Mediastinum and Lungs Flashcards
Mediastinum?
- area between two pleural sacs
- superior
- Inferior has three divisions (middle, anterior, posterior)
Superior Mediastinum? contents?
- sternal angle to T4
- contains trachea, esophagus, and important neural structures
Inferior mediastinum? Contents?
- Middle
- heart and pericardium - Anterior
- posterior to sternum and anterior to pericardium
- sternopericardial ligaments
- lymph nodes (cancer)
- thymus gland
- thyroid gland (can descend to substernal) - Posterior
- anterior to vertebral bodies and posterior to pericardium
- esophagus, thoracic duct, Vagus nerve
Esophagus location?
- extends lower end of pharynx to stomach
- midline structure
- no adventitia
Esophagus function?
- distensible: will accommodate anything that can be swallowed
- superior part: striated muscle for voluntary initiation of swallowing
- inferior part: smooth muscle for autonomic control of swallowing
Esophagus innervation?
-Vagus nerve runs behind it
Left recurrent laryngeal nerve? Clinical significance?
- branch of Vagus nerve goes back up and wraps around Aorta
- hoarse voice could be caused by Aortic aneurysm (very rare)
- put on differential
Varicose veins of esophagus?
- anastomosis of veins with left gastric veins
- associated with portal hypertension
- blood backs up into these veins of hepatic portal system
- can cause acid reflux and bleeding
Thoracic Duct path? Function?
- Starts in abdomen as dilated lymph duct called Cisterna Chyli
- goes through aortic opening and travels in posterior mediastinum
- enters at junction of left Internal Jugular vein and Left Subclavian vein
- Function: receives lymph from most of the body including left side of head and neck
Trachea structure?
- midline, mobile
- 16-20 C shaped bars of hyaline cartilage on anterior side
- elastic fibers on posterior side
- enclosed by fibrous muscle covering
- divides T5/T6
- 10 cm in length
Carina of Trachea?
- ridge down midline of trachea
- anterior posterior ridge where trachea branches
- richly innervated by Vagus nerve
If someone swallows something, where will it most likely go?
- right main stem bronchi
- larger and more midline with trachea
What supplies the main bronchi with blood?
- bronchial arteries
- supply non-respiratory areas of lungs and visceral pleura with oxygenated blood
- from Aorta
When someone get’s ear cleaned out, why would they cough?
- external ear: Auricular Temporal nerve
- connected with Vagus nerve to larynx and trachea
- Vagus nerve wanders everywhere (esophagus, cardiac plexus to slow HR, abdomen)
Function of lungs?
-gas exchange: O2 in, CO2 out
How are lungs attached?
- attached to heart and trachea by root and pulmonary ligaments
- double fold of mediastinal pleura
- root of hilum (bronchi, artery, vein, autonomic nerve fibers)
Left lung lobes?
- Superior and inferior lobes separated by an oblique fissure
- Clinical: pneumonias can be specific to one lobe
- has lingula
Right lung lobes?
- horizontal fissure separates superior and middle lobes
- oblique fissure separates inferior from middle and superior lobes
Lung Pleura?
- Parietal pleura
- lines chest cavity
- diaphragmatic
- mediastinal (Phrenic N.)
- costal (Intercostal N.)
- apical - Visceral pleura
- rests on lungs
- sends projections inwards
- no sensory innervation
Parietal pleura innervation and blood supply?
- Phrenic N. (sensory and motor)
- Intercostal N.
- Intercostal arteries
Visceral pleura blood supply and innervation?
- Bronchial arteries
- no sensory innervation
Pleural cavity where pleural effusions occur?
- between parietal and visceral pleura
- fluid accumulates here
- Pleurocentesis: removal of fluid from pleural cavity (stick needle superior to rib into pleural cavity)
Costal endothoracic fascia?
- thin layer of fascia separates costal pleura from ribs
- thickened superiorly over apex of lungs (simpson’s fascia)
Costomediastinal recess?
- only on left side
- goes over bare area of heart
- where lingual of lung extends to pericardium
Costodiaphagmatic recess?
- found on both right and left sides
- surrounds area of diaphragm
- during deep respiration lung extends inferiorly into recess
- when taking fluid from lungs, tell patient not to take deep breath
Cupola?
suprapleural membrane over apex of lungs
Hilar lympadenopathy?
swollen lymph nodes around hilum
Bronchopulmonary segments?
- third order branch
- largest within lobe
- 10 segments each lung
- separated by septa from visceral pleura
- pulmonary veins are intersegmental
- pulmonary arteries accompany bronchi
- pneumonia can occur in segments and not spread to others
Ventilation?
moving air inward via muscles of respiration
Diffusion in alveoli? Thickened membrane?
- O2 and CO2 diffuse through alveolar membrane
- CO2 takes less effort to diffuse
Pulmonary Fibrosis
- if alveolar membrane thickens, patients cannot get enough O2
- treat with O2 tank
Expiration?
passive process that allows air to flow in and out of lungs by elastic fibers
Pulmonary artery?
- bring deoxygenated blood from right ventricle to lungs
- elastic
Pulmonary veins?
- bring oxygenated blood from lungs back to heart
- enter left atrium
- no valves
- 4 veins
Bronchial arteries?
- come off Aorta
- supply non respiratory areas of lungs with blood
Bronchial veins?
-drain from lungs to azygous, hemiazygous, or intercostal veins
Azygous vein?
drains into superior vena cava
Lymph drainage of hilum?
- pulmonary nodes
- tracheobronchial nodes
Lung innervation?
autonomic
Diameter of lungs after Inspiration?
- vertical diameter: contraction of diaphragm
- AP diameter: shape of ribs, intercostals
- Transverse diameter: shape of ribs, intercostals
