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Describe the pleural linings and cavities
- The lungs are housed in the pleural cavities. The pleural linings extend above the 1st rib and extend inferiorly into points
- The visceral pleura is the lining that follows the contours of the lungs very closely. It is the inner lining
- The parietal pleura anchors the lungs to the ribs and the intercostal spaces
- In between the visceral and parietal pleura is serous fluid which provides the lungs with a frictionless environment
What are the parts of the pleural cavity?
- Cervical pleura: superior portion of the pleura
- Costal part: associated with the ribs and their intercostal spaces
- mediastinal part: associated with the mediastinum
- Diaphragmatic part: lines the superior portion of the diaphragm
What is the Hilum of the lung?
They are openings in the lungs found in the mediastinal part. They allow the passage of the vessels that enter and exit the lung (roots of the lung)
What is the innervation of the plueral cavity?
The pleural cavities receive somatic afferent fibers that carry signals back to the brain. The somatic fibers enter the brain through the posterior root of the spinal cord. This lets the brain know of the lung's status
What are the differences between the right and left lungs?
- Right lung is bigger - left lungs shares the mediastinum with the heart
- Right lung has 3 lobes (superior, middle, inferior) and the left lung only has 2 lobes (superior, inferior)
- Right lung has 2 fissures - horizontal fissure and an oblique fissure. Left lung only has a horizontal fissure
- Structures that run along the right lung: superior and inferior vena cava, azygos vein
- Structures that run along the left lung: thoracic aorta, arch of the aorta
What are the structures that pass through the Hilum of the lungs? And what surrounds these structures?
- Pulmonary arteries and veins
- These structures are surrounded in mediastinal pleura
Describe the branching of the Trachea
- Trachea / Right and left main bronchus / lobar bronchi / segmental bronchi / bronchioles / bronchopulmonary segments
- Trachea bifurcates outside the lungs at the level of T4 or T5
- Right bronchus divides outside the lung while the left divides in the lung
What nerves innervate the lungs?
: carries visceral afferent and efferent fibers (sensory and motor fibers), carries parasympathetic signals; constricts bronchioles
- anterior pulmonary plexus
- posterior pulmonary plexus: both of these plexes carry visceral afferent and efferent fibers and travel via the sympathetic trunk; dilates the bronchioles
What are the contents within the mediastinum?
- thymus glands
- thoracic duct
- vagus nerve
- anterior and posterior pulmonary plexes
- major arteries
What are the parts of the mediastinum?
- Superior mediastinum
- Inferior mediastinum: is divided into anterior, middle and posterior mediastinum
What are the structures that hold the pericardium in place?
- central tendon of the diaphragm
- superior sternopericardial ligament
- xiphoid pericardial ligament
What is the innervation of the pericardium?
- Right and left phrenic nerves
- Anterior rami of C3, C4, C5: supplies fibrous preicardium, somatic afferent fibers to parietal pericardium
- Vagus nerve
- Sympathetic trunk: regulates fight or flight responses
What structures supply blood to the pericardium?
- Internal thoracic artery
- Musculophrenic artery
- Inferior Phrenic artery
- Thoracic aorta
What are the surfaces of the heart and what structures are found in each?
- Base (posterior): left atrium, some of right atrium, pulmonary veins, superior/inferior vena cava
- Anterior surface: right ventricle, some of right atrium, some of left ventricle
- Diaphragmatic surface (inferior): left verntricle, some of right ventricle
- Left pulmonary surface: left ventricle, some of left atrium
- Right pulmonary surface: right atrium (primarily)
What are the various sulci found on the heart?
- Coronary sulcus(separates atria and ventricles): right coronary artery, small cardiac vein, circumflex branch of left coronary artery, coronary sinus
- Anterior interventricular sulci (separates ventricles): great cardiac vein, anterior interventricular branch of the left coronary artery
- Posterior interventricular sulci: middle cardiac vein, posterior interventricular branch of the coronary artery
Describe the path of blood
Superior/inferior vena cava, azygos vein, coronary sinus --> right atrium -(tricuspid valve)-> right ventricle -(Pulmonary semilunar valve)-> pulmonary trunk --> Pulmonary artery --> lungs --> pulmonary veins --> left atrium -(bicuspid valve)-> left ventricle -(Aortic semilunar valve)-> ascending aorta --> arch of the aorta --> systemic circulation
Describe the inner walls of the ventricles
The walls of the ventricles have irregularly shaped outgrowths called trabeculae carnae. Papillary muscles are extensions of the trabeculae carnae. Chordae tendinae are attached to papillary muscles on one side and to the cusps of the mitral valve or the tricuspid valve on the other
How many branches do the left and right pulmonary arteries have?
- Left pulmonary artery: 2 branches; on to each lobe of the left lung
- Right pulmonary artery: 4 branches; 2 branches in the superior lobe, then one in the middle and inferior lobe.
Why does the left ventricle have a larger muscle wall than the right ventricle?
The myocardium of the left ventricle is much thicker than the right because it needs to produces a stronger contractile force to pump the blood into systemic circulation
How do the semilunar valves work?
The semilunar valve consist of sinuses. Sinuses are "pocket-like" structures. Once the blood flows through the valve and begin to back flow, the sinuses fill up with blood which effectively closes the opening thus preventing back flow.
What are the branches of the arch of the aorta?
- Left subclavian
- Left common carotid artery
- Right brachiocephalic trunk: right subclavian, right common carotid artery
What are the functions of the cardiac skeleton?
- maintains the integrity of the openings
- provides points of attachments for the cusps of the valves
- separates the atrial and ventricular musculature
- electrically isolates the atria from the ventricles
What is the conductivity path of the heart?
SA node / AV node / Bundle of His (AV bundle) / Right and left bundle branches / subenocardial plexus
What are the effects of the sympathetic fibers on the heart?
- increases HR
- increases contraction force
What are the effects of parasympathetic fibers on the heart?
- Decrease HR
- Decrease contraction force
- Constrict coronary arteries
What contributes to the superficial part of the cardiac plexus?
- Cardiac branches from the sympathetic trunk
- Vagus nerve --> cervical branches of the left vagus nerve
What contributes to the deep part of the cardiac plexus?
- Cardiac branches from the sympathetic trunk
- vagus nerve --> right and left vagus nerves --> right and left recurrent pharyngeal nerves
- Vagus nerve --> right and left vagus nerve