LAB 21 Introduction
Pelvic Limb & Pelvic Nerves
and Arteries of the Pes
(Guide to the Dissection of the Dog, pp. 195-204)
Lab Objectives:
Medial View
• Find nerves that innervate the pelvic limb:
- obturator nerve (to medial thigh muscles)
- femoral nerve (to cranial thigh muscles) & saphenous n. (medial limb)
Lateral View
• Find nerves from sacral plexus to pelvis:
- pudendal nerve (SE and GSA to/from pelvic organs)
- pelvic nerve (VE and GVA to/from pelvic organs)
- caudal cutaneous femoral nerve
• Find nerves that innervate the pelvic limb:
- lumbosacral trunk (L6, L7, & S1)
-- cranial gluteal n. (gluteal & tensor fasciae latae mm.)
-- caudal gluteal n. (superficial gluteal m.)
- sciatic (ischiatic) n. (L6, L7, S1, & S2 )
-- tibial n. (caudal muscles of crus & plantar pes sensation)
-- common peroneal n., divides into: superficial & deep peroneal nn.
(cranial muscles of crus & dorsal pes sensation)
• Optionally, dissect lumbosacral plexus (L4 to S3 ventral branches),
located within sublumbar musculature and in the pelvic cavity.
• Arteries of the pes:
- dorsal pedal a. = cranial tibial a. re-named in the pes (foot)
-- arcuate a.
- perforating branch
Anatomical Terms:
Pelvic Limb Nerves
Lumbosacral Plexus:
obturator nerve
femoral nerve
saphenous nerve
pudendal nerve
caudal rectal nerve
perineal nerves
dorsal nerve of the penis (clitoris)
caudal cutaneous femoral nerve
lumbosacral trunk
cranial gluteal nerve
caudal gluteal nerve
sciatic nerve
common peroneal nerve
lateral cutaneous sural n.
superficial peroneal n.
deep peroneal nerve
dorsal digital nn.
tibial n.
caudal cutaneous sural nerve
plantar digital nn.
Arteries of the Pes
dorsal pedal a.
arcuate a.
dorsal metatarsal aa.
perforating branch
plantar digital aa.
Note:
coxa [Latin = hip] e.g., os coxae = bone of the hip
ischium [Latin & Greek ischion = hip] - caudal part (bone) of hip bone
sciatic [Latin: sciaticus = pertaining to the ischium]
ischiatic [Latin: ischiaticus = pertaining to the ischium]
Instructor Commentary:
The lumbosacral plexus which innervates the pelvic limb and pelvis, is formed by ventral braches of spinal nerves L4 to S3 in the carnivore. The lumbar portion of the plexus is located inside sublumbar musculature.
Innervation of the pelvic limb may be summarized as follows: The obturator n. innervates medial (adductor) muscles. The femoral n. innervates cranial muscles of the thigh. All remaining muscles of the limb are innervated by the sciatic n. After sending branches to hamstring muscles, the sciatic innervates muscles of the crus with two branches: the tibial n. to caudal muscles and the common peroneal n. to cranial muscles.
The sacral portion of the lumbosacral plexus gives rise to two principal nerves (in addition to cutaneous nerves): The pelvic n. carries parasympathetic visceral efferent innervation to pelvic viscera (smooth muscle and glands) and general visceral afferents from the viscera. The pudendal n. carries somatic efferent innervation to anal and urethral voluntary sphincters and general somatic afferent innervation from pelvic structures including the anus and penis/clitoris.
NOTE: The lumbosacral plexus paragraph in Guide to the Dissection of the Dog (p.195) states that the lumboscral plexus begins with the L1 ventral branch (which is official NAV terminology). However, with one exception, the first three lumbar ventral branches run independently. The actual plexus begins at L4 (L4 through S3). The one exception is that genitofemoral nerve fibers commonly arise from L3 & L4.
Dissection Images:
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