Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Related Posts. We highly encourage our visitors to purch ase orig inal books from the respected publishers. If someone with copyrights wants us to remove this content, please contact us. Moreover Medstudentscorner. If you feel that we have violated your copyrights, then please contact us immediately. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.
The plexuses contain postganglionic sympathetic fibers from the sympathetic trunks that innervate the smooth muscle of the bronchial tree, pulmonary vessels, and glands of the bronchial tree.
Sympathetic fibers are bronchodilators, vasoconstrictors, and inhibit glandular secretion. The plexuses contain preganglionic parasympathetic fibers from the vagus nerve CN X , small parasympathetic ganglia, and postganglionic parasympathetic nerves that innervate the smooth muscle of the bronchial tree, pulmonary vessels, and glands of the bronchial tree. Parasympathetic fibers are bronchoconstrictors, vasodilators, and secretomotor to the glands. Pneumonia: a bacterial or viral infection of the lung that can lead to widespread systemic infection and lung collapse.
Pneumonia is frequently confined to a single lobe of one lung and is called lobar pneumonia. It can be clearly seen circumscribed to one lobe in a chest radiograph. The entry of air into a pleural cavity because of a penetrating wound or a fractured rib is called a pneumothorax and results in partial or total collapse of the lung. The escape of fluid into the pleural cavity pleural effusion is called hydrothorax; if the fluid is blood, the condition is known as a hemothorax, and if it is chyle from the thoracic duct, it is called a chylothorax.
Inflammation of the pleurae is called pleuritis or pleurisy; resulting friction between the two pleurae pleural rub is very painful and can be heard with a stethoscope.
The inflamed pleurae may adhere to each other pleural adhesion Squamous cell or oat cell carcinoma is a common cancer of the lung, usually caused by smoking, that may be indicated by a persistent cough or spitting of blood hemoptysis. The fibrous outer layer of the pericardium the fibrous pericardium consists of dense connective tissue. The fibrous pericardium is attached to the central tendon of the diaphragm by the pericardiacophrenic ligament.
It blends with the tunica adventitia of the vessels entering and leaving the heart. It has ligamentous attachments to the sternum It is thus affected by movements of the heart, the great vessels, the sternum, and the diaphragm. It protects the heart against overfilling because it is fibrous and unyielding The inner layer of the pericardium is a serous membrane that lines the fibrous pericardium: the serous pericardium, also called the parietal pericardium.
The serous pericardium is a mesothelial layer that reflects onto the roots of the great vessels and is continuous over the external surface of the heart, where it is called the epicardium or visceral pericardium. Between the serous pericardium parietal pericardium and the epicardium visceral pericardium is a potential space: the pericardial cavity.
The pericardial cavity normally contains a thin film of fluid that allows the two layers to move over each other without friction or rubbing.
There are two sinuses within the pericardial cavity: the transverse sinus and the oblique sinus. The transverse pericardial sinus runs transversely in the pericardial sac between the origins of the great vessels: posterior to the ascending aorta and pulmonary trunk and anterior to the superior vena cava.
The oblique pericardial sinus is a wide recess in the posterior wall of the pericardial sac bounded laterally by the entrances of the pulmonary veins and inferiorly by the orifice of the inferior vena cava. Blood supply to the layers of the pericardium is mainly from the pericardiacophrenic vessels, from the internal thoracic arteries and veins. The nerve supply to the pericardium is from the phrenic nerves, primarily sensory fibers for pain, and the sympathetic trunks vasomotor.
The right side of the heart receives poorly oxygenated blood from the superior and inferior vena cava and pumps it to the lungs for oxygenation. The left side of the heart receives oxygenated blood from the lungs via the pulmonary veins and pumps it to the body via the aorta and its branches.
