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Each atrium is roughly cube-shaped except for an ear-shaped projection called an atrial appendage, previously known as an auricle. All animals with a closed circulatory system have at least one atrium. The atrium was formerly called the 'auricle'. [1] That term is still used to describe this chamber in some other animals, such as the Mollusca ...
Auricle, auricula or auricula may refer to: Auricle (anatomy), the external portion of the ear; Auricle, former name of the atrium of the heart; still used to describe this chamber in some other animals; Auricle (botany), an ear-like projection on the base of a leaf or petal; Auricles, ear-like projections at the base of the head of a planarium
The developing auricle is first noticeable around the sixth week of gestation in the human fetus, developing from the auricular hillocks, which are derived from the first and second pharyngeal arches. These hillocks develop into the folds of the auricle and gradually shift upwards and backwards to their final position on the head.
The outer ear is the external portion of the ear and includes the fleshy visible auricle, the ear canal, and the outer layer of the eardrum (also called the tympanic membrane). [2] [3] The auricle consists of the curving outer rim called the helix, the inner curved rim called the antihelix, and opens into the ear canal.
The left heart has two chambers: the left atrium and the left ventricle, separated by the mitral valve. [8] The left atrium receives oxygenated blood back from the lungs via one of the four pulmonary veins. The left atrium has an outpouching called the left atrial appendage. Like the right atrium, the left atrium is lined by pectinate muscles. [25]
Characterizing the size of the left atrium according to its volume is preferred over a single linear dimension since enlargement can be different for different directions. For example, because of the smaller distance in the thoracic cavity between the sternum and spine , compared to the other directions, less room exists for enlargement of the ...
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
The coronary sulcus (also called coronary groove, auriculoventricular groove, atrioventricular groove, AV groove) is a groove on the surface of the heart at the base of right auricle that separates the atria from the ventricles.