| Term 
 | Definition 
 
        | thin, whitish connective tissue deep to the superficial fascia; it invests all skeletal muscles and it has no fat. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Deepest layer of the skin and immediately above the superficial fascia. Undersurface has numerous tiny pits that serve as entry points into the skin for nerves and blood vessels |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Surface layer of the skin, typically less than 1mm thick. |  | 
        |  | 
        
        | Term 
 
        | Posterior cutaneous nerve |  | Definition 
 
        | It is a continuation of a dorsal ramus that beings at the superficial level of the erector spinae muscle. It provides somatosensory innervation to the skin of the back from the neck to the sacrum. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Just deep to the dermis of the skin. Characterized by connective tissue and variable amounts of fat, and varies in thickness throughout the body. |  | 
        |  | 
        
        | Term 
 
        | Anterior longitudinal ligament |  | Definition 
 
        | Located on anterior surface of vertebral bodies and intervening IV disks, spanning from C1 to sacrum. Limits extension of the spine. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Thin, transparent membrane between the dura and pia; its extent is the same as the dura to which it is adherent. It extends from the base of the skull to the S2 level within the vertebral canal. It is the outer membrane that confines CSF. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A vertically oriented collection of dorsal and ventral roots (and the filum terminale) that extends below the tip of the spinal cord down to the level of S2. In the lumbar region of vertebral canal and extends into the sacral canal to S2. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The tapered portion of the distal end of the spinal cord. Its tip is typically at the L2 vertebrae. It contains the distal most spinal cord segments. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Right and left lateral extensions of pia mater spanning between the periphery of the spinal cord to the dura mater. The lateral edge of the denticulate ligament is scalloped, as the ligament attaches to dura at intervals. Helps stabilize the spinal cord. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | First branch of a spinal nerve that courses dorsally |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A peripheral nerve that connects to the dorsal aspect of the spinal cord to a spinal nerve. It has a swelling (DRG) near where it joins the spinal nerve. It contains only sensory axons. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A swelling on a dorsal root located immediately proximal to a spinal nerve. It contains somatosensory and viscerosensory cell bodies. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Tough outermost layer of the three meninges. Surrounds the spinal cord from base of the skull to S2. It has laterally directed sleeves at the level of each of the 31 pairs of spinal nerves. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The space immediately above/external to the dura mater. Within vertebral and sacral canals. It houses epidural fat and the vertebral venous plexus. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Largest of the deep back muscles. Parallels the vertebral column, occupying the area immediately adjacent to the spine. Innervated by dorsal primary rami. Functions to extend the spine. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Synovial joints between superior and inferior articular processes of adjacent vertebrae. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Slender strand of pia mater that extends from tip of spinal cord to coccyx. Lighter in color than the nerve roots of the cauda equina. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Dense CT spanning between each of the spinous processes of vertebra C2 to L5. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Paired ligament that spans between adjacent laminae of all vertebrae. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Slight swelling of the distal spinal cord. Seen just above the conus medullaris. |  | 
        |  | 
        
        | Term 
 
        | Posterior cutaneous nerve |  | Definition 
 
        | Nerves that are continuations of the dorsal primary rami; they begin at the surface of the erector spinae muscle and continue to the skin, passing through superficial back muscles without innervating them. |  | 
        |  | 
        
        | Term 
 
        | Posterior longitudinal ligament |  | Definition 
 
        | Located within the vertebral canal on the posterior surface of the vertebral bodies, spanning from C1 to C7. |  | 
        |  | 
        
        | Term 
 
        | Posterior spinal arteries |  | Definition 
 
        | Two, very small arteries that course longitudinally on the posterior surface of the spinal cord. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Occupies vertebral canal and extends from brain to the L2 vertebral level. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Region of spinal cord that gives rise to a pair of spinal nerves. It contains ventral and dorsal horns associated with the spinal nerve pair. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The very short structure formed by the junction of dorsal and ventral roots. It is just lateral to the DRG. Spinal nerves almost immediately branch into ventral and dorsal rami. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The space between the arachnoid and the pia and occupied by the CSF. Extends from base of skull to S2. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Spans from C2 to L5, attaching to the tips of the spinous processes. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A potential space between the dura and the arachnoid. It is only present in pathologic states. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Large, first branch of a spinal nerve. It courses ventrally. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A peripheral nerve that connects the ventral aspect of the spinal cord to a spinal nerve. It contains only motor axons. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | An extensive, interconnected venous plexus located both within and external to the vertebral canal, spanning from the base of the skull to the sacrum. There are no valves in this plexus, so blood, infectious materials and metastatic cancer cells can spread in any direction through the veins. |  | 
        |  | 
        
