiratory, exposure - medical devices, foreign bodies - heart size, valves (if calcified) - mediastinal size, contour and divisions - lungs (normal) - airspace, airways, interstitium and lobes/
function of internal intercostal muscles?
splint the thorax
Tell me about the joints of the ribs
costovertebral joints - between bodies of adjacent vertebra and head of the rib costotransverse joints - between transverse process of vertebra and tubercle of rib
what makes, and where do they join, to make the brachiocephalic veins?
internal jugular vein and SVC unite at the medial end of the right and left clavicles and form the rigth and left brachicephalic veins
how can you tell if you patient is perfectly straight in an x-ray?
spinous processes line up with the trachea in the midline. They are also in the middle between the medial ends of the clavicles
branches of the right coronary artery
atrial, right marginal, posterior interventricular
Where does the SVC receive the azygous vein?
behind the 2nd costal cartilage
common route of vagus nerve
from head, runs in the carotid sheath (posterolateral to the common carotid artery)
Where is the base of the breast anatomically?
extends from the 2nd to 6th ribs and across from the lateral border of the sternum to the mid auxillary line
order of vessels in the neurovascular bundle
vein, artery, nerve
where do the musculi pectinati stop?
crista terminalis
Origin of the phrenic nerve
branch of the cervical plexus - from the ventral rami of C3, 4 and 5
what are the ridges of the wall of the RV called?
trabeculae carnae
branches of the left coronary arter
circumflex anterior interventricular
Route of arch of the aorta
ascending aorta (gives rise to R and L coronary arteries) arches upwards, backwards and to the left over the left lung root within the superior mediastinum ending at the T4-5 disc
where abouts do the left and right vagus nerves give off the right and left recurrent larngeal nerves
left - as it goes past the arch of the aorta right - at the level of the subclavian artery
arteries that supply the breast
gets arterial supply laterally (auxillary artery), medially (internal thoracic artery) and from the 2nd to 4th intercostal arteries
why do we prefer to take the JVP from the Right hand side?
because the right brachiocephalic vein has a much more shorter and vertical course that the left
3 layers of muscle in intercostal space
external, internal and innermost internal intercostals
oesophagus penetration of the diaphragm
passes through the muscular part of the diaphragm, just to the left of the midline, at the level of T10
branches of the thoracic aorta
intercostal bronchial pericardial oesophageal
branches of the left coronary artery supply blood to where
- most of the LV - Narrow slip of RV - most of LA - Anterior 2/3 of IV septum
what does fluid look like if it is present on an x-ray?
- will sink to the bottom - will form a meniscus (due to negative P in the thoracic cavity) - will form straight line if there is air in the thoracic cavity - looks white - loose silhouettes of structures in the x-ray
What are the ridges of the wall of the RA called?
musculi pectinati
What are Hounsfield units
absolute numbers of the grey scale from -1000 (blackest of black) to +1000 (whitest of white)
Where does the heart sit? (veretebral numbers)
T5-T8
what are the zones of the lung in x-ray
- upper (upper half of upper is apex) - middle - lower (lower half of lower is base) - lawyer zone!
placement of the internal intercostal muscles
muscle fibres extend from anterior to posterior - just before vertebra, replaced by anterior intercostal membrane
parietal and visceral pericardium - which is fibrous and which is serous
parietal - fibrous visceral - serous
what is the order of the right sided vessels as they come off the aorta
coronary arteries, brachiocephalic trunk - this divides into the right subclavian and right common carotid and then left common carotid. Last branch is the left subclavian
How is the anterior-posterior dimension of the thorax changed?
from elevation and depression of the ribs
what is the conventional view when looking at a cross-sectional CT slide
look from the feet up
where does the thoracic duct empty into?
the junction of the left internal jugular and left subclavian veins
Branches of the right coronary artery supply blood to where
-RA - portion of the La - interatrial septum - entire RV - Variable portion of the LV - posteroinferior one-third of the IV septum - portions of the conducting system of the heart
tell me about the sterno-cos tal joints of the ribs
•Ribs 1-7 articulate with the sternum via costal cartilage •Ribs 8-10 costal cartilage turn up and articulate with the costal cartilage above them •Ribs 11-12 dont articulate with anything and only have a little costal cartilage
muscles of forced inspiration
scalenes, sternocleiodmastoid
position of a patient in the CT machine for thoracic CT
lies on a table, arms up and holds their breath
how far do the right and left crus extend down to?
left - L1 and L2 right - L1, L2 and L3
which main muscle do the breasts overlie?
pectoralis major and minor and serratus anterior
what is the ligamentum arteriosum
fibrous band connecting the underside of the arch of the aorta to the bifurcation of the pulmonary trunk (remnant of the ductus arteriosus shunt during foetal development)
how is the nerve supply to the heart organised
cardiac plexus situated at the base on the heart (divided into superficial and deep parts) It receives branches from vagus and sympathetic trunks
aorta penetration of the diaphragm
passes behind posterior attachment of the diaphragm at vertebral level T12
key features of thoracic vertebra
demi facets on the body (inferior and superior) facets on the transverse process long vertical spinous process
what is the route of the azygous vein?
moves up the thoracic column on the right hand side, eventually arches behind into the back of the SVC at the level of the 2nd right costal cartilage
route of the right recurrent laryngeal nerve
ascends via the right tracheoesophageal groove from the right subclavien artery
papillary muscles of the RV and LV
RV has 3 papillary muscles, while LV has 2 - attach to cusps of the valves
What landmark separates the superior and inferior mediastinum
imaginary line between the manubrial-sternal junction anteriorly, back to the T4-5 disc posteriorly
lymph drainage of the breast
auxillary lymph nodes drain majority (75%). Other drainage to the internal thoracic nodes
IVC penetration of the diaphragm
passes through the central tendon, slightly to the right of the midline through the central tendon at the level of T8
where is the only place in the RV that does not have trabeculae carnae?
infundibulum/conus arteriosus
What is the cause of dysphagia by alteration in the anatomy of the branches of the aorta?
