Exam III: Thorax II

Question 1

Pericardium

Answer 1

located in middle mediastinum
Pericardium is a tough fibrous sac that surrounds the heart
1. White tissue layer – fibrous pericardium – what you see if you remove chest plate – “fibrous like tissue bag”
2. Parietal layer
3. Pericardial cavity: filled with 25 mL of slick, serous fluid produced by mesothelial cells
Why do you need a lubricating fluid? Reduce friction so you can get a good heartbeat
4. Viscera layer of the pericardium – the layer that actually is on the heart itself. It comes up, wraps around, and becomes the parietal layer
Immediately underneath the visceral layer is the endocardium, the heart itself

Phrenic vessels supply blood to the pericardium Pericardium is innervated by the phrenic nerve
Any agitation of the pericardium will be received by the phrenic nerve, will manifest itself in C3,4,5 as pain (in neck)
Phrenic nerve –innervates diaphragm and pericardium

Question 2

Landmarks of Pericardial Cavity

Answer 2

1. The transverse pericardial sinus – space formed in the pericardium where you could insert your fingers
   Separates the arterial system from the venous system (arteries above; veins below)
2. Oblique pericardial sinus – if you put your finger in it, you can palpate the pulmonary trunk.

Question 3

Cardiac Temponade

Answer 3

A build up of blood or other fluid in the pericardial sac putting pressure on the heart, which may prevent it from pumping effectively

Question 4

Pericardiocentesis

Answer 4

Insertion of needle into pericardial cavity to draw off blood or pericardial fluid during cardiac temponade

The patient undergoing pericardiocentesis is positioned supine with the head elevated 30 to 60 degrees. This places the heart in proximity to the chest wall for easier insertion of the needle into the pericardial sac.

Anatomically, the procedure is carried under the xiphisternum up and to the left

Can also position needle through the 5th or 6th intercostal space at the left sternal border at the cardiac notch of the left lung or through the infrasternal angle

Question 5

Clinical Findings Leading to Pericardiocentesis

Answer 5

Fibrous pericardium is a tough, fibrous tissue sack. Physiologically important for the “soft, squishy heart”
If fluid accumulates in the pericardial cavity, the “soft, squishy heart” will give first
Any kind of fluid build up will put pressure on the heart, compromising the heart – EKG finding, muffled heart sounds= medical emergency – need to do a pericardiocentesis
Stick a needle in patients chest, aim for cavity space. Aim for xiphoid sternal process
INSERT NEEDLE IN UPWARD MOTION AND SLIGHTLY TO THE LEFT. Don’t puncture heart.

Question 6

The Heart

Answer 6

GO TO FIFTH INTERCOSTAL SPACE, MIDCLAVICULAR LINE, will come to apex of heart
Known as the point of maximal impulse – where heart beat feels the strongest

Surface name is what is against: anterior surface, base, left and right pulmonary surface, diaphragmatic surface
Great vessels are at the base of the heart, the other end is the apex

Question 7

Heart Valves

Answer 7

Valves are tough piece of connective tissue
Fibrous dense connective rings – trigones – “heart’s skeleton” - the root of the valve
Fibrous rings also important for electrical insulation – atria and ventricle need to be electrically isolated to guarantee harmonious HB
AV bundle – only electrical connection between atria and ventricle; others than this exist in electrical isolation

Question 8

Skeletal Structure of the Heart

Answer 8

Fibrous rings for tricuspid, bicuspid, aorta, and pulmonary valves

Question 9

Right Atrium

Answer 9

First chamber of the heart
Fossa ovalis – in wall, which is an embryologic remnant of fossa ovale which allowed blood to go from left to right atria, bypassing lungs and closes after birth
Some people do not have a fuse, giving left to right communication, a left to right shunt resulting in blood mixing= bad
Blood gets returned in opening of coronary sinus
Crista terminalis – muscular ridge of a pseudochamber
Surface is rough through pectinate muscles – smooth muscles coming together would cause heart walls to stick together
Tricuspid valve – entrance to next chamber

Question 10

Right Ventricle

Answer 10

Each leaflet is anchored through papillary muscle then trabeculae carnea muscles – the muscular connections of the valve to the myocardial wall
Have connections to IV septum and post myocardial wall – ischemic event or cardiac damage compromising wall – will compromise ability of wall to close – people who have had an MI could have a murmur
Wall damage causes valve not to close properly
Conus arteriosus –area of smooth wall that marks final part of LV – surrounds pulmonary valve which is right before pulmonary trunk
2 types of valves – pulmonary semilunar/cusp valves and leaflet valves (tricuspid)

