The cardiovascular system consists of the heart and blood vessels. The heart is a hollow muscular pump made of four chambers. It is located in the mediastinum and is pyramidal in shape. Blood flows from the right atrium to right ventricle through the tricuspid valve and then to the lungs via the pulmonary trunk. Oxygenated blood returns to the left atrium via the pulmonary veins and flows to the left ventricle through the mitral valve. The left ventricle then pumps oxygenated blood through the aorta to the rest of the body. The heart is supplied with blood by the right and left coronary arteries and drained by the coronary sinus.

1. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Unit 7: The cardiovascular system
:
The cardiovascular system is formed of the heart and the blood vessels
A. The HEART
The heart is a hollow muscular pump formed of four chambers (2atria and 2
ventricles).
Position:
It lies obliquely in the lower part o the
of
mediastinum of the thorax (one third of the
heart lies to the right of the midline, while 2/3
lies to the left).
Shape:
The heart is pyramidal in shape. So, it has an
apex, base and surfaces which are:
sternocostal, diaphragmatic, right and left
surfaces.
The apex:
It is formed of the left ventricle only.
It is directed downwards, forwards and to the
left.
It lies opposite a point in the left 5th intercostal
space 9cm away from the midline.
The Base:
It is formed by the 2 atria (mainly the left
atrium).
It is directed upwards, backwards and to the
right.
It lies opposite the middle 4 thoracic vertebrae
(separated from them by the oesophagus, the
ted
descending aorta, the trachea and bronchi)
, bronchi).
The major blood vessels are connected to the
heart via the base.
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2. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
The sternocostal surface:
It is related to sternum and costal wall. It is formed of the left and right ventricles.
The diaphragmatic surface:
It lies on the diaphragm. It is formed of the 2 ventricles
The right surface:
It is formed by the right atrium It is related to the right lung.
atrium.
The left surface:
It is formed of the left ventricle. It is related to the left lung.
Chambers of the heart and their connections:
The heart is formed of 4 chambers, Rt. & Lt. atria and Rt. & Lt. ventricles. The 2 atria
are demarcated from the 2 ventricles by a groove called the coronary groove, while
the 2 ventricles are separated from each other by the anterior and posterior
interventricular grooves.
There is no direct connection between the right side and the left side of the heart.
side
The right atrium:
It forms the right surface of the heart.
It is separated from the left atrium by the
interatrial septum.
During intrauterine life, this septum shows
an oval foramen to allow passage of blood
from the right atrium directl into the left
directly
atrium (as there is no respiration). This
foramen is closed after birth.
Connections:
The right atrium receives non oxygenated blood from the whole body via:
non-oxygenated
1. Superior vena cava (SVC) which collects venous blood from the upper half of
the body.
2. Inferior vena cava (IVC) which collects venous blood from the lower half of the
body.
3. Coronary sinus that collects venous blood from the heart itself.
The right atrium pumps its blood content to the right ventricle through the right
atrioventricular orifice (which is guarded by the tricuspid valve).
ricular
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3. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
The right ventricle:
It forms most of the costo-diaphragmatic surface of the heart.
It is separated from the left ventricle by the interventricular septum that bulges into
the cavity of the right ventricle.
Connections:
It receives venous blood from the right atrium via the tricuspid valve.
It pumps its blood content, via the pulmonary trunk, to the lungs.
(The pulmonary valve prevents regurgitation of blood from the pulmonary trunk to the
right ventricle).
The left atrium:
It forms most of the base of the heart.
It receives two pulmonary veins from each lung.
It pumps its blood content to the left ventricle via the left atrioventricular orifice
(guarded by the mitral valve).
The left ventricle:
Its wall is thicker than that of the right ventricle.
It receives oxygenated blood from the left atrium via the mitral valve.
It pumps its blood content, via the aorta, to the whole body.
(The aortic valve prevents regurgitation of blood from the aorta to the left ventricle).
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4. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Blood Supply of the Heart:
The heart is supplied with arterial blood by
the right and the left coronary arteries,
which are branches from the ascending
aorta.
A large vein called coronary sinus drains
most of the heart, then it opens into the right
atrium.
Surface Anatomy of the heart:
The heart can be projected to the surface by determining 4 points and connecting
them together by four lines:
First point (A)(The apex of the
heart): it is a point drawn in the
left 5th intercostal space, 9cm
from the midline.
Second point (B): on the 2nd left
costal cartilage, 1.5 cm to the left
of the sternal edge.
Third point (C): on the 3rd right
costal cartilage, 1.5 cm to the
right of the sternal edge.
Fourth point (D): on the 6th right
costal cartilage, 1.5 cm to the
right of the sternal edge.
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5. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Coverings of the heart:
The heart lies within a fibrous tissue envelope called the fibrous pericardium
pericardium.
The fibrous pericardium is continuos with the adventitia of the great vessels
connected to the heart.
