Anomalous muscles in the first flexor compartment of the
forearm are quite common. Flexor digitorum superficialis
(FDS) is a well known example (Kernohan et al. 1984;
Ametewee et al. 1985; Elias et al. 1985; Tonkin & Lister,
1985). However, the anatomical variations of muscles, for
example flexor digitorum profundus (FDP) in the second
flexor compartment, are not rare (Hollinshead, 1969;
Williams & Warwick, 1980; Honing et al. 1995; Williams et
al. 1995). These muscles are usually asymptomatic and
discovered incidentally during anatomical dissection or at
operation. However, they may be symptomatic, presenting
as an enlarging tumour-like mass simulating a ganglion
(Vichare, 1970; Hayes, 1974; Murakami & Todani, 1982) or
may cause a compression neuropathy (Hutton & Kernohan,
1981; Simodynes & Cochran, 1981).