Heart & Mediastinum Dissection Objectives

Questions and Answers

What is the role of the SA node in the heart's conduction system?

It initiates an electrical impulse that causes atrial contraction. (correct)

It connects the atria and ventricles directly.

It mediates the flow of deoxygenated blood through the ventricles.

It prevents regurgitation during ventricular contraction.

During which phase does blood flow from the right atrium to the right ventricle?

During ventricular relaxation through the aortic valve.

During atrial contraction through the tricuspid valve. (correct)

During ventricular contraction through the tricuspid valve.

During atrial contraction through the pulmonary valve.

What is the role of the transverse sinus in the pericardial anatomy?

It lies posterior to the aortic arch and pulmonary trunk. (correct)

It is located anterior to the superior vena cava.

It is formed by the reflection of the visceral layer of serous pericardium.

It connects the pulmonary arteries and veins.

Where is the aortic valve located for auscultation?

2nd right intercostal space right of the sternal border. Signup and view all the answers

Which layers make up the pericardial sac?

Fibrous pericardium and parietal serous pericardium. Signup and view all the answers

What prevents the backflow of blood in the ventricles?

Papillary muscles. Signup and view all the answers

In which part of the heart does blood become oxygenated?

In the lungs. Signup and view all the answers

Where does the thoracic duct originate?

From the cisterna chyli in the abdomen. Signup and view all the answers

What structure conducts impulses from the AV node to the ventricles?

AV bundle of His. Signup and view all the answers

What regions does the thoracic duct primarily drain?

The lower limbs, pelvic cavity, and left side of the thorax. Signup and view all the answers

Which valve prevents blood from flowing back into the right atrium?

Tricuspid valve. Signup and view all the answers

Which structure is anterior to the thoracic duct?

Esophagus. Signup and view all the answers

How do the ascending lumbar veins contribute to the azygos system?

They transport blood from the inferior vena cava to the azygos vein. Signup and view all the answers

The cordae tendineae serve what primary function in the heart?

To prevent valve regurgitation. Signup and view all the answers

Which lymphatic trunks drain into the thoracic duct?

Lumbar and jugular lymphatic trunks. Signup and view all the answers

What does the right lymphatic duct drain?

The right side of the head and neck and right upper limb. Signup and view all the answers

Which structure in the fetal heart allows blood to flow directly from the right atrium to the left atrium?

Foramen ovale Signup and view all the answers

What is the primary purpose of the ductus arteriosus during fetal life?

To bypass the lungs and send blood to the aorta Signup and view all the answers

Which coronary artery supplies the anterior interventricular septum?

Left anterior descending artery Signup and view all the answers

Which vein parallels the left anterior descending artery and drains the same cardiac territory?

Great cardiac vein Signup and view all the answers

In the adult heart, which of the following chambers has a thicker muscular wall due to higher arterial pressure?

Left ventricle Signup and view all the answers

What is the primary function of the auricles in the adult heart?

To increase blood volume capacity Signup and view all the answers

Which of the following structures drains into the coronary sinus?

Great cardiac vein Signup and view all the answers

What anatomical structure prevents backflow in the heart during contraction?

Heart valves Signup and view all the answers

The phrenic nerve primarily innervates which muscle?

Diaphragm Signup and view all the answers

Which structure in the mediastinum contains the heart?

Middle mediastinum Signup and view all the answers

Which of the following nerves branches off the vagus nerve and innervates the larynx?

Recurrent laryngeal nerve Signup and view all the answers

What structure serves as the main route for venous blood return to the heart from the coronary circulation?

Coronary sinus Signup and view all the answers

Which nerve travels lateral to the common carotid arteries in the thorax?

Phrenic nerve Signup and view all the answers

Study Notes

Blood Flow through the Heart

Blood moves from the superior vena cava (SVC), inferior vena cava (IVC), and coronary sinus to the right atrium.
Right atrium flows through the tricuspid valve into the right ventricle.
Blood exits through the pulmonary valve into the pulmonary artery (carries deoxygenated blood).
Lungs oxygenate blood, returning it to the left atrium via pulmonary veins.
From left atrium, blood flows through the mitral (bicuspid) valve to the left ventricle.
Left ventricle pumps blood through the aortic semilunar valve into the aortic arch (branches include brachiocephalic trunk, left common carotid artery, left subclavian artery).

Conduction System of the Heart

SA node, located anterolateral to the junction of SVC and right atrium, is the pacemaker.
Impulse spreads to the AV node (medially to coronary sinus opening) and then to the bundle of His.
His bundle divides into left and right pathways, supplying Purkinje fibers to ventricles and papillary muscles.

Chest Wall Projections of Heart Valves

Aortic valve: 2nd right intercostal space, right sternal border.
Pulmonary valve: 2nd left intercostal space, left sternal border.
Tricuspid valve: 4th left intercostal space, left sternal border.
Mitral valve: 5th intercostal space, left mid-clavicular line.

Structure of the Heart

Pectinate muscles in the atrium assist in contraction.
Chordae tendineae connect the papillary muscles to the valve cusps in the ventricles.
Trabeculae carneae are muscular ridges in ventricular walls, preventing valve regurgitation.

Lateral Flow in the Left Side of the Heart

Left ventricle has a thicker wall due to higher systemic arterial pressure than pulmonary pressure.
Foramen ovale (becomes fossa ovalis post-birth) connects right and left atria allowing blood flow bypassing the right ventricle.
Ductus arteriosus connects pulmonary artery to aorta in fetuses, allowing blood to avoid lungs.

Coronary Circulation

Right coronary artery (RCA) supplies the right atrium, right ventricle, part of left ventricle, SA and AV nodes.
RCA has branches: right marginal artery, posterior descending artery, and septal branches.
Left coronary artery (LCA) branches into the left anterior descending artery and left circumflex artery.
Cardiac veins drain into the coronary sinus from great, middle, and small cardiac veins.

Mediastinum Divisions

Superior Mediastinum: bounds defined by the 1st rib and transverse thoracic plane (T4-T5).
Main vessels: brachiocephalic veins, pulmonary trunk, thoracic duct, trachea, and esophagus.
Inferior Mediastinum is divided into anterior, middle, and posterior regions:
- Anterior: internal thoracic vessels, fat, lymph nodes.
- Middle: pericardial sac and major vessels.
- Posterior: descending aorta and azygos vein system.

Nervous System Relationships

Phrenic nerve runs lateral to vagus nerve, innervating diaphragm.
Vagus nerve has branches forming a plexus influencing thoracic viscera.
Recurrent laryngeal nerves influence voice function.
Sympathetic trunk connects with splanchnic nerves, affecting abdominal organ innervation.

Pericardium Anatomy

Pericardium: double-walled fibro-serous membrane surrounding the heart.
Pericardial cavity lies between parietal and visceral layers.
Sinuses include the transverse sinus behind the aorta and the oblique sinus from pulmonary veins.

Thoracic Duct and Azygos System

Thoracic duct drains lymph from most body regions and ascends through the diaphragm, entering at the left venous angle.
Azygos system drains back and thoraco-abdominal walls, connecting IVC and SVC via ascending lumbar veins.
Right lymphatic duct collects lymph from the right head, neck, upper limb, and part of the thorax.

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Description

This quiz focuses on the objectives of the laboratory dissection related to the heart and mediastinum. Students will demonstrate an understanding of blood flow through the heart's right side and identify anatomical structures and the impulse conducting system. Prepare for both written and practical examinations.