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Anatomy of the Heart
Heart anatomy
Question | Answer |
---|---|
What is the fibroserous sac that holds the heart and roots of the great vessels? | The pericardial sac |
Where is the pericardium located (landmarks)? | Posterior to the body of the sternum (2 through 6th ribs); anterior to 5th through 8th thoracic vertebrae |
What are the components of the pericardium (of the sac itself)? | Fibrous pericardium and the serous pericardium |
What are the (2) points of attachment of the fibrous pericardium? | Inferior: central tendon of the diaphragm; Anterior: sternum via the sternopericardial ligaments |
Where are the phrenic nerves relative to the pericardium? | The periocardiophrenic nerves are embeded in the anterior surface of the fibrous pericardium; they pass IN FRONT of the root of the lung |
What is the main function(s) of the fibrous pericardium? | 1) Anchor the heart; 2) lmits distension |
Draw the following midsagital diagram of the pericardium showing the following structures: parietal layer of the serous pericardium, large blood vessel, heart, pericardial cavity, visceral layer of serous pericardium, and fibrous pericardium | See p. 64 or slides to determine if correct |
What structure(s) does the firbous pericardium beldn in with superiorly? | The outer coats of the great vessels passing through it. |
What is the serous pericardium? | The double layer sac deep to the fibrous pericardium that also surrounds the heart (continuous) |
Where are the parietal and the visceral layers of the serous pericardium? | Parietal P. lines inner surface of the fibrous pericardium, reflects at the roots of the great vessels to become the visceral pericardium and becomes closely applied to the heart |
What is the primary function of the serous pericardium? | To lubricate the moving parts of the heart (surfaces of the pericardial cavity) |
Relative to the heart, where are the sinuses located? | On the posterior surface of the heart |
What are the two sinuses of the heart and where are they located? | The transverse sinus (between aorta/pulmonary trunk and the superior vena cava) and the oblique sinus (cul de sac around the six major veins entering the heart behind the LEFT ATRIUM) |
What two spaces does the transverse sinus connect? | It's a passage between the right to the left of the pericardial cavity; can "scoop" the inferior surfaces of the arch of the aorta and the pulmonary trunk |
What are the (4) major surfaces of the heart? | Apex, sternocostal surface, diaphraghmatic surface, and the base |
Where is the apex located? Major landmark? | Tip of the left ventricle; points anteriorly, inferiorly, and to the left; Found in the left 5h intercostal space approximately 8-10 cm from midline |
What cardiac components comprises the sternocostal surface? | Right atrium, right ventricle, small part of left ventricle |
What cardiac components comprise the diaphragmatic surface? | Mostly left ventricle, small part of the right ventricle |
What cardiac components comprise the base of the heart? | Mostly left atrium and small portion of the right atrium (most superior part of the heart) |
Where are the borders of the heart marked by? | Right border: SVC, R. atrium, IVC; Left border: A. of aorta, P. trunk, left auricle, left ventricle; Superior Border: Great vessels; Inferior border: right ventricles, part of left ventricle |
What structure divides the two parts of the right atrium? | The crista terminalis |
What is the crista terminalis? | Smooth muscular ridge; starts at roof of atrium in front of the opening of the superior vena cava extending down to the antioer lip of the inferior van cava |
What is the cavity posterior to the crista terminalis? What major vessel(s) does it receive? | Sinus venarum which receives the superior and inferior vena cava |
What major chamber lies anterior to the crista terminalis? | The atrium proper (contains the right auricle) |
What is the sulcus terminalis? | Groove on the exterior surface of the heart (over the right auricle) that marks the position of the crista terminalis; extends between the superior and inferior vena cava |
Describe the texture(s) of the wall of the right atrium | The sinus venarum: smooth; atrium proper (anterior--includes auricle): ridged by pectinate muscles (comb-like) which fan out from crista terminalis into the auricle |
Where are the pectiate muscles? | In the right atrium; they fan out from the crista terminalis into the auricle |
Name the openings into the right atrium | Sup. vena cava, Inf. vena cava, Coronary sinus, right atrioventricular orifice |
Where does the superior vena cava open into the right atrium? | In the superior posterior part of the right atrium |
Where does the inferior van cava open into? | The inferior posterior part of the right atrium, almost in line with the SVC; contains a non-function valve of embryonic importance |
Where does the coronary sinus open into ? | Opens into the right atrium between the orifice of the inferior vena cava and the right atrioventricular orifice |
What is the thebesian valve | It is a non-functioning valve of embryonic origin |
Where is the right atrioventricular orifice | Lies anterior to the orifice of the IVC, guarded by the tricuspid valve |
Where is the fossa ovalis | A depression in the interatrial septum just above the opening of the inferior vena cava |
What does the fossa ovalis mark? What did this structure do? | The location of the embryonic foramen ovale, which was a hole which allow shunting from the right to the left atria |
What is the prominent upper margin of the fossa ovalis called? | The limbus fossa ovalis |
How does the right ventricle communicate with the right atrium? | Via the right atrioventricular orifice |
How does the rigth ventricle communicate with the pulmonary trunk? | Via the pulmonary orifice |
