Anatomical variations of the cutaneous innervation patterns of the sural nerve on the dorsum of the foot.

The present study attempts to determine the cutaneous pattern of distribution of the sural nerve on the dorsum of the foot to note the predominant pattern present and whether there was any association between the innervation pattern and sex or side. A total of 260 Indian feet (78 adult feet: 60 male, 18 female; 52 fetal feet: 20 male, 32 female) were dissected. The results showed six patterns of innervation of the toes by the sural nerve. In Type I, the lateral side of the little toe was supplied by the sural nerve alone and the adjacent sides of the 2nd, 3rd, 4th, and 5th toes by the superficial peroneal nerve alone (35.38%). In Type II the lateral side of the little toe was supplied by the sural nerve alone and the adjacent sides of the 4th and 5th toes by the sural nerve along with the superficial peroneal nerve (10%). In Type III the lateral side of the little toe was supplied by the sural nerve alone and the adjacent sides of the 3rd, 4th, and 5th toes by the sural nerve along with the superficial peroneal nerve (21.15%). In Type IV the lateral 1(1/2) toes were supplied by the sural nerve alone and the adjacent sides of the 3rd and 4th toes by the superficial peroneal nerve alone (3.85%). In Type V the lateral 1(1/2) toes were supplied by the sural nerve alone and the adjacent sides of the 3rd and 4th toes were supplied by the sural nerve along with the superficial peroneal nerve (5%). In Type VI the lateral 2(1/2) toes were supplied by the sural nerve alone (24.61%). The predominant patterns were Type I (35.38%), Type VI (24.61%), and Type III (21.15%). There was no association between the innervation pattern of the sural nerve and sex or side. The pattern, which is usually described, was found in only 35.38% of feet. Considering the variation in the pattern of cutaneous distribution of the sural nerve in Indian feet, the function of the sural nerve may be to supply a wider area of skin than is usually described.