Neuronal Pathways of Fine Sensibility

Neuronal Pathways of Fine Sensibility

• The pathway of fine sensibility originates from the contralateral part of the head and is responsible for transmitting information related to touch, discrimination, vibration, and pressure.
• This pathway also involves conscious proprioception, which is the ability to sense the position and movement of body parts.

First-Order Neurons

• The first-order neurons involved in this pathway are located in the trigeminal ganglion (CN V), geniculate ganglion (CN VII), and the superior and inferior ganglia of CN IX and CN X.

Second-Order Neurons

• The second-order neurons are found in the ipsilateral pontine nucleus of CN V.
• The axons of these neurons cross over in the brainstem and continue as the trigeminal lemniscus.

Third-Order Neurons

• The third-order neurons are located in the contralateral ventral posteromedial nucleus of the thalamus.
• The axons of these neurons form the thalamocortical tract, which passes through the internal capsule to the inferior part of the postcentral gyrus (sensory homunculus).
• The postcentral gyrus is organized in a specific way, with different areas responding to different parts of the body, forming the sensory homunculus.