Mediastinum: Heart and Lungs Learning Objectives

Identify the external features of the right lung

3 lobes (superior, middle, inferior)

2 fissures (oblique (superior and inferior), horizontal (inferior and middle)

Identify the external features of the left lung

2 lobes (superior, inferior)

1 fissure (oblique)

Lingula

Explain the pattern of branching and the structural anatomy of the bronchial tree

Trachea splits at the carina into:

Right and Left Primary (main) Bronchi, which split into:

Secondary (lobar) bronchi (2 for left lung, 3 for right lung), which split into:

Segmental (tertiary) bronchi (10 for each lung)

Identify the right and left lungs using only the related structures of their medial surface

RA LS

In right lung: Pulmonary arteries are Anterior to the primary bronchus

In left lung: Pulmonary arteries are Superior to the primary bronchus

Name the structures that comprose the root of the lung

Hilum of lung contains: Pulmonary arteries, Pulmonary veins, Primary Bronchus, and Pulmonary ligament surrounds the hilum

What are the different pleural coverings?

Visceral pleura - covers the lungs itself

Parietal pleura - Outer layer of covering along inside of thoracic cavity

What are the regions of the parietal pleura

Costal part - along the ribs

Diaphragmatic part - Inferior portion

Cervical part - Superior portion

Mediastinal part - Medial portion

What are the recesses of the parietal pleura?

Costomediastinal recess

Costodiaphragmatic recess

List the layers of pericardium from superficial to deep

Fibrous Pericardium, Parietal Layer of Serous Pericardium, Visceral Layer of Serous Pericardium (epicardium)

Identify the surface features of the heart

Ligamentum Arteriosum (connects pulmonary trunk to aortic arch; remnant of ductus arteriosus)

Right and Left Auricles (Ear)

Right and Left Coronary Sulcus (Atrioventricular)

Anterior and Posterior Interventricular Sulcus

Apex of Heart

Name the internal features of the Right Atrium

Crista Terminalis (Ridge where pectinate muscles meets smooth interatrial septum)

Openings for the: Atrioventricular Valve, Coronary Sinus, Superior/Inferior Vena Cava

Interatrial Septum (Fossa ovalis - remnant of fetal foramen ovale)

Pectinate Muscles

Name the internal features of the Right Ventricle

Opening for Right Atrioventricular (Tricuspid) Valve

3 cusps, 3 chordae tendineae, 3 papillary muscles (Anterior, Posterior, Septal)

Opening for Pulmonary (Semilunar) Valve

Conus Arteriosus - carries deoxygenated blood to pulmonary trunk

Wall: Trabeculae Carneae, and Septomarginal Trabecula

Name the internal features of the Left Atrium

Valve of Foramen Ovale (closes at birth)

Openings for: Atrioventricular Valve (Bicuspid/Mitral), Pulmonary Veins (4)

Pectinate Muscles

Interatrial Septum

Name the Internal Features of the Left Ventricle

Opening for Aortic Valve (3 cusps)

Opening for left atrioventricular valve (bicuspid/mitral), 2 cusps, chordae tendineae, 2 papillary muscles

Where do you auscultate the aortic valve

2nd Right intercostal space

Where do you auscultate the pulmonary valve

2nd Left intercostal space

Where do you auscultate the tricuspid valve?

5th Left intercostal spaceW

Where do you auscultate the Bicuspid/mitral valve?

5th Left Intercostal space (more laterally)

Describe the blood flow through the heart

Blood enters the heart at the right atrium from SVC/IVC, travels to right ventricle (Tricuspid Valve), blood exits heart through pulmonary valve to pulmonary trunk → Lungs

Blood from lungs enters the heart at the left atrium through pulmonary veins, travels to left ventricle (Bicuspid/Mitral valve), blood exits heart through Aortic Valve → Body

Describe the location of the remnants of fetal circulation (Fossa Ovalis)

The fossa ovalis is a remnant of the foramen ovale that connected the right and left atrium

Describe the location of the remnants of fetal circulation (Ligamentum arteriosum)

Ligamentum Arteriosum found on the external surface of heart; remnant of the ductus arteriosus which connected the pulmonary trunk and aortic arch)

Explain the conduction system of the heart

Electrical signal starts at the Sinoatrial (SA) Node in Right Atrium

Atrioventricular Node - adjacent to right atrioventricular valve

Signal travels down Atrioventricular Bundle and splits in the interventricular septum into left and right bundle branches

Moderator Band (Septomarginal trabeculae) provides conduction to lateral wall of right ventricle to assist with proper timing

Explain the anatomy of cardiac referred pain

Pain receptors found in the myocardium have visceral afferent axons that bring pain signals back to cell bodies in the Dorsal Root Ganglion

Cell bodies in the DRG are shared with general somatic axons from the body;

The brain interprets pain signals from the heart as if they are coming from the skin of the left pectoral region, left shoulder, and left medial upper extremity

What veins make up the coronary sinus?

Great cardiac vein and Oblique vein of left atrium

What would you find with the great cardiac vein?

Anterior interventricular Artery

What would you find with the middle cardiac vein?

Posterior Interventricular Artery

What would you find with the small cardiac vein?

Right Marginal Artery

What does the Left Coronary Artery bifurcate into?

Circumflex branch and Anterior Interventricular Artery