The Sensorimotor System Flashcards
What are antagonistic muscles?
pairs of muscles that act in opposition
What is apraxia?
a disorder in which patients have great difficulty performing movements when asked to do so out of context but can readily perform them spontaneously in natural situations
What is astereognosia?
an inability to recognise objects by touch that is not attributable to a simple sensory deficit or to an intellectual impairment
What are betz cells?
large pyramidal neurons of the primary motor cortex whose axons form part of the dorsolateral corticospinal tract
What are central semsoimotor programs?
patterns of activity that are programmed into the sensorimotor system
What are cingulate motor areas?
two small areas of secondary motor cortex located in the cortex of the cingulate gyrus of each hemisphere
What is cocontraction?
the simultaneous contraction of antagonistic muscles
What is contralateral neglect?
a disturbance of the patient’s ability to respond to stimuli on the side of the body opposite to a site of brain damage, usually the left side of the body following damage to the right parietal lobe
What is the dorsolateral corticorubrospinal tract?
the descending motor tract that synapses in the red nucleus of the midbrain, decussates, and descends in the contralateral dorsolateral spinal white matter
What is the dorsolateral corticospinal tract?
the motor tract that leaves the primary motor cortex, descends to the medullary pyramids, decussates, and then descends in the contralateral dorsolateral spinal white matter
What is the dorsolateral prefrontal association cortex?
an area of the prefrontal cortex that plays a role in the evaluation of external stimuli and the initiation of complex voluntary motor responses
What is dynamic contraction?
contraction of a muscle that causes the muscle to shorten
What are extensors?
muscles that act to straighten or extend a joint
What are flexors?
muscles act to bend or flex a joint
What is the frontal eye field?
a small area of prefrontal cortex that controls eye movements
What are golgi tendon organs?
receptors that are embedded in tendons and are sensitive to the amount of tension in the skeletal muscles to which their tendons are attached
What is a intrafusal motor neuron?
a motor neuron that innervates an intrafusal muscle
What is a intrafusal muscle?
a threadlike muscle that adjusts the tension on a muscle spindle
What is isometric contraction?
contraction of a muscle that increase the force of its pull but does not shorten the muscle
What are mirror neurons?
neurons that fire when an individual performs a particular goal-directed hand movement or when they observe that same goal-directed movement performed by another
What is a motor end-plate?
the receptive area on a muscle fibre at a neuromuscular junction
What is motor equivalence?
the ability of the sensorimotor system to carry out the same basic movement in different ways that involve different muscles
What is the motor homunculus?
the somatotopic map of the human primary motor cortex
What is a motor pool?
all of the motor neurons that innervate the fibres of a given muscle
What are motor units?
a single motor neuron and all of the skeletal muscle fibres that are innervated by it
What are muscle spindles?
receptors that are embedded in skeletal muscle tissue and are sensitive to changes in muscle length
What is the patella tendon reflex?
the stretch reflex that is elicited when the patella tendon is struck
What is the posterior parietal association cortex?
an area of association cortex that receives input from the visual, auditory, and somatosensory systems and is involved in the perception of spatial location and guidance of voluntary behaviour
What is the premotor cortex?
the area of secondary motor cortex that lies between the supplementary motor area and the lateral fissure
What is the primary motor cortex?
the cortex of the precentral gyrus, which is the major point of departure for motor signals descending from the cerebral cortex into lower levels of the sensorimotor system
What is reciprocal innervation?
the principle of spinal cord circuitry that causes a muscle to automatically relax when a muscle that is antagonistic to it contracts
What is recurrent collateral inhibition?
the inhibition of a neuron that is produced but its own activity via a collateral branch of its axon and an inhibitory interneuron
What is the response-chinking hypothesis?
the idea that practice combines the central sensorimotor programs that control individual responses into programs that control sequences (chunks) of behaviour
What is the reticular formation?
a complex network of about 100 tiny nuclei that occupies the central core of the brain stem
What is the secondary motor cortex?
an area of the cerebral cortex that receives most of its input from the primary sensory cortex of one sensory system or from other areas of secondary cortex of the same system
What is sensory feedback?
sensory signals that are produced by a response and are often used to guide the continuation of the response
What is skeletal (extrafusal) muscle?
striated muscle that is attached to the skeleton and is usually under voluntary control
What does somatotopic mean?
organised, like the primary somatosensory cortex, according to a map of the surface of the body
What are spindle afferent neurons?
neurons that carry signals from muscle spindles to the spinal cord via the dorsal root
What is stereognosis?
the process of identifying objects by touch
What is the stretch reflex?
a reflexive counteracting reaction to an unanticipated external stretching force on a muscle
What is the supllementary motor area?
the area of secondary motor cortex that is within and adjacent to the longitudinal fissure
What are synergistic muscles?
pairs of muscles whose contraction produces a movement in the same direction
What is the tectum?
the “roof”, or dorsal surface, of the mesencephalon; it includes the superior and inferior colliculi