Function of the Auricle in heart

What is the function of the auricles (conical appendages through the atria) present in the heart?

Do they have any other function than increasing the volume of blood the heart can hold?

The left auricle is a decompression chamber when atrial blood pressure is high (in systole or in some pathological conditions) [1, 2]. Some research claims it also plays a role in cardiac regeneration because it contains cardiac progenitor cells [3].

Probably the right auricle has less important function; also there are fewer studies about it.


  1. Al-Saady NM, Obel OA, Camm AJ. Left atrial appendage: structure, function, and role in thromboembolism. Heart. 1999 Nov;82(5):547-54. PubMed PMID: 10525506.

  2. Bansal M, Kasliwal RR. Echocardiography for left atrial appendage structure and function. Indian Heart J. 2012 Jul 27;64(5):469-75. doi: 10.1016/j.ihj.2012.07.020. PubMed PMID: 23102384.

  3. Leinonen JV, Emanuelov AK, Platt Y, Helman Y, Feinberg Y, Lotan C, Beeri R. Left atrial appendages from adult hearts contain a reservoir of diverse cardiac progenitor cells. PLoS ONE. 2013 Mar 12;8(3):e59228. doi: 10.1371/journal.pone.0059228. PubMed PMID: 23555001.

Structure of Heart (With Diagram) | Circulatory System | Human Physiology

After reading this article you will learn about the structure of human heart. This will also help you to draw the structure and diagram of human heart.

The Heart lies in the thoracic cavity between the two lungs in the mediastinal space and behind the sternum. It is directed more to the left than to the right side. The anterior surface of the heart faces the sternum, the posterior surface faces the vertebral column and the interior surface rests on diaphragm. The heart is composed of a specialized cardiac muscle which possesses the special property of automatic rhythmical contraction.

The heart is consisting of three layers:

1. Pericardium or outer covering layer:

The heart lies in a double membranous sac of pericardium with serous fluid between the two layers. This is known as pericardial fluid. By its lubricating action, the heart can move freely or contracts and expands without any injury. So it allows the easy movement of the heart. It keeps the heart moist and absorbs external shock.

This is the middle muscular layer. The thickness of the heart wall is composed of a network of heart muscle fibers which is known as myocardium. The muscular walls of the heart very in thickness. The ventricles have the thickest walls. The walls of the left ventricles are thicker then those of right ventricle because the force of contraction of the left ventricle is much greater. The walls of the auricle are composed of thinner muscles.

This is the inner layer of the heart. The heart is lined by endothelium layer which is known as Endocardium. The valves attached to the heart are the thickened portions of this membranes.

Auricles and Ventricles:

The heart is divided by a septum into two sides right and left. These two parts are automatically joined together, but physiologically separate. There is normally no communication between these sides after birth.

Each side of the heart consists of two chambers:

(1) An upper thin walled atrium or auricle and

(2) The lower thick walled chamber called as ventricle.

There are two auricles or atrium right and left and two ventricles. The auricles act as receiving chambers and the ventricles the pumping chambers. The auricles and ventricles of each side communicate with one another by means of the auriculo-ventricular openings. These openings are guarded by valves which permit blood to flow from auricles to the ventricles but not in the opposite direction – that is from ventricle to auricles.

On the right side, the auriculo-ventricular opening is guarded by tricuspid valve which is composed of three flaps and on the left side by the bicuspid valve which is composed of two flaps. When the auricles are contracted, the tricuspid and bicuspid valves open and blood enters into the ventricles. But when ventricles are contracted, the flaps in the valves open like umbrella and close the auriculo ventricular openings, so that blood cannot pass back again to the auricles.

The blood in the ventricles is forced to go into the respective blood vessels which arise from them, the pulmonary artery from right ventricle and aorta from the left ventricle. The opening leading to the pulmonary artery and the aorta are guarded by different types of valves which are called semilunar valves. These valves permit the blood to enter these arteries. They prevent back flow of blood.

Two large veins named superior vena cava and inferior vena cava are attached to the right auricle which brings impure or deoxygenated blood from all parts of the body. The left auricle is attached with four pulmonary veins which carry pure or oxygenated blood from the lungs.

