Somatosensory System

Which of the following are features of warm receptors?

1. an increase in action potential frequency as the skin temperature decreases

2. small diameter myelinated axons

3. conduction velocities in the range of 12-30 m.sec-1

• 1 only

• 2 & 3 only

• 1 & 3 only

• 1, 2 & 3

• none of these are features of warm receptors

In humans the homunculus is located in which of the following regions?

• brain stem

• ventrobasal complex

• presentation gyrus of parietal lobe

• postcentral gyrus of frontal lobe

• postcentral gyrus of parietal lobe

The area of somatosensory cortex that is dedicated to different parts of the homunculus is determined by which of the following?

• the type of receptors which innervate the region

• the number of sensory neurones which innervate the body region

• the size of the body region

• the innervation density of the body region

• how often you use the area

The total surface area of somatosensory cortex dedicated to different regions of the body is determined by which of the following?

• the type of mechanoreceptors that innervate the region

• the number of mechanoreceptors that innervate the body region

• the surface of the body region

• how thin the skin is in the region

• the innervation density of the body region

Which of the following classes of neurone have axons that terminate in the thalamus?

• touch receptors

• spinothalamic tract neurones

• thalamospinal tract neuones

• polymodal nociceptors

• thalamocortical neurones

The class of neurones that provides information about the rate of application of a low threshold mechanical stimulus would be an example of which of the following?

• very rapidly adapting mechanoreceptor

• slowly adapting mechanoreceptor

• rapidly adapting mechanoreceptor

• slowly adapting cutaneoreceptor

• rapidly adapting thermoreceptor

Which of the following classes of neurone is normally spontaneously active?

• rapidly adapting low threshold mechanoreceptors

• polymodal nociceptors

• slowing adapting low threshold mechanoreceptors

• warm thermoreceptors

• high threshold mechanoreceptors

The axons of the second-order neurones in the thermoreceptive pathway cross the midline at which of the following locations?

• below the central canal of the spinal cord

• in the dorsal columns

• in the ventrolateral funiculus

• in the medulla oblongata

• in the ventrobasal complex of the thalamus

Which of the following classes of neurone have axons that terminate in the thalamus?

1. touch receptors

2. polymodal nociceptors

3. thalamocortical neurones

• 1 only

• 1 & 2 only

• 1, 2 & 3

• 2 only

• none of them

The term that describes the number of neurones that innervate a particular surface area is which of the following?

• innovation density

• receptive field size

• innervation area

• innervation density

• homunculus