![]() ![]() In contrast, the extensive overlap and comparatively condensed organization of arm representation at inferior capsular levels suggest that lesions seated inferiorly are likely to correlate with poorer levels of recovery of upper limb movement. Our data suggest that CR and superior capsular lesions may correlate with more favourable levels of functional recovery due to the widespread nature of arm representation. M2, LPMCd and LPMCv fibres overlapped extensively, as did fibres from M4 and M1. Within the ICp, the projections from M3, M2, LPMCv, LPMCd, M4 and M1 maintained their anterior to posterior orientation, respectively. As each fibre system progressed inferiorly within the IC, all fibres shifted posteriorly to occupy the ICp. ![]() Fibres from M1 also travelled in the ICp, positioned immediately posterior to the M4 projection. The projection from M4 descended through the mid‐portion of the ICp. ![]() The projection from LPMCd occupied the anterior portion of the ICp. The projection from LPMCv travelled through the genu and anterior portion of the posterior limb (ICp). The projection from M2 passed through the posterior portion of the ICa and the genu (ICg). At superior levels of the IC, the corticofugal projection from the arm representation of M3 coursed through the middle and posterior portion of the anterior limb (ICa). In the IC, the individual corticofugal pathways were found to be widespread, topographically organized and partially overlapping. In the CR, each pathway was segregated as medial motor area fibres arched over the caudate and lateral motor area fibres arched over the putamen. They included the arm representation of the primary (M1), ventral lateral pre‐ (LPMCv), dorsolateral pre‐ (LPMCd), supplementary (M2), rostral cingulate (M3) and caudal cingulate (M4) motor cortices. To advance our understanding of the organization of the corticofugal projection in this critical brain region, we studied the trajectories of the projection arising from six different cortical arm representations in rhesus monkeys. Localization of the corticofugal projection in the corona radiata (CR) and internal capsule (IC) can assist in evaluating a patient’s residual motor capacity following subtotal brain damage and predicting their potential for functional restitution. ![]()
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