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Anatomy_Gray_500	Anatomy_Gray	Fig. 3.106 A. Close-up view of nipple and surrounding areola of the breast. B. Lateral view of the chest wall of a woman showing the axillary process of the breast. Fig. 3.107 Anterior view of the chest wall of a man showing the locations of various structures related to the TIV/V level. Fig. 3.108 Anterior view of the chest wall of a man showing the locations of different structures in the superior mediastinum as they relate to the skeleton. Right internal jugular veinRight common carotid arteryLeft common carotid arteryLeft subclavian arteryRight subclavian arteryRight pulmonaryarteryLeft pulmonaryarteryPulmonary trunkLeft subclavian veinLeft brachiocephalicveinRight brachiocephalic veinRight subclavian veinLeft internal jugular veinTracheaEsophagusEsophagusArch of aortaAscending aortaThoracic aortaLeft main bronchusRight mainbronchusSuperiorvena cava Fig. 3.109 Anterior view of the chest wall of a man showing skeletal structures and the surface projection of the heart.	Anatomy_Gray. Fig. 3.106 A. Close-up view of nipple and surrounding areola of the breast. B. Lateral view of the chest wall of a woman showing the axillary process of the breast. Fig. 3.107 Anterior view of the chest wall of a man showing the locations of various structures related to the TIV/V level. Fig. 3.108 Anterior view of the chest wall of a man showing the locations of different structures in the superior mediastinum as they relate to the skeleton. Right internal jugular veinRight common carotid arteryLeft common carotid arteryLeft subclavian arteryRight subclavian arteryRight pulmonaryarteryLeft pulmonaryarteryPulmonary trunkLeft subclavian veinLeft brachiocephalicveinRight brachiocephalic veinRight subclavian veinLeft internal jugular veinTracheaEsophagusEsophagusArch of aortaAscending aortaThoracic aortaLeft main bronchusRight mainbronchusSuperiorvena cava Fig. 3.109 Anterior view of the chest wall of a man showing skeletal structures and the surface projection of the heart.
Anatomy_Gray_501	Anatomy_Gray	Fig. 3.109 Anterior view of the chest wall of a man showing skeletal structures and the surface projection of the heart. Fig. 3.110 Anterior view of the chest wall of a man showing skeletal structures, heart, location of the heart valves, and auscultation points. Fig. 3.111 Views of the chest wall showing the surface projections of the lobes and the fissures of the lungs. A. Anterior view in a woman. On the right side, the superior, middle, and inferior lobes are illustrated. On the left side, the superior and inferior lobes are illustrated. B. Posterior view in a woman. On both sides, the superior and inferior lobes are illustrated. The middle lobe on the right side is not visible in this view.	Anatomy_Gray. Fig. 3.109 Anterior view of the chest wall of a man showing skeletal structures and the surface projection of the heart. Fig. 3.110 Anterior view of the chest wall of a man showing skeletal structures, heart, location of the heart valves, and auscultation points. Fig. 3.111 Views of the chest wall showing the surface projections of the lobes and the fissures of the lungs. A. Anterior view in a woman. On the right side, the superior, middle, and inferior lobes are illustrated. On the left side, the superior and inferior lobes are illustrated. B. Posterior view in a woman. On both sides, the superior and inferior lobes are illustrated. The middle lobe on the right side is not visible in this view.
Anatomy_Gray_502	Anatomy_Gray	Fig. 3.112 Views of the chest wall. A. Posterior view in a woman with arms abducted and hands positioned behind her head. On both sides, the superior and inferior lobes of the lungs are illustrated. When the scapula is rotated into this position, the medial border of the scapula parallels the position of the oblique fissure and can be used as a guide for determining the surface projection of the superior and inferior lobes of the lungs. B. Lateral view in a man with his right arm abducted. The superior, middle, and inferior lobes of the right lung are illustrated. The oblique fissure begins posteriorly at the level of the spine of vertebra TIV, passes inferiorly crossing rib IV, the fourth intercostal space, and rib V. It crosses the fifth intercostal space at the midaxillary line and continues anteriorly along the contour of rib VI. The horizontal fissure crosses rib V in the midaxillary space and continues anteriorly, crossing the fourth intercostal space and following the contour	Anatomy_Gray. Fig. 3.112 Views of the chest wall. A. Posterior view in a woman with arms abducted and hands positioned behind her head. On both sides, the superior and inferior lobes of the lungs are illustrated. When the scapula is rotated into this position, the medial border of the scapula parallels the position of the oblique fissure and can be used as a guide for determining the surface projection of the superior and inferior lobes of the lungs. B. Lateral view in a man with his right arm abducted. The superior, middle, and inferior lobes of the right lung are illustrated. The oblique fissure begins posteriorly at the level of the spine of vertebra TIV, passes inferiorly crossing rib IV, the fourth intercostal space, and rib V. It crosses the fifth intercostal space at the midaxillary line and continues anteriorly along the contour of rib VI. The horizontal fissure crosses rib V in the midaxillary space and continues anteriorly, crossing the fourth intercostal space and following the contour
Anatomy_Gray_503	Anatomy_Gray	anteriorly along the contour of rib VI. The horizontal fissure crosses rib V in the midaxillary space and continues anteriorly, crossing the fourth intercostal space and following the contour of rib IV and its costal cartilage to the sternum.	Anatomy_Gray. anteriorly along the contour of rib VI. The horizontal fissure crosses rib V in the midaxillary space and continues anteriorly, crossing the fourth intercostal space and following the contour of rib IV and its costal cartilage to the sternum.
Anatomy_Gray_504	Anatomy_Gray	Fig. 3.113 Views of the chest wall of a man with stethoscope placements for listening to the lobes of the lungs. A. Anterior views. B. Posterior views. Apex of right lungApex of left lungSuperior lobe of right lungSuperior lobe of left lungMiddle lobe of right lungInferior lobe of right lungInferior lobe of left lungABIIIIIIIVVVIVIIVIIIIXXXIXIIIIIIIIIVVVIVIIVIIIIXX Fig. 3.114 A. Normal left coronary artery angiogram. B. Left coronary artery angiogram showing decreased flow due to blockages. C. Mechanism for perceiving heart pain in T1–4 dermatomes. Fig. 3.115 Axial maximum intensity projection (MIP) CT image through the heart. A. Normal anterior interventricular (left anterior descending) artery. B. Stenotic (calcified) anterior interventricular (left anterior descending) artery. eFig. 3.116 Cervical ribs. A. Neck radiograph demonstrating bilateral cervical ribs. B. Coronal computed tomography image showing cervical ribs.	Anatomy_Gray. Fig. 3.113 Views of the chest wall of a man with stethoscope placements for listening to the lobes of the lungs. A. Anterior views. B. Posterior views. Apex of right lungApex of left lungSuperior lobe of right lungSuperior lobe of left lungMiddle lobe of right lungInferior lobe of right lungInferior lobe of left lungABIIIIIIIVVVIVIIVIIIIXXXIXIIIIIIIIIVVVIVIIVIIIIXX Fig. 3.114 A. Normal left coronary artery angiogram. B. Left coronary artery angiogram showing decreased flow due to blockages. C. Mechanism for perceiving heart pain in T1–4 dermatomes. Fig. 3.115 Axial maximum intensity projection (MIP) CT image through the heart. A. Normal anterior interventricular (left anterior descending) artery. B. Stenotic (calcified) anterior interventricular (left anterior descending) artery. eFig. 3.116 Cervical ribs. A. Neck radiograph demonstrating bilateral cervical ribs. B. Coronal computed tomography image showing cervical ribs.
