Session 2 ILOs - Chest and lung anatomy Flashcards
Describe how the structure of the nose and paranasal sinuses is conducive to warming, humidifying and filtering /trapping particles in inspired air
The nose is part of the conducting zone which:
- Provides a route for incoming and outgoing air
- Removes debris and pathogens from the incoming air
- Warms and humidifies incoming air
The mucosal contains glands that secrete mucus that
Anterior portion of the nasal cavities are lined with mucous epithelium, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity and helps to moisten the tract
Nasal choncae increases the SA and induces turbulence, meaning there is increased time for contact (warming and humidification). Conchae also conserve water and prevent dehydration of the nasal epithelium by trapping water during exhalation
Paranasal sinuses are areas of trapped air and help to warm and humidify air
Explain how the larynx protects the airway during swallowing
When you swallow:
- Epiglottis moves to block the entrance of food particles into your larynx and lungs
- The muscles of the larynx pull upward to assist with this movement.
- Muscles of the larynx also tightly close during swallowing, to prevent aspiration into the lung
Explain why hoarseness of voice/voice change may be a
sign of intra-thoracic disease
The recurrent laryngeal nerve is a branch of the vagus nerve (CN X), which:
- Innervates the muscles of the larynx
- Supply sensation to the larynx below the vocal cords
- Innversates muscles which open the vocal folds (posterior cricoarytenoid muscles)
Describe the structure of the bony thorax including the features of a typical rib and thoracic vertebra
12 ribs:
1-7 connect directly to the sternum
8-10 connect indirectly to the sternum, via costal cartilages
11-12 are floating, with no attachment to the sternum
Each thoracic vertebrae (1-12) is associated with a rib:
- Head of rib has two articular facets, one facet articulates with the corresponding vertebrae (superior articular facet) and the other articulates with the vertebrae above (inferior articular facet)
The costal groove on the inferior aspect has the neurovascular supply of the thorax running through it
Describe rib movements during respiration
2 types of chest wall movements during breathing:
- Bucket handle movement
- Elevation of the lateral aspect of rib shaft
- Increases lateral diameter - Pump handle movement
- Superior and anterior movement of sternum-
- Increases antero-posterior diameter
Describe the external, internal and innermost intercostal muscles and the diaphragm, their nerve supply and actions in respiration
External intercostals:
- Fibres run inferio-medially ‘hands in pockets’ direction
- Acts to raise the ribcage = increase intrathoracic volume
- Quiet inspiration
Internal and innermost intercostals:
- Fibres run in the superior-medial direction (90 degrees to external intercostals direction)
- Acts to lower the ribcage
- Forced expiration
Both innverated by: Intercostal nerves (T1-T11)
Diaphragm:
- Attaches at the inferior thoracic aperture and lumbar spine (crus)
- Mainly skeletal muscle
Innervation: Phrenic nerve (nerve roots C3, C4, C5 - keep the diaphragm alive)
Describe the course of the intercostal nerves, arteries and veins and how to avoid damaging them during pleural aspiration or insertion of a chest drain
The costal groove on the inferior aspect of each rib has the neurovascular supply of the thorax running through it (intercostal nerve, intercostal artery, intercostal vein)
In order to avoid damage, any invasive procedure should be done superior to the rib (NOT inferior to the rib - to avoid damage to these neurovascular structures)
Describe the pleural cavity & pleura, including its nerve supply and the role of the pleural fluid and the pleural seal in lung expansion
Pleural cavity is created by the potential space between the 2 serous membranes:
- Parietal pleura lining the wall of the thoracic cavity
- Visceral pleura lining the organs
Cavity contains a small amount of serous fluid which lubricates the layers, to prevent friction, irritation and inflammation
Parietal pleura:
- Sensitive to pressure, pain, and temperature
- Produces a well localised pain
- Innervated by the phrenic and intercostal nerves
Visceral pleura:
- NOT sensitive to pain, temperature or touch, its sensory fibres only detect stretch
