Anatomy Tables - Superior Mediastinum & Lungs

Topographic Anatomy

Structure/Space Description/Boundaries Significance
sternal angle (N185,TG4-04) the junction of the manubrium and body of the sternum it is an anterior projection located at the level of the costal cartilage of rib 2; an important landmark for internal thoracic anatomy
superior mediastinum (N231,TG4-35,TG4-36) superior to the transverse plane passing through the sternal angle and the junction of vertebrae T4/T5 main contents include: thymus, brachiocephalic veins, superior vena cava, aortic arch and the roots of its major branches, vagus (X) and phrenic nerves, left recurrent laryngeal n., trachea, esophagus, thoracic duct (Latin, medius = middle + stare = stand, thus the area which stands in the middle of the thorax)


Artery Source Branches Supply to Notes
aorta, ascending (N206,N232,TG4-38,TG4-39, Practical) 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
aortic arch (N206,N232,TG4-38,TG4-39, Practical) the continuation of the ascending aorta brachiocephalic trunk, left common carotid a., left subclavian a. the entire body except the heart aortic arch continues as the descending thoracic aorta; the fibrous ligamentum arteriosum connects to the inferior surface of the aortic arch and it marks the location of the fetal ductus arteriosus aortic arch continues as the descending thoracic aorta (Greek, aorta = to lift)
brachiocephalic trunk (N206,N232,TG4-38,TG4-39, Practical) aortic arch right common carotid a., right subclavian a. right side of the head and neck; right upper limb and right side of the chest wall there is only one brachiocephalic trunk (Greek/Latin, bracchium = arm + kephale = head)
carotid, common (N206,N232,TG4-38,TG4-39, Practical1, Practical2) brachiocephalic trunk (right), aortic arch (left) external carotid a., internal carotid a. most of the head and upper neck common carotid a. bifurcates at the level of the superior border of the thyroid cartilage; the internal carotid a. and the external carotid a. are its terminal brs.; the carotid sinus and carotid body are located at the bifurcation (Greek, kara = head)
subclavian (N206,N232,TG4-38,TG4-39, Practical) brachiocephalic a. (right), aortic arch (left) 1st part: vertebral a., thyrocervical trunk, internal thoracic a.; 2nd part: costocervical trunk; 3rd part: dorsal scapular a. (70%) neck, brain, spinal cord, thyroid gland, larynx, shoulder, chest muscles, upper limb subclavian a. is continuous with the axillary a., the name change occurs at the lateral border of the first rib; anterior scalene muscle passes anterior to the subclavian a., dividing it into 3 parts ("clavian" refers to the clavicle)
thoracic, internal (N191,TG4-19,TG4-09) subclavian a. (1st part) pericardiacophrenic a., perforating brs., anterior intercostal aa., mediastinal brs., thymic brs., musculophrenic a., superior epigastric a. mediastinum, anterior thoracic wall, anterior abdominal wall, respiratory diaphragm internal thoracic a. is also known as: internal mammary a.
pericardiacophrenic (N206,N191,TG4-19,TG4-20) internal thoracic a. pericardial br., sternal br., mediastinal br. pericardial sac, pleura, diaphragm pericardiacophrenic a. accompanies the phrenic n.
bronchial, left (N207,TG4-39) descending thoracic aorta right bronchial (occasionally) lower trachea, bronchial tree usually 2 in number


Vein Tributaries Drains Into Region Drained Notes
azygos (TG4-38, TG4-39, TG4-40, Practical) union of ascending lumbar & subcostal; post. intercostals 11-2 (rt. sup. intercostal), hemiazygos, accessory hemiazygos, esophageal, rt. bronchial sup. vena cava lateral & post. abdominal/chest wall, esophagus, bronchial tree may connect with inf. vena cava; arch of azygos passes sup. to root of lung (Greek,a- = not + zygon = yoke, therefore unyoked or unpaired, as the azygos vein)
brachiocephalic (N206,N212, TG4-19,TG4-18) union of subclavian & internal jugular; vertebral, thymic, inferior thyroid, internal thoracic, 1st post. intercostal, left sup. intercostal (to left brachiocephalic) left & right brachiocephalic unite to form sup. vena cava head, neck, upper limb, anterior chest wall at its origin, left brachiocephalic receives thoracic duct, right receives right lymphatic duct
intercostal, superior (TG4-37, Practical1, Practical2, Practical3) 2nd-4th posterior intercostal right: arch of azygos; left: left brachiocephalic intercostal spaces 2-4
thoracic, internal (TG4-17) union of musculophrenic and superior epigastric; ant. intercostal, perforating right - superior vena cava; left - left brachiocephalic anterior chest wall and upper anterior abdominal wall
thymic (N211,TG4-19) left brachiocephalic thymus (or thymic fat in adult)
thyroid, inferior (N 70,N238,TG7-13,TG4-19, Practical) left brachiocephalic thyroid gland inferiorly
vena cava, superior (N206,N212,N238,TG4-19,TG4-15) union of paired brachiocephalics; azygos arch rt. atrium body above diaphragm except for pulmonary vs. & heart


