Anatomy - The Heart Flashcards
What are the 3 branches of the arch of the aorta?
- Brachiocephalic trunk. 2. Left common carotid artery. 3. Left subclavian artery.
What are the branches of the brachiocephalic trunk?
Right common carotid (LHS). Right subclavian (RHS).
What is the ligamentum arteriosum a remnant of and what was its function in the foetus?
Remnant of the ductus arteriosum. It’s function was to shunt blood between the pulmonary trunk and the aorta in order to bypass the non-functioning lungs.
What branch does the left vagus nerve give off as it crosses the arch of the aorta?
The left recurrent laryngeal nerve.
Briefly describe the anatomical course of the right phrenic nerve.
Lies on large veins (brachiocephalic, superior vena cava) and along the right side of the heart. Crosses in front of root of the lung.
Briefly describe the anatomical course of the left phrenic nerve.
Crosses the arch of the aorta and descends in front of the root of the lung.
What spinal roots is the phrenic nerve derived?
- C3, 4 and 5 (cervical plexus).
- pain is felt on the third fourth and fifth Dermatomes
- i.e. the neck and shoulders, shoulder tip
What does the phrenic nerve supply?
Motor innervation to the diaphragm. Sensory innervation to the pleura, peritoneum and pericardium.
Briefly describe the anatomical course of the left vagus nerve.
Crosses the aorta and behind the root of the lung. Breaks up into branches on the oesophagus (oesophageal plexus) and leaves the thorax as the anterior gastric nerve.
Briefly describe the anatomical course of the right vagus nerve.
Lies on the trachea and crosses behind the root of the lung. Breaks up into branches on the oesophagus and leaves the thorax as the posterior gastric nerve.
Does the phrenic nerve enter the diaphragm? If so where?
Yes. It pierces the central tendon of the diaphragm alongside the IVC on the right (T8).
Does the vagus nerve enter the diaphragm? If so where?
Yes. Through the oesophageal hiatus (T10).
What are the layers of the pericardium?
- Outer fibrous layer. 2. Parietal serous layer. 3. Visceral serous layer.
What structures form the left border of the heart?
- Left pulmonary artery. 2. Left auricular appendage. 3. Left ventricle.
What is the surface marking for the apex of the heart?
5th intercostal space in the mid-clavicular line.
What forms the right border of the heart?
The right sternal edge.
On what aspect of the heart would you find the left atrium?
The posterior aspect. It is closely related to the oesophagus.
Where is the Right coronary artery found?
In the atrio-ventricular sulcus.
Name the 3 main branches of the Right coronary artery.
- Sino-atrial nodal branch. 2. Right marginal branch. 3. Posterior inter-ventricular branch.
In 90% of hearts where does the posterior inter-ventricular artery arise from?
Right coronary artery
In 30% of hearts where does the posterior inter-ventricular artery arise from?
The circumflex artery.
In 20% of hearts where does the posterior inter-ventricular artery arise from?
The right coronary artery and the circumflex artery.
Name the 2 main branches of the left cononary artery.
- Circumflex. 2. Left anterior descending (LAD).
In what sulcus does the circumflex artery lie? What other large vessel can be found here?
Left atrio-ventricular sulcus. The coronary sinus can also be found here. IT passes posteriorly and drains into the RA.
Where is the SAN located?
The upper aspect of the crista terminalis in the RA.
Where is the AVN located?
Inter-atrial septum.
Name the artery that supplies: a) The SAN b) The AVN
a) SAN: Sino-atrial nodal branch of right coronary artery. b) AVN: Posterior inter-ventricular branch, usually right coronary artery.
At what phase of the cardiac cycle do the coronary arteries fill?
Diastole; when the ventricles are relaxed.
What 2 spaces does the crista terminalis divide in the RA?
It divides the smooth walled atrium from the trabeculated auricle - ridges = musculi pecanti.
What is the Fossa Ovalis a remnant of?
The Foramen Ovale. In the foetus the foramen ovale shunted blood from the RA to the LA so as to bypass the lungs.
In the ventricles, what are the chordae tendinae attached to?
The valves (mitral or tricuspid) and the papillary muscles.
