Spinal cord
Medulla spinalis
NervousOrgansWhole body
- What it is
- The cable of nervous tissue continuing the medulla from the foramen magnum down the vertebral canal to the conus medullaris at the L1/L2 disc. It is thicker in the cervical enlargement (C4-T1, for the arms) and the lumbar enlargement (T11-L1, for the legs), with an anterior median fissure in front.
- Function
- Carries sensory tracts up and motor tracts down between brain and body, and contains the circuits for spinal reflexes and rhythmic walking patterns; 31 pairs of spinal nerves leave it.
- Size
- About 42-45 cm long; ~1 cm across (1.3-1.4 cm wide at the cervical enlargement); ~35 g
- Clinical note
- Because the cord stops at L1/L2 while the canal continues, lumbar punctures are done at L3/L4 or L4/L5, below the cord, where the needle only meets floating nerve roots.