Q: Which two arteries supply the myocardium, epicardium and pacemaking tissue of the heart? A: The right and left coronary arteries. Q: The right and left coronary arteries are both branches of what, and both give branches to the atria and ventricles and they run in the what? A: Ascending aorta and coronary sulcus. Q: Where do the right and left coronary arteries generally arise? A: The right (anterior) aortic sinus and the left (posterior) aortic sinus, respectively. Q: How may a third coronary artery be present (usually) in the heart? A: A right coronary branch (the conus artery) arising separately from the anterior coronary sinus. (Present in 36% of hearts) Q: What are the branches of the right coronary artery? A: The conus artery, the right diagonal artery, the right marginal artery, the posterior interventricular artery and the atrioventricular nodal artery. Q: What does the conus artery supply? A: The conus arteriosus. Q: What does the right diagonal artery supply? A: The anterior aspect of the right ventricle. Q: What does the right marginal artery supply? A: The lateral aspect of the right ventricle. Q: Where does the posterior interventricular artery run? A: It branches off after the right coronary artery has travelled along the coronary sulcus to the posterior surface and it runs in the posterior interventricular sulcus. Q: Which artery arises opposite the origin of the posterior interventricular artery in 85% of cases, enters the posterior part of the atrio ventricular groove and passes to the AV node located at the base of the interventricular septum (supplying the AV node and bundle)? A: The atrioventricular nodal artery. Q: What blood vessels usually supply the sinuatrial node? A: The sinuatrial nodal artery arises from the right coronary in 55% of cases and arises from the left coronary or its circumflex branch in 45% of cases. Q: What two structures does the initial stem of the left coronary artery lie between? A: The pulmonary trunk and the left auricular appendage. Q: What branches does the left coronary artery give? A: The anterior interventricular artery, the left diagonal artery, the circumflex artery, the left marginal artery and a possible artery to the AV node (as the terminal branch of the left coronary artery in 20%) Q: What are the 5 areas the right coronary artery supplies? (The left coronary artery supplies the reciprocal.) A: 1. All of the right ventricle (except a small region of the anterior interventricular sulcus). 2. A variable part of the left ventricular diaphragmatic surface. 3. The posterior inferior 1/3 of the interventricular septum. 4. All of the right atrium and part of the left. 5. The conducting system as far as the proximal parts of the right and left crura. Q: Do coronary anastomoses provide rapidly available collateral routes in the event of a sudden coronary obstruction? A: No, but the are more effective in slowly progressive coronary obstructions. Q: Anastomoses are present throughout the cardiac wall thickness. Which two arteries anastomose at the apex? A: The anterior and posterior interventricular arteries. Q: Anastomoses are present throughout the cardiac wall thickness. Which two arteries anastomose at the anterior aspect of the right ventricle? A: The anterior inerventricular artery and right diagonal branches. Q: Anastomoses are present throughout the cardiac wall thickness. Which two arteries anastomose at the posterior aspect of the left ventricle? A: The posterior interventricular artery and the circumflex branches. Q: What are the three groups of veins draining the heart? A: The coronary sinus and its tributaries, the anterior cardiac veins and the venae cordis minimae (Thebesian veins). Q: What regions of the heart do the coronary sinus and its tributaries receive blood from? A: The whole heart including the septa, except for the anterior region of the right ventricle and small parts of the left atrium and ventricle. Q: Where do the anterior cardiac veins receive blood from? A: The anterior right aspect of the right ventricle and a region around the right cardiac border where the right marginal vein joins this group. These veins end in the right atrium. Q: Where do the venae cordis minimae open into? A: The right atrium and ventricle and to a lesser extent the left atrium and sometimes the left venricle. They open directly into the heart chambers. Q: What structure of the heart lies in the posterior coronary sulcus and opens into the right atrium between the IVC opening and the right atrioventricular orifice? A: The coronary sinus. Q: Does the coronary sinus opening have a valve? A: Yes. Q: Which veins does the coronary sinus receive blood from and where to they lie? A: * The great cardiac vein (anterior interventricular vein) : in the anterior interventricular sulcus. * The small cardiac vein : in the posterior coronary sulcus between the right atrium and ventricle. * The middle cardiac vein : in the posterior interventricular sulcus. * The Posterior vein of the left ventricle : to the left of the middle cardiac vein. * The Oblique vein of the left atrium : on the back of the left atrium. Q: What is the normal heart rate in beats per minute? A: 60 to 100. Q: What is regarded as the principal pacemaker of the heart and intiator of each cardiac cycle? A: The sinuatrial node. Q: Where is the SA node located? A: The supreior limits of the crista terminalis in the wall of the right atrium. Q: Describe the shape of the sinuatrial node. A: It is a flattened ellipsoid, it is 10 to 20 mm in length, 1 mm thick and 3 mm at its maximun lateral convexity. Q: Where is the atrioventricular node located? A: Under the right atrial endocardium, 1 cm above the septal margin of the orifice of the coronary sinus. Q: Describe the size and shape of the AV node. A: It is an oval (7 mm by 3 mm by 1 mm) and its anteroinferior end becomes the common atrioventricluar bundle. Q: What structure is believed to be responsible for the atrioventricular conduction delay? A: The atrioventricular node. Q: Describe the course of the atrioventricular bundle. A: It course from the AV node along the posterior inferior margin of the membranous part of the interventricular septum to the muscular part where it divides into right and left branches. The right branch continues subendocardially to the septomarginal trabecula, which it traverses to reach the base of the anterior papillary muscle of the right ventricle, from which it goes to the rest of the right ventricle. The left branch is actually several separate fasicles (separately ensheathed), which form a flattened sheet over the subendocardium. This covers the muscular part of the interventricular septum and distributes to the left ventricle. Q: What 3 major results will stimulation of the vagus have on the heart? A: 1. Slowing of the heart. 2. Reduction of blood pressure. 3. Constriction of the coronary arteries. Q: What 4 major results will stimulation of the sympathetic nerves have on the heart? A: 1. Increased blood pressure. 2. Increased heart rate. 3. Vasodilation of the coronary arteries. 4. An increase in the force and speed of contraction of the cardiac muscle. Q: The sympathetic nerve supply of the heart is from the postganglionic fibres of which sympatheitc ganglia and from the thoracic cardiac nerves from which segments of the spinal cord? A: The superior, middle and inferior cervical ganglia and segments T1 to T4. Q: What are the pain sensory fibres thought to pass back to the CNS with? A: The sympathetic fibres (T1 to T4). Q: The parasympathetic supply of the heart is from cardiac branches of what cranial nerve? A: The vagus nerve. Q: Where is the superficial cardiac plexus located? A: Below the arch of the aorta, anterior to the right pulmonary artery and near the ligamentum arteriosum. Q: Where is the deep cardiac plexus located? A: At the back of the aorta, in front of the tracheal bifurcation. Q: What does the left coronary plexus supply? A: The left atrium and ventricle. Q: What does the right coronary plexus supply? A: The right atrium and ventricle.