Ribs 1-7: true ribs. 8-12: false ribs. 11-12: floating ribs

A fracture of the well-protected rib 1 suggests severe chest trauma.

Ribs 1 and 2 (protected by the clavicle) and ribs 11 and 12 are seldom fractured. In adults, a typical rib usually fractures near the angle, the point of greatest curvature. In a severe crush injury on one side, multiple ribs may fracture in two places. Fractured segments (flail chest) are sucked in during inspiration and pushed out during expiration, producing paradoxical respiratory movements. Associated pulmonary contusions contribute to respiratory insufficiency. The more flexible ribs and costal cartilages of children mean that blunt trauma may injure thoracic organs without fracturing ribs, masking the seriousness of the injury.

Thoracic and abdominal organ trauma may occur in children without rib fracture.

Paradoxical respiratory movements occur in flail chest.

A segment of rib can be excised to gain access to the thoracic cavity (thoracotomy) by longitudinally splitting the periosteum. Osteogenic cells of the periosteum regenerate bone to fill the defect.

In thoracic outlet syndrome, the subclavian artery or inferior trunk of the brachial plexus is stretched or compressed between the anterior and middle scalene muscles, often when the arm is hanging at the side. It produces numbness and tingling in the extremity, simulating a cervical disc problem. Thoracic outlet syndrome may be due to a cervical rib, hypertrophied scalene muscles, or an anomalous fibrous band.

A cervical rib may cause thoracic outlet syndrome.

Xiphisternal joint marks inferior border of heart and superior border of liver.

A traumatic sternal fracture requires evaluation for heart injury.

The sternum is split in the midline (sternotomy) and the two halves retracted for surgery on the heart (e.g., coronary bypass surgery) or other thoracic organs. The halves are wired back together.

Defective ossification may result in a lack of fusion of the right and left halves of the sternum, producing a sternal cleft. A congenital perforation in the body (sternal foramen) may be mistaken for a bullet wound. A caving in of the sternum and costal cartilages during development (pectus excavatum or funnel chest) may impair cardiac and respiratory function. It is the most common congenital abnormality of the chest wall and usually is apparent at birth but may not become pronounced until puberty. A congenital protrusion of the sternum and costal cartilages (pectus carinatum or pigeon chest) may occur alone or as part of syndrome, sometimes impairing respiration and decreasing endurance.

Pectus excavatum: funnel chest. Pectus carinatum: pigeon chest

Pectus excavatum is the most common congenital defect of the thoracic wall.

Sternal angle marks level of second costal cartilages, which is useful in counting ribs.

The sternal angle is a landmark for physical diagnosis because it is a convenient starting place for counting ribs. It is also useful because it indicates the level of a horizontal plane marking the bifurcation of the trachea, the beginning and end of the arch of the aorta, and the division into superior and inferior mediastinum.

Sternal angle marks level of tracheal bifurcation and inferior boundary of aortic arch.

Paralysis of the intercostal muscles results in intercostal tissues being sucked in during inspiration and ballooning out during expiration.

VAN = intercostal Vein, Artery, and Nerve from superior to inferior in intercostal space.

To block an intercostal nerve, the needle is inserted near the inferior border of the rib superior to the intercostal space. In contrast, to enter the pleural cavity to aspirate fluid or to perform a biopsy, the needle is inserted near the superior border of the rib inferior to the intercostal space.

To enter the pleural cavity, a needle is inserted at the superior border of the lower rib bounding the intercostal space.

Cardiac pain is often referred to the medial side of the left arm because the T1 and T2 dermatomes continue there from the thoracic wall. Communication of the intercostobrachial nerve (T2) with the medial brachial cutaneous nerve (C8, T1) is one pathway for referred pain.

Cardiac pain is often referred to the medial side of the left arm.

Herpes zoster (shingles) of an intercostal nerve produces vesicular eruptions and burning pain in the affected dermatome. Reactivation of the varicella-zoster virus follows a period of dormancy within the posterior root ganglion from years to decades after chicken pox. Elderly and immunocompromised individuals are particularly susceptible. Some patients experience severe residual pain for months or even years (postherpetic neuralgia). Contact with the shingles rash can cause chicken pox in a child who has never had it.

Shingles lesions follow a dermatomal pattern.

The T4 dermatome lies at the level of the nipple. The T10 dermatome lies at the level of the umbilicus.

Disease of the thoracic wall (e.g., in lower costal parietal pleura) may cause abdominal pain and tenderness and rigidity of abdominal muscles because the thoracoabdominal nerves continue into the anterior abdominal wall.