Question 11

Left Atrium and Ventricle

Answer 11

Atrium: has 2 openings for pulmonary veins
Can see other side of the fossa ovale
Mitral valve/bicuspid valve

Ventricle: papillary muscle roots valve to wall
Can see next aortic semilunar/cusp valve –blood will then enter systemic circulation

Question 12

Pump Flow

Answer 12

Heart is 2 pumps in 1 – pulmonary and systemic circulation
Right = pulmonary; left = systemic
2 different pumps; 2 different pressure – Right side = lower pressure; Left side = high pressure
Abnormalities in walls (holes) will give a left to right shunt (blood will go from left side to right side – left is under higher pressure) - causes right sided cardiac hypertrophy

Question 13

Radiology

Answer 13

Chest x-ray usually ordered to examine lung fields and cardiac size
Quick and dirty – compare the diameter of the cardiac silhouette to the overall diameter of the thoracic cage Looking for a ratio of .5 or less, if greater, indicates pathology
Look for presence of costodiaphragmatic recesses – should not be occluded or obliterated (indicates pleural effusion – liquid residue in pleural cavity)
Breast tissue makes it look more radioopaque
Identify arch of aorta, pulmonary trunk, apex of heart, LV, RV, and RA
Any trauma to chest – RV most susceptible
Called a P.A. film – X-ray comes from back so we do not artificially magnify the heart
Also want a sagittal film – can see vertebral column, some of cardiac silhouette, and costodiaphragmatic recess

Question 14

Electrical Properties of the Heart

Answer 14

Heart has its own pacemaker – the SA node (sinoatrial node) located in the RA – sets heart’s rate and rhythm Generates AP, sent out as wave across atrium causing depolarization causing atria to contract

On floor of RA is AV node – generates AP for ventricles Travels through single bundle fiber – the Bundle of His which will divide into a left bundle and right bundle
Will project down to apex of heart, the travel up and around the myocardium
Left will travel back to the base of the heart, right will take a side trip through the septal modulator bands, adds at tiny, tiny electrical delay
This allows the left to start the depolarization slightly before the right – allows heart to engage in a twisting motion so as much blood as possible is released into the circulation

Question 15

EKG/ECG

Answer 15

EKG is demonstrating depolarization/repolarization
P – atrial depolarization (atrial contraction)
QRS – ventricular depolarization
T – ventricular repolarization

Elongated QRS – conduction delay
QRS – rabbit ears/twin peaks – bundle branch block (1 side contracting before the other) = specifically left bundle branch block
Atria and ventricles beating on their own = complete heart block
MI = elevated ST – “tombstones”
Depressed ST = cardiac ischemia

Question 16

Heart Sounds

Answer 16

Sound 1 = lub; closing of AV valves (tricuspid and bicuspid)

Sound 2 = dub; closing of aortic and pulmonary valves

Question 17

Auscultation of the Heart

Answer 17

Need to listen to all 4 valves
Tricuspid – 5th intercostal space parasternally (directly adjacent to sternum) – listening to valve “beyond” the valve - checking for murmurs
Aortic valve – 2nd intercostal space, parasternally
Pulmonary valve -2nd intercostal space, left side
Mitral valve – 5th intercostal space midclavicularl line – the apex of the heart

Question 18

Coronary Vasculature

Answer 18

Heart deals with all of the blood of body, but does not meet metabolic demands of heart – role of coronary vasculature
Semilunar valves are cusp valves – on the aortic valve have little holes, the opening and origin of coronary arteries
Every time the valve closes, blood will fill up cusps and forcefeeding R + L coronary arteries
Most variable vasculature in body
Coronary artery starts at base of aorta, wraps behind pulmonary trunk
Left coronary area will bifurcate - anterior interventricular artery to apex of heart and circumflex goes to the backside of the heart
Left coronary artery has other names – left mainstream vessel, and the widow maker – if it is occluded obliterate perfusion to the entire anterior surface of the heart and the posterior surface of the heart – results in massive MI
DIAGONAL BRANCH COMES OFF ANTERIOR INTERVENTRICULAR BRANCH
Right coronary artery supplies the sinu-atrial branch, gives a marginal branch, then wraps around backside of the heart and provides posterior interventricular artery

