Heart Anatomy

Heart

is a hollow muscular organ that is somewhat pyramid shaped and lies within the pericardium in the mediastinum

The heart connected at its ———- to the ———- but otherwise lies free within the pericardium.

Base , great blood vessels

What is mediastinum?

The mediastinum is the central compartment of the thoracic cavity, located between the two lungs, that contains the heart, great vessels, trachea, esophagus, thymus, and other structures (except the lungs).

What are the types of mediastinum?

• Superior mediastinum

• Inferior mediastinum, which is further divided into:
  

  • Anterior

  • Middle (contains the heart)

  • Posterior

What is pericardium?

The pericardium is a fibroserous sac that encloses the heart and the roots of the great vessels.

Functions of Pericardium

is to restrict excessive movements of the heart as a whole

serve as a lubricated container in which the different parts of the heart can contract.

Location of pericardium

The pericardium lies within the middle mediastinum

posterior to the body of the sternum and the 2nd to the 6th costal cartilages and anterior to the 5th to the 8th thoracic vertebrae.

What are the types of pericardium?

Fibrous and Serous Pericardium

Fibrous pericardium:

It is firmly attached below to the central tendon of the diaphragm.and ABOVE to the outermost layer of the great blood vessels

Fibrous pericardium

This is the tough, outermost layer of your pericardium. It’s made of connective tissue that prevents your heart from expanding too much. It attaches to your great vessels (at the top of your heart) and to the central tendon of your diaphragm (at the bottom of your heart).

Serous pericardium

This is the inner layer of your pericardium. It’s actually made of two layers, described below. Your serous pericardium produces pericardial fluid that lubricates your heart as it beats.

What are the Layers of Serous pericardium:

Parietal and Viscera

Parietal layer:

• Parietal layer of the serous pericardium: This is the outer layer that’s firmly attached to your fibrous pericardium. There’s no space between them.

Visceral layer:

• Visceral layer of the serous pericardium: This is the innermost layer of your pericardium. It directly covers your heart and the roots of your great vessels. The portion that covers your heart is also known as your epicardium.

What is pericardial cavity?

Your pericardial cavity is the space between the two layers of your serous pericardium. This space holds your pericardial fluid.

What are and how many surfaces pf heart we have?

5 Surfaces

1- Anterior surface

2- Inferior ( Diaphragmatic ) surface

3- Base ( posterior) Surface

4- Left pulmonary surface

5- Right pulmonary surface

Anterior surface

Right Ventricle + small portion of right atrium

Inferior ( Diaphragmatic ) surface

Left ventricle+ small portion of right ventricle

Left pulmonary surface

Broad and convex, Left ventricle + small portion of left atrium

Right pulmonary surface

Broad and convex, Right atrium

Left ventricle and right ventricle are separated by:

Posterior interventricular groove

Boarders of the heart:

Right

Left

Superior

Inferior

Right boarder:

Right atrium

Left boarder

Left ventricle + slightly by left auricle

Inferior boarder

Right ventricle and small portion of right atrium and left ventricle.

Superior boarder

zis formed by both atria where the greatvessels enter the heart

Right boarder of the medistainal shadow

• right brachiocephalicvein

• superior vena cava

• right atrium

• sometimes inferior vena cava.

Left boarder limitation:

extends from apex to lower border of left second costal cartilage

about 2 cm from sternal margin

Lower boarder :

It passes from the right sixth costal cartilage to the apex, which is normally in the left fifth intercostal space in the midclavicular line

On the outside of the heart at the junction between the right atrium and the right auricle is a :

Vertical groove: Sulcus Terminalis

The junction on the inside forms a

Ridge : Crista Terminalis

The main part of the atrium that lies ———- to the ridge is ———— walled and is derived embryologically from the ————

Posterior—Smooth—Sinus venosus

• The part of the atrium in front of the ridge ———- by bundles of muscle fibers, the ———-

which run from the crista terminalis to the auricle. This anterior part is derived embryologically from the ———-

Roughned—Muscli pectinati—-primitive atrium

Sulcus terminalis

A shallow vertical groove on the external surface of the right atrium that marks the junction between the smooth posterior part (sinus venarum) and the rough anterior part

Crista Terminalis

A muscular ridge on the internal wall of the right atrium that corresponds to the sulcus terminalis externally; it separates the smooth sinus venarum from the rough area with pectinate muscles.