The mammary gland usually extends into the axilla as an axillary tail.

Seventy-five percent of the lymph from the breast drains to the axillary lymph nodes, particularly the pectoral group.

Radiographic examination of the breast by mammographic screening is used for early detection of small, nonpalpable breast carcinomas and is recommended annually for women over 40 or with a family history. BRCA1 and BRCA2 tumor suppressor gene mutations are responsible for most hereditary breast cancers, although these account for only about 7% of breast cancers.

BRCA1 and BRCA2 gene mutations cause most hereditary breast cancer.

Breast cancer may result in dimpling of the skin and retraction of the nipple caused by fibrosis and shortening of the suspensory ligaments or involvement of the ductal system. The skin may look like an orange peel (peau d’orange) because lymphatics are obstructed by the tumor. The breast may become fixed to the chest wall after the tumor invades the retromammary space, which is evident when the pectoralis major is contracted with the hand pressed against the hip.

The incidence of breast cancer in males is only 1% that of females, but often it is not diagnosed until extensive metastases have occurred. Males with Klinefelter syndrome (47, XXY) frequently exhibit gynecomastia and have an increased incidence of breast cancer.

Dimpling and an orange peel appearance of the skin and nipple retraction are signs of breast cancer.

Klinefelter syndrome males have an increased incidence of breast cancer.

Although less common than metastasis through lymphatics, cancer can spread from the breast through the venous system to the vertebral column, spinal cord, and brain through the posterior intercostal veins to the vertebral venous plexuses, and then superiorly to the dural venous sinuses of the cranial cavity.

Surgical removal of a breast carcinoma may involve only the tumor and adjacent tissue (lumpectomy), removal of the breast and axillary lymph nodes (modified radical mastectomy), or rarely the breast along with the axillary contents and pectoralis muscles (radical mastectomy). Surgery is often augmented by chemotherapy and/or radiation. During a radical mastectomy, the long thoracic nerve, which lies on the superficial surface of the serratus anterior muscle, is vulnerable. Paralysis of the serratus anterior prevents abduction of the arm above 90 degrees and causes a winged scapula. The thoracodorsal nerve also may be injured.

Breast cancer can metastasize through the venous system to the vertebral column, spinal cord, and brain.

Pneumothorax is air in the pleural cavity, resulting in collapse of the lung.

Pneumothorax is air in the pleural cavity that results in partial or total collapse of the lung. The parietal pleura may be punctured and the lung accidentally deflated (open pneumothorax) during a posterior approach to the kidney near rib 12, liver biopsy, nerve block of the stellate ganglion or brachial plexus at the root of the neck, or intravenous line insertion into the subclavian vein.

Pleural effusion is fluid in the pleural cavity from any of multiple causes, including infection, cancer, or congestive heart failure. Thoracentesis is surgical removal of fluid from the pleural cavity. A needle or incision over a lower intercostal space in the midaxillary line penetrates the skin, superficial fascia, serratus anterior, intercostal muscles, endothoracic fascia, and parietal pleura. The long thoracic nerve may be injured.

To enter pleural cavity in midaxillary line the needle penetrates skin, fascia, serratus anterior, intercostal muscles, endothoracic fascia, and parietal pleura.

Parietal pleura injury is painful due to somatic afferent innervation, but visceral pleura is not painful due to visceral afferent innervation.

Pleuritis (pleurisy) involving only visceral pleura may not be painful because innervation is from visceral afferent nerves. However, on inspiration a sharp pain in the chest wall is felt in pleuritis involving parietal pleura because innervation is from somatic nerves. Roughening of the pleura results in a pleural friction rub heard with a stethoscope, and pleural adhesions may develop between inflamed visceral and parietal pleurae.

Pain in the thorax, abdomen, or shoulder on deep inspiration suggests a pleural origin. Shoulder pain can be referred from irritated diaphragmatic pleura. Pleural pain related to pneumonia or cancer of the lower lobe may be referred to the anterior abdominal wall.

Pleuritis may cause chest pain and pleural friction rub.

During bronchoscopy, the carina is a critical landmark, and a deviation in its position may indicate metastasis of lung cancer to the tracheobronchial lymph nodes at the bifurcation of the trachea.

Insertion of an endotracheal tube during surgery or in emergency situations protects air flow to and from the lungs. Insertion too deeply may result in only one lung being ventilated, possibly causing pneumothorax and the other main bronchus being obstructed to cause atelectasis (see VI.A.3. following). Inadvertent insertion into the esophagus may result in aspiration of stomach contents and aspiration pneumonia.

