Mediastinum and Heart Learning Objectives

Question 1

Identify the external features of the right and left lungs.

Answer 1

Right:

• Apex
• Lobes (superior, middle, inferior)
• Fissures (oblique, horizontal)

Left:

• Apex
• Lobes (superior, inferior)
• Oblique fissure
• Lingula (L. tongue)
• Cardiac notch

Question 2

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

Answer 2

Trachea

• Rings
• Carina (at point of bifurcation, “ridge on underside of boat”, best visualized from inside the trachea)

Bronchi

• Primary (R & L main)
  - R primary more vertical, larger
• Secondary (lobar):
  - Left (superior and inferior); R (superior, middle, inferior)
• Tertiary (segmental):
  - 10 each lung

Right primary bronchus is more vertical

Question 3

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

Answer 3

Right lung, medial surface:
Superior vena cava
Esophagus
Azygos vein
Heart
Hilum

Left lung, medial surface:
Aortic arch
Thoracic aorta
Esophagus
Heart
Lingula
Hilum

Question 4

Name the structures that comprise the root of the lung and explain how they vary between right and left lungs.

Answer 4

Hilum
Pulmonary a.*
Pulmonary v.
Primary bronchus
Pulmonary ligament (allows for expansion of hilum while securing structures)

Right: pulmonary artery anterior to primary bronchus
Left: pulmonary artery superior to primary bronchus

Question 5

Describe the pleural coverings of the lungs including the regions and recesses.

Answer 5

Parietal pleura (outermost layer, parietal = “wall”)

• Cervical part
• Costalvertebral/costal part
• Diaphragmatic part
• Mediastinal part

Parietal pleura recesses:

• costodiaphragmatic
• costomediastinal

Visceral pleura (innermost layer directly surrounding lungs, visceral = “organ”)

Question 6

List the layers of the pericardium from superficial to deep.

Answer 6

Fibrous pericardium

Serous pericardium

• Parietal pericardium
• —> Pericardial cavity (b/t parietal and visceral, contains serous pericardial fluid)
• Visceral pericardium (epicardium)

Heart

• Visceral pericardium (epicardium)
• Myocardium
• Endocardium

Question 7

Identify the surface features of the heart.

Answer 7

Right auricle
Right atrium
Coronary sulcus
Right ventricle
Ligamentum arteriosum
Left auricle
Pericardium
Anterior interventricular sulcus
Left ventricle
Cardiac apex
Left atrium
Coronary sinus (runs at the inferior surface of heart, base of the left atrium)

Question 8

Name the internal features of each chamber of the heart: right atrium.

Answer 8

Right atrium:
Superior vena cava
Interatrial septum
Fossa ovalis
Valved orifice of inferior vena cava
Valved orifice of coronary sinus
Right auricle
Crista terminalis
Pectinate muscles
Right atrioventricular orifice with atrioventricular valve

Question 9

Name the internal features of each chamber of the heart: right ventricle.

Answer 9

Right ventricle:
Conus arteriosus
Right atrioventricular valve (3 cusps)
Chordae tendineae
Papillary muscles (3)
- anterior
- posterior
- septal
Septomarginal trabecula
Pulmonary trunk
Valve of pulmonary trunk (cusp)
Interventricular septum
Trabeculae carneae

Question 10

Name the internal features of each chamber of the heart: left atrium and left ventricle.

Answer 10

Left atrium:
Valve of foramen ovale
Atrioventricular valve
Pulmonary veins (4)

Left ventricle:
Aortic valve (cusps)
Left atrioventricular valve (bicuspid)
- two cusps
- chordae tendineae
- papillary muscles (ant/post)
Interventricular septum
Trabeculae carneae

Question 11

Explain the arrangement between chordae tendineae and the valves of the heart.

Answer 11

Attach to the papillary muscles. Prevents valves from prolapsing.

Question 12

Identify cardiac auscultation sites.

Answer 12

Blood carries sound in direction of its flow

Sites are located superficial to the vector blood follows as it passes through each chamber/vessel.

Aortic and pulmonary (?): 2nd intercostal space
R AV (tricuspid) and L AV (mitral): 5th intercostal space

Question 13

Describe the blood flow through the heart including all chambers and valves.

Answer 13

1. Blood enters right atrium via superior/inferior vena cava.
2. Blood passes through right atrioventricular (tricuspid) valve to right ventricle.
3. Right ventricle send blood through the pulmonary valve, through the pulmonary trunk, to the lungs via the left and right pulmonary arteries.
4. Oxygenated blood travels back to the heart via the pulmonary veins and into the left atrium.
5. Left atrium sends blood through the left atrioventricular (mitral/bicuspid) valve to the left ventricle.
6. Left ventricle sends blood through the aortic valve to the aorta, ascending aorta, aortic arch, thoracic aorta, and to the rest of the body.

Question 14

Describe the pattern of arterial supply of the heart.

Answer 14

SEE DIAGRAM.

Question 15

Explain the conduction system of the heart.

Answer 15

1. SA node, “pacemaker,” initiates muscle contraction and determines heart rate.
2. Contraction spreads through the atrial wall until it reaches the AV node.
3. AV node –> AV bundle –> left and right bundle branches which travel alongside the interventricular septum.
4. Right bundle branch passes the septomarginal trabecula, anterior papillary muscle, to right ventricle wall via subendocardial fibers.
5. Left bundle branch enters anterior/posterior papillary muscles and left ventricle wall via subendocardial fibers.

Question 16

Explain the anatomy underlying [cardiac] referred pain.

Answer 16

Pain receptors in the myocardium,
Visceral afferent axons (symp),
Cell bodies in DRG,
Shared with general somatic axons,
Brain interprets pain from skin,
L pectoral, shoulder, medial UE

Question 17

Describe the location of the remnants of fetal circulation (fossa ovalis & ligamentum arteriosum) and what structures they shunted blood between.

Answer 17

Heart

Ductus arteriosus →
Ligamentum arteriosum
(pulmonary trunk to arch of aorta)

Foramen ovale → Fossa ovalis
(right to left atrium)