Respiratory System Anatomy Flashcards
Function of the Thorax
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
Ribs
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.
Costovertebral Angle
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.
Diaphragm Origin and Insertion
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)
Diaphragm - Functions
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.
Diaphragm - Inspiration
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.
Diaphragm - Expiration
Moves upwards while exhaling.
Relaxes and gets back its initial shape (dome).
Volume in lungs goes down, pressure goes up.
AI
Diaphragm - Expiration
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.
Quite Inhilation
Active - muscles contract.
Quite Exhilation
Passive - no muscle contractions.
What are the names of the hiatus’ in the diaphragm and at which level are they?
Caval hiatus T8
Oesophageal hiatus T10
Aortic hiatus T12
Caval Hiatus
T8
Passing through:
Inferior vena cava
Terminal branches of right phrenic nerve
Oesophageal Hiatus
T10 Passing through: Oesophagus Right and left vagus nerve oesophageal branches of left gastric artery/vein
Aortic Hiatus
T12
Passing through:
Aorta
Thoracic duct
Diaphragm Innervation
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).
Accessory Inspiration Muscles
Forced Inspiration
- Scalene
- Sternocleidomastoid
- Trapezius
- Pectoralis major, minor
- Inferior fibers of serratus anterior, latissimus dorsi
Accessory Expiration Muscles
Forced Expiration
- Transversus abdominis
- Internal oblique
- External oblique
- Rectus abdominis
- Inner intercostal muscles
Why do we use accessory muscles?
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.
Pleura
Cannot ventilate without it. 2 layers: - Parietal pleura (contact to rib cage) - Visceral pleura (contact with lung) Decreases friction.
Pleura Cavity
8-10 ml pleural fluid.
No connection between right and left.
Allows lungs to slide inside the ribcage.
Why are the lungs always open?
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).
Blood Supply of Pleura
Parietal: intercostal arteries
Visceral: bronchial circulation
Nerve Supply of Pleura
Parietal: Intercostal nerves - phrenic nerve
Visceral: Intercostal nerves (no sensory innervation)
Mediastinum
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.
Superior Mediastinum
Thymus Trachea Esophagus Aortic arch Brachiocephalic trunk Left common carotid artery Left subclavian artery Superior vena cava Phrenic nerves Vagus nerves Thoracic duct
Anterior (Inferior) Mediastinum
Inferior portion of thymus
Lymph nodes
Mediastinal branches of internal thoracic vessels
Sternopericardial ligaments
Middle (Inferior) Mediastinum
Pericardial sac
Heart
Origins of great vessels: pulmonary trunk, ascending aorta, pulmonary veins, superior vena cava, inferior vena cava
Tracheal bifurcation and main bronchi
Posterior (Inferior) Mediastinum
Descending thoracic aorta and its branches
Thoracic duct & cisterna chyli
Esophagus and esophageal plexus
Vagus nerves