        | Term 
 
        | Anterior cutaneous nerves |  | Definition 
 
        | Terminal branches of intercostal and thoracoabdominal nerves. They arise adjacent to the sternum within intercostal spaces 1-6, and about 1 finger-breadth lateral to the linea alba in the abdomen. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A curving line that marks the inferior most aspect of the dense part of the posterior rectus sheath. It is located about two inches below the umbilicus. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Fatty layer of superficial fascia in the lower portion of the abdominal wall |  | 
        |  | 
        
        | Term 
 
        | External abdominal oblique aponeurosis |  | Definition 
 
        | Flat, sheet-like tendon of the the external abdominal oblique, attaches to the linea alba. |  | 
        |  | 
        
        | Term 
 
        | External abdominal oblique muscle |  | Definition 
 
        | Broad, thin muscles on the anterolateral abdominal wall just deep to Scarpa's fascia. |  | 
        |  | 
        
        | Term 
 
        | External intercostal muscle |  | Definition 
 
        | Superficial most muscle of an intercostal space. Its muscle fascicles slant downward and medially. Best seen lateral to a costochondral junction. |  | 
        |  | 
        
        | Term 
 
        | Inferior epigastric artery |  | Definition 
 
        | Seen on undersurface of to lower portion of rectus abdominis muscle. Arises from the external iliac artery. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Continuation of a ventral primary ramus of spinal nerves T1-T11. They course from posterior to anterior within the intercostal space, mostly between the internal intercostal muscle and the innermost muscle layer. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Drainage ducts that open at the surface of the nipple |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Nerves that arise from the intercostal and thoracoabdominal nerves approximately at the midaxillary line. They pierce all muscles on the sides of the thorax and abdomen without innervating them. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Vertical line down the center of the anterior abdominal wall. It marks the interdigitation of aponeurotic layers from the abdominal wall muscles (EAO, IAO, TA) |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Paired, vertically oriented muscles located immediately to the left and right of the linea alba, spanning from costal margin to pubic bone. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Tough CT sheath surrounding the rectus abdominis muscles. It has an anterior and a posterior layer. There is no sheath below the arcuate line. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The membranous layer of the superficial fascia of the lower abdominal wall. It is deep to Camper's fascia. Only seen anteriorly below the level of the umbilicus. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A surface anatomy landmark that is a bowed line paralleling the lateral border of the rectus abdominis muscle. |  | 
        |  | 
        
        | Term 
 
        | Superior epigastric artery |  | Definition 
 
        | One of two terminal branches of the internal thoracic artery. It supplies blood to the rectus abdominis. Seen just below and lateral to the xiphoid process. |  | 
        |  | 
        
        | Term 
 
        | Suspensory (Cooper's) Ligaments |  | Definition 
 
        | CT septa that extend from the glandular tissue to the dermis of the skin overlying the breast. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Large impression just superior to the hilar region of the left lung that curves anteriorly to posteriorly. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The continuations of the T7-T11 intercostal nerves beyond the borders of the costal margin and into the anterolateral abdominal wall. They innervate the EAO, IAO, TA and RA muscles. |  | 
        |  | 
        
        | Term 
 
        | Transverse thoracis muscle |  | Definition 
 
        | Located on the inner surface of the sternum and anterior ribs. Represents the innermost layer of the intercostal muscles. |  | 
        |  | 
        
        | Term 
 
        | Transversus abdominis muscle |  | Definition 
 
        | The deepest of the 3 anterolateral abdominal wall muscles. Its muscle fascicles are oriented transversely. Thoracoabdominal nerves course on the surface of this muscle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Transverse connective tissue within the rectus abdominus muscles. Adult remnants of the tendons for the 4-5 individual rectus muscles that formed in the embryo. |  | 
        |  | 
        
