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BIO_Ch8

Terms in this set (69)

movement
a change in the place or position of the body or a body part
cerebral palsy
a congenital neurological motor disorder characterized by postural instability and extraneous movement
skeletal muscle
a type of muscle that produces the movements of bones
tendon
a strong band of connective tissue linking a muscle to a bone that causes the bone to move when the muscle contracts
extensor muscle
a muscle that produces movement of a limb away from the body
flexor muscle
a muscle that produces movement of a limb toward the body
muscle fiber
one of the units comprising a skeletal muscle
myofibril
one of the units comprising a muscle fiber
myofilament
a component of a myofibril
myosin
the protein component of thick myofilaments
actin
the protein component of thin myofilaments
sarcomere
the functional unit of a myofibril, consisting of overlapping bands of thick myosin filaments and thin actin filaments
alpha motor neuron
a motor neuron with a long axon that leaves the ventral root of the spinal cord or brain stem and synapses with individual muscle fibers
extrafusal muscle fiber
a muscle fiber controlled by an alpha motor neuron
neuromuscular junction
a specialized synapse between an alpha motor neuron and an extrafusal muscle fiber
motor end plate
the flattened area of an extrafusal muscle fiber where a motor neuron and the muscle fiber synapse
myasthenia gravis
a neuromuscular disorder characterized by muscle fatigue following exercise
motor unit
an alpha motor neuron and all the muscle fibers it controls
slow-twitch muscle
a muscle fiber that contracts and fatigues slowly
fast-twitch muscle
a muscle fiber that contracts and fatigues quickly
intermediate-twitch muscle
a muscle fiber that contracts at a lower rate than fast-twitch and a higher rate than slow-twitch muscles
patellar reflex
a reflex in which tapping the tendon of the knee stretches one of the muscles that extends the leg, and the resulting muscle contraction causes the leg to kick outward
muscle spindle
a structure embedded within an extrafusal muscle fiber that enables the CNS to contract a muscle to counteract the stretching of the extrafusal muscle fiber
intrafusal muscle fiber
a muscle fiber within the muscle spindle that is surrounded by annulospiral endings
annulospiral ending
a sensory receptor in the central part of an intrafusal muscle fiber
la fiber
an axon from an annulospiral ending that enters the dorsal root of the spinal cord and synapses with an alpha motor neuron
polysynaptic reflex
a spinal reflex with more than one synapse between the sensory receptor and the muscle effector
withdrawal reflex
the automatic withdrawal of a limb from a painful stimulus
golgi tendon organ
a receptor located among the fibers of tendons that measures the total amount of force exerted by the muscle on the bone to which the tendon is attached
lb fiber
an axon of a golgi tendon organ that extends to the spinal cord and synapses with an interneuron that inhibits alpha motor neurons
renshaw cell
an inhibitory interneuron excited by an alpha motor neuron that causes it to stop firing, preventing excessive muscle contraction
gamma motor neuron
a neuron that synapses with intrafusal muscle fibers to produce continuous muscle tension
muscle tone
the resting tension of skeletal muscles caused by the activity of gamma motor neurons
dorsolateral prefrontal cortex
the top executive in the perception-action cycle; cells in this area integrate sensory information across time with motor actions needed to deal with the information
secondary motor cortex
a cortical area consisting of the supplementary motor area and the premotor cortex; involved in the planning and sequencing of voluntary movements
supplementary motor area
a part of the secondary motor cortex that receives input from the posterior parietal cortex and the somatosensory cortex
premotor cortex
a part of the secondary motor cortex that receives input mostly from the visual cortex
mirror neuron
neuron in the primate premotor cortex that is activated by performing an action or by watching another monkey or person performing an action
primary motor cortex
an area in the precentral gyrus of the frontal lobe that plays a major role in voluntary movements
precentral gyrus
an area in the frontal lobe that contains the primary motor cortex
pyramidal cell
a large, pyramid-shaped neuron in the primary motor cortex
posterior parietal cortex
a cortical area that integrates input from the visual, auditory, and skin senses and relays it to the primary motor cortex
contralateral neglect
a disturbance in the ability to respond to visual, auditory, or somatosensory stimuli on the left side of the body, generally caused by damage to the right posterior parietal cortex
apraxia
a movement disorder characterized by missing or inappropriate actions not caused by paralysis or any other motor impairment
constructional apraxia
a disorder characterized by difficulty drawing pictures or assembling objects
limb apraxia
an impairment in the voluntary use of a limb caused by damage to the left parietal lobe or the corpus callosum
apraxia of speech
a disorder characterized by difficulty speaking clearly, caused by damage limited to Broca's area
corticospinal tract
a motor pathway that controls movements of the fingers, hands, arms, trunk, legs, and feet
corticobulbar tract
a motor pathway that controls movements of the face and tongue
amyotrophic lateral sclerosis (ALS)
a degenerative neuromuscular disease caused by degeneration of the corticospinal and corticobulbar tracts and the anterior horns of the spinal cord
ventromedial tract
one of four motor pathways originating in different parts of the subcortex that control movements of the trunk and limbs
vestibulospinal tract
a ventromedial tract that plays a central role in posture
tectospinal tract
a ventromedial tract that controls upper trunk (shoulder) and neck movements and coordinates the visual tracking of stimuli
lateral reticulospinal tract
a ventromedial tract that activates the extensor muscles of the legs
medial reticulospinal tract
a ventromedial tract that activates the extensor muscles of the legs
rubrospinal tract
a motor pathway that controls movements of the hands, lower arms, lower legs, and feet
ballistic movement
a habitual, rapid movement that does not depend on sensory feedback
deep cerebellar nucleus
a group of neurons that correct movements in progress
purkinje cell
an output cell from the cerebellar cortex, which has an exclusively inhibitory effect
basket cell
cerebellar neuron that has an inhibitory influence on Purkinje cells
basal ganglia
a group of three structures that integrates voluntary movements; consists of the caudate nucleus, the putamen, and the globus pallidus
corpus striatum
the part of the basal ganglia consisting of the caudate nucleus and putamen
parkinson's disease
a degenerative neurological disorder characterized by rigidity of the limbs and muscle tremors
bradykinesia
a movement disorder characterized by slowed movement
festination
a tendency in a movement disorder to speed up a walking pace to running
levodopa (L-dopa)
a drug converted to dopamine in the brain; used to treat Parkinson's disease
thalamotomy
a psychosurgical treatment for Parkinson's disease that relieves tremors and improves rigidity but does not relieve bradykinesia
pallidotomy
a psychosurgical treatment for Parkinson's disease that reduces tremors, rigidity, and bradykinesia
hunington's disease
an inherited neurological disorder characterized by a slow, progressive detioration of motor control, cognition, and emotion
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