Anatomy of Heart

DEVELOPMENT OF HEART:
Embryonic Structure Adult Structure
Truncus Arteriosus Aorta ,Pulmonary trunk
Aortic sac, Left 4th Aortic Arch, left dorsal aorta Arch of Aorta
Left dorsal Aorta and fused dorsal Aorta Descending Aorta
Primitive ventricle Trabeculated part of Rt. & Lt. ventricle
Primitive atrium Trabeculated part of Rt. & Lt. atrium
Sinus venosus Smooth part of Rt. atrium(sinus venerum),coronary sinus, oblique V of Lt. atrium
  • Septum Primum: fossa ovalis
  • Septum Secundum: annulus ovalis
  • Septum Spurium: derived from fusion of right & left venous valves.
  • The heart tube bends & forms the cardiac loop by day 28.
Embryonic Structure Adult Structure
Remnant of first aortic arch Maxillary. A, may form Ext Carotid.A
Remnant of 2nd aortic arch Hyoid Et stapedial arteries
Right Horn of Aortic sac Brachiocephalic.A
Right 4th Arch artery & 7th Cervical
Intersegmental.A, right dorsal aorta
Right Subclavian.A
Left 7th Cervical IntersegmentaLA Left Subclavian
Proximal Part of 3rd Arch Artery Common Carotid. A
Distal Part of 3rd Arch Artery and
Cervical part of dorsal aorta
Internal carotid artery
Bud from 3rd Arch Artery External Carotid artery
Part of 6th arch(pulmonary arch) artery Pulmonary Artery
Part of left 6th arch artery between lungbud and aorta Ductus arteriosus
BORDERS & SURFACES OF HEART
  • Heart in anatomic position rests on diaphragmatic surface, consists of LV + small portion of RV.
  • Rt. Border is formed by RA + SVC, IVC ;
  • Lt. border: LV (mostly) + Lt auricle + Aortic knuckle+Pulmonary artery, obtuse border
  • Inf. Border: by RV + some part of LV
  • Apex: by LV (3.5"Lt. to 5th I.C.S.)
  • Base (post surface): LAURA (LA Receiving 4 pulmonary veins)
  • Anterior surface of heart (Sterna costal surface): RV mainly, Partly LV and left auricle.
  • The diaphragmatic surface of the heart :is formed mainly by the right and left ventricles. The inferior surface of the right atrium, into which the inferior vena cava opens, also forms part of this surface.
LOCATION & SHAPE
  • The human heart is situated in the middle mediastinum, at the level of thoracic vertebrae T5-T8.
  • Normal Axis of the heart is best described as being between – 30 to +90
  • A double-membraned sac called the pericardium surrounds the heart and attaches to the mediastinum.
  • The back surface of the heart lies near the vertebral column, and the front surface sits behind to the sternum and rib cartilages.
  • The upper part of the heart is the attachment point for several large blood vessels – the venae cavae, aorta and pulmonary trunk.
  • The upper part of the heart is located at the level of the third costal cartilage.
  • The lower tip of the heart, the apex, lies to the left of the sternum (8 to 9 cm from the midsternal line) between the junction of the fourth and fifth ribs near their articulation with the costal cartilages.
  • The largest part of the heart is usually slightly offset to the left side of the chest (though occasionally it may be offset to the right) and is felt to be on the left because the left heart is stronger and larger, since it pumps to all body parts.
  • Because the heart is between the lungs, the left lung is smaller than the right lung and has a cardiac notch in its border to accommodate the heart.
  • The heart is cone-shaped, with its base positioned upwards and tapering down to the apex.
  • An adult heart has a mass of 250–350 grams (9–12 oz).
  • The heart is typically the size of a fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness.
  • Right side of mediastinal shadow is formed by SVC/ Right brachiocephalic vessels,IVC and Right atrium
  • Right atrium,Superior vena cava,Inferior vena cava are seen on the right side of the cardiac silhouette in chest X-ray
Exam Question
  • Right border of the heart is formed by Right atria + Sup. Vena Cava & Inferior Vena Cava
  • Normal Axis of the heart is best described as being between – 30 to +90
  • In the adult heart, floor of fossa ovalis represents Septum Primum
  • Ascending aorta & Pulmonary trunk & heart lies in middle mediastinum
  • Base of the heart is formed mainly by Left atria & 4 pulmonary veins opening into it
  • Right side of mediastinal shadow is formed by SVC/ Right brachiocephalic vessels,IVC and Right atrium
  • Right atrium,Superior vena cava,Inferior vena cava are seen on the right side of the cardiac silhouette in chest X-ray
  • Lt. border: LV (mostly) + Lt auricle + Aortic knuckle+Pulmonary artery, obtuse border
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