Ch 3-Thorax: Component Parts

Question 1

-Thoracic wall-

Answer 1

• 12 thoracic vertebrae
• 12 pairs of ribs
  
  • sternum: Manubrium of sternum angled posteriorlys forming sternal angle, a landmark
  • Costal cartilage
  • Ribs 2-9 have three articulations with vert col.
  • Ribs 1-7 articulate with sternum
  • Ribs 8-10 articulate with inferior margins of ribs above
  • Ribs 11-12 are floating
  • Intercostal spaces: Lie between adj ribs filled with intercostal muscles
  • Intercost nerves/arteries/veins lie in costal groove
    
    • Vein-
    • Artery-
    • Nerve
    • endothoracic fascia, superficial fascia

Question 2

-Functions:

Answer 2

• Breathing
• Protection of vital organs
• Conduit

Question 3

-Intercostal Muscles:

Answer 3

• 11 pairs External Intercostal: Superior, pass obliquely anteroinferiorly. Involved in inspiration.
• 11 Pairs Internal Intercostal: Pass in opposite direction, obliquely posteroinferiorly. Expiration
• Innermost Intercostal: Least distinct. Same orientation as Internal.
• Subcostales: Same plane as Innermost, span many ribs, on post. Thoracic wall. Parellal same course as Internal.
• Transverus thoracis: Anterior thoracic wall, same plane as Innermost. Originate from xiphoid process. Insert into costal cart of ribs 3 to 6. helps in inspiration.

Question 4

-Superior thoracic aperture-

Answer 4

• Consists of vert T1 post, medial Rib 1 each side, manubrium anteriorly
• Ribs slope inferiorly from posterior aspect to sternum. (Pump handle)
• Structures & Vessels pass between upper limb and thorax over rib 1.
  
  • Subclavian arteries/veins
  • Internal jugular vein-superior
  • Common carotid artery
  • axillary inlet
  • Esophogus
  • trachea
  • manubrium of Sternum
  • clavicle
  • corocoid process

Question 5

-Inferior thoracic aperture-

Answer 5

• Closed by diaphram. Structures pass posteriorly to diaphragm.
  
  • Skeletal elements:
    
    • T12 posteriorly
    • Rib 12, rib 11 posterorlaterally
      - Ribs 7-10 anterlaterally
    • xiphoid process
• Posterior margin of inferior thoracic aperture is inferior to anterior margin
• Tilted superiorly

Question 6

-Diaphragm

Answer 6

• Central Tendon
• Right dome higher than left.
• Posterior attachment of diaphragm is inferior to ant attachment becoz of oblique angle.
• When contracted, thorax volume increases.
• Esophagus, inferior vena cava penetrate
• Aorta passes posteriorly

Question 7

-Mediastinum

Answer 7

• Horizontal plane through sternal angle between T4 and T5.

- Inferior divides into: Anterior Mediastinum, Middle Mediastinum, Posterior Mediastinum

Question 8

• Pleura cavitties

- Lined by membrane called Pleura.

Answer 8

• Parietal: walls of cavity
  - Costal part-ribs
  - Diaphragmatic part-diaphragm
  - Mediastinal-mediastinum
  - root of lung joins hilum of lung-where structures enter and leave lung
  - Cervical-cervical extenstion of pleura cavity.
  
  • Visceral: surface of lungs
    
    • Continuous with Parietal
• Lungs doesnt completely fill-recesses.
  
  • Costomediastinal recesses: Anteriorly on each side. Largest on left.
  • Costodiaphragmatic most important. Between costal and diaphragmatic pleura. Are deepest after expiration. Shallowest at inspiration.
  • Expiration: becomes larger

-Lungs attach to mediastinum by root.

Question 9

Relationship to other regions:

• Neck
• Upper limb

Answer 9

-Pleural cavity extends 2-3cm above rib 1

• Axillary inlet lies on each side of superior thoracic aperture:
  
  • superior scapulat posteriorly
  • clavicle anteriorly
  • lateral rib medially
  • Structures pass over rib 1

Question 10

Relationship to other regions:

-Abdomen/Diaphragm

Answer 10

• Inferior vena cava: pierces central tendon to right side mediastinum at T8 (Caval Opening)
• Esophagus/Vagus nerves: penetrates diaphargam leaving mediastinum at TX (Esophageal hiatus)
• Aorta/thoracic duct/(aygos&hemizygous veins) passes posteriorly at T12 (Aortic hiatus)
• Arterial Supply:
  
  • From pericardiacophrenic & musculophrenic arteries (branches of internal thoracic arteries)
  • Superior phrenic arteries
  • Inferior phrenic arteries
• Venous Drainage:
  
  • Into brachiocephalic veins, azygous veins, ab veins (L suprarenal vein & inferior vena cava)

Question 11

Relationship to other regions:

• Breast
  
  • On pectoral region, each side of anterior thoracic wall.

Answer 11

• consists of mammary glands, 20 lactiferous ducts that open into nipple, surrounded by areola.
• Connective tissues around lobules and ducts condense to form suspensory ligaments of breast
• Retromammary space separates breast from deep fascia, and provides deg of movement
  
  • bases extends from ribs 2-6

Question 12

Breast cancer solutions & staging:

Answer 12

• Surgery
• Chemotherapy
• Radiotherapy
  
  • Size of tumor
  • exact site of tumor
  • # and sites of lymph node spread
  • organs which tumor spread
  • Peau d’ orange=on surface
  • cancer en cuirasse-hard,woody texture.