Two of the ascending fibre tracts whose functions are tested in every neurological examination are depicted in Fig. 14.2. All the fibres ascending in the posterior column represent axons belonging to “pseudounipolar” neurons which are located in the spinal root ganglia. This means processes leading to damage of these cells or of their axons running through the dorsal roots result in degeneration of the corresponding fibre bundles. The afferent fibres of ganglion cells form the peripheral somatic nerves. The medial part of the posterior column is named fasciculus gracilis and contains fibres from the lower body, arranged in a somatotopic fashion (Fig. 14.2). The laterally situated fasciculus cuneatus appears above T6 and is prominent in the cervical cord. The fibres of these fascicles, being thick and myelinated, convey conscious position sense, fine touch and vibratory senses.

Other modalities of somatic perception, the senses of pain and temperature, are carried almost exclusively in the lateral spinothalamic tract (Fig. 14.2). Likewise, the peripheral conducting neurons are located in the spinal ganglia. However, their axons branch and connect with neurons of the posterior grey horn, running several segments up and down the spinal cord in the dorsolateral fascicle adjacent to the posterior horn (tract of Lissauer). They synapse with second-order neurons which send axons across the midline, through the anterior commissure, forming the lateral spinothalamic tract. Sensations of pressure and simple or light touch are conveyed in the ventrolateral spinothalamic tract.

The spinocerebellar tracts represent two further ascending pathways (Fig. 14.3), reaching the cerebellum via the inferior and superior cerebellar peduncles. They provide signals of unconscious position sense. This information arrives via the peripheral nervous system and, again, is transmitted via spinal root ganglia cells. However, the axons of the corresponding cells terminate on neurons of the spinal grey matter and the fibres forming the spinocerebellar tracts originate from these second-order neurons (see Chap.​ 16).