Respiratory System Anatomy

Question 1

Function of the Thorax

Answer 1

Protection for heart, lungs and large blood vessels
Supports shoulder girdle - upper limbs
Provides origin/insertion points for muscles
Resists negative pressure from from lungs on expiration

Question 2

Ribs

Answer 2

12 pairs
7 true ribs
3 false ribs - not in direct contact with sternum
2 floating ribs - not in direct contact with sternum. Protect kidneys, left more than right because right has protection from liver, left higher up.

Question 3

Costovertebral Angle

Answer 3

Helps with ventilation. Not 90° to the vertebral body. Allows for pump-handle and bucket-handle movements.
Use less than 1% of ATP for ventilation because of this angle.

Question 4

Diaphragm Origin and Insertion

Answer 4

ORIGIN
Lumbar:
• Medial part: vertebral bodies L1-L3, 2nd and 3rd intervertebral discs, anterior longitudinal ligament
• Lateral part: 3 tendinous arches
Costal: inner aspect of lower six ribs (rib 7-12).
Sternal: posterior aspect of xiphoid
INSERTION
Central tendon (attaching to pericardium)

Question 5

Diaphragm - Functions

Answer 5

Separates thoracic cavity from abdominal cavity.
Closes inferior thoracic aperture.
Main muscle of ventilation, respiration.
Helps keep posture.
Puts pressure on esophagus to prevent acid flux.

Question 6

Diaphragm - Inspiration

Answer 6

Moves downward (expanding ribs).
Contracts and becomes flat.
Volume in lungs goes up, pressure in lungs goes down.
Atmospheric pressure higher than lung pressure.
Air entering lungs from high to low pressure.

Question 7

Diaphragm - Expiration

Answer 7

Moves upwards while exhaling.
Relaxes and gets back its initial shape (dome).
Volume in lungs goes down, pressure goes up.
AI

Question 7

Diaphragm - Expiration

Answer 7

Moves upwards while exhaling.
Relaxes and gets back its initial shape (dome).
Volume in lungs goes down, pressure goes up.
Atmospheric pressure < lung pressure
Air leaving lungs from high pressure to low.

Question 8

Quite Inhilation

Answer 8

Active - muscles contract.

Question 9

Quite Exhilation

Answer 9

Passive - no muscle contractions.

Question 10

What are the names of the hiatus’ in the diaphragm and at which level are they?

Answer 10

Caval hiatus T8
Oesophageal hiatus T10
Aortic hiatus T12

Question 11

Caval Hiatus

Answer 11

T8
Passing through:
Inferior vena cava
Terminal branches of right phrenic nerve

Question 12

Oesophageal Hiatus

Answer 12

T10
Passing through:
Oesophagus
Right and left vagus nerve
oesophageal branches of left gastric artery/vein

Question 13

Aortic Hiatus

Answer 13

T12
Passing through:
Aorta
Thoracic duct

Question 14

Diaphragm Innervation

Answer 14

Phrenic nerve (left and right)
Arises from C3, C4, C5.
If there is high trauma on spine, lose innervation of the phrenic nerve, lose connection to medulla and diaphragm (mechanical ventilator).

Question 15

Accessory Inspiration Muscles

Answer 15

Forced Inspiration

• Scalene
• Sternocleidomastoid
• Trapezius
• Pectoralis major, minor
• Inferior fibers of serratus anterior, latissimus dorsi

Question 16

Accessory Expiration Muscles

Answer 16

Forced Expiration

• Transversus abdominis
• Internal oblique
• External oblique
• Rectus abdominis
• Inner intercostal muscles

Question 17

Why do we use accessory muscles?

Answer 17

If diaphragm and external intercostal muscles need help for full expansion during inspiration (exercise or disease)
If air needs to be exhaled fast.
10x more energy expenditure.

Question 18

Pleura

Answer 18

Cannot ventilate without it.
2 layers:
- Parietal pleura (contact to rib cage)
- Visceral pleura (contact with lung) 
Decreases friction.

Question 19

Pleura Cavity

Answer 19

8-10 ml pleural fluid.
No connection between right and left.
Allows lungs to slide inside the ribcage.

Question 20

Why are the lungs always open?

Answer 20

Because the pleura pressure is negative, sucks the two layers together, keeping the lungs always open.
Atmospheric pressure is more than pleura pressure.
Eccentric elastic forces of the ribcage pull against the concentric elastic force of the lung, balanced by negative pleura pressure (-5cmH20).

Question 21

Blood Supply of Pleura

Answer 21

Parietal: intercostal arteries
Visceral: bronchial circulation

Question 22

Nerve Supply of Pleura

Answer 22

Parietal: Intercostal nerves - phrenic nerve
Visceral: Intercostal nerves (no sensory innervation)

Question 23

Mediastinum

Answer 23

The mediastinum is an area found in the midline of the thoracic cavity, that is surrounded by the left and right pleural sacs.
It is divided into the superior and inferior mediastinum by a transverse plane that extends from the sternal angle to lower border of T4.

Question 24

Superior Mediastinum

Answer 24

Thymus
Trachea
Esophagus
Aortic arch
Brachiocephalic trunk
Left common carotid artery
Left subclavian artery
Superior vena cava
Phrenic nerves
Vagus nerves
Thoracic duct

Question 25

Anterior (Inferior) Mediastinum

Answer 25

Inferior portion of thymus
Lymph nodes
Mediastinal branches of internal thoracic vessels
Sternopericardial ligaments

Question 26

Middle (Inferior) Mediastinum

Answer 26

Pericardial sac
Heart
Origins of great vessels: pulmonary trunk, ascending aorta, pulmonary veins, superior vena cava, inferior vena cava
Tracheal bifurcation and main bronchi

Question 27

Posterior (Inferior) Mediastinum

Answer 27

Descending thoracic aorta and its branches
Thoracic duct & cisterna chyli
Esophagus and esophageal plexus
Vagus nerves