Heart Anatomy I and II Flashcards
What are the superior, inferior, anterior, and posterior borders of the mediastinum?
Superior = superior thoracic aperture
Inferior = diaphragm
Anterior = sternum + costal cartilages
Posterior = thoracic vertebrae
The inferior mediastinum is subdivided by the ___________ into 3 parts
Pericardium
The inferior mediastinum is subdivided by the pericardium into anterior, middle, and posterior parts. What structures are found in the middle subdivision?
Pericardium and its contents = heart, ascending aorta, pulmonary trunk, SVC
Is it possible for structures to exist in more than one mediastinal compartment?
Yes, some structures like the esophagus pass vertically and lie in more than one mediastinal compartment
The pericardium covers the heart and beginnings of the great vessels. It is a closed sac composed of what 2 major layers?
Fibrous pericardium = tough external layer
Serous pericardium = composed mainly of mesothelium (single layer of flattened cells)
The fibrous pericardium is continuous with the _____ _____ of the diaphragm. The internal surface is lined with a parietal layer of _______ pericardium, which is also reflected onto the heart at the great vessels.
Central tendon; serous
The fibrous pericardium is continuous superiorly with what 2 layers of named connective tissue?
- Tunica adventitia (perivascular connective tissue of great vessels entering and leaving the heart)
- Pretracheal layer of deep cervical fascia
The fibrous pericardium is attached anteriorly to the posterior surface of the sternum by what structures?
Sternopericardial ligaments (which are highly variable in their development)
The fibrous pericardium is bound posteriorly by _____ _______ to structures in the ______ ______
Loose CT; posterior mediastinum
The fibrous pericardium is continuous inferiorly with the central tendon of the diaphragm. What ligament forms the site of continuity?
Pericardiacophrenic ligament
[however, note that fibrous pericardium and central tendon are NOT separate structures that fused together secondarily, nor are they separable by dissection]
Overall, what connections are involved in tethering the heart inside the fibrous pericardium?
Tunica adventitia, pretracheal layer of deep cervical fascia, sternopericardial ligaments, loose connective tissue, and pericardiacophrenic ligament connecting to the central tendon of the diaphragm
The serous pericardium is composed mainly of mesothelium - a single layer of flattened cells forming an epithelium that lines both the internal surface of the fibrous pericardium and the external surface of the heart. What are the 2 layers of the serous pericardium?
Visceral layer - forms the epicardium (outermost layer of the heart wall)
Parietal layer - where the aorta and pulmonary trunk leave the heart, and where the SVC, IVC, and pulmonary veins enter
Where do the visceral and parietal layers of serous pericardium become continuous?
At the beginning of the great vessels
What provides the main arterial supply to the pericardium?
Pericardiacophrenic a. (slender branch of internal thoracic a.)
The main arterial supply to the pericardium is the pericardiacophrenic a., which is a slender branch of the ______ ______ artery and often accompanies the _______ nerve to the diaphragm
Internal thoracic
Phrenic
The main arterial supply to the pericardium is the pericardiacophrenic a.. What arteries provide smaller contributions?
Musculophrenic a. (Terminal branch of internal thoracic a.)
Bronchial, esophageal, and superior phrenic aa. (Branches of thoracic aorta)
Coronary aa. (First branches of aorta; supply visceral layer of pericardium only!)
Smaller contributions to the arterial supply of the pericardium include the following:
Musculophrenic a.
Bronchial, esophageal, and superior phrenic aa.
Coronary aa.
What arteries do the above branch off of?
Musculophrenic - internal thoracic a.
Bronchial, etc. - thoracic aorta
Coronary aa. - aorta (remember only supplying visceral pericardium)
What provides venous drainage of pericardium?
Pericardiacophrenic veins (tributaries of the brachiocephalic or internal thoracic vv.)
Variable tributaries of the azygous venous system
The pericardiacophrenic veins provide venous drainage to the pericardium. What are these veins tributaries of?
Brachiocephalic or internal thoracic veins
What nerves provide innervation to the pericardium?
Phrenic nerves (C3-5)
Vagus nn.
Sympathetic trunks
Innervation to the pericardium is provided by the phrenic nerves, vagus nerves, and sympathetic trunks. Which of those is the primary source of sensory fibers?
