Sinuatrial Node Anatomy

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Questions and Answers

Which system does the sympathetic nerves belong to?

Somatic nervous system

Autonomic nervous system (correct)

Peripheral nervous system

Central nervous system

What is the first branch of the aorta?

Left subclavian artery

Subclavian artery

Brachiocephalic artery (correct)

Left common carotid artery

Where can the auscultation location of the aorta be found?

Over the medial end of the first right intercostal space

Over the lower half of the left side of the sternum

Over the medial end of the second right intercostal space (correct)

Over the medial end of the second left intercostal space

Which of the following vessels does NOT branch directly from the aorta?

Pulmonary artery Signup and view all the answers

What does the brachial plexus primarily innervate?

Upper limb muscles Signup and view all the answers

Which group of nerves includes both sympathetic and parasympathetic components?

Vagus nerve Signup and view all the answers

Which artery predominantly supplies the left ventricle?

Anterior interventricular artery Signup and view all the answers

What percentage of people have the SA node supplied by the left coronary artery?

40% Signup and view all the answers

In a heart with right dominance, where is the posterior interventricular artery primarily located?

A large branch of the right coronary artery Signup and view all the answers

Which of the following statements is true about the left coronary artery?

It supplies the majority of the heart. Signup and view all the answers

Which heart structure has no blood supply from the left coronary artery in most individuals?

Right ventricle Signup and view all the answers

What is typically supplied by the branches of the left coronary artery?

Anterior two-thirds of the interventricular septum Signup and view all the answers

What does coronary artery dominance often indicate about blood supply variations?

Usually involves variations affecting both ventricles Signup and view all the answers

What branch of the left coronary artery runs to the left between the pulmonary trunk and left auricle?

Circumflex branch Signup and view all the answers

What is true regarding variations in coronary arteries?

They commonly affect the diaphragmatic surface of both ventricles. Signup and view all the answers

Which artery primarily supplies the posterior one-third of the interventricular septum?

Right coronary artery Signup and view all the answers

What is the primary area supplied by the left coronary artery?

Left atrium and left ventricle Signup and view all the answers

From which aortic sinus does the right coronary artery arise?

Anterior aortic sinus Signup and view all the answers

In the case of codominance of coronary arteries, which arteries may contribute to the posterior interventricular artery?

Both right coronary and circumflex arteries Signup and view all the answers

What is the approximate percentage of individuals that exhibit codominance in coronary artery distribution?

18% Signup and view all the answers

Where does the left coronary artery pass in relation to the pulmonary trunk?

In front of the pulmonary trunk Signup and view all the answers

Which structure does the right coronary artery primarily run between?

Pulmonary trunk and right auricle Signup and view all the answers

What part of the heart does the left coronary artery NOT supply?

Right ventricle Signup and view all the answers

Which artery originates from the left posterior aortic sinus?

Left coronary artery Signup and view all the answers

What is one potential function of the posterior interventricular artery?

Feeds into multiple branches substituting for that vessel Signup and view all the answers

Which artery is principally described as supporting the major part of the heart?

Left coronary artery Signup and view all the answers

What is the primary function of the sinoatrial (SA) node?

To initiate electrical impulses that regulate heart rhythm Signup and view all the answers

Where is the sinoatrial node located in the heart?

At the junction of crista terminalis and superior vena cava Signup and view all the answers

What is the conduction velocity of impulses generated by the sinoatrial node?

Approximately 1 m/s Signup and view all the answers

How does autonomic input affect the sinoatrial node?

It modulates the heart rate to maintain balance. Signup and view all the answers

What structure does the middle internodal pathway connect to?

The atrial septum and then to the AV node Signup and view all the answers

Which pathway leaves the posterior part of the sinoatrial node?

Posterior internodal pathway Signup and view all the answers

What is the normal heart rate influenced by the sinoatrial node?

70-90 bpm Signup and view all the answers

From which embryonic structure is the sinoatrial node derived?

Embryonic sinus venosus Signup and view all the answers

Which of the following statements about the sinoatrial node is incorrect?

It is located within the left atrium. Signup and view all the answers

Which thoracic vertebra is mentioned as turning to the right?

Eighth thoracic vertebra Signup and view all the answers

What type of nodes drain the lymph vessels of the skin of the anterior thoracic wall?

Anterior axillary nodes Signup and view all the answers

Where do the internal thoracic nodes drain their lymph?

Into the thoracic duct Signup and view all the answers

Which lymph nodes are responsible for draining the lymph vessels of the skin of the posterior thoracic wall?

Posterior axillary nodes Signup and view all the answers

What does the bronchomediastinal trunk drain into?

Superior vena cava Signup and view all the answers

Which structure does the azygos vein receive tributaries from?

Lower left intercostal veins Signup and view all the answers

What is the primary function of the posterior intercostal nodes?

Draining into the thoracic trunk Signup and view all the answers

Which type of lymph nodes are involved in draining the deep lymph vessels of the anterior intercostal space?

Internal thoracic nodes Signup and view all the answers

Which system do the lymph vessels from the thoracic wall predominantly drain into?

Lymphatic system Signup and view all the answers

To which main structure does lymph from thoracic wall nodes eventually lead?

Thoracic duct Signup and view all the answers

Study Notes

Sinuatrial Node

Located in the right atrium at the junction of crista terminalis and superior vena cava.
Acts as the heart's "Pacemaker", originating spontaneous rhythmic electrical impulses.
Sends impulses to the AV node via the atrial septum, influencing heart rate.
Has a conduction velocity of approximately 1 m/s, maintaining a heart rate of 70-90 bpm.
Autonomic input modulates the function of the SA node to balance heart rate.
Derived from the embryonic sinus venosus.

Coronary Arteries

The left coronary artery mainly supplies blood to the left atrium and most of the left ventricle.
Atrial branches of the left coronary supply the left atrium, while ventricular branches supply the left ventricle.
The right coronary artery supplies a small part of the right ventricle and the posterior one third of the ventricular septum.
The SA node receives blood supply from the left coronary artery in about 40% of individuals.
Blood supply variations are common and often affect the diaphragmatic surface of the ventricles.

Coronary Artery Dominance

Right dominance occurs in about 67% of individuals; the posterior interventricular artery originates from the right coronary artery.
Left dominance, where the posterior interventricular artery arises from the left coronary artery, is less common.
Codominance (~18%) involves both right coronary and circumflex arteries contributing to the posterior interventricular artery.

Thoracic Wall and Lymphatic Drainage

Thoracic wall nodes drain into the bronchomediastinal trunk and posterior intercostal node drains into the thoracic trunk.
Anterior axillary nodes drain lymph from the anterior thoracic wall, while posterior axillary nodes drain the posterior thoracic wall.
Internal thoracic nodes are responsible for draining deep lymph vessels from the anterior intercostal spaces, leading to the thoracic duct.

Nervous Supply

The sympathetic and parasympathetic nerves, including the brachial plexus, contribute to cardiac nerve supply.
The first branch of the aorta is the brachiocephalic artery, followed by the left common carotid artery and left subclavian artery.

Auscultation of Aorta

The aorta is auscultated over the medial end of the second right intercostal space.

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Description

This quiz covers the anatomy and function of the sinuatrial node, which is located in the right atrium. It explores its connections to the superior vena cava and its role in cardiac conduction. Test your knowledge of the heart's electrical system and its components.