Sensory and Motor Systems
Start with the big picture
Sensory processing follows a sequence from stimulus and receptor through central nervous system processing to a response. Receptors differ in how they respond over time: some detect changes in a stimulus, while others signal sustained input. The dorsal column–medial lemniscus pathway carries fine touch, proprioception, and vibration, ascending on the same side before crossing in the medulla. The anterolateral pathway carries pain, temperature, and crude touch, crossing in the spinal cord. Motor organization includes upper motor neurons, which originate in the cortex, and lower motor neurons, which originate in the anterior horn. Their lesions produce different clinical signs. Reflex arcs range from the monosynaptic stretch reflex to polysynaptic withdrawal responses.
What you'll learn
- Trace the sequence from sensory stimulus detection to response.
- Distinguish rapidly adapting from slowly adapting sensory receptors.
- Compare the modalities and crossing points of the major sensory pathways.
- Differentiate upper and lower motor neuron lesion findings.
- Contrast monosynaptic stretch reflexes with polysynaptic withdrawal reflexes.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
