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Anatomy Exam 1 > Mediastinum & Heart II > Flashcards

Mediastinum & Heart II Flashcards

1
Q

Overview of the heart

  • Do atria or ventricles have thicker walls?
  • What chamber has the thickest wall?
  • What are the septum names?
  • What are the grooves on the heart’s surface?
A

Overview of the heart

Ventricles have thicker walls than atria because ventricles pump blood to lungs or body, while atria pump blood to adjacent chambers

Left ventricle has thick wall because it pumps blood to the rest of the body

Interatrial septum separates the atria

Interventricular septum separates ventricles

Coronary vessels sit in the grooves of the heart’s surface:

  • Coronary (atrioventricular) groove
  • Anterior interventricular groove
  • Posterior interventricular groove
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2
Q

Describe flow of blood through heart (including if it is oxygen rich or poor blood)

A

SVC, IVC, and coronary sinus give oxygen POOR blood to right atrium

Right atrium pumps blood though tricuspid (right atrioventricular) valve into right ventricle

Right ventricle pumps blood through pulmonary valve into pulmonary trunk

Pulmonary trunk branches off into pulmonary arteries and head to the lungs so blood can get oxygenated

Pulmonary veins give oxygen RICH blood to left atrium

Left atrium pumps blood through mitral (left atrioventricular) valve into left ventricle

Left ventricle pumps blood through aortic valve, which pushes oxygen rich blood to rest of body

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3
Q

Arterial supply of the heart: coronary arteries

  • Where do coronary arteries arise?
  • Map out the coronary arteries and their branches
A

Arterial supply of the heart: coronary arteries

Coronary arteries arise from the ascending aorta

Right coronary artery (RCA)

  • Travels in coronary groove
  • Gives quickly off to sinoatrial (SA) nodal branch
  • Gives off to right marginal branch at inferior border of heart
  • Gives off to posterior interventricular branch, which occupies posterior interventricular groove

Left coronary arter (LCA)

  • Gives off quickly to circumflex branch, which occupies coronary groove
  • Circumflex branch gives rise to left marginal branch
  • Gives off to left anterior descending (LAD) aka anterior interventricular branch, which occupies the anterior interventricular groove and runs towards apex of heart
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4
Q

What is an MI?

A

Myocardial infarction

When an area of the heart muscle has undergone necrosis, is usually caused by ischemia (lack of adequate blood supply) due to occlusion of coronary arteries

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5
Q

What is coronary bypass surgery?

A

Coronary bypass surgery is a technique used to shunt blood around narrowed or blocked coronary arteries

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6
Q

Venous drainage of the heart

  • What drains blood from the heart?
  • Where is it located?
  • Where does it drain to?
  • What are the branches?
A

Venous drainage of the heart

Coronary sinus

Located in posterior portion of coronary groove

Drains into right atrium

Collects blood from:

  • Great cardiac vein
  • Middle cardiac vein
  • Small cardiac vein
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7
Q

Right atrium

  • What are all of the openings?
  • What are the structures of right atrium?
A

Right atrium

Openings: SVC, IVC, coronary sinus

Right auricle is an appendage of the right atrium with pectinate muscles

Crista terminalis is a ridge separating the auricle and the smooth posterior wall

Fossa ovalis is an oval shaped depression in the interatrial septum that is the remnant of the embryonic foramen ovale

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8
Q

Tricuspid valve (right atrioventricular valve)

  • How many cusps?
  • When does it open?
A

Tricuspid valve (right atrioventricular valve)

3 cusps

Opens passively during atrial contraction

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9
Q

Right ventricle

  • What are the structures in right ventricle?
  • How is backflow prevented?
A

Right ventricle

Wall has trabecular carneae muscle

3 papillary muscles come off wall - anterior, posterior, and septal

Chordae tendineae connect papillary muscles to cusps of tricuspid valve

Septomarginal trabecula (moderator band) - muscle bundle extending from interventricular septum to anterior papillary muscle, and carries portion of right bundle branch

Back flow of blood into the right atrium during ventricular contraction is prevented by the papillary muscle / chordae tendineae function to hold the tricuspid valve closed