What are the opnings in the right atrium?

SVC

IVC

CORONARY SINUS

RIGHT ATRIOVENTRICULAR ORIFICE

Does SVC has a valve?

No it has no valve

Which is bigger SVC or IVC

IVC

Does IVC has a valve ?

Yes, Non functioning rudimentary valve called ( Eustachian valve )

Whats the function of Coronary Sinus?

The function of the coronary sinus is to drain deoxygenated blood from the heart muscle (myocardium) into the right atrium, where it will then go to the lungs to be reoxygenated.”

Where does Coronary Sinus located?

Between IVC and Right atrioventricular orifice

The right atrioventricular orifice’s valve name ?

Tricuspid valve

Right atrioventricular orifice lies ——- to the IVC

Anterior

Fetus remenants of right atrium

• 🔶Fossa + Annulus ovalis → from foramen ovale

• 🔸Eustachian valve → from fetal blood-flow direction system

Seperates right atrium from the left atrium——-

Atrial septum

Right ventricle communicates with the Pulmonary Trunk through ———

Pulmonary Orifice

As the cavity approaches the pulmonary orifice it becomes ———- at which point it is referred to as the ———

Funnel shaped — Infundibulum

The projecting ridges give the ventricular wall a spongelike appearance and are known as

Tuberculae carneae

Tuberculae carneae

• These are irregular muscular ridges found on the inner walls of the ventricles.

• They help:

  • Prevent suction that would impair blood flow.

  • Strengthen the ventricular wall.

• They are of 3 types:

Make a comparison between the wall of right atrium and right ventricle

The walls of the right ventricle are much thicker than those of the

right atrium and show several internal projecting ridges formed of muscle bundles.

The musculi pectinati

Runs from crista terminalis to the auricle

First type of trabeculae carneae:

first type comprises the papillary muscles, which

project inward, being attached by their bases to the ventricular wall; their apices are connected by fibrous chords (the chordae tendineae) to the cusps of the tricuspid valve .

Second type

second type is attached at the ends to the

ventricular wall, being free in the middle. One of these, the moderator (septomarginal band, ) crosses the ventricular cavity from the septal to the anterior wall.

Third type

The third type is simply composed of prominent ridges.

Tricuspid valve composed of two types of tissue what are they?

Epithelium tissue and connective tissue ( collagen and elastic )

Tricuspid valve :

Guards the right atrioventricular orifice consist of. 3 cusps formed by endocardium fold and connective tissue

Cusps of tricuspid valve

anterior, septal, and inferior (posterior) cusps.

• The bases of the cusps are attached to the fibrous ring of the skeleton of the heart ‘

• whereas their free edges and ventricular surfaces are attached to the chordae tendineae

Pulmonary valve

guards the pulmonary orifice and consists of three semilunar cusps formed by folds of endocardium with some connective tissue enclosed.

• No chordae or papillary muscles are associated with these valve cusps; the attachments of the sides of the cusps to the arterial wall prevent the cusps from prolapsing into the ventricle.

At the root of the pulmonary trunk are three dilatations called

Sinuses

The three semilunar cusps are arranged with

two anterior one posterior

Anterior

Right cusps

Behind————lies the serous pericardium, and the fibrous pericardium separates it from the esophagus .

Left atrium

Left atrium

The interior of the left atrium is smooth, but the left

auricle possesses muscular ridges as in the rightauricle. The auricle contains musculi pectinateae

Opnings in the left atrium

The four pulmonary veins, two from each lung, open through the posterior wall and have no valves.

Left atrioventricular orifice with mitral valve guarding

Left ventricle

The left ventricle communicates with the left atrium through the atrioventricular orifice and with the aorta through the aortic orifice

Comparison between the wall of the right and left ventricle

The walls of the left ventricle are three times thicker than those of the right ventricle.

Trabeculae carneae in the left ventricle

There are well-developed trabeculae carneae, two large papillary muscles, but no moderator band.

Trabeculae carneae in left ventricle again

• BUT we don’t classify them into 3 types like we do in the right ventricle.

