Flashcards in Mediastinum and heart Deck (57)
1.) What are the superior, inferior, and lateral boundaries of the mediastinum?
2.) What is the dividing line between the superior and inferior mediastinum?
1.) Superior: Superior thoracic aperture
Lateral: Pleural cavities *Mediastinum does NOT contain the lungs*
2.) The angle of Louis (angle of the sternum), T4-T5
What is the corresponding vertebral level of the angle of Louis (angle of the sternum)?
What are the divisions of the inferior mediastinum? What are the dividing landmarks?
Anterior: The area between the sternum and the pericardium.
Middle: The heart and pericardium.
Posterior: The area between the pericardium and the vertebral bodies.
1.) What are the boundaries of the superior mediastinum?
2.) What are the contents of the superior mediastinum (11)?
1.) Superior: Thoracic inlet (upper opening of the thorax)
Inferior: Transverse thoracic plane (line from the sternal angle of Louis to the junction of T4-T5).
Posterior: First FOUR thoracic vertebrae.
2.) Superior vena cava (SVC), brachiocephalic veins, arch of the aorta, thoracic duct, trachea, esophagus, vagus nerve, left recurrent laryngeal nerve, phrenic nerve, and the thymus.
1.) What are the boundaries of the anterior mediastinum?
2.) What are the contents of the anterior mediastinum?
1.) Anterior: Sternum
Anterior: Left transversus thoracis and the 4th, 5th, 6th, and 7th left costal cartilages.
2.) Thymus (lies anterior to the pericardium), loose areolar tissue, lymphatic vessels, 2-3 anterior mediastinal lymph nodes, small mediastinal branches of the INTERNAL MAMMARY ARTERY (mediastinal arteries).
1.) What are the boundaries of the posterior mediastinum?
2.) What are the contents of the posterior mediastinum (7)?
1.) Anterior: Pericardium
Posterior: T5 (lower border) to T12
Superior: Transverse thoracic plane
Inferior: Thoracic surface of the diaphragm
Lateral: Mediastinal pleura (on either side)
2.) Thoracic part of the descending aorta (aka thoracic/descending aorta = synonymous), azygos vein, hemiazygos vein, accessory hemiazygos vein, vagus nerve, splanchnic nerve (not the sympathetic chain?????), esophagus, thoracic duct, some lymph glands.
*Mnemonic: DATES --> Descending aorta, Azygos vein and hemiazygos and accessory hemiazygos vein, Thoracic duct, Esophagus, Splanchnics.
Name the PAIRED branches of the descending thoracic aorta in descending order (5)
Bronchial branches, mediastinal branches, esophageal branches, pericardial branches, superior phrenic (supplies the diaphragm) arteries.
On which sides of the body are the azygos and hemiazygos veins, respectively?
Azygos = right side
Hemiazygos = left side
What carries the lymphatics from the lower portion of the body. Describe its course and where it empties.
Thoracic duct. It is a posterior mediastinal and midline structure. It travels up the midline with the azygos vein, then veers LEFT and empties into the LEFT VENOUS ANGLE (p.170 Moore).
What muscle and cartilage marks the beginning of the esophagus? What structure does that muscle form?
Muscle: Cricopharyngeus muscle, it forms the superior/upper esophageal sphincter (UES)
Cartilage: Cricoid cartilage
1.) What do the splanchnic nerves supply?
2.) What are the three branches located in the posterior mediastinum and where are they?
1.) Sympathetic innervation to the abdominal organs.
2.) Greater splanchnic (T5-T9), lesser splanchnic (T10-T11), least splanchnic (T12)
What are the contents of the middle mediastinum (6)?
Heart, pericardium, phrenic nerves, roots of the great vessels (aorta, pulmonary arteries and veins, and vena cava), arch of the azygos vein, and main bronchi.
1.) What attaches the heart to the diaphragm?
2.) What attaches the heart to the posterior surface of the sternum?
1.) Pericardiacophrenic ligament, which arises from the fibrous pericardium.
2.) Sternopericardial ligaments
What are the two subdivisions of the serous pericardium? What is between them?
Parietal and visceral (epicardium) pericardium. They are separated by the PERICARDIAL CAVITY which contains pericardial fluid.
What is the location and purpose of endocardium?
It is the innermost serous lining of the heart. It covers the chambers of the heart and lines the four valves of the heart.
Are any of the pericardial layers sensitive to pain? If so, which?
