Cardiovascular Lab Flashcards
(34 cards)
Auricles
Definition
- Small, wrinkled pouch-like extensions of the left and right atria
- Visible on the external surface of the heart
Function
- Allow expansion of atria to accommodate increased blood volume
- Help temporarily store blood during filling
Key Point
- Not the entire atrium — just a part of the atrial wall that increases capacity
- Named for their ear-like appearance
Pectinate Muscles
The pectinate muscles are found on the anterior surface of the right and left atrial walls and their corresponding auricles.
They are roughly parallel bars of myocardium that run in an anterolateral direction.
Function
- Help increase contractile force of the atrial wall without significantly increasing mass
- Most prominent in the right atrium and right auricle
Key Features
- Create a ridged internal surface
- The posterior atrial wall is smooth in contrast (formed from sinus venosus)
- Separated from the smooth wall by the crista terminalis
Opening of the Coronary Sinus (Right Atrium)
Location
- Found in the posterior wall of the right atrium, just inferior to the opening of the inferior vena cava
Function
- Drains deoxygenated blood from the myocardium via the cardiac veins
- Blood collected in the coronary sinus enters the right atrium for reoxygenation via the pulmonary circuit
Associated Structure
- The opening is partially guarded by the Thebesian valve (a small semicircular fold)
5 opening of coronary sinus
9 Fossa Ovalis
Papillary Muscles
Location
- Found in the ventricles of the heart (right and left)
- Are extensions of the myocardium (composed of cardiac muscle tissue)
Function
- Serve as anchoring points for the chordae tendineae, which attach to the cusps of the AV valves
- Also anchored to the ventricular wall (myocardium)
- During ventricular contraction (systole), they contract with the myocardium to maintain tension on the chordae tendineae
- This prevents AV valve prolapse (backflow of blood into atria)
Anatomy
- Right ventricle: usually has 3 papillary muscles (anterior, posterior, septal)
- Left ventricle: usually has 2 papillary muscles (anterior and posterior)
Clinical Note
- Damage (e.g., in myocardial infarction) can cause valve dysfunction or regurgitation
Location
- Found on the inner walls of both ventricles
Structure
- Irregular ridges and columns of cardiac muscle
- Appear as meaty, raised bundles projecting from the ventricular wall
Function
- Help prevent ventricular walls from sticking together during contraction
- May assist in directing blood flow within the ventricle
- Some trabeculae carneae anchor the papillary muscles and conduction system (e.g., moderator band in right ventricle)
Clinical Note
- Different from pectinate muscles, which are found in the atria
Location
- Wall separating the left and right ventricles of the heart
Structure
- Composed of two parts:
- Muscular portion (thicker, inferior part)
- Membranous portion (thinner, superior part near valves)
Function
- Prevents mixing of oxygenated and deoxygenated blood
- Serves as anchor for ventricular muscle fibers
- Contains part of the cardiac conduction system (bundle of His passes through septum)
Clinical Note
- Defects in the septum (Ventricular Septal Defects, VSDs) are common congenital heart abnormalities
Superior Vena Cava (SVC)
- Drains blood from the head, neck, upper limbs, and upper thorax
- Enters the upper posterior portion of the right atrium
Inferior Vena Cava (IVC)
- Drains blood from the lower limbs, abdomen, and pelvis
- Formed by the union of the right and left common iliac veins
- Enters the lower posterior portion of the right atrium
Pulmonary Trunk and Pulmonary Arteries
Function
- Carries deoxygenated blood from the right ventricle to the lungs for gas exchange
Pulmonary Trunk
- Arises from the right ventricle
- Passes upward and posteriorly, then bifurcates
Branches
- Right pulmonary artery: carries blood to the right lung
- Left pulmonary artery: carries blood to the left lung
Key Point
- Unlike systemic arteries, the pulmonary arteries carry oxygen-poor blood
- Blood is returned oxygenated to the left atrium via the pulmonary veins
Right and Left Pulmonary Veins
Function
- Carry oxygenated blood from the lungs to the left atrium
Structure
- Each side has two pulmonary veins (total of four)
- Right superior pulmonary vein
- Right inferior pulmonary vein
- Left superior pulmonary vein
- Left inferior pulmonary vein
Pathway
- Veins collect blood from lobes of the lungs
- Superior veins drain upper lobes
- Inferior veins drain lower lobes
Key Point
- Pulmonary veins are unique in that they carry oxygen-rich blood
- All four open into the posterior wall of the left atrium
Aortic Arch
Function
- Distributes oxygenated blood from the left ventricle to the systemic circulation
Location
- Continuation of the ascending aorta
- Curves posteriorly and to the left over the heart, then continues as the descending (thoracic) aorta
Major Branches (in order from right to left)
1. Brachiocephalic trunk → divides into:
- Right subclavian artery (right upper limb)
- Right common carotid artery (right side of head and neck)
2. Left common carotid artery → supplies left side of head and neck
