Origin and distribution of the sciatic nerve in pig fetuses (Sus scrofa domesticus – Linnaeus, 1758) from the lineage Pen Ar Lan

The origin and distribution of the sciatic nerve was studied in 31 pig fetuses from the lineage Pen Ar Lan, being 22 males and 9 females, after being fixed in a 10% formaldehyde aqueous solution. In these animals, the lumbar vertebrae ranged from 5 to 7, with a predominance of 6, something which contributed to variations in the origin of this nerve. The sciatic nerve originated in 80.64% of the antimeres from the ventral branch of the fifth lumbar spinal nerve (L5); in 96.77 % of L6; in 6.45% of L7; in 100% of S1; and in 64.51% of S2. The composition of this nerve took place in 45.16% of the animals due to the union of L5, L6, S1 and S2; in 32.25% of L5, L6 and S1; in 12.90% of L6, S1 and S2; in 6.45% of L6, L7 and S1; and in 3.22% L5, S1 and S2. There was symmetry in the origin of the sciatic nerve in all specimens under study. This nerve sent branches to the superficial gluteal, semitendinosus, semimembranosus and biceps femoris muscles in all specimens, and, in a lesser frequency, to the twins, quadratus femoris, adductors, as well as the middle, accessory, and deep gluteal muscles. In 74.19% of the sample, a branch communicating to the pudendal nerve was observed.