You have 4 branches coming off the aorta instead of the brachiocephalic trunk - order: Right common carotid, left common carotid, left subclavian artery and then right subclavian artery. This 4th branch tends to go behind the oesophagus and trachea towards the upper limb and compresses the trachea and oesophagus causing dysphagia
inner wall of the RA is called…
sinus venarum - smooth surface
What are the ligaments that reinforce the joints between the ribs and the vertebra
radiate ligament - reinforces costovertebral joint costotransverse ligament - reinforces costotransverse joint
tell me about the tubercle facets of the rib
2 facets: medial - smooth and concave - articulates with the transverse process of the vertebra lateral - rough - muscle attaches here
What are the most important things for the patient to do when taking a chest x-ray?
- full inspiration - Posterior-anterior - erect - arms around hugging” - to move scapulae”
route of the left recurrent laryngeal nerve
hooks around the ligamentum arteriosum, under the arch of the aorta –> travels back to the laryngeal structures in the left tracheosophageal groove
anterior border of the heart is made up of what
RV, RA and a little bit of LV
how can you tell if a patient has taken in a full inspiration in a chest x-ray?
can count 7 ribs anteriorly and 11 posteriorly in the mid-clavicular line
common route of the right and left phrenic nerves
branch of cervical plexus –> descends from here down on scalene anterior between subclavien artery and vein
where does the neurovascular bundle of the ribs lie?
between the inner and innermost intercostal muscles, just inferior to the rib
what is the cut off for a large heart” measured by x-ray?”
if heart is >50% of the maximum internal diameter of the chest
what is the conventional view when looking at a saggital CT slide
from the left
route of descending aorta through the mediastinum
moves down the left of the vertebral column –> moves across towards the midline behind the oesophagus –> goes behind the muscular fibres of the diaphgram in the midline at the level of T12
what does air look like if it is present on x-ray?
- will rise - difficult to determine whether it is outside or inside the lungs - pneumothorax black air looks a lot darker black than normal
attachments of the diaphragm
xiphoid process, costal margin, tips of 11th and 12th ribs, arcuate ligaments, right an left crus
3 landmarks for drainage into/from the SVC
L and R brachiocephalic veins meet and form the SVC behind the 1st costal cartilage SVC reveives the azygous vein behind the 2nd SVC enters the RA at the level of the 3rd cartilage
right vagus nerve route
trying to get to the midline! alongside carotid artery –> alongside trachea –> BEHIND lung root –> anterior side of the oesophagus –> meets with vagus nerve from L forming the oesophageal pleuxus -> through diaphragm with the oesophagus at the level of T10
what do you encounter as you move from anterior and posterior of the manubrium ( in order)
thymus and great veins aortic arch, vagus and phrenic nerves trachea, oesophagus, thoracic duct, L recurrent laryngeal nerve
what is the retromammary space
a layer of loose aerolar CT that separates the breast from the deep fascia and provides some degree of movement over underlying struces
advantages of CT
- better contrast resolution - better able to differentiate soft tissues - can undergo post processing
phrenic nerve sensory supplies
mediastinal and diaphragmatic pleura and pericardium
What makes up the fibrous skeleton?
the figure of 8 (surrounding the AV valves) and two coronets (surrounding pulmonary and aortic valves) - joined by 2 trigones
4 structures of the posterior mediastinum
- descending aorta 2. oesophaguse with vagus nerve plexus anteriorly and thoracic duct posteriorly 3. azygous vein 4. sympathetic trunks
route of left phrenic nerve
LATERAL to the ARTERIAL structures: Aortic arch and LV –> pushes it to the lateral left dome of the diaphragm and pierces the diaphragm through its own hole
route of right phrenic nerve
LATERAL to the VENOUS structures: SVC, RA and IVC –> then pierces diaphragm with the IVC through the central tendon at the level of T8
what separates the anterior and posterior mediastinum?
the heart
what is the principle of radiography?
a vacuum tube with a filament heated up to produce electrons - accelerates them across and hits a screen
origin of vagus nerves
cranial nerve (come from the head)
What do the brachiocephalic veins drain into, and where does this occur?
join just behind the first right costal cartilage to form the SVC –> enters RA behind the 3rd cartilage
functions of the fibrous skeleton of the heart
anchor atrial and ventricular muscle mass electrically isolates A and V provides attachment for the base of each valve cusp
route of osophagus through the mediastinum
behind the trachea moves out and to the left as it descends –> pierces diaphragm slightly left of the midline at the level of T10
route of left vagus nerve
cant get to the medial structures as easily as the right lateral to aortic arch –> BEHIND lung root –> anterior oesophagus
