CVS Flashcards
Where does the mediastinum lie?
Inferior surface of the diaphragm to the superior thoracic aperture, and from the sternum and costal cartilages anteriorly to the thoracic vertebra posteriorly
Where does the superior mediastinum occur?
T4
What structures are found in the superior mediastinum?
SVC Brachiocephalic v. Arch of aorta Vagus Phrenic nerve Trachea Oesophagus
What structures are found in the anterior mediastinum?
Sternopericardial ligament (anchors pericardium to sternum) Remnants of thymus gland which becomes fibrous and fatty after puberty
What structures are found in the middle mediastinum?
Heart
Ascending aorta
SVC
What structures are found in the posterior mediastinum?
Oesophagus
Thoracic aorta
Azygous and hemiazygous veins
What structure makes the base of the heart?
LA (T6-9)
What are the 4 surfaces of the heart?
Anterior - sternocostal
Inferior - diaphragmatic
Left - LV
Right - RA
What are the 4 borders of the heart?
Right: RV
Inferior: mainly RV and partly LV
Left: LV
Superior: RA and LA
What level is the heart located?
T5-8
How does the position of heart change with height?
Taller - more vertical
Smaller - more transversely placed
Describe layers to the pericardium
Fibrous outer layer
Serous inner layer: parietal, pericardial cavity, serous)
Describe endocarium
Simple squamous epithelium on BM adhered to connective tissue
Describe epicardium
Connective tissue, BM and simple squamous epithelium
Contains branches of the coronary arteries
Forms the serous visceral layer
Name the semi-lunar valves
Aortic and pulmonary (3 cusps)
Is mitral valve bicuspid or tricuspid?
Bicuspid
What is the annulus fibrosis?
A fibrous structural support for the heart chamber - supports the atrioventricular septum
Composed of dense connective tissue
What is the function of the chord tendineae?
Tendons that connect papillary muscles to valve cusps
What is the function of the papillary muscles?
Prevents inversion of valve
What is the function of the annulus fibrosis?
Keeps all valves open, preventing tears and back flow
Acts as an electrical insulator by preventing electrical impulses through atria and ventricles, so delaying contraction, to allow ventricles to fill up
What is the function of the coronary arteries?
Supply the myocardium and epicardium and are located deep in the epicardium, embedded in fat
Where do the coronary arteries arise from?
Aortic sinuses at the proximal part of the ascending
What does the RCA divide into further?
Sino-atrial (SA) nodal branch - SA node
R marginal branch - R of heart
AV nodal branch - AV node
Posterior IV branch - both ventricles
What does the LCA divide into further?
Circumflex
Anterior IV branch (LAD)
What are the two main sulci of the heart?
Coronary sulcus - between atria and ventricles
Interventricular sulcus - between ventricles
Where do the cardiac veins drain into?
Coronary sinus - a wide venous channel on the posterior side of the heart which feeds into the RA
What are the cardiac veins and what coronary aa. do they lie along?
Great cardiac vv. - LAD
Middle cardiac vv. - posterior descending aa.
Small cardiac vv. - R marginal aa.
At what level does the aortic arch lie?
T4
At what level is the bifurcation of abdominal aorta?
L4
At what level is the bifurcation of common iliac aa.?
L5
What are the 3 arteries that branch of the arch of the aorta?
Brachiocephalic trunk
L common carotid aa.
L subclavian aa.
What are the arteries that branch off the descending aorta?
Bronchial aa.
Oesophageal aa.
Pericardial aa.
Posterior IC aa. (only one indentifiable on wet specimen)
What are the tributaries of the SVC
L and R braciocephalic vv.
Azygous vv.
(Internal jugular vv. + subclavian vv. -> brachiocephalic vv.)
What is the function of the azygous vein?
Drain blood from the posterior IC veins to the SVC and found immediately to the right of the thoracic aorta
What are the hemiazygous veins?
Drain L IC veins and then drain into the azygous vein at T8/9
Where do the structures in the neuromuscular bundle arise from?
Larger structures that run vertically along the anterior and posterior chest wall
What drains into the azygous vein?
Posterior IC veins and hemiazygous vein
What arises from the descending aorta?
Posterior chest wall IC arteries
Where do the intercostal nerves arise from?
Ventral ramus of spinal nerves
What drains into the internal thoracic vein?
The anterior IC veins and then it drains into the bachiocephalic vein
What does the internal thoracic artery give rise to?
Branches off of the subclavian artery and gives rise to the anterior IC arteries
Where is the thoracic duct located?
Drains the posterior chest wall
Located on the vertebral lies between the azygous vein and the descending thoracic aorta on the R of the posterior thoracic wall
Where does the thoracic duct commence?
L1 as the cisterna chyli
Where does the thoracic duct drain into?
Medial end of L subclavian vein
What is the R upper quadrant drained by?
R lymphatic duct - which drains into the medial end of the R subclavian vein
What are the 5 different planes in the superior mediastinum (anterior to posterior)?
Glandular plane Venous plane Arterial-nervous plane Visceral plane Lymphatic plane
What is found in the glandular plane of the superior mediastinum?
Remnants of the thymus gland
What is found in the venous plane of the superior mediastinum?