Anatomy_Gray_505	Anatomy_Gray	eFig. 3.116 Cervical ribs. A. Neck radiograph demonstrating bilateral cervical ribs. B. Coronal computed tomography image showing cervical ribs. eFig. 3.117 Chest radiograph demonstrating an air/fluid level in the pleural cavity. eFig. 3.118 Chest radiograph of an individual with a pacemaker. The pacemaker wires (2) can be seen traveling through the venous system to the heart where one ends in the right atrium and the other ends in the right ventricle. eFig. 3.119 Chest radiograph demonstrating translucent notches along the inferior border of ribs III to VI. eFig. 3.120 A. CT image of aortic dissection. B. Normal aorta (left) and an aortic dissection (right). The line in the right figure indicates the plane of the CT scan shown in A. The true lumen surroundedby the collapsed intima and mediaCollapsed intima and mediaABThe false lumenThe false lumenAscendingaortaThoracic aortaThe true lumenEntrypointReturnpoint eFig. 3.121 Chest radiograph showing left upper lobe infection.	Anatomy_Gray. eFig. 3.116 Cervical ribs. A. Neck radiograph demonstrating bilateral cervical ribs. B. Coronal computed tomography image showing cervical ribs. eFig. 3.117 Chest radiograph demonstrating an air/fluid level in the pleural cavity. eFig. 3.118 Chest radiograph of an individual with a pacemaker. The pacemaker wires (2) can be seen traveling through the venous system to the heart where one ends in the right atrium and the other ends in the right ventricle. eFig. 3.119 Chest radiograph demonstrating translucent notches along the inferior border of ribs III to VI. eFig. 3.120 A. CT image of aortic dissection. B. Normal aorta (left) and an aortic dissection (right). The line in the right figure indicates the plane of the CT scan shown in A. The true lumen surroundedby the collapsed intima and mediaCollapsed intima and mediaABThe false lumenThe false lumenAscendingaortaThoracic aortaThe true lumenEntrypointReturnpoint eFig. 3.121 Chest radiograph showing left upper lobe infection.
Anatomy_Gray_506	Anatomy_Gray	Table 3.1 Muscles of the pectoral region Table 3.2 Muscles of the thoracic wall Table 3.3 Branches of the thoracic aorta In the clinic Axillary tail of breast It is important for clinicians to remember when evaluating the breast for pathology that the upper lateral region of the breast can project around the lateral margin of the pectoralis major muscle and into the axilla. This axillary process (axillary tail) may perforate deep fascia and extend as far superiorly as the apex of the axilla. In the clinic Breast cancer is one of the most common malignancies in women. It develops in the cells of the acini, lactiferous ducts, and lobules of the breast. Tumor growth and spread depends on the exact cellular site of origin of the cancer. These factors affect the response to surgery, chemotherapy, and radiotherapy. Breast tumors spread via the lymphatics and veins, or by direct invasion.	Anatomy_Gray. Table 3.1 Muscles of the pectoral region Table 3.2 Muscles of the thoracic wall Table 3.3 Branches of the thoracic aorta In the clinic Axillary tail of breast It is important for clinicians to remember when evaluating the breast for pathology that the upper lateral region of the breast can project around the lateral margin of the pectoralis major muscle and into the axilla. This axillary process (axillary tail) may perforate deep fascia and extend as far superiorly as the apex of the axilla. In the clinic Breast cancer is one of the most common malignancies in women. It develops in the cells of the acini, lactiferous ducts, and lobules of the breast. Tumor growth and spread depends on the exact cellular site of origin of the cancer. These factors affect the response to surgery, chemotherapy, and radiotherapy. Breast tumors spread via the lymphatics and veins, or by direct invasion.
Anatomy_Gray_507	Anatomy_Gray	When a patient has a lump in the breast, a diagnosis of breast cancer is confirmed by a biopsy and histological evaluation. Once confirmed, the clinician must attempt to stage the tumor. Staging the tumor means defining the: size of the primary tumor, exact site of the primary tumor, number and sites of lymph node spread, and organs to which the tumor may have spread. Computed tomography (CT) scanning of the body may be carried out to look for any spread to the lungs (pulmonary metastases), liver (hepatic metastases), or bone (bony metastases). Further imaging may include bone scanning using radioactive isotopes, which are avidly taken up by the tumor metastases in bone, and PET-CT, which can visualize active foci of the metastatic disease in the body.	Anatomy_Gray. When a patient has a lump in the breast, a diagnosis of breast cancer is confirmed by a biopsy and histological evaluation. Once confirmed, the clinician must attempt to stage the tumor. Staging the tumor means defining the: size of the primary tumor, exact site of the primary tumor, number and sites of lymph node spread, and organs to which the tumor may have spread. Computed tomography (CT) scanning of the body may be carried out to look for any spread to the lungs (pulmonary metastases), liver (hepatic metastases), or bone (bony metastases). Further imaging may include bone scanning using radioactive isotopes, which are avidly taken up by the tumor metastases in bone, and PET-CT, which can visualize active foci of the metastatic disease in the body.
Anatomy_Gray_508	Anatomy_Gray	Lymph drainage of the breast is complex. Lymph vessels pass to axillary, supraclavicular, and parasternal nodes and may even pass to abdominal lymph nodes, as well as to the opposite breast. Containment of nodal metastatic breast cancer is therefore potentially difficult because it can spread through many lymph node groups. Subcutaneous lymphatic obstruction and tumor growth pull on connective tissue ligaments in the breast, resulting in the appearance of an orange peel texture (peau d’orange) on the surface of the breast. Further subcutaneous spread can induce a rare manifestation of breast cancer that produces a hard, woody texture to the skin (cancer en cuirasse).	Anatomy_Gray. Lymph drainage of the breast is complex. Lymph vessels pass to axillary, supraclavicular, and parasternal nodes and may even pass to abdominal lymph nodes, as well as to the opposite breast. Containment of nodal metastatic breast cancer is therefore potentially difficult because it can spread through many lymph node groups. Subcutaneous lymphatic obstruction and tumor growth pull on connective tissue ligaments in the breast, resulting in the appearance of an orange peel texture (peau d’orange) on the surface of the breast. Further subcutaneous spread can induce a rare manifestation of breast cancer that produces a hard, woody texture to the skin (cancer en cuirasse).
