sheet no.28

♦ Heart has 3 borders and 3 surfaces.

**Borders :-

Right border:- form by right Atriumàrelated to right lung

Inferior border:- form mainly by right ventricle-->related to diaphragm

Left border:- form by left ventricleàrelated to left lung

* Apex of the heart is mainly form by left ventricle which is located in the 5th intercostal space about 9 cm from the sternum ---> This is the site of maximum Heart sound you hear.

4Surfaces :-

Sternocostal surface ((Anterior surface)) :-

- form by right ventricle .

- which is the easiest access for the heart to give intracardiac Injection(i.e:adrenaline)

-mainly one involved in CPR

Diaphragmatic surface ((Inferior surface)) :-

- Form by both ventricles – right and left - .

-Where the heart is resting on diaphragm precisely on central tendon of diaphragm.

3- Base ((posterior surface)) :-

- form by left atrium which is located anterior to esophagus .
- if a person swallow large bolus of food it may compress anterior on the base of heart.

.
- receives venous deoxygenated blood from all over the body through the

following veins :

Vein's name Convey blood from??

Superior vena cava Upper ½ of the body above diaphragm

Inferior vena cava Lower ½ of the body below diaphragm

Coronary sinus (coronary vein) Convey blood from the heart structure it self.

**The changing of the heart's direction

Before birth

-Heart was directed anterior with left side and right side

-Apex anterior and base posterior

After that

It turned 90° to the left converting :-
1)) Right surface to be anterior surface
2)) Left surface to be Base( posterior surface)
** So in adults' heart The right side of heart -->anterior surface.
The left side --->posterior surface.

Walls of the right atrium
1)) Anterior wall ---> rough wall.
2)) posterior wall ---> smooth wall / it forms by interatrial septum

** Anterior wall from inside
-Rough wall .
- Like a comb ::
* Its handle is called (crista terminalis) where its superior end is pin
pointing the SA node-Sinoatrial node- ((pacemaker of the heart))
* The teeth of the comb are called ( pectinate muscle or musculi pectinati ).

** smooth posterior wall consist firstly of fossa ovalis , i.e. remnants of foramen ovaliàshuttle blood from R.A to L.A to bipass the lungs.

FINALLY, I want to dedicate this sheet to all my friends specially:-
Bayan AL-khdor ,Doa' Abu jamea , Rasha jabra , Rawan Ghazal , Doa' Jarah , Israa AL-zawawi Dina Ammari , Dina Break, Ashar AL-Tarawneh , Samar Taqatqa, Muna , Samar Al- Rahmeh, Dania Dahmash, Sahar basel,Sawsan tabaza, Aseel, Nesreen , Shereen & Roaa , Amal , Heba nemer , Nadia , Doaa al-Ibraheem, Abeer , Asma'

And to every one whom I don't mention.

Special thanks to Dr . Maher AL-Hadidi