NOTA KEYBOARD 1 : HEART

Mula mula kita kena tahu la, heart tue ada 4 Chambers, atau 4 ruang didalamnyer iaitu

-Right Atrium,

-Right ventricle,

- left atrium dan

- left ventricle.

*dalam gambar kat atas, korunk kena boleh lae untuk meneka dan tahu dimana location each chambers tue yer.. ok?? pass??

anda pasti??

then, kita kena tahu tentang pericardium. apa tue erk?? pericardium tue??

pericardium is fibroserous sac taht enclose the heart and the roots of great vessel.. paham ker tak nie?? back to basic, pericaridum nie merupakan lapisan yang melinduingi jantung dan saluran darah yg penting di jantung kita seperti vena cava dan aorta..

pericardium ada 2 lapisan:

1) Fibrous pericardium

2) serous pericardium

*pericardial cavity ----> space between parietal dan visceral pericardium ---> as lubricant

ok, sekarang kita tengok pericardial sinuses plak yer,

pericardial sinuses plak ada pockets/ recess of pericardial cavity for by reflection of serous pericardium. ada 2 types of sinuses iaitu :

1)oblique sinuses

2) transverse sinuses

Pericardium.

strong fibrous layer, double walled sac w/ heart w/in

originates from intraembryonic somato and splanchno pleura

Layers of Heart itself: (sup –> deep)

Fibrous pericardium -
- bound to central tendon of diaphragm for deep inspiration,heart follows diaphragm, so heart is more vertical,
- in deep expiration, heart rises due to upward movement of diaphram – heart is more horizontal
Serous pericardium
- Has a parietal layer - stong dense reg CT, prevent heart from over dilating
- Visceral layer – simple squamous epithelium (mesothelium), that lines the heart itself aka Epicardium
- B/w 2 layers = Pericardial cavity
Subepicardial CT
Myocardium – muscular wall – striated cardiac m
Subendocardial CT
Endocardium - simple squamous epithelium (endothelium), same epith as blood vessels

Pericardium moves along w. movements of structures around it b/c:

fused w/ tunica adventia of great vessesl entering/leaving heart
attached to post surface of sternum by sternopericardial ligaments
fused w. central tendon of diaphragm

Blood supply = mostly from pericardiophrenic a (int thoracic a) musculophrenic a (int thoracic a),bronchiol, esophageal, sup phrenic a (thoracic aorta), coronary arteries

Reflections of pericardium: where 2 layers of pericardium meet each other

@ arterial end – Transverse sinus
- where pul a and aorta leave heart,
- when doing surgery on aorta or pulmonary a, can stop circulation to this area by making a stitch through this sinus,
- reach by reaching under pulmonary trunk and ant to SVC
@ venous end – Oblique sinus =
- where SVC,IVC pulmonary v enter heart,
- reach via inserting finger under apex of heart and pushing up and right towards root of R lung

Development of Sinuses:

Form during embryonic life due to folding of embryonic heart tube
As heart tube folds, venous end moves posterior and up, so venous end then is up by arterial end, separated bytransverse sinus
As veins of heart grow and expand, oblique sinus is formed, a recess, a blind sac behind post side of the heart

Innervation = phrenic n (C3-C5), vagus n (CN X), SNS trunk ->> sensitive to pain

pericardial pain -> diffuse to sternum -> substernal pain -> may due to pericarditis

ok sekarang kita tinjau tinjau gambar plak yer.. kita tengok general features or characteristic tentang heart nie. OK??

1- heart -> hollow muscular + conical in shape

the anterior surface of the heart is also known as the sternocostal surface for obvious reasons. Notice the ruffled edges of the left (LA) and right (RA) atria. These are the ones to use for orientation. Since we are looking at the anterior surface of the heart, they can be seen.Note that the anterior surface shows parts of each of the four chambers of the heart:

right atrium (RA)
left atrium (LA)
right ventricle (RV)
left ventricle (LV)

Also note the three borders of the heart:

right border (1) made up of the right atrium
inferior border (2) made up of right atrium, right ventricle and left ventricle
left border (3) made up of the left ventricle

When you view the heart in a radiograph, these borders will be obvious.Finally learn the great vessels of the heart and their relationships to one another. I usually learn the vessels from the view of blood circulating through the heart, starting with the return of blood from the body to the heart.

superior and inferior venae cavae
pulmonary trunk and left and right branches
pulmonary veins (usually 4 in number but this can vary
ascending aorta

The last item to identify is the remains of the embryonic connection between the pulmonary trunk and aortic arch, the ligamentum arteriosum. At one stage in development, the lungs were not functional so the blood was shunted into the arterial system at this site. Oxygen exchange in the embryo occurred at the placenta and not the lungs.