Yes. The fibrous and parietal pericardium and sensitive to pain. The visceral pericardium can feel STRETCHING, but not pain.
What is the location of the transverse pericardial sinus?
Within the pericardial cavity, it lies between the superior vena cava (SVC) posteriorly, and the ascending aorta and pulmonary trunk anteriorly.
The oblique sinus, also within the pericardial cavity, lies between the pulmonary veins and the inferior vena cava (IVC).
What provides blood supply to the pericardium? From where do these vessels arise?
Pericardiacophrenic vessels (to pericardium and diaphragm) --> artery and vein.
The pericardiacophrenic artery arises from the internal thoracic artery, the vein arises from the brachiocephalic vein.
What supplies pain sensation to the pericardium?
The phrenic nerve
What major structure of the heart is not visible anteriorly in situ?
List which chambers of the heart form each surface:
1.) Right pulmonary surface
2.) Left pulmonary surface
3.) Sternocostal (anterior) surface
4.) Diaphragmatic (inferior) surface
1.) Right atrium
2.) Left ventricle
3.) Right ventricle
4.) Left ventricle and part of the right ventricle
How do you know that you are looking at the left atrium?
Four pulmonary veins are visible.
Name which chamber is associated with the following heart borders:
1.) Right border
2.) Inferior border
3.) Left border
4.) Superior border
1.) Right atrium
2.) Right ventricle
3.) Left ventricle
4.) R&L auricles and the three great vessels --> 1.) SVC (right most) 2.) Ascending aorta (middle) 3.) Pulmonary artery (left, carries deoxygenated blood).
In an infant prior to birth, how does venous blood bypass the lungs?
All venous blood that comes through the right atrium is shunted through the FORAMEN OVALE into the LEFT ATRIUM. By birth, the foramen ovale has closed and is then known as the FOSSA OVALIS (oval fossa).
Why is a small patent foramen ovale usually not a problem?
Because left heart pressure is much greater and it is okay if oxygenated blood mixes with deoxygenated blood, just not the other way around. If right heart blood moves to the left side through a patent foramen ovale, then DEOXYGENATED blood is being pumped throughout the entire body.
What are the prominent ridges of myocardium on the interior wall of the right atrium and both auricles called? Where do they originate? Describe!
Pectinate muscles. They originate at the Crista Terminales --> a vertical muscular ridge running anteriorly along the right atrial wall from the opening of the SVC to the opening of the IVC.
Name and describe the location of the two nodes in the right heart
1.) SA node (sinoatrial node): Pacemaker of the heart. Lies at the base of the SVC.
2.) AV (atrioventricular node): Lies near the right atrioventricular (tricuspid) valve.
Name the three cusps of the tricuspid valve
1.) Septal cusp: Lies close to the interventricular septum.
2.) Anterior cusp:
3.) Posterior cusp:
Name and describe the muscles associated with the cusps of the tricuspid valve
1.) Each cusp has 10-12 CHORDAE TENDINEAE
2.) Each cusp has a papillary muscle (anterior, posterior, and septal) which the chordae tendineae attach to. *The papillary muscles attach to the right ventricular wall*
What attaches the anterior papillary muscle to the interventricular septum?
Septomarginal trabecula (aka MODERATOR BAND)
What is the name for the anastomosing muscular ridges of myocardium in both of the ventricles?
Trabeculae carneae cordis
What is the name for the smooth area at the base of the pulmonary valve?
What is the name and type of valve controls blood flow from the right ventricle into the pulmonary trunk? What are its constituent parts?
Pulmonary valve (Semilunar). It has 3 cusps --> Right, anterior, and left cusps.
What structure is known as the base of the heart?
What are TWO distinguishing left atrial features?
1.) Four pulmonary veins entering
2.) Fossa ovales
What is the name/type of valve that separates the left ventricle from the aorta?
Aortic valve = a semilunar valve
1.) Where is the opening of the right coronary artery?
2.) Where is the opening of the left coronary artery?
1.) Right CUSP of the aortic valve
2.) Left CUSP of the aortic valve
What are the functional components of a cusp of a semilunar valve?
Nodules: Come together when the valve closes, nodules separate when the valve opens.
When the ventricles are contracting (systole), what is the status of the valves?
AV valves shut, semilunar valves open.
What structure circumscribes the heart, separating the right and left atria from the right and left ventricles.
Trace the branches off of the right coronary artery? What do they supply?
1.) The Sinuatrial (SA) nodal branch, supplies the SA node (in the right atrium).
