Morphological variations and accessory ossicles in the peroneal and tibialis muscles / 대한해부학회지

This study describes five bilateral anatomical variations in the feet of a 97-year-old male cadaver. Following routine dissection, all variants were measured and documented. Three accessory tendons and two accessory ossicles were identified. Bilateral accessory tendons were present from the tibialis anterior (type II), peroneus tertius (type III), and peroneus brevis muscles. Accessory tendon length was 36–104 mm and width was 1–3 mm each inserting more distally then the main tendon. Accessory ossicles were identified as an accessory navicular and os peroneum, respectively. Individually, each variation has varying prevalence rates in the literature, but to date, no known studies have been published describing the combined presence of all five bilateral variations. The acknowledgement of multi-variant cases such as this one may be helpful in the clinical setting, particularly for patients with pathology or for those undergoing foot and ankle surgery.

BILATERAL VARIATIONS IN TENDONS OF DORSUM OF FOOT.

Anterior or extensor muscles of foot comprises Peroneus tertius (PT), Extensor digitorum longus (EDL), Extensor hallucis longus (EHL) and Tibialis anterior (TA). Presence of PT in many of the primates and humans suggests terrestrial bipedalism. PT is a dorsi-flexor of ankle joint and a weak evertor of foot. TA is the most medial and superficial dorsiflexor. Standard text-books describe the course of tendon of TA as passing deep to inferior extensor retinaculum (IER). In the present study, absence of PT with a course of TA superficial to IER on one side with variant origin of PT from Extensor digitorum longus on the other side were observed in an adult female cadaver. Knowledge on variations in PT and TA are of clinical significance and academic importance to orthopedic surgeons, radiologists and anatomists.

The presence of the peroneus tertius muscle in Thai people.

The peroneus tertius is a small partially separated portion of the extensor digitorum longus, as its fifth tendon, but has an important role in locomotion and in the evolution of human beings. It supports and stabilizes the longitudinal arches of the foot while standing and locomotion during bipedalism. In particular, it assists in everting the foot, which is a characteristically human movement. This study was performed by dissecting 247 legs from 144 cadavers. In these cadavers, we found a high percentage of the presence of this muscle, the peroneus tertius, (95.55%). The absence of the muscle was rare, only in 4.45%. Regarding the muscle size, which was calibrated at the ankle joint and compared with the common tendon of the extensor digitorum longus at the same area, the proportion was very large a t34.77% in the right leg and 39.55% in the left leg. The results of this study emphasized and clarified the important role of this muscle.