Heart of Cyclostomes

Lamprey's (Petromyzon) heart is like the English letter 'S'. It is formed by folding the posterior side of the gill and the sub-intestinal vessels. The larval heart develops as a straight duct. Later, this duct becomes longer and takes the shape of ‍‘S’ in a limited space. The heart consists of the sinus venosus, an atrium and a ventricle, and the conus arteriosus and is covered by the pericardium. A cartilage plate holds the pericardium. The sinus venosus is a thin-walled chamber that is exposed through a sinus-auricular opening to a thin-walled atrium at the top. The atrium is again connected to the thick-walled ventricle through the auricle-ventricular opening.

In Anatomy, what is the Auricle? (with pictures)

In the context of human anatomy, the auricle can refer to either one of two distinct body parts: the outer ear or an internal “pouch” or protective layer in the heart. These parts aren’t related except for their shared name. With respect to the ear, the term basically describes everything that’s visible outside the head. People don’t often realize that the ear is more than just the outward protrusion at the side of the face, but internally it’s quite complex. When it comes to the heart, the auricle is part of the atrium, which is actually two chambers — one on the left and one on the right — and the term refers to the muscular pouch-like cover that protects each of these spaces. As such, each person usually has two, one for each atrium.

Sound Collection

Most people, and especially children, think of the auricle when they refer to the ear. In truth the ear is much more complex than what’s seen externally. In most cases it’s made up of three parts: the outer ear, which is visible and is where sound is collected the middle ear, where sound is processed and the inner ear, where that sound is actually reverberated and translated by the brain into something intelligible. The outer portion is sometimes also called the pinna.

How the External Ear Works

Different people can have slightly different shaped and sized outer ears, and a lot of this is determined by genetics. Just the same, in nearly all cases the basic shape is the same. This part of the ear is made of flexible cartilage, and it’s protruding, layered shape is designed to not only amplify sound, but to filter it as well. To achieve this perhaps seemingly simple task, eleven different parts work together to reflect and channel sound vibrations from the environment. Noises are amplified and directed from outside of the person and into the auditory canal.

The outer ear works differently depending on the frequency of a sound. Low frequencies are directed toward the auditory canal, but there is an extra phase of noise processing for high-pitch sounds, which makes the filtering function even more valuable. People who have degenerative hearing problems or who suffer from progressive hearing loss often first notice the issue when they aren’t able to hear sounds in certain ranges, particularly those that are very high. Over time and after constant exposure to loud sounds, the filtering function of the outer ear can break down.

In the Heart

When referencing the heart, the auricle typically describes part of either the left of the right atrium. The human heart is made up of four main chambers, two ventricles and two atria, one each on the left and right sides. Atria typically sit just above the ventricles and help process blood as it pumps. In decades past, medical experts often referred to the atria as the left and right auricles, but this reference isn’t usually made anymore. Today, the term is typically used to refer to the small, cone-shaped, muscular pouch that projects from the atrium, insulating and in some ways protecting it. These pouches help the atria hold more blood, and in this respect they essentially serve as reservoirs.

Differences from Left to Right

The right pouch, also commonly called the “right auricular appendix,” is typically larger than the left one, which is also known as the “left atrial appendage.” Similarly, the right atrium is larger than the left atrium. They’re both located at the receiving end of the cavities, though, and the difference is largely due to the different functions of the atria themselves. The right atrium accepts de-oxygenated blood that is returning to the heart from the upper body via the superior vena cava and from the lower body via the inferior vena cava. By contrast, the left atrium receives oxygenated blood returning to the heart from the lungs via the pulmonary vein. Different volumes and pressures of blood are needed to execute these different functions.


  • Cardiogenic region - in splanchnic mesenchyme of prechordal plate region
  • Week 2 pair of thin-walled tubes tubes fused, truncus arteriosus outflow, heart contracting heart tube continues to elongate, curving to form S shape Septation starts, atrial and ventricular
  • Septation continues, atrial septa remains open, foramen ovale
  • Week 40 At birth pressure difference closes foramen ovale leaving a fossa ovalis

Comparison Human and Mouse

Heart Innervation

Comparison of Human, Mouse and Chicken heart innervation timeline. Δ]

  • DRG - dorsal root ganglion
  • HH - Hamburger and Hamilton stage
  • LA - left atrium
  • LV - left ventricle
  • OFT - outflow tract
  • RA - right atrium
  • RV - right ventricle
  • PEO - proepicardial organ

