Case 6- lung anatomy part 2 Flashcards
Limits of the lungs
The lungs extend to rib 8. Its limits are T6 in the mid-clavicular line, T8 in the mid axillary and T10 is the posterior and inferior limits of the lungs
Palpating the suprasternal notch and associated structures
You can find the jugular (suprasternal) notch of the manubrium of the sternum. If you move down, you will feel a slight bump - this is the sternal (manubriosternal) angle which is the joint between the manubrium of the sternum and the sternal body. The costal cartilage of rib 2 articulates at this joint, therefore, if you move laterally you will feel the 2nd rib which will allow you to continue counting the ribs inferiorly and laterally.
How air moves through the upper respiratory system
When you breathe in air goes through your nasal cavities or oral cavity into the pharynx, then the Larynx and the trachea. The trachea extends down the neck and into the thoracic cavity within the superior mediastinum.
Where does the trachea split into the bronchi
At the sternal angle (T4/T5), at this division you have the Carina cartilage
Cartilige in the trachea
Arranged in C-shaped rings, between the cartilage you have smooth muscle and fibroelastic tissue to allow for flexibility and to keep the airways open. There is mucosa which is adapted to warm and moisten the air, as well as trap any particles.
Lobes of the lungs
In the right lung there are three lobes and in the left lung there are two lobes.
Divisions of the lung
Trachea -> bronchus -> Lobar bronchi -> segmental bronchi -> bronchioles -> terminal bronchiole -> respiratory bronchiole -> pulmonary alveolus (alveolar duct/ alveolar sac)
Structure of right lung
The right lung has three lobes; the superior lobe, the middle lobe and the inferior lobe. The superior lobe is split from the middle lobe using the horizontal fissure. The inferior lobe is split from the middle lobe by the Oblique fissure. The apex is the top of the lungs and the inferior border is on top of the diaphragm.
Structures surrounding the right lungs
The inferior and superior vena cava, the oesophagus and the subclavian vessels
Structure of left lung
The left lung only has two lobes, the superior lobe and the inferior lobe. It contains the lingula left lung which is like a very small lobe. There is a cardiac notch where the heart sits.
Structures surrounding the left lung
The descending aorta and aortic arch, the oesophagus and subclavian vessels.
The hilum of the right lung
The main bronchus is on the side, it contains cartilage so is easy to identify. The pulmonary artery is in the middle, it comes from the right ventricle. On the other side and down is the pulmonary vein, the pulmonary artery has a thicker wall then the pulmonary vein. The pulmonary artery is superior to the pulmonary vein and the bronchus is superior to the pulmonary artery. Lymph nodes and nerves also go through the hilum
Hilum of the left lung
Has two pulmonary veins going to the heart. The pulmonary vein is anterior and the pulmonary artery is more superior and inferior
The difference between the right and left bronchus
The right bronchus is wider and goes straight down, on the left side it is longer. If you inhale a particle it is more likely to go down the right side
Upper respiratory tract
Contains the oral/nasal cavity, pharynx and larynx
Lower respiratory tract
Trachea, bronchi and lungs
Pleural membrane
A thin double mesothelial layer which is adherent to/surrounds the lungs. Has a visceral and parietal layer, the visceral layer is against the lung whilst the parietal layer is against the surrounding tissue. Between the two layer is the pleural cavity which is a potential space containing the pleural fluid. The visceral and parietal layer are continuous with each other
Role of pleural fluid
It allows the lungs to expand during inspiration as it causes surface tension between the two layers. When the thoracic cage expands the parietal layer will go with the thoracic wall and the surface tension between the visceral and parietal layers will cause the lung to go with it and expand
The regions of the parietal pleura
The parietal pleura has 4 regions: the Diaphragmatic, the Mediastinal (on the mediastin), the Costal (lateral and posterior ribs) and the Cervical (cupola) which is near the apex of the lungs
Recesses in the lungs
Regions which are not completely filled by the lungs, the two recesses are the costodiaphragmatic and costomediastinal
Costodiaphragmatic
Located between the costal and diaphragmatic pleura (inferiorly)
Costomediastinal
Located between the costal and mediastinal layers of the paritetal pleura (anteriorly)
Nerves of the parietal pleura
It is innervated by the phrenic and intercostal nerves, it can sense pressure, pain and temperature
Nerves of the visceral pleura
It is innervated by the pulmonary plexus (autonomic – sympathetic trunk and vagus nerve), it can sense stretch. The bronchial and intercostal arteries supply the visceral and parietal pleura respectively.
Larynx
Produces phonation (production of speech sounds). It is located at the C4-C6 level, extending from the base of the tongue to the trachea. It opens into the laryngopharynx at the inlet.
What is the larynx made of
- Cartilage (and joints).
- Membrane (and ligaments).
- Mucosa (coats cartilage and membranes).
- Muscles
The Hyoid bone
The larynx is suspended from the Hyoid bone, the Hyoid bone does not articulate with any other bone
The thyroid cartilage
The adams apple. It is a C-shaped cartilage with two lamina joined anteriorly forming the laryngeal prominence. The oblique line is the site of attachment of the inferior constrictor and infrahyoid muscles. Has a superior and inferior horn, the inferior horn articulates with the cicoid cartilage.
The Epiglottis cartilage
Goes over the inlet of the larynx when we swallow to stop food going down the airway. It is an elastic cartilage which is behind the root of the tongue. It attaches to Hyoid cartilage above and thyroid cartilage below.
The Cricoid cartilage
Articulates with the Thyroid cartilage and is just above the trachea. Unlike the thyroid cartilage, the cricoid cartilage is a full ring which articulates with the arytenoids at the cricoarteynoid joint.
