PART 2_CHAPTER 2

• Passage of lymph upward within the thoracic duct


  1. Aided by negative intrathoracic pressure

  2. Prevented from backflow by valves
• Openings in the diaphragm

  • Aortic opening
  • Esophageal opening
  • Caval opening
• Aortic opening


  • Anterior to the body of the 12th thoracic vertebra between the crura
  • Transmits the aorta, the thoracic duct, and the azygos vein
• Esophageal opening


  • At the level of the 10th thoracic vertebra in a sling of muscle fibers derived from the right crus
  • Transmits the esophagus, the right and left vagus nerves, the esophageal branches of the left gastric vessels, and the lymphatics from the lower third of the esophagus
• Caval opening


  • At the level of the 8th thoracic vertebra in the central tendon
  • Transmits the inferior vena cava and terminal branches of the right phrenic nerve
• In addition to these openings, the sympathetic splanchnic nerves pierce the crura, the sympathetic trunks pass posterior to the medial arcuate ligament on each side, and the superior epigastric vessels pass between the sternal and costal origins of the diaphragm on each side
• Internal thoracic artery


  Supplies the anterior wall of the body from the clavicle to the umbilicus<|>Branch of the first part of the subclavian artery in the neck<|>Descends vertically on the pleura behind the costal cartilages, a fingerbreadth lateral to the sternum<|>Ends in the sixth intercostal space by dividing into the superior epigastric and musculophrenic arteries
• Branches of the internal thoracic artery

  • Two anterior intercostal arteries for the upper six intercostal spaces
  • Perforating arteries, which accompany the terminal branches of the corresponding intercostal nerves
  • The pericardiacophrenic artery, which accompanies the phrenic nerve and supplies the pericardium
  • Mediastinal arteries to the contents of the anterior mediastinum (e.g., the thymus)
  • The superior epigastric artery, which enters the rectus sheath of the anterior abdominal wall and supplies the rectus muscle as far as the umbilicus
  • The musculophrenic artery, which runs around the costal margin of the diaphragm and supplies the lower intercostal spaces and the diaphragm
• Internal thoracic vein


  Accompanies the internal thoracic artery and drains into the brachiocephalic vein on each side
• Levatores costarum


  • 12 pairs of muscles
  • Each levator costa is triangular in shape and arises by its apex from the tip of the transverse process and is inserted into the rib below
  • Each raises the rib below and is therefore an inspiratory muscle
  • Nerve supply: Posterior rami of thoracic spinal nerves
• Serratus posterior superior muscle

  • Thin, flat muscle that arises from the lower cervical and upper thoracic spines
  • Fibers pass downward and laterally and are inserted into the upper ribs
  • It elevates the ribs and is therefore an inspiratory muscle
  • Nerve supply: Intercostal nerves
• Serratus posterior inferior muscle

  • Thin, flat muscle that arises from the upper lumbar and lower thoracic spines
  • Fibers pass upward and laterally and are inserted into the lower ribs
  • It depresses the ribs and is therefore an expiratory muscle
  • Nerve supply: Intercostal nerves
• A summary of the muscles of the thorax, their nerve supply, and their actions is given in Table 2.1
• The lymph drainage of the skin of the anterior chest wall passes to the anterior axillary lymph nodes; that from the posterior chest wall passes to the posterior axillary nodes
• The lymph drainage of the intercostal spaces passes forward to the internal thoracic nodes, situated along the internal thoracic artery, and posteriorly to the posterior intercostal nodes and the para-aortic nodes in the posterior mediastinum
• The sternal angle (angle of Louis) is the angle made between the manubrium and the body of the sternum and lies opposite the intervertebral disc between the 4th and 5th thoracic vertebrae
• The xiphisternal joint is the joint between the xiphoid process of the sternum and the body of the sternum and lies opposite the body of the ninth thoracic vertebra
• The subcostal angle is situated at the inferior end of the sternum, between the sternal attachments of the 7th costal cartilages
• The costal margin is the lower boundary of the thorax and is formed by the cartilages of the 7th, 8th, 9th, and 10th ribs and the ends of the 11th and 12th cartilages, with the lowest part formed by the 10th rib at the level of the third lumbar vertebra
• The clavicle is subcutaneous throughout its entire length and can be easily palpated, articulating at its lateral extremity with the acromion process of the scapula
• The suprasternal notch is the superior margin of the manubrium sterni and lies opposite the lower border of the body of the 2nd thoracic vertebra
• The 1st rib lies deep to the clavicle and cannot be palpated, while the lateral surfaces of the remaining ribs can be felt by pressing the fingers upward into the axilla and drawing them downward over the lateral surface of the chest wall
• The 12th rib can be used to identify a particular rib by counting from below, but in some individuals it is very short and difficult to feel, so an alternative method may be used to identify ribs by first palpating the sternal angle and the second costal cartilage
• In the midrespiratory position, the summit of the right dome of the diaphragm arches upward as far as the upper border of the 5th rib in the midclavicular line, but the left dome only reaches as far as the lower border of the 5th rib
• In the male, the nipple usually lies in the fourth intercostal space about 4 in. (10 cm) from the midline, but its position is not constant in the female
• The apex beat of the heart is normally found in the fifth left intercostal space 3.5 in. (9 cm) from the midline
• The anterior axillary fold is formed by the lower border of the pectoralis major muscle, and the posterior fold is formed by the tendon of the latissimus dorsi muscle as it passes around the lower border of the teres major muscle
• The spinous processes of the thoracic vertebrae can be palpated in the midline posteriorly, with the first one felt being the seventh cervical vertebrae (vertebra prominens)
• The scapula is flat and triangular in shape, with the superior angle lying opposite the spine of the second thoracic vertebra, the root of the spine lying on a level with the spine of the third thoracic vertebra, and the inferior angle lying on a level with the spine of the seventh thoracic vertebra
• Several imaginary lines are sometimes used to describe surface locations on the anterior and posterior chest walls, including the midsternal line, midclavicular line, anterior axillary line, posterior axillary line, midaxillary line, and scapular line
• Scapula


  Superior angle<|>Inferior angle
• Thoracic spine


  7<|>12
• Clavicle


  Acromion<|>Greater tuberosity of humerus
• Scapula


  Spine<|>Medial border<|>Lateral border
• Lines of orientation


  • Midsternal line
  • Midclavicular line
  • Anterior axillary line
  • Posterior axillary line
  • Midaxillary line
  • Scapular line
• Rib and costal cartilage identification

  • Sternal angle is an important landmark
  • 2nd rib can be felt from the sternal angle
  • 12th rib can usually be felt from behind
• Trachea


  Extends from lower border of cricoid cartilage to sternal angle
• Lung apex


  Projects into the neck, can be mapped out on the anterior surface
• Lung borders


  Anterior, lower, posterior
• Lung fissures


  Oblique fissure<|>Horizontal fissure (right lung only)