The adjacent figure shows the posterior aspect of the heart. Its identifiable features include:

right atrium (RA)
left atrium (LA)
right ventricle (RV)
left ventricle (LV). Notice that most of the left ventricle is posterior.

The left and right ventricles make up the diaphragmatic surface of the heart. This part rests on the fibrous part of the diaphragm.
The left atrium makes up the so-called base of the heart. When the body is in the supine position (lying on its back), the heart rests on its base and the apex of the heart (the tip of the left ventricle) projects up and to the left. The same three borders are seen from the back of the heart:

right (1)
inferior (2)
left (3)

When the vessels are removed from the heart, certain sulci (grooves) can be seen and separated the various chambers of the heart.

From the anterior view of the heart, the anterior interventricular and coronary sulci can be seen (the darker brown areas). The anterior interventricular sulcus separates the right and left ventricles. The anterior part of the coronary sulcus separates the right atrium from the right ventricle.

From the posterior view of the heart, the posterior part of the coronary sulcus and the posterior interventricular sulcus can be seen. From this view, the coronary sulcus can be seen to separate the left and right atria from the left and right ventricles. The posterior interventricular sulcus separated the right ventricle from the left ventricle and if followed inferiorly, it can be seen to be almost continuous with the anterior interventricular sulcus.

*********************************************************

Coronary Arteries and Cardiac Veins

The heart muscle is supplied by the coronary arteries which are direct branches of the ascending aorta, so the heart muscle gets the freshest blood possible. The heart muscle is drained by the cardiac veins. Most of the venous drainage is by was of the coronary sinus into the right atrium. A small amount of blood drains directly into the right atrium by way of the anterior cardiac veins.

The heart is supplied by two major coronary arteries, the right and left.The left coronary divides into the anterior interventricular and circumflex branches almost immediately after it arises from the left side of the ascending aorta. The anterior interventricular lies in the anterior interventricular sulcus and is also known as the left anterior descending artery. The circumflex branch lies in the coronary sulcus and forms an anastomosis with the right coronary in the posterior part of this sulcus.
The anterior interventricular artery is the one most often involved in coronary occlusions and is often the one that is bypassed in bypass cardiac surgery.

The right coronary lies in the coronary sulcus and gives rise to an important branch immediately after leaving the ascending aorta. This is the anterior right atrial branch which gives rise to the important nodal artery. This artery supplies the sinoatrial node (SA node) or pacemaker of the heart. When this vessels loses its ability to supply the node, a person usually needs to have a pace maker placed in their thoracic wall to take the place of the original pace maker.
The right coronary continues in the coronary sulcus, giving a branch along the right inferior border of the heart called the marginal artery.
Finally the right coronary gives rise to the posterior interventricular (or descending) branch, and then anastomoses with the circumflex artery from the left coronary.

When the heart is viewed from the back, the most obvious structure lying in the coronary sulcus is the coronary sinus. This sinus receives most of the venous blood from the heart and empties into the right atrium. Its tributaries are the small cardiac vein, the middle cardiac vein and the greater cardiac vein. There is a small vein that arises along the left side of the left atrium just beneath the lower left pulmonary artery (called the oblique vein. This vein is a remnant of the embryonic left superior vena cava.The arteries seen in the back of the heart are the circumflex coronary artery, the terminal part of the right coronary artery and its posterior interventricular branch.