        | Term 
 
        | Aortic descending impression |  | Definition 
 
        | Large, vertically oriented concavity on the posterior aspect of the left lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | the uppermost part of each lung; fits into the cupula and extends above the plane of the first rib. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The terminal part of the azygous vein arches superiorly over the root of the right lung, often causing an impression on the lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Very small arteries seen in cross section at the hilum of the lung; they lie immediately posterior to the secondary bronchi. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A subunit of the lung defined by its inflation via a segmental (tertiary) bronchus. Numerous segments per lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | On the left lung below the anterior root: concavity due to left ventricle of heart; on right lung impression is just anterior and below the root due to the right atrium. |  | 
        |  | 
        
        | Term 
 
        | Cardiac notch of left lung |  | Definition 
 
        | Subtle indentation at the anterior border of the left lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The parietal pleura lining the inner surface of the rib cage. Extends posteriorly from the heads of the ribs to the sternum anteriorly. Innervated by somatosensory axons from intercostal nerves. |  | 
        |  | 
        
        | Term 
 
        | Costodiaphragmatic recess |  | Definition 
 
        | The space within the inferior aspect of the pleural cavity located between the costal parietal and diaphragmatic pleurae. The inferior portion of the lung expands into this recess during full inspiration. The upper border of the recess (where lung ends) is at 6th rib at the mid-clavicular ling, 8th rib at mid-axillary line, and 10th rib at paravertebral line. The inferior border is 2 ribs down from each of the above points. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The parietal pleura located at the superior aspect of the pleural cavity. Located in the base of the neck since it extends above the plane of the first rib. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Thin, skeletal muscle that separates the thoracic and abdominal cavities. Dome shaped during quiet respiration with its convex upper surface projecting in to the concavity at the base of each lung. |  | 
        |  | 
        
        | Term 
 
        | Diaphragmatic parietal pleura |  | Definition 
 
        | The parietal pleura lining the superior surface of the diaphragm. It does not cover the central tendon (region) of the diaphragm because this is covered by the parietal pericardium. It receives somatosensory pain innervation via the phrenic nerve. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Located on the medial surface of each lung, the hilus is the somewhat circular area where many structures (bronchi, vessels) enter or exit the lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Often incomplete fissure that is only seen on the anterior surface of the right lung; located approximately at level of the 4th rib or 3rd intercostal space. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Nerves that are essentially continuations of the primary ventral rami of spinal nerves T1-T11. They course within the upper region of an intercostal space between the internal intercostal muscle and the innermost muscular layer (if present). |  | 
        |  | 
        
        | Term 
 
        | Internal thoracic vessels |  | Definition 
 
        | Internal thoracic mammary arteries arise from the subclavian arteries at the level of the thoracic inlet. They course inferiorly just lateral to the borders of the sternum, and they end just below the xiphoid process by dividing into the superior epigastric artery and the musculophrenic artery. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Has two lobes, upper and lower, that are separated by an oblique fissure. The left pulmonary artery is found superior to the left main bronchus in the hilum. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Has three lobes formed by the intersecting horizontal (parallel to 4th rib) and oblique (6th rib) fissure. |  | 
        |  | 
        
        | Term 
 
        | Mediastinal parietal pleura |  | Definition 
 
        | Parietal pleura that lines the medial surface of the pleural cavity. It begins anteriorly just deep to the sternum, courses posteriorly toward the root of the lung, ending posteriorly at the sides of the thoracic vertebral bodies where it is continuous with the costal parietal pleura. REceives somatosensory pain innervation from the phrenic nerve. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Present on both lungs and approximately parallel the 6th ribs, especially laterally and anteriorly. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The outer layer of the pleural sac that surrounds each lung. Its outer surface is connected to the inner surface of the rib cage via endothoracic fascia. Its inner surface is very smooth and shiny due to it being made of mesothelial cells. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A pair of long nerves that arise in the neck (from C3-5) and pass inferiorly through the thorax to reach the diaphragm. It passes anterior to the root of the lung, between the mediastinal parietal pleura and the fibrous pericardium. It does not pass through the pleural cavity. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | A two-layered sac that encloses each lung. Serous fluid is inside the sac and this facilitates respiration. There are no opening in the cavity, but rather the lung invaginates the pleural cavity during development like a fist being pushed into a balloon. |  | 
        |  | 
        
