Dorsal Nerve Root Origins of the Cutaneous Nerves of the Feline Pelvic Limb

Abstract

The dorsal root origins of cutaneous nerves supplying the feline pelvic limb were determined electrophysiologically in 11 cats. Cutaneous nerves were surgically exposed and the presence or absence of an evoked potential in response to stimulation of individual dorsal roots was noted. The dorsal cutaneous branches of L3-L5 and S3, and the lateral cutaneous branch of L3 each arose solely from their parent spinal nerves. The L7, S1, and S2 dorsal cutaneous branches had multiple dorsal root origins. The lateral cutaneous femoral nerve originated from L3-L6 dorsal roots in 4 patterns of origin, and the saphenous nerve originated from L4-L6 dorsal roots in 2 patterns of origin. The lateral and caudal cutaneous sural nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The lateral and medial plantar nerves arose from L6-S2 roots in 4 and 2 patterns, respectively. The superficial and deep peroneal nerves originated from L6-S1 roots in 2 and 3 patterns, respectively. The caudal cutaneous femoral nerve or its branches arose from L7-S3 in 8 origin patterns. The dorsal nerve of the penis and the superficial perineal nerve arose from L7-S3 and S1-S3 roots, respectively, each in 4 patterns. A subtle correlation between plexus type and dorsal root origins of the cutaneous nerves was noted.

Comparison of the Lumbosacral Plexus Nerves Formation in Pampas Fox (Pseudalopex gymnocercus) and Crab‐Eating Fox (Cerdocyon thous) in Relationship to Plexus Model in Dogs

“…However, in our study and indirectly in Bayley's description, the cutaneus femoris lateralis was observed as a branch of the first trunk, similarly to described in South American fur seal (Castro et al, 2009). Still, the nerve genitofemoralis was not formed by the LSP or by the first trunk as described in dogs (Fletcher, 1970, Bailey et al, 1988, but was originated from L3-4. No differences were observed in structures innervated by the femoralis and obturatorius in dogs, P. gymnocercus and C. thous, but our results showed three branches emerging from the femoralis: two rami innervating the femoral medial muscles, while the nerve saphenus (third ramus) supplying the medial musculature and skin of the limb distal portion.…”

“…However, was not prefixed type because L3 and L4 ventral branches not form the plexus, but was post-fixed due participation of S1-2 ventral branches. More, the plexus presented three trunks: L5-6-S1, L6-7-S1-2 and L7-S1-2, while in dog were described two (L3-6 and L6-7-S1-2, Fletcher, 1970;Bailey et al, 1988).…”

“…However, Fletcher (1970), Bailey et al (1988), and Mihelić et al (2007) reported that the LSP of dog presenting three models of organization: pre-(L3-S1), median-(L4-S1, predominantly), and postfixed (L4-S2), which was variably between body size, pure-breed, and nonpure-breed dogs. Recently, Gomez-Amaya et al (2015) proposed a classification of a mixed pre-post-fixed plexus (L3-S2), but indicated that the LPS in dogs possess a high degree of variability, independently of breed.…”

“…The contribution of S1 ventral rami in the formation of the femoralis and obturatorius nerves was not described in dogs or others carnivores. In domestic mammals (Getty, 1975, Dursun, 2000, as in dogs (Bailey et al, 1988), the more cranial lumbar ventral rami (L1-4) emerge constituting the nerves: iliohypogastricus (L1), ilioinguinalis (L2) and genitofemoralis (L3-4). To Bailey et al (1988), between the first lumbar nerves, only the cutaneus femoris lateralis was formed by multiple ventral rami (L3-5).…”

“…In domestic mammals (Getty, 1975, Dursun, 2000, as in dogs (Bailey et al, 1988), the more cranial lumbar ventral rami (L1-4) emerge constituting the nerves: iliohypogastricus (L1), ilioinguinalis (L2) and genitofemoralis (L3-4). To Bailey et al (1988), between the first lumbar nerves, only the cutaneus femoris lateralis was formed by multiple ventral rami (L3-5). However, in our study and indirectly in Bayley's description, the cutaneus femoris lateralis was observed as a branch of the first trunk, similarly to described in South American fur seal (Castro et al, 2009).…”