The lumbar dorsal rami of the wild pig: the intermediate branch


Abstract: This study has documented the intermediate branch of the dorsal rami of the spinal nerves in the lumbar region of 4 adult wild pigs. The lumbar spinal nerves at the L1-L4 levels left the vertebral canal through the intervertebral foramen. Upon the dissection of the 32 dorsal rami at these levels, 24 were displayed to construct 3 discrete branches while the remaining 8 were observed to form 2 typical branches. The dorsal rami were remarkably short, giving their branches in a fan-like spreading fashion. The lateral branches sent 2 to 3 smaller subbranches to the iliocostalis lumborum muscle, then became the cutaneous nerve. The medial branch innervated the medial component of the intertransversal and the multifidus muscles. The intermediate branch directed into the longissimus lumborum muscle, ramifying there and sending no cutaneous branches to the skin area. Four out of 8 dorsal rami dissected at L5 sent off the intermediate branch with roughly similar patterns and distributions to those seen at L1-L4. The dorsal branches at L6 were relatively longer, advanced dorsally, giving a constant branch, presumably the intermediate branch, to the caudal edge of the longissimus lumborum muscle. It then coursed upward through the subcutaneous fascia as the cutaneous nerve.

Keywords: Wild pig, lumbar dorsal rami, intermediate branch

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