Intermediate cervical septum

The intermediate cervical septum is formed by the spinal pia mater, as it invaginates into the posterior intermediate sulcus.

In spinal cord, the region between the posterior median fissure and the site of entry of dorsal (or posterior) nerve root–on either side–is called posterior white column (or posterior funiculus). It contains ascending sensory white matter tracts or fasciculi which transmit the sensory information of vibration, proprioception and two-point discrimination from the peripheral sensory receptors to the thalamus.

The posterior intermediate sulcus is an additional sulcus that is found midway between the posterior median fissure and posterior nerve root. The spinal pia, which closely invests the spinal cord, invaginates into this sulcus to create a septum called the intermediate cervical septum.

Both intermediate cervical septum and posterior intermediate sulcus can only be seen in the cervical and upper thoracic regions of the spinal cord, where they split up the posterior column into two sub-columns, namely the fasciulus gracilis (medially) and fasciulus cuneatus (laterally). The former transmits sensory information from the lower body (T4 and below), while the latter communicates the same sensory information to the thalamus from the upper body (T4 and above). Since, there is no fasciculus cuneatus in the lower dorsal spinal cord, therefore, the intermediate cervical septum and sulcus are also absent in the lower dorsal spinal cord.