Thorax

·         The right superior lobar (secondary) bronchus is known as the eparterial (above the artery) bronchus because it passes above the level of the pulmonary artery. All others are the hyparterial bronchi.

·         The cervical pleura (cupula) is the dome of the pleura, projecting into the neck above the neck of the first rib. It is reinforced by Sibson's fascia (suprapleural membrane), which is a thickened portion of the endothoracic fascia, and is attached to the first rib and the transverse process of the seventh cervical vertebra.

·         Visceral pleura (pulmonary pleura) is supplied by bronchial arteries, but its venous blood is drained by pulmonary veins.

·         Pancoast's or superior pulmonary sulcus tumor: is a malignant neoplasm of the lung apex and causes Pancoast's syndrome, which comprises (1) lower trunk brachial plexopathy (which causes severe pain radiating toward the shoulder and along the medial aspect of the arm and atrophy of the muscles of the forearm and hand) and (2) lesions of cervical sympathetic chain ganglia with Horner's syndrome (ptosis, enophthalmos, miosis, anhidrosis, and vasodilation).

·         Superior pulmonary sulcus: is a deep vertical groove in the posterior wall of the thoracic cavity on either side of the vertebral column formed by the posterior curvature of the ribs, lodging the posterior bulky portion of the lung.

·         Bronchopulmonary segment is the anatomic, functional, and surgical unit (subdivision) of the lungs.

Consists of a segmental (tertiary or lobular) bronchus, a segmental branch of the pulmonary artery, and a segment of the lung tissue, surrounded by a delicate connective tissue septum (intersegmental septum). It is drained by the intersegmental part of the pulmonary vein.

Refers to the portion of the lung supplied by each segmental bronchus and segmental artery. The pulmonary veins are said to be intersegmental.

Is clinically important because the intersegmental pulmonary veins form surgical landmarks; thus, a surgeon can remove a bronchopulmonary segment without seriously disrupting the surrounding lung tissue and major blood vessels.

·         Bronchopulmonary segments of right lung

"A PALM Seed Makes Another Little Palm":

· In order from superior to inferior: Apical Posterior Anterior Lateral Medial Superior Medial basal Anterior basal Lateral basal Posterior basal  

·         Bronchial arteries arise from the thoracic aorta; usually there is one artery for the right lung and two for the left lung.

 Bronchial veins Receive blood from the bronchi and empty into the azygos vein on the right and into the accessory hemiazygos vein or the superior intercostal vein on the left.

·         Phrenic Nerve Runs anterior to the root of the lung, whereas the vagus nerve runs posterior to the root of the lung.

·         Transverse sinus is a subdivision of the pericardial sac, lying posterior to the ascending aorta and pulmonary trunk, anterior to the SVC, and superior to the left atrium and the pulmonary veins.

Is of great importance to the cardiac surgeon because, while performing surgery on the aorta or pulmonary artery, a surgeon can pass a finger and make a ligature through the sinus between the arteries and veins, thus stopping the blood circulation with the ligature.

·         Right Atrium Contains the valve (eustachian) of the IVC and the valve (thebesian) of the coronary sinus.

·         Septomarginal trabecula (moderator band) Is an isolated band of trabeculae carneae that forms a bridge between the intraventricular (IV) septum and the base of the anterior papillary muscle of the anterior wall of the right ventricle.

Is called the moderator band for its ability to prevent overdistention of the ventricle and carries the right limb (Purkinje fibers) of the atrioventricular (AV) bundle from the septum to the sternocostal wall of the ventricle.

·         Bicuspid (left AV) valve is called the mitral valve because it is shaped like a bishop's miter.

·         CoArctation of Aorta leads to the development of the important collateral circulation over the thorax, which occurs between the

(1) anterior intercostal branches of the internal thoracic artery and the posterior intercostal arteries

(2) superior epigastric branch of the internal thoracic artery and the interior epigastric artery

(3) superior intercostal branch of the costocervical trunk and the third posterior intercostal artery

 (4) posterior intercostal arteries and the descending scapular (or dorsal scapular) artery, which anastomoses with the suprascapular and circumflex scapular arteries around the scapula.

·         White rami communicantes

Contain preganglionic sympathetic GVE (myelinated) fibers with cell bodies located in the lateral horn (intermediolateral cell column) of the spinal cord and GVA fibers with cell bodies located in the dorsal root ganglia.Are connected to the spinal nerves, limited to the spinal cord segments between T1 and L2.

Gray rami communicantes

Contain postganglionic sympathetic GVE (unmyelinated) fibers that supply the blood vessels, sweat glands, and arrector pili muscles of hair follicles.Are connected to every spinal nerve and contain fibers with cell bodies located in the sympathetic trunk.

·         Specialized cardiac muscle cells, which form the sinoatrial (SA) node, are the pacemakers of the heart. They have the fastest-paced autorhythmicity of all cardiac muscle cells and are located in the wall of the right atrium near the opening of the superior vena cava. Specialized cardiac muscle cells forming the atrioventricular node are also located in the wall of the right atrium, but near the interatrial wall and the opening of the coronary sinus.

·         The upper two posterior intercostal arteries arise from the costocervical trunk; the remaining arteries arise from the descending thoracic aorta. The posterior intercostal arteries anastomose with the anterior intercostal arteries, which arise from the internal thoracic artery.

·         Both the aortic and pulmonary valves have right and left cusps. Remember that the aortic valve has a right and left cusp, but also a posterior cusp, since it is more posterior. In contrast, the pulmonary valve has both right and left cusps and an anterior cusp since it is more anterior (each semilunar valve has the single cusp that the first letter of its name does not have); aortic has posterior; pulmonary has anterior. This also reminds you that the aorta is posterior to the pulmonary trunk. Also remember that the right ventricle is the more anterior chamber and thus gives off a more anterior great vessel. The left ventricle is the more posterior chamber as it gives off its outflow tract. As the great vessels proceed cranially, the aorta ends up on the left as it arches over the split of the pulmonary arteries.

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·         The papillary muscles attach the chordae tendineae to the heart wall and provide an important dynamic mechanism to ensure the competence of the valves. During the ejection phase of ventricular systole, shortening of the papillary muscle compensates for the decrease in the ventricular chamber size and thereby, prevents eversion of the atrioventricular valve leaflets, thereby preventing regurgitation during ventricular systole.

·         The sympathetic cardiac accelerator fibers, affecting primarily the ventricles, are derived from the superior, middle, and inferior cervical ganglia (cervical cardiac nerves) as well as from the upper four thoracic ganglia (thoracic cardiac nerves), whence they converge on the cardiac plexus before reaching the heart.

Having traversed these ganglia, the fibers gain access (via the white rami communicantes) to the upper four thoracic spinal nerves and the corresponding levels of the spinal cord.

Parasympathetic fibers derived from CN X and its recurrent laryngeal branch decrease heart rate and stroke volume through release of acetylcholine, principally in the vicinity of the sinuatrial node.

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