Thoracic Wall & Lungs

• 3 major spaces
• mediastinum
• right / left pulmonary cavities
• 2 apertures
• superior / inferior

• Vertebrocostal
• (Ribs 1 - 7)
• Attach directly to the sternum via costal cartilages

• Vertebrochondral
• (Ribs 8 - 10)
• Attach to the costal margin

• (Ribs 11 & 12)
• Do not attach to the sternum

• (Ribs 3 - 9)
• - Head (2 facets)
• - Neck
• - Tubercle
• - Body / Angle
• - Costal groove
• - Costal cartilage

(Ribs 1-2, 10-12)

• 1^st Rib:
• - grooves for subclavian BVs
• - 1 articular facet on head
• - tubercles for ant. / mid. scalene

• 2^nd Rib:
• - 1 articular facet
• - tubercle for posterior scalene

(Ribs 1-2, 10-12)

• Rib 10:
• - 1 articular facet

• Ribs 11 & 12:
• - 1 articular facet
• - floaters
• - no necks / tubercles

• Rib 2
• (2 articular facets)

• - mainly subcutaneous fat
• - modified apocrine sweat gland
• - lobules drains into lactiferous ducts
• - supported by suspensory ligaments
• - 2/3 pec. major & 1/3 serratus ant.
• - retromam. space = movement
• - lateral region = axillary tail

Breast: ribs 2-6

Nipple: 4^th intercostal space (males!)

• 1. Lateral thoracic a. (lateral mammary branches)
• 2. Internal thoracic a. (medail mammary branches)
• 3. Post. intercostals (2-4 intercostal spaces)

• 1. Axillary v. (via lat. mammary vv.)
• 2. Internal thoracic v. (via medial mammary vv.)

Venous drainage can reach the azygous system via intercostal veins

Ant. / Lat. cutaneous branches of 2^nd - 6^th intercostal nn.

(sensory / smooth muscle signals)

4^th intercostal n.

• Subareolar lymphatic plexus
• 75% -> axillary nodes -> r. lymphatic / thoracic ducts
• (some in parasternal nodes)

Lat. branches of post. intercostals -> azygous system -> thoracic duct

some drainage into subdiaphragmatic nodes / liver

• Pec. major
• clavipectoral fascia
• Pec. minor

• External intercostals
• - membranous anteriorly
• Internal intercostals
• - membranous posteriorly
• Innermost intercostals
• - membranous anteriorly & posteriorly

External intercostals (external oblique)

Internal intercostals (internal oblique)

2 main sources:

• posterior intercostal aa.
• - most arises from thoracic a.
• - upper 2 arise from superior thoracic a. (branch of costocervical trunk)

• anterior intercostal aa. (usually paired)
• - arises form internal thoracic aa. (subclavian aa.)

1) superior epigastric aa.

• 2) musculophrenic aa.
• - supplies the lower spaces
• - anastamoses w/ post. intercostals)

• Parallels arterial supply except for azygos system
• Ultimately drains via 2 routes:

• 1) Internal thoracic vv.
• - drains into brachiocephalic vv.

• 2) Azygos system
• - drains into superior vena cava

• - intercostal n. (ant. rami T1-11)
• - subcostal n. (ant. rami T12)

• - intercostal branches carry sympathetic motor to smooth muscle
• (i.e. vasculature / erector pili / hair follicles)

• lateral border = internal intercostal m.
• medial border = innermost intercostal m.

• Contents (superior to inferior)
• VAN + collateral branches

• Caval hiatus passes through central tendon:
• - IVC
• - R. Phrenic n.
• - Pericardiacophrenic a.

• Esophageal hiatus passes through muscular diaphragm:
• - Esophagus
• - Vagus n.

• Aortic hiatus passes posterior to diaphragm:
• - Thoracic aorta
• - Thoracic duct

• Blood supply
• - branches of abdominal aorta (major)
• - thoracic aorta / intercostals / pericardiacophrenic / musculophrenic (minor)

• Innervation
• - Phrenic n. (C3-C5) penetrate diaphragm and innervate it from underneath

• Hilum of the lung
• (T5-T7) pleura reflects back on itself
• extends inferiorly as pulmonary ligament

• - loose CT layer
• - separates the parietal pleura from internal surface of thoracic wall

• Below 6^th rib (MCL)
• Below 8^th rib (MAL)

• Each lung has 10 bronchopulmonary segments
• Right Lung (3 lobes)
• - separated by horizontal / oblique fissures

• Left Lung (2 lobes)
• - separated by oblique fissure

• Anteriorly:
• - groove for SVC
• - cardiac impression
• - pulmonary a.
• - pulmonary v.

• Posteriorly:
• - groove for azygos arch
• - groove for esophagus
• - Bronchus

• Anteriorly:
• - large cardiac impression
• - groove for subclavian a.
• - pulmonary v.
• - lingula

• Posteriorly:
• - groove for aortic arch / descending aorta
• - pulmonary a.
• - bronchus
• - pulmonary v.

• Trachea -> R. main bronchus
• -> R. superior (eparterial) bronchus
• -> R. middle / inferior bronchi

• Bronchial arteries
• (branches of descending aorta)

• Bronchial veins
• (right into azygos v. / left into hemiazygos system)

• Inside lungs, bronchial veins unite w/ pulmonary v.
• Delivers low oxygenated blood to right atrium

• Parasympathetics
• - Vagus n. (constrict)

• Sympathetics
• - sympathetic trunks (dialate)