Thorax II (Anatomy of the Heart) Flashcards
What is the position of the Heart?
- The heart lies in the inferior middle mediastinum
Where is the Apex of the heart?
left and anterior, 5th intercostal space, mid-clavicular line
Where is the Base of the heart?
posterior, T6-9 vertebrae
What is the Pericardium?
Encloses heart and roots of great vessels
* Blood supply: pericardiacophrenic vessels
* Innervation: phrenic nerve(C3-5)
What are the 2 types of Pericardium?
- Fibrous pericardium
- Serous pericardium
What is the Fibrous pericardium?
- Dense, inelastic connective tissue
- Anchored to the rest of the mediastinum and the diaphragm
- Protection, prevents over stretching of the heart
What is the Serous pericardium?
- A thin sac forms a double layer around the heart
- The lumen of this sac is pericardial cavity
- Contains pericardial fluid
What are the 2 layers of the Serous pericardium?
- Parietallayer
- Lines the internal surface of the fibrous pericardium
- Viscerallayer
- Covers the surface of the heart and portions of great vessels
What are the external features of the heart?
- Coronary Sulcus
- Interventricular Sulcus
Where does the Right Atrium receive blood from?
Receives deoxygenated blood from systemic veins
* From the upper body via the SUPERIOR VENA CAVA (SVC)
* From the lower body via the INFERIOR VENA CAVA (IVC)
What is the posterior & anterior inner surface of the Right Atrium like?
The posterior inner surface is smooth
The anterior inner surface is rough due to PECTINATE
MUSCLES, which extend into the RIGHT ATRIAL AURICLE
Where are the Crista terminalis of the Right Atrium?
borders between the smooth part and the rough part
Where are the Fossa ovalis of the Right Atrium?
is a depression on the INTERATRIAL SEPTUM
* Developmental remanent
What is the inner surface of the Right Ventricle covered by?
covered by bundles of cardiac muscle called trabeculae carneae
What is the Papillary muscle of the RV?
finger-like projection of trabeculae carneae
Blood passes from RA to RV through what?
through the TRICUSPID VALVE
* Tricuspid valve has three cusps
* Each cusp is connected to a papillary muscle via tendon-like cords, called CHORDAE TENDINEAE
Blood passes from the RV to what?
to the PULMONARY TRUNK through the PULMONARY VALVE
What does the pulmonary trunk give rise to?
gives rise to pulmonary arteries that supply the lungs
What is the Left Atrium posterior to?
Posterior to RA and forms most of the base of the heart
Where does the LA receive blood from?
Receives oxygenated blood via four pulmonary veins,
two from each lung
What is the inner surface of LA?
is smooth. Pectinate muscles are confined to the auricle
What does the LV form?
the APEX of the heart
What does the LV also poss?
posses TRABECULA CARNEAE and PAPILLARY MUSCLES
Blood passes from LA to LV through what?
through the BICUSPID (MITRAL) VALVE
* Bicuspid valve has two cusps
* Each cusp is connected to a PAPILLARY MUSCLE via CHORDAE TENDINEAE
Where does the LV pump oxygenated blood to?
to the AROTA via the AORTIC VALVE
What makes up the Interventricular septum?
- Membranous part
- Muscular part
What is the Interatrial septum vs. the Interventricular septum?
Interatrial septum
* Very thin
* Separates right and left atria
* Contains fossa ovalis (an embryological remnant)
Interventricular septum
* In the same plane as the
interventricular sulcus
* Has two parts:
1. Membranous
2. Muscular
What is the Fibrous Skeleton of the heart?
- Same plane as the coronal sulcus and valves
- Attachment for myocardium (cardiac muscle)
- Electrically insulates ventricular myocardium from atrial myocardium
- Attachment for valves cusps
(ALL 4 heart valves are on the SAME plane)
What happens if the Atrioventricular Valves are damaged?
we may not have UNIdirectional BF to the heart
What is the purpose of the Atrioventricular Valves (Tricuspid & Bicuspid)?
Valves allow one-way passage of blood
What happens when the atrium contracts?
When the atrium contracts, blood pushes open the
atrioventricular (AV) valve
* The cusps project into the ventricle
* The ventricle is relaxed and fills with blood
What happens when the ventricles contract?
When the ventricle contracts, the pressure of the blood drives the AV valve cusps upward until their edges meet, closing the AV orifice
* Papillary muscles also contract and pull the chordae tendineae taut
* This prevents the valve cusps from being pushed into the atrium
* If the AV valves or chordae tendineae are damaged, blood may regurgitate into the atria
How many cusps are there in the Tricuspid Valve vs. Bicuspid (Mitral) Valve?
3 vs. 2
What is the Pulmonary Valve?
?
What is the Aortic Valve?
?
What are the Semilunar Valves?
The pulmonary and aortic valves are called semilunar valves because of the shape of their cusps
What do the Semilunar Valves allow for?
Semilunar valves allow ejection of blood from ventricles into arteries but prevent black flow of blood
What happens when the ventricles contract?
When the ventricle contracts, blood pressure pushes open the semilunar valve
What happens when the ventricles relax?
When the ventricle relaxes, blood is pushed back towards the ventricle and fill the sinuses behind semilunar cusps
* Free edges of cusps are pushed together, nodules seal the center, closing the opening
What are the Auscultation Points?
closing valves cause heart sounds (therefore use auscultation points to distinguish which part)
- lub = AV valves closing (longer)
- dub = Semilunar valves closing
What are the Coronary Arteries?
Two coronary arteries arise from the root of the ascending aorta:
* Right coronary artery (RCA): from the right aortic sinus
* Left coronary artery (LCA): from the left aortic sinus
What does the Right coronary artery do?
from the right aortic sinus
What does the Left coronary artery do?
from the left aortic sinus
Where does the Left Coronary Artery go?