Anatomy_Gray_509	Anatomy_Gray	A mastectomy (surgical removal of the breast) involves excision of breast tissue. Within the axilla the breast tissue must be removed from the medial axillary wall. Closely applied to the medial axillary wall is the long thoracic nerve. Damage to this nerve can result in paralysis of the serratus anterior muscle, producing a characteristic “winged” scapula. It is also possible to damage the nerve to the latissimus dorsi muscle, and this may affect extension, medial rotation, and adduction of the humerus. In the clinic Cervical ribs are present in approximately 1% of the population. A cervical rib is an accessory rib articulating with vertebra CVII; the anterior end attaches to the superior border of the anterior aspect of rib I. Plain radiographs may demonstrate cervical ribs as small horn-like structures (see Fig. 3.106).	Anatomy_Gray. A mastectomy (surgical removal of the breast) involves excision of breast tissue. Within the axilla the breast tissue must be removed from the medial axillary wall. Closely applied to the medial axillary wall is the long thoracic nerve. Damage to this nerve can result in paralysis of the serratus anterior muscle, producing a characteristic “winged” scapula. It is also possible to damage the nerve to the latissimus dorsi muscle, and this may affect extension, medial rotation, and adduction of the humerus. In the clinic Cervical ribs are present in approximately 1% of the population. A cervical rib is an accessory rib articulating with vertebra CVII; the anterior end attaches to the superior border of the anterior aspect of rib I. Plain radiographs may demonstrate cervical ribs as small horn-like structures (see Fig. 3.106).
Anatomy_Gray_510	Anatomy_Gray	Plain radiographs may demonstrate cervical ribs as small horn-like structures (see Fig. 3.106). It is often not appreciated by clinicians that a fibrous band commonly extends from the anterior tip of the small cervical ribs to rib I, producing a “cervical band” that is not visualized on radiography. In patients with cervical ribs and cervical bands, structures that normally pass over rib I (see Fig. 3.7) are elevated by, and pass over, the cervical rib and band.	Anatomy_Gray. Plain radiographs may demonstrate cervical ribs as small horn-like structures (see Fig. 3.106). It is often not appreciated by clinicians that a fibrous band commonly extends from the anterior tip of the small cervical ribs to rib I, producing a “cervical band” that is not visualized on radiography. In patients with cervical ribs and cervical bands, structures that normally pass over rib I (see Fig. 3.7) are elevated by, and pass over, the cervical rib and band.
Anatomy_Gray_511	Anatomy_Gray	Clinically, “thoracic outlet syndrome” is used to describe symptoms resulting from abnormal compression of the brachial plexus of nerves as it passes over the first rib and through the axillary inlet into the upper limb. The anterior ramus of T1 passes superiorly out of the superior thoracic aperture to join and become part of the brachial plexus. The cervical band from a cervical rib is one cause of thoracic outlet syndrome by putting upward stresses on the lower parts of the brachial plexus as they pass over the cervical band and related cervical rib. In the clinic Collection of sternal bone marrow The subcutaneous position of the sternum makes it possible to place a needle through the hard outer cortex into the internal (or medullary) cavity containing bone marrow. Once the needle is in this position, bone marrow can be aspirated. Evaluation of this material under the microscope helps clinicians diagnose certain blood diseases such as leukemia. In the clinic	Anatomy_Gray. Clinically, “thoracic outlet syndrome” is used to describe symptoms resulting from abnormal compression of the brachial plexus of nerves as it passes over the first rib and through the axillary inlet into the upper limb. The anterior ramus of T1 passes superiorly out of the superior thoracic aperture to join and become part of the brachial plexus. The cervical band from a cervical rib is one cause of thoracic outlet syndrome by putting upward stresses on the lower parts of the brachial plexus as they pass over the cervical band and related cervical rib. In the clinic Collection of sternal bone marrow The subcutaneous position of the sternum makes it possible to place a needle through the hard outer cortex into the internal (or medullary) cavity containing bone marrow. Once the needle is in this position, bone marrow can be aspirated. Evaluation of this material under the microscope helps clinicians diagnose certain blood diseases such as leukemia. In the clinic
Anatomy_Gray_512	Anatomy_Gray	In the clinic Single rib fractures are of little consequence, though extremely painful. After severe trauma, ribs may be broken in two or more places. If enough ribs are broken, a loose segment of chest wall, a flail segment (flail chest), is produced. When the patient takes a deep inspiration, the flail segment moves in the opposite direction to the chest wall, preventing full lung expansion and creating a paradoxically moving segment. If a large enough segment of chest wall is affected, ventilation may be impaired and assisted ventilation may be required until the ribs have healed. In the clinic Surgical access to the chest A surgical access is potentially more challenging in the chest given the rigid nature of the thoracic cage. Moreover, access is also dependent upon the organ that is operated upon and its relationships to subdiaphragmatic structures and structures in the neck. The most common approaches are a median sternotomy and a lateral thoracotomy.	Anatomy_Gray. In the clinic Single rib fractures are of little consequence, though extremely painful. After severe trauma, ribs may be broken in two or more places. If enough ribs are broken, a loose segment of chest wall, a flail segment (flail chest), is produced. When the patient takes a deep inspiration, the flail segment moves in the opposite direction to the chest wall, preventing full lung expansion and creating a paradoxically moving segment. If a large enough segment of chest wall is affected, ventilation may be impaired and assisted ventilation may be required until the ribs have healed. In the clinic Surgical access to the chest A surgical access is potentially more challenging in the chest given the rigid nature of the thoracic cage. Moreover, access is also dependent upon the organ that is operated upon and its relationships to subdiaphragmatic structures and structures in the neck. The most common approaches are a median sternotomy and a lateral thoracotomy.
Anatomy_Gray_513	Anatomy_Gray	A median sternotomy involves making a vertical incision in the sternum from just below the sternal notch to the distal end of the xiphoid process. Care must be taken not to cause injury to the vessels, in particular to the brachiocephalic veins. Bleeding from the branches of the internal thoracic artery can occur and needs to be controlled. Opening the sternum causes traction on the upper ribs and may lead to rib fractures. Sometimes partial sternotomy is performed with the incision involving only the upper part of the sternum and ending at the level of manubriosternal junction or just below. A median sternotomy allows access to the heart, including coronary arteries and valves, pericardium, great vessels, anterior mediastinum, and thymus, as well as to the lower trachea. It can also be used for removal of retrosternal goiter or during esophagectomy. The incision can be extended laterally into the supraclavicular region, giving access to the subclavian and carotid arteries.	Anatomy_Gray. A median sternotomy involves making a vertical incision in the sternum from just below the sternal notch to the distal end of the xiphoid process. Care must be taken not to cause injury to the vessels, in particular to the brachiocephalic veins. Bleeding from the branches of the internal thoracic artery can occur and needs to be controlled. Opening the sternum causes traction on the upper ribs and may lead to rib fractures. Sometimes partial sternotomy is performed with the incision involving only the upper part of the sternum and ending at the level of manubriosternal junction or just below. A median sternotomy allows access to the heart, including coronary arteries and valves, pericardium, great vessels, anterior mediastinum, and thymus, as well as to the lower trachea. It can also be used for removal of retrosternal goiter or during esophagectomy. The incision can be extended laterally into the supraclavicular region, giving access to the subclavian and carotid arteries.
