Page 410 - Canine Lameness

Table 21.2 Summary of the major motor and sensory distribution of the lumbosacral plexus.
Spinal cord Segmental
Nerve segments Muscle innervated Motor function Cutaneous sensory zone spinal reflex Signs of dysfunction
Sciatic L6, L7, S1, S2 Biceps femoris, Extension of hip, Entire limb (via tibial Flexor Severe gait dysfunction
gastrocnemius, cranial extension and and peroneal branch) withdrawal Paw is knuckled, but able to
tibial, semitendinosus, flexion of stifle except for medial reflex (stifle support weight
and semimembranosus (see tibial and aspect and first digit flexion) Hip cannot be extended, hock
peroneal branches) cannot flex or extend (in more
proximal lesions, hip is flexed and
drawn toward the midline)
Absent flexor reflex
Loss of cutaneous sensation distal
to stifle (except for areas supplied
by saphenous nerve)
Fibular L6, L7, S1, S2 Tarsal flexors and Flexion of hock Dorsal aspect of Cranial tibial Hock is straightened, and foot
(peroneal) digital extensors and extension of metatarsus and paw reflex and tends to knuckle
branch of the digits withdrawal Poor hock flexion on flexor reflex
sciatic nerve reflex Loss of sensation on cranial
(hock flexion) surface distal to stifle
Tibial branch L6, L7, S1, S2 Tarsal extensors and Extension of hock Plantar aspect of Gastrocnemius Hock is dropped
of the sciatic digital flexors and flexion of digits metatarsus and paw reflex Loss of sensation on caudal
nerve surface of limb distal to stifle
Femoral L3, L4, L5, L6 Quadriceps group Extension of stifle Medial aspect of thigh Patellar reflex Severe gait dysfunction
and psoas group and flexion of hip and paw, first digit Non‐weight‐bearing
Decreased or absent patellar
reflex
Anesthesia in medial limb and
medial digit
Obturator L4, L5, L6 Adductors Adduction of None None Little gait abnormality
pelvic limb Abduction on slick surface
Genitofemoral L3, L4 None None Proximal aspect of the None Loss of sensation medial thigh
medial thigh and
pudendal region
The major spinal cord segments that for the nerve are underlined.

12/10/2019 1:51:45 PM
Chapter No.: 1 Title Name: <TITLENAME>
0004507104.INDD 382 0004507104.INDD
Comp. by: <USER> Date: 10 Dec 2019 Time: 01:51:44 pm Stage: <STAGE> WorkFlow:CSW Page Number: