part of abdominal segment larval intersegmental nerve larval abdominal intersegmental nerve Larval intersegmental nerve of a larval abdominal segment. These are only found in segments A1-7, as A8 and A9 do not have separate segmental and intersegmental nerves (Campos-Ortega and Hartenstein, 1997). It has two roots; an anterior root that is formed by neurons of the anteriorly adjacent neuromere, and a posterior root, that is formed by neurons of the same neuromere as the nerve (Campos-Ortega and Hartenstein, 1997). These roots converge and fuse shortly before leaving the ventral nerve cord (Campos-Ortega and Hartenstein, 1997). Proximally it shares a glial sheath with the segmental nerve before branching from it at the ventral edge of the ventral oblique muscles (Campos-Ortega and Hartenstein, 1997). It then runs dorsally, anterior to the segmental nerve (Campos-Ortega and Hartenstein, 1997). It has two ventral motor branches, ISNb and ISNd, which innervate the ventral lateral and ventral oblique muscles, respectively, and a lateral sensory branch that penetrates the lateral transverse muscle fibers to reach the lateral sensory cluster (Campos-Ortega and Hartenstein, 1997). Further dorsally, upon entering the dorsal muscle group, it splits to form an externally directed sensory branch connected to the dorsal sensory cluster, and an internally directed branch which carries efferent axons to the dorsal musculature (Campos-Ortega and Hartenstein, 1997). fly_anatomy.ontology larval intersegmental nerve of A1-7 FBbt:00002319 VFB:FBbt_00002319 larval abdominal anterior fascicle larval abdominal ISN larval abdominal segment A1-7 larval abdominal nerve