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