Chapter 7-Sensory systems, motor systems

the process by which sensory receptors convert stimuli into electrical signals that can be interpreted by the nervous system

sensory transduction

detect light touch and vibration

meissner’s corpuscles

detect sustained pressure, texture

merkel cells

respond to deep pressure, rapid vibrations

pacinian corpuscles

detect skin stretch, sustained pressure

ruffini endings

carries fine touch, vibration, proprioception, crosses over in the medulla before reaching the thalamus and sensory cortex

dorsal column

carries pain, temperature, crude touch, crosses over at the spinal cord level before reaching the thalamus and sensory cortex

anterolateral pathway

detect muscle stretch, help maintain posture

muscle spindles

detect tension in tendons and prevent excessive force

golgi tendon organs

detect changes in joint position and movement

joint receptors

maintains balance and spatial orientation

vestibular system (inner ear)

plays a critical role in both the planning and ongoing control of voluntary mpovements

cerebral corted

sensorimotor cortex

includes all parts of the cerebral cortex

a large number of neurons that give rise to descending pathways for motor control

primary motor cortex

neurons from here project directly to the spinal cord, play a role in the postural stabilization of the body

supplementary motor area

neurons play an important role in the visual control of movements

parietal association cortex

subcortical nuclei, help with motor problems, damage to this can result in motor problems, parkinson’s

basal nuclei

receives info from the sensorimotor cortex and receptors, provides timing signals to the cerebral cortex, helps coordinate movements

cerebellum

nerve fibers start in sensorimotor cortex, terminate in the SC, cross the midline. control muscles on the opposite side of the body

corticospinal pathway

most descending neurons synapse onto

local interneurons

descends from the sensorimotor cortex and ends in the brainstem. fibers synapse w motor neurons of the cranial nerves that innervate muscles of head and neck

corticobulbar pathway

especially important in controlling muscles of the trunk for posture, balance walking

brainstem pathways

a slight resistance when a muscle is stretched by an external force

muscle tone

conditions with abnormally high muscle tone, usually due to problems in the descending pathways inhibiting the motor neurons of the antagonist muscle

hypertonia

condition of abnormally low muscle tone

hypotonia