Week 9

Images from human heart (week 9) Ε]

fig 1 Ventrocephalic heart 31.5 mm embryo

fig 2 Dextral heart 31.5 mm embryo superficial cardiac vessels

fig 3 Dorsal heart 31.5 mm embryo

fig 4 Dextral heart 25 mm embryo atrium opened

fig 5 Dextral heart 25 mm embryo

fig 6 Dextral heart 31.5 mm embryo

fig 7 Dextral heart 31.5 mm embryo

fig 8 Sinistral heart 25 mm embryo

fig 9 Sinistral heart 31.5 mm embryo interatrial septal complex

fig 10 Tricuspid valve 31.5 mm embryo

fig 11 Pulmonary semilunar valves 31.5 mm embryo

fig 12 Branches coronary arteries supply sino-atrial node

fig 13 Branches coronary arteries supply bundle of His and its main branches

fig 14 Ventral heart and great vessels 31.5 mm embryo

fig 15 Dorsal heart 31.5 mm embryo

fig 16 Sinoventricular conduction system heart 31.5 mm embryo

fig 16a Right atrium near level of entrance of superior vena cava

fig 16b Detail from A box

fig 16c Interventricular septum

fig 16d Detail from C box

1. Step One: Orientation

When you first remove your heart from the bag, you will see a lot of fatty tissue surrounding it. It is usually a waste of time to try to remove this tissue. Grab some colored pencils to help you identify and mark the vessels you find.

There are a few clues to help you figure out the left and the right side, but often the packaging and preserving process can cause the heart to be misshapen. If you are lucky, the heart will be nicely preserved and you will see that the front (ventral) side of the heart has a couple of key features: 1) a large pulmonary trunk that extends off the top of it 2) the flaps of the auricles covering the top of the atria. 3) the curve of the entire front side, whereas the backside is much flatter.

The first image shows the front side of the heart, often identified by the coronary sinus that runs cross it at an angle (yellow).

The auricle is the flap that covers the atrium, it looks like an ear. The pulmonary trunk is the located at the front of the heart and enters at an angle.

Step 2: Locate the Aorta

Use your fingers to probe around the top of the heart. Four major vessels can be found entering the heart: the pulmonary trunk, aorta, superior vena cava, and the pulmonary vein. Remember that if you are looking at the back of the heart, then the right and left sides are the same as your right and left hand. This picture was on the board the day of the dissection so that you could glance up and recall which vessel entered which part of the heart.

If you find the pulmonary vein, the aorta should be situated a little bit behind it. It may be covered by fat, so use your fingers to poke around until you find the opening. Push your finger all the way in and you will feel inside of the left ventricle. The left ventricle has a very thick wall, unlike the right ventricle. Insert your finger through the pulmonary vessel to feel the left ventricle and you will notice and feel that it is much thinner than the left side of the heart.

With your fingers or probes in the aorta and the pulmonary trunk you should notice that they criss-cross each other, with the pulmonary trunk in the front.

At this point, you may want to use your colored pencils to mark these vessels so that you don't get them confused when you are searching for the other two openings that top of the heart.

Step 3: Locate the Veins

The two major veins that enter the heart can be found on the backside, as both enter the atria. On the left side, you should be able to find the opening of the pulmonary vein as it enters the left atrium. The superior vena cava enters the right atrium. In many preserved hearts, the heart was cut at these points, so you won't see the vessels themselves, you will just find the openings. Again, use your fingers to feel around the heart to find the openings. If you've marked the aorta and pulmonary then you won't mistake them for the veins you are looking for. This picture shows all of the vessels labeled.

Sometimes, the aorta still has its branches attached to it. There are three vessels that branch from the aorta: the brachiocephalic, left common carotid and the left subclavian. The majority of the time, these vessels are not visible because the aorta was cut too close to the main part of the heart when the heart was removed from the animal. Occassionally, you can find the brachiocephalic artery attached, as it is in this photo.