*********************************************

Internal Structure of the Chambers of the heart

The right atrium has a forward extension into its auricle. This space is lined by ridges of muscle called pectinate muscles and are not shown in the diagram.Starting with the right atrium, the internal structures are:

fossa ovalis
openings of the superior (SVC) and inferior (IVC) venae cavae and the coronary sinus opening (CS) The entrance of the inferior vena cava and coronary sinus may be covered with small valve leaflets (valve of the interior vena cava and valve of coronary sinus).
The SA node is located at the junction or the superior vena cava with the right atrium. The AV node is located in the lower part of the interatrial septum near the opening of the coronary sinus.

The right atrium and right ventricle communicate with each other by way of the tricuspid valve. As the name implies, it has three leaflets. As you observe the chamber of the right atrium, notice the following:

chordae tendineae, attaching the free border of the valve cusps (leaflets) to either papillary muscles (PM) or directly to the wall of the heart chamber. Papillary muscles are only found in the ventricles of the heart.
the rough lining of the ventricular wall is called trabeculae carneae, because of their meaty appearance
the anterior papillary that has an attachment to the interventricular wall known as the septomarginal trabecula or the moderator band.

Blood leaves the right ventricle and passes through the pulmonary trunk to the lungs. Oxygenated blood returns to the left atrium of the heart from the lung through the pulmonary veins. The left atrium doesn't have much to talk about. There is an extension into the small auricles which have pectinate muscles in its walls.The left atrium communicates with the left ventricle through the mitral or bicuspid valve. Just as in the right ventricle, the valve cusps or leaflets connect to the papillary muscles (PM) by way of chordae tendineae. The inner walls of the left ventricle is thrown into folds of trabeculae carneae just as in the right ventricle. Note, in particular that the left ventricular has a much thicker wall than the right ventricle. If the heart is not too diseased, this is how you can tell the difference between the two ventricles.
Note the interventricular septum (IVS) between the two ventricles.
Blood leaves the left ventricle through the ascending aorta and is then sent to body organs and tissues.

****************************************************8

Heart Valve Positions

This diagram is a special dissection that shows the four heart valves and their relationship to one another. The view is from the top after the left and right atria have been removed.Start with the right atrioventricular valve (tricuspid valve). It has an anterior (A), posterior (P) and septal (S) cusp.
The left atrioventricular valve (mitral valve) has an anterior (A) and a posterior (P) cusp.
The pulmonary and aortic valves are both tricuspid. During embryonic development, these two vessels were one. With rotation of the heart and a separation of the single channel, the pulmonary trunk ends up anterior and the ascending aorta ends up posterior. The original contained four primitive valve cusps, an anterior, left and right and a posterior. The left and right valves were divided during the separation so that a left and right ended up in both the pulmonary (or anterior channel) and the ascending aorta (or posterior channel). In the adult, this development results in an anterior displaced pulmonary trunk with an anterior and a left and right cusp, while the posterior displaced ascending aorta has a left and right coronary cusp and a posterior cusp. The coronary cusps are named because the origins of the left and right coronary arteries are found lateral to these cusps.

*************************************************

Innervation of the Heart

The strength and frequency of the heart beat is controlled by the autonomic nervous system. Both parasympathetic and sympathetic parts of the autonomic nervous system are involved in the control of the heart.
The sympathetic fibers arise from segments T2-T4 of the spinal cord and are distributed through the middle cervical and cervico-thoracic (or stellate) ganglia and the first four ganglia of the thoracic sympathetic chain. The sympathetic fibers pass into the cardiac plexus and from there to the SA node and the cardiac muscle. The effect of the sympathetic nerves at the SA node is an increase in heart rate. The effect on the muscle is an increase in rise of pressure within the ventricle, thus increasing stroke volume.
The vagus provides the parasympathetic control to the heart. The effect of the vagus at the SA node is the opposite of the sympathetic nerves, it decreases the heart rate. It also decreases the excitability of the junctional tissue around the AV node and this results in slower transmission. Strong vagal stimulation here may produce AV block.

The heart also has an internal nervous system made up of the SA (sinuatrial node) and the AV (atrioventricular) node. The AV bundle (His) leaves the AV node near the lower part of the interatrial septum and splits over the upper part of the interventricular septum into a left bundle branch (LBB) and a right bundle branch (RBB). The cardiac muscle is then supplied by branches of the two bundles.

from http://home.comcast.net/~wnor/thoraxlesson4.htm

***************************************************************************