Distorted carina on bronchoscopy often indicates metastatic lung cancer.

The trachea may be compressed by an enlarged thyroid gland or by an aortic arch aneurysm.

An aspirated object or an endotracheal tube that is inserted too far is likely to enter the right main bronchus.

A tumor of the apex of the lung (Pancoast tumor) may involve the sympathetic chain and interrupt sympathetic innervation to the head, producing Horner syndrome (ipsilateral anhidrosis, miosis, ptosis, and vasodilation). The tumor also may involve the inferior roots of the brachial plexus, producing upper-extremity symptoms.

An apical lung tumor (Pancoast tumor) may cause Horner syndrome.

The cardiac notch allows a needle to enter the pericardium and heart through the left fifth intercostal space without damaging the lung and pleura.

Bronchopulmonary segments are independent functional and surgical units.

Patient position determines the location of inhaled foreign objects.

Gravity moves foreign material to different bronchopulmonary segments of the right lung depending on the patient’s position (Figure 2-8). In a standing or sitting patient, the posterobasal segment is involved; in the supine patient, the superior segment of the lower lobe; in the right-sided recumbent position, the middle lobe or posterior segment of the right upper lobe. The arrangement of segments also means that a patient can be optimally positioned for postural drainage of an infected bronchopulmonary segment aided by percussion of the chest wall over the segment.

Intersegmental veins are surgical landmarks for segmentectomies.

Pulmonary arteries carry deoxygenated blood to the lungs; pulmonary veins return the oxygenated blood to the heart.

Lung cancer may metastasize to the brain through the arterial system when cancer cells enter the pulmonary veins and are returned to the left side of the heart. From the aorta, cancer cells pass through the common and internal carotid arteries or the subclavian and vertebral arteries.

Bronchial arteries supply oxygenated blood to lung tissues.

Lung cancer may metastasize to the spinal cord and brain through the venous system if cancer cells enter a bronchial vein and pass to the azygos system. Cancer cells may then pass to the vertebral venous plexuses and ascend to the dural venous sinuses in the cranial cavity.

Left and right venous angles formed at the union of internal jugular and subclavian veins.

The upper lobe of the left lung has lymphatic drainage to the left bronchiomediastinal trunk, but the lower lobe of the left lung has lymphatic drainage mainly to the right bronchomediastinal lymph trunk.

Lung cancer cells can metastasize through arteries, veins, or lymphatic vessels.

Esophageal atresia results in polyhydramnios.

A congenital tracheoesophageal fistula is an abnormal communication between the trachea and distal esophagus usually associated with esophageal atresia (blind-ending esophagus) (Figure 2-9). The resulting regurgitation and aspiration of swallowed milk (and possible reflux of gastric contents into lungs) cause pneumonia. Because esophageal atresia prevents the fetus from swallowing and absorbing amniotic fluid in the small intestine, the condition is often accompanied by excess amniotic fluid (polyhydramnios). An acquired tracheoesophageal fistula may result from malignancy, infection, or trauma.

Tracheoesophageal fistula with esophageal atresia causes pneumonia.

Some infants born at 22-25 weeks survive with intensive care but often suffer lifelong disability.

Pulmonary surfactant produced by type II alveolar cells reduces surface tension to prevent alveolar collapse.

Surfactant reduces surface tension to allow inflation of alveoli. Neonatal respiratory distress syndrome (hyaline membrane disease) results from deficient surfactant production by type II alveolar cells in premature infants. Glucocorticoid treatment in at-risk pregnancies speeds up lung development and surfactant production. Treatment with artificial surfactant reduces neonatal mortality.

Maternal glucocorticoid treatment may prevent neonatal respiratory distress syndrome.

The diaphragm is the primary muscle of inspiration.

Patient with dyspnea may lean on upper extremities to allow accessory muscles to aid in respiration.

In spontaneous pneumothorax, air enters the pleural cavity because of rupture of a bleb on a diseased lung. It occurs commonly in tall, slender males under 40 who smoke and Marfan syndrome patients.

Spontaneous pneumothorax occurs in tall, slender male smokers under 40.

Tension pneumothorax is a life-threatening condition in which air enters the pleural cavity during inspiration due to a penetrating wound but cannot exit during expiration. Air pressure increases on the affected side, and the mediastinum shifts away, compressing the contralateral lung and compromising venous return to the heart (Figure 2-10). Bedside ultrasonography often replaces chest radiographs for diagnosis. The patient complains of chest pain and dyspnea. Jugular venous distention and a tracheal shift

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