        | Term 
 
        | Primary (main stem) bronchi |  | Definition 
 
        | The first two branches of the trachea. The right is more vertical and shorter than the left. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Right and left branches off the pulmonary trunk that pass through the hilus of each lung, continuing to divide into smaller and smaller branches down to the level of the alveolar sacs. They convey relatively unoxygenated blood to the alveoli for gas exchange. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Typically four veins that exit the hilus of each lung and enter the left atrium of the heart. They convey highly oxygenated blood from the lung alveoli to the left atrium. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The collection of structures that pass through the hilum of the lung. The root includes pulmonary arteries, pulmonary veins, bronchial arteries and veins, lymphatic vessels and autonomic nerves. |  | 
        |  | 
        
        | Term 
 
        | Secondary (lobar) bronchi |  | Definition 
 
        | Second order branching of the trachea, or the branches that immediately follow the primary main stem bronchi. There are three lobar bronchi on the right since there are 3 lobes, 2 on the left. |  | 
        |  | 
        
        | Term 
 
        | Superior epigastric artery |  | Definition 
 
        | Terminal branch of the internal thoracic artery that arises just below the xiphoid process and anastomose with the inferior epigastric arteries. |  | 
        |  | 
        
        | Term 
 
        | Tertiary (segmental) bronchi |  | Definition 
 
        | Third stage of branching off of the trachea. Each secondary bronchus divides further into multiple tertiary bronchi, and each tertiary bronchus supplies air to a bronchopulmonary segment. |  | 
        |  | 
        
        | Term 
 
        | Transverse thoracis muscle |  | Definition 
 
        | Innermost layer of the intercostal muscles, obliquely positioned muscles on the inner surface of the lower sternum and adjacent ribs. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The serous membrane that is closely applied to the surface of each lung, dipping down into each fissure. It is continuous with the parietal pleura at the hilar region of each lung. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | deeply positioned triangular muscle that attaches to the 1st rib. It lies just lateral and deep to the internal jugular vein. The phrenic nerve lies on its anterior surface. The subclavian vein lies anterior and the subclavian artery lies posterior to the muscle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Continuation of the ascending aorta that curves posteriorly to become the descending aorta. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Uppermost part of each lung. It projects above the first rib which places it in the root of the neck. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The outflow track for the left ventricle. Sits between the SVC and the pulmonary trunk. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Most of the azygous vein is seen in the posterior mediastinum. The azygos arch curves anteriorly over the root of the lung to become a tributary to the SVC. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Large (first) branch off of the aorta. Ascends up and to the right to branch into the right common carotid and right subclavian arteries. |  | 
        |  | 
        
        | Term 
 
        | Brachiocephalic vein (left) |  | Definition 
 
        | Begins at the junction of the left IJV and left subclavian vein. It courses obliquely across the superior mediastinum to end as a tributary to the SVC. |  | 
        |  | 
        
        | Term 
 
        | Brachiocephalic vein (right) |  | Definition 
 
        | Begins at the junction of the right internal jugular and subclavian veins. Terminates as a tributary to the SVC. |  | 
        |  | 
        
        | Term 
 
        | Common carotid artery (left) |  | Definition 
 
        | Posterior most branch off of the aortic arch. It ascends thru the superior thoracic aperture to ascend vertically in the neck, paralleling the IJV on its medial side. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Branch off of the brachiocephalic trunk that ascends vertically up the neck, parallel with the IJV on its medial side. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Continuation of the posterior end of the aortic arch; often called the thoracic aorta. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Vertical muscular tube that descends through the thorax in a position that is first immediately posterior to the trachea and then anterior to the thoracic aorta as it nears the diaphragm. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Veins that start at the base of the skull, descend vertically down the neck immediately lateral to the common carotid arteries, and end as tributaries to the brachiocephalic veins. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The vertically coursing nerve seen on the anterior surface of the scalene muscle. Originates from C3,C4,C5 ventral rami of spinal nerves. |  | 
        |  | 
        
        | Term 
 
        | Recurrent laryngeal nerve, left |  | Definition 
 
        | Arises from the left vagus nerve and immediately courses medially around the ligamentum arteriosum and under the aortic arch; it then ascends back into the neck lying in a groove between the trachea and esophagus. |  | 
        |  | 
        
        | Term 
 
        | Recurrent laryngeal nerve, right |  | Definition 
 
        | Arises from the right vagus nerve at the beginning of the right subclavian artery; it turns medially and superiorly to ascend in the neck lying between the trachea and the esophagus |  | 
        |  | 
        