Anatomy_Gray_514	Anatomy_Gray	A lateral thoracotomy gives access to the ipsilateral hemithorax and its contents including the lung, mediastinum, esophagus, and heart (left lateral thoracotomy) (Fig. 3.33). However, it involves division of muscles of the thoracic wall which leads to significant postoperative pain that needs to be well controlled to avoid restricted lung function. The incision starts at the anterior axillary line and then passes below the tip of the scapula and is extended superiorly between the posterior midline and medial border of the scapula. The pleural cavity is entered through an intercostal space. In older patients and those with osteoporosis, a short segment of rib is often resected to minimize the risk of a rib fracture.	Anatomy_Gray. A lateral thoracotomy gives access to the ipsilateral hemithorax and its contents including the lung, mediastinum, esophagus, and heart (left lateral thoracotomy) (Fig. 3.33). However, it involves division of muscles of the thoracic wall which leads to significant postoperative pain that needs to be well controlled to avoid restricted lung function. The incision starts at the anterior axillary line and then passes below the tip of the scapula and is extended superiorly between the posterior midline and medial border of the scapula. The pleural cavity is entered through an intercostal space. In older patients and those with osteoporosis, a short segment of rib is often resected to minimize the risk of a rib fracture.
Anatomy_Gray_515	Anatomy_Gray	Minimally invasive thoracic surgery (video-assisted thoracic surgery [VATS]) involves making small (1-cm) incisions in the intercostal spaces, placing a small camera on a telescope, and manipulating other instruments through additional small incisions. A number of procedures can be performed in this manner, including lobectomy, lung biopsy, and esophagectomy. In the clinic Insertion of a chest tube is a commonly performed procedure and is indicated to relieve air or fluid trapped in the thorax between the lung and the chest wall (pleural cavity). This procedure is done for pneumothorax, hemothorax, hemopneumothorax, malignant pleural effusion empyema, hydrothorax, and chylothorax, and also after thoracic surgery.	Anatomy_Gray. Minimally invasive thoracic surgery (video-assisted thoracic surgery [VATS]) involves making small (1-cm) incisions in the intercostal spaces, placing a small camera on a telescope, and manipulating other instruments through additional small incisions. A number of procedures can be performed in this manner, including lobectomy, lung biopsy, and esophagectomy. In the clinic Insertion of a chest tube is a commonly performed procedure and is indicated to relieve air or fluid trapped in the thorax between the lung and the chest wall (pleural cavity). This procedure is done for pneumothorax, hemothorax, hemopneumothorax, malignant pleural effusion empyema, hydrothorax, and chylothorax, and also after thoracic surgery.
Anatomy_Gray_516	Anatomy_Gray	The position of the thoracostomy tube is usually between the anterior axillary and midaxillary anatomical lines from anterior to posterior and in either the fourth or fifth intercostal space. The position of the ribs in this region should be clearly marked. Anesthetic should be applied to the superior border of the rib and the inferior aspect of the intercostal space, including one rib and space above and one rib and space below. The neurovascular bundle runs in the neurovascular plane, which lies in the superior aspect of the intercostal space (just below the rib); hence, the reason for positioning the tube on the superior border of a rib (i.e., at the lowest position in the intercostal space).	Anatomy_Gray. The position of the thoracostomy tube is usually between the anterior axillary and midaxillary anatomical lines from anterior to posterior and in either the fourth or fifth intercostal space. The position of the ribs in this region should be clearly marked. Anesthetic should be applied to the superior border of the rib and the inferior aspect of the intercostal space, including one rib and space above and one rib and space below. The neurovascular bundle runs in the neurovascular plane, which lies in the superior aspect of the intercostal space (just below the rib); hence, the reason for positioning the tube on the superior border of a rib (i.e., at the lowest position in the intercostal space).
Anatomy_Gray_517	Anatomy_Gray	Chest tube insertion is now commonly done with direct ultrasound guidance. This approach allows the physician both to assess whether the pleural effusion is simple or complex and loculated, and to select the safest site for entering the pleural space. In some cases of pneumothorax, a chest drain can be inserted under computed tomography-guidance, especially in patients with underlying lung disease where it is difficult to differentiate a large bulla from free air in the pleural space. In the clinic Local anesthesia of intercostal nerves produces excellent analgesia in patients with chest trauma and in those patients requiring anesthesia for a thoracotomy, mastectomy, or upper abdominal surgical procedures. The intercostal nerves are situated inferior to the rib borders in the neurovascular bundle. Each neurovascular bundle is situated deep to the external and internal intercostal muscle groups.	Anatomy_Gray. Chest tube insertion is now commonly done with direct ultrasound guidance. This approach allows the physician both to assess whether the pleural effusion is simple or complex and loculated, and to select the safest site for entering the pleural space. In some cases of pneumothorax, a chest drain can be inserted under computed tomography-guidance, especially in patients with underlying lung disease where it is difficult to differentiate a large bulla from free air in the pleural space. In the clinic Local anesthesia of intercostal nerves produces excellent analgesia in patients with chest trauma and in those patients requiring anesthesia for a thoracotomy, mastectomy, or upper abdominal surgical procedures. The intercostal nerves are situated inferior to the rib borders in the neurovascular bundle. Each neurovascular bundle is situated deep to the external and internal intercostal muscle groups.
Anatomy_Gray_518	Anatomy_Gray	The intercostal nerves are situated inferior to the rib borders in the neurovascular bundle. Each neurovascular bundle is situated deep to the external and internal intercostal muscle groups. The nerve block may be undertaken using a “blind” technique or under direct imaging guidance. The patient is placed in the appropriate position to access the rib. Typically, under ultrasound guidance, a needle may be advanced into the region of the subcostal groove, followed by an injection with a local anesthetic. Depending on the type of anesthetic used, analgesia may be shortor long-acting. Given the position of the neurovascular bundle and the subcostal groove, complications may include puncture of the parietal pleura and an ensuing pneumothorax. Bleeding may also occur if the artery or vein is damaged during the procedure. In the clinic	Anatomy_Gray. The intercostal nerves are situated inferior to the rib borders in the neurovascular bundle. Each neurovascular bundle is situated deep to the external and internal intercostal muscle groups. The nerve block may be undertaken using a “blind” technique or under direct imaging guidance. The patient is placed in the appropriate position to access the rib. Typically, under ultrasound guidance, a needle may be advanced into the region of the subcostal groove, followed by an injection with a local anesthetic. Depending on the type of anesthetic used, analgesia may be shortor long-acting. Given the position of the neurovascular bundle and the subcostal groove, complications may include puncture of the parietal pleura and an ensuing pneumothorax. Bleeding may also occur if the artery or vein is damaged during the procedure. In the clinic
Anatomy_Gray_519	Anatomy_Gray	In the clinic In cases of phrenic nerve palsy, diaphragmatic paralysis ensues, which is manifested by the elevation of the diaphragm muscle on the affected side (Fig. 3.36). The most important cause of the phrenic nerve palsy that should never be overlooked is malignant infiltration of the nerve by lung cancer. Other causes include postviral neuropathy (in particular, related to varicella zoster virus), trauma, iatrogenic injury during thoracic surgery, and degenerative changes in the cervical spine with compression of the C3–C5 nerve roots. Most patients with unilateral diaphragmatic paralysis are asymptomatic and require no treatment. Some may report shortness of breath, particularly on exertion. Bilateral paralysis of the diaphragm is rare but can cause significant respiratory distress.	Anatomy_Gray. In the clinic In cases of phrenic nerve palsy, diaphragmatic paralysis ensues, which is manifested by the elevation of the diaphragm muscle on the affected side (Fig. 3.36). The most important cause of the phrenic nerve palsy that should never be overlooked is malignant infiltration of the nerve by lung cancer. Other causes include postviral neuropathy (in particular, related to varicella zoster virus), trauma, iatrogenic injury during thoracic surgery, and degenerative changes in the cervical spine with compression of the C3–C5 nerve roots. Most patients with unilateral diaphragmatic paralysis are asymptomatic and require no treatment. Some may report shortness of breath, particularly on exertion. Bilateral paralysis of the diaphragm is rare but can cause significant respiratory distress.