The heart consists of four chambers: the right and left atria and the right and left ventricles. The functions of the fibrous skeleton are: Maintains the patency of the atrioventricular valves Provides a fixed site for the attachment of the leaflets and cusps of the valves Provides a fixed site for the attachments of the cardiac muscle fibers Insulates the atria from the ventricles so that they can contract independently The cardiac cycle consists of Relaxation of the ventricles diastole followed by Contraction of the ventricles diastole Heart sounds heard with a stethoscope: "lub"-blood from the atria fills the ventricles "dub"-ventricles contract and push blood out of the heart Orientation of the Heart: Border and Surfaces [Plate , Heart: Base and Diaphragmatic Surfaces] The heart lies obliquely between the 3rd and the 5th ribs, mainly on the left side of the midline of the thorax, but with roughly a third of it slightly to the right.
The base of the heart is its posterior surface, which is the left atrium. The apex of the heart is formed from the most inferior and lateral part of the left ventricle and lies beneath the left 5th intercostal space at approximately the midclavicular line. The anterior wall is ridged with the pectinate muscles. The smooth and rough parts of the right atrium are separated internally by a smooth ridge, the crista terminalis, which presents externally as shallow groove, the sulcus terminalis.
The superior vena cava opens into the superior aspect of the right atrium. The inferior vena cava opens into the inferior part, in a direct line with the superior vena cava. An interatrial septum separates the right and left atria. An oval depression in the interatrial septum, the fossa ovalis, represents the fetal foramen ovale and its valve.
Aright atrioventricular AV orifice opens into the right ventricle Right ventricle The right ventricle is situated in front and to the left of the right AV orifice. The interior has prominent muscular ridges, the trabeculae carnea. The tricuspid valve or right AV valve usually consists of three leaflets.
The bases of the leaflets or cusps are attached to the fibrous ring around the orifice. The free edge of each leaflet is attached to two of the three papillary muscles by tendinous cords chordae tendinea.
The papillary muscles are three in number: septal, anterior and posterior. These muscles contract before the ventricle itself contracts, tightening the chordae tendinea and drawing the cusps of the valve together to prevent backflow of blood into the right atrium. The septomarginal trabecula, or moderator band, is a free band of muscle extending from the interventricular septum to the anterior wall of the ventricle, and it contains Purkinje fibers from the right bundle branch see conducting system.
The outflow tract of the ventricle is separated from the inflow tract by a smooth crest, the supraventricular crest. The outflow tract, or conus arteriosus, is smooth walled and leads to the pulmonary trunk and the valve that guards its orifice, the pulmonary valve.
It has a smooth walled portion from the developmental incorporation of a portion of the pulmonary veins and an auricular appendage which is ridged with pectinate muscles and which was the primitive left atrium. Four pulmonary veins empty into the left atrium.
The interatrial septum is nearly transverse, sloping posteriorly and to the right The left atrioventricular orifice leads to the left ventricle.
Left Ventricle page page The left ventricle is nearly twice as thick as the right ventricle, since it performs more work to circulate blood to the body. It has a conical cavity, the apex of which is the apex of the heart.
Its walls are lined with trabeculae carnea, which are more numerous and not as massive as the ones in the right ventricle. It contains only two papillary muscles, anterior and posterior, which both attach to the two leaflets of the left atrioventricular, or mitral, valve via chordae tendinea. These muscles contract before the ventricle itself contracts, tightening the chordae tendinea and drawing the cusps of the valve together to prevent backflow of blood into the left atrium.
The aortic orifice is located posteriorly and superiorly and, like the pulmonary orifice, is surrounded by a fibrous ring to which the three cusps of the aortic valve are attached.
The aortic valve has three cusps, which open like pockets to catch blood that backflows from the aorta during ventricular diastole. There are dilations in the wall of the aorta beneath each cusp: the aortic sinuses.
