The longitudinal muscle (LM) represents a strong muscular structure of
the anal canal situated between the internal (IAS) and the external a
nal sphincter (EAS). Terminal fibres of this muscle insert at the subm
ucosa of the anal canal, representing the m. canalis ani. Others cross
the subcutaneous part of the EAS to become the m. corrugator ani. Thu
s, the LM connects the visceral and somatic parts of the anal sphincte
r complex. Histologically ganglionic cells and as Vater-Pacinian corpu
scles can be identified inside the LM. Morphology, topography and hist
ology of the LM suggest that this muscle participates in maintaining a
norectal continence. It is mandatory that the exact functions of this
muscular structure be to elaborated upon, if we are to understand the
mechanism of anorectal continence.