Anatomy_Gray_520	Anatomy_Gray	Surgical plication of the diaphragm can be performed in cases with respiratory compromise and is often done laparoscopically. The surgeon creates folds in the paralyzed diaphragm and sutures them in place, reducing the mobility of the diaphragmatic muscle. There is usually good improvement in lung function, exercise tolerance, and shortness of breath after the procedure. In the clinic A pleural effusion occurs when excess fluid accumulates within the pleural space. As the fluid accumulates within the pleural space the underlying lung is compromised and may collapse as the volume of fluid increases. Once a pleural effusion has been diagnosed, fluid often will be aspirated to determine the cause, which can include infection, malignancy, cardiac failure, hepatic disease, and pulmonary embolism. A large pleural effusion needs to be drained to allow the collapsed part of the lung to reexpand and improve breathing (Fig. 3.41). In the clinic	Anatomy_Gray. Surgical plication of the diaphragm can be performed in cases with respiratory compromise and is often done laparoscopically. The surgeon creates folds in the paralyzed diaphragm and sutures them in place, reducing the mobility of the diaphragmatic muscle. There is usually good improvement in lung function, exercise tolerance, and shortness of breath after the procedure. In the clinic A pleural effusion occurs when excess fluid accumulates within the pleural space. As the fluid accumulates within the pleural space the underlying lung is compromised and may collapse as the volume of fluid increases. Once a pleural effusion has been diagnosed, fluid often will be aspirated to determine the cause, which can include infection, malignancy, cardiac failure, hepatic disease, and pulmonary embolism. A large pleural effusion needs to be drained to allow the collapsed part of the lung to reexpand and improve breathing (Fig. 3.41). In the clinic
Anatomy_Gray_521	Anatomy_Gray	In the clinic A pneumothorax is a collection of gas or air within the pleural cavity (Fig. 3.42). When air enters the pleural cavity the tissue elasticity of the parenchyma causes the lung to collapse within the chest, impairing the lung function. Occasionally, the gas within the pleural cavity may accumulate to such an extent that the mediastinum is “pushed” to the opposite side, compromising the other lung. This is termed a tension pneumothorax and requires urgent treatment. Most pneumothoraces are spontaneous (i.e., they occur in the absence of no known pathology and no known lung disease). In addition, pneumothoraces may occur as a result of trauma, inflammation, smoking, and other underlying pulmonary diseases. Certain pulmonary metastases, such as in patients with osteosarcoma, may cause spontaneous pneumothorax especially after chemotherapy. The occurrence of pneumothorax interferes with cancer treatment and increases mortality.	Anatomy_Gray. In the clinic A pneumothorax is a collection of gas or air within the pleural cavity (Fig. 3.42). When air enters the pleural cavity the tissue elasticity of the parenchyma causes the lung to collapse within the chest, impairing the lung function. Occasionally, the gas within the pleural cavity may accumulate to such an extent that the mediastinum is “pushed” to the opposite side, compromising the other lung. This is termed a tension pneumothorax and requires urgent treatment. Most pneumothoraces are spontaneous (i.e., they occur in the absence of no known pathology and no known lung disease). In addition, pneumothoraces may occur as a result of trauma, inflammation, smoking, and other underlying pulmonary diseases. Certain pulmonary metastases, such as in patients with osteosarcoma, may cause spontaneous pneumothorax especially after chemotherapy. The occurrence of pneumothorax interferes with cancer treatment and increases mortality.
Anatomy_Gray_522	Anatomy_Gray	The symptoms of pneumothorax are often determined by the degree of air leak and the rate at which the accumulation of gas occurs and the ensuing lung collapses. They include pain, shortness of breath, and cardiorespiratory collapse, if severe. In the clinic Imaging the lungs Medical imaging of the lungs is important because they are one of the commonest sites for disease in the body. While the body is at rest, the lungs exchange up to 5 L of air per minute, and this may contain pathogens and other potentially harmful elements (e.g., allergens). Techniques to visualize the lung range from plain chest radiographs to high-resolution computed tomography (CT), which enables precise localization of a lesion within the lung. In the clinic	Anatomy_Gray. The symptoms of pneumothorax are often determined by the degree of air leak and the rate at which the accumulation of gas occurs and the ensuing lung collapses. They include pain, shortness of breath, and cardiorespiratory collapse, if severe. In the clinic Imaging the lungs Medical imaging of the lungs is important because they are one of the commonest sites for disease in the body. While the body is at rest, the lungs exchange up to 5 L of air per minute, and this may contain pathogens and other potentially harmful elements (e.g., allergens). Techniques to visualize the lung range from plain chest radiographs to high-resolution computed tomography (CT), which enables precise localization of a lesion within the lung. In the clinic
Anatomy_Gray_523	Anatomy_Gray	In the clinic High-resolution computed tomography (HRCT) is a diagnostic method for assessing the lungs but more specifically the interstitium of the lungs. The technique involves obtaining narrow cross-sectional slices of 1 to 2 mm. These scans enable the physician and radiologist to view the patterns of disease and their distribution. Diseases that may be easily demonstrated using this procedure include emphysema (Fig. 3.52), pneumoconiosis (coal worker’s pneumoconiosis), and asbestosis. HRCT is also useful in regular follow-ups of patients with interstitial disease to monitor disease progression. In the clinic	Anatomy_Gray. In the clinic High-resolution computed tomography (HRCT) is a diagnostic method for assessing the lungs but more specifically the interstitium of the lungs. The technique involves obtaining narrow cross-sectional slices of 1 to 2 mm. These scans enable the physician and radiologist to view the patterns of disease and their distribution. Diseases that may be easily demonstrated using this procedure include emphysema (Fig. 3.52), pneumoconiosis (coal worker’s pneumoconiosis), and asbestosis. HRCT is also useful in regular follow-ups of patients with interstitial disease to monitor disease progression. In the clinic
Anatomy_Gray_524	Anatomy_Gray	In the clinic Patients who have an endobronchial lesion (i.e., a lesion within a bronchus) may undergo bronchoscopic evaluation of the trachea and its main branches (Fig. 3.53). The bronchoscope is passed through the nose into the oropharynx and is then directed by a control system past the vocal cords into the trachea. The bronchi are inspected and, if necessary, small biopsies are obtained. Bronchoscopy can also be used in combination with ultrasound (a technique known as EBUS, endobronchial ultrasound). An ultrasound probe is inserted through a working channel of the bronchoscope to visualize the airway walls and adjacent structures. EBUS allows an accurate localization of the lesion and therefore provides a higher diagnostic yield. It can be used for sampling of mediastinal and hilar lymph nodes or to assist in transbronchial biopsy of pulmonary nodules. In the clinic It is important to stage lung cancer because the treatment depends on its stage.	Anatomy_Gray. In the clinic Patients who have an endobronchial lesion (i.e., a lesion within a bronchus) may undergo bronchoscopic evaluation of the trachea and its main branches (Fig. 3.53). The bronchoscope is passed through the nose into the oropharynx and is then directed by a control system past the vocal cords into the trachea. The bronchi are inspected and, if necessary, small biopsies are obtained. Bronchoscopy can also be used in combination with ultrasound (a technique known as EBUS, endobronchial ultrasound). An ultrasound probe is inserted through a working channel of the bronchoscope to visualize the airway walls and adjacent structures. EBUS allows an accurate localization of the lesion and therefore provides a higher diagnostic yield. It can be used for sampling of mediastinal and hilar lymph nodes or to assist in transbronchial biopsy of pulmonary nodules. In the clinic It is important to stage lung cancer because the treatment depends on its stage.