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10
Q

Pulmonary valve

  • How many cusps and sinuses?
  • Explain how valve works
A

Pulmonary valve

3 cup-like cusps and 3 sinuses

When ventricles contract, valve opens and blood passes through to pulmonary trunk

When ventricles relax, the blood falls down trunk and fills the sinuses above the cup-like cusps, and the filled sinuses hold the valve closed

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11
Q

Left atrium

  • What opens into left atrium?
  • What are the structures of left atrium?
A

Pulmonary veins open up into left atrium

Left auricle has pectinate muscles

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12
Q

Mitral valve (left atrioventricular valve)

  • How many cusps?
  • When does it open?
A

Mitral valve (left atrioventricular valve)

2 cusps

Opens passively during atrial contraction

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13
Q

Left ventricle

  • Thick or thin walls?
  • What are the structures of left ventricle?
  • How is backflow prevented?
A

Left ventricle

Walls are twice as thick as right ventricle

Wall has trabecular carneae muscle

2 papillary muscles come off wall - anterior and posterior

Chordae tendineae connect papillary muscles to cusps of mitral valve

Backflow of blood into the left atrium during ventricular contraction is prevented by the papillary muscle / chordae tendineae function to hold the mitral valve closed

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14
Q

Aortic valve

  • How many cusps and sinuses?
  • Explain how valve works
  • Where does blood in sinuses go?
A

Aortic valve

3 cup-like cusps and 3 sinuses

When ventricles contract, valve opens and blood passes through to ascending aorta

When ventricles relax, the blood falls down aorta and fills the sinuses above the cup-like cusps, and the filled sinuses hold the valve closed

Blood in the aortic sinuses flow into coronary arteries

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15
Q

Explain fetal circulation

  • Include the two bypasses
  • Include when blood is oxygen rich, poor, or mixed
A

Oxygen rich blood enters fetus via umbilical vein

As O2 rich blood reaches liver, it is shunted past organ via ductus venosus (blood is already filtered by mother)

Ductus venosus leads directly to IVC, which carries the O2 rich (but now mixed with O2 poor blood from the structures inferior to the diaphragm) to the right atrium

Since there is no need to oxygenate the blood in the lungs (not functioning at this time anyways), there are two bypasses in fetal heart

  • Blood from right atrium passes through the foramen ovale into the left atrium, then goes to left ventricle, aorta, and body
  • Blood that does not enter the right ventricle and pulmonary trunk (which is typically O2 poor blood from the SVC, which does not tend to mix with the O2 rich blood from the IVC) bypasses the pulmonary arteries by flowing through the ductus ateriosus, a shunt to the arch of the aorta, then to the body
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16
Q

What are the 3 bypasses in fetal circulation?

A

Ductus venosus (liver)

Foramen ovale (heart going from right to left atrium)

Ductus arteriosis (heart going from pulmonary trunk to aorta)

17
Q

Explain lack of blood flow through pulmonary circulation for fetuses

A

In the fetus, very little blood flows through the pulmonary circulation (to and from the lungs) due to the high vascular resistance in the collapsed fetal lungs

Instead, blood follows the path of least resistance (e.g. through the foramen ovale or ductus arteriosus)

At birth, with the first intake of air, the flow of blood takes on the adult pattern as the vascular resistance in the lungs is drastically reduced

18
Q

Summary of fetal circulation

A

Umbilical vein (oxygen rich blood)
Ductus venous
IVC

Right atrium

  • Foramen ovale
  • Left atrium
  • Left ventricle
  • Aorta
  • Body

SVC (oxygen poor blood returned from the body)

  • Right atrium
  • Right ventricle
  • Pulmonary trunk
  • Ductus arteriosus
  • Aortic arch
  • Body

Body to umbilical arteries (oxygen poor blood)

19
Q

What are the adult remnants of the fetal bypasses in the heart? (There are others located in the abdomen)

A

Ligamentum arteriosum - fetal ductus arteriosus (closed by 3 weeks after birth)

Fossa ovalis - fetal foramen ovale (closed by 3 months after birth)

20
Q

Parts of the heart conduction system

A

Sinoatrial (SA) node
Atrioventricular (AV) node
Atrioventricular (AV) bundle / Bundle of His

