Chapter 7 - Pericardium and Heart Flashcards
Features of fibrous pericardium
- Made of fibrous tissue
- Parietal layer of serous pericardium is attached to its deep surface
- Blunt apex at level of sternal angle
- Fused with roots of great vessels and pretracheal fascia
- Broad base blended with central tendon of diaphragm
- Connected to body of sternum by superior and inferior sternopericardial ligaments
- Posteriorly, related to principal bronchi, oesophagus, and descending thoracic aorta
- On sides, medistinal surface of lungs, phrenic N, pericardiacophrenic vessels
- Protects the heart from sudden overfilling and prevents overexpansion
Features of serous pericardium
- Double layered
- Inner layer is fused with heart except along cardiac grooves
- Parietal and visceral layers are continuous with each other at roots of great vessels
- Space between parietal and visceral is called pericardial cavity
- Pericardial cavity is filled with fluid for lubrication
Transverse sinus
-Horizontal gap between arterial and venous ends
A: Ascending aorta, pulmonary trunk
P: Superior vena cava
I: Left atrium
-Develops from degenration of central part of dorsal mesocardium
Oblique sinus
A: Left atrium P: Parietal pericardium, oesophagus Sides: Reflections of pericardium -Opens into pericardial cavity below -Permits free pulsation of left atrium -Develops due to rearrangement of veins in venous end
Contents of pericardium
- Heart
- Cardiac vessels and N
- Ascending aorta
- Pulmonary trunk
- Lower part of superior vena cava
- Inferior vena cava
- Pulmonary V
Blood supply of pericardium
- Internal thoracic A
- Musculophrenic A
- Descending thoracic aorta
Nerve supply of pericardium
- Fibrous and parietal: Phrenic N, sensitive to pain
- Visceral: autonomic N, no pain
- Pain of pericarditis: from parietal pericardium
- Pain of angina: Cardiac muscles, vessels
Pericardial effusion
- Cardiac tamponade
- Collection of fluid in pericardal cavity
- Restriction of venous filling is seen
- Cardiac output decreases
- Drained at 5th/6th intercostal space just lateral to sternum
Mitral stenosis
Left atrium enlarges
Compresses oesophagus
Dysphagia
Coronary sulcus
- Atrioventricular sulcus
- Right half of anterior part lodges right coronary A
- Left half lodges circumflex branch of left coronary A
- Overlapped anteriorly by ascending aorta and pulmonary trunk
Interventricular groove
ANTERIOR -nearer to left margin -runs downwards and left POSTERIOR -on inferior/diaphragmatic surface -nearer to right margin
Apex of heart
- Formed entirely by left ventricle
- Directed downwards, forward, to left
- Overlapped by anterior border of lung
- At 5th intercostal space
Base of heart
- Also called posterior surface
- Mainly left atrium
- Openings of 4 pulmonary veins and vena cavae
- Related to T5-T8
- Separated from vertebral column by pericardium, pulmonary V, oesophagus and aorta
Borders of the heart
Upper: Oblique, mainly by left atrium
Right: Vertical, right atrium, from SVC to IVC
Inferior: Horizontal, mainly right ventricle, IVC to apex
Left: Oblique and curved, mainly left ventricle, apex to left auricle
Sternocostal surface
- Formed mainly by right atrium and ventricle
- Mostly covered by lungs except at cardiac notch
- Uncovered part is dull in percussion–area of superficial cardiac dullness
Diaphragmatic surface
-Rests on central tendon of diaphragm
-Left 2/3 - Left ventricle
Right 1/3 - Right ventricle
-Traversed by posterior interventricular groove
Left surface
- Mainly by left ventricle and auricle
- Crossed by coronary sulcus
- Related to left phrenic N, left pericardiacophrenic vessels, pericardium
Right atrium forms
- Right border
- Part of upper border
- Sternocostal surface
- Base of heart
External features of right atrium
- Vertically elongated
- Receives SVC and IVC
- Upper end forms right auricle
- Shallow vertical groove from SVC to IVC – sulcus terminalis produced by muscular ridge crista terminalis
- Right atrioventricular groove lodges right coronary A and small cardiac V
Right auricle
- Covers root of ascending aorta and infundibulum of right ventricle
- Margins are notched
- Sponge like interior to prevent free blood flow
Inlets of right atrium
- SVC and IVC
- Coronary sinus
- Anterior cardiac V
- Thebesian V
- Right marginal V
Interior divisions of right atrium
- Sinus venarum - smooth posterior part
- Pectinate - rough anterior part
- Interatrial septum
Sinus venarum
- Derived from right horn of sinus venosus
- SVC, IVC, coronary sinus and thebesian V open into it
- Opening of IVC is guarded by rudimentary Eustachian valve
- Opening of coronary sinus is guarded by thebesian valves
- Intervenous tubercle of Lower is a projection just below opening of SVC to direct blood into right ventricle in IUL
Pectinate part
- Derived from primitive atrial chamber
- Has transverse muscular ridges called musculi pectinati
- They arise from crista terminalis
- The run towards the atrioventricular foramen
Interatrial septum
-Derived from septum primum and septum secondum
-Fossa ovalis is seen
-Annulus ovalis is the margin of fossa ovalis.
Represents lower free edge of septum secondum.
Anteriorly it is continuous with valve of IVC
Right ventricle forms
- Inferior border
- 2/3 sternocostal surface
- 1/3 inferior surface
Features of coronary arteries
- Blood flows during diastole
- 1.5-5.2 nm diameter
- Left is larger and supplies to most of myocardium
- Functional end arteries. Anastamoses cannot compensate during thrombosis
- Origin of posterior interventricular A determnes dominance
Origin and course of right coronary A
- From anterior aortic sinus
- Emerges b/w pulmonary trunk and right auricle
- Runs in right anterior coronary sulcus
- Reaches diaphragmatic surface
- Runs in right posterior coronary sulcus
- Reaches posterior interventricular groove
- Anastamoses with circumflex branch of left coronary A
Branches of right coronary A
- Atrial: anterior, posterior, lateral–supply SA node
- Right conus- forms ANNULUS OF VIEUSSENS around pulmonary trunk with left conus
- Ventricular: anterior, posterior
- Right marginal- runs along inferir margin till apex
- Posterior interventricular- suplies AV node
Area of distribution of right coronary A
- Right atrium
- Greater part of right ventricle
- Small part of left ventricle
- Posterior 1/3 of IV septum
- Whole of conducting system
Origin and course of left coronary A
- From left posterior sinus
- Emerges b/w pulmonary trunk and left auricle
- Gives off anterior interventricular branch and continues as circumflex A
- Circumflex A runs in left anterior coronary sulcus
- Anastamoses with right coronary A near posterior interventricular groove
Branches of left coronary A
- Anterior interventricular branch: In anterior IV groove. Gives off left conus, septal and anterior ventricular branches
- Circumflex branch gives left marginal, anterior, posterior ventricular, and atrial branches
Area of distribution of left coronary A
- Left atrium
- Greater part of left ventricle
- Small part of right ventricle
- Anterior part of IV septum
- Left branch of AV bundle