Chapter 4 Flashcards
Neuron situated in a dorsal root ganglion just outside the spinal cord, afferent
Sensory
Neuron situated in the anterior horns of spinal cord, efferent
Motor neuron
Bundle of fibers enclosed within a connective tissue sheath, for transmission of impulses
Nerves
Total number of spinal nerves
31
Connection between neurons
Synapse
An excitatory stimulus
Facilitation
An inhibitory stimulus
Inhibition
Sensory receptors (2)
1) exteroceptors
2) interoceptors
Receptors Stimulated by body movements, transmits information to cns
Proprioceptors
Two primary categories of proprioceptors
1) muscle
2) joint and skin receptors
Muscle proprioceptors: located in muscle belly, parallel with fibers
Muscle spindles
Muscle proprioceptors: when stretched, sensory nerve sends impulses to CNS, which activates the motor neurons facilitating contraction of the same muscle
Muscle spindles
“Regular” muscle fibers
Extrafusal
Muscle fibers inside spindles
Intrafusal
Two types of nerve endings in spindles
1) primary/ annulospiral endings
2) flower spray endings
Nerve endings in spindle: coiled around non-contractile midsection, sensitive to velocity of change (phasic), sharp decline in impulses with static length change
Annulospiral endings
Nerve endings in spindle: at end of non-contractile midsection, respond to static muscle length, impulses directly proportional to change in length
Flower spray endings
Neurons that stimulate the intrafusal fibers to contract, shortening the muscle spindle
Gamma motor neurons
Muscle proprioceptors: embedded “ in series” in the tendon, as tension in tendon increases it activates, signals CNS to relax muscle
Golgi tendon organ
Joint and skin proprioceptors: in regions around joint capsules, ligaments, and tendon sheaths, activated by joint angle changes and pressure
Pacinian corpuscles
Joint and skin proprioceptors: in deep layers of skin and joint capsule, activated by mechanical deformation, stimulated strongly by sudden joint movement, sense joint position and changesin joint angle
Ruffini endings
3 cutaneous receptors:
1) meissner corpuscles
2) pacinian corpuscles
3) free nerve endings
Cutaneous receptors: touch
Meissner corpuscles
Cutaneous receptors: pressure
Pacinian corpuscles
Cutaneous receptors: pain
Free nerve endings
System concerned with sense of balance that consists of utricle, saccule, and semicircular canals
Labyrinthine
Labyrinthine and neck proprioceptors: sensitive to linear acceleration and head position with respect to gravity
Utricle
Labyrinthine and neck proprioceptors: sensitive to angular acceleration, three canals oriented indifferent planes at right angles to each other
Semicircular canals
Labyrinthine and neck proprioceptors: sensitive to angle between the body and the head, prevents labyrinthine proprioceptors from producing feeling of imbalance
Joint receptors of the neck
A specific pattern of response without volition from the cerebrum, stimulus - receptor organ - sensory neuron - motor neuron - muscle ( response)
Reflex movement
stimulus - pressure
receptor- pacinian corpuscles
response - contraction of the extensor muscles of that limb
extensor thrust reflex (exteroceptive reflex)
stimulus - pain, noxious stimuli
receptor - free nerve endings
response - quick withdrawal from source of pain
flexor reflex, exteroceptive reflex
stimulus - flexor reflex or un-weighting
response - opposite extensors contract for support
corssed extensor reflex
a reflex contraction of stretched muscle and synergists and relaxation of antagonists
stretch reflex
stimulus - high velocity stretch
receptor - annulospiral endings of muscle spindle
response - facilitates proportional contraction of stretched muscle
phasic response
stimulus - slow sustained stretch
receptor- flow spray endings of muscle spindle
response - gamma efferent system rests spindle tension using intrafusal fiber contraction or relaxation
tonic response
stim - high level of stretch, due to muslce stretch or muscle contraction
receptor - golgi tendon organ
response - relaxation of stretched muscle and facilitation of antagonist
tendon relex
stim - head not upright with respect to graity
recep - utricle and semicircular canals
response - bring the head to the upright position
–is integrated with movements ofthe arms and les as described in the tonic neck and labyrinthine reflexes
righting reflex
tonic neck reflex:
stim- head/neck flexion/hyper extension
receptor - neck receptors
response - h/n flexion facilitates upper extremity fleion, or hyperextension
symmetrical
tonic neck reflex:
stim - head/neck rotatoin
receptor - neck receptors
response - h/n rotation facilitates upper extremity chin side ab/ and extension, back of head side adduction and flexion
asymmetricl response
CNS level of control: where consciousness occurs, initiation of voluntary movement
erebral cortex
CNS level of control: responsible for homeostasis, coordination and some learned acts of posture
basal ganglia
CNS level of control: key role in sensory integration, regulates timing and intensity of muscle contraction
cerebellum
CNS level of control: arousal and monitoring of physiological parameters, key facilitory and inhibitory centers
brain stem
CNS level of control: contains cell bodies of lower motor neurons, common pahtway between CNS & PNS, final point for integration and control
spinal cord
the conscious awareness of position of body parts and the amt and rate of joint movement
kinesthesis
