Laboratory Syllabus

THE HEART
 

Objectives:
Upon completion of this session, the student will be able to:

1. To gain detailed knowledge of the anatomy of the heart.
2. To relate the antaomy of the heart to its physiology.
3. To understand the anatomical changes of the heart from fetal-life to birth.

Summary of Dissection Procedure
Shearer's Manual of Hunam Dissection - Pericrdium & Heart  p.106-118

1. The pericardium should have been opened previously.
2. Redefine the pericardial cavity and study the great vessels.
3. Direct your attention to the heart and examine the heart in situ.
4. Remove the heart prior to dissecting it (p.112).
5. Study the coronary circirulation (p. 112)
6. Open the chambers of the heart starting with the right atrium (p.110).

Materials to be learned:

1. The Heart: External Anatomy
a. The heart consists of four chambers:
                (1) the right and left ventricles
                (2) the right and left atria

b. Topography
                (1) interatrial and interventricular septa
                               - separates atria and ventricles of the right and left sides of the heart
                (2) coronary sulcus
                               - encircles the heart and separates the atria from the ventricles
c. Blood vessels of the heart - originate from the aortic sinus
              (1) right coronary artery
                       - posterior interventricular artery
                       - right marginal branch
               (2) left coronary artery
                       - anterior interventricular artery
                       - circumflex artery 
What is meant by Right or Left sided dominance?

              (3) coronary sinus - largest vein draining the heart
                       - the great cardiac vein
                       - the small and middle cardiac veins
                       - the posterior vein of the left ventricle
                       - the oblique vein of the left atrium
Review a coronary artery catherization

What is angina pectoris?








2. The Heart: Internal Anatomy
Right atrium
(1) the sinus venarum - a large rectangular cavity with smooth walls for efficient blood flow,
      is between the two venae cavae and is continuous with the right ventricle

(2) atrial portion
      a. auricular appendage, a blind pocket lined with pectinate muscles, projects from the
          sinus venarum to overlap the root of the aorta
      b. crista terminalis, a vertical ridge extending from the superior to the inferior vena cava
          - pectinate muscles project at right angles to this crest 

(3) interatrial septum - divides right from left atria
      a. fossa ovalis - an oval depression in the interatrial septum. This fossa was open as a
          foramen during fetal circulation. This foramen ovale allowed blood to flow from the
          right atrium into the left.

(4) openings into the right atrium
      a. superior vena cava from above
      b. the inferior vena cava from below
      c. coronary sinus
      d. atrioventricular orifice

Right ventricle - most of the sterno costal surface of the heart
(1)  conus arteriosus - the superior portion of the ventricle A funnel shaped infundibulum
      leads into the pulmonary orifice. The walls of the infundibulum are smooth. At the
      pulmonary orifice there is a fibrous ring to which is attached three pulmonary semilunar
      valves (right, left & anterior).
What is pulmonary valvular stenosis?

(2)  trabeculae carneae - muscular projections of the thick inner wall of the ventricle

(3)  papillary muscles connected to the tricuspid valve by slender fibrous threads called
      chordae tendineae

(4)  tricuspid valve (right atrioventricular valve) atrioventricular orifice is guarded by the
      tricuspid valve. The tricuspid valve has three triangular cusps, the bases of which are
      attached to the annulus fibrosis, a fibrous ring at the periphery of the atrioventricular
      orifice.

(5)  interventricular septum - separates the right ventricle from the left ventricle - it is divided
       into a thin upper the membranous part, and a thicker lower muscular part.

                     What is a ventricular septal defect (VSD)?

Left atrium
(1) atrium proper
       a. two pairs pulmonary veins enter into the smooth walled portion of the superior
           posterior surface
(2) auricular appendage - pectinate muscular portion

Left ventricle is similar in structure to the right except that its walls are thicker, and the cavity is longer and narrower
(1) trabeculae carneae - more numerous in the left ventricle

(2) papillary muscles & chordae tendineae

(3) bicuspid (mitral) valve (left atrioventricular valve)
      The bicuspid valve has two triangular cusps, the bases of which are attached to the
      annulus fibrosis.

(4) aortic vestibule - the upper portion of the ventricle which leads into the aortic orifice.
      Its walls are composed of fibrous tissue instead of muscular tissue.

(5) aortic orifice
      a. aortic semilunar valves (right, left & posterior)
      b. aortic sinuses - dilated sacs between the cusps and the wall of the aorta
         - from two of these sinuses the coronary arteries take origin.
What is mitral valve incompetence?              What is meant by a heart murmur?

3. Nerve supply of the heart
        There is an intrinsic and extrinsic control of contraction
(1) The extrinsic system influences the intrinsic system through the autonomic nervous system.
      The sympathetic nerves from the thoracic region of the cord accelerate the heart rate
      and dilate the coronary vessels. The parasympathetic vagus nerve slows the heart rate.
a. superficial cardiac plexus in the concavity of the aortic arch
b. deep plexus is formed at the base of the heart posterior to the aortic arch

(2) The intrinsic system is a specialized conduction system composed of nodal tissue,
      and under physiological conditions cardiac muscle has an inherent rhythmicity.
a. sinoatrial node at the junction of the superior vena cava and right auricle
     near the crista terminalis initiates a beat which is spread over the atria,
     and this node is called the pacemaker.
b. atrioventricular node, in the interatrial septum above the opening of the
    coronary sinus. The impulse from here is then directed toward the ventricles
    by the atrioventricular bundle passing from the atrioventricular node to the
    inter-ventricular septum where it divides into right and left bundle branches.

List of Items to Identify