Peroneus Quartus

Fig. 16.24. Peroneus quartus. Short-axis 12-5 MHz US image obtained over the retromalleolar groove demonstrates the peroneus longus (pi) and peroneus brevis (pb) tendons together with an additional element, the peroneus quartus, consisting of a discrete tendon (pq) surrounded by a hypoechoic muscle (asterisks). The peroneus quartus typically lies posteromedial to the peroneals. The increased volume of resident soft-tissue structures in the retromalleolar area may stress the superior peroneal retinaculum (arrowheads) that, in this particular case, appears bulging, thickened and hypoechoic. LM, lateral malleolus. The photograph at the upper left of the figure indicates probe positioning...

Soft-tissue masses in the ankle are uncommon (OzDEMiR et al. 1997). They may he asymptomatic or may cause disturbances, such as pain, weakness, swelling, joint impairment or tarsal tunnel syndrome. With US, the diagnosis of a solid or complex mass versus a cystic mass can reliably be performed in the soft tissue of the ankle. The US characteristics of many masses that arise around the ankle joint are reported in the General Section of this book. However, the specific features of some of them, including ganglia, neurogenic tumors and abscesses, warrant additional brief discussion here. Accessory muscles (peroneus quartus, flexor digitorumlongus accessorius, accessory soleus) have already been described in previous sections of this chapter. 

Chepuri NB, Jacobson JA, Fessell DP et al (2001) Sonographic appearance of the peroneus quartus muscle correlation with MR imaging appearance in seven patients. Radiology 218 415-419... 

Schweitzer ME, Karasick D (2000) MR imaging of disorders of the Achilles tendon. AJR Am J Roentgenol 175 613-625 Sella EJ, Caminear DS, McLarney EA (1998) Haglund s syndrome. J Foot Ankle Surg 37 110-114 Sobel M, Levy ME, Bohne WH (1990) Congenital variations of the peroneus quartus muscle an anatomic study. Foot Ankle 11 81-88... 

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