Tactile sensory system

Question 1

Describe the stages in the vibrissae system of rats

Answer 1

Neurons from the vibrissae project to the trigeminal ganglion. Trigeminal ganglion neurons then send information to the trigeminal nucleus.
From here, projections go via the brainstem to the VPM of the thalamus and then to the primary sensory cortex

Question 2

Describe the first order neruons in the tactile pathway of humans

Answer 2

First order neurons are the neurons that innervate the cutaneous mechanosensory cells of afferents in the skin. Those from the lower limbs travel in the fasciculus gracilis and those from upper limbs travel in a nerve bundle called the fasciculus cuneatus to the lower medulla

Question 3

Describe the second order neurons in the tactile pathway of humans

Answer 3

Axons travel from the medulla via the medial lemniscus to the VPL of the thalamus

Question 4

Describe the third order neurons in the tactile pathway of humans

Answer 4

Neurons in the VPL of the thalamus send axons to the primary sensory cortex (S1) and S1 sends neurons to S2

Question 5

Describe the pathway of tactile neurons from the face to the brain

Answer 5

Trigeminal ganglion neurons innervate the face and the head. These neurons project to the trigeminal brainstem complex and these neurons project to the VPM.