Anatomy_Gray_525	Anatomy_Gray	In the clinic It is important to stage lung cancer because the treatment depends on its stage. If a small malignant nodule is found within the lung, it can sometimes be excised and the prognosis is excellent. Unfortunately, many patients present with a tumor mass that has invaded structures in the mediastinum or the pleurae or has metastasized. The tumor may then be inoperable and is treated with radiotherapy and chemotherapy. Spread of the tumor is by lymphatics to lymph nodes within the hila, mediastinum, and root of the neck. A key factor affecting the prognosis and ability to cure the disease is the distant spread of metastases. Imaging methods to assess spread include plain radiography (Fig. 3.54A), computed tomography (CT; Fig. 3.54B,C), and magnetic resonance imaging (MRI). Increasingly, radionuclide studies using fluorodeoxyglucose positron emission tomography (FDG PET; Fig. 3.54D) are being used.	Anatomy_Gray. In the clinic It is important to stage lung cancer because the treatment depends on its stage. If a small malignant nodule is found within the lung, it can sometimes be excised and the prognosis is excellent. Unfortunately, many patients present with a tumor mass that has invaded structures in the mediastinum or the pleurae or has metastasized. The tumor may then be inoperable and is treated with radiotherapy and chemotherapy. Spread of the tumor is by lymphatics to lymph nodes within the hila, mediastinum, and root of the neck. A key factor affecting the prognosis and ability to cure the disease is the distant spread of metastases. Imaging methods to assess spread include plain radiography (Fig. 3.54A), computed tomography (CT; Fig. 3.54B,C), and magnetic resonance imaging (MRI). Increasingly, radionuclide studies using fluorodeoxyglucose positron emission tomography (FDG PET; Fig. 3.54D) are being used.
Anatomy_Gray_526	Anatomy_Gray	In FDG PET a gamma radiation emitter is attached to a glucose molecule. In areas of high metabolic activity (i.e., the tumor), excessive uptake occurs and is recorded by a gamma camera. In the clinic Pericarditis is an inflammatory condition of the pericardium. Common causes are viral and bacterial infections, systemic illnesses (e.g., chronic renal failure), and after myocardial infarction.	Anatomy_Gray. In FDG PET a gamma radiation emitter is attached to a glucose molecule. In areas of high metabolic activity (i.e., the tumor), excessive uptake occurs and is recorded by a gamma camera. In the clinic Pericarditis is an inflammatory condition of the pericardium. Common causes are viral and bacterial infections, systemic illnesses (e.g., chronic renal failure), and after myocardial infarction.
Anatomy_Gray_527	Anatomy_Gray	Pericarditis is an inflammatory condition of the pericardium. Common causes are viral and bacterial infections, systemic illnesses (e.g., chronic renal failure), and after myocardial infarction. Pericarditis must be distinguished from myocardial infarction because the treatment and prognosis are quite different. As in patients with myocardial infarction, patients with pericarditis complain of continuous central chest pain that may radiate to one or both arms. Unlike myocardial infarction, however, the pain from pericarditis may be relieved by sitting forward. An electrocardiogram (ECG) is used to help differentiate between the two conditions. It usually shows diffuse ST elevation. Echocardiography can also be performed if there is clinical or radiographic suspicion of pericardial effusion. In the clinic	Anatomy_Gray. Pericarditis is an inflammatory condition of the pericardium. Common causes are viral and bacterial infections, systemic illnesses (e.g., chronic renal failure), and after myocardial infarction. Pericarditis must be distinguished from myocardial infarction because the treatment and prognosis are quite different. As in patients with myocardial infarction, patients with pericarditis complain of continuous central chest pain that may radiate to one or both arms. Unlike myocardial infarction, however, the pain from pericarditis may be relieved by sitting forward. An electrocardiogram (ECG) is used to help differentiate between the two conditions. It usually shows diffuse ST elevation. Echocardiography can also be performed if there is clinical or radiographic suspicion of pericardial effusion. In the clinic
Anatomy_Gray_528	Anatomy_Gray	In the clinic Normally, only a tiny amount of fluid is present between the visceral and parietal layers of the serous pericardium. In certain situations, this space can be filled with excess fluid (pericardial effusion) (Fig. 3.62). Because the fibrous pericardium is a “relatively fixed” structure that cannot expand easily, a rapid accumulation of excess fluid within the pericardial sac compresses the heart (cardiac tamponade), resulting in biventricular failure. Removing the fluid with a needle inserted into the pericardial sac can relieve the symptoms. In the clinic	Anatomy_Gray. In the clinic Normally, only a tiny amount of fluid is present between the visceral and parietal layers of the serous pericardium. In certain situations, this space can be filled with excess fluid (pericardial effusion) (Fig. 3.62). Because the fibrous pericardium is a “relatively fixed” structure that cannot expand easily, a rapid accumulation of excess fluid within the pericardial sac compresses the heart (cardiac tamponade), resulting in biventricular failure. Removing the fluid with a needle inserted into the pericardial sac can relieve the symptoms. In the clinic
Anatomy_Gray_529	Anatomy_Gray	In the clinic Abnormal thickening of the pericardial sac (constrictive pericarditis), which usually involves only the parietal pericardium, but can also less frequently involve the visceral layer, can compress the heart, impairing heart function and resulting in heart failure. It can present acutely but often results in a chronic condition when thickened pericardium with fibrin deposits causes pericardial inflammation, leading to chronic scarring and pericardial calcification. As a result, normal filling during the diastolic phase of the cardiac cycle is severely restricted. The diagnosis is made by inspecting the jugular venous pulse in the neck. In normal individuals, the jugular venous pulse drops on inspiration. In patients with constrictive pericarditis, the reverse happens and this is called Kussmaul’s sign. Treatment often involves surgical opening of the pericardial sac. In the clinic	Anatomy_Gray. In the clinic Abnormal thickening of the pericardial sac (constrictive pericarditis), which usually involves only the parietal pericardium, but can also less frequently involve the visceral layer, can compress the heart, impairing heart function and resulting in heart failure. It can present acutely but often results in a chronic condition when thickened pericardium with fibrin deposits causes pericardial inflammation, leading to chronic scarring and pericardial calcification. As a result, normal filling during the diastolic phase of the cardiac cycle is severely restricted. The diagnosis is made by inspecting the jugular venous pulse in the neck. In normal individuals, the jugular venous pulse drops on inspiration. In patients with constrictive pericarditis, the reverse happens and this is called Kussmaul’s sign. Treatment often involves surgical opening of the pericardial sac. In the clinic
