What are motor neurons?
-innervates multiple fibers on same muscle
Motor unit
is when an alpha motor unit innervates 1 muscle fiber ??????
Patellar reflex response
- 2 is considered normal
Patellar reflex response 0-2
Patellar reflex response 3-4
What can cause hyper-reflexion?
- hyperthyroidism, pre-clampsia (hypertension in pregnancy)
Why is reflex necessary?
-protect joints from hyperextension
What is clonus?
-reflex constant–continued firing
What causes the patellar reflex?
-The stretch reflex
Stretch reflex location (4) and nerve root that corresponds
Static response
-steady-state; causes tone
Dynamic response
-velocity of change in muscle response
What kind of response is used in stretch reflex?
-dynamic response
Outline the stretch reflex
-stimulus–stretch patellar tendon–passive stretch of muscle spindles–sensory 1a neurons distorted–receptor potential generated–action potential sent through sensory fiber–alpha motor neuron discharged–contraction of extrafusal fibers (EPSP/IPSP)–muscle spindle unloads–sensory fibers start firing–gamma motor neuron activated–intrafusal fiber shorten–sensory 1a neurons stop sending signal–extrafusal muscle relaxes
EPSP
IPSP
Intrafusal fibers
Extrafusal fibers
Afferent fibers in muscle spindles
- II: static; causes muscle tone
Counterstrain technique
Golgi tendon reflex
Inverse myotatic reflex
-tension too great–golgi organ stimulates sensory 1b fiber–generates IPSP (relaxation) on agonist AND EPSP (contraction) on anatagonist–contraction stops–muscle relaxes
Muscle energy
Flexion reflex
stimulus occurs–EPSP interneurons stimulate alpha motor neuron to activate flexion of muscles on limb stimulus occurred AND– IPSP interneurons activate alpha motor neurons to inhibit antagonist extensor muscles–causes one or more joints to flex