Phrenic nerves (C3-C5)
Pain sensations conveyed are commonly referred to skin (C3-5 dermatomes) of ipsilateral supraclavicular region
Innervation to the pericardium is provided by the phrenic nerves, vagus nerves, and sympathetic trunks. The phrenic nerves are the primary source of sensory innervation. What are the functions of the other 2?
Vagus nerves - function uncertain
Sympathetic trunks - vasomotor
What structure, found posterior to the intrapericardial parts of the pulmonary trunk and ascending aorta, anterior to the SVC, and superior to the heart atria, forms a passage within the pericardial cavity between 2 groups of vessels and the reflections of serous pericardium surrounding them?
Transverse pericardial sinus
The transverse pericardial sinus forms a transversely running passage within the pericardial cavity between what 2 groups of vessels (and the reflections of serous pericardium surrounding them)?
- Aorta and pulmonary trunk
2. SVC, IVC, pulmonary veins
What is the surgical significance of the transverse pericardial sinus?
After the pericardial sac is opened anteriorly, a finger can be passed through this sinus posterior to the ascending aota and pulmonary trunk.
By passing a surgical clamp or ligature around these vessels, inserting the tubes of a coronary bypass machine, then tightening the ligature, surgeons can stop or divert the circulation of blood in these arteries while performing cardiac surgery such as coronary bypass grafting.
What structure forms a wide, pocket-like recess in the pericardial cavity posterior to the base of the heart (formed by left atrium)?
Oblique pericardial sinus
The oblique pericardial sinus is bounded laterally by the pericardial reflections surrounding the pulmonary veins and ______, and posteriorly by the pericardium overlying the anterior aspect of the _________.
It can be entered inferiorly and will admit several fingers, but they cannot pass around any of these structures because the sinus is a ______ sac.
IVC; esophagus
Blind
What is cardiac tamponade its symptoms?
Heart compression due to fluid in the fibrous pericardium, which compromises heart function and therefore circulation fails.
Symptoms: engorged veins in face and neck (due to backup of blood beginning where the SVC enters the pericardium), chest pain, low blood pressure, fainting, lightheadedness, tachycardia, shortness of breath or tachypnea, distant heart sounds, swelling in extremities
Cardiac tamponade is characterized by compression of the heart within the fibrous pericardium. What might cause this compression?
Extensive pericardial effusion (fluid in heart cavity)
Hemopericardium (blood in heart cavity) - results from perforation of weakened area of heart muscle owing to previous myocardial infarction, bleeding into pericardial cavity after cardiac surgery, or from stab wounds
The apex of the heart is directed anteriorly and to the _____. It is formed by the inferolateral part of the ____ _____.
Left; left ventricle
Describe the position of the apex of the heart relative to body landmarks nearby
Lies posterior to the left 5th intercostal space, usually about 9 cm from the median plane
What part of the heart remains motionless throughout the entire cardiac cycle?
Apex
The base of the heart faces most posteriorly. What chambers of the heart make up the base?
Mainly the left atrium, some from right atrium
Where are the sounds of mitral valve closure maximal?
Apex
Describe orientation/position of the base of the heart relative to body landmarks nearby
The base faces posteriorly toward bodies of vertebrae T6-9 and is separated from them by the pericardium, oblique pericardial sinus, esophagus, and aorta
The base of the heart extends superiorly to the bifurcation of the ________ _______, and inferiorly to the ________ ________
It receives ________ _______ on the right and left sides of its left atrial portion, and ________ at the superior and inferior ends of the right atrial portion
Pulmonary trunk; coronary sulcus
Pulmonary veins; IVC
The right atrium forms the right border of the heart. It receives venous blood from what 3 structures?
SVC, IVC, coronary sinus
What structure forms a conical muscular pouch that projects from the right atrium like an add-on room, increasing the capacity of the atrium as it overlaps the ascending aorta?
Right auricle
The interior of the right atrium is characterized by:
_______ ______ = smooth, thin-walled, posterior part which the SVC, IVC, and coronary sinus open into, bringing poorly oxygenated blood into the heart
Rough, muscular anterior wall composed of _______ muscle.
Right _______ orifice through which the right atrium discharges poorly oxygenated blood to the right ventricle.