The right coronary artery originates in the right aortic sinus, while the left coronary artery originates in the left aortic sinus. They arise from the corresponding aortic sinuses, just distal to the origin of the aortic valve. The left coronary artery passes between the left auricle and the pulmonary trunk. Its main branches are Acircumflex branch, which reaches the posterior surface of the heart by traveling in the atrioventricular groove around the left side of the heart In slightly less than half of all people, a sinoatrial SA nodal branch from the circumflex branch will supply the SAnode.
An anterior interventricular branch left anterior descending artery or LAD , which descends in the anterior interventricular groove to the apex of the heart and then anastomoses with the posterior interventricular artery. The right coronary artery runs in the atrioventricular groove to the right and around to the posterior surface of the heart. It gives rise to The SAnodal branch near its origin in most people Aright marginal branch to the right margin of the heart An AV nodal branch to the atrioventricular node, as the junction of the septa and four chambers of the heart on the posterior side of the heart Aposterior interventricular branch that runs in the posterior interventricular groove.
It consists of The sinoatrial node SAnode , located at the superior end of the sulcus terminalis of the right atrium, near the entrance of the superior vena cava The SAnode is the so-called pacemaker of the heart, from which impulses for contraction are initiated and spread through the musculature of both atria.
Fibers from the cardiac plexus supply the SAnode. Sympathetic innervation accelerates the rate and force of contraction of heart muscle. Parasympathetic stimulation slows down the rate and force of contraction of heart muscle. Signal from the SAnode is propagated by the cardiac muscle to the AV node. The AV node is located near the inferior end of the interatrial septum posteriorly, near the septal cusp of the tricuspid valve.
The AV bundle carries the signal from the AV node through the fibrous skeleton of the heart and the membranous interventricular septum. It divides into right and left bundles that pass on either side of the muscular interventricular septum.
The fibers of the right and left bundles Purkinje fibers spread into the walls and papillary muscles of the ventricles. Purkinje fibers from the right bundle innervate the anterior papillary muscle of the right ventricle via the septomarginal trabecula or moderator band, to coordinate the timing of the contraction of the papillary muscles.
Heart Sounds Clinicians need to listen to valve sounds. Blood carries sound in the direction of its flow, so valve sounds are best heard auscultated directly superficial to their location or at the end of a line of blood flow through the valve.
Similarly, stab wounds to the heart can result in the leakage of blood into the pericardial cavity. As excess blood or fluid accumulates in the pericardial cavity, the heart becomes increasingly inhibited from expanding as it beats, and blood flow to the ventricles is impeded.
This situation is called cardiac tamponade and is a potentially lethal condition. Symptoms include distension of neck veins and a collapsing pulse, i. Pericardiocentesis Pericardiocentesis or drainage of fluid from the pericardial cavity is necessary to relieve cardiac tamponade.
Awide bore needle is inserted into the 5th or 6th intercostal space adjacent to the sternum but not too close because of the presence of the internal thoracic vessels. This approach can be made because of the cardiac notch in the left lung and left parietal pleura, leaving the pericardial sac exposed. Aneedle can also be inserted into the infrasternal angle, again being careful of the internal thoracic artery and its branches, and passed superiorly and posteriorly to reach the pericardial sac.
Cardiac Referred Pain While the heart is generally insensitive to various stimuli, ischemia lack of oxygen and the resulting accumulation of metabolic products registers as pain, typically in the left pectoral and substernal regions and over the medial aspect of the left shoulder and upper limb.
The axons of visceral afferent fibers from the heart typically enter spinal cord segments from T1 through T4 or 5 on the left side. General sensory fibers from these areas also enter the same spinal cord segments Cardiac Bypass Graft CABG In this surgery, the patient has a blood vessel grafted into the coronary circulation to bypass an occlusion in one of the coronary arteries or its branches. In the past, the saphenous vein was commonly used in the bypass graft, because it is easily obtained from the lower limb and has lengthy sections without valves or branches.
