L1.2 Thoracic Wall

Question 1

What defines the thoracic wall?

Answer 1

Thoracic cage + coverings

Question 2

Function of the thoracic wall

Answer 2

• Protects, and forms the mechanical basis of breathing

Question 3

True, false and floating ribs

Answer 3

• 1-7 (true) → attach directly to the sternum via own costal cartilage
• 8-10 (false) → Attach to costal cartilage of ribs above
• 11 & 12 (floating) → Have no ANT attachments (contributes to mobility of thoracic cage)

Question 4

Typical and atypical ribs

Answer 4

• 3-9 (typical)
  
  • curved & flat
  • Head → has multiple facets (S & I & articular)
  • INF aspect has the costal groove (vessels run through it)
• 1, 2, 10-12 (atypical)
  
  • e.g. 1:
  • Grooves for subclavian vessels, scalene tubercle

Question 5

Sternum

Answer 5

• Manubrium, body, xyphoid
• 1st rib articulation at manubrium
• 2nd rib articulation b/w manubrium and body
• Sternal angle of Louis: Angle b/w manubrium & body

Question 6

Distinction of the thoracic vertebrae

Answer 6

• Distinction are the rib articulations
  
  • S/I demi-facets
  • 2 points of rib articulations
  • Coronal → permits rotation

Question 7

External intercostal muscles

Answer 7

• From ribs above to below, antero-inferiorly
• Medially continues as external intercosatal membrane
• For ribs elevation

Question 8

Internal intercostal muscles

Answer 8

• Fibres direction opposite of external intercostal muscles
• Run throughout the length
• For ribs depression, BUT MED helps elevation

Question 9

Innermost intercostal muscles

Answer 9

• Fibres direction same as internal
• Fragmented, not full length, deficient POS (exposes N)
• Functionally same as internal

Question 10

Intercostal vessels

Answer 10

• VAN (Sup → Inf)
• B/w internal & innermost muscles
• Nerves are just extension of spinal Nerve (Ventral Ramus)
  
  • Branches off to supply skin → define dermatomes

Question 11

Features of the breasts

Answer 11

• Mammary glands under skin on ANT thoracic wall (on fascia SUP to pec maj)
• 15-20 lobules which contains alveoli at the end of duct
  
  • Alveoli secretes milk into duct systems
• Each lobule drained by single duct (lactiferous duct → opens directly on nipple)

Question 12

What is the retromammary space?

Answer 12

• area which can be opened up for implants
• B/w pec maj & mammary glands

Question 13

Location of breasts

Answer 13

• 1/3 breast on serratus ANT laterally
• Rest MED to LAT border to sternum (Ribs 2-6)

Question 14

Features of the nipple

Answer 14

• In 4th intercostal space in mid-clavicular line
• Only applies for nulliporous women (women with no baby)
• Surrounded by S.M → erects it
• No fat/hair/sweat glands

Question 15

Areola

Answer 15

• Pigmented area around nipple
• Sebaceous gland → oil for lubrication

Question 16

Is it harder or easier to check for cancers in younger or older women

Answer 16

• Younger women with dense tissues → harder to identify breast cancer growing

Question 17

BS to the breasts

Answer 17

• MED → internal thoracic A (mammary A) from behind sternum
• LAT → branches of intercostal A & Subclavial A

Question 18

Venous drainage

Answer 18

Same as BS

Question 19

Lymphatics of the breasts

Answer 19

• Subareolar plexus → parasternal/axillary nodes (75% to axillary) → subclavian trunk → R.lymphatic duct/Thoracic duct

Question 20

Breast cancer

Answer 20

• Derived from glandular epithelium in lobules, appeared as jagged mass on mammogram
• Could damage suspensory ligament → could invert nipple, skin thickened or dimpled
  
  • Anchors lobules to fascia
• Cancer cells can lodge in nodes → metastases → can be palpated

Question 21

Breast cancer in men

Answer 21

• Still can get breast cancer
• Usually no glandular development
• Only small duct development → but cancer can arise from the epithelium of the duct

Question 22

Thoracic dermatome landmark

Answer 22

• T4 - teets
• T10 - Bellybutton

Question 23

What do muscles of the ribs help to do

Answer 23

• Muscles of the ribs protect & aids in breathing

Question 24

Muscles of the ribs assisting in elevation and depression

Answer 24

• Pec maj/min → when humerus is fixed
• Seratus ANT → when scapular is fixed
  
  • Both expands thoracic cage when contracted → helps get extra air in
• Serratus POS
  
  • SUP → elevate ribs (inspiration)
  • INF → depress ribs (expiration)