Question 19

Coronary Vasculature: Right and Left Dominant

Answer 19

Some people will be right dominant – left coronary artery - LAD, circumflex = “normal”

Left coronary artery casts off SA nodal artery
Circumflex becomes posterior artery
Both the SA and posterior interventricular are to the left - anatomic minority

Question 20

Coronary Venous Drainage

Answer 20

Anterior interventricular vein =great cardiac vein (runs parallel to anterior interventricular artery)
Wraps around back, where we have a middle cardiac vein and a right marginal vein
All veins converge on the coronary sinus

Backside of the heart – note the coronary sinus
Great cardiac vein comes from the front
Coronary sinus is the last stop of all the oxygenated blood used by the heart – directly empties into RA

Question 21

Cardiac Innervation

Answer 21

Sympathetic for heart = T1-T4
Will ascend to cervical ganglion, synapse, and then postganglionic fibers will come back down to chest in cardiac plexus
Parasympathetic innervation comes from the vagus nerve (X)

Ligamentum arteriosum – fibrous connective tissue running from aorta to pulmonary trunk- embryologic structure carried through to adulthood
In embryologic development – no need for functioning lungs - provides a portal for anything in the pulmonary trunk to enter systemic supply and avoid lungs
In adulthood, only a fibrous connective band is left
May not obliterate – allows for another area of left to right shunting
Consequences of overloading pulmonary circulation? Pulmonary edema and pulmonary hypertension

Question 22

Cardiac Plexus

Answer 22

Autonomic division of the peripheral nervous system is directly responsible for heart rate, force of contractions, and cardiac output
Branches from parasympathetic and sympathetic systems contribute to the formation of the cardiac plexus consisting of the superficial and deep cardiac plexus between the aortic arch and tracheal bifurcation

Question 23

Referred Pain

Answer 23

Results from “brain confusion”
MI manifests as crushing chest pain to arm
Brain constantly receives info form somatic T1-4
GVAs and GSAs located in the dorsal root ganglion – myocardial event sensed by GVAs
Brain not used to receiving info of cardiac crisis, brain initially interprets as somatic T1-T4 pain

Question 24

Mediastinum

Answer 24

Mediastinum developed into several compartments
Middle mediastinum – heart
Sternal angle – forms a depression – will be between vertebrae IV and V; above that line is the superior mediastinum and below is inferior mediastinum
Superior Mediastinum: Most concerned w/the great vessels – aortic arch -> brachiocephalic trunk -> right common carotid and right subclavian
Anterior mediastinum – in front of pericardium
Posterior mediastinum- behind pericardium

Question 25

Thymus

Answer 25

More important in children, atrophies with age Spans superior mediastinum up to neck, also found in anterior compartment Responsible for T cell maturation – important for immune function Born in bone marrow, go to thymus for self maturation – self recognizing T cells are destroyed

Question 26

Super Vena Cava and Brachiocephalic Veins

Answer 26

Contents of the Superior Mediastinum: 1. Retrosternal Great Veins 2. Left Brachiocephalic: formed by union of left internal jugular and subclavian veins 3. Right Brachiocephalic- formed by union of right internal jugular and subclavian veins 4. Superior Vena Cava: formed by the union of the right and left brachiocephalic