21
Q

Sinoatrial (SA) node

  • Location?
  • What does it do?
  • Stimulated by? Inhibited by?
A

Sinoatrial (SA) node

Located at the junction of the SVC and right atrium

Pacemaker of the heart, initiates electrical impulse for atrial contraction

Stimulated by sympathetic innervation - increases HR

Inhibited by parasympathetic innervation via vagus nerve - decreases HR

22
Q

Atrioventricular (AV) node

  • Location?
  • What does it do?
A

Atrioventricular (AV) node

Located at the interatrial septum

Receives signal of the SA node via atrial walls

Sends signal to ventricles via the AV bundle

23
Q

Atrioventricular (AV) bundle / Bundle of His

  • Location?
  • What does each bundle stimulate?
A

Atrioventricular (AV) bundle / Bundle of His

Located at the interventricular septum

Divides into right and left bundles

Right bundle stimulates the interventricular septum, walls, and papillary muscles of the right ventricle via moderator band

Left bundle stimulates the interventricular septum, walls, and papillary muscles of the left ventricle

24
Q

Esophagus

  • Location?
  • Where does it pass through diaphragm?
A

Esophagus

Fibromuscular tissue flattened between the pharynx and stomach

Posterior to trachea and superior to mediastinum

Right side of thoracic aorta

Posterior to base of heart

Passes through esophageal hiatus at T10

25
Q

Thoracic (descending) aorta

  • Left or right of midline?
  • Where does it pass through diaphragm?
  • Anterior midline branches?
  • Paired branches?
A

Thoracic (descending) aorta

Lies to left of midline

Passes through aortic hiatus at T12

Anterior midline branches - bronchial arteries and esophageal arteries

Paired branches - posterior intercostal arteries (part of VAN)

26
Q

Azygos system

  • Do this system have valves?
  • Describe location of three parts of azygos system
  • Where does he azygos vein collect blood from and drain to?
A

Azygos system - no valves

Azygos vein

  • Lies to right of midline
  • Collects blood from the mediastinal structures (via bronchial and esophageal veins), thoracic wall (via intercostal and subcostal veins), and posterior abdominal wall (via lumbar veins)
  • Drains primarily into the SVC

Accessory hemiazygos vein

  • Lies to left of midline
  • Courses down posterior to esophagus to join azygos vein at T9 level

Hemiazygos vein

  • Lies to left of midline, inferior to accessory hemiazygos vein
  • Courses up posterior to esophagus to join the azygos vein at T9 level
27
Q

Thoracic duct

  • Function?
  • Location?
  • Where does it drain?
A

Thoracic duct

Collects lymph from most of body

Courses posterior to the esophagus on the anterior surface of the vertebral bodies, between the azygos vein and the aorta

Drains into the left venous angle (where the subclavian and left internal jugular veins join)

28
Q

Right lymphatic duct

  • Function?
  • Where does it drain?
A

Right lymphatic duct

Collects lymph from the right upper quadrant (right side of the head / neck / thorax and right upper extremity)

Drains into right venous angle (where subclavian and right internal jugular veins join)

29
Q

Sympathetic trunks

  • Function?
  • Location?
  • How does it connect to the ventral rami?
  • What kind of innervation and how does it provide innervation to the abdominal organs?
A

Sympathetic trunks - right and left

Connects series of paravertebral ganglia

Extends from the cervical to sacral region

Connected to ventral rami (e.g. intercostal nerves, which are the ventral rami of thoracic spinal nerves) via the white (entrance) and gray (exit) commincans

Provides sympathetic innervation to the abdominal organs via the thoracic splanchnic nerves

30
Q

Thoracic splanchnic nerves

  • What are the three parts?
  • Where do they emerge?
  • What kind of fibers do they carry?
A

Thoracic splanchnic nerves

The greater, lesser, and least splanchnic nerves emerge from the sympathetic trunks in the posterior mediastinum

They carry preganglionic fibers that will synapse in the prevertebral ganglia in the abdomen to supply the abdominal viscera

Anatomy Exam 1 (8 decks)

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