Somatosensory and motor pathways Flashcards
properties of somatic nervous system
Effector organ = skeletal muscle
Contain heavily myelinated axons that extend from the CNS to skeletal muscle
Neurotransmitter released = ACh
Target = nicotinic ACh receptors (ligand gated ion channels)
Characteristics the neuromuscular junction
Muscle movement
no ganglia
Transmitter acetylcholine
recptor nicotinic receptor
Difference between Spinal reflex and cranial reflex
Intergration occurs in spinal cord in spinal reflex
whereas in cranial reflex, intergration occurs in the brain
What are monosynaptic msucle reflexes
Single sensory afferent neuron
Single efferent somatic motor neuron
Synapse in spinal cord
What is polsynaptic skeletal muscle reflex
complex
extensive banchin in CNS
Divergence - single stimulus can affect musltiple targets
Convergence - multiple stimuli intergrated to modify response
What is the sequence of events that occur in skeletal muscle reflex
Activation of propriorecptos in muscles, joints and ligaments
AP fires and signals to CNS
INtegration occurs and response sent
What responses are sent in skeletal muscle reflexes
COntration - somatic motor nerve activated
Relaxation - inhibitory interneurons activated
Refelx is subconcious - intergration in cerebral cortex can consiouslt modulate reflex
What are muscle spindles
Muscle spindles are stretch receptors that signal the length and changes in length of muscles. They lie within an independent capsule, parallel to the main muscle. They are therefore stretched when the muscle lengthens but shorten when the muscle contracts.
Central region of intrafusal fibres
Multiple per muscle
Tonic activity
What are golgi tendon organs
Found between muscles and organs Free nerve endings surrounding collagen fibers Respond to isometric contraction provide sensory information senses the changes in the muscle tension
What do alpha motor neurons innervate
Innervate skeletal msucles extrafusal fibres
What do gamma motor neurons innrevate
innervate intrafusal fibres
What is voluntary movement
External stimuli or at will
Most complex - intergrated at cerebral cortex
Learned moevemnts that improve with practice, once learned can become subconcious
What stimulus inititates reflex movement
Primarily external via sensory receptors; minimally voluntary
WHat is rhythmic movement
Initiation, termination and modulation voluntary
INtermediate complexity - intergrated in spinal cor wth higher centre input required
spinal circuits act as pattern generators
