Middle Mediastinum and Heart

Gross Anatomy


Middle Mediastinum and External Features of the Heart


Anatomy Tables for Today's Topic

Arteries of the Heart
Veins of the Heart
Parts of the Heart
Nerves of the Thoracic Cavity

Arteries of the Heart

ArterySourceBranchesSupplyNotes
aorta, ascending left ventricle of the heart left and right coronary aa. heart, entire body ascending aorta is the shortest part of the aorta; it continues as the aortic arch
artery to the atrioventricular node right coronary a. near the point where it becomes the posterior interventricular a. no named branches atrioventricular node and the surrounding myocardium artery to the atrioventricular node is located at the junction of the coronary sulcus and the posterior interventricular sulcus
artery to the sinuatrial node right coronary a. no named branches sinuatrial node and the surrounding myocardium artery to the sinuatrial node is important artery to locate during cardiac surgical procedures
circumflex left coronary a. marginal br., possibly posterior artery of the left ventricle posterior surface of the left ventricle circumflex a. courses in the atrioventricular (coronary) sulcus
coronary, left ascending aorta anterior interventricular a., circumflex a. left ventricle, left atrium, anterosuperior 2/3 of the interventricular septum left coronary a. arises superior to the left cusp of the aortic semilunar valve; during its short course, it is located in the coronary sulcus; the anterior interventricular a. and the circumflex a. are its terminal brs.
coronary, right ascending aorta sinuatrial nodal a., right marginal a., posterior interventricular a., atrioventricular nodal a. right ventricle, right atrium, inferior 1/3 of the interventricular septum right coronary a. usually provides the posterior interventricular a.; it courses within the coronary sulcus

Veins of the Heart

VeinTributariesDrains IntoRegion DrainedNotes
cardiac, anterior no named veins are tributary to these vessels right atrium anterior surface of the right ventricle anterior cardiac vv. cross the superficial surface of the right coronary a.
cardiac, great ventricular vv. unites with the oblique v. of the left atrium to form the coronary sinus region of the heart near the anterior interventricular sulcus great cardiac v. is the longest of the cardiac vv.; it accompanies the anterior interventricular a.
cardiac, middle ventricular vv. coronary sinus region of the heart near the posterior interventricular sulcus middle cardiac v. accompanies the posterior interventricular a.
cardiac, small no named veins are tributary to this vessel coronary sinus region of the heart near the inferior vena cava and right coronary sulcus small cardiac v. courses through the coronary sulcus with the right coronary a.
cardiac, smallest no named veins are tributary to these small vessels drain directly into the heart chambers, particularly the atria myocardium also known as: Thebesian vv.; least cardiac vv.; venae cordis minimae
coronary sinus formed by the union of the great cardiac v. and the oblique v. of the left atrium; tributaries: middle cardiac v., small cardiac v. right atrium heart, except the region drained by the anterior cardiac vv. and the smallest cardiac vv. coronary sinus is located in the coronary (atrioventricular) sulcus; its opening into the right atrium is guarded by an imperfect valve
oblique v. of the left atrium no named tributaries coronary sinus left auricle and a small portion of the left atrium oblique v. of the left atrium is the remnant of the embryonic left superior vena cava, the proximal portion of which forms the coronary sinus

