A separate supernumerary muscle in the lateral cubital fossa
originating from the humerus or brachioradialis and
inserting into the radius, pronator teres or supinator muscle
has been considered as a variation of the brachioradialis
muscle (Dawson, 1822; Meckel, 1823; Lauth, 1830;
Halbertsma, 1864; Gruber, 1868b; Testut, 1884; LeDouble,
1897; Spinner & Spinner, 1996). However, a similar
description was used to report additional heads of the
brachialis or biceps brachii muscles (Gruber, 1848; Wood,
1864, 1868; Macalister, 1864–66, 1966–69, 1875; Gruber,
1868a; Wolff-Heidegger, 1937).
The innervation of these variant muscles would be a good
tool to assign each variation to its associated muscle.
Consequently, innervation by the radial nerve would
indicate that it is a derivative of the humero–radialis group
of muscles, while innervation by the musculocutaneous
nerve would support it as a derivative of the anterior
musculature of the arm (Rolleston, 1887; Lewis, 1989).
However, no references to the innervation were found in the
Therefore this study set out to establish the phylogenetic
origin of the brachioradialis accessorius muscle and, with
the help of its innervation, to determine its incidence and
unreported detailed morphology.