- Receives autonomic innervation from the pulmonary plexus (a network of nerves derived from the sympathetic trunk and vagus nerve)
Pleural seal is important for lung expansion as is formed by the surface tension of the serous fluid between the parietal pleura and the visceral pleura - important because if this seal is broken i.e. pneumothorax, then the lung can collapse
Describe the lower respiratory tract including the airways and the lungs, its blood and nerve supply and lymphatic drainage
Lower respiratory tract includes:
Trachea -> Primary bronchioles (left and right) -> Lobar bronchioles -> Segmental bronchioles -> Alveoli
Point at which the trachea splits into left and right primary bronchioles = carina (angle)
Arterial blood supply: left and right pulmonary arteries plus bronchial arteries
Venous drainage: left and right pulmonary veins plus bronchial veins
Nerve supply: autonomic nervous system and the vagus nerve share the responsibility for innervating the lungs:
- ANS is responsible for dilating and constricting the airway and for regulating bronchial secretions
- Branches from the vagus nerve and sympathetic branches from the cervical cardiac nerves unite to form the pulmonary plexus
Lymphatic drainage: originate below the pleura and are referred to as the subpleural plexus - vessels can be further subdivided into superficial and deep groups
Describe structures in the root of the neck and mediastinum
The mediastinum is a broad central partition that separates the two laterally placed pleural cavities
It extends:
- From the superior thoracic aperture to the diaphragm
- From the sternum to the bodies of the vertebrae
= Has 3 smaller sections (superior mediastinum and inferior mediastinum, then divided into anterior, middle and posterior mediastinum)
Superior mediastinum:
- The major arteries and veins
- Trachea
Inferior mediastinum (separated at sternal angle) Anterior: - Thymus gland (children) - internal thoracic vessels Middle: - Pericardial sac and heart only! Posterior: - Thoracic aorta - Oesophagus - Thoracic duct
Describe the surface marking of the lungs & lobes of the lung
Surface markings (due to restricted space!): Right lung: - Oesophagus - Superior vena cava - Azygous vein Left lung: - Thoracic aorta - Part of aortic arch
Right lung:
- 3 lobes; superior, middle and inferior
- Divided from each other by two fissures:
1. Oblique fissure – runs in supero-posterior direction
2. Horizontal fissure - runs horizontally from the sternum, at the level of the 4th rib, to meet the oblique fissure.
Left lung
- 2 lobes: superior and inferior
- Separated by oblique fissure
(Histology) Describe the histology of the airways and alveoli and relate it to the functions and defence of the lungs
Airways histology:
- Mucous secretions cover almost all luminal surfaces of the conducting airways, involved in humidifying air and trapping pathogens
Alveoli histology:
- Very thin simple squamous epithelium
- Type 1 (gas exchange) and type 2 (surfactant production) pneumocytes
(Histology) Distinguish bronchi from bronchioles histologically
Bronchi have same general histological structure as trachea
- Cartilage rings (bronchioles have irregular cartilage plates)
- Bronchi are larger (bronchioles decrease in size as they branch lower)
- Bronchi have no smooth muscle layer (Bronchioles have a smooth muscle layer, as cartilage diminishes)
(Histology) Define what is meant by a terminal bronchiole, respiratory bronchiole, alveolar duct and alveoli
Terminal bronchiole:
- Smallest conducting bronchiles
- Lined with simple cuboidal epithelium, containing Club cells
Respiratory bronchiole:
- First part of the tree that allows gas exchange (transitional zone between conducting and respiratory zones)
- Narrow diameter and lined with cuboidal epithelium, containing Club cells and cilia
Alveolar duct:
- Elongated airways that have no walls, only alveoli
Alveoli:
- Terminal air spaces of the respiratory system
- Surrounded by a network of capillaries
(Histology) Distinguish between the conducting zone and the respiratory zone of the airways
Conducting zone:
- Mouth/nasal cavity
- Trachea
- Primary bronchi (L and R)
Respiratory zone:
- Respiratory bronchioles
- Alveoli (incl. ducts and sacs)
Distinguishing - respiratory bronchioles which is the point at which gas exchange can first occur