        | Term 
 
        | Subclavian vein, right/left |  | Definition 
 
        | Begins at the lateral margin of the 1st rib, courses horizontally and medially to end as tributary to the right/left brachiocephalic vein. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Begins at the junction of the right and left brachiocephalic veins, descends vertically just to the right of the ascending aorta and ends by entering the upper region of the right atrium. It receives the azygos as a tributary. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | in the root of the neck on the left side only. It is seen as it arches up and laterally through the superior thoracic aperture behind the carotid sheath contents to end near the junction of the IJV and left subclavian vein. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The first structure deep to the manubrium and superficial to the great vessels. In older individuals it is fatty. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Large hollow tube that lies just posterior to the aortic arch and brachiocephalic trunk. It lies anterior to the esophagus. It ends by bifurcating into right and left main stem bronchi. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | one of 12 cranial nerves that arises from the brain stem, descends down the neck within the carotid sheath to enter the thorax. Both the right and left vagus nerves pass posterior to the root of the lung. |  | 
        |  | 
        
        | Term 
 
        | Anterior interventricular artery (LAD) |  | Definition 
 
        | Arises from the left coronary artery and descends down the anterior interventricular sulcus. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Tricuspid valve at the beginning of the ascending aorta. Open during ventricular systole and closes during diastole to preven backflow of blood into the ventricle |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Conical, tapered inferior aspect of the left ventricle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Located between the SVC and the pulmonary trunk; it is the outflow tract of the left ventricle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Part of the conduction system located just below the membranous IV septum. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Located on the interatrial septum just above the opening of the coronary sinus into the right atrium. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Network of autonomic nerves located just inferior to the aortic arch and anterior to the trachea. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Tough, string-like muscles between the valve cusps and the papillary muscles in both ventricles. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Arises from the left coronary artery and courses around the left margin of the heart in the coronary sulchus |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Elongated venous channel located on posterior side of the heart in the coronary sulcus; it receives as tributaries the great cardiac vein and the middle cardiac vein. It enters the right atrium. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Groove on the surface of the heart around the circumference of the heart between the atria and the ventricles. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | a vertical ridge in the right atrium that marks the junction of the smooth-walled part of the atrium with the rough, pectinate part. Pectinate muscles extend like teeth of a comb in a direction perpendicular to the atria and ventricles. |  | 
        |  | 
        
        | Term 
 
        | Diaphragmatic surface of the heart |  | Definition 
 
        | Faces somewhat posteriorly and has part of the posterior aspects of the right and left ventricles. Good landmark for quickly realizing one is looking at the posterior side of the heart. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Outermost layer of the connective tissue of the pericardium; fused inferiorly with the central tendon of the diaphragm. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Thumb sized depression on the interatrial septum within the right atrium. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Courses with the LAD artery and then turns left at the coronary sulcus to enter the coronary sinus |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Intrathoracic portion is very short as the vein pierces the diaphragm and immediately enters the inferior aspect of the right atrium |  | 
        |  | 
        
        | Term 
 
        | Infundibulum (conus arteriosus) |  | Definition 
 
        | Funnel-shaped outflow track for the right ventricle. It is located in the right ventricle just below the opening of the pulmonary trunk. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Partition between the two atria. |  | 
        |  | 
        
        | Term 
 
        | Interventricular septum (membranous part) |  | Definition 
 
        | Small, membranous partition located at the superior end of the muscular IV septum. It partially separates the two ventricles, as well as separating the right atrium from the left ventricle. |  | 
        |  | 
        
        | Term 
 
        | Interventricular septum, muscular part |  | Definition 
 
        | Large, thick muscle that separates the two ventricles; it is slightly bowed to the right due to the higher pressure in the left ventricle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Groove on both the anterior and posterior surfaces of the heart between the right and left ventricles; the muscular part of the IV septum lies deep to this groove. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Posterior most chamber that lies just anterior to the esophagus; receives 4 pulmonary veins |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Small appendage attached to the left atrium; lined with pectinate muscle. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | The left division of the AV bundle that course down the left side of the IV septum (muscular) deep to the endocardium. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | Arises from the ascending aorta and descends towards anterior interventricular sulcus; it ends by dividing into the LAD and circumflex branches. |  | 
        |  | 
        
        | Term 
 
        | Left recurrent laryngeal nerve |  | Definition 
 
        | Branch of the vagus that hooks around the ligamentum arteriosum at the undersurface of the aortic arch; it ascends vertically to the larynx by coursing in the tracheoesophageal groove. |  | 
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        | Term 
 | Definition 
 
