Thorax: Heart Flashcards
Fibrous Skeleton of the Heart
- Formed by 4 fibrous rings, 2 fibrous trigones, and the membranous septum
- Separates atria from the ventricles
- Supports and provides attachment for heart valves
- Electrical insulation
Surfaces of the Heart
- Anterior (sternocostal): right ventricle
- Inferior (diaphragmatic): mostly left ventricle, some right
- Left pulmonary: left ventricle
- Right pulmonary: right atrium
- Posterior: left atrium
Anterior (Sternocostal) Surface of the Heart
- Right ventricle
Inferior (Diaphragmatic) Surface of the Heart
- Mostly left ventricle, some right
Left Pulmonary Surface of the Heart
- Left ventricle
Right Pulmonary Surface of the Heart
- Right atrium
Posterior Surface of the Heart
- Left atrium
Coronary Sulcus (AV Sulcus)
- Groove that separates atria from ventricles (external feature)
Anterior and Posterior Interventricular Sulci
- Groove over the ventricular septum
Borders of the Heart
- Right: right atrium
- Inferior: right and left ventricle
- Left: left ventricle
- Superior: left and right atria
Crux of the Heart
- Junction of AV sulcus and posterior interventricular sulcus
Apex of Heart
- Formed by left ventricle
- Located 5th intercostal space about midclavicular line
- About a hands width from sternum, ~ 9cm
Base of Heart
- Formed by mostly the left atrium (some right atrium)
- Faces posteriorly
- Anterior to esophagus, aorta, T6-9 vertebrae
- Receives inflow vessels
Coronary Arteries
- Travel in coronary sulcus (atrioventricular sulcus)
- Deep to epicardium embedded in fat
Left and Right Coronary Arteries
- 1st branches off the aorta (ascending)
- Arises from the aortic sinuses
Right Coronary Bracnhes
- Conal artery
- Sino-atrial nodal (~60% of people)
- Right marginal artery
- Posterior interventricular (posterior descending) in ~ 70% of people (right heart dominant)
- AV nodal artery (~80% of people)
Left Coronary Branches
- Anterior interventricular (left anterior descending) artery
- Circumflex
Anterior Interventricular (Left Anterior Descending) Artery
- Diagonal branches
- Septal branches
Circumflex
- SA nodal (40%)
- Left posterior ventricular branches
- Left marginal artery
- Posterior interventricular, in ~10% (left dominant heart)
Coronary Sinus
- Main vein of the heart
- Drains into the right atrium
Tributaries of Coronary Sinus
- Great cardiac vein
- Middle cardiac vein
- Small cardiac vein
- Posterior vein of the left atrium
- Oblique vein of left atrium
Left Marginal Vein
- Drains into great cardiac vein
Anterior Cardiac Veins
- Drain directly into the right atrium
Right Atrium
- Right auricle
Internal Right Atrium
- Sinus venarum
- Crista terminalis
- Pectinate muscle
- Interatrial septum
- Fossa ovalis
Right Atrium Openings
- SVC
- IVC
- Coronary sinus
- Right atrioventricular orifice
- Anterior cardiac veins
Left Atrium
- Left auricle
- Smooth wall except for pectinate muscle
- Slightly thicker wall vs. right atrium
- Interatrial septum
- Depression (floor of the fossa ovalis)
Left Atrium Openings
- Left atrioventricular orifice
- 4 pulmonary veins
Right Ventricle Openings
- Right AV orifice
- Pulmonary orifice
Interior Right Ventricle
- Trabeculae carneae
- Tricuspid valve (right AV valve)
- Chordae tendinae
- Papillary muscle
- Pulmonary valve
- Septomarginal trabeculae (moderator band)
- Right bundle branch
Trabeculae Carneae
- Muscle elevations in right ventricle
Tricuspid Valve (Right AV Valve)
- Contains chordae tendinae
Papillary Muscles in Right Atrium
- Anterior (A)
- Posterior (P)
- Septal (S)
Septomarginal Trabeculae (Moderator Band)
- Holds right bundle branch in right ventricle
Left Ventricle
- Thicker myocardium
- Trabeculae carneae
- Larger papillary muscles (anterior and posterior)
- Left AV orifice
- Mitral valve (left AV valve, bicuspid valve)
- Chordae tendinae
- Papillary muscle
- Aortic orifice
- Aortic valve
Heart Septum
- Interatrial septum
- Interventricular septum
- Muscular part (thick)
- Membranous part (thin)
- Interventricular part
- Atrioventricular septum
Heart Valves
- Prevent retrograde blood flow
AV Valves
- Papillary muscle contraction puts tension on chordae tendinea
- Prevents AV valve prolapse during systole
Regurgitation
- AV valve prolapse during systole
Semilunar Valves
- No chordae tendineae
- Closed by back pressure of ejected blood into the pulmonary trunk and aorta
Semilunar Valves
- Each has 3 cusp, each with:
- Lunules and a nodule
- Aortic: posterior, right, left cusps
- Pulmonary: anterior, right, left cusps
Auscultatory Sites
- Isolates potential valve sounds from other valves
- Pulmonary valve
- Aortic valve
- Mitral valve
- Tricuspid valve
Pulmonary Valve Auscultatory Site
- 2nd left intercostal space, left sternal border
Aortic Valve Auscultatory Site
- 2nd right intercostal space, right sternal border
Mitral Valve Auscultatory Site
- 5th left intercostal space, ~ midclavicular line
Tricuspid Valve Auscultatory Site
- 4th left intercostal space, left sternal border
- Left sternal border at the inferior aspect of the sternum
- 5th at left or right sternal border also used
Intrinsic Conduction System
- SA node
- AV node
- AV Bundle
- Left and right bundle branches
- Subendocardial branches (Purkinje fibers)
Sinu-Atrial (SA) Node
- Located at junction of SVC and right atrium
Atrioventircular (AV) Node
- Located near opening of coronary sinus in the right atrium
Atrioventricular (AV) Bundle
- Bridges atrium and ventricle, passes through fibrous skeleton
Left and Right Bundle Branches
- Travel through muscular IVS
- Branches of the right pass through moderator band (septomarginal trabecula)
Extrinsic Regulation by Autonomic Nervous System
- Influence HR, impulse conduction speed, contractile force, blood flow
Autonomic Innervation of the Heart
- Sympathetic
- Parasympathetic
Presynaptic (Preganglionic) Innervation of SNS
- Originate IML of T1-4(5) levels
- Synapse in cervical sympathetic ganglia
- Upper thoracic paravertebral ganglia
Postsynaptic (Postganglionic) Innervation of SNS
- Superior, middle, inferior cardiac nerves from cervical paravertebral ganglia
- Cardiac branches from thoracic paravertebral ganglia
Parasympathetic (Preganglionic) Innervation
- Originate brainstem
- Travel in Vagus nerve to cardiac plexus
Cardiac Plexus
- Autonomics pass through this
- Postsynaptic sympathetic neurons from cervical and upper thoracic paravertebral ganglia
- Presynaptic neurons traveling in the vagus