Sinus venarum
Pectinate
Atrioventricular
What structure, associated with the right atrium, forms the external separation of the rough and smooth atrial wall?
Sulcus terminalis (terminal groove)
What structure, associated with the right atrium, forms the internal separation of rough and smooth atrial wall?
Crista terminalis
What structure separates the right and left atria? What embryologic remnant would you find here?
Interatrial septa
Fossa ovalis = remnant of foramen ovale in fetus
Which heart chamber forms the largest part of the anterior surface and almost the entire inferior border of the heart?
Right ventricle
______ ______ refers to the superior taper of the right ventricle, leading to the pulmonary trunk
Conus arteriosus
_______ ______ are irregular muscular elevations found in the interiors of the right and left ventricles
Trabeculae carnae
Compare the trabeculae carnae found in the right vs. left ventricles
Those in the left ventricle are finer and more numerous than in the right ventricle
What structure associated with the right ventricle separates the ridged muscular wall of the inflow part of the chamber from the smooth wall of the conus arteriosus (outflow part)?
Supraventricular crest
What valve forms the inflow part of the right ventricle?
Right atrioventricular valve (tricuspid valve)
Describe the location of the right AV (tricuspid) valve relative to body landmarks
Right AV valve is located posterior to body of sternum at the level of 4th and 5th intercostal spaces
The right AV (tricuspid) valve is surrounded by fibrous rings of the _____ of the heart.
_______ _______ attach to the free edges and ventricular surfaces of the anterior, posterior, and septal cusps.
Skeleton
Chordae tendinae
Chordae tendinae arise from ______ muscles, which are conical muscular projections with bases attached to the ventricular wall
Papillary
How do papillary muscles prevent right AV valve prolapse?
They begin to contract before RV contraction, tightening the chordae tendinae and drawing the cusps together, thus preventing prolapse
Describe the 3 papillary muscles associated with the right AV valve. Which one is the largest? What do their chordae tendinae attach to?
Anterior - largest, most prominent, found on anterior wall of RV. Chordae tendinae attach to anterior and posterior cusps of tricuspid valve.
Posterior - arises from inferior wall of RV. Chordae tendinae attach to posterior and septal cusps of tricuspid valve.
Septal - arises from interventricular septum. Chordae tendinae attach to anterior and septal cusps of tricuspid valve.
Describe the position/location of the pulmonary valve relative to body landmarks
Pulmonary valve is found at the apex of the conus arteriosus, at the level of the 3rd costal cartilage
The valveless pairs of right and left pulmonary veins will enter which chamber of the heart?
Left atrium
What structure, associated with the left atrium, forms the superior part of the left border of the heart and overlaps the root of the pulmonary trunk?
Left auricle
The interior of the left atrium is characterized by:
Large smooth walled muscle part and smaller muscular auricle with _____ muscle.
4 _____veins (2 superior and 2 inferior)
Slightly ______ wall than that of right atrium
___________ septum that slopes posteriorly and to the right
Pectinate
Pulmonary
Thicker
Interatrial
What chamber of the heart forms the apex, nearly entire left surface, and most of the diaphragmatic surface?
Left ventricle
Describe the wall thickness, trabeculae carnae, conical cavity, and papillary muscles relative to the right ventricle
Walls are 2-3x thicker and covered in trabeculae carnae that are finer and more numerous than RV
Longer conical cavity
Larger anterior and posterior papillary muscles
The left ventricle has a smooth-walled, nonmuscular, superoanterior outflow part called the _____ ______, which leads to the aortic orifice and valve
It also has a ______ valve that guards the left AV orifice
The _____ orifice lies in the right posterosuperior part of the LV.
Aortic vestibule
Mitral (bicuspid)
Aortic
What structure forms as the continuation of the right ventricle and divides into the right and left pulmonary arteries, conducting low-oxygen blood to the lungs for oxygenation?
Pulmonary trunk
Which of the great vessels opens into the superior part of the right atrium at the level of the right 3rd costal cartilage?
SVC
Which of the following is not considered a great vessel of the heart?
A. Pulmonary trunk B. Aorta C. Superior vena cava D. Inferior vena cava E. Left coronary artery
E. Left coronary artery
What demarcates the atria from the venticles?
Coronary sulcus (atrioventricular groove)