3. Left subclavian artery → supplies left upper limb
Key Point
- These branches ensure blood delivery to the head, neck, and upper limbs
Chordae Tendineae
Definition
- Tough, fibrous cords of connective tissue that connect the cusps of the atrioventricular (AV) valves to the papillary muscles in the ventricles
Location
- Found in both right and left ventricles
- Right: attach to tricuspid valve
- Left: attach to bicuspid (mitral) valve
Function
- Prevent valve prolapse during ventricular contraction
- Maintain proper valve closure by holding the valve cusps in place
- Transmit tension from papillary muscle contraction to valve leaflets
Key Point
- Sometimes called the “heart strings”
- Do not open or close the valves—they stabilize them
Pulmonary Semilunar Valve
- Located between right ventricle and pulmonary trunk
- Prevents backflow of blood into right ventricle after it contracts
- Opens when ventricular pressure exceeds pressure in pulmonary arteries
Aortic Semilunar Valve
- Located between left ventricle and ascending aorta
- Prevents backflow of blood into left ventricle
- Opens during ventricular systole, closes during diastole
Right AV Valve (Tricuspid Valve)
- Located between right atrium and right ventricle
- Has three cusps
- Opens during atrial systole to allow blood into right ventricle
- Prevented from inverting by chordae tendineae attached to papillary muscles
Left AV Valve (Bicuspid/Mitral Valve)
- Located between left atrium and left ventricle
- Has two cusps
- Opens to let oxygenated blood flow into left ventricle
- Also stabilized by chordae tendineae and papillary muscles
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Fossa Ovalis
- Location: Right atrial wall, interatrial septum
- Structure: Shallow depression; remnant of foramen ovale from fetal circulation
- Function (fetal): Allowed blood to bypass lungs by flowing directly from right atrium to left atrium
- Function (postnatal): Normally closes at birth; forms fossa ovalis
- Clinical note: If remains open → patent foramen ovale → may allow abnormal shunting of blood
Ligamentum Arteriosum
- Location: Connects aortic arch to pulmonary trunk (left pulmonary artery)
- Structure: Fibrous remnant of the ductus arteriosus (fetal vessel)
- Function (fetal): Allowed blood to bypass lungs by flowing from pulmonary trunk → aorta
- Function (postnatal): Normally closes after birth and becomes ligamentum arteriosum
- Clinical note: Can tear during traumatic deceleration injuries (e.g., car accidents)
Left Coronary Artery (LCA)
- Origin: Arises from ascending aorta
- Branches:
1. Anterior interventricular artery (LAD) → supplies anterior walls of both ventricles and interventricular septum
2. Circumflex artery → curves around left side of heart in coronary sulcus
- Gives off left marginal artery → supplies lateral wall of left ventricle
- Function: Supplies most of the left atrium and left ventricle
Anterior Interventricular Artery (LAD)
- Branch of: Left coronary artery
- Location: Runs in anterior interventricular sulcus
- Supplies:
- Anterior walls of both ventricles
- Anterior 2/3 of interventricular septum
- Clinical note: Common site of occlusion → “widowmaker” infarct
Circumflex Artery
- Branch of: Left coronary artery
- Location: Curves around left side of heart in coronary sulcus
- Branches:
- Left marginal artery (supplies lateral left ventricle)
- Supplies:
- Left atrium
- Posterolateral left ventricle
Right Coronary Artery (RCA)
- Origin: Arises from ascending aorta
- Course: Runs in the right coronary sulcus between right atrium and right ventricle
Branches:
1. Right marginal artery → supplies right ventricle
2. Posterior interventricular artery (in most people) → supplies posterior ventricles and posterior 1/3 of interventricular septum
Supplies:
- Right atrium
- Right ventricle
- Part of left ventricle (posterior)
- SA node (~60% of people)
- AV node (~80% of people)
Clinical Note: Dominance (right vs left) depends on which artery gives rise to the posterior interventricular artery
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Right Marginal Artery
- Branch of: Right coronary artery (RCA)
- Location: Runs along the inferior margin of the heart
- Supplies: Right ventricular wall
- Function: Delivers oxygenated blood to the lateral and anterior portions of the right ventricle
Posterior Interventricular Artery
- Usually a branch of: Right coronary artery (in right-dominant circulation)
- Location: Runs in the posterior interventricular sulcus
- Supplies:
- Posterior walls of both ventricles
- Posterior 1/3 of the interventricular septum
Great Cardiac Vein
- Location: Runs alongside the anterior interventricular artery (LAD) in the anterior interventricular sulcus
- Function: Drains blood from the anterior left ventricle, interventricular septum, and left atrium
- Drains into: Coronary sinus
Coronary Sinus
- Location: Large vein in the posterior coronary sulcus
- Function: Collects blood from all major cardiac veins
- Drains into: Right atrium
- Visible from: Posterior surface of the heart
Middle Cardiac Vein
- Location: Runs in the posterior interventricular sulcus with the posterior interventricular artery
- Function: Drains blood from the posterior ventricles
- Drains into: Coronary sinus
