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Thoracic Cavity Organization
- 3 major spaces
- right / left pulmonary cavities
- 2 apertures
- superior / inferior
- (Ribs 1 - 7)Attach directly to the sternum via costal cartilages
- (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
Superior Atypical Ribs
- 1st Rib:- grooves for subclavian BVs
- - 1 articular facet on head
- - tubercles for ant. / mid. scalene
- 2nd Rib:- 1 articular facet
- - tubercle for posterior scalene
Inferior Atypical Ribs
(Ribs 1-2, 10-12
- Rib 10:
- - 1 articular facet
- Ribs 11 & 12:- 1 articular facet
- - floaters
- - no necks / tubercles
Which is the only atypical rib to have similar structure at the head as the typical ribs?
- Rib 2
- (2 articular facets)
Anatomical appearance of the breast
- - 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
Anatomical levels of breast / nipples
Breast: ribs 2-6
Nipple: 4th intercostal space (males!)
Arterial supply to the breast
- 1. Lateral thoracic a. (lateral mammary branches)
- 2. Internal thoracic a. (medail mammary branches)
- 3. Post. intercostals (2-4 intercostal spaces)
Venous drainage to the breast
- 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
Innervation of the breast
Ant. / Lat. cutaneous branches of 2nd - 6th intercostal nn.
(sensory / smooth muscle signals)
Innervation of the nipple
4th intercostal n.
Lymphatic drainage of the breast
- 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
Anterior muscles of forceful respiration
- Pec. major
- clavipectoral fascia
- Pec. minor
Major contributors of respiration
- External intercostals - membranous anteriorly
- Internal intercostals - membranous posteriorly
- Innermost intercostals - membranous anteriorly & posteriorly
Which intercostal muscles are continuous w/ abdominal muscles?
External intercostals (external oblique)
Internal intercostals (internal oblique)
Arterial supply to thorax
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.)
What are the terminal branches of the internal thoracic aa. in the thorax?
1) superior epigastric aa.
- 2) musculophrenic aa.
- - supplies the lower spaces
- - anastamoses w/ post. intercostals)
Venous drainage of thorax
- 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
Innervation of thorax
- - 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)
Intercostal Spaces: Boundaries & Contents
- lateral border = internal intercostal m.
- medial border = innermost intercostal m.
- Contents (superior to inferior)
- VAN + collateral branches
Structures that pass thru diaphragm @ T8
- Caval hiatus passes through central tendon:
- - IVC
- - R. Phrenic n.
- - Pericardiacophrenic a.
Structures that pass thru diaphragm @ T10
- Esophageal hiatus passes through muscular diaphragm:- Esophagus
- - Vagus n.
Structures that pass thru diaphragm @ T12
- Aortic hiatus passes posterior to diaphragm:- Thoracic aorta
- - Thoracic duct
Innervation / Blood Supply to Diaphragm
- Blood supply
- - branches of abdominal aorta (major)
- - thoracic aorta / intercostals / pericardiacophrenic / musculophrenic (minor)
- - Phrenic n. (C3-C5) penetrate diaphragm and innervate it from underneath
At what point do the parietal and visceral pleura become continuous?
- 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 6th rib (MCL)
- Below 8th rib (MAL)
Lobes of the lungs
- Each lung has 10 bronchopulmonary segments
- Right Lung (3 lobes)
- - separated by horizontal / oblique fissures
- Left Lung (2 lobes)
- - separated by oblique fissure
Right Lung - Mediastinal surface
- - groove for SVC
- - cardiac impression
- - pulmonary a.
- - pulmonary v.
- - groove for azygos arch
- - groove for esophagus
- - Bronchus
Left Lung - Mediastinal surface
- Anteriorly:- large cardiac impression
- - groove for subclavian a.
- - pulmonary v.
- - lingula
- Posteriorly:- groove for aortic arch / descending aorta
- - pulmonary a.
- - bronchus
- - pulmonary v.
Right bronchial tree
- Trachea -> R. main bronchus
- -> R. superior (eparterial) bronchus
- -> R. middle / inferior bronchi
Arterial supply to lung
- Bronchial arteries
- (branches of descending aorta)
Venous drainage of lung
- Bronchial veins
- (right into azygos v. / left into hemiazygos system)
Why can't blood oxygenation reach 100%?
- Inside lungs, bronchial veins unite w/ pulmonary v.
- Delivers low oxygenated blood to right atrium
- - Vagus n. (constrict)
- - sympathetic trunks (dialate)