Anatomy of Breathing - Lecture 17 Flashcards
What are the lungs?
○ Located in thorax
○ Separated by mediastinum and heart
○ Extend from neck to diaphragm
○ Diaphragm separates throacic and abdominal cavities
What makes up the lungs?
○ Conical shaped with soft, spongy texture
○ Apex of the lung lies above the clavicle
○ Diaphragmatic surface: sits on the diaphragm
○ Costal surface: lies adjacent to the ribs
○ Mediastinal surface: faces the mediastinum
What are the features of the right lung?
○ Wider and shorted than the left lung: liver underneath the diaphragm
○ Three lobes: superior, middle, inferior
○ Two fissures: oblique and horizontal
What are the features of the left lung?
○ Narrower and longer than the right lung
○ Two lobes: superior and inferior
○ One fissure: oblique
What is the hilum of the lung?
○ Located on the mediastinal surface
○ The area where the pulmonary vessels, bronchi, bronchial vessels, lumpathics and nerves enters/leaves the lung
What are the physical properties of the lungs?
○ Compliance: the ability of the lungs to expand
○ Elasticity: elastic tissue allows lung expansion during inspiration and recoil during expiration
What factors can affect compliance?
○ Connective tissue structure of the lungs
○ Level of surfactant
○ Mobility of thoracic cage
What is the pleura?
Double layered serous membrane
What makes up the serous membrane?
○ Visceral pleura: adheres to the lung
○ Parietal pleura: attaches to the thoracic wall and diaphragm
○ Pleural cavity: Thin layer of serous fluid that holds the two layers together
What are the functions of the pleura?
○ Reduces friction during breathing
○ Creates a pressure gradient which assists in ventilation
○ Compartmentalises each lung: reduces spread of infection
What is the bony thorax and what does it consist of?
○ Forms the skeleton of the chest wall
Consists of:
○ Sternum
○ Ribs (12 pair)
○ Thoracic vertebrae (12)
What is the sternum and what does it consist of?
○ Breast bone
Consists of:
○ Manubrium
○ Body
○ Xiphisternum
What are the ribs?
○ Attached by the head and tubercle to the thoracic vertebrae
○ Slope downwards and forwards
How are the ribs attached?
○ Ribs 1-10 attached by costal cartilage to the sternum:
- 7 pairs true
- 3 pairs false
- 2 floating
What is the thoracic vertebrae?
○ Head of rib articulates with the body of the thoracic vertebrae
○ Tubercle of rib articulates with the transverse process of the thoracic vertebra
○ Synovial joints between the ribs and vertebrae to allow movement of ribs
What are intercoastal muscles and what does it consist of?
○ Span the spaces between the ribs
○ External intercostal muscles: superficial layer
○ Internal intercostal muscles: middle layer
○ Innermost intercostal muscles: deep layer
Which direction does the external intercostal run?
Downwards and fowards
Which direction does the internal intercostal run?
Downwards and backwards
How is blood and nerves supplied to the intercostal muscles?
○ Nerves and vessels course between the internal intercostal and innermost intercostal muscles
○ Protected by the ribs
○ Supply the muscles, adjacent skin and pleura
What are the features of the diaphragm?
○ Separates the thorax from the abdomen
○ Dome-shaped skeletal muscle with a central tendon
○ Attached to the xiphisternum, costal margin, 11th and 12th ribs and the lumbar vertebrae
○ Openings for inferior vena cava, oesophagus & aorta
○ Fibrous pericardium fused to central tendon
○ Innervated by the phrenic nerve
When does inspiration occur?
When intrapulmonary pressure is lower than atmospheric pressure
When does expiration occur?
When intrapulmonary pressure is greater than atmospheric pressure
How is intrapulmonary pressure altered?
Changes in thoracic volume
How can thoracic volume be altered?
Changes in:
○ Vertical diamter: top of thorax to diaphragm
○ Anterior posterior (AP) diameter: between sternum and vertebral column
○ Transverse diameter: left and right side of ribcage