The right ventricle is partially divided into inflow and outlfow tracts by a smooth muscular crest called ______ | Supraventricular crest |
Which of the tracts is posterior? Which of the tracts is anterior? What are their walls like? | Inflow: posterior (rough); outflow: anterior (smooth) |
What is the infundibulum? What is its shape and function? | It is the ouflow tract for the right ventricle; it is funnel shaped; it is also called the conus arterious |
What are the inflow tract walls lined with? | Prominent fleshy ridges called the trabeculae carnae |
What structures does the trabeculae give rise to? | The paillary muscles; shaped like columns/nipples |
How many sets of papillary muscles are there? What are they and how are they named? | Three sets: anterior, posterior, septal; named according to location of their bases |
What structure attaches the apex of each papillary muscle to the cusps of the tricuspid valve? | Chordae tendinae |
Which of the papillary muscles is the most constant + prominent? | The anterior papillary muscle; spring from the wall of the septum |
What is the function of the papillary muscles and the chordae tendinae? | Prevent eversion of the atrioventricular valve into the atrium during ventricular systole |
Where is the tricuspic valve? | Between the right atrium and the right ventricle |
What are the three cusps of the tricuspid valve called? | anterior, posterior, and septal cusps |
How are they secured? | Bases of the cusps secured to the fibrous ring of the heart |
* What is the septomarginal trabeculae (Moderator band) | Specialized trabeculae carnae running from the interventricular septum to the base of the anterior papillary muscle; carries right branch of the bundle of His to the anterior papillary muscle |
How many valves does the pulmonary valve have? | Composed of three delicate cup-shaped valves (valvules) |
How are the cusps named? | One is anterior, the other two are right and left and named accordingly |
What is a nodule in the pulmonary valve? | The center of the free margin of each cusp |
What is a lanula in the pulmonary valve? | The thin margins of each side of the nodule |
What is the location and the role of the sinus of the pulmonary trunk? | They are pockets/sinuses/dilations of the pulmonary trunk where the cusps attach along the curved inferior margins of each sinus; backflow of blood during diastole fills the sinuses, but the cusps prevent regurgitation of blood |
How many internal sections does the left atrium have? | Two internal sections, but no definite line of demarcation |
What veins empty into the posterior portion of the heart? | Four pulmonary veins empty into the posterior portion |
What is the texture of the walls of the posterior part of the left atrium | They are smooth |
What structures line the walls of the anterior wall and the left auricle of the left atrium? | Pectinate muscles (musculi pectinati) |
What structure is in contact with the posterior side of the left atrium? What layers/spaces lie between them? | The esophagus; only the oblique sinus and the pericardium lie between them |
How does the left ventricle differ from the right ventricle (in terms of muscular wall)? | The walls are ~3x thicker; trabeculae carnae not as well developed |
What is the outflow tract of the left ventricle called? What similar structure exists in the right ventricle? | Aortic vestibule; anologous to the conus arterious |
What separates the two ventricles? | The interventricular septum |
What are the two main portions of the interventricular septum called? | 1) pars muscularis (thick and muscular); 2) Pars membranacea (thin membranous). P. membranacea lies above the muscularis and close to the atrioventricular orifices |
Where is the mitrial valve? How many cusps does it have? What attaches them (cusps) to the wall? | Guards the atrioventricular orifice between the left atrium and ventricle; two cusps; anterior and posterior papillary muscles (via chordae tendinae)-->each chordae tendinae attached to BOTH cusps |
What is the cardiac skeleton? How is it organized? What is its function? | Fibrous connective tissue that forms the central support of the heart; has four fibrous rings for attachment of the valvules and cusps of the heart valves and bundles of the atrial and ventricular muscle fibers; prevent excessive valve stretching |
What is the physiological significance of the cardiac skeleton? | Atrial bundles attached to upper borders of rings; ventricular bundels attached to the lower bundles of the rings-->two sets of muscle bundles electrically separated except through specialized conducting system |
Where does the right coronary artery arise from? Where does it emerge from? | The right right aortic sinus-->emerges on the right side of the pulmonary trunk |
Where does it run through? | Runs through the right coronary sulcus between the right atrium and the right ventricle |
What are its major branches? | Sinuatrial nodal branch, right marginal branch (aka acute marginal*), AV nodal branch, posterior interventricular branch (posterior descending artery, PDA) |
Where does the sinuatrial branch run through? | Given off from the atrial branch near the origin of the RCA |
What area does the right marginal branch supply? | supplies the right border |
Where is the AV nodal branch given off? | At the crux of the heart |
Where does the posterior interventricular branch run through? | In the posterior interventricular sulcus |
What structures does the right coronary artery supply? | Right atrium, right ventricle (most of it), part of the left ventricle (diaphragmatic surface), posterior 1/3 of the IV septum, SA and AV nodes (most of the time) |
Where does the left coronary artery arise from? | From the left aortic sinus and emerges on the left side of the pulmonary trunk |