The internal thoracic artery is more frequently used to shunt blood from the aorta to branches of the coronary arteries beyond the occlusion. This restores normal blood flow to the part of the heart distal to the blockage. It can be a result of any one of several developmental anomalies, such as failure of the embryonic endocardial cushions, which form part of the septum, to fuse.
Aleft to right flow of blood occurs with this defect because of the strength of contraction of the left ventricle. This increases the blood flow through the pulmonary trunk to the lungs and results in pulmonary hypertension increased blood pressure and an enlarged heart.
This condition is potentially fatal if not corrected. Pathologies of the Aorta Aneurysms of the ascending aorta An aortic aneurysm is an enlargement of a weakened area of the aorta, in this case in the distal part of the ascending aorta. Ascending aortic aneurysms frequently cause dilation and leakage of the aortic valve, resulting in shortness of breath or even heart failure.
Aortic dissection is a tearing of the internal wall of the aorta, with subsequent bleeding into the wall, as the result of an aneurysm, atherosclerosis, or high blood pressure. Coarctation of aorta is a birth defect in which the aorta is narrowed somewhere along its length, most commonly just past the point where the subclavian artery arises.
This results in low blood pressure in branches of the aorta distal to the narrowing and high blood pressure in branches between the narrowing and the heart. People with this condition often have high blood pressure in the upper body and arms or one arm and low blood pressure in the lower body and legs. The intercostal arteries can become enlarged, since the anastomoses of the anterior intercostals from the internal thoracic artery with the posterior intercostals can circumvent the narrowing.
Aortic coarctation is more common in some genetic conditions such as Turner syndrome but also can be associated with congenital abranditemities of the aortic valve such as a bicuspid aortic valve.
Valvular Insufficiencies The mitral valve is the heart valve most frequently affected by disease. It can be caused by endocarditis, myocarditis, rheumatic heart disease, or lupus erythematosus, or can result from a developmental abranditemity.
The diseased mitral valve allows reversal of blood flow from the left ventricle to the left atrium mitral regurgitation. It is characterized by a high pitched murmur, loudest over the apex of the heart. Narrowing of the pulmonary valve stenosis is caused by fusion of the valve cusps.
It can result from a developmental abranditemity or diseases such as rheumatic fever or endocarditis. Stretches from the thoracic inlet to the diaphragm and from the sternum to the bodies of the thoracic vertebrae posteriorly. Its contents include the heart, trachea, esophagus, great vessels of the heart, lymph nodes, nerves, and fat.
Superior mediastinum contains the superior vena cava arch of the aorta and its branches trachea phrenic nerves thoracic duct esophagus vagus nerves left recurrent laryngeal nerve thymus Inferior mediastinum is subdivided into anterior mediastinum middle mediastinum posterior mediastinum The anterior mediastinum contains fat and the remnants of the thymus gland The middle mediastinum contains the heart surrounded by the pericardium and the roots of the great vessels.
Thymus gland plays a central role in the development of the immune system lies posterior to the manubrium receives blood from the internal thoracic and anterior intercostal arteries is gradually replace by adipose tissue after puberty b.
Heart and pericardial sac Section Thorax-Heart c. Superior vena cava Formed by the union of two brachiocephalic veins Returns blood to the heart from all structures above the diaphragm except the heart and lungs Descends vertically and terminates in the right atrium Lies to the right of the ascending aorta and to the left of the right phrenic nerve Receives azygous veins before piercing fibrous pericardium d.
Brachiocephalic veins Are formed in the root of the neck posterior to the sternoclavicular joints by union of the internal jugular and subclavian veins. Right brachiocephalic vein receives lymph from the right lymph duct. Left brachiocephalic vein is twice as long as the right runs obliquely down and behind the manubrium crosses the roots of the three major branches of the aorta receives lymph from the thoracic duct e.
