Spinal cord reflex arcs Flashcards
Stretch reflex arc: sensory receptor
Muscle spindle in striated muscle
- intrafusal fibers + CT capsule
- anulospiral nerve endings + flower spray nerve ending (activated by elongation)
- Agamma motorneuron innervate
Stretch reflex arc: sensory neuron
Type IA muscle sensory neuron
- pseudounipolar
- thick myelinated
- dorsal root ganglion to ventral horn
- collaterals to Clarke’s column
Stretch reflex arc: Interneurons
No interneurons
-exept collaterals synapse with inhibitory interneurons -> terminate on motoneurons innervating muscles antagonist
Stretch reflex arc: Effector neuron
A alpha motoneuron
- lamina 9
- thick, myelinated
Stretch reflex arc: Effector organ
Motor end plate in the same striated muscle
Withdrawal reflex arc: Sensory receptor
Free nerve endings in skin- nocireceptors
-mechanical, thermal, chemical stimuli
Withdrawal reflex arc: Sensory neuron
Fine myelinated A delta or unmyelinated C
- pseudounipolar
- peripheral branches collected in skin nerves
- central branches follow dorsal root
- dorsal root (lateral aspecy) -> Lissauer tract
- collaterals to lamina 1 and 2 and 5
Withdrawal reflex arc: Interneurons
1 or several
- last one in row exite motorneuron in ventral horn-innervates flexor m.
- activate tract neuron- cross - spinothalamic tract (PAIN)
- contralateral collaterals of spinothalamic tract - contralateral motoneurons - innervate extensor m.
Withdrawal reflex arc: Effector neuron
A alpha motoneuron
- lamina 9
- thick, myelinated
- ventral root -> flexor m.
Withdrawal reflex arc: Effector organ
motor end plate of striated muscle
Autonomous reflex arc: Sensory receptor
Free nerve ending in the viscera
-stretching of organ, tension by obliteration of tube-like organ, insufficient blood supply
Autonomous reflex arc: sensory neuron
Fine myelinated A delta or unmyelinated C
- pseudounipolar
- peripheral branches - visceral nerves
- central branches - dorsal root
- dorsal root (lateral) -> Lissauer tract
- collaterals to lamina 1 and 5
Autonomous reflex arc: Interneurons
1 or more
- linkage between sensory and motor neurons
- mismatched signaling between autonomous and withdrawal
Autonomous reflex arc: Effector neuron
Preganglionic and postganglionic
-ventral root -> white communicating rami -> sympathetic trunk -> join lesser and greater splanchnic nerves -> celiac ganglion -> postganglionic neuron to organ (ganglion depend on level)
Autonomous reflex arc: Effector organ
Grundplexus
