Thorax, Pleural Cavity

Bones sternum - all landmarks 12 ribs, costal cartilages - all landmarks 12 thoracic vertebrae - all landmarks

Borders 1. superior thoracic aperture ( thoracic inlet) - opening to neck, superior borders of: manubrium, 1st pair ribs, costal cartilages, 1st thoracic vertebrae 2. inferior thoracic aperture / thoracic outlet - opening to abdomen inferior borders of: T12 vertebra; ribs 12, 11; costal cartilages #10, 9, 8, 7, xiphoid

Diaphragm muscle + fibrous connective tissue - separates thoracic & abdominal cavities domed in center

Pleural sacs a continuous serous membrane folded back on itself to form a double layer 1. visceral pleura - inner layer - forms external surface covering of lung  2. parietal pleura - outer layer - forms inner lining of thoracic wall  3. both layers meet at root

Pleural sacs Pleural cavities: potential space - contains thin serous fluid layer, slight negative pressure Regions of parietal pleura are named by surrounding structures: cervical/apical, costal, diaphragmatic, mediastinal Recesses: narrow clefts at edges of pleura, where lungs don't extend costodiaphragmatic - most inferior, between costal & peripheral border of diaphragm, first place to find fluid accumulation in X-ray costomediastinal - most anterior, medial, in front of mediastinum

Thoracocentesis

Mediastinum central structures between two pleural sacs, sternum & vertebral bodies Heart: pericardium, chambers, blood supply, pulmonary vessels, ligamentum arteriosum vagus nerve, recurrent laryngeal nerve Trachea Esophagus Phrenic nerve: in mediastinal pleura -- to pericardium

Blood Vessels Intercostal arteries - anterior & posterior, + subcostal (12th) 1st and 2nd posterior intercostal artery - branch off supreme (superior) intercostal artery, which branches off costocervical trunk of subclavian artery 3d - 11th posterior intercostal, & subcostal artery - are branches of thoracic aorta

Blood Vessels 1st- 5th (or 6th) anterior intercostal artery: = branches of internal thoracic artery 6th (or 7th) - 9th anterior intercostal arteries - are branches of musculophrenic artery - anterior & posterior intercostal arteries terminate by anastomosing with each other There are no anterior intercostal arteries in the most inferior two intercostal spaces. These areas are provided by posterior intecostal arteries only.

Blood Vessels internal thoracic artery (branch of subclavian): divides behind #6 costal cartilage: a. superior epigastric artery b. musculophrenic artery

Nerves Intercostal nerves = ventral rami of thoracic nerves 1-11 to intercostal muscle, skin travel in costal grooves, between internal & innermost intercostal muscle.

Herpes Zoster Shingles Viral infection of Chicken pox virus Affect along intercostal nerve

Muscles External intercostalis Internal intercostalis Innermost intercostalis Subcostalis Transversus thoracis

External intercostalis ORIGIN Inferior border of ribs as far back as posterior angles INSERTION Superior border of ribs below, passing obliquely downwards and backward ACTION Fix intercostal spaces during respiration. Aids forced inspiration by elevating ribs NERVE Muscular collateral branches of intercostal nerves

Internal intercostalis ORIGIN Inferior border of ribs as far back as posterior angles INSERTION Superior border of ribs below , passing obliquely downwards and backwards ACTION Fix intercostal spaces during espiration. Aids forced inspiration by elevating ribs NERVE Muscular collateral branches of intercostal nerves

Innermost intercostalis ORIGIN Internal aspect of ribs above and below INSERTION Internal aspect of ribs above and below ACTION Fix intercostal spaces during respiration NERVE Muscular collateral branches of intercostal nerves

Subcostalis ORIGIN Internal posterior aspects of lower six ribs INSERTION Internal aspects of ribs two to three levels below ACTION Depresses lower ribs NERVE Muscular collateral branches of intercostal nerves

Transversus thoracis ORIGIN Lower third of inner aspect of sternum and lower three costosternal junctions INSERTION Second to sixth costal cartilages ACTION Depresses upper ribs NERVE Muscular collateral branches of intercostal nerves