part of abdominal segment larval segmental nerve larval abdominal segmental nerve FBbt:00002450 larval abdominal SN Larval segmental 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, anterior and posterior, both formed from neurons of the same segment as the nerve (Campos-Ortega and Hartenstein, 1997). Proximally it shares a glial sheath with the intersegmental nerve before branching from it at the ventral edge of the ventral oblique muscles (Campos-Ortega and Hartenstein, 1997). A thick, posteriorly directed branch (SNc) leaves the main trunk of the nerve (SNa) and splits into fine branches - 3 carrying axons from the ventral sensory cluster and a 4th carrying efferents to the ventral acute musculature (Campos-Ortega and Hartenstein, 1997). The SNa branch continues dorsally and carries efferent axons innervating the external lateral transverse and lateral oblique muscles and the axons of v'es2 and v'ch1 (Campos-Ortega and Hartenstein, 1997). larval segmental nerve of A1-7 VFB:FBbt_00002197 larval abdominal posterior fascicle fly_anatomy.ontology FBbt:00002197 larval abdominal segment A1-7 larval abdominal nerve