23B02: Exam Report

Outline the anatomy of the cardiac ventricles including the chambers, valves and conduction elements

11% of candidates passed this question.

This question expected an outline of the anatomy of the cardiac ventricles. Candidates that broke down the anatomy into subsections with correct and clear descriptions of each component were most successful. A potential structure to approach this question is included below;

  • Position, orientation, relations and characteristics of the chambers including ventricular interdepence
  • Internal ventricular structures including muscle type, septum, trabeculae, papillary muscules, infundibulum and moderator band
  • Valves and valvular rings’ position, structure and attachments
  • Conduction elements position and divisions
  • Blood and nerve supply

G1i / 23B02: Outline the anatomy of the cardiac ventricles including the chambers, valves and conduction elements

Tips

  • The heart is a mediastinal structure obliquely positioned
  • Sits in Pericardial Sac

Position

Left Ventricle

Right ventricle

Left Ventricle

Left and posterior

Right ventricle

Right and anterior

Orientation

  • Anatomical base points posterolaterally to right
  • Apex directed anteroinferiorly to the left

Relations

Left Ventricle

Right ventricle

Left Ventricle

Right ventricle

RV anterior to LV and anteroinferior to RA

Characteristics of Chambers

Left Ventricle

Right ventricle

Left Ventricle

  • Conical in shape, more elongated than right ventricle

Right ventricle

  • Irregular, triangular (when viewed laterally)
  • 1/3 thickness of LV

Internal ventricular structures

  • Atrioventricular septa: fibroelastic structure that separates atria from ventricles
  • Interventricular septum: thick muscular wall attached to atrioventricular rings
    • Muscular part: separates left and right ventricles
    • Membranous part: separates RV from subaortic area
  • Chordae tendineae: strong, fibrous connections between valve leaflets and papillary muscles
  • Trabeculae: irregular muscular columns projecting from inner ventricular surface

Interventricular Interdependence

  • Because it is contained within Pericardial Sac, this promotes Ventricular Interdependence in pathological conditions
  • R+L ventricles share myocardial fibres that directly surround both ventricles
  • Elevation of pericardial pressure causes one ventricle to compress onto the other
  • Systolic alteration of one ventricle will affect the performance of the other as a volume increase in one ventricle results in volume decrease of the other ventricle

Left Ventricle

Right ventricle

Left Ventricle

  • Fibrous subaortic curtain – separates mitral valve from aortic valve
  • 2 Papillary muscles (larger than RV)
    • Anterior
    • Posterior
  • Mitral valve: 2 cusps, fibrous ring formed by anterior and posterior fila coronaria
  • Aortic valve: 3 cusps, no specific fibrous ring

Right ventricle

  • Supraventricular crest: thick muscular band separating RV inlet and outlet, directs blood flow – prevents it from going directly to outflow tract
  • 3 Papillary muscles: anterior, posterior, septal
  • Septomarginal band (moderator band): condensation of trabeculae, conduit for part of right AV bundle tract
  • Infundibulum: funnel-like sleeve of RV muscle forming RV outflow tract, forms fibrous ring for pulmonary valve
  • Tricuspid valve: 3 cusps, fibrous ring that attaches to cardiac fibrous skeleton
  • Pulmonary valve: 3 cusps, fibrous ring at the top of the infundibulum attaches to the crescent-shaped arches of the cardiac skeleton at the root of the pulmonary artery

Conduction Elements

  • The conducting system is the only connection between the two muscular systems
  • SA Node
  • AV Node
  • Bundle of His
  • Right bundle branch – conducts impulse of Purkinje fibers of RV
  • Left bundle branch – conducts impulse of Purkinje fibers of LV
  • Purkinje fibers – located in subendocardial surface of ventricular walls

Blood Supply

Left Ventricle

Right ventricle

Left Ventricle

  • LAD and circumflex

Right ventricle

  • RCA and circumflex

Venous Drainage

Coronary sinus

Nerve Supply

Innervated by cardiac plexus

  • Superficial part: left vagus + left cervical sympathetic ganglion
  • Deep: left and right vagus, recurrent laryngeal nerve, sympathetic fibres from cervical and thoracic sympathetic ganglia

Author: Novia Tan