Accessory obturator nerve (AON)

The accessory obturator nerve is a relatively rare anatomical variant present in approximately 10–30% of individuals. It typically arises from the lumbar plexus, most often from the ventral rami of the L3 and L4 spinal nerves, and descends along the medial border of the psoas major muscle, crossing the superior pubic ramus beneath the pectineus muscle. Its primary role is to provide motor innervation to the pectineus muscle (sometimes to other adductor muscles), and sensory innervation to the hip joint and, variably, to the skin over the medial thigh. The presence and course of the accessory obturator nerve are highly variable, which can affect clinical outcomes during regional nerve blocks or pelvic/hip surgeries. It is not considered a druggable therapeutic target, receptor, enzyme, or related molecular entity; rather, it is a named anatomical structure of clinical importance during nerve blocks and surgical interventions.

Other names

Accessory obturator