The Artenoids
Articulates with the posterior portion of the cricoid cartilage to form a synovial joint called the cricoarytenoid joint. The vocal processes are where vocal ligaments attach to. The muscular processes attach to some intrinsic muscles of the larynx that move the vocal folds, which change tone.
Two types of membrane in the larynx
The extrinsic membrane start from outside the larynx and then goes into it, the intrinsic membrane starts and finish’s in the larynx
The external membrane
Thyrohyoid membrane, Cricotracheal membrane and Hyoepiglottic membrane
Thyrohyoid membrane
Comes from the hyoid bone and goes into the thyrohyoid cartilage. There is a thickening in the middle called the median thyrohoid ligament
Hyoepiglottic and Thyroepiglottic membrane
Keeps the epiglottis in place, the Thyroeppiglottic is internal
Cricotracheal membrane
Connects the larynx to the trachea, it is seen inferiorly
The internal membranes
The Quadrangular, Cricothyroid and Thyroepilottic membrane
The Cricothyroid membrane
Can be seen externally but extends internally along the thyroid cartilage and is considered an internal membrane. Has a thickening which is called the median Cricothyroid ligament which is used for emergency openings of the airway if the patient is unable to breath. It is made of elastic tissue, also known as conus elasticus, has a free upper border which forms the vocal ligament
The Quadrangular membrane
Forms the epiglottis and arytenoids and hangs down from the aryepiglottic fold. Has a free lower border which forms the vestibular ligament.
Aryepiglottic fold
A mucus membrane covering the aryepiglottic muscle and the lateral borders of the laryngeal. Extends down over the Quadrangular membrane
Vestibular fold (false vocal fold)
Mucosa covering the vestibular ligament, the vestibular fold lies superior to the vocal fold.
Vocal fold (true vocal cord)
Mucosa covering the vocal ligament (upper border of the Cricothyroid membrane), adduction of vocal folds close the airways.
Trachea structure
Contains C-shaped Hyaline cartilage, easily recognised by the chondrocytes in the Lacunae
Bronchus structure
1) Ciliated pseudostratified columnar epithelium
2) Goblet cells and mucus glands
3) Lamina propria
4) Serous gland
5) Cartilage
Segmental bronchi structure
1) Ciliated columnar epithelium
2) Reduced goblet cells and Mucus glands
3) Thin Lamina propria
4) Smooth muscle is more prominent
5) Reduced cartilage
Bronchioles structure
1) Ciliated columnar epithelium
2) No goblet cells
3) Smooth muscle
4) No cartilage
Terminal bronchiole structure
1) Ciliated cuboidal epithelium
2) No goblet cell
3) No smooth muscle
4) No cartilage
5) Ciliated Clara cells
Respiratory bronchiole structure
1) Ciliated cuboidal epithelium
2) No-goblet cells
3) Non-ciliated Clara cells
Alveolar duct structure
1) Squamous epithelia (no cilia)
2) Type 1 pneumocyte
3) Type 2 pneumocyte
Alveolar sac structure
1) Squamous epithelia (no cilia)
2) Type 1 pneumocyte
3) Type 2 pneumocyte
Alveolus structure
1) Squamous epithelia (no cilia)
2) Type 1 pneumocyte
3) Type 2 pneumocyte
4) Shares basal lamina with endothelial cells for gas exchange as thin barrier
5) No connective tissue just elastic fibre which allow elastic recoil and prevent alveolar collapse
Pneumocyte
An alveolar cell involved in gas exchange. The organelles group centrally to save space. Type 1 pneumocytes are found in the alveolar ducts and alveoli, they are extremely thin and slender. There are more type 1 pneumocytes the type 2. They function to secrete surfactant which reduces alveolar surface tension. Act as progenitor cells for type 1 pneumocytes. They are short and fat.
Alveolar Macrophage
Monocytes that have escaped from the pulmonary vasculature and function to phagocytose foreign matter in the alveoli. Large and very dark.
Function of capillaries, cilia and goblet cells
Warm (capillaries in the Lamina propria), filter (cilia), moisten (goblet cells)
Capillaries- air-blood barrier
Thin due to the shared basal lamina
Basal cells
Progenitor and stem cells that reside at the bottom of the epithelium and replenish cells above. They are short, triangular and darker
Divisions of the bronchioles
Has 14 divisions with less cartilage on each division but more smooth muscle
Conducting area of bronchial tree
Trachea, bronchi, bronchioles and terminal bronchioles
Respiratory area of Bronchial tree
Alveolar ducts and alveolar sacs
Goblet cells
They secrete mucous which is formed from mucin granules in the cytoplasm. The mucus traps particulates and microbes. Located in conducting airways, found in the epithelium with pale, cup like structure.
The submucosa layer
Contains seromucous glands and allows for the mucocilary escalator
Structure of the nasal cavity
The nasal cavity is lined by respiratory mucosa. Along the nasal surface is pseudostratified ciliated columnar epithelium, between these cells are goblet cells. At the bottom of these cells is the basement membrane, beneath the basement membrane is a thicker layer of loose connective tissue called the lamina propria. There are many blood vessels and seromucosal glands within the lamina propria.
Mucus production and clearance in the nasal cavity
The blood vessels in the lamina propria warm the air near to body temperature. Simultaneously the watery mucus secreted from the goblet cells and seromucosal glands humidifies the air. It also traps the foreign particles and keeps them from entering other parts of the respiratory tract. The wave like beating of the epithelial cilia move the debris to the throat where it is swallowed.