LCA passes inferiorly under the left atrial auricle and gives off two branches
Where does the Anterior interventricular branch or left anterior descending (LAD) artery travel?
travels in the anterior interventricular sulcus, supplies both ventricles anteriorly
Where does the Circumflex branch (Cx) travel?
travels posteriorly in the coronary sulcus supplying left atrium and ventricle
Where does the Right Coronary Artery (RCA) enter?
RCA enters the CORONARY SULCUS under the right atrial auricle
Where does the RCA travel?
Travels posteriorly in the coronary sulcus supplying right atrium and ventricle
Gives off the RIGHT MARGINAL BRANCH at the inferior surface
Becomes the POSTERIOR INTERVENTRICULAR BRANCH or POSTERIOR DESCENDING ARTERY (PDA), supplying both ventricles posteriorly
What is Coronary Dominance?
- The PDA arises from the RCA in 85% of the population (right dominant coronary circulation)
- The PDA arises from the circumflex artery in 8% of the population (left dominant coronary circulation)
- In the remaining population, the posterior heart receives blood supply from both the RCA and the circumflex (codominant)
Why is the Coronary Dominance important?
- treat someone that has stenosis
- responsible for pap muscle, AV node (imp. structures)
imp. functionally to keep whole heart functioning properly
Where do the Coronary Veins drain?
Coronary veins drain deoxygenated blood from the myocardium
What is the Great cardiac vein?
ascends in the anterior interventricular sulcus to the coronary sulcus (along LAD)
* Travels posteriorly in the coronary sulcus (along Cx)
What is the Middle cardiac vein?
ascends in the posterior interventricular
sulcus to the coronary sulcus (along PDA)
What is the Small cardiac vein?
arises from the anterior right ventricle and travels posteriorly in the coronary sulcus (along RCA)
What is the Coronary sinus?
lies in the posterior coronary sulcus, joins all three veins and return blood to the RIGHT ATRIUM
What is the order of the Conduction System?
- Cardiac excitation begins in the SA NODE
* Located in the right atrial wall just to the right of the opening of SVC - Impulse propagates in both atria via intermodal tracts to the AV node
* Fibrous skeleton insolates ventricular myocardium from atrial depolarization - AV NODE is excited by the impulse from atria (with a delay)
* Located in the inferior posterior part of the interatrial septum - Impulse is passed on by BUNDLE OF HIS in the interventricular septum
* The bundle of His bifurcate into: - RIGHT BUNDLE BRANCH
- LEFT BUNDLE BRANCH
- Terminal portions of these branches send PURKINJIE FIBERS to cardiac muscle
* Impulses are transmitted first to papillary muscles then throughout the ventricular myocardium
* Wave of contraction spreads from apex to AV sulcus
What is the Sympathetic innervention of the heart?
- Presynaptic neurons from T1-
4/5 - Synapse in sympathetic trunk ganglia
- Cardiopulmonary splanchnic nerve to cardiac plexus
- ↑ rate of SA node pacing, ↑ force of contraction, coronary vasodilation
What is the Parasympathetic innervention of the heart?
- Presynaptic neurons in vagus
nerve - Synapse in cardiac plexus
- ↓ rate of SA node pacing, coronary vasoconstriction
What is Referred Pain?
brain does’t know how to map pain from viscera (maps with fibers that are closest to it instead)
- therefore, heart attack can vary in people
Describe Referred Pain?
Ø Cardiac pain occurs due to ischemia and accumulation of metabolic byproducts
Ø Nerves that receive cardiac pain travel back with sympathetic fibers to T1- T4/5 levels of spinal cord
* The pain is misinterpreted as arising from these dermatomes
Ø Phrenic nerves proved sensory innervation to the pericardium
* Pain from pericarditis can be referred to C3-5 dermatomes
What is the Blood Flow order in the Heart?
- Sup. vena cava
- Inf. vena cava
- RA
- Tricuspid valve
- RV
- Pulmonary valve
- Pulmonary trunk
- LA?
- Bicuspid/mitral valve
- LV
- Aortic Valve
- Ascending Aorta
What is included in the Thoracic Aorta & Branches?
A. Ascending aorta
B. Arch of aorta
C. Descending aorta
D. Brachiocephalic trunk
E. Left subclavian a.
F. Right subclavian a.
G. Left common carotid a.
H. Right common carotid a.
I. Posterior intercostal a.
J. Bronchial a.
K. Esophageal a.
L. Superior phrenic a.
What structure is right ant. to aorta?
- esophagus
- trachea
therefore, we have smaller arteries supplying
What is included in the Veins of the Thorax?
A. Subclavian v.
B. Internal jugular v.
C. Brachiocephalic v.
D. Superior vena cava
E. Inferior vena cava
F. Azygos v.
G. Hemiazygos v.
H. Accessory hemiazygos v.
What is included in the Pulmonary Vessels? Do they carry oxygenated or deoxygenated blood?
A. Pulmonary trunk
B. Right pulmonary a.
C. Left pulmonary a.
D. Right pulmonary v.
E. Left pulmonary v.
F. Ligamentum arteriosum
?
What is the Pulmonary system?
- Transports blood to/from the alveoli for gas exchange
- Pulmonary arteries: __________ blood from right ventricle
- Pulmonary veins: __________ blood to left atrium
?
What is the Bronchial system?
- Transports blood to/from root structures of lungs and supporting tissues
- Bronchial arteries: branches of descending aorta
- Bronchial veins: drains into azygos vein and accessory hemi-azygos vein
