ChoiceHub
Sign in

Fasciculus gracilis (medial dorsal column)

First-order neurone / UMN · T6 and below ipsilateral medial

Central processes of dorsal root ganglion neurones from T6 and below (lower limb and lower trunk) enter the dorsal column and ascend on the same side without synapsing, lying medially with sacral fibres innermost. They terminate in the nucleus gracilis of the caudal medulla.

Traced from the start

  1. Cutaneous mechanoreceptors (Meissner, Pacinian, Merkel, Ruffini)Proprioceptors (muscle spindle, Golgi tendon organ, joint receptors)
  2. Fasciculus gracilis (medial dorsal column)

Detail

Input
T6 and below: lower limb and lower trunk
Side
Ipsilateral, uncrossed throughout the cord
Position
Medial dorsal column; sacral fibres most medial
Ends in
Nucleus gracilis, caudal medulla

When it goes wrong

Subacute combined degeneration (vitamin B12 deficiency, nitrous oxide misuse, copper deficiency)

Symmetrical loss of vibration and joint position sense starting in the feet, sensory ataxia with positive Romberg test, combined with UMN signs in the legs but absent ankle jerks from the coexisting neuropathy

Tabes dorsalis (tertiary syphilis; dorsal roots and columns)

Lightning pains, sensory ataxia, absent knee and ankle jerks, Charcot joints and Argyll Robertson pupils

Brown-Sequard hemisection

Ipsilateral loss of vibration and joint position sense below the lesion

Practise this structure

No question in the bank is tagged to Fasciculus gracilis (medial dorsal column) yet. Questions appear here automatically once one is — the question bank is free to browse in the meantime.