Brachiocephalic vv
SVC
What is found in the arterial-nervous plane of the superior mediastinum?
Branch of aorta
Vagus nn
Phrenic nn
What is found in the visceral plane of the superior mediastinum?
Trachea
Oesophagus
What is found in the lymphatic plane of the superior mediastinum?
Thoracic duct
What is the effect of innervation from the vagus nerve?
Part of the parasympathetic system to control heart rate and regulate breathing, however it has some sympathetic influence through peripheral chemoreceptors
Where are the vagus nerves situated?
L: anterior to aortic arch then behind L bronchus and to the oesophagus
R: behind R bronchus and oesophagus
Both enter abdomen through the oesophageal hiatus of the diaphragm
Where do the superficial veins in the upper limbs arise from?
The dorsal venous arch on the back of the hand
What superficial vein is most lateral in the upper limbs and what does it drain into?
Cephalic vein - drains into the axillary vv.
What superficial vein is most medial in the upper limbs and what does it drain into in the upper limbs?
Basilic vein - becomes continuous with the brachial vein (deep vein) and drains into axillary vv.
What vein connects the basilic and cephalic veins and where in the upper limbs?
Median cubital vein in the median cubital fossa
What is the term for deep veins lying alongside corresponding arteries?
Venae comitantes
Where does the subclavian aa. become axillary aa in the upper limbs?
Lateral border of the 1st rib
Where does the axillary aa. become the brachial aa. in the upper limbs?
Inferior border of the teres major muscle
What two arteries does the brachial artery give rise to in the upper limbs?
Radial (lateral) and ulnar (medial)
What do the names of the deep veins in the legs correspond to?
The name of the arteries
Where do the superficial veins of the lower limbs arise from?
The dorsal arch of the foot
What superficial vein runs up the lower limbs anteriorly to the medial malleous?
The long saphenous vein and drains into the femoral vv.
What superficial vein runs up the lower limbs posteriorly to the lateral malleous?
Short saphenous vein and drains into the popliteal vv
Describe the main arteries of the lower limb from top of led to feet
External iliac aa
Superficial femoral aa (and deep femoral aa)
Popliteal aa.
Anterior tibial aa and posterior tibial aa
Fibular aa (from post tibial aa)
Dorsalis pedis (from ant tibial aa)
What artery provides temporal and facial pulses?
Branches of external carotid
What artery provides common carotid pulses?
Common carotid aa from aortic arch
What artery provides brachial pulse?
Brachial aa from axially aa
What artery provides radial pulse?
Radia aa branch off of brachial aa
What artery provides femoral pulse?
Femoral aa
What artery provides dorsals pedis pulse?
Dorsalis pedis aa from the ant tibial aa
What makes up the anterior surface of the heart?
RV (most)
RA
LV
What are the main features of the RA?
Openings for the IVC, SVC coronary sinus
Fossa ovalis
Musculi pectinati
Tricuspid valve
Extending from anterograde-medial portion is the R auricle (RA appendage)
What are the main features of the RV?
Tricuspid valve: 3 valves, chordae tendineae, papillary muscles x3
Trabeculae carnae
Moderator band - connects the IV septum with the anterior wall
Opening for the pul. trunk
IV septum
What is the purpose of the papillary muscles?
Pull on the chord tendinae to prevent prolapse of the valve leaflet during ventricular systole
What are the main features of the LA?
Openings for the pul veins: L and R superior/inferior
Bicuspid (mitral) valve
Smooth walled, small chamber lying most posterior and superior against the oesophagus
Forms base of the heart
What are the main features of the LV?
Bicuspid (mitral) valve: 2 valve cusps and 2 pap muscles
Trabeculae Carneae
Opening for the aorta
Forms apex of the heart
Wall is x3 thicker than the R as it pumps blood around the body
What nerves innervate the heart wall?
Vagus nerve (parasympathetic) - visceral layer
Sympathetic fibres (T1-4) which synapse in the ganglionic chain and continue through the cardiac plexus at the trachea bifib (pain and sensory) - heart muscle and visceral
Phrenic nerve - fibrous and parietal layers
Describe innervation of SA and AV nodes
Motor fibres innervate and influence nodes of modified cardiac muscle cells that generate electrical pulse (pacemaker cells) - these are punkinje cells and their branches are the punkinje fibres
Where are the purkinje fibres located?
In the subendothelial surface and rapidly transmit AP from the AV node to the myocardium
What is the effect of parasympathetic innervation?
Reduces heart rate
Reduces force of contraction
Vasoconstriction of coronary arteries
What is the effect of sympathetic innervation?
Increases heart rate
Increases force of contraction
What is referred pain?
Pain that emanates from an organ/viscus but experienced somaticcaly
Give example of referred pain
Pain of Myocardial ischaemi is carried back to T1-4 by sympathetic afferent nerves that supply heart
Pain is also felt on the anterior chest and medial side of the L arm
What causes referred pain?
Dermatomes responsible for cutaneous innervation are supplied by the same spinal cord levels as visceral afferents of the heart
Dermatome T1 innervates medial side of the L arm as pain from heart usually left of the chest. The brain isn’t used to receiving such strong signals from the heart, so it interprets them as pain in the chest and left arm.
