External structures
- Provide the external borders for the lungs
- Borders comprised of:
- Sternum
- Provides anatomical landmarks for auscultation
- Rib cage
- 12 ribs and adjacent intercostal musculature assist with movement of air
- Provide anatomical landmarks for auscultation
- Vertebral column
- Provides posterior border
- Shoulder girdle
- Provides attachment for accessory muscles to support in movement of air
Diagram of pulmonary system
Internal structures:
- Upper airways
- Entry point for air
- Comprised of nose, mouth, pharynx, and larynx
- Lower airways
- Continue the conduction of air in which air gas exchange occurs
- Comprised of trachea, bronchioles, alveolar ducts, and alveolar sacs
- Internal supporting structures
- Each lung is comprised of lobes
- Right lobe has 10 segments
- Left lobe has 8 segments
- Pleura
- Parietal pleura located on the outer surface and provides barrier to thoracic cage, diaphragm, and mediastinal border
- Visceral pleura located on the inner surface and provides barriers to lung
Muscles and mechanics of ventilation
Primary muscles of inspiration
- Diaphragm
- When contracted, muscle is pulled downward- inhalation
- Leads to protruded abdominal cavity
- When relaxed, muscle in dome shape- exhalation
- Takes the natural shape of lower rib cage
- Intercostals
- Aid in movement of rib cage
- Accessory muscles
- Scalenes
- Sternocleidomastoid
- Trapezius
- Serratus anterior
- Pectorals muscles
Primary muscles for exhalation
- Passive recoil of activated inspiratory muscles
- Accessory muscles that can be utilized during disease state or exercise
- Quadratus lumborum
- Abdominal muscles
- Sections of intercostals
Mechanism of breathing
- Inspiration
- Activation of muscles to provide sufficient pressure gradient to allow for air to enter the lungs
- Causes the movement of bony thorax outward
- Exhalation
- Passive recoil of the activated muscle to allow to leave the lungs
- Causes the movement of bony thorax inward
Pulmonary function test - ventilation