        | Located on the left side of the heart shadow and makes up the obtuse margin of the heart. Its inferior aspect is conical and is the apex of the heart. It is adjacent to the left lung. |  | 
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        | Term 
 | Definition 
 
        | A half-inch long stout ligament that spans between the undersurface of the aortic arch and the left pulmonary artery. Left recurrent laryngeal nerve hooks around this ligament. Remnant of the embryonic ductus arteriosus. |  | 
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        | Term 
 | Definition 
 
        | Courses with the posterior interventricular artery on the back of the heart. |  | 
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        | Term 
 | Definition 
 
        | Two cusps that comprise the mitral valve. seen best via the left ventricle. |  | 
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        | Term 
 | Definition 
 
        | Pillars of myocardium that arise from the interior walls of both ventricles and extend upward toward the valves. Chordae tendinae attach to their tips. |  | 
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        | Term 
 
        | Parietal serous pericardium |  | Definition 
 
        | outer layer of the serous pericardium; it is firmly attached to the inner surface of the fibrous pericardium |  | 
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        | Term 
 | Definition 
 
        | A defect in the interatrial septum formed during development; it is located within the upper region of the fossa ovalis. |  | 
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        | Term 
 | Definition 
 
        | Bumpy, irregular surface found within both auricles, as well as a large portion of the right atrium. |  | 
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        | Term 
 
        | Posterior interventricular artery |  | Definition 
 
        | Located int he posterior interventricular groove; usually arises from the right coronary artery, but in 15% of cases it arise from the circumflex branch. |  | 
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        | Term 
 | Definition 
 
        | Located to the left of the ascending aorta, it is the outflow tract for the right ventricle. |  | 
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        | Term 
 | Definition 
 
        | Four veins that enter the left atrium, located on the posterior aspect of the heart. |  | 
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        | Term 
 | Definition 
 
        | Located at the beginning of the pulmonary trunk, has three semilunar cusps that are open during ventricular systole and closed during diastole. |  | 
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        | Term 
 | Definition 
 
        | The chamber of the heart that forms the right margin of the heart shadow. It is adjacent to the right lung. The SVC and IVC are landmarks to this chamber |  | 
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        | Term 
 | Definition 
 
        | Small appendage attached to the right atrium; it is lined with pectinate muscle |  | 
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        | Term 
 | Definition 
 
        | Division of the AV bundle that travels down the right side of the IV septum (muscular) deep to the endocardium |  | 
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        | Term 
 | Definition 
 
        | Arises from the ascending aorta and descends down the anterior aspect of the heart in the coronary sulcus; at the acute margin of the heart, it turns onto the posterior aspect of the heart. |  | 
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        | Term 
 | Definition 
 
        | Anterior most chamber of the heart. Located between the right atrium and the left ventricle. |  | 
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        | Term 
 | Definition 
 
        | Located at the junction of the SVC and the base of the right auricle |  | 
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        | Term 
 
        | Septomarginal trabecula (moderator band) |  | Definition 
 
        | In the right ventricle only. Bar of muscle that spans from the IV septum (muscular part) to the base of the anterior papillary muscle |  | 
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        | Term 
 | Definition 
 
        | Analogous to the pleural cavity in having parietal and visceral layers. A sac lined internally by a thin layer of mesothelial cells that surrounds the heart; it contains a small amount of serous fluid that minimizes friction during heart contractions. |  | 
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        | Term 
 | Definition 
 
        | Vertically coursing vein that is located to the right of the ascending aorta. enters right atrium from a superior aspect. Formed by convergence of the brachiocephalic veins. |  | 
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        | Term 
 | Definition 
 
        | Bumpy, irregular pattern of muscle lining the inner walls of both ventricles. |  | 
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        | Term 
 | Definition 
 
        | Three cusps that are part of the tricuspid valve, which separates the right atrium and ventricle. Seen best via the right ventricle |  | 
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        | Term 
 
        | Visceral serous pericardium (epicardium) |  | Definition 
 
        | This is the layer of pericardium that intimately covers the surface of the heart and extends up onto the great vessels. |  | 
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        | Term 
 | Definition 
 
        | Opening in the diaphragm through which the the thoracic aorta passes into the abdomen. Located at the level of T12 vertebra. |  | 
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        | Term 
 | Definition 
 
