Week 12 Anatomy - The Heart Flashcards
What is the apex of the heart, and from a surface anatomy perspective, where would you find it?
Apex = inferolateral part of left ventricle, “the pointy bit”
Usually found at 5th ICS, mid clavicular line
What is the base of the heart? What blood vessels is it associated with?
The posterior aspect of the heart, largely left atrium. Associated with paired pulmonary veins, pulmonary trunk, and superior and inferior venae cavae
What vertebral levels do the base of the heart correlate with?
T6-T9
What part of the heart forms the anterior aspect?
Right ventricle
What part of heart forms diaphragmatic aspect?
Left ventricle
What structures form the right heart border on chest X-ray?
Right atrium, SVC and IVC
What structures from left heart border on CXR?
Left ventricle
Where does the right coronary artery arise from?
Right aortic sinus
Describe the course of the RCA?
Runs from aorta, through coronary sulcus (between RA and RV) and gives off ‘right marginal branch’ before wrapping around posteriorly, continuing as ‘Posterior inter ventricular branch of RCA’
What structures does the RCA supply?
60% of people, SA node
80% AV node
Supplied RA and RV, posterior inter ventricular septum
What are the branches of the RCA?
SA nodal branch
Right marginal branch
AV nodal branch
Posterior inter ventricular branch
Where does LCA arise from?
Left aortic sinus
Describe course of LCA?
Runs in coronary sulcus between L auricle and pulmonary trunk, then gives off LAD down the inter ventricular groove, and the later circumflex artery which courses around to the posterior aspect of the heart and anastomoses with the RCA
What are branches of the LCA?
Circumflex
Left marginal (off the circumflex)
LAD
Lateral/diagonal branch (from LAD)
Perforating interseptal branches
What are sites of anastomoses in the coronary circulation?
Left circumflex + RCA
LAD + Post. Int. Artery
What is meant by the term ‘dominant circulation?’
Defined by the vessel of origin which supplies the posterior inter ventricular artery. 80% hearts are right circulation dominant, 20% left dominant or co-dominant.
What is the location and role of the coronary sinus?
Main vein of heart that runs L –> R within posterior coronary sulcus. Drains blood from small, middle and great cardiac veins
What are the layers of the pericardium?
Fibrous (outer)
Serous (visceral and parietal pericardium)
*Parietal pericardium also known as epicardium
What is the function of the fibrous pericardium?
Relatively non distensible fibrous connective tissue which provides structure to heart and prevents rapid overfilling, but also the cause of why tamponade can occur
From surface anatomy perspective, where does the brachiocephalic vein form?
Behind the stereo-clavicular joint (bilaterally)
Brachiocephalic artery is formed by the confluence of internal jugular vein and subclavian vein
What vessel is formed by the union of the R + L brachiocephalic veins?
Superior vena cava
What structures does the SVC return blood from?
Everything above the level of the diaphragm (excepts heart and lungs)
At what level does the IVC enter the right atrium?
3rd costal cartilage
How does the SVC relate to the trachea and the aorta?
Passes anterior to the trachea, and posterolateral to the ascending aorta
In order of anterior to posterior, what are the structures of the superior mediastinum?
Thymus
Veins
Arteries
Airway
Oesophagus
Lymphatic trunk
What are the only branches of the ascending aorta?
Coronary arteries
How does the aorta relate to the trachea?
Arch of aorta passes anteriorly to the R) pulmonary artery and in front of the carina
What are the branches (in order) from the arch of aorta? (Remember, my right arm is stronger)
Brachiocephalic trunk
Left common carotid
Left subclavian artery
At what location does the brachiocephalic trunk divide into RCC and R subclavian vein? (Hint, also same answer for where LCC and L subclavian
At the level of the stereo-costal joint
What vessel does the vagus nerve travel with down into the mediastinum after it exits the cranium?
Common carotid artery (bilaterally - travels within carotid sheath)
Where does the path of the R and L vagus nerves no longer mirror each other?
As it enters the base of the neck
What is the course of the Right Vagus nerve?
Enters thorax anterior to R) subclavian artery, gives off branch of R) recurrent laryngeal nerve (hooks under and back up from subclavian artery)
R vagus continues to run postero-inferiorly to the R side of the trachea, posterior to R) brachiocephalic vein, SVC
What plexus does the vagus nerve form when it passes below root of R lung?
Right pulmonary plexus, before reforming into a single nerve again before forming R oesophageal plexus
What is the course of the L) vagus nerve?
Passes inferiorly from neck alongside left common carotid, before entering mediastinum between LCC and L subclavian artery
Travels down to reach the left side of aortic arch, curving medially as to passes over the top of aorta, giving off L recurrent laryngeal nerve
Then as it passes posterior to root of left lung, divides to pulmonary plexus, and then onto oesophageal plexus
What spinal roots does the phrenic nerve originate from?
C3-C5 (keeps the diaphragm alive!)
How does the phrenic nerve travel into the mediastinum? What is the major point of difference to the course of the vagus nerve?
It enters superior mediastinum between subclavian artery (which lies posterior to phrenic nerve) and brachiocephalic vein.
Passes ANTERIORLY to root of the lung
What is the sinus venarum?
Smooth, thin walled posterior aspect of right atrium into which the SVC, IVC and coronary arteries open into
What is the anterior wall of the right atrium composed of?
Rough, muscular wall composed of pectinate muscles