Where does the left coronary artery branch? | While it is still behin the left auricle, brachnes into the anterior interventricular branch (left anterior descending, LAD) and the circumflex branch |
Where does the anterior interventricular artery run through? | Descends towards the apex in the anterior interventricular sulcus |
Where does the circumflex artery run through? What does it supply? | Runs to the left in the left coronary sulcus between left auricle and left ventricle, continues onto the posterior of the hear; if it reaches the posterior interventricular sulcus, may give rise to the posterior interventricular artery |
What is left coronary dominance? How common is it? | in 10% of cases, the left coronary artery (by way of circumflex branch) may give rise to posterior interventricular artery |
What are the branches of the circumflex artery? | The left marginal branch (obtuse marginal) supplies left border; occasionally the SA and AV nodal branches |
What structures does the left coronary sartery supply? | left atrium, left ventricle (most), part of the right ventricle, anterior 2/3 of IV septum (including the bundle of His), SA and AV node (occasionally) |
Where is the coronary sinus? What is its major role? | Lies in the left coronary sulcus from the left margin of the heart to its orifice in the right atrium; receives most of the veins in the heart |
Where is the great cardiac vein? Where does it pass through? What is it continuous with? | Lies in the anterior interventricular sulcus and passes upward and to the left of the left coronary sulcus; becomes continous with the left margin of the hear after receiving the oblique vein of the left atrium |
Where is the middle cardiac vein? Where does it pass through? Where does it empty into? | Runs in the posterior interventricular sulcus; empties into the coronary sinus ont he posterior surface of the heart |
Where is the small cardiac vein? Where does it pass through? Where does it empty into? | Parallels the right marginal artery; passes the right coronary sulcus to the posterior of the heart and drains into the coronary coronary sinus |
What are the only veins that do not empty into the coronary sinus? | The anterior cardiac veins and the least cardiac veins |
Where are the anterior cardiac veins? Where do they run through? Where do they empty? | Arie on the anterior surface of the right ventricle, pass across the right coronary sulcus and penetrate the anterior wall of the right atrium directly |
What are the venae cordis minimis (least cardiac veins)? | Minute veins int he muscular walls of the heart-->empty directly into the cardiac chambers |
What structure provides the sympathetic and the parasympathetic input to the heart? Where is it located? | The cardiac plexus; diffuse netwrok of delicate fibers extending from in front of the trachea to the aortic arch, pulmonary trunk, and ligamentum arteriosum |
What are the three cervical cardiac nerves? Where do they arise from? What signals do they carry? | Superior cervical, middle cervical, and inferior cervical (named after the ganglion they arise from); sympathetic; |
Where do the thoracic cardiac nerves arise from? | From the upper four or five thoracic ganglia of the sympathetic trunk |
The sympathetic fibers of the plexus are all ____gaglionic. | Postganglionic |
* Where do the preganglionic fibers of the sympathetic cardiac nerves arise from? | From the upper four or five thoracic segments of the spinal cord |
* What are the three main function of the sympathetic cardiac branches? | Accelerate heart rate, increase force of heart beat, dilate the coronary arteries |
* Where does the heart get its parasympathetic branches? | From the vagus nerves |
How many cervical cardiac nerves supply the heart? Where do they arise from? | Two of them from the vagus nerves of the neck (superior cervical and inferior cervical) |
Describe the thoracic cardiac branches | arise from the vagal trunks or the recurrent laryngeal branches of the vagus |
The parasympathetic fibers of the plexus from the vagi are ____ganglionic and synapse within _______ ganglia within the _______ or in the _______ of the heart | preganglionic, small, plexus, walls |
* What are the (3) main functions of the parasympathetic innervation of the heart? | Decrease the heart rate, reduce force of contraction, constrict coronary arteries |
Describe the path the afferent (sensory) fibers of the heart take to reach the spinal cord | Visceral afferents from the heart join the cardiac plexus and pass along the sympathetic and the vagal cardiac branches |
What information is carried by the vagal afferents of the heart? | Concerned with cardiac reflexes (blood pressure, rate, etc) |
* What information is carried by the sympathetic afferents of the heart? What levels of the spinal cord do they enter? Why is this significant? | Conduction of the pain sensations of the heart; T1 and T5 (they enter via the dorsal roots), may result in referred pain to the dermatomes supplies by the upper thoracic spinal nerves (T1, T2: ulnar border of upper limb; T2-T5: upper part of thorax) |
What are the components of the conducting system of the heart? | Sinuatrial node, atrioventricular node, atrioventricular bundle (of His) |
Describe the shape, location, and purpose of the sinuatrial node | Crescent shaped structure (5-8 mm in length) occupying the whole thickness of the wall of the right atrium; on the anterior lip of the superior vena caval orifice near the top of the crista terminalis; pacemaker |
Describe the shape, location, and purpose of the atrioventricular node | Embedded in the interatrial septum close to the opening of the coronary sinus; on the fibrous AV ring close to the attachment of the septal cusp of the tricuspid valve; in the septum extends forward from the opening of the c. sinus; continues as AV bundle |