        | Located posteriorly against the thoracic vertebral bodies on the right side only. Vertical venous channel that ascends from the diaphragm to the root of the lung, where it arches above the root to enter the SVC. Its tributaries are the posterior intercostal veins. |  | 
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        | Term 
 | Definition 
 
        | Network of autonomic nerves (symp and parasymp) located just beneatyh the aortic arch and just anterior to the tracheal bifurcation. |  | 
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        | Term 
 | Definition 
 
        | Cartilage ridge located internally at the bifurcation of the trachea |  | 
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        | Term 
 | Definition 
 
        | Opening in the diaphragm where the inferior vena cava passes from the abdomen to the thorax. Located at the level of the T8 vertebra. |  | 
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        | Term 
 | Definition 
 
        | Two short nerves that span between each ventral ramus of each intercostal nerve and the thoracic sympathetic trunk. |  | 
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        | Term 
 | Definition 
 
        | Opening through which the esophagus and vagal trunks pass to enter the abdomen. Located at the T10 vertebral level. |  | 
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        | Term 
 | Definition 
 
        | Network of autonomic nerves (symp and parasymp) that surrounds the lower aspect of the esophagus |  | 
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        | Term 
 | Definition 
 
        | Muscular tube that spans the length of the thorax. Located posterior to trachea and anterior to the lower portion of the thoracic aorta. |  | 
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        | Term 
 
        | Greater thoracic splanchnic nerve |  | Definition 
 
        | Branch off the thoracic sympathetic trunk that descends adjacent to the lower thoracic vertebral bodies. From its origin it angles anteriorly and inferiorly to the diaphragm. contains symp/pre and viscersensory pain axons. |  | 
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        | Term 
 | Definition 
 
        | Direct continuation of the primary ventral rami of T1-T11. Located in the upper region of each intercostal space just inferior to the posterior intercostal artery. |  | 
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        | Term 
 | Definition 
 
        | Begins at the bifurcation of the trachea and extends toward the left lung. It is longer, more horizontal, and narrower than the right main stem bronchus. |  | 
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        | Term 
 
        | Posterior intercostal artery |  | Definition 
 
        | Branch off of the thoracic aorta that courses in the upper region of an intercostal space just superior to the intercostal nerve. Anastomose with anterior intercostal arteries. |  | 
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        | Term 
 
        | Posterior intercostal vein |  | Definition 
 
        | Located in upper region of each intercostal space just superior to the intercostal artery. They are tributaries to the azygos vein on the right and to the hemiazygos vein on the left. |  | 
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        | Term 
 | Definition 
 
        | Located at the bifurcation of the trachea and courses obliquely toward the right lung. It is shorter, more vertical and larger diameter than the left main bronchus. |  | 
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        | Term 
 | Definition 
 
        | Small ganglia spaced along the length of the thoracic sympathetic trunk, approx one per intercostal space. They contain the cell bodies for the postganglionic sympathetic nerves. |  | 
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        | Term 
 | Definition 
 
        | Largest lymph channel in the body located posteriorly adjacent to the thoracic vertebrae between the azygos vein and the aorta. It courses vertically from the diaphragm to the level of thracheal bifurcation where it begins to turn towards the left, ultimately passing into the root of the neck on the left side to end in the venous junction of the IJV and subclavian vein. |  | 
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        | Term 
 | Definition 
 
        | Located at the level of the inferior aspect of the aortic arch. |  | 
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        | Term 
 
        | Tracheobronchial lymph nodes |  | Definition 
 
        | Located at the bifurcation of the trachea. |  | 
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        | Term 
 | Definition 
 
        | Arises distally from the esophageal plexus on the anterior surface of the esophagus. It passes through esophageal hiatus with the esophagus to reach the abdomen. |  | 
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        | Term 
 | Definition 
 
        | It courses adjacent to the lateral side of the aortic arch and then passes posterior to the left root of the lung. It seemingly ends at the sophageal plexus, but its preganglionic parasympathetic axons continue to course through the plexus to the vagal trunks. |  | 
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        | Term 
 | Definition 
 
        | It courses adjacent to the right side of the trachea and then passes posterior to the root of the right lung. It seemingly ends at the esophageal plexus but its para/pre axons continue to course through the plexus to the vagal trunks. |  | 
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