Structure Location Afferents from Efferents to Regions drained Notes
pulmonary nodes (N208,TG4-42,TG4-44) within the lung parenchyma lymphatic vessels from the parenchyma of the lung bronchopulmonary (hilar) nodes lung parenchyma, bronchial tree within the lungs pulmonary nodes are located along the larger bronchi of the lung
bronchopulmonary nodes (N208,TG4-42,TG4-44) hilum of the lung pulmonary nodes tracheobronchial nodes lung bronchopulmonary nodes are also known as: hilar nodes
tracheobronchial nodes, inferior (N208,TG4-42,TG4-44, Practical1, Practical2) inferior to tracheal bifurcation bronchopulmonary nodes, left side inferior tracheobronchial nodes drain into right inferior tracheobronchial nodes right superior tracheobronchial nodes lower lobes of the lungs; middle mediastinum; posterior mediastinum left inferior tracheobronchial nodes drain to the right side
tracheobronchial nodes, superior (N208,TG4-42,TG4-44) superolateral to the tracheal bifurcation bronchopulmonary (hilar) nodes paratracheal (tracheal) nodes lungs, middle mediastinum, posterior mediastinum inferior tracheobronchial nodes drain lymph from the lower lobe of the left lung to the right superior tracheobronchial nodes
tracheal (paratracheal) nodes (N208,TG4-42,TG4-44) coursing along the lateral surface of the trachea and esophagus superior tracheobronchial nodes bronchomediastinal trunk lungs, trachea, upper esophagus, the part of the larynx below the vocal folds paratracheal nodes are an important group of nodes in cases of pulmonary infection or lung cancer; also known as: tracheal nodes


Nerve Source Branches Motor Sensory Notes
phrenic n. (TG4-20,TG4-29, Practical1, Practical2, Practical3) ventral primary rami of spinal nerves C3-C5 (cervical plexus) no named branches skeletal muscle of the respiratory diaphragm diaphragmatic pleura; some fibers contributed to the pericardium and to the adjacent mediastinal and costal pleurae phrenic n. crosses the anterior surface of the anterior scalene m. (Greek, phren = diaphragm, for which we derive the word "frenzy," for the diaphragm was considered to be the seat of emotions)
vagus n. (TG7-51,TG7-52, Practical) 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; (Latin, vagus = wanderer, so called because of its wide distribution to the body cavities)
recurrent laryngeal n. (TG4-45,TG4-47A) vagus n. (X) esophageal brs., tracheal brs., cardiac brs., pharyngeal brs., inferior laryngeal n. upper esophagus, lower pharynx, laryngeal mm. (except cricopharyngeus); smooth muscle of the trachea; secretomotor to mucosal glands in the upper esophagus, lower pharynx, larynx below the vocal fold, trachea; cardiac muscle of the heart (slows heart rate, decreases force of contraction) upper esophagus, lower pharynx, larynx below the vocal folds, GVA from heart right recurrent laryngeal n. loops posteriorly around the right subclavian a.; left recurrent laryngeal n. loops posteriorly around the aortic arch and ligamentum arteriosum; the inferior laryngeal br. supplies all intrinsic muscles of the larynx EXCEPT the cricothyroid m.
cardiac plexus (N209,N226,N240,TG4-38,TG4-45) 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 (Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels)
pulmonary plexus (N209,N240,TG4-38,TG4-45, Practical) continuous with cardiac plexus, thoracic visceral ns., pulmonary brs. of vagus smooth muscle & glands of bronchial tree (parasymp.); vascular smooth muscle of lungs (symp.) located along pulmonary vessels & primary bronchi in root of lung (Latin, plexus = a braid, a network of nerves, blood vessels, or lymphatic vessels)


