The anatomy of the muscle wall of the human colon : the inter-taenial continuity of the longitudinal muscle coat

Abstract

This report is, in modified form, part of the thesis presented by Dr. Pace for his Ph.D. The work reported was done whilst he was a Commonwealth Scholar in the Department of Anatomy at the Middlesex Medical School, London. Contradictions exist in the literature as to whether the outer muscle coat of the human colon is complete or not. There are conflicting points of view as to the presence and extent of the longitudinal muscle in between the taeniae. The material used consisted of 112 human colons, mainly postmortem, from subjects ranging in age from early fetal to 88 years. Portions from the named regions of the colon fixed in various states of distension were examined. The methods of microdissection were combined with those of histology. Sections, transverse of the whole circumference and longitudinal of the intertaenial wall, were studied. It was found that in the human colon the outer longitudinal coat, though thin in between the toenia, forms a complete and continuous layer. This is so at all ages, in all regions of the colon and in all states of distension except maximal when the muscle fascicles become separated by gaps filled in with connective tissue. Under no circumstances was the outer coat found to consist only of a few scattered longitudinal fibres and isolated bits of muscle, or to be entirely absent.