In seven patients with spastic hemiparesis and in three normal subjects, latencies of the brachioradialis reflex and forearm flexor responses to blows at the styloid process of the radius were identical. Moreover, these latencies were similar to those of independently obtained finger flexor reflexes. H reflexes, obtained only in hemiplegic arms, were of similar latency from brachioradialis and forearm flexor muscles following stimulation of the appropriate nerves. These findings indicate that the brachioradialis reflex and associated contraction of forearm flexor muscles result from independent myotatic reflexes and not from intraspinal spread.
Teasdall RD, Magladery JW. Brachioradialis Reflex and Contraction of Forearm FlexorsAn Electromyographic Study. Arch Neurol. 1974;30(1):94–95. doi:10.1001/archneur.1974.00490310096015