L2.1 Diaphragm

Question 1

Structure of the domes

Answer 1

• R dome is higher (liver beneath) than L dome (heart apex above)
• Muscles project twds central tendon (apopneurotic connective tissue)

Question 2

Attachments of the diaphragm

Answer 2

• Xyphoid & Costal margin
• Ribs
• Transverse process

Question 3

Features of the POS part of the diaphragm

(Arcuate ligament)

Answer 3

• Arcuate ligament arches over psoas major & quadratus lumborum
  
  • 2 LAT → over Q.L
  • 2 MED → over psoas maj
  • 1 Median → over descending aorta

Question 4

Crura

Answer 4

• Median arcuate lig attaching to:
  
  • L1-2/3 (L.crus)
  • L1-3/4 (R.crus)

Question 5

Structure that pierces the diaphragm: T8

Answer 5

• IVC
• Diaphragm helps pump blood into IVC
  
  • When diaphragm move down → ↑pressure in ab, ↓pressure in thorax → blood moves up
  • Also pulls open IVC during inhalation

Question 6

Structure that pierces the diaphragm: T10

Answer 6

• Oesophagus
  
  • R.crus over & around
  • L.crus beneath
    
    • Crura forms sphincter → when diaphragm contracts → closes oesophagus (functional sphincter)

Question 7

Structure that pierces the diaphragm: T12

Answer 7

• Aorta
  
  • Behind diaphragm

Question 8

Nerves that pierces the diaphragm

Answer 8

• Phrenic N
  
  • R → within central tendon
  • L → pierces muscular bit
• Sym trunk
  
  • Under medial arcuate ligament

Question 9

Where does the azygous V pierce the diaphragm

Answer 9

• Pierces crura

Question 10

Innervation of the diaphragm

Answer 10

• Mostly by phrenic N (C3,4,5)
  
  • All motor
  • Sensory to central part & pericardium
  • ANT to subclavian A & root of lungs
• Branches of lower intercostal N (N surrounding body wall)
  
  • Supplies peripheral sensory

Question 11

What is the mechanism of breathing

Answer 11

• Movement of air: along pressure gradient
• Air In passively, lung pressure changed actively
• Parietal pleura moves → moves visceral pleura (due to adhesive fluid in the space) → moves lung

Question 12

What is quiet breathing

Answer 12

• Diaphragm = main determinant of quiet breathing
• Contract → pull on central tendon downwards
• Relax (can’t contract to relax as fibres directed down) → collapses lungs
  
  • Elasticity of lung (recoil) has significant contribution

Question 13

What is forced breathing

Answer 13

• Moves thoracic cage
• Elevating different ribs → creates different movements

Question 14

Pump-handle & Bucket-handle breathing mechanisms?

Answer 14

• Pump-handle (vertebral-sternal)→ sternum up & out (elevation of 2-6th ribs) → A.P dimensions
• Bucket-handle (vertebral-chondral) → ribs (7-10) move outwards → transverse dimension

Question 15

Accessory resp muscles?

Answer 15

• External ICM LAT to costochondral junction
  
  • Elevates ribs
• Internal ICM LAT
  
  • LAT → collapse ribs
  • MED → expand ribs
• Scalene muscles
  
  • Attaches to 1&2 ribs → elevation
• Abdominal muscles:
  
  • ↑pressure in abdomen → expiration
• SUP thoracic cage muscles → elevate muscles

Question 16

What are hiccups?

Answer 16

• Quick inspiration formed by spasmodic contractions of diaphragm
• By Irritation of
  
  • phrenic N
  • Diaphragm
  • resp centres of the brainstem