A serous sac intervenes between the heart and its
fibrous pericardium to prevent friction. This serous
sac is called serous pericardium It is formed of
pericardium.
two layers and a cavity in between, visceral layer
covering the heart surface and pari
parietal layer lining
the fibrous pericardium. The cavity of the serous
pericardium contains nothing but few drops of fluid
for lubrication.
Structure of the Heart:
The heart is formed of two myocardial muscles, one for the atria and another one for
the ventricles. Both muscles are attached to the corresponding side of the fibrous
ricles.
rings surrounding the atrioventricular orifices. The atrial and ventricular muscles are
completely separated from each other except for at the atrioventricular bundle, which
represents the only communication between both muscles.
nts
The heart cavity is lined with endothelial layer.
The conducting system: this is formed of some specialized cardiac muscle fibers,
which are able to initialize and conduct cardiac impulses. It comprises the following
structures:
Sino-atrial node (pacemaker of the heart) in the right atrium close to the opening of
the SVC
Atrioventricular node: in the lower part of the interatrial septum.
The atrioventricular bundle: It represents the only possible communicat
bundle: communication
between the atrial and ventricular muscles. It is divided into to two (Rt. &Lt.)
branches for the Rt. and Lt. Ventricles.
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6. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
B. The Blood Vessels
The blood vessels are of three types: arteries, veins, and capillaries.
1. The arteries: They convey blood from the heart and distribute it to the body tissues.
The smallest arteries (less than 0.1 mm in diameter, are called arterioles.
The wall of an artery is formed of three layers;
a) Tunica intema: it is formed of simple squamous endothelium.
b) Tunica Media: It is formed of smooth muscle fibers and elastic fibers. Medium
sized and small sized arteries contain more smooth muscles fibers than elastic
fibers. On the other hand, Large sized arteries contain more elastic fibers than
muscle fibers.
c) Tunica adventitia: it is formed of fibrous connective tissue.
2. The veins: They convey blood back to the heart. The smallest veins are called
venules. The wall of the vien is formed of the same layers as the artery but it is
comparatively thin and very poor in muscle and elastic fibers.
Veins may be deep or superficial. Medium-sized deep arteries are usually
accompanied by two
veins, one on each side,
called venae comitantes.
The superficial veins lie
under the skin, they
clinically important as they
are used for intravenous
injections.
3. The capillaries: they are
microscopic vessels
arranged in a network-form
connecting the arterioles to
the venules. The wall of the
blood capillary is formed of
a single layer of squamous
cells on a basement membrane.
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7. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Major arteries of the body
The Aorta: it is the largest artery in the body. It conveys blood from the left ventricle of
the heart to the whole body. It has three distinct parts: Ascending aor
aorta, it gives
left and right coronary arteries to the heart.
Arch of the aorta, it giv three main arteries: brachiocephalic left common
, gives brachiocephalic,
carotid & left subclavian arteries to the head, neck and upper limbs.
Descending aorta, the part of the descending aorta
,
that lies above the diaphragm is called thoracic
aorta. The part below the diaphra
. diaphragm is the
abdominal aorta. The abominal aorta ends by
.
dividing into right and left common iliac arteries.
The Common iliac arteries: Each one divides into Internal
iliac artery (for the pelvis) and external iliac arteries
(for the lower limbs).
Arteries of the upper limb: The subclavian artery when
passing the axilla is called axillary artery. It
continues its course in the upper arm as the brachial
artery, which is a superficial artery. The brachial
artery divides into radial and ulnar arteries in the
forearm (they are superficial in the lower part of the forearm.
arm
Arteries of the lower limb: The external iliac artery
continues on the front aspect of the thigh as the
femoral artery, then the artery passes behind the
Knee joint as the popliteal artey The poplitea
artey.
artery divides in the back of the leg into anterior
and posterior tibial arteries.
Arterial pulse
Arterial pulse can be palpated at the superficial arteries
especially those related to bones, e.g. the radial
artery at the lower end of the radius, the common
carotid artery in the neck and the femoral artery at
the upper part of the front of the thigh.
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8. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
The major deep veins
The Superior vena Cava (SVC): it drains the upper part of the body. It is formed by the
union of the the right and left brachiocephalic veins
The right and left brachio cephalic veins: Each of which is formed by the union of the
corresponding internal jugular and subclavian vein.
The inferior vena cava (IVC): It drains the lower part of the body. It is formed in the
abdomen by the union of the right and left common iliac veins.
Superficial veins of clinical importance:
External Jugular Vein: it lies in the neck extending obliquely backwards from the angle
of the mandible to the middle of the clavicle. It is used as a monitor for the heart
function. Also, it can be used for intravenous injections.
Cephalic vein of the upper limb: It lies constantly under the skin immediately behind
the styloid process of the radius.
Median cubital vein: it lies obliquely in the cubital fossa (in front of the elbow joint).
The great saphenous vein of the lower limb: It has a constant position in front of the
medial malleolus. It is liable to be varicose (elongated and tortuous).
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9. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Major Arteries
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10. Dr. Kamal Motawei HIMT Introduction to Anatomy (ANAT 215)
Major Veins
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