thoracic cavity

• What do the external intercostal muscles extend forward to?

  Costal cartilage
• What replaces the external intercostal muscles at the front?

  Anterio intercostal membrane
• Which nerves innervate the external intercostal muscles?

  Intercostal nerves
• What is the primary function of the external intercostal muscles?

  Responsible for forced and quiet inhalation
• How do the external intercostal muscles affect the chest cavity?

  They raise the ribs and expand the chest cavity
• In which direction do the fibers of the external intercostal muscles run?

  Up and towards the sternum
• What is the primary function of the internal intercostal muscles?

  Responsible for forced exhalation
• How do the internal intercostal muscles affect the chest cavity?

  They depress the ribs and decrease space in the chest cavity
• In which direction do the fibers of the internal intercostal muscles run?

  Down and away from the sternum
• What is unique about the innermost intercostal muscles compared to other layers?

  They are made of 3 portions
• What are the components of the neurovascular bundle in the intercostal region?

  • Intercostal vein
  • Intercostal artery
  • Intercostal nerve
• From which spinal nerves do the intercostal nerves arise?

  Anterior rami of thoracic spinal nerves T1-T11
• What is the subcostal nerve associated with?

  Ventral ramus of thoracic nerve 12
• Where is the subcostal nerve located?

  Below the last rib
• What type of branches do intercostal nerves have?

  Collateral, lateral cutaneous, anterior cutaneous, and muscular branches
• What does the collateral branch of intercostal nerves do?

  Runs parallel to the main nerve on the upper border of the rib
• What is the function of the lateral cutaneous branch of intercostal nerves?

  Innervates skin on the side of the thoracic wall
• What does the anterior cutaneous branch of intercostal nerves innervate?

  Skin near the midline of the chest
• What do muscular branches of intercostal nerves lead to?

  Intercostal muscles
• From where does the internal thoracic artery arise?

  1st part of the subclavian artery
• Where does the internal thoracic artery descend?

  Lateral to the sternum
• At which intercostal space does the internal thoracic artery terminate?

  6th intercostal space
• What happens at the 6th intercostal space regarding the internal thoracic artery?

  It divides into superior and musculophrenic arteries
• What is a dermatome?

  Area of skin innervated by sensory fibres from a single spinal nerve
• What is the mediastinum?

  Potential space between the lungs
• Where is the mediastinum located?

  Posterior to the sternum and anterior to the vertebral column
• What are the subdivisions of the mediastinum?

  Superior mediastinum and inferior mediastinum
• How is the inferior mediastinum further divided?

  Into anterior, middle, and posterior mediastinum
• What structures are located at the sternal angles?

  Start and end of aortic arch, division between superior and inferior mediastinum, upper margin of superior vena cava, bifurcation of pulmonary trunk, level of rib 2, and body of vertebra T4
• What is the superior mediastinum's location?

  From manubrium to T1-T4
• What structures are found in the superior mediastinum?

  Thymus, right and left brachiocephalic veins, superior vena cava, arch of aorta, trachea, esophagus, phrenic nerve, vagus nerve, left recurrent laryngeal branch of vagus nerve, thoracic duct
• What is the location of the inferior mediastinum?

  Superior to the diaphragm and inferior to the sternal angle
• What is located in the posterior mediastinum?

  Descending aorta, esophagus, thoracic duct, azygous and hemizygous veins, lower portion of vagus, sympathetic chains, posterior mediastinal nodes
• What does the anterior mediastinum contain?

  Portion of thymus, fat and connective tissue, mediastinal branches of internal thoracic vessels, sternopericardial ligaments
• What structures are found in the middle mediastinum?

  Pericardium, heart, ascending aorta, pulmonary trunk with left and right branches, SVC vein, termination of azygos, end of SVC
• What is the upper limit of the heart on the right side of the sternum?

  It reaches as high as the 3rd costal cartilage.
• What is the upper limit of the heart on the left side of the sternum?

  It reaches as high as the 2nd costal cartilage.
• How far is the upper limit of the heart from the sternal border?

  It is 1.2 cm from the sternal border.
• What is the right margin of the heart?

  It extends from the right 3rd costal cartilage to the 6th costal cartilage.
• How far is the right margin of the heart from the border of the sternum?

  It is 1.25 cm from the border of the sternum.