Thorax & Resp System (Exam 3) Flashcards
The ___ rib inserts at the Sternal Angle (Manubriosternal)
Second
At what level does the Second Rib insert at the Sternal Angle? A. T2-T3 B. T1-T2 C. T4-T5 D. T3-T4
C. T4-T5
The Sternal Angle separates the ___ from the Inferior Mediastinum
Superior
The Sternal Angle is at the level of Tracheal Bifurcation which is also the ___
Carina
The Sternal Angle is an important landmark for many other features and separates…
- Superior limit of Pericardium and of the Pulmonary Trunk
- Where Arch of the Aorta begins
- Where Superior Vena Cava begins to enter the RA - Central Venous Pressure determination
The top of the Manubrium (Suprasternal Notch) is at the level of?
T2-T3
The Mediastinum is divided into what 5 areas?
- Anterior
- Middle
- Posterior
- Superior
- Inferior
What are the 4 contents of the Anterior Mediastinum?
- Thymus (behind Manubrium)
- Internal Mammary vessels
- Lymph nodes
- Loose Connective Tissue
Think Ant “TILL”
What are the 5 main contents of the Middle Mediastinum?
- Pericardia (Fibrous, Serous [Visceral and Parietal])
- Heart
- Great Vessels (Aorta, SVC, IVC, Pulmonary aa and vv)
- Nerves (Vagus, sympathetics, Phrenics)
- Trachea
What are the 6 main contents of the Posterior Mediastinum?
- Descending Aorta
- Esophagus
- Intercostal aa and vv
- Thoracic Duct
- Azygos
- Hemiazygos vv
The Thoracic Duct carries ___ from below the diaphragm up into the ___ veins.
lymph
Subclavian
What are the 10 main contents of the Superior Mediastinum
- Thymus
- Brachiocephalic vv
- SVC
- Aortic Arch and Branches
- Trachea
- Esophagus
- Phrenic nn
- Vagus nn
- L Recurrent Laryngeal n
- Thoracic Duct
What is the significance of buffalo not having a mediastinum?
Having no mediastinum creates an open pneumothorax (air pressure is much higher outside) - air rushes in and the lungs collapse.
Both lungs will collapse at the same time due to no mediastinum
What is the significance of the cervical plexus?
C3, 4, 5 keep you alive
Phrenic nerves originate here
Diaphragm Innervation:
The Phrenic Nerves take a “___ ___” through the Middle Mediastinum
“Vascular route”
Diaphragm Innervation:
The R Phrenic follows the ___. The L Phrenic follow the ___ ___.
R follows Veins (SVC, RA, and IVC)
L follows Arterial blood (PA, LV)
*Phrenic Nerves take a Vascular Route through the Middle Mediastinum
The L Vagus takes the ___ route through the Superior Mediastinum, then takes the ___ route through the Posterior Mediastinum
arterial
food
The R Vagus takes the ___ route (next to Trachea) in the Superior Mediastinum then takes the ___ route in the Posterior Mediastinum
air
food
The Vagus nerve is located ____ to the phrenic nerve. In the Mediastinum it passes posterior to the ___ ___.
posterior
hilar roots
What happens in unilateral Phrenic Nerve paralysis?
The phrenic nerve provides the primary motor nerve to the diaphragm. Injury to either side of the diaphragm = loss of the ability to contract and allow proper inspiration.
This can impact daily living by causing dyspnea, sleep disturbances, or in severe cases decreased life expectancy.
Leading cause of unilateral paralysis is iatrogenic (from surgery…or trauma)
What innervates the diaphragm?
Phrenic nerve
Caput Medusae is a sign of what?
Portal hypertension
Caput Medusae is created by distension of the Superior and Inferior Epigastric veins and this extends into the ___ ___ ___
Thoraco-epigastric anastomosis (collaterals)
What are the Primary Muscles of breathing?
- Diaphragm (75% of inspiration, quiet respiration, Phrenic n (C3,4,5)
- External Intercostals (move ribs up and out - T1-T11 - “hands into pockets”)
- Interchondral portion of the Internal Intercostals (T1-T11 - at 90 degrees to external)
What are the major accessory muscles of breathing?
- Sternocleidomastoid (CN XI)
2. Scalene Muscles (anterior, middle, posterior - C3-C8)
Accessory muscles of breathing are used when there is ___ ___ (i.e exercise and pathological states)
Forced breathing
Move upper two ribs and sternum
What are the two forms of expiration?
Quiet breathing
Active breathing
What is Quiet Breathing?
Essentially the passive elastic recoil of the lungs
What is Active Breathing?
Exercise and pathological states
What are the 3 main drivers of respiration?
- Medullary Inspiratory Center (Brain Stem)
- Central Medullary Chemoreceptors
- Peripheral Carotid and Aortic Chemoreceptors
What innervates the diaphragm?
