test 1: lecture 8 Flashcards
interfusal fibers are stimulates by ___
gamma neuron
extrafusal fibers are innervated by ___
alpha motor fiber
spinal nerve and their relationship to vertebral bodies
there are 8 cervical spinal nerves
C1-7 come off before its named vertebrae
C8 after Cervical Vet 7
spinal nerve T→ sacral comes off after the named vertebrae
division of spinal cord
C1-5
C6-T2 (front leg)
T3-L3
L4-Caudal5 +cauda equina (back leg)
lumbar enlargment
femoral nerve is made of what spinal nerve?
L4,5,6
obturator nerve is made of what spinal nerve?
(L4) 5, 6
cranial gluteal is made of what spinal nerves
L6,7, S1
caudal gluteal is made of what spinal nerves
L7, (S1 and S2)
sciatic nerve is made of what spinal nerves?
L6, 7, S1 and (S2)
what spinal nerves innervate the front limbs?
radial
ulnar
musculocutaneous
what nerve innervates the pelvic limbs?
femoral
sciatic which branch into the
- tibial
- peroneal
myotatic reflexes
stretch reflexes
3 types of myotatic reflexes for the front limb
Stretch reflex
- Extensor carpi radialis reflex
- Triceps reflex
- Biceps reflex
3 types of myotatic reflexes for the hind limb
stretch reflex
- Patellar reflex
- Cranial tibial reflex
- Gastrocnemius reflex
alpha motor neurons go to ___ and are under ___ control
skeletal muscle fibers
voluntary motor
gamma motor neurons go to ___ and help regulate ___ reflex. Gamma will also create the ___ for alpha motor neurons.
muscle spindles (intrafusal fibers)
stretch
baseline activity
___ neuron help with proprioception and tone and position
gamma motor
withdrawal reflex on back leg
pinch toe
sensory through dorsal root
synapse in dorsal horn on interneuron
interneuron will synapse on motor to send flexor contraction and extensor inhibition on same side
another interneuron will synapse and send contralateral extensor inhibition by UMN to other limb (body is laying down does not need to extend not pinched leg)
perineal reflex
anal sphincter
babinski
flexion (normal)
extension (bad)
crossed extensor reflex
pathologic- something is wrong- lesion somewhere
pet laying down pinch R toe
R leg flexes, L leg extends
(in normal, when laying down, there should not be movement in L leg)
crossed extensor reflex is a ____ motor neuron sign
upper
(there is a lesion somewhere in the spinal cord that is preventing a signal from telling the opposite leg to NOT move when laying down)
contralateral extension NOT inhibited by YMN
cutting lower motor neuron results in
small reflex
decreased tone
cutting UMN will cause
big reflex (hyper-reflexive)
spastic tone (increased)
upper or lower motor nerve damage results in increased tone?
upper
increased tone and big relfex
upper or lower motor neuron defect results in flaccid muscles?
lower
flaccid and weak reflex
what toxin results in stiffness and big reflexes
tetanus
what results in weakness/paresis and paralysis
damage to motor neurons
lower motor neuron disorders
- Decreased segmental reflexes
- Paresis (flaccid)
- Short strided gait
- +/- cranial nerve deficits
monosynaptic spinal reflex
damage to UMN (tract in spinal cord)
big reflex
spastic paresis
+/- CN deficits
upper motor neuron disorders
big reflex
spastic paresis
+/- CN deficits
___ motor neuron disorder causes short strided gait
lower motor neuron disorder