How do the mitral and tricuspid valves work?
They open passively when the atria contract and then close afterwards to prevent backflow. The papillary muscles and chordae tendinae work to keep the valves closed during ventricular contraction.
How do the atrial and pulmonary valves work?
They open passively when the ventricles contract. Towards the end of systole they close to prevent the back flow of blood. The pressure of blood on the valves keeps them closed.
How would you know if the atrial and pulmonary valves were incompetent?
You would get regurgitation of blood into the ventricles. This could be heard as a diastolic murmur.
Where can you hear the pulmonary valve?
Left of the sternum, 2nd intercostal space.
Where can you hear the aortic valve?
Right of the sternum, 2nd intercostal space.
Describe the path of the phrenic nerves?
- under the mediastinal pleura
- downwards anterior to hilum of the lung
- pierce the dome of the diaphragm
Describe how the path of the left and right phrenic nerves differ?
- right - runs adjacent to the right brachiocephalic vein and superior vena cava
- left - over the arch of the aorta along the lateral side of the pericardium
Name the 2nd nerve that passes more posteriorly than the phrenic nerves?
vagus nerve
Describe the pathway the left vagus nerve?
Behind the root of the lung to join the esophagus which flows down into the abdomen
Where does the vagus nerve divide and what is its importance?
- As it passes over the aortic arch gives off the recurrent laryngeal nerve
- recurrent laryngeal nerve passes over the ligament arteriosum
- and back into the neck in the group between the trachea anteriorly and the oesophagus behind
- supplying the muscles of the larynx
- Cancerous tumours putting pressure on the laryngeal nerve results in a hoarse voice
What are the functions of the left and right brachiocephalic veins?
Drain blood from the head and neck and upper limbs combining to form the superior vena cava that enters the pericardium
What two vessels does the brachiocephalic trunk divided into?
- The right common carotid
- subclavian vessels
What 2 vessels are on the left and supply the upper half of the body?
- left common carotid
- left subclavian arteries
Describe the two layers of the pericardial and their function?
- parietal Pericardial - Covers the fibrous pericardium
- visceral pericardium - Covers blood vessels and heart
Define the surfaces of the heart?
- diaphragmatic - inferior
- Sterno-costal - Anterior
- base - posterior
Describe the pathology of the pericardial?
- distend over a long period of time
- limits ventricular filling
- reducing cardiac output
Describe the sulci that runs transversely across the heart?
- Coronary sulcus ( a.k.a. atrioventricular groove)
- Represents the wall dividing the atria from the ventricles
- contains the right coronary artery
What’s sulci can be found running the vertically?
- Anterior and posterior intraventricular sulci
- represent the wall separating the ventricles
What are pericardial sinuses and describe the two found around the heart?
- Passageways formed by the unique way pericardial folds around the great vessels
- oblique pericardial sinus - Blind ending passageway located on the posterior surface of the heart
- transverse pericardial sinus - Superiorly found in the heart, used during coronary Artery bypass grafting
Describe the left coronary arteries branching?
- initially branches to yield the left anterior descending, left marginal artery And left circumflex artery
- in 20-25% Of individuals the left circumflex artery contributes to the posterior intraventricular artery
Describe the branching of the right coronary artery?
- branches to form the right marginal artery anteriorly
- 80-85% of individuals also branches into the posterior Interventricular artery
Describe the journey of deoxygenated blood back from the myocardium?
- drains from the sub- endocardium into the thebesian veins
- Empty into the coronary sinus, located on the posterior surface of the coronary sulcus running between the left atrium and left ventricle
What are the main five tributaries which drain into the coronary sinus?
- Great Cardiac vein - originates from the apex of the heart follows the anterior interventricular groove and coronary sulcus
- Small cardiac vein - on the anterior surface
- middle cardiac vein - on the posterior surface
- left marginal vein - left posterior surface
- left posterior ventricular vein - runs along the posterior intraventricular suclus
What regions does the right Coronary artery supply?
- Right Atrium
- SA and AV nodes
- Posterior part of interventricular septum
What regions does the right marginal artery supply?
- right ventricle
- apex
What regions does the posterior intraventricular artery supply?
- right ventricle
- left ventricle
- posterior one third of IVS
What regions does the left coronary artery supply?
- left atrium
- left ventricle
- Interventricular septum
- AV bundles
What regions does the left anterior descending artery supply?
- right ventricle
- left ventricle
- Anterior two thirds of IVS
What region does the left marginal artery supply?
left ventricle
What regions does the circumflex artery supply?
left atrium
left ventricle
Describe how the aorta branches off into the vessels that supply the upper body?
- arch of the aorta
- subclavian arteries
- common Carotid artery
- Brachiocephalic trunk
- common carotid artery
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how does the sympathetic and parasympathetic nervous system influence the SA node?
- sympathetic nervous system - increases firing rate of SA node therefore increasing heart rate
- parasympathetic nervous system - decreases firing of SA node therefore decreasing heart rate
Described the Electrical delay?
- Approximately 120ms
- gives each enough time to fully object blood into the ventricles before they systole
Describe the Purkinje fibres?
- Network of specialised cells
- sub endocardial plexus of conductive cells
- abundant with glycogen and have extensive Junctions
- coordinate ventricular contractions
What are the three major arteries supplying the head and neck and upper limbs that branch of the aorta?
- brachiocephalic trunk
- left common carotid artery
- left subclavian artery
Describe the positioning of the pulmonary trunk?
- medially and Anteriorly to the right atrium
- Shares pericardial with the ascending aorta
- overlaps the route of the aorta and passes posteriorly
At what level does pulmonary trunk splitting to the right and left pulmonary arteries?
T5 to T6
Describe the differences between the left pulmonary arteries and the right pulmonary arteries?
- the left bifurcates into two branches supplying each lobe of the lung
- Right pulmonary arteries are thicker and longer, bifurcates into two branches
The superior vena cava is formed by the merging of what veins? What level does it drain into the right atrium?
- right and left brachiocephalic veins (1st costal space)
- drain at 2nd/3rd intercostal space
Where is the inferior vena cava initially formed?
Common iliac veins joining together at the pelvis (L5)
What divides the two parts the inner surface of the right atrium?
Chrisa terminalis
Describe the two parts of the interior surface that the right atrium can be divided into?
- Sinus venarum - Posterior to Christa terminalis, receives blood from the superior and inferior vena cava, smooth walls, derived from embryonic sinus venosus
- Atrium proper - anterior to Christa terminalis, includes right auricle, Rough muscular walls formed by pectinate muscles
Describe the coronary sinus?
- receives blood from the coronary veins
- opens into the right atrium between inferior vena cava orifice and right atrioventricular orifice
Describe what is found interatrial septum?
- Oval-shaped depression - fossa ovalis
- remnant of foramen ovale of the fetal heart
- shunting of blood from right to left bypassing lungs
Describe the two portions of the inferior surface of the left atrium?
- inflow portion - receives blood from pulmonary veins, smooth surface
- outflow portion - located anteriorly, includes left auricle, lined by pectinate muscles
What is the muscular ridge that divides the right ventricle?
supraventricular crest
Series regular muscular elevations right ventricle called?
trabeculae carnae
Describe the outflow portion of the right ventricle?
- conus arteriosus
- Smooth walls and no trabeculae carneae
Describe the inflow portion of the left ventricle?
- Inflow portion are lined by trabeculae carneae
- two papillary muscles presence which attaches to the cusp of the mitral valve
Describe the outflow portion of the left ventricle?
- known as the aortic vestibule
- smooth walled
- no trabeculae carneae
Describe the tricuspid valve?
- Three cusps - anterior, septal and posterior
- anchored to fibrous ring that surrounds the orifice
- RA into RV
Describe the distribution of the papillary muscle?
- five in total
- three in the right ventricle, tricuspid valve
- two the left ventricle, Mitral valve
Describe the structure of the semi-lunar valves?
- the free superior edge of leaflet is thickened (lunule)
- Widest part of the superior edge of the midline (nodule)
- at the beginning of ventricular diastolic, flow back to the heart fills the sinuses pushing the valve cusps closed
What is the function of the pericardium?
It provides a friction free surface to accommodate the heart’s sliding movements.