Instead:

In Left Ventricle

• You mainly describe:

  • ✅ Papillary muscles (2 major ones: anterior & posterior)

  • ✅ Trabeculae carneae (just general ridges on the wall — not divided into types)

• No special classification like the right side.

• Moderator band (septomarginal trabecula) is absent in left ventricle — it’s only in the right ventricle.

What is aortic vestibule ?

• The aortic vestibule is the smooth part of the left ventricle just below the aortic valve.

• It leads up to the aorta.

What is vestibule?

A vestibule just means a small smooth-walled chamber or passage leading to an opening — like a hallway before a door.

Infundibulum and aortic vestibule

• 🫀 Right Ventricle → Infundibulum → Pulmonary Valve

• 🫀 Left Ventricle → Aortic Vestibule → Aortic Valve

The 3 types of trabeculae carneae are ( right ventricle )

Papilary muscle

Bridge

Ridge

Mitral valve

guards the atrioventricular orifice .

• It consists of two cusps, one anterior and one posterior, which have a

structure similar to that of the cusps of the tricuspid valve.

• The attachment of the chordae tendineae to the cusps and the

papillary muscles is similar to that of the tricuspid valve.

Difference and similarities between the tricuspid and mitral valve

Because the structure of cusps, chordae, papillary muscles, and function are the same — only the number of cusps is different.)

Blood supply to the heart

The arterial supply of the heart is provided by the right and left

coronary arteries, which arise from the ascending aorta immediately

above the aortic valve

Right coronary artery

arises from the anterior aortic sinus of the ascending aorta and runs forward between the pulmonary trunk and the right auricle .

• It descends almost vertically in the right atrioventricular groove, and at the inferior border of the heart it continues posteriorly along the atrioventricular groove to anastomose with the left coronary artery in the posterior interventricular groove.

• The following branches from the right coronary artery supply the right atrium and right ventricle and parts of the left atrium and left ventricle and the atrioventricular septum.

Right coronary artery branches :

1. The right conus artery supplies the anterior surface of the pulmonary conus (infundibulum of the right ventricle) and the upper part of the anterior wall of the right ventricle.

• 2.The anterior ventricular branches are two or three in number and supply the anterior surface of the right ventricle. The marginal branch

is the largest and runs along the lower margin of the costal surface to reach the apex.

• 3.The posterior ventricular branches are usually two in number and supply the diaphragmatic surface of the right ventricle.

4.The posterior interventricular (descending) artery runs toward the apex in the posterior interventricular groove.

• A large septal branch supplies the atrioventricular node.

• In 10% of individuals the posterior interventricular artery is replaced by a branch from the left coronary artery.

• 5. The atrial branches supply the anterior and lateral surfaces of the right atrium.

• in 35% of individuals it arises from the left coronary artery.

Left coronary artery

• which is usually larger than the right coronary artery, supplies the major part of the heart, including the greater part of the left atrium, left ventricle, and ventricular septum.

• It arises from the left posterior aortic sinus of the ascending aorta and passes forward between the pulmonary trunk and the left auricle .

• It then enters the atrioventricular groove and divides into an anterior inter-ventricular branch and a circumflex branch.

LCA Branches

1.The anterior interventricular (descending) branch runs downward in the anterior interventricular groove to the apex of the heart .

• In one third of individuals it ends at the apex of the heart.

• The anterior interventricular branch supplies the right and left ventricles with numerous branches that also supply the anterior part of the ventricular septum.

2.The circumflex artery is the same size as the inter-ventricular artery .It winds around the left margin of the heart in the atrioventricular groove.

• A left marginal artery is a large branch that supplies the left margin of the left ventricle down to the apex.

Variations of blood supply to the heart ?

Variations in the blood supply to the heart do occur,

the most common variations affect the blood supply to_________, here the ——,——-,——, of ___________artery are variable

Diaphragmatic surface, origin,size,distribution,,PDA

What is collateral circulation?

Anastomoses between the terminal branches of the right and left coronary arteries

Is collateral circulation large enough to supply the heart in case one of the large branches becomes blocked?

No it’s not that large dude

A sudden block of one of the larger branches of either coronary artery usually leads to:

Myocardial death ( Myocardial infarction )