QS Study

Fasciculus Gracilis and Cuneatus

Fasciculus gracilis and cuneatus are the tracts for conveying fine touch sensation. The fasciculus gracilis contains fibers from spinal cord levels lower than fasciculus cuneatus, and fasciculus gracilis lies medial to fasciculus cuneatus. It is the larger lateral subdivision of the posterior funiculus.

Origin: Tactile receptors are –

  1. Tactile (Messiner’s) corpuscles.
  2. Merkel’s discs.
  3. Free nerve endings around hair follicles.

It contains dorsal root ganglion cell axons transmitting discriminative sensations from the ipsilateral arm, shoulder, and neck.

Fasciculus Gracilis and Cuneatus 1

Fig: Fasciculus Gracilis and Cuneatus – Pathway

Pathway: It is part of the dorsal column-medial lemniscus pathway.

  • Tactile receptors,
  • Sensation passes to the first order neuron to the dorsal root ganglia,
  • Enter the posterior white column of the spinal cord to form fasciculus gracilis and cuneatus,
  • A second-order neuron in nucleus gracilis or nucleus cuneatud,
  • Internal arcuate fibers cross to the opposite side is a sensory decussation,
  • Passes as medial lemniscus,
  • A posterolateral ventral nucleus of the thalamus,
  • Fibers pass through internal capsule and corona radiate,
  • Somatosensory area of cerebral cortex.

Termination: Somatosensory area of the cerebral cortex.

Function:

  • They convey the tactile (fine touch) sensation from a periphery to the sensory area of the cerebral cortex.
  • They also convey a sense of vibration.
  • It transmits fine touch, fine pressure, vibration, and proprioception information from spinal nerves located in dermatomes C1 through T6.
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