Anatomy_Gray_530	Anatomy_Gray	In the clinic Valve problems consist of two basic types: incompetence (insufficiency), which results from poorly functioning valves; and stenosis, a narrowing of the orifice, caused by the valve’s inability to open fully. Mitral valve disease is usually a mixed pattern of stenosis and incompetence, one of which usually predominates. Both stenosis and incompetence lead to a poorly functioning valve and subsequent heart changes, which include: left ventricular hypertrophy (this is appreciably less marked in patients with mitral stenosis); increased pulmonary venous pressure; pulmonary edema; and enlargement (dilation) and hypertrophy of the left atrium. Mitral valve stenosis can be congenital or acquired; in the latter, the most common cause is rheumatic fever. Stenosis usually occurs decades after an acute episode of rheumatic endocarditis.	Anatomy_Gray. In the clinic Valve problems consist of two basic types: incompetence (insufficiency), which results from poorly functioning valves; and stenosis, a narrowing of the orifice, caused by the valve’s inability to open fully. Mitral valve disease is usually a mixed pattern of stenosis and incompetence, one of which usually predominates. Both stenosis and incompetence lead to a poorly functioning valve and subsequent heart changes, which include: left ventricular hypertrophy (this is appreciably less marked in patients with mitral stenosis); increased pulmonary venous pressure; pulmonary edema; and enlargement (dilation) and hypertrophy of the left atrium. Mitral valve stenosis can be congenital or acquired; in the latter, the most common cause is rheumatic fever. Stenosis usually occurs decades after an acute episode of rheumatic endocarditis.
Anatomy_Gray_531	Anatomy_Gray	Mitral valve stenosis can be congenital or acquired; in the latter, the most common cause is rheumatic fever. Stenosis usually occurs decades after an acute episode of rheumatic endocarditis. Aortic valve disease, both aortic stenosis and aortic regurgitation (backflow), can produce marked heart failure. Aortic valve stenosis is the most common type of cardiac valve disease and results from atherosclerosis causing calcification of the valve leaflets. It can also be caused by postinflammatory or postrheumatic conditions. These may lead to aortic regurgitation such as infective endocarditis, degenerative valve disease, rheumatic fever, or trauma.	Anatomy_Gray. Mitral valve stenosis can be congenital or acquired; in the latter, the most common cause is rheumatic fever. Stenosis usually occurs decades after an acute episode of rheumatic endocarditis. Aortic valve disease, both aortic stenosis and aortic regurgitation (backflow), can produce marked heart failure. Aortic valve stenosis is the most common type of cardiac valve disease and results from atherosclerosis causing calcification of the valve leaflets. It can also be caused by postinflammatory or postrheumatic conditions. These may lead to aortic regurgitation such as infective endocarditis, degenerative valve disease, rheumatic fever, or trauma.
Anatomy_Gray_532	Anatomy_Gray	Valve disease in the right side of the heart (affecting the tricuspid or pulmonary valve) is most likely caused by infection. Intravenous drug use, alcoholism, indwelling catheters, and extensive burns predispose to infection of the valves, particularly the tricuspid valve. The resulting valve dysfunction produces abnormal pressure changes in the right atrium and right ventricle, and these can induce cardiac failure. In the clinic In practice, physicians use alternative names for the coronary vessels. The short left coronary artery is referred to as the left main stem vessel. One of its primary branches, the anterior interventricular artery, is termed the left anterior descending artery (LAD). Similarly, the terminal branch of the right coronary artery, the posterior interventricular artery, is termed the posterior descending artery (PDA). In the clinic	Anatomy_Gray. Valve disease in the right side of the heart (affecting the tricuspid or pulmonary valve) is most likely caused by infection. Intravenous drug use, alcoholism, indwelling catheters, and extensive burns predispose to infection of the valves, particularly the tricuspid valve. The resulting valve dysfunction produces abnormal pressure changes in the right atrium and right ventricle, and these can induce cardiac failure. In the clinic In practice, physicians use alternative names for the coronary vessels. The short left coronary artery is referred to as the left main stem vessel. One of its primary branches, the anterior interventricular artery, is termed the left anterior descending artery (LAD). Similarly, the terminal branch of the right coronary artery, the posterior interventricular artery, is termed the posterior descending artery (PDA). In the clinic
Anatomy_Gray_533	Anatomy_Gray	In the clinic A heart attack occurs when the perfusion to the myocardium is insufficient to meet the metabolic needs of the tissue, leading to irreversible tissue damage. The most common cause is a total occlusion of a major coronary artery. Occlusion of a major coronary artery, usually due to atherosclerosis, leads to inadequate oxygenation of an area of myocardium and cell death (Fig. 3.80). The severity of the problem will be related to the size and location of the artery involved, whether or not the blockage is complete, and whether there are collateral vessels to provide perfusion to the territory from other vessels. Depending on the severity, patients can develop pain (angina) or a myocardial infarction (MI).	Anatomy_Gray. In the clinic A heart attack occurs when the perfusion to the myocardium is insufficient to meet the metabolic needs of the tissue, leading to irreversible tissue damage. The most common cause is a total occlusion of a major coronary artery. Occlusion of a major coronary artery, usually due to atherosclerosis, leads to inadequate oxygenation of an area of myocardium and cell death (Fig. 3.80). The severity of the problem will be related to the size and location of the artery involved, whether or not the blockage is complete, and whether there are collateral vessels to provide perfusion to the territory from other vessels. Depending on the severity, patients can develop pain (angina) or a myocardial infarction (MI).