Phrenic nerve
Caput Medusae is a sign of what?
Portal hypertension
The Central Medullary Chemoreceptors respond to?
pH of CSF
What is collateral circulation?
The alternate circulation around a blocked artery or vein via a different pathway, such as a nearby minor vessel.
Formation may be provoked by high vascular resistance or ischemia.
The Peripheral Carotid and Aortic Chemoreceptors are sensitive to?
PaO2 of < 60mmHg
What does a decrease in PaO2 (of < 60mmHg) stimulate?
The Peripheral Carotid and Aortic Chemoreceptors to increase ventilation.
This is the most sensitive peripheral mechanism that affects breathing.
*Caution in severe chronic lung dz as this can dampen breathing
Accessory muscles of breathing are used when there is ___ ___ (i.e exercise and pathological states)
Forced breathing
Move upper two ribs and sternum
What are the main muscles involved in Active Breathing?
Internal intercostals (T1-T11 move ribs down and inward) Abdominus Muscles = -Abdominus Rectus -External and Internal Obliques -Transversus Abdominus
The Medullary Inspiratory Center is the ___ ___ for respiration. What are its components?
Rhythm generator
- Sensory input: via CN 9 and 10 chemoreceptors and CN 10 pulmonary mechanoreceptors
- Motor input via Phrenic n.
Where would you place a chest tube (tube thoracostomy) and why?
Over the top of the rib - you do not want to damage intercostal aa or nn below
Why does aspiration pneumonia most often affect the RLL?
The Right Main Bronchus is straighter and slightly wider than the L and foreign bodies and aspiration will take the path of least resistance.
Elasticity and Compliance are ___ related.
Inversely
What is compliance?
A measure of the ability of the lungs and chest wall to distend (i.e the change in the volume for a given change in pressure)
Ventilation and Perfusion Ratio:
What happens when there is ventilation but no perfusion?
Pulmonary embolus or “dead space”
Blood will be high in PAO2
Ventilation and Perfusion Ratio: What happens when there is perfusion but no ventilation?
Airway Obstruction or R to L shunt
Blood will be high in CO2 and O2 - they pass on through and no gaseous exchange occurs
Describe the pleural space
Pleural cavity extends 2-3cm above the first rib and 3-4cm above the first costal cartilage
Know the pleural space and what happens with pneumothorax
Air in the pleural space. Increased positive pleural pressure causes collapse of the lung. 3 Types: Spontaneous Traumatic Tension
Know the pleural space and what happens with pleural effusion
Fluid accumulates between the visceral and pleural space. Causes: Transudative (CHF) Exudative Traumatic
Compliance will ____ in restrictive pulmonary conditions
decrease
Lungs become stiffer, ie any condition that results in the reduction in the ability of the lung or chest wall to inflate
What are the the segments of the lungs that Dr. Witwer specifically wants us to know?
Lingular segment (superior and inferior)
Apical segment (apex of each lobe)
Superior Segment
(Slide# 22 and 23)
The lower border of the lungs has what landmarks?
- MidClavicular Line (Rib 6,7 anteriorly)
- MidAxillary Line (Rib 8 laterally)
- Infrascapular Line (Rib 10 posteriorly)
- Lateral and Vertebral Column (Rib 11)
What is different about the dermatomes posteriorly compared to anteriorly?
Posteriorly the dermatomes go up higher than anteriorly (they are not horizontal)
What is the lymphatic drainage of the breast?
Approximately 75% of spread of breast malignancies goes to the axillary nodes and 25% will go to the internal mammary (internal thoracic) nodes.
What is the lymphatic drainage of the lungs?
Lung malignancies will spread to the hilar, then sub carinal, mediastinal paratracheal nodes, then can spread to the supraclavicular nodes (Virchow’s node, signal node)
What is the Brachial Plexus?
C5 to T1
Roots form –> Trunks –> Divisions
Radial Neuropathy or “Saturday Night Palsy” is ___ paralysis
Extensor
Radial n. (posterior compartment of arm) is pinched causing nerve paralysis - cannot extend elbow, wrist, or fingers
What is the function of the Latissimus dorsi muscle?
Adduction, Flexion, and internal rotation of the shoulder joint (climbing muscle)
Innervation: Thoracodorsal n
What is the function of the Serratus Anterior muscle?
Shoulder thruster muscle (forward)
Innervation: Long Thoracic n - if this is sacrificed during SX - causes winging of the scapula
What are the Rotator Cuff Muscles?
SITS
- Teres Minor and Deltoid mm (Axillary n)
- Supraspinatus, Infraspinatus mm (Suprascapular n)
- Subsapularis, Teres major mm (Inferior Subscapular n)
What are splanchnic nerves?
Supply the abdominal and pelvic viscera.
Motor: to the internal organs
Sensory: coming from the internal organs
What is the most important determinant of normal breathing?
Central Medullary Chemoreceptors
