We have studied in vitro preparations of canine right and left papillary muscles to determine the excitation sequences of the Purkinje and ventricular cells, using both monopolar surface electrodes and intracellular microelectrodes. Our results show, for right papillary muscles, that the Purkinje layer covers the basal part of the muscle, and that activation from the right bundle branch propaga...

PURPOSE To clarify whether structural peculiarities formerly described in extraocular muscle (EOM) spindles of aged persons are already present in EOM spindles of a 2-year-old infant. METHODS Distal halves of two EOMs obtained from a 2-year-old multiorgan donor were immersion-fixed and prepared for electron microscopy. The fine structure of 10 muscle spindles and of 1 "false spindle" was inve...

A naval cook. aged twenty. complained of diffuse pain in the left hand after heavy use. with a swelling on the back of the hand. He had first noticed this swelling three years before. and said that it had appeared spontaneously. A course of short-wave diathermy had failed to relieve his symptoms. Examination showed an elongated tumour on the dorsum of the hand, which appeared to arise from the ...

Valvular heart disease remains a major problem worldwide and is responsible for 20 000 deaths each year in the United States, with an estimated 99 000 inpatient valve procedures performed annually.1 The mitral and tricuspid valve complexes comprise the valve leaflets, valvular annulus, papillary muscles, and chordae tendineae, which anchor the leaflets to the papillary muscles. As papillary mus...