Gross anatomic evidence of partitioning in the human fibularis longus and brevis muscles

Abstract

Evidence from a variety of studies suggests that many mammalian muscles are partitioned with respect to their architecture and innervation. Each of these specific muscle subvolumes is innervated by an individual muscle nerve branch, contains motor unit territories with a unique array of physiological attributes and has been known as a neuromuscular compartment or segment. This gross anatomic study investigated for evidence of neuromuscular segmentation in human fibularis (peroneus) longus and brevis muscles. Forty-three legs (24 left, 19 right) from embalmed adult cadavers were dissected. Any architectural segment within these muscles were identified. The specific innervation patterns of these muscles were also described. The fibularis longus muscle was consistently found to have connective tissue partitions that separated it into four parts: anterior superficial, anterior deep, posterior superficial, and posterior deep. The innervation pattern of this muscle was consistent with the segments defined by the connective tissue partitions. There were consistently four primary motor branches, each supplying a specific portion of the fibularis longus muscle. While a typical branching pattern was recognized, there was some variability as to the order of these branches as they originated. The fibularis brevis muscle was consistently found to have a central connective tissue partition that separated it into two portions: anterior and posterior. In 91% of the fibularis brevis muscles, there were two primary motor branches, one for each of the two segments of the muscle. In the other 9%, only one primary motor branch supplying the muscle could be identified.

Fascicular analysis at perineurial level of the branching pattern of the human common peroneal nerve

“…Usual textbooks describe the PS as supplying the lateral muscles of the leg, and the PP the anterior muscles (Woodburne & Burkel, 1988;Berry et al, 1995;Moore & Dalley, 1999). However, most researchers indicate that the RPL arises from the PC and PP in addition to the PS (Sunderland & Hughes, 1946;O'Rahilly, 1986;Bakkum et al, 1996;Rosse & Gaddum-Rosse, 1997; the present study). Furthermore a muscular branch to extensor muscles may arise from the CDM bundle (Reimann, 1984; the present study).…”

“…The CDM bundle may arise from the PP bundle or at the division of the PC bundle (Reimann, 1984; the present study). The CD bundle was also reported to arise directly from the PC trunks (Bakkum et al ., 1996). The PC trunk may bifurcate into terminal branches proximal to the fibular head (Deutsch et al ., 1999).…”

“…In previous studies the number of the RPL was counted in connection with the architecture of the muscle. Frohse and Fränkel (1913) described three sets of nerve branches and muscular segments, while Bakkum et al (1996) suggested four sets. The result of the present study differs from these studies, but it is obtained only from observations of the RPL fascicles.…”

Differences in End-Point Force Trajectories Elicited by Electrical Stimulation of Individual Human Calf Muscles

“…There is evidence that FIB innervation is variable (Barrett et al, 2006) which could mean we were more or less likely to stimulate particular nerve branches in subjects. This fact considered with the possibility of compartmentalization (Bakkum et al, 1996) could mean that we stimulated different compartments to a different degree in different subjects therefore causing variability in the magnitude of the force trajectory.…”

“…Anatomical differences such as compartmentalization (e.g. LG – Segal et al, 1991; fibularis longus - Bakkum et al, 1996), innervation differences (e.g. fibularis longus - Barrett et al, 2006) and differences in the number of muscles contributing to movements (e.g.…”