Anatomy_Gray_534	Anatomy_Gray	This is a technique in which a long fine tube (a catheter) is inserted into the femoral artery in the thigh and passed through the external and common iliac arteries and into the abdominal aorta. It continues to be moved upward through the thoracic aorta to the origins of the coronary arteries. The coronaries may also be approached via the radial or brachial arteries. A fine wire is then passed into the coronary artery and is used to cross the stenosis. A fine balloon is then passed over the wire and may be inflated at the level of the obstruction, thus widening it; this is termed angioplasty. More commonly, this is augmented by placement of a fine wire mesh (a stent) inside the obstruction to hold it open. Other percutaneous interventions are suction extraction of a coronary thrombus and rotary ablation of a plaque.	Anatomy_Gray. This is a technique in which a long fine tube (a catheter) is inserted into the femoral artery in the thigh and passed through the external and common iliac arteries and into the abdominal aorta. It continues to be moved upward through the thoracic aorta to the origins of the coronary arteries. The coronaries may also be approached via the radial or brachial arteries. A fine wire is then passed into the coronary artery and is used to cross the stenosis. A fine balloon is then passed over the wire and may be inflated at the level of the obstruction, thus widening it; this is termed angioplasty. More commonly, this is augmented by placement of a fine wire mesh (a stent) inside the obstruction to hold it open. Other percutaneous interventions are suction extraction of a coronary thrombus and rotary ablation of a plaque.
Anatomy_Gray_535	Anatomy_Gray	If coronary artery disease is too extensive to be treated by percutaneous intervention, surgical coronary artery bypass grafting may be necessary. The great saphenous vein, in the lower limb, is harvested and used as a graft. It is divided into several pieces, each of which is used to bypass blocked sections of the coronary arteries. The internal thoracic and radial arteries can also be used. In the clinic The most common abnormalities that occur during development are those produced by a defect in the atrial and ventricular septa.	Anatomy_Gray. If coronary artery disease is too extensive to be treated by percutaneous intervention, surgical coronary artery bypass grafting may be necessary. The great saphenous vein, in the lower limb, is harvested and used as a graft. It is divided into several pieces, each of which is used to bypass blocked sections of the coronary arteries. The internal thoracic and radial arteries can also be used. In the clinic The most common abnormalities that occur during development are those produced by a defect in the atrial and ventricular septa.
Anatomy_Gray_536	Anatomy_Gray	A defect in the interatrial septum allows blood to pass from one side of the heart to the other from the chamber with the higher pressure to the chamber with the lower pressure; this is clinically referred to as a shunt. An atrial septal defect (ASD) allows oxygenated blood to flow from the left atrium (higher pressure) across the ASD into the right atrium (lower pressure), resulting in a left to right shunt and volume overload in the right-sided circulation. Many patients with ASD are asymptomatic, but in some cases the ASD may cause symptoms and needs to be closed surgically or by endovascular devices. Occasionally, increased blood flow into the right atrium over many years leads to right atrial and right ventricular hypertrophy and enlargement of the pulmonary trunk, resulting in pulmonary arterial hypertension. In such cases, the patients can present with shortness of breath, increasing tiredness, palpitations, fainting episodes and heart failure. In ASD, the left ventricle is not	Anatomy_Gray. A defect in the interatrial septum allows blood to pass from one side of the heart to the other from the chamber with the higher pressure to the chamber with the lower pressure; this is clinically referred to as a shunt. An atrial septal defect (ASD) allows oxygenated blood to flow from the left atrium (higher pressure) across the ASD into the right atrium (lower pressure), resulting in a left to right shunt and volume overload in the right-sided circulation. Many patients with ASD are asymptomatic, but in some cases the ASD may cause symptoms and needs to be closed surgically or by endovascular devices. Occasionally, increased blood flow into the right atrium over many years leads to right atrial and right ventricular hypertrophy and enlargement of the pulmonary trunk, resulting in pulmonary arterial hypertension. In such cases, the patients can present with shortness of breath, increasing tiredness, palpitations, fainting episodes and heart failure. In ASD, the left ventricle is not
Anatomy_Gray_537	Anatomy_Gray	arterial hypertension. In such cases, the patients can present with shortness of breath, increasing tiredness, palpitations, fainting episodes and heart failure. In ASD, the left ventricle is not enlarged as it is not affected by increased returning blood volume.	Anatomy_Gray. arterial hypertension. In such cases, the patients can present with shortness of breath, increasing tiredness, palpitations, fainting episodes and heart failure. In ASD, the left ventricle is not enlarged as it is not affected by increased returning blood volume.
Anatomy_Gray_538	Anatomy_Gray	The most common of all congenital heart defects are those that occur in the ventricular septum—ventriculoseptal defect (VSD). These lesions are most frequent in the membranous portion of the septum and they allow blood to flow from the left ventricle (higher pressure) to the right ventricle (lower pressure), leading to an abnormal communication between the systemic and pulmonary circulation. This leads to right ventricular hypertrophy, increased pulmonary blood flow, elevated arterial pulmonary pressure, and increased blood volume returning to the left ventricle, causing its dilation. Increased pulmonary pressure in most severe cases may cause pulmonary edema. If large enough and left untreated, VSDs can produce marked clinical problems that might require surgery. VSD may be an isolated abnormality or part of a syndromic constellation, such as the tetralogy of Fallot.	Anatomy_Gray. The most common of all congenital heart defects are those that occur in the ventricular septum—ventriculoseptal defect (VSD). These lesions are most frequent in the membranous portion of the septum and they allow blood to flow from the left ventricle (higher pressure) to the right ventricle (lower pressure), leading to an abnormal communication between the systemic and pulmonary circulation. This leads to right ventricular hypertrophy, increased pulmonary blood flow, elevated arterial pulmonary pressure, and increased blood volume returning to the left ventricle, causing its dilation. Increased pulmonary pressure in most severe cases may cause pulmonary edema. If large enough and left untreated, VSDs can produce marked clinical problems that might require surgery. VSD may be an isolated abnormality or part of a syndromic constellation, such as the tetralogy of Fallot.
Anatomy_Gray_539	Anatomy_Gray	The tetralogy of Fallot, the most common cyanotic congenital heart disorder diagnosed soon after birth, classically consists of four abnormalities: pulmonary stenosis, VSD, overriding aorta (originating to a varying degree from the right ventricle), and right ventricular hypertrophy. The underdevelopment of the right ventricle and pulmonary stenosis reduce blood flow to the lungs, leading to reduced volume of oxygenated blood returning to the heart. The defect in the interventricular septum causes mixing of oxygenated and nonoxygenated blood. The mixed blood is then delivered by the aorta to the major organs, resulting in poor oxygenation and cyanosis. Infants can present with cyanosis at birth or develop episodes of cyanosis while feeding or crying (tet spells). Most affected infants require surgical intervention. The advent of cardiopulmonary bypass was crucial in delivering highly satisfactory surgical results.	Anatomy_Gray. The tetralogy of Fallot, the most common cyanotic congenital heart disorder diagnosed soon after birth, classically consists of four abnormalities: pulmonary stenosis, VSD, overriding aorta (originating to a varying degree from the right ventricle), and right ventricular hypertrophy. The underdevelopment of the right ventricle and pulmonary stenosis reduce blood flow to the lungs, leading to reduced volume of oxygenated blood returning to the heart. The defect in the interventricular septum causes mixing of oxygenated and nonoxygenated blood. The mixed blood is then delivered by the aorta to the major organs, resulting in poor oxygenation and cyanosis. Infants can present with cyanosis at birth or develop episodes of cyanosis while feeding or crying (tet spells). Most affected infants require surgical intervention. The advent of cardiopulmonary bypass was crucial in delivering highly satisfactory surgical results.