Question 27

Aortic Arch

Answer 27

``` Contents of the Superior Mediastinum: 1. Intermediate Structures 2. Aortic arch and great branches: A. Right brachiocephalic artery that divides into the right common carotid and right subclavian B. Left common carotid artery C. Left subclavian artery ** Ligamentum arteriosum – obliterated ductus arteriosus ** Arch – site of most aortic aneurysms ```

Question 28

Thoracic Aorta

Answer 28

Location: TV 4 – TV 12 ``` Gives rise to the following arteries : Bronchial Pericardial Intercostal/subcostal Superior phrenic Esophageal Mediastinal ```

Question 29

Azygos Venous System

Answer 29

Function: drains the body wall and highly variable system of veins Major Veins in the System: Azygos (right side) and Hemiazygos and accessory azygous (left side) Located in the posterior mediastinum

Question 30

Azygos Vein

Answer 30

Formed by: right ascending lumbar vein and right subcostal vein Right superior intercostal vein (junction of intercostal veins 1,2,3, and 4 on right side) Azygos dumps into inferior vena cava

Question 31

Hemiazygos and Accessory Hemiazygos Veins

Answer 31

Hemiazygos Formed by: left lumbar vein and left subcostal vein Crosses to right side ~ TIX (behind: aorta, esophagus, and thoracic duct) and then enters the azygos Accessory Hemiazygos Crosses to right ~ VIII (crosses of over to azygos or connects with the hemiazygos) Left Superior intercostal vein: intervertebral veins 1,2, and 3; empties directly to the left brachiocephalic veins Vena cava – on the right; aorta – on the left

Question 32

Thoracic Duct

Answer 32

Originates from cisterna chyli (abdominal cavity) Begins at ~ L2 and ascends on right side in the thoracic cavity Crosses to the left side ~ T5 and continues until it continues to the superior mediastinum into the neck Empties into the venous angle = left jugular trunk and left subclavian trunk Cisterna chyli – the largest, grossly visible part of lymphatic system – all lymph return from lower half of body will go here – these plus thoracic duct are the only grossly visible compartments of lymphatic system you will see Thoracic duct returns at junction

Question 33

Superior Mediastinum

Answer 33

1. Thoracic Duct: Location: Passes though the superior mediastinum Posterior to the arch of the aorta and initial portions of the left subclavian artery Between the esophagus and left mediastinal part of the parietal pleura Empties it contents at the union of the left internal jugular and subclavian veins (left venous angle) 2. Arch of aorta, brachiocephalic trunk, jugular, thoracic duct enters into the venous system

Question 34

Abormalities: Coarctation

Answer 34

Abormalities: 1. Coarctation (constriction) of the aorta – aorta narrows- vascular supply to limbs has already branched off, will have unequal pulses/BP in extremities (higher in upper than lower) 2. Coarctation will result in surrounding eventual changes - greater than average flow of blood through subclavians, which give rise to internal thoracic, which give supply to internal intercostals – results in increasing in pressure – blood vessels will become bigger – “macroni sized internal thoracic arteries will become bigger, as well as internal intercostals, which will supply blood into aorta” – roundabout fill into aorta

Question 35

Nerves of the Superior Mediastinum: Intermediate Structures

Answer 35

Intermediate Structures: Nerves: vagus nerves, phrenic nerves, sympathetic branches Vagus= wanderer, sends off a collateral known as the left recurrent branch/the left laryngeal at high risk for injury during surgery – if damaged, will affect laryngeal tone – patient’s voice will change – landmark = ligamentum arteriosum Have cardiac nerves coming from the sympathetic trunk All come into the superficial cardiac plexus which innervates the myocardium

Question 36

Nerves of the Superior Mediastinum: Prevertebral Structures

Answer 36

Prevertebral Structures: | Nerves: Vagus nerves dividing into the right recurrent laryngeal nerve

Question 37

Sympathetic Trunks

Answer 37

Sympathetic Trunk and Derivatives Sympathetic Innervation: T1 to L2 Branches Greater Splanchnic – T5 - 9 Lesser Splanchnic – T10 - 11 Least Splanchnic – T12 Located in posterior mediastinum

Question 38

Esophagus: General Information, Blood Supply, Venous Drainage, and Lymphatic Drainage

Answer 38

Location: traverses both superior and posterior mediastinum; muscular tube connecting mouth to stomach Compressed by three structures: aortic arch, left main bronchus, and diaphragm Relations of the esophagus and the descending aorta Blood Supply: esophageal arteries from the thoracic aorta and the left gastric artery Venous Drainage: azygos, hemiazygos, and esophageal veins leading to the left gastric vein (abdomen) Lymphatic Drainage: posterior mediastinal nodes and left gastric nodes

Question 39

Esophagus Abnormalities

Answer 39

Esophagus crossed at TV8 – passes into abdomen and stomach Tight relationship between the trachea, esophagus, and aortic arch - congenital abnormality – may have a double arched aorta – constricts esophagus and makes it difficult to swallow Esophageal disorders put trachea and aorta at risk Common sites where things can get stuck in the esophagus: junction of esophagus with pharynx, where esophagus is crossed by aortic arch, where esophagus is compressed by left main bronchus, and at the esophageal hiatus Hiatal hernia – common presentation – incessant heartburn, get full really quick cardiac sphincter getting pushed up into thoracic cavity

Question 40

Esophagus Innervation

Answer 40

Innervation: Esophageal plexus: right and left vagus nerves (goes to form the anterior and posterior vagal trunks), sympathetic trunks, and splanchinic nerves Vagus nerve and sympathetics make esophageal plexus– sympathetics suppress peristaltic motion, but parasympathetic increases peristalsis