Spinal Nerves And Reflexes Flashcards
Spinal reflexes
They are subconscious
Spinal cord is divided into
Posterior median sulcus
Anterior median fissure
How many cervical nerves Thoracic nerves Lumbar nerves Sacral nerves Coccygeal nerves
Cervical 8 Thoracic 12 Lumbar 5 Sacral 5 Coccygeal 1-2
Dorsal roots
Are posterior and are always sensory
Ventral roots
Are anterior and are motor and control somatic and visceral effectors
Spinal nerve
Mixed nerves sensory and motor
Dura Mater
Tough outer layer of spinal cord
Three spinal meninges
Dura mater
Arachnoid mater
Pia mater
Protect spinal cord and carry blood supply
Arachnoid mater
Middle layer
Subdural space
Cerebrospinal fluid
Between dura and arachnoid
Pia mater
Inner most layer
Soft and connected to neural tissue
Denticulate ligaments
Keeps spinal cord in place
Extends from pia to dura so there is no side to side movement
Organization of gray mater
Posterior gray horns
Anterior gray horns
Lateral gray horns
Posterior gray horns
Somatic and visceral sensory nuclei
Anterior gray horn
Contain somatic motor nuclei
Lateral gray horn
Interneuron communication
Gray commissures
Connect right and left side of gray matter
Organization of white matter
Posterior white columns
Anterior white columns
Lateral white columns
Tracts or fasciculi
Bundles of axons relaying info in white matter
Ascending tracts
Carry sensory afferent info to brain
Go through the dorsal root
Descending tracts
Carry motor commands to spinal cord
Go through central root
Three tissue layers of spinal nerves
Epineurium outer layer collagen fibers
Perineurium middle divides nerves into axon bundles
Endoneurium inner surrounds individual axons
White ramus
Carries visceral motor fibers to sympathetic ganglion
Gray ramus
Returns sympathetic ganglion to rejoin spinal nerve
Dorsal ramus
Somatic and visceral to the back
Ventral ramus
Goes to the front
Dermatomes
Sections of skin supplied by certain spinal nerve
Four types of nerve plexuses of ventral rami
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
Phrenic nerve
Controls diaphragm and includes c1- c5
Cervical plexus
Major nerves of brachial plexus
Musculocutaneous nerve Median nerve Ulnar nerve Axillary nerve Radical nerve
Lumbar plexus major nerves
Genitofemoral nerve
Lateral femoral cutaneous nerve
Femoral nerve
Sacral plexus major nerves
Pudendal nerve
Sciatic nerve
Organization of neurons
Sensory neurons
Motor neurons
Interneurons
Neuronal pools
Functional groups of interconnected neurons
Five patterns of neuronal pools
Divergence Convergence Serial processing Parallel processing Reverberation
Reflex arc
Begins at receptor and ends at peripheral effector
5 steps of neural reflex
Arrival of stimulus, activation of receptor activation of sensory neuron Info process by postsynaptic ganglion Activation of motor neuron Response of peripheral effector
Monosynaptic reflex
Sensory neuron synapse directly on motor neuron
Polysynaptic reflex
At least one interneuron is between sensory and motor neuron
Stretch reflex
Triggered by elongation of tendon
Ex: patellar reflex
Intrafusal muscle fibers
Receptors that sense the stretch
In a stretch reflex
3 characteristics of polysynaptic reflexes
Involve reciprocal inhibition
Involve pools of neurons
Several reflexes cooperate
Reciprocal inhibition
Motor neurons are stimulated, the neurons that control the opposing muscle are inhibited. This allows one muscle to flex and opposing to relax
Golgi tendon organs
Located between skeletal muscle tendon. Dendrites branch and wrap around tendon. Stimulated by tension in tendon. Monitor external tension, when stimulated during contraction it will cause muscle to relax
Autonomic reflexes
Involuntary superficial skin and mucous membranes
Stretch or deep tendon reflexes
Visceral reflexes
Control systems other than muscular system
Smooth, cardiac, glands, adipose tissue
