Feathered Fibres of Human Soleus Muscle

Abstract

The large size of superficial group of muscles of back of leg is a characteristic feature of the musculature of man being related directly to its erect posture and mode of progression. Triceps surae is one of the powerful muscles of the body after Gluteus maximus and Quadriceps femoris. To make the muscle more powerful nature has devised a unique method of packing the fibers in a small space by pennation. There exists a bipenniform mass as a peculiarly human feature. Its feathered fasciculi arise from the deep (anterior) surface of the soleus muscle. Most of the textbooks of Anatomy and the available literature on the triceps surae or the tendoachillis do not appreciate and describe this fascinating aspect of the muscle. It was Schafer et al. (1923) who gave a detailed account of this muscle. Standring et al. (2005) have also described this muscle in great detail. We have studied the unique features of this part of soleus muscle. Bipennate arrangement was seen in 86% (right-83%; left-89%); and its maximum width was found to be 3.63 cm (Rt-3.71cm; Lt-3.55cm). Median tendinous septum was directed backwards and medially. Thus this muscle will further increase the power of contraction of soleus, which is so very important for a bipedal gait.