Tricyclic and Other Cyclic Antidepressants


CAs alter the cardiac conduction system in a myriad of ways. The most distinctive toxicity relates to the inhibition of the fast sodium channels in the His-Purkinje tissue, leading to a slowing of phase 0 depolarization. 46, 47 This “membrane stabilizing” or “quinidine-like” effect is analogous to that of Vaughn Williams (VW) class I antidysrhythmic drugs. 48 Impaired depolarization of cells within the His-Purkinje system slows the propagation of ventricular depolarization. This appears on the electrocardiogram (ECG) as prolongation of the QRS interval, the hallmark of TCA toxicity. The degree of conduction delay is rate-dependent and worsens with tachycardia. 49 The QRS morphology is generally that of nonspecific intraventricular conduction delay, with discrete bundle branch block being less common. However, the longer refractory period of the right bundle relative to the left leads to the characteristic rightward axis deviation of the terminal 40 msec of the QRS complex seen in many patients with TCA toxicity. 50 On the ECG this appears as an increased R wave amplitude in lead aVR and a deep S wave in leads I and aVL ( Fig. 27-2 ). 51 A less specific finding is prolongation of the corrected QT interval (QTc). This delay in myocyte repolarization may result from a direct effect of CAs on potassium channels. 52, 53 A prolonged QTc may also be seen in therapeutic dosing.

Health Solutions From Our Sponsors

Top What Are the Four Main Functions of the Heart Related Articles

Coronary Heart Disease Screening Tests (CAD)

Coronary heart disease or coronary heart disease (CAD) screening tests can be used to potentially prevent a heart attack or cardiac event in a person without heart disease symptoms, and can assist in diagnosing heart disease in individuals with heart disease symptoms. Examples of coronary heart disease tests include:

Function of the Heart

The heart's only function is to pump blood.

The right side of the heart: Pumps blood to the lungs, where oxygen is added to the blood and carbon dioxide is removed

The left side of the heart: Pumps blood to the rest of the body, where oxygen and nutrients are delivered to tissues and waste products (such as carbon dioxide) are transferred to the blood for removal by other organs (such as the lungs and kidneys)

A Look Into the Heart

This cross-sectional view of the heart shows the direction of normal blood flow.

Blood travels the following circuit: Blood from the body, which is depleted of oxygen and laden with carbon dioxide, flows through the two largest veins—the superior vena cava and the inferior vena cava, known collectively as the venae cavae—into the right atrium. When the right ventricle relaxes, blood in the right atrium pours through the tricuspid valve into the right ventricle. When the right ventricle is nearly full, the right atrium contracts, propelling additional blood into the right ventricle, which then contracts. This contraction closes the tricuspid valve and propels blood through the pulmonary valve into the pulmonary arteries, which supply the lungs. In the lungs, blood flows through the tiny capillaries that surround the air sacs. Here, the blood absorbs oxygen and gives up carbon dioxide, which is then exhaled.

Blood from the lungs, which is now oxygen-rich, flows through the pulmonary veins into the left atrium. When the left ventricle relaxes, the blood in the left atrium pours through the mitral valve into the left ventricle. When the left ventricle is nearly full, the left atrium contracts, propelling additional blood into the left ventricle, which then contracts. (In older people, the left ventricle does not fill as well before the left atrium contracts, making this contraction of the left atrium especially important.) The contraction of the left ventricle closes the mitral valve and propels blood through the aortic valve into the aorta, the largest artery in the body. This blood carries oxygen to all of the body except to the lungs.

The pulmonary circulation is the circuit through the right side of the heart, the lungs, and the left atrium.

The systemic circulation is the circuit through the left side of the heart, most of the body, and the right atrium.

Does the auricle have a significant function?

Ear dyskinesias The auricular muscles are vestigial in humans and few individuals can move their ears voluntarily. As a result, the auricular muscles are generally considered to be of little functional significance, although auricular reflexes activate ear muscles during eye movements (Urban et al., 1993).

Likewise, what is the function of the right and left Auricles? The right auricle receive non-oxygenated blood from upper and lower venae cavae and small veins in the thorax and direct it to the right ventricle. While the left auricle receive oxygenated blood coming from lungs through pulmonary veins and direct it to the left ventricle.

Also asked, what is the function of the auricle?

The pinna is the only visible part of the ear (the auricle) with its special helical shape. It is the first part of the ear that reacts with sound. The function of the pinna is to act as a kind of funnel which assists in directing the sound further into the ear.

What are the divisions of the auricle?

The medical term for the outer ear is the auricle or pinna. The outer ear is made up of cartilage and skin. There are three different parts to the outer ear the tragus, helix and the lobule. The ear canal starts at the outer ear and ends at the ear drum.

Watch the video: Πως λειτουργεί το σώμα μου - Το δέρμα (January 2022).