Parts of the Heart

Organ/Part of Organ Location/Description Notes
heart muscular pump for blood located within middle mediastinum of the thorax heart is nearly surrounded by the pericardial sac and pericardial cavity
coronary sulcus groove on the surface of the heart that separates the atria from the ventricles coronary sulcus contains the coronary sinus, circumflex a., and right coronary a.
apex tip of the left ventricle of the heart apex of the heart is located 3" to the left of the midline at the level of the 5th intercostal space
atrium, right chamber of the heart that receives deoxygenated blood from the systemic circulation (body) right atrium forms the right margin of the heart; it receives blood from the superior vena cava, inferior vena cava and coronary sinus
atrium, left chamber of the heart that receives oxygenated blood from the pulmonic circulation (lungs) left atrium is located on the posterior aspect of the heart; it receives blood from the pulmonary vv.
auricle small appendage that projects anteriorly from the atrium paired, one on each atrium; right auricle lies beside the aorta and covers the right coronary artery; left auricle lies beside the pulmonary trunk
base the superior aspect of heart base of the heart is where the aorta, pulmonary trunk and superior vena cava exit/enter the heart
interventricular sulcus, anterior groove between the ventricles on the anterior surface of the heart anterior interventricular sulcus contains the anterior interventricular a. and the great cardiac v.; it marks the location of the interventricular septum
interventricular sulcus, posterior groove between the ventricles on the diaphragmatic surface of the heart posterior interventricular sulcus contains the posterior interventricular a. and the middle cardiac v.; it marks the location of the interventricular septum
ligamentum arteriosum fibrous cord of connective tissue that connects the left pulmonary a. near its origin with the undersurface of the aortic arch ligamentum arteriosum is a remnant of the ductus arteriosus; the left recurrent laryngeal n. passes beneath it
pericardial sinus, oblique an area of the pericardial cavity located behind the left atrium of heart serous pericardium reflects onto the inferior vena cava and pulmonary vv. to define this space
pericardial sinus, transverse an area of the pericardial cavity located behind the aorta and pulmonary trunk and anterior to the superior vena cava transverse pericardial sinus was a simple structure when the heart tube began to form during development; it separates the outflow vessels from the inflow vessels of the heart
pericardium, fibrous a fibrous sac that attaches to the central tendon of the diaphragm and fuses with the adventitia of the great vessels superiorly fibrous pericardium contains the pericardial cavity and heart; it is lined on its inner surface by the parietal layer of serous pericardium; it defines the outermost boundary of the middle mediastinum
pericardium, parietal serous serous membrane lining the pericardial cavity; it is located on the inner surface of the fibrous pericardium parietal serous pericardium reflects onto the heart at the origins of the great vessels to become continuous with the visceral serous pericardium
pericardium, visceral serous serous membrane covering the surface of the heart visceral serous pericardium reflects onto the inner surface of the fibrous pericardium at the origins of the great vessels to become continuous with the parietal serous pericardium; also known as: epicardium
sulcus terminalis groove on the external surface of the right atrium marking the location of the crista terminalis the sinuatrial node is located at the superior end of the crista terminalis
ventricle, right heart chamber that pumps blood to the pulmonary circulation right ventricle has a septomarginal trabecula and 3 papillary mm.; it pumps blood into the pulmonary trunk
ventricle, left heart chamber that pumps blood to the systemic circulation left ventricle has 2 papillary mm.; it pumps blood into the ascending aorta
atrioventricular node part of the conduction system of the heart atrioventricular node is located in the wall of the right atrium above the opening of the coronary sinus and the septal cusp of the tricuspid valve
atrioventricular bundle part of the conduction system of the heart atrioventricular bundle is a strand of specialized myocardium that passes through the right fibrous trigone into the muscular part of the interventricular septum; it divides into right and left branches to supply the ventricles; also known as: bundle of His
sinuatrial node part of the conduction system of the heart sinuatrial node is located within the crista terminalis near the superior vena cava; it is the "pacemaker" of the heart

Nerves of the Thoracic Cavity

Nerve Source Branches Motor Sensory Notes
cardiac plexus cardiac brs. of the vagus n. and cervical sympathetic trunk; thoracic visceral nn. no named branches moderates heart muscle (parasympathetic: decreases rate and force of contraction; sympathetic: increases rate and force of contraction); vascular smooth muscle of the heart & lungs (sympathetic); smooth muscle & mucous glands of bronchial tree (parasympathetic) pain from the heart and lungs cardiac plexus is continuous with the coronary and pulmonary plexuses; thoracic visceral nn. carry pain from the heart to the upper thoracic spinal cord segments resulting in pain referred to the left upper limb in the T1 and T2 dermatomes
cardiac, sympathetic cervical sympathetic trunk no named branches heart (sympathetic: increases rate and force of contraction, parasympathetic: decreases rate and force of contraction); bronchial tree & lungs via pulmonary plexus heart, bronchial tree and lungs cervical sympathetic trunk usually gives 3 cervical cardiac brs. l (superior, middle and inferior) to the cardiac plexus
cardiac, vagal vagus n. (X) no named branches heart (parasympathetic: decreases rate and force of contraction; sympathetic: increases rate and force of contraction); bronchial tree and lungs via pulmonary plexus heart, bronchial tree and lungs vagus n. has 2 cervical cardiac brs. (superior and inferior) and 1 or more thoracic cardiac brs.
pulmonary plexus continuous with the cardiac plexus; thoracic visceral nn.; pulmonary brs. of vagus no named branches parasympathetic: smooth muscle & glands of the bronchial tree; sympathetic: vascular smooth muscle of the lungs none pulmonary plexus is located along the pulmonary vessels and primary bronchi in the root of the lung
vagus n. medulla: dorsal motor nucleus (GVE preganglionic parasympathetic); inferior ganglion (GVA); nucleus ambiguus (SVE); superior ganglion (GSA); inferior ganglion(SVA) auricular br., pharyngeal br., superior laryngeal, superior and inferior cervical cardiac brs., recurrent laryngeal n., thoracic cardiac brs., brs. to the pulmonary plexus, brs. to the esophageal plexus, anterior and posterior vagal trunks SVE: intrinsic muscles of the larynx, pharynx (except stylopharyngeus), and palate (except tensor veli palatini); GVE: smooth muscle of the respiratory tree & gut (proximal to the left colic flexure), heart; secretomotor: mucous glands of the larynx, respiratory tree, pharynx and gut; secretomotor to digestive glands GSA: skin of the external auditory meatus; GVA: viscera of head, neck, thorax & abdomen proximal to the left colic flexure; SVA: taste from the epiglottis also known as: CN X, 10th cranial nerve; the vagus n. passes through the jugular foramen to exit the posterior cranial fossa; vagus means "wanderer" in reference to its extensive distribution to the body cavities


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Some of the material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest and Jaye Schlesinger
Published by ILOC, Inc., New York. Copyright 1995.

Content of tables edited for use in this course by Patrick W. Tank, Ph.D.
Copyright 2005, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences.

Unauthorized use is prohibited.