Aorta Ascending begins at the aortic orifice ascends to the 2nd right sternocostal joint Arch Begins at the 2nd right sternocostal joint and arches superiorly and to the left Anterior to the right pulmonary artery and bifurcation of the trachea Passes over the root of the right lung Ends at the body of the T4 vertebra Descending thoracic begins at the body of T4 vertebra descends on the left side of the bodies of T vertebrae, posterior to the root of the left lung and the pericardium enters the abdomen through the aortic hiatus at the T12 vertebral body has a number of branches: bronchial pericardial twigs superior phrenic 1 pair esophageal 2 posterior intercostal 9 pairs subcostal 1 pair f.
Vascular supply arterial: esophageal branches of the thoracic aorta venous: azygos, hemiazygos and accessory azygos veins h.
Azygos venous system Drains blood from the back and thoracoabdominal walls Is highly variable Is composed of an unpaired azygos vein and its main tributary, the hemiazygos vein. Phrenic nerves Supply motor and sensory fibers to the diaphragm Enter the superior mediastinum between the subclavian artery and brachiocephalic vein on either side Pass anterior to the roots of the lungs, unlike the vagus nerve The right phrenic nerve descends on the right side of the inferior vena cava to the diaphragm The left phrenic nerve crosses the arch of the aorta descends anterior to the root of the left lung and along the pericardium over the left atrium and ventricle pierces the diaphragm to the left of the pericardium 1.
Surgery, injury, or disease affecting the contents of superior mediastinum can damage either or both recurrent laryngeal nerves, reducing the voice to a hoarse whisper. The left recurrent laryngeal nerve passes beneath the arch of the aorta and ascends to the neck between the trachea and the esophagus. Bronchogenic or esophageal carcinoma or an aneurysm of the arch of the aorta can thus affect this nerve.
Chylothorax Surgical procedures involving the posterior mediastinum can injure the thoracic duct, which is hard to identify because it has a thin wall and is usually colorless. Injury to the thoracic duct can lead to leakage of lymph into the thoracic cavity at a volume of up to mL per hour. Lymph is called chyle when it is carrying chylomicrons fat droplets from the digestion of food in the gastrointestinal system.
If lymph from the thoracic duct enters the pleural cavity, the resulting condition is called a chylothorax and may require removal by thoracocentesis. Mnemonics Memory Aids To remember the spinal nerve contributions to the phrenic nerve: C3,4,5 keeps the diaphragm alive T8-Site at which inferior vena cava pierces the diaphragm TSite at which esophagus pierces the diaphragm TSite at which aorta pierces the diaphragm Memory Aids SAT for major contents of the superior mediastinum : Superior vena cava, Arch of aorta, and Trachea Turkeys Blow Eggs: Trachea lies Behind the Esophagus page page Memory Aids Relationship of Thoracic Duct to Esophagus and Azygos Vein "The duck lies between two gooses.
Is the largest cavity in the body and is continuous with the pelvic cavity. Lined with parietal peritoneum, a serous membrane Bounded superiorly by the diaphragm Has a concave dome Spleen, liver, part of the stomach, and part of the kidneys lies under the dome and are protected by the lower ribs and costal cartilages.
Lower extent lies in the greater pelvis Between the ala or wings of the ilia Ileum, cecum, and sigmoid colon thus partly protected Anterior and lateral walls composed of muscle Viscera in these areas are more likely to be damaged by blunt force and penetrating injuries. Posterior wall comprised of vertebral column, the lower ribs, and associated muscles Protect the abdominal contents.
Please bear in mind that we do not own copyrights to these books. We highly encourage our visitors to purchase original books from respected publishers. We have provided the link to buy the books from the publisher directly. If someone with copyrights wants us to remove this content, please contact us immediately. Contact Us. If someone with copyrights wants us to remove this content, please contact us.
Moreover Medstudentscorner. If you feel that we have violated your copyrights, then please contact us immediately. Your email address will not be published.
Save my name, email, and website in this browser for the next time I comment. Colors pictures make the book very standard, There are eight edition of the book so far.
New addition is update completely.
0コメント