2.) Atrial branches: supply the atria
3.) Marginal artery (at the right margin)
*It then turns around in the right coronary sulcus and travels posteriorly*
4.) Posterior interventricular artery (posterior descending): Lies in the sulcus created by the interventricular septum.
5.) ENDS by anastomosing with the CIRCUMFLEX ARTERY (which comes off of the left coronary)
Trace the branches off of the left coronary artery? What do they supply?
*Directly after it leaves the aorta and runs into the sulcus, it quickly divides into TWO LARGE BRANCHES -->
1.) Circumflex branch of the left coronary artery, gives off the
i.) Left (obtuse) marginal vein. The circumflex then turns posteriorly and gives off the ii.) Posterior left ventricular branch. ENDS by anastomosing with the RIGHT CORONARY ARTERY.
2.) Anterior interventricular artery (aka --> LAD = left anterior descending) running in the anterior interventricular sulcus*
What does the right coronary artery supply (6)?
1.) The right atrium
2.) MOST of the right ventricle
3.) Part of the left ventricle (the diaphragmatic surface)
4.) Part of the IV septum, usually the posterior 1/3
5.) SA node (60% of ppl)
6.) AV node (80% ppl)
What does the left coronary artery supply (4)?
1.) Left atrium
2.) Most of the left ventricle
3.) Part of the right ventricle
4.) Most of the IVS (usually its anterior 2/3), including the ***AV bundle of the conducting system of the heart***, through its perforating IV septal branches. THIS CAN CAUSE ARYTHMIAS!!!
5.) SA node (40% of ppl)
1.) What is "left-dominant" coronary circulation?
2.) Right dominant?
1.) When the posterior descending artery (PDA) is supplied by the circumflex artery.
2.) PDA is supplied by the right coronary artery (RCA)
3.) PDA is supplied by both the RCA and the circumflex artery
What is the most commonly diseased heart vessel (e.g. coronary artery disease)?
Left anterior descending (LAD) aka Anterior interventricular branch
1.) Where does MOST of the cardiac venous drainage empty? Where is it and in what view is it most easily seen?
2.) What are the exception vessels to the above? Where do they drain?
1.) The coronary sinus. It lies in the coronary sulcus. Most obvious in a posterior view.
2.) Anterior cardiac veins pierce the RIGHT ATRIAL WALL and drain into the right atrium.
Name the veins of the heart and what artery they travel with (4).
1.) Great cardiac vein: Travels with the LAD (left anterior descending artery) and drains into the coronary sinus.
2.) Small cardiac vein: Travels with the RIGHT MARGINAL ARTERY
3.) Middle cardiac vein: Travels with the posterior interventricular artery (posterior descending artery).
4.) Posterior vein of left ventricle: Travels with the posterior ventricular artery.
List the six most common locations for CAD, in descending order.
2.) Right coronary artery
4.) Left coronary (widow-maker, because it gives off circumflex and anterior descending)
5.) Posterior interventricular branch
6.) Right coronary
What main structure does the AV node lie near?
Trace the path of heart conduction
Right atrium: SA node (pacemaker) --> AV node --> [AV bundle in the interventricular septum (IVS)] --> divides into TWO (bundle of His) --> a.) right bundle travels through the SEPTOMARGINAL BAND (moderator band) b.) the left bundle runs divides into PURKINJE FIBERS which supply the left ventricle.
What are the vessels associated with the right atrium? Describe their location and function.
1.) Superior vena cava (SVC): Three ajoining vessels on the superior right atrium that bring in deoxygenated blood from the upper body.
2.) Inferior vena cava (IVC): Large vein on the inferior aspect of the right atrium that brings in deoxygenated blood from the lower trunk and limbs.
The beginning of the cardiac cycle is marked by the (systole or diastole?) and the simultaneous closing of what valve(s)?
Diastole: Begins upon closure of the AORTIC and PULMONARY valves.
What are the two heart sounds (lub, dub) created by?
The 1st heart sound (lub), is created by the MITRAL VALVE and TRICUSPID VALVE closing.
The 2nd heart sound (dub) is created by the PULMONARY VALVE and AORTIC VALVE closing.
1.) The apex of the heart is formed by the what?
2.) Describe its anatomical position in relation to the intercostal spaces
1.) Inferolateral part of the left ventricle.
2.) Lies POSTERIOR to the LEFT 5TH INTERCOSTAL SPACE.
Which direction does the apex of the heart face in situ?
Anteriorly and to the left