Organ/Part of Organ Location/Description Notes
trachea (N202,TG4-33,TG4-34) main airway that lies anterior to the esophagus trachea extends from vertebral level C6 to the level of the T4/5 intervertebral disc; superiorly it is connected to the cricoid cartilage via the cricotracheal ligament; it bifurcates into two primary bronchi (Greek, trachys = rough, originally the term for this structure was trachea arteria, the rough artery)
carina (N202,TG4-33,TG4-34) keel-shaped cartilage lying within the tracheal bifurcation carina trachealis is an important landmark during endoscopy of the bronchial tree (Latin, carina = keel of a boat)
main (primary) bronchus (N202,N203,TG4-33,TG4-34,TG4-38, Practical) pass inferolaterally from the bifurcation of the trachea at the level of the sternal angle to the hilum the right main bronchus is wider, shorter and runs more vertically than the left main bronchus; the left main bronchus passes inferior to the arch of the aorta and anterior to the esophagus and thoracic aorta (Latin, bronchus = windpipe, from the Greek brechein, to pour or moisten, from an ancient belief that solids were conveyed to the stomach by the esophagus and fluids by the bronchi)
hilum (N199,N211,TG4-30,TG4-31) medial surface of the lung the point at which the structures forming the root - the main bronchus, pulmonary vessels, bronchial vessels, lymphatic vessels, and nerves - enter and leave the lung
lung (N199,N211,TG4-30,TG4-31) the portion of the respiratory system where exchange of gasses occurs between the air and the blood; located in the thoracic cavity paired; right lung is divided into three lobes: superior, middle and inferior; left lung has two lobes: superior and inferior
lobe, superior (N201,N203,TG4-32AB,TG4-32CD) the portion of the lung supplied by the superior lobar bronchus superior lobe of the right lung: possesses three bronchopulmonary segments - apical, anterior and posterior; superior lobe of the left lung: possesses four bronchopulmonary segments - apicoposterior, anterior, superior lingular, inferior lingular
lobar (secondary) bronchi (N202,N203,TG4-33,TG4-34,TG4-38, Practical1, Practical2) branches of the main bronchus two on the left; three on the right (Latin, bronchus = windpipe, from the greek brechein, to pour or moisten, from an ancient belief that solids were conveyed to the stomach by the esophagus and fluids by the bronchi)
apex of lung (N199,N211,TG4-30,TG4-31, Practical) the blunt superior surface of the lung projecting above the level of the 1st rib into the root of the neck; covered by cervical pleura (Latin, apex = tip)
base of lung (N199,N211,TG4-30,TG4-31) the inferior surface of the lung that contacts the dome of the diaphragm also called the diaphragmatic surface
cardiac notch (N199,N211,TG4-30,TG4-31) indents the anteroinferior aspect of the superior lobe of the left lung creates the lingula, a tongue-like process of the superior lobe
fissure, oblique (N199,N211,TG4-30,TG4-31, Practical) deep groove in the surface of the lung that separates the upper lobe from the lower lobe (both lungs), and the middle lobe from the lower lobe (right lung) oblique fissure extends from the level of the T3 vertebra posteriorly to the 6th costochondral junction anteriorly
fissure, horizontal (N199,N211,TG4-30,TG4-31) deep groove in the surface of the lung that separates the middle lobe from the upper lobe (right lung only) horizontal fissure extends from the 5th rib at the mid-axillary line along the 4th rib to the sternum anteriorly
lingula (N199,N211,TG4-30,TG4-31, Practical1, Practical2) lower portion of superior lobe of left lung; below cardiac notch (Latin, lingula = little tongue)
lobe, inferior (N201,N203,TG4-32AB,TG4-32CD) the portion of the lung supplied by the inferior lobar bronchus inferior lobe of the right lung: possesses 5 bronchopulmonary segments - superior, anterior basal, posterior basal, medial basal, lateral basal; inferior lobe of the left lung: possesses 5 bronchopulmonary segments - superior, anterior basal, medial basal (may be fused into anteromedial basal), posterior basal, lateral basal
lobe, middle (N201,N203,TG4-32AB,TG4-32CD) the portion of the right lung supplied by the middle lobar bronchus middle lobe is found in the right lung only; it possesses 2 bronchopulmonary segments: medial and lateral; lingula of the inferior lobe of the left lung is equivalent to the middle lobe of the right lung
lingular bronchus (N202,N203,TG4-33,TG4-34,TG4-38, Practical) bronchus branch located in the lingula of the left lung (Latin, bronchus = windpipe, from the greek brechein, to pour or moisten, from an ancient belief that solids were conveyed to the stomach by the esophagus and fluids by the bronchi)
segmental (tertiary) bronchi (N202,N203,TG4-33,TG4-34,TG4-38), Practical) branches of the lobar bronchi (Latin, bronchus = windpipe, from the greek brechein, to pour or moisten, from an ancient belief that solids were conveyed to the stomach by the esophagus and fluids by the bronchi)
bronchopulmonary segments (N202,N203,TG4-33,TG4-34,TG4-38) branches of the segmental bronchi pyramidal-shaped segment of the lung, with its apex facing the root and its base at the pleural surface; these are the largest subdivisions of a lobe, separated by septa, and are named according to the segmental broncus supplying it

Clinical Terms

Term Definition
bronchoscopy an examination used for inspection of the interior of the tracheo-bronchial tree, performance of endobronchial diagnostic tests, taking of specimens for biopsy and culture and removal of foreign bodies
pneumonectomy an operation to remove an entire lung
chronic obstructive pulmonary disease (COPD) a progressive disease process that most commonly results from smoking and mainly affects expiratory air flow. COPD includes chronic bronchitis and emphysema. Obstructive pulmonary disease is characterized by difficulty breathing, wheezing, and a chronic cough; treatment includes absolute avoidance of smoking, bronchodilators and oxygen for those with advanced disease; complications include bronchitis, pneumonia

The material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest & Jaye Schlesinger
Published by ILOC, Inc., New York
Copyright © 1995, unauthorized use prohibited.
The excellent editorial assistance of
Dr. Pat Tank, UAMS
is gratefully acknowledged.


Updated: 14 Oct 2011